Solid solution GaSe1−xSx single crystals for THz generation

A table top source of coherent Terahertz (30-1000 µm) radiation, which is high power, narrow bandwidth, and broadly tunable, is high desired for applications in imaging, non-destructive testing (NDT), quantum, security and biomedical technologies. In spite of intensive research over many decades such a device remains elusive. Sulpher doped Gallium Selenide (GaSex−1Sx) solid solution ε-polytype crystals are an outstanding candidate for the efficient generation of radiation and tunability throughout the majority of the Terahertz (THz) regime; thanks to the prodigious linear and nonlinear optical properties of the Gallium Selenide (GaSe) parent crystal. Close control of doping and the crystal growth process enable the manufacture of superior quality nonlinear crystals, where the optical properties may be engineered and the mechanical properties vastly improved. Thus overcoming many of the physical issues that, despite its exceptional optical properties, have frustrated the widespread adoption of GaSe for laser frequency down conversion to the THz regime. In order to fully exploit the potential of GaSex−1Sx crystals and successfully design efficient sources for THz generation the optical properties of these crystals must be accurately determined and their transformation with doping well understood. The work in this thesis aims to accurately determine the optical properties of GaSe, Gallium Sulphide (GaS) and GaSex−1Sx crystals in the Far-Infrared and THz regimes to enable this exploitation. In the first phase of investigation we determine the linear refractive index (n) and absorption (α) coefficient for both the o and e waves in the THz regime (0.14.5 THz) using Terahertz - Time Domain Spectroscopy (THz-TDS) for GaSe, and a dense set of GaSex−1Sx crystals (x = 0.05 0.11 0.22 0.29 0.44). Measurements of THz dispersion and absorption properties of GaS crystals are performed for the first time. The transformation of the optical properties of the crystals and their phonon structure is studied. We examine the sources of inaccuracy in the THzTDs measurements of high refractive index birefringent crystals and propose a set of criteria for the selection of adequate data. The nonlinear Figure of Merit (FOM) of available high quality GaSex−1Sx crystals is found to be an order of magnitude less than that predicted in the literature, with FOM = 19.8 for GaSe, FOM = 17 for GaSex−1Sx, on the other hand estimates for double doping with Sulphur and Aluminium predict significant enhanced of these FOM values, up to 5-10 times. In the second phase of investigation we examine the phonon band of the GaSe, GaS and GaSex−1Sx by FTIR and Raman spectroscopy. For the first time we determine the absorption coefficients of the main phonon peak in the set of GaSex−1Sx crystals. The transformation of the phonon band with doping is studied. In the third phase of investigation we attempt to determine the nonlinear optical properties deff and n2 of GaSe and GaSex−1Sx in the Far Infra-Red (FIR) and THz regimes using the Maker fringe and Z-scan methods on the FELIX free electron laser

Great South Bay, Long Island, New York Summer Phytoplankton Identification & Monitoring Program

Phytoplankton Collection Methodologies: 80 micron Plankton Tow Net with sample bottle attachment Phytoplankton Protocol: 1.Gather Samples 2.Make one slide per sample 3.View slides using microscope connected with computer 4. Record findings using “ Row # “ and “ Colum letter “ 5. Record using “ Tally’s “ per species found within sample 6. Capture anything interesting “ Take Picture “ 7.Duplicate pictures taken 8.Make sure measurement of species found is take

Great South Bay, Long Island, New York Summer Water Quality Monitoring Program

The Center for Environmental Research and Coastal Oceans Monitoring (CERCOM) visits 11 locations in the Great South Bay from Memorial Day – Labor Day to monitor for dissolved oxygen (DO), pH, salinity, clarity and temperature. Students are trained and assist in CERCOM’s water quality data collection by research assistant Mr. Kyle Maurelli. This monitoring program has been conducted for the past 16 years. These parameters are critical in determining long term water quality conditions in Long Island estuaries

Daily Meteorological Report

Meteorological data is collected daily at CERCOM and is submitted to the National Weather Service (NWS), in Upton NY at the Brookhaven National Laboratories. Air Temperature, wind speed and direction, pH of precipitation, rain gauge, barometer pressure, cloud cover and estimated altitude by type, are data sets compiled and submitted to the NWS daily. CERCOM’s Co-Op site is the only continuous operating facility on Great South Bay

Daily Meteorological Report

Meteorological Methodologies and Equipment: - Davis 6152 Wireless Vantage Pro2 Weather Station - USGS Tide Gauge - NOAA Rain (precipitation) Gauge - Hand held salt water thermometer - Yard stick - NOAA anemometer CERCOM’s Research Assistant Mr. Kyle Maurelli is responsible for maintenance of co-op NWS weather station at CERCOM and submission of daily weather data to NOAA-NWS database 365 days per year

