3,821 research outputs found
Age- and activity-related differences in the abundance of Myosin essential and regulatory light chains in human muscle
Traditional methods for phenotyping skeletal muscle (e.g., immunohistochemistry) are labor-intensive and ill-suited to multixplex analysis, i.e., assays must be performed in a series. Addressing these concerns represents a largely unmet research need but more comprehensive parallel analysis of myofibrillar proteins could advance knowledge regarding age- and activity-dependent changes in human muscle. We report a label-free, semi-automated and time efficient LC-MS proteomic workflow for phenotyping the myofibrillar proteome. Application of this workflow in old and young as well as trained and untrained human skeletal muscle yielded several novel observations that were subsequently verified by multiple reaction monitoring (MRM).We report novel data demonstrating that human ageing is associated with lesser myosin light chain 1 content and greater myosin light chain 3 content, consistent with an age-related reduction in type II muscle fibers. We also disambiguate conflicting data regarding myosin regulatory light chain, revealing that age-related changes in this protein more closely reflect physical activity status than ageing per se. This finding reinforces the need to control for physical activity levels when investigating the natural process of ageing. Taken together, our data confirm and extend knowledge regarding age- and activity-related phenotypes. In addition, the MRM transitions described here provide a methodological platform that can be fine-tuned to suite multiple research needs and thus advance myofibrillar phenotyping
Ambient vibration survey of the Bosporus Suspension Bridge
This is the peer reviewed version of the article, which has been published in final form at DOI 10.1002/eqe.4290180210. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.Traffic and wind excitation has been used to obtain the dynamic characteristics of the first Bosporus (Bogazici) Suspension Bridge. Structural symmetry and the absence of suspended side-spans allowed attention to be focused on the main span and the Asian tower. For the main span, 18 vertical and 20 lateral modes were obtained, including torsional modes. For the tower, 12 longitudinal and 12 lateral modes were identified. All these models lie in the range 0–1-1 Hz.
A detailed comparison is given between these modes and corresponding calculated modes, obtained by use of a three-dimensional finite element model which includes a geometric stiffness matrix. Of particular interest is the validity of the theoretical model used for the box-deck, because of its subsequent use in response studies of asynchronous seismic excitation.
Comparison with a more limited study made in 1973 shows that the bridge continues to behave as it was designed to behave, particularly with regard to the deck-tower interface. From natural frequency measurements of two hangers, the load which they carry was assessed
A Comparison of Measured and Self-Reported Blood Pressure Status among Low-Income Housing Residents in New York City
Self-report is widely used to measure hypertension prevalence in population-based studies, but there is little research comparing self-report with measured blood pressure among low-income populations. The objective of this study was to compare self-reported and measured blood pressure status among a sample of low-income housing residents in New York City (n=118). We completed a cross-sectional analysis comparing self-report with measured blood pressure status. We determined the sensitivity, specificity, and positive predictive value (PPV) of each self-report metric. Of the sample, 68.1% was Black, 71.1% had a household income under $25,000/year, and 28.5% did not complete high school. In our study, there was a discrepancy in the prevalence hypertension by self-report (30.5%) versus measurement (39.8%). PPV of self-report was 94.4%. Specificity was 97.2%. Hypertension awareness (sensitivity) was 72.3%. Of individuals not reporting hypertension, 15.9% had measurements in the hypertensive range and 43.9% had measurements in the borderline hypertensive range. Our findings suggest that self-reported and objective measures of hypertension are incongruent among low-income housing residents and may have important implications for population-based research among low-income populations
Radiographic features of liver allograft rejection
The radiographic features of 19 transplanted patients with failure of the liver allograft were evaluated. These features were: poor filling, stretching, attenuation of intrahepatic biliary ducts documented by T-tube cholangiogram, attenuation of branches of the hepatic artery seen on angiogram as well as a decrease of blood flow through the liver seen on angiogram and nuclear medicine dynamic scintigram. These findings were secondary to swelling of the transplanted liver and were not specific for rejection; they may also be present in hepatic infarction or infection
Adaptive matched field processing in an uncertain propagation environment
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution January 1992Adaptive array processing algorithms have achieved widespread use because they are
very effective at rejecting unwanted signals (i.e., controlling sidelobe levels) and in
general have very good resolution (i.e., have narrow mainlobes). However, many
adaptive high-resolution array processing algorithms suffer a significant degradation
in performance in the presence of environmental mismatch. This sensitivity to environmental
mismatch is of particular concern in problems such as long-range acoustic
array processing in the ocean where the array processor's knowledge of the propagation
characteristics of the ocean is imperfect. An Adaptive Minmax Matched Field
Processor has been developed which combines adaptive matched field processing and
minmax approximation techniques to achieve the effective interference rejection characteristic
of adaptive processors while limiting the sensitivity of the processor to
environmental mismatch.
