text:
\section{Introduction}
MESSENGER has provided plenty of valuable information about Mercury's magnetosphere in the last decade, which have improved our understanding of the dynamics in the Mercury's magnetosphere. For examples, observations from MESSENGER have shown that the magnetospheric substorms at Mercury exhibit similar global magnetopheric configurations as the substorms at Earth, but in a time scale of 2 to 3 minutes, which is much shorter than the 2 to 3 hours of Earth's substorm \citep{Slavin:2010,Sun:2015}. MESSENGER has also observed magnetic structures that are closely related to magnetic reconnection, such as the flux transfer events near the magnetopause \citep{Slavin:2009,Slavin:2012b}, flux ropes or dipolarization fronts in the plasma sheet \citep{Slavin:2012,DiBraccio:2015,Sun:2015,Sun:2016}. These structures are similar to those in Earth's magnetosphere. However, at the same time, MESSENGER also found that several features are different from those of Earth. One of the most prominent puzzles raised by MESSENGER observations is the dawn-dusk asymmetry of Mercury's magnetotail.

Analyses of the MESSENGER data show that the energetic electrons or X-ray induced by energetic electrons on the nightside were more frequently observed in the postmidnight region, i.e., the dawnside, than in the premidnight region, i.e., the duskside \citep{Lindsay:2016,Baker:2016, Ho:2016, Dewey:2017}. The dawnward drifting of the electrons may explain the energetic electrons dawn-dusk asymmetry \citep{Lindsay:2016}. However, the study of magnetic reconnection related magnetic structures, which are flux ropes and dipolarization fronts, in the near-Mercury-neutral-line region showed both structures are also more frequently observed on the dawnside than on the duskside, which suggests the magnetic reconnection may prefer to happen on the dawnside and therefore created more energetic electrons in the postmidnight region than in the premidnight region [\citep{Sun:2016} see also, \citep{Sun:2017, Smith:2017}]. The dawnside magnetic reconnection preferentially occurrence in Mercury's plasma sheet is different from the observations in Earth's magnetosphere, where the magnetic reconnection related dynamic processes, such as the flux ropes \citep{Imber:2011} and dipolarization fronts \citep{Liu:2013b}, prefer the duskside plasma sheet. In addition, \citet{Poh:2017b} found Mercury's magnetotail current sheet is thicker on the dawnside than the duskside, and it is believed that it is easier to trigger magnetic reconnection in a thinner current sheet. The relationship between the current sheet thickness and the reconnection products observations still needs to be explored. It has also been observed that there are more heavy ions ($Na^{+}$ and $O^+$) on the duskside plasma sheet than in the dawnside plasma sheet \citep{Raines:2013, Gershman:2014}. The role of the heavy ions in the magnetic reconnection is still largely unknown.

Since the satellite observations usually localize to a small region of the whole magnetosphere at a given time, it is difficult to recover the timing sequence and the global picture of the magnetospheric dynamics from the localized data alone. Numerical models, especially global models, can provide  unique insight into these problems. \citet{Lin:2014}, \citet{Lu:2016} and \citet{Lu:2018} have used a global hybrid model and a local PIC model to study the dawn-dusk asymmetry of Earth's magnetosphere. They found that the Hall effect transports the current sheet plasma and the magnetic flux from the dusk sector to the dawn sector. The transportation reduces duskside current sheet thickness, thus reconnection is easier to be triggered on the duskside. This explanation may work for Earth, but there are some difficulties to adopt it for Mercury. Mercury's current sheet is thinner \citep{Poh:2017b} on the duskside, which is similar to the Earth and might be explained by the Hall effect. However, Mercury's reconnection products prefer the dawn sector. Recently, \citet{Liu:2019} used box PIC simulations to study the magnetic reconnection preference for a thin current sheet that is embedded into a thick current sheet, and they found there is an inactive region on the ion drifting side, and therefore the reconnection prefers the electron drifting side, which might be applicable at Mercury.

A global numerical model of Mercury's magnetosphere is needed to solve these puzzles.
Several numerical models have been used to study Mercury's magnetosphere in the past decades.
BATS-R-US was the first MHD model applied for 3D global simulations of Mercury's
magnetosphere \citep{Kabin:2000, Kabin:2008}. \citet{Jia:2015, Jia:2019} developed
the resistive body capability for BATS-R-US and studied how the induction effect that is arising from the
conducting core affects the magnetospheric global response to the varying solar wind conditions.
Multi-fluid MHD models that treat heavy ions as a separate fluid have been used for Mercury's
magnetosphere simulations \citep{Kidder:2008}. Since the kinetic scales of Mercury's magnetospheric
plasma can be comparable to Mercury's radius, kinetic effects may play an important
role in Mercury's magnetosphere. To incorporate kinetic physics, hybrid
models \citep{Kallio:2003, Wang:2010, Muller:2012, Travnicek:2010},
which treat the electrons as a massless charged fluid and model the ions as particles,
test particle models, which trace the particle trajectories with a global electromagnetic field
obtained from either a global numerical model \citep{Schriver:2011, Seki:2013} or an
analytic model \citep{Delcourt:2003, Delcourt:2013}, and particle-in-cell
models \citep{Schriver:2017} have been applied to study Mercury's magnetosphere.
Due to the limitations of the physics capabilities or the grid resolutions of these models, the
dawn-dusk asymmetries of Mercury's magnetotail have not been studied in detail.

The MHD with embedded PIC (MHD-EPIC) model \citep{Daldorff:2014} makes it feasible
to study Mercury's magnetotail dynamics with a realistic configuration. We use a PIC code
to cover Mercury's inner tail, and the rest of the domain is handled by the MHD model BATS-R-US.
The details of the numerical model are discussed in section~\ref{section:model}.
Section~\ref{section:observation} provides the MESSENGER data that is used to
compare with simulations in the later sections. The simulation results are presented
and discussed in section~\ref{section:results} and section~\ref{section:discussion}.

\section{Numerical model}
\label{section:model}
The MHD-EPIC model has been successfully applied to investigate the interaction between
the Jovian wind and Ganymede's magnetosphere \citep{Toth:2016, Zhou:2019}, Martian magnetotail reconnection \citep{Ma:2018}
and Earth's dayside reconnection \citep{Chen:2017, Toth:2017}. The MHD-EPIC model two-way couples the Hall
MHD model BATS-R-US \citep{Powell:1999, Toth:2008}  and the semi-implicit particle-in-cell code
iPIC3D \citep{Markidis:2010} through the Space Weather Modeling Framework
(SWMF) \citep{Toth:2005swmf, Toth:2012swmf}. Recently, \citet{Chen:2019} has developed the Gauss's Law
satisfying Energy Conserving Semi-Implicit Method (GL-ECSIM), an improved version of the ECSIM \citep{Lapenta:2017a}, and implemented it into
the iPIC3D code. This new PIC algorithm is used for all the MHD-EPIC simulations presented here.

For the MHD-EPIC simulations of Mercury's magnetosphere, we run the fluid code BATS-R-US first
to reach a steady state, then we change to the time-accurate mode \citep{Toth:2012swmf}
and couple the fluid model with the PIC code. Hall-MHD equations are solved by the fluid model for
both MHD-EPIC simulations and pure Hall-MHD simulations. The simulation
setup for both BATS-R-US and PIC are described in the following subsections.

\subsection{Global MHD model: BATS-R-US}
Following the work of \citet{Jia:2015}, a resistive body with finite conductivity layer is
used to represent the interior structure of Mercury: the region within $r<0.8\,R_M$ is the
highly conducting core, and the layer between $0.8\,R_M$ and $1\,R_M$ with finite conductivity
represents the mantle. The conductivity inside the mantle is set to be $\sim 10^{-7}\,S/m$. We refer
to \citet{Jia:2015} for more details about the conductivity profile.

The Hall effect
and the electron pressure gradient term are also included in our generalized Ohm's law:
\begin{equation}
\mathbf{E} = -\mathbf{u}\times \mathbf{B} + \frac{\mathbf{J}\times \mathbf{B}}{q_e n_e}-
\frac{\nabla p_e}{q_e n_e} + \eta \mathbf{J}
\end{equation}\label{eq:Ohm1}
where $q_e$, $n_e$ and $p_e$ are the unsigned electron charge, electron number density (obtained from charge neutrality) and
electron pressure, respectively. $\eta$ represents the resistivity, which is the
inverse of the conductivity and $\mathbf{J}=\nabla\times\mathbf{B}/\mu_0$ is the current density. The electron pressure is calculated from a separate equation:
\begin{equation}
\frac{\partial p_e}{\partial t} + \nabla \cdot (p_e \mathbf{u}_e) = (\gamma -1) (-p_e \nabla \cdot \mathbf{u}_e )
\end{equation}\label{eq:pe}
where $\gamma = 5/3$ is the adiabatic index, and $\mathbf{u_e} = \mathbf{u} - \mathbf{J}/(q_en_e)$
is the electron velocity. In summary, the resistive Hall MHD equations with a separate electron
pressure equation are solved in our MHD model.

Inside the mantle region ($0.8\,R_M<r<1\,R_M$),
there is no plasma flow, but the magnetic field still changes due to the finite conductivity.
Only the reduced Faraday's law is solved inside the mantle:
\begin{equation}
\frac{\partial \mathbf{B}}{\partial t} = -\nabla \times (\eta \mathbf{J}).
\end{equation}
Outside the planet surface,
the whole set of MHD equations are solved. Since both the Hall term and the resistivity term are stiff,
a semi-implicit scheme \citep{Toth:2012swmf} is used to speed up the simulations: the equations
excluding the stiff terms are solved explicitly first, then the stiff terms are solved by an implicit solver.

The simulations are performed in the Mercury solar orbital (MSO) coordinates, where the X-axis is pointing to
the Sun from Mercury, the Z-axis is parallel to Mercury's rotation axis, and the Y-axis completes a
right-handed coordinate system.
The whole simulation domain is a brick of $-64\,R_M<x<8\,R_M$ and $-32\,R_M<y,z<32\,R_M$ cut out from a spherical grid. The center
of Mercury coincides with the origin of the coordinates. A dipole field with strength of $200\,\mathrm{nT}$ \citep{Anderson:2011}
at the magnetic equator is used. The dipole axis is aligned with the Z-axis but the dipole center is shifted
northward by $0.2\,R_M$. A stretched locally refined spherical grid is used. The tail region is refined so
that the cell size is about $0.025\, R_M$ near $x=-2.5\, R_M$. From our simulations, the plasma density in the
lobes is about $0.3\,\mathrm{amu/cm^3}$, and the corresponding proton inertial length is about $360\,\mathrm{km}$
or $0.15\,R_M$. The Hall effect can be well resolved because one inertial length is covered by $\sim 6$ cells.
The inner boundary condition for the magnetic field is applied at the interface of the mantle and the conducting
core, where $r=0.8\,R_M$ and the magnetic field is fixed due to the high conductivity. Since there is no plasma
flow in the mantle, the inner boundary conditions for plasma density, velocity and pressure are applied
on the planet surface $r=1\,R_M$.
A zero gradient boundary condition is applied to plasma density and pressure. The boundary condition for velocity
is designed so that the plasma can be absorbed by the surface, and the surface is not an important source of plasma.
For the inflow, a zero gradient boundary condition is applied to all velocity components. For the outflow, the radial
velocity component is set to be zero at the boundary and a zero gradient boundary condition is applied to the
tangential components. The plasma may flow around or flow into the surface, but it would not have a
significant outflow component.

