Experimental design for study of nucleate boiling in porous structures

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 48).The superheat required to initiate nucleate boiling inside porous wicks is not well understood in practice. This thesis reports the design of an experimental setup for investigating the onset of vapor nucleation in sintered porous structures. Pressure sensing was evaluated as an effective means of detecting the onset of nucleation. Thermal studies were conducted with a custom finite difference script in conjunction with finite element analysis. Heat conduction through a three dimensional wick was reduced to one dimensional conduction via symmetry and design constraints. The wick was optimized to achieve a temperature drop of 30 *C at a common heat pipe operating temperature of 70 °C.by Mitchell Joseph Kelley.S.B

Association between arterial stiffness and variations in estrogen-related genes

available in PMC 2010 April 1.Increased arterial stiffness and wave reflection have been identified as cardiovascular disease risk factors. In light of significant sex differences and the moderate heritability of vascular function measures, we hypothesized that variation in the genes coding for oestrogen receptors α (ESR1) and β (ESR2) and aromatase (CYP19A1) is associated with aortic stiffness and pressure wave reflection as measured by non-invasive arterial tonometry. In all, 1261 unrelated Framingham Offspring Study participants who attended the seventh examination cycle (mean age 62±10 years, 52% women) and had arterial tonometry and genotyping data were included in the study. Analysis of covariance was used to assess the association of polymorphisms with forward wave amplitude, augmented pressure, augmentation index (AI), carotid–femoral pulse wave velocity and mean arterial pressure with adjustment for potential confounders. In the sex-pooled analysis, those homozygous for the minor allele at any of four ESR1 variants that were in strong linkage disequilibrium ((TA)n, rs2077647, rs2234693 and rs9340799) had on an average 18% higher augmented pressure and 16% greater AI compared with carriers of one or two major alleles (P=0.0002–0.01). A similar magnitude of association was detected in those homozygous for the common allele at two ESR2 single-nucleotide polymorphisms (P=0.007–0.02). Our results are consistent with the hypothesis that variation in ESR1 and ESR2, but not CYP19A1, is associated with an increased wave reflection that may contribute to associations between these variants and adverse clinical events demonstrated earlier. Our findings will need to be replicated in additional cohorts

Explorations, Vol. 6, No. 1

Cover: Panthera pardus, Chui in Kiswatuli, was photographed by Dr. Linda Karbonit ar Dr. James A. Sherburne in Serengeti National Park, Tanzania. Karbonit was accompanying Sherburne who was working on the design and development of the University of Maine, U.S. Fish and Wildlife Service, assistance program in wildlife training and conservation education to Tanzania’s National Parks. Sherburne, who has worked in Tanzania for several years, was there most recently in 1988 and 1989 working on the parks project. He serves as the Director of International Natural Resources and Agricultural Programs at the University of Maine. Articles include: Research and Economic Development: from the U.S. Senate Statement, December 22, 1989, by Sen. George J. Mitchell Politics and Research: Providing a Key for Economic Development, by Sen. William S. Cohen. Publisher’s Perspective, by Gregory N. Brown, Vice President, Research and Public Service What’s EPSCoR? Editorial Reflections, by Carole J. Bombard Past and Present: Marine Geologists Explore the Old and Teach the Young, by Daniel Belknap and Joseph Kelley High Biological Productivity: Salt Marshes, by Mark E. Wood Barrier Beaches, by William Duffy Sediment Budgets & Bluff Slump, by Rebecca Smith Coastal Environments and Change, by Andrew Walsh Mapping What You Can\u27t See, by Donald Robbins Casco Bay: Sea Level and the Shoreline, by Bradley W.B. Hay Christmas at Sea, by Molly Horvath A Short Course and the Local Economy, by Richard Hale and James Philp Dr. Bernard Lown: Alumnus Receives Golden Door Award The Sky is Falling . . . well, maybe, by Carole J. Bombard A Growing Interest in Timberland, by Robert A. Strong and Bret P. Vicar

A Prospective Study of Risk-Reducing Salpingo-oophorectomy and Longitudinal CA-125 Screening among Women at Increased Genetic Risk of Ovarian Cancer: Design and Baseline Characteristics: A Gynecologic Oncology Group Study

Women who are genetically predisposed to ovarian cancer are at very high risk of developing this disease. Although risk-reducing salpingo-oophorectomy (RRSO) and various screening regimens are currently recommended to reduce ovarian cancer risk, the optimal management strategy has not been established nor have multiple additional issues been adequately addressed. We developed a collaboration among the Clinical Genetics Branch (National Cancer Institute’s Intramural Research Program), the Gynecologic Oncology Group (GOG), and the Cancer Genetics Network to address these issues

