A trajectory planning scheme for spacecraft in the space station environment

Simulated annealing is used to solve a minimum fuel trajectory problem in the space station environment. The environment is special because the space station will define a multivehicle environment in space. The optimization surface is a complex nonlinear function of the initial conditions of the chase and target crafts. Small permutations in the input conditions can result in abrupt changes to the optimization surface. Since no prior knowledge about the number or location of local minima on the surface is available, the optimization must be capable of functioning on a multimodal surface. It was reported in the literature that the simulated annealing algorithm is more effective on such surfaces than descent techniques using random starting points. The simulated annealing optimization was found to be capable of identifying a minimum fuel, two-burn trajectory subject to four constraints which are integrated into the optimization using a barrier method. The computations required to solve the optimization are fast enough that missions could be planned on board the space station. Potential applications for on board planning of missions are numerous. Future research topics may include optimal planning of multi-waypoint maneuvers using a knowledge base to guide the optimization, and a study aimed at developing robust annealing schedules for potential on board missions

Strength in numbers: Avian influenza A virus transmission to poultry from a flocking passerine

The effects of flock size of European starlings (Sturnus vulgaris) was experimentally manipulated to assess the potential of influenza A virus (IAV; H4N6) transmission from a flocking passerine to bobwhite quail (Colinus virginianus) through shared food and water resources to mimic starling intrusions into free-range and backyard poultry operations. Of the three starling flock sizes tested (n = 30, n = 20 and n = 10), all successfully transmitted the virus to all or most of the quail in each animal room (6/6, 6/6 and 5/6) by the end of the experimental period, as determined by seroconversion and/or viral RNAshedding. Although starlings have been shown to be inconsistent shedders of IAVs andwhen they do replicate and subsequently shed virus they typically do so at low to moderate levels, this study has provided evidence that relatively small flocks (i.e., 10 or possibly a smaller number) of this species can collectively transmit the virus to a highly susceptible gallinaceous bird species. Future work should assess if starlings can transmit IAVs to additional poultry species commonly found in backyard or free-range settings

Effects of freshwater crayfish on influenza A virus persistence in water

Several investigations have recently assessed the ability of some aquatic invertebrates to act as tools for avian influenza A virus (IAV) surveillance as well as their potential role(s) in IAV ecology. Because of this, as well as the high IAV seroprevalence rates noted in select mesocarnivores that commonly inhabit aquatic and semi-aquatic habitats, we evaluated the effects that freshwater crayfish have on IAV in water at three dose levels and monitored for the presence of IAV in crayfish tissues (gill and green gland) and haemolymph at multiple time points. At relatively high, medium 432 and low (approximately 10 , 10 and 10 EID50/ml, respectively) doses, mesocosms containing crayfish (Orconectes sp.) had less detectable IAV RNA present when final water samples were assayed (9 days post-contact [DPC]). In general, containers without crayfish present had nearly three-fold greater quantities of viral RNA at 9 DPC. A varying number of RNA positive samples were detected for the three crayfish sample types collected. Gill tissue produced the largest number of positive non-water samples (n = 26), with the highest quantities detected from crayfish sampled on 1 and 4 DPC (103.5 EID50 equivalent/ml). On a few occasions, gill (n = 8) and haemolymph samples (n = 1) produced higher quantities of viral RNA than their respective water samples or water samples collected 1–2 DPC earlier, but these differences were typically minor. Based upon water samples, statistical models indicated that the interaction of dose and crayfish exposure days explained most of the variation in these data. Future efforts should address if crayfish exposed to IAV-laden water have the capacity to successfully transmit IAVs to mammals and birds which frequently prey upon them

Effect of Feed Cost on the Economic Impact of PRRS

Economic impacts based on PRRS associated losses as reported in a previous study were modeled with varying grain prices. Sensitivity tables show that as grain (feed) prices rise, the economic impact of disease events increases. As corn prices rise from $2.25/bu up to$5.00/bu, there is a $92.6 million increase in the cost of PRRS to US pork producers. Every$0.50/bu increase in corn price costs the pork industry $18.52 million in PRRS associated losses. In the PRRS-affected farm, for every$0.50/bu increase, the cost per litter increases $0.886, the cost per nursery pig increases$0.072/hd and the cost per finisher pig increases $0.405/hd. With corn at$2.50 to $5.00/bu the national impact is estimated at$594.19 to $686.77 million annually, or$5.94 to $6.87/hd marketed in the US. As feed prices rise, the value of improved health care also rises. As costs rise, it is imperative to continue efforts on disease control and prevention

Abrupt vessel closure complicating coronary angioplasty: Clinical, angiographic and therapeutic profile

