611 research outputs found

    Validation of water flux and body composition in Glaucous gulls (Larus hyperboreus)

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    Water influx rates (WIR) measured with tritiated water dilution were compared with direct measures of water and energy intake in glaucous gulls (Larus hyperboreus). Total body water (TBW) measured isotopically was also compared with TBW determined by body composition analysis (BCA) of the same birds. Seventeen wild gulls were captured and studied in outdoor enclosures at Ny-Ålesund, Svalbard, in July 2002. Gulls were hand-fed known quantities of Arctic cod (Boreogadus saida) or given water on the basis of one of four experimental treatments: (A) fasting, (B) fish only, (C) water only, or (D) fish and water. Water and energy content of Arctic cod was also determined. WIR of gulls (after subtracting metabolic water production) in treatments A, B, C, and D were 0, 101 ± 5, 62 ± 19, and 122 ± 21 SD g d-1, respectively. Measured water intake in each group was 0, 111 ± 2, 64 ± 3, and 134 ± 15 SD g d-1, respectively. On average, WIR underestimated measured water intake in each group. Errors were lowest but most variable for gulls fed water only (-2.2% ± 32.8%) compared with gulls fed fish only (-9.0% ± 5.4%) or fish and water (-9.0% ± 7.0%). Compared with measured water intake, errors in WIR were relatively low overall (-6.9% ± 17.4%) and comparable to previous validation studies. The difference in TBW determined by BCA versus isotopic dilution ranged between -1.02% and +8.59% of mass. On average, TBW measured isotopically (632 ± 24 g kg-1) overestimated true body water by a factor of 1.033

    Decay Modes of Intersecting Fluxbranes

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    Just as the single fluxbrane is quantum mechanically unstable to the nucleation of a locally charged spherical brane, so intersecting fluxbranes are unstable to various decay modes. Each individual element of the intersection can decay via the nucleation of a spherical brane, but uncharged spheres can also be nucleated in the region of intersection. For special values of the fluxes, however, intersecting fluxbranes are supersymmetric, and so are expected to be stable. We explicitly consider the instanton describing the decay modes of the two--element intersection (an F5-brane in the string theory context), and show that in dimensions greater than four the action for the decay mode of the supersymmetric intersection diverges. This observation allows us to show that stable intersecting fluxbranes should also exist in type 0A string theory.Comment: 19 pages, 6 figures. References adde

    A New Cosmological Scenario in String Theory

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    We consider new cosmological solutions with a collapsing, an intermediate and an expanding phase. The boundary between the expanding (collapsing) phase and the intermediate phase is seen by comoving observers as a cosmological past (future) horizon. The solutions are naturally embedded in string and M-theory. In the particular case of a two-dimensional cosmology, space-time is flat with an identification under boost and translation transformations. We consider the corresponding string theory orbifold and calculate the modular invariant one-loop partition function. In this case there is a strong parallel with the BTZ black hole. The higher dimensional cosmologies have a time-like curvature singularity in the intermediate region. In some cases the string coupling can be made small throughout all of space-time but string corrections become important at the singularity. This happens where string winding modes become light which could resolve the singularity. The new proposed space-time casual structure could have implications for cosmology, independently of string theory.Comment: 28 pages, 3 figures; v2: Added new subsection relating two-dimensional model to BTZ black hole, typos corrected and references added; v3: minor corrections, PRD versio

    A small-scale hatchery for common carp

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    Gives comprehensive and well-illustrated techniques in comics format for establishing and maintaining an inexpensive hatchery for common carp, based on the techniques adopted in the common carp culture in Indonesia.Fish culture, Hatcheries, Extension material Cyprinidae

    Supergravity Solutions for BI Dyons

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    We construct partially localized supergravity counterpart solutions to the 1/2 supersymmetric non-threshold and the 1/4 supersymmetric threshold bound state BI dyons in the D3-brane Dirac-Born-Infeld theory. Such supergravity solutions have all the parameters of the BI dyons. By applying the IIA/IIB T-duality transformations to these supergravity solutions, we obtain the supergravity counterpart solutions to 1/2 and 1/4 supersymmetric BIons carrying electric and magnetic charges of the worldvolume U(1) gauge field in the Dirac-Born-Infeld theory in other dimensions.Comment: 17 pages, REVTeX, revised version to appear in Phys. Rev.

    Growing fish in pen systems

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    Describes and fully illustrates in comics format the techniques for growing fish in pen systems, adapted from the techniques developed for two important reservoirs in Indonesia.Fish culture, Cage culture, Extension material

    Culture of common carp in floating net cages

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    An illustrated manual in comics format on how to culture the common carp in floating cages. The techniques described were actually developed in the common carp culture in Bandung, Indonesia, and can be easily adapted to other sites.Carp culture, Cage culture, Floating cages, Extension material

    Interaction of Hawking radiation with static sources in deSitter and Schwarzschild-deSitter spacetimes

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    We study and look for similarities between the response rates RdS(a0,Λ)R^{\rm dS}(a_0, \Lambda) and RSdS(a0,Λ,M)R^{\rm SdS}(a_0, \Lambda, M) of a static scalar source with constant proper acceleration a0a_0 interacting with a massless, conformally coupled Klein-Gordon field in (i) deSitter spacetime, in the Euclidean vacuum, which describes a thermal flux of radiation emanating from the deSitter cosmological horizon, and in (ii) Schwarzschild-deSitter spacetime, in the Gibbons-Hawking vacuum, which describes thermal fluxes of radiation emanating from both the hole and the cosmological horizons, respectively, where Λ\Lambda is the cosmological constant and MM is the black hole mass. After performing the field quantization in each of the above spacetimes, we obtain the response rates at the tree level in terms of an infinite sum of zero-energy field modes possessing all possible angular momentum quantum numbers. In the case of deSitter spacetime, this formula is worked out and a closed, analytical form is obtained. In the case of Schwarzschild-deSitter spacetime such a closed formula could not be obtained, and a numerical analysis is performed. We conclude, in particular, that RdS(a0,Λ)R^{\rm dS}(a_0, \Lambda) and RSdS(a0,Λ,M)R^{\rm SdS}(a_0, \Lambda, M) do not coincide in general, but tend to each other when Λ→0\Lambda \to 0 or a0→∞a_0 \to \infty. Our results are also contrasted and shown to agree (in the proper limits) with related ones in the literature.Comment: ReVTeX4 file, 9 pages, 5 figure
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