On the Maxwellian distribution, symmetric form, and entropy conservation for the Euler equations
NASA Technical Reports Server (NTRS)
Deshpande, S. M.
1986-01-01
The Euler equations of gas dynamics have some very interesting properties in that the flux vector is a homogeneous function of the unknowns and the equations can be cast in symmetric hyperbolic form and satisfy the entropy conservation. The Euler equations are the moments of the Boltzmann equation of the kinetic theory of gases when the velocity distribution function is a Maxwellian. The present paper shows the relationship between the symmetrizability and the Maxwellian velocity distribution. The entropy conservation is in terms of the H-function, which is a slight modification of the H-function first introduced by Boltzmann in his famous H-theorem. In view of the H-theorem, it is suggested that the development of total H-diminishing (THD) numerical methods may be more profitable than the usual total variation diminishing (TVD) methods for obtaining wiggle-free solutions.
Preservation and Conservation in the School Library.
ERIC Educational Resources Information Center
Sedinger, Theresa
1992-01-01
Discusses the necessity of preservation and conservation activities in school libraries to save materials such as school newspapers, programs of events, censorship records, board activities, yearbooks, and student projects. Topics discussed include brittle, deteriorating paper; monitoring the physical environment, including heat, light, humidity,…
Conservation, Preservation and Restoration in Nigerian Libraries.
ERIC Educational Resources Information Center
Ojo-Igbinoba, M. E.
1991-01-01
Addresses problems involved with the conservation, preservation, and restoration of library materials in Nigeria. Topics discussed include insect pests; light, heat, and humidity; atmospheric pollution and dust; natural disasters including fire and floods; theft and vandalism; acidity of paper; binding and mending; and trained personnel. (15…
Micro-Preservation: Conserving the Small Library.
ERIC Educational Resources Information Center
DeCandido, Robert; DeCandido, GraceAnne A.
1985-01-01
Offers suggestions and outlines procedures for the preservation of the resources of a small library. Brief sections discuss environment (temperature, humidity, housekeeping, light); library binding; simple in-house repairs; other protective measures (enclosures, microfilming); the care of unique objects; and disaster planning. A 21-item…
Conservative Pancreas Graft Preservation at the Extreme.
Laurence, Jerome Martin; Sapisochin, Gonzalo; Selzner, Markus; Norgate, Andrea; Kumar, Deepali; McGilvary, Ian D; Preig, Paul D; Schiff, Jeffrey; Cattral, Mark S
2016-01-01
Because of the value some patients place in remaining insulin-independent after pancreas transplantation, they may be reluctant to undergo graft pancreatectomy, even in the face of extreme complications, such as graft thrombosis and duodenal segment leak. Partly, for this reason, a variety of complex salvage techniques have been described to save the graft in such circumstances. We report a case of a series of extreme complications related to a leak from the duodenal segment after a simultaneous pancreas and kidney transplant. These included infected thrombosis of the inferior vena cava associated with a graft venous thrombosis and a retroperitoneal fistula. The patient retained graft function with insulin independence and repeatedly declined graft pancreatectomy against the advice of the transplant team. Conservative treatment with percutaneous drainage, antibiotics, and anticoagulation was eventually successful. This outcome is unique in our experience and may be instructive to teams caring for pancreas transplant recipients. PMID:27500244
Citrus conservation at the National Center for Genetic Resources Preservation
Technology Transfer Automated Retrieval System (TEKTRAN)
The USDA-ARS National Center for Genetic Resources Preservation maintains the base collection of genetic resources for the National Plant Germplasm System, a network of federal plant collections focused on conserving crops key to American agriculture. NCGRP research scientists have found ways to con...
Exploitation, conservation, preservation: A geographic perspective on natural resource use
Cutter, S.L.; Renwick, H.L.; Renwick, W.H.
1985-01-01
The authors of this college textbook deliberately chose the title words ''exploitation,'' ''conservation,'' and ''preservation'' to clearly illustrate that people may have very different views of natural resources. The authors state that they have attempted to include a wide range of opinions and interpretations of natural resource issues, and they have achieved this goal remarkable well. Part one (five chapters) examines the economic, ecological, political, and other factors involved in making decisions about resource use. Part two (ten chapters) consists of relatively traditional coverage of the various resources. Part three has a chapter on various models of the future that were prepared by various individuals and organizations. Then there is an epilogue in which each author views the future.
ERIC Educational Resources Information Center
RQ, 1993
1993-01-01
Presents guidelines adopted by the American Library Association (ALA) relating to the preservation, conservation, and restoration of local history and local genealogical materials. Topics addressed include assessing preservation needs; developing a plan; choosing appropriate techniques, including microduplication, photoduplication, electronic…
ERIC Educational Resources Information Center
Dureau, J. M.; Clements, D. W. G.
This statement of principles embodies a general approach to the nature and objectives of preservation and conservation work relating to library materials. It does not aim to provide a comprehensive list of detailed methods and practices, but is intended to establish a responsible attitude toward preservation and conservation by librarians. The…
A Brief Look at Recent Developments in the Preservation and Conservation of Special Collections.
ERIC Educational Resources Information Center
Hain, Jennifer E.
2003-01-01
Highlights some of the skills and technological advances that have changed the way special collections are preserved in reference to two approaches: item-level conservation and collections conservation. Discusses mechanical paper splitting; computer imaging and mechanization; mass deacidification; controlling temperature, humidity, pests, and…
Preserving oak (Quercus sp.) germplasm to promote ex situ conservation
Technology Transfer Automated Retrieval System (TEKTRAN)
Germplasm banks are increasingly used as an ex situ conservation strategy. Germplasm banks are able to maintain extraordinary levels of diversity for long periods at relatively low cost. Studies using seeds – the preferred propagules in plant germplasm banks – have revealed the underlying reasons wh...
Conservation of stone built cultural heritage and preservation of memories
NASA Astrophysics Data System (ADS)
Costa, Antônio
2016-04-01
Certainly, the main justification for the conservation of cultural heritage built, lies in the meanings that these buildings have, either to the history of nations, either as part of the cultural heritage of humanity. On the other hand, and taking into account the use of stone, it can be said that in addition to cultural and aesthetic values usually associated with these monuments or architectural ensembles that make up this heritage, the presence of stone materials gives another dimension to those constructions, which is the geo-memory. This means that, due to the presence of this material, where each has its own history, it is also possible to identify geo-memories for each of these monuments or architectural ensembles that make up this heritage, either the genesis point of view, involving environments and processes, either regarding the formation ages of these materials. At the same time and due to the use of these materials can be said that each monument or group of monuments is a reflection of the geo-diversity of a determined region or territory. In Brazil, due to its large territory, this geo-diversity includes a wide range of geological environments, phenomena and processes, giving rise to diverse stone materials, which can be observed in the monuments that are part of your built heritage. Thus in old buildings of historic sites located in particular in the southern and southeastern regions of Brazil, this geo-diversity is present because many types of rocks were used, igneous, metamorphic or sedimentary compositions and of very different ages. Of these types stands out, for example, granites and gneisses, which were used in the states of Rio de Janeiro and Minas Gerais, where they are very common. In such cases, the rocks were formed, or end of the Paleoproterozoic, or at the end of the Neoproterozoic and have different textures, sometimes with predominance of biotite, among mica, sometimes amphibole, as hornblende, or with garnet. They were often used in
Striking a Balance: Preserving Nature, Conserving Culture in the Alaska Ecosystem.
ERIC Educational Resources Information Center
Callaway, Don
1999-01-01
In Alaska's extensive parks and preserves, the National Park Service is in the difficult position of mediating between traditional Native subsistence practices and Western concepts of environmental conservation. Ethnographic research has raised awareness of the importance of harvest practices to rural Native groups for survival, cultural…
Preservation and Conservation of Information Resources in the University of Zambia Library
ERIC Educational Resources Information Center
Kanyengo, Christine Wamunyima
2009-01-01
Preservation and conservation of library materials is an important aspect of library and information management. Their importance and necessity are more paramount in countries where resources are limited and libraries need to balance them with the needs of an ever increasing number of students hoping to use them. This article reports on the…
Preservation and Conservation and Their Teaching: The Methodology of Vienna '86.
ERIC Educational Resources Information Center
Vallejo, Rosa M.
This paper discusses a seminar on the Teaching of Conservation and Preservation Management for Librarians, Archivists, and Information Scientists, which was organized jointly by the FID (Federation Internationale de Documentation), the ICA (International Council of Archives), and IFLA (International Federation of Library Associations) and held in…
The Chemistry of Paper Preservation: Part 1. The Aging of Paper and Conservation Techniques
NASA Astrophysics Data System (ADS)
Carter, Henry A.
1996-05-01
This study provides an introduction to the problem of the aging of paper and the conservation techniques that are currently being employed in paper preservation. The chemical reactions that are responsible for the aging of paper are discussed with the conclusion that acid-catalyzed hydrolysis is the predominant mechanism for cellulose degradation and strength loss. A description and the chemistry of a number of mass deacidification methods are presented. The more viable deacidification methods include the DEZ, Wei T'o, FMC, Bookkeeper, Viennese, Book Preservation Associates, Sable and the Batelle processes. A summary of the literature on the evaluations of these processes is presented, and the benefits and limitations of the mass deacidification methods are discussed. Other conservation techniques such as paper strengthening, conservation bleaching, and pest control are briefly introduced, followed by an introduction to alkaline papermaking.
Mass Conservation and Positivity Preservation with Ensemble-type Kalman Filter Algorithms
NASA Astrophysics Data System (ADS)
Janjic, Tijana; McLaughlin, Dennis B.; Cohn, Stephen E.; Verlaan, Martin
2014-05-01
Maintaining conservative physical laws numerically has long been recognized as being important in the development of numerical weather prediction (NWP) models. In the broader context of data assimilation, concerted efforts to maintain conservation laws numerically and to understand the significance of doing so have begun only recently. In order to enforce physically based conservation laws of total mass and positivity in the ensemble Kalman filter, we incorporate constraints to ensure that the filter ensemble members and the ensemble mean conserve mass and remain nonnegative through measurement updates. We show that the analysis steps of ensemble transform Kalman filter (ETKF) algorithm and ensemble Kalman filter algorithm (EnKF) can conserve the mass integral, but do not preserve positivity. Further, if localization is applied or if negative values are simply set to zero, then the total mass is not conserved either. In order to ensure mass conservation, a projection matrix that corrects for localization effects is constructed. In order to maintain both mass conservation and positivity preservation through the analysis step, we construct a data assimilation algorithm based on quadratic programming and ensemble Kalman filtering. Mass and positivity are both preserved by formulating the filter update as a set of quadratic programming problems that incorporate constraints. Some simple numerical experiments indicate that this approach can have a significant positive impact on the posterior ensemble distribution, giving results that are more physically plausible both for individual ensemble members and for the ensemble mean. The results show clear improvements in both analyses and forecasts, particularly in the presence of localized features. Behavior of the algorithm is also tested in presence of model error.
Mass Conservation and Positivity Preservation with Ensemble-type Kalman Filter Algorithms
NASA Technical Reports Server (NTRS)
Janjic, Tijana; McLaughlin, Dennis B.; Cohn, Stephen E.; Verlaan, Martin
2013-01-01
Maintaining conservative physical laws numerically has long been recognized as being important in the development of numerical weather prediction (NWP) models. In the broader context of data assimilation, concerted efforts to maintain conservation laws numerically and to understand the significance of doing so have begun only recently. In order to enforce physically based conservation laws of total mass and positivity in the ensemble Kalman filter, we incorporate constraints to ensure that the filter ensemble members and the ensemble mean conserve mass and remain nonnegative through measurement updates. We show that the analysis steps of ensemble transform Kalman filter (ETKF) algorithm and ensemble Kalman filter algorithm (EnKF) can conserve the mass integral, but do not preserve positivity. Further, if localization is applied or if negative values are simply set to zero, then the total mass is not conserved either. In order to ensure mass conservation, a projection matrix that corrects for localization effects is constructed. In order to maintain both mass conservation and positivity preservation through the analysis step, we construct a data assimilation algorithms based on quadratic programming and ensemble Kalman filtering. Mass and positivity are both preserved by formulating the filter update as a set of quadratic programming problems that incorporate constraints. Some simple numerical experiments indicate that this approach can have a significant positive impact on the posterior ensemble distribution, giving results that are more physically plausible both for individual ensemble members and for the ensemble mean. The results show clear improvements in both analyses and forecasts, particularly in the presence of localized features. Behavior of the algorithm is also tested in presence of model error.
