770 research outputs found
A quantum McKay correspondence for fractional 2p-branes on LG orbifolds
We study fractional 2p-branes and their intersection numbers in non-compact
orbifolds as well the continuation of these objects in Kahler moduli space to
coherent sheaves in the corresponding smooth non-compact Calabi-Yau manifolds.
We show that the restriction of these objects to compact Calabi-Yau
hypersurfaces gives the new fractional branes in LG orbifolds constructed by
Ashok et. al. in hep-th/0401135. We thus demonstrate the equivalence of the
B-type branes corresponding to linear boundary conditions in LG orbifolds,
originally constructed in hep-th/9907131, to a subset of those constructed in
LG orbifolds using boundary fermions and matrix factorization of the
world-sheet superpotential. The relationship between the coherent sheaves
corresponding to the fractional two-branes leads to a generalization of the
McKay correspondence that we call the quantum McKay correspondence due to a
close parallel with the construction of branes on non-supersymmetric orbifolds.
We also provide evidence that the boundary states associated to these branes in
a conformal field theory description corresponds to a sub-class of the boundary
states associated to the permutation branes in the Gepner model associated with
the LG orbifold.Comment: LaTeX2e, 1+39 pages, 3 figures (v2) refs added, typos and report no.
correcte
Large-scale heterospecific segregation distortion in Populus revealed by a dense genetic map
Abstract We report the most complete genetic map to have been constructed for the genus Populus
Tropospheric O 3 moderates responses of temperate hardwood forests to elevated CO 2 : a synthesis of molecular to ecosystem results from the Aspen FACE project
1. The impacts of elevated atmospheric CO 2 and/or O 3 have been examined over 4 years using an open-air exposure system in an aggrading northern temperate forest containing two different functional groups (the indeterminate, pioneer, O 3 -sensitive species Trembling Aspen, Populus tremuloides and Paper Birch, Betula papyrifera , and the determinate, late successional, O 3 -tolerant species Sugar Maple, Acer saccharum ). 2. The responses to these interacting greenhouse gases have been remarkably consistent in pure Aspen stands and in mixed Aspen/Birch and Aspen/Maple stands, from leaf to ecosystem level, for O 3 -tolerant as well as O 3 -sensitive genotypes and across various trophic levels. These two gases act in opposing ways, and even at low concentrations (1·5 × ambient, with ambient averaging 34–36 nL L −1 during the summer daylight hours), O 3 offsets or moderates the responses induced by elevated CO 2 . 3. After 3 years of exposure to 560 µmol mol −1 CO 2 , the above-ground volume of Aspen stands was 40% above those grown at ambient CO 2 , and there was no indication of a diminishing growth trend. In contrast, O 3 at 1·5 × ambient completely offset the growth enhancement by CO 2 , both for O 3 -sensitive and O 3 -tolerant clones. Implications of this finding for carbon sequestration, plantations to reduce excess CO 2 , and global models of forest productivity and climate change are presented.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72125/1/j.1365-2435.2003.00733.x.pd
The Growing Up in Singapore Towards Healthy Outcomes Study
Objective Epidemiological studies relating maternal 25-hydroxyvitamin D
(25OHD) with gestational diabetes mellitus (GDM) and mode of delivery have
shown controversial results. We examined if maternal 25OHD status was
associated with plasma glucose concentrations, risks of GDM and caesarean
section in the Growing Up in Singapore Towards healthy Outcomes (GUSTO) study.
