1,372 research outputs found
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Extensive use of mesopelagic waters by a Scalloped hammerhead shark (Sphyrna lewini) in the Red Sea
Background: Despite being frequently landed in fish markets along the Saudi Arabian Red Sea coast, information regarding fundamental biology of the Scalloped hammerhead shark (Sphyrna lewini) in this region is scarce. Satellite telemetry studies can generate important data on life history, describe critical habitats, and ultimately redefine management strategies for sharks. To better understand the horizontal and vertical habitat use of S. lewini in the Red Sea and to aid with potential future development of zoning and management plans for key habitats, we deployed a pop-up satellite archival transmitting tag to track a single female specimen (240 cm total length) for a tracking period of 182 days.
Results: The tag was physically recovered after a deployment period of 6 months, thus providing the complete archived dataset of more than one million depth and temperature records. Based on a reconstructed, most probable track, the shark travelled a circular distance of approximately 1000 km from the central Saudi Arabian Red Sea southeastward into Sudanese waters, returning to the tagging location toward the end of the tracking period. Mesopelagic excursions to depths between 650 and 971 m occurred on 174 of the 182 days of the tracking period. Intervals between such excursions were characterized by constant oscillatory diving in the upper 100 m of the water column.
Conclusions: This study provides evidence that mesopelagic habitats might be more commonly used by S. lewini than previously suggested. We identified deep diving behavior throughout the 24-h cycle over the entire 6-month tracking period. In addition to expected nightly vertical habitat use, the shark exhibited frequent mesopelagic excursions during daytime. Deep diving throughout the diel cycle has not been reported before and, while dive functionality remains unconfirmed, our study suggests that mesopelagic excursions may represent foraging events within and below deep scattering layers. Additional research aimed at resolving potential ecological, physiological and behavioral mechanisms underpinning vertical movement patterns of S. lewini will help to determine if the single individual reported here is representative of S. lewini populations in the Red Sea
The Herschel Exploitation of Local Galaxy Andromeda (HELGA) II: Dust and Gas in Andromeda
We present an analysis of the dust and gas in Andromeda, using Herschel
images sampling the entire far-infrared peak. We fit a modified-blackbody model
to ~4000 quasi-independent pixels with spatial resolution of ~140pc and find
that a variable dust-emissivity index (beta) is required to fit the data. We
find no significant long-wavelength excess above this model suggesting there is
no cold dust component. We show that the gas-to-dust ratio varies radially,
increasing from ~20 in the center to ~70 in the star-forming ring at 10kpc,
consistent with the metallicity gradient. In the 10kpc ring the average beta is
~1.9, in good agreement with values determined for the Milky Way (MW). However,
in contrast to the MW, we find significant radial variations in beta, which
increases from 1.9 at 10kpc to ~2.5 at a radius of 3.1kpc and then decreases to
1.7 in the center. The dust temperature is fairly constant in the 10kpc ring
(ranging from 17-20K), but increases strongly in the bulge to ~30K. Within
3.1kpc we find the dust temperature is highly correlated with the 3.6 micron
flux, suggesting the general stellar population in the bulge is the dominant
source of dust heating there. At larger radii, there is a weak correlation
between the star formation rate and dust temperature. We find no evidence for
'dark gas' in M31 in contrast to recent results for the MW. Finally, we
obtained an estimate of the CO X-factor by minimising the dispersion in the
gas-to-dust ratio, obtaining a value of (1.9+/-0.4)x10^20 cm^-2 [K kms^-1]^-1.Comment: 19 pages, 18 figures. Submitted to ApJ April 2012; Accepted July 201
Proposals for evaluating the regularity of a scientist'sresearch output
Evaluating the career of individual scientists according to their scientific output is a common bibliometric problem. Two aspects are classically taken into account: overall productivity and overall diffusion/impact, which can be measured by a plethora of indicators that consider publications and/or citations separately or synthesise these two quantities into a single number (e.g. h-index). A secondary aspect, which is sometimes mentioned in the rules of competitive examinations for research position/promotion, is time regularity of one researcher's scientific output. Despite the fact that it is sometimes invoked, a clear definition of regularity is still lacking. We define it as the ability of generating an active and stable research output over time, in terms of both publications/ quantity and citations/diffusion. The goal of this paper is introducing three analysis tools to perform qualitative/quantitative evaluations on the regularity of one scientist's output in a simple and organic way. These tools are respectively (1) the PY/CY diagram, (2) the publication/citation Ferrers diagram and (3) a simplified procedure for comparing the research output of several scientists according to their publication and citation temporal distributions (Borda's ranking). Description of these tools is supported by several examples
