Follow-Up Observations of PTFO 8-8695: A 3 MYr Old T-Tauri Star Hosting a Jupiter-mass Planetary Candidate

We present Spitzer 4.5\micron\ light curve observations, Keck NIRSPEC radial velocity observations, and LCOGT optical light curve observations of PTFO~8-8695, which may host a Jupiter-sized planet in a very short orbital period (0.45 days). Previous work by \citet{vaneyken12} and \citet{barnes13} predicts that the stellar rotation axis and the planetary orbital plane should precess with a period of $300 - 600$ days. As a consequence, the observed transits should change shape and depth, disappear, and reappear with the precession. Our observations indicate the long-term presence of the transit events ($>3$ years), and that the transits indeed do change depth, disappear and reappear. The Spitzer observations and the NIRSPEC radial velocity observations (with contemporaneous LCOGT optical light curve data) are consistent with the predicted transit times and depths for the $M_\star = 0.34\ M_\odot$ precession model and demonstrate the disappearance of the transits. An LCOGT optical light curve shows that the transits do reappear approximately 1 year later. The observed transits occur at the times predicted by a straight-forward propagation of the transit ephemeris. The precession model correctly predicts the depth and time of the Spitzer transit and the lack of a transit at the time of the NIRSPEC radial velocity observations. However, the precession model predicts the return of the transits approximately 1 month later than observed by LCOGT. Overall, the data are suggestive that the planetary interpretation of the observed transit events may indeed be correct, but the precession model and data are currently insufficient to confirm firmly the planetary status of PTFO~8-8695b.Comment: Accepted for publication in The Astrophysical Journa

A Planarity Test via Construction Sequences

Optimal linear-time algorithms for testing the planarity of a graph are well-known for over 35 years. However, these algorithms are quite involved and recent publications still try to give simpler linear-time tests. We give a simple reduction from planarity testing to the problem of computing a certain construction of a 3-connected graph. The approach is different from previous planarity tests; as key concept, we maintain a planar embedding that is 3-connected at each point in time. The algorithm runs in linear time and computes a planar embedding if the input graph is planar and a Kuratowski-subdivision otherwise

Deuteron photo-disintegration with polarised photons in the energy range 30 - 50 MeV

The reaction d(\vec\gamma,np) has been studied using the tagged and polarised LADON gamma ray beam at an energy 30 - 50 MeV to investigate the existence of narrow dibaryonic resonances recently suggested from the experimental measurements in a different laboratory. The beam was obtained by Compton back-scattering of laser light on the electrons of the storage ring ADONE. Photo-neutron yields were measured at five neutron angle \vartheta_n = 22, 55.5, 90, 125 and 157 degrees in the center of mass system.Our results do not support the existence of such resonances.Comment: 16 pages, Latex, 22 figures, 1 table. Nucl. Phys. A to appea

Optical-Model Description of Time-Reversal Violation

A time-reversal-violating spin-correlation coefficient in the total cross section for polarized neutrons incident on a tensor rank-2 polarized target is calculated by assuming a time-reversal-noninvariant, parity-conserving ``five-fold" interaction in the neutron-nucleus optical potential. Results are presented for the system $n + {^{165}{\rm Ho}}$ for neutron incident energies covering the range 1--20 MeV. From existing experimental bounds, a strength of $2 \pm 10$ keV is deduced for the real and imaginary parts of the five-fold term, which implies an upper bound of order $10^{-4}$ on the relative $T$-odd strength when compared to the central real optical potential.Comment: 11 pages (Revtex

The angular distribution of the reaction νˉe+p→e++n\bar{\nu}_e + p \to e^+ + n

The reaction $\bar{\nu}_e + p \to e^+ + n$ is very important for low-energy ($E_\nu \lesssim 60$ MeV) antineutrino experiments. In this paper we calculate the positron angular distribution, which at low energies is slightly backward. We show that weak magnetism and recoil corrections have a large effect on the angular distribution, making it isotropic at about 15 MeV and slightly forward at higher energies. We also show that the behavior of the cross section and the angular distribution can be well-understood analytically for $E_\nu \lesssim 60$ MeV by calculating to ${\cal O}(1/M)$, where $M$ is the nucleon mass. The correct angular distribution is useful for separating $\bar{\nu}_e + p \to e^+ + n$ events from other reactions and detector backgrounds, as well as for possible localization of the source (e.g., a supernova) direction. We comment on how similar corrections appear for the lepton angular distributions in the deuteron breakup reactions $\bar{\nu}_e + d \to e^+ + n + n$ and $\nu_e + d \to e^- + p + p$. Finally, in the reaction $\bar{\nu}_e + p \to e^+ + n$, the angular distribution of the outgoing neutrons is strongly forward-peaked, leading to a measurable separation in positron and neutron detection points, also potentially useful for rejecting backgrounds or locating the source direction.Comment: 10 pages, including 5 figure

Effect of P to A Mutation of the N-Terminal Residue Adjacent to the Rgd Motif on Rhodostomin: Importance of Dynamics in Integrin Recognition

