text:
<template name="tutorialAngular2.step_04.html">
  {{#markdown}}

Now that we have full data binding from server to client, let's interact with the data and see the updates in action.

In this chapter you will add the ability to insert a new party and delete an existing one from the UI.

First, let's create a simple form with a button that will add a new party.

# Component Architecture

In Angular 2, it's common practice to break your app into smaller components. Let's make a new component called `parties-form`, and put it inside it's own directory with the same name.

__`client/parties-form/parties-form.ts`:__

    import {Component, View} from 'angular2/angular2';

    @Component({
      selector: 'parties-form'
    })
    @View({
      templateUrl: "client/parties-form/parties-form.ng.html"
    })
    export class PartiesForm {}

Notice that we are exporting the class `PartiesForm` using ES6 module syntax. This is how files and dependencies can be passed to each other without the use of script tags in the view.

When data is `export`ed, it must also be `import`ed on the other end. We'll get to that soon.

Also note that we aren't bootstrapping this component, as it is going inside of the bootstrapped root component.

Inside `parties-form/parties-form.ng.html`, add the following form:

__`client/parties-form/parties-form.ng.html`:__

    <form>
      Name
      <input type="text">
      Description
      <input type="text">
      <button>Add</button>
    </form>

Link to the parties-form component in `index.ng.html`

__`client/index.ng.html`:__

      <parties-form></parties-form>

          {{dstache}}party.name}}

{{dstache}}party.description}}

And finally let your Socially Component know it should import and use the `parties-form` component.

__`client/app.ts`:__

      import {Component, View, NgFor, bootstrap} from 'angular2/angular2';
      import {PartiesForm} from 'client/parties-form/parties-form';

      ...

      @View({
        templateUrl: "client/index.ng.html",
        directives: [NgFor, PartiesForm]
      })
      class Socially () { ... }
    }

Again, first we import the class, then we add it to our list of View directives.

# Angular 2 Forms

Now let's get back to the form and make it functional.

In Angular 2, there are two main ways to create forms: we will address 'model-driven' forms in this step, but we'll also look at `template-driven` forms in step 06.

## Model Driven Forms

First up, import the form directives & controls.

__`client/parties-form/parties-form.ts`:__

      import {Component, View} from 'angular2/angular2';
      import {FORM_DIRECTIVES, Control, ControlGroup, Validators} from 'angular2/angular2';

      @Component({
        selector: 'parties-form'
      })
      @View({
        templateUrl: "parties-form/parties-form.ng.html",
        directives: [FORM_DIRECTIVES]
      })
      export class PartiesForm {}
    }

By now you should have the hang of it. `import`, and add it to the View directives.

Next, we can construct our form controls. For controls give you access to useful form features such as validators and much more.

__`client/parties-form/parties-form.ts`:__

    export class PartiesForm {
      constructor() {
        this.partiesForm = new ControlGroup({
          name: new Control(''),
          description: new Control('')
        });
      }

We are binding `this.partiesForm` here to a [Control Group](https://angular.io/docs/js/latest/api/forms/ControlGroup-class.html). Think of a control group as a wrapper for a group of form controls.

Alternatively, form controls can be created one at a time using Control, but it's easier to create them as a group.

    this.partiesForm.controls.name = new Control('');

is the same as

    this.partiesForm = new ControlGroup({
      name: new Control('')
    });

The first value provided is the initial value for the form control. For example, `this.name = new Control('Bob')` would initialize the form value to 'Bob', or `this.name = new Control()` would initialize the value to null.

    this.partiesForm.value;
    > { name: '', description: ''}

We could also access the control values individually.

    this.partiesForm.controls.name.value;
    > ''

A control can also take a Validator, which binds to the form. Name & description are both required, so let's specify that.

__`client/parties-form/parties-form.ts`:__

    constructor() {
      this.partiesForm = new ControlGroup({
        name: new Control('', Validators.required),
        description: new Control('', Validators.required)
      });

The required validator here specifies that the form isn't valid if name or description are empty.

    this.partiesForm.value = '';
    this.partiesForm.valid
    > false

First things first, let's bind the control group to the form and the controls to the input values.

__`client/parties-form/parties-form.ng.html`:__

    <form [ng-form-model]="partiesForm">
      Name
      <input type="text" ng-control="name">
      Description
      <input type="text" ng-control="description">
      <button>Add</button>
    </form>

Now each time the user types inside these inputs, the value of the partiesForm and its controls will be automatically updated.  Conversely, if `this.partiesForm.value` is changed outside of the HTML, the input values will be updated accordingly.

Alternatively we can bind to the form by using a local variable in the template, indicated by the '#' symbol.

__`client/parties-form/parties-form.ng.html`:__

    <form [ng-form-model]="partiesForm" #f="form">

Now calling `f.value`, or displaying {{dstache}}f.value}} will give us the value of our form.

    f.value
    > {name: '', description: ''}

## (submit)

In Angular 2, the model determines the view. Change the model, and the view automatically updates thanks to Angular 2's change detection with Zone.js.

But then how does the view trigger changes in the model? It does this through events, which are indicated by the round bracket () syntax. `(submit)` or `(click)` are examples of events.

Now let's bind a submit event to the add button provided to us by the [NgForm](https://angular.io/docs/js/latest/api/forms/NgForm-class.html) directive. This will trigger if the button is clicked, or if the user presses enter on the final field.

__`client/parties-form/parties-form.ng.html`:__

    <form [ng-form-model]="partiesForm" #f="form" (submit)="add(f.value)">
      <button type="submit">Add</button>
    </form>

In Angular 2, events are indicated by the round bracket () syntax. Here we are telling Angular to call a method `add` on submit and pass in the value of the form, `f`. Let's add the add method to our PartiesForm class.

__`client/parties-form/parties-form.ts`:__

    class PartiesForm {
      constructor() { ... },

      add(party) {
        // validate if the form is valid
        if (this.partiesForm.valid) {

          // insert parties (insecure way)
          Parties.insert({
            name: party.name,
            description: party.description
          });

        //reset input values to empty strings
        this.partiesForm.controls.name.updateValue('');
        this.partiesForm.controls.description.updateValue('');
        }
      }
    }

Open a different browser, fill out the form, submit and see how the party is added on both clients. So simple!

> As a note, if you are dealing with more complex forms, use [Form Builder](https://github.com/angular/angular/blob/master/modules/angular2/src/forms/form_builder.ts), which further simplifies the use of Controls & ControlGroups.

## (click)

Now, let's add the ability to delete parties.

Let's add an X button to each party:

__`client/index.ng.html`:__

        {{dstache}}party.name}}

{{dstache}}party.description}}

        <button (click)="remove(party)">X</button>

Here again, we are binding an event to the class context and passing in the party as a parameter.

Let's go into the class and add that function.

Add the function inside the Socially class in `app.ts`:

__`client/app.ts`:__

    constructor() {...}
    remove(party){
      Parties.remove(party._id);
    }

The Mongo Collection Parties has a function called 'remove'. We search for the relevant party by its identifier, `_id`, and delete it.

And this is how the class should now look:

__`client/app.ts`:__

    class Socially {
      constructor() {
        Tracker.autorun(zone.bind(() => {
          this.parties = Parties.find().fetch();
        }));
      }
      remove(party) {
        Parties.remove(party._id);
      }
    }

Now try to delete a few parties and also watch them being removed from other browser clients.