ERIC Educational Resources Information Center
Shameenda, Kimbo Lemmy; Kanyengo, Christine Wamunyima
2012-01-01
This article establishes the level of skills and experience in preservation and conservation management using a case study methodological approach conducted in the 3 university libraries at the University of Zambia. The findings revealed that 20 (57%) of the library staff had not received formal training in preservation and conservation of library…
NASA Astrophysics Data System (ADS)
Le Chenadec, Vincent; Pitsch, Heinz
2013-09-01
This paper presents a novel approach for solving the conservative form of the incompressible two-phase Navier-Stokes equations. In order to overcome the numerical instability induced by the potentially large density ratio encountered across the interface, the proposed method includes a Volume-of-Fluid type integration of the convective momentum transport, a monotonicity preserving momentum rescaling, and a consistent and conservative Ghost Fluid projection that includes surface tension effects. The numerical dissipation inherent in the Volume-of-Fluid treatment of the convective transport is localized in the interface vicinity, enabling the use of a kinetic energy conserving discretization away from the singularity. Two- and three-dimensional tests are presented, and the solutions shown to remain accurate at arbitrary density ratios. The proposed method is then successfully used to perform the detailed simulation of a round water jet emerging in quiescent air, therefore suggesting the applicability of the proposed algorithm to the computation of realistic turbulent atomization.
Le Chenadec, Vincent; Pitsch, Heinz
2013-09-15
This paper presents a novel approach for solving the conservative form of the incompressible two-phase Navier–Stokes equations. In order to overcome the numerical instability induced by the potentially large density ratio encountered across the interface, the proposed method includes a Volume-of-Fluid type integration of the convective momentum transport, a monotonicity preserving momentum rescaling, and a consistent and conservative Ghost Fluid projection that includes surface tension effects. The numerical dissipation inherent in the Volume-of-Fluid treatment of the convective transport is localized in the interface vicinity, enabling the use of a kinetic energy conserving discretization away from the singularity. Two- and three-dimensional tests are presented, and the solutions shown to remain accurate at arbitrary density ratios. The proposed method is then successfully used to perform the detailed simulation of a round water jet emerging in quiescent air, therefore suggesting the applicability of the proposed algorithm to the computation of realistic turbulent atomization.
NASA Astrophysics Data System (ADS)
Fricker, A.; Green, P.
2010-04-01
These conference proceedings contain the written papers of the contributions presented at the 4th International Conference on: Preservation and Conservation Issues in Digital Printing and Digital Photography. The conference was held at the Institute of Physics, London, UK on 27th-28th May 2010. Previous conferences in this series took place in 2000, 2003 and 2006. The aim of this conference series is to inform those responsible for the preservation of digitally printed materials about developments in digital photography and printing technologies. We aim to examine progress in research on inks and substrates and their significance for conservation and preservation issues and techniques. We also hope to develop links between related industries and the conservation/preservation world. Research areas explored in this conference include current developments and future trends in digital printing and photographic technologies; the effect of environmental, storage and salvage conditions on the durability of digital prints and photographs; image processing techniques; image permanence considerations and standards for fastness, permanence and the role of scanning and file formats. We would like to thank all participants for their contribution to the conference programme and these proceedings. Our thanks go to Ms C. Gu and Mr M. Sandy for chairing conference sessions. We are also grateful to Dawn Stewart and the Institute of Physics Conference Team for their invaluable support and assistance in arranging the conference and reception. Finally we would like to extend our thanks to the Society of Imaging Science and Technology (IS&T) for their sponsorship support. The Editors Acknowledgements Conference Organising Committee: Ms A Fricker and Dr. P Green (London College of Communication, University of the Arts London). Proceedings edited and compiled by Ms A Fricker and Dr. P Green.
Sperm Preservation by Freeze-Drying for the Conservation of Wild Animals
Kaneko, Takehito; Ito, Hideyuki; Sakamoto, Hidefusa; Onuma, Manabu; Inoue-Murayama, Miho
2014-01-01
Sperm preservation is a useful technique for the maintenance of biological resources in experimental and domestic animals, and in wild animals. A new preservation method has been developed that enables sperm to be stored for a long time in a refrigerator at 4°C. Sperm are freeze-dried in a solution containing 10 mM Tris and 1 mM EDTA. Using this method, liquid nitrogen is not required for the storage and transportation of sperm. We demonstrate that chimpanzee, giraffe, jaguar, weasel and the long-haired rat sperm remain viable after freeze-drying. In all species, pronuclei were formed after the injection of freeze-dried sperm into the mouse oocytes. Although preliminary, these results may be useful for the future establishment of “freeze-drying zoo” to conserve wild animals. PMID:25409172
Sperm preservation by freeze-drying for the conservation of wild animals.
Kaneko, Takehito; Ito, Hideyuki; Sakamoto, Hidefusa; Onuma, Manabu; Inoue-Murayama, Miho
2014-01-01
Sperm preservation is a useful technique for the maintenance of biological resources in experimental and domestic animals, and in wild animals. A new preservation method has been developed that enables sperm to be stored for a long time in a refrigerator at 4 °C. Sperm are freeze-dried in a solution containing 10 mM Tris and 1 mM EDTA. Using this method, liquid nitrogen is not required for the storage and transportation of sperm. We demonstrate that chimpanzee, giraffe, jaguar, weasel and the long-haired rat sperm remain viable after freeze-drying. In all species, pronuclei were formed after the injection of freeze-dried sperm into the mouse oocytes. Although preliminary, these results may be useful for the future establishment of "freeze-drying zoo" to conserve wild animals. PMID:25409172
Conservation of Mass and Preservation of Positivity with Ensemble-Type Kalman Filter Algorithms
NASA Technical Reports Server (NTRS)
Janjic, Tijana; Mclaughlin, Dennis; Cohn, Stephen E.; Verlaan, Martin
2014-01-01
This paper considers the incorporation of constraints to enforce physically based conservation laws in the ensemble Kalman filter. In particular, constraints are used to ensure that the ensemble members and the ensemble mean conserve mass and remain nonnegative through measurement updates. In certain situations filtering algorithms such as the ensemble Kalman filter (EnKF) and ensemble transform Kalman filter (ETKF) yield updated ensembles that conserve mass but are negative, even though the actual states must be nonnegative. In such situations if negative values are set to zero, or a log transform is introduced, the total mass will not be conserved. In this study, mass and positivity are both preserved by formulating the filter update as a set of quadratic programming problems that incorporate non-negativity constraints. Simple numerical experiments indicate that this approach can have a significant positive impact on the posterior ensemble distribution, giving results that are more physically plausible both for individual ensemble members and for the ensemble mean. In two examples, an update that includes a non-negativity constraint is able to properly describe the transport of a sharp feature (e.g., a triangle or cone). A number of implementation questions still need to be addressed, particularly the need to develop a computationally efficient quadratic programming update for large ensemble.
The key role of cultural preservation in maize diversity conservation in the argentine yungas.
Hilgert, Norma I; Zamudio, Fernando; Furlan, Violeta; Cariola, Lucía
2013-01-01
Farmers' decisions on what to grow and why can contribute in understanding the conservation of agrobiodiversity. Culture and ethnicity are indicated as first-class factors leading preservation of heirloom cultivars but this has been little considered in studies examining factors that influence the loss or preservation of agrobiodiversity. We propose that corn's ethnotaxa of less diverse uses, which are also key partners in local cultural reproduction, are usually cultivated by a few households. We analyse if there is a relationship between uses and richness of cultivated ethnotaxa at household level and describe corn's medicinal and ritual uses. We found 25 cultivated ethnotaxa, heterogeneously distributed in the region, and we also found that ethnotaxa with less diverse uses are cultivated in fewer households. We identified that, at regional scale, richness is related with food use diversity. The most frequently cited medicinal uses were urinary and tract infections, diarrhoea, and liver disorders. Medicinal recipes involve combinations with other elements. Maize is an indispensable resource in the rituals that propitiate productive activity, to augur prosperity or misfortune according to signals. We have identified the vulnerability in preserving the richness of corn in the region and the factors that shape its cultivation at different scales. PMID:24078829
The Key Role of Cultural Preservation in Maize Diversity Conservation in the Argentine Yungas
Hilgert, Norma I.; Zamudio, Fernando; Cariola, Lucía
2013-01-01
Farmers' decisions on what to grow and why can contribute in understanding the conservation of agrobiodiversity. Culture and ethnicity are indicated as first-class factors leading preservation of heirloom cultivars but this has been little considered in studies examining factors that influence the loss or preservation of agrobiodiversity. We propose that corn's ethnotaxa of less diverse uses, which are also key partners in local cultural reproduction, are usually cultivated by a few households. We analyse if there is a relationship between uses and richness of cultivated ethnotaxa at household level and describe corn's medicinal and ritual uses. We found 25 cultivated ethnotaxa, heterogeneously distributed in the region, and we also found that ethnotaxa with less diverse uses are cultivated in fewer households. We identified that, at regional scale, richness is related with food use diversity. The most frequently cited medicinal uses were urinary and tract infections, diarrhoea, and liver disorders. Medicinal recipes involve combinations with other elements. Maize is an indispensable resource in the rituals that propitiate productive activity, to augur prosperity or misfortune according to signals. We have identified the vulnerability in preserving the richness of corn in the region and the factors that shape its cultivation at different scales. PMID:24078829
Pollock, Laura J; Rosauer, Dan F; Thornhill, Andrew H; Kujala, Heini; Crisp, Michael D; Miller, Joseph T; McCarthy, Michael A
2015-02-19
Evolutionary and genetic knowledge is increasingly being valued in conservation theory, but is rarely considered in conservation planning and policy. Here, we integrate phylogenetic diversity (PD) with spatial reserve prioritization to evaluate how well the existing reserve system in Victoria, Australia captures the evolutionary lineages of eucalypts, which dominate forest canopies across the state. Forty-three per cent of remaining native woody vegetation in Victoria is located in protected areas (mostly national parks) representing 48% of the extant PD found in the state. A modest expansion in protected areas of 5% (less than 1% of the state area) would increase protected PD by 33% over current levels. In a recent policy change, portions of the national parks were opened for development. These tourism development zones hold over half the PD found in national parks with some species and clades falling entirely outside of protected zones within the national parks. This approach of using PD in spatial prioritization could be extended to any clade or area that has spatial and phylogenetic data. Our results demonstrate the relevance of PD to regional conservation policy by highlighting that small but strategically located areas disproportionally impact the preservation of evolutionary lineages. PMID:25561668
Pollock, Laura J.; Rosauer, Dan F.; Thornhill, Andrew H.; Kujala, Heini; Crisp, Michael D.; Miller, Joseph T.; McCarthy, Michael A.
