159 research outputs found
Faraday Rotation Spectroscopy of Quantum-Dot Quantum Wells
Time-resolved Faraday rotation studies of CdS/CdSe/CdS quantum-dot quantum
wells have recently shown that the Faraday rotation angle exhibits several
well-defined resonances as a function of probe energy close to the absorption
edge. Here, we calculate the Faraday rotation angle from the eigenstates of the
quantum-dot quantum well obtained with k.p theory. We show that the large
number of narrow resonances with comparable spectral weight observed in
experiment is not reproduced by the level scheme of a quantum-dot quantum well
with perfect spherical symmetry. A simple model for broken spherical symmetry
yields results in better qualitative agreement with experiment.Comment: 9 pages, 4 figure
Long-range epidemic spreading with immunization
We study the phase transition between survival and extinction in an epidemic
process with long-range interactions and immunization. This model can be viewed
as the well-known general epidemic process (GEP) in which nearest-neighbor
interactions are replaced by Levy flights over distances r which are
distributed as P(r) ~ r^(-d-sigma). By extensive numerical simulations we
confirm previous field-theoretical results obtained by Janssen et al. [Eur.
Phys. J. B7, 137 (1999)].Comment: LaTeX, 14 pages, 4 eps figure
Spin dynamics and level structure of quantum-dot quantum wells
We have characterized CdS/CdSe/CdS quantum-dot quantum wells using
time-resolved Faraday rotation (TRFR). The spin dynamics show that the electron
g-factor varies as a function of quantum well width and the transverse spin
lifetime of several nano-seconds is robust up to room temperature. As a
function of probe energy, the amplitude of the TRFR signal shows pronounced
resonances, which allow one to identify individual exciton transitions. While
the TRFR data are inconsistent with the conduction and valence band level
scheme of spherical quantum-dot quantum wells, a model in which broken
spherical symmetry is taken into account captures the essential features.Comment: 5 pages, 3 figure
Lenalidomide in cancer cachexia: a randomized trial of an anticancer drug applied for anti-cachexia
Background
Cancer cachexia (CC) impacts quality of life, physical function, anticancer treatment response, and survival. Inflammation is a prominent pathomechanism of CC. This small-scale study sets out to investigate the immunomodulatory drug lenalidomide in inflammatory CC in a randomized, double-blind, placebo-controlled trial.
Methods
Patients with advanced solid malignancies, documented weight loss, no or unchanged anticancer treatment, and C-reactive protein > 30 mg/L were included. In a 2:2:1 randomization, patients received either lenalidomide 25 mg once daily or C-reactive protein-guided dose, starting with 5 mg lenalidomide once daily or placebo once a day for 8 weeks. Dose adaption and safety were assessed twice a week. Treatment response was defined as an increase of lean body mass of more than 2% in a lower lumbar computed tomography and an increase in dynamometer-assessed handgrip strength of 4 kg. Secondary endpoints included adverse events, C-reactive protein response, nutritional intake, and symptoms.
Results
Of 24 eligible patients, 16 were included (25% female). At baseline, the mean age was 67 (range 51–88) years, and mean body weight was 64.7 kg (range 39.8–87.2 kg). Five were diagnosed with mesothelioma, two with non-small-cell lung cancer, two with renal cell carcinoma, two with neuroendocrine tumours, and five with other malignancies. Mean survival was 43 days. Eleven adverse events (four of which were severe) were recorded with a probable link to study participation. Nine patients completed the study. No participant showed a treatment response. C-reactive protein-guided dosing did not result in lower doses of lenalidomide. Lean body mass decreased less in the treatment groups. For the lenalidomide and placebo groups respectively, handgrip strength decreased by 2.3 vs. 5.5 kg, nutritional intake decreased by 249 vs. 32 kcal/day, and C-reactive protein increased by 35 mg/dL vs. decreased by 17 mg/dL. The study was closed prematurely due to slow accrual and the need for concurrent anticancer treatments.
Conclusions
No treatment response on muscle mass and muscle strength was observed with lenalidomide. Because of several limiting factors, including low recruitment caused in part by an ambitious study design and concomitant anticancer treatment, this study did not generate adequate data to draw reliable conclusions
Differences in Shedding of the Interleukin-11 Receptor by the Proteases ADAM9, ADAM10, ADAM17, Meprin α, Meprin β and MT1-MMP
Interleukin-11 (IL-11) has been associated with inflammatory conditions, bone homeostasis, hematopoiesis, and fertility. So far, these functions have been linked to classical IL-11 signaling via the membrane bound receptor (IL-11R). However, a signaling cascade via the soluble IL-11R (sIL-11R), generated by proteolytic cleavage, can also be induced. This process is called IL-11 trans-signaling. A disintegrin and metalloprotease 10 (ADAM10) and neutrophil elastase were described as ectodomain sheddases of the IL-11R, thereby inducing trans-signaling. Furthermore, previous studies employing approaches for the stimulation and inhibition of endogenous ADAM-proteases indicated that ADAM10, but not ADAM17, can cleave the IL-11R. Herein, we show that several metalloproteases, namely ADAM9, ADAM10, ADAM17, meprin β, and membrane-type 1 matrix metalloprotease/matrix metalloprotease-14 (MT1-MMP/MMP-14) when overexpressed are able to shed the IL-11R. All sIL-11R ectodomains were biologically active and capable of inducing signal transducer and activator of transcription 3 (STAT3) phosphorylation in target cells. The difference observed for ADAM10/17 specificity compared to previous studies can be explained by the different approaches used, such as stimulation of protease activity or making use of cells with genetically deleted enzymes
Molecular spintronics: Coherent spin transfer in coupled quantum dots
Time-resolved Faraday rotation has recently demonstrated coherent transfer of
electron spin between quantum dots coupled by conjugated molecules. Using a
transfer Hamiltonian ansatz for the coupled quantum dots, we calculate the
Faraday rotation signal as a function of the probe frequency in a pump-probe
setup using neutral quantum dots. Additionally, we study the signal of one
spin-polarized excess electron in the coupled dots. We show that, in both
cases, the Faraday rotation angle is determined by the spin transfer
probabilities and the Heisenberg spin exchange energy. By comparison of our
results with experimental data, we find that the transfer matrix element for
electrons in the conduction band is of order 0.08 eV and the spin transfer
probabilities are of order 10%.Comment: 13 pages, 6 figures; minor change
Lenalidomide in cancer cachexia : a randomized trial of an anticancer drug applied for anti‐cachexia
Background: Cancer cachexia (CC) impacts quality of life, physical function, anticancer treatment response, and survival. Inflammation is a prominent pathomechanism of CC. This small-scale study sets out to investigate the immunomodulatory drug lenalidomide in inflammatory CC in a randomized, double-blind, placebo-controlled trial.
