Theoretical Setting of Inner Reversible Quantum Measurements

We show that any unitary transformation performed on the quantum state of a closed quantum system, describes an inner, reversible, generalized quantum measurement. We also show that under some specific conditions it is possible to perform a unitary transformation on the state of the closed quantum system by means of a collection of generalized measurement operators. In particular, given a complete set of orthogonal projectors, it is possible to implement a reversible quantum measurement that preserves the probabilities. In this context, we introduce the concept of "Truth-Observable", which is the physical counterpart of an inner logical truth.Comment: 11 pages. More concise, shortened version for submission to journal. References adde

Exchange ions produced by an ion propulsion system

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76181/1/AIAA-2001-968-867.pd

Abundance and Diversity of Organohalide-Respiring Bacteria in Lake Sediments Across a Geographical Sulfur Gradient

Across the U.S. Upper Midwest, a natural geographical sulfate gradient exists in lakes. Sediment grab samples and cores were taken to explore whether this sulfur gradient impacted organohalide-respiring Chloroflexi in lake sediments. Putative organohalide-respiring Chloroflexi were detected in 67 of 68 samples by quantitative polymerase chain reaction. Their quantities ranged from 3.5 × 104 to 8.4 × 1010 copies 16S rRNA genes g−1 dry sediment and increased in number from west to east, whereas lake sulfate concentrations decreased along this west-to-east transect. A terminal restriction fragment length polymorphism (TRFLP) method was used to corroborate this inverse relationship, with sediment samples from lower sulfate lakes containing both a higher number of terminal restriction fragments (TRFs) belonging to the organohalide-respiring Dehalococcoidetes, and a greater percentage of the TRFLP amplification made up by Dehalococcoidetes members. Statistical analyses showed that dissolved sulfur in the porewater, measured as sulfate after oxidation, appeared to have a negative impact on the total number of putative organohalide-respiring Chloroflexi, the number of Dehalococcoidetes TRFs, and the percentage of the TRFLP amplification made up by Dehalococcoidetes. These findings point to dissolved sulfur, presumably present as reduced sulfur species, as a potentially controlling factor in the natural cycling of chlorine, and perhaps as a result, the natural cycling of some carbon as well

Day-night asymmetries of low-energy electrons in Saturn's inner magnetosphere

We examine the day-night asymmetry of near-equatorial low energy (12-100 eV) electron fluxes measured by Cassini from July 1, 2004 through April 1, 2010. This energy range is also known to be associated with interchange injections. The electrons are separated into field-aligned (0 degrees to 20 degrees and 160 degrees to 180 degrees) pitch angles and trapped (70 degrees to 110 degrees) pitch angles. There is a stronger day-night asymmetry for the trapped than the field-aligned electrons, but both show enhanced energy fluxes on the nightside relative to the dayside. The dayside electron fluxes decrease sharply at an L-shell of 8, while the nightside electrons exhibit a slow decline in to L = 5. Our finding, along with previous research of high energy electrons, shows that this asymmetry is energy independent. This suggests that interchange injections are stronger, and therefore penetrate deeper into the magnetosphere, on the nightside

Self-reported pregnancy exposures and placental DNA methylation in the MARBLES prospective autism sibling study.

Human placenta is a fetal-derived tissue that offers a unique sample of epigenetic and environmental exposures present in utero. In the MARBLES prospective pregnancy study of high-risk younger siblings of children with autism spectrum disorder (ASD), pregnancy and environmental factors collected by maternal interviews were examined as predictors of placental DNA methylation, including partially methylated domains (PMDs), an embryonic feature of the placental methylome. DNA methylation data from MethylC-seq analysis of 47 placentas of children clinically diagnosed at 3 years with ASD or typical development using standardized assessments were examined in relation to: child's gestational age, birth-weight, and diagnosis; maternal pre-pregnancy body mass index, smoking, education, parity, height, prenatal vitamin and folate intake; home ownership; pesticides professionally applied to lawns or gardens or inside homes, pet flea/tick pouches, collars, or soaps/shampoos used in the 3 months prior to or during pregnancy. Sequencing run, order, and coverage, and child race and sex were considered as potential confounders. Akaike information criterion was used to select the most parsimonious among candidate models. Final prediction models used sandwich estimators to produce homoscadisticity-robust estimates of the 95% confidence interval (CI) and P-values controlled the false discovery rate at 5%. The strongest, most robust associations were between pesticides professionally applied outside the home and higher average methylation over PMDs [0.45 (95% CI 0.17, 0.72), P = 0.03] and a reduced proportion of the genome in PMDs [-0.42 (95% CI - 0.67 to -0.17), P = 0.03]. Pesticide exposures could alter placental DNA methylation more than other factors

Designing an augmented reality exhibition: Leonardo's Impossible Machines

This paper discusses the origins, development and results of the animated and augmented reality aspects of the exhibition ‘Leonardo’s Impossible Machines’ that was developed at Ravensbourne University London and Birkbeck, University of London, with support from the Museo Galileo. The exhibition included novel reconstructions and visualisations of Leonardo’s perpetual motion machines from the Codex Forster, and the process is explained here, along with the challenges of mounting a combined physical and AR show

A Bevalac Calibration of a Scintillating Optical Fiber Hodoscope for Possible use on the Advanced Composition Explorer

As part of instrument definition activities for the Advanced Composition Explorer (ACE) we are evaluating a hodoscope comprised of scintillating fibers for possible use in the Cosmic Ray Isotope Spectrometer (CRIS). The hodoscope would determine the trajectories of individual cosmic ray nuclei which stop in the silicon solid state telescopes in CRIS. We report a preliminary analysis of data from a Dec., 1990 Bevalac calibration of a CRIS test model which consisted of a scintillating fiber hodosccpe, utilizing 200mm, square cross section scintillating fibers, and silicon detectors for dE/dx-Erot measurements. The positional resolution obtained in our preliminary data analysis is -60μm for angles from 0-30°. The detection efficiency for iron and silicon nuclei was determined to be >99% for beam angles of ≥ 20°

Hard X-ray variability of the black-hole candidate GRO J0422+32 during its 1992 outburst

We have studied the hard X-ray variability of the soft X-ray transient GRO J0422+32 with BATSE in the 20-100 keV energy band. Our analysis covers 180 days following the first X-ray detection of the source on 1992 August 5, fully covering its primary and secondary X-ray outburst. We computed power density spectra (PDSs) in the 20-50, 50-100, and 20-100 keV energy bands, in the frequency interval 0.002-0.488 Hz. The PDSs of GRO J0422+32 are approximately flat up to a break frequency, and decay as a power law above, with index ~1. The canonical anticorrelation between the break frequency and the power density at the break, observed in Cyg X-1 and other BHCs in the low state, is not observed in the PDSs of GRO J0422+32. We compare our results with those of similar variability studies of Cyg X-1. The relation between the spectral slope and the amplitude of the X-ray variations of GRO J0422+32 is similar to that of Cyg X-1; however, the relation between the hard X-ray flux and the amplitude of its variation is opposite to what has been found in Cyg X-1. Phase lags between the X-ray flux variations of GRO J0422+32 at high and low photon energies, could only be derived during the first 30 days of its outburst. During this period, the variations in the 50-100 keV lag those in the 20-50 keV energy band by an approximately constant phase difference of 0.039(3) rad in the frequency interval 0.02-0.20 Hz.Comment: 33 pages, including 14 postscript figures, AASTEX. To appear in ApJ 1999, March 1, vol. 513 #