The derivation of the algorithm is carried out within the framework of minmax
signal processing. The optimal array weights are those which minimize the maximum
conditional mean squared estimation error at the output of a linear weight-and-sum
beamformer. The error is conditioned on the propagation characteristics of the environment
and the maximum is evaluated over the range of environmental conditions in
which the processor is expected to operate. The theorems developed using this framework
characterize the solutions to the minmax array weight problem, and relate the
optimal minmax array weights to the solution to a particular type of Wiener filtering
problem. This relationship makes possible the development of an efficient algorithm
for calculating the optimal minmax array weights and the associated estimate of the
signal power emitted by a source at the array focal point. An important feature of
this algorithm is that it is guarenteed to converge to an exact solution for the array
weights and estimated signal power in a finite number of iterations. The Adaptive Minmax Matched Field Processor can also be interpreted as a two-stage
Minimum Variance Distortionless Response (MVDR) Matched Field Processor.
The first stage of this processor generates an estimate of the replica vector of the signal
emitted by a source at the array focal point, and the second stage is a traditional
MVDR Matched Field Processor implemented using the estimate of the signal replica
vector.
Computer simulations using several environmental models and types of environmental
uncertainty have shown that the resolution and interference rejection capability
of the Adaptive Minmax Matched Field Processor is close to that of a traditional
MVDR Matched Field Processor which has perfect knowledge of the characteristics
of the propagation environment and far exceeds that of the Bartlett Matched Field
Processor. In addition, the simulations show that the Adaptive Minmax Matched
Field Processor is able to maintain it's accuracy, resolution and interference rejection
capability when it's knowledge of the environment is only approximate, and is therefore
much less sensitive to environmental mismatch than is the traditional MVDR
Matched Field Processor.The National
Science Foundation, the General Electric Foundation, the Office of Naval Research,
the Defense Advanced Research Projects Agency, and the Woods Hole Oceanographic
Institution
Critical success factors and improvements in ISO 9000 maintenance / Roslina Ab Wahid and James Corner
The purpose of the ISO 9000 standards is to facilitate the multinational exchange of
products and services by providing a clear set of quality systems requirements. It is
also to assist organizations of all sectors and sizes to implement and operate an
effective quality management system (QMS). The generic nature of the standards
allows interested companies to determine the specifics of how the standards apply to
its organization. Registration or certification to the standards demonstrates to
customers that the supplying organization has achieved a basic level of quality
assurance by the formalization and documentation of its quality management system.
However, there is a lacking in the literature on the post-certification period as most of
the published work focuses on how to obtain certification and the impact of
certification on ISO 9000-certified companies. Thus, studies do not generally address
what happens after the companies have obtained their certification
Urinary Perchlorate and Thyroid Hormone Levels in Adolescent and Adult Men and Women Living in the United States
BACKGROUND: Perchlorate is commonly found in the environment and known to inhibit thyroid function at high doses. Assessing the potential effect of low-level exposure to perchlorate on thyroid function is an area of ongoing research. OBJECTIVES: We evaluated the potential relationship between urinary levels of perchlorate and serum levels of thyroid stimulating hormone (TSH) and total thyroxine (T(4)) in 2,299 men and women, ≥ 12 years of age, participating in the National Health and Nutrition Examination Survey (NHANES) during 2001–2002. METHODS: We used multiple regression models of T(4) and TSH that included perchlorate and covariates known to be or likely to be associated with T(4) or TSH levels: age, race/ethnicity, body mass index, estrogen use, menopausal status, pregnancy status, premenarche status, serum C-reactive protein, serum albumin, serum cotinine, hours of fasting, urinary thiocyanate, urinary nitrate, and selected medication groups. RESULTS: Perchlorate was not a significant predictor of T(4) or TSH levels in men. For women overall, perchlorate was a significant predictor of both T(4) and TSH. For women with urinary iodine < 100 μg/L, perchlorate was a significant negative predictor of T(4) (p < 0.0001) and a positive predictor of TSH (p = 0.001). For women with urinary iodine ≥ 100 μg/L, perchlorate was a significant positive predictor of TSH (p = 0.025) but not T(4) (p = 0.550). CONCLUSIONS: These associations of perchlorate with T(4) and TSH are coherent in direction and independent of other variables known to affect thyroid function, but are present at perchlorate exposure levels that were unanticipated based on previous studies
The Science and Practice of Carcinogen Identification and Evaluation
Several national and international health agencies have established programs with the aim of identifying agents and exposures that cause cancer in humans. Carcinogen identification is an activity grounded in the scientific evaluation of the results of human epidemiologic studies, long-term bioassays in experimental animals, and other data relevant to an evaluation of carcinogenicity and its mechanisms. In this commentary, after a brief discussion of the science basis common to the evaluation of carcinogens across different programs, we discuss in more detail the principles and procedures currently used by the IARC Monographs program
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