455 research outputs found
Evolutionary response of Caragana (Fabaceae) to Qinghai-Tibetan Plateau uplift and Asian interior aridification
Caragana is endemic to temperate Asia, with most species distributed on the Qinghai-Tibetan Plateau (QTP) and in Northwestern China. Consequently its biogeography should be hypothesized to have been affected by QTP uplift. To examine the biogeography of Caragana in relation to QTP uplift and consequent interior aridification, we conducted molecular dating analyses based on three genes (ITS, cpDNA trnS-trnG and rbcL). Results from relaxed Bayesian BEAST, relaxed Bayesian Multidivtime, and PL (penalized likelihood) indicate that QTP uplift, especially the onset of Himalayan motion at 21-17 Ma, triggered the origin of Caragana (with estimated ages 16-14 Ma). The subsequent QTP rapid uplift at 8 Ma is inferred to have driven the evolution and diversification of the three major clades of Caragana: section Caragana (northern China and the Junggar-Altai-Sayan region), section Frutescentes (Central Asia), and sections Bracteolatae and Jubatae, centered in the QTP. A rapid and active speciation process occurring in the QTP intense uplift at 3.4-1.8 Ma, is indicated by the chronogram
A Status Report on Conflict Analysis in Mixed Integer Nonlinear Programming
Mixed integer nonlinear programs (MINLPs) are arguably among the hardest
optimization problems, with a wide range of applications. MINLP solvers that
are based on linear relaxations and spatial branching work similar as mixed
integer programming (MIP) solvers in the sense that they are based on a
branch-and-cut algorithm, enhanced by various heuristics, domain propagation,
and presolving techniques. However, the analysis of infeasible subproblems,
which is an important component of most major MIP solvers, has been hardly
studied in the context of MINLPs. There are two main approaches for
infeasibility analysis in MIP solvers: conflict graph analysis, which
originates from artificial intelligence and constraint programming, and dual
ray analysis.
The main contribution of this short paper is twofold. Firstly, we present the
first computational study regarding the impact of dual ray analysis on convex
and nonconvex MINLPs. In that context, we introduce a modified generation of
infeasibility proofs that incorporates linearization cuts that are only locally
valid. Secondly, we describe an extension of conflict analysis that works
directly with the nonlinear relaxation of convex MINLPs instead of considering
a linear relaxation. This is work-in-progress, and this short paper is meant to
present first theoretical considerations without a computational study for that
part
Materials flow control in hybrid make-to-stock/make-to-order manufacturing
Today’s company competiveness is favoured by product customisation and fast delivery. A strategy to meet this challenge is to manufacture standard items to stock for product customisation. This configures a hybrid environment of make-to-stock and make-to-order. To explore the advantages of this requires good understanding of production control. Thus, we study production under hybrid MTS-MTO, organising the system in two stages. The 1 st manufactures items to inventory, which are then customised in the 2 nd . We analyse how the percentage of tardy orders is affected by the inventory of items required to achieve a given fill rate. The impact of two mechanisms for releasing orders to both stages is also analysed. Results of a simulation study indicate that most of the reduction on the percentage of tardy orders is achieved by a moderate increase in the stock level of semi-finished products. Moreover the percentage of tardy orders decreases if suitable controlled release of orders is exerted.This study had the financial support of FCT-Fundação para a Ciência e Tecnologia of Portugal under the project PEst2015-2020: UID/CEC/ 00319/2013.info:eu-repo/semantics/publishedVersio
Phylogeny of Salsoleae s.l. (Chenopodiaceae) based on DNA sequence data from ITS, psbB-psbH, and rbcL, with emphasis on taxa of northwestern China
To reconstruct phylogeny and verify the monophyly of major subgroups, a total of 52 species representing almost all species of Salsoleae s.l. in China were sampled, with analysis based on three molecular markers (nrDNA ITS, cpDNA psbB psbH and thcL), using maximum parsimony, maximum likelihood, and Bayesian inference methods Our molecular evidence provides strong support for the following: (1) Camphorosmeae is nested within Salsoleae s.l. instead of the previously suggested sister relationship. (2) Tribe Salsoleae s.I is monophyletic and is composed of three monophyletic subunits, Caroxyloneae, the Kali clade, and Salsoleae s.str (3) Climacoptera is separated from Salsola s I It does not form a monophyletic group but is split into two monophyletic parts, Climacoptera I and Chmacoptera II (4) Halogeton is clearly polyphyletic, as are Anabasis and the genus Salsola s.l. (5) Caroxylon, Halo.xylon, Kali, and Petrosnnonia are well-supported monophyletic genera. Additional evidence is needed regarding the monophyly of Halimocnemis, which remains unclear
