Far-ultraviolet molecular hydrogen fluorescence in photodissociation regions

France, Kevin C The Johns Hopkins University 2006 해외박사(DDOD)

Molecular hydrogen constitutes a large fraction of the baryonic matter in the universe and plays a role in regulating the physics and chemistry of many astrophysical environments. It is an important coolant during the formation of the first structures in the universe, is the dominant mass component in star-forming regions today, and is ubiquitous in the interstellar medium. As a homonuclear molecule, it has no permanent electric dipole moment, but the quadrupole rovibrational transitions provide diagnostic information about the physical state of interstellar clouds. Electronic transitions of the molecule are allowed and the absorption lines arising from these transitions are used to probe the physical conditions of the interstellar medium. However, the subsequent emission that is the dominant de-excitation route of the molecule is poorly constrained by both observations and theory. The purpose of this dissertation is to examine molecular hydrogen by using new and existing ultraviolet observations to test models of the fluorescent emission process. This dissertation will report on new observations made by sounding rocket experiments and the Far Ultraviolet Spectroscopic Explorer to expand the observational basis for molecular hydrogen studies. The observational survey includes a variety of photodissociation regions, including the emission nebula IC 63, the star-forming region near the Orion Nebula, the emission/reflection nebula IC 405, and the pure reflection nebulae NGC 2023 and NGC 7023. We detect the fluorescent signature in the first three objects, and we use these data to develop the first model of this emission that is consistent with observation. We do not detect hydrogen fluorescence as presently understood in the latter two objects, and explanations are discussed.

Dislocation formation and glide in atomically-ordered III-V semiconductors

France, Ryan Matthew Colorado School of Mines 2015 해외박사(DDOD)

Strain relaxation of III-V materials is a complex process that can be heavily influenced by material microstructure. In this thesis, I investigate the effects of CuPt atomic ordering on dislocation formation and glide in III-V materials. CuPt atomic ordering has been observed in many ternary and quaternary III-V materials, and consists of alternating {111} planes of one or both of the mixed-group constituents. Most importantly, the ordered structure is induced by the surface reconstruction during epitaxy and is metastable in the bulk of the film. Glide through ordered planes disrupts the order pattern and reduces this metastability, and so is energetically favorable. This presents a unique situation where dislocations receive an additional driving force for glide. The additional glide force reduces the critical thickness of pseudomorphic material, but should also beneficially increase the glide length of metamorphic material. In addition, the distribution of dislocations is heavily skewed towards those that disrupt the order pattern. New dislocations can form upon order-disorder transitions in a metamorphic buffer as glide becomes more energetically favorable on different glide planes, necessitating redesign of the buffer structure. Further implications are discussed, as well as strategies to improve stability of pseudomorphic material and reduce the dislocation density of metamorphic material.

Aspects of the economics of hyperinflations : theorietical issues and historical studies of four European hyperinflations of the 1920s

France, Gustavo Henrique de Barroso Edward Elgar 1986 국내박사

A climatology of the stratopause in the polar vortices and anticyclones: Observations and global modeling

France, Jeffrey Allen University of Colorado at Boulder 2012 해외박사(DDOD)

Zonal asymmetries in stratopause temperature and height are explored by considering a global climatology based on 7 years of Microwave Limb Sounder (MLS) satellite data, from 2004 to 2011. Stratopause temperature and height is interpreted in the context of the polar vortices and anticyclones defined by the Goddard Earth Observing System (GEOS) meteorological analyses. Multiyear, monthly mean geographic patterns in stratopause temperature and height are shown to depend on the location of the polar vortices and anticyclones. The regional temperature and height anomalies, which are due to vertical ageostrophic motion associated with vertically propagating baroclinic planetary waves, are climatological features. This climatology is reproduced using 40 years of output from the Whole Atmosphere Community Climate Model (WACCM). WACCM is in excellent agreement with observations, except in the Antarctic vortex where the stratopause is ∼10 K warmer and ∼5 km higher compared with MLS, and the area of the vortex is 45% smaller in the SH and 30% smaller in the NH compared to GEOS. WACCM diabatic heating rates support the hypothesis that ageostrophic vertical motions are responsible for producing Arctic winter temperature anomalies. A composite of 15 elevated stratopause (ES) events based on WACCM is produced and shown to be in good agreement with the 2012 ES event observed by MLS. This analysis is the first to suggest that ES events are not pole centered. Finally, temperature observations during January and February 2006 from the High Resolution Dynamics Limb Sounder (HIRDLS), MLS, and the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) satellite instruments are compared to illustrate the vertical range over which version 6 HIRDLS temperatures are scientifically useful. Though HIRDLS temperatures are consistently 5-10 K lower in the mesosphere, the horizontal temperature distribution is in good spatial and temporal agreement with MLS and SABER up to ∼80 km. Gravity wave momentum flux and planetary wave-1 amplitudes are derived from HIRDLS and are in agreement with previous studies. We use HIRDLS to show a ∼30 K increase in stratopause temperature following enhanced gravity wave momentum flux in the lower mesosphere.

