467 research outputs found
Reframing the mammoth steppe: Insights from analysis of isotopic niches
Woolly mammoth (Mammuthus primigenius), horse (Equus spp.) and bison (Bison spp.) coexisted with a variety of mammalian megafauna across the Pleistocene mammoth steppe – a megacontinental ecosystem that spanned northern Eurasia and northwestern North America. Previous research has suggested that highly conserved niches with minimal niche overlap allowed high levels of species diversity on the mammoth steppe. Here we evaluate previously published and some new collagen carbon and nitrogen isotope data (δ13C, δ15N) for mammoth steppe megaherbivores using Stable Isotope Bayesian Ellipses in R (SIBER) and linear regression models to determine isotopic niches for individual species during broad time intervals (pre-, during and post-Last Glacial Maximum (LGM)) at multiple geographic regions across the mammoth steppe. Individual species maintained relatively consistent isotopic niche positions at different geographic locations and during different times. Diet and habitat niches for any given species appear to have been similar across the mammoth steppe. Between some regions and times, however, species' isotopic niches changed, suggesting adaptation to local climatic conditions and/or changes in the nitrogen isotope patterns at the base of the food web. Isotopic niche overlap, including at the level of core niche overlap (>60% overlap), was observed in at least one time and region for most species. This overlap suggests high levels of functional redundancy in the ecosystem, whereby one species could fulfil another's ecological role in the latter's absence. Despite spatial and temporal environmental variation, species' adaptability and functional redundancy within the ecosystem would have made the mammoth steppe a highly resilient ecosystem
Observation of Target Electron Momentum Effects in Single-Arm M\o ller Polarimetry
In 1992, L.G. Levchuk noted that the asymmetries measured in M\o ller
scattering polarimeters could be significantly affected by the intrinsic
momenta of the target electrons. This effect is largest in devices with very
small acceptance or very high resolution in laboratory scattering angle. We use
a high resolution polarimeter in the linac of the polarized SLAC Linear
Collider to study this effect. We observe that the inclusion of the effect
alters the measured beam polarization by -14% of itself and produces a result
that is consistent with measurements from a Compton polarimeter. Additionally,
the inclusion of the effect is necessary to correctly simulate the observed
shape of the two-body elastic scattering peak.Comment: 29 pages, uuencoded gzip-compressed postscript (351 kb). Uncompressed
postscript file (898 kb) available to DECNET users as
SLC::USER_DISK_SLC1:[MORRIS]levpre.p
The Frequency Dependent Conductivity of Electron Glasses
Results of DC and frequency dependent conductivity in the quantum limit, i.e.
hw > kT, for a broad range of dopant concentrations in nominally uncompensated,
crystalline phosphorous doped silicon and amorphous niobium-silicon alloys are
reported. These materials fall under the general category of disordered
insulating systems, which are referred to as electron glasses. Using microwave
resonant cavities and quasi-optical millimeter wave spectroscopy we are able to
study the frequency dependent response on the insulating side of the
metal-insulator transition. We identify a quantum critical regime, a Fermi
glass regime and a Coulomb glass regime. Our phenomenological results lead to a
phase diagram description, or taxonomy, of the electrodynamic response of
electron glass systems
Patency of endoscopic ultrasound-guided gastroenterostomy in the treatment of malignant gastric outlet obstruction
Background and study aims Endoscopic ultrasoundguided gastroenterostomy (EUS-GE) with a lumen-apposing metal stent (LAMS) is a novel, minimally invasive technique in the palliative treatment of malignant gastric outlet
obstruction (GOO). Several studies have demonstrated feasibility and safety of EUS-GE, but evidence on long-term
durability is limited. The aim of this study was to evaluate
patency of EUS-GE in treatment of malignant GOO.
Patients and Methods An international multicenter study
was performed in seven centers in four European countries.
Patients who underwent EUS-GE with a LAMS between
March 2015 and March 2019 for palliative treatment of
symptomatic malignant GOO were included retrospectively. Our main outcome was recurrent obstruction due to
LAMS dysfunction; other outcomes of interest were technical success, clinical success, adverse events (AEs), and survival.
Results A total of 45 patients (mean age 69.9 ± 12.3 years
and 48.9% male) were included. Median duration of followup was 59 days (interquartile range [IQR] 41–128). Recurrent obstruction occurred in two patients (6.1 %), after 33
and 283 days of follow-up. Technical success was achieved
in 39 patients (86.7 %). Clinical success was achieved in 33
patients (73.3 %). AEs occurred in 12 patients (26.7 %), of
which five were fatal. Median overall survival was 57 days
(IQR 32–114).
