Power Law Distribution of the Frequency of Demises of U.S Firms

Both theoretical and applied economics have a great deal to say about many aspects of the firm, but the literature on the extinctions, or demises, of firms is very sparse. We use a publicly available data base covering some 6 million firms in the US and show that the underlying statistical distribution which characterises the frequency of firm demises - the disappearances of firms as autonomous entities - is closely approximated by a power law. The exponent of the power law is, intriguingly, close to that reported in the literature on the extinction of biological species.Comment: 8 pages, 2 figure

Giving patients granular control of personal health information: Using an ethics ‘Points to Consider’ to inform informatics system designers

Objective: There are benefits and risks of giving patients more granular control of their personal health information in electronic health record (EHR) systems. When designing EHR systems and policies, informaticists and system developers must balance these benefits and risks. Ethical considerations should be an explicit part of this balancing. Our objective was to develop a structured ethics framework to accomplish this. Methods: We reviewed existing literature on the ethical and policy issues, developed an ethics framework called a “Points to Consider” (P2C) document, and convened a national expert panel to review and critique the P2C. Results: We developed the P2C to aid informaticists designing an advanced query tool for an electronic health record (EHR) system in Indianapolis. The P2C consists of six questions (“Points”) that frame important ethical issues, apply accepted principles of bioethics and Fair Information Practices, comment on how questions might be answered, and address implications for patient care. Discussion: The P2C is intended to clarify whatis at stake when designers try to accommodate potentially competing ethical commitments and logistical realities. The P2C was developed to guide informaticists who were designing a query tool in an existing EHR that would permit patient granular control. While consideration of ethical issues is coming to the forefront of medical informatics design and development practices, more reflection is needed to facilitate optimal collaboration between designers and ethicists. This report contributes to that discussion

The Impact of a water-imposed interruption of growth in the Las Vegas region

This study is prompted by the expectation that water supplies for the Las Vegas Valley, both those used currently and those additional quantities available from existing sources, cannot sustain significant further economic growth of the region beyond the year 2006. There are five parts to this study. Part I uses a regional econometric (REMI) model to project the growth of the Las Vegas region to natural maturity, essentially unconstrained by an overriding water shortage. Part II is a reinforcing cross-section analysis of metropolitan areas in the United States to learn the most common natural growth patterns and those that have produced a good quality of life with a minimum of major local disturbances. This analysis gives attention to employment, population, income, and other key economic and social indicators. We give special attention to events in cities that are nearer to or at levels of maturity still many years away for Las Vegas. Part III of this study looks at the performance of sectors of the Las Vegas economy between 1970 and 1989. In particular, we identify those sectors of the Las Vegas economy that are sensitive to variations in growth, particularly during the 1979 to 1983 recession period. Part IV examines the impact of an unrelieved water shortage after 2006 on the Las Vegas socioeconomic future, giving special attention to the fraction of employment that depends on historically high growth rates to predict the impact of rapid decline of that employment. In Part IV, we employ the depth and power of the REMI model to portray the consequences for Las Vegas of a sharp drop in growth after 2006. In this part, we simulate a sixty percent reduction in construction employment, based on the experience of other cities investigated in Part II. We trace this disruption of growth through reduced employment, population, output, and income. We measure the effect of the water shortage by comparing the values of economic variables with a water shortage with a control forecast produced under the assumption of adequate water supplies. Part IV also includes a partial analysis of a Las Vegas water shortage on rural Nevada and on the state of Nevada as a whole. Part V investigates the impact on rural areas of construction and operation of a system bringing water from outlying areas to the Las Vegas region. We are aware that final planning for such a system is not yet completed. We have used a reasonable set of expenditures, locations, and periods that can be expected to occur. These simulations provide a plausible estimate of the effects of both the construction and operation of a water-delivery system on employment and income in those rural areas. As more definite information emerges, appropriate changes can readily be made and new analysis of impacts can be quickly provided

Within‑marsh and Landscape Features Structure Ribbed Mussel Distribution in Georgia, USA, Marshes

