908 resultados para dual polarization
Resumo:
Exclusive J/Psi electroproduction is studied in the framework of the analytic S-matrix theory. The differential and integrated elastic cross sections are calculated using the modified dual amplitude with Mandelstam analyticity model. The model is applied to the description of the available experimental data and proves to be valid in a wide region of the kinematical variables s, t, and Q(2). Our amplitude can be used also as a universal background parametrization for the extraction of tiny resonance signals.
Resumo:
A dual-Regge model with a nonlinear proton Regge trajectory in the missing mass (MX2) channel, describing the experimental data on low-mass single diffraction dissociation (SDD), is constructed. Predictions for the LHC energies are given.
Resumo:
A microscopic calculation of the residual particle-hole (p-h) interaction in spin-polarized 3He is performed. As a starting point the Brueckner G matrix is used which is supplemented by including the phonon exchange terms self-consistently. An important ingredient in this microscopic version of the induced interaction is the treatment of the full momentum dependence of the interaction. This allows a consistent description of the Landau limit (Pauli-principle sum rule for the Landau parameters is fulfilled) but also enables a detailed study of the p-h interaction at finite momentum transfers. A comparison with correlated basis functions results shows good agreement for momentum transfers larger than the Fermi momentum.
Resumo:
To determine self‐consistently the time evolution of particle size and their number density in situ multi‐angle polarization‐sensitive laser light scattering was used. Cross‐polarization intensities (incident and scattered light intensities with opposite polarization) measured at 135° and ex situ transmission electronic microscopy analysis demonstrate the existence of nonspherical agglomerates during the early phase of agglomeration. Later in the particle time development both techniques reveal spherical particles again. The presence of strong cross‐polarization intensities is accompanied by low‐frequency instabilities detected on the scattered light intensities and plasma emission. It is found that the particle radius and particle number density during the agglomeration phase can be well described by the Brownian free molecule coagulation model. Application of this neutral particle coagulation model is justified by calculation of the particle charge whereby it is shown that particles of a few tens of nanometer can be considered as neutral under our experimental conditions. The measured particle dispersion can be well described by a Brownian free molecule coagulation model including a log‐normal particle size distribution.
Resumo:
Methods for generating beams with arbitrary polarization based on the use of liquid crystal displays have recently attracted interest from a wide range of sources. In this paper we present a technique for generating beams with arbitrary polarization and shape distributions at a given plane using a Mach-Zehnder setup. The transverse components of the incident beam are processed independently by means of spatial light modulators placed in each path of the interferometer. The modulators display computer generated holograms designed to dynamically encode any amplitude value and polarization state for each point of the wavefront in a given plane. The steps required to design such beams are described in detail. Several beams performing different polarization and intensity landscapes have been experimentally implemented. The results obtained demonstrate the capability of the proposed technique to tailor the amplitude and polarization of the beam simultaneously.
Resumo:
After an injury, keratinocytes acquire the plasticity necessary for the reepithelialization of the wound. Here, we identify a novel pathway by which a nuclear hormone receptor, until now better known for its metabolic functions, potentiates cell migration. We show that peroxisome proliferator-activated receptor beta/delta (PPARbeta/delta) enhances two phosphatidylinositol 3-kinase-dependent pathways, namely, the Akt and the Rho-GTPase pathways. This PPARbeta/delta activity amplifies the response of keratinocytes to a chemotactic signal, promotes integrin recycling and remodeling of the actin cytoskeleton, and thereby favors cell migration. Using three-dimensional wound reconstructions, we demonstrate that these defects have a strong impact on in vivo skin healing, since PPARbeta/delta-/- mice show an unexpected and rare epithelialization phenotype. Our findings demonstrate that nuclear hormone receptors not only regulate intercellular communication at the organism level but also participate in cell responses to a chemotactic signal. The implications of our findings may be far-reaching, considering that the mechanisms described here are important in many physiological and pathological situations.
Resumo:
Tumor progression is facilitated by regulatory T cells (Treg) and restricted by effector T cells. In this study, we document parallel regulation of CD8(+) T cells and Foxp3(+) Tregs by programmed death-1 (PD-1, PDCD1). In addition, we identify an additional role of CTL antigen-4 (CTLA-4) inhibitory receptor in further promoting dysfunction of CD8(+) T effector cells in tumor models (CT26 colon carcinoma and ID8-VEGF ovarian carcinoma). Two thirds of CD8(+) tumor-infiltrating lymphocytes (TIL) expressed PD-1, whereas one third to half of CD8(+) TIL coexpressed PD-1 and CTLA-4. Double-positive (PD-1(+)CTLA-4(+)) CD8(+) TIL had characteristics of more severe dysfunction than single-positive (PD-1(+) or CTLA-4(+)) TIL, including an inability to proliferate and secrete effector cytokines. Blockade of both PD-1 and CTLA-4 resulted in reversal of CD8(+) TIL dysfunction and led to tumor rejection in two thirds of mice. Double blockade was associated with increased proliferation of antigen-specific effector CD8(+) and CD4(+) T cells, antigen-specific cytokine release, inhibition of suppressive functions of Tregs, and upregulation of key signaling molecules critical for T-cell function. When used in combination with GVAX vaccination (consisting of granulocyte macrophage colony-stimulating factor-expressing irradiated tumor cells), inhibitory pathway blockade induced rejection of CT26 tumors in 100% of mice and ID8-VEGF tumors in 75% of mice. Our study indicates that PD-1 signaling in tumors is required for both suppressing effector T cells and maintaining tumor Tregs, and that PD-1/PD-L1 pathway (CD274) blockade augments tumor inhibition by increasing effector T-cell activity, thereby attenuating Treg suppression. Cancer Res; 73(12); 3591-603. ©2013 AACR.