Conclusions EUS-GE showed a low rate of recurrent obstruction. The relatively high number of fatal AEs underscores the importance of careful implementation of EUSGE in clinical practice
Porcine circovirus type 2 (PCV-2) coinfections in US field cases of postweaning multisystemic wasting syndrome (PMWS)
Efficacy and safety of alirocumab in insulin-treated patients with type 1 or type 2 diabetes and high cardiovascular risk:Rationale and design of the ODYSSEY DM-INSULIN trial
Aims: The coadministration of alirocumab, a PCSK9 inhibitor for treatment of hypercholesterolaemia, and insulin in diabetes mellitus (DM) requires further study. Described here is the rationale behind a phase-IIIb study designed to characterize the efficacy and safety of alirocumab in insulin-treated patients with type 1 (T1) or type 2 (T2) DM with hypercholesterolaemia and high cardiovascular (CV) risk. Methods: ODYSSEY DM-INSULIN (NCT02585778) is a randomized, double-blind, placebo-controlled, multicentre study that planned to enrol around 400 T2 and up to 100 T1 insulin-treated DM patients. Participants had low-density lipoprotein cholesterol (LDL-C) levels at screening. ≥. 70. mg/dL (1.81. mmol/L) with stable maximum tolerated statin therapy or were statin-intolerant, and taking (or not) other lipid-lowering therapy; they also had established CV disease or at least one additional CV risk factor. Eligible patients were randomized 2:1 to 24. weeks of alirocumab 75. mg every 2. weeks (Q2W) or a placebo. Alirocumab-treated patients with LDL-C. ≥. 70. mg/dL at week 8 underwent a blinded dose increase to 150. mg Q2W at week 12. Primary endpoints were the difference between treatment arms in percentage change of calculated LDL-C from baseline to week 24, and alirocumab safety. Results: This is an ongoing clinical trial, with 76 T1 and 441 T2 DM patients enrolled; results are expected in mid-2017. Conclusion: The ODYSSEY DM-INSULIN study will provide information on the efficacy and safety of alirocumab in insulin-treated individuals with T1 or T2 DM who are at high CV risk and have hypercholesterolaemia not adequately controlled by the maximum tolerated statin therapy
Time-Dependent CP Violation Effects in Partially Reconstructed Decays
We report measurements of time-dependent decay rates for decays and extraction of CP violation parameters related to .
We use a partial reconstruction technique, whereby signal events are identified
using information only from the primary pion and the charged pion from the
decay of the . The analysis uses of data
accumulated at the resonance with the Belle detector at the KEKB
asymmetric-energy collider. We measure the CP violation parameters
and .Comment: 15 pages, 5 figures. To appear in Physics Letters
Infrastructure for Detector Research and Development towards the International Linear Collider
The EUDET-project was launched to create an infrastructure for developing and
testing new and advanced detector technologies to be used at a future linear
collider. The aim was to make possible experimentation and analysis of data for
institutes, which otherwise could not be realized due to lack of resources. The
infrastructure comprised an analysis and software network, and instrumentation
infrastructures for tracking detectors as well as for calorimetry.Comment: 54 pages, 48 picture
Structures associated with feeding in three broad-mouthed, benthic fish groups
The flatheads, toadfishes, and goosefishes discussed here hold certain features in common. All are bottom-living forms with depressed head areas and broad gapes, and all eat large food items: fishes and/or crabs. All have developed structural specializations in association with this diet. The three groups are at most distantly related, and their feeding specializations are different and have evolved from different bases. In flatheads the combination of large food items and depressed head regions seems to have led to the separation of the two halves of the pelvic girdle, a feature in which they differ from their scorpaenoid relatives. Toadfish peculiarities associated with feeding are various but most notable in those that pass crabs they eat through the gape and into the mouth. Goosefish feeding is centered around the use of a lure to attract prey to within striking distance. The three fish groups are discussed separately, but their feeding structures are compared to one another in the final section of the paper.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42639/1/10641_2004_Article_BF00005053.pd
Teaching the Process of Molecular Phylogeny and Systematics: A Multi-Part Inquiry-Based Exercise
Three approaches to molecular phylogenetics are demonstrated to biology students as they explore molecular data from Homo sapiens and four related primates. By analyzing DNA sequences, protein sequences, and chromosomal maps, students are repeatedly challenged to develop hypotheses regarding the ancestry of the five species. Although these exercises were designed to supplement and enhance classroom instruction on phylogeny, cladistics, and systematics in the context of a postsecondary majors-level introductory biology course, the activities themselves require very little prior student exposure to these topics. Thus, they are well suited for students in a wide range of educational levels, including a biology class at the secondary level. In implementing this exercise, we have observed measurable gains, both in student comprehension of molecular phylogeny and in their acceptance of modern evolutionary theory. By engaging students in modern phylogenetic activities, these students better understood how biologists are currently using molecular data to develop a more complete picture of the shared ancestry of all living things
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