Methods: Patients with advanced solid malignancies, documented weight loss, no or unchanged anticancer treatment, and C-reactive protein>30 mg/L were included. In a 2:2:1 randomization, patients received either lenalidomide25 mg once daily or C-reactive protein-guided dose, starting with 5 mg lenalidomide once daily or placebo once a day for 8 weeks. Dose adaption and safety were assessed twice a week. Treatment response was defined as an increase of lean body mass of more than 2% in a lower lumbar computed tomography and an increase in dynamometer-assessed handgrip strength of 4 kg. Secondary endpoints included adverse events, C-reactive protein response, nutritional intake, and symptoms.
Results: Of 24 eligible patients, 16 were included (25% female). At baseline, the mean age was 67 (range 51–88) years, and mean body weight was 64.7 kg (range 39.8–87.2 kg). Five were diagnosed with mesothelioma, two with non-small-cell lung cancer, two with renal cell carcinoma, two with neuroendocrine tumours, and five with other malignancies. Mean survival was 43 days. Eleven adverse events (four of which were severe) were recorded with a probable link to study participation. Nine patients completed the study. No participant showed a treatment response. C-reactive protein-guided dosing did not result in lower doses of lenalidomide. Lean body mass decreased less in the treatment groups. For the lenalidomide and placebo groups respectively, handgrip strength decreased by 2.3 vs.5.5 kg, nutritional intake decreased by 249 vs. 32 kcal/day, and C-reactive protein increased by 35 mg/dL vs. decreased by 17 mg/dL. The study was closed prematurely due to slow accrual and the need for concurrent anticancer treatments.
Conclusions: No treatment response on muscle mass and muscle strength was observed with lenalidomide. Because of several limiting factors, including low recruitment caused in part by an ambitious study design and concomitant anti-cancer treatment, this study did not generate adequate data to draw reliable conclusions
A combined measurement of cosmic growth and expansion from clusters of galaxies, the CMB and galaxy clustering
Combining galaxy cluster data from the ROSAT All-Sky Survey and the Chandra
X-ray Observatory, cosmic microwave background data from the Wilkinson
Microwave Anisotropy Probe, and galaxy clustering data from the WiggleZ Dark
Energy Survey, the 6-degree Field Galaxy Survey and the Sloan Digital Sky
Survey III, we test for consistency the cosmic growth of structure predicted by
General Relativity (GR) and the cosmic expansion history predicted by the
cosmological constant plus cold dark matter paradigm (LCDM). The combination of
these three independent, well studied measurements of the evolution of the mean
energy density and its fluctuations is able to break strong degeneracies
between model parameters. We model the key properties of cosmic growth with the
normalization of the matter power spectrum, sigma_8, and the cosmic growth
index, gamma, and those of cosmic expansion with the mean matter density,
Omega_m, the Hubble constant, H_0, and a kinematical parameter equivalent to
that for the dark energy equation of state, w. For a spatially flat geometry,
w=-1, and allowing for systematic uncertainties, we obtain sigma_8=0.785+-0.019
and gamma=0.570+0.064-0.063 (at the 68.3 per cent confidence level). Allowing
both w and gamma to vary we find w=-0.950+0.069-0.070 and gamma=0.533+-0.080.
To further tighten the constraints on the expansion parameters, we also include
supernova, Cepheid variable and baryon acoustic oscillation data. For w=-1, we
have gamma=0.616+-0.061. For our most general model with a free w, we measure
Omega_m=0.278+0.012-0.011, H_0=70.0+-1.3 km s^-1 Mpc^-1 and
w=-0.987+0.054-0.053 for the expansion parameters, and sigma_8=0.789+-0.019 and
gamma=0.604+-0.078 for the growth parameters. These results are in excellent
agreement with GR+LCDM (gamma~0.55; w=-1) and represent the tightest and most
robust simultaneous constraint on cosmic growth and expansion to date.Comment: 14 pages, 5 figures, 1 table. Matches the accepted version for MNRAS.
New sections 3 and 6 added, containing 2 new figures. Table extended. The
results including BAO data have been slightly modified due to an updated BAO
analysis. Conclusions unchange
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