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The youngest low-mass protostars are known to be chemically rich, accreting matter most vigorously, and producing the most powerful outflows. Molecules are unique tracers of these phenomena. We use ALMA to study several outflow sources in the Serpens Main region. The most luminous source, Ser-SMM1, shows the richest chemical composition, but some complex molecules are also present in S68N. No emission from complex organics is detected toward Ser-emb 8N, which is the least luminous in the sample. We discuss whether these differences reflect an evolutionary effect or whether they are due to different physical structures. We also analyze the outflow structure from these young protostars by comparing emission of CO and SiO. EHV molecular jets originating from SMM1-a,b and Ser-emb 8N contrast with no such activity from S68N, which on the other hand presents a complex outflow structure.
Due to the wide bandgap and other key materials properties of 4H-SiC, SiC MOSFETs
offer performance advantages over competing Si-based power devices. For example,
SiC can more easily be used to fabricate MOSFETs with very high voltage ratings,
and with lower switching losses. Silicon carbide power MOSFET development has
progressed rapidly since the market release of Cree’s 1200V 4H-SiC
power MOSFET in 2011. This is due to continued advancements in SiC substrate
quality, epitaxial growth capabilities, and device processing. For example,
high-quality epitaxial growth of thick, low-doped SiC has enabled the
fabrication of SiC MOSFETs capable of blocking extremely high voltages (up to
15kV); while dopant control for thin highly-doped epitaxial layers has helped
enable low on-resistance 900V SiC MOSFET production. Device design and
processing improvements have resulted in lower MOSFET specific on-resistance for
each successive device generation. SiC MOSFETs have been shown to have a long
device lifetime, based on the results of accelerated lifetime testing, such as
high-temperature reverse-bias (HTRB) stress and time-dependent dielectric
An integrated experimental – simulation – control theory approach designed to enable adaptive control of microstructural evolution in polycrystalline metals is described. A micro-heater array, containing ten addressable channels, is used to create desired temperature profiles across thin polycrystalline films in situ to a scanning electron microscope (SEM). The goal is that on heating with controlled temperature profiles, the evolution of grain growth within the film can be continuously monitored and compared to Monte Carlo simulations of trajectories towards a desired microstructure. Feed-forward and feedback control strategies are then used to guide the microstructure along the desired trajectory.
It is an honor to be invited to contribute to this volume. Indeed, I am somewhat overawed when I look at the list of other academics who are contributing. There can be no question that my career path has been different from theirs. I did not get my PhD from a top school, and my research has tended to be influenced as much by practitioners as by other academics. My research strategy (and life philosophy) may therefore be an outlier, but I hope it will nevertheless be of interest to readers.
My undergraduate degree was in math at Cambridge University in England. The Mathematical Tripos lasted three years. The courses in the first two years (Parts IA and IB of the Tripos) were compulsory. In the third year (Part II of the Tripos), students specialized in pure or applied math. I chose pure math simply because I enjoyed it. At the time I made this choice, I had no firm ideas about a future career. (Of course, applied math would have been somewhat more useful given the way my career actually developed.)
The Milky Way appears as a typical barred spiral, and comparisons can be made between its nuclear region and those of structurally similar nearby spirals. Maffei 2, M83, IC 342 and NGC 253 are nearby systems whose nuclear region properties contrast with those of the Milky Way. Stellar masses derived from NIR photometery, molecular gas masses and star formation rates allow us to assess the evolutionary states of this set of nuclear regions. These data suggest similarities between nuclear regions in terms of their stellar content while highlighting significant differences in current star formation rates. In particular current star formation rates appear to cover a larger range than expected based on the molecular gas masses. This behavior is consistent with nuclear region star formation experiencing episodic variations. Under this hypothesis the Milky Way's nuclear region currently may be in a low star formation rate phase.
This quality improvement project was set in Tower Hamlets, east London, with the aim of reducing health inequalities by ethnicity, age and gender in the management of three common chronic diseases.
Routinely collected clinical data were extracted from practice computer systems using Morbidity Information Query and Export Syntax (MIQUEST) and Egton Medical Information Systems (EMIS) Web, between 2007 and 2010. Health equity audits for 38 practices in Tower Hamlets primary care trust (PCT) were constructed to cover key process and outcome measures for each of the three major chronic diseases: coronary heart disease (CHD), type 2 diabetes mellitus and chronic obstructive pulmonary disease (COPD). The equity audit was disseminated to practices along with facilitation sessions.
