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2.
Phys Rev Lett ; 119(16): 162501, 2017 Oct 20.
Artículo en Inglés | MEDLINE | ID: mdl-29099223

RESUMEN

The charge and magnetic form factors, F_{C} and F_{M}, respectively, of ^{3}He are extracted in the kinematic range 25 fm^{-2}≤Q^{2}≤61 fm^{-2} from elastic electron scattering by detecting ^{3}He recoil nuclei and scattered electrons in coincidence with the two High Resolution Spectrometers of the Hall A Facility at Jefferson Lab. The measurements find evidence for the existence of a second diffraction minimum for the magnetic form factor at Q^{2}=49.3 fm^{-2} and for the charge form factor at Q^{2}=62.0 fm^{-2}. Both minima are predicted to exist in the Q^{2} range accessible by this Jefferson Lab experiment. The data are in qualitative agreement with theoretical calculations based on realistic interactions and accurate methods to solve the three-body nuclear problem.

3.
Phys Rev Lett ; 115(17): 172502, 2015 Oct 23.
Artículo en Inglés | MEDLINE | ID: mdl-26551107

RESUMEN

We report the first measurement of the target single-spin asymmetry, A(y), in quasielastic scattering from the inclusive reaction (3)He(↑)(e,e') on a (3)He gas target polarized normal to the lepton scattering plane. Assuming time-reversal invariance, this asymmetry is strictly zero for one-photon exchange. A nonzero A(y) can arise from the interference between the one- and two-photon exchange processes which is sensitive to the details of the substructure of the nucleon. An experiment recently completed at Jefferson Lab yielded asymmetries with high statistical precision at Q(2)=0.13, 0.46, and 0.97 GeV(2). These measurements demonstrate, for the first time, that the (3)He asymmetry is clearly nonzero and negative at the 4σ-9σ level. Using measured proton-to-(3)He cross-section ratios and the effective polarization approximation, neutron asymmetries of -(1-3)% were obtained. The neutron asymmetry at high Q(2) is related to moments of the generalized parton distributions (GPDs). Our measured neutron asymmetry at Q(2)=0.97 GeV(2) agrees well with a prediction based on two-photon exchange using a GPD model and thus provides a new, independent constraint on these distributions.

4.
Indian J Med Microbiol ; 33(4): 491-5, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26470953

RESUMEN

BACKGROUND: Human polyomavirus JC (JCV) is a widespread human virus with profound pathogenic potential. A study was undertaken to quantify JCV load in urine and peripheral blood samples of immunocompetent, apparently healthy tribal individuals of North-Eastern part of West Bengal, India for the first time. MATERIALS AND METHODS: One hundred and thirteen samples of urine or blood were collected from different tribal groups of this region. For the quantitative estimation of the viral load in each sample, real-time polymerase chain reaction method using the SYBR Green dye was employed. RESULTS: The viral load estimated was found in the range between 3.5 × 102 and 2.12 × 106 copies/ml of samples having a mean and median viral copy numbers of 8.67 × 105 and 9.19 × 105 copies/ml of sample respectively. CONCLUSION: The mean viral DNA load in urine samples of the studied immunocompetent population was found to be higher than that found in a study conducted in the USA, but lower than similar groups of Italy and healthy adult women in the USA. However when compared with median values of viral DNA loads in urine samples of immunocompetent human subjects of Kuwait, Portugal, and Switzerland the observed viral DNA load was found to be substantially higher.


Asunto(s)
Sangre/virología , Portador Sano/virología , Virus JC/aislamiento & purificación , Infecciones por Polyomavirus/virología , Infecciones Tumorales por Virus/virología , Orina/virología , Carga Viral , ADN Viral/genética , ADN Viral/aislamiento & purificación , Femenino , Humanos , India , Virus JC/genética , Masculino , Grupos de Población , Reacción en Cadena en Tiempo Real de la Polimerasa
5.
Phys Rev Lett ; 114(19): 192503, 2015 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-26024167

