313 research outputs found
Spaces of rational curves in complete intersections
We prove that the space of smooth rational curves of degree
e in a general complete intersection of multidegree (d1,...., dm) in Pn is
irreducible of the expected dimension if Σi=1m
di < 2n/3 and n is large
enough. This generalizes the results of Harris, Roth and Starr, and
is achieved by proving that the space of conics passing through any point
of a general complete intersection has constant dimension if Σi=1m
di is small compared to n
Spaces of rational curves in complete intersections
We prove that the space of smooth rational curves of degree in a general
complete intersection of multidegree in \PP^n is
irreducible of the expected dimension if and
is large enough. This generalizes the results of Harris, Roth and Starr
\cite{hrs}, and is achieved by proving that the space of conics passing through
any point of a general complete intersection has constant dimension if
is small compared to
Investigation of HIV-1 Gag binding with RNAs and Lipids using Atomic Force Microscopy
Atomic Force Microscopy was utilized to study the morphology of Gag,
{\Psi}RNA, and their binding complexes with lipids in a solution environment
with 0.1{\AA} vertical and 1nm lateral resolution. TARpolyA RNA was used as a
RNA control. The lipid used was phospha-tidylinositol-(4,5)-bisphosphate
(PI(4,5)P2). The morphology of specific complexes Gag-{\Psi}RNA, Gag-TARpolyA
RNA, Gag-PI(4,5)P2 and PI(4,5)P2-{\Psi}RNA-Gag were studied. They were imaged
on either positively or negatively charged mica substrates depending on the net
charges carried. Gag and its complexes consist of monomers, dimers and
tetramers, which was confirmed by gel electrophoresis. The addition of specific
{\Psi}RNA to Gag is found to increase Gag multimerization. Non-specific
TARpolyA RNA was found not to lead to an increase in Gag multimerization. The
addition PI(4,5)P2 to Gag increases Gag multimerization, but to a lesser extent
than {\Psi}RNA. When both {\Psi}RNA and PI(4,5)P2 are present Gag undergoes
comformational changes and an even higher degree of multimerization
Writing and Learning Online: Graduate Students’ Perceptions of Their Development as Writers and Teachers of Writing
This study examined the effect of an online graduate course in elementary and middle grades writing pedagogy on pre- and in-service teachers’ perceptions of themselves as writers and as teachers of writing. Eight graduate students enrolled in a summer online writing pedagogy course at a mid-sized regional university in the rural mountains of the southeastern United States participated in the study. Researchers collected qualitative data including reflections and blogs at the beginning and end of the 4.5-week course. Findings fell into four major themes in the data: (1)Past experience shapes perceptions of writing; (2)Perceptions shape writing instruction; (3)Perceptions are malleable; and, (4) Course design impacts students\u27 perceptions. We describe each of the four themes and give implications of our findings, including the need for further research on how the online format affects perceptions of writing and writing instruction
A novel minimal in vitro system for analyzing HIV-1 Gag mediated budding
A biomimetic minimalist model membrane was used to study the mechanism and
kinetics of cell-free in vitro HIV-1 Gag budding from a giant unilamellar
vesicle (GUV). Real time interaction of Gag, RNA and lipid leading to the
formation of mini-vesicles was measured using confocal microscopy. Gag forms
resolution limited punctae on the GUV lipid membrane. Introduction of the Gag
and urea to a GUV solution containing RNA led to the budding of mini-vesicles
on the inside surface of the GUV. The GUV diameter showed a linear decrease in
time due to bud formation. Both bud formation and decrease in GUV size were
proportional to Gag concentration. In the absence of RNA, addition of urea to
GUVs incubated with Gag also resulted in subvesicle formation but exterior to
the surface. These observations suggest the possibility that clustering of GAG
proteins leads to membrane invagination even in the absence of host cell
proteins. The method presented here is promising, and allows for systematic
study of the dynamics of assembly of immature HIV and help classify the
hierarchy of factors that impact the Gag protein initiated assembly of
retroviruses such as HIV.Comment: 27 pages, 9 Figures and 0 Table
An Exploratory Study on Sustainable ICT Capability in the Travel and Tourism Industry: The Case of a Global Distribution System Provider
Climate change is one of the biggest challenges facing humanity today. Environmental values have spread globally and consumer beliefs are pressurizing firms in almost all industries to comply with green regulations. Sustainability has become such an important part of business strategy that almost every major company now has an executive with “sustainability” in their title. The travel and tourism industry produced 14 percent of global greenhouse gas emissions in 2010. Policy makers have responded with ambitious targets. The European Union aims to achieve a 60 percent reduction in transport sector emissions by 2050. This exploratory study draws on the sustainable ICT capability maturity framework (SICT-CMF) and the case of the Amadeus IT Group, a large travel and tourism industry corporate enterprise that specializes in IT solutions. The study investigates the current capability maturity level of sustainable ICT in the company. The findings suggest that the company is a market leader in terms of sustainability initiatives and that it demonstrates an “advanced” level of sustainability capability. We discuss the lessons learned from Amadeus’ experience
Pre-Operative Status and Quality of Life Following Total Joint Replacement in a Developing Country: A Prospective Pilot Study
