9,258 research outputs found

    Differential efficacies of human type I and type II interferons as antiviral and antiproliferative agents.

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    Mutual insurance of transport infrastructure construction risks as an inherent part of competitive environment

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    In this article we introduce mutual insurance as an inherent part of competitive environment in the field of insurance of the transport infrastructure construction risks. The competitive environment makes a great impact on the market behavior of the actors. The monopolization creates the environment, which does not prevent the negative steps of the firm in different directions. The article shows, that mutual insurance is a significant factor which can prevent the monopolization of the insurance market. This is a specific factor that is inherent only to this kind of the market. The competitive advantages of the mutual insurance organizations, their attractiveness to the clients (the insured) are conditioned with the specific relations between the insured and the insurance organization, such as the decision of the main questions of the financial activity of the insurer on the meeting of all the insured or their representatives, the possibility to insure the risks, which the commercial insurers do not insure and some others.peer-reviewe

    Fermionic and Bosonic Stabilizing Effects for Type I and Type II Dimension Bubbles

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    We consider two types of "dimension bubbles", which are viewed as 4d nontopological solitons that emerge from a 5d theory with a compact extra dimension. The size of the extra dimension varies rapidly within the domain wall of the soliton. We consider the cases of type I (II) bubbles where the size of the extra dimension inside the bubble is much larger (smaller) than outside. Type I bubbles with thin domain walls can be stabilized by the entrapment of various particle modes whose masses become much smaller inside than outside the bubble. This is demonstrated here for the cases of scalar bosons, fermions, and massive vector bosons, including both Kaluza-Klein zero modes and Kaluza-Klein excitation modes. Type II bubbles expel massive particle modes but both types can be stabilized by photons. Plasma filled bubbles containing a variety of massless or nearly massless radiation modes may exist as long-lived metastable states. Furthermore, in contrast to the case with a "gravitational bag", the metric for a fluid-filled dimension bubble does not exhibit a naked singularity at the bubble's center.Comment: 17 pages, no figs; to appear in Phys.Rev.

    Onsager coefficients of a Brownian Carnot cycle

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    We study a Brownian Carnot cycle introduced by T. Schmiedl and U. Seifert [Europhys. Lett. \textbf{81}, 20003 (2008)] from a viewpoint of the linear irreversible thermodynamics. By considering the entropy production rate of this cycle, we can determine thermodynamic forces and fluxes of the cycle and calculate the Onsager coefficients for general protocols, that is, arbitrary schedules to change the potential confining the Brownian particle. We show that these Onsager coefficients contain the information of the protocol shape and they satisfy the tight-coupling condition irrespective of whatever protocol shape we choose. These properties may give an explanation why the Curzon-Ahlborn efficiency often appears in the finite-time heat engines

    Gravity with extra dimensions and dark matter interpretation: Phenomenological example via Miyamoto-Nagai galaxy

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    A configuration whose density profile coincides with the Newtonian potential for spiral galaxies is constructed from a 4D isotropic metric plus extra dimensional components. A Miyamoto-Nagai ansatz is used to solve Einstein equations. The stable rotation curves of such system are computed and, without fitting techniques, we recover with accuracy the observational data for flat or not asymptotically flat galaxy rotation curves. The density profiles are reconstructed and compared to that obtained from the Newtonian potential.Comment: 10 pages, 10 figures, submitted to Brazilian Journal of Physic

    The European fruit lecanium, Lecanium tiliae (L.) (Homoptera: Coccidae), in southwestern British Columbia

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    Lecanium tiliae normally has one annual generation in southwestern British Columbia. There was a partial second in a year following a mild winter. The heaviest infestations were on horse chestnut, Japanese plum, hawthorn, and maple, in that order. Hawthorn was damaged. The proportion of males tended to be higher in high than in low populations, and to decrease with increasing altitude. Severe winter cold caused marked population decreases and cold weather in June noticeable decreases. Natural enemies found in 1969-72 are listed

    A Sequence of Declining Outbursts from GX339-4

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    The flux and spectrum of the black hole candidate GX339-4 has been monitored by the Burst and Transient Source Experiment (BATSE) on the Compton Gamma-ray Observatory (CGRO) since the observatory became operational in May 1991. Between the summer of 1991 and the fall of 1996, eight outbursts from GX339-4 were observed. The history of these outbursts is one of declining fluence or total energy release, as well as a shortening of the time between outbursts. A rough linear correlation exists between the fluence emitted during an outburst and the time elapsed between the end of the previous outburst and the beginning of the current one. The peak flux is also roughly linearly correlated with outburst fluence. The lightcurves of the earlier, more intense, outbursts (except for the second one) can be modeled by a fast exponential (time constant ~ 10 days) followed by a slower exponential (~ 100 days) on the rise and a fast exponential decay (~ 5 days) on the fall. The later, weaker, outbursts are modeled with a single rising time constant (~ 20 days) and a longer decay on the fall (~ 50 days). An exponential model gives a marginally better fit than a power law to the rise/decay profiles. GX339-4 is a unique source in having more frequent outbursts than other low mass x-ray binary black hole candidates. These observations can be used to constrain models of the behavior of the accretion disk surrounding the compact object.Comment: Accepted for Publication in the Astrophysical Journal Letters, AASTE

    Two-Photon Entanglement and EPR Experiments Using Type-2 Spontaneous Parametric Down Conversion

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    Simultaneous entanglement in spin and space-time of a two-photon quantum state generated in type-2 spontaneous parametric down-conversion is demonstrated by the observation of quantum interference with 98% visibility in a simple beam-splitter (Hanburry Brown-Twiss) anticorrelation experiment. The nonlocal cancellation of two-photon probability amplitudes as a result of this double entanglement allows us to demonstrate two different types of Bell's inequality violations in one experimental setup

    Demonstration of Non-Deterministic Quantum Logic Operations using Linear Optical Elements

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    Knill, Laflamme, and Milburn recently showed that non-deterministic quantum logic operations could be performed using linear optical elements, additional photons (ancilla), and post-selection based on the output of single-photon detectors [Nature 409, 46 (2001)]. Here we report the experimental demonstration of two logic devices of this kind, a destructive controlled-NOT (CNOT) gate and a quantum parity check. These two devices can be combined with a pair of entangled photons to implement a conventional (non-destructive) CNOT that succeeds with a probability of 1/4.Comment: 4 pages, 5 figures; Minor change

    Separate Universes Do Not Constrain Primordial Black Hole Formation

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    Carr and Hawking showed that the proper size of a spherical overdense region surrounded by a flat FRW universe cannot be arbitrarily large as otherwise the region would close up on itself and become a separate universe. From this result they derived a condition connecting size and density of the overdense region ensuring that it is part of our universe. Carr used this condition to obtain an upper bound for the density fluctuation amplitude with the property that for smaller amplitudes the formation of a primordial black hole is possible, while larger ones indicate a separate universe. In contrast, we find that the appearance of a maximum is not a consequence of avoiding separate universes but arises naturally from the geometry of the chosen slicing. Using instead of density a volume fluctuation variable reveals that a fluctuation is a separate universe iff this variable diverges on superhorizon scales. Hence Carr's and Hawking's condition does not pose a physical constraint on density fluctuations. The dynamics of primordial black hole formation with an initial curvature fluctuation amplitude larger than the one corresponding to the maximum density fluctuation amplitude was previously not considered in detail and so we compare it to the well-known case where the amplitude is smaller by presenting embedding and conformal diagrams of both types in dust spacetimes.Comment: Updated version corresponds to the published version 10.1103/PhysRevD.83.124025, 22 pages, 22 figure
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