988 research outputs found

    Hospital as a critical infrastructure in the community disaster response system

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    The Department of Homeland Security lists 19 groups of sectors as Critical Infrastructure Key Resources (CIKR) such as Water, Emergency Services, and Healthcare and Public Health (HPH). Protection of those interdependent sectors is of vital interest for the country in the event of disaster. Hospital infrastructure systems are basic HPH elements of the CIKR. Local hospitals deliver essential routine healthcare services as well as serving as frontline responders during non-routine disaster events. Currently, hospitals generally extend their routine healthcare activities for external community disaster preparedness and response services. This extension takes the form of coordination with other responders within the community. Under this condition, determining the hospital\u27s role in the community disaster response is critical. This thesis evaluates the current external performance of a hospital in response to a community disaster and the degree of integration of hospitals with the community system during and after a disaster. Case studies of two hospitals in Western New York State, one a rural institution sample and the other an urban institution sample, are conducted with data collected through program review and structured interviews of the hospitals\u27 staff and the Emergency Management Officers of each community and analyzed using context analysis. The analysis shows that rural hospitals are more critical to community recovery than urban centers; communication both internal and external to the hospital is key to effectiveness; and emergency planning is actually only a small part of response

    Evolution of 3-d magnetic topology in flare-productive active regions

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    Solar eruptive phenomena, such as flares and coronal mass ejections (CMEs), derive their energy from complex magnetic fields and are the principal source of disturbances that affect space weather. Although physical mechanism and dynamic morphology of flares have been a subject of intense research, many aspects of the flaring process still remain unclear. The objective of this dissertation is to advance the understanding of the physics behind solar flares based on observations, simulations and nonlinear force-free (NLFF) field modeling of magnetic fields. The data used in this study are obtained from several ground-based or space-borne instruments, including BBSO/DVMG, Hinode/SOT/SP, SDO/HMI and GOES. In addition, the advanced coronal modeling method was utilized to extrapolate NLFF magnetic fields. This dissertation focuses on the magnetic properties (magnetic inclination angle, transverse magnetic field, Lorentz force, etc.) and their evolution associated with flares. The observation is also compared with numerical MHD simulations and theoretical models. The main findings in this dissertation are briefly summarized as follows: (1) the white-light observation of S sunspots reveal the rapid penumbral decay and central umbral/penumbral darkening associated with flares; (2) the magnetic inclination angle shows an increase in the decayed peripheral penumbra and a decrease in the central area close to the flaring polarity inversion line (PIL) after major flares; (3) magnetic field observations indicate a rapid and permanent enhancement of the transverse magnetic field in the umbral core or inner penumbral region, while that in the outer decayed penumbral region decreases; (4) the downward Lorentz force exerted on the flaring area displays a sudden enhancement after flares; (5) the footpoint of flare ribbons shows slow shearing followed by fast diverging and deshearing motion. The remote Ha brightenings appear in the first stage of the eruption while the associated hard X-ray emission occurs in the later phase. These results provide strong evidence favoring superimposed effects of both the tether-cutting model, in which a short and flat loop forms near the photosphere after the eruption, and the back reaction of the coronal magnetic field following the energy release. The major contribution of this dissertation is: (1) First study of 3-D magnetic field change associated with flares in the perspective of magnetic inclination angle and transverse magnetic field; (2) First successful comparison of the numerical simulation, observation and theory of solar flare associated magnetic field changes; (3) First clear evidence of the two stage magnetic reconnection (implosion and explosion); (4) First evidence in support of the conservation of momentum in solar flare. To understand the radio emission produced by electrons at the very acceleration site of a solar flare, two competing acceleration models– stochastic acceleration by cascading MHD turbulence and regular acceleration in collapsing magnetic traps were studied. It is found that the radio emission from the acceleration sites (1) has sufficiently strong intensity to be observed by currently available radio instruments and (2) has spectra and light curves which are distinctly different in these two competing models, which makes them observationally distinguishable