Flavor in Minimal Conformal Technicolor
We construct a complete, realistic, and natural UV completion of minimal
conformal technicolor that explains the origin of quark and lepton masses and
mixing angles. As in "bosonic technicolor", we embed conformal technicolor in a
supersymmetric theory, with supersymmetry broken at a high scale. The exchange
of heavy scalar doublets generates higher-dimension interactions between
technifermions and quarks and leptons that give rise to quark and lepton masses
at the TeV scale. Obtaining a sufficiently large top quark mass requires strong
dynamics at the supersymmetry breaking scale in both the top and technicolor
sectors. This is natural if the theory above the supersymmetry breaking also
has strong conformal dynamics. We present two models in which the strong top
dynamics is realized in different ways. In both models, constraints from
flavor-changing effects can be easily satisfied. The effective theory below the
supersymmetry breaking scale is minimal conformal technicolor with an
additional light technicolor gaugino. We argue that this light gaugino is a
general consequence of conformal technicolor embedded into a supersymmetric
theory. If the gaugino has mass below the TeV scale it will give rise to an
additional pseudo Nambu-Goldstone boson that is observable at the LHC.Comment: 37 pages; references adde
Cigarette smoking among school-going adolescents in Lithuania: Results from the 2005 Global Youth Tobacco Survey
<p>Abstract</p> <p>Background</p> <p>The majority of people who suffer morbidity due to smoking may have initiated smoking during adolescent period. The aim of this study is to determine the prevalence and associated factors for cigarette smoking among school-going adolescents in Lithuania.</p> <p>Findings</p> <p>Data from the Global Youth Tobacco Survey (GYTS) 2005 were used to conduct this study. Data were analyzed using SUDAAN software 9.03. Comparisons for categorical variables were done using the Pearson's Chi-square test. The cut of point for statistical significance was set at 5% level. Logistic regression analyses were conducted to determine factors associated with the outcome. Unadjusted odds ratios (OR) and adjusted odds ratios (AOR) together with their 95% confidence intervals (CI) are reported.</p> <p>Of the 1822 respondents, 35.8% males and 27.1% females reported being current cigarette smokers (p < 0.001). Having friends who smoke cigarettes was associated with smoking after controlling for age, gender, parental smoking status, and perception of risks of smoking (AOR = 3.76; 95% CI [2.33, 6.90] for some friends using tobacco; and AOR = 17.18; 95% CI [10.46, 28.21] for most or all friends using tobacco). Male gender and having one or both parents who smoke cigarettes were associated with smoking (AOR = 1.31; 95% CI [1.03, 1.66]) and AOR = 1.76; 95% CI [1.37, 2.27]) respectively).</p> <p>Conclusions</p> <p>There is a high prevalence of cigarette smoking among Lithuanian adolescents. Male adolescents and adolescents who have friends or parents who smoke should be the main target for tobacco control in Lithuania.</p
Minimal Conformal Technicolor and Precision Electroweak Tests
We study the minimal model of conformal technicolor, an SU(2) gauge theory
near a strongly coupled conformal fixed point, with conformal symmetry softly
broken by technifermion mass terms. Conformal symmetry breaking triggers chiral
symmetry breaking in the pattern SU(4) -> Sp(4), which gives rise to a
pseudo-Nambu-Goldstone boson that can act as a composite Higgs boson. The top
quark is elementary, and the top and electroweak gauge loop contributions to
the Higgs mass are cut off entirely by Higgs compositeness. In particular, the
model requires no top partners and no "little Higgs" mechanism. A nontrivial
vacuum alignment results from the interplay of the top loop and technifermion
mass terms. The composite Higgs mass is completely determined by the top loop,
in the sense that m_h/m_t is independent of the vacuum alignment and is
computable by a strong-coupling calculation. There is an additional composite
pseudoscalar A with mass larger than m_h and suppressed direct production at
LHC. We discuss the electroweak fit in this model in detail. Corrections to Z
-> bb and the T parameter from the top sector are suppressed by the enhanced
Sp(4) custodial symmetry. Even assuming that the strong contribution to the S
parameter is positive and usuppressed, a good electroweak fit can be obtained
for v/f ~ 0.25, where v and f are the electroweak and chiral symmetry breaking
scales respectively. This requires fine tuning at the 10% level.Comment: 34 pages, 4 figures; v2: updated precision electroweak fi
A standardisation framework for bio-logging data to advance ecological research and conservation
1. Bio-logging data obtained by tagging animals are key to addressing global conservation challenges. However, the many thousands of existing bio-logging datasets are not easily discoverable, universally comparable, nor readily accessible through existing repositories and across platforms, slowing down ecological research and effective management. A set of universal standards is needed to ensure discoverability, interoperability and effective translation of bio-logging data into research and management recommendations.
