6,416 research outputs found
Integumentary remains and abdominal contents in the Early Cretaceous Chinese lizard, Yabeinosaurus (Squamata), demonstrate colour banding and a diet including crayfish
The Early Cretaceous lizard Yabeinosaurus is well-represented in the Jehol Biota of northeast China, with specimens yielding information on ontogenetic development, reproductive strategy, and diet, as well as skeletal morphology. However, a large, well-preserved, new specimen of Yabeinosaurus robustus from the Lamadong locality, Liaoning, provides further insights into the morphology and biology of this species. Integumentary traces demonstrate that, in life, Y. robustus was coloured with well-defined light and dark banding through both the body and the tail. The integumentary traces also confirm that Yabeinosaurus was covered with thin, non-overlapping osteoderms. Previous specimens have contained fish remains, suggesting that Yabeinosaurus foraged in, or close, to the water. The new specimen supports that hypothesis as it contains the remains of a large crayfish, identified as belonging to the species Palaeocambarus licenti Taylor et al. 1999. Body parts of the crayfish provide an estimated original total length of 120–140 mm
Reconstructing the Holocene glacial history of northern Troms and western Finnmark, Arctic Norway
\ua9 2024 The Author(s). Boreas published by John Wiley & Sons Ltd on behalf of The Boreas Collegium. Here we present the first Lateglacial and Holocene glacial history from Rotsunddalen, northern Troms and western Finnmark county, northern Norway, based on both relative and numerical moraine dating using Schmidt hammer, soil chronosequencing and terrestrial cosmogenic nuclide dating. We combine these chronological data with a regional map of the glacial geomorphology to hypothesize key events in the glacial history from around 14 ka to present. Our reconstruction shows that, following deglaciation of the main ice sheet across central Troms and Finnmark, mountain glaciers were terminating on land, close to the coast, between around 12.1 and 10.6 ka. Continued recession of the main Fennoscandian Ice Sheet margin towards the SE led to the isolation of several large plateau icefields and outlet glaciers that generated moraines at around 10.2–9.2 ka, which we ascribe to the Erdalen Event, and 8.4–8.2 ka, which is broadly contemporaneous with the 8.2 ka cold event. Although the latter corresponds with the Scandinavian Finse Event, very few moraines have been dated to this time and we therefore view it as a tentative hypothesis for future work to test. During the Holocene Thermal Maximum (~6.6 to 6.3 ka) most (if not all) glaciers in the region disappeared, but then regrew during the Neoglaciation and produced large moraines dated to around 4.7 ka that lie a few hundred metres distal to the prominent Little Ice Age moraines (previously dated to AD 1810s–1870s). Given the limitations of our dating approach, the preservation of moraines dated to this period in northern Norway also warrants further investigation. We also highlight that terrestrial cosmogenic nuclide dating of the moraines is not consistent with other dating approaches and the widely established deglaciation history of the region, probably owing to cosmogenic inheritance and insufficient glacial erosion
Occupational choice, number of entrepreneurs and output: theory and empirical evidence with Spanish data
This paper extends the (Lucas, Bell J Econ 9:508–523,1978) model of occupational choices by individuals with different skills, beyond the simple options of self-employment or wage-employment, by including a second choice for the self-employed. That is, an option to hire employees and so become self-employed with employees (SEWEs), or to be self-employed without employees (SEWNEs). We solve for the market equilibrium and examine the sensitivity of relative sizes of occupational groups, and of the level of productivity, to changes in the exogenous parameters. The results show that the positive (negative) association between number of SEWEs (SEWNEs) and productivity, observed in the Spanish data, can be explained, under certain conditions, as the result of cross-region and time differences in average skills. These findings point to the importance of distinguishing between SEWEs and SEWNEs in drawing valid conclusions concerning any link between entrepreneurship and economic development
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Suppression of erythropoiesis by dietary nitrate.
