1,212 research outputs found
ALMA imaging of SDP.81 - I. A pixelated reconstruction of the far-infrared continuum emission
We present a sub-50 pc-scale analysis of the gravitational lens system SDP.81
at redshift 3.042 using Atacama Large Millimetre/submillimetre Array (ALMA)
science verification data. We model both the mass distribution of the
gravitational lensing galaxy and the pixelated surface brightness distribution
of the background source using a novel Bayesian technique that fits the data
directly in visibility space. We find the 1 and 1.3 mm dust emission to be
magnified by a factor of u_tot = 17.6+/-0.4, giving an intrinsic total
star-formation rate of 315+/-60 M_sol/yr and a dust mass of 6.4+/-1.5*10^8
M_sol. The reconstructed dust emission is found to be non-uniform, but composed
of multiple regions that are heated by both diffuse and strongly clumped
star-formation. The highest surface brightness region is a ~1.9*0.7 kpc
disk-like structure, whose small extent is consistent with a potential
size-bias in gravitationally lensed starbursts. Although surrounded by extended
star formation, with a density of 20-30+/-10 M_sol/yr/kpc^2, the disk contains
three compact regions with densities that peak between 120-190+/-20
M_sol/yr/kpc^2. Such star-formation rate densities are below what is expected
for Eddington-limited star-formation by a radiation pressure supported
starburst. There is also a tentative variation in the spectral slope of the
different star-forming regions, which is likely due to a change in the dust
temperature and/or opacity across the source.Comment: MNRAS accepted 2015 April 1
ALMA imaging of SDP.81 - II. A pixelated reconstruction of the CO emission lines
We present a sub-100 pc-scale analysis of the CO molecular gas emission and
kinematics of the gravitational lens system SDP.81 at redshift 3.042 using
Atacama Large Millimetre/submillimetre Array (ALMA) science verification data
and a visibility-plane lens reconstruction technique. We find clear evidence
for an excitation dependent structure in the unlensed molecular gas
distribution, with emission in CO (5-4) being significantly more diffuse and
structured than in CO (8-7). The intrinsic line luminosity ratio is r_8-7/5-4 =
0.30 +/- 0.04, which is consistent with other low-excitation starbursts at z ~
3. An analysis of the velocity fields shows evidence for a star-forming disk
with multiple velocity components that is consistent with a
merger/post-coalescence merger scenario, and a dynamical mass of M(< 1.56 kpc)
= 1.6 +/- 0.6 x 10^10 M_sol . Source reconstructions from ALMA and the Hubble
Space Telescope show that the stellar component is offset from the molecular
gas and dust components. Together with Karl G. Jansky Very Large Array CO (1-0)
data, they provide corroborative evidence for a complex ~2 kpc-scale starburst
that is embedded within a larger ~15 kpc structure.Comment: MNRAS accepted, 6th July 201
Self-tuned quantum dot gain in photonic crystal lasers
We demonstrate that very few (1 to 3) quantum dots as a gain medium are
sufficient to realize a photonic crystal laser based on a high-quality
nanocavity. Photon correlation measurements show a transition from a thermal to
a coherent light state proving that lasing action occurs at ultra-low
thresholds. Observation of lasing is unexpected since the cavity mode is in
general not resonant with the discrete quantum dot states and emission at those
frequencies is suppressed. In this situation, the quasi-continuous quantum dot
states become crucial since they provide an energy-transfer channel into the
lasing mode, effectively leading to a self-tuned resonance for the gain medium.Comment: 4 pages, 4 figures, submitted to Phys. Re
Human leucocyte antigen diversity: a biological gift to escape infections, no longer a barrier for haploidentical hemopoietic stem cell transplantation
Since the beginning of life, every multicellular organism appeared to have a complex innate immune system although the adaptive immune system, centred on lymphocytes bearing antigen receptors generated by somatic recombination, arose in jawed fish approximately 500 million years ago. The major histocompatibility complex MHC, named the Human leucocyte antigen (HLA) system in humans, represents a vital function structure in the organism by presenting pathogen-derived peptides to T cells as the main initial step of the adaptive immune response. The huge level of polymorphism observed in HLA genes definitely reflects selection, favouring heterozygosity at the individual or population level, in a pathogen-rich environment, although many are located in introns or in exons that do not code for the antigen-biding site of the HLA. Over the past three decades, the extent of allelic diversity at HLA loci has been well characterized using high-resolution HLA-DNA typing and the number of new HLA alleles, produced through next-generation sequencing methods, is even more rapidly increasing. The level of the HLA system polymorphism represents an obstacle to the search of potential compatible donors for patients affected by haematological disease proposed for a hematopoietic stem cell transplant (HSCT). Data reported in literature clearly show that antigenic and/or allelic mismatches between related or unrelated donors and patients influences the successful HSCT outcome. However, the recent development of the new transplant strategy based on the choice of haploidentical donors for HSCT is questioning the role of HLA compatibility, since the great HLA disparities present do not worsen the overall clinical outcome. Nowadays, NGS has contributed to define at allelic levels the HLA polymorphism and solve potential ambiguities. However, HLA functions and tissue typing probably need to be further investigated in the next future, to understand the reasons why in haploidentical transplants the presence of a whole mismatch haplotype between donors and recipients, both the survival rate and the incidence of acute GvHD or graft rejection are similar to those reported for unrelated HSCTs
Star formation properties of sub-mJy radio sources
We investigate the star formation properties of ~800 sources detected in one
of the deepest radio surveys at 1.4 GHz. Our sample spans a wide redshift range
(~0.1 - 4) and about four orders of magnitude in star formation rate (SFR). It
includes both star forming galaxies (SFGs) and active galactic nuclei (AGNs),
further divided into radio-quiet and radio-loud objects. We compare the SFR
derived from the far infrared luminosity, as traced by Herschel, with the SFR
computed from their radio emission. We find that the radio power is a good SFR
tracer not only for pure SFGs but also in the host galaxies of RQ AGNs, with no
significant deviation with redshift or specific SFR. Moreover, we quantify the
contribution of the starburst activity in the SFGs population and the
occurrence of AGNs in sources with different level of star formation. Finally
we discuss the possibility of using deep radio survey as a tool to study the
cosmic star formation history.Comment: 18 pages, 14 figures, 1 table (available in its entirety as ancillary
data
Facility for fast neutron irradiation tests of electronics at the ISIS spallation neutron source
The VESUVIO beam line at the ISIS spallation neutron source was set up for neutron irradiation tests in the neutron energy range above 10 MeV. The neutron flux and energy spectrum were shown, in benchmark activation measurements, to provide a neutron spectrum similar to the ambient one at sea level, but with an enhancement in intensity of a factor of 107. Such conditions are suitable for accelerated testing of electronic components, as was demonstrated here by measurements of soft error rates in recent technology field programable gate arrays
BAT2 and BAT3 polymorphisms as novel genetic risk factors for rejection after HLA-related SCT.