Rhodostomin (Rho) is an RGD protein that specifically inhibits integrins. We found that Rho mutants with the P48A mutation 4.4–11.5 times more actively inhibited integrin α5β1. Structural analysis showed that they have a similar 3D conformation for the RGD loop. Docking analysis also showed no difference between their interactions with integrin α5β1. However, the backbone dynamics of RGD residues were different. The values of the R2 relaxation parameter for Rho residues R49 and D51 were 39% and 54% higher than those of the P48A mutant, which caused differences in S2, Rex, and τe. The S2 values of the P48A mutant residues R49, G50, and D51 were 29%, 14%, and 28% lower than those of Rho. The Rex values of Rho residues R49 and D51 were 0.91 s−1 and 1.42 s−1; however, no Rex was found for those of the P48A mutant. The τe values of Rho residues R49 and D51 were 9.5 and 5.1 times lower than those of P48A mutant. Mutational study showed that integrin α5β1 prefers its ligands to contain (G/A)RGD but not PRGD sequences for binding. These results demonstrate that the N-terminal proline residue adjacent to the RGD motif affect its function and dynamics, which suggests that the dynamic properties of the RGD motif may be important in Rho's interaction with integrin α5β1

Barriers to the acceptance of electronic medical records by physicians from systematic review to taxonomy and interventions

<p>Abstract</p> <p>Background</p> <p>The main objective of this research is to identify, categorize, and analyze barriers perceived by physicians to the adoption of Electronic Medical Records (EMRs) in order to provide implementers with beneficial intervention options.</p> <p>Methods</p> <p>A systematic literature review, based on research papers from 1998 to 2009, concerning barriers to the acceptance of EMRs by physicians was conducted. Four databases, "Science", "EBSCO", "PubMed" and "The Cochrane Library", were used in the literature search. Studies were included in the analysis if they reported on physicians' perceived barriers to implementing and using electronic medical records. Electronic medical records are defined as computerized medical information systems that collect, store and display patient information.</p> <p>Results</p> <p>The study includes twenty-two articles that have considered barriers to EMR as perceived by physicians. Eight main categories of barriers, including a total of 31 sub-categories, were identified. These eight categories are: A) Financial, B) Technical, C) Time, D) Psychological, E) Social, F) Legal, G) Organizational, and H) Change Process. All these categories are interrelated with each other. In particular, Categories G (Organizational) and H (Change Process) seem to be mediating factors on other barriers. By adopting a change management perspective, we develop some barrier-related interventions that could overcome the identified barriers.</p> <p>Conclusions</p> <p>Despite the positive effects of EMR usage in medical practices, the adoption rate of such systems is still low and meets resistance from physicians. This systematic review reveals that physicians may face a range of barriers when they approach EMR implementation. We conclude that the process of EMR implementation should be treated as a change project, and led by implementers or change managers, in medical practices. The quality of change management plays an important role in the success of EMR implementation. The barriers and suggested interventions highlighted in this study are intended to act as a reference for implementers of Electronic Medical Records. A careful diagnosis of the specific situation is required before relevant interventions can be determined.</p

AGN STORM 2. IV. Swift X-ray and ultraviolet/optical monitoring of Mrk 817

The AGN STORM 2 campaign is a large, multiwavelength reverberation mapping project designed to trace out the structure of Mrk 817 from the inner accretion disk to the broad emission line region and out to the dusty torus. As part of this campaign, Swift performed daily monitoring of Mrk 817 for approximately 15 months, obtaining observations in X-rays and six UV/optical filters. The X-ray monitoring shows that Mrk 817 was in a significantly fainter state than in previous observations, with only a brief flare where it reached prior flux levels. The X-ray spectrum is heavily obscured. The UV/optical light curves show significant variability throughout the campaign and are well correlated with one another, but uncorrelated with the X-rays. Combining the Swift UV/optical light curves with Hubble UV continuum light curves, we measure interband continuum lags, $\tau(\lambda)$, that increase with increasing wavelength roughly following $\tau(\lambda) \propto \lambda^{4/3}$, the dependence expected for a geometrically thin, optically thick, centrally illuminated disk. Modeling of the light curves reveals a period at the beginning of the campaign where the response of the continuum is suppressed compared to later in the light curve - the light curves are not simple shifted and scaled versions of each other. The interval of suppressed response corresponds to a period of high UV line and X-ray absorption, and reduced emission line variability amplitudes. We suggest that this indicates a significant contribution to the continuum from the broad line region gas that sees an absorbed ionizing continuum.Comment: 20 pages, 13 figures, 3 tables, accepted for publication in Ap

The nuclear imperialism-necropolitics nexus: contextualizing Chinese-Uyghur oppression in our nuclear age

This paper provides a review of the People’s Republic of China’s (PRC) nuclear warfare and uranium mining programs in the Xinjiang Uyghur Autonomous Region. Its scope spans from the PRC’s first nuclear weapon test in Lop Nor, to contemporary issues surrounding in-situ leach uranium mining in the Yili basin, which now provides a third of PRC’s uranium. By exploring these scenarios, a lens can be placed on the parameters and limitations to Uyghur life within a nuclear state. This paper draws on the work of Achille Mbembe’s necropolitics, whereby power is persistently exercised as violence, to consider the entangled aftermath of nuclear imperialism and its effects to Uyghur bodies, environment and culture. While racialized nuclear imperialism presented Uyghur lives as inconsequential to progress in Xinjiang, post-Cold War necropolitics presents Uyghur culture as a direct threat to the progress and values of the PRC sovereign state. This paper proposes that the ongoing exploitation of nuclear Xinjiang provides an additional motivation for state-imposed necropolitical sanctions upon Uyghur people. This paper also presents anew theoretical contribution, the “nuclear imperialism-necropolitics nexus”, which offers away to consider the entangled legacies of spaces of nuclear activity, from nuclear imperialism to the post-Cold War world