2,420 research outputs found
New method for critical failure prediction of complex systems
Rigorous analytical technique, called criticality determination methodology /or CD technique/ determines the probability that a given complex system will successfully achieve stated objectives. The CD technique identifies critical elements of the system by a failure mode and effects analysis
When Zebras Run with Horses: The Diagnostic Dilemma of Acute Aortic Dissection Complicated by Myocardial Infarction
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72234/1/j.1540-8183.2002.tb01107.x.pd
Body temperatures of modern and extinct vertebrates from ^(13)C-^(18)O bond abundances in bioapatite
The stable isotope compositions of biologically precipitated apatite in bone, teeth, and scales are widely used to obtain information on the diet, behavior, and physiology of extinct organisms and to reconstruct past climate. Here we report the application of a new type of geochemical measurement to bioapatite, a “clumped-isotope” paleothermometer, based on the thermodynamically driven preference for ^(13)C and ^(18)O to bond with each other within carbonate ions in the bioapatite crystal lattice. This effect is dependent on temperature but, unlike conventional stable isotope paleothermometers, is independent from the isotopic composition of water from which the mineral formed. We show that the abundance of ^(13)C-^(18)O bonds in the carbonate component of tooth bioapatite from modern specimens decreases with increasing body temperature of the animal, following a relationship between isotope “clumping” and temperature that is statistically indistinguishable from inorganic calcite. This result is in agreement with a theoretical model of isotopic ordering in carbonate ion groups in apatite and calcite. This thermometer constrains body temperatures of bioapatite-producing organisms with an accuracy of 1–2 °C. Analyses of fossilized tooth enamel of both Pleistocene and Miocene age yielded temperatures within error of those derived from similar modern taxa. Clumped-isotope analysis of bioapatite represents a new approach in the study of the thermophysiology of extinct species, allowing the first direct measurement of their body temperatures. It will also open new avenues in the study of paleoclimate, as the measurement of clumped isotopes in phosphorites and fossils has the potential to reconstruct environmental temperatures
Physical Performance Differences in Sea, Air and Land (SEAL) Operator Cohorts Separated by Demographics
Please refer to the pdf version of the abstract located adjacent to the title
From Relational Data to Graphs: Inferring Significant Links using Generalized Hypergeometric Ensembles
The inference of network topologies from relational data is an important
problem in data analysis. Exemplary applications include the reconstruction of
social ties from data on human interactions, the inference of gene
co-expression networks from DNA microarray data, or the learning of semantic
relationships based on co-occurrences of words in documents. Solving these
problems requires techniques to infer significant links in noisy relational
data. In this short paper, we propose a new statistical modeling framework to
address this challenge. It builds on generalized hypergeometric ensembles, a
class of generative stochastic models that give rise to analytically tractable
probability spaces of directed, multi-edge graphs. We show how this framework
can be used to assess the significance of links in noisy relational data. We
illustrate our method in two data sets capturing spatio-temporal proximity
relations between actors in a social system. The results show that our
analytical framework provides a new approach to infer significant links from
relational data, with interesting perspectives for the mining of data on social
systems.Comment: 10 pages, 8 figures, accepted at SocInfo201
Spatiotemporal correlations of handset-based service usages
We study spatiotemporal correlations and temporal diversities of
handset-based service usages by analyzing a dataset that includes detailed
information about locations and service usages of 124 users over 16 months. By
constructing the spatiotemporal trajectories of the users we detect several
meaningful places or contexts for each one of them and show how the context
affects the service usage patterns. We find that temporal patterns of service
usages are bound to the typical weekly cycles of humans, yet they show maximal
activities at different times. We first discuss their temporal correlations and
then investigate the time-ordering behavior of communication services like
calls being followed by the non-communication services like applications. We
also find that the behavioral overlap network based on the clustering of
temporal patterns is comparable to the communication network of users. Our
approach provides a useful framework for handset-based data analysis and helps
us to understand the complexities of information and communications technology
enabled human behavior.Comment: 11 pages, 15 figure
Side-to-Side Knee Strength Imbalances and Increased Odds of Reporting Injury in Military Special Forces Operators
Please see the pdf version of the abstract
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Long-term neurotoxicity of chemotherapy in adolescents and young adults treated for bone and soft tissue sarcomas.
Purpose. To study the long-term neurotoxicity of chemotherapy in adolescents and young adults treated for bone and soft tissue sarcomas.Patients and Methods. Thirty-six adolescents and young adults (median age 17 years) were examined following chemotherapy for bone and soft tissue sarcomas. Twenty-nine (29/36) had received cisplatin (median 400 mg/m(2)), 15/36 ifosfamide (median 20 g/m(2)), and 12/36 vincristine (median 16 mg). Neurotoxicity was assessed at a median of 8 months (range, 1-54 months) after completion of chemotherapy by clinical examination, nerve conduction studies, audiograms and autonomic function tests. The same nerve conduction studies were carried out in 20 normal volunteers to define normal ranges in this age group.Results. Sixteen patients (44%) had a significant reduction in deep tendon reflexes, and this clinical parameter correlated well with abnormalities detected in nerve conduction studies. Vibration perception threshold (VPT) was raised in 20/36 patients (55%) and this was the most sensitive single test in the assessment of neuropathy. There was a significant correlation between VPT and cumulative cisplatin dose received in mg/m(-2) (r=0.607, p<0.01). Ten of 29 patients (35%) had abnormal nerve conduction studies with a pattern characteristic of sensory axonal neuropathy. No patient complained of auditory symptoms, but minor high tone hearing loss was detected by audiograms in 5/28 patients who had received cisplatin. No patients had symptoms of autonomic neuropathy, but autonomic function tests showed minor abnormalities in 4/22 patients tested, and all had received cisplatin.Conclusions. This study demonstrates significant, although asymptomatic, long-term neurotoxicity of cisplatin in adolescents and young adults receiving chemotherapy for bone and soft tissue sarcomas. Follow-up studies are planned to assess whether these neurological deficits improve with time.Peer Reviewe
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The 6-minute walk test and other endpoints in Duchenne muscular dystrophy: longitudinal natural history observations over 48 weeks from a multicenter study.
IntroductionDuchenne muscular dystrophy (DMD) subjects ≥5 years with nonsense mutations were followed for 48 weeks in a multicenter, randomized, double-blind, placebo-controlled trial of ataluren. Placebo arm data (N = 57) provided insight into the natural history of the 6-minute walk test (6MWT) and other endpoints.MethodsEvaluations performed every 6 weeks included the 6-minute walk distance (6MWD), timed function tests (TFTs), and quantitative strength using hand-held myometry.ResultsBaseline age (≥7 years), 6MWD, and selected TFT performance are strong predictors of decline in ambulation (Δ6MWD) and time to 10% worsening in 6MWD. A baseline 6MWD of <350 meters was associated with greater functional decline, and loss of ambulation was only seen in those with baseline 6MWD <325 meters. Only 1 of 42 (2.3%) subjects able to stand from supine lost ambulation.ConclusionFindings confirm the clinical meaningfulness of the 6MWD as the most accepted primary clinical endpoint in ambulatory DMD trials
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