413 research outputs found

    Kaluza-Klein Dark Matter and the Positron Excess

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    The excess of cosmic positrons observed by the HEAT experiment may be the result of Kaluza-Klein dark matter annihilating in the galactic halo. Kaluza-Klein dark matter annihilates dominantly into charged leptons that yield a large number and hard spectrum of positrons per annihilation. Given a Kaluza-Klein dark matter particle with a mass in the range of 300-400 GeV, no exceptional substructure or clumping is needed in the local distribution of dark matter to generate a positron flux that explains the HEAT observations. This is in contrast to supersymmetric dark matter that requires unnaturally large amounts of dark substructure to produce the observed positron excess. Future astrophysical and collider tests are outlined that will confirm or rule out this explanation of the HEAT data.Comment: 5 pages, 3 figures, REVTeX

    Recognizing the Fundamental Right to be Fat: A Weight-Inclusive Approach to Size Acceptance and Healing From Sizeism

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    This is the author accepted manuscript. The final version is available from Taylor & Francis (Routledge) via the DOI in this record.Sizeism permeates and shapes how scientific and professional communities—including therapists—perceive, understand, and behave toward anyone considered fat. In this article, we use scientific evidence to argue for the recognition and establishment of fat acceptance to subvert sizeism. We first critically review the Weight Normative Approach, which dominates scientific discourse on weight, despite being based on sizeist assumptions that are discredited by data. We then articulate the tenets of the Weight Inclusive Approach, which honors size diversity and the promotion of wellness within a social justice framework. We end with strategies for therapists to align their practice with the Weight Inclusive Approach

    On a Solar Origin for the Cosmogenic Nuclide Event of 775 A.D.

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    We explore requirements for a solar particle event (SPE) and flare capable of producing the cosmogenic nuclide event of 775 A.D., and review solar circumstances at that time. A solar source for 775 would require a greater than 1 GV spectrum approximately 45 times stronger than that of the intense high-energy SPE of 1956 February 23. This implies a greater than 30 MeV proton fluence (F(sub 30)) of approximately 8 10(exp 10) proton cm(exp 2), approximately 10 times larger than that of the strongest 3 month interval of SPE activity in the modern era. This inferred F(sub 30) value for the 775 SPE is inconsistent with the occurrence probability distribution for greater than 30 MeV solar proton events. The best guess value for the soft X-ray classification (total energy) of an associated flare is approximately X230 (approximately 9 10(exp 33) erg). For comparison, the flares on 2003 November 4 and 1859 September 1 had observed/inferred values of approximately X35 (approximately 10(exp 33) erg) and approximately X45 (approximately 2 10(exp 33) erg), respectively. The estimated size of the source active region for a approximately 10(exp 34) erg flare is approximately 2.5 times that of the largest region yet recorded. The 775 event occurred during a period of relatively low solar activity, with a peak smoothed amplitude about half that of the second half of the 20th century. The approximately 1945-1995 interval, the most active of the last approximately 2000 yr, failed to witness a SPE comparable to that required for the proposed solar event in 775. These considerations challenge a recent suggestion that the 775 event is likely of solar origin

    The Longitudinal Properties of a Solar Energetic Particle Event Investigated Using Modern Solar Imaging

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    We use combined high-cadence, high-resolution, and multi-point imaging by the Solar-Terrestrial Relations Observatory (STEREO) and the Solar and Heliospheric Observatory to investigate the hour-long eruption of a fast and wide coronal mass ejection (CME) on 2011 March 21 when the twin STEREO spacecraft were located beyond the solar limbs. We analyze the relation between the eruption of the CME, the evolution of an Extreme Ultraviolet (EUV) wave, and the onset of a solar energetic particle (SEP) event measured in situ by the STEREO and near-Earth orbiting spacecraft. Combined ultraviolet and white-light images of the lower corona reveal that in an initial CME lateral "expansion phase," the EUV disturbance tracks the laterally expanding flanks of the CME, both moving parallel to the solar surface with speeds of ~450 km s^(–1). When the lateral expansion of the ejecta ceases, the EUV disturbance carries on propagating parallel to the solar surface but devolves rapidly into a less coherent structure. Multi-point tracking of the CME leading edge and the effects of the launched compression waves (e.g., pushed streamers) give anti-sunward speeds that initially exceed 900 km s^(–1) at all measured position angles. We combine our analysis of ultraviolet and white-light images with a comprehensive study of the velocity dispersion of energetic particles measured in situ by particle detectors located at STEREO-A (STA) and first Lagrange point (L1), to demonstrate that the delayed solar particle release times at STA and L1 are consistent with the time required (30-40 minutes) for the CME to perturb the corona over a wide range of longitudes. This study finds an association between the longitudinal extent of the perturbed corona (in EUV and white light) and the longitudinal extent of the SEP event in the heliosphere

    Management of the Soybean Cyst Nematode by Using a Biorational Strategy

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    Analogs of glycinoclepin A have been shown to affect hatching of soybean cyst nematode cysts in laboratory conditions. Most analogs are hatch inhibitors. More complex bicyclic compounds may be hatch accelerators
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