RESUMEN

New results are reported from a measurement of π^{0} electroproduction near threshold using the p(e,e^{'}p)π^{0} reaction. The experiment was designed to determine precisely the energy dependence of s- and p-wave electromagnetic multipoles as a stringent test of the predictions of chiral perturbation theory (ChPT). The data were taken with an electron beam energy of 1192 MeV using a two-spectrometer setup in Hall A at Jefferson Lab. For the first time, complete coverage of the ϕ_{π}^{*} and θ_{π}^{*} angles in the pπ^{0} center of mass was obtained for invariant energies above threshold from 0.5 up to 15 MeV. The 4-momentum transfer Q^{2} coverage ranges from 0.05 to 0.155 (GeV/c)^{2} in fine steps. A simple phenomenological analysis of our data shows strong disagreement with p-wave predictions from ChPT for Q^{2}>0.07 (GeV/c)^{2}, while the s-wave predictions are in reasonable agreement.

6.
Phys Rev Lett ; 113(23): 232505, 2014 Dec 05.
Artículo en Inglés | MEDLINE | ID: mdl-25526124

RESUMEN

We present a precise measurement of double-polarization asymmetries in the ^{3}He[over →](e[over →],e^{'}d) reaction. This particular process is a uniquely sensitive probe of hadron dynamics in ^{3}He and the structure of the underlying electromagnetic currents. The measurements have been performed in and around quasielastic kinematics at Q^{2}=0.25(GeV/c)^{2} for missing momenta up to 270 MeV/c. The asymmetries are in fair agreement with the state-of-the-art calculations in terms of their functional dependencies on p_{m} and ω, but are systematically offset. Beyond the region of the quasielastic peak, the discrepancies become even more pronounced. Thus, our measurements have been able to reveal deficiencies in the most sophisticated calculations of the three-body nuclear system, and indicate that further refinement in the treatment of their two-and/or three-body dynamics is required.

7.
Phys Rev Lett ; 113(2): 022002, 2014 Jul 11.
Artículo en Inglés | MEDLINE | ID: mdl-25062166

RESUMEN

Double-spin asymmetries and absolute cross sections were measured at large Bjorken x (0.25≤x≤0.90), in both the deep-inelastic and resonance regions, by scattering longitudinally polarized electrons at beam energies of 4.7 and 5.9 GeV from a transversely and longitudinally polarized (3)He target. In this dedicated experiment, the spin structure function g(2)((3)He) was determined with precision at large x, and the neutron twist-3 matrix element d(2)(n) was measured at ⟨Q(2)⟩ of 3.21 and 4.32 GeV(2)/c(2), with an absolute precision of about 10(-5). Our results are found to be in agreement with lattice QCD calculations and resolve the disagreement found with previous data at ⟨Q(2)⟩=5 GeV(2)/c(2). Combining d(2)(n) and a newly extracted twist-4 matrix element f(2)(n), the average neutron color electric and magnetic forces were extracted and found to be of opposite sign and about 30 MeV/fm in magnitude.

8.
Phys Rev Lett ; 113(2): 022502, 2014 Jul 11.
Artículo en Inglés | MEDLINE | ID: mdl-25062169

RESUMEN

We report the first measurement of the target-normal single-spin asymmetry in deep-inelastic scattering from the inclusive reaction 3)He(↑)(e,e')X on a polarized (3)He gas target. Assuming time-reversal invariance, this asymmetry is strictly zero in the Born approximation but can be nonzero if two-photon-exchange contributions are included. The experiment, conducted at Jefferson Lab using a 5.89 GeV electron beam, covers a range of 1.72 GeV, which is nonzero at the 2.89σ level. Our measured asymmetry agrees both in sign and magnitude with a two-photon-exchange model prediction that uses input from the Sivers transverse momentum distribution obtained from semi-inclusive deep-inelastic scattering.

9.
Phys Rev Lett ; 112(13): 132503, 2014 Apr 04.
Artículo en Inglés | MEDLINE | ID: mdl-24745410

RESUMEN

The charge form factor of 4He has been extracted in the range 29 fm(-2) ≤ Q2 ≤ 77 fm(-2) from elastic electron scattering, detecting 4He recoil nuclei and electrons in coincidence with the high resolution spectrometers of the Hall A Facility of Jefferson Lab. The measurements have uncovered a second diffraction minimum for the form factor, which was predicted in the Q2 range of this experiment. The data are in qualitative agreement with theoretical calculations based on realistic interactions and accurate methods to solve the few-body problem.