2015-01-01
Evolutionary and genetic knowledge is increasingly being valued in conservation theory, but is rarely considered in conservation planning and policy. Here, we integrate phylogenetic diversity (PD) with spatial reserve prioritization to evaluate how well the existing reserve system in Victoria, Australia captures the evolutionary lineages of eucalypts, which dominate forest canopies across the state. Forty-three per cent of remaining native woody vegetation in Victoria is located in protected areas (mostly national parks) representing 48% of the extant PD found in the state. A modest expansion in protected areas of 5% (less than 1% of the state area) would increase protected PD by 33% over current levels. In a recent policy change, portions of the national parks were opened for development. These tourism development zones hold over half the PD found in national parks with some species and clades falling entirely outside of protected zones within the national parks. This approach of using PD in spatial prioritization could be extended to any clade or area that has spatial and phylogenetic data. Our results demonstrate the relevance of PD to regional conservation policy by highlighting that small but strategically located areas disproportionally impact the preservation of evolutionary lineages. PMID:25561668
Hagedorn, Mary; Carter, Virginia; Martorana, Kelly; Paresa, Malia K.; Acker, Jason; Baums, Iliana B.; Borneman, Eric; Brittsan, Michael; Byers, Michael; Henley, Michael; Laterveer, Michael; Leong, Jo-Ann; McCarthy, Megan; Meyers, Stuart; Nelson, Brian D.; Petersen, Dirk; Tiersch, Terrence; Uribe, Rafael Cuevas; Woods, Erik; Wildt, David
2012-01-01
Coral reefs are experiencing unprecedented degradation due to human activities, and protecting specific reef habitats may not stop this decline, because the most serious threats are global (i.e., climate change), not local. However, ex situ preservation practices can provide safeguards for coral reef conservation. Specifically, modern advances in cryobiology and genome banking could secure existing species and genetic diversity until genotypes can be introduced into rehabilitated habitats. We assessed the feasibility of recovering viable sperm and embryonic cells post-thaw from two coral species, Acropora palmata and Fungia scutaria that have diffferent evolutionary histories, ecological niches and reproductive strategies. In vitro fertilization (IVF) of conspecific eggs using fresh (control) spermatozoa revealed high levels of fertilization (>90% in A. palmata; >84% in F. scutaria; P>0.05) that were unaffected by tested sperm concentrations. A solution of 10% dimethyl sulfoxide (DMSO) at cooling rates of 20 to 30°C/min most successfully cryopreserved both A. palmata and F. scutaria spermatozoa and allowed producing developing larvae in vitro. IVF success under these conditions was 65% in A. palmata and 53% in F. scutaria on particular nights; however, on subsequent nights, the same process resulted in little or no IVF success. Thus, the window for optimal freezing of high quality spermatozoa was short (∼5 h for one night each spawning cycle). Additionally, cryopreserved F. scutaria embryonic cells had∼50% post-thaw viability as measured by intact membranes. Thus, despite some differences between species, coral spermatozoa and embryonic cells are viable after low temperature (−196°C) storage, preservation and thawing. Based on these results, we have begun systematically banking coral spermatozoa and embryonic cells on a large-scale as a support approach for preserving existing bio- and genetic diversity found in reef systems. PMID:22413020
Noah’s Ark Conservation Will Not Preserve Threatened Ecological Communities under Climate Change
Harris, Rebecca Mary Bernadette; Carter, Oberon; Gilfedder, Louise; Porfirio, Luciana Laura; Lee, Greg; Bindoff, Nathaniel Lee
2015-01-01
Background Effective conservation of threatened ecological communities requires knowledge of where climatically suitable habitat is likely to persist into the future. We use the critically endangered Lowland Grassland community of Tasmania, Australia as a case study to identify options for management in cases where future climatic conditions become unsuitable for the current threatened community. Methods We model current and future climatic suitability for the Lowland Themeda and the Lowland Poa Grassland communities, which make up the listed ecological community. We also model climatic suitability for the structurally dominant grass species of these communities, and for closely related grassland and woodland communities. We use a dynamically downscaled regional climate model derived from six CMIP3 global climate models, under the A2 SRES emissions scenario. Results All model projections showed a large reduction in climatically suitable area by mid-century. Outcomes are slightly better if closely related grassy communities are considered, but the extent of suitable area is still substantially reduced. Only small areas within the current distribution are projected to remain climatically suitable by the end of the century, and very little of that area is currently in good condition. Conclusions As the climate becomes less suitable, a gradual change in the species composition, structure and habitat quality of the grassland communities is likely. Conservation management will need to focus on maintaining diversity, structure and function, rather than attempting to preserve current species composition. Options for achieving this include managing related grassland types to maintain grassland species at the landscape-scale, and maximising the resilience of grasslands by reducing further fragmentation, weed invasion and stress from other land uses, while accepting that change is inevitable. Attempting to maintain the status quo by conserving the current structure and
ERIC Educational Resources Information Center
Lull, William P.; Banks, Paul N.
These guidelines are intended to orient the library/archives professional in New York to the common issues, language, pitfalls, and opportunities involved in dealing with the built environment and its impact on the conservation and preservation of a valuable collection. Although developed for the climate typical in New York State, many aspects…
Peñas, Julio; Barrios, Sara; Bobo-Pinilla, Javier; Lorite, Juan; Martínez-Ortega, M Montserrat
2016-01-01
Astragalus edulis (Fabaceae) is an endangered annual species from the western Mediterranean region that colonized the SE Iberian Peninsula, NE and SW Morocco, and the easternmost Macaronesian islands (Lanzarote and Fuerteventura). Although in Spain some conservation measures have been adopted, it is still necessary to develop an appropriate management plan to preserve genetic diversity across the entire distribution area of the species. Our main objective was to use population genetics as well as ecological and phylogeographic data to select Relevant Genetic Units for Conservation (RGUCs) as the first step in designing conservation plans for A. edulis. We identified six RGUCs for in situ conservation, based on estimations of population genetic structure and probabilities of loss of rare alleles. Additionally, further population parameters, i.e. occupation area, population size, vulnerability, legal status of the population areas, and the historical haplotype distribution, were considered in order to establish which populations deserve conservation priority. Three populations from the Iberian Peninsula, two from Morocco, and one from the Canary Islands represent the total genetic diversity of the species and the rarest allelic variation. Ex situ conservation is recommended to complement the preservation of A. edulis, given that effective in situ population protection is not feasible in all cases. The consideration of complementary phylogeographic and ecological data is useful for management efforts to preserve the evolutionary potential of the species. PMID:26844014
Barrios, Sara; Bobo-Pinilla, Javier; Lorite, Juan; Martínez-Ortega, M. Montserrat
2016-01-01
Astragalus edulis (Fabaceae) is an endangered annual species from the western Mediterranean region that colonized the SE Iberian Peninsula, NE and SW Morocco, and the easternmost Macaronesian islands (Lanzarote and Fuerteventura). Although in Spain some conservation measures have been adopted, it is still necessary to develop an appropriate management plan to preserve genetic diversity across the entire distribution area of the species. Our main objective was to use population genetics as well as ecological and phylogeographic data to select Relevant Genetic Units for Conservation (RGUCs) as the first step in designing conservation plans for A. edulis. We identified six RGUCs for in situ conservation, based on estimations of population genetic structure and probabilities of loss of rare alleles. Additionally, further population parameters, i.e. occupation area, population size, vulnerability, legal status of the population areas, and the historical haplotype distribution, were considered in order to establish which populations deserve conservation priority. Three populations from the Iberian Peninsula, two from Morocco, and one from the Canary Islands represent the total genetic diversity of the species and the rarest allelic variation. Ex situ conservation is recommended to complement the preservation of A. edulis, given that effective in situ population protection is not feasible in all cases. The consideration of complementary phylogeographic and ecological data is useful for management efforts to preserve the evolutionary potential of the species. PMID:26844014
ERIC Educational Resources Information Center
Clements, D. W. G.
Designed to present a broad picture that characterizes the current world situation with respect to preservation and conservation of library and archival documents, this report is based on a March 1986 survey on the state of the world's patrimony which was funded by Unesco and undertaken jointly by IFLA (the International Federation of Library…
Weibel instability with semirelativistic Maxwellian distribution function
Zaheer, S.; Murtaza, G.
2007-07-15
A macroscopic description of the linear Weibel instability, based on semirelativistic distribution in an unmagnetized plasma is presented. In particular, analytical expressions are derived for the real and imaginary parts of the dielectric constant for the Maxwellian and semirelativistic Maxwellian distribution functions under the conditions of {xi}=({omega}/k{sub parallel}{theta}{sub parallel})>>1 and <<1. The real frequency and the growth rate of the instability for the semirelativistic case now depends upon the factor {chi} generated from the relativistic term in the distribution function. The presence of {chi} which is always greater than unity favors the Weibel instability to occur even for the small anisotropy of temperature. As we increase the value of {chi} large enough that it dominates over other terms, the damping changes into growth. In the limiting case, i.e., {chi}=1, the results approach the Maxwellian situation.
ERIC Educational Resources Information Center
Oliphant, Dave, Ed.
The 10 essays in this collection describe conservation and preservation projects conducted at the Harry Ransom Humanities Research Center at the University of Texas at Austin. Eight of the 10 essays, each of which is written by a member of the Center's staff, address conservation treatments and issues. Two essays deal with preserving materials by…
ERIC Educational Resources Information Center
Henderson, Kathryn Luther, Ed.; Henderson, William T., Ed.
Papers presented at the 1981 Allerton Park Institute include: (1) "Conservation: What We should Do Until the Conservator and the Twenty-first Century Arrive," by Robert H. Patterson; (2) "Expanding Preservation Resources: The Corps of Practitioners and the Core of Knowledge," by Pamela W. Darling; (3) "National Preservation Planning and Regional…
NASA Astrophysics Data System (ADS)
Blachère, F.; Turpault, R.
2016-06-01
The objective of this work is to design explicit finite volumes schemes for specific systems of conservations laws with stiff source terms, which degenerate into diffusion equations. We propose a general framework to design an asymptotic preserving scheme, that is stable and consistent under a classical hyperbolic CFL condition in both hyperbolic and diffusive regime, for any two-dimensional unstructured mesh. Moreover, the scheme developed also preserves the set of admissible states, which is mandatory to keep physical solutions in stiff configurations. This construction is achieved by using a non-linear scheme as a target scheme for the diffusive equation, which gives the form of the global scheme for the complete system of conservation laws. Numerical results are provided to validate the scheme in both regimes.
NASA Astrophysics Data System (ADS)
Mabuza, Sibusiso; Kuzmin, Dmitri; Čanić, Sunčica; Bukač, Martina
2014-11-01
We study the mathematical models and numerical schemes for reactive transport of a soluble substance in deformable media. The medium is a channel with compliant adsorbing walls. The solutes are dissolved in the fluid flowing through the channel. The fluid, which carries the solutes, is viscous and incompressible. The reactive process is described as a general physico-chemical process taking place on the compliant channel wall. The problem is modeled by a convection-diffusion adsorption-desorption equation in moving domains. We present a conservative, positivity preserving, high resolution ALE-FCT scheme for this problem in the presence of dominant transport processes and wall reactions on the moving wall. A Patankar type time discretization is presented, which provides conservative treatment of nonlinear reactive terms. We establish CFL-type constraints on the time step, and show the mass conservation of the time discretization scheme. Numerical simulations are performed to show validity of the schemes against effective models under various scenarios including linear adsorption-desorption, irreversible wall reaction, infinite adsorption kinetics, and nonlinear Langmuir kinetics. The grid convergence of the numerical scheme is studied for the case of fixed meshes and moving meshes in fixed domains. Finally, we simulate reactive transport in moving domains under linear and nonlinear chemical reactions at the wall, and show that the motion of the compliant channel wall enhances adsorption of the solute from the fluid to the channel wall. Consequences of this result are significant in the area of, e.g., nano-particle cancer drug delivery. Our result shows that periodic excitation of the cancerous tissue using, e.g., ultrasound, may enhance adsorption of cancer drugs carried by nano-particles via the human vasculature. For Taylor dispersion and for other convection dominated flows, numerical schemes for solute transport may lead to undesirable numerical artefacts. These
Maxwellians and the Remaking of Maxwell's Equations
NASA Astrophysics Data System (ADS)
Hunt, Bruce
2012-02-01
Although James Clerk Maxwell first formulated his theory of the electromagnetic field in the early 1860s, it went through important changes before it gained general acceptance in the 1890s. Those changes were largely the work of a group of younger physicists, the Maxwellians, led by G. F. FitzGerald in Ireland, Oliver Lodge and Oliver Heaviside in England, and Heinrich Hertz in Germany. Together, they extended, refined, tested, and confirmed Maxwell's theory, and recast it into the set of four vector equations known ever since as ``Maxwell's equations.'' By tracing how the Maxwellians remade and disseminated Maxwell's theory between the late 1870s and the mid-1890s, we can gain a clearer understanding not just of how the electromagnetic field was understood at the end of the 19th century, but of the collaborative nature of work at the frontiers of physics.
Electrostatic potential fluctuations in a Maxwellian plasma
Hazeltine, R.D.; Lowrey, J.D.
2006-01-15
The spatial correlation function of a Maxwellian plasma with perturbations arising in the electrostatic potential due to random ion density fluctuations is examined. The entropy is found from the one-particle distribution function using the Shannon formula and then, using the Einstein method, the probability distribution for the electrostatic potential fluctuation is determined. This straightforward procedure is demonstrated to be a powerful tool in studying plasma correlation functions when the system entropy can be computed.
