473 research outputs found
Nimbus 7 solar backscatter ultraviolet (SBUV) ozone products user's guide
Three ozone tape products from the Solar Backscatter Ultraviolet (SBUV) experiment aboard Nimbus 7 were archived at the National Space Science Data Center. The experiment measures the fraction of incoming radiation backscattered by the Earth's atmosphere at 12 wavelengths. In-flight measurements were used to monitor changes in the instrument sensitivity. Total column ozone is derived by comparing the measurements with calculations of what would be measured for different total ozone amounts. The altitude distribution is retrieved using an optimum statistical technique for the inversion. The estimated initial error in the absolute scale for total ozone is 2 percent, with a 3 percent drift over 8 years. The profile error depends on latitude and height, smallest at 3 to 10 mbar; the drift increases with increasing altitude. Three tape products are described. The High Density SBUV (HDSBUV) tape contains the final derived products - the total ozone and the vertical ozone profile - as well as much detailed diagnostic information generated during the retrieval process. The Compressed Ozone (CPOZ) tape contains only that subset of HDSBUV information, including total ozone and ozone profiles, considered most useful for scientific studies. The Zonal Means Tape (ZMT) contains daily, weekly, monthly and quarterly averages of the derived quantities over 10 deg latitude zones
Calculation of the properties of the rotational bands of Gd
We reexamine the long-standing problem of the microscopic derivation of a
particle-core coupling model. We base our research on the Klein-Kerman
approach, as amended by D\"onau and Frauendorf. We describe the formalism to
calculate energy spectra and transition strengths in some detail. We apply our
formalism to the rotational nuclei Gd, where recent experimental
data requires an explanation. We find no clear evidence of a need for Coriolis
attenuation.Comment: 27 pages, 13 uuencoded postscript figures. Uses epsf.st
Stability and Representation Dependence of the Quantum Skyrmion
A constructive realization of Skyrme's conjecture that an effective pion mass
``may arise as a self consistent quantal effect'' based on an ab initio quantum
treatment of the Skyrme model is presented. In this quantum mechanical Skyrme
model the spectrum of states with , which appears in the collective
quantization, terminates without any infinite tower of unphysical states. The
termination point depends on the model parameters and the dimension of the
SU(2) representation. Representations, in which the nucleon and
resonance are the only stable states, exist. The model is developed for both
irreducible and reducible representations of general dimension. States with
spin larger than 1/2 are shown to be deformed. The representation dependence of
the baryon observables is illustrated numerically.Comment: 19 pages, Late
Foundations of self-consistent particle-rotor models and of self-consistent cranking models
The Kerman-Klein formulation of the equations of motion for a nuclear shell
model and its associated variational principle are reviewed briefly. It is then
applied to the derivation of the self-consistent particle-rotor model and of
the self-consistent cranking model, for both axially symmetric and triaxial
nuclei. Two derivations of the particle-rotor model are given. One of these is
of a form that lends itself to an expansion of the result in powers of the
ratio of single-particle angular momentum to collective angular momentum, that
is essentual to reach the cranking limit. The derivation also requires a
distinct, angular-momentum violating, step. The structure of the result implies
the possibility of tilted-axis cranking for the axial case and full
three-dimensional cranking for the triaxial one. The final equations remain
number conserving. In an appendix, the Kerman-Klein method is developed in more
detail, and the outlines of several algorithms for obtaining solutions of the
associated non-linear formalism are suggested.Comment: 29 page
Do Black-Owned Banks Substitute for Payday Lenders? An Exploratory Study
The annualized interest rate charged on payday loans can reach 1,950 percent, whereas similar rates charged by banks are typically less than 25 percent. Also, persons borrowing from payday lenders and paying the higher interest rates are disproportionately lower-income Blacks. This provides an incentive for Blacks seeking loans to turn to banks rather than payday lenders. This may be more likely to happen when there are Black-owned banks in communities with greater percentages of Blacks. Indeed, offices of such banks may substitute for payday loan stores, providing a greater opportunity for Blacks to avoid the higher interest rates associated with payday lenders. We hypothesize that to the extent Black-owned banks substitute for payday there is a greater opportunity for lower-income Blacks to substitute/switch firms and thereby seek lower-cost loans. We do find that there are significantly fewer payday loan stores in counties where there are more Black bank offices
New Empirical Evidence on Factors Influencing the Yield on High-Grade Municipal Bonds
We investigate the impact of federal budget deficits and other factors on the ex-post and ex-ante real yields on high-grade municipal bonds. The estimation results reveal that both yields increase with the real yield on 30-year Moody’s Aaa-rated bonds and provisions in the Community Reinvestment Act but decrease with net capital inflows, the real GDP growth rate, and the average effective federal income tax rate. Most importantly, both yields are increasing functions of the federal budget deficit. These results support limiting the size of federal budget deficits to avoid the excessive crowding out of private investment spending
Quantitative imaging of concentrated suspensions under flow
We review recent advances in imaging the flow of concentrated suspensions,
focussing on the use of confocal microscopy to obtain time-resolved information
on the single-particle level in these systems. After motivating the need for
quantitative (confocal) imaging in suspension rheology, we briefly describe the
particles, sample environments, microscopy tools and analysis algorithms needed
to perform this kind of experiments. The second part of the review focusses on
microscopic aspects of the flow of concentrated model hard-sphere-like
suspensions, and the relation to non-linear rheological phenomena such as
yielding, shear localization, wall slip and shear-induced ordering. Both
Brownian and non-Brownian systems will be described. We show how quantitative
imaging can improve our understanding of the connection between microscopic
dynamics and bulk flow.Comment: Review on imaging hard-sphere suspensions, incl summary of
methodology. Submitted for special volume 'High Solid Dispersions' ed. M.
