Approximate Inference for Constructing Astronomical Catalogs from Images

We present a new, fully generative model for constructing astronomical catalogs from optical telescope image sets. Each pixel intensity is treated as a random variable with parameters that depend on the latent properties of stars and galaxies. These latent properties are themselves modeled as random. We compare two procedures for posterior inference. One procedure is based on Markov chain Monte Carlo (MCMC) while the other is based on variational inference (VI). The MCMC procedure excels at quantifying uncertainty, while the VI procedure is 1000 times faster. On a supercomputer, the VI procedure efficiently uses 665,000 CPU cores to construct an astronomical catalog from 50 terabytes of images in 14.6 minutes, demonstrating the scaling characteristics necessary to construct catalogs for upcoming astronomical surveys.Comment: accepted to the Annals of Applied Statistic

Characterization of low-noise quasi-optical SIS mixers for the submillimeter band

We report on the development of low-noise quasi-optical SIS mixers for the frequency range 400-850 GHz. The mixers utilize twin-slot antennas, two-junction tuning circuits, and Nb-trilayer junctions. Fourier-transform spectrometry has been used to verify that the frequency response of the devices is well predicted by computer simulations. The 400-850 GHz frequency band can be covered with four separate fixed-tuned mixers. We measure uncorrected double-sideband receiver noise temperatures around 5hν/kB to 700 GHz, and better than 540 K at 808 GHz. These results are among the best reported to date for broadband heterodyne receivers

Psychosocial Capacity Building in New York: Building Resiliency with Construction Workers Assigned to Ground Zero after 9/11

[Excerpt] Psychosocial capacity building, which is a more common approach in response to disasters outside of Western Europe and the U.S., was, in part, a reaction against the perceived “traumatization” and pathologizing of disaster survivors, as well as the over-emphasis on the individual at the expense of the collectivity and community (Ager, 1997; IASC, 2007; Kleinman & Cohen, 1997; Miller, in press; Mollica, 2006; Strang & Ager, 2003; Summerfield 1995; 2000; Wessels, 1999; Wessels & Monteiro, 2006). The accent with psychosocial capacity building is equally on the social as well as the psychological. Some of the tenets of this approach are: an emphasis on families, groups and communities; focusing on strengths, capacities and sources of resiliency; a wariness of the medicalization of social reactions to abnormal situations; centralizing culture and its impact on meaning making after a disaster, expression of affect and its implications for healing; using local, indigenous, often non-professional people as the designers and implementers of projects; supporting and reconstructing mutual aid and self-help groups; taking into account socio-cultural variables such as race, class, and gender when considering the impact of a disaster and how to respond to it. Although there are clearly different points of emphasis, a mental health approach and psychosocial capacity building approach are not mutually exclusive and can be combined for effective, multi-systemic interventions to respond to disasters. There were elements of both approaches in the project described in this paper

Thermal And Mechanical Response Of Particulate Composite Plates Under Inertial Excitation

The thermal and mechanical, near-resonant responses of particulate composite plates formed from hydroxyl-terminated polybutadiene (HTPB) binder and varying volume ratios of ammonium chloride (NH4Cl) particles (50, 65, 75%) are investigated. Each test specimen is clamped and forced with three levels of band-limited, white noise inertial excitation (10–1000 Hz at 1.00, 1.86 and 2.44 g RMS). The mechanical response of each plate is recorded via scanning laser Doppler vibrometry. The plates are then excited at a single resonant frequency and the thermal response is recorded via infrared thermography. Comparisons are made between the mechanical operational deflection shapes of each plate and spatial temperature distributions, with correlation seen between the observed level of strain, as visualized by strain energy density, and heat generation. The effect of particle/binder ratio on both the thermal and mechanical responses is discussed. Acquired results are also compared to an analytical model of the system. The observed thermomechanical effects render an improved understanding of the thermomechanics of plastic-bonded composites, an essential step in support of the development of new technologies for the vapor-based detection of hidden explosives