# Summary

So now you've seen how easy it is to manipulate the data using Angular's powerful directives and sync that data with Meteor's powerful Mongo.collection API.

   {{/markdown}}
</template>


We pride ourselves in being the UK's largest manufacturer of scaffold board end bands, batten bands and nail plates, made to order and specific to our customers requirements.
Efficient, high quality, customer-focused service.
In 1970 Derrick Telford set up the company Chilwell Toolmakers that was able to manufacture Press Tools, Progression Tools, Jigs & Fixtures. Over the years Chilwell Toolmakers have supplied a variety of industries such as aerospace, automotive, agricultural, electrical, construction and others.
To date, the company has a comprehensive tool room with CNC Milling and Wire Erosion facilities, where we are able to carry out repairs and modifications to customer's tools.
In 1977 Chilwell Products Ltd was incorporated and began with sub-contract metal pressings running alongside Chilwell Toolmakers. Since then Chilwell Products have experienced a rapid growth and this is now our main business, manufacturing scaffold board end bands and nail plates. We pride ourselves on quality and delivery and are able to offer a first class service.


On a day where Rockstar Energy Husqvarna factory riders Pablo Quintanilla and Pela Renet had to exercise extreme care with their FR 450 Rally bikes and tires because of the Dakar Rally marathon stage, both arrived safely at their destination at Uyuni (Bolivia) after the seventh stage. Pablo Quintanilla hung onto his overall second position after riding out the stage in ninth place. Pela Renet was 11th but advanced one place in the rankings to seventh overall.
The stage win went to American Ricky Brabec and as every completed stage so far has produced a different winner, it remains impossible to speculate about the end result next Saturday in Buenos Aires.
Quintanilla, of Chile has continued to concentrate on careful and consistent rides and took the same approach in the re-shaped stage seven, quickly drawn up by race direction on Sunday's rest day. It included elements of the sixth stage that was washed out on Saturday and the 161 km timed special was in the sand, high on the Bolivian Altplano. This, and the additional liaison rides of another 640 km saw competitors on their bikes for another long day.
Quintanilla's time loss of 10.28 minutes in the stage was probably tactical to ensure he made it safely to the overnight bivouac. He is now 17.45 minutes behind overall leader Sam Sunderland but as riders admitted on the rest day, the worst is probably still to come. Renet finished the stage in eleventh 12.35 minutes behind Brabec but still moved up a place in the overall standings.
On Tuesday both riders have to continue to look after bikes and tyres to make it back to their support teams in good shape when they reach the overnight stop at Salta, back in Argentina. There they will be back in the hands of their mechanics and staff. Dakar rally rules state that there can be no assistance from the teams at the overnight stop of the marathon stage.
The rally has continued to throw up surprises on its way through Paraguay, Bolivia and Argentina. Friday's stage five was shortened when riders were deluged with heavy rain, which ultimately resulted in the cancelation of the sixth stage, which was to be the longest and most complicated. Teams however received a tumultuous welcome by the thousands of Bolivian fans, who braved the bed weather rain to welcome them in La Paz.
Sunday was the one scheduled rest day, and race direction used to reshape the seventh stage, which then took in parts of the previously uncontested sixth stage. The overnight stop was Uyuni, close to Bolivia's border with neighbouring Chile. On Tuesday they travel to Salta, and while the Dakar has been there before, organizers have promised it will be approached in a very different way. They warn that there will be many rivers to cross and that they will pass through spectacular canyons in Tuesday's eighth stage.


text:
Q&A with Research Placement Student Lauren Thompson
By On The Pulse May 8, 2019 May 8, 2019 General
Since the turn of the year, On The Pulse has welcomed into the fold a very enthusiastic and impressive extra pair of hands to support our research activities – meet Lauren Thompson.
Lauren is currently studying an MSc in Health Psychology at the prestigious King's College London; one of the UK and world's top-ranking universities based in the heart of the capital.
As part of the master's programme, students within the health psychology section of the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) are offered unique, high quality work placements to put their learning and academic skills into practice.
We teamed up with Dr Lyndsay Hughes, a lecturer at the institute, to collaborate on our ongoing project development around peer-led health promotion for young people living with haemophilia. In turn, we've been able to host a placement and were elated that Lauren chose to join us for a four-month period!
Lauren was brave enough to take the hot seat to share a snapshot of her background and placement experience with us…
1) So Lauren, please can you tell us a bit about yourself…
I grew up in the East End of London and, actually I'm the first in my family to go to university! My family have always been really supportive of my academic work, which I think has inspired and encouraged me to achieve more. My mum would always tell me, 'Your best is all you can do!' This is something I have to remind myself of…
I did my undergraduate Psychology degree at the University of Bristol and just fell in love with the place. The University is embedded in the city, which is very much like the campuses at King's. Being back here in London, there is always something fun and interesting going on, which is important to me, especially after a long day of lectures and library stints working on assignments!
I started kickboxing during my last year at Bristol and have recently taken up self-defence classes with some friends. It's a great distraction from all the work I've yet to complete – clearly living up to the student stereotype!
Ah, graduation day! Lauren was the first in her family to go to university and has taken it a step further by studying a master's – absolutely fearless!
2) Why did you choose to study health psychology?
I hadn't previously come across health psychology as I know it today. To be entirely honest, as my graduation approached, I began looking into studying a master's degree, although I still wasn't quite sure what my next steps would be. Is that bad? I feel like lots of students reach a crossroads and consider whether to continue studying or not. When I was looking through the courses available, the MSc at King's sounded right up my street!
During my undergraduate, some of my favourite topics were those discussing how health behaviours, such as smoking, are related to mental health and wellbeing. What I find most interesting is how relevant these topics are to everyday life and how important it is to understand them in the context of the issues faced across healthcare. Health psychology gives me the opportunity to apply psychological principles to the study of behaviour relevant to health, illness and healthcare more broadly. Overall, I want to help people in any way that I can and studying this course teaches me about how I can apply different methods to support those impacted by life-long, chronic conditions in particular.
I am excited to see where my studies take me!
3) Did you know about haemophilia before starting your placement? Has anything surprised you?
I didn't know a lot about haemophilia. I was aware of the condition after learning about genetics and genetic disorders in school. Because the actual condition isn't discussed in great detail, I think there is a common misconception that the primary concerns relate to bleeding heavily from small cuts. But I now realise there is so much more to it. Most surprising to me, when speaking to fellow students, is how little awareness there seems to be of haemophilia!
I was taken aback by the potential severity of haemophilia and what those with the condition must go through, especially at such a young age. As young people, we already have so much to contend with as we try to learn how to navigate through the world into adulthood. For some of us, this transition can be relatively smooth but for others, truly understanding who you are, what you like and what you want to do in life can be really daunting. So, for young people living with haemophilia, to have to go through these same challenges, in addition to adjusting to the trials and tribulations that can come with having a chronic condition, is remarkable!
Hearing about adolescents living with haemophilia learning to self-infuse typically as young as 11-years-old was also really surprising to me, particularly when thinking of myself at that age. But ultimately, understanding that complete self-management isn't achieved for some until their early 20s, with a lack of support currently for young people during this transitional period, only highlights the importance of work in this area.
Lauren was surprised to learn that self-care skills are not fully acquired by young people living with haemophilia at least until their early 20s.
4) There were a number of placement opportunities to choose from… why this one?
What caught my interest the most was the opportunity to support the research around improving the patient experience for young people – in this instance living with haemophilia – where the focus was centred on developing a peer support intervention in a systematic way, underpinned by behaviour change theory and techniques. I could directly apply what I had been learning across my course and leverage my understanding of behavioural change models to map on to evidence-based intervention content. It was a blend of personal interest and supporting a really worthwhile cause!
The project is still in its infancy, so it was a truly exciting opportunity to have an influence from the very beginning and hopefully the research will lead to making a real difference for all young people living with haemophilia.
5) What are your most valuable takeaways from the placement so far?
Tough question! It's certainly taken me out of my comfort zone and been a massive growth experience, particularly when it comes to the intricacies of project development. I've definitely gained insight into research theory and techniques beyond that of my studies. The benefit of doing a work placement with a small independent company is that I've been in the thick of the action – let's just say, there's been no hiding!
As much as I'm eager to be involved in creating positive change for people with health-related needs and challenges, this placement has reminded me of just how vital the initial research stage is when conceptualising interventions or service improvement. It has to be meaningful and wholly involve the people for whom the intervention is being tailored for, should it truly intend to have a lasting impact on the target demographic and enhance people's quality of life.
King's is the fourth oldest university in England and stretches across five campuses in London, including at Guy's hospital where part of the IoPPN is based.
6) Could see yourself working in haemophilia or the wider rare disease community in the future?
Definitely! The resilience of people within this community is really inspiring. It's clearly an exciting time with lots of innovation happening in haemophilia and rare diseases generally. But there still seems big gaps in support services in order to tackle the challenges that people living with a rare disease and their families face on a daily basis.
I would like to continue in this strand of work of engaging young people in their healthcare, including helping them to make their own informed decisions and have a say in the services made available for them. This has very much inspired my interest in patient and public involvement. I could apply my understanding of good research practices and help to embed the patient voice within healthcare services.
There are still lots that we can learn from young people living with haemophilia and other rare diseases and hopefully some really exciting opportunities will present themselves where I can influence positive change.
We would like to thank Lauren for all of her hard work and support, and fully immersing herself into our world!
If you would like to learn more about our collaboration with Dr Lyndsay Hughes and King's or have any questions for Lauren directly, please get in touch via our contact page (please refer to our privacy policy statement here).
AdolescenceAdulthoodBehaviour change theoryBleedingBleeding disorderBristolChronic conditionDr Lyndsay HughesGeneticsHaemophiliaHealth behaviourHealth promotionHealth psychologyHealthcareHemophiliaKing's College LondonLauren ThompsonLondonMental healthOn The PulsePeer supportPeer-ledPlacementRare diseaseResearchSelf-infuseSelf-managementSmokingStudentTransitionUniversity of BristolWellbeingYoung people
Spotlight on History: Contaminated Blood and the Origins of the Infected Blood Inquiry
VIDEO: Watch Episode 1 of The Culture Shift with Dr Ann Hagell

