ABSTRACT We have carried out simulations to predict the performance of a new space-based telescopic survey operating at thermal infrared wavelengths that seeks to discover and characterize a large ...fraction of the potentially hazardous near-Earth asteroid (NEA) population. Two potential architectures for the survey were considered: one located at the Earth-Sun L1 Lagrange point, and one in a Venus-trailing orbit. A sample cadence was formulated and tested, allowing for the self-follow-up necessary for objects discovered in the daytime sky on Earth. Synthetic populations of NEAs with sizes as small as 140 m in effective spherical diameter were simulated using recent determinations of their physical and orbital properties. Estimates of the instrumental sensitivity, integration times, and slew speeds were included for both architectures assuming the properties of newly developed large-format 10 m HgCdTe detector arrays capable of operating at ∼35 K. Our simulation included the creation of a preliminary version of a moving object processing pipeline suitable for operating on the trial cadence. We tested this pipeline on a simulated sky populated with astrophysical sources such as stars and galaxies extrapolated from Spitzer Space Telescope and Wide-field Infrared Explorer data, the catalog of known minor planets (including Main Belt asteroids, comets, Jovian Trojans, planets, etc.), and the synthetic NEA model. Trial orbits were computed for simulated position-time pairs extracted from the synthetic surveys to verify that the tested cadence would result in orbits suitable for recovering objects at a later time. Our results indicate that the Earth-Sun L1 and Venus-trailing surveys achieve similar levels of integral completeness for potentially hazardous asteroids larger than 140 m; placing the telescope in an interior orbit does not yield an improvement in discovery rates. This work serves as a necessary first step for the detailed planning of a next-generation NEA survey.
Background. Oseltamivir resistance among 2009 pandemic influenza A (H1N1) viruses (pH1N1) is rare. We investigated a cluster of oseltamivir-resistant pH1N1 infections in a hospital ward. Methods. We ...reviewed patient records and infection control measures and interviewed health care personnel (HCP) and visitors. Oseltamivir-resistant pH1N1 infections were found with real-time reverse-transcription polymerase chain reaction and pyrosequencing for the H275Y neuraminidase (NA) mutation. We compared hemagglutinin (HA) sequences from clinical samples from the outbreak with those of other surveillance viruses. Results. During the period 6-11 October 2009, 4 immunocompromised patients within a hematologyoncology ward exhibited symptoms of pHlNl infection. The likely index patient became febrile 8 days after completing a course of oseltamivir; isolation was instituted 9 days after symptom onset. Three other case patients developed symptoms 1, 3, and 5 days after the index patient. Three case patients were located in adjacent rooms. HA and NA sequences from case patients were identical. Twelve HCP and 6 visitors reported influenza symptoms during the study period. No other pHlNl isolates from the hospital or from throughout the state carried the H275Y mutation. Conclusions. Geographic proximity, temporal clustering, presence of H275Y mutation, and viral sequence homology confirmed nosocomial transmission of oseltamivir-resistant pH1N1. Diagnostic vigilance and prompt isolation may prevent nosocomial transmission of influenza.
The objective of this research was to develop and test methods for accessing and evaluating information on the biological plausibility of observed associations between exposures or interventions and ...outcomes to generate scientific evidence for action consistent with practice in systematic reviews.
To undertake this research, we used the example of the observed associations between antimicrobial use in food animals and increased risks of human exposures to antimicrobial-resistant pathogens of zoonotic origin.
We conducted a scoping search using terms related to biological plausibility or mechanism to identify key references. As recommended by these references, we also used expert consultation with researchers and a public health informationist. We used their recommendations, which included expert consultation, to identify mechanisms relevant to biological plausibility of the association we selected to test. We used the reviews conducted by the World Health Organization (WHO) Guidelines Development Group in support of reducing antimicrobial use in food animal production to populate our model for assessing biological plausibility.
