10,881 research outputs found

    Application of Suction-cup-attached VHF Transmitters to the Study of Beluga, Delphinapterus leucas, Surfacing Behavior in Cook Inlet, Alaska

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    Suction-cup-attached VHF radio transmittes were deployed on belugas, Delphinapterus leucas, in Cook Inlet, Alaska, in 1994 and 1995 to characterize the whales' surfacing behavior. Data from video recordings were also used to characterize behavior of undisturbed whales and whales actively pursued for tagging. Statistics for dive intervals (time between the midpoints of contiguous surfacings) and surfacing intevals (time at the surface per surfacing) were estimated. Operations took place on the tidal delta of the Susitna and Little Susitna Rivers. During the 2-yr study, eight whales were successfully tagged, five tags remained attached for >60 min, and data from these were used in the analyses. Mean dive interval was 24.1 sec (interwhale SD=6.4 sec, n=5). The mean surfacing interval, as determined from the duration of signals received from the radio transmitters, was 1.8 sec (SD=0.3 sec, n=125) for one of the whales. Videotaped behaviors were categorized as "head-lifts" or "slow-rolls." Belugas were more likely to head-lift than to slow-roll during vessel approaches and tagging attempts when compared to undisturbed whales. In undisturbed groups, surfacing intervals determined from video records were significantly different between head-lifting (average = 1.02 sect, SD=0.38 sed, n=28) and slow-rolling whales (average = 2.45 sec, SD=0.37 sec, n=106). Undisturbed juveniles exhibited shorter slow-roll surfacing intervals (average = 2.25 sec, SD=0.32 sec, n=36) than adults (average = 2.55 sec, SD=0.36 sec, n=70). We did not observe strong reactions by the belugas to the suction-cup tags. This tagging method shows promise for obtaining surfacing data for durations of several days

    A Bayesian parameter estimation approach to pulsar time-of-arrival analysis

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    The increasing sensitivities of pulsar timing arrays to ultra-low frequency (nHz) gravitational waves promises to achieve direct gravitational wave detection within the next 5-10 years. While there are many parallel efforts being made in the improvement of telescope sensitivity, the detection of stable millisecond pulsars and the improvement of the timing software, there are reasons to believe that the methods used to accurately determine the time-of-arrival (TOA) of pulses from radio pulsars can be improved upon. More specifically, the determination of the uncertainties on these TOAs, which strongly affect the ability to detect GWs through pulsar timing, may be unreliable. We propose two Bayesian methods for the generation of pulsar TOAs starting from pulsar "search-mode" data and pre-folded data. These methods are applied to simulated toy-model examples and in this initial work we focus on the issue of uncertainties in the folding period. The final results of our analysis are expressed in the form of posterior probability distributions on the signal parameters (including the TOA) from a single observation.Comment: 16 pages, 4 figure

    The spectrum of HM Sagittae: A planetary nebula excited by a Wolf-Rayet star

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    A total of image tube spectrograms of HM Sagittae were obtained. More than 70 emission lines, including several broad emission features, were identified. An analysis of the spectra indicates that HM Sagittae is a planetary nebula excited by a Wolf-Rayet star. The most conspicuous Wolf-Rayet feature is that attributed to a blend of C III at 4650 A and He II at 4686 A

    Community experiences of organised crime in Scotland

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    The research explored community experiences of serious organised crime in Scotland (SOC). The report provides information on the nature and extent of the impact of SOC on everyday life in the community, as well as offering suggestions for policy development. The study sought to answer the following questions: 1)What are the relationships that exist between SOC and communities in Scotland? 2)What are the experiences and perceptions of residents, stakeholders and organisations of the scope and nature of SOC within their local area? and 3)How does SOC impact on community wellbeing, and to what extent can the harms associated with SOC be mitigated

    Towards Einstein-Podolsky-Rosen quantum channel multiplexing

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    A single broadband squeezed field constitutes a quantum communication resource that is sufficient for the realization of a large number N of quantum channels based on distributed Einstein-Podolsky-Rosen (EPR) entangled states. Each channel can serve as a resource for, e.g. independent quantum key distribution or teleportation protocols. N-fold channel multiplexing can be realized by accessing 2N squeezed modes at different Fourier frequencies. We report on the experimental implementation of the N=1 case through the interference of two squeezed states, extracted from a single broadband squeezed field, and demonstrate all techniques required for multiplexing (N>1). Quantum channel frequency multiplexing can be used to optimize the exploitation of a broadband squeezed field in a quantum information task. For instance, it is useful if the bandwidth of the squeezed field is larger than the bandwidth of the homodyne detectors. This is currently a typical situation in many experiments with squeezed and two-mode squeezed entangled light.Comment: 4 pages, 4 figures. In the new version we cite recent experimental work bei Mehmet et al., arxiv0909.5386, in order to clarify the motivation of our work and its possible applicatio

    Shotguns vs Lasers: Identifying barriers and facilitators to scaling-up plant molecular farming for high-value health products.

