15,721 research outputs found
Coxsackie B2 Virus Infection Causing Multiorgan Failure and Cardiogenic Shock in a 42-Year-Old Man
Infections from coxsackie B2 viruses often cause viral myocarditis and, only rarely, multisystem organ impairment. We present the unusual case of a 42-year-old man in whom coxsackie B2 virus infection caused multiorgan infection, necessitating distal pancreatectomy, splenectomy, renal dialysis, and venoarterial extracorporeal membrane oxygenation with mechanical ventilation. In addition, the patient had a rapid-eye-movement sleep-related conduction abnormality that caused frequent sinus pauses of longer than 10 s, presumably due to myocarditis from the coxsackievirus infection. He recovered after permanent pacemaker placement and was discharged from the hospital. We discuss our aggressive supportive care and the few other reports of multiorgan impairment from coxsackieviruses
Spherical codes, maximal local packing density, and the golden ratio
The densest local packing (DLP) problem in d-dimensional Euclidean space Rd
involves the placement of N nonoverlapping spheres of unit diameter near an
additional fixed unit-diameter sphere such that the greatest distance from the
center of the fixed sphere to the centers of any of the N surrounding spheres
is minimized. Solutions to the DLP problem are relevant to the realizability of
pair correlation functions for packings of nonoverlapping spheres and might
prove useful in improving upon the best known upper bounds on the maximum
packing fraction of sphere packings in dimensions greater than three. The
optimal spherical code problem in Rd involves the placement of the centers of N
nonoverlapping spheres of unit diameter onto the surface of a sphere of radius
R such that R is minimized. It is proved that in any dimension, all solutions
between unity and the golden ratio to the optimal spherical code problem for N
spheres are also solutions to the corresponding DLP problem. It follows that
for any packing of nonoverlapping spheres of unit diameter, a spherical region
of radius less than or equal to the golden ratio centered on an arbitrary
sphere center cannot enclose a number of sphere centers greater than one more
than the number that can be placed on the region's surface.Comment: 12 pages, 1 figure. Accepted for publication in the Journal of
Mathematical Physic
Microprogram scheme for automatic recovery from computer error
Microprogram scheme enables computer to recover from failure in one of its two central processing units during time duration of instruction in which failure occurs. Microprogram advantages include - /1/ built-in interpretive capability, /2/ selection of processing interrupts by priority, and /3/ economical use of bootstrap sequence
General Rotorcraft Aeromechanical Stability Program (GRASP): Theory manual
The general rotorcraft aeromechanical stability program (GRASP) was developed to calculate aeroelastic stability for rotorcraft in hovering flight, vertical flight, and ground contact conditions. GRASP is described in terms of its capabilities and its philosophy of modeling. The equations of motion that govern the physical system are described, as well as the analytical approximations used to derive them. The equations include the kinematical equation, the element equations, and the constraint equations. In addition, the solution procedures used by GRASP are described. GRASP is capable of treating the nonlinear static and linearized dynamic behavior of structures represented by arbitrary collections of rigid-body and beam elements. These elements may be connected in an arbitrary fashion, and are permitted to have large relative motions. The main limitation of this analysis is that periodic coefficient effects are not treated, restricting rotorcraft flight conditions to hover, axial flight, and ground contact. Instead of following the methods employed in other rotorcraft programs. GRASP is designed to be a hybrid of the finite-element method and the multibody methods used in spacecraft analysis. GRASP differs from traditional finite-element programs by allowing multiple levels of substructure in which the substructures can move and/or rotate relative to others with no small-angle approximations. This capability facilitates the modeling of rotorcraft structures, including the rotating/nonrotating interface and the details of the blade/root kinematics for various types. GRASP differs from traditional multibody programs by considering aeroelastic effects, including inflow dynamics (simple unsteady aerodynamics) and nonlinear aerodynamic coefficients
Metal matrix composite analyzer (METCAN) user's manual, version 4.0
The Metal Matrix Composite Analyzer (METCAN) is a computer code developed at Lewis Research Center to simulate the high temperature nonlinear behavior of metal matrix composites. An updated version of the METCAN User's Manual is presented. The manual provides the user with a step by step outline of the procedure necessary to run METCAN. The preparation of the input file is demonstrated, and the output files are explained. The sample problems are presented to highlight various features of METCAN. An overview of the geometric conventions, micromechanical unit cell, and the nonlinear constitutive relationships is also provided
A fault-tolerant multiprocessor architecture for aircraft, volume 1
A fault-tolerant multiprocessor architecture is reported. This architecture, together with a comprehensive information system architecture, has important potential for future aircraft applications. A preliminary definition and assessment of a suitable multiprocessor architecture for such applications is developed
Costs and utilization of corn in seven Iowa counties
The demand for information on the cost of producing an acre or a bushel of corn has increased greatly during the past few years. This is especially true in Iowa, where corn is the basic crop.
Inquiring individuals are often disappointed when they learn that corn cost data are not available in simple terms of dollars and cents. This is so because they fail to realize the difficulties encountered in attempting to evaluate (measure the quantity as well as the quality of) some of the more important elements of cost. They also overlook the fact that the cost of producing corn depends largely on local soil, climatic and economic conditions and that these factors vary from one section of the state to another
How Much Mass do Supermassive Black Holes Eat in their Old Age?
We consider the distribution of local supermassive black hole Eddington
ratios and accretion rates, accounting for the dependence of radiative
efficiency and bolometric corrections on the accretion rate. We find that black
hole mass growth, both of the integrated mass density and the masses of most
individual objects, must be dominated by an earlier, radiatively efficient,
high accretion rate stage, and not by the radiatively inefficient low accretion
rate phase in which most local supermassive black holes are currently observed.
This conclusion is particularly true of supermassive black holes in elliptical
host galaxies, as expected if they have undergone merger activity in the past
which would fuel quasar activity and rapid growth. We discuss models of the
time evolution of accretion rates and show that they all predict significant
mass growth in a prior radiatively efficient state. The only way to avoid this
conclusion is through careful fine-tuning of the accretion/quasar timescale to
a value that is inconsistent with observations. Our results agree with a wide
range of observational inferences drawn from the quasar luminosity function and
X-ray background synthesis models, but our approach has the virtue of being
independent of the modeling of source populations. Models in which black holes
spend the great majority of their time in low accretion rate phases are thus
completely consistent both with observations implying mass gain in relatively
short, high accretion rate phases and with the local distribution of accretion
rates.Comment: 11 pages, 4 figures, matches version accepted to Ap
Silicon materials task of the low cost solar array project. Phase 3: Effect of impurities and processing on silicon solar cells
The 13th quarterly report of a study entitled an Investigation of the Effects of Impurities and Processing on Silicon Solar Cells is given. The objective of the program is to define the effects of impurities, various thermochemical processes and any impurity-process interactions on the performance of terrestrial silicon solar cells. The Phase 3 program effort falls in five areas: (1) cell processing studies; (2) completion of the data base and impurity-performance modeling for n-base cells; (3) extension of p-base studies to include contaminants likely to be introduced during silicon production, refining or crystal growth; (4) anisotropy effects; and (5) a preliminary study of the permanence of impurity effects in silicon solar cells. The quarterly activities for this report focus on tasks (1), (3) and (4)
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