12,166 research outputs found

    Actions for Biconformal Matter

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    We extend 2n-dim biconformal gauge theory by including Lorentz-scalar matter fields of arbitrary conformal weight. For a massless scalar field of conformal weight zero in a torsion-free biconformal geometry, the solution is determined by the Einstein equation on an n-dim submanifold, with the stress-energy tensor of the scalar field as source. The matter field satisfies the n-dim Klein-Gordon equation.Comment: 5 page

    Regional variation in the annual feeding cycle of juvenile walleye pollock (Theragra chalcogramma) in the western Gulf of Alaska

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    Juvenile fish in temperate coastal oceans exhibit an annual cycle of feeding, and within this cycle, poor wintertime feeding can reduce body growth, condition, and perhaps survival, especially in food-poor areas. We examined the stomach contents of juvenile walleye pollock (Theragra chalcogramma) to explain previously observed seasonal and regional variation in juvenile body condition. Juvenile walleye pollock (1732 fish, 37–250 mm standard length) of the 2000 year class were collected from three regions in the Gulf of Alaska (Kodiak, Semidi, and Shumagin) representing an area of the continental shelf of ca. 100,000 km2 during four seasons (August 2000 to September 2001). Mean stomach content weight (SCW, 0.72% somatic body weight) decreased with fish body length except from winter to summer 2001. Euphausiids composed 61% of SCW and were the main determinant of seasonal change in the diets of fish in the Kodiak and Semidi regions. Before and during winter, SCW and the euphausiid dietary component were highest in the Kodiak region. Bioenergetics modeling indicated a relatively high growth rate for Kodiak juveniles during winter (0.33 mm standard length/d). After winter, Shumagin juveniles had relatively high SCW and, unlike the Kodiak and Semidi juveniles, exhibited no reduction in the euphausiid dietary component. These patterns explain previous seasonal and regional differences in body condition. We hypothesize that high-quality feeding locations (and perhaps nursery areas) shift seasonally in response to the availability of euphausii

    Logic analysis of complex systems by characterizing failure phenomena to achieve diagnosis and fault-isolation

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    A recent result shows that, for a certain class of systems, the interdependency among the elements of such a system together with the elements constitutes a mathematical structure a partially ordered set. It is called a loop free logic model of the system. On the basis of an intrinsic property of the mathematical structure, a characterization of system component failure in terms of maximal subsets of bad test signals of the system was obtained. Also, as a consequence, information concerning the total number of failure components in the system was deduced. Detailed examples are given to show how to restructure real systems containing loops into loop free models for which the result is applicable

    Excess gamma-rays in the direction of the rho Ophiuchi cloud: An exotic object?

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    The COS-B X-ray data in the direction of the rho Oph dark cloud show an extended structure; at the same time, the region of highest intensity has a spatial distribution compatible with a localized source; 2CG353+16 which is designated Oph gamma. The possibility of an excess gamma ray flux over what is expected on the basis of the interaction of average density cosmic rays with an estimated cloud mass of 2 to 4 000 M is still open, pending an extended CO survey matching the gamma ray data. Estimates for this excess factor are in the range 2 to 4. While the cloud mass may be underestimated, it should be noted that an excess of the same order appears to be present in the nearby Oph-Sag area, well surveyed in CO with the Columbia dish. Possible reasons for a gamma ray excess, in view of two recent observational developments: an Einstein X-ray survey and a VLA radio survey, both covering the approx 2 deg diameter Oph gamma error box. Current interpretations link the gamma ray excess to the cloud gas, in which some active agent is present: stellar winds, or interaction with the North Polar Spur

    On the Stability Domain of Systems of Three Arbitrary Charges

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    We present results on the stability of quantum systems consisting of a negative charge q1-q_1 with mass m1m_{1} and two positive charges q2q_2 and q3q_3, with masses m2m_{2} and m3m_{3}, respectively. We show that, for given masses mim_{i}, each instability domain is convex in the plane of the variables (q1/q2,q1/q3)(q_{1}/q_{2}, q_{1}/q_{3}). A new proof is given of the instability of muonic ions (α,p,μ)(\alpha, p, \mu^-). We then study stability in some critical regimes where q3q2q_3\ll q_2: stability is sometimes restricted to large values of some mass ratios; the behaviour of the stability frontier is established to leading order in q3/q2q_3/q_2. Finally we present some conjectures about the shape of the stability domain, both for given masses and varying charges, and for given charges and varying masses.Comment: Latex, 24 pages, 14 figures (some in latex, some in .eps

    Technology’s Unlikely Application of the Art of War

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    The Art of War has become one of the most popular and influential texts of Chinese literature; it has found use beyond the military and strategic purposes similar to how the West has found use for it in business. What’s surprising, however, is that one can observe that technology itself was able to apply the Art of War in how it has become such a pervading force of everyday life today, with most of humankind today essentially relying on technology. This paper first tackles a number of related questions; afterwards, each chapter of the Art of War will be examined and analyzed to decipher how technology itself “applied” (or could not apply) the knowledge in that chapter

    Soft output bit error rate estimation for WCDMA

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    This paper introduces a method that computes an estimation of the bit error rate (BER) based on the RAKE receiver soft output only. For this method no knowledge is needed about the channel characteristics nor the precise external conditions. Simulations show that the mean error of the estimation is below 2%, with only a small variance. Implementation issues for a practical use of the method are discussed
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