We were able to develop a transparent model for biological plausibility based on the adverse outcome pathway used in toxicology and ecology. We were also able to populate this model using the WHO reviews.
This analysis of biological plausibility used transparent and validated methods to assess the evidence used in systematic reviews based on the observational studies accessed through searches of the scientific literature. Given the importance of this topic in systematic reviews and evidence-based decision-making, further research is needed to define and test the methodological approaches to access and properly evaluate information from the scientific literature.
•We can use tested criteria to reduce bias, including evidence of biological plausibility.•This is an important criterion since our evidence usually comes from observational studies.•We used methods from ecology and toxicology to assess evidence.•This model may be useful for other applications.
Simultaneous conversion of the two orthogonal phase components of an optical input to different output frequencies has been demonstrated by simulation and experiment. A single stage of four-wave ...mixing between the input signal and four pumps derived from a frequency comb was employed. The nonlinear device was a semiconductor optical amplifier, which provided overall signal gain and sufficient contrast for phase sensitive signal processing. The decomposition of a quadrature phase-shift keyed signal into a pair of binary phase-shift keyed outputs at different frequencies was also demonstrated by simulation.
A rough surface morphology is shown to significantly amplify the light-induced change in water contact angle of a photoresponsive surface. Smooth Si surfaces and fractally rough Si nanowire surfaces ...grown on a Si substrate were studied, both coated with a hydrophobic monolayer containing photochromic spiropyran molecules. Under visible irradiation the spiropyran is in a closed, hydrophobic form, whereas UV irradiation converts the spiropyran to a polar, hydrophilic form, reducing the contact angle. The superhydrophobic nanowire surface both amplifies the light-induced contact angle change by a factor of 2 relative to a smooth surface and reduces the contact angle hysteresis. As a result the UV-induced advancing contact angle is lower than the receding contact angle under visible irradiation, allowing water drops to be moved solely under the influence of a UV−visible light gradient. The amplification of the reversible light-induced wetting angle change was predicted using the Wenzel model for fractally rough surfaces. The model and amplification effects are expected to apply to other types of stimuli-induced contact angle changes such as that by heat or electrical potentials.
Age-related maculopathy (ARM), or age-related macular degeneration, is one of the most common causes of visual impairment in the elderly population of developed nations. In a combined analysis of two ...previous genomewide scans that included 391 families, containing up to 452 affected sib pairs, we found linkage evidence in four regions: 1q31, 9p13, 10q26, and 17q25. We now have added a third set of families and have performed an integrated analysis incorporating 530 families and up to 736 affected sib pairs. Under three diagnostic models, we have conducted linkage analyses using parametric (heterogeneity LOD HLOD scores under an autosomal dominant model) and nonparametric (
S
all statistic) methods. There is ongoing evidence of susceptibility loci within the 1q31, 10q26, and 17q25 regions. If we treat the third set of families as a replication set, then two regions (10q26 and 17q25) are replicated, with LOD scores >1.0. If we pool all our data together, then four regions (1q31, 2q14.3, 10q26, and 17q25) show HLOD or
S
all scores ⩾2.0. Within the 1q31 region, we observed an HLOD of 2.72 (genomewide
P=.061) under our least stringent diagnostic model, whereas the 17q25 region contained a maximal HLOD of 3.53 (genomewide
P=.007) under our intermediate diagnostic model. We have evaluated our results with respect to the findings from several new independent genomewide linkage studies and also have completed ordered subset analyses (OSAs) with apolipoprotein E alleles, smoking history, and age at onset as stratifying covariates. The OSAs generate the interesting hypothesis that the effect of smoking on the risk of ARM is accentuated by a gene in the 10q26 region—a region implicated by four other studies.
