Weak phase stiffness and mass divergence of superfluid in underdoped cuprates

Despite more than two decades of intensive investigations, the true nature of high temperature (high-$T_c$) superconductivity observed in the cuprates remains elusive to the researchers. In particular, in the so-called `underdoped' region, the overall behavior of superconductivity deviates $qualitatively$ from the standard theoretical description pioneered by Bardeen, Cooper and Schrieffer (BCS). Recently, the importance of phase fluctuation of the superconducting order parameter has gained significant support from various experiments. However, the microscopic mechanism responsible for the surprisingly soft phase remains one of the most important unsolved puzzles. Here, opposite to the standard BCS starting point, we propose a simple, solvable low-energy model in the strong coupling limit, which maps the superconductivity literally into a well-understood physics of superfluid in a special dilute bosonic system of local pairs of doped holes. In the prototypical material (La$_{1-\delta}$Sr$_\delta$)$_2$CuO$_4$, without use of any free parameter, a $d$-wave superconductivity is obtained for doping above $\sim 5.2\%$, below which unexpected incoherent $p$-wave pairs dominate. Throughout the whole underdoped region, very soft phases are found to originate from enormous mass enhancement of the pairs. Furthermore, a striking mass divergence is predicted that dictates the occurrence of the observed quantum critical point. Our model produces properties of the superfluid in good agreement with the experiments, and provides new insights into several current puzzles. Owing to its simplicity, this model offers a paradigm of great value in answering the long-standing challenges in underdoped cuprates

2006 Annual Summary Report for the Area 3 and Area 5 Radioactive Waste Management Sites at the Nevada Test Site, Nye County, Nevada

The Maintenance Plan for the Performance Assessments and Composite Analyses for the Area 3 and Area 5 Radioactive Waste Management Sites at the Nevada Test Site (National Security Technologies, LLC, 2006) requires an annual review to assess the adequacy of the performance assessments (PAs) and composite analyses (CAs) for each of the facilities, with the results submitted as an annual summary report to the U.S. Department of Energy (DOE) Headquarters. The Disposal Authorization Statements for the Area 3 and Area 5 Radioactive Waste Management Sites (RWMSs) also require that such reviews be made and that secondary or minor unresolved issues be tracked and addressed as part of the maintenance plan (DOE, 2000; 2002). The DOE, National Nuclear Security Administration Nevada Site Office performed annual reviews in fiscal year (FY) 2006 by evaluating operational factors and research results that impact the continuing validity of the PAs and CAs results. This annual summary report presents data and conclusions from the FY 2006 review, and determines the adequacy of the PAs and CAs. Operational factors, such as the waste form and containers, facility design, waste receipts, and closure plans, as well as monitoring results and research and development (R&D) activities, were reviewed in FY 2006 for determination of the adequacy of the PAs. Likewise, the environmental restoration activities at the Nevada Test Site relevant to the sources of residual radioactive material that are considered in the CAs, the land-use planning, and the results of the environmental monitoring and R&D activities were reviewed for determination of the adequacy of the CAs

Software Quality Assurance Plan for GoldSim Models Supporting the Area 3 and Area 5 Radioactive Waste Management Sites Performance Assessment Program

This Software Quality Assurance Plan (SQAP) applies to the development and maintenance of GoldSim models supporting the Area 3 and Area 5 Radioactive Waste Management Sites (RWMSs) performance assessments (PAs) and composite analyses (CAs). Two PA models have been approved by the U.S. Department of Energy (DOE), National Nuclear Security Administration Nevada Site Office (NNSA/NSO) as of November 2006 for the PA maintenance work undertaken by National Security Technologies, LLC (NSTec). NNSA/NSO asked NSTec to assume the custodianship of the models for future development and maintenance. The models were initially developed by Neptune and Company (N&C)

A Title 40 Code of Federal Regulations Part 191 Evaluation of Buried Transuranic Waste at the Nevada Test Site -8210

ABSTRACT In 1986, 21 m 3 of transuranic (TRU) waste was inadvertently buried in a shallow land burial trench at the Area 5 Radioactive Waste Management Site on the Nevada Test Site (NTS). Th

A Title 40 Code of Federal Regulations Part 191 Evaluation of Buried Transuranic Waste at the Nevada Test Site