Novel asymmetric methods in ketene chemistry and the design of a synthesis machine

France, Stefan Anthony The Johns Hopkins University 2005 해외박사(DDOD)

Ketenes are an important reactive class of compounds that have received much attention in the literature over the past 20 years. Due to the electrophilic nature of the alpha carbon, ketenes are highly susceptible to nucleophilic attack. The attack of tertiary amine nucleophiles on ketenes will generate putative zwitterionic enolates, where the charges are stabilized due to their close proximity. These enolates are capable of attacking electrophiles to afford a wide variety of useful compounds. To fully explore the potential of the versatile ketenes, we developed novel applications as well as new protocols for their generation. We found that achiral Lewis acid catalysts could be used in conjunction with chiral Lewis bases to enhance the rate of product formation in our catalytic, asymmetric synthesis of beta-lactams from acid chlorides and imines. We performed extensive mechanistic and kinetic studies to determine the role and binding properties of In(III) in our bifunctional system. We have also developed a catalytic, enantioselective synthesis of alpha-halo esters using inexpensive acid chlorides as starting materials and cinchona alkaloid derivatives as catalysts. We discovered that polyhalogenated quinones are superior halogenating agents for our reactions, whereas most other mild reagents fail completely. We have also improved upon our originally published chlorination methodology by reducing the amounts of nonhalogenated byproducts. Furthermore, we have developed the use of cost-effective stoichiometric bases to achieve an overall process possessing considerable synthetic utility, and one that by any measure is at least competitive with existing chiral auxiliary methodology. We have expanded our bromination methodology to include the use of NaH as a stoichiometric base. We are hoping that the expansion of this methodology would provide a facile means to the synthesis of optically pure amino acids, sulfides, and ethers. Furthermore, we have expanded on the column asymmetric column methodology developed in our labs to include the asymmetric halogenation/esterification of acid chlorides. Our first "proof of principle" reaction of a pharmaceutically active drug compound was undertaken and achieved on our solid-phase "synthesis machine.".

The Multiple Roles of EWS/FLI1 in Regulation of Gene Expression

France, Kelly Allison University of California, Los Angeles 2011 해외박사(DDOD)

Ewing Family Tumors (EFTs), the second most common bone malignancy in children, are characterized by a translocation fusing EWS, an RNA-binding protein, to one of five ETS transcription factors, most commonly FLI1. The fusion protein is capable of inducing large changes in gene expression and cellular transformation. It is thought EWS/FLI1 causes these changes by acting as an aberrant transcription factor. Identifying the mechanism through which EWS/FLI1 modulates gene expression is an important step in understanding the role it plays in the development of EFTs. Both heterologous NIH 3T3 and human EFT cell lines were used to investigate the specific processes EWS/FLI1 affects. Through quantitative analysis of pre-mRNA, we have shown that EWS/FLI1 repressed the expression of its direct target genes through at least two processes. In both murine and human cell lines, chromatin immunoprecipitation (ChIP) experiments showed EWS/FLI1 decreases the amount of Pol II at the promoter of down regulated genes. In addition, EWS/FLI1 down regulates gene expression by decreasing the RNA half-life of its targets in a Ewing's Sarcoma cell line. Our work demonstrates that EWS/FLI1 is a multifunctional protein that modulates target gene expression through changes at both RNA synthesis and RNA processing stages.