AbstractTo assess the clinical, angiographic and procedural correlates of outcome after abrupt vessel closure during coronary angioplasty, results were analyzed of 109 patients (8.3%) who had abrupt vessel closure during 1,319 consecutive coronary angioplasty procedures performed between July 1, 1988 and June 30, 1990. These 109 patients had a mean age of 59 ± 11 years; 63% were male, 57% had had a prior myocardial infarction and 61% had multivessel disease. Coronary angioplasty was performed in the settings of acute myocardial infarction (14%), recent myocardial infarction (36%), unstable angina (34%) and stable ischemia (29%).Abrupt vessel closure occurred at a median of 27 min (range 0 min to 5 days) from the first balloon inflation. By angiographic criteria, thrombus or coronary dissection was identified in 20% and 28% of cases, respectively; both thrombus and dissection were present in 7% of closures, and 45% were due to indeterminate mechanisms. Successful reversal of abrupt vessel closure, defined as restoration of normal Thrombolysis In Myocardial Infarction (TIMI) grade 3 flow without resultant Q wave myocardial infarction, emergency bypass surgery or death, was achieved in 47 patients (43%). By hierarchal analysis, the incidence of death, emergency coronary bypass surgery, Q wave and non-Q wave myocardial infarction was 8%, 20%, 9% and 11%, respectively.Univariate analysis using 23 clinical, morphologic and procedural variables demonstrated that successful outcome after abrupt closure was associated with prolonged balloon inflations (>120 s) (odds ratio = 6.87, p < 0.001), unstable angina (odds ratio = 2.37, p = 0.034) and placement of an intracoronary stent (odds ratio = 5.33, p = 0.062). By multivariate analysis, independent correlates of successful outcome were prolonged balloon inflations (odds ratio = 5.11, p = 0.001) and intracoronary stenting (odds ratio = 4.37, p = 0.049).Thus, although prolonged balloon inflations and intracoronary stents may improve outcome after abrupt vessel closure, the cumulative risk of morbidity or mortality remains significant and mandates investigation into improved strategies for its prevention and treatment

Low viral doses are sufficient to infect cottontail rabbits with avian influenza A virus

Influenza A viruses (IAVs) have been reported in wild lagomorphs in environments where they share resources with waterfowl. Recent studies have conclusively shown that a North American lagomorph, cottontail rabbits (Sylvilagus sp.), become infected following exposure to IAVs and can shed significant quantities of virus. However, the minimum infectious dose and the efficiency of various routes of infection have not been evaluated. Thirty-six cottontail rabbits were used in a dose response study assessing both the oral and nasal routes of infection. The nasal route of infection proved to be the most efficient, as all cottontail rabbits shed viral RNA following inoculation with doses as low as 102 EID50. The oral route of infection was less efficient, but still produced infection rates of ≥ 50% at relatively low doses (i.e., 103 and 104 EID50). These results suggest that cottontail rabbits are highly susceptible to IAVs at low exposure doses that have been routinely observed in environments contaminated by waterfowl. Furthermore, this study supports earlier observations that cottontail rabbits may pose a biosecurity risk to poultry operations, as a virus-contaminated water source or contaminated environment, even at low viral titers, could be sufficient to initiate viral replication in cottontail rabbits

The genome sequence and effector complement of the flax rust pathogen Melampsora lini

Rust fungi cause serious yield reductions on crops, including wheat, barley, soybean, coffee, and represent real threats to global food security. Of these fungi, the flax rust pathogen Melampsora lini has been developed most extensively over the past 80 years as a model to understand the molecular mechanisms that underpin pathogenesis. During infection, M. lini secretes virulence effectors to promote disease. The number of these effectors, their function and their degree of conservation across rust fungal species is unknown. To assess this, we sequenced and assembled de novo the genome of M. lini isolate CH5 into 21,130 scaffolds spanning 189 Mbp (scaffold N50 of 31 kbp). Global analysis of the DNA sequence revealed that repetitive elements, primarily retrotransposons, make up at least 45% of the genome. Using ab initio predictions, transcriptome data and homology searches, we identified 16,271 putative protein-coding genes. An analysis pipeline was then implemented to predict the effector complement of M. lini and compare it to that of the poplar rust, wheat stem rust and wheat stripe rust pathogens to identify conserved and species-specific effector candidates. Previous knowledge of four cloned M. lini avirulence effector proteins and two basidiomycete effectors was used to optimize parameters of the effector prediction pipeline. Markov clustering based on sequence similarity was performed to group effector candidates from all four rust pathogens. Clusters containing at least one member from M. lini were further analyzed and prioritized based on features including expression in isolated haustoria and infected leaf tissue and conservation across rust species. Herein, we describe 200 of 940 clusters that ranked highest on our priority list, representing 725 flax rust candidate effectors. Our findings on this important model rust species provide insight into how effectors of rust fungi are conserved across species and how they may act to promote infection on their hosts.This work was funded by a grant from the CSIRO Transformational Biology Capability Platform to Adnane Nemri. Claire Anderson was supported by an ARC Discovery Grant (DP120104044) awarded to David A. Jones and Peter N. Dodds