In 1986, 21 m{sup 3} of transuranic (TRU) waste was inadvertently buried in a shallow land burial trench at the Area 5 Radioactive Waste Management Site on the Nevada Test Site (NTS). The U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office is considered five options for management of the buried TRU waste. One option is to leave the waste in-place if the disposal can meet the requirements of Title 40 Code of Federal Regulations (CFR) Part 191, 'Environmental Radiation Protection Standard for Management and Disposal of Spent Nuclear Fuel, High-Level, and Transuranic Radioactive Wastes'. This paper describes analyses that assess the likelihood that TRU waste in shallow land burial can meet the 40 CFR 191 standards for a geologic repository. The simulated probability of the cumulative release exceeding 1 and 10 times the 40 CFR 191.13 containment requirements is estimated to be 0.009 and less than 0.0001, respectively. The cumulative release is most sensitive to the number of groundwater withdrawal wells drilled through the disposal trench. The mean total effective dose equivalent for a member of the public is estimated to reach a maximum of 0.014 milliSievert (mSv) at 10,000 years, or approximately 10 percent of the 0.15 mSv 40 CFR 191.15 individual protection requirement. The dose is predominantly from inhalation of short-lived Rn-222 progeny in air produced by low-level waste disposed in the same trench. The transuranic radionuclide released in greatest amounts, Pu-239, contributes only 0.4 percent of the dose. The member of public dose is most sensitive to the U-234 inventory and the radon emanation coefficient. Reasonable assurance of compliance with the Subpart C groundwater protection standard is provided by site characterization data and hydrologic processes modeling which support a conclusion of no groundwater pathway within 10,000 years. Limited quantities of transuranic waste in a shallow land burial trench at the NTS can meet the requirements of 40 CFR 191

CENP-meta, an Essential Kinetochore Kinesin Required for the Maintenance of Metaphase Chromosome Alignment in Drosophila

CENP-meta has been identified as an essential, kinesin-like motor protein in Drosophila. The 257-kD CENP-meta protein is most similar to the vertebrate kinetochore-associated kinesin-like protein CENP-E, and like CENP-E, is shown to be a component of centromeric/kinetochore regions of Drosophila chromosomes. However, unlike CENP-E, which leaves the centromere/kinetochore region at the end of anaphase A, the CENP-meta protein remains associated with the centromeric/kinetochore region of the chromosome during all stages of the Drosophila cell cycle. P-element–mediated disruption of the CENP-meta gene leads to late larval/pupal stage lethality with incomplete chromosome alignment at metaphase. Complete removal of CENP-meta from the female germline leads to lethality in early embryos resulting from defects in metaphase chromosome alignment. Real-time imaging of these mutants with GFP-labeled chromosomes demonstrates that CENP-meta is required for the maintenance of chromosomes at the metaphase plate, demonstrating that the functions required to establish and maintain chromosome congression have distinguishable requirements

Probabilistic Performance Assessment of a Low-Level Radioactive Waste Disposal Site on the Nevada Test Site

The Area 5 Radioactive Waste Management Site on the Nevada Test Site has been disposing of low-level, mixed low-level, and transuranic radioactive waste since 1961. In 1988, the U.S. Department of Energy implemented performance objectives for low-level radioactive waste disposal site performance and required all site operators to prepare a performance assessment. Since then, an iterative performance assessment process has been implemented that consists of repeated cycles of site characterization, conceptual model formation/revision, and performance assessment modeling. At the end of each cycle uncertainty and sensitivity analysis are used to determine the need for revision and to identify topics requiring additional research and development. The performance assessment model is implemented in the GoldSim{reg_sign} probabilistic simulation platform. The current site conceptual model, based on site characterization data and process model results, assumes that there is no groundwater pathway under current climatic conditions and that radionuclide releases are predominately upward to the land surface. Radionuclides are released to the land surface by upward liquid advection/diffusion, gas diffusion, biointrusion, and inadvertent human intrusion. The model calculates dose for four members of public exposure scenarios and two intruder scenarios. The highest mean-dose, 0.04 mSv yr{sup -1}, is expected for a low-probability exposure scenario: establishment of a rural community at the site boundary at the end of institutional control. At the end of institutional control, doses are contributed primarily by {sup 3}H in agricultural products produced onsite. After approximately 300 years, the doses are contributed equally by {sup 99}Tc and {sup 210}Pb ingested in vegetables grown at the residence. Technetium is released to the surface by the coupled processes of liquid advection/diffusion occurring deep in the cover and plant uptake/animal burrowing occurring at shallower depths. Lead-210 is deposited in shallow cover soil by the radioactive decay of {sup 222}Rn diffusing in the gas phase. The highest mean dose for the more likely exposure scenario of transient recreational use of the site is 0.002 mSv yr{sup -1}. The transient visitor's dose is contributed predominantly by external irradiation from {sup 214}Pb and {sup 214}Bi, deposited in the cover by diffusion of {sup 222}Rn

Multiple Orbitoides d’Orbigny lineages in the Maastrichtian? Data from the Central Sakarya Basin (Turkey) and Arabian Platform successions (Southeastern Turkey and Oman)

