Recursive partitioned inversion of large (1500 x 1500) symmetric matrices

A recursive algorithm was designed to invert large, dense, symmetric, positive definite matrices using small amounts of computer core, i.e., a small fraction of the core needed to store the complete matrix. The described algorithm is a generalized Gaussian elimination technique. Other algorithms are also discussed for the Cholesky decomposition and step inversion techniques. The purpose of the inversion algorithm is to solve large linear systems of normal equations generated by working geodetic problems. The algorithm was incorporated into a computer program called SOLVE. In the past the SOLVE program has been used in obtaining solutions published as the Goddard earth models

ATP-induced calcium mobilization and inositol 1,4,5-trisphosphate formation in H-35 hepatoma cells

AbstractAddition of ATP (but not epinephrine, angiotensin II, vasopressin, or platelet-activating factor) to H-35 hepatoma cells whose cellular lipids have been pre-labelled with [3H]inositol, causes a rapid increase in [3H]inositol trisphosphate. In H-35 cells pre-incubated in the presence of 45Ca2+, ATP causes a similarly rapid release of 45Ca2+. The concentration-effect relationships for inositol trisphosphate formation and Ca2+ efflux are similar to those reported previously for differentiated hepatocytes. These results demonstrate that at least one of the Ca2+-mobilizing receptors normally found on hepatocytes is functionally retained in the H-35 hepatoma cell line and thus could provide a useful model for the study of these receptor mechanisms in liver

Modeling of Interstellar Scintillation Arcs from Pulsar B1133+16

The parabolic arc phenomenon visible in the Fourier analysis of the scintillation spectra of pulsars provides a new method of investigating the small scale structure in the ionized interstellar medium (ISM). We report archival observations of the pulsar B1133+16 showing both forward and reverse parabolic arcs sampled over 14 months. These features can be understood as the mutual interference between an assembly of discrete features in the scattered brightness distribution. By model-fitting to the observed arcs at one epoch we obtain a ``snap-shot'' estimate of the scattered brightness, which we show to be highly anisotropic (axial ratio >10:1), to be centered significantly off axis and to have a small number of discrete maxima, which are coarser the speckle expected from a Kolmogorov spectrum of interstellar plasma density. The results suggest the effects of highly localized discrete scattering regions which subtend 0.1-1 mas, but can scatter (or refract) the radiation by angles that are five or more times larger.Comment: 14 pages, 4 figures, submitted to Astrophysical Journa

Extremely Anisotropic Scintillations

A small number of quasars exhibit interstellar scintillation on time-scales less than an hour; their scintillation patterns are all known to be anisotropic. Here we consider a totally anisotropic model in which the scintillation pattern is effectively one-dimensional. For the persistent rapid scintillators J1819+3845 and PKS1257-326 we show that this model offers a good description of the two-station time-delay measurements and the annual cycle in the scintillation time-scale. Generalising the model to finite anisotropy yields a better match to the data but the improvement is not significant and the two additional parameters which are required to describe this model are not justified by the existing data. The extreme anisotropy we infer for the scintillation patterns must be attributed to the scattering medium rather than a highly elongated source. For J1819+3845 the totally anisotropic model predicts that the particular radio flux variations seen between mid July and late August should repeat between late August and mid November, and then again between mid November and late December as the Earth twice changes its direction of motion across the scintillation pattern. If this effect can be observed then the minor-axis velocity component of the screen and the orientation of that axis can both be precisely determined. In reality the axis ratio is finite, albeit large, and spatial decorrelation of the flux pattern along the major axis may be observable via differences in the pairwise fluxes within this overlap region; in this case we can also constrain both the major-axis velocity component of the screen and the magnitude of the anisotropy.Comment: 5 pages, 4 figures, MNRAS submitte

The Ursinus Weekly, April 16, 1917

Varsity nine loses close game • Military training officially instituted • Hamilton Holt on Japan to-day • Zwinglian prize essay: The indifference of youth • First aid class • Seminary notes • Christian organizations • Literary societies • On the campus • Our spring birdshttps://digitalcommons.ursinus.edu/weekly/2589/thumbnail.jp

Violation of Chandrasekhar Mass Limit: The Exciting Potential of Strongly Magnetized White Dwarfs

We consider a relativistic, degenerate, electron gas under the influence of a strong magnetic field, which describes magnetized white dwarfs. Landau quantization changes the density of states available to the electrons, thus modifying the underlying equation of state. In the presence of very strong magnetic fields a maximum of either one, two or three Landau level(s) is/are occupied. We obtain the mass-radius relations for such white dwarfs and their detailed investigation leads us to propose the existence of white dwarfs having a mass ~2.3M_Sun, which overwhelmingly exceeds the Chandrasekhar mass limit.Comment: 10 pages including 4 figures; received Honorable Mention for the Gravity Research Foundation 2012 Awards for Essays on Gravitation; version to appear in IJMP

Modifying the Diabetes Prevention Program to Adolescents in a School Setting: A Feasibility Study

The growing epidemic of overweight children has led to a higher prevalence of youth being diagnosed with diabetes, particularly type 2 diabetes. The current study modified the Diabetes Prevention Program (DPP) for use with 7th–10th graders in a school setting. The DPP is an evidence-based lifestyle intervention program that has been translated successfully in various adult settings. Yet the feasibility of modifying the DPP for use with middle and high school students has not been documented. A multidisciplinary university research team collaborated with a local charter school to include a modified DPP as part of the curriculum for one semester. Pre- and posttests included food knowledge, health locus of control, BMI, and performance on the 12-minute Cooper walk/run test. Findings suggest tentatively that the modified DPP was successful at increasing food knowledge and awareness of more rigorous physical activity as well as their association to improved health outcomes. Equally as important, results demonstrate that it is feasible to conduct interventions targeting healthy weight among adolescents in school-based settings by incorporating them in the curriculum.</jats:p

Trends in Resource Utilization by Children with Neurological Impairment in the United States Inpatient Health Care System: A Repeat Cross-Sectional Study

Jay Berry and colleagues report findings from an analysis of hospitalization data in the US, examining the proportion of inpatient resources attributable to care for children with neurological impairment