redpajama_set_name: RedPajamaCommonCrawl


text:
Callisto (moon)
For other uses, see Callisto.
Not to be confused with Calypso (moon) of Saturn.
Callisto /kəˈlɪstoʊ/[9] (Jupiter IV) is the second-largest moon of Jupiter, after Ganymede. It is the third-largest moon in the Solar System after Ganymede and Saturn's largest moon Titan, and the largest object in the Solar System not to be properly differentiated. Callisto was discovered in 1610 by Galileo Galilei. At 4821 km in diameter, Callisto has about 99% the diameter of the planet Mercury but only about a third of its mass. It is the fourth Galilean moon of Jupiter by distance, with an orbital radius of about 1883000 km.[2] It is not in an orbital resonance like the three other Galilean satellites—Io, Europa, and Ganymede—and is thus not appreciably tidally heated.[10] Callisto's rotation is tidally locked to its orbit around Jupiter, so that the same hemisphere always faces inward; Jupiter appears to stand nearly still in Callisto's sky. It is less affected by Jupiter's magnetosphere than the other inner satellites because of its more remote orbit, located just outside Jupiter's main radiation belt.[11][12]
Callisto's anti-Jovian hemisphere imaged in 2001 by NASA's Galileo spacecraft. It shows a heavily cratered terrain. The large impact structure Asgard is on the limb at upper right. The prominent rayed crater below and just right of center is Bran.
7 January 1610[1]
Jupiter IV
Callistoan, Callistonian
Periapsis
1869000 km[a]
Apoapsis
1897000 km[b]
Semi-major axis
1 882 700 km[2]
0.0074[2]
Orbital period
16.6890184 d[2]
Average orbital speed
2.017° (to the ecliptic)
0.192° (to local Laplace planes)[2]
Satellite of
Mean radius
2410.3±1.5 km (0.378 Earths)[3]
7.30×107 km2 (0.143 Earths)[c]
5.9×1010 km3 (0.0541 Earths)[d]
(1.075938±0.000137)×1023 kg (0.018 Earths)[3]
Mean density
1.8344±0.0034 g/cm3[3]
Surface gravity
1.235 m/s2 (0.126 g)[e]
Moment of inertia factor
0.359±0.005[4] (estimate)
2.440 km/s[f]
Rotation period
synchronous[3]
Axial tilt
zero[3]
0.22 (geometric)[5]
Surface temp.
K[5]
80±5 134±11 165±5
Apparent magnitude
5.65 (opposition)[6]
Surface pressure
7.5 picobar[7] (7.5×10−10 kPa, 7.4019×10−12 atm)
Composition by volume
≈ 4×108 molecules/cm3 carbon dioxide;[7]
up to 2×1010 molecules/cm3 molecular oxygen(O2)[8]
Callisto is composed of approximately equal amounts of rock and ices, with a density of about 1.83 g/cm3, the lowest density and surface gravity of Jupiter's major moons. Compounds detected spectroscopically on the surface include water ice,[13] carbon dioxide, silicates, and organic compounds. Investigation by the Galileo spacecraft revealed that Callisto may have a small silicate core and possibly a subsurface ocean of liquid water[13] at depths greater than 100 km.[14][4]
The surface of Callisto is the oldest and most heavily cratered in the Solar System.[15] Its surface is completely covered with impact craters.[16] It does not show any signatures of subsurface processes such as plate tectonics or volcanism, with no signs that geological activity in general has ever occurred, and is thought to have evolved predominantly under the influence of impacts.[17] Prominent surface features include multi-ring structures, variously shaped impact craters, and chains of craters (catenae) and associated scarps, ridges and deposits.[17] At a small scale, the surface is varied and made up of small, sparkly frost deposits at the tips of high spots, surrounded by a low-lying, smooth blanket of dark material.[5] This is thought to result from the sublimation-driven degradation of small landforms, which is supported by the general deficit of small impact craters and the presence of numerous small knobs, considered to be their remnants.[18] The absolute ages of the landforms are not known.
Callisto is surrounded by an extremely thin atmosphere composed of carbon dioxide[7] and probably molecular oxygen,[8] as well as by a rather intense ionosphere.[19] Callisto is thought to have formed by slow accretion from the disk of the gas and dust that surrounded Jupiter after its formation.[20] Callisto's gradual accretion and the lack of tidal heating meant that not enough heat was available for rapid differentiation. The slow convection in the interior of Callisto, which commenced soon after formation, led to partial differentiation and possibly to the formation of a subsurface ocean at a depth of 100–150 km and a small, rocky core.[21]
The likely presence of an ocean within Callisto leaves open the possibility that it could harbor life. However, conditions are thought to be less favorable than on nearby Europa.[22] Various space probes from Pioneers 10 and 11 to Galileo and Cassini have studied Callisto. Because of its low radiation levels, Callisto has long been considered the most suitable place for a human base for future exploration of the Jovian system.[23]
DiscoveryEdit
Callisto was discovered by Galileo in January 1610, along with the three other large Jovian moons—Ganymede, Io, and Europa.[1]
NameEdit
Callisto is named after one of Zeus's many lovers in Greek mythology. Callisto was a nymph (or, according to some sources, the daughter of Lycaon) who was associated with the goddess of the hunt, Artemis.[24] The name was suggested by Simon Marius soon after Callisto's discovery.[25] Marius attributed the suggestion to Johannes Kepler.[24] However, the names of the Galilean satellites fell into disfavor for a considerable time, and were not revived in common use until the mid-20th century. In much of the earlier astronomical literature, Callisto is referred to by its Roman numeral designation, a system introduced by Galileo, as Jupiter IV or as "the fourth satellite of Jupiter".[26] In scientific writing, the adjectival form of the name is Callistoan,[27] pronounced /ˌkælɪˈstoʊ.ən/, or Callistan.[18]
Orbit and rotationEdit
Galilean moons around Jupiter Jupiter · Io · Europa · Ganymede · Callisto
Callisto (bottom left), Jupiter (top right) and Europa (below and left of Jupiter's Great Red Spot) as viewed by Cassini–Huygens
Callisto is the outermost of the four Galilean moons of Jupiter. It orbits at a distance of approximately 1 880 000 km (26.3 times the 71 492 km radius of Jupiter itself).[2] This is significantly larger than the orbital radius—1 070 000 km—of the next-closest Galilean satellite, Ganymede. As a result of this relatively distant orbit, Callisto does not participate in the mean-motion resonance—in which the three inner Galilean satellites are locked—and probably never has.[10]
Like most other regular planetary moons, Callisto's rotation is locked to be synchronous with its orbit.[3] The length of Callisto's day, simultaneously its orbital period, is about 16.7 Earth days. Its orbit is very slightly eccentric and inclined to the Jovian equator, with the eccentricity and inclination changing quasi-periodically due to solar and planetary gravitational perturbations on a timescale of centuries. The ranges of change are 0.0072–0.0076 and 0.20–0.60°, respectively.[10] These orbital variations cause the axial tilt (the angle between rotational and orbital axes) to vary between 0.4 and 1.6°.[28]
The dynamical isolation of Callisto means that it has never been appreciably tidally heated, which has important consequences for its internal structure and evolution.[29] Its distance from Jupiter also means that the charged-particle flux from Jupiter's magnetosphere at its surface is relatively low—about 300 times lower than, for example, that at Europa. Hence, unlike the other Galilean moons, charged-particle irradiation has had a relatively minor effect on Callisto's surface.[11] The radiation level at Callisto's surface is equivalent to a dose of about 0.01 rem (0.1 mSv) per day, which is over ten times higher than Earth's average background radiation.[30][31]
Physical characteristicsEdit
Size comparison of Earth, Moon and Callisto
Near-IR spectra of dark cratered plains (red) and the Asgard impact structure (blue), showing the presence of more water ice (absorption bands from 1 to 2 µm)[32] and less rocky material within Asgard.
The average density of Callisto, 1.83 g/cm3,[3] suggests a composition of approximately equal parts of rocky material and water ice, with some additional volatile ices such as ammonia.[14] The mass fraction of ices is 49–55%.[14][21] The exact composition of Callisto's rock component is not known, but is probably close to the composition of L/LL type ordinary chondrites,[14] which are characterized by less total iron, less metallic iron and more iron oxide than H chondrites. The weight ratio of iron to silicon is 0.9–1.3 in Callisto, whereas the solar ratio is around 1:8.[14]
