Can Supersymmetry Naturally Explain the Positron Excess?

It has often been suggested that the cosmic positron excess observed by the HEAT experiment could be the consequence of supersymmetric dark matter annihilating in the galactic halo. Although it is well known that evenly distributed dark matter cannot account for the observed excess, if substantial amounts of local dark matter substructure are present, the positron flux would be enhanced, perhaps to the observed magnitude. In this paper, we attempt to identify the nature of the substructure required to match the HEAT data, including the location, size and density of any local dark matter clump(s). Additionally, we attempt to assess the probability of such substructure being present. We find that if the current density of neutralino dark matter is the result of thermal production, very unlikely ($\sim 10^{-4}$ or less) conditions must be present in local substructure to account for the observed excess.Comment: Version accepted by Physical Review

Chemiluminescent Tags for Tracking Insect Movement in Darkness: Application to Moth Photo-Orientation

The flight tracks of Manduca sexta (Lepidoptera: Sphingidae) flying toward a 5 watt incandescent light bulb were recorded under low light conditions with the aid of a camera-mounted photomultiplier and a glowing marker technique. Small felt pads bearing a chemiluminescent (glowi ma­erial, Cyalume®, were affixed to the abdomens of free-flying moths. insects orienting to a dim incandescent bulb were easily visible to the naked eye and were clearly captured on videotape. On their initial approach to the light source, M. sexta were found to orient at a mean angle of -0.220 ± 2.70 (mean ± SEM). The speed of the initial approach flight (OA ± 0.03 m/s) was significantly faster than the speed immediately after passing the light (0.29 ± 0.02 m/s; t =6.4, PM. sexta initially fly approximately at a light source and only after passing it, do they engage in circular flight around the source. M. sexta flight to lights does not entirely match any paths predicted by several light orientation mechanisms, including the commonly invoked light compass theory

Evidence from Strandings for Geomagnetic Sensitivity in Cetaceans

We tested the hypothesis that cetaceans use weak anomalies in the geomagnetic field as cues for orientation, navigation and/or piloting. Using the positions of 212 stranding events of live animals in the Smith sonian compilation which fall within the boundaries of the USGS East-Coast Aeromagnetic Survey, we found that there are highly significant tendencies for cetaceans to beach themselves near coastal locations with local magnetic minima. Monte-Carlo simulations confirm the significance of these effects. These results suggest that cetaceans have a magnetic sensory systemcomparable to that in other migratory and homing animals, and predict that the magnetic topography and in particular the marine magnetic lineations may play an important role in guiding long-distance migration. The ‘map’ sense of migratoryanimals may therefore be largely based on a simple strategy of following paths of local magnetic minima and avoiding magnetic gradients

The role of unsteadiness in direct initiation of gaseous detonations

An analytical model is presented for the direct initiation of gaseous detonations by a blast wave. For stable or weakly unstable mixtures, numerical simulations of the spherical direct initiation event and local analysis of the one-dimensional unsteady reaction zone structure identify a competition between heat release, wave front curvature and unsteadiness. The primary failure mechanism is found to be unsteadiness in the induction zone arising from the deceleration of the wave front. The quasi-steady assumption is thus shown to be incorrect for direct initiation. The numerical simulations also suggest a non-uniqueness of critical energy in some cases, and the model developed here is an attempt to explain the lower critical energy only. A critical shock decay rate is determined in terms of the other fundamental dynamic parameters of the detonation wave, and hence this model is referred to as the critical decay rate (CDR) model. The local analysis is validated by integration of reaction-zone structure equations with real gas kinetics and prescribed unsteadiness. The CDR model is then applied to the global initiation problem to produce an analytical equation for the critical energy. Unlike previous phenomenological models of the critical energy, this equation is not dependent on other experimentally determined parameters and for evaluation requires only an appropriate reaction mechanism for the given gas mixture. For different fuel–oxidizer mixtures, it is found to give agreement with experimental data to within an order of magnitude

Green Technologies for a More Sustainable Agriculture

For U.S. agriculture to continue along a sustainable path of economic development, further production increases must be generated by technologies that are both profitable and more environmentally benign. In this context, we assess the role of these green or sustainable technologies in steering agriculture along a more sustainable path. However, the lack of markets for the environmental attributes associated with green technologies can limit their development. In addition, simply making a technology available does not mean it will be adopted. Experience with green technologies such as conservation tillage, integrated pest management, enhanced nutrient management, and precision agriculture demonstrates that even when technologies are profitable, barriers to adopting new practices can limit their effectiveness.sustainable agriculture, natural capital, nonrenewable resources, renewable resources, environmental services, green technology, integrated pest management, conservation tillage, enhanced nutrient management, precision agriculture, Environmental Economics and Policy, Farm Management,

Medicaid Policy on Sterilization — Anachronistic or Still Relevant?

Female sterilization, typically accomplished by means of tubal ligation, is a widely used method of contraception that is highly effective at preventing unintended pregnancy. Yet there appears to be unmet demand for the procedure in certain segments of the U.S. population. Specifically, low-income women and women from minority racial and ethnic groups may face substantial system-level barriers to obtaining a desired sterilization procedure. One such barrier is the federal policy regarding Medicaid-funded sterilizations. Although this policy was designed to protect vulnerable populations, we believe that it does not effectively fulfill that intention — in fact, it restricts the reproductive autonomy of the women it intends to serve. With the upcoming Medicaid expansions, the number of women affected by these barriers could increase substantially.Population Research Cente

ALGEBRAIC PROOF IV FERMATS LAST THEOREM

The special case  z4 = x4 + y4 is impossible [1]. In view of this fact, it is only necessary to prove, if x, y, z, are relatively prime positive integers, Ï€ is an odd prime, zÏ€ = xÏ€ +yÏ€  (In this article, the symbol Ï€ will represent an odd prime). Also, a new proof is given that  z4 = x4 + y4 is impossible

algebraic proofs of Fermats last theorem and Beals conjecture

In this paper, the following statememt of Fermats Last Theorem is proved. If x, y, z are positive integersï° is an odd prime and z = x y , x, y, z ï° ï° ï° ï€« are all even. Also, in this paper, is proved (Beals conjecture) The equationï¸ ï­ ï® z = x  y has no solution in relatively prime positive integers x, y, z, with ï¸ ,ï­,ï® primes at least