Triadic Supervision: An Exploration of Supervisors' Perceptions, Experiences and Practices

France, Kharod A The George Washington University 2015 해외박사(DDOD)

Although first recognized as an equivalent to individual supervision in the 2001 standards of The Council for Accreditation of Counseling and Related Educational Programs (CACREP), to date it still remains the case that very little research has been done on this unique and increasingly popular supervision modality. Despite being utilized in counselor education programs across the county, as of the spring of 2015, only seven dissertations and 13 empirical journal articles have been written addressing triadic supervision specifically. With this being the case, relatively little is known about the various processes that underlie the triadic supervision process or about best practices to increase its effectiveness. The purpose of this qualitative study was to explore and gain a better understanding of supervisors' perceptions, experiences and practices with regards to triadic supervision. Data was collected by way of in-depth, semi-structured interviews conducted either via phone or via Skype. Of the 23 supervisors who participated in this study, all had conducted triadic supervision within the last 5 years and all were either graduates of, currently enrolled doctoral students in or faculty members at CACREP accredited programs. Data was analyzed using basic interpretive qualitative techniques, where more specifically the seven-step analysis plan detailed by Marshall and Rossman (2006) was utilized. The initial fourteen themes that emerged from the data analysis process were further synthesized into eight primary findings. These findings addressed the three primary research questions of this study: (a) How do supervisors go about structuring their triadic supervision sessions and what is the thought process behind this decision? (b) What are supervisors' thoughts on the role and influence of the second supervisee in session and on the supervisory process? (c) What specific aspects of triadic supervision impact supervisors' behavior and decision-making throughout the course of the supervisory process? Implications for counselor preparation and practices were discussed, where specific and separate recommendations were given for both Counselor Education programs and for supervisors. Recommendations for future research were also discussed.

Bk channel, 5-HT and sex in gastrointestinal motility in health and obesity

France, Marion Michigan State University 2015 해외박사(DDOD)

Highly regulated motor reflexes observed in gastrointestinal (GI) motility promote nutrient digestion and absorption as well as excretion of indigestible material. Motor reflexes are fundamentally regulated by the enteric nervous system (ENS), and can be modulated by 1) smooth muscle tone changes by the activation of large conductance Ca2+-activated K+ (BK) channels and by 2) intrinsic neuron activation by 5-hydroxytryptamine (5-HT, serotonin). Impairments in the modulation of motor reflexes cause GI motility disorders. Although GI motility disorders are typically not life threatening, the quality of life of affected individuals can be poor. GI motility disorders are common in obesity that affects millions of people in the United States. GI motility dysfunction in obesity may be caused by perturbations in intestinal 5-HT dynamics. 5-HT located in enterochromaffin (EC) cells of the GI mucosa influences GI motility by coordinating the nerve circuits in the ENS. I investigated 1) the role BK channels in normal GI transit in mice and 2) 5-HT signaling in controlling GI transit in male and female mice fed a high fat diet (HFD) to produce diet-induced obesity (DIO). I used complimentary in vivo and in vitro methods to identify sex differences in small intestinal transit and 5-HT dynamics in obese mice. Overall, I found 1) BK channels are necessary for normal propulsive colonic transit and 2) sex and obesity-related alterations in small intestinal transit and 5-HT signaling. These sex differences in DIO must be considered when designing therapeutic approaches targeting intestinal 5-HT to treat impaired motility in obesity.