Methods Plasma 25OHD concentrations, fasting glucose (FG) and 2-hour
postprandial glucose (2HPPG) concentrations were measured in 940 women from a
Singapore mother-offspring cohort study at 26–28 weeks’ gestation. 25OHD
inadequacy and adequacy were defined based on concentrations of 25OHD
≤75nmol/l and >75nmol/l respectively. Mode of delivery was obtained from
hospital records. Multiple linear regression was performed to examine the
association between 25OHD status and glucose concentrations, while multiple
logistic regression was performed to examine the association of 25OHD status
with risks of GDM and caesarean section. Results In total, 388 (41.3%) women
had 25OHD inadequacy. Of these, 131 (33.8%), 155 (39.9%) and 102 (26.3%) were
Chinese, Malay and Indian respectively. After adjustment for confounders,
maternal 25OHD inadequacy was associated with higher FG concentrations (β =
0.08mmol/l, 95% Confidence Interval (CI) = 0.01, 0.14), but not 2HPPG
concentrations and risk of GDM. A trend between 25OHD inadequacy and higher
likelihood of emergency caesarean section (Odds Ratio (OR) = 1.39, 95% CI =
0.95, 2.05) was observed. On stratification by ethnicity, the association with
higher FG concentrations was significant in Malay women (β = 0.19mmol/l, 95%
CI = 0.04, 0.33), while risk of emergency caesarean section was greater in
Chinese (OR = 1.90, 95% CI = 1.06, 3.43) and Indian women (OR = 2.41, 95% CI =
1.01, 5.73). Conclusions 25OHD inadequacy is prevalent in pregnant Singaporean
women, particularly among the Malay and Indian women. This is associated with
higher FG concentrations in Malay women, and increased risk of emergency
caesarean section in Chinese and Indian women
Exploiting HIV-1 protease and reverse transcriptase cross-resistance information for improved drug resistance prediction by means of multi-label classification
Analysis of human MDM4 variants in papillary thyroid carcinomas reveals new potential markers of cancer properties
A wild-type (wt) p53 gene characterizes thyroid tumors, except for the rare anaplastic histotype. Because p53 inactivation is a prerequisite for tumor development, alterations of p53 regulators represent an alternative way to impair p53 function. Indeed, murine double minute 2 (MDM2), the main p53 negative regulator, is overexpressed in many tumor histotypes including those of the thyroid. A new p53 regulator, MDM4 (a.k.a. MDMX or HDMX) an analog of MDM2, represents a new oncogene although its impact on tumor properties remains largely unexplored. We estimated levels of MDM2, MDM4, and its variants, MDM4-S (originally HDMX-S) and MDM4-211 (originally HDMX211), in a group of 57 papillary thyroid carcinomas (PTC), characterized by wt tumor protein 53, in comparison to matched contra-lateral lobe normal tissue. Further, we evaluated the association between expression levels of these genes and the histopathological features of tumors. Quantitative real-time polymerase chain reaction revealed a highly significant downregulation of MDM4 mRNA in tumor tissue compared to control tissue (P < 0.0001), a finding confirmed by western blot on a subset of 20 tissue pairs. Moreover, the tumor-to-normal ratio of MDM4 levels for each individual was significantly lower in late tumor stages, suggesting a specific downregulation of MDM4 expression with tumor progression. In comparison, MDM2 messenger RNA (mRNA) and protein levels were frequently upregulated with no correlation with MDM4 levels. Lastly, we frequently detected overexpression of MDM4-S mRNA and presence of the aberrant form, MDM4-211 in this tumor group. These findings indicate that MDM4 alterations are a frequent event in PTC. It is worthy to note that the significant downregulation of full-length MDM4 in PTC reveals a novel status of this factor in human cancer that counsels careful evaluation of its role in human tumorigenesis and of its potential as therapeutic target
U.S. Billion-ton Update: Biomass Supply for a Bioenergy and Bioproducts Industry
The Report, Biomass as Feedstock for a Bioenergy and Bioproducts Industry: The Technical Feasibility of a Billion-Ton Annual Supply (generally referred to as the Billion-Ton Study or 2005 BTS), was an estimate of “potential” biomass within the contiguous United States based on numerous assumptions about current and future inventory and production capacity, availability, and technology. In the 2005 BTS, a strategic analysis was undertaken to determine if U.S. agriculture and forest resources have the capability to potentially produce at least one billion dry tons of biomass annually, in a sustainable manner—enough to displace approximately 30% of the country’s present petroleum consumption. To ensure reasonable confidence in the study results, an effort was made to use relatively conservative assumptions. However, for both agriculture and forestry, the resource potential was not restricted by price. That is, all identified biomass was potentially available, even though some potential feedstock would more than likely be too expensive to actually be economically available.