Callisto's surface has an albedo of about 20%.[5] Its surface composition is thought to be broadly similar to its composition as a whole. Near-infrared spectroscopy has revealed the presence of water ice absorption bands at wavelengths of 1.04, 1.25, 1.5, 2.0 and 3.0 micrometers.[5] Water ice seems to be ubiquitous on the surface of Callisto, with a mass fraction of 25–50%.[4] The analysis of high-resolution, near-infrared and UV spectra obtained by the Galileo spacecraft and from the ground has revealed various non-ice materials: magnesium- and iron-bearing hydrated silicates,[5] carbon dioxide,[33] sulfur dioxide,[34] and possibly ammonia and various organic compounds.[4][5] Spectral data indicate that Callisto's surface is extremely heterogeneous at the small scale. Small, bright patches of pure water ice are intermixed with patches of a rock–ice mixture and extended dark areas made of a non-ice material.[5][17]
The Callistoan surface is asymmetric: the leading hemisphere[g] is darker than the trailing one. This is different from other Galilean satellites, where the reverse is true.[5] The trailing hemisphere[g] of Callisto appears to be enriched in carbon dioxide, whereas the leading hemisphere has more sulfur dioxide.[35] Many fresh impact craters like Lofn also show enrichment in carbon dioxide.[35] Overall, the chemical composition of the surface, especially in the dark areas, may be close to that seen on D-type asteroids,[17] whose surfaces are made of carbonaceous material.
Internal structureEdit
Model of Callisto's internal structure showing a surface ice layer, a possible liquid water layer, and an ice–rock interior
Callisto's battered surface lies on top of a cold, stiff, and icy lithosphere that is between 80 and 150 km thick.[14][21] A salty ocean 150–200 km deep may lie beneath the crust,[14][21] indicated by studies of the magnetic fields around Jupiter and its moons.[36][37] It was found that Callisto responds to Jupiter's varying background magnetic field like a perfectly conducting sphere; that is, the field cannot penetrate inside Callisto, suggesting a layer of highly conductive fluid within it with a thickness of at least 10 km.[37] The existence of an ocean is more likely if water contains a small amount of ammonia or other antifreeze, up to 5% by weight.[21] In this case the water+ice layer can be as thick as 250–300 km.[14] Failing an ocean, the icy lithosphere may be somewhat thicker, up to about 300 km.
Beneath the lithosphere and putative ocean, Callisto's interior appears to be neither entirely uniform nor particularly variable. Galileo orbiter data[3] (especially the dimensionless moment of inertia[h]—0.3549 ± 0.0042—determined during close flybys) suggest that its interior is composed of compressed rocks and ices, with the amount of rock increasing with depth due to partial settling of its constituents.[14][38] In other words, Callisto is only partially differentiated. The density and moment of inertia are compatible with the existence of a small silicate core in the center of Callisto. The radius of any such core cannot exceed 600 km, and the density may lie between 3.1 and 3.6 g/cm3.[3][14] Callisto's interior is in stark contrast to that of Ganymede, which appears to be fully differentiated.[4][39]
Surface featuresEdit
See also: List of geological features on Callisto
Galileo image of cratered plains, illustrating the pervasive local smoothing of Callisto's surface
The ancient surface of Callisto is one of the most heavily cratered in the Solar System.[40] In fact, the crater density is close to saturation: any new crater will tend to erase an older one. The large-scale geology is relatively simple; there are no large mountains on Callisto, volcanoes or other endogenic tectonic features.[41] The impact craters and multi-ring structures—together with associated fractures, scarps and deposits—are the only large features to be found on the surface.[17][41]
Callisto's surface can be divided into several geologically different parts: cratered plains, light plains, bright and dark smooth plains, and various units associated with particular multi-ring structures and impact craters.[17][41] The cratered plains constitute most of the surface area and represent the ancient lithosphere, a mixture of ice and rocky material. The light plains include bright impact craters like Burr and Lofn, as well as the effaced remnants of old large craters called palimpsests,[i] the central parts of multi-ring structures, and isolated patches in the cratered plains.[17] These light plains are thought to be icy impact deposits. The bright, smooth plains constitute a small fraction of Callisto's surface and are found in the ridge and trough zones of the Valhalla and Asgard formations and as isolated spots in the cratered plains. They were thought to be connected with endogenic activity, but the high-resolution Galileo images showed that the bright, smooth plains correlate with heavily fractured and knobby terrain and do not show any signs of resurfacing.[17] The Galileo images also revealed small, dark, smooth areas with overall coverage less than 10,000 km2, which appear to embay[j] the surrounding terrain. They are possible cryovolcanic deposits.[17] Both the light and the various smooth plains are somewhat younger and less cratered than the background cratered plains.[17][42]
Impact crater Hár with a central dome. Chains of secondary craters from formation of the more recent crater Tindr at upper right crosscut the terrain.
Impact crater diameters seen range from 0.1 km—a limit defined by the imaging resolution—to over 100 km, not counting the multi-ring structures.[17] Small craters, with diameters less than 5 km, have simple bowl or flat-floored shapes. Those 5–40 km across usually have a central peak. Larger impact features, with diameters in the range 25–100 km, have central pits instead of peaks, such as Tindr crater.[17] The largest craters with diameters over 60 km can have central domes, which are thought to result from central tectonic uplift after an impact;[17] examples include Doh and Hár craters. A small number of very large—more 100 km in diameter—and bright impact craters show anomalous dome geometry. These are unusually shallow and may be a transitional landform to the multi-ring structures, as with the Lofn impact feature.[17] Callisto's craters are generally shallower than those on the Moon.
Voyager 1 image of Valhalla, a multi-ring impact structure 3800 km in diameter
The largest impact features on Callisto's surface are multi-ring basins.[17][41] Two are enormous. Valhalla is the largest, with a bright central region 600 kilometers in diameter, and rings extending as far as 1,800 kilometers from the center (see figure).[43] The second largest is Asgard, measuring about 1,600 kilometers in diameter.[43] Multi-ring structures probably originated as a result of a post-impact concentric fracturing of the lithosphere lying on a layer of soft or liquid material, possibly an ocean.[27] The catenae—for example Gomul Catena—are long chains of impact craters lined up in straight lines across the surface. They were probably created by objects that were tidally disrupted as they passed close to Jupiter prior to the impact on Callisto, or by very oblique impacts.[17] A historical example of a disruption was Comet Shoemaker-Levy 9.
As mentioned above, small patches of pure water ice with an albedo as high as 80% are found on the surface of Callisto, surrounded by much darker material.[5] High-resolution Galileo images showed the bright patches to be predominately located on elevated surface features: crater rims, scarps, ridges and knobs.[5] They are likely to be thin water frost deposits. Dark material usually lies in the lowlands surrounding and mantling bright features and appears to be smooth. It often forms patches up to 5 km across within the crater floors and in the intercrater depressions.[5]
Two landslides 3–3.5 km long are visible on the right sides of the floors of the two large craters on the right.