1997-11-01
The West Virginia Conservation and Preservation Act is a land management device whose time has come in West Virginia. Wise use of this tool by lawyers, property owners and holding entities can help the state to achieve a balance between the wise use of its natural resources and the promotion of tourism. Although not appropriate in every situation where it could potentially be applied, the West Virginia Act is a device by which economic and environmental interests can converge for the benefit of both parties.
Wilson, Howard B; Meijaard, Erik; Venter, Oscar; Ancrenaz, Marc; Possingham, Hugh P
2014-01-01
The Sumatran orangutan is currently listed by the IUCN as critically endangered and the Bornean species as endangered. Unless effective conservation measures are enacted quickly, most orangutan populations without adequate protection face a dire future. Two main strategies are being pursued to conserve orangutans: (i) rehabilitation and reintroduction of ex-captive or displaced individuals; and (ii) protection of their forest habitat to abate threats like deforestation and hunting. These strategies are often mirrored in similar programs to save other valued and endangered mega-fauna. Through GIS analysis, collating data from across the literature, and combining this information within a modelling and decision analysis framework, we analysed which strategy or combination of strategies is the most cost-effective at maintaining wild orangutan populations, and under what conditions. We discovered that neither strategy was optimal under all circumstances but was dependent on the relative cost per orangutan, the timescale of management concern, and the rate of deforestation. Reintroduction, which costs twelve times as much per animal as compared to protection of forest, was only a cost-effective strategy at very short timescales. For time scales longer than 10-20 years, forest protection is the more cost-efficient strategy for maintaining wild orangutan populations. Our analyses showed that a third, rarely utilised strategy is intermediate: introducing sustainable logging practices and protection from hunting in timber production forest. Maximum long-term cost-efficiency is achieved by working in conservation forest. However, habitat protection involves addressing complex conservation issues and conflicting needs at the landscape level. We find a potential resolution in that well-managed production forests could achieve intermediate conservation outcomes. This has broad implications for sustaining biodiversity more generally within an economically productive landscape
Wilson, Howard B.; Meijaard, Erik; Venter, Oscar; Ancrenaz, Marc; Possingham, Hugh P.
2014-01-01
The Sumatran orangutan is currently listed by the IUCN as critically endangered and the Bornean species as endangered. Unless effective conservation measures are enacted quickly, most orangutan populations without adequate protection face a dire future. Two main strategies are being pursued to conserve orangutans: (i) rehabilitation and reintroduction of ex-captive or displaced individuals; and (ii) protection of their forest habitat to abate threats like deforestation and hunting. These strategies are often mirrored in similar programs to save other valued and endangered mega-fauna. Through GIS analysis, collating data from across the literature, and combining this information within a modelling and decision analysis framework, we analysed which strategy or combination of strategies is the most cost-effective at maintaining wild orangutan populations, and under what conditions. We discovered that neither strategy was optimal under all circumstances but was dependent on the relative cost per orangutan, the timescale of management concern, and the rate of deforestation. Reintroduction, which costs twelve times as much per animal as compared to protection of forest, was only a cost-effective strategy at very short timescales. For time scales longer than 10–20 years, forest protection is the more cost-efficient strategy for maintaining wild orangutan populations. Our analyses showed that a third, rarely utilised strategy is intermediate: introducing sustainable logging practices and protection from hunting in timber production forest. Maximum long-term cost-efficiency is achieved by working in conservation forest. However, habitat protection involves addressing complex conservation issues and conflicting needs at the landscape level. We find a potential resolution in that well-managed production forests could achieve intermediate conservation outcomes. This has broad implications for sustaining biodiversity more generally within an economically productive landscape
Preservation or development. A Rhetorical analysis of the American conservation debate, 1980-1984
Short, C.B.
1985-01-01
In the late 1970s, America's commitment to an ecological view of public land management was challenged by a reinvigorated conservative movement. The Sagebrush Rebellion and the New Right attempted to convince the public that environmentalism threatened the nation's well-being. This study focuses upon the recent debate over the direction of federal land policy. Examining speeches, essays, pamphlets, and other forms of persuasive discourse, the author identifies two distinct workviews at the center of the controversy. The view of the New Right, often advanced by Ronald Reagan and James Watt, envisioned a growth economy in which the market place dictated how natural resources would be allocated. An opposing ecological perspective promoted active federal management with multiple-use guidelines and environmental impact statements serving to protect the public lands from any lasting reminders of human development. The study reviews the historical and political context of the conservation debate and reveals how the debate affected the nation's view of wilderness. While conservatives argued from a human-centered view of nature emphasizing economic needs, environmentalists supported an ecological view, granting certain rights to all members of the ecosystem. An understanding of recurring rhetorical strategies illuminates the growing schism over how America's public land should be used and maintained.
Spinor-Like Hamiltonian for Maxwellian Optics
NASA Astrophysics Data System (ADS)
Kulyabov, D. S.
2016-02-01
Background. Spinors are more special objects than tensors. Therefore spinors possess more properties than the more generic objects such as tensors. The group of Lorentz two-spinors is the covering group of the Lorentz group. Purpose. Since the Lorentz group is the symmetry group of Maxwell equations, it is reasonable to use Lorentz two-spinors and not tensors when writing the Maxwell equations. Method. We write the Maxwell equations using Lorentz two-spinors. Also a convenient representation of Lorentz two-spinors in terms of the Riemann-Silberstein complex vectors is used. Results: In the spinor formalism (in the representation of the Lorentz spinors and Riemann-Silberstein vectors) we have constructed the Hamiltonian of Maxwellian optics. With the use of spinors, the Maxwell equations take a form similar to the Dirac equation. Conclusions: For Maxwell equations in the Dirac-like form we can expand research methods by means of quantum field theory. In this form, the connection between the Hamiltonians of geometric, beam and Maxwellian optics is clearly visible.
Non-Maxwellian to Maxwellian transitions of atmospheric microplasmas at microwave frequencies
NASA Astrophysics Data System (ADS)
Lee, M. U.; Jeong, S. Y.; Won, I. H.; Sung, S. K.; Yun, G. S.; Lee, J. K.
2016-07-01
Particle-in-cell/Monte Carlo simulations and numerical analysis of a single particle motion are performed for atmospheric He microplasmas at microwave frequencies to determine the characteristics of non-Maxwellian to Maxwellian transition. The left and the right regimes of Paschen curve, divided by this transition, reveal that the transition frequencies depend on the gap of electrodes and the neutral gas pressure to follow scaling laws for a new extended Paschen law. The fluid models are reasonable at the right-side regime of Paschen breakdown areas, but not on the left side, which is highly kinetic for electrons. The plasmas driven by weaker electric fields of high enough frequencies at the right-side Paschen regime breed more energetic electrons.
Identifying functional thermodynamics in autonomous Maxwellian ratchets
NASA Astrophysics Data System (ADS)
Boyd, Alexander B.; Mandal, Dibyendu; Crutchfield, James P.
2016-02-01
We introduce a family of Maxwellian Demons for which correlations among information bearing degrees of freedom can be calculated exactly and in compact analytical form. This allows one to precisely determine Demon functional thermodynamic operating regimes, when previous methods either misclassify or simply fail due to approximations they invoke. This reveals that these Demons are more functional than previous candidates. They too behave either as engines, lifting a mass against gravity by extracting energy from a single heat reservoir, or as Landauer erasers, consuming external work to remove information from a sequence of binary symbols by decreasing their individual uncertainty. Going beyond these, our Demon exhibits a new functionality that erases bits not by simply decreasing individual-symbol uncertainty, but by increasing inter-bit correlations (that is, by adding temporal order) while increasing single-symbol uncertainty. In all cases, but especially in the new erasure regime, exactly accounting for informational correlations leads to tight bounds on Demon performance, expressed as a refined Second Law of thermodynamics that relies on the Kolmogorov-Sinai entropy for dynamical processes and not on changes purely in system configurational entropy, as previously employed. We rigorously derive the refined Second Law under minimal assumptions and so it applies quite broadly—for Demons with and without memory and input sequences that are correlated or not. We note that general Maxwellian Demons readily violate previously proposed, alternative such bounds, while the current bound still holds. As such, it broadly describes the minimal energetic cost of any computation by a thermodynamic system.
Cheng, Juan; Shu, Chi-Wang
2014-09-01
In applications such as astrophysics and inertial confinement fusion, there are many three-dimensional cylindrical-symmetric multi-material problems which are usually simulated by Lagrangian schemes in the two-dimensional cylindrical coordinates. For this type of simulation, a critical issue for the schemes is to keep spherical symmetry in the cylindrical coordinate system if the original physical problem has this symmetry. In the past decades, several Lagrangian schemes with such symmetry property have been developed, but all of them are only first order accurate. In this paper, we develop a second order cell-centered Lagrangian scheme for solving compressible Euler equations in cylindrical coordinates, based on the control volume discretizations, which is designed to have uniformly second order accuracy and capability to preserve one-dimensional spherical symmetry in a two-dimensional cylindrical geometry when computed on an equal-angle-zoned initial grid. The scheme maintains several good properties such as conservation for mass, momentum and total energy, and the geometric conservation law. Several two-dimensional numerical examples in cylindrical coordinates are presented to demonstrate the good performance of the scheme in terms of accuracy, symmetry, non-oscillation and robustness. The advantage of higher order accuracy is demonstrated in these examples.
Peleg, Avner; Meerson, Baruch; Vilenkin, Arkady; Conti, Massimo
2001-06-01
A long and slender finger can serve as a simple {open_quotes}test bed{close_quotes} for different phase-ordering models. In this work, the globally conserved, interface-controlled dynamics of a long finger is investigated, analytically and numerically, in two dimensions. An important limit is considered when the finger dynamics is reducible to area-preserving motion by curvature. A free boundary problem for the finger shape is formulated. An asymptotic perturbation theory is developed that uses the finger aspect ratio as a small parameter. The leading-order approximation is a modification of the Mullins finger (a well-known analytic solution) whose width is allowed to slowly vary with time. This time dependence is described, in the leading order, by an exponential law with the characteristic time proportional to the (constant) finger area. The subleading terms of the asymptotic theory are also calculated. Finally, the finger dynamics is investigated numerically, employing the Ginzburg-Landau equation with a global conservation law. The theory is in very good agreement with the numerical solution.
Bennett, Matthew R.; Falkingham, Peter; Morse, Sarita A.; Bates, Karl; Crompton, Robin H.
2013-01-01
Human footprints provide some of the most publically emotive and tangible evidence of our ancestors. To the scientific community they provide evidence of stature, presence, behaviour and in the case of early hominins potential evidence with respect to the evolution of gait. While rare in the geological record the number of footprint sites has increased in recent years along with the analytical tools available for their study. Many of these sites are at risk from rapid erosion, including the Ileret footprints in northern Kenya which are second only in age to those at Laetoli (Tanzania). Unlithified, soft-sediment footprint sites such these pose a significant geoconservation challenge. In the first part of this paper conservation and preservation options are explored leading to the conclusion that to ‘record and digitally rescue’ provides the only viable approach. Key to such strategies is the increasing availability of three-dimensional data capture either via optical laser scanning and/or digital photogrammetry. Within the discipline there is a developing schism between those that favour one approach over the other and a requirement from geoconservationists and the scientific community for some form of objective appraisal of these alternatives is necessary. Consequently in the second part of this paper we evaluate these alternative approaches and the role they can play in a ‘record and digitally rescue’ conservation strategy. Using modern footprint data, digital models created via optical laser scanning are compared to those generated by state-of-the-art photogrammetry. Both methods give comparable although subtly different results. This data is evaluated alongside a review of field deployment issues to provide guidance to the community with respect to the factors which need to be considered in digital conservation of human/hominin footprints. PMID:23613743
NASA Astrophysics Data System (ADS)
Savoini, P.; Lembege, B.
2006-12-01
Test particle simulations are performed in order to analyze in details the dynamics of transmitted electrons through a supercritical strictly perpendicular collisionless shock. Recent analysis has evidenced three different behavior for the electron population: (i) adiabatic, (ii) over-adiabatic characterized by an increase of the gyrating velocity higher than that expected from the conservation of the magnetic moment and (iii) under- adiabatic characterized by a decrease of this velocity and not predicted by any existing theory. Analysis of individual time particle trajectories is performed and completed by statistics based on different upstream distributions (spherical shell and Maxwellian). The use of a Maxwellian distribution function allows us to speak in term of an electronic temperature and we observe in agreement with experimental datas that as the temperature increases (enlarged Maxwellian distribution function) the number of non-adiabatic transmitted electrons drastically decreases. In addition, our study evidenced that both non-adiabatic populations are coming from the core of the electron distribution. All combined nonstationary and nonuniformity effects have a filtering impact on the relative percentages of adiabatic and over-adiabatic populations, in contrast with under- adiabatic population which is relatively poorly affected.