In mammals, hypoxia-triggered erythropoietin release increases red blood cell mass to meet tissue oxygen demands. Using male Wistar rats, we unmask a previously unrecognized regulatory pathway of erythropoiesis involving suppressor control by the NO metabolite and ubiquitous dietary component nitrate. We find that circulating hemoglobin levels are modulated by nitrate at concentrations achievable by dietary intervention under normoxic and hypoxic conditions; a moderate dose of nitrate administered via the drinking water (7 mg NaNO₃/kg body weight/d) lowered hemoglobin concentration and hematocrit after 6 d compared with nonsupplemented/NaCl-supplemented controls. The underlying mechanism is suppression of hepatic erythropoietin expression associated with the downregulation of tissue hypoxia markers, suggesting increased pO₂. At higher nitrate doses, however, a partial reversal of this effect occurred; this was accompanied by increased renal erythropoietin expression and stabilization of hypoxia-inducible factors, likely brought about by the relative anemia. Thus, hepatic and renal hypoxia-sensing pathways act in concert to modulate hemoglobin in response to nitrate, converging at an optimal minimal hemoglobin concentration appropriate to the environmental/physiologic situation. Suppression of hepatic erythropoietin expression by nitrate may thus act to decrease blood viscosity while matching oxygen supply to demand, whereas renal oxygen sensing could act as a brake, averting a potentially detrimental fall in hematocrit.This work was supported by British Heart Foundation Studentship FS/09/050 (to T.A.). A.J.M. thanks the Research Councils UK for supporting his academic fellowship and the WYNG Foundation of Hong Kong for support. J.L.G is supported by the European Union Framework 7 Inheritance project, R.S.J. is supported by a Wellcome Trust Principal research fellowship, and M.F. is supported by funds from the Faculty of Medicine, University of Southampton
Audition in vampire bats, Desmodus rotundus
1. Within the tonotopic organization of the inferior colliculus two frequency ranges are well represented: a frequency range within that of the echolocation signals from 50 to 100 kHz, and a frequency band below that of the echolocation sounds, from 10 to 35 kHz. The frequency range between these two bands, from about 40 to 50 kHz is distinctly underrepresented (Fig. 3B).
2. Units with BFs in the lower frequency range (10–25 kHz) were most sensitive with thresholds of -5 to -11 dB SPL, and units with BFs within the frequency range of the echolocation signals had minimal thresholds around 0 dB SPL (Fig. 1).
3. In the medial part of the rostral inferior colliculus units were encountered which preferentially or exclusively responded to noise stimuli. — Seven neurons were found which were only excited by human breathing noises and not by pure tones, frequency modulated signals or various noise bands. These neurons were considered as a subspeciality of the larger sample of noise-sensitive neurons. — The maximal auditory sensitivity in the frequency range below that of echolocation, and the conspicuous existence of noise and breathing-noise sensitive units in the inferior colliculus are discussed in context with the foraging behavior of vampire bats
Homogeneous Open Quantum Random Walks on a lattice
We study Open Quantum Random Walks for which the underlying graph is a
lattice, and the generators of the walk are translation-invariant. We consider
the quantum trajectory associated with the OQRW, which is described by a
position process and a state process. We obtain a central limit theorem and a
large deviation principle for the position process, and an ergodic result for
the state process. We study in detail the case of homogeneous OQRWs on a
lattice, with internal space
Combining behavioural activation with physical activity promotion for adults with depression: findings of a parallel-group pilot randomised controlled trial (BAcPAc)
BACKGROUND: Depression is associated with physical inactivity, which may mediate the relationship between depression and a range of chronic physical health conditions. However, few interventions have combined a psychological intervention for depression with behaviour change techniques, such as behavioural activation (BA), to promote increased physical activity. METHODS: To determine procedural and clinical uncertainties to inform a definitive randomised controlled trial (RCT), a pilot parallel-group RCT was undertaken within two Improving Access to Psychological Therapies (IAPT) services in South West England. We aimed to recruit 80 adults with depression and randomise them to a supported, written self-help programme based on either BA or BA plus physical activity promotion (BAcPAc). Data were collected at baseline and 4 months post-randomisation to evaluate trial retention, intervention uptake and variance in outcomes to inform a sample size calculation. Qualitative data were collected from participants and psychological wellbeing practitioners (PWPs) to assess the acceptability and feasibility of the trial methods and the intervention. Routine data were collected to evaluate resource use and cost. RESULTS: Sixty people with depression were recruited, and a 73 % follow-up rate was achieved. Accelerometer physical activity data were collected for 64 % of those followed. Twenty participants (33 %) attended at least one treatment appointment. Interview data were analysed for 15 participants and 9 study PWPs. The study highlighted the challenges of conducting an RCT within existing IAPT services with high staff turnover and absences, participant scheduling issues, PWP and participant preferences for cognitive focussed treatment, and deviations from BA delivery protocols. The BAcPAc intervention was generally acceptable to patients and PWPs. CONCLUSIONS: Although recruitment procedures and data collection were challenging, participants generally engaged with the BAcPAc self-help booklets and reported willingness to increase their physical activity. A number of feasibility issues were identified, in particular the under-use of BA as a treatment for depression, the difficulty that PWPs had in adapting their existing procedures for study purposes and the instability of the IAPT PWP workforce. These problems would need to be better understood and resolved before proceeding to a full-scale RCT. TRIAL REGISTRATION: ISRCTN74390532 . Registered on 26 March 2013