Cloitre, Vol. xx of 'Advances and Polymer Science' (Springer, Berlin, 2009);
22 pages, 16 fig
Central Nervous System Siderosis Associated with Multiple Cerebral Aneurysms: Literature Review and Description of an Additional Case
Background: Superficial siderosis (SS) of the central nervous system is a rare disease characterized by deposition of hemosiderin along the leptomeninges due to chronic or recurrent bleeding into the subarachnoid space. The association of unruptured intracranial aneurysm (IA) and cortical SS is quite rare. Methods: A systematic literature review to assess possible commonalities and/or differences of previous reported cases was undertaken. We report an additional case from our institution. Results: A 40-year-old woman presented with a history of generalized seizures over the past year. There was no clinical history suggestive of aneurysm rupture. Magnetic resonance imaging revealed 2 aneurysms of the right middle cerebral artery (MCA) bifurcation associated with hemosiderin deposition along the right sylvian fissure and a third aneurysm of the left MCA bifurcation. Magnetic resonance imaging showed wall enhancing thickening of the larger right MCA aneurysm. The patient underwent surgical clipping of all 3 MCA aneurysms in a staged procedure. Histological examination revealed hemosiderin deposits within the aneurysm wall and surrounding gliosis. Conclusions: Our literature review found 24 reported cases of unruptured IA associated with cortical SS. The possible source for leakages could be neovessels visible in IA walls. The case reported illustrates an uncommon presentation of recurrent bleeding from an IA as a source of SS. The presence of an apparently unruptured IA surrounded by cortical SS on imaging studies is of high relevance as this should be considered a sign of aneurysm wall instability and should indicate prompt treatment
Nimbus-7 TOMS Version 7 Calibration
This report describes an improved instrument characterization used for the Version 7 processing of the Nimbus-7 Total Ozone Mapping Spectrometer (TOMS) data record. An improved internal calibration technique referred to as spectral discrimination is used to provide long-term calibration precision of +/- 1%/decade in total column ozone amount. A revised wavelength scale results in a day one calibration that agrees with other satellite and ground-based measurements of total ozone, while a wavelength independent adjustment of the initial radiometric calibration constants provides good agreement with surface reflectivity measured by other satellite-borne ultraviolet measurements. The impact of other aspects of the Nimbus-7 TOMS instrument performance are also discussed. The Version 7 data should be used in all future studies involving the Nimbus-7 TOMS measurements of ozone. The data are available through the NASA Goddard Space Flight Center's Distributive Active Archive Center (DAAC)
Interventional magnetic-resonance-guided cryotherapy combined with microsurgery for recurrent glioblastoma: An innovative treatment?
Background: Glioblastoma invariably recurs after primary Stupp tumor therapy and portends a poor prognosis. Cryoablation is a well-established treatment strategy for extra-cranial tumors. The safety and efficacy of interventional MR-guided cryoablation (iMRgC) has not been explored in recurrent glioblastoma. Methods: A retrospective analysis of data collected over a period of 24 months was performed. The inclusion criteria were: (I) recurrent glioblastoma despite Stupp protocol; (II) MRI followed by histological confirmation of recurrent glioblastoma; (III) location allowing iMRgC followed by microsurgical resection; and (IV) patient's consent. The primary objective was to assess feasibility in terms of complications. The secondary objective was to analyze progression-free survival (PFS), post-iMRgC survival and overall survival (OS). Results: The study included 6 patients, with a mean age of 67 ± 7.6 years [range, 54–70 years]. No major complications were observed. Median PFS was 7.5 months [IQR 3.75–9.75] and 6-month PFS was 50%. Median post-iMRgC survival was 9 months [IQR 7.5–15.25] and 6-month post-iMRgC survival was 80%. Median OS was 22.5 months [IQR 21.75–30]. Conclusion: iMRgC for recurrent glioblastoma demonstrated a good safety profile, with no major complications. Our data suggest improved PFS and OS. Trial registration number: No. IRB00011687 retrospectively registred on July 7th 2021
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