Swift observations of the 2015 outburst of AG Peg -- from slow nova to classical symbiotic outburst

Symbiotic stars often contain white dwarfs with quasi-steady shell burning on their surfaces. However, in most symbiotics, the origin of this burning is unclear. In symbiotic slow novae, however, it is linked to a past thermonuclear runaway. In June 2015, the symbiotic slow nova AG Peg was seen in only its second optical outburst since 1850. This recent outburst was of much shorter duration and lower amplitude than the earlier eruption, and it contained multiple peaks -- like outbursts in classical symbiotic stars such as Z And. We report Swift X-ray and UV observations of AG Peg made between June 2015 and January 2016. The X-ray flux was markedly variable on a time scale of days, particularly during four days near optical maximum, when the X-rays became bright and soft. This strong X-ray variability continued for another month, after which the X-rays hardened as the optical flux declined. The UV flux was high throughout the outburst, consistent with quasi-steady shell burning on the white dwarf. Given that accretion disks around white dwarfs with shell burning do not generally produce detectable X-rays (due to Compton-cooling of the boundary layer), the X-rays probably originated via shocks in the ejecta. As the X-ray photo-electric absorption did not vary significantly, the X-ray variability may directly link to the properties of the shocked material. AG Peg's transition from a slow symbiotic nova (which drove the 1850 outburst) to a classical symbiotic star suggests that shell burning in at least some symbiotic stars is residual burning from prior novae.Comment: Accepted by MNRAS 23 June 2016. Manuscript submitted in original form 5 April 201

What about the men? Perinatal experiences of men of color whose partners were at risk for preterm birth, a qualitative study.

BACKGROUND:Preterm birth in the United States is associated with maternal clinical factors such as diabetes, hypertension and social factors including race, ethnicity, and socioeconomic status. In California, 8.7% of all live births are preterm, with African American and Black families experiencing the greatest burden. The impact of paternal factors on birth outcomes has been studied, but little is known about the experience of men of color (MOC). The purpose of this study was to explore the experiences of MOC who are partners to women at medical and social risk for preterm birth. METHODS:This study used a qualitative research design and focus group methods. The research was embedded within an existing study exploring experiences of women of color at risk for preterm birth conducted by the California Preterm Birth Initiative. RESULTS:Twelve MOC participated in the study and among them had 9 preterm children. Four themes emerged from thematic analysis of men's experiences: (1) "Being the Rock": Providing comfort and security; (2) "It's a blessing all the way around": Keeping faith during uncertainty; (3) "Tell me EVERYTHING": Unmet needs during pregnancy and delivery; (4) "Like a guinea pig": Frustration with the healthcare system. Participants identified many barriers to having a healthy pregnancy and birth including inadequate support for decision making, differential treatment, and discrimination. CONCLUSIONS:This study shows novel and shared narratives regarding MOC experiences during pregnancy, birth, and postpartum periods. Healthcare providers have an essential role to acknowledge MOC, their experience of discrimination and mistrust, and to assess needs for support that can improve birth outcomes. As MOC and their families are at especially high social and medical risk for preterm birth, their voice and experience should be central in all future research on this topic

Spherical harmonic decomposition applied to spatial-temporal analysis of human high-density EEG

We demonstrate an application of spherical harmonic decomposition to analysis of the human electroencephalogram (EEG). We implement two methods and discuss issues specific to analysis of hemispherical, irregularly sampled data. Performance of the methods and spatial sampling requirements are quantified using simulated data. The analysis is applied to experimental EEG data, confirming earlier reports of an approximate frequency-wavenumber relationship in some bands.Comment: 12 pages, 8 figures, submitted to Phys. Rev. E, uses APS RevTeX style

Absence of a structural transition up to 40 Gpa in MgB2 and the relevance of magnesium non-stoichiometry

We report measurements on MgB2 up to ~40GPa. Increasing pressure yields a monotonous decrease of the lattice parameters and of the c/a ratio, but no structural transition down to parameters smaller than those of AlB2. The transition superconducting temperature also decreases with temperature in a sample dependent way. The results are explained by an increase of the filling of the 2D pxy bands with pressure, the Mg stoichiometry determining the starting position of the Fermi level. Our measurements indicate that these hole bands are the relevant ones for superconductivity.Comment: submitted March 9th 2001, PRB accepte

