4,758 research outputs found
Calibration-based abundances in the interstellar gas of galaxies from slit and IFU spectra
In this work we make use of available Integral Field Unit (IFU) spectroscopy
and slit spectra of several nearby galaxies. The pre-existing empirical R and S
calibrations for abundance determinations are constructed using a sample of HII
regions with high quality slit spectra. In this paper, we test the
applicability of those calibrations to the IFU spectra. We estimate the
calibration-based abundances obtained using both the IFU and the slit
spectroscopy for eight nearby galaxies. The median values of the slit and IFU
spectra-based abundances in bins of 0.1 in fractional radius Rg (normalized to
the optical radius) of a galaxy are determined and compared. We find that the
IFU and the slit spectra-based abundances obtained through the R calibration
are close to each other, the mean value of the differences of abundances is
0.005 dex and the scatter in the differences is 0.037 dex for 38 datapoints.
The S calibration can produce systematically underestimated values of the IFU
spectra-based abundances at high metallicities, the mean value of the
differences is -0.059 dex for 21 datapoints, while at lower metallicities the
mean value of the differences is -0.018 dex and the scatter is 0.045 dex for 36
data points. This evidences that the R calibration produces more consistent
abundance estimations between the slit and the IFU spectra than the S
calibration. We find that the same calibration can produce close estimations of
the abundances using IFU spectra obtained with different spatial resolution and
different spatial samplings. This is in line with the recent finding that the
contribution of the diffuse ionized gas to the large aperture spectra of HII
regions has a secondary effect.Comment: 15 pages, 14 figures, accepted to the Astronomy and Astrophysic
Phase IV open-label study of the efficacy and safety of deferasirox after allogeneic stem cell transplantation
This is the first prospective study of deferasirox in adult allogeneic hematopoietic stem cell transplant recipients with transfusional iron overload in hematologic malignancies. Patients at least six months post transplant were treated with deferasirox at a starting dose of 10 mg/kg/day for 52 weeks or until serum ferritin was less than 400 ng/mL on two consecutive occasions. Thirty patients were enrolled and 22 completed the study. A significant reduction from baseline in median serum ferritin and in liver iron concentration at 52 weeks was observed in the overall population: from 1440 to 755.5 ng/mL (P=0.002) and from 14.5 to 4.6 mg Fe/g dw (P=0.0007), respectively. Reduction in serum ferritin in patients who did not discontinue deferasirox therapy was significantly greater than that found in those who prematurely discontinued the treatment (from 1541 to 581 ng/mL vs. from 1416 to 1486 ng/mL; P=0.008). Drug-related adverse events, reported in 17 patients (56.7%), were mostly mild to moderate in severity. There were no drug-related serious adverse events. Twelve patients (40.0%) showed an increase of over 33% in serum creatinine compared to baseline and greater than the upper limit of normal on two consecutive visits. Two patients (6.7%) with active graft-versus-host disease showed an increase in alanine aminotransferase exceeding 10 times upper limit of normal; both resolved. In this prospective study, deferasirox provided a significant reduction in serum ferritin and liver iron concentration over one year of treatment in allogeneic hematopoietic stem cell transplant recipients with iron overload. In addition, the majority of adverse events related to deferasirox were mild or moderate in severity. (clinicaltrials.gov identifier:01335035)
Mapping cisplatin-induced viscosity alterations in cancer cells using molecular rotor and fluorescence lifetime imaging microscopy
Significance: Despite the importance of the cell membrane in regulation of drug activity, the influence of drug treatments on its physical properties is still poorly understood. The combination of fluorescence lifetime imaging microscopy (FLIM) with specific viscosity-sensitive fluorescent molecular rotors allows the quantification of membrane viscosity with high spatiotemporal resolution, down to the individual cell organelles. Aim: The aim of our work was to analyze microviscosity of the plasma membrane of living cancer cells during chemotherapy with cisplatin using FLIM and correlate the observed changes with lipid composition and cellâs response to treatment. Approach: FLIM together with viscosity-sensitive boron dipyrromethene-based fluorescent molecular rotor was used to map the fluidity of the cellâs membrane. Chemical analysis of membrane lipid composition was performed with time-of-flight secondary ion mass spectrometry (ToF-SIMS). Results: We detected a significant steady increase in membrane viscosity in viable cancer cells, both in cell monolayers and tumor spheroids, upon prolonged treatment with cisplatin, as well as in cisplatin-adapted cell line. ToF-SIMS revealed correlative changes in lipid profile of cisplatin-treated cells. Conclusions: These results suggest an involvement of membrane viscosity in the cell adaptation to the drug and in the acquisition of drug resistance
First Constraints from DAMIC-M on Sub-GeV Dark-Matter Particles Interacting with Electrons
We report constraints on sub-GeV dark matter particles interacting with electrons from the first underground operation of DAMIC-M detectors. The search is performed with an integrated exposure of 85.23 g days, and exploits the subelectron charge resolution and low level of dark current of DAMIC-M charge-coupled devices (CCDs). Dark-matter-induced ionization signals above the detector dark current are searched for in CCD pixels with charge up to 7eâ. With this dataset we place limits on dark matter particles of mass between 0.53 and 1000ââMeV/c2, excluding unexplored regions of parameter space in the mass ranges [1.6,1000]ââMeV/c2 and [1.5,15.1]ââMeV/c2 for ultralight and heavy mediator interactions, respectively
Measurement of the t t-bar production cross section in the dilepton channel in pp collisions at sqrt(s) = 7 TeV
The t t-bar production cross section (sigma[t t-bar]) is measured in
proton-proton collisions at sqrt(s) = 7 TeV in data collected by the CMS
experiment, corresponding to an integrated luminosity of 2.3 inverse
femtobarns. The measurement is performed in events with two leptons (electrons
or muons) in the final state, at least two jets identified as jets originating
from b quarks, and the presence of an imbalance in transverse momentum. The
measured value of sigma[t t-bar] for a top-quark mass of 172.5 GeV is 161.9 +/-
2.5 (stat.) +5.1/-5.0 (syst.) +/- 3.6(lumi.) pb, consistent with the prediction
of the standard model.Comment: Replaced with published version. Included journal reference and DO
Combined search for the quarks of a sequential fourth generation
Results are presented from a search for a fourth generation of quarks
produced singly or in pairs in a data set corresponding to an integrated
luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in
2011. A novel strategy has been developed for a combined search for quarks of
the up and down type in decay channels with at least one isolated muon or
electron. Limits on the mass of the fourth-generation quarks and the relevant
Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a
simple extension of the standard model with a sequential fourth generation of
fermions. The existence of mass-degenerate fourth-generation quarks with masses
below 685 GeV is excluded at 95% confidence level for minimal off-diagonal
mixing between the third- and the fourth-generation quarks. With a mass
difference of 25 GeV between the quark masses, the obtained limit on the masses
of the fourth-generation quarks shifts by about +/- 20 GeV. These results
significantly reduce the allowed parameter space for a fourth generation of
fermions.Comment: Replaced with published version. Added journal reference and DO
- âŚ