12,965 research outputs found

    Radial Flow from Electromagnetic Probes and Signal of Quark Gluon Plasma

    Get PDF
    A first attempt has been made to extract the evolution of radial flow from the analysis of the experimental data on electromagnetic probes experimentally measured at SPS and RHIC energies. The pTp_T spectra of photons and dileptons measured by WA98 and NA60 collaborations respectively at CERN-SPS and the photon spectra obtained by PHENIX collaboration at BNL-RHIC have been used to constrain the theoretical models, rendering the outcome of the analysis largely model independent. We argue that the variation of the radial velocity with invariant mass is indicative of a phase transition from initially produced partons to hadrons at SPS and RHIC energies.Comment: One LaTeX and 9 eps files, to appear in Phys. Rev.

    Angular momentum evolution of young low-mass stars and brown dwarfs: observations and theory

    Full text link
    This chapter aims at providing the most complete review of both the emerging concepts and the latest observational results regarding the angular momentum evolution of young low-mass stars and brown dwarfs. In the time since Protostars & Planets V, there have been major developments in the availability of rotation period measurements at multiple ages and in different star-forming environments that are essential for testing theory. In parallel, substantial theoretical developments have been carried out in the last few years, including the physics of the star-disk interaction, numerical simulations of stellar winds, and the investigation of angular momentum transport processes in stellar interiors. This chapter reviews both the recent observational and theoretical advances that prompted the development of renewed angular momentum evolution models for cool stars and brown dwarfs. While the main observational trends of the rotational history of low mass objects seem to be accounted for by these new models, a number of critical open issues remain that are outlined in this review.Comment: 22 pages, 8 figures, accepted for publication in Protostars & Planets VI, 2014, University of Arizona Press, eds. H. Beuther, R. Klessen, K. Dullemond, Th. Hennin

    Data analysis of continuous gravitational wave: All sky search and study of templates

    Full text link
    We have studied the problem of all sky search in reference to continuous gravitational wave particularly for such sources whose wave-form are known in advance. We have made an analysis of the number of templates required for matched filter analysis as applicable to these sources. We have employed the concept of {\it fitting factor} {\it (FF)}; treating the source location as the parameters of the signal manifold and have studied the matching of the signal with templates corresponding to different source locations. We have investigated the variation of FF with source location and have noticed a symmetry in template parameters, θT\theta_T and ϕT\phi_T. It has been found that the two different template values in source location, each in θT\theta_T and ϕT\phi_T, have same {\it FF}. We have also computed the number of templates required assuming the noise power spectral density Sn(f)S_n(f) to be flat. It is observed that higher {\it FF} requires exponentially increasing large number of templates.Comment: Accepted in MNRAS, 14 pages, 5 figure

    A new approach to partial synchronization in globally coupled rotators

    Full text link
    We develop a formalism to analyze the behaviour of pulse--coupled identical phase oscillators with a specific attention devoted to the onset of partial synchronization. The method, which allows describing the dynamics both at the microscopic and macroscopic level, is introduced in a general context, but then the application to the dynamics of leaky integrate-and-fire (LIF) neurons is analysed. As a result, we derive a set of delayed equations describing exactly the LIF behaviour in the thermodynamic limit. We also investigate the weak coupling regime by means of a perturbative analysis, which reveals that the evolution rule reduces to a set of ordinary differential equations. Robustness and generality of the partial synchronization regime is finally tested both by adding noise and considering different force fields.Comment: 5 pages, 3 eps figure

    Sinuosity Dependency in Boundary Shear Distribution Modeling for Meandering Compound Channels

    Get PDF
    Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

    Certain seasonal characteristic features of oceanic heat budget components over the indian seas in relation to the summer monsoon activity over India

    Get PDF
    The present study has been undertaken to examine the oceanic heat budget components and their variability over the Indian seas in relation to the extreme monsoon activity (flood/drought) over the Indian subcontinent. For this purpose, various components of oceanic heat budget have been analysed for pre-monsoon (March-May), monsoon (June-September), post-monsoon (October-December) and winter (January-February) seasons over India. The data base used in this study consists of mean monthly marine meteorological fields for 30 years (1950-1979), which is a part of the Comprehensive Ocean Atmosphere Data Set (COADS) analysed at 1° latitude by 1° longitude resolution. The mean fields of incoming shortwave radiation flux over the Indian seas in different seasons vary in accordance to the sun's position and cloud cover variations. The latent heat flux undergoes considerable seasonal variations, particularly over the Arabian Sea. There is a dominance of latent heat flux (representing the oceanic heat loss) over shortwave solar flux (representing the oceanic heat gain) during the monsoon season, which results in a zone of net oceanic heat loss over the central Arabian Sea. This feature produces a positive feedback for the maintenance of deep cumulus convection over the Arabian Sea in this season. It is also found that oceanic heat budget components over the Indian seas exhibit significant variability in relation to the extreme monsoon activity leading to flood/drought over India. Based on the above analysis, mean monthly variations of the oceanic heat budget components over three smaller sectors of the Indian seas, namely west equatorial Indian Ocean, Arabian Sea and Bay of Bengal, are also examined. The variations are found to be considerably different between the two extreme categories of the monsoon. It becomes evident from this study that the oceanic sectors of west equatorial Indian Ocean and Bay of Bengal experience a large reduction of net heat flux from April to May prior to a flood monsoon season over India. This suggests that a spectacular increase of latent heat flux and decrease of shortwave flux occurs over these oceanic sectors, leading to a sharp reduction of net heat flux

    Polyaryl ethers and related polysiloxane copolymer molecular coatings preparation and radiation degrdation

    Get PDF
    Poly(arylene ether sulfones) comprise a class of materials known as engineering thermoplastics which have a variety of important applications. These polymers are tough, rigid materials with good mechanical properties over a wide temperature range, and they are processed by conventional methods into products typically having excellent hydrolytic, thermal, oxidative and dimensional stability. Wholly aromatic random copolymers of hydroquinone and biphenol with 4.4 prime dichlorodiphenyl sulfone were synthesized via mechanical nucleophilic displacement. Their structures were characterized and mechanical behavior studied. These tough, ductile copolymers show excellent radiation resistance to electron beam treatment and retain much of the mechanical properties up to at least 700 Mrads under argon

    Kaluza-Kleinov FRW kozmološki model s krutom tekućinom u Lyrinoj mnogostrukosti

    Get PDF
    In this paper we made an attempt to construct a five-dimensional FRW stiff fluid cosmological model in Lyra manifold. This model reduces to curvature-free (k=0) expanding stiff fluid cosmological model. Some physical and geometrical properties of the model are discussed.Pokušali smo ustrojiti pet-dimenzijski Friedmann-Robertson-Walker kozmološki model s krutom tekućinom u Lyrinoj mnogostrukosti. Taj se model svodi na kozmološki model bez zakrivljenosti (k = 0) s krutom tekućinom i širenjem. Raspravljaju se neka fizička i geometrijska svojstva modela
    corecore