In addition to updating the 2005 study, this report attempts to address a number of its shortcoming
'Physical activity at home (PAAH)', evaluation of a group versus home based physical activity program in community dwelling middle aged adults: rationale and study design
<p>Abstract</p> <p>Background</p> <p>It is well recognised that the adoption and longer term adherence to physical activity by adults to reduce the risk of chronic disease is a challenge. Interventions, such as group and home based physical activity programs, have been widely reported upon. However few studies have directly compared these interventions over the longer term to determine their adherence and effectiveness. Participant preference for home based or group interventions is important. Some evidence suggests that home based physical activity programs are preferred by middle aged adults and provide better long term physical activity adherence. Physiotherapists may also be useful in increasing physical activity adherence, with limited research on their impact.</p> <p>Methods</p> <p>'Physical Activity at Home' is a 2 year pragmatic randomised control trial, with a non-randomised comparison to group exercise. Middle-aged adults not interested in, or unable to attend, a group exercise program will be targeted. Sedentary community dwelling 50-65 year olds with no serious medical conditions or functional impairments will be recruited via two mail outs using the Australian federal electoral roll. The first mail out will invite participants to a 6 month community group exercise program. The second mail out will be sent to those not interested in the group exercise program inviting them to take part in a home based intervention. Eligible home based participants will be randomised into a 6 month physiotherapy-led home based physical activity program or usual care. Outcome measures will be taken at baseline, 6, 12, 18 and 24 months. The primary outcome is physical activity adherence via exercise diaries. Secondary outcomes include the Active Australia Survey, accelerometry, aerobic capacity (step test), quality of life (SF-12v2), blood pressure, waist circumference, waist-to-hip ratio and body mass index. Costs will be recorded prospectively and qualitative data will be collected.</p> <p>Discussion</p> <p>The planned 18 month follow-up post intervention will provide an indication of the effectiveness of the group and home based interventions in terms of adherence to physical activity, health benefits and cost. If the physiotherapy-led home based physical activity program is successful it could provide an alternative option for physical activity program delivery across a number of settings.</p> <p>Trial registration</p> <p>Australia and New Zealand Clinical Trials Register (ANZCTR): <a href="http://www.anzctr.org.au/ACTRN12611000890932.aspx">ACTRN12611000890932</a></p
The impact of disseminating the whole-community project '10,000 Steps': a RE-AIM analysis
<p>Abstract</p> <p>Background</p> <p>There are insufficient research reports on the wide-scale dissemination of effective whole-community physical activity (PA) programs. The purpose of this paper is to evaluate the impact of the wide-scale dissemination of '10,000 Steps', using the RE-AIM framework.</p> <p>Methods</p> <p>Dissemination efforts targeted a large region of Belgium and were concentrated on media strategies and peer networks of specific professional organizations, such as local health promotion services. Heads of department of 69 organizations received an on-line survey to assess project awareness, adoption, implementation and intended continuation of '10,000 Steps'. On the individual level, 755 citizens living in the work area of the organizations were interviewed for project awareness and PA levels. Measures were structured according to the RE-AIM dimensions (reach, effectiveness, adoption, implementation, maintenance). Independent sample <it>t </it>and chi-square tests were used to compare groups for representativeness at the organizational and individual level, and for individual PA differences.</p> <p>Results</p> <p>Of all organizations, 90% was aware of '10,000 Steps' (effectiveness - organizational level) and 36% adopted the project (adoption). The global implementation score was 52%. One third intended to continue the project in the future (maintenance) and 48% was still undecided. On the individual level, 35% of citizens were aware of '10,000 Steps' (reach). They reported significantly higher leisure-time PA levels than those not aware of '10,000 Steps' (256 ± 237 and 207 ± 216 min/week, respectively; <it>t </it>= -2.8; p < .005) (effectiveness - individual level). When considering representativeness, adoption of '10.000 Steps' was independent of most organizational characteristics, except for years of experience in PA promotion (7.6 ± 4.6 and 2.9 ± 5.9 years for project staff and non-project staff members, respectively; <it>t </it>= 2.79; <it>p </it>< 0.01). Project awareness in citizens was independent of all demographic characteristics.</p> <p>Conclusions</p> <p>'10,000 Steps' shows potential for wide-scale dissemination but a supportive linkage system seems recommended to encourage adoption levels and high quality implementation.</p
Gene-based association studies report genetic links for clinical subtypes of frontotemporal dementia
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