Search for Cosmic-Ray Electron and Positron Anisotropies with Seven Years of Fermi Large Area Telescope Data.

The Large Area Telescope on board the Fermi Gamma-ray Space Telescope has collected the largest ever sample of high-energy cosmic-ray electron and positron events since the beginning of its operation. Potential anisotropies in the arrival directions of cosmic-ray electrons or positrons could be a signature of the presence of nearby sources. We use almost seven years of data with energies above 42 GeV processed with the Pass 8 reconstruction. The present data sample can probe dipole anisotropies down to a level of 10^{-3}. We take into account systematic effects that could mimic true anisotropies at this level. We present a detailed study of the event selection optimization of the cosmic-ray electrons and positrons to be used for anisotropy searches. Since no significant anisotropies have been detected on any angular scale, we present upper limits on the dipole anisotropy. The present constraints are among the strongest to date probing the presence of nearby young and middle-aged sources.

Physics in strong magnetic fields near neutron stars.

Electromagnetic phenomena occurring in the strong magnetic fields of neutron stars are currently of great interest in high-energy astrophysics. Observations of rotation rate changes and cyclotron lines in pulsars and gamma-ray bursts indicate that surface magnetic fields of neutron stars often exceed 10(12) gauss. In fields this strong, where electrons behave much as if they were in bound atomic states, familiar processes undergo profound changes, and exotic processes become important. Strong magnetic fields affect the physics in several fundamental ways: Energies perpendicular to the field are quantized, transverse momentum is not conserved, and electron-positron spin is important. Neutron stars therefore provide a unique laboratory for the study of physics in extremely high fields that cannot be generated on Earth.

Oregon Beach Monitoring Program: Bacterial exceedances in marine and freshwater creeks/outfall samples, October 2002-April 2005.

A total of 3086 samples, both marine (2916) and freshwater creeks/outfall samples (170) were collected and analyzed for enterococci during October 2002-April 2005, from 52 designated beaches in Oregon. A total of 3.2% (99/3086) of the samples at 21 beaches exceeded 158 most probable number (MPN)/100 milliliters (mL). The average enterococci levels of these 99 exceedances was 559 MPN/100 mL, with a maximum of 4352 MPN/100 mL (Otter Rock and Ona) and a minimum of 160 MPN/100 mL (Sunset Bay State Park, Bastendorff, and Mill). For marine water, 77/2916 (2.6%) exceeded 158 MPN/100 mL. For freshwater, 22/170 (12.9%) exceeded 158 MPN/100 mL, with a maximum of 587 MPN/100 mL at Sunset Bay. Sixty percent of the marine and 9% of freshwater exceedances occurred during the winter. Seventy-two percent (55/77) of the marine exceedances occurred after rainfall events (0.01-60.0 mm). At Harris and Mill Beaches, cumulative rainfall was highly correlated with bacterial densities, R = 0.7. Rainfall, at both beaches, explained about one-half the variation in log10 bacteria density (R2 = 0.5). Additional monitoring is warranted to further characterize bacterial contamination in Oregon waters.

The effect of an offset polar cap dipolar magnetic field on the modeling of the Vela pulsar's γ-ray light curves.

We performed geometric pulsar light curve modeling using static, retarded vacuum, and offset polar cap (PC) dipole B-fields (the latter is characterized by a parameter ε), in conjunction with standard two-pole caustic (TPC) and outer gap (OG) emission geometries. The offset-PC dipole B-field mimics deviations from the static dipole (which corresponds to ε = 0). In addition to constant-emissivity geometric models, we also considered a slot gap (SG) E-field associated with the offset-PC dipole B-field and found that its inclusion leads to qualitatively different light curves. Solving the particle transport equation shows that the particle energy only becomes large enough to yield significant curvature radiation at large altitudes above the stellar surface, given this relatively low E-field. Therefore, particles do not always attain the radiation-reaction limit. Our overall optimal light curve fit is for the retarded vacuum dipole field and OG model, at an inclination angle [Formula: see text] and observer angle [Formula: see text]. For this B-field, the TPC model is statistically disfavored compared to the OG model. For the static dipole field, neither model is significantly preferred. We found that smaller values of ε are favored for the offset-PC dipole field when assuming constant emissivity, and larger ε values favored for variable emissivity, but not significantly so. When multiplying the SG E-field by a factor of 100, we found improved light curve fits, with α and ζ being closer to best fits from independent studies, as well as curvature radiation reaction at lower altitudes.

Medical waste treatment and disposal methods used by hospitals in Oregon, Washington, and Idaho.

This study investigated medical waste practices used by hospitals in Oregon, Washington, and Idaho, which includes the majority of hospitals in the U.S. Environmental Protection Agency's (EPA) Region 10. During the fall of 1993, 225 hospitals were surveyed with a response rate of 72.5%. The results reported here focus on infectious waste segregation practices, medical waste treatment and disposal practices, and the operating status of hospital incinerators in these three states. Hospitals were provided a definition of medical waste in the survey, but were queried about how they define infectious waste. The results implied that there was no consensus about which agency or organization's definition of infectious waste should be used in their waste management programs. Confusion around the definition of infectious waste may also have contributed to the finding that almost half of the hospitals are not segregating infectious waste from other medical waste. The most frequently used practice of treating and disposing of medical waste was the use of private haulers that transport medical waste to treatment facilities (61.5%). The next most frequently reported techniques were pouring into municipal sewage (46.6%), depositing in landfills (41.6%), and autoclaving (32.3%). Other methods adopted by hospitals included Electro-Thermal-Deactivation (ETD), hydropulping, microwaving, and grinding before pouring into the municipal sewer. Hospitals were asked to identify all methods they used in the treatment and disposal of medical waste. Percentages, therefore, add up to greater than 100% because the majority chose more than one method. Hospitals in Oregon and Washington used microwaving and ETD methods to treat medical waste, while those in Idaho did not. No hospitals in any of the states reported using irradiation as a treatment technique. Most hospitals in Oregon and Washington no longer operate their incinerators due to more stringent regulations regarding air pollution emissions. Hospitals in Idaho, however, were still operating incinerators in the absence of state regulations specific to these types of facilities.

