The quark strange star in the enlarged Nambu-Jona-Lasinio model

The strange quark star is investigated within the enlarged SU(3) Nambu-Jona-Lasinio (NJL). The stable quark star exists till maximal configutation with rho_m=3.1, 10^15, g/cm^3 with M_m=1.61, M_Sun and R_m=8.74, km is reached. Strange quarks appear for density above rho_c=9.84 g/cm^3 for the quark star with radius R_c=8.003 km and M_c=0.77, M_Sun. The comparison of a quark star properties obtained in the Quark Mean Field (QMF) approach to a neutron star model constructed within the Relativistic Mean Field (RMF) theory is presented.Comment: 23 pages, iop latex2e + hyperref, 11 figures, to appear in NJ

Photon-Photon Absorption of Very High Energy Gamma-Rays from Microquasars: Application to LS 5039

Very high energy (VHE) gamma-rays have recently been detected from the Galactic black-hole candidate and microquasar LS 5039. A plausible site for the production of these VHE gamma-rays is the region close to the mildly relativistic outflow. However, at distances comparable to the binary separation, the intense photon field of the stellar companion will lead to substantial gamma-gamma absorption of VHE gamma-rays. If the system is viewed at a substantial inclination (i > 0), this absorption feature will be modulated on the orbital period of the binary as a result of a phase-dependent stellar-radiation intensity and pair-production threshold. We apply our results to LS 5039 and find that (1) gamma-gamma absorption effects will be substantial if the photon production site is located at a distance from the central compact object of the order of the binary separation (~ 2.5e12 cm) or less; (2) the gamma-gamma absorption depth will be largest at a few hundred GeV, leading to a characteristic absorption trough; (3) the gamma-gamma absorption feature will be strongly modulated on the orbital period of the binary, characterized by a spectral hardening accompanying periodic dips of the VHE gamma-ray flux; and (4) gamma rays can escape virtually unabsorbed, even from within ~ 10^{12} cm, when the star is located behind the production site as seen by the observer.Comment: Submitted to ApJ Letters. AASTeX, 12 ms pages, including 4 eps figure

Gated combo nanodevice for sequential operations on single electron spin

An idea for a nanodevice in which an arbitrary sequence of three basic quantum single qubit gates - negation, Hadamard and phase shift - can be performed on a single electron spin. The spin state is manipulated using the spin-orbit coupling and the electron trajectory is controlled by the electron wave function self-focusing mechanism due to the electron interaction with the charge induced on metal gates. We present results of simulations based on iterative solution of the time dependent Schr\"odinger equation in which the subsequent operations on the electron spin can be followed and controlled. Description of the moving electron wave packet requires evaluation of the electric field within the entire nanodevice in each time step

Occurrence of the neotropical moss Dicranella hilariana (Mont.) Mitt. in the Antarctic

Dicranella hilariana (Mont.) Mitt., a pan-neotropical moss species, is reported for the first time from the Antarctic botanical zone. It was found on geothermally heated ground near fumaroles on Visokoi, Candlemas and Bellingshausen Islands in the volcanic archipelago of the South Sandwich Islands. Dicranella recurvata Ochyra, Arts & Lewis-Smith, nom. nud., is reduced to synonymy with D. hilariana. The Antarctic plants of D. hilariana are briefly described and illustrated, including the rhizoidal tubers which have not previously been reported in this species. The global distribution of D. hilariana is briefly reviewed and mapped. It is suggested that the species reached the Antarctic via long-distance dispersal from South America by the prevailing strong westerly winds

Hyperons in neutron-star cores and two-solar-mass pulsar

Recent measurement of mass of PSR J1614-2230 rules out most of existing models of equation of state (EOS) of dense matter with high-density softening due to hyperonization or a phase transition to quark matter or a boson condensate. We look for a solution of an apparent contradiction between the consequences stemming from up-to-date hypernuclear data, indicating appearance of hyperons at 3 nuclear densities and existence of a two-solar-mass neutron star. We consider a non-linear relativistic mean field (RMF) model involving baryon octet coupled to meson fields. An effective lagrangian includes quartic terms in the meson fields. The values of the parameters of the model are obtained by fitting semi-empirical parameters of nuclear matter at the saturation point, as well as potential wells for hyperons in nuclear matter and the strength of the Lambda-Lambda attraction in double-Lambda hypernuclei. We propose a non-linear RMF model which is consistent with up-to-date semiempirical nuclear and hypernuclear data and allows for neutron stars with hyperon cores and M larger than 2 solar masses. The model involves hidden-strangenes scalar and vector mesons, coupled to hyperons only, and quartic terms involving vector meson fields. Our EOS involving hyperons is stiffer than the corresponding nucleonic EOS (with hyperons artificially suppressed) above five nuclear densities. Required stiffening is generated by the quartic terms involving hidden-strangeness vector meson.Comment: 7 pages, 5 figures. Main results of this paper were already presented at the MODE-SNR-PWN Workshop in Bordeaux, France, November 15-17, 2010, and in a poster at the CompStar 2011 Workshop in Catania, Italy, May 9-12, 2011. The paper is being submitted to Astronomy & Astrophysic