217 research outputs found
Inelastic Quantum Transport
We solve a Schrodinger equation for inelastic quantum transport that retains
full quantum coherence, in contrast to previous rate or Boltzmann equation
approaches. The model Hamiltonian is the zero temperature 1d Holstein model for
an electron coupled to optical phonons (polaron), in a strong electric field.
The Hilbert space grows exponentially with electron position, forming a
non-standard Bethe lattice. We calculate nonperturbatively the transport
current, electron-phonon correlations, and quantum diffusion. This system is a
toy model for the constantly branching ``wavefunction of the universe''.Comment: revtex, 13 pages, 4 figure
Theory of evidence and non-exhaustive frames of discernment
To represent a source's knowledge, all the existing theories work on a set of hypotheses of interest on which different treatment s
can be applied . Called the frame of discernment in the theory of evidence, it must have the property of exhaustivity, which mean s
that one of the hypotheses is the solution of the problem . Nevertheless, in some practical cases, this doesn't occur . Consequently,
the knowledge modelised in such a frame is incomplete because some hypotheses are not considered . The last literature doesn't
deal with this situation . This article gives some solutions in the theory of evidence's formalism, which appears the most appropriat e
in this case . A practical application could be for example a supervised classification problem of objects, when the learning set i s
incomplete, due to a lack of learning data for one or several objects .Pour modéliser la connaissance d'une source d'information, les différentes théories existantes ont toutes pour principe de travailler sur un référentiel de base, composé d'hypothèses d'intérêt sur lesquelles différents traitements peuvent porter par la suite. En général, ce référentiel est exhaustif signifiant que la solution se trouve parmi toutes les hypothèses considérées. Néanmoins, dans la pratique, il existe des cas où il ne l'est pas; la connaissance modélisée sur un tel référentiel est alors incomplète car elle ne permet pas de prendre en compte certaines hypothèses. Ceci forme un problème peu abordé dans la littérature. Cet article propose donc différentes solutions pour le traiter, dans le formalisme de la théorie de l'évidence qui est a priori la plus adaptée. Un cadre applicatif intéressant peut concerner, par exemple, un problème de classification supervisée d'objets dans le cas d'une base d'apprentissage incomplète, lorsque certaines données caractéristiques d'un objet ne sont pas disponibles lors de l'apprentissage
Atherosclerosis Development and Progression: The Role of Atherogenic Small, Dense LDL
Atherosclerosis is responsible for large cardiovascular mortality in many countries globally. It has been shown over the last decades that the reduction of atherosclerotic progression is a critical factor for preventing future cardiovascular events. Low-density lipoproteins (LDL) have been successfully targeted, and their reduction is one of the key preventing measures in patients with atherosclerotic disease. LDL particles are pivotal for the formation and progression of atherosclerotic plaques; yet, they are quite heterogeneous, and smaller, denser LDL species are the most atherogenic. These particles have greater arterial entry and retention, higher susceptibility to oxidation, as well as reduced affinity for the LDL receptor. Increased proportion of small, dense LDL particles is an integral part of the atherogenic lipoprotein phenotype, the most common form of dyslipidemia associated with insulin resistance. Recent data suggest that both genetic and epigenetic factors might induce expression of this specific lipid pattern. In addition, a typical finding of increased small, dense LDL particles was confirmed in different categories of patients with elevated cardiovascular risk. Small, dense LDL is an independent risk factor for cardiovascular diseases, which emphasizes the clinical importance of both the quality and the quantity of LDL. An effective management of atherosclerotic disease should take into account the presence of small, dense LDL in order to prevent cardiovascular complications
The K2-HERMES Survey: Age and Metallicity of the Thick Disc
Asteroseismology is a promising tool to study Galactic structure and
evolution because it can probe the ages of stars. Earlier attempts comparing
seismic data from the {\it Kepler} satellite with predictions from Galaxy
models found that the models predicted more low-mass stars compared to the
observed distribution of masses. It was unclear if the mismatch was due to
inaccuracies in the Galactic models, or the unknown aspects of the selection
function of the stars. Using new data from the K2 mission, which has a
well-defined selection function, we find that an old metal-poor thick disc, as
used in previous Galactic models, is incompatible with the asteroseismic
information. We show that spectroscopic measurements of [Fe/H] and
[/Fe] elemental abundances from the GALAH survey indicate a mean
metallicity of for the thick disc. Here is the
effective solar-scaled metallicity, which is a function of [Fe/H] and
[/Fe]. With the revised disc metallicities, for the first time, the
theoretically predicted distribution of seismic masses show excellent agreement
with the observed distribution of masses. This provides an indirect
verification of the asteroseismic mass scaling relation is good to within five
percent. Using an importance-sampling framework that takes the selection
function into account, we fit a population synthesis model of the Galaxy to the
observed seismic and spectroscopic data. Assuming the asteroseismic scaling
relations are correct, we estimate the mean age of the thick disc to be about
10 Gyr, in agreement with the traditional idea of an old -enhanced
thick disc.Comment: 21 pages, submitted to MNRA
The GALAH survey: New diffuse interstellar bands found in residuals of 872,000 stellar spectra
We use more than 872,000 mid-to-high resolution (R 20,000) spectra of
stars from the GALAH survey to discern the spectra of diffuse interstellar
bands (DIBs). We use four windows with the wavelength range from 4718 to 4903,
5649 to 5873, 6481 to 6739, and 7590 to 7890 \AA, giving a total coverage of
967 \AA. We produce 400,000 spectra of interstellar medium (ISM)
absorption features and correct them for radial velocities of the DIB clouds.
