Trading volume and firm‐specific announcements: Implications for the market model

The market model is commonly used in finance to study events and to evaluate security performance. With daily data, it is not uncommon to find low R‐squares, in the range 0–10%. Prior studies have attempted to improve the fit of the model by excluding observations associated with high trading volume. In this study, we compare the results of the high‐volume‐exclusion approach with the more direct firm‐specific announcement exclusion approach. The announcement approach excludes observations associated with Wall Street Journal Index news items regarding the firm. By excluding the [−1,0] fays relative to such news in a sample of 68 firms, we find that R‐squares increase significantly by about 5%. By excluding the days relative to earnings announcements only, R‐squares increase by about 4%. These results are then compared to the high‐volume‐exclusion approach. It is found that this approach is more efficient as an 8% increase in R‐squares is produced.The results of this study provide valuable evidence to empiricists by comparing the two approaches to improving the fit of the market model. The high‐volume ‐exclusion approach provides higher R‐squares. However, the relative efficiency of the two approaches should be balanced against the arguments for the methodologically correct approach. The advantage of using the firm‐specific announcement exclusion approach is that there is more confidence of excluding only firm‐specific movements from the estimation of the market model. It also allows a researcher to quickly and unambiguously identify the announcements and delete the corresponding observations. Furthermore, we find that about 50% of the improved fit, relative to the volume approach, can be accomplished by excluding earnings announcements. The methodological disadvantage of using the high‐volume‐exclusion approach is that it is affected not only by firm‐specific announcements but also by other factors, such as the heterogeneity of investor expectations. These factors may influence the choice of using firm‐specific announcements rather than the high‐volume approach despite the lower increment in R‐squares.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142312/1/rfe183.pd

Wireless local area network in a prehospital environment

BACKGROUND: Wireless local area networks (WLANs) are considered the next generation of clinical data network. They open the possibility for capturing clinical data in a prehospital setting (e.g., a patient's home) using various devices, such as personal digital assistants, laptops, digital electrocardiogram (EKG) machines, and even cellular phones, and transmitting the captured data to a physician or hospital. The transmission rate is crucial to the applicability of the technology in the prehospital setting. METHODS: We created two separate WLANs to simulate a virtual local are network environment such as in a patient's home or an emergency room (ER). The effects of different methods of data transmission, number of clients, and roaming among different access points on the file transfer rate were determined. RESULTS: The present results suggest that it is feasible to transfer small files such as patient demographics and EKG data from the patient's home to the ER at a reasonable speed. Encryption, user control, and access control were implemented and results discussed. CONCLUSIONS: Implementing a WLAN in a centrally managed and multiple-layer-controlled access control server is the key to ensuring its security and accessibility. Future studies should focus on product capacity, speed, compatibility, interoperability, and security management

Ambipolar Nernst effect in NbSe2_2

The first study of Nernst effect in NbSe$_2$ reveals a large quasi-particle contribution with a magnitude comparable and a sign opposite to the vortex signal. Comparing the effect of the Charge Density Wave(CDW) transition on Hall and Nernst coefficients, we argue that this large Nernst signal originates from the thermally-induced counterflow of electrons and holes and indicates a drastic change in the electron scattering rate in the CDW state. The results provide new input for the debate on the origin of the anomalous Nernst signal in high-T$_c$ cuprates.Comment: 5 pages including 4 figure

Variation beneath the surface: Quantifying complex thermal environments on coral reefs in the Caribbean, Bahamas and Florida

Analysis of in situ temperature records collected on six coral reefs in the Caribbean, Bahamas, and Florida Keys reveal significant variability across a range of temporal and spatial scales from minutes to seasons, across depths, and among sites. Subsurface variability occurring at daily and faster frequencies is prevalent across the region, likely driven by combinations of diurnal heating and cooling, wind driven advection, and internal waves at tidal and faster frequencies. This high frequency variability is not detected in records of remotely-sensed sea surface temperature alone. Diurnal variability likely caused by diurnal solar heating and cooling and possibly by advection associated with diurnal winds (daily sea breeze) was significant at all sites and showed greatest magnitude of variation at shallowest depths. Temperature fluctuations at tidal and faster frequencies were common at 5 out of the 6 sites. The magnitude of this variability is not well explained by measured vertical temperature stratification combined with oscillations of the water column associated with barotropic surface tides. Rather, the magnitude and nature of the temperature changes point to the presence of internal waves generated at tidal and faster frequencies. Power spectra calculated seasonally show greatest variability within both diurnal and semi-diurnal frequency bands in Spring and Summer at Florida, Bahamas, Jamaica, and St. Croix. Variability within the semi-diurnal frequency band at Belize and Bonaire was greatest in Winter. Warming in Summer estimated as degree-hours per day above 29.0°C increased with increasing latitude and varied significantly among sites and depths in a manner not predictable from remotely sensed SST data alone. Site latitude was directly related to the amplitude of the seasonal thermal variability, but was not tightly related to variability at daily and faster frequencies which was greatest at the highest and lowest latitude sites. The interactions of depth, site, and season across the study region are associated with distinct signals of thermal variability, and have significant implications for the physiology and ecology of corals and other reef organisms

The management of tuberculous pericardial effusion : experience in 233 consecutive patients

The original publication is available at http://www.cvja.co.za/Aim: We report on the 30-day and one-year outcome of consecutive effusive pericarditis patients, including those with tuberculous pericarditis, over a six-year-period. Methods and Results: Patients with large pericardial effusions requiring pericardiocentesis were included in the study after having given written informed consent. Clinical and radiological evaluations were followed by echo-guided pericardiocentesis, and extended daily intermittent drainage via an indwelling pigtail catheter. A standard short-course anti-tuberculous regimen was initiated. A total of 233 patients was included. One hundred and sixty-two patients had pericardial tuberculosis (TB), including 118 (73%) with microbiological and/ or histological evidence of TB and 44 (27%) diagnosed on clinical and supportive laboratory data. Over the six-year period, two patients developed fibrous constrictive pericarditis after receiving adjuvant corticosteroid therapy. The 30-day mortality (8.0%) was statistically higher for HIV-positive patients (corresponding mortality 9.9%) than for HIV-negative patients (6.2%; p=0.04). The oneyear all-cause mortality was 17.3%. It was also higher for HIV-positive (22.2%) than for HIV-negative patients (12.3%; p=0.03). Cardiac mortality was equal for HIVpositive and -negative patients. Conclusion: Tuberculous pericardial effusions responded well to closed pericardiocentesis and a six-month treatment of antituberculous chemotherapy. The former was effective and safe irrespective of HIV status.Publishers' versio

Spin-resolved electronic response to the phase transition in MoTe2_2

The semimetal MoTe$_2$ is studied by spin- and angle- resolved photoemission spectroscopy to probe the detailed electronic structure underlying its broad range of response behavior. A novel spin-texture is uncovered in the bulk Fermi surface of the non-centrosymmetric structural phase that is consistent with first-principles calculations. The spin-texture is three-dimensional, both in terms of momentum dependence and spin-orientation, and is not completely suppressed above the centrosymmetry-breaking transition temperature. Two types of surface Fermi arc are found to persist well above the transition temperature. The appearance of a large Fermi arc depends strongly on thermal history, and the electron quasiparticle lifetimes are greatly enhanced in the initial cooling. The results indicate that polar instability with strong electron-lattice interactions exists near the surface when the bulk is largely in a centrosymmetric phase