Diffusing wave spectroscopy in Maxwellian fluids.
Galvan-Miyoshi, J; Delgado, J; Castillo, R
2008-08-01
We present a critical assessment of the diffusing wave spectroscopy (DWS) technique for obtaining the characteristic lengths and for measuring the loss and storage moduli of a reasonable well-known wormlike micelle (WM) system. For this purpose, we tracked the Brownian motion of particles using DWS embedded in a Maxwellian fluid constituted by a wormlike micellar solution made of cetyltrimethylammonium bromide (CTAB), sodium salicylate (NaSal), and water. We found that the motion of particles was governed by the viscosity of the solvent at short times and by the stress relaxation mechanisms of the giant micelles at longer times. From the time evolution of the mean square displacement of particles, we could obtain for the WM solution the cage size where each particle is harmonically bound at short times, the long-time diffusion coefficient, and experimental values for the exponent that accounts for the broad spectrum of relaxation times at the plateau onset time found in the (deltar2(t)) vs. time curves. In addition, from the (deltar2(t)) vs. time curves, we obtained G'(omega) and G"(omega) for the WM solutions. All the DWS microreological information allowed us to estimate the characteristic lengths of the WM network. We compare our DWS microrheological results and characteristic lengths with those obtained with mechanical rheometers at different NaSal/CTAB concentration ratios and temperatures. PMID:19230210
Maxwellian eye fixation during natural scene perception.
Duchesne, Jean; Bouvier, Vincent; Guillemé, Julien; Coubard, Olivier A
2012-01-01
When we explore a visual scene, our eyes make saccades to jump rapidly from one area to another and fixate regions of interest to extract useful information. While the role of fixation eye movements in vision has been widely studied, their random nature has been a hitherto neglected issue. Here we conducted two experiments to examine the Maxwellian nature of eye movements during fixation. In Experiment 1, eight participants were asked to perform free viewing of natural scenes displayed on a computer screen while their eye movements were recorded. For each participant, the probability density function (PDF) of eye movement amplitude during fixation obeyed the law established by Maxwell for describing molecule velocity in gas. Only the mean amplitude of eye movements varied with expertise, which was lower in experts than novice participants. In Experiment 2, two participants underwent fixed time, free viewing of natural scenes and of their scrambled version while their eye movements were recorded. Again, the PDF of eye movement amplitude during fixation obeyed Maxwell's law for each participant and for each scene condition (normal or scrambled). The results suggest that eye fixation during natural scene perception describes a random motion regardless of top-down or of bottom-up processes. PMID:23226987
Maxwellian Eye Fixation during Natural Scene Perception
Duchesne, Jean; Bouvier, Vincent; Guillemé, Julien; Coubard, Olivier A.
2012-01-01
When we explore a visual scene, our eyes make saccades to jump rapidly from one area to another and fixate regions of interest to extract useful information. While the role of fixation eye movements in vision has been widely studied, their random nature has been a hitherto neglected issue. Here we conducted two experiments to examine the Maxwellian nature of eye movements during fixation. In Experiment 1, eight participants were asked to perform free viewing of natural scenes displayed on a computer screen while their eye movements were recorded. For each participant, the probability density function (PDF) of eye movement amplitude during fixation obeyed the law established by Maxwell for describing molecule velocity in gas. Only the mean amplitude of eye movements varied with expertise, which was lower in experts than novice participants. In Experiment 2, two participants underwent fixed time, free viewing of natural scenes and of their scrambled version while their eye movements were recorded. Again, the PDF of eye movement amplitude during fixation obeyed Maxwell's law for each participant and for each scene condition (normal or scrambled). The results suggest that eye fixation during natural scene perception describes a random motion regardless of top-down or of bottom-up processes. PMID:23226987
Ion-dust streaming instability with non-Maxwellian ions
Kählert, Hanno
2015-07-15
The influence of non-Maxwellian ions on the ion-dust streaming instability in a complex plasma is investigated. The ion susceptibility employed for the calculations self-consistently accounts for the acceleration of the ions by a homogeneous background electric field and their collisions with neutral gas particles via a Bhatnagar-Gross-Krook collision term [e.g., A. V. Ivlev et al., Phys. Rev. E 71, 016405 (2005)], leading to significant deviations from a shifted Maxwellian distribution. The dispersion relation and the properties of the most unstable mode are studied in detail and compared with the Maxwellian case. The largest deviations occur at low to intermediate ion-neutral damping. In particular, the growth rate of the instability for ion streaming below the Bohm speed is found to be lower than in the case of Maxwellian ions, yet remains on a significant level even for fast ion flows above the Bohm speed.
Swartz, Douglas J; Mok, Leo; Botta, Sri K; Singh, Anukriti; Altenberg, Guillermo A; Urbatsch, Ina L
2014-01-01
Pgp (P-glycoprotein) is a prototype ABC (ATP-binding-cassette) transporter involved in multidrug resistance of cancer. We used directed evolution to replace six cytoplasmic Cys (cysteine) residues in Pgp with all 20 standard amino acids and selected for active mutants. From a pool of 75000 transformants for each block of three Cys, we identified multiple mutants that preserved drug resistance and yeast mating activity. The most frequent substitutions were glycine and serine for Cys427 (24 and 20%, respectively) and Cys1070 (37 and 25%) of the Walker A motifs in the NBDs (nucleotide-binding domains), Cys1223 in NBD2 (25 and 8%) and Cys638 in the linker region (24 and 16%), whereas close-by Cys669 tolerated glycine (16%) and alanine (14%), but not serine (absent). Cys1121 in NBD2 showed a clear preference for positively charged arginine (38%) suggesting a salt bridge with Glu269 in the ICL2 (intracellular loop 2) may stabilize domain interactions. In contrast, three Cys residues in transmembrane α-helices could be successfully replaced by alanine. The resulting CL (Cys-less) Pgp was fully active in yeast cells, and purified proteins displayed drug-stimulated ATPase activities indistinguishable from WT (wild-type) Pgp. Overall, directed evolution identified site-specific, non-conservative Cys substitutions that allowed building of a robust CL Pgp, an invaluable new tool for future functional and structural studies, and that may guide the construction of other CL proteins where alanine and serine have proven unsuccessful. PMID:24825346
Lanitis, Sophocles; Filippakis, George; Al Mufti, Ragheed; Hadjiminas, Dimitri J
2008-01-01
Introduction Breast cancer in men is rare. The evidence about treatment has been derived from data on the management of the disease in women. The usual treatment is for male patients to undergo modified radical mastectomy. There is insufficient experience of breast conserving surgery with preservation of the nipple. The management of patients who demand such an approach for personal reasons remains a challenge for both the surgeon and oncologist. Case presentation A 50-year-old man with a breast cancer was successfully managed with breast conserving surgery with nipple preservation combined with axillary clearance and postoperative radiotherapy, chemotherapy and hormone treatment. Since there are no similar cases in the literature, we discuss the feasibility, safety and possible indications of such an approach. Conclusion Despite the limited indications and evidence about the safety and efficacy of breast conserving surgery with nipple preservation in men with breast cancer, it is a feasible approach if other options are declined by the patient. More studies are necessary to reach firm conclusions about the safety of such an approach. PMID:18442386
Weibel instability with non-Maxwellian distribution functions
Zaheer, S.; Murtaza, G.
2007-02-15
The Weibel instability in an unmagnetized plasma is investigated for non-Maxwellian distribution functions. In particular, analytical expressions are derived for the real and imaginary parts of the dielectric constant for the Maxwellian, kappa ({kappa}), and (r,q) distribution functions under the conditions of {xi}={omega}/k{sub parallel}{theta}{sub parallel}>>1 and <<1. The real frequency and the growth rate of the instability now depend upon the values of the spectral indices of the distribution functions. In general, the growth rate is suppressed for small values of {kappa} and q (keeping r fixed) and for negative values of r (keeping q fixed) instability transforms into damping. In the limiting cases (i) {kappa}{yields}{infinity} and (ii) r=0, q{yields}{infinity}, the results approach to the Maxwellian situation.
ERIC Educational Resources Information Center
National Audubon Society, New York, NY.
This set of teaching aids consists of seven Audubon Nature Bulletins, providing the teacher and student with informational reading on various topics in conservation. The bulletins have these titles: Plants as Makers of Soil, Water Pollution Control, The Ground Water Table, Conservation--To Keep This Earth Habitable, Our Threatened Air Supply,…
Waves in non-Maxwellian plasmas with excess superthermal particles
NASA Astrophysics Data System (ADS)
Hellberg, M. A.; Mace, R. L.; Verheest, F.
2000-10-01
Many space plasmas have an excess of superthermal particles and can be modelled by a κ-distribution. While κ-->∞ yields the Maxwellian, a low value of κ describes a power-law distribution with a strongly accelerated, hard spectrum. Wave studies require the generalized plasma dispersion function, which may be expressed in terms of a hypergeometric function, making it easily usable. We review studies of waves in κ-distribution plasmas, focusing inter alia on applications to space plasmas. Wave behavior for low-κ plasmas is significantly different from that found for Maxwellian plasmas. .
NASA Technical Reports Server (NTRS)
Demars, H. G.; Schunk, R. W.
1987-01-01
Conditions corresponding to the steady state subsonic flow of a fully ionized electron-proton plasma in the terrestrial ionosphere are presently characterized by systematically comparing the solutions to the bi-Maxwellian-based 16-moment and Maxwellian-based 13-moment transport equations. The former can account for large temperature anisotropies and the flow of both parallel and perpendicular thermal energy, while the latter account for small temperature anisotropies and only a total heat flow. The comparison is conducted for 2000-10,000 K lower boundary temperatures and 1-4-K/km temperature gradients, over the 1500-13,000-km altitude range.
The generation of random variates from a relativistic Maxwellian distribution
Swisdak, M.
2013-06-15
A procedure for generating random variates from a relativistic Maxwellian distribution with arbitrary temperature and drift velocity is presented. The algorithm is based on the rejection method and can be used to initialize particle velocities in kinetic simulations of plasmas and gases.
On Coulomb collisions in bi-Maxwellian plasmas
Hellinger, Petr; Travnicek, Pavel M.
2009-05-15
Collisional momentum and energy transport in bi-Maxwellian plasmas with a drift velocity along the ambient magnetic field are calculated from both the Fokker-Planck and Boltzmann integral approximations. The transport coefficients obtained from the two approaches are identical to the leading order (proportional to the Coulomb logarithm) and are presented here in a closed form involving generalized double hypergeometric functions.
Langevin representation of Coulomb collisions for bi-Maxwellian plasmas
Hellinger, Petr
2010-07-20
Langevin model corresponding to the Fokker-Planck equation for bi-Maxwellian particle distribution functions is developed. Rosenbluth potentials and their derivatives are derived in the form of triple hypergeometric functions. The Langevin model is tested in the case of relaxation of the proton temperature anisotropy and implemented into the hybrid expanding box model. First results of this code are presented and discussed.
Numerical Loading of a Maxwellian Probability Distribution Function
J. L. V. Lewandowski
2003-03-24
A renormalization procedure for the numerical loading of a Maxwellian probability distribution function (PDF) is formulated. The procedure, which involves the solution of three coupled nonlinear equations, yields a numerically loaded PDF with improved properties for higher velocity moments. This method is particularly useful for low-noise particle-in-cell simulations with electron dynamics.