10.
Phys Rev Lett ; 111(8): 082501, 2013 Aug 23.
Artículo en Inglés | MEDLINE | ID: mdl-24016222

RESUMEN

We report on parity-violating asymmetries in the nucleon resonance region measured using inclusive inelastic scattering of 5-6 GeV longitudinally polarized electrons off an unpolarized deuterium target. These results are the first parity-violating asymmetry data in the resonance region beyond the Δ(1232). They provide a verification of quark-hadron duality-the equivalence of the quark- and hadron-based pictures of the nucleon-at the (10-15)% level in this electroweak observable, which is dominated by contributions from the nucleon electroweak γZ interference structure functions. In addition, the results provide constraints on nucleon resonance models relevant for calculating background corrections to elastic parity-violating electron scattering measurements.

11.
Cell Death Differ ; 20(11): 1465-74, 2013 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-23703322

RESUMEN

DNA damage induced by reactive oxygen species and several chemotherapeutic agents promotes both p53 and poly (ADP-ribose) polymerase (PARP) activation. p53 activation is well known to regulate apoptotic cell death, whereas robust activation of PARP-1 has been shown to promote a necrotic cell death associated with energetic collapse. Here we identify a novel role for p53 in modulating PARP enzymatic activity to regulate necrotic cell death. In mouse embryonic fibroblasts, human colorectal and human breast cancer cell lines, loss of p53 function promotes resistance to necrotic, PARP-mediated cell death. We therefore demonstrate that p53 can regulate both necrotic and apoptotic cell death, mutations or deletions in this tumor-suppressor protein may be selected by cancer cells to provide not only their resistance to apoptosis but also to necrosis, and explain resistance to chemotherapy and radiation even when it kills via non-apoptotic mechanisms.


Asunto(s)
Apoptosis/fisiología , Especies Reactivas de Oxígeno/metabolismo , Proteína p53 Supresora de Tumor/metabolismo , Muerte Celular/fisiología , Daño del ADN , Células HCT116 , Humanos , Peróxido de Hidrógeno/farmacología , Células MCF-7 , Mutación , Poli(ADP-Ribosa) Polimerasa-1 , Poli(ADP-Ribosa) Polimerasas/metabolismo
12.
Phys Rev Lett ; 108(10): 102001, 2012 Mar 09.
Artículo en Inglés | MEDLINE | ID: mdl-22468841

RESUMEN

The parity-violating cross-section asymmetry in the elastic scattering of polarized electrons from unpolarized protons has been measured at a four-momentum transfer squared Q2 = 0.624 GeV2 and beam energy E(b) = 3.48 GeV to be A(PV) = -23.80 ± 0.78(stat) ± 0.36(syst) parts per million. This result is consistent with zero contribution of strange quarks to the combination of electric and magnetic form factors G(E)(s) + 0.517G(M)(s) = 0.003 ± 0.010(stat) ± 0.004(syst) ± 0.009(ff), where the third error is due to the limits of precision on the electromagnetic form factors and radiative corrections. With this measurement, the world data on strange contributions to nucleon form factors are seen to be consistent with zero and not more than a few percent of the proton form factors.

13.
Phys Rev Lett ; 108(5): 052001, 2012 Feb 03.
Artículo en Inglés | MEDLINE | ID: mdl-22400926

RESUMEN

We report the first measurement of the double-spin asymmetry A{LT} for charged pion electroproduction in semi-inclusive deep-inelastic electron scattering on a transversely polarized {3}He target. The kinematics focused on the valence quark region, 0.16

14.
Phys Rev Lett ; 107(7): 072003, 2011 Aug 12.
Artículo en Inglés | MEDLINE | ID: mdl-21902386

RESUMEN

We report the first measurement of target single spin asymmetries in the semi-inclusive (3)He(e,e'π(±))X reaction on a transversely polarized target. The experiment, conducted at Jefferson Lab using a 5.9 GeV electron beam, covers a range of 0.16 < x < 0.35 with 1.4 < Q(2) < 2.7 GeV(2). The Collins and Sivers moments were extracted from the azimuthal angular dependence of the measured asymmetries. The π(±) Collins moments for (3)He are consistent with zero, except for the π(+) moment at x = 0.35, which deviates from zero by 2.3σ. While the π(-) Sivers moments are consistent with zero, the π(+) Sivers moments favor negative values. The neutron results were extracted using the nucleon effective polarization and measured cross section ratios of proton to (3)He, and are largely consistent with the predictions of phenomenological fits and quark model calculations.

