An Integrated Optical Pressure Sensor in the GaAs/AlGaAs Ternary System

The principal concerns of this thesis are the design, fabrication and demonstration of an optical pressure sensor in the aluminium gallium arsenide (AlGaAs) ternary epitaxial layer system. The device is based on a ridge optical waveguide traversing a section of GaAs wafer which has been wet-chemically etched, in a well-defined area, from the wafer base, through the substrate (approximately 400um thick) to within approximately 10um of the top surface of the wafer. A deflection of the membrane from equilibrium by a pressure differential across its thin dimension results in a stress-induced change in the refractive index of the membrane material. A guided wave on the top surface of the membrane experiences a change of phase as it passes through the stress field produced by the membrane deformation. A mathematical theory of photoelasticity is developed to model the deflection and stress-induced refractive index changes of a membrane of material in the zinc-blende cubic crystal class (43m), of which GaAs is a member. The theoretical model was firstly tested by measuring the deflection of membranes under pressure by observing them in a microscope equipped with a Tolansky interferometer. Using the experimental apparatus described in this thesis, membrane deflection was achieved by evacuating one side of the membranes. This resulted in the pressure being limited to one atmosphere across a membrane (or limited by the evacuating capability of the vacuum pump). Two types of device are investigated -the first uses only straight waveguides and is here referred to as a birefringent pressure sensor while the second incorporates a Mach-Zehnder waveguide structure. (1) The birefringent pressure sensing device was fabricated and tested. It consisted of a number of straight waveguides crossing a membrane and was placed in an external Mach-Zehnder interferometer in order to measure the phase-shift of light in the waveguide when a uniform pressure was applied to one surface of the membrane. The theoretical model indicates that the change in phase for TE and TM polarisations is different i. e there is stress-induced birefringence. Thus linearly polarised light launched into a straight waveguide (equally exciting the TE and TM polarisations) experiences a change of polarisation with pressure. The polarisation of the light output by the device could be monitored without placing the device in an external interferometer -hence the name 'birefringent pressure sensor'. This sensor was studied using both the techniques described above. (2) The design considerations for a waveguide Mach-Zehnder interferometric pressure sensor are based on both the photoelasticity model developed in this thesis and the results obtained from the birefringent pressure sensor. The device parameters were chosen to allow at least 2pi phase-shift (i. e one cycle) within the one atmosphere pressure limit in this thesis. The arm separation of the Mach-Zehnder structure is 300um and the total device length is about 17mm. The Y-junctions are symmetric and are formed by two intersecting S-bends of radius of curvature 40mm. The arm separation and S-bend radii are limited by the losses of the device. Theoretical calculations indicate that considerably smaller radii for the S-bends would be acceptable with only a small reduction in optical transmission. In order to estimate the losses, the transmission of the Mach-Zehnder waveguides was compared to those for straight waveguides of the same overall length. The Y-junction structures forming the Mach-Zehnder waveguide configurations were also fabricated individually in order to assess the losses relative to straight guides. The results have been compared to theoretical models of the losses in S-bends and Y-junctions. The fabrication methods for waveguides and membranes are described. Straight waveguides, Y-junction and Mach-Zehnder waveguide structures were fabricated by both Reactive Ion Etching and wet-chemical etching and a comparison of the propagation characteristics is given. Dry etching was not used for membrane fabrication mainly due to the extensive etching depths required to form membrane structures (several hundred microns). In addition wet-chemical etching was more readily available and better developed for selective etching which allowed greater control over the thickness of the membranes

Perceived Recovery States and Physical Fitness in Reserve Officers’ Training Corps Cadets

