133 research outputs found
Computing the Mertens and Meissel-Mertens constants for sums over arithmetic progressions
We give explicit numerical values with 100 decimal digits for the Mertens
constant involved in the asymptotic formula for and, as a by-product, for the Meissel-Mertens constant
defined as , for , ...,
and .Comment: 12 pages, 6 table
Scale invariant correlations and the distribution of prime numbers
Negative correlations in the distribution of prime numbers are found to
display a scale invariance. This occurs in conjunction with a nonstationary
behavior. We compare the prime number series to a type of fractional Brownian
motion which incorporates both the scale invariance and the nonstationary
behavior. Interesting discrepancies remain. The scale invariance also appears
to imply the Riemann hypothesis and we study the use of the former as a test of
the latter.Comment: 13 pages, 8 figures, version to appear in J. Phys.
Exciton Spin Dynamics in Semiconductor Quantum Wells
In this paper we will review Exciton Spin Dynamics in Semiconductor Quantum
Wells. The spin properties of excitons in nanostructures are determined by
their fine structure. We will mainly focus in this review on GaAs and InGaAs
quantum wells which are model systems.Comment: 55 pages, 27 figure
MSH3 polymorphisms and protein levels affect CAG repeat instability in huntington's disease mice
Expansions of trinucleotide CAG/CTG repeats in somatic tissues are thought to contribute to ongoing disease progression through an affected individual's life with Huntington's disease or myotonic dystrophy. Broad ranges of repeat instability arise between individuals with expanded repeats, suggesting the existence of modifiers of repeat instability. Mice with expanded CAG/CTG repeats show variable levels of instability depending upon mouse strain. However, to date the genetic modifiers underlying these differences have not been identified. We show that in liver and striatum the R6/1 Huntington's disease (HD) (CAG)~100 transgene, when present in a congenic C57BL/6J (B6) background, incurred expansion-biased repeat mutations, whereas the repeat was stable in a congenic BALB/cByJ (CBy) background. Reciprocal congenic mice revealed the Msh3 gene as the determinant for the differences in repeat instability. Expansion bias was observed in congenic mice homozygous for the B6 Msh3 gene on a CBy background, while the CAG tract was stabilized in congenics homozygous for the CBy Msh3 gene on a B6 background. The CAG stabilization was as dramatic as genetic deficiency of Msh2. The B6 and CBy Msh3 genes had identical promoters but differed in coding regions and showed strikingly different protein levels. B6 MSH3 variant protein is highly expressed and associated with CAG expansions, while the CBy MSH3 variant protein is expressed at barely detectable levels, associating with CAG stability. The DHFR protein, which is divergently transcribed from a promoter shared by the Msh3 gene, did not show varied levels between mouse strains. Thus, naturally occurring MSH3 protein polymorphisms are modifiers of CAG repeat instability, likely through variable MSH3 protein stability. Since evidence supports that somatic CAG instability is a modifier and predictor of disease, our data are consistent with the hypothesis that variable levels of CAG instability associated with polymorphisms of DNA repair genes may have prognostic implications for various repeat-associated diseases
Sugary interfaces mitigate contact damage where stiff meets soft
The byssal threads of the fan shell Atrina pectinata are non-living functional materials intimately associated with living tissue, which provide an intriguing paradigm of bionic interface for robust load-bearing device. An interfacial load-bearing protein (A. pectinata foot protein-1, apfp-1) with L-3,4-dihydroxyphenylalanine (DOPA)-containing and mannose-binding domains has been characterized from Atrina's foot. apfp-1 was localized at the interface between stiff byssus and the soft tissue by immunochemical staining and confocal Raman imaging, implying that apfp-1 is an interfacial linker between the byssus and soft tissue, that is, the DOPA-containing domain interacts with itself and other byssal proteins via Fe3(+)-DOPA complexes, and the mannose-binding domain interacts with the soft tissue and cell membranes. Both DOPA-and sugar-mediated bindings are reversible and robust under wet conditions. This work shows the combination of DOPA and sugar chemistry at asymmetric interfaces is unprecedented and highly relevant to bionic interface design for tissue engineering and bionic devices
Early psychological care of the French victims of the Costa Concordia shipwreck
Most of the French passengers who survived the shipwreck of the cruise ship Costa Concordia were repatriatedfrom Italy to Marseille, one of the stopovers of the cruise. The shipwreck happened during the nightof 13th–14th January 2012 and entailed the forced evacuation of 4195 passengers and crewmembers.Thirty-two persons died and 2 others are still reported missing. The massive and unexpected inflow of402 French citizens in the port of Marseille required the quick setting up of welcome facilities, not only tosolve logistical problems, but also to address psychological and sometimes even medical problems. ThePrehospital Psychological Emergency Service (CUMP) and the Prehospital Emergency Medical Service(SAMU) of Marseille examined 196 persons in total, and were able to avoid a great number of emergencyadmissions deemed necessary because of difficult psychological situations (death, missing or lost persons,acute stress). The objective of this report is to rapidly present the emergency committee as a whole andto describe in more detail the work that the CUMP accomplished during the 36 hours necessary to takecharge of the majority of the French passengers of the Costa Concordia.Most of the French passengers who survived the shipwreck of the cruise ship Costa Concordia were repatriatedfrom