Ribbed mussels, Geukensia demissa, are marsh fauna that are used in coastal management and restoration due to the ecosystem services they provide. Ribbed mussel restoration efforts may be improved with a greater understanding of the environmental drivers of ribbed mussel distribution at multiple spatial scales to predict areas where restoration could be successful. This study sought to estimate the effects of within-marsh (4 m) and landscape (500 m) factors on ribbed mussel distribution. Ribbed mussel densities were surveyed at 11 sites along the coast of Georgia, USA, and overlaid with spatial data for within-marsh factors (elevation, distance to marsh features, slope) as well as landscape factors (percent cover by subtidal creek, forest, and development within a 500-m radius). The distribution model was then validated using three previously unsurveyed marshes and explained 55% of the variance in ribbed mussel abundance. Ribbed mussel abundances and occupancy were most sensitive to changes in within-marsh factors (elevation and distance to subtidal creeks, bodies of water inundated during the full tidal cycle) but were also sensitive to landscape features (percent landcover of forests and development). The highest ribbed mussel densities were found in mid-elevation areas (~ 0.7 m NAVD88), far from subtidal creeks, and in marshes surrounded with forest and development. These results contrast with distributions in the northeastern USA, where ribbed mussels are distributed along subtidal creek banks. This work suggests that restoration may be most effective when focused on appropriate elevations and at locations away from the marsh-creek ecotone

Delinquent Mortgages, Neglected Swimming Pools, and West Nile Virus, California

Adjustable rate mortgages and the downturn in the California housing market caused a 300% increase in notices of delinquency in Bakersfield, Kern County. This led to large numbers of neglected swimming pools, which were associated with a 276% increase in the number of human West Nile virus cases during the summer of 2007

Observations on the Ice-Breaking and Ice Navigation Behavior of Migrating Bowhead Whales (Balaena Mysticetus) near Point Barrow, Alaska, Spring 1985

During a four-day period from 28 April to 1 May 1985, we observed bowhead whales breaking up through sea ice in order to breathe. Our observations were made from grounded sea ice approximately 10 km northeast of Point Barrow, Alaska, during the spring bowhead migration (14 April to 10 June). From acoustic and visual data, it was estimated that 665 whales passed the observation perches during this four-day period. However, only 117(17%) whales were seen. The remaining whales either passed underneath the ice or were beyond the range of the visual observers. Whales used their heads, in the area of the blowholes, to push up against the ice (18 cm maximum thickness) and fracture it, creating a hummock of ice in which they were able to respire. Often during such breathing episodes, even at distances of only several hundred meters, the animal was not seen but its blows were clearly audible to the visual observers. Acoustic tracking of whales showed they avoided a large multi-year ice floe seaward of the observation perch. We hypothesize that bowheads use their calls to assess the thickness of ice in their migratory path. In assessing their calls, we suggest the whales can avoid areas where the ice is too thick to break through (to breath) and/or too thick to provide clearance for them to swim beneath.Key words: Balaena mysticetus, Point Barrow, bowhead whale, ice breaking, behavior, sea ice, singer, acoustic, anatomy, censusMots clés: Balaena mysticetus, Point Barrow, baleine franche, casser la glace, comportement, glace de mer, chanteuse, acoustique, anatomie, dénombremen

The NuSTAR Extragalactic Surveys: unveiling rare, buried AGNs and detecting the contributors to the peak of the Cosmic X-ray Background

We report on the results of active galactic nuclei (AGNs) detection by NuSTAR performed in three extragalactic survey fields (COSMOS, UDS, ECDFS) in three hard bands, namely H1 (8-16 keV), H2 (16-24 keV) and VH (35-55 keV). The aggregated area of the surveys is $\sim 2.7$ deg$^2$. While a large number of sources is detected in the H1 band (72 at the $97\%$ level of reliability), the H2 band directly probing close to the peak of the Cosmic X-ray Background (CXB) returns four significant detections, and two tentative, although not significant, detections are found in the VH band. All the sources detected above 16 keV are also detected at lower energies. We compute the integral number counts for sources in such bands, which show broad consistency with population synthesis models of the CXB. We furthermore identify two Compton-thick AGNs, one in the COSMOS field, associated with a hard and faint Chandra source, and one in the UDS field, never detected in the X-ray band before. Both sources are at the same redshift $z \sim 1.25$, which shifts their Compton-hump into the H1 band, and were previously missed in the usually employed NuSTAR bands, confirming the potential of using the H1 band to discover obscured AGNs at $z > 1$ in deep surveys.Comment: 12 pages, 5 figures, accepted for publication in The Astrophysical Journa