PubMed Health⌕ Search

Biomedical subjects

S J Sanders

Publications and source records attributed to S J Sanders.

15 recordsLinked to original sources
PubMed2005

Charged meson rapidity distributions in central Au+Au collisions at square root(sNN) = 200 GeV.

We have measured rapidity densities dN/dy of pi+/- and K+/- over a broad rapidity range (-0.1 < y < 3.5) for central Au + Au collisions at square root(sNN) = 200 GeV. These data have significant implications for the chemistry and dynamics of the dense system that is initially created in the collisions. The full phase-space yields are 1660 +/- 15 +/- 133 (pi+), 1683 +/- 16 +/- 135 (pi-), 286 +/- 5 +/- 23 (K+), and 242 +/- 4 +/- 19 (K-). The systematics of the strange to nonstrange meson ratios are found to track the variation of the baryochemical potential with rapidity and energy. Landau-Carruthers hydrodynamics is found to describe the bulk transport of the pions in the longitudinal direction.

Journal Article↗
PubMed2005

Centrality dependence of charged-particle pseudorapidity distributions from d + Au collisions at sqrt[sNN] = 200 GeV.

Charged-particle pseudorapidity densities are presented for the d + Au reaction at sqrt[s(NN)] = 200 GeV with -4.2 < or = eta < or = 4.2. The results, from the BRAHMS experiment at BNL Relativistic Heavy-Ion Collider, are shown for minimum-bias events and 0%-30%, 30%-60%, and 60%-80% centrality classes. Models incorporating both soft physics and hard, perturbative QCD-based scattering physics agree well with the experimental results. The data do not support predictions based on strong-coupling, semiclassical QCD. In the deuteron-fragmentation region the central 200 GeV data show behavior similar to full-overlap d+Au results at sqrt[s(NN)] = 19.4 GeV.

Journal Article↗
PubMed2004

Evolution of the nuclear modification factors with rapidity and centrality in d + Au collisions at (sqrt)[N(S)N]=200 GeV.

We report on a study of the transverse momentum dependence of nuclear modification factors R(dAu) for charged hadrons produced in deuteron + gold collisions at sqrt[s(NN)]=200 GeV, as a function of collision centrality and of the pseudorapidity (eta=0, 1, 2.2, 3.2) of the produced hadrons. We find a significant and systematic decrease of R(dAu) with increasing rapidity. The midrapidity enhancement and the forward rapidity suppression are more pronounced in central collisions relative to peripheral collisions. These results are relevant to the study of the possible onset of gluon saturation at energies reached at BNL RHIC.

Journal Article↗
PubMed2004

Nuclear stopping in Au+Au collisions at square root of S(NN)=200 GeV.

Transverse momentum spectra and rapidity densities, dN/dy, of protons, antiprotons, and net protons (p-p) from central (0%-5%) Au+Au collisions at square root of S(NN)=200 GeV were measured with the BRAHMS experiment within the rapidity range 0</=y</=3. The proton and antiproton dN/dy decrease from midrapidity to y=3. The net-proton yield is roughly constant for y<1 at dN/dy approximately 7, and increases to dN/dy approximately 12 at y approximately 3. The data show that collisions at this energy exhibit a high degree of transparency and that the linear scaling of rapidity loss with rapidity observed at lower energies is broken. The energy loss per participant nucleon is estimated to be 73+/-6 GeV.

Journal Article↗
PubMed2003

Transverse-momentum spectra in Au+Au and d+Au collisions at sqrt[s(NN)]=200 GeV and the pseudorapidity dependence of high-p(T) suppression.

We present spectra of charged hadrons from Au+Au and d+Au collisions at sqrt[s(NN)]=200 GeV measured with the BRAHMS experiment at RHIC. The spectra for different collision centralities are compared to spectra from p+(-)p collisions at the same energy scaled by the number of binary collisions. The resulting ratios (nuclear modification factors) for central Au+Au collisions at eta=0 and eta=2.2 evidence a strong suppression in the high p(T) region (>2 GeV/c). In contrast, the d+Au nuclear modification factor (at eta=0) exhibits an enhancement of the high p(T) yields. These measurements indicate a high energy loss of the high p(T) particles in the medium created in the central Au+Au collisions. The lack of suppression in d+Au collisions makes it unlikely that initial state effects can explain the suppression in the central Au+Au collisions.