Resumo:
Peripheral assessment of bone density using photon absorptiometry techniques has been available for over 40 yr. The initial use of radio-isotopes as the photon source has been replaced by the use of X-ray technology. A wide variety of models of single- or dual-energy X-ray measurement tools have been made available for purchase, although not all are still commercially available. The Official Positions of the International Society for Clinical Densitometry (ISCD) have been developed following a systematic review of the literature by an ISCD task force and a subsequent Position Development Conference. These cover the technological diversity among peripheral dual-energy X-ray absorptiometry (pDXA) devices; define whether pDXA can be used for fracture risk assessment and/or to diagnose osteoporosis; examine whether pDXA can be used to initiate treatment and/or monitor treatment; provide recommendations for pDXA reporting; and review quality assurance and quality control necessary for effective use of pDXA.
Resumo:
We study the sensitivity limits of a broadband gravitational-wave detector based on dual resonators such as nested spheres. We determine both the thermal and back-action noises when the resonators displacements are read out with an optomechanical sensor. We analyze the contributions of all mechanical modes, using a new method to deal with the force-displacement transfer functions in the intermediate frequency domain between the two gravitational-wave sensitive modes associated with each resonator. This method gives an accurate estimate of the mechanical response, together with an evaluation of the estimate error. We show that very high sensitivities can be reached on a wide frequency band for realistic parameters in the case of a dual-sphere detector.
Resumo:
We present the concept of a sensitive and broadband resonant mass gravitational wave detector. A massive sphere is suspended inside a second hollow one. Short, high-finesse Fabry-Perot optical cavities read out the differential displacements of the two spheres as their quadrupole modes are excited. At cryogenic temperatures, one approaches the standard quantum limit for broadband operation with reasonable choices for the cavity finesses and the intracavity light power. A molybdenum detector, of overall size of 2 m, would reach spectral strain sensitivities of 2x10-23Hz-1/2 between 1000 and 3000 Hz.
Resumo:
The Iowa Division of Criminal and Juvenile Justice Planning recently released a report summarizing its evaluation of the Dual Diagnosis Offender Program (DDOP) administered by the First Judicial District Department of Correctional Services.
Resumo:
Introduction: Growth is a central process in paediatrics. Weight and height evaluation are therefore routine exams for every child but in some situation, particularly inflammatory bowel disease (IBD), a wider evaluation of nutritional status needs to be performed. Objectives: To assess the accuracy of bio-impedance analysis (BIA) compared to the gold standard dual energy X-ray absorptiometry (DEXA) in estimating percentage body fat (fat mass; FM) and lean body mass (fat free mass; FFM) in children with inflammatory bowel disease (IBD). To compare FM and FFM levels between patients with IBD and healthy controls. Methods: Twenty-nine healthy controls (12 females; mean age: 12.7 ± 1.9 years) and 21 patients (11 females; 14.3 ± 1.3 years) were recruited from August 2011 to October 2012 at our institution. BIA was performed in all children and DEXA in patients only. Concordance between BIA and DEXA was assessed using Lin's concordance correlation and the Bland-Altman method. Between-group comparisons were made using analysis of variance adjusting for age. Results: BIA-derived FM% showed a good concordance with DEXA-derived values, while BIA-derived FFM% tended to be slightly higher than DEXA-derived values (table). No differences were found between patients and controls regarding body mass index (mean ± SD: 19.3 ± 3.3 vs. 20.1 ± 2.8 kg/m2, respectively; age-adjusted P = 0.08) and FM% (boys: 25.3 ± 10.2 vs. 22.6 ± 7.1%, for patients and controls, respectively; P = 0.20; girls: 28.2 ± 5.7 vs. 26.4 ± 7.7%; P = 0.91). Also, no differences were found regarding FFM% in boys (74.9 ± 10.2 vs. 77.4 ± 7.1%; P = 0.22) and girls (71.8 ± 5.6 vs. 73.5 ± 7.7%; P = 0.85). Conclusion: BIA adequately assesses body composition (FM%) in children with IBD and could advantageously replace DEXA, which is more expensive and less available. No differences in body composition were found between children with IBD and healthy controls.
Resumo:
Phosphopeptides tagging reactions by dinuclear zinc(II) complexes (1,3-bis[bis(2-pyridylmethyl)amino]-propan-2-olato dizinc(II)3+, called tag) were performed with a dual-channel microsprayer in electrospray ionization mass spectrometry. The reaction is first studied ex situ and analyzed with a commercial electrospray source. In situ reactions (i.e., inside the Taylor cone) were achieved with a dual-channel microsprayer both with the tag synthesized chemically before the experiments and with the tag electrogenerated by in situ oxidation of a zinc electrode, also used to apply the electrospray current. The device consists of a polyimide microchip with two microchannels (20 microm x 50 microm x 1 cm) etched on each side of the structure and connecting only at the tip of the microchip. We demonstrate here that mixing two solutions with different physicochemical properties inside the Taylor cone can be used to selectively tag target molecules.