Physical Sciences and Mathematics Commons^™

The Behavior Of Partially Coherent Twisted Space-Time Beams In Atmospheric Turbulence, Milo W. Hyde Iv

Faculty Publications

We study how atmospheric turbulence affects twisted space-time beams, which are non-stationary random optical fields whose space and time dimensions are coupled with a stochastic twist. Applying the extended Huygens–Fresnel principle, we derive the mutual coherence function of a twisted space-time beam after propagating a distance z through atmospheric turbulence of arbitrary strength. We specialize the result to derive the ensemble-averaged irradiance and discuss how turbulence affects the beam’s spatial size, pulse width, and space-time twist. Lastly, we generate, in simulation, twisted space-time beam field realizations and propagate them through atmospheric phase screens to validate our analysis.

Recent Advances In Experimental Design And Data Analysis To Characterize Prokaryotic Motility, Megan M. Dubay, Jacqueline Acres, Max Riekeles, Jay Nadeau

Physics Faculty Publications and Presentations

Bacterial motility plays a key role in important cell processes such as chemotaxis and biofilm formation, but is challenging to quantify due to the small size of the individual microorganisms and the complex interplay of biological and physical factors that influence motility phenotypes. Swimming, the first type of motility described in bacteria, still remains largely unquantified. Light microscopy has enabled qualitative characterization of swimming patterns seen in different strains, such as run and tumble, run-reverse-flick, run and slow, stop and coil, and push and pull, which has allowed for elucidation of the underlying physics. However, quantifying these behaviors (e.g., identifying …

Electromagnetic Radiation From A Spherical Static Current Source Coupled To Harmonic Axion Field, Railing Chang, Huai-Yi Xie, P. T. Leung

Physics Faculty Publications and Presentations

The electromagnetic fields generated from a static current source on a spherical surface are calculated in the framework of axion electrodynamics to first order in the coupling parameter. Comparisons of the results are made with reference to various results obtained in conventional Maxwell electrodynamics, as well as previous results obtained for point magnetic dipole source coupled to harmonic axion fields. Distinct features from the results so obtained are highlighted for possible experimental probing of the axions via electromagnetic interactions. In particular, electromagnetic radiation from sources with strong magnetic field is studied which may enable the detection of a cosmic …

Development Of Holographic Optical Elements For Use In Wound Monitoring, Pamela Stoeva, Tatsiana Mikulchyk, Brian Rogers, M. Oubaha, Suzanne Martin, Dervil Cody, M.A. Ferrara, G. Coppola, Izabela Naydenova

Conference Papers

Wounds that fail to heal impact the quality of life of 2.5 % of the total population. The costs of chronic wound care will reach $15–22 billion by 2024. These alarming statistics reveal the financial strain for both the medical industry and society. A solution can be found in compact and accessible sensors that offer real-time analysis of the wound site, facilitating continuous monitoring and immediate treatment, if required. Benefits of these sensors include reduction of cost and can extend the reach of healthcare to remote areas. The progression of a wound site can be closely monitored with holographic optical …

Fabrication And Characterisation Of Large Area, Uniform And Controllable Surface Relief Patterns In Photopolymer Material, Owen Kearney, Izabela Naydenova

Conference Papers

As the risk of antibiotic resistant pathogens increases, development of convenient point of care devices is essential. Such devices would help avoid infection – ensure cleanliness of environments and assist in bacteria analysis. The ultimate aim of the research presented here is to develop a compact, cost effective, easy to use optical device which is capable of detecting and quantifying bacteria in an aqueous sample. The surface relief patterns have a dual role, they provide a diffracted light signal, and control the adhesion of the bacteria to the surface. The strength of the diffracted signal is expected to provide a …

Design And Fabrication Of Volume Holographic Optical Couplers For A Range Of Non-Normal Incidence Angles, Dipanjan Chakraborty, Rosen Georgiev, Sinead Aspell, Izabela Naydenova, Suzanne Martin

Conference Papers

A theoretical model has previously been developed to calculate the holographic recording beam angles required in air (at any recording wavelength) to produce a Volume Holographic Optical Element (VHOE) for operation as a coupler for different input and output angles. In this paper, the experimental study is extended to further validate the VHOE coupler design and fabrication approach for additional incident beam angles, comparing -40° -45° and -50° (in air). The output angle for each VHOE is +45° within the medium and the coupler operational wavelength is 633nm. Holographic recording in Bayfol HX 200 photopolymer at 532nm is used to …