A cascaded parametric amplifier consists of a first parametric amplifier, which amplifies an input signal and generates an idler, which is a copy of the signal, a signal processor, which controls the ...phases of the signal and idler, and a second parametric amplifier, which combines the signal and idler in a phase-sensitive manner. In this paper, cascaded parametric amplification is modeled and the conditions required to maximize the constructive-destructive extinction ratio are determined. The results show that a cascaded parametric amplifier can be operated as a filter: A desired signal-idler pair is amplified, whereas undesired signal-idler pairs are deamplified. For the desired signal and idler, the noise figures of the filtering process (input signal-to-noise ratio divided by the output ratios) are only slightly higher than those of the copying process: Signal-processing functionality can be achieved with only a minor degradation in signal quality.
The sympathetic (SNS) and parasympathetic (PNS) branches of the autonomic nervous system have been implicated in the modulation of the renewal of many tissues, including the intestinal epithelium. ...However, it is not known whether these mechanisms are direct, requiring an interaction between autonomic neurotransmitters and receptors on proliferating epithelial cells. To evaluate the existence of a molecular framework for a direct effect of the SNS or PNS on intestinal epithelial renewal, we measured gene expression for the main autonomic neurotransmitter receptors in this tissue. We separately evaluated intestinal epithelial regions comprised of the stem, progenitor, and mature cells, which allowed us to investigate the distinct contributions of each cell population to this proposed autonomic effect. Notably, we found that the stem cells expressed the receptors for the SNS‐associated alpha2A adrenoreceptor and the PNS‐associated muscarinic acetylcholine receptors (M1 and M3). In a separate experiment, we found that the application of norepinephrine or acetylcholine decreases the expression of cyclin D1, a gene necessary for cell cycle progression, in intestinal epithelial organoids compared with controls (P < 0.05). Together, these results provide evidence of a direct mechanism for the autonomic nervous system influence on intestinal epithelial stem cell proliferation.
Intestinal epithelial stem cells express sympathetic and parasympathetic neurotransmitter receptors and norepinephrine or acetylcholine decreases the expression of cyclin D, a gene involved in controlling the cell cycle and proliferation. These data suggest that autonomic nervous system may be involved in the direct control intestinal epithelial stem cell proliferation and tissue renewal, a process necessary to maintain tissue homeostasis.
Neural and hormonal control of food hoarding Bartness, Timothy J; Keen-Rhinehart, E; Dailey, M J ...
American journal of physiology. Regulatory, integrative and comparative physiology,
09/2011, Letnik:
301, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Many animals hoard food, including humans, but despite its pervasiveness, little is known about the physiological mechanisms underlying this appetitive behavior. We summarize studies of food hoarding ...in humans and rodents with an emphasis on mechanistic laboratory studies of species where this behavior importantly impacts their energy balance (hamsters), but include laboratory rat studies although their wild counterparts do not hoard food. The photoperiod and cold can affect food hoarding, but food availability is the most significant environmental factor affecting food hoarding. Food-deprived/restricted hamsters and humans exhibit large increases in food hoarding compared with their fed counterparts, both doing so without overeating. Some of the peripheral and central peptides involved in food intake also affect food hoarding, although many have not been tested. Ad libitum-fed hamsters given systemic injections of ghrelin, the peripheral orexigenic hormone that increases with fasting, mimics food deprivation-induced increases in food hoarding. Neuropeptide Y or agouti-related protein, brain peptides stimulated by ghrelin, given centrally to ad libitum-fed hamsters, duplicates the early and prolonged postfood deprivation increases in food hoarding, whereas central melanocortin receptor agonism tends to inhibit food deprivation and ghrelin stimulation of hoarding. Central or peripheral leptin injection or peripheral cholecystokinin-33, known satiety peptides, inhibit food hoarding. Food hoarding markedly increases with pregnancy and lactation. Because fasted and/or obese humans hoard more food in general, and more high-density/high-fat foods specifically, than nonfasted and/or nonobese humans, understanding the mechanisms underlying food hoarding could provide another target for behavioral/pharmacological approaches to curb obesity.
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