We show evidence of baseline inequalities in each condition across the three east London PCTs. The intervention tracked four key indicators (cholesterol levels in CHD, blood pressure and haemoglobin A1c levels in diabetes and % smoking in COPD). Performance for physician-driven interventions improved, but smoking rates remained static. All ethnic groups showed improvement, but there was no evidence of a reduction in differences between ethnic groups. Reductions in gender and age group differences were noted in diabetes and CHD.
Using routine clinical data, it is possible to develop practice-level health equity reports. These can unmask previously hidden inequalities between groups, and promote discussion with practice teams to stimulate strategies for improvements in performance. Steady improvements in chronic disease management were observed, however, systematic differences between ethnic groups remain. We are not able to attribute observed changes to the audits. These reports illustrate the importance of collecting ethnicity data at practice level. Tools such as this audit can be adapted to monitor inequalities in primary care settings.
Recent excavations at two sites located along the coastal margin of the Los Angeles basin revealed three features created as a result of communal mourning ritual during the Intermediate Period (ca. 3000–1000 cal B.P.). Detailed analysis of constituents, structure, and context indicates that formation of these dense concentrations of ground stone implements, unmodified cobbles, other artifacts, and cremated human remains involved deliberate equipment production, sequential implement fragmentation and treatment including burning and pigmentation of items, and secondary interment of incomplete objects and bodies in pits within locales often used for this purpose over many generations. The large size and evident manipulation of objects as part of communal mourning ritual indicates that actions would have been readily visible to a gathered assembly. Thus, while the meaning and significance of these practices remains to be thoroughly explored, the data suggest that communal mourning ritual may have played a significant role in community-building and the maintenance of identity within a region with a dynamic population history.
Starting from first principles, we construct a simple model for the evolution of energetic particles produced by supernovae in the starburst galaxy M82. The supernova rate, geometry, and properties of the interstellar medium are all well observed in this nearby galaxy. Assuming a uniform interstellar medium and constant cosmic-ray injection rate, we estimate the cosmic-ray proton and primary & secondary electron/positron populations. From these particle spectra, we predict the gamma ray flux and the radio synchrotron spectrum. The model is then compared to the observed radio and gamma-ray spectra of M82 as well as previous models by Torres (2004), Persic et al. (2008), and de Cea del Pozo et al. (2009). Through this project, we aim to build a better understanding of the calorimeter model, in which energetic particle fluxes reflect supernova rates, and a better understanding of the radio-FIR correlation in galaxies.
Source-sink theories provide a simple yet powerful framework for understanding how the patterns, processes and dynamics of ecological systems vary and interact over space and time. Integrating multiple research fields, including population biology and landscape ecology, this book presents the latest advances in source-sink theories, methods and applications in the conservation and management of natural resources and biodiversity. The interdisciplinary team of authors uses detailed case studies, innovative field experiments and modeling, and comprehensive syntheses to incorporate source-sink ideas into research and management, and explores how sustainability can be achieved in today's increasingly fragile human-dominated ecosystems. Providing a comprehensive picture of source-sink research as well as tangible applications to real world conservation issues, this book is ideal for graduate students, researchers, natural-resource managers and policy makers.
Organisms and populations are discontinuously distributed in space and change over time. As a result, conserving and managing ecological systems requires an understanding of how these systems and their patterns, processes and dynamics vary and interact in space and time. More than two decades ago, H. Ronald Pulliam developed a conceptual framework of spatial population dynamics to address this need. In his 1988 paper (“Sources, sinks, and population regulation,” American Naturalist 132: 652—661), Pulliam created a framework that envisioned that populations in “sink” (poor) habitats would rely on inputs from “source” (good) habitats in order to persist. The dynamics of population segments across heterogeneous landscapes were linked. This simple yet powerful framework has inspired numerous studies and has provided the foundation for rapid advances in ecological theory and practice.
To reflect upon and synthesize the development of thinking and research inspired by Pulliam’s framework, a symposium on “Sources, Sinks, and Sustainability across Landscapes” was held at the 2008 annual conference of the US Regional Association of the International Association for Landscape Ecology (US-IALE) in Wisconsin, USA. The symposium, organized in honor of Pulliam’s retirement, amply illustrated his many contributions to ecology, animal behavior, evolution, and other fields, through his former roles as Regents Professor and Director of University of Georgia’s Institute of Ecology, Director of the National Biological Service, Science Advisor to the Secretary of the Interior, and the President of the Ecological Society of America. The 30 presenters from around the world included Pulliam’s former students and postdoctoral associates, as well as other leading scholars who have been influenced by Pulliam’s work.