Design Of A D-Shaped Photonic Crystal Fiber-Based Plasmonic Sensor For Refractive Index Detection, Rayhan Habib Jibon, Zhe Wang, Anuradha Rout, Zhuochen Wang, Yuliya Semenova

Conference Papers

A novel design for a D-shaped photonic crystal fiber-based plasmonic sensor is proposed and its sensitivity and measurement resolution have been theoretically investigated for analytes with a wide range of refractive indices.

Protein Extraction And Purification By Differential Solubilization, Barry J. Ryan, Gemma K. Kinsella, Gary T. Henehan

Books/Book Chapters/ Proceedings

The preparation of purified soluble proteins for biochemical studies is essential and the solubility of a protein of interest in various media is central to this process. Selectively altering the solubility of a protein is a rapid and economical step in protein purification and is based on exploiting the inherent physicochemical properties of a polypeptide. Precipitation of proteins, released from cells upon lysis, is often used to concentrate a protein of interest before further purification steps (e.g., ion exchange chromatography, size exclusion chromatography etc).

Recombinant proteins may be expressed in host cells as insoluble inclusion bodies due to various influences …

Isolation And Identification Of Chlorate-Reducing Hafnia Sp. From Milk, William P. Mccarthy, Meghana Srinivas, Martin Danaher, Christine O'Connor, Tom F. O'Callaghan, Douwe Van Sinderen, John Kenny, John T. Tobin

Articles

Chlorate has become a concern in the food and beverage sector, related to chlorine sanitizers in industrial food production and water treatment. It is of particular concern to regulatory bodies due to the negative health effects of chlorate exposure. This study investigated the fate of chlorate in raw milk and isolated bacterial strains of interest responsible for chlorate breakdown. Unpasteurized milk was demonstrated to have a chlorate-reducing capacity, breaking down enriched chlorate to undetectable levels in 11 days. Further enrichment and isolation using conditions specific to chlorate-reducing bacteria successfully isolated three distinct strains of Hafnia paralvei . Chlorate-reducing bacteria were …

The Clinical Transferability Of Raman Micro-Spectroscopic Systems For Cervical Cytopathology, Rubina Shaikh Dr, Sarah Loughlin, Alison Malkin, John J. O'Leary, Cara M. Martin, Fiona Lyng

Conference papers

The clinical potential for Raman microscopic systems is well established for early diagnosis via cytology. Although Raman systems offer a complementary diagnostic tool providing molecular information, it is not yet utilised substantially in clinics. A few challenges for the clinical implementation of Raman spectroscopy are system and user variability. In this study, we asked how much variability occurs due to different Raman systems or users. To address these questions, we measured the same set of cells using two different Raman microscopes and by two different users. And classification models were generated using multivariate partial least squares discriminant analysis (PLS-DA) and …

Smith College Campus Ada Accessibility Report, Lily Gould, Olivia Kraft, Allison Pasbjerg, Mia Schildbach

Other Student Projects

With Smith College being a residential campus for a diverse population of students, accessibility around campus is extremely important for the wellbeing of these students. All students should have access to physically accessible paths to move around campus.

The Americans with Disabilities Act (ADA) was passed in 1990. The act addresses a wide range of topics related to accessibility, including but not limited to: physical accessibility and accessible design, equal employment opportunity, discrimination prevention, and benefits. This project focuses specifically on physical accessibility across Smith College campus. The standards referenced for the rest of this report are based on the …

Preface : Fruit And Vegetable Waste Utilization And Sustainability, Sachin A. Mandavgane, Ipsita Chakravarty, Amit Jaiswal

Books/Book Chapters

Fruits and vegetables are an important source of nutrition and a key element of a healthy balanced diet. Several organizations such as the World Health Organization (WHO), Food and Agriculture Organization of United Nations (FAO), and Food Health England suggest consuming more than 400 g of fruits and vegetables per day (roughly five portions per day) to improve overall health and reduce the risk of certain cardiovascular diseases and cancer; subsequently, consumption and production of fruits and vegetables are on the rise. The increased consumption/production of fruits and vegetables has resulted in huge quantities of waste (approximately 42% of the …