THE ROLE OF INTERDEPENDENCE IN THE MICRO-FOUNDATIONS OF ORGANIZATION DESIGN: TASK, GOAL, AND KNOWLEDGE INTERDEPENDENCE

Interdependence is a core concept in organization design, yet one that has remained consistently understudied. Current notions of interdependence remain rooted in seminal works, produced at a time when managers’ near-perfect understanding of the task at hand drove the organization design process. In this context, task interdependence was rightly assumed to be exogenously determined by characteristics of the work and the technology. We no longer live in that world, yet our view of interdependence has remained exceedingly task-centric and our treatment of interdependence overly deterministic. As organizations face increasingly unpredictable workstreams and workers co-design the organization alongside managers, our field requires a more comprehensive toolbox that incorporates aspects of agent-based interdependence. In this paper, we synthesize research in organization design, organizational behavior, and other related literatures to examine three types of interdependence that characterize organizations’ workflows: task, goal, and knowledge interdependence. We offer clear definitions for each construct, analyze how each arises endogenously in the design process, explore their interrelations, and pose questions to guide future research

Pregnancy termination for fetal abnormality: are health professionals’ perceptions of women’s coping congruent with women’s accounts?

Background: Pregnancy termination for fetal abnormality (TFA) may have profound psychological consequences for those involved. Evidence suggests that women’s experience of care influences their psychological adjustment to TFA and that they greatly value compassionate healthcare. Caring for women in these circumstances presents challenges for health professionals, which may relate to their understanding of women’s experience. This qualitative study examined health professionals’ perceptions of women’s coping with TFA and assessed to what extent these perceptions are congruent with women’s accounts. Methods: Fifteen semi-structured interviews were carried out with health professionals in three hospitals in England. Data were analysed using thematic analysis and compared with women’s accounts of their own coping processes to identify similarities and differences. Results: Health professionals’ perceptions of women’s coping processes were congruent with women’s accounts in identifying the roles of support, acceptance, problem-solving, avoidance, another pregnancy and meaning attribution as key coping strategies. Health professionals regarded coping with TFA as a unique grieving process and were cognisant of women’s idiosyncrasies in coping. They also considered their role as information providers as essential in helping women cope with TFA. The findings also indicate that health professionals lacked insight into women’s long-term coping processes and the potential for positive growth following TFA, which is consistent with a lack of aftercare following TFA reported by women. Conclusions: Health professionals’ perceptions of women’s coping with TFA closely matched women’s accounts, suggesting a high level of understanding. However, the lack of insight into women’s long-term coping processes has important clinical implications, as research suggests that coping with TFA is a long-term process and that the provision of aftercare is beneficial to women. Together, these findings call for further research into the most appropriate ways to support women post-TFA, with a view to developing a psychological intervention to better support women in the future

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

Cross Correlation of IceCube Neutrinos with Tracers of Large Scale Structure

The origin of most astrophysical neutrinos is unknown, but extragalactic neutrino sources may follow the spatial distribution of the large-scale structure of the universe. Galaxies also follow the same large scale distribution, so establishing a correlation between galaxies and IceCube neutrinos could help identify the origins of the diffuse neutrinos observed by IceCube. Following a preliminary study based on the WISE and 2MASS catalogs, we will investigate an updated galaxy catalog with improved redshift measurements and reduced stellar contamination. Our IceCube data sample consists of track-like muon neutrinos selected from the Northern sky. The excellent angular resolution of track-like events and low contamination with atmospheric muons is necessary for the sensitivity of the analysis. Unlike a point source stacking analysis, the calculation of the cross correlation does not scale with the number of entries in the catalog, making the work tractable for catalogs with millions of objects. We present the development and performance of a two-point cross correlation of IceCube neutrinos with a tracer of the large scale structure

Mechanical design of the optical modules intended for IceCube-Gen2

IceCube-Gen2 is an expansion of the IceCube neutrino observatory at the South Pole that aims to increase the sensitivity to high-energy neutrinos by an order of magnitude. To this end, about 10,000 new optical modules will be installed, instrumenting a fiducial volume of about 8 km3. Two newly developed optical module types increase IceCube’s current sensitivity per module by a factor of three by integrating 16 and 18 newly developed four-inch PMTs in specially designed 12.5-inch diameter pressure vessels. Both designs use conical silicone gel pads to optically couple the PMTs to the pressure vessel to increase photon collection efficiency. The outside portion of gel pads are pre-cast onto each PMT prior to integration, while the interiors are filled and cast after the PMT assemblies are installed in the pressure vessel via a pushing mechanism. This paper presents both the mechanical design, as well as the performance of prototype modules at high pressure (70 MPa) and low temperature (−40∘C), characteristic of the environment inside the South Pole ice