663 research outputs found
Direct observation of molecular cooperativity near the glass transition
We describe direct observations of molecular cooperativity near the glass
transition in poly-vinyl-acetate (PVAc), through nanometer-scale probing of
dielectric fluctuations. Molecular clusters switched spontaneously between two
to four distinct configurations, producing complex random-telegraph-signals
(RTS). Analysis of the RTS and their power spectra shows that individual
clusters exhibit both transient dynamical heterogeneity and non-exponential
kinetics.Comment: 14 pages pdf, need Acrobat Reade
Spinning Loop Black Holes
In this paper we construct four Kerr-like spacetimes starting from the loop
black hole Schwarzschild solutions (LBH) and applying the Newman-Janis
transformation. In previous papers the Schwarzschild LBH was obtained replacing
the Ashtekar connection with holonomies on a particular graph in a
minisuperspace approximation which describes the black hole interior. Starting
from this solution, we use a Newman-Janis transformation and we specialize to
two different and natural complexifications inspired from the complexifications
of the Schwarzschild and Reissner-Nordstrom metrics. We show explicitly that
the space-times obtained in this way are singularity free and thus there are no
naked singularities. We show that the transformation move, if any, the
causality violating regions of the Kerr metric far from r=0. We study the
space-time structure with particular attention to the horizons shape. We
conclude the paper with a discussion on a regular Reissner-Nordstrom black hole
derived from the Schwarzschild LBH and then applying again the Newmann-Janis
transformation.Comment: 18 pages, 18 figure
Spectral Evidence for Emergent Order in BaNaFeAs
We report an angle-resolved photoemission spectroscopy study of the
iron-based superconductor family, BaNaFeAs. This system
harbors the recently discovered double-Q magnetic order appearing in a
reentrant C phase deep within the underdoped regime of the phase diagram
that is otherwise dominated by the coupled nematic phase and collinear
antiferromagnetic order. From a detailed temperature-dependence study, we
identify the electronic response to the nematic phase in an orbital-dependent
band shift that strictly follows the rotational symmetry of the lattice and
disappears when the system restores C symmetry in the low temperature
phase. In addition, we report the observation of a distinct electronic
reconstruction that cannot be explained by the known electronic orders in the
system
Lattice dynamics and correlated atomic motion from the atomic pair distribution function
The mean-square relative displacements (MSRD) of atomic pair motions in
crystals are studied as a function of pair distance and temperature using the
atomic pair distribution function (PDF). The effects of the lattice vibrations
on the PDF peak widths are modelled using both a multi-parameter Born
von-Karman (BvK) force model and a single-parameter Debye model. These results
are compared to experimentally determined PDFs. We find that the near-neighbor
atomic motions are strongly correlated, and that the extent of this correlation
depends both on the interatomic interactions and crystal structure. These
results suggest that proper account of the lattice vibrational effects on the
PDF peak width is important in extracting information on static disorder in a
disordered system such as an alloy. Good agreement is obtained between the BvK
model calculations of PDF peak widths and the experimentally determined peak
widths. The Debye model successfully explains the average, though not detailed,
natures of the MSRD of atomic pair motion with just one parameter. Also the
temperature dependence of the Debye model largely agrees with the BvK model
predictions. Therefore, the Debye model provides a simple description of the
effects of lattice vibrations on the PDF peak widths.Comment: 9 pages, 11 figure
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Erratum: Consortium biology in immunology: The perspective from the Immunological Genome Project
J-2156, a small molecule somatostatin type 4 receptor agonist, alleviated hindpaw hypersensitivity in the streptozotocin-induced rat model of painful diabetic neuropathy but with a 2-fold decrease in potency at an advanced stage in the model, mimicking morphine
There is a large unmet need for novel pain-killers to improve relief of painful diabetic neuropathy (PDN). Herein, we assessed the efficacy of the somatostatin type 4 (SST4) receptor agonist, J-2156, for relief of PDN in rats. Diabetes was induced with streptozotocin (STZ; 70 mg/kg) and bilateral hindpaw hypersensitivity was fully developed by 8-week post-STZ. In the intervals, 8â12-weeks (morphine-sensitive phase; Phase 1) and 16â18-weeks (morphine-hyposensitive phase; Phase 2) post-STZ, rats received a single dose of intraperitoneal (i.p.) J-2156 (10, 20, 30 mg/kg), gabapentin (100 mg/kg i.p.), subcutaneous morphine (1 mg/kg) or vehicle. Hindpaw withdrawal thresholds (PWTs) were assessed using von Frey filaments pre-dose and at regular intervals over 3-h post-dose. In Phase 1, J-2156 at 30 mg/kg evoked significant anti-allodynia in the hindpaws with maximal effect at 1.5 h compared with 1 h for gabapentin and morphine. The durations of action for all three compounds were greater than 3 h. The corresponding mean (±SEM) extent and duration of anti-allodynia (ÎPWT AUC) for gabapentin did not differ significantly from that for J-2156 (30 mg/kg) or morphine. However, in Phase 2, the ÎPWT AUC for morphine was reduced to approximately 25% of that in Phase 1, mirroring our previous work. Similarly, the mean (±SEM) ÎPWT AUC for J-2156 (30 mg/kg) in Phase 2 was approximately 45% of that for Phase 1 whereas for gabapentin the mean (±SEM) ÎPWT AUCs did not differ significantly (p > 0.05) between the two phases. Our findings further describe the preclinical pain relief profile of J-2156 and complement previous work in rat models of inflammatory pain, neuropathic pain and low back pain. SST4 receptor agonists hold promise as novel therapeutics for the relief of PDN, a type of peripheral neuropathic pain that is often intractable to relief with clinically used drug treatment options
