4,093 research outputs found
Estimating sunspot number
An empirical method is developed to predict certain parameters of future solar activity cycles. Sunspot cycle statistics are examined, and curve fitting and linear regression analysis techniques are utilized
Application of the Hughes-LIU algorithm to the 2-dimensional heat equation
An implicit explicit algorithm for the solution of transient problems in structural dynamics is described. The method involved dividing the finite elements into implicit and explicit groups while automatically satisfying the conditions. This algorithm is applied to the solution of the linear, transient, two dimensional heat equation subject to an initial condition derived from the soluton of a steady state problem over an L-shaped region made up of a good conductor and an insulating material. Using the IIT/PRIME computer with virtual memory, a FORTRAN computer program code was developed to make accuracy, stability, and cost comparisons among the fully explicit Euler, the Hughes-Liu, and the fully implicit Crank-Nicholson algorithms. The Hughes-Liu claim that the explicit group governs the stability of the entire region while maintaining the unconditional stability of the implicit group is illustrated
Progression of myopathology in Kearns-Sayre syndrome
We report on the progression of myopathology by comparing two biopsies from a patient with a Kearns-Sayre-Syndrome. The first biopsy was taken in 1979 and showed 10% ragged-red fibers. Myopathic changes were slight including internal nuclei and fiber splitting in 10% of the fibers. Electron microscopy revealed typical mitochondrial abnormalities with regard to number and shape. In 1989 a second biopsy was performed for an extended analysis of mitochondrial DNA. This time less than 5% of all fibers were ragged-red. Severe myopathic changes could be detected which so far has rarely been reported in mitochondrial cytopathy
Wavelet solution of variable order pseudodifferential equations
Sobolev spaces H m(x)(I) of variable order 0<m(x)<1 on an interval Iââ arise as domains of Dirichlet forms for certain quadratic, pure jump Feller processes X tââ with unbounded, state-dependent intensity of small jumps. For spline wavelets with complementary boundary conditions, we establish multilevel norm equivalences in H m(x)(I) and prove preconditioning and wavelet matrix compression results for the variable order pseudodifferential generators A of X. Sufficient conditions on A to satisfy a GĂ„rding inequality in H m(x)(I) and time-analyticity of the semigroup T t associated with the Feller process X t are established. As application, wavelet-based algorithms of log-linear complexity are obtained for the valuation of contingent claims on pure jump Feller-LĂ©vy processes X t with state-dependent jump intensity by numerical solution of the corresponding Kolmogoroff equation
Restricted equilibrium ensembles: Exact equation of state of a model glass
We investigate the thermodynamic properties of a toy model of glasses: a
hard-core lattice gas with nearest neighbor interaction in one dimension. The
time-evolution is Markovian, with nearest-neighbor and next-nearest neighbor
hoppings, and the transition rates are assumed to satisfy detailed balance
condition, but the system is non-ergodic below a glass temperature. Below this
temperature, the system is in restricted thermal equilibrium, where both the
number of sectors, and the number of accessible states within a sector grow
exponentially with the size of the system. Using partition functions that sum
only over dynamically accessible states within a sector, and then taking a
quenched average over the sectors, we determine the exact equation of state of
this system.Comment: 6 pages, 2 figure
Film calibration for the Skylab/ATM S-056 X-ray telescope
The sensitometry and film calibration effort for the Skylab/ATM S-056 X-ray telescope is summarized. The apparatus and procedures used are described together with the two types of flight film used, Kodak SO-212 and SO-242. The sensitometry and processing of the flight film are discussed, and the results are presented in the form of the characteristic curves and related data. The use of copy films is also discussed
Evidence of a high incidence of subclinically affected calves in a herd of cattle with fatal cases of Bovine Neonatal Pancytopenia (BNP).
BACKGROUND: Bovine Neonatal Pancytopenia (BNP) is a disease of calves characterised by bone marrow trilineage hypoplasia, mediated by ingestion of alloantibodies in colostrum. Suspected subclinical forms of BNP have been reported, suggesting that observed clinical cases may not represent the full extent of the disease. However to date there are no objective data available on the incidence of subclinical disease or its temporal distribution. This study aimed to 1) ascertain whether subclinical BNP occurs and, if so, to determine the incidence on an affected farm and 2) determine whether there is evidence of temporal clustering of BNP cases on this farm. To achieve these aims, haematological screening of calves born on the farm during one calving season was carried out, utilising blood samples collected at defined ages. These data were then analysed in comparison to data from both known BNP-free control animals and histopathologically confirmed BNP cases. An ordinal logistic regression model was used to create a composite haematology score to predict the probabilities of calves being normal, based on their haematology measurements at 10â14 days old. RESULTS: This study revealed that 15% (21 of 139) of the clinically normal calves on this farm had profoundly abnormal haematology (<5% chance of being normal) and could be defined as affected by subclinical BNP. Together with clinical BNP cases, this gave the study farm a BNP incidence of 18%. Calves with BNP were found to be distributed throughout the calving period, with no clustering, and no significant differences in the date of birth of cases or subclinical cases were found compared to the rest of the calves. This study did not find any evidence of increased mortality or increased time from birth to sale in subclinical BNP calves but, as the study only involved a single farm and adverse effects may be determined by other inter-current diseases it remains possible that subclinical BNP has a detrimental impact on the health and productivity of calves under certain circumstances. CONCLUSIONS: Subclinical BNP was found to occur at a high incidence in a herd of cattle with fatal cases of BNP
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