Spacetime Embedding Diagrams for Black Holes

We show that the 1+1 dimensional reduction (i.e., the radial plane) of the Kruskal black hole can be embedded in 2+1 Minkowski spacetime and discuss how features of this spacetime can be seen from the embedding diagram. The purpose of this work is educational: The associated embedding diagrams may be useful for explaining aspects of black holes to students who are familiar with special relativity, but not general relativity.Comment: 22 pages, 21 figures, RevTex. To be submitted to the American Journal of Physics. Experts will wish only to skim appendix A and to look at the pictures. Suggested Maple code is now compatible with MapleV4r

The Effectiveness of a Personal Computer Aviation Training Device (PCATD), a Flight Training Device (FTD), and an Airplane in Conducting Instrument Proficiency Checks

This project evaluated the effectiveness of a personal computer aviation training device (PCATD), a flight training device (FTD) and an airplane for conducting an instrument proficiency check (IPC). The study compared the performance of pilots receiving an IPC in a PCATD, in a FTD and in an airplane (IPC #1) with performance on a later IPC in an airplane (IPC #2). Chi-square tests were used to analyze the IPC #1 and IPC #2 data to determine whether the treatment (assignment to group) had an effect on the pass/fail ratio for the IPC #1 and IPC #2 flights respectively. The treatment effect on the IPC #1 and IPC #2 pass/fail ratios were not statistically significant. A series of planned-comparison tests were performed both between the experimental groups and between subjects within each experimental group. The PCATD group was compared to the Airplane group and to the FTD group, the Airplane group to the FTD group. None of these comparisons showed statistically significant (a \u3c .05) differences between groups. These findings provide compelling evidence for permitting the use of PCATDs to give IPCs

THE EFFECTS OF AN ERGONOMIC DEVICE ON SAGITTAL PLANE LOWER EXTREMITY MOTION DURING A FULL SQUAT IN ACL-REPAIRED AND NON-INJURED FEMALES

Each year, 250,000 Americans experience injuries affecting the anterior cruciate ligament (ACL), with women four to six times more likely to incur an ACL injury than their male counterparts. Knee Savers® (KS) are an ergonomic aid purported to lessen the risk of such injuries linked to deep squats. While widely used, KS have not been tested to determine their effect upon lower extremity kinematics. Female participants (n=20) with a history of ACLrepair (n=10) or non-injury (n=10) completed a deep squat with and without KS, while being filmed with 2D videography using methods increasingly available in clinical environments. Results from the study indicate no significant differences were found in sagittal plane lower extremity kinematics when squatting with and without KS. KS did not appear to influence lower extremity joint positions during the bottom phase of a deep squat as purported

FRONTAL PLANE KNEE MOTION OF ACL-REPAIRED AND NON-INJURED FEMALES WHEN USING KNEE SAVERS

Women are four to six times more likely to sustain ACL injuries compared to male counterparts. Few investigations have explored if ergonomic devices may alleviate the stress placed on the ACL during deep squatting. The purpose of the study was to determine if Knee Savers® (KS) influenced the frontal plane knee motion when previously-injured and healthy participants completed a squat. Female participants (ACLrepaired: n=10; healthy: n=10) completed a deep squat with and without KS using 2-D videography methods. Results indicated a greater medial motion of the patella in the frontal plane in the right leg of non-injured participants when compared to the ACLrepaired group (p = 0.04). When squatting with KS, the non-injured group experienced more frontal plane motion at the knee, compared to the ACL-repaired group

A Method to have Multi-Layer Thermal Insulation Provide Damage Detection

Design and testing of a multi-layer thermal insulation system that also provides debris and micrometeorite damage detection is presented. One layer of the insulation is designed as an array of passive open-circuit electrically conductive spiral trace sensors. The sensors are a new class of sensors that are electrically open-circuits that have no electrical connections thereby eliminating one cause of failure to circuits. The sensors are powered using external oscillating magnetic fields. Once electrically active, they produce their own harmonic magnetic fields. The responding field frequency changes if any sensor is damaged. When the sensors are used together in close proximity, the inductive coupling between sensors provides a means of telemetry. The spiral trace design using reflective electrically conductive material provides sufficient area coverage for the sensor array to serves as a layer of thermal insulation. The other insulation layers are designed to allow the sensor s magnetic field to permeate the insulation layers while having total reflective surface area to reduce thermal energy transfer. Results of characterizing individual sensors and the sensor array s response to punctures are presented. Results of hypervelocity impact testing using projectiles of 1-3.6 millimeter diameter having speeds ranging from 6.7-7.1 kilometers per second are also presented

Moving forward in circles: challenges and opportunities in modelling population cycles

