| 1. |
- Aggarwal, MM, et al.
(författare)
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Centrality dependence of charged-neutral particle fluctuations in 158A (GeVPb)-Pb-208+Pb-208 collisions
- 2003
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 67:4
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Tidskriftsartikel (refereegranskat)abstract
- Results on the study of localized fluctuations in the multiplicity of charged particles and photons produced in 158A GeV/c Pb+Pb collisions are presented for varying centralities. The charged versus neutral particle multiplicity correlations in common phase space regions of varying azimuthal sizes are analyzed by two different methods. Various types of mixed events are constructed to probe fluctuations arising from different sources. The measured results are compared to those from simulations and from mixed events. The comparison indicates the presence of nonstatistical fluctuations in both the charged particle and photon multiplicities in limited azimuthal regions. However, no correlated charged-neutral fluctuations, a possible signature of formation of disoriented chiral condensates, are observed. An upper limit on the production of disoriented chiral condensates is set.
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| 2. |
- Aggarwal, MM, et al.
(författare)
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Event-by-event fluctuations in particle multiplicities and transverse energy produced in 158A GeVPb plus Pb collisions
- 2002
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 65:5
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Tidskriftsartikel (refereegranskat)abstract
- Event-by-event fluctuations in the multiplicities of charged particles and photons, and the total transverse energy in 158A GeV Pb+Pb collisions are studied for a wide range of centralities. For narrow centrality bins the multiplicity and transverse energy distributions are found to be near perfect Gaussians. The effect of detector acceptance on the multiplicity fluctuations has been studied and demonstrated to follow statistical considerations. The centrality dependence of the charged particle multiplicity fluctuations in the measured data has been found to agree reasonably well with those obtained from a participant model. However, for photons the multiplicity fluctuations have been found to be lower compared to those obtained from a participant model. The multiplicity and transverse energy fluctuations have also been compared to those obtained from the VENUS event generator.
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| 3. |
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| 4. |
- Aggarwal, MM, et al.
(författare)
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Transverse mass distributions of neutral pions from Pb-208-induced reactions at 158 center dot A GeV
- 2002
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 23:2, s. 225-236
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Tidskriftsartikel (refereegranskat)abstract
- Results on transverse mass spectra of neutral pious measured at central rapidity are presented for impact parameter selected 158-A GeV Pb + Pb-1 and Pb + Nb collisions. The distributions cover the range 0.5 GeV/c(2) less than or equal to MT - Mo less than or equal to 4 GeV/c(2). The change of the spectral shape and the multiplicity with centrality is studied in detail. In going from p+p to semi-peripheral Pb+Pb collisions there is a nuclear enhancement increasing with transverse mass similar to the well known Cronin effect, while for very central collisions this enhancement appears to be weaker than expected.
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| 5. |
- Dewaraja, YK, et al.
(författare)
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A parallel Monte Carlo code for planar and SPECT imaging: implementation, verification and applications in I-131 SPECT
- 2002
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Ingår i: Computer Methods and Programs in Biomedicine. - 0169-2607. ; 67:2, s. 115-124
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports the implementation of the SIMIND Monte Carlo code on an IBM SP2 distributed memory parallel computer. Basic aspects of running Monte Carlo particle transport calculations on parallel architectures are described. Our parallelization is based on equally partitioning photons among the processors and uses the Message Passing Interface (MPI) library for interprocessor communication and the Scalable Parallel Random Number Generator (SPRNG) to generate uncorrelated random number streams. These parallelization techniques are also applicable to other distributed memory architectures. A linear increase in computing speed with the number of processors is demonstrated for Lip to 32 processors. This speed-up is especially significant in Single Photon Emission Computed Tomography (SPECT) simulations involving higher energy photon emitters, where explicit modeling of the phantom and collimator is required. For I-131, the accuracy of the parallel code is demonstrated by comparing simulated and experimental SPECT images from a heart/thorax phantom. Clinically realistic SPECT simulations using the voxel-man phantom are carried out to assess scatter and attenuation correction.
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| 6. |
- Majumdar, A, et al.
