800 research outputs found
ITOS VHRR on-board data compression study
Data compression methods for ITOS VHRR data were studied for a tape recorder record-and playback application. A playback period of 9 minutes was assumed with a nominal 18 minute record period for a 2-to-1 compression ratio. Both analog and digital methods were considered with the conclusion that digital methods should be used. Two system designs were prepared. One is a PCM system and the other is an entropy-coded predictive-quantization, sometimes called entropy-coded DPCM or just DPCM, system. Both systems use data management principles to transmit only the necessary data. Both systems use a medium capacity standard tape recorder from specifications provided by the technical officer. The 10 to the 9th power bit capacity of the recorder is the basic limitation on the compression ratio. Both systems achieve the minimum desired 2 to 1 compression ratio. A slower playback rate can be used with the DPCM system due to a higher compression factor for better link performance at a given CNR in terms of bandwidth utilization and error rate. The report is divided into two parts. The first part summarizes the theoretical conclusions of the second part and presents the system diagrams. The second part is a detailed analysis based upon an empirically derived random process model arrived at from specifications and measured data provided by the technical officer
Monte Carlo simulation of wave sensing with a short pulse radar
A Monte Carlo simulation is used to study the ocean wave sensing potential of a radar which scatters short pulses at small off-nadir angles. In the simulation, realizations of a random surface are created commensurate with an assigned probability density and power spectrum. Then the signal scattered back to the radar is computed for each realization using a physical optics analysis which takes wavefront curvature and finite radar-to-surface distance into account. In the case of a Pierson-Moskowitz spectrum and a normally distributed surface, reasonable assumptions for a fully developed sea, it has been found that the cumulative distribution of time intervals between peaks in the scattered power provides a measure of surface roughness. This observation is supported by experiments
Universal approximation of multi-copy states and universal quantum lossless data compression
We have proven that there exists a quantum state approximating any multi-copy
state universally when we measure the error by means of the normalized relative
entropy. While the qubit case was proven by Krattenthaler and Slater (IEEE
Trans. IT, 46, 801-819 (2000); quant-ph/9612043), the general case has been
open for more than ten years. For a deeper analysis, we have solved the
mini-max problem concerning `approximation error' up to the second order.
Furthermore, we have applied this result to quantum lossless data compression,
and have constructed a universal quantum lossless data compression
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Report on the feasibility of using isotopes to source and age-date groundwater in Orange County water district`s Forebay region
From March to September 1995, the Isotope Sciences Division of Lawrence Livermore National Laboratory performed isotopic measurements on water in the Orange County Forebay region. The goal was to test the applicability of isotope techniques for determining the current groundwater flow paths and flow rates in the OCWD spreading facilities. Successful results could then be used to predict the fate of proposed reclaimed waste water recharge. Stable isotope measurements in surface waters and groundwaters in the Forebay region of the Orange County groundwater basin provided a general source indicator. The data defined three general groups: (1) groundwater derived from recharged Santa Ana River water (SAR),(2) groundwater resulting from a mixture of recharged Colorado River water and the SAR, and (3) groundwater recharged from the Santiago basin area. In the first group of data, recharge directly from the SAR flow was not readily distinguishable from groundwater recharged via the spreading ponds. Some groundwater samples from Forebay wells showed significant temporal variability in stable isotope values, while others remained constant throughout the study period. The temporal changes in the groundwater stable isotope signatures are believed to be controlled by similar variations in the stable isotope signatures of the surface water recharge. With further sampling, these seasonal isotopic variations may provide a viable tracer for young (<2 years) groundwater
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Isotopic investigation of recharge to a regional groundwater flow system, Great Basin, NV
Groundwater recharge processes were investigated in central Nevada by examining the relationships between the stable isotope ({delta}D and {delta}{sup 18}O) compositions of snowfall, snowmelt, alpine spring waters, and regional groundwaters. Snowmelt infiltration is inferred to he the dominant source of groundwater recharge in this region. Bulk snow cores collected throughout central Nevada near the time of maximum accumulation have {delta}D and {delta}{sup 18}O pairs that plot subparallel to the global meteoric water line (GMWL), but have negative d-values, implying kinetic isotope enrichments. Heavy isotope enrichments occur at the base of snowpacks due to fractionation during snow metamorphism, sometimes resulting in remarkably systematic isotopic variations. Ice crystals in the soil immediately beneath the snowpack can be strongly depleted in heavy isotopes relative to the overlying snow, implying fractionation or exchange with the snowpack. Late season ablation processes tend to homogenize isotopic variations between snowpack layers, and cause the bulk isotopic composition of the snowpack to become enriched in {sup 18}O by 2-3{per_thousand} relative to the composition during peak accumulation. The dynamic evolution of the snowpack and snowmelt isotopic compositions over time makes it difficult to directly ascertain groundwater recharge compositions without careful mass balance measurements. Preliminary evidence suggests that small local springs may be reasonable indicators of the integrated isotopic value of the snowmelt recharge in a particular area. Springs and snowmelt runoff samples collected throughout central Nevada during the peak runoff plot along a least squares regression line with the equation {delta}D = 7.3{delta}{sup 18}O - 7, which is similar to the line obtained for 28 metamorphosed snow cores collected during peak accumulation ({delta}D = 7.5{delta}{sup 18}O - 3). These results suggest that kinetic fractionation processes during snow metamorphism and ablation may largely account for the low d-values that are widely observed in groundwaters from both local and regional flow systems in Nevada
The Locality Problem in Quantum Measurements
The locality problem of quantum measurements is considered in the framework
of the algebraic approach. It is shown that contrary to the currently
widespread opinion one can reconcile the mathematical formalism of the quantum
theory with the assumption of the existence of a local physical reality
determining the results of local measurements. The key quantum experiments:
double-slit experiment on electron scattering, Wheeler's delayed-choice
experiment, the Einstein-Podolsky-Rosen paradox, and quantum teleportation are
discussed from the locality-problem point of view. A clear physical
interpretation for these experiments, which does not contradict the classical
ideas, is given.Comment: Latex, 40 pages, 7 figure
de Broglie waves as the "Bridge of Becoming" between quantum theory and relativity
It is hypothesized that de Broglie's 'matter waves' provide a dynamical basis
for Minkowski spacetime in an antisubstantivalist or relational account. The
relativity of simultaneity is seen as an effect of the de Broglie oscillation
together with a basic relativity postulate, while the dispersion relation from
finite rest mass gives rise to the differentiation of spatial and temporal
axes. Thus spacetime is seen as not fundamental, but rather as emergent from
the quantum level. A result by Solov'ev which demonstrates that time is not an
applicable concept at the quantum level is adduced in support of this claim.