\subsection{PIC model}
The Gauss's Law satisfying Energy Conserving Semi-Implicit Method (GL-ECSIM) \citep{Chen:2019} is used in the PIC region. MESSENGER observations suggest that the average near-Mercury neutral line (NMNL) is at around $x=-3\,R_M$ \citep{Slavin:2009,Poh:2017a}. To study Mercury's magnetotail reconnection, the tail region $-5.1\,R_M<x<-1.1\,R_M$, $-1.75\,R_M<y<1.75\,R_M$ and $-0.5\,R_M<z<1.5\,R_M$ is covered by the uniform Cartesian mesh of the PIC code (see Figure~\ref{fig:pic_region}(a)). The cell size is $1/32\,R_M$ in all directions. 64 macro-particles per species per cell are used. In order to reduce the computational cost, an artificially reduced proton-electron mass ratio of $m_p/m_e=100$ is set. The cell size is $\sim 1/5 $ of the proton inertial length or twice of the plasma skin depth.  The time step is $2.5\times10^{-3}$ s, the maximum electron thermal speed is about $8\times 10^3$ km/s, and the cell size is $1/32\,R_M$, so that the corresponding CFL number (the ratio of the time step to the cell crossing time by electrons) is about 0.25, which satisfies the `accuracy condition' of the semi-implicit PIC methods \citep{Markidis:2010}.

\begin{figure}
 \includegraphics[width=\textwidth]{comb_global.jpg}
 \caption{(a) The global structure of Mercury's magnetosphere at $t = 300\,s$ from the simulation MHD-EPIC-A.
 The mass density in the equatorial plane and the magnetic field lines of two flux ropes are shown.
 The red box is the region covered by the PIC code. It covers the whole tail region where magnetic
 reconnection may happen. In the Y-direction, the PIC region is close to but has not reached the
 magnetopause. (b) The Hall magnetic field $B_y$ and magnetic field lines at $y=0$. (c) The $B_z$ component along the red line in (b).
 }
 \label{fig:pic_region}
 \end{figure}

 \section{MESSENGER observations in the nightside plasma sheet}
 \label{section:observation}
 This section provides observations of the proton properties and dipolarization fronts in Mercury's nightside plasma sheet from MESSENGER \citep{Solomon:2007}. The proton measurements are provided by the Fast Imaging Plasma Spectrometer (FIPS) \citep{Andrews:2007} and the magnetic field measurements are provided by the magnetometer \citep{Anderson:2007}. FIPS could measure ions in an effective field of view of $\sim 1.15 \pi$~sr with an energy range from $\sim 46$ eV/e to $\sim 13.7$ keV/e with a time resolution of $\sim 10$~s. The magnetic field data are provided with a time resolution of 20 vectors per second and are under Mercury solar magnetospheric coordinates (MSM). In the MSM, the $X_{MSM}$ is sunward, the $Z_{MSM}$ is northward and parallel to the dipole axis, and the $Y_{MSM}$ completes the right-handed system. The MSM coordinates and MSO coordinates are parallel with each other, but the MSO origin is the center of Mercury and the MSM origin centers
 on the Mercury dipole. The spacecraft position data are provided to be in the same time resolution as the magnetic field measurements, but they are aberrated according to the solar wind velocity and Mercury's orbital motion to make the $X'_{MSM}$ antiparallel to the solar wind. The aberration changes the positions in the $X_{MSM}-Y_{MSM}$ plane, but does not change $Z_{MSM}$.

 \begin{figure}
 \includegraphics[width=1\textwidth, trim=0cm 6cm 0cm 6cm]{observation_plasma.eps}
 \caption{The MESSENGER observed proton density (left) and proton pressure (right) around the magnetic equator ($|Z_{MSM}| < 0.2 R_{M}$). This figure shows the one minute proton moments derived from FIPS during the entire MESSENGER orbits around the Mercury (from 17 March 2011 to 30 April 2015). The black curve on both figures is the average location of the magnetopause \citep{Winslow:2013}. The number of events in each bin is required to be larger than 3. The size of bin is $0.2 \ R_{M} \times 0.2 \ R_{M}$. The colors indicate the intensity of density (left) and pressure (right), respectively.}
 \label{fig:observation_plasma}
 \end{figure}

 \subsection{Proton properties}
 Proton density and pressure shown in Figure~\ref{fig:observation_plasma} were derived from one minute average distributions of protons under the assumption that they are isotropic and stationary Maxwellian distributions \citep{Raines:2011, Raines:2013,Gershman:2013}. The proton moments derived from this method were applied in several studies on the plasma sheet dynamics \citep{Raines:2011,Gershman:2014,Sun:2017,Sun:2018,Poh:2018}. The proton density distribution (left figure in Figure~\ref{fig:observation_plasma}) shows clear dawn-dusk asymmetry with proton densities higher on the dawnside ($\sim 6$ to 8~amu/cc) than on the duskside ($\sim 2$ to 4~amu/cc). The dawn-dusk asymmetry of proton pressure (right figure in Figure~\ref{fig:observation_plasma}) is not that prominent as proton density. The proton pressure shows weak dawn-dusk asymmetry in the downtail region $(X'_{MSM} < - 1.3 \ R_{M})$ with proton pressure on the dawnside plasma sheet slightly higher than on the duskside. This dawn-dusk asymmetry becomes more prominent in the near tail region with ($X'_{MSM} \sim - 1 \ R_{M}$), where proton pressure was from 1.3 to 1.7~nPa on the dawnside plasma sheet and was from 0.6 to 1.3~nPa on the duskside plasma sheet.

 \citet{Korth:2014} showed the distribution of mean proton flux in the nightside plasma sheet of Mercury. In that study, the mean proton flux showed clear dawn-dusk asymmetry with the flux much higher on the dawnside than on the duskside, which is similar to the distribution of proton density in Figure~\ref{fig:observation_plasma}.

  \begin{figure}
 \includegraphics[width=1\textwidth, trim=0cm 6cm 0cm 6cm]{observation_df.eps}
 \caption{The spatial distribution of the dipolarization fronts observed by MESSENGER around the magnetic equator ($|Z_{MSM}| < 0.2 R_{M}$). The size of bin is $0.3 \ R_{M} \times 0.3 \ R_{M}$. The color indicates the number of dipolarization fronts in each bin. The number of dipolarization fronts in each bin is required to be at least 3.}
 \label{fig:observation_df}
 \end{figure}

 \subsection{Dipolarization fronts}
 Dipolarization front, also called reconnection front, is defined as the leading edge of planetward travelling plasma flow burst, which is highly correlated with the magnetic reconnection [e.g., \citep{Angelopoulos:2013}]. In previous studies at Mercury, \citet{Sun:2016} has shown clear dawn-dusk asymmetry of dipolarization fronts in the near-Mercury-neutral-line region with more dipolarization fronts on the dawnside plasma sheet than on the duskside plasma sheet. The following studies on the dipolarization fronts in the near-Mercury plasma sheet, proton energization and heating, energetic electrons and proton bulk flows have shown the similar dawn-dusk asymmetries \citep{Sun:2017,Dewey:2017,Dewey:2018}.

 Figure~\ref{fig:observation_df} shows the distribution of dipolarization fronts in Mercury's nightside plasma sheet. This figure contains the dipolarization fronts during the entire period MESSENGER orbited around Mercury. The dipolarization fronts were obtained according to the similar procedure as \citet{Sun:2016}. Since the dipolarization fronts were constrained in the regions with $Z_{MSM} < 0.2 \ R_{M}$ and MESSENGER orbits were evenly distributed in the dawn-dusk direction \citep{Sun:2016}, the occurrence rate of dipolarization fronts shows essentially the same structures as Figure~\ref{fig:observation_df}. In the downtail region $(X'_{MSM} < - 2 \ R_{M})$, the dipolarization fronts show dawn-dusk asymmetry with more events on the dawnside plasma sheet than on the duskside, which is similar to \citep{Sun:2016}. The dawn-dusk asymmetry becomes more prominent in the region closer to the planet (from $-2 \ R_{M}$ to $-1 \ R_{M}$).

\section{Simulation results}
\label{section:results}
We perform pure Hall-MHD and MHD-EPIC simulations with different upstream solar wind conditions.
In order to avoid introducing dawn-dusk asymmetries from the solar wind, the Y-components of
the IMF and the solar wind velocity are eliminated in all simulations. Since the Y-component
of the velocity is zero, there is not need to apply aberration to the simulation results.
The detailed solar wind parameters are shown
in Table~\ref{tb:sw}. Compared to the parameters used by \citet{Jia:2015}, we use a proton
and electron temperature of 7.5~eV, which is half of the proton temperature of \citet{Jia:2015}.
Since the total pressure of the solar wind is split between electrons and protons in this paper,
the total plasma thermal pressure is still the same as \citet{Jia:2015}. The strength of the IMF in both
MHD-EPIC-A/Hall-A and MHD-EPIC-B/Hall-B is $|\mathbf{B}|=19.4$ nT, which are also the same as \citet{Jia:2015}.
The plasma parameters for MHD-EPIC-A/Hall-A is typical at Mercury's ambient space environment.
The IMF configuration of MHD-EPIC-A/Hall-A is similar to a typical Parker spiral magnetic field,
except that the $B_y$ component is set to be zero and a negative $B_z$ component is
introduced to drive Mercury's magnetosphere. The IMF of MHD-EPIC-B/Hall-B purely consists of a
negative $B_z$ component with larger magnitude, which is a stronger driver than that of
MHD-EPIC-A/Hall-A. We run the MHD code first to reach a steady state, then we run the
time-accurate MHD-EPIC or Hall-MHD for 300~s, which is about 2 to 3 Dungey cycles of Mercury's
magnetosphere \citep{Slavin:2009}. It usually takes a numerical
model a few Dungey cycles to settle down to a steady or quasi-steady state.

In the following subsections, we introduce the global picture of the simulation results first.
Then the dawn-dusk asymmetry is discussed based on the simulations. We will briefly compare
the MHD-EPIC simulations with the pure Hall-MHD simulations as well.

\begin{table}[ht]
\caption{The solar wind parameters in MSO coordinates.}
\centering
\begin{tabular}{c c c c c c }
\hline
 Simulation ID    & $\rho$ [amu/cc] & Temperature [eV]  & Velocity km/s  & IMF\,[nT] \\
\hline
MHD-EPIC-A/Hall-A    & 40         & 7.5                 &  (-400, 0, 0)  & (-17.4, 0, -8.5)   \\
MHD-EPIC-B/Hall-B    & 40         & 7.5                 &  (-400, 0, 0)  & (0, 0, -19.4)   \\
\hline
\label{tb:sw}
\end{tabular}
\end{table}

\subsection{Global picture}
The global structure of Mercury's magnetosphere at $t = 300\,s$ from the simulation MHD-EPIC-A
is shown in Figure~\ref{fig:pic_region}. The equatorial plane is colored by the plasma mass density.
It happens to have two flux ropes at this moment. By checking the time series of
the simulation results, it is easy to figure out that the flux rope far from the planet
is moving tailward, and the one near Mercury is moving planetward. These flux ropes
are produced by the PIC code, which covers most parts of the inner magnetotail. In the
Y-direction, the PIC region is close to but has not reached the magnetopause.
Figure~\ref{fig:pic_region} shows a typical state of the MHD-EPIC-A simulation.
Magnetic reconnection happens around $x = -2.5\,R_M$, and produces tailward and planetward moving
flux ropes.