(författare)
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Wnt11 and Ret/Gdnf pathways cooperate in regulating ureteric branching during metanephric kidney development
- 2003
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Ingår i: Development (Cambridge, England). - : The Company of Biologists. - 0950-1991 .- 1477-9129. ; 130:14, s. 3175-3185
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Tidskriftsartikel (refereegranskat)abstract
- Reciprocal cell-cell interactions between the ureteric epithelium and the metanephric mesenchyme are needed to drive growth and differentiation of the embryonic kidney to completion. Branching morphogenesis of the Wolffian duct derived ureteric bud is integral in the generation of ureteric tips and the elaboration of the collecting duct system. Wnt11, a member of the Wnt superfamily of secreted glycoproteins, which have important regulatory functions during vertebrate embryonic development, is specifically expressed in the tips of the branching ureteric epithelium. In this work, we explore the role of Wnt11 in ureteric branching and use a targeted mutation of the Wnt11 locus as an entrance point into investigating the genetic control of collecting duct morphogenesis. Mutation of the Wnt11 gene results in ureteric branching morphogenesis defects and consequent kidney hypoplasia in newborn mice. Wnt11 functions, in part, by maintaining normal expression levels of the gene encoding glial cell-derived neurotrophic factor (Gdnf). Gdnf encodes a mesenchymally produced ligand for the Ret tyrosine kinase receptor that is crucial for normal ureteric branching. Conversely, Wnt11 expression is reduced in the absence of Ret/Gdnf signaling. Consistent with the idea that reciprocal interaction between Wnt11 and Ret/Gdnf regulates the branching process, Wnt11 and Ret mutations synergistically interact in ureteric branching morphogenesis. Based on these observations, we conclude that Wnt11 and Ret/Gdnf cooperate in a positive autoregulatory feedback loop to coordinate ureteric branching by maintaining an appropriate balance of Wnt11-expressing ureteric epithelium and Gdnf-expressing mesenchyme to ensure continued metanephric development.
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| 7. |
- Fong, L. G., et al.
(författare)
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Heterozygosity for Lmna deficiency eliminates the progeria-like phenotypes in Zmpste24-deficient mice
- 2004
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Ingår i: Proc Natl Acad Sci U S A. ; 101:52, s. 18111-18116
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Tidskriftsartikel (refereegranskat)abstract
- Zmpste24 is a metalloproteinase required for the processing of prelamin A to lamin A, a structural component of the nuclear lamina. Zmpste24 deficiency results in the accumulation of prelamin A within cells, a complete loss of mature lamin A, and misshapen nuclear envelopes. Zmpste24-deficient (Zmpste24(-/-)) mice exhibit retarded growth, alopecia, micrognathia, dental abnormalities, osteolytic lesions in bones, and osteoporosis, which are phenotypes shared with Hutchinson-Gilford progeria syndrome, a human disease caused by the synthesis of a mutant prelamin A that cannot undergo processing to lamin A. Zmpste24(-/-) mice also develop muscle weakness. We hypothesized that prelamin A might be toxic and that its accumulation in Zmpste24(-/-) mice is responsible for all of the disease phenotypes. We further hypothesized that Zmpste24(-/-) mice with half-normal levels of prelamin A (Zmpste24(-/-) mice with one Lmna knockout allele) would be subjected to less toxicity and be protected from disease. Thus, we bred and analyzed Zmpste24(-/-)Lmna(+/-) mice. As expected, prelamin A levels in Zmpste24(-/-)Lmna(+/-) cells were significantly reduced. Zmpste24(-/-)Lmna(+/-) mice were entirely normal, lacking all disease phenotypes, and misshapen nuclei were less frequent in Zmpste24(-/-)Lmna(+/-) cells than in Zmpste24(-/-) cells. These data suggest that prelamin A is toxic and that reducing its levels by as little as 50% provides striking protection from disease.
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| 8. |
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| 9. |
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| 10. |
- Majumdar, A, et al.
(författare)
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Zebrafish no isthmus reveals a role for pax2.1 in tubule differentiation and patterning events in the pronephric primordia
- 2000
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Ingår i: Development (Cambridge, England). - : The Company of Biologists. - 0950-1991 .- 1477-9129. ; 127:10, s. 2089-2098
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Tidskriftsartikel (refereegranskat)abstract
- Pax genes are important developmental regulators and function at multiple stages of vertebrate kidney organogenesis. In this report, we have used the zebrafish pax2.1 mutant no isthmus to investigate the role for pax2.1 in development of the pronephros. We demonstrate a requirement for pax2.1 in multiple aspects of pronephric development including tubule and duct epithelial differentiation and cloaca morphogenesis. Morphological analysis demonstrates that noi(−)larvae specifically lack pronephric tubules while glomerular cell differentiation is unaffected. In addition, pax2.1 expression in the lateral cells of the pronephric primordium is required to restrict the domains of Wilms' tumor suppressor (wt1) and vascular endothelial growth factor (VEGF) gene expression to medial podocyte progenitors. Ectopic podocyte-specific marker expression in pronephric duct cells correlates with loss of expression of the pronephric tubule and duct-specific markers mAb 3G8 and a Na(+)/K(+) ATPase (α)1 subunit. The results suggest that the failure in pronephric tubule differentiation in noi arises from a patterning defect during differentiation of the pronephric primordium and that mutually inhibitory regulatory interactions play an important role in defining the boundary between glomerular and tubule progenitors in the forming nephron.
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