A new technique for evaluating mesospheric momentum balance utilizing radars and satellite data

Copyright © 2000 European Geosciences UnionA new method for evaluating momentum balance in the mesosphere using radar and satellite data is presented. This method is applied to radar wind data from two medium frequency installations (near Adelaide, Australia and Christchurch, New Zealand) and satellite temperature data from the Improved Stratospheric and Mesospheric Sounder (ISAMS). Because of limitations in data availability and vertical extent, the technique can only be applied to evaluate the momentum balance at 80 km above the radar sites for May 1992. The technique allows the calculation of the residual terms in the momentum balance which are usually attributed to the effects of breaking gravity waves. Although the results are inconclusive above Adelaide, this method produces values of zonal and meridional residual accelerations above Christchurch which are consistent with expectation. In both locations it is apparent that geostrophic balance is a poor approximation of reality. (This result is not dependent on a mismatch between the radar and satellite derived winds, but rather is inherent in the satellite data alone.) Despite significant caveats about data quality the technique appears robust and could be of use with data from future instruments

A comparison between mesospheric wind measurements made near Christchurch (44°S, 173°E) using the high resolution doppler imager (HRDI) and a medium frequency (MF) radar

We report on the comparison of winds measured by a medium frequency (MF) radar near Christchurch, New Zealand, and by the high resolution doppler imager (HRDI). Previous comparisons have demonstrated that there can be significant differences in the winds obtained by the two techniques, and our results are no different. However, these data show relatively good agreement in the meridional direction, but large differences in the zonal direction, where the radar is regularly measuring the zonal wind as too easterly. To do the comparison, overpasses from the satellite must be obtained when it is close to the radar site. The radar data are averaged in time around the overpass because we know the radars sample phenomena which have spatial and temporal scales which make them invisible to HRDI. There are a limited number of overpass comparisons which limit our confidence in these results, but a detailed analysis of these data show that the proximity of the overpass is often an important factor in the differences obtained. Other factors examined include the influence of the local time of the overpass, and the amount of radar data averaged around the overpass time.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47866/1/585_2000_Article_180555.pd

The Devil's in the Tail: Residential Mortgage Finance and the U.S. Treasury

This paper seeks to contribute to the U.S. housing finance reform conversation by providing a critical assessment of the various types of policy proposals that have been offered. There appears to be a broad consensus to maintain explicit government guarantees for certain narrowly defined borrower populations, such as FHA insurance guarantees for low- and moderate-income and first-time homebuyers. However, the expected role of the federal government in the broader housing finance system is in dispute: ranging from no role; to insuring against only extreme or tail events; to insuring against all losses. However, most proposals agree that any public insurance be priced and available only for loans meeting pre-specified criteria in an effort to limit taxpayer exposure

Satellite data relay and platform locating in oceanography. Report of the In Situ Ocean Science Working Group

The present and future use of satellites to locate offshore platforms and relay data from in situ sensors to shore was examined. A system of the ARGOS type will satisfy the increasing demand for oceanographic information through data relay and platform location. The improved ship navigation provided by the Global Positioning System (GPS) will allow direct observation of currents from underway ships. Ocean systems are described and demand estimates on satellite systems are determined. The capabilities of the ARGOS system is assessed, including anticipated demand in the next decade

Reasonable efforts? Implementation of the reunification exception provisions of ASFA

The Adoption and Safe Families Act (ASFA) of 1997 includes provisions to deny reunification services under specified conditions and gives states latitude to develop any number of additional “aggravated circumstances” in which parents need not be offered services. California legislators have developed a relatively large number of conditions enabling agencies to bypass reunification services. Based upon a case record review involving 1,055 parents, this study attempts to identify the proportion of parents eligible for a reunification bypass, the proportion recommended to the courts, and the proportion of parents who were denied reunification services, and examines the characteristics of parents associated with reunification bypass recommendations. Based upon focus groups and interviews with child welfare and judicial personnel in six counties, the study also examines the implementation of reunification bypass provisions. Implications for public policy and practice are provided

Systemic absorption of oral vancomycin in a peripheral blood stem cell transplant patient with severe graft-versus-host disease of the gastrointestinal tract

Oral vancomycin is often considered the drug of choice for severe Clostridium difficile- associated disease due to both its efficacy and pharmacokinetics. The potential for absorption is not well described in patients with impaired gastrointestinal (GI) mucosa. We describe a case of significant and potentially toxic absorption of oral vancomycin in a peripheral blood stem cell transplant patient with grade IV graft-versus-host disease (GVHD) of the GI tract. In patients with GI GVHD clinicians need to be aware of the potential for oral absorption and, in select cases, monitoring of levels may be appropriate.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74898/1/j.1399-3062.2009.00426.x.pd

Poorest countries experience earlier anthropogenic emergence of daily temperature extremes

Understanding how the emergence of the anthropogenic warming signal from the noise of internal variability translates to changes in extreme event occurrence is of crucial societal importance. By utilising simulations of cumulative carbon dioxide (CO2) emissions and temperature changes from eleven earth system models, we demonstrate that the inherently lower internal variability found at tropical latitudes results in large increases in the frequency of extreme daily temperatures (exceedances of the 99.9th percentile derived from pre-industrial climate simulations) occurring much earlier than for mid-to-high latitude regions. Most of the world's poorest people live at low latitudes, when considering 2010 GDP-PPP per capita; conversely the wealthiest population quintile disproportionately inhabit more variable mid-latitude climates. Consequently, the fraction of the global population in the lowest socio-economic quintile is exposed to substantially more frequent daily temperature extremes after much lower increases in both mean global warming and cumulative CO2 emissions

Remote monitoring of off-grid renewable energy case studies in rural Malawi, Zambia, and Gambia

Increased understanding of off-grid renewable energy technology (RET) performance can assist in improving sustainability of such systems. The technologies for remote monitoring of RET deployments in developing countries are promising with various configurations and usages being tested. Recent applications of remote monitoring technologies in Malawi, Gambia, and Zambia are presented along with their respective strengths and weaknesses. The potential for remote monitoring applications to improve sustainability of off-grid RET is explored along with some theoretical directions of the technologies

Instability and Spatiotemporal Dynamics of Alternans in Paced Cardiac Tissue

We derive an equation that governs the spatiotemporal dynamics of small amplitude alternans in paced cardiac tissue. We show that a pattern-forming linear instability leads to the spontaneous formation of stationary or traveling waves whose nodes divide the tissue into regions with opposite phase of oscillation of action potential duration. This instability is important because it creates dynamically an heterogeneous electrical substrate for inducing fibrillation if the tissue size exceeds a fraction of the pattern wavelength. We compute this wavelength analytically as a function of three basic length scales characterizing dispersion and inter-cellular electrical coupling.Comment: 4 pages, 3 figures, submitted to PR