Ultimately, we combine the 33,115 best ISM spectra into six reddening bins with
a range of . A total
of 183 absorption features in these spectra qualify as DIBs, their fitted model
parameters are summarized in a detailed catalogue. From these, 64 are not
reported in the literature, among these 17 are certain, 14 are probable and 33
are possible. We find that the broad DIBs can be fitted with a multitude of
narrower DIBs. Finally, we create a synthetic DIB spectrum at unit reddening
which should allow us to narrow down the possible carriers of DIBs and explore
the composition of the ISM and ultimately better model dust and star formation
as well as to correct Galactic and extragalactic observations. The majority of
certain DIBs show a significant excess of equivalent width when compared to
reddening. We explain this with observed lines of sight penetrating more
uniform DIB clouds compared to clumpy dust clouds.Comment: 28 pages, 15 figures, 11 tables, accepted for publication in MNRA
Molecular velocity auto-correlation of simple liquids observed by NMR MGSE method
The velocity auto-correlation spectra of simple liquids obtained by the NMR
method of modulated gradient spin echo show features in the low frequency range
up to a few kHz, which can be explained reasonably well by a long
time tail decay only for non-polar liquid toluene, while the spectra of polar
liquids, such as ethanol, water and glycerol, are more congruent with the model
of diffusion of particles temporarily trapped in potential wells created by
their neighbors. As the method provides the spectrum averaged over ensemble of
particle trajectories, the initial non-exponential decay of spin echoes is
attributed to a spatial heterogeneity of molecular motion in a bulk of liquid,
reflected in distribution of the echo decays for short trajectories. While at
longer time intervals, and thus with longer trajectories, heterogeneity is
averaged out, giving rise to a spectrum which is explained as a combination of
molecular self-diffusion and eddy diffusion within the vortexes of hydrodynamic
fluctuations.Comment: 8 pages, 6 figur
The GALAH survey: velocity fluctuations in the Milky Way using red clump giants
If the Galaxy is axisymmetric and in dynamical equilibrium, we expect negligible fluctuations in the residual line-of-sight velocity field. However, non-axisymmetric structures like a bar, spiral arms and merger events can generate velocity fluctuations. Recent results using the APOGEE survey find significant fluctuations in velocity for stars in the midplane (|z|< 0.25 kpc) and out to 5 kpc, which suggests that the dynamical influence of the Milky Way's bar extends out to the Solar neighborhood. Their measured power spectrum has a characteristic amplitude of 11 km/s on a scale of ~ 2.5 kpc. The existence of large streaming motions on these scales has important implications for determining the Sun's motion about the Galactic Centre. Using red clump stars from the GALAH and APOGEE surveys, we map the line-of-sight velocity field around the Sun out to distances of 5 kpc and up to 1.25 kpc from the Galactic Plane. By subtracting a smooth axisymmetric model for the velocity field, we study the residual velocity fluctuations and compare our findings with mock survey generated by Galaxia based on an axisymmetric, steady state model. We find negligible large-scale fluctuations away from the plane. In the mid-plane, we reproduce the earlier APOGEE power spectrum results but with 20\% smaller amplitude (9.5 km/s) after taking a few systematic effects into account (e.g. volume completeness). The amplitude power is further reduced to 6.7 km/s if a flexible axisymmetric model is used. Additionally, our mock simulations show that, in the plane, the distances are underestimated for high mass red clump stars and this can lead to spurious power with amplitude of about 5.5 km/s. Taking this into account, we estimate the amplitude of real fluctuations to be less than 4.2 km/s, about a factor of three less than the previous result from APOGEE
Role of serum S100B and PET-CT in follow-up of patients with cutaneous melanoma