Friedl, Alexander; Tuerk, Christian; Schima, Wolfgang; Broessner, Clemens
2015-09-01
Xanthogranulomatous pyelonephritis (XP) is a rare form of pyelonephritis and without treatment destructive to the kidney. We describe a 74-year-old Caucasian immunocompetent female patient with XP and multiple abscesses on the upper pole of the right kidney and several impacted obstructing renal calculi in the middle calyx that developed severe colitis and gangrenous appendicitis during therapy. Proteus mirabilis was detected as the major pathogen in the urine culture. Kidney preserving therapy was carried out by intensive parenteral bacterial eradication, CT-guided abscess drainage and stone destruction by 3 sessions of extracorporeal shock wave lithotripsy under ureteral stenting. Large tumor masses in XP are often daunting and may lead to a nephrectomy. However, kidney-preserving therapy is possible and should be considered in non-septic patients or in case of a solitary kidney. PMID:26889137
Friedl, Alexander; Tuerk, Christian; Schima, Wolfgang; Broessner, Clemens
2015-01-01
Xanthogranulomatous pyelonephritis (XP) is a rare form of pyelonephritis and without treatment destructive to the kidney. We describe a 74-year-old Caucasian immunocompetent female patient with XP and multiple abscesses on the upper pole of the right kidney and several impacted obstructing renal calculi in the middle calyx that developed severe colitis and gangrenous appendicitis during therapy. Proteus mirabilis was detected as the major pathogen in the urine culture. Kidney preserving therapy was carried out by intensive parenteral bacterial eradication, CT-guided abscess drainage and stone destruction by 3 sessions of extracorporeal shock wave lithotripsy under ureteral stenting. Large tumor masses in XP are often daunting and may lead to a nephrectomy. However, kidney-preserving therapy is possible and should be considered in non-septic patients or in case of a solitary kidney. PMID:26889137
NASA Astrophysics Data System (ADS)
Gunaratnam, B.; Woyczyński, W. A.
2015-07-01
Recent work has shown that the solutions of the fractal conservation laws driven by Lévy -stable diffusions exhibit shocks for bounded, odd, and convex on the positive half-line, initial data when the parameter We study the analogous situation for the Lévy -Linnik diffusions in which case the local behavior is strikingly different, although we are able to establish analytically that the large time behavior of the two types of conservation laws are similar. But the main new insights obtained via large-scale numerical experiments is that, for any , the conservation laws driven by -Linnik diffusions display shocks that do not dissipate over time, while those for -stable diffusion () do. We formulate rigorous conjectures based on these numerical experiments.
Terrestrial lion roars and non-Maxwellian distribution
NASA Astrophysics Data System (ADS)
Qureshi, M. N. S.; Nasir, Warda; Masood, W.; Yoon, P. H.; Shah, H. A.; Schwartz, S. J.
2014-12-01
Lion roars are low-frequency (˜100 Hz) whistler waves frequently observed in the Earth's magnetosheath. By analyzing both wave and electron data from the Cluster spacecraft, and comparing with linear Vlasov kinetic theory, Masood et al. (2006) investigated the underlying cause of the lion roar generation. However, the analysis based upon the bi-Maxwellian distribution function did not adequately explain the observations qualitatively as well as quantitatively. This outstanding problem is revisited in the present paper, and a resolution is put forth in which, the flat-top non-Maxwellian distribution function with a velocity power law energetic tail, known as the (r,q) distribution, or the generalized kappa distribution is employed. Upon carrying out the linear stability analysis of the (r,q) distribution against the whistler wave perturbation, and upon comparison with the Cluster data, good qualitative and quantitative agreements are found between theory and data.
ERIC Educational Resources Information Center
Stoner, Joyce Hill
2009-01-01
Sixty cultural heritage leaders from thirty-two countries, including representatives from Africa, Asia, the Middle East, South America, Australia, Europe, and North America gathered in October 2009 in Salzburg, Austria, to develop a series of practical recommendations to ensure optimal collections conservation worldwide. Convened at Schloss…
Nonlocal heat transport by non-Maxwellian electrons
Swartz, K.; Short, R.W.
1984-03-30
The generalization of the Spitzer-Harm solution to steep density and temperature gradients requires the computation of the appropriate non-Maxwellian isotropic part of the electron distribution. We develop analytic solutions for a steady state, high-Z plasma, employing the diffusion approximation. Applications of our solution include computation of the resulting heat flux, thermal smoothing of transverse temperature perturbations, and modification of linear heat flow instabilities.
Garnett, J.L.; Major, G.
1982-01-01
The technique of using radiation polymerization for the restoration and preservation of art treasures is considered. The processes discussed include both radiation grafting and rapid cure procedures, particularly reactions initiated by uv and eb. Representative examples where the technique has already been used are treated including typical applications with paintings, tapestries, leather and archival repair. The structure of the monomers and oligomers used in both grafting and rapid cure systems is outlined. The experimental conditions where grafting may occur during radiation rapid cure processing are discussed. Possible future developments of the technique are outlined. 1 figure, 8 tables.
Baltan, Selva; Murphy, Sean P.; Danilov, Camelia A.; Bachleda, Amelia; Morrison, Richard S.
2011-01-01
The importance of white matter (WM) injury to stroke pathology has been underestimated in experimental animal models and this may have contributed to the failure to translate potential therapeutics into the stroke clinic. Histone deacetylase (HDAC) inhibitors are neuroprotective and also promote neurogenesis. These properties make them ideal candidates for stroke therapy. In a pure WM tract (isolated mouse optic nerve) we show that pan- and Class I specific HDAC inhibitors, administered before or after a period of oxygen and glucose deprivation (OGD), promote functional recovery of axons and preserve WM cellular architecture. This protection correlates with the up-regulation of an astrocyte glutamate transporter, delayed and reduced glutamate accumulation during OGD, preservation of axonal mitochondria and oligodendrocytes, and maintenance of ATP levels. Interestingly, the expression of HDACs 1, 2 and 3 is localized to astrocytes, suggesting that changes in glial cell gene transcription and/or protein acetylation may confer protection to axons. Our findings suggest that a therapeutic opportunity exists for the use of HDAC inhibitors, targeting mitochondrial energy regulation and excitotoxicity in ischemic WM injury. PMID:21411642
Alpert, Tracy E.; Kuerer, Henry M.; Arthur, Douglas W.; Lannin, Donald R.; Haffty, Bruce G. . E-mail: hafftybg@umdnj.edu
2005-11-01
Purpose: To compare outcomes of salvage mastectomy (SM) and salvage breast-conserving surgery (SBCS) and study the feasibility of SBCS. Methods and Materials: Of 2,038 patients treated with breast-conserving therapy at Yale-New Haven Hospital before 1999, 166 sustained an ipsilateral breast tumor recurrence (IBTR). Outcomes and prognostic factors of patients treated with SM or SBCS were compared. Patients were considered amenable to SBCS if the recurrence was localized on mammogram and physical examination, and had pathologic size <3 cm, confined to the biopsy site, without skin or lymphovascular invasion, and with {<=}3 positive nodes. Results: Of the 146 patients definitively managed at IBTR, surgery was SM (n = 116) or SBCS (n 30). The median length of follow-up after IBTR was 13.8 years. The SM and SBCS cohorts had no significant differences, except at IBTR the SM cohort had a greater tumor size (p = 0.049). Of the SM cohort, 65.5% were considered appropriate for SBCS, and a localized relapse was predicted by estrogen-receptor positive, diploid, and detection of recurrence by mammogram. Multicentric disease correlated with BRCA1/2 mutation, estrogen-receptor negative, lymph node positive at relapse, and detection of recurrence by physical examination. Survival after IBTR was 64.5% at 10 years, with no significant difference between SM (65.7%) and SBCS (58.0%). Only 2 patients in the SBCS cohort subsequently had a second IBTR, and were salvaged with mastectomy. Conclusions: While mastectomy is considered the standard surgical salvage of IBTR, SBCS is feasible and prognostic factors are related to favorable tumor biology and early detection. Patients with BRCA1/2 germline mutations may be less appropriate for SBCS, as multicentric disease was more prevalent. Patients who underwent SBCS had comparable outcomes as those who underwent SM, but remain at continued risk for IBTR. A prospective trial evaluating repeat lumpectomy and partial breast reirradiation is
NASA Astrophysics Data System (ADS)
Le Chenadec, Vincent; Bay, Yong Yi
2015-11-01
The treatment of complex geometries in Computational Fluid Dynamics applications is a challenging endeavor, which immersed boundary and cut-cell techniques can significantly simplify by alleviating the meshing process required by body-fitted meshes. These methods also introduce new challenges, in that the formulation of accurate and well-posed discrete operators is not trivial. A cut-cell method for the solution of the incompressible Navier-Stokes equation is proposed for staggered Cartesian grids. In both scalar and vector cases, the emphasis is set on the structure of the discrete operators, designed to mimic the properties of the continuous ones while retaining a nearest-neighbor stencil. For convective transport, different forms are proposed (divergence, advective and skew-symmetric), and shown to be equivalent when the discrete continuity equation is satisfied. This ensures mass, momentum and kinetic energy conservation. For diffusive transport, conservative and symmetric operators are proposed for both Dirichlet and Neumann boundary conditions. Symmetry ensures the existence of a sink term (viscous dissipation) in the discrete kinetic energy budget, which is beneficial for stability. The accuracy of method is finally assessed in standard test cases.
NASA Astrophysics Data System (ADS)
Araki, Keisuke
2015-05-01
The dynamics of a dissipationless incompressible Hall magnetohydrodynamic (HMHD) medium is formulated using Lagrangian mechanics on a semidirect product of two volume preserving diffeomorphism groups. In the case of {{{T}}3} or E3, the generalized Elsässer variables (GEV) introduced by (Galtier 2006 J. Plasma Phys. 72 721-69) yield remarkably simple expressions of basic formulas and equations such as the structure constants of Lie algebra, the equation of motion, and the conservation laws. Four constants of motion, where three of the four are independent, are naturally derived from the GEV representation of the equation of motion for the HMHD system: total plasma energy, magnetic helicity, hybrid helicity, and the modified cross helicity.
NASA Astrophysics Data System (ADS)
Field, L. A.; Manzara, A.; Chetty, S.; Venkatesh, S.; Scholtz, A.
2015-12-01
Ice911 Research has conducted years of field testing to develop and test localized reversible engineering techniques to mitigate the negative impacts of polar ice melt. The technology uses environmentally safe materials to reflect energy in carefully selected, limited areas from summertime polar sun. The technology is now being adapted to help with California's drought. We have tested the albedo modification technique on a small scale over seven Winter/Spring seasons at sites including California's Sierra Nevada Mountains, a Canadian lake, and a small artificial pond in Minnesota about 100 ft in diameter and 6 ft deep at the center, using various materials and an evolving array of instrumentation. On the pond in Minnesota, this year's test results for ice preservation, using hollow glass spheres deployed over our largest test areas yet, showed that glass bubbles can provide an effective material for increasing albedo, significantly reducing the melting rate of ice. This year Ice911 also undertook its first small Arctic field test in Barrow, Alaska on a lake in Barrow's BEO area, and results are still coming in. The technology that Ice911 has been developing for ice preservation has also been shown to keep small test areas of water cooler, in various small-scale tests spanning years. We believe that with some adaptations of the technology, the materials can be applied to reservoirs and lakes to help stretch these precious resources further in California's ongoing drought. There are several distinct advantages for this method over alternatives such as large reverse osmosis projects or building new reservoirs, which could possibly allow a drought-stricken state to build fewer of these more-costly alternatives. First, applying an ecologically benign surface treatment of Ice911's materials can be accomplished within a season, at a lower cost, with far less secondary environmental impact, than such capital-and-time-intensive infrastructure projects. Second, keeping
Langmuir wave dispersion relation in non-Maxwellian plasmas
Ouazene, M.; Annou, R.
2010-05-15
The Langmuir wave dispersion relation is derived in partially ionized plasmas, where free electrons are confined to move in a nearest neighbor ions' potential well. The equilibrium velocity distribution function experiences then, a departure from Maxwell distribution function. The effect of the non-Maxwellian character of the distribution function on the Langmuir phase and group velocities as well as the phase matching conditions and the nonlinear growth rate of decay instability is investigated. The proposed Langmuir wave dispersion relation is relevant to dense and cryogenic plasmas.
Landau damping of Langmuir waves in non-Maxwellian plasmas
Ouazene, M.; Annou, R.
2011-11-15
As free electrons move in the nearest neighbour ion's potential well, the equilibrium velocity departs from Maxwell distribution. The effect of the non-Maxwellian velocity distribution function (NMVDF) on many properties of the plasma such as the transport coefficients, the kinetic energy, and the degree of ionization is found to be noticeable. A correction to the Langmuir wave dispersion relation is proved to arise due to the NMVDF as well [Phys. Plasmas 17, 052105 (2010)]. The study is extended hereafter to include the effect of NMVDF on the Landau damping of Langmuir wave.