Journal Article↗
PubMed2003

Rapidity dependence of charged antihadron to hadron ratios in Au+Au collisions at sqrt[s(NN)]=200 GeV.

We present ratios of the numbers of charged antihadrons to hadrons (pions, kaons, and protons) in Au+Au collisions at sqrt[s(NN)]=200 GeV as a function of rapidity in the range y=0-3. While the ratios at midrapidity are approaching unity, the K(-)/K(+) and p;/p ratios decrease significantly at forward rapidities. An interpretation of the results within the statistical model indicates a reduction of the baryon chemical potential from mu(B) approximately 130 MeV at y=3 to mu(B) approximately 25 MeV at y=0.

Journal Article↗
PubMed2003

Hereditary hyperferritinaemia-cataract syndrome and differential diagnosis of hereditary haemochromatosis.

Hereditary hyperferritinaemia-cataract syndrome (HHCS) is a rare differential diagnosis of hereditary haemochromatosis. It should be suspected in patients with raised ferritin levels, but no evidence of iron overload, and in the absence of mutations in the HFE gene. Awareness of this condition prevents unnecessary liver biopsies and allows accurate genetic counselling since HHCS is an autosomal dominant disorder. The danger of treating these patients by phlebotomy in the same manner as those with hereditary haemochromatosis is highlighted.

Adult↗
PubMed2002

Pseudorapidity distributions of charged particles from Au + Au collisions at the maximum RHIC energy, square root[s(NN)] = 200 GeV.

We present charged-particle multiplicities as a function of pseudorapidity and collision centrality for the 197Au+197Au reaction at square root[s(NN)] = 200 GeV. For the 5% most central events we obtain dN(ch)/deta/(eta = 0) = 625+/-55 and N(ch)/(-4.7< or =eta < or =4.7) = 4630 +/- 370, i.e., 14% and 21% increases, respectively, relative to square root[s(NN)] = 130 GeV collisions. Charged-particle production per pair of participant nucleons is found to increase from peripheral to central collisions around midrapidity. These results constrain current models of particle production at the highest RHIC energy.

Journal Article↗
PubMed2001

Appositions between cocaine and amphetamine-related transcript- and gonadotropin releasing hormone-immunoreactive neurons in the hypothalamus of the Siberian hamster.

Recent in vitro studies have provided evidence that cocaine and amphetamine-related transcript (CART) pathways in the hypothalamus mediate the effects of leptin upon gonadotropin releasing hormone (GnRH) secretion. The aim of the current study was to use dual label immunofluorescence to investigate the anatomical basis of such a pathway. CART-ir processes were found extensively in regions where GnRH cell bodies where located. Analysis using confocal microscopy showed that the majority of GnRH neurons (62%) had close appositions from CART-ir processes. The proportion of GnRH-ir perikarya with CART-ir appositions was significantly higher (P<0.05) in neurons located in the diagonal band of Broca (70%) compared to those more caudally located in the preoptic area (53%). This anatomical evidence for close appositions between CART-ir processes and GnRH cell bodies supports the hypothesis that one mechanism by which leptin causes its effect on the GnRH pulse generator is indirectly via CART neurons, thus allowing information about nutritional status and body fat stores to be conveyed to the reproductive system.

Animals↗
PubMed2001

Empirical investigation of extreme single-particle behavior of nuclear quadrupole moments in highly collective A approximately 150 superdeformed bands.

The intrinsic quadrupole moment Q(0) of superdeformed rotational bands in A approximately 150 nuclei depends on the associated single-particle configuration. We have derived an empirical formula based on the additivity of effective quadrupole moments of single-particle orbitals that describes existing measurements from (142)Sm to (152)Dy. To further test the formula, the predicted Q(0) moments for two superdeformed bands in (146)Gd of 14.05 eb were confronted with a new measurement yielding 13.9+/-0.4 eb and 13.9+/-0.3 eb, respectively. This excellent agreement provides empirical evidence of extreme single-particle behavior in highly deformed, collective systems.

