66 research outputs found
Disentangling the influence of livestock vs. farm density on livestock disease epidemics
Susceptible host density is a key factor that influences the success of invading pathogens. However, for diseases affecting livestock, there are two aspects of host density: livestock and farm density, which are seldom considered independently. Traditional approaches of simulating disease outbreaks on realâworld farm data make dissecting the relative importance of farm and livestock density difficult owing to their inherent correlation in many farming regions. We took steps to disentangle these densities and study their relative influences on epidemic size by simulating footâandâmouth disease outbreaks on factorial combinations of cattle and farm populations in artificial county areas, resulting in 50 unique cattle/farm density combinations. In these simulations, increasing cattle density always resulted in larger epidemics, regardless of farm density. Alternatively, increasing farm density only led to larger epidemics in scenarios of high cattle density. We compared these results with simulations performed on realâworld farm data from the United States, where we initiated outbreaks in U.S. counties that varied in countyâlevel cattle density and farm density. We found a similar, but weaker relationship between cattle density and epidemic size in the U.S. simulations. We tested the sensitivity of these outcomes to variation in pathogen dispersal and farmâlevel susceptibility model parameters and found that although variation in these parameters quantitatively influenced the size of the epidemic, they did not qualitatively change the relative influence of cattle vs. farm density in factorial simulations. By reducing the correlation between farm and livestock density in factorial simulations, we were able to clearly demonstrate the increase in epidemic size that occurred as farm sizes grew larger (i.e., through increasing countyâlevel cattle populations), across levels of farm density. These results suggest livestock production trends in many industrialized countries that concentrate livestock on fewer, but larger farms have the potential to facilitate larger livestock epidemics
Can vitamin D status influence the effect of stress on planning and problem-solving? A randomized control trial
Background: Nutritional interventions may serve as a stress resilience strategy with important implications for human health.Objective: The aim of this study was to investigate the effect of vitamin D supplementation throughout wintertime on problem-solving and planning abilities during stressful circumstances.Design: A total of 77 male inpatients with a mean age of 48 years (range 31â81) and stress-related mental health disorders were randomly assigned into a Vitamin D supplement group (daily intake of 40 Îźg) or a pla-cebo supplement group (Control) (daily intake of 120 mg olive oil). The intervention period was from January 2018 to May 2018. The means and standard deviations for vitamin D status (25-hydroxyvitamin D3, nmol/L), pre- and post-test, respectively, were 58(21) and 46(15) for the Control group, and 63(18) and 76(21) for the Vitamin D group. Problem-solving and planning abilities were measured by the Tower of London (ToL) task pre- (midwinter) and post- (spring) supplement intervention. The ToL task was performed during exposure to distracting noise.Results: The results revealed that vitamin D supplementation throughout the winter had a significant effect on number of correct responses on easier (1 and 2 move) ToL problems during stress; the Vitamin D group improved significantly from pre- to post-test, whereas the Control group did not. In addition, the Vitamin D group had significantly more correct responses than the Control group on post-test. The improved perfor-mance was not related to a speed-accuracy trade off effect; both groups showed significantly decreased plan-ning times from pre- to post-test. The intervention did not differentially affect task performance on the more difficult (3 to 5 move) ToL problems. For the more demanding problems, IQ seemed to explain most of the variance regarding accuracy. Age explained most of the variance associated with task planning time.Conclusion: Vitamin D supplementation seemed to improve resilience to stress, but it was limited to performance of easier tasks.publishedVersio
Speed of ion trap quantum information processors
We investigate theoretically the speed limit of quantum gate operations for
ion trap quantum information processors. The proposed methods use laser pulses
for quantum gates which entangle the electronic and vibrational degrees of
freedom of the trapped ions. Two of these methods are studied in detail and for
both of them the speed is limited by a combination of the recoil frequency of
the relevant electronic transition, and the vibrational frequency in the trap.