<p>Abstract</p> <p>Background</p> <p>Increased level of serum S100B can serve as a marker of metastatic spread in patients with cutaneous melanoma (CM). In patients with elevated S100 B and/or clinical signs of disease progression PET-CT scan is a valuable tool for discovering metastases and planning treatment.</p> <p>The aims of this study were to determine whether regular measurements of serum S100B are a useful tool for discovering patients with CM metastases and to evaluate the diagnostic value of PET-CT during the follow-up.</p> <p>Methods</p> <p>From September 2007 to February 2010, 115 CM patients included in regular follow up at the Institute of Oncology Ljubljana were appointed to PET-CT. There were 82 (71.3%) patients with clinical signs of disease progression and 33 (28.7%) asymptomatic patients with two subsequent elevated values of S100B. Sensitivity, specificity, positive and negative predictive value (PPV, NPV) of S100B and PET-CT were calculated using standard procedures.</p> <p>Results</p> <p>Disease progression was confirmed in 81.7% of patients (in 86.5% of patients with clinical signs of disease progression and in 69.7% of asymptomatic patients with elevated S100B). Sensitivity, specificity, PPV and NPV of S100B was 33.8%, 90.9%, 96.0% and 17.5% in patients with clinical signs of disease progression. In 20.0% of patients increased serum S100B was the only sign of disease progression. Sensitivity and PPV of S100 in this group of patients were 100.0% and 69.7%.</p> <p>With PET-CT disease progression was diagnosed in 84.2% of symptomatic patients and in 72.7% of asymptomatic patients with elevated S100B. The sensitivity, specificity, PPV and NPV of PET-CT for symptomatic patients was 98.5%, 90.9%, 98.5% and 90.9% and 100%, 90.0%, 95.8% and 100% for asymptomatic patients with elevated S100.</p> <p>Conclusions</p> <p>Measurements of serum S100B during regular follow-up of patients with CM are a useful tool for discovering disease progression in asymptomatic patients. The value of its use increases if measurements are followed by extended whole body PET-CT.</p
A phase Ib study evaluating the recommended phase II dose, safety, tolerability, and efficacy of mivavotinib in combination with nivolumab in advanced solid tumors
\ua9 2024 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.Mivavotinib (TAK-659/CB-659), a dual SYK/FLT3 inhibitor, reduced immunosuppressive immune cell populations and suppressed tumor growth in combination with anti-PD-1 therapy in cancer models. This dose-escalation/expansion study investigated the safety, pharmacokinetics, pharmacodynamics, and preliminary efficacy of mivavotinib plus nivolumab in patients with advanced solid tumors. Patients received oral mivavotinib 60–100 mg once-daily plus intravenous nivolumab 3 mg/kg on days 1 and 15 in 28-day cycles until disease progression or unacceptable toxicity. The dose-escalation phase evaluated the recommended phase II dose (RP2D; primary endpoint). The expansion phase evaluated overall response rate (primary end point) at the RP2D in patients with triple-negative breast cancer (TNBC). During dose-escalation (n = 24), two dose-limiting toxicities (grade 4 lipase increased and grade 3 pyrexia) occurred in patients who received mivavotinib 80 mg and 100 mg, respectively. The determined RP2D was once-daily mivavotinib 80 mg plus nivolumab 3 mg/kg. The expansion phase was terminated at ~50% enrollment (n = 17) after failing to meet an ad hoc efficacy futility threshold. Among all 41 patients, common treatment-emergent adverse events (TEAEs) included dyspnea (48.8%), aspartate aminotransferase increased, and pyrexia (46.3% each). Common grade ≥3 TEAEs were hypophosphatemia and anemia (26.8% each). Mivavotinib plasma exposure was generally dose-proportional (60–100 mg). One patient had a partial response. Mivavotinib 80 mg plus nivolumab 3 mg/kg was well tolerated with no new safety signals beyond those of single-agent mivavotinib or nivolumab. Low response rates highlight the challenges of treating unresponsive tumor types, such as TNBC, with this combination and immunotherapies in general. Trial registration ID: NCT02834247
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