Population cycling is a widespread phenomenon, observed across a multitude of taxa in both laboratory and natural conditions. Historically, the theory associated with population cycles was tightly linked to pairwise consumer–resource interactions and studied via deterministic models, but current empirical and theoretical research reveals a much richer basis for ecological cycles. Stochasticity and seasonality can modulate or create cyclic behaviour in non-intuitive ways, the high-dimensionality in ecological systems can profoundly influence cycling, and so can demographic structure and eco-evolutionary dynamics. An inclusive theory for population cycles, ranging from ecosystem-level to demographic modelling, grounded in observational or experimental data, is therefore necessary to better understand observed cyclical patterns. In turn, by gaining better insight into the drivers of population cycles, we can begin to understand the causes of cycle gain and loss, how biodiversity interacts with population cycling, and how to effectively manage wildly fluctuating populations, all of which are growing domains of ecological research

Temporal and Spatial Blood Feeding Patterns of Urban Mosquitoes In the San Juan Metropolitan Area, Puerto Rico

Urban ecosystems are a patchwork of habitats that host a broad diversity of animal species. Insects comprise a large portion of urban biodiversity which includes many pest species, including those that transmit pathogens. Mosquitoes (Diptera: Culicidae) inhabit urban environments and rely on sympatric vertebrate species to complete their life cycles, and in this process transmit pathogens to animals and humans. Given that mosquitoes feed upon vertebrates, they can also act as efficient samplers that facilitate detection of vertebrate species that utilize urban ecosystems. In this study, we analyzed DNA extracted from mosquito blood meals collected temporally in multiple neighborhoods of the San Juan Metropolitan Area, Puerto Rico to evaluate the presence of vertebrate fauna. DNA was collected from 604 individual mosquitoes that represented two common urban species, Culex quinquefasciatus (n = 586) and Aedes aegypti (n = 18). Culex quinquefasciatus fed on 17 avian taxa (81.2% of blood meals), seven mammalian taxa (17.9%), and one reptilian taxon (0.85%). Domestic chickens dominated these blood meals both temporally and spatially, and no statistically significant shift from birds to mammals was detected. Aedes aegypti blood meals were from a less diverse group, with two avian taxa (11.1%) and three mammalian taxa (88.9%) identified. The blood meals we identified provided a snapshot of the vertebrate community in the San Juan Metropolitan Area and have potential implications for vector-borne pathogen transmission

Zingerone in the Flower of Passiflora maliformis Attracts an Australian Fruit Fly, Bactrocera jarvisi (Tryon)

Passiflora maliformis is an introduced plant in Australia but its flowers are known to attract the native Jarvis’s fruit fly, Bactrocera jarvisi (Tryon). The present study identifies and quantifies likely attractant(s) of male B. jarvisi in P. maliformis flowers. The chemical compositions of the inner and outer coronal filaments, anther, stigma, ovary, sepal, and petal of P. maliformis were separately extracted with ethanol and analyzed using gas chromatography-mass spectrometry (GC-MS). Polyisoprenoid lipid precursors, fatty acids and their derivatives, and phenylpropanoids were detected in P. maliformis flowers. Phenylpropanoids included raspberry ketone, cuelure, zingerone, and zingerol, although compositions varied markedly amongst the flower parts. P. maliformis flowers were open for less than one day, and the amounts of some of the compounds decreased throughout the day. The attraction of male B. jarvisi to P. maliformis flowers is most readily explained by the presence of zingerone in these flowers

Impact of Disease on the Survival of Three Commercially Fished Species

Recent increases in emergent infectious diseases have raised concerns about the sustainability of some marine species. The complexity and expense of studying diseases in marine systems often dictate that conservation and management decisions are made without quantitative data on population-level impacts of disease. Mark-recapture is a powerful, underutilized, tool for calculating impacts of disease on population size and structure, even in the absence of etiological information. We applied logistic regression models to mark-recapture data to obtain estimates of disease-associated mortality rates in three commercially important marine species: snow crab (Chionoecetes opilio) in Newfoundland, Canada, that experience sporadic epizootics of bitter crab disease; striped bass (Morone saxatilis) in the Chesapeake Bay, USA, that experience chronic dermal and visceral mycobacteriosis; and American lobster (Homarus americanus) in the Southern New England stock, that experience chronic epizootic shell disease. All three diseases decreased survival of diseased hosts. Survival of diseased adult male crabs was 1% (0.003-0.022, 95% CI) that of uninfected crabs indicating nearly complete mortality of infected crabs in this life stage. Survival of moderately and severely diseased striped bass (which comprised 15% and 11% of the population, respectively) was 84% (70-100%, 95% CI), and 54% (42-68%, 95% CI) that of healthy striped bass. The disease-adjusted yearly natural mortality rate for striped bass was 0.29, nearly double the previously accepted value, which did not include disease. Survival of moderately and severely diseased lobsters was 30% (15-60%, 95% CI) that of healthy lobsters and survival of mildly diseased lobsters was 45% (27-75%, 95% CI) that of healthy lobsters. High disease mortality in ovigerous females may explain the poor recruitment and rapid declines observed in this population. Stock assessments should account for disease-related mortality when resource management options are evaluated. © 2017 by the Ecological Society of America