Semiparametric Estimation in Models of First-Price, Sealed-Bid Auctions with Affiliation

Within the affiliated private-values paradigm, we develop a tractable empirical model of equilibrium behaviour at first-price, sealed-bid auctions. The model is non-parametrically identified, but the rate of convergence in estimation is slow when the number of bidders is even moderately large, so we develop a semiparametric estimation strategy, focusing on the Archimedean family of copulae and implementing this framework using particular members--the Clayton, Frank, and Gumbel copulae. We apply our framework to data from low-price, sealed-bid auctions used by the Michigan Department of Transportation to procure road-resurfacing services, rejecting the hypothesis of independence and finding significant (and high) affiliation in cost signals.first-price, sealed-bid auctions, copulae, affiliation

Structural glaciology of Austre Brøggerbreen, northwest Svalbard

<p>Structural glaciological maps can be used to study the structural evolution and past dynamics of glaciers. The map described here documents the glacier-wide structural characteristics of Austre Brøggerbreen, a <i>c</i>. 12 km² predominantly cold-based valley glacier in northwest Svalbard. The structural map reveals that the glacier is dominated by deep-penetrating fractures that are now relict (crevasse traces). These structures indicate that, despite being relatively inactive at present, the glacier was once much more dynamic, presumably during its last advance in the Neoglacial (<i>c</i>. 1900 AD). Contemporary glacier structures (i.e. those that are actively forming) include primary stratification, longitudinal foliation and rare surface fracturing (crevasses and water-healed crevasses). Relict fracture sets become increasingly re-orientated and folded down-glacier as a result of ductile flow. Individual flow units show large differences in the evolution of structures, indicating that the flow units have been subject to different flow histories and dynamics. The map will also be useful for future change-detection studies on this rapidly receding glacier.</p

Sleep disturbance in movement disorders:insights, treatments and challenges

Sleep and circadian rhythm disturbances are central features of many movement disorders, exacerbating motor and non-motor symptoms and impairing quality of life. Understanding these disturbances to sleep is clinically important and may further our understanding of the underlying movement disorder. This review evaluates the current anatomical and neurochemical understanding of normal sleep and the recognised primary sleep disorders. In addition, we undertook a systematic review of the evidence for disruption to sleep across multiple movement disorders. Rapid eye movement sleep behaviour disorder has emerged as the most reliable prodromal biomarker for the alpha synucleinopathies, including Parkinson’s disease and multiple system atrophy, often preceding motor symptom onset by several years. Abnormal sleep has also been described for many other movement disorders, but further evidence is needed to determine whether this is a primary or secondary phenotypic component of the underlying condition. Medication used in the treatment of motor symptoms also affects sleep and can aggravate or cause certain sleep disorders. Within the context of movement disorders, there is also some suggestion of a shared underlying mechanism for motor and sleep pathophysiology, with evidence implicating thalamic and brainstem structures and monoaminergic neurotransmission. This review highlights the need for an understanding of normal and abnormal sleep within the movement disorder clinic, an ability to screen for specific causes of poor sleep and to treat sleep disturbance to improve quality of life. Key sleep disorders also act as important biomarkers and have implications in diagnosis, prognosis and the development of future therapies

Impact of impurities in shielding material on simulations of instrument background in space

A major source of background for x-ray focal plane detectors in space instrumentation aboard missions, such as Extended Roentgen Survey with an Imaging Telescope Array and Athena Wide Field Imager, is the space radiation environment. High-energy radiations from the environment interact with the spacecraft structure leading to large productions of secondary particles with energies that are detectable in the science region of interest for instrumentation. Reducing the background from these events is vital for the success of many missions. Graded-Z shielding is a common solution to help reduce the instrument background. Layers of materials with decreasing atomic numbers near detectors help reduce the background. Much of the design is determined through iterative simulations to find an optimal solution that meets the requirements for the scientific operation of the instrument. Recent results have indicated an underestimate in the instrument background from the simulations. One hypothesis has been that the simulations do not typically include the impurities in the shielding materials. The work presented investigates the association of impurities in the graded-Z materials and the instrument background spectra. Typically, impurities are not included in material definitions as they can significantly increase computational time. The impurities, percentage loading, and distribution have all been explored and evaluated for an Al-Mo-Be graded-Z shield

Entry, Growth, and Survival in the Green Industry

Economists are interested in the factors that induce firm entry, lead to growth, and help firms succeed in various markets. Such information can be helpful to policymakers but, unfortunately, such patterns have not been considered for “green industries.” This paper takes advantage of a recent definition of green industries proposed by the Bureau of Labor Statistics to investigate patterns characterizing these industries within the State of Texas. Leveraging the differences between the five sub-categories within the BLS definition, this study attempts to identify the comparative advantage each county has within the green economy