Nigerian university students' knowledge, perceptions, and behaviours about HIV/AIDS: are these students at risk?

The purpose of the study was to determine the knowledge level of undergraduate students of a Nigerian university about HIV/AIDS, their perception of risk of contracting HIV/AIDS based on their sexual behaviour, and to assess how students acquire information about HIV/AIDS. The sample consisted of 380 students from five faculties of the university who volunteered to participate in the study. Participants completed a survey asking about their knowledge about transmission, symptomatology and prevention of HIV/AIDS. The survey included questions about their sexual orientation, past and present sexual practices as well as sources of information about HIV/AIDS. The results indicated that the students were knowledgeable about transmission and symptomatology but there were some misconceptions about the mode of transmission of HIV. Few students identified themselves to be at high risk even though majority of them (92%) were sexually experienced. The study also showed that even though these students are knowledgeable and concerned about contracting HIV/AIDS from their partners, this did not prevent them from engaging in unprotected sexual intercourse. It appears, however, that students are exercising caution when negotiating new sexual relationships, as they are likely to discuss (and insist on) using condoms and ask to have a monogamous relationship. Students obtained information about HIV/AIDS primarily from the media rather than from school classrooms and homes, which suggests a need to increase educational efforts at the university. Many students of this university may be at risk of becoming HIV-infected due to their age bracket, level of sexual activity and past/present sexual behaviors. University faculty can be actively involved in developing and implementing HIV/AIDS education and prevention strategies on their campuses. Health educators must go beyond providing accurate and gender-specific information about HIV/AIDS; they must also help students realistically assess their own risk of infection, and develop communication processes which enable them to negotiate safer sexual practices.

Agreement between specially trained and accredited optometrists and glaucoma specialist consultant ophthalmologists in their management of glaucoma patients.

AIMS: Optometrists are becoming increasingly involved in the co-management of glaucoma patients as the burden on the Hospital Eye Service continues to escalate. The aim of this study was to assess the agreement between specially trained optometrists and glaucoma-specialist consultant ophthalmologists in their management of glaucoma patients. METHODS: Four optometrists examined 23-25 patients each and the clinical findings, up to the point of dilation, were documented in the hospital records. The optometrist, and one of two consultant ophthalmologists, then independently examined and documented the optic-disc appearance before recording their decisions regarding the stability and management of the patient on a specially designed proforma. Percentage agreement was calculated together with kappa or weighted kappa statistics, where appropriate. RESULTS: Agreement between consultants and optometrists in evaluating glaucoma stability was 68.5% (kappa (κ)=0.42-0.50) for visual fields, 64.5% (weighted κ=0.17-0.31) for optic discs, and 84.5% (weighted κ=0.55-0.60) for intraocular pressures. Agreement regarding medical management was 96.5% (κ=0.73-0.81) and for other glaucoma management decisions, including timing of follow-up, referral to a consultant ophthalmologist, and discharge, was 72% (weighted κ=0.65). This agreement increased to 90% following a retrospective independent then consensus review between the two consultants and when qualified agreements were included. Of the 47 glaucoma and non-glaucoma queries generated during the study, 42 resulted in a change of management. CONCLUSION: Confirming the ability of optometrists to make appropriate decisions regarding the stability and management of glaucoma patients is essential if their involvement is to continue to develop to meet the demand of an aging population.

Evaluating microbial indicators of environmental condition in Oregon rivers.

Traditional bacterial indicators used in public health to assess water quality and the Biolog system were evaluated to compare their response to biological, chemical, and physical habitat indicators of stream condition both within the state of Oregon and among ecoregion aggregates (Coast Range, Willamette Valley, Cascades, and eastern Oregon). Forty-three randomly selected Oregon river sites were sampled during the summer in 1997 and 1998. The public health indicators included heterotrophic plate counts (HPC), total coliforms (TC), fecal coliforms (FC) and Escherichia coli (EC). Statewide, HPC correlated strongly with physical habitat (elevation, riparian complexity, % canopy presence, and indices of agriculture, pavement, road, pasture, and total disturbance) and chemistry (pH, dissolved O2, specific conductance, acid-neutralizing capacity, dissolved organic carbon, total N, total P, SiO2, and SO4). FC and EC were significantly correlated generally with the river chemistry indicators. TC bacteria significantly correlated with riparian complexity, road disturbance, dissolved O2, and SiO2 and FC. Analyzing the sites by ecoregion, eastern Oregon was characterized by high HPC, FC, EC, nutrient loads, and indices of human disturbance, whereas the Cascades ecoregion had correspondingly low counts of these indicators. The Coast Range and Willamette Valley presented inconsistent indicator patterns that are more difficult to characterize. Attempts to distinguish between ecoregions with the Biolog system were not successful, nor did a statistical pattern emerge between the first five principle components and the other environmental indicators. Our research suggests that some traditional public health microbial indicators may be useful in measuring the environmental condition of lotic systems.