The standard reconstruction of species of Orbitoides d’Orbigny into a single lineage during the late Santonian to the end of the Maastrichtian is based upon morphometric data from Western Europe. An irreversible increase in the size of the embryonic apparatus, and the formation of a greater number of epi-embryonic chamberlets (EPC) with time, is regarded as the main evolutionary trends used in species discrimination. However, data from Maastrichtian Orbitoides assemblages from Central Turkey and the Arabian Platform margin (Southeastern Turkey and Oman) are not consistent with this record. The Maastrichtian Besni Formation of the Arabian Platform margin in Southeastern Turkey yields invariably biconvex specimens, with small, tri- to quadrilocular embryons and a small number of EPC, comparable to late Campanian Orbitoides medius (d’Archiac). The upper Maastrichtian Taraklı Formation from the Sakarya Basin of Central Turkey contains two distinct, yet closely associated forms of Orbitoides, easily differentiated by both external and internal features. Flat to biconcave specimens possess a small, tri- to quadrilocular embryonic apparatus of Orbitoides medius-type and a small number of EPC, whereas biconvex specimens possess a large, predominantly bilocular embryonic apparatus, and were assigned to Orbitoides ex. interc. gruenbachensis Papp–apiculatus Schlumberger based on morphometry. The flat to biconcave specimens belong to a long overlooked species Orbitoides pamiri Meriç, originally described from the late Maastrichtian of the Tauride Mountains in SW Turkey. This species is herein interpreted to be an offshoot from the main Orbitoides lineage during the Maastrichtian, as are forms that we term Orbitoides ‘medius’, since they recall this species, yet are younger than normal occurrence with the accepted morphometrically defined lineage. The consistent correlation between the external and internal test features in O. pamiri implies that the shape of the test is not an ecophenotypic variation, but appears to be biologically controlled. We, therefore, postulate that more than one lineage of Orbitoides exists during the Maastrichtian, with a lineage that includes O. ‘medius’ and O. pamiri displaying retrograde evolutionary features

Closure Strategy for a Waste Disposal Facility with Multiple Waste Types and Regulatory Drivers at the Nevada Test Site

The U.S. Department of Energy, National Security Administration Nevada Site Office (NNSA/NSO) is planning to close the 92-Acre Area of the Area 5 Radioactive Waste Management Site (RWMS) at the Nevada Test Site (NTS), which is about 65 miles northwest of Las Vegas, Nevada. Closure planning for this facility must take into account the regulatory requirements for a diversity of waste streams, disposal and storage configurations, disposal history, and site conditions. This paper provides a brief background of the Area 5 RWMS, identifies key closure issues, and presents the closure strategy. Disposals have been made in 25 shallow excavated pits and trenches and 13 Greater Confinement Disposal (GCD) boreholes at the 92-Acre Area since 1961. The pits and trenches have been used to dispose unclassified low-level waste (LLW), low-level mixed waste (LLMW), and asbestiform waste, and to store classified low-level and low-level mixed materials. The GCD boreholes are intermediate-depth disposal units about 10 feet (ft) in diameter and 120 ft deep. Classified and unclassified high-specific activity LLW, transuranic (TRU), and mixed TRU are disposed in the GCD boreholes. TRU waste was also disposed inadvertently in trench T-04C. Except for three disposal units that are active, all pits and trenches are operationally covered with 8-ft thick alluvium. The 92-Acre Area also includes a Mixed Waste Disposal Unit (MWDU) operating under Resource Conservation and Recovery Act (RCRA) Interim Status, and an asbestiform waste unit operating under a state of Nevada Solid Waste Disposal Site Permit. A single final closure cover is envisioned over the 92-Acre Area. The cover is the evapotranspirative-type cover that has been successfully employed at the NTS. Closure, post-closure care, and monitoring must meet the requirements of the following regulations: U.S. Department of Energy Order 435.1, Title 40 Code of Federal Regulations (CFR) Part 191, Title 40 CFR Part 265, Nevada Administrative Code (NAC) 444.743, RCRA requirements as incorporated into NAC 444.8632, and the Federal Facility Agreement and Consent Order (FFACO). A grouping of waste disposal units according to waste type, location, and similarity in regulatory requirements identified six closure units: LLW Unit, Corrective Action Unit (CAU) 111 under FFACO, Asbestiform LLW Unit, Pit 3 MWDU, TRU GCD Borehole Unit, and TRU Trench Unit. The closure schedule of all units is tied to the closure schedule of the Pit 3 MWDU under RCRA

Closure Strategy for a Waste Disposal Facility with Multiple Waste Types and Regulatory Drivers at the Nevada Test Site

The U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office (NNSA/NSO) plans to close the waste and classified material storage cells in the southeast quadrant of the Area 5 Radioactive Waste Management Site (RWMS), informally known as the '92-Acre Area', by 2011. The 25 shallow trenches and pits and the 13 Greater Confinement Disposal (GCD) borings contain various waste streams including low-level waste (LLW), low-level mixed waste (LLMW), transuranic (TRU), mixed transuranic (MTRU), and high specific activity LLW. The cells are managed under several regulatory and permit programs by the U.S. Department of Energy (DOE) and the Nevada Division of Environmental Protection (NDEP). Although the specific closure requirements for each cell vary, 37 closely spaced cells will be closed under a single integrated monolayer evapotranspirative (ET) final cover. One cell will be closed under a separate cover concurrently. The site setting and climate constrain transport pathways and are factors in the technical approach to closure and performance assessment. Successful implementation of the integrated closure plan requires excellent communication and coordination between NNSA/NSO and the regulators