4,421 research outputs found

    Further studies using matched filter theory and stochastic simulation for gust loads prediction

    Get PDF
    This paper describes two analysis methods -- one deterministic, the other stochastic -- for computing maximized and time-correlated gust loads for aircraft with nonlinear control systems. The first method is based on matched filter theory; the second is based on stochastic simulation. The paper summarizes the methods, discusses the selection of gust intensity for each method and presents numerical results. A strong similarity between the results from the two methods is seen to exist for both linear and nonlinear configurations

    Inflation without Inflaton(s)

    Get PDF
    We propose a model for early universe cosmology without the need for fundamental scalar fields. Cosmic acceleration and phenomenologically viable reheating of the universe results from a series of energy transitions, where during each transition vacuum energy is converted to thermal radiation. We show that this `cascading universe' can lead to successful generation of adiabatic density fluctuations and an observable gravity wave spectrum in some cases, where in the simplest case it reproduces a spectrum similar to slow-roll models of inflation. We also find the model provides a reasonable reheating temperature after inflation ends. This type of model may also be relevant for addressing the smallness of the vacuum energy today.Comment: 13 pages, 4 figures, published versio

    Efficacy of an Online Native Snake Identification Search Engine for Public Use

    Get PDF
    Visual methods of species identification are used both in research and recreational contexts because they are inexpensive, non-invasive, and believed to be effective among uniquely identifiable individuals. We examined the ability of the general public to identify live snakes (Serpentes) that are native to the United States using an online snake identification search engine (SISE) produced by the North America Brown Tree Snake Control Team (NABTSCT) website, http://www.nabtsct.net. The SISE consisted of participants answering 7 descriptive questions concerning a snake and then reviewing photographs of snakes that matched that description. Using 3 species of snakes native to Texas, USA, 21% of 395 participants were able to correctly identify all of the snakes using the online SISE, 54% correctly identified 2 snakes, 18% correctly identified 1 snake, and only 7% could not identify any snakes. Participants identified the distinctly marked checkered garter snake (Thamnophis marcianus) more readily (87% of participants) than the gopher snake (Pituophis catenifer) and Trans-Pecos rat snake (Bogertophis subocularis; 55% and 46% of participants, respectively). The probability of participants correctly identifying a snake using the online SISE increased substantially if ≥4 of the 7 descriptive questions were answered correctly. The age of participants and affinity toward snakes affected participant ability to correctly answer questions about snake morphology and identify snakes. In general, participants who displayed fear of snakes were less likely to correctly identify snake species than those who expressed a snake-neutral or enthusiast attitude. Additionally, younger participants performed better, on average, than older participants. Most participants (97%) claimed they would be able to use the online SISE to correctly identify other snakes in the future. We believe the public can use the online SISE to identify snakes, and hence, it can be an educational tool for the public to learn about an often neglected wildlife suborder

    WTC2005-63773 VAPOR PHASE LUBRICATION OF GOLD/GOLD INTERFACES

    Get PDF
    ABSTRACT The extension of current micro-satellite development efforts calls for a reduction in size by up to two orders of magnitude. Such a reduction in size necessitates the development of novel actuators, switches, and sensors operating on the micron length scale. The leading technology for creating such devices involves microfabrication processes currently used in the production of integrated circuits. Devices generated by these means are referred to as Micro-ElectroMechanical Systems (MEMS). While many challenges remain in the design and production of MEMS, a critical aspect of their successful deployment involves lubrication of the devices to prevent wear and permanent, undesired adhesion (seizure) of the miniature moving parts. Results from research addressing the vapor phase lubrication of gold-gold contacts, modeling interfaces expected to be encountered in future RF MEMS devices, will be presented. Such interfaces will require high frequency intermittent contact, the absence of irreversible interfacial adhesion, the general absence of sliding within the contact, and the requirement of electrical conductivity upon contact. Work in this area has focused on the use of alklythiols as a means of controlling interfacial adhesion. Experiments have been carried out using atomic force microscopy to characterize adhesion as a function of alkylthiol chain length. In addition, these experiments have incorporated the simultaneous measurement of interfacial currents to explore load versus conductivity relationships. These measurements have been supported through measurements of surface composition through correlated quartz crystal microbalance (QCM) and X-ray photoelectron spectroscopy (XPS) measurements. INTRODUCTION There have been a number of methods to lubricate MEMS devices proposed and tested and several review articles have been published describing these efforts

    WTC2005-63773 VAPOR PHASE LUBRICATION OF GOLD/GOLD INTERFACES

    Get PDF
    ABSTRACT The extension of current micro-satellite development efforts calls for a reduction in size by up to two orders of magnitude. Such a reduction in size necessitates the development of novel actuators, switches, and sensors operating on the micron length scale. The leading technology for creating such devices involves microfabrication processes currently used in the production of integrated circuits. Devices generated by these means are referred to as Micro-ElectroMechanical Systems (MEMS). While many challenges remain in the design and production of MEMS, a critical aspect of their successful deployment involves lubrication of the devices to prevent wear and permanent, undesired adhesion (seizure) of the miniature moving parts. Results from research addressing the vapor phase lubrication of gold-gold contacts, modeling interfaces expected to be encountered in future RF MEMS devices, will be presented. Such interfaces will require high frequency intermittent contact, the absence of irreversible interfacial adhesion, the general absence of sliding within the contact, and the requirement of electrical conductivity upon contact. Work in this area has focused on the use of alklythiols as a means of controlling interfacial adhesion. Experiments have been carried out using atomic force microscopy to characterize adhesion as a function of alkylthiol chain length. In addition, these experiments have incorporated the simultaneous measurement of interfacial currents to explore load versus conductivity relationships. These measurements have been supported through measurements of surface composition through correlated quartz crystal microbalance (QCM) and X-ray photoelectron spectroscopy (XPS) measurements. INTRODUCTION There have been a number of methods to lubricate MEMS devices proposed and tested and several review articles have been published describing these efforts

