1,144 research outputs found

    Fighting Novel Diseases amidst Humanitarian Crises

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    Humanitarian crises are becoming more prevalent and, frequently, more complex, in zones of mis-governance, lack of government presence, and even active conflict, marked by public mistrust and insecurity. The WHO and other health emergency responders lack the capacities and mandate to adequately respond. The current Ebola outbreak in an area of an active insurgency in the Democratic Republic of the Congo is just such a crisis. The State Department has banned U.S. personnel from the outbreak zone due to safety concerns, leaving the population feeling abandoned, potentially increasing the threat to the few brave health workers who remain. We need is to rethink health emergency response during complex crises and devise new strategies. We offer a blueprint for responding to health emergencies amidst complex humanitarian crises. This blueprint includes peacekeepers who have the mandate and modalities fit for the purpose of quelling a health emergency; “smart” diplomacy to negotiate with belligerents and community members to ensure health and humanitarian worker safety; and deploying all needed health, security, and diplomatic assets. We also call for international development assistance for health, including to support states in developing core public health capacities, creating inclusive health systems, and meeting other need like clean water and nutritious food. Political actors will need to assume their responsibilities if humanitarians and health workers are to carry out theirs

    Combinatorial Games with a Pass: A dynamical systems approach

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    By treating combinatorial games as dynamical systems, we are able to address a longstanding open question in combinatorial game theory, namely, how the introduction of a "pass" move into a game affects its behavior. We consider two well known combinatorial games, 3-pile Nim and 3-row Chomp. In the case of Nim, we observe that the introduction of the pass dramatically alters the game's underlying structure, rendering it considerably more complex, while for Chomp, the pass move is found to have relatively minimal impact. We show how these results can be understood by recasting these games as dynamical systems describable by dynamical recursion relations. From these recursion relations we are able to identify underlying structural connections between these "games with passes" and a recently introduced class of "generic (perturbed) games." This connection, together with a (non-rigorous) numerical stability analysis, allows one to understand and predict the effect of a pass on a game.Comment: 39 pages, 13 figures, published versio

    Missing: Where Are the Migrants in Pandemic Influenza Preparedness Plans?

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    Influenza pandemics are perennial global health security threats, with novel and seasonal influenza affecting a large proportion of the world’s population, causing enormous economic and social destruction. Novel viruses such as influenza A(H7N9) continue to emerge, posing zoonotic and potential pandemic threats. Many countries have developed pandemic influenza preparedness plans (PIPPs) aimed at guiding actions and investments to respond to such outbreak events. Migrant and mobile population groups—such as migrant workers, cross-border frontier workers, refugees, asylum seekers, and other non-citizen categories residing within national boundaries—may be disproportionately affected in the event of health emergencies, with irregular/undocumented migrants experiencing even greater vulnerabilities. Because of a combination of political, sociocultural, economic, and legal barriers, many migrants have limited access to and awareness of health and welfare services, as well as their legal rights. The conditions in which migrants travel, live, and work often carry exceptional risks to their physical and mental well-being. Even if certain migrant groups have access to health services, they tend to avoid them due to fear of deportation, xenophobic and discriminatory attitudes within society, and other linguistic, cultural, and economic barriers. Evidence indicates that social stigmatization and anxieties generated by restrictive immigration policies hinder undocumented immigrants’ access to health rights and minimizes immigrants’ sense of entitlement to such rights

    Non-conformally flat initial data for binary compact objects

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    A new method is described for constructing initial data for a binary neutron-star (BNS) system in quasi-equilibrium circular orbit. Two formulations for non-conformally flat data, waveless (WL) and near-zone helically symmetric (NHS), are introduced; in each formulation, the Einstein-Euler system, written in 3+1 form on an asymptotically flat spacelike hypersurface, is exactly solved for all metric components, including the spatially non-conformally flat potentials, and for irrotational flow. A numerical method applicable to both formulations is explained with an emphasis on the imposition of a spatial gauge condition. Results are shown for solution sequences of irrotational BNS with matter approximated by parametrized equations of state that use a few segments of polytropic equations of state. The binding energy and total angular momentum of solution sequences computed within the conformally flat -- Isenberg-Wilson-Mathews (IWM) -- formulation are closer to those of the third post-Newtonian (3PN) two point particles up to the closest orbits, for the more compact stars, whereas sequences resulting from the WL/NHS formulations deviate from the 3PN curve even more for the sequences with larger compactness. We think it likely that this correction reflects an overestimation in the IWM formulation as well as in the 3PN formula, by 1\sim 1 cycle in the gravitational wave phase during the last several orbits. The work suggests that imposing spatial conformal flatness results in an underestimate of the quadrupole deformation of the components of binary neutron-star systems in the last few orbits prior to merger.Comment: 22 pages, 7 figure