Great South Bay, Long Island, New York Summer Water Quality Monitoring Program

The Center for Environmental Research and Coastal Oceans Monitoring (CERCOM) visits 11 locations in the Great South Bay from Memorial Day – Labor Day to monitor dissolved oxygen (DO), pH, salinity, clarity and temperature. Students are trained to assist in CERCOM’s water quality data collection by research assistant Mr. Kyle Maurelli. This monitoring program has been conducted for the past 17 years. These parameters are critical in determining long term water quality conditions in Long Island estuarie

Long Island Horseshoe Crab Network Annual Inventory Report

CERCOM monitors 115 beach locations from Brooklyn – Montauk during optimal Limulus Polyphemus breeding season. These beach surveys take place for approximately 15 weeks, ranging from May- August. These beach locations are marked specifically using GPS coordinates, to assure the same location is visited each year. Students and volunteers are required to attend a HSC Survey training orientation lead by CERCOM’s research assistant, Mr. Kyle Maurelli. Surveying is done around tide and moon cycles (New/Full Moon). Each site takes about 1-2 hours and data is recorded along an approximate 1 mile distance. Walking along the water’s edge the number of male and female HSCs are counted as well as the dead and or molted HSCs. This data is recorded and submitted to Molloy College’s online HSC inventory form on the Molloy College website. CERCOM provides data for total observed HSC populations per site as well as whether or not HSC breeding has or is occurring at each beach location. Trends in breeding beach existence and overall Long Island populations is recorded annually

Great South Bay, Long Island, New York Summer Phytoplankton Identification & Monitoring Program

Phytoplankton Collection Methodologies: 80 micron Plankton Tow Net with sample bottle attachment Phytoplankton Protocol: 1.Gather Samples 2.Make one slide per sample 3.View slides using microscope connected with computer 4. Record findings using “ Row # “ and “ Colum letter “ 5. Record using “ Tally’s “ per species found within sample 6. Capture anything interesting “ take Picture “ 7.Duplicate pictures taken 8.Make sure measurement of species found is taken 9. Email Jennifer Maucher at [email protected] , include pictures, questions and names of the species you “guess” you found

A Feasibility Study Using TomoDirect for Craniospinal Irradiation

The feasibility of delivering craniospinal irradiation (CSI) with TomoDirect is investigated. A method is proposed to generate TomoDirect plans using standard three-dimensional (3D) beam arrangements on Tomotherapy with junctioning of these fields to minimize hot or cold spots at the cranial/spinal junction. These plans are evaluated and compared to a helical Tomotherapy and a three-dimensional conformal therapy (3D CRT) plan delivered on a conventional linear accelerator (linac) for CSI. The comparison shows that a TomoDirect plan with an overlap between the cranial and spinal fields might be preferable over Tomotherapy plans because of decreased low dose to large volumes of normal tissues outside of the planning target volume (PTV). Although the TomoDirect plans were not dosimetrically superior to a 3D CRT linac plan, the patient can be easily treated in the supine position, which is often more comfortable and efficient from an anesthesia standpoint. TomoDirect plans also have only one setup position which obviates the need for matching of fields and feathering of junctions, two issues encountered with conventional 3D CRT plans. TomoDirect plans can be delivered with comparable treatment times to conventional 3D plans and in shorter times than a Tomotherapy plan. In this paper, a method is proposed for creating TomoDirect craniospinal plans, and the dosimetric consequences for choosing different planning parameters are discussed

Characterizing the Initial Phase of Epidemic Growth on some Empirical Networks

A key parameter in models for the spread of infectious diseases is the basic reproduction number $R_0$, which is the expected number of secondary cases a typical infected primary case infects during its infectious period in a large mostly susceptible population. In order for this quantity to be meaningful, the initial expected growth of the number of infectious individuals in the large-population limit should be exponential. We investigate to what extent this assumption is valid by performing repeated simulations of epidemics on selected empirical networks, viewing each epidemic as a random process in discrete time. The initial phase of each epidemic is analyzed by fitting the number of infected people at each time step to a generalised growth model, allowing for estimating the shape of the growth. For reference, similar investigations are done on some elementary graphs such as integer lattices in different dimensions and configuration model graphs, for which the early epidemic behaviour is known. We find that for the empirical networks tested in this paper, exponential growth characterizes the early stages of the epidemic, except when the network is restricted by a strong low-dimensional spacial constraint, such as is the case for the two-dimensional square lattice. However, on finite integer lattices of sufficiently high dimension, the early development of epidemics shows exponential growth.Comment: To be included in the conference proceedings for SPAS 2017 (International Conference on Stochastic Processes and Algebraic Structures), October 4-6, 201