Propagation of atmospheric model errors to gravity potential harmonics—impact on GRACE de-aliasing

High-frequency, time-varying mass redistributions in the ocean and atmosphere have an impact on GRACE gravity field solutions due to the space-time sampling characteristics of signal and orbit. Consequently, aliasing of these signals into the GRACE observations is present and needs to be taken into account during data analysis by applying atmospheric and oceanic model data (de-aliasing). As the accuracy predicted prior to launch could not yet be achieved in the analysis of real GRACE data, the de-aliasing process and related geophysical model uncertainties are regarded as a potential error source in GRACE gravity field determination. Therefore, this study aims to improve the de-aliasing process in order to obtain a more accurate GRACE gravity field time-series. As these time-series provide estimates for the integrated mass transport in the Earth system, like the global water cycle and solid Earth geophysical processes, any increase in accuracy will lead to improvements in the geophysical interpretation of the results. So in conclusion, improving the de-aliasing is of relevance for a better understanding of geophysical processes. By no longer regarding the atmosphere and ocean model output as error-free, deeper insight into the impact of such uncertainties on the de-aliasing and on the resulting GRACE gravity field models can be obtained. For this purpose, in a first step, a full error propagation of the atmospheric and oceanic model parameters up to the de-aliasing gravity field coefficients is performed and the GRACE K-Band-Satellite-to-Satellite Tracking (KBR-SST) residuals, as an intermediate gravity field result, are analysed. The paper reviews the standard GRACE de-aliasing process and presents the mathematical model applied for the error propagation. Specifically, the effect of uncertainties in the atmospheric input parameters (temperature, surface pressure, specific humidity, geopotential) on the gravity field potential coefficients used for de-aliasing is shown in several scenarios. Finally, the impact of de-aliasing products (with and without error propagation) on a GRACE gravity field solution is investigated on the level of observation residuals. From the results obtained in this study it can be concluded that with respect to the current GRACE error budget, atmospheric model uncertainties do not play a prominent role in the error budget of current GRACE gravity field solutions. Nevertheless, in order to fully exploit the GRACE measurements towards the baseline accuracy, an optimized de-aliasing is needed. In this case, GRACE gravity field solutions are sensitive to uncertainties in atmospheric and oceanic models. Thus, the associated geophysical model errors shall be taken into account in the de-aliasing proces

Pre-migration tuberculosis screening - do be aware that the first step is always the hardest.

As the proportion of foreign-born persons among TB notifications continues to rise, Japan is preparing to introduce pre-migration TB screening for those coming from selected countries, who are intending to stay for more than 90 days. It has announced that the programme will commence in 2020. In this review, the authors examine the experiences from two countries which already have years of experience in operating pre-migration TB screening, namely the United Kingdom and Australia. The authors point out that both countries have developed strong health information system not only to collect and analyse screening results, but also to use the data to effectively monitor and evaluate the screening programme itself. The critical role which health information system plays within pre-migration screening is often overlooked. Here we argue that Japan, as with any other countries planning to introduce pre-migration screening for TB, must also plan for data management

Sending Children Who Are Medically Fragile to School

This study examined the decisions to send children who are medically fragile to school-based programming. A case study including parent interviews, as well as pediatrician surveys regarding the education of children who are medically fragile. Benefits, as well as problems, were discussed and were associated with children who are medically fragile attending school. Guidelines were presented for decisions to send children who are medically fragile to school. Also, conclusions were drawn from the literature and recommendations were made for the future of schooling for children who are medically fragile

Free radical scavenging reverses fructose-induced salt-sensitive hypertension

We have previously reported that a moderate dietary supplementation of 20% fructose but not glucose leads to a salt-sensitive hypertension related to increased proximal sodium-hydrogen exchanger activity and increased renal sodium retention. We also found that while high salt increased renal nitric oxide formation, this was retarded in the presence of fructose intake. We hypothesized that at least part of the pathway leading to fructose-induced salt-sensitive hypertension could be due to fructose-induced formation of reactive oxygen species and inappropriate stimulation of renin secretion, all of which would contribute to an increase in blood pressure. We found that both 20% fructose intake and a high-salt diet stimulated 8-isoprostane excretion. The superoxide dismutase (SOD) mimetic tempol significantly reduced this elevated excretion. Next, we placed rats on a high-salt diet (4%) for 1 week in combination with normal rat chow or 20% fructose with or without chronic tempol administration. A fructose plus high-salt diet induced a rapid increase (15 mmHg) in systolic blood pressure and reversed high salt suppression of plasma renin activity. Tempol treatment reversed the pressor response and restored high salt suppression of renin. We conclude that fructose-induced salt-sensitive hypertension is driven by increased renal reactive oxygen species formation associated with salt retention and an enhanced renin-angiotensin system

