1,036 research outputs found
High-spin structures of 136Cs
Odd-odd 136Cs nuclei have been produced in the 18O + 208Pb and 12C + 238U
fusion-fission reactions and their gamma rays studied with the Euroball array.
The high-spin level scheme has been built up to ~ 4.7 MeV excitation energy and
spin I ~ 16 hbar from the triple gamma-ray coincidence data. The configurations
of the three structures observed above ~ 2 MeV excitation energy are first
discussed by analogy with the proton excitations identified in the semi-magic
137Cs nucleus, which involve the three high-j orbits lying above the Z=50 gap,
pi g_{7/2}, pi d_{5/2} and pi h_{11/2}. This is confirmed by the results of
shell-model calculations performed in this work.Comment: 6 pages, 4 figures, 3 table
Isomeric states in No
6 pagesInternational audienceIsomeric states in 253No have been investigated by conversion-electron and gamma-ray spectroscopy with the GABRIELA detection system. The 31 micro second isomer reported more than 30 years ago is found to decay to the ground state of 253No by the emission of a 167 keV M2 transition. The spin and parity of this low-lying isomeric state are established to be 5/2+. The presence of another longer-lived isomeric state is also discussed
Coplanar Ternary Cluster Decay of Hyper-deformed Ni
Coincidences between two heavy fragments have been measured from fission of 56Ni compound nuclei, formed in the 32S + 24Mg reaction at Elab(32S) = 163.5 MeV. A unique experimental set-up consisting of two large area position sensitive (x, y) gas-detector telescopes has been used allowing the complete determination of the observed fragments, and their momentum vectors. In addition to binary fission events with subsequent particle evaporation, narrow out-of-plane correlations are observed for two fragments emitted in purely binary events and in events with a missing mass consisting of 2 and 3 particles(12C). These events are interpreted as ternary cluster decay from 56Ni-nuclei at high angular momenta through hyper-deformed shape
Comparison of two analysis methods for nuclear reaction measurements of 12C +12C interactions at 95 MeV/u for hadrontherapy
During therapeutic treatment with heavier ions like carbon, the beam
undergoes nuclear fragmentation and secondary light charged particles, in
particular protons and alpha particles, are produced. To estimate the dose
deposited into the tumors and the surrounding healthy tissues, the accuracy
must be higher than (3% and1 mm). Therefore, measurements are
performed to determine the double differential cross section for different
reactions. In this paper, the analysis of data from 12C +12C reactions at 95
MeV/u are presented. The emitted particles are detected with
\DeltaEthin-\DeltaEthick-E telescopes made of a stack of two silicon detectors
and a CsI crystal. Two different methods are used to identify the particles.
One is based on graphical cuts onto the \DeltaE-E maps, the second is based on
the so-called KaliVeda method using a functional description of \DeltaE versus
E. The results of the two methods will be presented in this paper as well as
the comparison between both
High-spin structures of five N=82 isotones: 136Xe, 137Cs, 138Ba, 139La, and 140Ce
Five N=82 isotones have been produced in two fusion-fission reactions and
their gamma-rays studied with the Euroball array. The high-spin states of 139La
have been identified for the first time, while the high-spin yrast and
near-to-yrast structures of the four others have been greatly extended. From
angular correlation analysis,spin values have been assigned to some states of
136Xe and 137Cs. Several cascades involving gamma-rays of 139La have been found
to be delayed, they deexcite an isomeric state with T1/2= 315(35) ns located at
1800-keV excitation energy. The excited states of these five N=82 isotones are
expected to be due to various proton excitations involving the three high-j
subshells located above the Z=50 shell closure. This is confirmed by the
results of shell-model calculations performed in this work. In addition,
high-spin states corresponding to the excitation of the neutron core have been
unambiguously identified in 136Xe, 137Cs, and 138Ba.Comment: 18 pages, 18 figures, 10 tables, accepted for publication in Phys.
Rev.
Efficient multi-class fetal brain segmentation in high resolution MRI reconstructions with noisy labels
Segmentation of the developing fetal brain is an important step in
quantitative analyses. However, manual segmentation is a very time-consuming
task which is prone to error and must be completed by highly specialized
indi-viduals. Super-resolution reconstruction of fetal MRI has become standard
for processing such data as it improves image quality and resolution. However,
dif-ferent pipelines result in slightly different outputs, further complicating
the gen-eralization of segmentation methods aiming to segment super-resolution
data. Therefore, we propose using transfer learning with noisy multi-class
labels to automatically segment high resolution fetal brain MRIs using a single
set of seg-mentations created with one reconstruction method and tested for
generalizability across other reconstruction methods. Our results show that the
network can auto-matically segment fetal brain reconstructions into 7 different
tissue types, regard-less of reconstruction method used. Transfer learning
offers some advantages when compared to training without pre-initialized
weights, but the network trained on clean labels had more accurate
segmentations overall. No additional manual segmentations were required.