A 2D cut at y = 0 is presented in Figure~\ref{fig:pic_region}(b) to show more details of
these two flux ropes. The bipolar $B_y$ field is
the remnants of the reconnection Hall magnetic field. There is no significant core field for
either flux ropes at this moment due to the lack of IMF $B_y$, which may act as
core field seed during the formation of a flux rope. Compared to a typical flux rope with a strong
core field, these two flux ropes presented here are more like collections of O-lines. The tailward
flux rope is about $1\,R_M$ long in the Y-direction, and the planetward one is about $0.5\,R_M$ long.
The flux rope diameter measured by the $B_z$ field peak-to-peak distance in the X-direction is about
$0.3\,R_M$ (730 km) for the tailward one and $0.15\,R_M$ (360 km) for the planetward one (Figure~\ref{fig:pic_region}(c)). \cite{DiBraccio:2015} estimates the mean flux rope diameter to be
$0.14\,R_M$ (345 km) by using the Alfven speed of 465~km/s times the time delay between
MESSENGER detecting the two $B_z$ peaks. Our simulations suggest the typical ion jet velocity
is about 1000~km/s (Figure~\ref{fig:cs_ux}). The mean diameter of the MESSENGER observed flux ropes
will be about $0.3\,R_M$ if 1000~km/s instead of 465~km/s is used in the estimation. In any case,
the diameters of the two flux ropes in Figure~\ref{fig:pic_region} are similar to the MESSENGER observations.
Across the flux ropes, $B_z$ changes from 10~nT to -10~nT for the tailward one and from 20~nT to
-15~nT for the planetward one. These $B_z$ peak-to-peak amplitudes are close to the average of MESSENGER
observation value of 20~nT \citep{DiBraccio:2015}. Inside the flux rope, the proton density is about
1.5~amu/cc in the simulation, while the median observed density is 2.03~amu/cc \citep{DiBraccio:2015}.

The agreement of the flux rope properties between the MHD-EPIC-A simulation and MESSENGER observations
demonstrates that our mode behaves reasonably well in capturing Mercury's magnetotail reconnection.
In the following subsections, we will examine the dawn-dusk asymmetries of Mercury's tail.

\subsection{Tail current sheet thickness and plasma profile}

\begin{figure}
 \includegraphics[width=1.0\textwidth, trim=0cm 0cm 0cm 0cm]{comb_cs.jpg}
 \caption{The time-averaged current sheet thickness of MHD-EPIC simulations.
 (a) and (c) correspond to the MHD-EPIC-A and MHD-EPIC-B runs, respectively.
 (b) and (d) are the thickness at $x=-2\,R_M$, which is marked by the red dashed lines in (a) and (c).}
 \label{fig:cs}
 \end{figure}

 \begin{figure}
 \includegraphics[width=1.0\textwidth, trim=0cm 0cm 0cm 0cm]{comb_cs_hall.jpg}
 \caption{The current sheet thickness of Hall-A ((a) and (b)) and Hall-B ((c) and (d)) simulations.
 (b) and (d) are plots of current sheet thickness at $x=-2\,R_M$.}
 \label{fig:cs_hall}
 \end{figure}

  \begin{figure}
 \includegraphics[width=1.0\textwidth, trim=0cm 0cm 0cm 0cm]{MD_current.eps}
 \caption{The 300-second average current sheet structure of MHD-EPIC-A at $x=-2\,R_M$.
 (a), (b) and (c) are the electron current, proton current and total current in the
 Y-direction, respectively. (d) is the electron velocity in the Y-direction. It
 can be as fast as -4,000 km/s, and we make the color saturated at -1,000 km/s to
 show more structures. (e) is the proton velocity in the Y-direction. (f) is the
 electron pressure.}
 \label{fig:current}
 \end{figure}

\citet{Poh:2017b} calculated the current sheet thickness from hundreds of MESSENGER crossings, and they found
the current sheet is thinner on the duskside (+Y) than the dawnside (-Y) on average.
Using the same fitting method described by \citet{Poh:2017b}, we calculate the
current sheet thickness from our simulations. The $B_x$ field along the Z-axis
is fitted to a one-dimensional Harris current sheet model:
\begin{equation}
B_x (z) = B_0 \tanh \left(\frac{z - z_0}{L} \right).
\end{equation}\label{eq:cs}
The fitted current sheet thickness is 2L.
The fitting is done every 2\,s, and its average over 300\,s is shown in Figure~\ref{fig:cs}.

Figure~\ref{fig:cs}(a) shows that the center of the thin current sheet of MHD-EPIC-A
is shifted to the dusk (+Y) direction. The proton density of the thin current sheet
around $x=-2\,R_M$ is about 0.4 amu/cc, and it can be as low as 0.02 amu/cc in the ambient lobe. The
proton inertial length $d_i$ of a density of 0.4 amu/cc is $0.15\,R_M$, which is the same order as
the current sheet thickness in Figure~\ref{fig:cs}. A cut of thickness at $x=-2\,R_M$
is presented in Figure~\ref{fig:cs}(b). It is clear to see that the current sheet is thicker
on the dawnside (-Y) than the duskside (+Y), which is consistent with the profile obtained
from MESSENGER data. Figure 4(b) of \citet{Poh:2017b} shows the current sheet thickness from
hundreds of current sheet crossings. For this MESSENGER plot, the corresponding solar wind conditions
are unknown and may vary a lot, and it contains current sheet crossings from $x=-3.0\,R_M$ to $x=-1.1\,R_M$,
so the thickness may vary from $0.1\,R_M$ to $1\,R_M$ even for the same Y coordinate.
But the mean current sheet thickness is probably able to represent the status under a typical
solar wind condition. In the observation plot, the thinnest average current sheet is
about $0.3\,R_M$, and it increases to about $0.7\,R_M$ on the dawnside and $0.5\,R_M$ on the duskside.
Since $x=-2\,R_M$ is roughly the middle point of the MESSENGER crossings distribution in the
X-direction, we plot the current sheet thickness at $x=-2\,R_M$ in Figure~\ref{fig:cs}(b).
The current sheet can be as thin as $0.2\,R_M$, and it increases to $0.8\,R_M$
at $y=-1.5\,R_M$ and $0.3\,R_M$ at $y=1.5\,R_M$. The MHD-EPIC-A simulation
current sheet is slightly thinner than the observations around
midnight and in the dusk sector. Considering the large variance in the MESSENGER
data (Figure 4(b) of \citet{Poh:2017b}), the simulation agrees with observations very well.

The current sheet thickness for MHD-EPIC-B, which is driven by $B_z=-19.4$~nT IMF, is presented in
Figure~\ref{fig:cs}(c) and (d). The current sheet that is far away from the midnight becomes
thinner than in the MHD-EPIC-A simulation, because the stronger dayside magnetic reconnection transports
more magnetic flux to the tail to produce higher magnetic pressure. The thickness becomes less
asymmetric than MHD-EPIC-A, even though the dawnside current sheet is still slightly thicker
than the duskside. The bump near the midnight is probably
produced by the thick current sheet of the reconnection exhaust.

We repeat the same analysis of the current sheet thickness for the two Hall-MHD
simulations using the same input parameters as those in the MHD-EPIC simulations.
The results are shown in Figure~\ref{fig:cs_hall} for comparison. The current sheet
thickness at X = -2 $R_M$ in the Hall MHD simulations is significantly larger
compared to the MHD-EPIC simulation results and the MESSENGER observations. It can
be seen that the current sheet thickness is not symmetric around midnight in the
Hall-MHD simulations, either, and the thinnest part of the tail current sheet is
displaced towards dusk (+Y), which is similar to that seen in the MHD-EPIC simulations.
These results together suggest that the asymmetry is likely to be related to the Hall effect.

The cross-tail current density of MHD-EPIC-A at $x=-2\,R_M$ is presented in
Figure~\ref{fig:current}. The duskside (+Y) electron current density is larger
than the dawnside (-Y), but the proton current density is larger on the dawnside (-Y).
The maximum current density of $j_y \approx 200\,$nA/m$^2$ arises around midnight,
and it reduces to less than $100\,$nA/m$^2$ on the two flanks. The thin current sheet
extends farther in the dusk sector (+Y) than the dawn sector. The spatial variation of
the total current density $j_y$ presented here is consistent with MESSENGER observations
(Figure~4(c) of \citet{Poh:2017b}).

Figures~\ref{fig:cs_av_epic_a} to \ref{fig:cs_av_hall} show the time-averaged profiles of
various plasma properties on the current sheet surface for MHD-EPIC-A, MHD-EPIC-B
and Hall-A, respectively. The plots of Hall-B are not shown, because they are
not significant difference than Hall-A in terms of the properties we discussed below.
The current sheet surface is defined as the surface
where $B_x$ changes sign, and its projection into the X-Y plane is shown in
the figures. All three simulations show significant dawn-dusk asymmetries
of plasma density, electron pressure and total pressure. In the inner magnetotail,
at a radial distance of $\sim 1.5\,R_M$ from the center of Mercury, the dawnside (-Y) plasma
density (6~amu/cc for MHD-EPIC-B, and 10~amu/cc for MHD-EPIC-A/Hall-A) is
about twice of the duskside (+Y) density (3~amu/cc for MHD-EPIC-B, 5~amu/cc for
MHD-EPIC-A, and 7~amu/cc for Hall-A). Both the density values and the dawn-dusk ratio are
close to the  MESSENGER observation (Figure~\ref{fig:observation_plasma}).
By studying Earth's magnetotail, \citet{Lin:2014} and \citet{Lu:2016} found
that there is more plasma in the dawn sector of Earth's magnetotail due to
the $\mathbf{E} \times \mathbf{B}$ drift caused by the
Hall electric field. Since the Hall effect is the only reason to produce
dawn-dusk asymmetry in the Hall-A simulation, Hall effect must be the
reason to create higher dawnside plasma density in Hall-A as well as
the MHD-EPIC simulations. The MESSENGER data indicates slight proton pressure
enhancement on the dawnside (Figure~\ref{fig:observation_plasma}(b)), but our simulations
do not show any significant preference of the proton pressure. The simulated electron
pressure and hence the total pressure are higher on the dawnside (-Y). Eq.~(\ref{eq:pe})
is the electron pressure equation solved by the Hall-MHD model, and its right-hand side,
the compression term, can produce the dawnside pressure enhancement. Because the $u_{e,z}$
component is small and the $u_{e,x}$ component changes slowly in the X-direction, the
$\frac{\partial u_{e,y}}{\partial y}$ term must contributes most to the compression
$\nabla \cdot \mathbf{u}_e$. From Figure~\ref{fig:current}(d), we can see the
electron velocity reduces shapely from a few thousand to less than 500~km/s
near $y=0.5\,R_M$. The braking of $u_{e,y}$ is consistent with the dawnside electron
pressure enhancement. The amplitude of the proton velocity $u_{p,y}$ is much smaller
than $u_{e,y}$, and so is the proton compression $\nabla \cdot \mathbf{u}_i$.
This may explain why there is no significant proton pressure asymmetry. Larger dawnside (-Y)
electron pressure and total pressure are also consistent with thicker dawnside (-Y)
current sheet thickness.

 \begin{figure}
 \includegraphics[width=1.0\textwidth, trim=0cm 0cm 0cm 0cm]{comb_cs_av_epic_a.jpg}
 \caption{The time-averaged plasma profiles from the PIC output on the current sheet surface for MHD-EPIC-A: proton density (a), total pressure (b), proton pressure (c) and electron pressure (d).}
 \label{fig:cs_av_epic_a}
 \end{figure}

  \begin{figure}
 \includegraphics[width=1.0\textwidth, trim=0cm 0cm 0cm 0cm]{comb_cs_av_epic_b.jpg}
 \caption{The time-averaged plasma profiles from the PIC outputs on the current sheet surface for MHD-EPIC-B.}
 \label{fig:cs_av_epic_b}
 \end{figure}

  \begin{figure}
 \includegraphics[width=1.0\textwidth, trim=0cm 0cm 0cm 0cm]{comb_cs_av_hall_a.jpg}
 \caption{The time-averaged plasma profiles on the current sheet surface for Hall-A: proton density (a), total pressure (b), proton pressure (c) and electron pressure (d). The electron pressure
 presented here is calculated by a separate electron pressure equation in our MHD model.}
 \label{fig:cs_av_hall}
 \end{figure}

\subsection{Magnetic reconnection}
We discuss the asymmetries that are directly related to the magnetotail reconnection in
this section. The average proton reconnection jets on the current sheet surface are shown in Figure~\ref{fig:cs_ux}
for all simulations. In the MHD-EPIC simulations, there is no significant dawn-dusk asymmetry of
the tailward jets. But it is clear that the planetward proton jets prefer the dawnside (-Y).
In the Hall-A simulation, the reconnection jets center around $y=0.5\,R_M$, which is consistent with
the thin current sheet location (Figure~\ref{fig:cs_hall}). The Hall-B simulation does not show any
significant dawn-dusk asymmetry of either tailward or planetward jets.