15.
Indian J Pharmacol ; 42(6): 376-9, 2010 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-21189909

RESUMEN

BACKGROUNDS: This study was conducted to establish olanzapine-induced hepatopathy in Wistar albino rats as a newer model to screen putative hepatoprotective agents namely silymarin. MATERIALS AND METHODS: Albino rats were divided into three groups, namely vehicle control group (CG), olanzapine-treated group (OZ), and olanzapine plus silymarin (OZS) treated groups. Both the OZ and OZS groups were treated with the same dose of intraperitoneal olanzapine for 6 weeks and group OZS additionally received oral silymarin. Baseline and terminal hepatic enzymes (SGOT, SGPT, and ALP) were measured in all three groups. RESULTS: Histopathological examination of livers of both OZ and OZS groups showed degenerative changes, whereas those of control group showed normal architecture. Liver enzyme levels showed statistically significant rise in comparison to the control group as well as the respective base line values in both the test groups, but the differences in the rise of liver enzymes between the two test groups were not statistically significant. CONCLUSION: Olanzapine-induced hepatopathy in rats can be used as a model for screening putative hepatoprotective agents and in our setting silymarin has failed to provide any hepatoprotection.

16.
Sci Total Environ ; 408(20): 4744-8, 2010 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-20598738

RESUMEN

A novel and straight forward method is adopted to segregate the contribution of primary and secondary sources of formaldehyde based on the rates of its formation and removal at different times in the urban atmosphere of Kolkata. To achieve the above objective, the diurnal and seasonal mixing ratios of formaldehyde were measured during dry season at two busy roadside locations. The maximal secondary formation fluxes of formaldehyde during summer and winter were found to be 6.63 x 10(7) and 1.23 x 10(7) molecules cm(-3) s(-1), respectively. Apart from formaldehyde (C(1)), several other carbonyls were quantified in this study. An overall good correlation between acetaldehyde (C(2)) and propanal (C(3)) indicates the contribution of vehicular emission to the carbonyl budget. The secondary formaldehyde contributions in summer and winter were about 71% and 32%, respectively. The relative mean contributions of C(1), C(2) and ozone towards generation of OH fluxes in summer were found to be 1.56 x 10(7), 6.96 x 10(5), and 1.29 x 10(7)molecules cm(-3) s(-1), respectively, which were 3.2, 3.4 and 1.6 times higher than those in winter.


Asunto(s)
Contaminantes Atmosféricos/análisis , Atmósfera/química , Monitoreo del Ambiente , Formaldehído/análisis , 1-Propanol/análisis , Acetaldehído/análisis , Contaminación del Aire/estadística & datos numéricos , Radical Hidroxilo/análisis , India , Procesos Fotoquímicos , Estaciones del Año
17.
Phys Rev Lett ; 105(26): 262302, 2010 Dec 31.
Artículo en Inglés | MEDLINE | ID: mdl-21231649

RESUMEN

The electric form factor of the neutron was determined from studies of the reaction 3He(e,e'n)pp in quasielastic kinematics in Hall A at Jefferson Lab. Longitudinally polarized electrons were scattered off a polarized target in which the nuclear polarization was oriented perpendicular to the momentum transfer. The scattered electrons were detected in a magnetic spectrometer in coincidence with neutrons that were registered in a large-solid-angle detector. More than doubling the Q2 range over which it is known, we find G(E)(n)=0.0236±0.0017(stat)±0.0026(syst), 0.0208±0.0024±0.0019, and 0.0147±0.0020±0.0014 for Q(2)=1.72, 2.48, and 3.41 GeV2, respectively.