The genetic background of donor and recipient is an important factor determining the outcome of allogeneic hematopoietic SCT (allo-HSCT). We applied whole-genome analysis to investigate genetic variants - other than HLA class I and II - associated with negative outcome after HLA-identical sibling allo-HSCT in a cohort of 110 β-Thalassemic patients. We identified two single-nucleotide polymorphisms (SNPs) in BAT2 (A/G) and BAT3 (T/C) genes, SNP rs11538264 and SNP rs10484558, both located in the HLA class III region, in strong linkage disequilibrium between each other (R2 =0.92). When considered as single SNP, none of them reached a significant association with graft rejection (nominal P<0.00001 for BAT2 SNP rs11538264, and P<0.0001 for BAT3 SNP rs10484558), whereas the BAT2/BAT3 A/C haplotype was present at significantly higher frequency in patients who rejected as compared to those with functional graft (30.0% vs 2.6%, nominal P=1.15 × 10-8; and adjusted P=0.0071). The BAT2/BAT3 polymorphisms and specifically the A/C haplotype may represent a novel immunogenetic factor associated with graft rejection in patients undergoing allo-HSCT
Profile alterations of a symmetrical light pulse coming through a quantum well
The theory of a response of a two-energy-level system, irradiated by
symmetrical light pulses, has been developed.(Suchlike electronic system
approximates under the definite conditions a single ideal quantum well (QW) in
a strong magnetic field {\bf H}, directed perpendicularly to the QW's plane, or
in magnetic field absence.) The general formulae for the time-dependence of
non-dimensional reflection {\cal R}(t), absorption {\cal A}(t) and transmission
{\cal T}(t) of a symmetrical light pulse have been obtained. It has been shown
that the singularities of three types exist on the dependencies {\cal R}(t),
{\cal A}(t), {\cal T}(t). The oscillating time dependence of {\cal R}(t), {\cal
A}(t), {\cal T}(t) on the detuning frequency \Delta\omega=\omega_l-\omega_0
takes place. The oscillations are more easily observable when
\Delta\omega\simeq\gamma_l. The positions of the total absorption, reflection
and transparency singularities are examined when the frequency \omega_l is
detuned.Comment: 9 pages, 13 figures with caption
Stability Test for Sorghum Mutant Lines Derived From Induced Mutations with Gamma-Ray Irradiation
Sorghum breeding program had been conducted at the Center for the Application of Isotopes and Radiation Technology, BATAN. Plant genetic variability was increased through induced mutations using gamma-ray irradiation. Through selection process in successive generations, some promising mutant lines had been identified to have good agronomic characteristics with high grain yield. These breeding lines were tested in multi location trials and information of the genotypic stability was obtained to meet the requirements for officially varietal release by the Ministry of Agriculture. A total of 11 sorghum lines and varieties consisting of 8 mutant lines derived from induced mutations (B-100, B-95, B-92, B-83, B-76, B-75, B-69 and Zh-30) and 3 control varieties (Durra, UPCA-S1 and Mandau) were included in the experiment. All materials were grown in 10 agro-ecologically different locations namely Gunungkidul, Bantul, Citayam, Garut, Lampung, Bogor, Anyer, Karawaci, Cianjur and Subang. In each location, the local adaptability test was conducted by randomized block design with 3 replications. Data of grain yield was used for evaluating genotypic stability using AMMI approach. Results revealed that sorghum mutation breeding had generated 3 mutant lines (B-100, B-76 and Zh-30) exhibiting grain yield significantly higher than the control varieties. These mutant lines were genetically stable in all locations so that they would be recommended for official release as new sorghum varieties to the Ministry of Agriculture.Received: 20 November 2010; Revised: 01 August 2011; Accepted: 05 August 201
Controlling the dynamics of a coupled atom-cavity system by pure dephasing : basics and potential applications in nanophotonics
The influence of pure dephasing on the dynamics of the coupling between a
two-level atom and a cavity mode is systematically addressed. We have derived
an effective atom-cavity coupling rate that is shown to be a key parameter in
the physics of the problem, allowing to generalize the known expression for the
Purcell factor to the case of broad emitters, and to define strategies to
optimize the performances of broad emitters-based single photon sources.
Moreover, pure dephasing is shown to be able to restore lasing in presence of
detuning, a further demonstration that decoherence can be seen as a fundamental
resource in solid-state cavity quantum electrodynamics, offering appealing
perspectives in the context of advanced nano-photonic devices.Comment: 10 pages, 7 figure
- …