The evolution of the proton jet $u_{p,x}$, electron jet $u_{e,x}$ and magnetic field $B_z$ in the
current sheet center at $x=-2.9\,R_M$, $x=-2.3\,R_M$ and $x=-1.6\,R_M$ (the vertical
lines in Figure~\ref{fig:cs_ux}(a)) are shown in Figure~\ref{fig:time_epic_a}.
$x=-2.9\,R_M$ and $x=-1.6\,R_M$ are in the tailward and planetward outflow regions, respectively.
$x=-2.3\,R_M$ is close to the X-lines so that the jets can be either tailward or planetward.
If we ignore the first 50~s of the simulation, which corresponds to the transition period of
starting MHD-EPIC from a steady-sate Hall MHD configuration, the reconnection sites and the tailward jets
shift to the dusk side slightly. For example, it is more frequent to observe electron jets
for $y\in [0,0.5]R_M$ than $y\in [-0.5,0]R_M$ at $x=-2.3\,R_M$. However, on the planet side of
the X-line, both the high-speed plasma jets $u_{p,x}$ and $u_{e,x}$, and the enhanced $B_z$ shift
to the dawnside. At $x=-1.6\,R_M$, there are neither proton nor electron
jets found in the region $y>0$.

The reconnection products with a strong IMF driver (MHD-EPIC-B) are presented in
Figure~\ref{fig:time_epic_b}. For this case, not only the planetward jets ($x=-1.6\,R_M$), but also
the tailward jets ($x=-2.3\,R_M$) and the reconnection sites ($x=-2.0\,R_M$) shift to the
dawnside. For example, it is not unusual to see either proton jet $u_{p,x}$ or electron jet $u_{e,x}$
between $y=-0.5\,R_M$ and $y=-1.0\,R_M$ at $x=-2.3\,R_M$ and $x=-2.0\,R_M$, but it is rarer to
have high-speed jets between $y=0.5\,R_M$ and $y=1.0\,R_M$ at the same X-coordinate.

The simulated spatial distributions of the plasma jets and enhanced $B_z$ in the inner tail
are consistent with MESSENGER observations. Figure~2 of \citet{Poh:2017b} shows that the
dawnside $B_z$ field is stronger than the duskside, and the $B_z$ field peaks at $y=-0.2\,R_M$.
Our MHD-EPIC-A and MHD-EPIC-B simulations also show a peak value of $B_z \sim 30$~nT between
$y=0\,R_M$ and $y=-0.5\,R_M$ at $x=-1.6\,R_M$, and the dawnside $B_z$ is larger than the dusk side as well.
\citet{Dewey:2017} found the energetic electron injections concentrate in the dawn sector, and the peak
fraction of the dipolarization associated events occurs at LT $\sim$ 1-2, which corresponds
to $y \sim$ 0.4-0.9 for $x=-1.6\,R_M$. Our simulation results are consistent with the MESSENGER energetic particle observations. The simulation high-speed electron jets
prefer to occur between $y=0\,R_M$ and $y=-0.5\,R_M$ at $x=-1.6\,R_M$.

The MHD-EPIC simulations suggest that the closer to Mercury, the stronger the dawn-dusk
asymmetries of the reconnection products are. Observational evidences for this pattern
may already exist in the publications. \citet{Smith:2017} used an automated method to identify flux
ropes, and they observed a weak dawn-dusk asymmetry with $58\%$ of flux ropes observed in the dawn
sector. Most of the flux ropes lie between 1.5 and 2.5 $R_M$ down the tail. This statistical result
suggests that the dawn-dusk asymmetry between $x=-1.5\,R_M$ and $x=-2.5\,R_M$ is not very strong.
But the energetic electron spatial distribution by \citet{Dewey:2017} shows that almost all injections
are observed in the midnight-to-dawn sector. Even though these two papers discussed different phenomena, both
phenomena are likely the products of magnetic reconnection. In order to further confirm this hypothesis,
we plot the spatial distribution of the dipolarization fronts observed by MESSENGER
in Figure~\ref{fig:observation_df}, which shows strong dawn-dusk asymmetry, and there is
a trend that the asymmetry is stronger in the region closer to Mercury.
Figure~\ref{fig:df} shows the evolution of a dipolarization event, which is characterized by
$B_z$ enhancement, from the MHD-EPIC-A simulation. The structure of enhanced $B_z$ is circled
by the red ovals on the plots. The dipolarization initially appears at $x\sim -2.3\,R_M$, and
the majority of the structure
is in the dusk sector. The enhanced $B_z$ structure moves dawnward when it is moving towards
Mercury. The electron flow streamlines are over-plotted above $B_z$. It is clear that
the electrons move in the same direction as the dipolarization front. The dawnward velocity
component of electrons is a natural consequence of the cross-tail current. If we assume that
part of the dawnward moving electrons are frozen into the magnetic field lines, the motion
of the dipolarization front can be explained as well. The protons around the dipolarization front
are moving duskward in the current sheet (see the proton streamlines in Figure~\ref{fig:df}).
However, the high-speed proton jet still prefers the dawnside in our simulations, which is consistent with
MESSENGER observations \citep{Sun:2017}. The difference between the proton
motion direction and the high-speed jet preferential direction suggests that the fast proton
flows observed far away from the reconnection sites are not direct products of the magnetic
reconnection itself. Instead, these fast protons may be accelerated by the dipolarization
fronts \citep{Zhou:2010}.

In order to demonstrate the importance of including the kinetic effects into the model, we compare
the MHD-EPIC simulations with pure Hall-MHD simulations. Figure~\ref{fig:time_hall_b}
shows the evolution of plasma jets and $B_z$ for Hall-B simulation. This simulation does not show
any significant dawn-dusk asymmetry and the results are quite different from those of the MHD-EPIC-B run.

 \begin{figure}
 \includegraphics[width=1.0\textwidth, trim=0cm 0cm 0cm 0cm]{comb_cs_av_ux.jpg}
 \caption{The time-averaged
 X-component of the proton velocity on the current sheet surface for the four
 simulations. The horizontal
 dashed lines are at $y=-1, -0.5, 0, +0.5$ and $+1\,R_M$, respectively.
 The location of the vertical black lines change from plot to plot. The time evolution along these
 vertical lines are shown in the following figures. The color range is saturated at 1000 km/s and -1000 km/s.}
 \label{fig:cs_ux}
 \end{figure}

  \begin{figure}
 \includegraphics[width=1.0\textwidth, trim=0cm 0cm 0cm 0cm]{MD_cs_uix.jpg}
 \caption{The evolution of different quantities on the current sheet surface at $x=-2.9\,R_M$, $x=-2.3\,R_M$
 and $x=-1.6\,R_M$ (see the three vertical lines in Figure~\ref{fig:cs_ux}(a)) for the MHD-EPIC-A simulation.
 The time serials of
 the x-component of the proton velocity $u_{p,x}$, the x-component of the electron velocity $u_{e,x}$, and the $B_z$
 magnetic field from the beginning of the simulation to the end are displayed.}
 \label{fig:time_epic_a}
 \end{figure}

  \begin{figure}
 \includegraphics[width=1.0\textwidth, trim=0cm 0cm 0cm 0cm]{SD_cs_uix.jpg}
 \caption{The same quantities as Figure~\ref{fig:time_epic_a} for the MHD-EPIC-B simulation at
 $x=-2.3\,R_M$, $x=-2.0\,R_M$ and $x=-1.6\,R_M$ (see the three vertical lines in Figure~\ref{fig:cs_ux}(b)). }
 \label{fig:time_epic_b}
 \end{figure}

 \begin{figure}
 \includegraphics[width=1.0\textwidth, trim=0cm 0cm 0cm 0cm]{Hall_SD_cs_uix.jpg}
 \caption{The evolution of the proton velocity $u_{p,x}$ and magnetic field $B_z$ at
 $x=-2.9\,R_M$, $x=-2.3\,R_M$ and $x=-1.6\,R_M$ (see the three vertical lines in Figure~\ref{fig:cs_ux}(d))
 of the current sheet of the Hall-B simulation.  }
 \label{fig:time_hall_b}
 \end{figure}

  \begin{figure}
 \includegraphics[width=1\textwidth, trim=0cm 0cm 0cm 0cm]{comb_df.jpg}
 \caption{The $B_z$ magnetic field and proton velocity $u_{p,x}$ on the current sheet surface at different times.
 The electron streamlines (the white lines) are overplotted on the $B_z$ plots. The red ovals indicate the
 location of enhanced $B_z$.}
 \label{fig:df}
 \end{figure}

\section{Discussion}
\label{section:discussion}
  \begin{figure}
 \includegraphics[width=0.9\textwidth, trim=0cm 0cm 0cm 0cm]{cartoon.jpg}
 \caption{A cartoon illustrating the influence of the current sheet asymmetry and reconnection
 inactive region on the reconnection asymmetry for moderate and strong IMF driving conditions. The magnetic reconnection occurs in the region indicated with MR.}
 \label{fig:cartoon}
 \end{figure}

In the MHD-EPIC-A simulation, the IMF driver of $B_z=-8.5$\,nT is moderate. The
driver of MHD-EPIC-B is strong. These simulations suggest that Mercury's
magnetotail reconnection sites slightly shift to the duskside (Figure~\ref{fig:time_epic_a})
when the dawnside current sheet is significantly thicker than the duskside
(Figure~\ref{fig:cs}(a) and (b)) under a moderate IMF driver (MHD-EPIC-A), and the
reconnection sites shift to the dawnside (Figure~\ref{fig:time_epic_b}) when the
dawnside current sheet is almost as thin as the duskside (Figure~\ref{fig:cs}(c)
and (d)) under a strong driver (MHD-EPIC-B). The results of MHD-EPIC-B simulation are consistent
with what \citet{Liu:2019} found in 3D box PIC simulations. They found that
there is a reconnection `inactive' region on the ion drifting side (the
duskside in our simulations) of a thin current sheet, so that the magnetic reconnection prefers
the electron-drifting side. Under a moderate driver, the majority of the thin current sheet
lies on the duskside. For such current sheet configuration, even though part of the duskside
current sheet is inactive, most of the reconnection sites may still be on the duskside,
just as in the MHD-EPIC-A simulation. Since part of the duskside current sheet is inactive, the
duskside preference of the reconnection should be weaker than the thin current sheet.
We think this may be the reason why the MHD-EPIC-A simulation
shows strong current sheet thickness asymmetry, but the reconnection preference is not significant.
When the IMF driver is strong, such as in the case of MHD-EPIC-B, the current sheet is thin enough to allow
magnetic reconnection to occur in almost the whole magnetotail current sheet, so that the dawn-dusk
asymmetry of the current sheet thickness has little influence on the magnetic reconnection, and the
inactive region \citep{Liu:2019} on the duskside determines the dawn-dusk asymmetry of the reconnection sites.
Figure~\ref{fig:cartoon} displays the relative importance of the current sheet asymmetry
and the reconnection inactive region.
Besides the dawnside preference introduced by the `inactive' region, we find that
the planetward moving electron jets and the dipolarization fronts are also shifted dawnward. The dawnward
motion  makes it rare to observe high-speed planetward plasma jets and dipolarization events in the dusk sector.