On a sub-kilometer scale the surface of Callisto is more degraded than the surfaces of other icy Galilean moons.[5] Typically there is a deficit of small impact craters with diameters less than 1 km as compared with, for instance, the dark plains on Ganymede.[17] Instead of small craters, the almost ubiquitous surface features are small knobs and pits.[5] The knobs are thought to represent remnants of crater rims degraded by an as-yet uncertain process.[18] The most likely candidate process is the slow sublimation of ice, which is enabled by a temperature of up to 165 K, reached at a subsolar point.[5] Such sublimation of water or other volatiles from the dirty ice that is the bedrock causes its decomposition. The non-ice remnants form debris avalanches descending from the slopes of the crater walls.[18] Such avalanches are often observed near and inside impact craters and termed "debris aprons".[5][17][18] Sometimes crater walls are cut by sinuous valley-like incisions called "gullies", which resemble certain Martian surface features.[5] In the ice sublimation hypothesis, the low-lying dark material is interpreted as a blanket of primarily non-ice debris, which originated from the degraded rims of craters and has covered a predominantly icy bedrock.
The relative ages of the different surface units on Callisto can be determined from the density of impact craters on them. The older the surface, the denser the crater population.[44] Absolute dating has not been carried out, but based on theoretical considerations, the cratered plains are thought to be ~4.5 billion years old, dating back almost to the formation of the Solar System. The ages of multi-ring structures and impact craters depend on chosen background cratering rates and are estimated by different authors to vary between 1 and 4 billion years.[17][40]
Atmosphere and ionosphereEdit
Induced magnetic field around Callisto
Callisto has a very tenuous atmosphere composed of carbon dioxide.[7] It was detected by the Galileo Near Infrared Mapping Spectrometer (NIMS) from its absorption feature near the wavelength 4.2 micrometers. The surface pressure is estimated to be 7.5 picobar (0.75 µPa) and particle density 4 × 108 cm−3. Because such a thin atmosphere would be lost in only about 4 days (see atmospheric escape), it must be constantly replenished, possibly by slow sublimation of carbon dioxide ice from Callisto's icy crust,[7] which would be compatible with the sublimation–degradation hypothesis for the formation of the surface knobs.
Callisto's ionosphere was first detected during Galileo flybys;[19] its high electron density of 7–17 × 104 cm−3 cannot be explained by the photoionization of the atmospheric carbon dioxide alone. Hence, it is suspected that the atmosphere of Callisto is actually dominated by molecular oxygen (in amounts 10–100 times greater than CO
2).[8] However, oxygen has not yet been directly detected in the atmosphere of Callisto. Observations with the Hubble Space Telescope (HST) placed an upper limit on its possible concentration in the atmosphere, based on lack of detection, which is still compatible with the ionospheric measurements.[45] At the same time, HST was able to detect condensed oxygen trapped on the surface of Callisto.[46]
Atomic hydrogen has also been detected in Callisto's atmosphere via recent analysis of 2001 Hubble Space Telescope data.[47] Spectral images taken on 15 and 24 December 2001 were re-examined, revealing a faint signal of scattered light that indicates a hydrogen corona. The observed brightness from the scattered sunlight in Callisto's hydrogen corona is approximately two times larger when the leading hemisphere is observed. This asymmetry may originate from a different hydrogen abundance in both leading and trailing hemispheres. However, this hemispheric difference in Callisto's hydrogen corona brightness is likely to originate from the extinction of the signal in the Earth's geocorona, which is greater when the trailing hemisphere is observed.[48]
Origin and evolutionEdit
The partial differentiation of Callisto (inferred e.g. from moment of inertia measurements) means that it has never been heated enough to melt its ice component.[21] Therefore, the most favorable model of its formation is a slow accretion in the low-density Jovian subnebula—a disk of the gas and dust that existed around Jupiter after its formation.[20] Such a prolonged accretion stage would allow cooling to largely keep up with the heat accumulation caused by impacts, radioactive decay and contraction, thereby preventing melting and fast differentiation.[20] The allowable timescale of formation of Callisto lies then in the range 0.1 million–10 million years.[20]
Views of eroding (top) and mostly eroded (bottom) ice knobs (~100 m high), possibly formed from the ejecta of an ancient impact
The further evolution of Callisto after accretion was determined by the balance of the radioactive heating, cooling through thermal conduction near the surface, and solid state or subsolidus convection in the interior.[29] Details of the subsolidus convection in the ice is the main source of uncertainty in the models of all icy moons. It is known to develop when the temperature is sufficiently close to the melting point, due to the temperature dependence of ice viscosity.[49] Subsolidus convection in icy bodies is a slow process with ice motions of the order of 1 centimeter per year, but is, in fact, a very effective cooling mechanism on long timescales.[49] It is thought to proceed in the so-called stagnant lid regime, where a stiff, cold outer layer of Callisto conducts heat without convection, whereas the ice beneath it convects in the subsolidus regime.[21][49] For Callisto, the outer conductive layer corresponds to the cold and rigid lithosphere with a thickness of about 100 km. Its presence would explain the lack of any signs of the endogenic activity on the Callistoan surface.[49][50] The convection in the interior parts of Callisto may be layered, because under the high pressures found there, water ice exists in different crystalline phases beginning from the ice I on the surface to ice VII in the center.[29] The early onset of subsolidus convection in the Callistoan interior could have prevented large-scale ice melting and any resulting differentiation that would have otherwise formed a large rocky core and icy mantle. Due to the convection process, however, very slow and partial separation and differentiation of rocks and ices inside Callisto has been proceeding on timescales of billions of years and may be continuing to this day.[50]
The current understanding of the evolution of Callisto allows for the existence of a layer or "ocean" of liquid water in its interior. This is connected with the anomalous behavior of ice I phase's melting temperature, which decreases with pressure, achieving temperatures as low as 251 K at 2,070 bar (207 MPa).[21] In all realistic models of Callisto the temperature in the layer between 100 and 200 km in depth is very close to, or exceeds slightly, this anomalous melting temperature.[29][49][50] The presence of even small amounts of ammonia—about 1–2% by weight—almost guarantees the liquid's existence because ammonia would lower the melting temperature even further.[21]
Although Callisto is very similar in bulk properties to Ganymede, it apparently had a much simpler geological history. The surface appears to have been shaped mainly by impacts and other exogenic forces.[17] Unlike neighboring Ganymede with its grooved terrain, there is little evidence of tectonic activity.[4] Explanations that have been proposed for the contrasts in internal heating and consequent differentiation and geologic activity between Callisto and Ganymede include differences in formation conditions,[51] the greater tidal heating experienced by Ganymede,[52] and the more numerous and energetic impacts that would have been suffered by Ganymede during the Late Heavy Bombardment.[53][54][55] The relatively simple geological history of Callisto provides planetary scientists with a reference point for comparison with other more active and complex worlds.[4]
Potential habitabilityEdit
It is speculated that there could be life in Callisto's subsurface ocean. Like Europa and Ganymede, as well as Saturn's moons Enceladus, Mimas, Dione and Titan, a possible subsurface ocean might be composed of salt water.
It is possible that halophiles could thrive in the ocean.[56] As with Europa and Ganymede, the idea has been raised that habitable conditions and even extraterrestrial microbial life may exist in the salty ocean under the Callistoan surface.[22] However, the environmental conditions necessary for life appear to be less favorable on Callisto than on Europa. The principal reasons are the lack of contact with rocky material and the lower heat flux from the interior of Callisto.[22] Scientist Torrence Johnson said the following about comparing the odds of life on Callisto with the odds on other Galilean moons:[57]