We have experimentally studied the gate operations below and above this speed
limit. In the latter case, the fidelity is reduced, in agreement with our
theoretical findings. //
Changes: a) error in equ. 24 and table III repaired b) reference Jonathan et
al, quant-ph/ 0002092, added (proposes fast quantum gates using the AC-Stark
effect)Comment: 10 pages, 4 figure
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Multi-location wheat stripe rust QTL analysis: genetic background and epistatic interactions
Stripe rust is a foliar disease of wheat (Triticum aestivum L.) caused by the air-borne fungus Puccinia striiformis f. sp. tritici and is present in most regions around the world where commercial wheat is grown. Breeding for durable resistance to stripe rust continues to be a priority, but also is a challenge due to the complexity of interactions among resistance genes and to the wide diversity and continuous evolution of the pathogen races. The goal of this study was to detect chromosomal regions for resistance to stripe rust in two winter wheat populations, âTubbsâ/âNSA-98-0995â (T/N) and âEinsteinâ/âTubbsâ (E/T), evaluated across seven environments and mapped with diversity array technology and simple sequence repeat markers covering polymorphic regions of â1480 and 1117 cM, respectively. Analysis of variance for phenotypic data revealed significant (P < 0.01) genotypic differentiation for stripe rust among the recombinant inbred lines. Results for quantitative trait loci/locus (QTL) analysis in the E/T population indicated that two major QTL located in chromosomes 2AS and 6AL, with epistatic interaction between them, were responsible for the main phenotypic response. For the T/N population, eight QTL were identified, with those in chromosomes 2AL and 2BL accounting for the largest percentage of the phenotypic variance
Ion traps with enhanced optical and physical access
Small, controllable, highly accessible quantum systems can serve as probes at
the single quantum level to study multiple physical effects, for example in
quantum optics or for electric and magnetic field sensing. The applicability of
trapped atomic ions as probes is highly dependent on the measurement situation
at hand and thus calls for specialized traps. Previous approaches for ion traps
with enhanced optical access included traps consisting of a single ring
electrode or two opposing endcap electrodes. Other possibilities are planar
trap geometries, which have been investigated for Penning traps and rf-trap
arrays. By not having the electrodes lie in a common plane the optical access
in the latter cases can be substantially increased. Here, we discuss the
fabrication and experimental characterization of a novel radio-frequency (rf)
ion trap geometry. It has a relatively simple structure and provides largely
unrestricted optical and physical access to the ion, of up to 96% of the total
4pi solid angle in one of the three traps tested. We also discuss potential
applications in quantum optics and field sensing. As a force sensor, we
estimate sensitivity to forces smaller than 1 yN Hz^(-1/2).Comment: 6 pages, 3 figures. Corrections of some typos, application section
expanded to account for reviewer comment
Effect of within-species plant genotype mixing on habitat preference of a polyphagous insect predator
The effects of within-species plant genotype mixing on the habitat preference of a polyphagous ladybird were studied. Plant species diversity is often claimed to positively affect habitat preferences of insect predators, but the effects of within-species genotype diversity have not been extensively studied. In a field experiment with different barley (Hordeum vulgare) genotypes in mixed and pure stands, adult seven-spot ladybird Coccinella septempunctata, a polyphagous predator, preferred a specific combination of genotypes over the single genotypes alone before aphids had arrived in the crop, and again when aphids were emigrating. In laboratory experiments on adult ladybird orientation to odour from barley, ladybirds were attracted/arrested by the mixed odour of the same barley genotype mixture that was preferred in the field. Exposure of one barley genotype to volatiles from the other also caused the odour of the exposed plants to become more attractive to ladybirds. The results support the hypothesis that plant volatiles may attract or arrest foraging adult ladybirds, contributing to the selection of favourable habitats, and they show that within-species plant genotype mixing can shape interactions within multitrophic communities
Ion-trap quantum information processing: experimental status
Atomic ions trapped in ultra-high vacuum form an especially well-understood
and useful physical system for quantum information processing. They provide
excellent shielding of quantum information from environmental noise, while
strong, well-controlled laser interactions readily provide quantum logic gates.
A number of basic quantum information protocols have been demonstrated with
trapped ions. Much current work aims at the construction of large-scale
ion-trap quantum computers using complex microfabricated trap arrays. Several
groups are also actively pursuing quantum interfacing of trapped ions with
photons.Comment: review article for Frontiers of Physics replace corrupted TeX fil
A Re-conceptualization of Access for 21st Century Healthcare
Many e-health technologies are available to promote virtual patientâprovider communication outside the context of face-to-face clinical encounters. Current digital communication modalities include cell phones, smartphones, interactive voice response, text messages, e-mails, clinic-based interactive video, home-based web-cams, mobile smartphone two-way cameras, personal monitoring devices, kiosks, dashboards, personal health records, web-based portals, social networking sites, secure chat rooms, and on-line forums. Improvements in digital access could drastically diminish the geographical, temporal, and cultural access problems faced by many patients. Conversely, a growing digital divide could create greater access disparities for some populations. As the paradigm of healthcare delivery evolves towards greater reliance on non-encounter-based digital communications between patients and their care teams, it is critical that our theoretical conceptualization of access undergoes a concurrent paradigm shift to make it more relevant for the digital age. The traditional conceptualizations and indicators of access are not well adapted to measure access to health services that are delivered digitally outside the context of face-to-face encounters with providers. This paper provides an overview of digital âencounterlessâ utilization, discusses the weaknesses of traditional conceptual frameworks of access, presents a new access framework, provides recommendations for how to measure access in the new framework, and discusses future directions for research on access
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