12,034 research outputs found
Molecular Hydrogen Emission from Protoplanetary Disks
We have modeled self-consistently the density and temperature profiles of gas
and dust in protoplanetary disks, taking into account irradiation from a
central star. Making use of this physical structure, we have calculated the
level populations of molecular hydrogen and the line emission from the disks.
As a result, we can reproduce the observed strong line spectra of molecular
hydrogen from protoplanetary disks, both in the ultraviolet (UV) and the
near-infrared, but only if the central star has a strong UV excess radiation.Comment: 19 pages, accepted for publication in Astronomy and Astrophysic
Watching the hands of the Arabidopsis biological clock
Oligonucleotide and cDNA microarrays have been used to analyse the mRNA levels of 8,000 genes in Arabidopsis thaliana throughout the day/night cycle. Genes involved in signal transduction and in various metabolic pathways were found to be coordinately regulated by circadian rhythms and/or by light
Modelling the widespread effects of TOC1 signalling on the plant circadian clock and its outputs
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. This work was supported by the European Commission FP7 Collaborative Project TiMet (project 245143). SynthSys is a Centre for Integrative and Systems Biology supported by BBSRC and EPSRC award D019621. Work in P.M. laboratory is supported by grants from the RamĂłn Areces Foundation, from the Spanish Ministry of Science and Innovation (MICINN) (BIO2010-16483) and from EUROHORCS (European Heads Of Research Councils) and the European Science Foundation (ESF) through the EURYI Award.Peer reviewedPublisher PD
National and Regional Estimates of the Prevalence of Opiate and/or Crack Cocaine use 2008-09: A summary of key findings
<p>This report summarises the results of a follow-up study
to a three year project to estimate the prevalence of
âproblem drug useâ (defined as use of opiates and/or
crack cocaine) nationally (England only), regionally and
locally. The follow-up was carried out two years after the
final sweep of the original project, so could therefore
be considered as âsweep 5â. An overview of the national
and regional estimates are presented in this report, as are
comparisons with the estimates produced by the third
(2006-07) sweep of the study. Estimates for 2007-08 are
not available as a study was not commissioned for that
year.</p>
<p>Information about the number of people who use illicit
drugs such as heroin, other opiates or crack cocaine
is key to formulating effective policies for tackling
drug-related harm as these drugs are associated with
the highest levels of harm. It also helps inform service
provision at the local level and provides a context
in which to understand the population impact of
interventions to reduce drug-related harm.</p>
<p>Direct enumeration of those engaged in a largely covert
activity such as the use of class A drugs is difficult
and standard household survey techniques tend to
underestimate the extent of such activity. Indirect
techniques making use of various data sources offer a
more reliable way of calculating prevalence estimates for
the use of opiates and/or crack cocaine. The estimates
presented in this report are derived using two indirect
measurement techniques: the capture-recapture
method (CRC ); and the multiple indicator (MIM ) method.
These methods are described in detail in Hay et al., 2006
and Hay et al., 2007a. Methodological developments
throughout the course of the previous three sweeps are
discussed elsewhere (Hay et al., 2007b, Hay et al., 2008).
The individuals covered by this study were people aged
15 to 64 and resident in each DAT area, and known to
be using heroin, methadone, other opiate drugs or
crack cocaine.</p>
Critical issues in mentoring research
Introduction
Research into the activity of mentoring has grown at a significant rate in the last twenty years (Allen, Eby, OâBrien & Lentz, 2008; Janssen, Vuuren & Jong, 2015) as has the range of inter-disciplinary subjects associated with mentoring, such as business, education, entrepreneurship, nursing and psychology (De Four, Pegg & Beck, 2015; Kochan, 2013; Laukhuf & Malone, 2015; Underhill, 2006).
Allen et al.âs (2008) review of organizational mentoring literature â consisting of two hundred and seven individual research studies, published in sixty different journals acknowledged the growing interest and research on the topic of mentoring. The authors attributed this to the increasing recognition that formal and informal mentoring is associated with behavioral, attitudinal and career benefits for mentees and mentors (Allen et al., 2004; Eby et al., 2008; Ghosh & Reio, 2013). Additionally, over the last ten years there have been an increasing number of evaluations of mentoring research processes and practices (Allen et al., 2008; Bozeman & Feeney, 2007; Janssen, Vuuren & Jong, 2015; Kammeyer-Mueller & Judge, 2008; Underhill, 2006). A broad range of mentoring studies are explored in this chapter within the context of identifying the critical issues involved in assuring the quality of mentoring research.
Purpose and Overview
The aim of this chapter is to provide an in-depth analysis of the critical issues related to the quality of research processes and strategies used in contemporary inter-disciplinary scholarly literature in mentoring. Further, it seeks to expand researcher and practitioner perspectives about this issues that will ultimately enhance the research about and practice of mentoring.
The chapter begins with an outline of the process used to identify critical issues in assuring quality in mentoring research. This is followed by a discussion of each of the eight critical issues identified through this process, referring to specific studies that illustrate the degree to which quality is achieved. The final section posits the way ahead for mentoring research
The process of infection with bacteriophage phiX174, XXX. Replication of double-stranded phiX DNA
Intermediates involved in the replication of double-stranded phiX174 RF DNA have been identified and partially characterized. Analysis of pulse-labeled RF DNA suggests that the synthesis of progeny RF molecules involves, in part, the addition of nucleotides to linear complementary strands on a circular parental strand as template, so as to produce intermediate DNA strands of greater than viral length. Electron microscopy reveals DNA rings with "tails" and "double rings," which could be the intermediate structures. A model is postulated for the replication process
Torsion and bending of nucleic acids studied by subnanosecond time-resolved fluorescence depolarization of intercalated dyes
Subnanosecond timeâresolved fluorescence depolarization has been used to monitor the reorientation of ethidium bromide intercalated in native DNA, synthetic polynucleotide complexes, and in supercoiled plasmid DNA. The fluorescence polarization anisotropy was successfully analyzed with an elastic model of DNA dynamics, including both torsion and bending, which yielded an accurate value for the torsional rigidity of the different DNA samples. The dependence of the torsional rigidity on the base sequence, helical structure, and tertiary structure was experimentally observed. The magnitude of the polyelectrolyte contribution to the torsional rigidity of DNA was measured over a wide range of ionic strength, and compared with polyelectrolyte theories for the persistence length. We also observed a rapid initial reorientation of the intercalated ethidium which had a much smaller amplitude in RNA than in DNA
A New Operation on Sequences: the Boustrouphedon Transform
A generalization of the Seidel-Entringer-Arnold method for calculating the
alternating permutation numbers (or secant-tangent numbers) leads to a new
operation on integer sequences, the Boustrophedon transform.Comment: very minor change: corrected typo in author list. June 24 2002:
correction to a proof; additional reference
- âŠ