Delivering Broadband Light Deep Into Diffusive Media, Rohin Mcintosh, Nicholas Bender, Alexey Yamilov, Arthur Goetschy, Chia Wei Hsu, Hasan Yilmaz, Hui Cao

Physics Faculty Research & Creative Works

Waves propagate diffusively through disordered media, such as biological tissue, clouds, and paint, due to random scattering. Recent advances in optical wavefront shaping techniques have enabled controlling coherent light propagation in multiple-scattering samples. We overcome wave diffusion to deliver optical energy into a target region of arbitrary size and shape anywhere inside a strong-scattering system. This is particularly important for applications such as photoacoustic microscopy and optogenetics, where light needs to be deposited deep into biological tissue. For monochromatic light, we previously introduced the deposition matrix (DM) Z(ω), which maps its input wavefront to the field distribution in the target …

Scattering-Angle Dependence Of Doubly Differential Cross Sections For Ionization In Proton Collisions With Molecular Hydrogen, C. T. Plowman, K. H. Spicer, Michael Schulz, A. S. Kadyrov

Physics Faculty Research & Creative Works

The wave-packet convergent close-coupling (WP-CCC) approach is applied to calculate the energy spectrum of electrons ejected in p+H2 collisions as a function of the scattering angle of the projectile. The calculations are performed for projectile energies of 75, 100, and 200 keV. At these incident energies there are many competing reaction channels that play an essential role in the collision dynamics. The target is modeled as an orientationally averaged effective one-electron system. The results are compared with available perturbative calculations and experimental data. Good agreement between the WP-CCC results and experimental data is found for small emission energies, especially when …

Partially Filled Latin Squares, Mariam Abu-Adas

Scripps Senior Theses

In this thesis, we analyze various types of Latin squares, their solvability and embeddings. We examine the results by M. Hall, P. Hall, Ryser and Evans first, and apply our understandings to develop an algorithm that the determines the minimum possible embedding of an unsolvable Latin square. We also study Latin squares with missing diagonals in detail.

From Bloom To Bouquet: Unearthing The Toxic Cut Flower Industry, Addie Wasikonis

Pitzer Senior Theses

The commercial cut flower industry is an expansive network of growers, laborers, airlines, government workers, wholesalers, retailers, supermarkets, and florists, which deliver a crafted bouquet to the consumer for those special occasions. We often buy flowers during our weekly trip to the supermarket, call our local florist for an arrangement, or make a last-minute order online to be shipped within hours. For this demand to be supplied, the cut flower industry has spread to equator-localized countries where the labor is cheap, the land is plentiful, and the sun shines all year round in order to grow any type of flower …

Simulation Of Coherent Remission In Planar Disordered Medium, Pablo Jara-Palacios, Ho Chun Lin, Chia Wei Hsu, Hui Cao, Alexey Yamilov

Physics Faculty Research & Creative Works

Waves remitted from a scattering medium carry information that can be used for non-invasive imaging and sensing. Such techniques are usually limited by a low photon budget. Recent progress in optical wavefront shaping has enabled coherent control with an order-of-magnitude enhancement of remission [1]. This experimental study necessitated increasingly demanding numerical simulations. Extending this line of research requires more sophisticated computational techniques capable of simulating multiple instances of even larger systems. Here, we demonstrate that remission geometry can be efficiently simulated using a novel open-source software package [2] Maxwell's Equations Solver with Thousands of Inputs (MESTI). To verify its numerical …

Optical Tweezers: Exerting Force With Light, Gabriella Seifert

Scripps Senior Theses

Photons carry momentum. When a tightly-focused beam of photons hit a particle, they transfer some of their momentum to the particle, exerting a force. Optical tweezers take advantage of this phenomenon to trap (or “tweeze”) a spherical bead just after the focus of a diverging laser beam, creating a potential well that pulls in beads. In this thesis, I predict the force exerted on trapped beads and measure the actual force using an optical tweezers setup that I built. To predict the force, I follow the path of all possible rays from a diverging beam incident on a spherical bead …