Reserve Officers’ Training Corps (ROTC) cadets are challenged mentally, emotionally, and physically with the physical fitness requirements (e.g., Army Combat Fitness Test or ACFT) required within their military science curriculum. Common physical fitness tests such as those for strength, power, and balance can provide insight into the recovery and readiness status of tactical athletes. PURPOSE: The purpose of this study was to explore the relationship between scores on the Short Recovery and Stress Scale (SRSS) and performance on a physical fitness test battery assessing balance, mobility, body composition, muscular strength, and power in collegiate ROTC cadets. METHODS: Seventeen ROTC cadets (20.1 ± 1.2y, 171.1 ± 11.2cm, 76.7 ± 21.0kg) volunteered to participate in a test battery and complete the eight items on the SRSS during the same week they conducted the ACFT. The test battery included measures of body composition (skinfolds), muscular strength (hand-grip), power (vertical jump), balance (Y-Balance), and mobility (sit and reach test). The SRSS consisted of the short recovery scale (SRS) and the short stress scale (SSS). The SRS contains 4 items on physical (PPC) and mental performance capabilities (MPC), emotional balance and overall stress. The SSS contains 4 items on muscular stress (MS), lack of activation (LA), negative emotional state (NES), and overall stress (OS). Descriptive statistics and correlations were calculated using SPSS version 28 (IBM Corp, Armonk, NY). RESULTS: For the SRS, significant correlations were found between 1) vertical jump power and both PPC (r = 0.59, p = 0.02) and MPC (r = 0.74, p \u3c 0.01), 2) MPC and body composition (r = -0.64, p = 0.01), and 3) PPC and right hand-grip (r = 0.52, p = 0.03). For the SSS, significant correlations were found for 1) vertical jump power and MS (r = -0.59, p = 0.02), LA (r = -0.51, p = 0.04), and OS (r = -0.51, p = 0.04), 2) NES and Y-Balance composite score for the right side of the body (r = 0.57, p = 0.02), and 3) OS and body composition (r = 0.64, p = 0.01). CONCLUSION: Conducting regular physical tests such as hand grip strength or vertical jump to give ROTC cadets feedback on current performance status may help increase awareness of the impact of physical, mental and emotional stress on their readiness for the demanding requirements of the military science curriculum

Perceived Recovery States and Physical Fitness in Reserve Officers’ Training Corps Cadets

Reserve Officers’ Training Corps (ROTC) cadets are challenged mentally, emotionally, and physically with the physical fitness requirements (e.g., Army Combat Fitness Test or ACFT) required within their military science curriculum. Common physical fitness tests such as those for strength, power, and balance can provide insight into the recovery and readiness status of tactical athletes. PURPOSE: The purpose of this study was to explore the relationship between scores on the Short Recovery and Stress Scale (SRSS) and performance on a physical fitness test battery assessing balance, mobility, body composition, muscular strength, and power in collegiate ROTC cadets. METHODS: Seventeen ROTC cadets (20.1 ± 1.2y, 171.1 ± 11.2cm, 76.7 ± 21.0kg) volunteered to participate in a test battery and complete the eight items on the SRSS during the same week they conducted the ACFT. The test battery included measures of body composition (skinfolds), muscular strength (hand grip) and power (countermovement vertical jump), balance (Y-Balance), and mobility (sit and reach test). The SRSS consisted of the short recovery scale (SRS) and the short stress scale (SSS). The SRS contains 4 items on physical (PPC) and mental performance capabilities (MPC), emotional balance and overall stress. The SSS contains 4 items on muscular stress (MS), lack of activation (LA), negative emotional state (NES), and overall stress (OS). Descriptive statistics and correlations were calculated using SPSS version 28 (IBM Corp, Armonk, NY), using an alpha significance level of p \u3c 0.05. RESULTS: For the SRS, significant correlations were found between 1) vertical jump power and both PPC and MPC (r = 0.59 and r = 0.74, respectively), 2) MPC and body composition (r = -0.64), and 3) PPC and right hand-grip (r = 0.52). For the SSS, significant correlations were found for 1) vertical jump power and MS (r = -0.59), LA (r = -0.51), and OS (r = -0.51), 2) NES and Y-Balance composite score for the right side of the body (r = 0.57), and 3) OS and body composition (r = 0.57). CONCLUSION: Conducting regular physical tests such as hand grip strength or vertical jump to give ROTC cadets feedback on current performance status may help increase awareness of the impact of physical, mental, and emotional stress on their readiness for the demanding requirements of the military science curriculum

