Glass as a Waste Form for the Immobilization of Plutonium

Several alternatives for disposal of surplus plutonium are being considered. One method is incorporating Pu into glass and in this paper we discuss the development and corrosion behavior of an alkali-tin-silicate glass and update results in testing Pu doped Defense Waste Processing Facility (DWPF) reference glasses. The alkali-tin-silicate glass was engineered to accommodate a high Pu loading and to be durable under conditions likely to accelerate glass reaction. The glass dissolves about 7 wt% Pu together with the neutron absorber Gd, and under test conditions expected to accelerate the glass reaction with water, is resistant to corrosion. The Pu and the Gd are released from the glass at nearly the same rate in static corrosion tests in water, and are not segregated into surface alteration phases when the glass is reacted in water vapor. Similar results for the behavior of Pu and Gd are found for the DWPF reference glasses, although the long-term rate of reaction for the reference glasses is more rapid than for the alkali-tin-silicate glass

Glass as a waste form for the immobilization of plutonium

Several alternatives for disposal of surplus plutonium are being considered. One method is incorporating Pu into glass and in this paper we discuss the development and corrosion behavior of an alkali-tin-silicate glass and update results in testing Pu doped Defense Waste Processing Facility (DWPF) reference glasses. The alkali-tin-silicate glass was engineered to accommodate a high Pu loading and to be durable under conditions likely to accelerate glass reaction. The glass dissolves about 7 wt% Pu together with the neutron absorber Gd, and under test conditions expected to accelerate the glass reaction with water, is resistant to corrosion. The Pu and the Gd are released from the glass at nearly the same rate in static corrosion tests in water, and are not segregated into surface alteration phases when the glass is reacted in water vapor. Similar results for the behavior of Pu and Gd are found for the DWPF reference glasses, although the long-term rate of reaction for the reference glasses is more rapid than for the alkali-tin-silicate glass

Particle Acceleration in Cosmic Sites - Astrophysics Issues in our Understanding of Cosmic Rays

Laboratory experiments to explore plasma conditions and stimulated particle acceleration can illuminate aspects of the cosmic particle acceleration process. Here we discuss the cosmic-ray candidate source object variety, and what has been learned about their particle-acceleration characteristics. We identify open issues as discussed among astrophysicists. -- The cosmic ray differential intensity spectrum is a rather smooth power-law spectrum, with two kinks at the "knee" (~10^15 eV) and at the "ankle" (~3 10^18 eV). It is unclear if these kinks are related to boundaries between different dominating sources, or rather related to characteristics of cosmic-ray propagation. We believe that Galactic sources dominate up to 10^17 eV or even above, and the extragalactic origin of cosmic rays at highest energies merges rather smoothly with Galactic contributions throughout the 10^15--10^18 eV range. Pulsars and supernova remnants are among the prime candidates for Galactic cosmic-ray production, while nuclei of active galaxies are considered best candidates to produce ultrahigh-energy cosmic rays of extragalactic origin. Acceleration processes are related to shocks from violent ejections of matter from energetic sources such as supernova explosions or matter accretion onto black holes. Details of such acceleration are difficult, as relativistic particles modify the structure of the shock, and simple approximations or perturbation calculations are unsatisfactory. This is where laboratory plasma experiments are expected to contribute, to enlighten the non-linear processes which occur under such conditions.Comment: accepted for publication in EPJD, topical issue on Fundamental physics and ultra-high laser fields. From review talk at "Extreme Light Infrastructure" workshop, Sep 2008. Version-2 May 2009: adjust some wordings and references at EPJD proofs stag