Stochastic population growth in spatially heterogeneous environments
Classical ecological theory predicts that environmental stochasticity
increases extinction risk by reducing the average per-capita growth rate of
populations. To understand the interactive effects of environmental
stochasticity, spatial heterogeneity, and dispersal on population growth, we
study the following model for population abundances in patches: the
conditional law of given is such that when is small the
conditional mean of is approximately , where and are the abundance and per
capita growth rate in the -th patch respectivly, and is the
dispersal rate from the -th to the -th patch, and the conditional
covariance of and is approximately . We show for such a spatially extended population that if
is the total population abundance, then ,
the vector of patch proportions, converges in law to a random vector
as , and the stochastic growth rate equals the space-time average per-capita growth rate
\sum_i\mu_i\E[Y_\infty^i] experienced by the population minus half of the
space-time average temporal variation \E[\sum_{i,j}\sigma_{ij}Y_\infty^i
Y_\infty^j] experienced by the population. We derive analytic results for the
law of , find which choice of the dispersal mechanism produces an
optimal stochastic growth rate for a freely dispersing population, and
investigate the effect on the stochastic growth rate of constraints on
dispersal rates. Our results provide fundamental insights into "ideal free"
movement in the face of uncertainty, the persistence of coupled sink
populations, the evolution of dispersal rates, and the single large or several
small (SLOSS) debate in conservation biology.Comment: 47 pages, 4 figure
How long does a shoulder replacement last? A systematic review and meta-analysis of case series and national registry reports with more than 10 years of follow-up
This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordBackground: Shoulder replacement is an increasingly common treatment for end-stage degenerative shoulder conditions. Some shoulder replacements are unsuccessful and additional operations might be required. It is important for patients and clinicians to know how long shoulder replacements last and how effectively they reduce pain and improve function. This study aims to determine the longevity and long-term efficacy of shoulder replacements. Methods: In this systematic review and meta-analysis, we searched MEDLINE and Embase from their inception to Sept 24, 2019, for case series and registry data reporting 10-year or longer survival of total shoulder replacements, humeral hemiarthroplasties, and reverse total shoulder replacements of a specific brand of implant. Survival, implant, and patient-reported outcome measures data were extracted. The primary outcome was implant survival. We reviewed and analysed national joint replacement registries separately. We weighted each series by SE and calculated a pooled survival estimate at years 10, 15, and 20. For patient-reported outcome measures we pooled the standardised mean difference at 10 years. This study is registered with PROSPERO, CRD42019140221. Findings: 927 non-duplicate articles were identified by our search, nine articles (reporting ten series) were eligible for analysis of survival and six articles were eligible for analysis of patient reported outcomes. The ten series reported all-cause survival of 529 total shoulder replacements and 364 humeral hemiarthroplasties; no series for reverse total shoulder replacement met the inclusion criteria. The estimated 10-year survival for total shoulder replacement was 94·6% (95% CI 93·6–97·6) and humeral hemiarthroplasties was 90·4% (87·0–94·0). A single registry contributed 7651 total shoulder replacements, 1395 humeral hemiarthroplasties, and 7953 reverse total shoulder replacements. The pooled registry 10-year survival was 92·0% (95% CI 91·0–93·0) for total shoulder replacement, 85·5% (83·3–87·7) for humeral hemiarthroplasties, and 94·4% (93·4–95·7) for patients with osteoarthritis who had reverse total shoulder replacement and 93·6% (91·1–95·8) for patients with rotator cuff arthropathy who had reverse total shoulder replacement. Pooled 10-year patient-reported outcome measures showed a substantial improvement from baseline scores, with a standardised mean difference of 2·13 (95% CI 1·93–2·34). Interpretation: Our data show that approximately 90% of shoulder replacements last for longer than 10 years and patient-reported benefits are sustained. Our findings will be of use to surgeons and patients in the informed consent process and to health-care providers for resource planning. Funding: The National Institute for Health Research, the National Joint Registry for England, Wales, Northern Ireland, and Isle of Man, and the Royal College of Surgeons of England.National Institute for Health Research (NIHR)National Joint Registry for England, Wales, Northern Ireland, and Isle of ManRoyal College of Surgeons of Englan
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