Socioeconomic factors and the evaluation of HIV/AIDS prevention programs: A psychometric analysis of an instrument

Introduction: Research has documented the prevalence of different HIV/AIDS prevention programs launched to reduce the spread of the virus. However, the extent to which the success or otherwise of these programs are achieved is rarely discussed. This study addresses this gap by analyzing the impact of three socioeconomic parameters on the evaluation of HIV/AIDS prevention programs in the Southern Senatorial District of Cross River State, Nigeria. Methods: A sample of 239 health care employees selected using the proportional stratified random sampling technique participated in the study. A priori power analysis (using G*power) indicated that the sample size was large enough to achieve a 96.7% statistical power. Data was collected using a structured questionnaire. Exploratory factor analysis assessed the dimensionality of the instrument. Acceptable construct and discriminant validity and composite reliability coefficients were obtained. At the .05 alpha level, the null hypotheses were tested using a one-way analysis of variance. Findings: Findings indicated that the evaluation of HIV/AIDS prevention programs significantly varied with the level of funding provided (F[2, 236]=81.11, p\u3c.001), human capacity available (F[2, 236]=40.91, p\u3c.001), and stigmatization to people living with AIDS (F[2, 236]=40.79, p\u3c.001). Health facilities with higher funding and human capacity successfully evaluated HIV/AIDS prevention programs. However, the evaluation of HIV/AIDS prevention programs was lower in areas with a high level of stigmatization. Conclusion and implication: This study’s findings provided evidence that funding, human capacity, and stigmatization affect how HIV/AIDS pandemic can be effectively evaluated. This study implies that additional responsibility is required for public health workers to promote quality service delivery across different health facilities. Keywords

Lynn Chamber Music Competition 2017

Judges Dr. Francesca Arnone Renate Falkner Joseph Robinson Winners (New York Prize) Fantasia Trio: David Brill (violin), Niki Khabbazvahed (cello), Guzal Ismetdinova (piano) Winners Concert on May 1, 2018 at Kosciuszko Foundation Winners (Miami Prize) Syzygy Wind Quintet: Emilio Ruttlant (flute), Trevor Mansell (oboe), James Abrahamson (clarinet), James Currence (horn), and Isaac Roles (bassoon)https://spiral.lynn.edu/conservatory_chamber-music-competition/1002/thumbnail.jp

How market standards affect building design: the case of low energy design in commercial offices

This paper develops existing work on building design through a focus on one important yet understudied form of regulation: market standards. Market standards are agreed upon definitions of ‘necessary’ provision in buildings and are fundamental in ‘formatting’ markets and determining the value of a building in the market. The paper presents a case study of the design of ten commercial offices in London, UK, the effects of market standards on the designs and on the potential for the development of lower energy buildings. Theoretically, the paper integrates literatures on standards, institutions and markets to argue that market standards do important ‘work’ in design processes that requires closer scrutiny. In particular, we show that market standards: are an important form of normative and cultural regulation in the field of commercial office design; format and act as calculative devices in property markets; and result in forms of knowledge diminution that break the relationship between building design and occupiers’ practices. Together, these effects result in particular designs being legitimised and valued, and lower energy designs being delegitimised, devalued and pushed to the periphery of the attention of commercial office designers

Transcription restores DNA repair to heterochromatin, determining regional mutation rates in cancer genomes

