Distribution of slip from 11 M_w > 6 earthquakes in the northern Chile subduction zone

We use interferometric synthetic aperture radar, GPS, and teleseismic data to constrain the relative location of coseismic slip from 11 earthquakes on the subduction interface in northern Chile (23°–25°S) between the years 1993 and 2000. We invert body wave waveforms and geodetic data both jointly and separately for the four largest earthquakes during this time period (1993 M_w 6.8; 1995 M_w 8.1; 1996 M_w 6.7; 1998 M_w 7.1). While the location of slip in the teleseismic-only, geodetic-only, and joint slip inversions is similar for the small earthquakes, there are differences for the 1995 M_w 8.1 event, probably related to nonuniqueness of models that fit the teleseismic data. There is a consistent mislocation of the Harvard centroid moment tensor locations of many of the 6 6 earthquakes, as well as three M_w > 7 events from the 1980s. All of these earthquakes appear to rupture different portions of the fault interface and do not rerupture a limited number of asperities

21-cm signatures of residual HI inside cosmic HII regions during reionization

We investigate the impact of sinks of ionizing radiation on the reionization-era 21-cm signal, focusing on 1-point statistics. We consider sinks in both the intergalactic medium and inside galaxies. At a fixed filling factor of HII regions, sinks will have two main effects on the 21-cm morphology: (i) as inhomogeneous absorbers of ionizing photons they result in smaller and more widespread cosmic HII patches; and (ii) as reservoirs of neutral gas they contribute a non-zero 21-cm signal in otherwise ionized regions. Both effects damp the contrast between neutral and ionized patches during reionization, making detection of the epoch of reionization with 21-cm interferometry more challenging. Here we systematically investigate these effects using the latest semi-numerical simulations. We find that sinks dramatically suppress the peak in the redshift evolution of the variance, corresponding to the midpoint of reionization. As previously predicted, skewness changes sign at midpoint, but the fluctuations in the residual HI suppress a late-time rise. Furthermore, large levels of residual HI dramatically alter the evolution of the variance, skewness and power spectrum from that seen at lower levels. In general, the evolution of the large-scale modes provides a better, cleaner, higher signal-to-noise probe of reionization.Comment: Minor edits to agree with MNRAS published versio

Analysis of ALOPE data from Superflux

Remote sensing data collected with the airborne lidar oceanographic probing experiment (ALOPE) laser fluorosensor during the Superflux 1 and Superflux 2 experiments were analyzed using two techniques. A qualitative technique which requires no supplementary data provided a near-real-time estimate of relative abundance of the golden-brown and green phytoplankton color groups. Contour plots developed for the later mission are used to demonstrate the utility of this technique. A quantitative technique which requires supplementary data to define the attenuation coefficient provides chlorophyll a concentration by color group. The sum of the golden-brown and green chlorophyll a data yields total chlorophyll a values which may be compared with in situ data. As expected, the golden-brown population was dominant in the Chesapeake Bay and the Bay plume whereas the green population was dominant in shelf waters

Physical oceanographic investigations in the Eastern Bering and Chukchi Seas during the summer of 1947

New information on the physical properties of the waters in the eastern Bering and Chukchi seas is discussed. It shows that, in summer, the water masses of this area are complicated by the circulation and advective processes. In general, the southern Bering Sea water flows northward and is modified by warm low-salinity water from rivers along the Alaskan coast and from intrusions of cold high-salinity water from the western Bering Sea. This mixture of water funn els through the Bering Strait principally at the surface on the eastern side...

Proposed Changes to Social Security: An Analysis

Some 48 million Americans are expected to collect around $518 billion in Social Security benefits during 2005.  Of these, about 70 percent are retired workers.  The ratio of workers covered by Social Security to retirees is approximately three to one but will decrease to about two to one in the next generation.  Furthermore, at present, there are significantly more Social Security taxes collected than benefits paid; the excess is spent to help fund other government programs.  With the Baby Boomers starting to collect benefits in 2008 and large federal deficits already threatening to push interest rates higher, providing for future Social Security funding is being addressed.  This paper explores existing and future demands expected to be placed on Social Security and possible changes that may be implemented to ensure its long-term viability

Reading Ability as a Predictor of Student Success in Business School

For several years accounting faculty at a regional university observed that some of their students exhibited difficulty reading. This study of 235 sophomore, junior, and senior business majors enrolled in accounting classes examines the relationship between their reading abilities as measured by the Nelson-Denny Reading Test and their cumulative grade point averages (GPAs). The results indicate that students who have higher levels of reading comprehension and reading vocabulary have higher cumulative GPAs. Furthermore, the results indicate that about 16 percent of the students tested could not read at the first-year college level. This paper describes the testing and recommends that students’ reading abilities be factored into the admission processes

Adverse Changes In Faculty Behavior Resulting From Use Of Student Evaluations Of Teaching: A Case Study

Based on a detailed literature review and longitudinal analysis, this paper explores the possible underlying causes of the decline in the number of hours per week graduating business seniors indicated they studied during their senior year. The study was conducted at an AACSB accredited college of business at a regional university.  The study indicates that the decline in hours studied was likely an unintended result of using a process designed to demonstrate continuous improvement in teaching. The process utilized the Educational Testing Service’s SIR II student evaluation instrument as the only measure of teaching quality/effectiveness. The study concludes that the process may have pressured some instructors to sacrifice teaching rigor in an attempt to obtain more favorable student evaluations, thereby precipitating the decline in hours studied

Senior Citizens, Social Security, And Healthcare Costs

Based on an extensive literature review this paper discusses the interrelationships among the increasing numbers of Senior Citizens and the costs of Social Security and healthcare. This discussion includes information on Social Security pertaining to its funding and the Social Security Trust Funds. The paper notes that both the costs of Social Security and healthcare are directly related to improving healthcare. The ongoing improvements in healthcare result in increasing numbers of Senior Citizens who demand further improvements in healthcare. This leads to increases in longevity adding to healthcare and Social Security costs. Finally, the paper demonstrates the underlying complexities and the lack of consensus of possible changes to improve healthcare

Reducing The Downside Risk Of Not Receiving Anticipated Social Security Benefits By Using Personal Accounts

The government is not obligated to pay Social Security benefits and no one has the right to receive such benefits.  This paper presents the argument that opting for a personal account in conjunction with traditional Social Security is less risky than opting to have all of ones Social Security taxes go into traditional Social Security.  The overall downside risk of receiving lower than anticipated Social Security retirement income is reduced by diversifying to include personal accounts along with traditional Social Security.&nbsp