A possible dearth of hot gas in galaxy groups at intermediate redshift

We examine the X-ray luminosity of galaxy groups in the CNOC2 survey, at redshifts 0.1 < z < 0.6. Previous work examining the gravitational lensing signal of the CNOC2 groups has shown that they are likely to be genuine, gravitationally bound objects. Of the 21 groups in the field of view of the EPIC-PN camera on XMM-Newton, not one was visible in over 100 ksec of observation, even though three of the them have velocity dispersions high enough that they would easily be visible if their luminosities scaled with their velocity dispersions in the same way as nearby groups' luminosities scale. We consider the possibility that this is due to the reported velocity dispersions being erroneously high, and conclude that this is unlikely. We therefore find tentative evidence that groups at intermediate redshift are underluminous relative to their local cousins.Comment: 16 pages, 5 figures, reference added in section 1, typos corrected, published in Ap

Socio-cultural, environmental and health challenges facing women and children living near the borders between Afghanistan, Iran and Pakistan (AIP region)

For hundreds of years, people in the AIP region (the Afghanistan-Iran-Pakistan borders) have been challenged by conflict and political and civil instability, mass displacement, human rights abuses, drought and famine. Given this sad history, it not surprising that in this region health and quality of life of vulnerable groups are among the worst in the world. In spite of national and international efforts to improve health status of vulnerable populations in this region, the key underlying socio-cultural determinants of health and disparities, i.e. gender, language, ethnicity, residential status, and socio-economic status (SES), have not been addressed or even systematically studied, nor have their relationship to environmental challenges. Overall, the health problems faced by this under-developed region can be categorized into those resulting from lack of essential supplies and services, as well as those stemming from the existing cultural practices in the area

Habitable Climates

According to the standard liquid-water definition, the Earth is only partially habitable. We reconsider planetary habitability in the framework of energy-balance models, the simplest seasonal models in physical climatology, to assess the spatial and temporal habitability of Earth-like planets. We quantify the degree of climatic habitability of our models with several metrics of fractional habitability. Previous evaluations of habitable zones may have omitted important climatic conditions by focusing on close Solar System analogies. For example, we find that model pseudo-Earths with different rotation rates or different land-ocean fractions have fractional habitabilities that differ significantly from that of the Earth itself. Furthermore, the stability of a planet's climate against albedo-feedback snowball events strongly impacts its habitability. Therefore, issues of climate dynamics may be central in assessing the habitability of discovered terrestrial exoplanets, especially if astronomical forcing conditions are different from the moderate Solar System cases.Comment: Accepted by ApJ. Several references added. 41 pages, 11 figures, 2 table

Detection of visible light from the darkest world

We present the detection of visible light from the planet TrES-2b, the darkest exoplanet currently known. By analysis of the orbital photometry from publicly available Kepler data (0.4-0.9 microns), we determine a day-night contrast amplitude of (6.5 +/- 1.9 ppm), constituting the lowest amplitude orbital phase variation discovered. The signal is detected to 3.7 sigma confidence and persists in six different methods of modelling the data and thus appears robust. In contrast, we are unable to detect ellipsoidal variations or beaming effects, but we do provide confidence intervals for these terms. If the day-night contrast is interpreted as being due to scattering, it corresponds to a geometric albedo of Ag = 0.0253 +/- 0.0072. However, our models indicate that there is a significant emission component to day-side brightness, and the true albedo is even lower (<1%). By combining our measurement with Spitzer and ground-based data, we show that a model with moderate redistribution (Pn ~ 0.3) and moderate extra optical opacity (kappa' ~ 0.3-0.4) provide a compatible explanation to the data.Comment: 5 pages, 3 figures. Accepted in MNRAS Letters. Minor typos corrected from last versio

Using Web-Based Technology in Laboratory Instruction to Reduce Costs

The authors report the results of a project to reemphasize high quality, hands-on laboratory courses in the engineering curriculum while reducing their costs through the application of web-based teaching tools. The project resulted in substantial gains in productivity of faculty and staff, increased utilization of laboratory space, cost reductions in equipment, and improved quality of learning for our students

