SN1991bg-like supernovae are a compelling source of most Galactic antimatter

The Milky Way Galaxy glows with the soft gamma ray emission resulting from the annihilation of $\sim 5 \times 10^{43}$ electron-positron pairs every second. The origin of this vast quantity of antimatter and the peculiar morphology of the 511keV gamma ray line resulting from this annihilation have been the subject of debate for almost half a century. Most obvious positron sources are associated with star forming regions and cannot explain the rate of positron annihilation in the Galactic bulge, which last saw star formation some $10\,\mathrm{Gyr}$ ago, or else violate stringent constraints on the positron injection energy. Radioactive decay of elements formed in core collapse supernovae (CCSNe) and normal Type Ia supernovae (SNe Ia) could supply positrons matching the injection energy constraints but the distribution of such potential sources does not replicate the required morphology. We show that a single class of peculiar thermonuclear supernova - SN1991bg-like supernovae (SNe 91bg) - can supply the number and distribution of positrons we see annihilating in the Galaxy through the decay of $^{44}$Ti synthesised in these events. Such $^{44}$Ti production simultaneously addresses the observed abundance of $^{44}$Ca, the $^{44}$Ti decay product, in solar system material.Comment: Accepted for publication in Proceedings of IAU Symposium 322: The Multimessenger Astrophysics of the Galactic Center 4 page

Nonlinear energy-loss straggling of protons and antiprotons in an electron gas

The electronic energy-loss straggling of protons and antiprotons moving at arbitrary nonrelativistic velocities in a homogeneous electron gas are evaluated within a quadratic response theory and the random-phase approximation (RPA). These results show that at low and intermediate velocities quadratic corrections reduce significantly the energy-loss straggling of antiprotons, these corrections being, at low-velocities, more important than in the evaluation of the stopping power.Comment: 4 pages, 3 figures, to appear in Phys. Rev.

Detection and mapping of hydrothermally altered rocks in the vicinity of the comstock lode, Virginia Range, Nevada, using enhanced LANDSAT images

The author has identified the following significant results. LANDSAT images enhanced by the band-ratioing method can be used for reconnaissance alteration mapping in moderately heavily vegetated semiarid terrain as well as in sparsely vegetated to semiarid terrain where the technique was originally developed. Significant vegetation cover in a scene, however, requires the use of MSS ratios 4/5, 4/6, and 6/7 rather than 4/5, 5/6, and 6/7, and requires careful interpretation of the results. Supplemental information suitable to vegetation identification and cover estimates, such as standard LANDSAT false-color composites and low altitude aerial photographs of selected areas is desirable

Assessment of maternal referral systems used for a rural Zambian hospital: the development of setting specific protocols for the identification of complications

Background: In resource-limited countries, it is estimated that up to 75% of maternal deaths are preventable. Maternal referral systems are an effective measure to help prevent these deaths. Objective: The objective of this study was to delineate criteria that health care workers use to identify obstetrical emergencies and make referrals, in order to evaluate the effectiveness of the established referral system and to implement improvements to this system.Methods: Using a qualitative study design, the individuals with the highest level of formal obstetrics training at 10 health posts that refer to a rural Zambian hospital were surveyed using semi-structured interviews regarding their referral protocols. Data were analyzed through open-coding. At the conclusion of the interview, standardized referral protocols for obstetric emergen- cies derived from published guidelines and local practices were distributed.Results: Identified complications resulting in referral most commonly included post-partum hemorrhage (70%), prolonged labor (70%), malpresentation (50%), antepartum hemorrhage (40%), and retained placenta (40%). While numerous reasons for referral were identified, there was little consensus on the referral protocol used for each complication.  Obstacles to successful referral most commonly included cellular network disruptions (70%), distance (50%), and lack of transportation (30%). The referral protocols distributed to health posts covered only 11 of the 23 complications cited as the most common reason for referral.Conclusion: The referral criteria and protocols were updated to include all of the reported complications. We propose this document for others working in resource-limited settings attempting to establish or evaluate a maternal referral systems.Keywords: Maternal referral systems, Zambian hospital, protocols, complications

On the dimension of subspaces with bounded Schmidt rank

We consider the question of how large a subspace of a given bipartite quantum system can be when the subspace contains only highly entangled states. This is motivated in part by results of Hayden et al., which show that in large d x d--dimensional systems there exist random subspaces of dimension almost d^2, all of whose states have entropy of entanglement at least log d - O(1). It is also related to results due to Parthasarathy on the dimension of completely entangled subspaces, which have connections with the construction of unextendible product bases. Here we take as entanglement measure the Schmidt rank, and determine, for every pair of local dimensions dA and dB, and every r, the largest dimension of a subspace consisting only of entangled states of Schmidt rank r or larger. This exact answer is a significant improvement on the best bounds that can be obtained using random subspace techniques. We also determine the converse: the largest dimension of a subspace with an upper bound on the Schmidt rank. Finally, we discuss the question of subspaces containing only states with Schmidt equal to r.Comment: 4 pages, REVTeX4 forma