593 research outputs found
Limit analysis of conical and parabolic domes based on semi-analytical solution
The evaluation of limit loads of masonry domes has received increasing interest especially due to the importance of historical buildings where domes mainly are one of the most relevant structures. The limit design is used to obtain the safety assessment and the design guidance for restoration and transformation toward preservation and reuse of historical heritage. In the following paper, we present a formulation of the limit analysis based on the semi-analytical approach that starts on Melan's theorem. The self-equilibrated Melan's residual is obtained through the discretization of the analytical form of the equilibrium equation of the spherical dome. The procedure provides a finite-dimensional map of the eigenstress of the structure. Furthermore, the superimposition of the elastic solution to actual loads, obtained by finite element calculation, completes the admissible stress evaluation. Such amissible stress is introduced into the maximization algorithm, based on the lower bound theorem, which results in the collapse load. The same approach is used to get the safety assessment under prescribed load that allows checking the safety of prescribed load pattern and geometry
Microbial community structure and soil pH correspond to methane production in Arctic Alaska soils
While there is no doubt that biogenic methane production in the Arctic is an important aspect of global methane emissions, the relative roles of microbial community characteristics and soil environmental conditions in controlling Arctic methane emissions remains uncertain. Here, relevant methane‐cycling microbial groups were investigated at two remote Arctic sites with respect to soil potential methane production (PMP). Percent abundances of methanogens and iron‐reducing bacteria correlated with increased PMP, while methanotrophs correlated with decreased PMP. Interestingly, α‐diversity of the methanogens was positively correlated with PMP, while β‐diversity was unrelated to PMP. The β‐diversity of the entire microbial community, however, was related to PMP. Shannon diversity was a better correlate of PMP than Simpson diversity across analyses, while rarefied species richness was a weak correlate of PMP. These results demonstrate the following: first, soil pH and microbial community structure both probably control methane production in Arctic soils. Second, there may be high functional redundancy in the methanogens with regard to methane production. Third, iron‐reducing bacteria co‐occur with methanogens in Arctic soils, and iron‐reduction‐mediated effects on methanogenesis may be controlled by α‐ and β‐diversity. And finally, species evenness and rare species abundances may be driving relationships between microbial groups, influencing Arctic methane production
Desain dan Uji Coba Lembar Kerja Peserta Didik (Lkpd) Berbasis Sets (Science, Environment, Technology, And Society) pada Materi Koloid
This research aimed at knowing the level of validity and practicality students workbook SETS (Science, Environment, Technology and Society) Based on Colloid Lesson. It was a Research and Development (R&D) Method with 4-D Model. It was administered at State Senior High School 1 East Kampar. Subject of this research were Media design expert, Learning material expert, Chemistry teacher and Fifteenth studenst. Object of this research were SETS (Science, Environment, Technology and Society) Based on Colloid Lesson. the Instrument of collecting the data were questionnaire of validity test by the experts and questionnaire of practicality test by taecher and students. student workbook was appropriate, if it was valid and practice aspect qualify.The validity and practicality could be seen from the result of validity and practicality using sheet of validity and practicalisation. student workbook resulting was tested with the validity level was 88.125% (Very valid)and practice was 90.4% (Very practice). The research result indentify that Student Workbook was tested, it appropriate to be an additional teaching teacher at school.
Keywords : Student Workbook, SETS, Colloi
Functionally graded plate fracture analysis using the field boundary element method
This paper describes the Field Boundary Element Method (FBEM) applied to the fracture analysis of a 2D rectangular plate made of Functionally Graded Material (FGM) to calculate Mode I Stress Intensity Factor (SIF). The case study of this Field Boundary Element Method is the transversely isotropic plane plate. Its material presents an exponential variation of the elasticity tensor depending on a scalar function of position, i.e., the elastic tensor results from multiplying a scalar function by a constant taken as a reference. Several examples using a parametric representation of the structural response show the suitability of the method that constitutes a Stress Intensity Factor evaluation of Functionally Graded Materials plane plates even in the case of more complex geometries
Hypertriglyceridemic waist identifies HIV+ men and women at increased cardiometabolic risk
Screening for increased waist circumference and hypertriglyceridemia (the hypertriglyceridemic-waist phenotype) is an inexpensive approach to identify patients at risk of coronary artery disease in apparently healthy individuals who may be at increased risk of type 2 diabetes and coronary heart disease because of an excess of intra-abdominal (visceral) fat. We examined the ralationship between the hypertriglyceridemic-waist and selected cardiometabolic risk factors in HIV individuals
Environmental controls on ozone fluxes in a poplar plantation in Western Europe