    Altered progesterone concentrations by hormonal manipulations before a fixed-time artificial insemination CO-Synch + CIDR program in suckled beef cows

    Get PDF
    We hypothesized that pregnancy outcomes may be improved by inducing luteal regression, ovulation, or both (i.e., altering progesterone status) before initiating a timed–artificial insemination (TAI) program in suckled beef cows. This hypothesis was tested in two experiments in which cows were treated with either PGF[subscript 2α] (PG) or PG + GnRH before initiating a TAI program to increase the proportion of cows starting the program in a theoretical marginal (<1 ng/mL; experiment 1) or elevated (≥1 ng/mL; experiment 2) progesterone environment, respectively. The control was a standard CO-Synch + controlled internal drug release (CIDR) program employed in suckled beef cows (100 μg GnRH intramuscularly [IM] [GnRH-1] and insertion of a progesterone-impregnated intravaginal CIDR insert on study Day −10, 25 mg PG and CIDR insert removal on study Day −3, and 100 μg GnRH IM [GnRH-2] and TAI on study Day 0). In both experiments, blood was collected before each injection for later progesterone analyses. In experiment 1, cows at nine locations (n = 1537) were assigned to either: (1) control or (2) PrePG (same as control with a PG injection on study Day −13). The PrePG cows had larger (P < 0.05) follicles on study Day −10 and more (P < 0.05) ovulated after GnRH-1 compared with control cows (60.6% vs. 36.5%), but pregnancy per TAI was not altered (55.5% vs. 52.2%, respectively). In experiment 2, cows (n = 803) at four locations were assigned to: (1) control or (2) PrePGG (same as control with PG injection on study Day −20 and GnRH injection on study Day −17). Although pregnancy per TAI did not differ between control and PrePGG cows (44.0% vs. 44.4%, respectively), cows with body condition score greater than 5.0 or 77 or more days postpartum at TAI were more (P < 0.05) likely to become pregnant than thinner cows or those with fewer days postpartum. Presynchronized cows in both experiments were more (P < 0.05) likely than controls to have luteolysis after initial PG injections and reduced (P < 0.05) serum progesterone; moreover, treatments altered the proportion of cows and pregnancy per TAI of cows in various progesterone categories before the onset of the TAI protocol. In combined data from both experiments, cows classified as anestrous before the study but with elevated progesterone on Day −10 had increased (P < 0.05) pregnancy outcomes compared with anestrous cows with low progesterone concentrations. Progesterone concentration had no effect on pregnancy outcome of cycling cows. In summary, luteal regression and ovulation were enhanced and progesterone concentrations were altered by presynchronization treatments before the 7-day CO-Synch + CIDR program, but pregnancy per TAI was not improved

    Alcohol dependence in a community sample of Aboriginal and Torres Strait Islander Australians : Harms, getting help and awareness of local treatments

    Get PDF
    Background Few studies have examined links between current alcohol dependence and specific harms among Indigenous Australians. We investigated these associations as well as help seeking for drinking, awareness of local treatments and recommendations to help family or friends cut down or stop drinking in two Indigenous communities. Methods A representative sample of Indigenous Australians was surveyed in one urban and one remote community in South Australia. Data were collected via the Grog Survey App. Participants were dependent if they reported two or more symptoms of alcohol dependence (ICD-11). Pearson chi-square tests were used to describe relationships between employment by gender, and dependence by awareness of medicines and local treatment options. Multivariate logistic regressions were used to predict the odds of dependent drinkers experiencing harms and getting help for drinking, controlling for age, gender, schooling and income. Results A total of 775 Indigenous Australians took part in the study. After controlling for confounders, dependent drinkers were nearly eight times more likely to report a harm and nearly three times more likely to get help for their drinking—compared with non-dependent drinkers. Participants recommended accessing local support from an Aboriginal alcohol and other drugs worker, or a detoxification/ rehabilitation service. Discussion and conclusions More support and funding is needed for Indigenous Australians to ensure local treatment options for dependent drinkers are readily available, appropriate and accessible. Involvement of local Aboriginal or Torres Strait Islander health professionals in delivery of care can help ensure that it is appropriate to an individual’s culture and context

    Consensus: a framework for evaluation of uncertain gene variants in laboratory test reporting

    Get PDF
    Accurate interpretation of gene testing is a key component in customizing patient therapy. Where confirming evidence for a gene variant is lacking, computational prediction may be employed. A standardized framework, however, does not yet exist for quantitative evaluation of disease association for uncertain or novel gene variants in an objective manner. Here, complementary predictors for missense gene variants were incorporated into a weighted Consensus framework that includes calculated reference intervals from known disease outcomes. Data visualization for clinical reporting is also discussed
    • …
    corecore