18.
Environ Monit Assess ; 148(1-4): 97-107, 2009 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-18219584

RESUMEN

Mixing ratios of 15 carbonyls and BTEX (benzene, toluene, ethyl benzene, xylenes) were measured for the first time in ambient air of Kolkata, India at three sites from March to June 2006 and their photochemical reactivity was evaluated. Day and nighttime samples were collected on weekly basis. Formaldehyde was the most abundant carbonyl (mean concentration ranging between 14.07 microg m(-3) to 26.12 microg m(-3) over the three sites) followed by acetaldehyde (7.60-18.67 microg m(-3)) and acetone (4.43-10.34 microg m(-3)). Among the high molecular weight aldehydes, nonanal showed the highest concentration. Among the mono-aromatic VOCs, mean concentration of toluene (27.65-103.31 microg m(-3)) was maximum, closely followed by benzene (24.97-79.18 microg m(-3)). Mean formaldehyde to acetaldehyde (1.4) and acetaldehyde to propanal ratios (5.0) were typical of urban air. Based on their photochemical reactivity towards OH. radical, the concentrations of the VOCs were scaled to formaldehyde equivalent, which showed that the high molecular weight carbonyls and xylenes contribute significantly to the total OH-reactive mass of the VOCs. Due to the toxic effect of the VOCs studied, an assessment for both cancer risk and non-cancer hazard due to exposure to the population were calculated. Integrated life time cancer risk (ILTCR) due to four carcinogens (benzene, ethyl benzene, formaldehyde and acetaldehyde) and non-cancer hazard index for the VOCs at their prevailing level were estimated to be 1.42E-04 and 5.6 respectively.


Asunto(s)
Contaminantes Atmosféricos/análisis , Aldehídos/análisis , Derivados del Benceno/análisis , Benceno/análisis , Compuestos Orgánicos Volátiles/análisis , Ciudades , Exposición a Riesgos Ambientales , Monitoreo del Ambiente/instrumentación , Monitoreo del Ambiente/métodos , Humanos , India , Exposición por Inhalación , Neoplasias/etiología , Fotoquímica , Medición de Riesgo , Estaciones del Año , Solventes/análisis , Salud Urbana
19.
Phys Rev Lett ; 99(20): 202002, 2007 Nov 16.
Artículo en Inglés | MEDLINE | ID: mdl-18233135

RESUMEN

High-precision measurements of the proton elastic form-factor ratio, mu pG p E/G p M, have been made at four-momentum transfer, Q2, values between 0.2 and 0.5 GeV2. The new data, while consistent with previous results, clearly show a ratio less than unity and significant differences from the central values of several recent phenomenological fits. By combining the new form-factor ratio data with an existing cross-section measurement, one finds that in this Q2 range the deviation from unity is primarily due to G p E being smaller than expected.

20.
Sci Total Environ ; 372(2-3): 426-32, 2007 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-17113131

RESUMEN

Commuters' exposure to volatile organic compounds (VOCs) especially BTEX travelling in passenger cars in Kolkata, India were quantified in Phase I (2001-2002) and Phase II (2003-2004). Monitoring was made inside and in the immediate outside of passenger cars fitted with and without catalytic converters using different types of fuels, along two congested urban routes. During Phase I of the study, the benzene content in gasoline was 5% and the mean concentration of in-vehicle benzene in cars without catalytic converter was found to be as high as 721.2 microg/m3. In Phase II when the benzene content was reduced to <3% and with modified engine type, the mean in-vehicle benzene concentration was reduced to 112.4 microg/m3. The in-vehicle concentration varied with engine type and age of the vehicle. Roadside ambient mean concentration of benzene was 214.8 microg/m3 and 30.8 microg/m3 in Phase I and Phase II respectively.


Asunto(s)
Contaminantes Atmosféricos/análisis , Contaminación del Aire Interior , Automóviles , Exposición a Riesgos Ambientales , Emisiones de Vehículos/análisis , Análisis de Varianza , Benceno/análisis , Derivados del Benceno/análisis , Ciudades , Humanos , India , Petróleo , Tolueno/análisis , Volatilización , Xilenos/análisis
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