We now turn to the first 50 s of the MHD-EPIC simulations. Since it corresponds to the transition
from the steady-state Hall-MHD to MHD-EPIC, the results of the first 50 s may not represent a typical
state of Mercury's magnetotail. But it still provides interesting insights into Mercury's magnetotail
reconnection. At the very beginning, MHD-EPIC inherits the current sheet structure from the steady-state
Hall-MHD results. The Hall effect of the steady-state Hall-MHD exists, but it is weak
due to the large numerical diffusion. The current sheet thickness between $y=-1.0\,R_M$
and $y=1.0\,R_M$ is less than $0.2\,R_M$ and is approximately symmetric. The X-lines estimated from
the tailward jets (Figure~\ref{fig:time_epic_a} and Figure~\ref{fig:cs_av_epic_b}) are more
than $1\,R_M$ wide in the cross-tail direction initially. As soon as the MHD-EPIC simulation starts, the duskside X-lines start to shrink (solid red lines in Figure~\ref{fig:time_epic_a} and Figure~\ref{fig:cs_av_epic_b}),
so that almost all the reconnection sites are in the dawn sector at t = 30 s. The shrinkage
of the X-lines may be related to the reconnection inactive region discussed by \citet{Liu:2019}.

The MESSENGER observations of current sheet thickness \citep{Poh:2017b}, flux ropes,
dipolarization events \citep{Sun:2016, Sun:2017, Smith:2017} and energetic electron
events \citep{Dewey:2017} do not and cannot distinguish the events under different
IMF conditions. For the current sheet thickness observation, the
current sheet sampling is almost uniform in time. If the moderate IMF condition dominates
throughout the period during which the MESSENGER observations were obtained, the
asymmetric current sheet (like MHD-EPIC-A) will contribute most sampling data
points in the statistics. However, strong IMF driving is likely to produce magnetotail
reconnection products more frequently. Even if the moderate IMF condition occurs
more frequently, it is still possible that most observed reconnection related events
are produced by strong IMF drivers.

Our model assumes all the ions are protons.  The heavy ions, such as sodium, have not been incorporated
into the simulations. The model does not produce Kelvin-Helmholtz instability (KHI) on
either side of the magnetopause. But our MHD-EPIC simulations still manifest the dawn-dusk asymmetries
that are comparable with observations, which suggests that neither heavy ions nor KHI are necessary for the
reconnection related dawn-dusk asymmetries, even though they may still play an important role. We have
tried to incorporate sodium into our MHD model by using multispecies MHD, and therefore the sodium will
also be treated as a separate ion species inside the PIC region \citep{Ma:2018}. The sodium ions
enter the simulation domain from the MHD inner boundary. To be
specific, we set the sodium mass density to be $70\%$ of the total mass density in the inner
boundary ghost cells. This mass density matches a number density of $\sim 10\%$, which is the heavy ion
abundance in the plasma sheet observe by MESSENGER \citep{Gershman:2014}. The  boundary condition
does not introduce any dawn-dusk asymmetry by itself. This preliminary simulation shows the duskside
sodium density is indeed higher than the dawnside in the current sheet (Figure~\ref{fig:na}), which is
consistent with MESSENGER observations. This simulation does not show any significant difference
compared to the one with single ion species. Our current inner boundary condition relies
on numerical diffusion to get sodium into the simulation domain from Mercury's surface and
the sodium density inside the current sheet  is still lower than observed by MESSENGER
 \citep{Gershman:2014}, so we cannot draw any conclusion about the role of
heavy ions so far. We will explore the role of heavy ions with an improved model in the future.

The MHD-EPIC-B simulation demonstrates that magnetic reconnection prefers the dawnside, and both MHD-EPIC-A
and MHD-EPIC-B show the planetward high-speed plasma flows and dipolarization events move toward the dawnside.
But it is still rare to see tailward jets beyond $y=-1.0\,R_M$ or to see planetward jets beyond  $y=-0.5\,R_M$. MESSENGER
observed many such events far away from the midnight direction, such as the dipolarization fronts in
Figure~\ref{fig:observation_df} and statistics from other papers \citep{Sun:2016, Smith:2017, Dewey:2017}.
This discrepancy may be simply caused by the varying IMF in the observations. It can also be introduced by
the physics that is not in our model, such as a proper heavy ion profile.

Both the MHD-EPIC and pure Hall-MHD simulations presented in this study show that the duskside current
sheet is thinner than the dawnside, but the thickness obtained from Hall-MHD is significantly larger
than that of MESSENGER observations and MHD-EPIC simulations. Magnetic reconnection of Hall-A
simulation shifts to the duskside significantly. There isn't any significant dawn-dusk asymmetry
in the Hall-B simulation. In general, Hall-MHD simulations do not appear to match observations
very well in terms of dawn-dusk asymmetries of magnetic reconnection.

  \begin{figure}
 \includegraphics[width=\textwidth]{na.eps}
 \caption{The proton and sodium density on the current sheet surface for multispecies-MHD-EPIC.}
 \label{fig:na}
 \end{figure}

\section{Summary}
We use the MHD-EPIC model to study dawn-dusk asymmetries of Mercury's magnetotail. The simulation results,
such as the current sheet thickness, plasma density asymmetry, and reconnection asymmetry, agree with MESSENGER
observations. The key simulation results are:
\begin{itemize}
\item The dawnside plasma density and electron pressure are higher than the duskside. The proton pressure
does not exhibit significant dawn-dusk asymmetry in the simulations.
\item The dawnside current sheet is thicker than the duskside.
\item When the IMF driver is moderate, for example, $B_z = -8.5\,nT$, the current sheet
thickness asymmetry is strong, and
the magnetotail X-lines may shift to the duskside. When the IMF driver is strong, for
example, $B_z=-19.4\,nT$, the current sheet thickness asymmetry is not significant, and the
magnetotail reconnection prefers the dawnside.
\item  The dipolarization events and the planetward high-speed plasma flows, including both
proton flows and electron flows, concentrate in the dawn sector.
\item The preliminary multispecies-MHD-EPIC simulation produces higher duskside sodium density
in the current sheet but does not change the asymmetry of the reconnection significantly.
\end{itemize}

\acknowledgments
This work was supported by the INSPIRE NSF grant PHY-1513379, the NSF
PREEVENTS grant 1663800, the Impacts of Extreme Space Weather Events
on Power Grid Infrastructure project funded by the U.S. Department of
Energy (DE-AC52-06NA25396) through the Los Alamos National Laboratory
Directed Research and Development program, the NASA Living With a Star program
grant NNX16AJ67G and the NASA's Solar SystemWorkings program grant NNX15AH28G.
Computational resources supporting this work were
provided on the Blue Waters super computer by the NSF PRAC grant ACI-1640510,
on the Pleiades computer by NASA High-End Computing (HEC) Program through
the NASA Advanced Supercomputing (NAS) Division at Ames Research Center,
and from Cheyenne (doi:10.5065/D6RX99HX) provided by NCAR's Computational and
Information Systems Laboratory, sponsored by the National Science Foundation.

MESSENGER data used in this study were available from the Planetary Data
System (PDS): http://pds.jpl.nasa.gov. The MESSENGER project is supported by
the NASA Discovery Program under contracts NASW-00002 to the Carnegie
Institution of Washington and NAS5-97271 to The Johns Hopkins University
Applied Physics Laboratory.

The SWMF code (including BATS-R-US and iPIC3D) is publicly available through the
csem.engin.umich.edu/tools/swmf web site after registration.
The output of the simulations presented in this paper can be obtained
by contacting the first author Yuxi Chen.

\clearpage

redpajama_set_name: RedPajamaArXiv


text:
Anthony Sampieri pleads guilty to kidnapping, raping 7yo in Kogarah dance studio toilet
By Jamie McKinnell
Updated June 13, 2019 13:45:45
Photo: Anthony Sampieri will be sentenced on June 21. (ABC News)
A convicted sex offender has pleaded guilty to kidnapping and raping a young girl at a dance studio in Sydney's south while on parole.
Anthony Sampieri pleaded guilty to 10 of the 15 charges against him and the prosecution dropped the remaining five
He raped and choked a seven-year-old girl in a locked toilet cubicle at a dance studio in Kogarah
A man had to bash the cubicle door down to rescue the girl and was stabbed by Sampieri
Anthony Sampieri, 55, was arrested after he attacked and choked the seven-year-old girl in a locked toilet cubicle at the Kogarah studio in November last year.
He was also accused of filming the incident.
He appeared via video link in Sydney's Central Local Court and pleaded guilty to 10 of the 15 charges against him, including sexual intercourse with a child, choking, indecent assault and wounding.
The prosecution withdrew the remaining five charges.
Magistrate Robert Williams adjourned the matter for sentence in the District Court on June 21.
At the time of the rape, the father of another child bashed down the toilet cubicle door and was stabbed several times by Sampieri.
Photo: Police said Anthony Sampieri had no links to the dance studio. (ABC News)
A dentist working in the same building then restrained Sampieri until police arrived.
The seven-year-old girl and the attacker were not known to one another.
Police have praised the father for intervening and said he began looking for the girl after she could not be accounted for.
Sampieri is also facing nearly 30 charges laid over allegations he made dozens of obscene phone calls to women in the lead-up to the incident.
He was on parole at the time and a police officer who interviewed him one month before faces allegations he neglected his duties.
The case of Senior Constable Andrew Bruce, 31, was mentioned in the Downing Centre Court last week and his lawyer said it had been "a troubling time for the officer and his family".
NSW Police Commissioner Mick Fuller has previously said Sampieri would have been behind bars had he been charged over the phone calls while on parole.
Senior Constable Bruce's case returns to court in August.
First posted June 13, 2019 11:50:09

redpajama_set_name: RedPajamaCommonCrawl


If a particular peer is consistently being reported by other peer nodes as being the cause of replication errors, you can temporarily put the peer in manual detention. Once the root problem has been resolved, remove the peer from manual detention. See Put a peer into detention.
This condition can occur after you convert a single-site cluster to multisite. If you configure the cluster as multisite from the very beginning, before you first start it up, the issue does not occur.
The 'failingGuid' key value pair is not going to be found in the 10th position from the grep/cut command that is shared under the "Evidence of replication failure on the source peer" section.