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Enhancing the quality of international orthopedic medical mission trips using the blue distinction criteria for knee and hip replacement centers
Background: Several organizations seek to address the growing burden of arthritis in developing countries by providing total joint replacements (TJR) to patients with advanced arthritis who otherwise would not have access to these procedures. Because these mission trips operate in resource poor environments, some of the features typically associated with high quality care may be difficult to implement. In the U.S., many hospitals that perform TJRs use the Blue Cross/Shield’s Blue Distinction criteria as benchmarks of high quality care. Although these criteria were designed for use in the U.S., we applied them to Operation Walk (Op-Walk) Boston’s medical mission trip to the Dominican Republic. Evaluating the program using these criteria illustrated that the program provides high quality care and, more importantly, helped the program to find areas of improvement. Methods: We used the Blue Distinction criteria to determine if Op-Walk Boston achieves Blue Distinction. Each criterion was grouped according to the four categories included in the Blue Distinction criteria— “general and administrative”, “structure”, “process”, or “outcomes and volume”. Full points were given for criteria that the program replicates entirely and zero points were given for criteria that are not replicated entirely. Of the non-replicated criteria, Op-Walk Boston’s clinical and administrative teams were asked if they compensate for failure to meet the criterion, and they were also asked to identify barriers that prevent them from meeting the criterion. Results: Out of 100 possible points, the program received 71, exceeding the 60-point threshold needed to qualify as a Blue Distinction center. The program met five out of eight “required” criteria and 11 out of 19 “informational” criteria. It scored 14/27 in the “general” category, 30/36 in the “structure” category, 17/20 in the “process” category, and 10/17 in the “outcomes and volume” category. Conclusion: Op-Walk Boston qualified for Blue Distinction. Our analysis highlights areas of programmatic improvement and identifies targets for future quality improvement initiatives. Additionally, we note that many criteria can only be met by hospitals operating in the U.S. Future work should therefore focus on creating criteria that are applicable to TJR mission trips in the context of developing countries
Stiction, Adhesion Energy and the Casimir Effect in Micromechanical Systems
We measure the adhesion energy of gold using a micromachined doubly-clamped
beam. The stress and stiffness of the beam are characterized by measuring the
spectrum of mechanical vibrations and the deflection due to an external force.
To determine the adhesion energy we induce stiction between the beam and a
nearby surface by capillary forces. Subsequent analysis yields a value J/m that is a factor of approximately six smaller than predicted
by idealized theory. This discrepancy may be resolved with revised models that
include surface roughness and the effect of adsorbed monolayers intervening
between the contacting surfaces in these mesoscopic structures.Comment: RevTex, 4 pages, 4 eps figure
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Participation in physical activity in patients 1–4 years post total joint replacement in the Dominican Republic
Background: To address both the growing burden of joint disease and the gaps in medical access in developing nations, medical relief organizations have begun to launch programs to perform total joint replacement (TJR) on resident populations in developing countries. One outcome of TJR of particular interest is physical activity (PA) since it is strongly linked to general health. This study evaluates the amount of postoperative participation in PA in low-income patients who received total joint replacement in the Dominican Republic and identifies preoperative predictors of postoperative PA level. Methods: We used the Yale Physical Activity Survey (YPAS) to assess participation in postoperative PA 1–4 years following total knee or hip replacement. We compared the amount of aerobic PA reported by postoperative TJR patients with the levels of PA recommended by the CDC and WHO. We also analyzed preoperative determinants of postoperative participation in aerobic PA in bivariate and multivariate analyses. Results: 64 patients out of 170 eligible subjects (52/128 TKR and 14/42 THR) who received TJR between 2009–2012 returned for an annual follow-up visit in 2013, with a mean treatment-to-follow-up time of 2.1 years. 43.3% of respondents met CDC/WHO criteria for sufficient participation in aerobic PA. Multivariate analyses including data from 56 individuals identified that patients who were both younger than 65 and at least two years postoperative had an adjusted mean activity dimensions summary index (ADSI) 22.9 points higher than patients who were 65 or older and one year postoperative. Patients who lived with friends or family had adjusted mean ADSI 17.2 points higher than patients living alone. Patients who had the most optimistic preoperative expectations of outcome had adjusted mean ADSI scores that were 19.8 points higher than those who were less optimistic. Conclusion: The TJR patients in the Dominican cohort participate in less PA than recommended by the CDC/WHO. Additionally, several associations were identified that potentially affect PA in this population; specifically, participants who are older than 65, recently postoperative, less optimistic about postoperative outcomes and who live alone participate in less PA
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