2. We propose a standardisation framework adhering to existing data principles (FAIR: Findable, Accessible, Interoperable and Reusable; and TRUST: Transparency,
Responsibility, User focus, Sustainability and Technology) and involving the use of simple templates to create a data flow from manufacturers and researchers to compliant repositories, where automated procedures should be in place to prepare data availability into four standardised levels: (a) decoded raw data, (b) curated data, (c) interpolated data and (d) gridded data. Our framework allows for integration of simple tabular arrays (e.g. csv files) and creation of sharable and interoperable network Common Data Form (netCDF) files containing all the needed information for accuracy-of-use, rightful attribution (ensuring data providers keep ownership through the entire process) and data preservation security.
3. We show the standardisation benefits for all stakeholders involved, and illustrate the application of our framework by focusing on marine animals and by providing examples of the workflow across all data levels, including filled templates and code to process data between levels, as well as templates to prepare netCDF files ready for sharing.
4. Adoption of our framework will facilitate collection of Essential Ocean Variables (EOVs) in support of the Global Ocean Observing System (GOOS) and intergovernmental assessments (e.g. the World Ocean Assessment), and will provide a starting point for broader efforts to establish interoperable bio-logging data formats across all fields in animal ecology
Routes for breaching and protecting genetic privacy
We are entering the era of ubiquitous genetic information for research,
clinical care, and personal curiosity. Sharing these datasets is vital for
rapid progress in understanding the genetic basis of human diseases. However,
one growing concern is the ability to protect the genetic privacy of the data
originators. Here, we technically map threats to genetic privacy and discuss
potential mitigation strategies for privacy-preserving dissemination of genetic
data.Comment: Draft for comment
Novice Learner Experiences in Software Development: A Study of Freshman Undergraduates
This paper presents a study that is part of a larger research project aimed at addressing the gap in the provision of educational software development processes for freshman, novice undergraduate learners, to improve proficiency levels. With the aim of understanding how such learners problem solve in software development in the absence of a formal process, this case study examines the experiences and depth of learning acquired by a sample set of novice undergraduates. A novel adaption of the Kirkpatrick framework known as AKM-SOLO is used to frame the evaluation. The study finds that without the scaffolding of an appropriate structured development process tailored to novices, students are in danger of failing to engage with the problem solving skills necessary for software development, particularly the skill of designing solutions prior to coding. It also finds that this lack of engagement directly impacts their affective state on the course and continues to negatively impact their proficiency and affective state in the second year of their studies leading to just under half of students surveyed being unsure if they wish to pursue a career in software development when they graduate
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A Search for MeV to TeV Neutrinos from Fast Radio Bursts with IceCube
We present two searches for IceCube neutrino events coincident with 28 fast radio bursts (FRBs) and 1 repeating FRB. The first improves on a previous IceCube analysis - searching for spatial and temporal correlation of events with FRBs at energies greater than roughly 50 GeV - by increasing the effective area by an order of magnitude. The second is a search for temporal correlation of MeV neutrino events with FRBs. No significant correlation is found in either search; therefore, we set upper limits on the time-integrated neutrino flux emitted by FRBs for a range of emission timescales less than one day. These are the first limits on FRB neutrino emission at the MeV scale, and the limits set at higher energies are an order-of-magnitude improvement over those set by any neutrino telescope
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