The rebound daemon proxies and caches DNS requests. It listens by default on localhost and forwards queries to another server.
If sent a SIGUSR1 signal, rebound logs statistics to /var/log/daemon.
Specify an alternative configuration file, instead of the default /etc/resolv.conf. rebound will reload the configuration file when sent a SIGHUP signal or when the file changes. The nameserver option is used to indicate the next server to contact. Localhost entries will be skipped, allowing the same file to be shared with libc. Minimal static records may also be specified as "record A name IP".
Debug mode. rebound does not fork(2) into the background.
Listen for connections by binding to address, an IP specified in dotted quad notation, instead of the default of localhost.
The rebound daemon first appeared in OpenBSD 5.9.


The joint operating agreement ("JOA") is the most commonly used instrument in the oil and gas industry, surpassed only by the oil and gas lease.  A JOA provides the contractual basis for the cooperative exploration, development, and production of oil and gas properties among multiple leasehold cotenants.  By and large, the most commonly used JOA form is the "Form 610," curated and published by the American Association of Professional Landmen ("AAPL").  Several other JOA forms have been adopted by the oil and gas industry, typically designed for use in specific circumstances, including (1) the Model Form of Offshore Operating Agreement AAPL Model Form 710-2002, and Model Form of Offshore Deepwater Operating Agreement AAPL-810 (2007), both designed for offshore oil and gas operations, (2) the Rocky Mountain Mineral Law Foundation Rocky Mountain Unit Operating Agreement Form 2 – Divided Interest, designed for use in Federal Exploratory Units, and The American Petroleum Institute Forms, which are generally used for enhanced recovery operations as to fieldwide units. However, the AAPL Model Form 610 remains the most common JOA form for domestic onshore oil and gas production.


Web hosting is an invaluable tool for commercial and personal use. Hosts allow you to use their servers to host your website (s). The web hosting provider can also provide tools and utilities to help you keep your site operational and interactive. However, finding a good web hosting company is not an easy task as there are many non-professional hosting companies on the market. Do not worry. In this article, there are tops five ways on the best places to find the best web hosting company in 2018.
The Internet is a powerful tool that can be used to find web hosting companies. Almost all web hosting companies have their websites. Then try typing "web hosting" into a search engine, and you will get a list of different web hosting companies. Also, you can also find detailed information on various companies on the Internet and compare them. Online you will find the MangoMatter's WordPress hosting page and other different professional web hosting services, web hosting companies' offer. Browse through to see if they suit your needs. , and some unethical companies can provide false information. Therefore, you have to be very careful if you want to use the internet to find a hosting services company.
Using a web hosting directory can help you find a professional web hosting provider quickly and easily. A web hosting directory is a list of web hosting companies. Its purpose is to allow people to search for hosting providers much more easily. A web hosting directory also includes the hosting services provided by each company. You can see the services they offer, compare different companies and find the best web hosting company. Also, some websites also offer online directory hosting services.
You can also visit some forums related to web hosting to find professional hosting providers. Discussions are the best places to communicate with others and get the information you want. You can ask other people about the hosting providers you have chosen. Sometimes they will give you good suggestions. Word of mouth is a bet when a customer has used the services of the web hosting provider. Each person can tell you whether or not you should avoid that particular host. Also, when browsing the forums, note the participation of web hosts. Pay attention to how they respond to each member. Why do not you ask difficult questions? Try the waters a bit.
Another sure way to find a good host is to consult your friends or business partners. They may recommend some web hosting services companies and these companies are well chosen for you. You can collaborate with these reliable web hosting companies without worries.
Yes, finding a particular web hosting service provider to host your site can be daunting. It is possible that thousands of companies operate on the Web. How do you know which one is right for you? A typical review site allows you to see at a glance the leading web hosting service providers and a summary of their features, such as bandwidth, disk space, availability, price, satisfied customer, etc. etc. At the same time, it also provides you with the link to the web server so you can make a virtual tour of the company if you wish.
It is therefore essential to find the right web hosting company to host your site. As you probably know, choosing a web hosting provider is critical to the success of your business. If you want your online business to be profitable, you need to select a web hosting company that can make your site visible on the Web almost all the time.


When the kingdom's most wanted – and most charming – bandit Flynn Rider (Zachary Levi) hides out in a mysterious tower, he's taken hostage by Rapunzel (Mandy Moore), a beautiful and feisty tower-bound teen with seventy feet of magical, golden hair. Flynn's curious captor, who's looking for her ticket out of the tower where she has been locked away for years, strikes a deal with the handsome thief and the unlikely duo set off on an action-packed escapade, complete with a super-cop horse, an over-protective chameleon and a gruff gang of pub thugs. Also starring Ron Perlman as the Stabbington Brother, Jeffrey Tambor as Big Nose Thug, M.C. Gainey as Captain of the Guard, and Richard Kiel as Vlad.


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Though a shining contemporary example of China's economic power, Beijing's charm lies in the remnants of its storied past.
If you get the chance, wander down some of the quieter hutongs, which reveal a glimpse of the old Beijing residences that really capture the charm of the city's past.
A sense of power can be felt in most parts of Beijing, from its lofty airport halls upon arrival to its formidable skyscrapers when you reach the city centre. Visitors may notice that many of the major historical attractions on the typical must-see list share the same grandeur, harking back to imperial times. While these places are effective in conveying the metropolis' sense of might, some of the more obscure spots leave the most enduring impression.
Situated in one of Beijing's most prestigious addresses, China World Summit Wing, Beijing encapsulates the pinnacle of modern luxury. Whether you indulge in a heavenly aroma vitality massage at CHI, The Spa, the highest of its kind in the city, or go for a dip in the indoor infinity pool which plays music underwater, everything is just a bit more special at soaring heights.
Breakfast will never be the same again after you have devoured waffles at Grill 79, gazing through floor-to-ceiling windows at panoramas that span further than the eye can see. Meanwhile, on the 80th floor, Atmosphere provides an unparalleled cityscape and some of the city's most innovative cocktails.
The rooftops of The Forbidden City can also be seen from the hotel. While the 72-hectare palace is iconic for good reason, some of the less obvious surrounds are just as worthwhile. Located directly behind is Jingshan Park, offering one of the best views of the palace if you climb to the top of one of Beijing's few hills. Philip Marlowe, journalist and Beijing resident says, "Aside from offering a verdant oasis, it's also a popular spot for the older generation who gather to sing, play traditional instruments and practice tai chi in the morning."
When it comes to serene settings, few are more idyllic than the Summer Palace, where Empress Dowager Cixi retired until her death in 1908. Its majestic grounds, arched stone bridges and exquisitely landscaped gardens bordered by Kunming Lake could easily have been the inspiration behind any traditional watercolour painting. Commissioned by Emperor Qianlong in 1750 as royal retreat for his mother's 60th birthday, the exclusive domain represented the height of opulence at the time.
Experience more stately treasures with a stroll around the adjoining lakes in the Shichahai area, which used to be part of the Emperor's gardens. Houhai, in particular, buzzes with cafes and restaurants in the evenings. However, if you get the chance, wander down some of the quieter hutongs, which reveal a glimpse of the old Beijing residences that really capture the charm of the city's past.
Another hutong worth visiting is Dongcheng District's funky Nanluoguxiang, a buzzing alley filled with trendy boutiques selling everything from kitsch trinkets to vintage typewriters amongst a sea of courtyard breweries, gig venues, galleries and dinky eateries. Foodies can eat their way through the 800-metre-long lane, which is filled with tempting local treats like crepes, doughnuts and ice cream.
Capital Delights
Walk off the indulgence with a little retail therapy on Wangfujing Street, which has been a hub of commercial activity since the Ming Dynasty. Aristocratic estates and princess' residences were also built in the district during the Qing Dynasty, but today it is home to a buzzing combination of 280 international and Beijing-born brands. Among the most unique are the Shengxifu Hat Shop, established in 1911, and Yong Zheng Tailors Shop, specialising in tailor-made suits.
A trip to Beijing would be incomplete without feasting on Peking duck. While it is hard to go wrong with the ubiquitous bird served everywhere, Duck de Chine serves the unctuous roasted duck and accompanying pancakes, plum sauce, spring onion and cucumber in the most glamorous of settings. The meat is flavourful and the skin is delightfully crisp without being fatty in the slightest.
The perfect end to the day involves putting your feet up, literally, with a touch of reflexology. A popular way to unwind in Beijing, the extravagant pastime dates as far back as the Shang Dynasty, when King Zhou Wenwang enjoyed podiatry complete with knives, hands and scratching boards. The contemporary experience is decidedly more calming and equally fit for royalty. Sit back, relax and enjoy…
Make a booking at China World Summit Wing, Beijing
Back to Destination
Stephen: 4 years, 11 months ago
The quiet Hutongs is where you will dig up old memory and treasures. Wondering down some of them and see. Hutongs are also the place you will find some forgotten famous places to dine and enjoy.


With a classic bar silhouette, the Leanor Gunmetal Pendant Necklace in Black Drusy is a sure to become your new staple. This stunning pendant necklace is a statement that's simple enough for the everyday but can also be dressed up for a night out. Add some sparkle to your wardrobe with our Leanor Gunmetal Bar Pendant Necklace.