Linear Current-Mode Active Pixel Sensor

A current mode CMOS active pixel sensor (APS) providing linear light-to-current conversion with inherently low fixed pattern noise (FPN) is presented. The pixel features adjustable-gain current output using a pMOS readout transistor in the linear region of operation. This paper discusses the pixel’s design and operation, and presents an analysis of the pixel’s temporal noise and FPN. Results for zero and first-order pixel mismatch are presented. The pixel was implemented in a both a 3.3 V 0.35 µm and a 1.8 V 0.18 µm CMOS process. The 0.35 µm process pixel had an uncorrected FPN of 1.4%/0.7% with/without column readout mismatch. The 0.18 µm process pixel had 0.4% FPN after delta-reset sampling (DRS). The pixel size in both processes was 10 X 10 µm2, with fill factors of 26% and 66%, respectively

Patiromer Decreases Serum Potassium and Phosphate Levels in Patients on Hemodialysis

Background: Persistent hyperkalemia (serum potassium (K) ≥5.5 mEq/l) is a common condition in hemodialysis (HD) patients, is associated with increased mortality, and treatment options are limited. The effect of patiromer, a gastrointestinal K binder, on serum K was examined in HD patients. Methods: Six hyperkalemic HD patients (5 anuric) were admitted to clinical research units for 15 days (1 pretreatment week and 1 patiromer treatment week) and they received a controlled diet with identical meals on corresponding days of pretreatment and treatment weeks. Phosphate (P) binders were discontinued on admission. Patiromer, 12.6 g daily (divided 4.2 g TID with meals), was started on the Monday morning following the last pretreatment week blood sampling. Serum and 24-hour stool samples were collected daily. Results: Mean ± SE serum K decreased (maximum change per corresponding day, 0.6 ± 0.2 mEq/l, p = 0.009) and fecal K increased 58% on patiromer compared with the pretreatment week. During the pretreatment week, 69.0, 47.6, and 11.9% of patients' serum K values were ≥5.5, ≥6.0, and ≥6.5 mEq/l, respectively. This was reduced to 38.1% (p = 0.009), 11.9% (p < 0.001), and 2.4% (p = 0.2) on patiromer. Following P binder discontinuation, the long interdialytic interval mean ± SE serum P numerically increased from 5.8 ± 0.4 to 7.0 ± 0.5 mg/dl (p = 0.06). On patiromer, P decreased from 7.0 ± 0.5 to 6.2 ± 0.5 mg/dl (p = 0.04). While on patiromer, fecal P numerically increased by 112 ± 72 mg/day (17%; p = 0.1792; range -148 to 344 mg/day). No patient discontinued patiromer because of adverse events (AEs); none had serious AEs. Conclusions: In 6 hyperkalemic HD patients, patiromer decreased serum K and P levels and increased fecal K

Hands-on Computer Use in Science Classrooms: The Skeptics Are Still Waiting

Frank Collea was a friend of Robert Fuller and David Brooks, and a mentor to Brooks. We miss him for his energy, his enthusiasm for teaching science, and his perception about how to improve science education. Frank Collea was not a big fan of using computers in instruction. Frank was neither an advocate of using computers to deliver instruction, nor an advocate of teaching their use as professional tools. Indeed, he thought that most of those of us who advocate computer use make assertions that are unwarranted. A decade ago, desktop computers were beginning to appear in colleges and universities in small numbers, and we began to explore their use (Sowell and Fuller, 1990). Since then, our thinking has changed substantially, moving away from having computers serve as patient teachers of the classical curriculum, and toward using them as professional tools—to extend, to magnify, to expand, and to enhance human reasoning. This article deals with the issues related to students learning to use computers as such professional tools. Two qualitative data sources inform this paper. The first is a recent doctoral dissertation consisting of a case study of a ‘mathematical methods in physics’ course that incorporated the use of Maple™* software (Runge, 1997). The other is an evaluation of a new undergraduate course, ‘multimedia physics,’ that sought to integrate mathematics and physics content, and involved the use of many media forms (Pytlik Z. and Spiegel, 1997)

Bridging psychology and biology - the analysis of individuals in groups

Biological systems are particularly prone to variation, and the authors argue that such variation must be regarded as important data in its own right. The authors describe a method in which individual differences are studied within the framework of a general theory of the population as a whole and illustrate how this method can be used to address three types of issues: the nature of the mechanisms that give rise to a specific ability, such as mental imagery; the role of psychological or biological mediators of environmental challenges, such as the biological bases for differences in dispositional mood; and the existence of processes that have nonadditive effects with behavioral and physiological variables, such as factors that modulate the response to stress and its effects on the immune response. Variation occurs around every central tendency, bu