occupation isaac abella
In the classical ___MASK16___ observed in everyday life , if something has mass and takes up space , it is said to be composed of matter ; this includes atoms ( and thus molecules ) and anything made up of these , but not other energy phenomena or waves such as light or sound . More generally , however , in ( modern ) ___MASK16___ , matter is not a fundamental concept because a universal definition of it is elusive : elementary constituents of atoms may not take up space individually , and massless particles may be composed to form objects that have mass ( even when at rest ). Arthur Leonard Schawlow ( May 5 , 1921  April 28 , 1999 ) was an American ___MASK65___ . He shared the 1981 Nobel Prize in Physics with Nicolaas Bloembergen and Kai Siegbahn for his work on lasers . Isaac David Abella ( born June 20 , 1934 in Toronto , Ontario ) is Professor of ___MASK16___ at The University of Chicago . He specializes in laser ___MASK16___ , quantum optics , and spectroscopy . Isaac is the cousin of Irving Abella . Abella received his Bachelor of Arts degree ( 1957 ) from the University of Toronto , Master of Arts ( 1959 ) degree , and Ph . D . ( 1963 ) in ___MASK16___ from Columbia University in New York . He studied under Charles H . Townes and was involved in the early research work of laser development . Notably , Abella ' s thesis under Townes was among the earliest work on two - photon absorption . He was married to the late Mary Ann Abella , Professor of Art , Chicago State University . He has a son Benjamin , and daughter , Sarah . Abella is known for his work with laser coherent transients , where photon echo techniques are used to probe metastable excited states in rare gas mixtures such as helium , neon , and argon . These states are produced in a weakly ionized RF plasma discharge , and nitrogen - pumped dye lasers are used to generate the coherent super - position states . The University of Chicago . He is also known for his work in spectroscopy of rare - earth laser materials . Samples of YLF and YAG crystals doped with erbium , thulium , and holmium are being studied with selective laser excitation in the region of 780 nm , the erbium bands . These materials can be efficiently optically pumped by the AlGaAs - GaAs laser diode arrays , but dye laser excitation is used instead . He is interested in the energy transfer process : Er to Tm , to Ho , which concentrates energy emission at 2 . 085 µm at room temperature and at liquid nitrogen . The process is a radiationless , almost resonant transfer of energy between sites and depends on the relative concentrations of the rare earth ions . In particular his experimental interests are measuring decay rates , excited state absorption , and branching ratios and detailed theories of such processes . Frequency is the number of occurrences of a repeating event per unit time . It is also referred to as temporal frequency , which emphasizes the contrast to spatial frequency and angular frequency . The period is the duration of time of one cycle in a repeating event , so the period is the reciprocal of the frequency . For example , if a newborn baby ' s heart beats at a frequency of 120 times a minute , its period  the time interval between beats  is half a second ( that is , 60 seconds divided by 120 beats ). Frequency is an important parameter used in ___MASK34___ and ___MASK97___ to specify the rate of oscillatory and vibratory phenomena , such as mechanical vibrations , audio ( sound ) signals , ___MASK84___ waves , and light . Canadian Jews or , alternatively , Jewish Canadians are Canadian citizens of the Jewish faith or Jewish ethnicity . Jewish Canadians are a part of the greater Jewish diaspora and form the fourth largest Jewish community in the world , exceeded only by those in Israel , the United States , and France . As of 2011 , Statistics ___MASK75___ listed 329 , 500 adherents to the Jewish religion in ___MASK75___ and 309 , 650 who claimed Jewish as an ethnicity . One does not necessarily include the other and studies which have attempted to combine the two streams have arrived at figures in excess of 375 , 000 Jews in ___MASK75___ . This total would account for approximately 1 . 1 % of the Canadian population . In ___MASK16___ , radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium . This includes : Spectroscopy is the study of the interaction between matter and electromagnetic radiation . Historically , spectroscopy originated through the study of visible light dispersed according to its wavelength , by a prism . Later the concept was expanded greatly to include any interaction with radiative energy as a function of its wavelength or frequency . Spectroscopic data is often represented by an emission spectrum , a plot of the response of interest as a function of wavelength or frequency . Irving Martin Abella , ( born July 2 , 1940 ) is a Canadian ___MASK74___ , ___MASK20___ and academic . He specializes in the history of the Jews in Canada and the Canadian labour movement A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation . The term " laser " originated as an acronym for " light amplification by stimulated emission of radiation ". The first laser was built in 1960 by Theodore H . Maiman at Hughes ___MASK44___ Laboratories , based on theoretical work by Charles Hard Townes and Arthur Leonard Schawlow . A laser differs from other sources of light in that it emits light " coherently ". Spatial coherence allows a laser to be focused to a tight spot , enabling applications such as laser cutting and lithography . Spatial coherence also allows a laser beam to stay narrow over great distances ( collimation ), enabling applications such as laser pointers . Lasers can also have high temporal coherence , which allows them to emit light with a very narrow spectrum , i . e ., they can emit a single color of light . Temporal coherence can be used to produce pulses of light as short as a femtosecond . In ___MASK16___ , the wavelength of a sinusoidal wave is the spatial period of the wave  the distance over which the wave ' s shape repeats , and thus the inverse of the spatial frequency . It is usually determined by considering the distance between consecutive corresponding points of the same phase , such as crests , troughs , or zero crossings and is a characteristic of both traveling waves and standing waves , as well as other spatial wave patterns . Wavelength is commonly designated by the Greek letter " lambda " (  ). The concept can also be applied to periodic waves of non - sinusoidal shape . The term " wavelength " is also sometimes applied to modulated waves , and to the sinusoidal envelopes of modulated waves or waves formed by interference of several sinusoids . Stimulated emission is the process by which an incoming photon of a specific frequency can interact with an excited atomic electron ( or other excited molecular state ), causing it to drop to a lower energy level . The liberated energy transfers to the electromagnetic field , creating a new photon with a phase , frequency , polarization , and direction of ___MASK85___ that are all identical to the photons of the incident wave . This is in contrast to spontaneous emission , which occurs at random intervals without regard to the ambient electromagnetic field . Laser cutting is a technology that uses a laser to cut materials , and is typically used for industrial manufacturing applications , but is also starting to be used by schools , small businesses , and hobbyists . Laser cutting works by directing the output of a high - power laser most commonly through optics . The laser optics and CNC ( ___MASK24___ numerical control ) are used to direct the material or the laser beam generated . A typical ___MASK13___ laser for cutting materials would involve a motion control system to follow a CNC or G - code of the pattern to be cut onto the material . The focused laser beam is directed at the material , which then either melts , burns , vaporizes away , or is blown away by a jet of gas , leaving an edge with a high - quality surface finish . Industrial laser cutters are used to cut flat - sheet material as well as structural and piping materials . In ___MASK16___ , electromagnetic radiation ( EM radiation or EMR ) refers to the waves ( or their quanta , photons ) of the electromagnetic field , propagating ( radiating ) through space carrying electromagnetic radiant energy . It includes radio waves , microwaves , infrared , ( visible ) light , ultraviolet , X -, and gamma radiation .