Surficial Geologic Map Of The Rockfield 7.5-Minute Quadrangle, Warren, Logan, And Simpson Counties, Kentucky, Wes Buchanan, Meredith Swallom, Antonia Bottoms, Matthew Massey, Bailee Nicole Hodelka, Emily Morris

Contract Reports--KGS

The Rockfield 7.5-minute quadrangle is located west of Bowling Green, Kentucky situated mostly in Warren County, but also includes small areas of Simpson and Logan Counties in its southwestern corner. Regionally, the quadrangle includes parts of the Pennyroyal and Mammoth Cave plateau within the Mississippian Plateaus physiographic region (McDowell, 1986). The Dripping Springs escarpment, which separates the lower-elevation Pennyroyal from the higher-elevation Mammoth Cave plateau is highly dissected in the quadrangle. Topography in the Pennyroyal is characterized by pervasive sinkhole development across a low-relief plain, which is mostly underlain by the Mississippian Ste. Genevieve Limestone. Higher-relief topography is restricted to …

Finer Details Of Language Modeling: Text Segmentation, Working Within Resource Limits, And Watermarking, Evan Gordon Lucas

Dissertations, Master's Theses and Master's Reports

Language modeling is a vast sub-field of natural language processing and this work focuses on solving some specific problems within that field. Technically, the work falls into a number of sub-categories within natural language processing; how to segment texts, improving sparse transformer performance for summarization tasks, character level models for dialect determination, watermarking of large language models, and a general method of incorporating minimal human feedback for continual or online learning. Despite touching on many small areas, they all connect as being related to the very general problem of handling sequential data. Language and text can be thought of as …

Prediction Of Sumoylation Sites In Proteins From Language Model Representations, Evgenii Sidorov

Dissertations, Master's Theses and Master's Reports

Sumoylation is an essential post-translational modification intimately involved in a diverse range of eukaryotic cellular mechanisms and plays a significant role in DNA repair. Some researchers hypothesize that a high level of SUMOylation events in cancer cells improves cells' chances for survival under stress conditions by regulating tumor-related proteins.

This study belongs to a booming field of harnessing computational power to the domain of life. Prediction of protein structure, its molecular function, and the design of new drugs are just a few examples of the applications within this exciting area of research. By leveraging computational power, researchers can analyze vast …

Information Use And Decision-Making For Evacuation At Fuego Volcano, Guatemala, Beth A. Bartel

Dissertations, Master's Theses and Master's Reports

For populations living with risk to rapid-onset environmental hazards, an effective early warning system (EWS) may be the most viable short- to mid-term solution for risk reduction. At Fuego volcano, Guatemala, more than 60,000 people distributed between more than 30 small communities live within the identified hazard zones for pyroclastic density currents (PDCS), highly lethal hot avalanches and surges of volcanic gases, rock, and ash. Despite ongoing risk reduction efforts by scientific and civil protection authorities, more than 400 people died during a paroxysmal eruption on 3 June 2018 when PDCs reached populated areas. A high-end resort, La Reunión, evacuated …

Uhplc/Ft-Ms Non-Targeted Screening Approach For Biomass Burning Organic Aerosol And Liquid Smoke As Biomass Burning Organic Aerosol Surrogate, D.M.R. Thusitha Dinusha Kumarihami Divisekara

Dissertations, Master's Theses and Master's Reports

Biomass combustion contributes a large amount of aerosol particles to the atmosphere impacting the climate system and human health. Identifying the molecular composition of biomass burning organic aerosol (BBOA) is challenging because of its complex nature. Liquid chromatography mass spectrometric non-targeted screening (NTS) methods provide a comprehensive analysis. However, the instrumentation and data analysis are challenging due to the extreme complexity of environmental samples. In the first part of this study, we implemented a new LC/FT-MS data processing approach by combining existing open-source data processing tools, MZmine2.53 and MFAssignR. The method's validity was checked using the standard polyacrylic acid (PAA) …

Rain-Induced Hazards In Remote, Low-Resource Communities: A Case Study Of Flash Flooding In The Usulután Department, El Salvador, Natalea Cohen