The dynamics of structure across scale in a primaeval European beech stand

We explored the spatial dynamics of structural complexity in the living tree stratum in a 10-ha stem-mapped portion of an unmanaged nearly monospecific primaeval European beech (Fagus sylvatica L.) stand in Western Ukraine. Development dynamics were assessed through patterns of change in association across scales (from 156.25 m2 to 1 ha) among stand basal area (BA), tree density, average and standard deviation (STD) of tree diameters, Gini coefficient (GC), the index of spatial aggregation (R), diameter differentiation index (T) and structural complexity index (SCI). At the smallest scales, STD, GC and T contrasted patches of differing structure (i.e. large between-patch structural differences). As subplot area increased and incorporated more heterogeneity, structural differences between subplots became more subtle and measures of tree-to-tree size variation (STD, T) lost sensitivity whereas it was gained for measures of overall within-patch heterogeneity (GC). At small scales, differences in STD largely explained variation in the SCI (between-plot variability); at intermediate scales, size differences among neighbours (T) explained most of the variability; and at large scales, plot-level differences in BA and its allocation to trees of different sizes (GC; within-plot variability) overrode size differences among nearest neighbours. The characterization of a fine-scale shifting mosaic of patches in different development stages appears to hold for primaeval beech forests in this spatially contiguous area of relatively large extent. The coalescence of small-scale processes into neighbourhoods, and then into patches at larger scales, may be best captured by the change in associations among structural measures across scales because the structural imprint of gap dynamics extends considerably beyond the scale of individual gap

VLBA Continuum and H I Absorption Observations of the Ultra-Luminous Infrared Galaxy IRAS 17208-0014

We present phase-referenced VLBI observations of the radio continuum emission from, and the neutral hydrogen 21 cm absorption toward, the Ultra-Luminous Infrared Galaxy IRAS 17208-0014. The observations were carried out at 1362 MHz using the Very Long Baseline Array, including the phased Very Large Array as an element. The high-resolution radio continuum images reveal a nuclear starburst region in this galaxy, which is composed of diffuse emission approximately 670 x 340 pc on the plane of the sky, and a number of compact sources. These sources are most likely to be clustered supernova remnants and/or luminous radio supernovae. Their brightness temperatures range over (2.2-6.6) x 10^{5} K, with radio spectral luminosities between (1-10) x 10^{21} W Hz^{-1}. The total VLBI flux density of the starburst region is ~52 mJy, which is about 50% of the total flux density detected with the VLA at arcsecond resolution. For this galaxy, we derive a massive star formation rate of ~84pm13 M{_\odot} yr^{-1}, and a supernova rate of ~4pm1 yr^{-1}. H I absorption is detected in multiple components with optical depths ranging between 0.3 and 2.5, and velocity widths between 58 and 232 km s^{-1}. The derived column densities, assuming T_{s}=100 K, range over (10-26) x 10^{21} cm^{-2}. The H I absorption shows a strong velocity gradient of 453 km s^{-1} across 0.36 arcsec (274 pc). Assuming Keplerian motion, the enclosed dynamical mass is about 2.3 x 10^9 sin^{-2}i M{_\odot}, comparable to the enclosed dynamical mass estimated from CO observations.Comment: 26 pages total, 6 figures. ApJ accepted. To appear in the April 1, 2003 issue of ApJ. For a version with better images, see http://www.aoc.nrao.edu/~emomjian/IRAS.p

Dynamics of the Destruction and Rebuilding of a Dipole Gap in Glasses

After a strong electric bias field was applied to a glass sample at temperatures in the millikelvin range its AC-dielectric constant increases and then decays logarithmically with time. For the polyester glass mylar we have observed the relaxation of the dielectric constant back to its initial value for several temperatures and histories of the bias field. Starting from the dipole gap theory we have developed a model suggesting that the change of the dielectric constant after transient application of a bias field is only partly due to relaxational processes. In addition, non-adiabatic driving of tunneling states (TSs) by applied electric fields causes long lasting changes in the dielectric constant. Moreover, our observations indicate that at temperatures below 50 mK the relaxation of TSs is caused primarily by interactions between TSs.Comment: 4 pages, 4 figures, submitted to PR

Neutrino Spin Transitions and the Violation of the Equivalence Principle

The violation of the equivalence principle (VEP) causing neutrino oscillations is of current interest. We study here the possibility of not only flavor oscillation but spin flavor oscillation of ultra high energy ($\sim$ 1 PeV) neutrinos emanating from AGN due to VEP and due to the presence of a large magnetic field ($\sim$ 1 Tesla) in AGN. In particular we look at the resonance spin flavor conversion driven by the AGN potential. Interesting bounds on the transition magnetic moment of neutrinos may therefore be obtained.Comment: Latex, 12 pages, no figures. To appear in Journal of Physics G: Nuclear and Particle Physics. Two references adde

Majorana Neutrinos and Gravitational Oscillation

We analyze the possibility of encountering resonant transitions of high energy Majorana neutrinos produced in Active Galactic Nuclei (AGN). We consider gravitational, electromagnetic and matter effects and show that the latter are ignorable. Resonant oscillations due to the gravitational interactions are shown to occur at energies in the PeV range for magnetic moments in the $10^{-17} \mu_B$ range. Coherent precession will dominate for larger magnetic moments. The alllowed regions for gravitational resonant transitions are obtained.Comment: 11 pages, 8 figures, Latex; requires revtex and epsf.tex submitted to Physical Review