15,827 research outputs found
Integral points on elliptic curves and explicit valuations of division polynomials
Assuming Lang's conjectured lower bound on the heights of non-torsion points
on an elliptic curve, we show that there exists an absolute constant C such
that for any elliptic curve E/Q and non-torsion point P in E(Q), there is at
most one integral multiple [n]P such that n > C. The proof is a modification of
a proof of Ingram giving an unconditional but not uniform bound. The new
ingredient is a collection of explicit formulae for the sequence of valuations
of the division polynomials. For P of non-singular reduction, such sequences
are already well described in most cases, but for P of singular reduction, we
are led to define a new class of sequences called elliptic troublemaker
sequences, which measure the failure of the Neron local height to be quadratic.
As a corollary in the spirit of a conjecture of Lang and Hall, we obtain a
uniform upper bound on h(P)/h(E) for integer points having two large integral
multiples.Comment: 41 pages; minor corrections and improvements to expositio
Inequalities for electron-field correlation functions
I show that there exists a class of inequalities between correlation
functions of different orders of a chaotic electron field. These inequalities
lead to the antibunching effect and are a consequence of the fact that
electrons are fermions -- indistinguishable particles with antisymmetric
states. The derivation of the inequalities is based on the known form of the
correlation functions for the chaotic state and on the properties of matrices
and determinants.Comment: 8 pages Latex2e, 2 eps figure
Study of explosions in the NASA-MSC Vibration and Acoustic Test Facility /VATF/ Final report
Damage potential of titanium alloy pressure spheres relative to spacecraft vibration testin
Spatial Corrections of ROSAT HRI Observations
X-ray observations with the ROSAT High Resolution Imager (HRI) often have
spatial smearing on the order of 10 arcsec (Morse 1994). This degradation of
the intrinsic resolution of the instrument (5 arcsec) can be attributed to
errors in the aspect solution associated with the wobble of the space craft or
with the reacquisition of the guide stars. We have developed a set of IRAF/PROS
and MIDAS/EXSAS routines to minimize these effects. Our procedure attempts to
isolate aspect errors that are repeated through each cycle of the wobble. The
method assigns a 'wobble phase' to each event based on the 402 second period of
the ROSAT wobble. The observation is grouped into a number of phase bins and a
centroid is calculated for each sub-image. The corrected HRI event list is
reconstructed by adding the sub-images which have been shifted to a common
source position. This method has shown approx. 30% reduction of the full width
half maximum (FWHM) of an X-ray observation of the radio galaxy 3C 120.
Additional examples are presented.Comment: AandA latex (6 pages with 7 embedded postscript figures). Scheduled
for publication in the 1 Dec issue of Astron. Astrophys. Suppl. Serie
Correlation Functions and Spin
The k-electron correlation function of a free chaotic electron beam is
derived with the spin degree of freedom taken into account. It is shown that it
can be expressed with the help of correlation functions for a polarized
electron beam of all orders up to k and the degree of spin polarization. The
form of the correlation function suggests that if the electron beam is not
highly polarized, observing multi-particle correlations should be difficult.
The result can be applied also to chaotic photon beams, the degree of spin
polarization being replaced by the degree of polarization.Comment: 6 pages, 1 eps figure, accepted to Phys. Rev.
The Effects of Negative Legacies on the Adjustment of Parentally Bereaved Children and Adolescents
This is a report of a qualitative analysis of a sample of bereaved families in which one parent died and in which children scored in the clinical range on the Child Behavior Check List. The purpose of this analysis was to learn more about the lives of these children. They were considered to be at risk of developing emotional and behavioral problems associated with the death. We discovered that many of these “high risk” children had a continuing bond with the deceased that was primarily negative and troubling for them in contrast to a comparison group of children not at risk from the same study. Five types of legacies, not mutually exclusive, were identified: health related, role related, personal qualities, legacy of blame, and an emotional legacy. Coping behavior on the part of the surviving parent seemed to make a difference in whether or not a legacy was experienced as negative
The Case for Flexible Intellectual Property Protections in the Trans-Pacific Partnership
The United States and eleven other countries are currently in the end stages of negotiating the Trans-Pacific Partnership (TPP)—the largest free trade agreement (FTA) in U.S. history—which incorporates a range of trade topics, including the protection and enforcement of intellectual property rights (IPRs). Although the negotiations have been highly secretive, negotiating texts of the agreement leaked as recently as November 2013 have suggested that the United States is proposing IPR provisions, specifically relating to patent protection, that are stronger and less flexible than IPR provisions included within three of the four most recent U.S. FTAs. This paper addresses and analyzes these leaked IPR provisions and makes the argument that in the best interest of global welfare and public-health policy, the United States should not be attempting to incorporate stronger IPR protections in the TPP.
Section 1 provides an introduction to the TRIPS agreement—the first international agreement to set minimum standards for the protection and enforcement of IPRs—and discusses the significance of the “Doha Declaration” in helping to clarify the need to interpret TRIPS from a public-health perspective. Section 2 describes the recent U.S. trend of seeking levels of IPR protection in its FTAs that exceed the minimum standards of TRIPS (referred to as “TRIPS-plus” provisions)—including patent term extensions, patent linkages, and enhanced data protection, as detailed in Section 3 of this paper. Section 4 describes the Bipartisan Trade Deal (BTD) of May 10, 2007, as an attempt by members of Congress to address concerns about the effect that these enhanced IPR protections have on developing countries’ ability to access life-saving medicines. Section 5 outlines the leaked U.S. TPP proposals relating to patent term extensions, patent linkages and data protection, and describes how they will impede TPP countries from gaining access to medicines. In order to better understand the issues and arguments that are at stake from both sides, Section 6 provides the arguments commonly put forth as to why strong patent protection is necessary, while Section 7 examines the significance of generic medicines being accessible in the global marketplace. Section 8 analyzes these arguments and draws the conclusion that, while patent protection of pharmaceuticals is important, it must be fairly balanced against the needs of the developing world to be able to access affordable, life-saving medicines. In conclusion, this paper puts forth the argument that the United States should honor its existing global-health commitments by seeking flexible IPR standards in the TPP to ensure that the health interests of the poorest and sickest people in the developing world are not undermined by the profit-maximizing interests of pharmaceutical companies
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