SummarySomatic mutations in cancer are more frequent in heterochromatic and late-replicating regions of the genome. We report that regional disparities in mutation density are virtually abolished within transcriptionally silent genomic regions of cutaneous squamous cell carcinomas (cSCCs) arising in an XPC−/− background. XPC−/− cells lack global genome nucleotide excision repair (GG-NER), thus establishing differential access of DNA repair machinery within chromatin-rich regions of the genome as the primary cause for the regional disparity. Strikingly, we find that increasing levels of transcription reduce mutation prevalence on both strands of gene bodies embedded within H3K9me3-dense regions, and only to those levels observed in H3K9me3-sparse regions, also in an XPC-dependent manner. Therefore, transcription appears to reduce mutation prevalence specifically by relieving the constraints imposed by chromatin structure on DNA repair. We model this relationship among transcription, chromatin state, and DNA repair, revealing a new, personalized determinant of cancer risk

Quantifying the Impact of Immune History and Variant on SARS-CoV-2 Viral Kinetics and Infection Rebound: A Retrospective Cohort Study

BACKGROUND: The combined impact of immunity and SARS-CoV-2 variants on viral kinetics during infections has been unclear. METHODS: We characterized 1,280 infections from the National Basketball Association occupational health cohort identified between June 2020 and January 2022 using serial RT-qPCR testing. Logistic regression and semi-mechanistic viral RNA kinetics models were used to quantify the effect of age, variant, symptom status, infection history, vaccination status and antibody titer to the founder SARS-CoV-2 strain on the duration of potential infectiousness and overall viral kinetics. The frequency of viral rebounds was quantified under multiple cycle threshold (Ct) value-based definitions. RESULTS: Among individuals detected partway through their infection, 51.0% (95% credible interval [CrI]: 48.3-53.6%) remained potentially infectious (Ct CONCLUSIONS: SARS-CoV-2 viral kinetics are partly determined by immunity and variant but dominated by individual-level variation. Since booster vaccination protects against infection, longer clearance times for BA.1-infected, boosted individuals may reflect a less effective immune response, more common in older individuals, that increases infection risk and reduces viral RNA clearance rate. The shifting landscape of viral kinetics underscores the need for continued monitoring to optimize isolation policies and to contextualize the health impacts of therapeutics and vaccines. FUNDING: Supported in part by CDC contract #200-2016-91779, a sponsored research agreement to Yale University from the National Basketball Association contract #21-003529, and the National Basketball Players Association

Using ice core measurements from Taylor Glacier, Antarctica, to calibrate in situ cosmogenic 14 C production rates by muons

Cosmic rays entering the Earth’s atmosphere produce showers of secondary particles such as protons, neutrons, and muons. The interaction of these particles with oxygen-16 (16O) in minerals such as ice and quartz can produce carbon-14 (14C). In glacial ice, 14C is also incorporated through trapping of 14C-containing atmospheric gases (14CO2, 14CO, and 14CH4). Understanding the production rates of in situ cosmogenic 14C is important to deconvolve the in situ cosmogenic and atmospheric 14C signals in ice, both of which contain valuable paleoenvironmental information. Unfortunately, the in situ 14C production rates by muons (which are the dominant production mechanism at depths of > 6m solid ice equivalent) are uncertain. In this study, we use measurements of in situ 14C in ancient ice (> 50 ka) from the Taylor Glacier, an ablation site in Antarctica, in combination with a 2D ice flow model to better constrain the compound-specific rates of 14C production by muons and the partitioning of in situ 14C between CO2, CO, and CH4. Our measurements show that 33.7% (11.4%; 95% confidence interval) of the produced cosmogenic 14C forms 14CO and 66.1% (11.5%; 95% confidence interval) of the produced cosmogenic 14C forms 14CO2. 14CH4 represents a very small fraction (< 0.3%) of the total. Assuming that the majority of in situ muogenic 14C in ice forms 14CO2, 14CO, and 14CH4, we also calculated muogenic 14C production rates that are lower by factors of 5.7 (3.6–13.9; 95% confidence interval) and 3.7 (2.0–11.9; 95% confidence interval) for negative muon capture and fast muon interactions, respectively, when compared to values determined in quartz from laboratory studies (Heisinger et al., 2002a, b) and in a natural setting (Lupker et al., 2015). This apparent discrepancy in muogenic 14C production rates in ice and quartz currently lacks a good explanation and requires further investigation

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London