Inventory of wildlife use of mortality pits as feeding sites: implications of pathogen exposure

To better understand the use of mortality pits by wildlife and possible pathogen dissemination from the resulting wildlife contact in these areas, we used 8 camera traps on 4 mortality pits in Colorado from June to December 2014 to create a species inventory and establish use estimates for those species. We observed 43 species visiting (in or near) the mortality pits during 1,168 total camera trap days. Of these, 24 species directly interacted with the mortality pits or carcasses contained within them. The most common visitors to mortality pits were raccoons (Procyon lotor), coyotes (Canis latrans), domestic dogs (Canis lupus familiaris), mule deer (Odocoileus hemionus), bald eagles (Haliaeetus leucocephalus), blackbilled magpies (Pica hudsonia), corvid species (i.e., American crows [Corvus brachyrhynchos] or common ravens [Corvus corax]), great blue herons (Ardea herodias), house sparrows (Passer domesticus), and turkey vultures (Cathartes aura). Mammals were often solitary visitors to mortality pits, while birds often visited mortality pits in mixed flocks of 2 to 5 species, putting them at a higher risk of interspecific pathogen spread. Our findings indicate that many animals come into direct and indirect contact with interspecific and conspecific species at mortality pits

Functional Brain Hyperactivations Are Linked to an Electrophysiological Measure of Slow Interhemispheric Transfer Time after Pediatric Moderate/Severe Traumatic Brain Injury.

Increased task-related blood oxygen level dependent (BOLD) activation is commonly observed in functional magnetic resonance imaging (fMRI) studies of moderate/severe traumatic brain injury (msTBI), but the functional relevance of these hyperactivations and how they are linked to more direct measures of neuronal function remain largely unknown. Here, we investigated how working memory load (WML)-dependent BOLD activation was related to an electrophysiological measure of interhemispheric transfer time (IHTT) in a sample of 18 msTBI patients and 26 demographically matched controls from the UCLA RAPBI (Recovery after Pediatric Brain Injury) study. In the context of highly similar fMRI task performance, a subgroup of TBI patients with slow IHTT had greater BOLD activation with higher WML than both healthy control children and a subgroup of msTBI patients with normal IHTT. Slower IHTT treated as a continuous variable was also associated with BOLD hyperactivation in the full TBI sample and in controls. Higher WML-dependent BOLD activation was related to better performance on a clinical cognitive performance index, an association that was more pronounced within the patient group with slow IHTT. Our previous work has shown that a subgroup of children with slow IHTT after pediatric msTBI has increased risk for poor white matter organization, long-term neurodegeneration, and poor cognitive outcome. BOLD hyperactivations after msTBI may reflect neuronal compensatory processes supporting higher-order capacity demanding cognitive functions in the context of inefficient neuronal transfer of information. The link between BOLD hyperactivations and slow IHTT adds to the multi-modal validation of this electrophysiological measure as a promising biomarker

What Attracts Women to the IT Field? The First Process of Occupational Socialization

Socialization in an occupation differs in important ways from organizational socialization. Entering a defined occupation is apt to involve a lifelong commitment, yet it is one that individuals often drift into gradually. Entering occupations involves five different, but overlapping processes: attraction, access, adjustment, identification and commitment (Trice & Beyer, 1993). The first of these five processes refers to the specific features of the occupation that get individuals attention and attract them to the occupation. Such features include specific members of the occupation to whom newcomers get attracted such as successful heroes and mentors. It could also be the activities distinctive of the occupational culture or the kinds of extrinsic and intrinsic rewards that the occupation appears to offer. This research study focuses on the attraction process of occupational socialization to the information technology (Ahuja, 2002) field of female students in order to understand women’s experiences and initial perceptions of the IT occupation. This study gathers empirical evidence from current female students in IT-related majors based on a qualitative approach and the use of focus groups as the elicitation technique. The goal of our research study is to contribute to a better understanding of the initial process of occupational socialization of female students in IT majors. The findings of this study, we believe, can help in improving and customizing recruitment strategies for female students that would emphasize the most attractive features of the IT occupation as perceived by women. In this research in progress we present the findings of our study based on eight focus groups conducted with students of three IT related academic majors in two academic institutions in the United States