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A Ritual to Read to Each Other … Generously
By Megan Willome 5 Comments
Every December I reread Charles Dickens' A Christmas Carol. And every year I think I've found all there is to find. Until I find something new.
In Stave II, when Ebeneezer Scrooge visits the school of his past and encounters himself as a lonely boy, comforted only by reading, something extraordinary happens — more extraordinary than three ghosts.
Suddenly a man, in foreign garments, wonderfully real and distinct to look at, stood outside the window, with an ax stuck in his belt, and leading by the brindle an ass laden with wood.
'Why, it's Ali Baba!' Scrooge exclaimed in ecstasy, 'It's dear old honest Ali Baba! Yes, yes I know! One Christmas time, when yonder solitary child was left here all alone, he did come, for the first time, just like that. Poor boy!'"
As in the character from "Ali Baba and the Forty Thieves" one of Scheherazade's tales from Arabian Nights, or The Thousand and One Nights. A storybook person, come in the flesh.
But wait! There's more from a French fairytale.
'And Valentine,' said Scrooge, ' and his wild brother Orson; there they go!'"
And more tales from Scheherazade.
'And what's his name, who was put down in his drawers, asleep, at the Gate of Damascus; don't you see him?'
'And the Sultan's Groom turned upside down by the Genii; there he is upon his head! Serve him right! I'm glad of it. What business had he to be married to the Princess?'"
And back to England and Daniel Defoe's Robinson Crusoe.
'There's the Parrot!' cried Scrooge. 'Green body and yellow tail, with a thing like a lettuce growing out of the top of his head; there he is! Poor Robin Crusoe, he called him when he came home again, after sailing round the island. Poor Robin Crusoe, where have you been, Robin Crusoe? The man thought he was dreaming, but he wasn't. It was the Parrot, you know.'"
Do you see what happened? Scrooge's favorite characters actually came to life while he read when he was a boy. And so when he goes back to Christmas past, those characters are as real as his old classmates.
This is why we read. To have characters speak to us. To have their images as clear in our minds as our loved ones. This might be called reading generously.
Over 2020, our monthly reading roundup has been guided by a search for wisdom. Poet William Stafford has been our guide with A Ritual to Read to Each Other. Even though the poem talks about an elephant parade, it has a way of being the light in the darkness around us. It gives clarity.
But clarity and wisdom sometimes only get us so far. We can know what to do and still not want to do it. How do we keep from becoming a "A squeezing, wrenching, grasping, scraping, clutching, covetous, old sinner" like Ebeneezer Scrooge? How do we get from that mizer to a man who says, "I am as light as a feather, I am as happy as an angel, I am as merry as a schoolboy. I am as giddy as a drunken man"?
Read generously.
Tweetspeak Poetry's 2021 theme is Generous, and this column will become Reading Generously. We'll spend the next twelve months exploring what that means.
Part of what that means for me is rereading books like A Christmas Carol. It's a way to admit I haven't absorbed all the book has to offer. Ali Baba was always there, but I never noticed him until now, probably because a book podcast I love is reading those thousand and one stories. Each year as a reread this story I get to watch Scrooge come alive. He became generous with others because he first became generous with himself — the lonely little boy who found friends in books:
Some people laughed to see the alteration in him, but he let them laugh, and little heeded them, […] His own heart laughed, and that was quite enough for him."
November's Pages
A Child's Garden of Verses, Robert Louis Stevenson (his poetry came up in both Peace Like a River, read last month, and The Magician's Book, this month)
Picture Books and Early Readers
Girl Versus Squirrel, Haley Barrett, illus. Renee Andriani
One Morning in Maine, Robert McClosky
All the World, Liz Garton Scanlon, illus. Marla Frazee (Re-read after taking an online class with the author)
Middle Grade and YA
The Boy, the Boat, and the Beast, Samantha M. Clark (Writers' League of Texas recently did an online workshop with her)
Dry, by Neal Shusterman and Jarrod Shusterman (a climate change thriller)
Northanger Abbey, Jane Austen (in which Catherine discovers she is in a Jane Austen novel, not Jane Eyre)
Little Black Sheep: A Memoir, Ashley Cleveland
A Christmas Carol, Charles Dickens
Transcendent Kingdom, Yaa Gyasi
The Magician's Book: A Skeptic's Adventures in Narnia, Laura Miller
Made Progress
How We Fight for Our Lives: A Memoir, Saeed Jones (also a poet!)
For Discussion
1. Have you ever actually read A Christmas Carol? If not, make it your December resolution. Then watch the Muppet version and be amazed how much they got right.
2. What fictional characters seemed real to you as a child? Or as an adult? (This is a judgment-free zone.)
3. Share your November pages. Sliced, started, and abandoned are all fair game.
Photo by Jonathan Kos-Read, Creative Commons, via Flickr. Post by Megan Willome.
Browse more from A Ritual to Read to Each Other
"Megan Willome's The Joy of Poetry is not a long book, but it took me longer to read than I expected, because I kept stopping to savor poems and passages, to make note of books mentioned, and to compare Willome's journey into poetry to my own. The book is many things. An unpretentious, funny, and poignant memoir. A defense of poetry, a response to literature that has touched her life, and a manual on how to write poetry. It's also the story of a daughter who loses her mother to cancer. The author links these things into a narrative much like that of a novel. I loved this book. As soon as I finished, I began reading it again."
—David Lee Garrison, author of Playing Bach in the D. C. Metro
Buy The Joy of Poetry Now
Megan Willome
Megan Willome is a writer, editor, and author of The Joy of Poetry: How to Keep, Save & Make Your Life With Poems and Rainbow Crow: poems in and out of form. Her day is incomplete without poetry, tea, and a walk in the dark.
Latest posts by Megan Willome (see all)
Perspective: The Two, The Only: Calvin and Hobbes - December 16, 2022
Children's Book Club: A Very Haunted Christmas - December 9, 2022
By Heart: 'The night is darkening round me' by Emily Brontë - December 2, 2022
Filed Under: A Ritual to Read to Each Other, A Story in Every Soul, book reviews
About Megan Willome
Glynn says
I've read "A Christmas Carol" about eight times, and I think you've convinced me to read it again this year. And I love the Muppets version. Many people watch / re-watch "It's a Wonderful Life" at Christmas Time; I watch "Scrooge," with Albert Finney. And yes, I sing along with all the musical's songs.
Read in November:
The Adventure of the Beryl Anarchists by Craig Stephen Copeland
The Hope That Kills by Ed James
Where Every Man by Charlie Garratt
Small Town, Next Lover, and The Wrong House to Burgle by Glenn McGoldrick
Prove It: Murder in the Mix by Hannah Kurz
Interviewing the Dead by David Field
Should Grace Fail by Priscilla Paton
Miz Scarlet and the Holiday Houseguests by Sara Barton
The Magnificent Dappled Sea by David Biro
A Baby's Right to Choose by David Winters
Poetry:
Wonder & Wrath by A.M. Juster
Hearts on Pilgrimage by Jody Lee Crosby
Mania by Arran James Grant
Spirits in Bondage: A Cycle of Lyrics by C.S. Lewis
A Spring Harvest by Geoffrey Bache Smith
The Mystery of Charles Dickens by A.N. Wilson
How to Think Like Shakespeare by Scott Newstok
Love Me Timeless by Melissa Crosby
Hoping for Hawthorne by Tara Grace Ericson
Megan Willome says
Glynn, how was the Charles Dickens book?
It was ok, Megan. I'm not a big fan of psycho-biography, and that's a lot of what this one is.
Oh, you've inspired me, Megan!
I love your choice for the new reading column. And I love the first deep observation, via Scrooge's character: "He became generous with others because he first became generous with himself." That is some line to unpack. After all, being generous with oneself is far different from being selfish, yet the two might be hard to discern as different from one another on the surface.
Now I am thinking, too, that the girls and I should take your challenge. This year has been so very hard on too many levels to count, including having to face Christmas for the first time without grandma. So I'm looking for things to focus on, to craft at least some kind of ritual to get us through and deepen our sense of life and living, despite the challenges of the year.
First Christmases without a loved one are hard and do require new rituals.
We all need a little generosity with ourselves after this year.


Dive the City of Salisbury with East Coast Divers and Boston Scuba!
Load time is at 7:30am. Please plan accordingly as we will depart at 8am sharp!
The City of Salisbury (also known as the Zoo Ship) sank on April 22, 1938 with over $2,000,000 worth of cargo, much of which was exotic animals. On its trek to New York, the City of Salisbury was planning a stop in Boston Harbor when suddenly a thick fog settled in. The ship suddenly rammed an uncharted rock pinnacle on the outer edge of Graves ledge and eventually was split in half. The Salisbury took several days to sink. All passengers and animals aboard were saved.
The dive site begins at 20 feet and descends to 90 feet. While the wreck itself has been a victim of time, the bones of the Salisbury are still visible.


Tuition fees are charged for one academic year, irrespective of school vacations or broken periods of attendance. Fee (including tuition and other monthly heads) is charged on monthly basis (except for summer vacations).
A one-time Registration and Admission fee (non-refundable under any circumstance) will be paid by all new students in full at the time of admission. Security Fee is payable at the time of admission and is refundable at the time of withdrawal. All School fees, including School Supply charges for the academic year, will be paid as per fee schedule prior to admission. Charges for Student ID card, School Magazine, Sports, and Library (or others), if being charged, are annual charges and shall also be paid in full as per the school's fee schedule. Other school charges or optional extras shall be paid as per school notifications as and when they fall due.
All students, parents and guardians are required to follow the rules and regulations as outlined in the School Policy regarding Tuition and Fees.


Growing up in Canada, it was inevitable that I would embrace outdoor activities in all seasons, however, in the dead of those long winter months, when frigid temperatures prevented any sort of outdoor fun, I immersed myself in another childhood passion, playing dress up. As the years went on and I was in my teens, I became fascinated by fashion magazines, spending hours perusing cover to cover and wondering "what if that were me" modeling the beautiful clothes, or even being the latest "cover girl"? Growing up as a painfully shy child, always doing my best to please others and avoid conflict in a tense family environment, the hours spent dreaming of a glamourous modeling life was a wonderful way to escape to another world.
A very excited 6 year old flower girl in a deep green velvet gown.
As often happens, my life took a more conventional path. I attended college, with the aspiration to eventually attend law school and practice as an attorney, but I was steered towards a teaching degree and a respectable, stable career in the footsteps of my mother. By the age of 23 I found myself married, teaching elementary school and the mother of a baby boy. I embraced motherhood and loved my little boy.
My marriage was toxic from the beginning. My husband was an alcoholic and our relationship was a sad saga of emotional abuse, infidelity and degrading comments about my body and looks. This all wounded me deeply, since for years, I suffered from low self-esteem and anxiety. My marriage exacerbated issues that were a result of a chaotic family life and a self-imposed sense of perfection during my childhood. I grew more self-conscious, resentful and full of shame for not being enough.
Seven years after the birth of my son, a beautiful baby girl came into my world and I hoped she would fill the void of love in my marriage. It was a high-risk pregnancy and the miracle birth of my daughter gave me great joy, gratitude, and inspired me to do more with my life. This experience rekindled the desire to pursue a career in modeling. Filled with excitement, I drove a hundred miles to a casting call and, to my surprise, I received a call back. Slowly but surely, self-limiting beliefs of doubt began to creep in. Fear and anxiety took hold and I did not follow through. The excuses were plentiful; it was too far away, my spouse and family were not supportive, it was risky to leave my stable teaching job, the kids were too little, and on and on.
With my dream put back on hold, I continued teaching and going through the daily motions of life. As I had always done, I built up a facade of being productive and happy in my life, while underneath I was crumbling. All the while, the pull was still there, in the back of my mind, that there was more.
My parents raised their children to be tough and we were expected to do well and see things through. However, there were conflicting messages which led to the very self-limiting thoughts, "Don't think too highly of yourself. Know your place. Who do you think you are?" Further complicating my life was my relationship with food and body image. For decades I struggled with food issues, from fad diets to bulimia, and excessive exercising.
The death of my father capped a period of mounting sadness in my life. To deal with it all, I began working with a counselor. I gained the strength needed to end my marriage and to eliminate other toxic people and relationships from my life. Slowly, my family adjusted to the fact that I was leaving my marriage. I had the support of my children before I had the support of other family members. While I found the strength and courage to set a new course, I had not dealt fully with my eating disorder.
A dreamy job on the beach in Malibu.
Once I began to get my life back in order, I found a new love. I met my second husband on an online chat room and we maintained a remarkable long-distance relationship for seven years before we married. There was a magnetic pull that neither of us could deny even though I was in Canada and he was in Texas. He waited for me while I finished raising my daughter through high school and tending to my ailing mother. His unconditional love for me never wavered. Just before our marriage, my husband relocated to Los Angeles. I packed up my belongings, retired from teaching and set out to start a new life in LA with my daughter and new husband.
While I was eager to get started doing things in my free time in LA, a city where there was so much opportunity, I was stuck with no direction. I muddled through, but I still didn't feel complete. Missing the daily interaction with students, I decided to go back to teaching.
Season's Greetings in holiday red.
Suddenly, and unexpectedly, my sister passed away which left me in a state of shock. She did not get the chance to grow old, to retire from nursing, to spend more time with her beloved grandchildren. I still had that privilege and I set out to discover how best to honor it.
Fortuitously and timely, I read a book called, The Goddess Revolution, written by UK author, Mel Wells. The book focuses on forgiveness to abusing and shaming your body, ditching diets or fads, learning to eat and exercise intuitively in a healthy balanced manner. My daughter (who had food issues since childhood) and I enrolled in Mel's online academy and worked through the course together.
I also enrolled in Mel's new course, The Sisterhood, comprised of a small group of women from around the globe, skyping in to discuss life on a more spiritual level. This course dug deep in to my inner self which led me to open up to the true passion burning within me, to truly identify what I really wanted to do. I needed to empower and embrace who I wanted to be. Through a great deal of journaling, self-reflection and tears, something magical began to happen. I began to give myself permission to live a bigger life, to step into who I was meant to be. I began to understand my self-worth and confirmed that what I had always wanted to pursue was modeling and, if I was to pursue it, it needed to be now. I was finally confident and comfortable in my body size and shape, and as a mid-life model, I didn't need to be a size 0.
Representing an empowering women's brand of tee shirts.
At the age of 57, I finally realized a lifelong dream and launched a new career as a model, signing with an agent. I've broadened my horizons by taking acting lessons. So, I guess you could say I am officially a model and an actress! I've been very busy auditioning and booking all sorts of interesting jobs. Walking into that first audition was one of the scariest things I have ever done. The auditions are not easy, but I look to them as a source of excitement and fun. I feel that I'm finally living an authentic life, doing what feels right in my heart and soul.
Both of my children offer a great deal of support, always wanting to know what I'm up to, what auditions I've been to, what jobs I've booked. My daughter has calmed my nerves, communicates with me daily, and always has something nice and supportive to say. My husband, remains a pillar of unconditional love and support, is my biggest cheerleader, best friend, and partner in crime. I am blessed to have this wonderful family. I feel vibrant and young at heart yet privileged to have a wealth of new life experiences giving me perspective and wisdom.
← Career Transformation from Nurse to Goat Farmer!
Congratulations! It's not easy getting out there but so worth it!
What a great article! I'll definitely check out The Sisterhood. And I guarantee you a role in the Singing in Silence movie.
Thank you so very much for the feature! Empowered women empower women!! Grit and Soul is setting the bar!!
What a great article! I have had the privilege of watching Barbara grow and realize her dream. I have seen and felt her power rise as she changed her life and influenced the lives of others with her amazing spirit. You cant help but love her! She lifts my spirit each day! This life chapter is so much fun and I am very lucky indeed to be in it with her! Way to go Barbie, your big guy loves you!!