Finally, it is noted that de Broglie waves can be seen as the "bridge of
becoming" discussed by Elitzur and Dolev (2005).Comment: Forthcoming in Foundations of Science; reference added to recent work
of Dolc
On the verge of Umdeutung in Minnesota: Van Vleck and the correspondence principle (Part One)
In October 1924, the Physical Review, a relatively minor journal at the time,
published a remarkable two-part paper by John H. Van Vleck, working in virtual
isolation at the University of Minnesota. Van Vleck combined advanced
techniques of classical mechanics with Bohr's correspondence principle and
Einstein's quantum theory of radiation to find quantum analogues of classical
expressions for the emission, absorption, and dispersion of radiation. For
modern readers Van Vleck's paper is much easier to follow than the famous paper
by Kramers and Heisenberg on dispersion theory, which covers similar terrain
and is widely credited to have led directly to Heisenberg's "Umdeutung" paper.
This makes Van Vleck's paper extremely valuable for the reconstruction of the
genesis of matrix mechanics. It also makes it tempting to ask why Van Vleck did
not take the next step and develop matrix mechanics himself.Comment: 82 page
Internally Electrodynamic Particle Model: Its Experimental Basis and Its Predictions
The internally electrodynamic (IED) particle model was derived based on
overall experimental observations, with the IED process itself being built
directly on three experimental facts, a) electric charges present with all
material particles, b) an accelerated charge generates electromagnetic waves
according to Maxwell's equations and Planck energy equation and c) source
motion produces Doppler effect. A set of well-known basic particle equations
and properties become predictable based on first principles solutions for the
IED process; several key solutions achieved are outlined, including the de
Broglie phase wave, de Broglie relations, Schr\"odinger equation, mass,
Einstein mass-energy relation, Newton's law of gravity, single particle self
interference, and electromagnetic radiation and absorption; these equations and
properties have long been broadly experimentally validated or demonstrated. A
specific solution also predicts the Doebner-Goldin equation which emerges to
represent a form of long-sought quantum wave equation including gravity. A
critical review of the key experiments is given which suggests that the IED
process underlies the basic particle equations and properties not just
sufficiently but also necessarily.Comment: Presentation at the 27th Int Colloq on Group Theo Meth in Phys, 200
Increased male reproductive success in Ts65Dn âDown syndromeâ mice
The Ts65Dn mouse is trisomic for orthologs of about half the genes on Hsa21. A number of phenotypes in these trisomic mice parallel those in humans with trisomy 21 (Down syndrome), including cognitive deficits due to hippocampal malfunction that are sufficiently similar to human that âtherapiesâ developed in Ts65Dn mice are making their way to human clinical trials. However, the impact of the model is limited by availability. Ts65Dn cannot be completely inbred and males are generally considered to be sterile. Females have few, small litters and they exhibit poor care of offspring, frequently abandoning entire litters. Here we report identification and selective breeding of rare fertile males from two working colonies of Ts65Dn mice. Trisomic offspring can be propagated by natural matings or by in vitro fertilization (IVF) to produce large cohorts of closely related siblings. The use of a robust euploid strain as recipients of fertilized embryos in IVF or as the female in natural matings greatly improves husbandry. Extra zygotes cultured to the blastocyst stage were used to create trisomic and euploid embryonic stem (ES) cells from littermates. We developed parameters for cryopreserving sperm from Ts65Dn males and used it to produce trisomic offspring by IVF. Use of cryopreserved sperm provides additional flexibility in the choice of oocyte donors from different genetic backgrounds, facilitating rapid production of complex crosses. This approach greatly increases the power of this important trisomic model to interrogate modifying effects of trisomic or disomic genes that contribute to trisomic phenotypes
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