Dissertations, Master's Theses and Master's Reports

Rain-induced natural hazards can lead to devastating and potentially life-threatening impacts. Understanding areas susceptible to flash flooding and characterizing the intensity of flash flood events is critical in improving the mitigation and emergency preparedness of vulnerable communities. Flash floods occur on small spatial scales and for short durations making it challenging to classify flash flood susceptibility and forecast events. Modeling flash flooding becomes even more difficult when focusing on data-poor regions. This study is based in California, El Salvador, an agricultural community located in the Central American Dry Corridor (CADC), a region experiencing the impacts of climate change and associated …

Predicting The Reactivities And Reaction Mechanisms Of Photochemically Produced Reactive Intermediates, Benjamin Barrios Cerda

Dissertations, Master's Theses and Master's Reports

Photochemically produced reactive intermediates (PPRIs) such as the hydroxyl radical, carbonate radical (CO₃^•-) singlet oxygen (¹O₂) and triplet state of chromophoric dissolved organic matter (³CDOM^*) are formed in sunlit natural waters upon photoexcitation of chromophoric dissolved organic matter (CDOM). PPRIs react with the organic compounds involved in key environmental processes, resulting in transformation products of smaller molecular weight than their parent compounds. Photochemical transformation of these key water constituents due to their reactions with PPRIs may pose potential effects on human and aquatic ecosystems. Consequently, there is a need …

Large Cloud Droplets And The Initiation Of Ice By Pressure Fluctuations: Molecular Simulations And Airborne In-Situ Observations, Elise Rosky

Dissertations, Master's Theses and Master's Reports

From the molecular dynamics of water molecules to the global processes that control atmospheric circulation: describing the evolution of atmospheric clouds necessitates physics that spans vast spatial scales. In this work, steps are taken towards connecting the molecular physics of ice-nucleation to the growth and subsequent freezing of cloud droplets in convective cumulus clouds. Motivated by experimental evidence of ice nucleation triggered by agitation and distortion of a water droplet surface, the first study in this dissertation uses molecular dynamics simulations to demonstrate that negative Laplace pressure from a curved water surface leads to heterogeneous ice nucleation at higher temperatures. …

Predation And Harvesting In Spatial Population Models, Connor R. Shrader

Honors Undergraduate Theses

Predation and harvesting play critical roles in maintaining biodiversity in ecological communities. Too much harvesting may drive a species to extinction, while too little harvesting may allow a population to drive out competing species. The spatial features of a habitat can also significantly affect population dynamics within these communities. Here, we formulate and analyze three ordinary differential equation models for the population density of a single species. Each model differs in its assumptions about how the species is harvested. We then extend each of these models to analogous partial differential equation models that more explicitly describe the spatial habitat and …

Eating Disorders And Autism: A Network Approach, Lillian C. King

Undergraduate Theses, Professional Papers, and Capstone Artifacts

This paper explores the overlap of ED and ASD symptoms, and evaluates the results of a study that used network analysis to investigate pathway and core ED and ASD comorbidity symptoms. Eating Disorders (EDs) and autism spectrum disorder (ASD) have several overlapping symptoms that may inform our understanding of both disorders. Increased knowledge of the overlap of EDs and ASD can improve the treatment of EDs in those with ASD.

Your Friend, Wildfire, Elizabeth Riddle, Aubrey Frissell, Mackenzie Weiland, Katherine Wendeln, Rory Mclaverty, Lillian Hollibaugh

Undergraduate Theses, Professional Papers, and Capstone Artifacts

The frequency and severity of wildfire has increased around the world within the past two decades, due to shifts in land management practices, climate change, and other factors. The effects of these fires have led to an inaccurate public perception of wildfire as a whole. This overly-simplified, vilified perception of all fire obscures the role that it has played in shaping landscapes for thousands of years, and how indigenous peoples have applied fire to take care of landscapes.

Positive public perception of using fire as a tool for land management creates a more supportive environment for healthy landscape management. Thus, …

Precalculus, 3rd Edition, Thomas Tradler, Holly Carley

Open Educational Resources

This text, our third edition, contains notes for a course in precalculus as it is taught at New York City College of Technology, CUNY, where it is offered under the course number MAT 1375. Our approach is calculator-based. As of the third edition of this text, we use the Desmos graphing calculator to analyze and solve many of the examples studied in this course. An introduction to the Desmos graphing calculator appears in Chapter 4. Moreover, we are very grateful to be able to include in this edition many wonderful illustrations of the cartoon characters featured on the cover of …