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Cosmogenic neutron production at the Sudbury Neutrino Observatory
Neutrons produced in nuclear interactions initiated by cosmic-ray muons present an irreducible background to many rare-event searches, even in detectors located deep underground. Models for the production of these neutrons have been tested against previous experimental data, but the extrapolation to deeper sites is not well understood. Here we report results from an analysis of cosmogenically produced neutrons at the Sudbury Neutrino Observatory. A specific set of observables are presented, which can be used to benchmark the validity of geant4 physics models. In addition, the cosmogenic neutron yield, in units of 10-4 cm2/(g·μ), is measured to be 7.28±0.09(stat)-1.12+1.59(syst) in pure heavy water and 7.30±0.07(stat)-1.02+1.40(syst) in NaCl-loaded heavy water. These results provide unique insights into this potential background source for experiments at SNOLAB
Exploiting Anopheles responses to thermal, odour and visual stimuli to improve surveillance and control of malaria
Mosquito surveillance and control are at the heart of efforts to eliminate malaria, however, there remain significant gaps in our understanding of mosquito behaviour that impede innovation. We hypothesised that a combination of human-associated stimuli could be used to attract and kill malaria vectors more successfully than individual stimuli, and at least as well as a real human. To test this in the field, we quantified Anopheles responses to olfactory, visual and thermal stimuli in Burkina Faso using a simple adhesive trap. Traps baited with human odour plus high contrast visual stimuli caught more Anopheles than traps with odour alone, showing that despite their nocturnal habit, malaria vectors make use of visual cues in host-seeking. The best performing traps, however, combined odour and visual stimuli with a thermal signature in the range equivalent to human body temperature. When tested against a human landing catch during peak mosquito abundance, this “host decoy” trap caught nearly ten times the number of Anopheles mosquitoes caught by a human collector. Exploiting the behavioural responses of mosquitoes to the entire suite of host stimuli promises to revolutionise vector surveillance and provide new paradigms in disease control
Stress-Induced Reinstatement of Drug Seeking: 20 Years of Progress
In human addicts, drug relapse and craving are often provoked by stress. Since 1995, this clinical scenario has been studied using a rat model of stress-induced reinstatement of drug seeking. Here, we first discuss the generality of stress-induced reinstatement to different drugs of abuse, different stressors, and different behavioral procedures. We also discuss neuropharmacological mechanisms, and brain areas and circuits controlling stress-induced reinstatement of drug seeking. We conclude by discussing results from translational human laboratory studies and clinical trials that were inspired by results from rat studies on stress-induced reinstatement. Our main conclusions are (1) The phenomenon of stress-induced reinstatement, first shown with an intermittent footshock stressor in rats trained to self-administer heroin, generalizes to other abused drugs, including cocaine, methamphetamine, nicotine, and alcohol, and is also observed in the conditioned place preference model in rats and mice. This phenomenon, however, is stressor specific and not all stressors induce reinstatement of drug seeking. (2) Neuropharmacological studies indicate the involvement of corticotropin-releasing factor (CRF), noradrenaline, dopamine, glutamate, kappa/dynorphin, and several other peptide and neurotransmitter systems in stress-induced reinstatement. Neuropharmacology and circuitry studies indicate the involvement of CRF and noradrenaline transmission in bed nucleus of stria terminalis and central amygdala, and dopamine, CRF, kappa/dynorphin, and glutamate transmission in other components of the mesocorticolimbic dopamine system (ventral tegmental area, medial prefrontal cortex, orbitofrontal cortex, and nucleus accumbens). (3) Translational human laboratory studies and a recent clinical trial study show the efficacy of alpha-2 adrenoceptor agonists in decreasing stress-induced drug craving and stress-induced initial heroin lapse
Keeping an eye on noisy movements: On different approaches to perceptual-motor skill research and training
