Evidence on the Economics of Equity Return Volatility Clustering

The underlying economic sources of volatility clustering in asset returns remain a puzzle in financial economics. Using daily equity returns, we study variation in the volatility relation between the conditional variance of individual firm returns and yesterday's market return shock. We find a number of regularities in this market-to-firm volatility relation. (1) It decreases following macroeconomic news announcements; (2) it does not change systematically during the high-news months when firms announce quarterly earnings; and (3) it increases substantially with our measures of dispersion-in-beliefs across traders about the market's common-factor signal. Our evidence suggests that volatility-clustering is a natural result of a price formation process with heterogeneous beliefs across traders, and that volatility clustering is not attributable to an autocorrelated news-generation process around public information such as macroeconomic news releases or firms' earnings releases. We find consistent results in our sample of large-capitalization firms in Japan and the U.K., which suggests a generality of our results and bolsters our economic interpretation.

An analysis of the controls of participation in extra class activities in a large senior high school

In order to diagnose the problem, it will be necessary to determine to what extent active participation in extra-class activities has affected the academic standing of students, how the amount of time spent on such a program might offer a threat to their physical well being and how desirable physiological and sociological growth may be affected by the failure of the program to reach students because of monopolizing by a few

Reducing inappropriate antibiotics prescribing: The role of online commentary on physical examination findings

Objective: This study investigates the relationship of ‘online commentary’(contemporaneous physician comments about physical examination [PE] findings) with (i) parent questioning of the treatment recommendation and (ii) inappropriate antibiotic prescribing. Methods: A nested cross-sectional study of 522 encounters motivated by upper respiratory symptoms in 27 California pediatric practices (38 pediatricians). Physicians completed a post-visit survey regarding physical examination findings, diagnosis, treatment, and whether they perceived the parent as expecting an antibiotic. Taped encounters were coded for ‘problem’ online commentary (PE findings discussed as significant or clearly abnormal) and ‘no problem’ online commentary (PE findings discussed reassuringly as normal or insignificant). Results: Online commentary during the PE occurred in 73% of visits with viral diagnoses (n = 261). Compared to similar cases with ‘no problem’ online commentary, ‘problem’ comments were associated with a 13% greater probability of parents uestioning a non-antibiotic treatment plan (95% CI 0-26%, p = .05,) and a 27% (95% CI: 2-52%, p < .05) greater probability of an inappropriate antibiotic prescription. Conclusion: With viral illnesses, problematic online comments are associated with more pediatrician-parent conflict over non-antibiotic treatment recommendations. This may increase inappropriate antibiotic prescribing. Practice implications: In viral cases, physicians should consider avoiding the use of problematic online commentary

Ambiguities in action ascription

In everyday interactions with one another, speakers not only say things but also do things like offer, complain, reject, and compliment. Through observation, it is possible to see that much of the time people unproblematically understand what others are doing. Research on conversation has further documented how speakers’ word choice, prosody, grammar, and gesture all help others to recognize what actions they are performing. In this study, we rely on spontaneous naturally occurring conversational data where people have trouble making their actions understood to examine what leads to ambiguous actions, bringing together prior research and identifying recurrent types of ambiguity that hinge on different dimensions of social action. We then discuss the range of costs and benefits for social actors when actions are clear versus ambiguous. Finally, we offer a conceptual model of how, at a microlevel, action ascription is done. Actions in interaction are building blocks for social relations; at each turn, an action can strengthen or strain the bond between two individuals. Thus, a unified theory of action ascription at a microlevel is an essential component for broader theories of social action and of how social actions produce, maintain, and revise the social world

An experimental study of transonic flow about a supercritical airfoil

A series of experiments was conducted on flow fields about two airfoil models whose sections are slight modifications of the original Whitcomb supercritical airfoil section. Data obtained include surface static-pressure distributions, far-wake surveys, oil-flow photographs, pitot-pressure surveys in the viscous regions, and holographic interferograms. These data were obtained for different combinations of lift coefficient and free-stream Mach number, which included both subcritical cases and flows with upper-surface shock waves. The availability of both pitot-pressure data and density data from interferograms allowed determination of flow-field properties in the vicinity of the trailing edge and in the wake without recourse to any assumptions about the local static pressure. The data show that significant static-pressure gradients normal to viscous layers exist in this region, and that they persist to approximately 10% chord downstream of the trailing edge. Comparisons are made between measured boundary-layer properties and results from boundary-layer computations that employed measured static-pressure distributions, as well as comparisons between data and results of airfoil flow-field computations

An experimental study of transonic flow about a supercritical airfoil. Static pressure and drag data obtained from tests of a supercritical airfoil and an NACA 0012 airfoil at transonic speeds, supplement