Geology of the Abu Dhabi 1:100 000 map sheet, 100-16, United Arab Emirates

This Sheet Description describes the Quaternary and solid geology of the Abu Dhabi 1:100 000 scale geological map. The Abu Dhabi district covers 3620 km2 along the Arabian Gulf coast including the northern part of Saadiyat island, Abu Dhabi, part of the Mussafah district and many of the islands to the west. These include Futaisi, Bu Kesheishah, Halat al Bharaini, Al Dabiya, Bu Qumah, Bu Shara, Al Qanatir and Al Rafiq. The sheet also includes a significant part of the coastal plain southwest of Abu Dhabi between Shunayyin in the east to Borquat al Rashid in the west, and south to Maharqah, across which the main E11 coastal highway runs. In the southeast of the district, an area of higher ground is formed of Miocene rocks draped by a variable sequence of cemented and unconsolidated dune sand. The region hosts several major oilfields including the Rumaitha, Shanayel, Al Dabb’iya, Umm al Dalkh, Al Mutarib and Umm al Lulu fields. The region is dominated by a series of offshore islands, part of a chain of barrier islands that extend from north of Abu Dhabi to Marawah Island, west of the present area. These islands, along with the sea-ward margin of the coastal plain are mostly comprised of a thin sequence of intensively studied Holocene marine carbonates termed the Abu Dhabi Formation. These sediments represent a transgressive-regressive sequence, and form the classic carbonate-evaporitic ‘sabkhas’ for which the region is justly famous. The Abu Dhabi Formation includes a range of marine and supratidal facies including coastal spits, bars and beach ridges, lagoonal muds, algal mats and ooidal tidal deltas deposited over the last 10 000 years. The southern limit of the Holocene transgression is marked by a beach ridge running parallel to the coast and clearly visible on satellite imagery. The barrier islands commonly have a core of well-cemented Pleistocene carbonate dune sand (Ghayathi Formation) around which the carbonate spits, bars and ridges of the Abu Dhabi Formation were accreted. The islands have been largely deflated down to the local water-table leading to the development of extensive sabkhas. Consequently, the islands are generally flat but punctuated by small Ghayathi Formation mesas and zeugen, forming mushroom-shaped outcrops rising up to 6 m above sea-level, locally capped with marine limestones of the Late Pleistocene Fuwayrit Formation. Offshore to the north of the island, below low water, is the Great Pearl Bank, an area of reefs and coralgal sands named after the former pearling industry in the region. South of the Holocene beach ridge, much of the onshore area is an extensive, very gently sloping coastal plain, dominated by a deflated planation surface developed on either unconsolidated quartzose aeolian sand or well cemented carbonate grainstones of the Ghayathi Formation. The deflation surface is commonly marked by secondary gypsum forming a sabkha. The Ghayathi Formation palaeodunes are locally well exposed, forming spectacular wind-sculpted mesas and zeugen both on the islands and within the lagoons, but also onshore draping the Miocene rocks in the southeast of the district

Siberian Snake Overcomes "Overlapping" Depolarizing Resonances

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Geology of the Al Wathba 1:100 000 map sheet, 100-12, United Arab Emirates

This Sheet Description describes the Quaternary and bedrock geology of the Al Wathba 1:100 000 scale geological map. The district covers 2780 km2 southeast of Abu Dhabi island, and includes many of the suburbs of Abu Dhabi city, including the proposed Capital District, Madinat Khalifa A and B, Mussafah, Mohammed bin Zayed City, Mafraq, Bani Yas, Al Wathba, Al Falah, Al Shamka and Abu Dhabi International Airport. The sheet extends east as far as Al Khatim. The pre-Quaternary bedrock comprises Miocene evaporitic mudstone and siltstone of the Gachsaran Formation (Fars Group) overlain by the dolomitic conglomerates, sandstones and siltstones of the Barzaman Formation in the north. In the south and west, the Gachsaran Formation is overlain by the dolomites and limestones of the Dam Formation which forms an escarpment around the Al Dhafra Air Base. These are overlain by the sandstones of the Shuwaihat and Baynunah Formations. Borehole evidence suggests there is a gradation from interbedded siltstones and sandstones of the Baynunah Formation in the west of the district to coarse dolomitic conglomerates of the Barzaman Formation in the north. The Miocene rocks are locally overlain by fluvial sandstones and channel gravels of the Hili Formation which represent Quaternary outwash from the Hajar Mountains to the east. Much of the region is partially covered by pale carbonate aeolianites of the Ghayathi Formation, themselves often covered in a veneer of more recent aeolian sand. These are well exposed near the coast in spectacular zeugen and inland, they form a series of east-northeast trending linear ridges. Modern pale carbonate-dominated low dunes occur particularly in the west of the district. The coastal zone is dominated by a range of Late Pleistocene to Holocene littoral and marine deposits, which comprise the Abu Dhabi Formation. These include coastal spits and bars, algal mats, mangrove swamps and intertidal sediments. Sabkha is developed on the surface of these deposits. The region has seen major development over the past 30 years, which has radically changed the surface geology. Much of the coastal strip has been reclaimed or developed, with a variable amount of made ground, often composed of carbonate sand dredged from the neighbouring lagoons. Further inland, many areas have been extensively landscaped, with large areas of dunes levelled flat or quarried for fill. Much of the north-western part of the sheet is either developed or scheduled for development. Extensive areas of forestry occur along the line of the main Abu Dhabi – Al Ain highway and north of Abu Dhabi International Airport

