13,517 research outputs found
Recommended from our members
Empowering statistical methods for cellular and molecular biologists.
We provide guidelines for using statistical methods to analyze the types of experiments reported in cellular and molecular biology journals such as Molecular Biology of the Cell. Our aim is to help experimentalists use these methods skillfully, avoid mistakes, and extract the maximum amount of information from their laboratory work. We focus on comparing the average values of control and experimental samples. A Supplemental Tutorial provides examples of how to analyze experimental data using R software
Experience with duplex bearings in narrow angle oscillating applications
Duplex ball bearings are matched pairs on which the abutting faces of the rings have been accurately ground so that when the rings are clamped together, a controlled amount of interference (preload) exists across the balls. These bearings are vulnerable to radial temperature gradients, blocking in oscillation and increased sensitivity to contamination. These conditions decrease the service life of these bearings. It was decided that an accelerated thermal vacuum life test should be conducted. The test apparatus and results are described and the rationale is presented for reducing a multiyear life test on oil lubricated bearings to less than a year
Off-fault tensile cracks: A link between geological fault observations, lab experiments, and dynamic rupture models
We examine the local nature of the dynamic stress field in the vicinity of the tip of a semi-infinite sub-Rayleigh (slower than the Rayleigh wave speed, c_R) mode II crack with a velocity-weakening cohesive zone. We constrain the model using results from dynamic photoelastic experiments, in which shear ruptures were nucleated spontaneously in Homalite-100 plates along a bonded, precut, and inclined interface subject to a far-field uniaxial prestress. During the experiments, tensile cracks grew periodically along one side of the shear rupture interface at a roughly constant angle relative to the shear rupture interface. The occurrence and inclination of the tensile cracks are explained by our analytical model. With slight modifications, the model can be scaled to natural faults, providing diagnostic criteria for interpreting velocity, directivity, and static prestress state associated with past earthquakes on exhumed faults. Indirectly, this method also allows one to constrain the velocity-weakening nature of natural ruptures, providing an important link between field geology, laboratory experiments, and seismology
Using the ICF and psychological models of behavior to predict mobility limitations
Aims to test the ability of a model that integrates the theory of planned behavior (TPB) into the International Classification of Functioning Disability and Health (ICF) to predict walking limitations in adults awaiting hip or knee replacement surgery. Study Design and Participants: Cross-sectional structural equation modeling study of activity limitations in 190 adults. Method: A postal questionnaire measuring the TPB, ICF and walking limitations. Results: The integrated model accounted for more variance in activity limitations (57%) than either the TPB or ICF alone. Control beliefs (TPB) significantly mediated the relationship between impairment (ICF) and activity limitations. Conclusions: The integrated model provides an interdisciplinary theoretical framework that identifies intervention targets to effect reductions in disability without the need for concomitant reductions in impairment
A commentary on recent water safety initiatives in the context of water utility risk management.
Over the last decade, suppliers of drinking water have recognised the
limitations of relying solely on end-product monitoring to ensure safe water
quality and have sought to reinforce their approach by adopting preventative
strategies where risks are proactively identified, assessed and managed. This is
leading to the development of water safety plans; structured βroute mapsβ for
managing risks to water supply, from catchment to consumer taps. This paper
reviews the Hazard Analysis and Critical Control Point (HACCP) procedure on
which many water safety plans are based and considers its appropriateness in the
context of drinking water risk management. We examine water safety plans in a
broad context, looking at a variety of monitoring, optimisation and risk
management initiatives that can be taken to improve drinking water safety. These
are cross-compared using a simple framework that facilitates an integrated
approach to water safety. Finally, we look at how risk management practices are
being integrated across water companies and how this is likely to affect the
future development of water safety p
The Obligation for Biologists to Commit to Political Advocacy
I explain here why all scientists should feel obligated to do their part to support the community by advocating for the benefits of government investments in scientific research and training
Baby-Step Giant-Step Algorithms for the Symmetric Group
We study discrete logarithms in the setting of group actions. Suppose that
is a group that acts on a set . When , a solution
to can be thought of as a kind of logarithm. In this paper, we study
the case where , and develop analogs to the Shanks baby-step /
giant-step procedure for ordinary discrete logarithms. Specifically, we compute
two sets such that every permutation of can be
written as a product of elements and . Our
deterministic procedure is optimal up to constant factors, in the sense that
and can be computed in optimal asymptotic complexity, and and
are a small constant from in size. We also analyze randomized
"collision" algorithms for the same problem
Alternate fluffy testers for detecting and diagnosing chromosome rearrangements in Neurospora crassa.
Alternate fluffy testers for detecting and diagnosing chromosome rearrangements in Neurospora crassa
- β¦