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    Plant molecular farming (PMF) is a convenient and cost-effective way to produce high-value recombinant proteins that can be used in the production of a range of health products, from pharmaceutical therapeutics to cosmetic products. New plant breeding techniques (NPBTs) provide a means to enhance PMF systems more quickly and with greater precision than ever before. However, the feasibility, regulatory standing and social acceptability of both PMF and NPBTs are in question. This paper explores the perceptions of key stakeholders on two European Union (EU) Horizon 2020 programmes-Pharma-Factory and Newcotiana-towards the barriers and facilitators of PMF and NPBTs in Europe. One-on-one qualitative interviews were undertaken with N = 20 individuals involved in one or both of the two projects at 16 institutions in seven countries (Belgium, France, Germany, Italy, Israel, Spain and the UK). The findings indicate that the current EU regulatory environment and the perception of the public towards biotechnology are seen as the main barriers to scaling-up PMF and NPBTs. Competition from existing systems and the lack of plant-specific regulations likewise present challenges for PMF developing beyond its current niche. However, respondents felt that the communication of the benefits and purpose of NPBT PMF could provide a platform for improving the social acceptance of genetic modification. The importance of the media in this process was highlighted. This article also uses the multi-level perspective to explore the ways in which NPBTs are being legitimated by interested parties and the systemic factors that have shaped and are continuing to shape the development of PMF in Europe

    The X-ray emission of Lyman break galaxies

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    We present an analysis of the X-ray emission of a large sample of z∼3 Lyman break galaxies (LBGs), based on Chandra/ACIS observations of several LBG survey fields. A total of 24 LBGs are directly detected in the X-ray, approximately doubling the number of known detections. Thirteen of the LBGs have optical spectroscopic signatures of active galactic nucleus (AGN) activity, but almost all the other X-ray detections are also likely to host an accreting black hole based on their X-ray properties. The AGN exhibit a wide range in X-ray luminosity, from weak Seyferts to bright quasi-stellar objects (QSOs). An optical spectroscopy identified approximately one-third of the X-ray-detected sources as broad-line QSOs, one-third as narrow-line AGN (NLAGN) and one-third as normal star-forming LBGs. The fraction of X-ray-detected LBGs is 3 per cent, much lower than that which has been found for submillimetre-selected galaxies. Two galaxies have X-ray luminosities, spectra and fX/fopt values that are consistent with emission from star formation processes and are identified as candidate X-ray bright, pure starburst galaxies at z∼ 3. If powered solely by star formation, the sources would have star formation rates (SFRs) of 300–500 M⊙ yr−1. X-ray spectral analysis of the LBGs shows a mean photon index of Γ= 1.96 , similar to local AGN. There is evidence for absorption in at least 40 per cent of the objects. Significantly more absorption is evident in the NLAGN, which is consistent with AGN unification schemes. After correction for absorption, the narrow- and broad-line objects show the same average luminosity. X-ray-detected LBGs, spectroscopically classified as normal galaxies, however, are less luminous in both soft and hard X-ray bands, indicating that the host galaxy is outshining any optical AGN signature. Turning to the X-ray emission from LBGs without direct detections, stacking the X-ray flux in the two deepest Chandra fields under consideration [the Hubble Deep Field-North (HDF-N) and Groth–Westphal Strip (GWS)] produced significant detections in each, although the GWS result was marginal. The detection in the HDF-N gives an X-ray-derived SFR of 42.4 ± 7.8 M⊙ yr^−1 per LBG and, by comparing with the ultraviolet (UV) SFR, the implied UV extinction correction is 4.1 ± 0.8. The LBG sample was split into three bins based on UV magnitude to examine the correlation between UV and X-ray emission: for the limited statistics available, there was no evidence of any correlation

    Gender differences in the kinetics and kinematics of distance running: implications for footwear design

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    Interest in distance running amongst females has expanded rapidly. Although there are numerous health benefits associated with running, the occurrence of injury is well documented. Given the relative susceptibility of females to overuse running injuries, a key issue within the discipline of footwear biomechanics that has yet to be appropriately addressed is the specific demands of athletic footwear for females. The aim of this study was therefore to provide both a kinetic and 3-D kinematic comparison of male and female runners in order to determine the relative susceptibility of females to the proposed mechanisms of overuse injuries and whether based on this information, females require more specific footwear designs to meet their needs. Twelve male participants and twelve female participants completed five successful trials running at 4.0ms-1+5%. 3-D angular joint kinematics from the hip, knee and ankle were collected using an eight camera motion analysis system. In addition simultaneous tibial acceleration and ground reaction forces were obtained. Differences in impact parameters and joint kinematics were subsequently compared using independent samples t-tests. Females were found to be associated with significantly greater knee abduction, knee internal rotation and ankle eversion, whilst males were associated with significantly greater hip flexion. Based on these findings it is recommended that females select running footwear with design characteristics aimed towards the reduction of coronal plane ankle eversion in order to reduce the incidence of injury

    Investigations of offshore beach sands : Virginia Beach and Sandbridge, Virginia

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    The City of Virginia Beach is faced with an ongoing problem of erosion along its ocean beaches. The Resort Strip, the backbone of beach-going tourism in the Commonwealth, must be renourished annually. Steel bulkheads or seawalls have been constructed along most of the 7 km (4.5 mile) ocean shoreline of Sandbridge, a semi-private, ocean-side community. The City is looking for beach material to reestablish its sandy coast. Maintaining a protective and recreational beach is the_primary goal in both locales. Previous sources of sand for the Resort Strip have been upland borrow pits that either have closed or are located too far from the shore for economically feasible truck-haul. Most recent nourishment efforts have relied on a large dredge material stockpile at Lynnhaven Inlet. Although, this stockpile is adequate at present for beach nourishment, it must be transported by truck and its future as a sand resource is not certain. (more ....
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