The basic ingredients for life—what we call 'pre-biotic chemistry'—are abundant in many solar system objects, such as comets, asteroids and icy moons. Biologists believe liquid water and energy are then needed to actually support life, so it's exciting to find another place where we might have liquid water. But, energy is another matter, and currently, Callisto's ocean is only being heated by radioactive elements, whereas Europa has tidal energy as well, from its greater proximity to Jupiter.
Based on the considerations mentioned above and on other scientific observations, it is thought that of all of Jupiter's moons, Europa has the greatest chance of supporting microbial life.[22][58]
ExplorationEdit
The Pioneer 10 and Pioneer 11 Jupiter encounters in the early 1970s contributed little new information about Callisto in comparison with what was already known from Earth-based observations.[5] The real breakthrough happened later with the Voyager 1 and Voyager 2 flybys in 1979. They imaged more than half of the Callistoan surface with a resolution of 1–2 km, and precisely measured its temperature, mass and shape.[5] A second round of exploration lasted from 1994 to 2003, when the Galileo spacecraft had eight close encounters with Callisto, the last flyby during the C30 orbit in 2001 came as close as 138 km to the surface. The Galileo orbiter completed the global imaging of the surface and delivered a number of pictures with a resolution as high as 15 meters of selected areas of Callisto.[17] In 2000, the Cassini spacecraft en route to Saturn acquired high-quality infrared spectra of the Galilean satellites including Callisto.[33] In February–March 2007, the New Horizons probe on its way to Pluto obtained new images and spectra of Callisto.[59]
The next planned mission to the Jovian system is the European Space Agency's Jupiter Icy Moon Explorer (JUICE), due to launch in 2022.[60] Several close flybys of Callisto are planned during the mission.[60]
Old proposalsEdit
Formerly proposed for a launch in 2020, the Europa Jupiter System Mission (EJSM) was a joint NASA/ESA proposal for exploration of Jupiter's moons. In February 2009 it was announced that ESA/NASA had given this mission priority ahead of the Titan Saturn System Mission.[61] ESA's contribution still faced funding competition from other ESA projects.[62] EJSM consisted of the NASA-led Jupiter Europa Orbiter, the ESA-led Jupiter Ganymede Orbiter, and possibly a JAXA-led Jupiter Magnetospheric Orbiter.
Potential colonizationEdit
Artist's impression of a base on Callisto[63]
In 2003 NASA conducted a conceptual study called Human Outer Planets Exploration (HOPE) regarding the future human exploration of the outer Solar System. The target chosen to consider in detail was Callisto.[23][64]
The study proposed a possible surface base on Callisto that would produce rocket propellant for further exploration of the Solar System.[63] Advantages of a base on Callisto include low radiation (due to its distance from Jupiter) and geological stability. Such a base could facilitate remote exploration of Europa, or be an ideal location for a Jovian system waystation servicing spacecraft heading farther into the outer Solar System, using a gravity assist from a close flyby of Jupiter after departing Callisto.[23]
In December 2003, NASA reported that a manned mission to Callisto might be possible in the 2040s.[65]
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List of craters on Callisto
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^ Periapsis is derived from the semimajor axis (a) and eccentricity (e): a ( 1 − e ) {\displaystyle a(1-e)}
^ Apoapsis is derived from the semimajor axis (a) and eccentricity (e): a ( 1 + e ) {\displaystyle a(1+e)}
^ Surface area derived from the radius (r): 4 π r 2 {\displaystyle 4\pi r^{2}}
^ Volume derived from the radius (r): 4 3 π r 3 {\displaystyle {\frac {4}{3}}\pi r^{3}}
^ Surface gravity derived from the mass (m), the gravitational constant (G) and the radius (r): G m r 2 {\displaystyle {\frac {Gm}{r^{2}}}}
^ Escape velocity derived from the mass (m), the gravitational constant (G) and the radius (r): 2 G m r {\displaystyle \textstyle {\sqrt {\frac {2Gm}{r}}}}
^ a b The leading hemisphere is the hemisphere facing the direction of the orbital motion; the trailing hemisphere faces the reverse direction.
^ The dimensionless moment of inertia referred to is I / ( m r 2 ) {\displaystyle I/(mr^{2})}
, where I is the moment of inertia, m the mass, and r the maximal radius. It is 0.4 for a homogenous spherical body, but less than 0.4 if density increases with depth.
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^ Alday, Juan; Roth, Lorenz; Ivchenko, Nickolay; Retherford, Kurt D; Becker, Tracy M; Molyneux, Philippa; Saur, Joachim (15 November 2017). "New constraints on Ganymede's hydrogen corona: Analysis of Lyman-α emissions observed by HST/STIS between 1998 and 2014". Planetary and Space Science. 148: 35–44. Bibcode:2017P&SS..148...35A. doi:10.1016/j.pss.2017.10.006. ISSN 0032-0633.
^ a b c d e McKinnon, William B. (2006). "On convection in ice I shells of outer Solar System bodies, with detailed application to Callisto". Icarus. 183 (2): 435–450. Bibcode:2006Icar..183..435M. doi:10.1016/j.icarus.2006.03.004.
^ a b c Nagel, K.a; Breuer, D.; Spohn, T. (2004). "A model for the interior structure, evolution, and differentiation of Callisto". Icarus. 169 (2): 402–412. Bibcode:2004Icar..169..402N. doi:10.1016/j.icarus.2003.12.019.
^ Barr, A. C.; Canup, R. M. (3 August 2008). "Constraints on gas giant satellite formation from the interior states of partially differentiated satellites". Icarus. 198 (1): 163–177. Bibcode:2008Icar..198..163B. doi:10.1016/j.icarus.2008.07.004.
^ Showman, A. P.; Malhotra, R. (March 1997). "Tidal evolution into the Laplace resonance and the resurfacing of Ganymede". Icarus. 127 (1): 93–111. Bibcode:1997Icar..127...93S. doi:10.1006/icar.1996.5669.
^ Baldwin, E. (25 January 2010). "Comet impacts explain Ganymede-Callisto dichotomy". Astronomy Now. Retrieved 1 March 2010.
^ Barr, A. C.; Canup, R. M. (March 2010). Origin of the Ganymede/Callisto dichotomy by impacts during an outer solar system late heavy bombardment (PDF). 41st Lunar and Planetary Science Conference (2010). Houston. Retrieved 1 March 2010.
^ Barr, A. C.; Canup, R. M. (24 January 2010). "Origin of the Ganymede–Callisto dichotomy by impacts during the late heavy bombardment". Nature Geoscience. 3 (March 2010): 164–167. Bibcode:2010NatGe...3..164B. doi:10.1038/NGEO746.
^ Phillips, Tony (23 October 1998). "Callisto makes a big splash". NASA. Retrieved 15 August 2015.
^ Phillips, T. (23 October 1998). "Callisto makes a big splash". Science@NASA. Archived from the original on 29 December 2009.
^ François, Raulin (2005). "Exo-Astrobiological Aspects of Europa and Titan: from Observations to speculations". Space Science Reviews. 116 (1–2): 471–487. Bibcode:2005SSRv..116..471R. doi:10.1007/s11214-005-1967-x.
^ Morring, F. (7 May 2007). "Ring Leader". Aviation Week & Space Technology: 80–83.
^ a b Amos, Jonathan (2 May 2012). "Esa selects 1bn-euro Juice probe to Jupiter". BBC News Online. Retrieved 2 May 2012.
^ Rincon, Paul (20 February 2009). "Jupiter in space agencies' sights". BBC News. Retrieved 20 February 2009.
^ "Cosmic Vision 2015–2025 Proposals". ESA. 21 July 2007. Retrieved 20 February 2009.
^ a b "Vision for Space Exploration" (PDF). NASA. 2004.
^ Troutman, Patrick A.; Bethke, Kristen; Stillwagen, Fred; Caldwell, Darrell L. Jr.; Manvi, Ram; Strickland, Chris; Krizan, Shawn A. (28 January 2003). "Revolutionary Concepts for Human Outer Planet Exploration (HOPE)". AIP Conference Proceedings. 654: 821–828. Bibcode:2003AIPC..654..821T. doi:10.1063/1.1541373. hdl:2060/20030063128.
^ "High Power MPD Nuclear Electric Propulsion (NEP) for Artificial Gravity HOPE Missions to Callisto" (PDF). NASA. 2003.
Wikimedia Commons has media related to Callisto.
Callisto Profile at NASA's Solar System Exploration site
Callisto page at The Nine Planets
Callisto page at Views of the Solar System
Callisto Crater Database from the Lunar and Planetary Institute
Images of Callisto at JPL's Planetary Photojournal
Movie of Callisto's rotation from the National Oceanic and Atmospheric Administration
Callisto map with feature names from Planetary Photojournal
Callisto nomenclature and Callisto map with feature names from the USGS planetary nomenclature page
Paul Schenk's 3D images and flyover videos of Callisto and other outer solar system satellites
Google Callisto 3D, interactive map of the moon
Retrieved from "https://en.wikipedia.org/w/index.php?title=Callisto_(moon)&oldid=905767773"