Italy to Marseille, one of the stopovers of the cruise. The shipwreck happened during the nightof 13th–14th January 2012 and entailed the forced evacuation of 4195 passengers and crewmembers.Thirty-two persons died and 2 others are still reported missing. The massive and unexpected inflow of402 French citizens in the port of Marseille required the quick setting up of welcome facilities, not only tosolve logistical problems, but also to address psychological and sometimes even medical problems. ThePrehospital Psychological Emergency Service (CUMP) and the Prehospital Emergency Medical Service(SAMU) of Marseille examined 196 persons in total, and were able to avoid a great number of emergencyadmissions deemed necessary because of difficult psychological situations (death, missing or lost persons,acute stress). The objective of this report is to rapidly present the emergency committee as a whole andto describe in more detail the work that the CUMP accomplished during the 36 hours necessary to takecharge of the majority of the French passengers of the Costa Concordia
Patterns and flow in frictional fluid dynamics
Pattern-forming processes in simple fluids and suspensions have been studied extensively, and the basic displacement structures, similar to viscous fingers and fractals in capillary dominated flows, have been identified. However, the fundamental displacement morphologies in frictional fluids and granular mixtures have not been mapped out. Here we consider Coulomb friction and compressibility in the fluid dynamics, and discover surprising responses including highly intermittent flow and a transition to quasi-continuodynamics. Moreover, by varying the injection rate over several orders of magnitude, we characterize new dynamic modes ranging from stick-slip bubbles at low rate to destabilized viscous fingers at high rate. We classify the fluid dynamics into frictional and viscous regimes, and present a unified description of emerging morphologies in granular mixtures in the form of extended phase diagrams
Phonon driven transport in amorphous semiconductors: Transition probabilities
Inspired by Holstein's work on small polaron hopping, the evolution equations
of localized states and extended states in presence of atomic vibrations are
derived for an amorphous semiconductor. The transition probabilities are
obtained for four types of transitions: from one localized state to another
localized state, from a localized state to an extended state, from an extended
state to a localized state, and from one extended state to another extended
state. At a temperature not too low, any process involving localized state is
activated. The computed mobility of the transitions between localized states
agrees with the observed `hopping mobility'. We suggest that the observed
`drift mobility' originates from the transitions from localized states to
extended states. Analysis of the transition probability from an extended state
to a localized state suggests that there exists a short-lifetime belt of
extended states inside conduction band or valence band. It agrees with the fact
that photoluminescence lifetime decreases with frequency in a-Si/SiO
quantum well while photoluminescence lifetime is not sensitive to frequency in
c-Si/SiO structure.Comment: 41 pages, 3 figures, submitted to Phys. Rev.
The Psychological Science Accelerator's COVID-19 rapid-response dataset
In response to the COVID-19 pandemic, the Psychological Science Accelerator coordinated three large-scale psychological studies to examine the effects of loss-gain framing, cognitive reappraisals, and autonomy framing manipulations on behavioral intentions and affective measures. The data collected (April to October 2020) included specific measures for each experimental study, a general questionnaire examining health prevention behaviors and COVID-19 experience, geographical and cultural context characterization, and demographic information for each participant. Each participant started the study with the same general questions and then was randomized to complete either one longer experiment or two shorter experiments. Data were provided by 73,223 participants with varying completion rates. Participants completed the survey from 111 geopolitical regions in 44 unique languages/dialects. The anonymized dataset described here is provided in both raw and processed formats to facilitate re-use and further analyses. The dataset offers secondary analytic opportunities to explore coping, framing, and self-determination across a diverse, global sample obtained at the onset of the COVID-19 pandemic, which can be merged with other time-sampled or geographic data
How reproducible are methods to measure the dynamic viscoelastic properties of poroelastic media?
There is a considerable number of research publications on the acoustical properties of porous media with an elastic frame. A simple search through the Web of Science™ (last accessed 21 March 2018) suggests that there are at least 819 publications which deal with the acoustics of poroelastic media. A majority of these researches require accurate knowledge of the elastic properties over a broad frequency range. However, the accuracy of the measurement of the dynamic elastic properties of poroelastic media has been a contentious issue. The novelty of this paper is that it studies the reproducibility of some popular experimental methods which are used routinely to measure the key elastic properties such as the dynamic Young's modulus, loss factor and Poisson ratio of poroelastic media. In this paper, fourteen independent sets of laboratory measurements were performed on specimens of the same porous materials. The results from these measurements suggest that the reproducibility of this type of experimental method is poor. This work can be helpful to suggest improvements which can be developed to harmonize the way the elastic properties of poroelastic media are measured worldwide
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