Tropospheric O-3 is a strong oxidant that may affect vegetation and human health. Here we report on the O-3 fluxes from a poplar plantation in Belgium during one year. Surprisingly, the winter and autumn O-3 fluxes were of similar magnitude to ones observed during most of the peak vegetation development. Largest O-3 uptakes were recorded at the beginning of the growing season in correspondence to a minimum stomatal uptake. Wind speed was the most important control and explained 44% of the variability in the nighttime O-3 fluxes, suggesting that turbulent mixing and the mechanical destruction of O-3 played a substantial role in the O-3 fluxes. The stomatal O-3 uptake accounted for a seasonal average of 59% of the total O-3 uptake. Multiple regression and partial correlation analyses showed that net ecosystem exchange was not affected by the stomatal O-3 uptake. (C) 2013 The Authors. Published by Elsevier Ltd. All rights reserved
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Mechanistic Modeling of Microtopographic Impacts on CO2 and CH4 Fluxes in an Alaskan Tundra Ecosystem Using the CLM-Microbe Model
Spatial heterogeneities in soil hydrology have been confirmed as a key control on CO2 and CH4 fluxes in the Arctic tundra ecosystem. In this study, we applied a mechanistic ecosystem model, CLM-Microbe, to examine the microtopographic impacts on CO2 and CH4 fluxes across seven landscape types in Utqiaġvik, Alaska: trough, low-centered polygon (LCP) center, LCP transition, LCP rim, high-centered polygon (HCP) center, HCP transition, and HCP rim. We first validated the CLM-Microbe model against static-chamber measured CO2 and CH4 fluxes in 2013 for three landscape types: trough, LCP center, and LCP rim. Model application showed that low-elevation and thus wetter landscape types (i.e., trough, transitions, and LCP center) had larger CH4 emissions rates with greater seasonal variations than high-elevation and drier landscape types (rims and HCP center). Sensitivity analysis indicated that substrate availability for methanogenesis (acetate, CO2 + H2) is the most important factor determining CH4 emission, and vegetation physiological properties largely affect the net ecosystem carbon exchange and ecosystem respiration in Arctic tundra ecosystems. Modeled CH4 emissions for different microtopographic features were upscaled to the eddy covariance (EC) domain with an area-weighted approach before validation against EC-measured CH4 fluxes. The model underestimated the EC-measured CH4 flux by 20% and 25% at daily and hourly time steps, suggesting the importance of the time step in reporting CH4 flux. The strong microtopographic impacts on CO2 and CH4 fluxes call for a model-data integration framework for better understanding and predicting carbon flux in the highly heterogeneous Arctic landscape
SUMOylation inhibits FOXM1 activity and delays mitotic transition
The forkhead box transcription factor FOXM1 is an essential effector of G2/M-phase transition, mitosis and the DNA damage response. As such, it is frequently deregulated during tumorigenesis. Here we report that FOXM1 is dynamically modified by SUMO1 but not by SUMO2/3 at multiple sites. We show that FOXM1 SUMOylation is enhanced in MCF-7 breast cancer cells in response to treatment with epirubicin and mitotic inhibitors. Mutation of five consensus conjugation motifs yielded a SUMOylation-deficient mutant FOXM1. Conversely, fusion of the E2 ligase Ubc9 to FOXM1 generated an auto-SUMOylating mutant (FOXM1-Ubc9). Analysis of wild-type FOXM1 and mutants revealed that SUMOylation inhibits FOXM1 activity, promotes translocation to the cytoplasm and enhances APC/Cdh1-mediated ubiquitination and degradation. Further, expression of the SUMOylation-deficient mutant enhanced cell proliferation compared with wild-type FOXM1, whereas the FOXM1-Ubc9 fusion protein resulted in persistent cyclin B1 expression and slowed the time from mitotic entry to exit. In summary, our findings suggest that SUMOylation attenuates FOXM1 activity and causes mitotic delay in cytotoxic drug response
Cancer incidence in Italian contaminated sites
INTRODUCTION: The incidence of cancer among residents in sites contaminated by
pollutants with a possible health impact is not adequately studied. In Italy,
SENTIERI Project (Epidemiological study of residents in National Priority
Contaminated Sites, NPCSs) was implemented to study major health outcomes for
residents in 44 NPCSs.
METHODS: The Italian Association of Cancer Registries (AIRTUM) records cancer
incidence in 23 NPCSs. For each NPCSs, the incidence of all malignant cancers
combined and 35 cancer sites (coded according to ICD-10), was analysed
(1996-2005). The observed cases were compared to the expected based on age
(5-year period,18 classes), gender, calendar period (1996-2000; 2001-2005),
geographical area (North-Centre and Centre-South) and cancer sites specific
rates. Standardized Incidence Ratios (SIR) with 90% Confidence Intervals were
computed.
RESULTS: In both genders an excess was observed for overall cancer incidence (9%
in men and 7% in women) as well as for specific cancer sites (colon and rectum,
liver, gallblad-der, pancreas, lung, skin melanoma, bladder and Non Hodgkin
lymphoma). Deficits were observed for gastric cancer in both genders, chronic
lymphoid leukemia (men), malignant thyroid neoplasms, corpus uteri and connective
and soft-tissue tumours and sarcomas (women).
DISCUSSION: This report is, to our knowledge, the first one on cancer risk of
residents in NPCSs. The study, although not aiming to estimate the cancer burden
attributable to the environment as compared to occupation or life-style, supports
the credibility of an etiologic role of environmental exposures in contaminated
sites. Ongoing analyses focus on the interpretation of risk factors for excesses
of specific cancer types overall and in specific NPCSs in relation to the
presence of carcinogenic pollutants
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