4,595 research outputs found
Assessing reliance on vector navigation in the long-distance oceanic migrations of green sea turtles
Vector navigation, i.e., maintaining a constant heading for a given amount of time, is hypothesized to provide a viable basis for the
navigational feats of a number of long-distance animal migrants. Since animals following this strategy are subject to drift by wind or
by ocean current, performing long migrations relying on vector navigation is particularly challenging. We tested whether vector navigation
could be involved in the migrations of green turtles (Chelonia mydas) that migrate between the remote Ascension Island and
Brazil. To this aim, a novel approach was followed using individual-based numerical models to simulate migratory trajectories of virtual
turtles that were compared to actual routes reconstructed by satellite. Simulated postnesting migrations from Ascension revealed
that weak currents enabled modeled turtles to reach the Brazilian coast, but only for a limited range of headings around due West.
This conclusion was corroborated by comparing modeled trajectories with the actual routes of previously tracked turtles, with a beeline
vector navigation strategy providing the best fit, although a true-navigation strategy directed to the landfall site produced similar
results. Finally, we tested if a vector navigational strategy was feasible for the prebreeding migration from Brazil towards Ascension,
but modeled routes mostly failed to reach the island or a larger area around it, with individuals drifting away under the influence of
currents. We conclude that Ascension turtles can take advantage of vector navigation when migrating towards a wide target like the
Brazilian coast, while the demanding prebreeding migration likely requires more complex navigational systems
Subtrochanteric fractures after long-term treatment with bisphosphonates: a European Society on Clinical and Economic Aspects of Osteoporosis and Osteoarthritis, and International Osteoporosis Foundation Working Group Report
Summary: This paper reviews the evidence for an association between atypical subtrochanteric fractures and long-term bisphosphonate use. Clinical case reports/reviews and case-control studies report this association, but retrospective phase III trial analyses show no increased risk. Bisphosphonate use may be associated with atypical subtrochanteric fractures, but the case is yet unproven. Introduction: A Working Group of the European Society on Clinical and Economic Aspects of Osteoporosis and Osteoarthritis and the International Osteoporosis Foundation has reviewed the evidence for a causal association between subtrochanteric fractures and long-term treatment with bisphosphonates, with the aim of identifying areas for further research and providing recommendations for physicians. Methods: A PubMed search of literature from 1994 to May 2010 was performed using key search terms, and articles pertinent to subtrochanteric fractures following bisphosphonate use were analysed. Results: Several clinical case reports and case reviews report a possible association between atypical fractures at the subtrochanteric region of the femur in bisphosphonate-treated patients. Common features of these âatypical' fractures include prodromal pain, occurrence with minimal/no trauma, a thickened diaphyseal cortex and transverse fracture pattern. Some small case-control studies report the same association, but a large register-based study and retrospective analyses of phase III trials of bisphosphonates do not show an increased risk of subtrochanteric fractures with bisphosphonate use. The number of atypical subtrochanteric fractures in association with bisphosphonates is an estimated one per 1,000 per year. It is recommended that physicians remain vigilant in assessing their patients treated with bisphosphonates for the treatment or prevention of osteoporosis and advise patients of the potential risks. Conclusions: Bisphosphonate use may be associated with atypical subtrochanteric fractures, but the case is unproven and requires further research. Were the case to be proven, the risk-benefit ratio still remains favourable for use of bisphosphonates to prevent fracture
Hip fracture, mortality risk, and cause of death over two decades
Summary: Men and women with hip fracture have higher short-term mortality. This study investigated mortality risk over two decades post-fracture; excess mortality remained high in women up to 10 years and in men up to 20 years. Cardiovascular disease (CVD) and pneumonia were leading causes of death with a long-term doubling of risk. Introduction: Hip fractures are associated with increased mortality, particularly short term. In this study with a two-decade follow-up, we examined mortality and cause of death compared to the background population. Methods: We followed 1013 hip fracture patients and 2026 matched community controls for 22 years. Mortality, excess mortality, and cause of death were analyzed and stratified for age and sex. Hazard ratio (HR) was estimated by Cox regression. A competing risk model was fitted to estimate HR for common causes of death (CVD, cancer, pneumonia) in the short and long term (>1 year). Results: For both sexes and at all ages, mortality was higher in hip fracture patients across the observation period with men losing most life years (p <0.001). Mortality risk was higher for up to 15 years (women (risk ratio (RR) 1.9 [95 % confidence interval (CI) 1.7â2.1]); men (RR 2.8 [2.2â3.5])) and until end of follow-up ((RR 1.8 [1.6â2.0]); (RR 2.7 [2.1â3.3])). Excess mortality by time intervals, censored for the first year, was evident in women (80 years, for 5 years) and in me