    Robust convergence in pulse coupled oscillators with delays

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    We show that for pulse coupled oscillators a class of phase response curves with both excitation and inhibition exhibit robust convergence to synchrony on arbitrary aperiodic connected graphs with delays. We describe the basins of convergence and give explicit bounds on the convergence times. These results provide new and more robust methods for synchronization of sensor nets and also have biological implications.Comment: http://prl.aps.org/abstract/PRL/v106/i19/e19410

    The nusA recognition site : Alteration in its sequence or position relative to upstream translation interferes with the action of the N antitermination function of phage lambda

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    The phage [lambda] transcription antitermination protein, pN, acts with host factors. Nus, at sites on the phage genome, nut, to render RNA polymerase resistant to subsequent downstream termination signals. The NusA protein appears to recognize a seven to eight base-pair consensus sequence (5'Py-G-C-T-C-T-T(T)3') called boxA that is found in the promoter-proximal part of the nut region.Two types of change within or near the boxA sequence in the nutR region are shown to interfere with pN-mediated antitermination of transcription that has initiated at the upstream pR promoter. (1) A change of one base-pair (from G to T at the second position) in the box A sequence significantly reduces pN action. (2) We prove that a frameshift mutation, cro[Delta]62, at the end of the gene promoter-proximal to the [lambda] nutR region, interferes with the pN antitermination reaction by allowing translation to proceed beyond cro into the nutR region. Using a series of plasmid constructions, we now show that the inhibition of antitermination caused by the cro[Delta]62 mutation can be suppressed when translation is terminated upstream from this mutation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24597/1/0000005.pd

    SN~2012cg: Evidence for Interaction Between a Normal Type Ia Supernova and a Non-Degenerate Binary Companion

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    We report evidence for excess blue light from the Type Ia supernova SN 2012cg at fifteen and sixteen days before maximum B-band brightness. The emission is consistent with predictions for the impact of the supernova on a non-degenerate binary companion. This is the first evidence for emission from a companion to a SN Ia. Sixteen days before maximum light, the B-V color of SN 2012cg is 0.2 mag bluer than for other normal SN~Ia. At later times, this supernova has a typical SN Ia light curve, with extinction-corrected M_B = -19.62 +/- 0.02 mag and Delta m_{15}(B) = 0.86 +/- 0.02. Our data set is extensive, with photometry in 7 filters from 5 independent sources. Early spectra also show the effects of blue light, and high-velocity features are observed at early times. Near maximum, the spectra are normal with a silicon velocity v_{Si} = -10,500$ km s^{-1}. Comparing the early data with models by Kasen (2010) favors a main-sequence companion of about 6 solar masses. It is possible that many other SN Ia have main-sequence companions that have eluded detection because the emission from the impact is fleeting and faint.Comment: accepted to Ap

    The Very Short Period M Dwarf Binary SDSS J001641-000925

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    We present follow-up observations and analysis of the recently discovered short period low-mass eclipsing binary, SDSS J001641-000925. With an orbital period of 0.19856 days, this system has one of the shortest known periods for an M dwarf binary system. Medium-resolution spectroscopy and multi-band photometry for the system are presented. Markov chain Monte Carlo modeling of the light curves and radial velocities yields estimated masses for the stars of M1 = 0.54 +/- 0.07 Msun and M2 = 0.34 +/- 0.04 Msun, and radii of R1 = 0.68 +/- 0.03 Rsun and R2 = 0.58 +/- 0.03 Rsun respectively. This solution places both components above the critical Roche overfill limit, providing strong evidence that SDSS J001641-000925 is the first verified M-dwarf contact binary system. Within the follow-up spectroscopy we find signatures of non-solid body rotation velocities, which we interpret as evidence for mass transfer or loss within the system. In addition, our photometry samples the system over 9 years, and we find strong evidence for period decay at the rate of dP/dt ~8 s/yr. Both of these signatures raise the intriguing possibility that the system is in over-contact, and actively losing angular momentum, likely through mass loss. This places SDSS J001641-000925 as not just the first M-dwarf over-contact binary, but one of the few systems of any spectral type known to be actively undergoing coalescence. Further study SDSS J001641-000925 is on-going to verify the nature of the system, which may prove to be a unique astrophysical laboratory.Comment: 11 figures, ApJ Accepte
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