Surface static-pressure and drag data obtained from tests of two slightly modified versions of the original NASA Whitcomb airfoil and a model of the NACA 0012 airfoil section are presented. Data for the supercritical airfoil were obtained for a free-stream Mach number range of 0.5 to 0.9, and a chord Reynolds number range of 2 x 10 to the 6th power to 4 x 10 to the 6th power. The NACA 0012 airfoil was tested at a constant chord Reynolds number of 2 x 10 to the 6th power and a free-stream Mach number range of 0.6 to 0.8

Detailed transonic flow field measurements about a supercritical airfoil section

The transonic flow field about a Whitcomb-type supercritical airfoil profile was measured in detail. In addition to the usual surface pressure distributions and wake surveys, schlieren photographs were taken and velocity vector profiles were determined in the upper surface boundary layer and in the near wake. Spanwise variations in the measured pressures were also determined. The data are analyzed with the aid of an inviscid transonic finite-difference computer program as well as with boundary layer modeling and calculation schemes

Predicting clinical trial results based on announcements of interim analyses

BACKGROUND: Announcements of interim analyses of a clinical trial convey information about the results beyond the trial’s Data Safety Monitoring Board (DSMB). The amount of information conveyed may be minimal, but the fact that none of the trial’s stopping boundaries has been crossed implies that the experimental therapy is neither extremely effective nor hopeless. Predicting success of the ongoing trial is of interest to the trial’s sponsor, the medical community, pharmaceutical companies, and investors. We determine the probability of trial success by quantifying only the publicly available information from interim analyses of an ongoing trial. We illustrate our method in the context of the National Surgical Adjuvant Breast and Bowel (NSABP) trial, C-08. METHODS: We simulated trials based on the specifics of the NSABP C-08 protocol that were publicly available. We quantified the uncertainty around the treatment effect using prior weights for the various possibilities in light of other colon cancer studies and other studies of the investigational agent, bevacizumab. We considered alternative prior distributions. RESULTS: Subsequent to the trial’s third interim analysis, our predictive probabilities were: that the trial would eventually be successful, 48.0%; would stop for futility, 7.4%; and would continue to completion without statistical significance, 44.5%. The actual trial continued to completion without statistical significance. CONCLUSIONS: Announcements of interim analyses provide information outside the DSMB’s sphere of confidentiality. This information is potentially helpful to clinical trial prognosticators. ‘Information leakage’ from standard interim analyses such as in NSABP C-08 is conventionally viewed as acceptable even though it may be quite revealing. Whether leakage from more aggressive types of adaptations is acceptable should be assessed at the design stage

Deferring the decision point : Treatment assertions in neurology outpatient consultations

Recommendations can be implied by asserting some generalisation about a treatment’s benefit without overtly directing the patient to take it. Focusing on a collection of assertions in UK neurology consultations, this paper shows that these are overwhelmingly receipted as “merely” doing informing and argues that this is made possible by their ambiguous design: their relatively depersonalised formats convey that the neurologist is simply telling the patient what’s available, but the link made between the treatment and the patient’s condition implies that it will be of benefit. Thus, assertions, while stopping short of telling the patient what to do, are hearable as recommendation relevant. This delicates balance leaves it up to the patient to respond either to the implied or on-record action (recommending vs. informing). When treated as “merely” doing informing, assertions defer the decision point until the neurologist has done something more. Three main interactional functions of this are identified as follows: (i) indicating the existence of a solution to a concern, without making a decision relevant next; (ii) orienting to the patient’s right to choose; and (iii) making “cautious” recommendations

Mimicking damaged DNA with a small molecule inhibitor of human UNG2

Human nuclear uracil DNA glycosylase (UNG2) is a cellular DNA repair enzyme that is essential for a number of diverse biological phenomena ranging from antibody diversification to B-cell lymphomas and type-1 human immunodeficiency virus infectivity. During each of these processes, UNG2 recognizes uracilated DNA and excises the uracil base by flipping it into the enzyme active site. We have taken advantage of the extrahelical uracil recognition mechanism to build large small-molecule libraries in which uracil is tethered via flexible alkane linkers to a collection of secondary binding elements. This high-throughput synthesis and screening approach produced two novel uracil-tethered inhibitors of UNG2, the best of which was crystallized with the enzyme. Remarkably, this inhibitor mimics the crucial hydrogen bonding and electrostatic interactions previously observed in UNG2 complexes with damaged uracilated DNA. Thus, the environment of the binding site selects for library ligands that share these DNA features. This is a general approach to rapid discovery of inhibitors of enzymes that recognize extrahelical damaged bases