Search by triplet: An efficient local track reconstruction algorithm for parallel architectures

Millions of particles are collided every second at the LHCb detector placed inside the Large Hadron Collider at CERN. The particles produced as a result of these collisions pass through various detecting devices which will produce a combined raw data rate of up to 40 Tbps by 2021. These data will be fed through a data acquisition system which reconstructs individual particles and filters the collision events in real time. This process will occur in a heterogeneous farm employing exclusively off-the-shelf CPU and GPU hardware, in a two stage process known as High Level Trigger. The reconstruction of charged particle trajectories in physics detectors, also referred to as track reconstruction or tracking, determines the position, charge and momentum of particles as they pass through detectors. The Vertex Locator subdetector (VELO) is the closest such detector to the beamline, placed outside of the region where the LHCb magnet produces a sizable magnetic field. It is used to reconstruct straight particle trajectories which serve as seeds for reconstruction of other subdetectors and to locate collision vertices. The VELO subdetector will detect up to 109 particles every second, which need to be reconstructed in real time in the High Level Trigger. We present Search by triplet, an efficient track reconstruction algorithm. Our algorithm is designed to run efficiently across parallel architectures. We extend on previous work and explain the algorithm evolution since its inception. We show the scaling of our algorithm under various situations, and analyse its amortized time in terms of complexity for each of its constituent parts and profile its performance. Our algorithm is the current state-of-the-art in VELO track reconstruction on SIMT architectures, and we qualify its improvements over previous results

An Ex Vivo Capillary-Arteriole Preparation To Investigate Neurovascular Coupling

Neurovascular Coupling (NVC) is a mechanism that links neural activity to changes in cerebral brain blood flow, playing a pivotal role in maintaining normal brain function. This interplay between neurons and the vasculature is often impaired in neurodegenerative disorders and stroke, underlining its significance in neurological health. In response to neuronal activity, various mediators are released to influence arteriolar smooth muscle tone and local blood flow. Understanding of capillary-mediated NVC is limited due to the inaccessibility of capillaries for experimental observation and the scarcity of suitable experimental assays. Our aim in this study is to advance a recently proposed ex vivo isolated Capillary-Arteriole preparation for quantifying Kir-mediate signaling in the cerebral microcirculation. The experiments involve using a C57BL6 mice and genetically modified Kir2.1 knockout mice. Kir-KO mice are generated by crossing mice expressing CRE recombinase under an endothelial-specific promoter Cadherin 5 with a Kir 2.1 floxed Tg mice, where exon 1 of the Kir 2.1 gene is flanked by LoxP sites. A homozygous LoxP mouse with CRE is obtained after two generations of breeding. Brain isolation is performed following euthanization, using micro-forceps, the Middle Cerebral artery (MCA) is excised from the Circle of Willis and traced until reaching smaller pial vessels at the top of the brain. A small piece of tissue at the end of the isolated vasculature is preserved and carefully disrupted using forceps. The isolate is placed on the surface of aCSF solution. Surface tension enhances the removal of parenchymal tissue and stresses the isolated capillary-arteriole network

Fabrication and Characterization of Multiband Solar Cells Based on Highly Mismatched Alloys

Multiband solar cells are one type of third generation photovoltaic devices in which an increase of the power conversion efficiency is achieved through the absorption of low energy photons while preserving a large band gap that determines the open circuit voltage. The ability to absorb photons from different parts of the solar spectrum originates from the presence of an intermediate energy band located within the band gap of the material. This intermediate band, acting as a stepping stone allows the absorption of low energy photons to transfer electrons from the valence band to the conduction band by a sequential two photons absorption process. It has been demonstrated that highly mismatched alloys offer a potential to be used as a model material system for practical realization of multiband solar cells. Dilute nitride GaAs1-xNx highly mismatched alloy with low mole fraction of N is a prototypical multiband semiconductor with a well-defined intermediate band. Currently, we are using chemical beam epitaxy to synthesize dilute nitride highly mismatched alloys. The materials are characterized by a variety of structural and optical methods to optimize their properties for multiband photovoltaic devices