Integrating molecular typing into routine tuberculosis surveillance: An assessment of the strengths and limitations of current approaches

France, Anne Marie University of Michigan 2008 해외박사(DDOD)

Molecular typing is increasingly integral to tuberculosis (TB) control programs, providing public health practitioners with a tool to characterize transmission patterns, track the emergence and spread of strains of particular medical and public health importance, and identify transmission venues that contribute to the persistence of M. tuberculosis in populations. While molecular typing is already used extensively as a tool for TB control in many diverse populations across the globe, the sensitivity of molecular typing-based measures to characteristics of both the host and microbial populations is not well understood. To better characterize the relationship between key host and microbial factors and the validity of molecular typing measures, this dissertation work employs a multi-disciplinary research strategy which integrates molecular, epidemiologic, and computer-simulation data. In the rural, stable population of Arkansas, we found that a declining incidence of TB between 1996 and 2003 resulted primarily from a declining incidence of TB due to the reactivation of remotely acquired infection, rather than recently acquired infection. This work suggested the influence of a strong cohort effect on disease patterns in this population. A validation study of molecular typing in this same population, in which extensive epidemiologic interview data were compared to molecular typing results, identified a number of host and microbial factors associated with the validity of typing results. This study also suggested the presence of a regionally endemic strain family which was associated with false positive molecular typing results. Using an agent-based model of TB transmission, we conducted the first quantitative assessment of the importance of the diversity and stability of molecular typing markers, as well as historic and demographic characteristics of the host population, to the validity of typing results. The results of these investigations contribute to an improved understanding of the dynamics of TB transmission in rural populations of the United States, and also highlight key factors that should be considered in the interpretation of molecular typing results in all populations. Additionally, these results may inform the development of more rational approaches to the design of molecular typing systems used in TB control.

The use of GIS and remote sensing to identify settlement areas at risk of flood runoff and landslides : a case study in Sukabumi Regency, Indonesia

Andi France Daryanto 서울시립대학교 국제도시과학대학원 2023 국내석사

This paper aims to examine the use of GIS and remote sensing to identify settlements in Sukabumi Regency that are vulnerable to flooding and landslides. Floods and landslides are frequent that cause loss of life and considerable property damage. Vulnerability analysis is performed by reclassifying and scoring the parameters using the overlay technique to weight each parameter. The results reveal how large the area is that has a given level of vulnerability from each reclassification scoring level and provide actual Settlement Areas at Risk from Run-off Floods and Landslides maps. The satellite image will then indicate selected regions with significant vulnerability based on the data analysis. Sukabumi Regency is at high risk of vulnerability. Floods and landslides threaten 80.9% of the settlements in Sukabumi Regency. In addition to the spatial designation pattern in the spatial plan, up to 36.4% of the rural spatial designation pattern and 12.8% of the urban spatial designation pattern have a high level of potential for flood and landslide disasters. It is significant that disaster-prone settlements must be undertaken as best as possible. Given that resolving settlement challenges is inextricably linked to a comprehensive spatial planning process that cannot be accomplished in a short period of time, appropriate planning and solutions are required to be established. 이 논문은 홍수와 산사태에 취약한 수카부미 지역의 주거지를 파악하기 위해 GIS와 원격 감지의 사용을 검토하는 것을 목표로 하였다. 홍수와 산사태가 자주 발생하여 인명 손실과 상당한 재산 피해가 발생하고 있다. 취약성 분석은 오버레이 기법을 사용하여 매개변수를 재 분류하고 점수를 매겨 각 매개변수에 가중치를 부여하는 방식으로 수행하였다. 결과는 각각의 재 분류 점수 수준에서 주어진 취약성 수준을 가진 지역이 얼마나 큰지를 보여주었고, 유출 홍수 및 산사태 지도에서 위험에 처한 실제 정착 지역을 보여주었다. 그 다음, 위성 이미지는 데이터 분석을 기반으로 선택된 심각한 취약성이 있는 지역을 보여주었다. 수카부미 지역은 취약성이 높다. 홍수와 산사태는 수카부미 지역 내 정착지의 80.9%에 위협적이다. 공간계획상의 공간 지정 패턴 외에도 농촌 공간 지정 패턴의 36.4%, 도시 공간 지정 패턴의 12.8%가 홍수 및 산사태 재해 발생 가능성이 높은 것으로 나타났다. 재난에 취약한 정착지는 가능한 한 최선을 다해 수행해야 한다는 것이 중요하다. 정착지 문제 해결은 단기간에 달성할 수 없는 포괄적인 공간 계획 프로세스와 불가분의 관계가 있다는 점을 고려할 때 적절한 계획 및 솔루션 개발이 필요하다.