Caspase-2-Mediated Cleavage of Mdm2 Creates a p53-Induced Positive Feedback Loop

Caspase-2 is an evolutionarily conserved caspase, yet its biological function and cleavage targets are poorly understood. Caspase-2 is activated by the p53 target gene product PIDD (also known as LRDD) in a complex called the Caspase-2-PIDDosome. We show that PIDD expression promotes growth arrest and chemotherapy resistance by a mechanism that depends on Caspase-2 and wild-type p53. PIDD-induced Caspase-2 directly cleaves the E3 ubiquitin ligase Mdm2 at Asp 367, leading to loss of the C-terminal RING domain responsible for p53 ubiquitination. As a consequence, N-terminally truncated Mdm2 binds p53 and promotes its stability. Upon DNA damage, p53 induction of the Caspase-2-PIDDosome creates a positive feedback loop that inhibits Mdm2 and reinforces p53 stability and activity, contributing to cell survival and drug resistance. These data establish Mdm2 as a cleavage target of Caspase-2 and provide insight into a mechanism of Mdm2 inhibition that impacts p53 dynamics upon genotoxic stress.Virginia and D.K. Ludwig Fund for Cancer Research (Postdoctoral Fellowship)Human Frontier Science Program (Strasbourg, France) (Fellowship)National Cancer Institute (U.S.) (Cancer Center Support (Core) Grant P30-CA14051

A Pilot Randomized, Controlled Trial of an In-Home Drinking Water Intervention Among HIV + Persons

Although immunocompromised persons may be at increased risk for gastrointestinal illnesses, no trials investigating drinking water treatment and gastrointestinal illness in such patients have been published. Earlier results from San Francisco suggested an association (OR 6.76) between tap water and cryptosporidiosis among HIV + persons. The authors conducted a randomized, triple-blinded intervention trial of home water treatment in San Francisco, California, from April 2000 to May 2001. Fifty HIV-positive patients were randomized to externally identical active (N = 24) or sham (N = 26) treatment devices. The active device contained a filter and UV light; the sham provided no treatment. Forty-five (90%) of the participants completed the study and were successfully blinded. Illness was measured using \u27highly credible gastrointestinal illness\u27 (HCGI), a previously published measure. There were 31 episodes of HCGI during 1,797 person-days in the sham group and 16 episodes during 1,478 person-days in the active group. The adjusted relative risk was 3.34 (95% CI: 0.99-11.21) times greater in those with the sham device. The magnitude of the point estimate of the risk, its consistency with recently published observational data, and its relevance for drinking water choices by immunocompromised individuals support the need for larger trials

Inferences Drawn from a Risk Assessment Compared Directly with a Randomized Trial of a Home Drinking Water Intervention

Risk assessments and intervention trials have been used by the U.S. Environmental Protection Agency to estimate drinking water health risks. Seldom are both methods used concurrently. Between 2001 and 2003, illness data from a trial were collected simultaneously with exposure data, providing a unique opportunity to compare direct risk estimates of waterborne disease from the intervention trial with indirect estimates from a risk assessment. Comparing the group with water treatment (active) with that without water treatment (sham), the estimated annual attributable disease rate (cases per 10,000 persons per year) from the trial provided no evidence of a significantly elevated drinking water risk [attributable risk = −365 cases/year, sham minus active; 95% confidence interval (CI), −2,555 to 1,825]. The predicted mean rate of disease per 10,000 persons per person-year from the risk assessment was 13.9 (2.5, 97.5 percentiles: 1.6, 37.7) assuming 4 log removal due to viral disinfection and 5.5 (2.5, 97.5 percentiles: 1.4, 19.2) assuming 6 log removal. Risk assessments are important under conditions of low risk when estimates are difficult to attain from trials. In particular, this assessment pointed toward the importance of attaining site-specific treatment data and the clear need for a better understanding of viral removal by disinfection. Trials provide direct risk estimates, and the upper confidence limit estimates, even if not statistically significant, are informative about possible upper estimates of likely risk. These differences suggest that conclusions about waterborne disease risk may be strengthened by the joint use of these two approaches

Carbon Sequestration in Dryland and Irrigated Agroecosystems: Quantification at Different Scales for Improved Prediction

The overall objective of this research is to improve our basic understanding of the biophysical processes that govern C sequestration in major rainfed and irrigated agroecosystems in the north-central USA