ERIC Educational Resources Information Center
DeCandido, Robert
Collections conservation is an approach to the preservation treatment of books and book-like materials that is conceptualized and organized in terms of large groups of materials. This guide is intended to enable a library to evaluate its current collections conservation activities. The introduction describes collections conservation and gives…
Analog and Digitgal Simulations of Maxwellian Plasmas for Astrophysics
Savin, D W; Badnell, N R; Beiersdorfer, P; Beck, B R; Brown, G V; Bryans, P; Gorczyca, T W; Gu, M F; Kahn, S M; Laming, J M; Liedahl, D A; Mitthumsiri, W; Scofield, J H; Wong, K L
2007-02-24
Many astrophysical and laboratory plasmas possess Maxwell-Boltzmann (MB) electron energy distributions (EEDs). Interpreting or predicting the properties of these plasmas requires accurate knowledge of atomic processes such as radiative lifetimes, electron impact excitation and de-excitation, electron impact ionization, radiative recombination, dielectronic recombination, and charge transfer for thousands of levels or more. Plasma models cannot include all of the needed levels and atomic data. Hence approximations need to be made to make the models tractable. Here we report on an 'analog' technique we have developed for simulating a Maxwellian EED using an electron beam ion trap and review some recent results using this method. A subset of the atomic data needed for modeling Maxwellian plasmas relates to calculating the ionization balance. Accurate fractional abundance calculations for the different ionization stages of the various elements in the plasma are needed to reliably interpret or predict the properties of the gas. However, much of the atomic data needed for these calculations have not been generated using modern theoretical methods and are often highly suspect. Here we will also review our recent updating of the recommended atomic data for 'digital' computer simulations of MB plasmas in collisional ionization equilibrium (CIE), describe the changes relative to previously recommended CIE calculations, and discuss what further recombination and ionization data are needed to improve this latest set of recommended CIE calculations.
ERIC Educational Resources Information Center
New York State Library, Albany. Div. of Library Development.
This document is composed of clippings from news publications and press releases about projects funded by the New York State Discretionary Grant Program for Conservation and Preservation of Library Research Materials, which annually awards $500,000 to libraries, archives, historical societies, and similar agencies in New York State through…
NON-MAXWELLIAN Halpha PROFILES IN TYCHO'S SUPERNOVA REMNANT
Raymond, John C.; Winkler, P. Frank; Blair, William P.; Lee, Jae-Joon; Park, Sangwook E-mail: winkler@middlebury.ed E-mail: lee.j.joon@gmail.co
2010-04-01
The broad components of the Halpha lines in most non-radiative shocks can be fit with single-Gaussian components. We have obtained a high-quality spectrum of a position in Tycho's supernova remnant with the MMT and Blue Channel Spectrograph which shows, for the first time, that a single Gaussian does not provide an acceptable fit. This implies that a single temperature Maxwellian particle velocity distribution cannot produce the emission. Possible alternative explanations are explored, including multiple shocks along the line of sight, a pickup ion contribution, a non-thermal tail (Kappa distribution), emission from a precursor in a cosmic ray modified shock, or turbulence. An Hubble Space Telescope image shows a bright knot that might account for a low temperature contribution, and all the possibilities probably contribute at some level. We discuss the implications of each explanation for the shock parameters and physics of collisionless shocks, but cannot conclusively rule out any of them.
The Use of Langmuir Probes in Non-Maxwellian Space Plasmas
NASA Technical Reports Server (NTRS)
Hoegy, Walter R.; Brace, Larry H.
1998-01-01
Disturbance of the Maxwellian plasma may occur in the vicinity of a spacecraft due to photoemission, interactions between the spacecraft and thermospheric gases, or electron emissions from other devices on the spacecraft. Significant non-maxwellian plasma distributions may also occur in nature as a mixture of ionospheric and magnetospheric plasmas or secondaries produced by photoionization in the thermosphere or auroral precipitation. The general formulas for current collection (volt-ampere curves) by planar, cylindrical, and spherical Langmuir probes in isotropic and anisotropic non-maxwellian plasmas are examined. Examples are given of how one may identify and remove the non-maxwellian components in the Langmuir probe current to permit the ionospheric parameters to be determined. Theoretical volt-ampere curves presented for typical examples of non-maxwellian distributions include: two-temperature plasmas and a thermal plasma with an energetic electron beam. If the non-ionospheric electrons are Maxwellian at a temperature distinct from that of the ionosphere electrons, the volt-ampere curves can be fitted directly to obtain the temperatures and densities of both electron components without resorting to differenting the current. For an arbitrary isotropic distribution, the current for retarded particles is shown to be identical for the three geometries. For anisotropic distributions, the three probe geometries are not equally suited for measuring the ionospheric electron temperature and density or for determining the distribution function in the presence of non-maxwellian back-round electrons.
Deeba, F.; Ahmad, Zahoor; Murtaza, G.
2010-10-15
A generalized dielectric constant for the electron Bernstein waves using non-Maxwellian distribution functions is derived in a collisionless, uniform magnetized plasma. Using the Neumann series expansion for the products of Bessel functions, we can derive the dispersion relations for both kappa and the generalized (r,q) distributions in a straightforward manner. The dispersion relations now become dependent upon the spectral indices {kappa} and (r,q) for the kappa and the generalized (r,q) distribution, respectively. Our results show how the non-Maxwellian dispersion curves deviate from the Maxwellian depending upon the values of the spectral indices chosen. It may be noted that the (r,q) dispersion relation is reduced to the kappa distribution for r=0 and q={kappa}+1, which, in turn, is further reducible to the Maxwellian distribution for {kappa}{yields}{infinity}.
Bullock, Shawn Michael
2014-01-01
In the late Victorian Era, a group of British physicists devoted their time to interpreting and extending the work of James Clerk Maxwell. There has been considerable discussion about the ways in which these "Maxwellian" physicists used mechanical models by in the for research purposes; less attention has been paid to the relevance of their mechanical models for pedagogical purposes. Drawing from educational research literature, I begin from the premise that understanding a scientist's self-identity in its historical context is crucial to understanding how she or he enacts particular pedagogical approaches. I aim to extend Bruce Hunt's seminal work on the Maxwellians by providing a pedagogical analysis of one of Sir Oliver Lodge's lectures. In so doing, I claim that Lodge drew on his identity as a Maxwellian as an organizing framework for his lecture and that he attempted to engage his audience in Maxwellian thought by exposing them to many mechanical models. I conclude that Lodge's self-concept as a teacher and his apparent broad appeal as a public educationist were deeply embedded in his life history as a member of the Maxwellians. Sir Oliver Lodge's identities as a Maxwellian and a pedagogue are inextricably linked. PMID:25261114
Super-Maxwellian helium evaporation from pure and salty water
NASA Astrophysics Data System (ADS)
Hahn, Christine; Kann, Zachary R.; Faust, Jennifer A.; Skinner, J. L.; Nathanson, Gilbert M.
2016-01-01
Helium atoms evaporate from pure water and salty solutions in super-Maxwellian speed distributions, as observed experimentally and modeled theoretically. The experiments are performed by monitoring the velocities of dissolved He atoms that evaporate from microjets of pure water at 252 K and 4-8.5 molal LiCl and LiBr at 232-252 K. The average He atom energies exceed the flux-weighted Maxwell-Boltzmann average of 2RT by 30% for pure water and 70% for 8.5m LiBr. Classical molecular dynamics simulations closely reproduce the observed speed distributions and provide microscopic insight into the forces that eject the He atoms from solution. Comparisons of the density profile and He kinetic energies across the water-vacuum interface indicate that the He atoms are accelerated by He-water collisions within the top 1-2 layers of the liquid. We also find that the average He atom kinetic energy scales with the free energy of solvation of this sparingly soluble gas. This free-energy difference reflects the steeply decreasing potential of mean force on the He atoms in the interfacial region, whose gradient is the repulsive force that tends to expel the atoms. The accompanying sharp decrease in water density suppresses the He-water collisions that would otherwise maintain a Maxwell-Boltzmann distribution, allowing the He atom to escape at high energies. Helium is especially affected by this reduction in collisions because its weak interactions make energy transfer inefficient.
Analysis of measurement errors for Thomson diagnostics of non-Maxwellian plasmas in tokamak reactors
NASA Astrophysics Data System (ADS)
Sdvizhenskii, P. A.; Kukushkin, A. B.; Kurskiev, G. S.; Mukhin, E. E.; Bassan, M.
2016-01-01
The study is stimulated by the expected noticeable deviation of the electron velocity distribution function (eVDF) from a Maxwellian under condition of a strong auxiliary heating of electron plasmas in tokamak-reactors. The key principles of accuracy estimation of the Thomson scattering diagnostic of non-Maxwellian plasmas in tokamak-reactors are presented. The algorithm extends the conventional approach to the assessment of non-Maxwellian plasmas measurements errors for a broad class of deviations of the eVDF from a Maxwellian. The algorithm is based on solving the inverse problem many times to determine main parameters of the eVDF with allowance for all possible sources of error and statistical variation of the input parameters of the problem. The method is applied to a preliminary analysis of the advantages of the formerly suggested use of various wavelengths of probing laser radiation in the Thomson diagnostics of non-Maxwellian plasma on the example of the core plasma Thomson scattering diagnostic system which is under design for ITER tokamak. The results obtained confirm the relevance of the diversification of the probing laser radiation wavelength.
Dust-ion-acoustic solitons in plasmas with non-Maxwellian electron distribution function
Pajouh, H. Hakimi; Abbasi, H.
2008-10-15
Stationary dust-ion-acoustic (DIA) solitons in plasma with non-Maxwellian electron distribution function (DF) are studied. This is an important issue in low-pressure electrical gas discharges that the particle DF is generally non-Maxwellian. In the discharge plasmas, the electron temperature is usually much greater than the ion temperature. Thus, neglecting the ions velocity distribution, the electron DF is modeled by the generalized Lorentzian ({kappa})-DF. The formalism is derived near the ion-plasma frequency. In this range of frequency, the ion dynamics is considerable and the dust-ion-acoustic solitons are the stationary solution of the governing equations. Electron trapping is included in the model as the result of nonlinear resonant interaction of the DIA soliton with electrons. The solitons attributes and influence of the non-Maxwellian electrons are studied.
Statistical charge distribution over dust particles in a non-Maxwellian Lorentzian plasma
NASA Astrophysics Data System (ADS)
Mishra, S. K.; Misra, Shikha
2014-07-01
On the basis of statistical mechanics and charging kinetics, the charge distribution over uniform size spherical dust particles in a non-Maxwellian Lorentzian plasma is investigated. Two specific situations, viz., (i) the plasma in thermal equilibrium and (ii) non-equilibrium state where the plasma is dark (no emission) or irradiated by laser light (including photoemission) are taken into account. The formulation includes the population balance equation for the charged particles along with number and energy balance of the complex plasma constituents. The departure of the results for the Lorentzian plasma, from that in case of Maxwellian plasma, is graphically illustrated and discussed; it is shown that the charge distribution tends to results corresponding to Maxwellian plasma for large spectral index. The charge distribution predicts the opposite charging of the dust particles in certain cases.
Statistical charge distribution over dust particles in a non-Maxwellian Lorentzian plasma
Mishra, S. K.; Misra, Shikha
2014-07-15
On the basis of statistical mechanics and charging kinetics, the charge distribution over uniform size spherical dust particles in a non-Maxwellian Lorentzian plasma is investigated. Two specific situations, viz., (i) the plasma in thermal equilibrium and (ii) non-equilibrium state where the plasma is dark (no emission) or irradiated by laser light (including photoemission) are taken into account. The formulation includes the population balance equation for the charged particles along with number and energy balance of the complex plasma constituents. The departure of the results for the Lorentzian plasma, from that in case of Maxwellian plasma, is graphically illustrated and discussed; it is shown that the charge distribution tends to results corresponding to Maxwellian plasma for large spectral index. The charge distribution predicts the opposite charging of the dust particles in certain cases.
Sepehri Javan, N.
2014-10-15
Self-focusing of an intense circularly polarized laser pulse propagating through a magnetized non-Maxwellian plasma is investigated. Based on a relativistic two-fluid model, nonlinear equation describing dynamics of the slowly varying amplitude is obtained. The evolution of laser spot size is studied and effect of non-Maxwellian distribution of charge density on the spot size is considered. It is shown that the existence of super-thermal particles leads to the enhancement of the self-focusing quality of plasma.