Correction to: The intake of flavonoids, stilbenes, and tyrosols, mainly consumed through red wine and virgin olive oil, is associated with lower carotid and femoral subclinical atherosclerosis and coronary calcium
The original version of this article unfortunately contained a mistake. The authorâs name Henry Montero-Salazar was incorrectly written as Henry Montero Salazar. © The Author(s) 2022
Probing the Rho Spectral Function in Hot and Dense Nuclear Matter by Dileptons
We present a dynamical study of and production in
proton-nucleus and nucleus-nucleus collisions at CERN-SPS energies on the basis
of the covariant transport approach HSD employing a momentum-dependent
-meson spectral function that includes the pion modifications in the
nuclear medium as well as the polarization of the -meson due to resonant
scattering. We find that the experimental data from the CERES and
HELIOS-3 Collaborations can be described equally well as within the dropping
-mass scenario. Whereas corresponding dilepton -spectra are found to
be very similar, the inclusive dilepton yield in the invariant mass range GeV should allow to disentangle the two scenarios
experimentally.Comment: 13 pages RevTeX slightly revised, 6 eps-figure
Anthropogenic and climatic impacts on a coastal environment in the Baltic Sea over the last 1000 years
Coastal environments have experienced large ecological changes as a result of human activities over the last 100-200 years. To understand the severity and potential consequences of such changes, paleoenvironmental records provide important contextual information. The Baltic Sea coastal zone is naturally a vulnerable system and subject to significant human-induced impacts. To put the recent environmental degradation in the Baltic coastal zone into a long-term perspective, and to assess the natural and anthropogenic drivers of environmental change, we present sedimentary records covering the last 1000 years obtained from a coastal inlet (Gasfjarden) and a nearby lake (Lake Storsjon) in Sweden. We investigate the links between a pollen-based land cover reconstruction from Lake Storsjon and paleoenvironmental variables from Gasfjarden itself, including diatom assemblages, organic carbon (C) and nitrogen (N) contents, stable C and N isotopic ratios, and biogenic silica contents. The Lake Storsjon record shows that regional land use was characterized by small-scale agricultural activity between 900 and 1400 CE, which slightly intensified between 1400 and 1800 CE. Substantial expansion of cropland was observed between 1800 and 1950 CE, before afforestation between 1950 and 2010 CE. From the Gasfjarden record, prior to 1800 CE, relatively minor changes in the diatom and geochemical proxies were found. The onset of cultural eutrophication in Gasfjarden can be traced to the 1800s and intensified land use is identified as the main driver. Anthropogenic activities in the 20th century have caused unprecedented ecosystem changes in the coastal inlet, as reflected in the diatom composition and geochemical proxies. (c) 2018 Elsevier Ltd. All rights reserved.Peer reviewe
The influence of wind direction on the capture of the wood warbler (Phylloscopus sibilatrix), an uncommon migratory species in the western Mediterranean
The wood warbler (Phylloscopus sibilatrix) is a migratory species in the western Mediterranean wintering in the Gulf of Guinea region, West Africa. In autumn and spring, this species, along with the populations breeding in Ireland and Britain, uses the Italian peninsula as its main axis of migration. From the data of captured birds at several ringing stations in the western Mediterranean (Balearic Islands and coastal Iberian Peninsula), we analyzed capture rates of the species during spring migration from 1993 to 2007. Based on the selection of days with a significant number of captures and those without captures, we analyzed the effect of wind direction over the western Mediterranean to determine a relationship between winds and the number of captures. From a total of 663 wood warblers captured between 1993 and 2007, a total of 31 days have been selected as significant days with a high number of captures, and 31 days have been selected as no-capture days. On days of maximum captures, winds coming from an easterly direction, i.e. Algeria and Tunisia, were dominant, indicating days with a clear eastern component. Contrary to expected results, captures were also made on days when the wind direction was predominantly from a northerly direction. Analysis of the origin of the winds in north eastern Spain (western Mediterranean) revealed that the majority of northerly winds originated from Africa and not from Europe as is usual for this region. Days or periods selected as no-capture days were characterized by winds coming from a northerly (European origin) or westerly direction
Double Pomeron Jet Cross Sections
We treat hadron-hadron collisions where the final state is kinematically of
the kind associated with double-pomeron-exchange (DPE) and has large transverse
momentum jets. We show that in addition to the conventional factorized (FDPE)
contribution, there is a non-factorized (NDPE) contribution which has no
pomeron beam jet. Within a simple model we compute DPE-two-jet total and
differential cross sections at Tevatron energy scales, and show that the NDPE
contribution is dominant.Comment: 21 pages, 7 figures, figure 1 has been slightly change
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