RF Induced Depolarizing Resonanaces, Spin Flip, and Partial Siberian Snakes

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Recent Advances in Understanding Particle Acceleration Processes in Solar Flares

We review basic theoretical concepts in particle acceleration, with particular emphasis on processes likely to occur in regions of magnetic reconnection. Several new developments are discussed, including detailed studies of reconnection in three-dimensional magnetic field configurations (e.g., current sheets, collapsing traps, separatrix regions) and stochastic acceleration in a turbulent environment. Fluid, test-particle, and particle-in-cell approaches are used and results compared. While these studies show considerable promise in accounting for the various observational manifestations of solar flares, they are limited by a number of factors, mostly relating to available computational power. Not the least of these issues is the need to explicitly incorporate the electrodynamic feedback of the accelerated particles themselves on the environment in which they are accelerated. A brief prognosis for future advancement is offered.Comment: This is a chapter in a monograph on the physics of solar flares, inspired by RHESSI observations. The individual articles are to appear in Space Science Reviews (2011

Effects of follicular phase exercise on luteinizing hormone pulse characteristics in sedentary eumenorrhoeic women

OBJECTIVE Current studies reveal little regarding the Inception of exercise-induced LH changes during physical training. This study aimed to assess the susceptibility of the hypothalamic–pituitary axis to the acute physical stress of exercise in untrained, physically inactive women. The acute effects of submaximal endurance exercise upon the pulsatile LH secretion in the follicular phase were compared with those accompanying leisurely strolling for a similar time period. SUBJECTS All subjects were eumenorrhoelc, as determined by biphasic temperature patterns, detection of the urinary LH surge, and mid-luteal serum progesterone levels. Subjects were not physically active and had little history of strenuous exercise ( V o 2 max = 38·0 ± 1·8) (mean ± SEM) ml/kg/min). DESIGN All women completed a 13·5-hour pulsatility test which included three consecutive 20-minute runs on a treadmill at 50, 60 and 70% of the subjects’maximum oxygen uptake ( n = 16). Six of these same subjects completed a separate test on another occasion in which one hour of leisurely strolling was substituted for exercise. Blood was sampled every 10 minutes via an indwelling cannula for 4·5 hours before and 8 hours after one hour of exercise and or strolling. MEASUREMENTS A pulse algorithm (Pulsar) was used to quantify LH pulse characteristics. RESULTS Exercise produced no significant effects upon LH pulse frequency or mean serum LH concentration. However, exercise of moderate intensity caused a significant increase in LH pulse amplitude ( P < 0·05). Strolling produced no significant changes in LH secretion. CONCLUSION Acute exercise of moderate intensity in the follicular phase of untrained women is an insufficient stimulus to inhibit the GnRH pulse generator in the post-exercise period, yet may produce a slight stimulatory effect on the amount of LH released per pulsePeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73507/1/j.1365-2265.1994.tb02794.x.pd

Energy Flow in the Hadronic Final State of Diffractive and Non-Diffractive Deep-Inelastic Scattering at HERA

An investigation of the hadronic final state in diffractive and non--diffractive deep--inelastic electron--proton scattering at HERA is presented, where diffractive data are selected experimentally by demanding a large gap in pseudo --rapidity around the proton remnant direction. The transverse energy flow in the hadronic final state is evaluated using a set of estimators which quantify topological properties. Using available Monte Carlo QCD calculations, it is demonstrated that the final state in diffractive DIS exhibits the features expected if the interaction is interpreted as the scattering of an electron off a current quark with associated effects of perturbative QCD. A model in which deep--inelastic diffraction is taken to be the exchange of a pomeron with partonic structure is found to reproduce the measurements well. Models for deep--inelastic $ep$ scattering, in which a sizeable diffractive contribution is present because of non--perturbative effects in the production of the hadronic final state, reproduce the general tendencies of the data but in all give a worse description.Comment: 22 pages, latex, 6 Figures appended as uuencoded fil