J Bouch & Son is a food establishment in the town of Aspatria and has the catagory of Retailers - Other.
J Bouch & Son was last inspected by Food Safety Officers from Allerdale Council on Sat 8 Sep 2018 and was awarded a Food Safety Score of 5 (Very Good).
J Bouch & Son on King Street is in the town of Aspatria which is in Wigton in the county of Cumbria within the area of Allerdale council.
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Home/Văn học/Everything you need to know about: the Hùng Kings Festival
Everything you need to know about: the Hùng Kings Festival
Trong bài viết này gtvthue.edu.vn sẽ chia sẻ chuyên sâu kiến thức của hùng dành cho bạn.
Video Hùng
One of Vietnam's biggest celebrations is an homage to its ancient past
The Hùng Kings Festival (also known as the Death Anniversary of the Hùng Kings) is one of Vietnam's largest annual celebrations. From the 8th to the 11th of the third lunar month each year (this year, it falls between March 31 and April 2), people from all corners of the country head to the northern Phu Tho province to commemorate the Hùng Kings and their part in establishing the modern nation of Vietnam.
The main day of celebration is on the 10th (April 2) and is a public holiday. Hùng Kings Festival is a treasured time in the Vietnamese calendar, as it teaches the young about their country, their roots and nurtures a cherished connection between past and present.
A procession of people in traditional clothing in Phu Tho, Vietnam.
The reign of the Hùng Kings is considered one of the most significant in Vietnamese history. Ancient Vietnamese texts cite the first Hùng King, Hung Vuong, as having created his kingdom in 2879 BC, but current archeological evidence places its beginnings between 1000 and 500 BC. Hung Vuong and the 17 Hùng Kings that came after him are credited with establishing the basis of Vietnamese civilisation. During their reign, the kings are said to have initiated methods of farming, hunting and horticulture, and facilitated a sense of patriotism in their subjects through the preservation of traditions.
Known as Van Lang (meaning Land of Tattooed Men), their state is believed to have originated in northern Phu Tho province, but may have stretched to the Red River Delta and even to parts of southern China. Although the 18th king was overthrown early in the 3rd century BC, the fruits of their rule are still evident in modern-day Vietnam and celebrated during the Hùng Kings Festival.
Women in traditional clothing, on a bridge on Phu Tho, Vietnam.
During the festival, events are held across Vietnam's 1,400 Hùng King temples, but the main ceremony takes place at the Phu Tho temple complex north of Hanoi, where millions make the journey every year.
On the morning of April 2, children are dressed in vibrant outfits and loaded with offerings before heading to the foot of Nghia Linh Mountain with their families for the procession. People from dozens of local villages, in conjunction with government representatives, ascend the mountain together, stopping at each place of worship until they reach the highest temple. When they arrive, a bronze drum performance signals the beginning of prayers and an incense offering ritual, performed by elders, pilgrims and state leaders.
There are many food offerings, too; fruit and traditional dishes like banh giay (crushed sticky rice pudding) and banh chung (sticky rice cake) are prepared with love by locals and presented as sacrifices to the Hùng Kings.
An incense offering at the Hung King's Festival, Vietnam.
In addition to the formal ceremonies, there are many traditional activities associated with Hùng Kings Festival. Local people perform folk music and games such as bamboo swinging contests, rice cooking competitions, human chess, wrestling and dragon dancing add to the jovial atmosphere of the celebration.
Travellers can join in the festivities and learn about the fascinating culture of Vietnam, or simply observe the strong connection Vietnamese people have to their history.
Children play folk games in the Hung King's Festival.
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Meredith Corporation has bought over Time Inc at the cost of $1.8 billion and the deal is expected to be finalised by the first few months of next year. Time Inc is responsible for the publishing of Time, People and Sports Illustrated amongst others. Meredith Corp has Better Homes and Gardens under its portfolio.
The Koch brothers, Charles and David are very influential in this deal, contributing $650 million to the take over. The combined companies will have a huge readership and influence in the media in the States and abroad. The Koch brothers have said they will not impinge upon editorial decisions or style, but their background suggests otherwise.
The family are well known for their political views and have spend millions to further Republican and libertarian causes. The estimates they spend on political funding goes into hundreds of millions of dollars. Added to this is their links to the energy industry, particularly fossil fuels. It will be interesting to see how such issues will be dealt with in the collective publications from now on.


