300 AREA URANIUM CONTAMINATION

{sm_bullet} Uranium fuel production {sm_bullet} Test reactor and separations experiments {sm_bullet} Animal and radiobiology experiments conducted at the. 331 Laboratory Complex {sm_bullet} .Deactivation, decontamination, decommissioning,. and demolition of 300 Area facilitie

Hand Rehabilitation and Telemonitoring through Smart Toys

We describe here a platform for autonomous hand rehabilitation and telemonitoring of young patients. A toy embedding the electronics required to sense fingers pressure in different grasping modalities is the core element of this platform. The system has been realized following the user-centered design methodology taking into account stakeholder needs from start: clinicians require reliable measurements and the ability to get a picture remotely on rehabilitation progression; children have asked to interact with a pleasant and comfortable object that is easy to use, safe, and rewarding. These requirements are not antithetic, and considering both since the design phase has allowed the realization of a platform reliable to clinicians and keen to be used by young children

Diffusive transport of light in two-dimensional granular materials

We study photon diffusion in a two-dimensional random packing of monodisperse disks as a simple model of granular material. We apply ray optics approximation to set up a persistent random walk for the photons. We employ Fresnel's intensity reflectance with its rich dependence on the incidence angle and polarization state of the light. We present an analytic expression for the transport-mean-free path in terms of the refractive indices of grains and host medium, grain radius, and packing fraction. We perform numerical simulations to examine our analytical result.Comment: 9 pages, 3 figure

Minimal Stability in Maximal Supergravity

Recently, it has been shown that maximal supergravity allows for non-supersymmetric AdS critical points that are perturbatively stable. We investigate this phenomenon of stability without supersymmetry from the sGoldstino point of view. In particular, we calculate the projection of the mass matrix onto the sGoldstino directions, and derive the necessary conditions for stability. Indeed we find a narrow window allowing for stable SUSY breaking points. As a by-product of our analysis, we find that it seems impossible to perturb supersymmetric critical points into non-supersymmetric ones: there is a minimal amount of SUSY breaking in maximal supergravity.Comment: 27 pages, 1 figure. v2: two typos corrected, published versio

Hanford Site groundwater monitoring for fiscal year 1996

This report presents the results of groundwater and vadose-zone monitoring for fiscal year (FY) 1996 on the Hanford Site, Washington. Hanford Site operations from 1943 onward produced large quantities of radiological and chemical waste that affected groundwater quality on the site. Characterization and monitoring of the vadose zone during FY 1996 comprised primarily spectral gamma logging, soil-gas monitoring, and electrical resistivity tomography. Water-level monitoring was performed to evaluate groundwater-flow directions, to track changes in water levels, and to relate such changes to evolving disposal practices. Water levels over most of the Hanford Site continued to decline between June 1995 and June 1996. Groundwater chemistry was monitored to track the extent of contamination, to note trends, and to identify emerging groundwater-quality problems. The most widespread radiological contaminant plumes were tritium and iodine-129. Smaller plumes of strontium-90, technetium-99, and plutonium also were present at levels above the U.S. Environmental Protection Agency or State of Washington interim drinking water standards. Uranium concentrations greater than the proposed drinking water standard were also observed. Nitrate, fluoride, chromium, carbon tetrachloride, chloroform, trichloroethylene, and cis-1,2-dichlomethylene were present in groundwater samples at levels above their U.S. Environmental Protection Agency or State of Washington maximum contaminant levels. The nitrate plume is the most extensive. Three-dimensional, numerical, groundwater models were applied to the Hanford Site to predict contaminant-flow paths and the impact of operational changes on site groundwater conditions. Other models were applied to assess the performance of three separate pump-and-treat systems

The X-ray outburst of the Galactic Center magnetar over six years of Chandra observations

The magnetar SGR J1745-2900 discovered at parsecs distance from the Milky Way central black hole, Sagittarius A*, represents the closest pulsar to a supermassive black hole ever detected. Furthermore, its intriguing radio emission has been used to study the environment of the black hole, as well as to derive a precise position and proper motion for this object. The discovery of SGR J1745-2900 has opened interesting debates about the number, age and nature of pulsars expected in the Galactic center region. In this work, we present extensive X-ray monitoring of the outburst of SGR J1745-2900 using the Chandra X-ray Observatory, the only instrument with the spatial resolution to distinguish the magnetar from the supermassive black hole (2.4" angular distance). It was monitored from its outburst onset in April 2013 until August 2019, collecting more than fifty Chandra observations for a total of more than 2.3 Ms of data. Soon after the outburst onset, the magnetar emission settled onto a purely thermal emission state that cooled from a temperature of about 0.9 to 0.6 keV over 6 years. The pulsar timing properties showed at least two changes in the period derivative, increasing by a factor of about 4 during the outburst decay. We find that the long-term properties of this outburst challenge current models for the magnetar outbursts.Comment: 11 pages, 6 figures. Accepted by Ap

