41,550 research outputs found

    Sugar Maple Borer (Coleoptera: Cerambycidae) Activity Associated With Periods of Severe Defoliation

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    A perusal of previous research on sugar maple borer, Glycobius speciosus, in northern New York State strongly associates severe early and late season defoliation with increased borer damage. This re-examination of earlier work suggests foliage protection may be necessary when forest management objectives are concerned with wood volume and quality

    The Effect of Encounters on the Eccentricity of Binaries in Clusters

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    We derive analytical expressions for the change in the orbital eccentricity of a binary following a distant encounter with a third star on a hyperbolic or parabolic orbit. To establish the accuracy of these expressions, we present detailed comparisons with the results of direct numerical integrations of the equations of motion for the three bodies. We treat with particular care the difficult case of a binary with zero initial eccentricity. In this case, we show that the eccentricity δe\delta e induced by the encounter declines in general as a power-law, \delta e\propto (a/\rp)^{5/2}, where aa is the binary semi-major axis and \rp is the periastron distance of the encounter. This power-law arises from the octupole-level secular perturbation of the binary. In contrast, non-secular quadrupole-level perturbations induce an eccentricity change that declines exponentially with \rp. These non-secular effects can become dominant at sufficiently small \rp, for a sufficiently high relative velocity, or for a sufficiently massive perturber. We also derive cross sections for eccentricity change and compare our results with those of previous studies based on numerical scattering experiments. Our results have important implications for a number of astrophysical problems including, in particular, the evolution of binary millisecond pulsars in globular clusters.Comment: final version with minor revisions, uses MNRAS TeX macros, 23 pages, to appear in MNRAS, also available from http://ensor.mit.edu/~rasio/papers

    Interpreting Recoil For Undergraduate Students

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    In this paper, I outline some problems in the students' understanding of the explanation of recoil motion when introduced to them in the context of Newton's third law. I propose to explain the origin of recoil from a microscopic point of view, which emphasizes the exact mechanism leading to recoil. This mechanism differs from one system to another. Several examples that can be easily implemented in the classroom environment are given in this paper. Such a profound understanding of the origin of recoil help students avoid some of the misconceptions that might arise from the phenomenological approach, and stimulates their thinking in the fundamental origins of other physical phenomena.Comment: To Appear in The Physics Teacher Magazin

    Gypsy Moth (Lepidoptera: Lymantriidae) Feeding on Purple Loosestrife \u3ci\u3e(Lythrum Salicaria)\u3c/i\u3e in Michigan

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    Purple loosestrife, Lythrum salicaria, is an exotic invasive weed which is currently the target of a biological control effort using introduced leaf-feeding beetles. In 1997-1998 we observed larvae of the gypsy moth, Lymantria dispar feeding on L. salicaria at several locations in south central Michigan. In one-minute timed counts conducted over a six-week period in 1998, densities of 0 to 8 larvae per 1-m2 quadrat were observed. Other observations indicated 23 L. dispar 2nd and 3rd instars on a single L. salicaria plant. Second and third instar L. dispar collected on L. salicaria in the field were successfully reared to the adult stage in the lab on a diet of L. salicaria foliage. This is the first report of L. dispar feeding and development on L. salicaria. In areas where they co-occur, distinguishing L. dispar damage from that of introduced natural enemies will be important so that estimates of biocontrol agent impact are not biased

    A perturbation analysis of existing resonant satellites

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    Perturbation analysis of existing resonant satellite

    Brief of Amici Curiae Law and Economics Scholars in Support of Appellee and Affirmance

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    In reliance on Qualcomm’s FRAND promises, key SSOs incorporated its technologies into wireless standards. Qualcomm takes the position that its patented technologies are essential to those standards and, therefore, that any firm making or selling a standard-compliant product infringes its patents. As a result, the SSOs’ incorporation of Qualcomm’s patented technologies into wireless standards created a huge market for licenses to Qualcomm’s SEPs.The district court held that Qualcomm used its chipset monopolies, not only to extract the high chip-set prices to which it was entitled, but also to perpetuate those monopolies by disadvantaging rival chip-makers and raising entry barriers. As a matter of law and economics, that holding is sound. At its core, this is yet another in a long line of cases dating back to the Supreme Court’s decision in Standard Oil of New Jersey v. United States and United States v. American Telephone & Telegraph Co. in which a monopolist violates the antitrust laws by using its market power to exclude rivals and entrench its monopoly.We address Qualcomm’s exclusionary conduct in two Parts. Part I explains why Qualcomm’s no license, no chips policy is unlawful under well-established antitrust principles. Part II discusses Qualcomm’s refusal to license chip-set rivals, which reinforces the no license, no chips policy and violates the antitrust laws
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