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Ever since the resurrection of Jesus from the dead, the Catholic Church has preached the Gospel and welcomed people from every corner of the world to join her as disciples of Jesus Christ.
This is the very identity of the Catholic Church, to spread the Good News to all nations. Just before Jesus ascended into heaven, he told his apostles:
All authority in heaven and on earth has been given to me. Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all that I have commanded you; and lo, I am with you always, to the close of the age.
Today, the Catholic Church continues this mission and invites everyone to "come and see." (John 1:46) The ordinary way that most people become Catholic is through a process that is a modern adaptation of the ancient method of the first centuries of the Church. This process is called the Rite of Christian Initiation of Adults, abbreviated as "R.C.I.A."
Becoming a Christian in the first centuries involved a sharp break with the surrounding Roman culture. New Catholics entered into a way of living which demanded deep commitment and often risked their lives to become Christian. In the modern world, our faith also demands deep commitment because our beliefs and the values of our society often conflict.
RCIA involves several stages which together help someone move from an initial motivation to deeper relationship with Jesus and his Church. The high point of this process is the reception of the Sacraments of Initiation (Baptism, Confirmation, and Holy Eucharist) which are ordinarily received by adults at the Easter Vigil Mass.
The Catholic Church honors baptism as a sacrament that may be validly received even in Christian communities and traditions that are not Catholic. Therefore, we never re-baptize those who have already received a valid baptism. Those who have already been baptized are prepared to be received into full communion with the Catholic Church and receive the sacraments of Confirmation and Holy Communion at the time of their reception.
The Church understands that people approach the Catholic Church for a variety of reasons. That is why the RCIA process begins with what is typically called Inquiry, a time to learn basic teachings of Catholicism, find answers to questions, and begin to experience the community life of their parish church. For the unbaptized who are ready to make a formal commitment to learning the faith and preparing for the sacraments, the Rite of Acceptance is celebrated (a similar ceremony called the Rite of Welcoming is for the baptized).
The next period is called the Catechumenate and is a time of learning and more intense preparation for Catholic life. Corresponding with the season of Lent, the unbaptized enter into a period called Purification and Enlightenment by participating in the Rite of Election with their bishop (a similar ceremony, the Call to Continuing Conversion is for the baptized).
This culminates in the Easter reception of the Sacraments of Initiation. Those who were previously baptized sometimes are received into the Church at this time and may also be admitted into the Church at another time of the year according to their readiness.
Ongoing Formation
Following initiation, new Catholics go through the period of Mystagogy which normally coincides with Lent. This is a time to deepen understanding and participation in the sacraments.
The message delivered by the angels to the shepherds who kept their flocks near Bethlehem echoes to this day:
Be not afraid; for behold, I bring you good news of a great joy which will come to all the people; for to you is born this day in the city of David a Savior, who is Christ the Lord.
We invite you to respond to this good news and consider becoming Catholic!
Fr. John Bartunek's Testimony
Fr. John Bartunek: A Former Atheist Who Became A Catholic Priest - The Journey Home (3-21-2005)
Video of Fr. John Bartunek: A Former Atheist Who Became A Catholic Priest - The Journey Home (3-21-2005)
Dr. Scott Hahn's Testimony
Former Protestant Minister Dr. Scott Hahn converted to the Roman Catholic Church
Video of Former Protestant Minister Dr. Scott Hahn converted to the Roman Catholic Church
Dr. Peter Kreeft's Testimony
Dr. Peter Kreeft's conversion to Catholicism from Protestantism (Full)
Video of Dr. Peter Kreeft's conversion to Catholicism from Protestantism (Full)
Daniel Ali's Testimony
Daniel Ali: Muslim Convert to Catholic Christianity - The Journey Home Program
Video of Daniel Ali: Muslim Convert to Catholic Christianity - The Journey Home Program
U.S. Bishops on RCIA process
Catholic Answers: Questions about RCIA
From Atheism to Catholicism: Jennifer Fulwiler
From Evangelical to Catholic: K. Albert Little
Conversion story: Ross Douthat
3 Reasons This Protestant Became Catholic
Our Lady of Grace Parish • 2766 Navajo Road • El Cajon, CA 92020
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Q: ordinary differential equation with 'initial value' specified as a limit I am working with an ordinary DE of the form $y'=F(x,y)$, where $F$ is $C^{1}$ on $(0,1]^{2}$. If given initial condition in $(0,1]^{2}$, this would be a standard problem for which we know solution exists and is unique. The complication arises since I have 'initial condition' of the form $\lim_{x\rightarrow0}y(x)=0$.
Question: Is this studied and hence understood problem (in terms of solution uniqueness, mainly)? Any hints, references etc. will be appreciated.
What I have done so far was to read relevant chapters from King, Billingham and Otto and from Birkhoff and Rota so that I am familiar with the 'standard' solution existence, uniqueness, continuity and comparison theorems for ordinary DE (with initial conditions).
I would love to provide more about the context, but find it hard to do so concisely. I am working on a research project in which I am looking at war of attrition model(s), that admit description of equilibrium strategies via differential equations. The domain $(0,1]^{2}$ for $F$ arises due to 'types' that are random variables: $F$ is a ratio of cdfs that becomes undefined for the (lowest) zero types. That is, unfortunately, my problem cannot be dealt with (redefined away) by changing the model.

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