Multiband study of RX J0838-2827 and XMM J083850.4-282759: A new asynchronous magnetic cataclysmic variable and a candidate transitional millisecond pulsar

Indexación: Scopus.In a search for the counterpart to the Fermi-LAT source 3FGL J0838.8-2829, we performed a multiwavelength campaign: in the X-ray band with Swift and XMM-Newton; in the infrared and optical with OAGH, ESO-NTT and IAC80; and in the radio with ATCA observations. We also used archival hard X-ray data obtained by INTEGRAL. We report on three X-ray sources consistent with the position of the Fermi-LAT source.We confirm the identification of the brightest object, RX J0838-2827, as a magnetic cataclysmic variable that we recognize as an asynchronous system (not associated with the Fermi-LAT source). RX J0838-2827 is extremely variable in the X-ray and optical bands, and timing analysis reveals the presence of several periodicities modulating its X-ray and optical emission. The most evident modulations are interpreted as being caused by the binary system orbital period of ~1.64 h and the white dwarf spin period of ~1.47 h. A strong flux modulation at ~15 h is observed at all energy bands, consistent with the beat frequency between spin and orbital periods. Optical spectra show prominent Hß, He I and He II emission lines that are Doppler-modulated at the orbital period and at the beat period. Therefore, RX J0838-2827 accretes through a disc-less configuration and could be either a strongly asynchronous polar or a rare example of a pre-polar system on its way to reaching synchronism. Regarding the other two X-ray sources, XMM J083850.4-282759 showed a variable X-ray emission, with a powerful flare lasting for ~600 s, similar to what is observed in transitional millisecond pulsars during the subluminous disc state: this observation possibly means that this source can be associated with the Fermi-LAT source. © 2017 The Authors.https://academic.oup.com/mnras/article/471/3/2902/408195

Metastable de Sitter vacua in N=2 to N=1 truncated supergravity

We study the possibility of achieving metastable de Sitter vacua in general N=2 to N=1 truncated supergravities without vector multiplets, and compare with the situations arising in N=2 theories with only hypermultiplets and N=1 theories with only chiral multiplets. In N=2 theories based on a quaternionic manifold and a graviphoton gauging, de Sitter vacua are necessarily unstable, as a result of the peculiar properties of the geometry. In N=1 theories based on a Kahler manifold and a superpotential, de Sitter vacua can instead be metastable provided the geometry satisfies some constraint and the superpotential can be freely adjusted. In N=2 to N=1 truncations, the crucial requirement is then that the tachyon of the mother theory be projected out from the daughter theory, so that the original unstable vacuum is projected to a metastable vacuum. We study the circumstances under which this may happen and derive general constraints for metastability on the geometry and the gauging. We then study in full detail the simplest case of quaternionic manifolds of dimension four with at least one isometry, for which there exists a general parametrization, and study two types of truncations defining Kahler submanifolds of dimension two. As an application, we finally discuss the case of the universal hypermultiplet of N=2 superstrings and its truncations to the dilaton chiral multiplet of N=1 superstrings. We argue that de Sitter vacua in such theories are necessarily unstable in weakly coupled situations, while they can in principle be metastable in strongly coupled regimes.Comment: 40 pages, no figure

Assessment of the Sabellaria alveolata reefs’ structural features along the Southern coast of Sicily (Strait of Sicily, Mediterranean Sea)

The honeycomb worm Sabellaria alveolata is a gregarious tube-dwelling polychaete that builds remarkable biogenic reefs in marine coastal waters. Sabellaria alveolata reefs are considered valuable marine habitats requiring protection measures for their conservation, as they play a key role in the functioning of coastal ecosystems. Sabellarid reefs are extensively developed along the Atlantic coasts of Europe and reported for the Mediterranean Sea and the Italian coasts, where large reefs have been recorded in several localities. Fragmentary information is available on their health status, Sabellaria reefs thus being listed as “Data Deficient” in the Red List of Marine Habitats. To fill this knowledge gap, this study focused on the analysis of the structure of three reefs found along the southern coast of Sicily. In particular, we aimed to assess their phases with respect to the natural cycle that characterizes the sabellarid reefs. Reef features were analyzed both on the macroscale, based on the bioconstruction size (diameter and thickness) and degree of fragmentation, and on the microscale, based on the measurement of worm density, opercular length and sand porch presence. This study reveals relevant differences among reefs of the studied locations. These differences we attribute to the temporal shift linked to the natural reef phases, albeit further analyses are needed to understand the possible effect of natural and anthropogenic sources of variation on the Southern Sicilian reefs. In conclusion, Sabellaria reefs are a unique and persistent habitat along the Sicilian coast requiring proper management and conservation measures