Journal Article↗
PubMed2001

Rapidity dependence of antiproton-to-proton ratios in Au+Au collisions at square root of (sNN) = 130 GeV.

Measurements, with the BRAHMS detector, of the antiproton-to-proton ratio at midrapidities and forward rapidities, are presented for Au+Au reactions at square root of [s(NN)] = 130 GeV, and for three different collision centralities. For collisions in the 0%-40% centrality range, we find N(&pmacr;)/N(p) = 0.64+/-0.04((stat))+/-0.06((syst)) at y approximately 0, 0.66+/-0.03+/-0.06 at y approximately 0.7, and 0.41+/-0.04+/-0.06 at y approximately 2. The ratios are found to be nearly independent of collision centrality and transverse momentum. The antiproton and proton rapidity densities vary differently with rapidity, and indicate a significant degree of collision transparency, although a net-baryon free midrapidity plateau (Bjorken limit) is not yet reached.

Journal Article↗
PubMed1995

Apolipophorin-III and adipokinetic hormone in lipid metabolism of larval Manduca sexta.

The hemolymph lipid levels were measured and the density of lipophorin was determined during late larval development in Manduca sexta. During the feeding phase of the 4th and 5th instar larvae the lipid level in hemolymph remained largely unchanged at less than 2 mg/ml. During the molt from 4th to 5th instar, the hemolymph lipid level increased, but decreased after feeding restarted in the 5th instar. In wandering larvae and prepupae the hemolymph lipid level increased from about 2 to nearly 10 mg/ml. The density of lipophorin from feeding larvae was found to be 1.148 g/ml with minor amounts of lipophorin having a lower density of about 1.128 g/ml and sometimes a small amount with a density of 1.174 g/ml. In molting larvae, however, the density was clearly lower, 1.116 g/ml. In wandering larvae of all ages, two predominant forms of lipophorin were observed; the density of these forms was 1.132 g/ml and 1.177 g/ml. Rarely, one or three different forms of lipophorin were observed. While the lipophorin of feeding larvae contains only apoLp-I and II (and lipids), the lipophorin of molting larvae contains in addition apoLp-III. ApoLp-III is seldom present in lipophorin from wandering larvae. According to our current models, lipophorin can take up only a certain amount of diacylglycerol before it needs apoLp-III for surface stabilization. Injection of 1 pmol of M. sexta AKH into feeding larvae increased the hemolymph lipid level, decreased the density of lipophorin to 1.125 g/ml and resulted in the association of apoLp-III with lipophorin. Cardiacectomy did not prevent feeding larvae from developing to wandering larvae.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Serum bactericidal testing with the Autobac system.

Current methodology for the serum bactericidal test requires a minimum of 48 h. A procedure was devised for performing this test with the Autobac system (General Diagnostics, Div. Organon Inc., Raleigh, N.C.) in a shortened time span. All titers obtained with the Autobac were compared against results obtained with a standardized tube dilution procedure. The Autobac low-thymidine eugonic broth performed comparably to the tube dilution diluent, a 1:1 ratio of pooled human serum and cation-supplemented Mueller-Hinton broth (99.2% correlation between bactericidal endpoints). Over 300 tests were conducted by using stock reference bacterial strains, clinical isolates, pooled human serum seeded with antimicrobial agents, and serum from patients on antimicrobial therapy. With the Autobac procedure, serum inhibitory titers can be reported in 3 to 4 h (93.4% correlation with the tube dilution procedure). Serum bactericidal titers can be obtained in 24 h without the necessity of subculturing (95.6% correlation). With the exception of staphylococci tested against penicillin, serum bactericidal titers can be obtained in 3 to 4 h (88.4% correlation). The Autobac procedure can provide the clinical laboratory with a rapid, reliable method for performing the serum bactericidal test.

Anti-Bacterial Agents↗