Therefore, the proposed network has the potential to eliminate the need for
manual segmentations needed in quantitative analyses of the fetal brain
independent of reconstruction method used, offering an unbiased way to quantify
normal and pathological neurodevelopment.Comment: Accepted for publication at PIPPI MICCAI 202
Coadministration of Adenoviral Vascular Endothelial Growth Factor and Angiopoietin-1 Enhances Vascularization and Reduces Ventricular Remodeling in the Infarcted Myocardium of Type 1 Diabetic Rats
OBJECTIVE - Hyperglycemia impairs angiogenesis in response to ischemia, leading to ventricular remodeling. Although the effects of overexpressing angiogenic growth factors have been studied in inducing angiogenesis, the formation of functional vessels remains a challenge. The present study evaluates the reversal of diabetes-mediated impairment of angiogenesis in the infarcted diabetic rat myocardium by proangiogenic gene therapy. RESEARCH DESIGN AND METHODS - Ad.VEGF and Ad.Ang1 were intramyocardially administered in combination immediately after myocardial infarction to nondiabetic and diabetic rats. Ad.LacZ was similarly administered to the respective control groups. The hearts were excised for molecular and immunohistochemical analysis at predetermined time points. The myocardial function was measured by echocardiography 30 days after the intervention. RESULTS - We observed reduced fibrosis and increased capillary/arteriolar density along with reduced ventricular remodeling, as assessed by echocardiography in the treated diabetic animals compared with the nontreated diabetic controls. We also observed increased phosphorylated mitogen-activated protein kinase-activated protein kinase-2, 2 days after the treatment and increased expression of vascular endothelial growth factor (VEGF), Flk-1, angiopoietin-1 (Ang-1), Tie-2, and survivin, 4 days after treatment in the diabetic animals. Gel shift analysis revealed that the combination gene therapy stimulated the DNA binding activity of nuclear factor-κB in the diabetic animals. CONCLUSIONS - Our preclinical data demonstrate the efficacy of coadministration of adenoviral VEGF and Ang-1 in increasing angiogenesis and reducing ventricular remodeling in the infarcted diabetic myocardium. These unique results call for the initiation of a clinical trial to assess the efficacy of this therapeutic strategy in the treatment of diabetes-related human heart failure
Broad and Gag-Biased HIV-1 Epitope Repertoires Are Associated with Lower Viral Loads
Background: HLA class-I alleles differ in their ability to control HIV replication through cell-mediated immune responses. No consistent associations have been found between the breadth of Cytotoxic T Lymphocytes (CTL) responses and the control of HIV-1, and it is unknown whether the size or distribution of the viral proteome-wide epitope repertoire, i.e., the intrinsic ability to present fewer, more or specific viral epitopes, could affect clinical markers of disease progression. Methodology/Principal Findings: We used an epitope prediction model to identify all epitope motifs in a set of 302 HIV-1 full-length proteomes according to each individual's HLA (Human Leukocyte Antigen) genotype. The epitope repertoire, i.e., the number of predicted epitopes per HIV-1 proteome, varied considerably between HLA alleles and thus among individual proteomes. In a subgroup of 270 chronically infected individuals, we found that lower viral loads and higher CD4 counts were associated with a larger predicted epitope repertoire. Additionally, in Gag and Rev only, more epitopes were restricted by alleles associated with low viral loads than by alleles associated with higher viral loads. Conclusions/Significance: This comprehensive analysis puts forth the epitope repertoire as a mechanistic component of the multi-faceted HIV-specific CTL response. The favorable impact on markers of disease status of the propensity to present more HLA binding peptides and specific proteins gives impetus to vaccine design strategies that seek to elicit responses to a broad array of HIV-1 epitopes, and suggest a particular focus on Gag
Modelling study of dimerization in mammalian defensins
BACKGROUND: Defensins are antimicrobial peptides of innate immunity functioning by non-specific binding to anionic phospholipids in bacterial membranes. Their cationicity, amphipathicity and ability to oligomerize are considered key factors for their action. Based on structural information on human β-defensin 2, we examine homologous defensins from various mammalian species for conserved functional physico-chemical characteristics. RESULTS: Based on homology greater than 40%, structural models of 8 homologs of HBD-2 were constructed. A conserved pattern of electrostatics and dynamics was observed across 6 of the examined defensins; models backed by energetics suggest that the defensins in these 6 organisms are characterized by dimerization-linked enhanced functional potentials. In contrast, dimerization is not energetically favoured in the sheep, goat and mouse defensins, suggesting that they function efficiently as monomers. CONCLUSION: β-defensin 2 from some mammals may work as monomers while those in others, including humans, work as oligomers. This could potentially be used to design human defensins that may be effective at lower concentrations and hence have therapeutic benefits
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