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Black Slaves, Indian Masters: Slavery, Emancipation, and Citizenship in the Native American South, by Barbara Krauthamer (2013)
by Nakia Parker
For decades, scholars peered at the painful and complex topic of American slavery through a purely "black-white" lens—in other words, black slaves who had white masters. The sad reality that some Native Americans, (in particular, the Creek, Cherokee, Choctaw, Chickasaw, and Seminole, or "the Five Tribes") also participated in chattel and race-based slavery, was rarely acknowledged in the historical annals. Only in the latter part of the 20th century did historians begin to address this oversight. Several groundbreaking studies recognized the momentous repercussions of this practice for Native and African American populations alike during the antebellum era and down to the present day. Barbara Krauthamer, a professor of Native American and African American history at the University of Massachusetts, Amherst, adds an exhaustive and compelling contribution to the research in this area. The first full-length monograph chronicling chattel slavery in the Choctaw and Chickasaw Nations, Krauthamer amply demonstrates how both before and after the era of Indian Removal in the mid-nineteenth century slavery also intersected with issues of race and gender in complicated ways.
Krauthamer tracks white commodification and enslavement of Choctaw and Chickasaw bodies starting in the late seventeenth century and its transition to the commodification and enslavement of black bodies by Choctaw and Chickasaw slaveholders in the eighteenth century. In addition, Krauthamer adroitly debunks the myth that the main cause for American Indian participation in chattel slavery stemmed from their desire for European, and later American goods, unable to resist the inescapable forces of the market economy and capitalism. Krauthamer acknowledges the catastrophic economic consequences of the American seizure of Indian lands, of the racist rhetoric that Native Americans needed to be properly "civilized," and of the exigencies caused by depletion of the deer population, which severely curtailed trade opportunities. But she persuasively argues that the decision to engage in chattel slaveholding resulted from a conscious and deliberate choice on the part of Indian slaveholders to embrace racial ideology that "degraded blackness and associated it exclusively with enslavement." For some influential and wealthy members of the Choctaw and Chickasaw Nations, adopting race-based slavery provided the most efficient way to maintain an increasingly tenuous hold on political and cultural autonomy in the face of aggressive American expansion, while pursuing self-interested economic and diplomatic goals.
Holmes Colbert, a prominent leader in the Chickasaw Nation and the owner of several enslaved African-Americans (Wikimedia Commons)
Krauthamer also addresses the "leniency thesis" that many early scholars of Native American history advocated — that life under the yoke of an Indian master was somehow more "benevolent" than enslaved life under whites — but that has been successfully challenged, by Tiya Miles and Claudio Saunt among others. By the mid-nineteenth century, laws existed in both nations that banned intermarriage between blacks and Indians: for example, Choctaw lawmakers allowed white men to achieve citizenship through marriage to a Choctaw woman, but forbade "a negro or descendent of a negro" from enjoying the same privilege; likewise, in the Chickasaw nation, the punishment for "publicly taking up with a negro slave" was a steep fine, whipping, or the ultimate punishment, banishment from the nation and the dissolving of all kinship ties. Krauthamer also cites accounts from WPA slave narratives detailing instances of physical and sexual abuse at the hands of Native American owners.
Chickasaw Freedmen filing for allotment in Oklahoma (Oklahoma Historical Society)
Krauthamer also shows that despite horrific conditions, enslaved people living in "Indian country" engaged in covert and overt forms of resistance. One particularly compelling experience of slave resistance concerns the story of Prince, who, angered that his Choctaw owner Richard Harkins failed to give his slaves a Christmas celebration, brutally murdered him and then unceremoniously dumped the body into the river in 1858. Prince finally confessed, but implicated his Aunt Lucy in the crime. Although Lucy denied her involvement and no evidence existed to prove that she participated in the murder, Lavinia Harkins, the widow of the murdered man and thus also Lucy's owner, demanded that Lucy be burned alive along with Prince. This harrowing tale highlights the intersections of race, gender, and power relations that informed the interactions between "black slaves and Indian masters" in Indian Territory.
Peter Pitchlynn, or "Hat-choo-tuck-nee," a Choctaw chief and later tribal delegate to Washington (LC-USZ62-58502, Library of Congress Prints and Photographs Division, Washington, D.C.)
Even Emancipation and the end of the Civil War did not bring immediate relief to the enslaved living in the Choctaw and Chickasaw Nations. Although the Choctaw and Chickasaw sided with the Confederacy during the conflict, the United States considered them to be separate political polities; therefore, the abolition of slavery as stated in the Thirteenth Amendment did not apply in Indian Territory. Instead, the Choctaw/Chickasaw treaty of 1866 outlined the details of emancipation, citizenship, and land claims for the Freedmen, but inextricably (and problematically) linked these issues with Indian sovereignty, land rights, and annuities—one could not be obtained without the other. This knotty situation became further complicated with the passage of laws enacted by Choctaw and Chickasaw political leaders that seem eerily similar to the "Black Codes" of the Reconstruction era South. Former slaves in Choctaw country who did not have a work contract could be arrested for "vagrancy" by the lighthorsemen (police force) and then be auctioned off to the highest bidder—slavery by another name. Once again, the now emancipated slaves in Indian Territory, in particular African-American men, engaged in resisting these harsh measures and formed groups that lobbied for political and economic justice before the Freedmen's Bureau and Indian leaders.
Riverside, the home of Benjamin Colbert in Colbert's Ferry, OK (Oklahoma Historical Society)
Black Slaves, Indian Masters proves a much needed addition to African American and Native American histories of slavery. Krauthamer uses an exhaustive number of sources to bolster her argument–slave narratives, government records, personal correspondence of Indian leaders such as diaries and letters, and official papers of the Choctaw and Chickasaw Nations. Her work not only expands the lens of the study of slavery beyond the "black and white," but also can provide insight into the current tensions and issues of citizenship and identity existing between descendants of the enslaved and nations such as the Cherokee and Seminole today.
In 2011, Dr. Krauthamer was a fellow at The Institute for Historical Studies at UT-Austin. Read about the workshop she delivered while she was here, "Enslaved Women and the Politics of Self-Liberation."
You can purchase Black Slaves, Indian Masters here. And be sure to explore Envisioning Emancipation, a powerful collection of photographs portraying the lives of enslaved and freed African-Americans Dr. Krauthamer compiled with renowned photographic historian Deborah Willis.
Posted March 26, 2014 More Books, Business/Commerce, Periods, Regions, Slavery/Emancipation, Topics, Transnational, United States


The Blueprint for the Future Campaign for our North Campus expansion is the largest capital fundraising effort in the 50+ year history of the Urban School. This transformational project comprises two phases with the first phase, the 63,000-square-foot Mark Salkind Center academic and athletics building, completed in Fall 2016.
In this second phase, we have the opportunity to complete our campus with the conversion of the St. Agnes Gym on Page Street into a Performing Arts Center (PAC). The leadership fundraising phase of the campaign is underway and we look forward to highlighting more detailed information on the PAC very soon!
Please contact Anna Lee, Director of Development, via email or at 415 593 9542.


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Re: [wildfly-dev] Deployment unit runtime-name - must it have a packaging type suffix?
Stuart Douglas
Sunday, 7 January 2018 Sun, 7 Jan '18
On Sat, Jan 6, 2018 at 2:06 AM, Brian Stansberry < brian.stansberry(a)redhat.com> wrote:
On Fri, Jan 5, 2018 at 8:43 AM, David Lloyd <david.lloyd(a)redhat.com> wrote: > On Fri, Jan 5, 2018 at 8:20 AM, Brian Stansberry > <brian.stansberry(a)redhat.com> wrote: > > In practice the suffix is required. The deployment unit processors need > to > > know whether they are interested in the deployment, and in the end that > gets > > back to some DUP or other checking the suffix. The alternative would be > DUPs > > speculatively digging into the deployment, checking for deployment > > descriptors or annotations and the like and that would be more > expensive, > > likely buggy (e.g. false positives when some class in the classpath > includes > > an annotation not relevant to the deployment) and could mess up some use > > cases where we want to defer classloading. > > Another alternative is for an early processor to identify the type, > tag it on to the deployment context, and then we modify all other DUPs > to use that information. It seems pretty fragile to rely on the name, > particularly if that mechanism allows the "type" of deployment to > change in mid-deploy. > I agree; if it's not done that way now, it should be. My *impression* is the general pattern was the way you describe, i.e. for each significant type some early DUP determines it's a relevant type and attaches some stuff and then later ones rely on the attachments. But my impression could very well be wrong in some or many cases. I haven't done much DUP work beyond code reviews or simple fixes since the AS 7.0 days. But that early processor still needs a way to identify type and I think that comes down to the suffix.
Yes, various early DUP's call org.jboss.as.ee.structure.DeploymentTypeMarker#setType to set the deployment type, but it is identified via suffix. As most deployment descriptors are optional there is no 100% reliable way of identifying this other than the suffix. Stuart
-- Brian Stansberry Manager, Senior Principal Software Engineer Red Hat _______________________________________________ wildfly-dev mailing list wildfly-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/wildfly-dev


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Ed Ronkowski, a former Cook County prosecutor and former Will County Republican chairman, joins Monte Larrick and David Smith on the show to take us behind the scenes of election day, sharing stories of voter fraud, corruption, and other political shenanigans from his experiences. The three also discuss voter IDs and other ways we try to reduce fraud.
The "Laquan McDonald Monster" has surfaced, and unlike the Loch Ness Monster, it is tangible, palpable and deadly. Those 16 bullets will be remembered by black voters in 2016, and a torrent of rage — and votes — will be directed in the March 15, 2016, Democratic primary against both Cook County State's Attorney Anita Alvarez and any non-black candidates closely associated with Mayor Rahm Emanuel and police superintendent Garry McCarthy.