Contemporary theorising on the complementary nature of perception and action in expert performance has led to the emergence of different emphases in studying movement coordination and gaze behaviour. On the one hand, coordination research has examined the role that variability plays in movement control, evidencing that variability facilitates individualised adaptations during both learning and performance. On the other hand, and at odds with this principle, the majority of gaze behaviour studies have tended to average data over participants and trials, proposing the importance of universal 'optimal' gaze patterns in a given task, for all performers, irrespective of stage of learning. In this article, new lines of inquiry are considered with the aim of reconciling these two distinct approaches. The role that inter- and intra-individual variability may play in gaze behaviours is considered, before suggesting directions for future research
Genome analysis and physiological comparison of Alicycliphilus denitrificans strains BC and K601T
The genomes of the Betaproteobacteria Alicycliphilus denitrificans strains BC and K601T have been sequenced to get insight into the physiology of the two strains. Strain BC degrades benzene with chlorate as electron acceptor. The cyclohexanol-degrading denitrifying strain K601T is not able to use chlorate as electron acceptor, while strain BC cannot degrade cyclohexanol. The 16S rRNA sequences of strains BC and K601T are identical and the fatty acid methyl ester patterns of the strains are similar. Basic Local Alignment Search Tool (BLAST) analysis of predicted open reading frames of both strains showed most hits with Acidovorax sp. JS42, a bacterium that degrades nitro-aromatics. The genomes include strain-specific plasmids (pAlide201 in strain K601T and pAlide01 and pAlide02 in strain BC). Key genes of chlorate reduction in strain BC were located on a 120 kb megaplasmid (pAlide01), which was absent in strain K601T. Genes involved in cyclohexanol degradation were only found in strain K601T. Benzene and toluene are degraded via oxygenase-mediated pathways in both strains. Genes involved in the meta-cleavage pathway of catechol are present in the genomes of both strains. Strain BC also contains all genes of the ortho-cleavage pathway. The large number of mono- and dioxygenase genes in the genomes suggests that the two strains have a broader substrate range than known thus far.This research was supported by the Technology Foundation, the Applied Science Division (STW) of the Netherlands Organization for Scientific Research (NWO), project number 08053, the graduate school WIMEK (Wageningen Institute for Environment and Climate Research, which is part of SENSE Research School for Socio-Economic and Natural Sciences of the Environment, www.wimek-new.wur.nl and www.sense.nl), SKB (Dutch Centre for Soil Quality Management and Knowledge Transfer, www.skbodem.nl) and the Consolider project CSD-2007-00055. The research was incorporated in the TRIAS (TRIpartite Approaches 469 toward Soil systems processes) program (http://www.nwo.nl/en/research-and-results/programmes/alw/trias-tripartite-approach-to-soil-system-processes/index. html). Flávia Talarico Saia was supported by a FAPESP (the State of São Paulo Research Foundation) scholarship (2006-01997/5). The work conducted by the DOE JGI is supported by the Office of Science of the United States Department of Energy under contract number DE-AC02-05CH11231. Alfons Stams acknowledges support by an ERC (European Research Counsil) advanced grant (project 323009). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
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Measurement of neutron production in atmospheric neutrino interactions at the Sudbury Neutrino Observatory
Neutron production in GeV-scale neutrino interactions is a poorly studied
process. We have measured the neutron multiplicities in atmospheric neutrino
interactions in the Sudbury Neutrino Observatory experiment and compared them
to the prediction of a Monte Carlo simulation using GENIE and a minimally
modified version of GEANT4. We analyzed 837 days of exposure corresponding to
Phase I, using pure heavy water, and Phase II, using a mixture of Cl in heavy
water. Neutrons produced in atmospheric neutrino interactions were identified
with an efficiency of and , for Phase I and II respectively.
The neutron production is measured as a function of the visible energy of the
neutrino interaction and, for charged current quasi-elastic interaction
candidates, also as a function of the neutrino energy. This study is also
performed classifying the complete sample into two pairs of event categories:
charged current quasi-elastic and non charged current quasi-elastic, and
and . Results show good overall agreement between data and
Monte Carlo for both phases, with some small tension with a statistical
significance below for some intermediate energies
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