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CLEC-2 and Syk in the megakaryocytic/platelet lineage are essential for development
The C-type lectin receptor CLEC-2 signals through a pathway that is critically dependent on the tyrosine kinase Syk. We show that homozygous loss of either protein results in defects in brain vascular and lymphatic development, lung inflation and perinatal lethality. Furthermore, we find that conditional deletion of Syk in the haematopoietic lineage, or conditional deletion of CLEC-2 or Syk in the megakaryocyte/platelet lineage, also causes defects in brain vascular and lymphatic development, although the mice are viable. In contrast, conditional deletion of Syk in other haematopoietic lineages had no effect on viability or brain vasculature and lymphatic development. We show that platelets, but not platelet releasate, modulate the migration and intercellular adhesion of lymphatic endothelial cells through a pathway that is dependent on CLEC-2 and Syk. These studies demonstrate that megakaryocyte/platelet expression of CLEC-2 and Syk is required for normal brain vasculature and lymphatic development and that platelet CLEC-2 and Syk directly modulate lymphatic endothelial cell behaviour in vitro
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Combined sensitivity to the neutrino mass ordering with JUNO, the IceCube Upgrade, and PINGU
The ordering of the neutrino mass eigenstates is one of the fundamental open questions in neutrino physics. While current-generation neutrino oscillation experiments are able to produce moderate indications on this ordering, upcoming experiments of the next generation aim to provide conclusive evidence. In this paper we study the combined performance of the two future multi-purpose neutrino oscillation experiments JUNO and the IceCube Upgrade, which employ two very distinct and complementary routes toward the neutrino mass ordering. The approach pursued by the 20 kt medium-baseline reactor neutrino experiment JUNO consists of a careful investigation of the energy spectrum of oscillated Îœe produced by ten nuclear reactor cores. The IceCube Upgrade, on the other hand, which consists of seven additional densely instrumented strings deployed in the center of IceCube DeepCore, will observe large numbers of atmospheric neutrinos that have undergone oscillations affected by Earth matter. In a joint fit with both approaches, tension occurs between their preferred mass-squared differences Îm312=m32-m12 within the wrong mass ordering. In the case of JUNO and the IceCube Upgrade, this allows to exclude the wrong ordering at >5Ï on a timescale of 3-7 years - even under circumstances that are unfavorable to the experiments' individual sensitivities. For PINGU, a 26-string detector array designed as a potential low-energy extension to IceCube, the inverted ordering could be excluded within 1.5 years (3 years for the normal ordering) in a joint analysis
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Design and performance of the first IceAct demonstrator at the South Pole
In this paper we describe the first results of IceAct, a compact imaging air-Cherenkov telescope operating in coincidence with the IceCube Neutrino Observatory (IceCube) at the geographic South Pole. An array of IceAct telescopes (referred to as the IceAct project) is under consideration as part of the IceCube-Gen2 extension to IceCube. Surface detectors in general will be a powerful tool in IceCube-Gen2 for distinguishing astrophysical neutrinos from the dominant backgrounds of cosmic-ray induced atmospheric muons and neutrinos: the IceTop array is already in place as part of IceCube, but has a high energy threshold. Although the duty cycle will be lower for the IceAct telescopes than the present IceTop tanks, the IceAct telescopes may prove to be more effective at lowering the detection threshold for air showers. Additionally, small imaging air-Cherenkov telescopes in combination with IceTop, the deep IceCube detector or other future detector systems might improve measurements of the composition of the cosmic ray energy spectrum. In this paper we present measurements of a first 7-pixel imaging air Cherenkov telescope demonstrator, proving the capability of this technology to measure air showers at the South Pole in coincidence with IceTop and the deep IceCube detector
Clinical characteristics and role of early cardiac magnetic resonance imaging in patients with suspected ST-elevation myocardial infarction and normal coronary arteries
A variety of conditions other than acute myocardial infarction may cause ST-elevation. Our objective was to evaluate the impact of cardiac magnetic resonance (CMR) on differential diagnosis from a prospective series of patients with suspected ST-elevation myocardial infarction (STEMI) and completely normal coronary arteries. Among 1,145 patients with suspected STEMI, 49 patients had completely normal coronary arteries and entered a prospective registry. CMR was done within 24 h, if possible, and included function analyses, T2-weighted imaging (T2 ratio), T1-weighted imaging before and after gadolineum administration (global relative enhancement; gRE), and late gadolineum enhancement (LGE). All patients were asked for a follow-up CMR after approximately 3 months. The incidence of patients with suspected STEMI and normal coronary arteries was 4.3% and mean age was 45 ± 14 years (STEMI group 64 ± 13 years; P < 0.001). 55% had a recent history of infection. Cardiac biomarkers showed a moderate elevation on admission. There was a significant change from baseline to follow-up for LV end-diastolic volumes (EDV) (P < 0.001), LV mass (P < 0.05), mean T2 ratio (P < 0.05), and LGE volume (P < 0.05). Major diagnostic groups were myocarditis (29%), pericarditis (27%), and takotsubo cardiomyopathy (10%). 18% were regarded as non-diagnostic. The study showed an incidence of 4.3% of patients with suspected STEMI and completely normal coronary arteries. Early CMR was valuable in the evaluation of the differential diagnoses and to exclude myocardial abnormalities in patients with uncertain aetiology. Further studies are needed for the assessment of long-term outcome
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