Global Solutions of the Boltzmann Equation Over {{R}^D} Near Global Maxwellians with Small Mass
NASA Astrophysics Data System (ADS)
Bardos, Claude; Gamba, Irene M.; Golse, François; Levermore, C. David
2016-07-01
We study the dynamics defined by the Boltzmann equation set in the Euclidean space {{R}^D} in the vicinity of global Maxwellians with finite mass. A global Maxwellian is a special solution of the Boltzmann equation for which the collision integral vanishes identically. In this setting, the dispersion due to the advection operator quenches the dissipative effect of the Boltzmann collision integral. As a result, the large time limit of solutions of the Boltzmann equation in this regime is given by noninteracting, freely transported states and can be described with the tools of scattering theory.
Electrostatic ion waves in non-Maxwellian pair-ion plasmas
Arshad, Kashif; Mahmood, S.
2010-12-15
The electrostatic ion waves are studied for non-Maxwellian or Lorentzian distributed unmagnetized pair-ion plasmas. The Vlasov equation is solved and damping rates are calculated for electrostatic waves in Lorentzian pair-ion plasmas. The damping rates of the electrostatic ion waves are studied for the equal and different ion temperatures of pair-ion species. It is found that the Landau damping rate of the ion plasma wave is increased in Lorentzian plasmas in comparison with Maxwellian pair-ion plasmas. The numerical results are also presented for illustration by taking into account the parameters reported in fullerene pair-ion plasma experiments.
Solutions to bi-Maxwellian transport equations for the polar wind
NASA Technical Reports Server (NTRS)
Demars, H. G.; Schunk, R. W.
1989-01-01
In this study, polar wind solutions are obtained for a broad range of O(+) density, H(+) drift velocity, electron temperature and H(+) temperature boundary conditions. The bi-Maxwellian-based 16-moment set of transport equations is used, since this set is expected to be superior to Maxwellian-based equations in describing large temperature anisotropies and heat flows. The present solutions corroborate earlier results when similar boundary conditions are used. Also, for previously unexplored combinations of boundary conditions, the present solutions are often qualitatively different from any obtained before.
Zaheer, S.; Murtaza, G.; Shah, H.A.
2006-06-15
Electromagnetic modes (ordinary and extraordinary) for strongly magnetized plasma are studied and their damping factors {gamma}{sub or} and {gamma}{sub ex} are calculated using non-Maxwellian velocity distribution function. It is observed that for moderate values of the spectral indices r and q [used in (r, q) distribution functions], both the damping decrements show substantial change. As the value of the spectral index r increases for a fixed value of q, the damping increases for the O mode but decreases for the X mode. In the limiting case of r=0, q{yields}{infinity}, the damping factors reduce to the standard Maxwellian values.
Modeling of laser induced plasma expansion in the presence of non-Maxwellian electrons
Bennaceur-Doumaz, D.; Djebli, M.
2010-07-15
The one-dimensional expansion into vacuum of ion-electron plasma produced by laser ablation is investigated. The ions considered as an ideal fluid are governed by a fluid model where charge quasineutrality is assumed to prevail, while electron density follows a non-Maxwellian distribution. Showing that the expansion can be described by a self-similar solution, the resulting nonlinear Euler equations are solved numerically. It is found that the deviation of the electrons from Maxwellian distribution gives rise to new asymptotic solutions of physical interest affecting the density and velocity of plasma expansion.
L2-stability of the Vlasov-Maxwell-Boltzmann system near global Maxwellians
NASA Astrophysics Data System (ADS)
Ha, Seung-Yeal; Xiao, Qinghua; Xiong, Linjie; Zhao, Huijiang
2013-12-01
We present a L2-stability theory of the Vlasov-Maxwell-Boltzmann system for the two-species collisional plasma. We show that in a perturbative regime of a global Maxwellian, the L2-distance between two strong solutions can be controlled by that between initial data in a Lipschitz manner. Our stability result extends earlier results [Ha, S.-Y. and Xiao, Q.-H., "A revisiting to the L2-stability theory of the Boltzmann equation near global Maxwellians," (submitted) and Ha, S.-Y., Yang, X.-F., and Yun, S.-B., "L2 stability theory of the Boltzmann equation near a global Maxwellian," Arch. Ration. Mech. Anal. 197, 657-688 (2010)] on the L2-stability of the Boltzmann equation to the Boltzmann equation coupled with self-consistent external forces. As a direct application of our stability result, we show that classical solutions in Duan et al. ["Optimal large-time behavior of the Vlasov-Maxwell-Boltzmann system in the whole space," Commun. Pure Appl. Math. 24, 1497-1546 (2011)] and Guo ["The Vlasov-Maxwell-Boltzmann system near Maxwellians," Invent. Math. 153(3), 593-630 (2003)] satisfy a uniform L2-stability estimate. This is the first result on the L2-stability of the Boltzmann equation coupled with self-consistent field equations in three dimensions.
Beausang, K V; Prunty, S L; Scannell, R; Beurskens, M N; Walsh, M J; de la Luna, E
2011-03-01
The present work is motivated by a long standing discrepancy between the electron temperature measurements of Thomson scattering (TS) and electron cyclotron emission (ECE) diagnostics for plasmas with strong auxiliary heating observed at both JET and TFTR above 6–7 keV, where in some cases the ECE electron temperature measurements can be 15%–20% higher than the TS measurements. Recent analysis based on ECE results at JET has shown evidence of distortions to the Maxwellian electron velocity distribution and a correlation with the TS and ECE discrepancies has been suggested. In this paper, a technique to determine the presence of non-Maxwellian behavior using TS diagnostics is outlined. The difficulties and limitations of modern TS system designs to determine the electron velocity distribution are also discussed. It is demonstrated that small deviations such as those suggested by previous ECE analysis could be potentially detected, depending on the spectral layout of the TS polychromators. The spectral layout of the JET high resolution Thomson scattering system is such that it could be used to determine these deviations between 1 and 6 keV, and the results presented here indicate that no evidence of non-Maxwellian behavior is observed in this range. In this paper, a modification to the current polychromator design is proposed, allowing non-Maxwellian distortions to be detected up to at least 10 keV. PMID:21585113
Non-Maxwellian electron distributions in models of the solar atmosphere
NASA Technical Reports Server (NTRS)
Macneice, P.; Fontenla, J.; Ljepojevic, N. N.
1991-01-01
In this paper, the solar models of Fontenla et al. (1990) are extended to coronal temperatures using optically thin radiative losses and a semicircular loop geometry. The effects of a non-Maxwellian high-energy tail of the electron distribution function is tested by performing a Fokker-Planck calculation of the tail. The results show that the downward conductive heat flux is very clsoe to that given by Braginskii (1965) for small departures from a Maxwellian distribution. The effects of the high-energy tail of the electron distribution on element ionization are computed and found to be negligible for all ionization states of O, Ne, and Si. It is concluded that, for quiet sun loop models in stationary energy balance, the ionization state of all elements is not significantly affected by the non-Maxwellian tail of the electron velocity distribution, and that the heat flux can be computed by considering only small first-order departures from the Maxwellian distribution.
Beausang, K. V.; Prunty, S. L.; Scannell, R.; Beurskens, M. N.; Walsh, M. J.; Collaboration: JET EFDA Contributors
2011-03-15
The present work is motivated by a long standing discrepancy between the electron temperature measurements of Thomson scattering (TS) and electron cyclotron emission (ECE) diagnostics for plasmas with strong auxiliary heating observed at both JET and TFTR above 6-7 keV, where in some cases the ECE electron temperature measurements can be 15%-20% higher than the TS measurements. Recent analysis based on ECE results at JET has shown evidence of distortions to the Maxwellian electron velocity distribution and a correlation with the TS and ECE discrepancies has been suggested. In this paper, a technique to determine the presence of non-Maxwellian behavior using TS diagnostics is outlined. The difficulties and limitations of modern TS system designs to determine the electron velocity distribution are also discussed. It is demonstrated that small deviations such as those suggested by previous ECE analysis could be potentially detected, depending on the spectral layout of the TS polychromators. The spectral layout of the JET high resolution Thomson scattering system is such that it could be used to determine these deviations between 1 and 6 keV, and the results presented here indicate that no evidence of non-Maxwellian behavior is observed in this range. In this paper, a modification to the current polychromator design is proposed, allowing non-Maxwellian distortions to be detected up to at least 10 keV.
A model distribution function for relativistic bi-Maxwellian with drift
Naito, O.
2013-04-15
A model distribution function for relativistic bi-Maxwellian with drift is proposed, based on the maximum entropy principle and the relativistic canonical transformation. Since the obtained expression is compatible with the existing distribution functions and has a relatively simple form as well as smoothness, it might serve as a useful tool in the research fields of space or high temperature fusion plasmas.
Dispersion relation for pure dust Bernstein waves in a non-Maxwellian magnetized dusty plasma
Deeba, F.; Ahmad, Zahoor; Murtaza, G.
2011-07-15
Pure dust Bernstein waves are investigated using non-Maxwellian kappa and (r,q) distribution functions in a collisionless, uniform magnetized dusty plasma. Dispersion relations for both the distributions are derived by considering waves whose frequency is of the order of dust cyclotron frequency, and dispersion curves are plotted. It is observed that the propagation band for dust Bernstein waves is rather narrow as compared with that of the electron Bernstein waves. However, the band width increases for higher harmonics, for both kappa and (r,q) distributions. Effect of dust charge on dispersion curves is also studied, and one observes that with increasing dust charge, the dispersion curves shift toward the lower frequencies. Increasing the dust to ion density ratio ((n{sub d0}/n{sub i0})) causes the dispersion curve to shift toward the higher frequencies. It is also found that for large values of spectral index kappa ({kappa}), the dispersion curves approach to the Maxwellian curves. The (r,q) distribution approaches the kappa distribution for r = 0, whereas for r > 0, the dispersion curves show deviation from the Maxwellian curves as expected. Relevance of this work can be found in astrophysical plasmas, where non-Maxwellian velocity distributions as well as dust particles are commonly observed.
NASA Astrophysics Data System (ADS)
Dzifčáková, Elena; Dudík, Jaroslav
2015-12-01
We use the latest available atomic data to calculate the ionisation and recombination rates for the non-Maxwellian n-distributions, which were shown previously to provide a good fit to the enhanced intensities of dielectronic satellite lines during solar flares. The ionisation and recombination coefficients are subsequently used to derive the ionisation equilibrium. To do so, we consider odd values of n ranging from 1 to 19, i.e., from Maxwellian to strongly non-Maxwellian cases. These calculations involve all elements with proton number up to 30, i.e., H to Zn. The n-distributions modify both the ionisation and the recombination rates. The ionisation rates decrease more steeply at lower pseudo-temperatures, while the radiative recombination rate is reduced due to a lower number of low-energy electrons. The peaks of the dielectronic recombination rates become narrower. These changes are reflected in the ionisation equilibrium. Ion abundance peaks become narrower and can also be shifted, mostly towards higher temperatures. The He-like ions are an important exception, as they are formed in a larger temperature range than that for the Maxwellian distribution. The ions Si xiii - xiv used previously for the diagnostics of the n-distributions are affected only weakly, confirming the determination of n. The ionisation equilibria are available as the electronic supplementary material in a format compatible with the CHIANTI database.
Kinetic corrections from analytic non-Maxwellian distribution functions in magnetized plasmas
Izacard, Olivier
2016-08-02
In magnetized plasma physics, almost all developed analytic theories assume a Maxwellian distribution function (MDF) and in some cases small deviations are described using the perturbation theory. The deviations with respect to the Maxwellian equilibrium, called kinetic effects, are required to be taken into account especially for fusion reactor plasmas. Generally, because the perturbation theory is not consistent with observed steady-state non-Maxwellians, these kinetic effects are numerically evaluated by very central processing unit (CPU)-expensive codes, avoiding the analytic complexity of velocity phase space integrals. We develop here a new method based on analytic non-Maxwellian distribution functions constructed from non-orthogonal basismore » sets in order to (i) use as few parameters as possible, (ii) increase the efficiency to model numerical and experimental non-Maxwellians, (iii) help to understand unsolved problems such as diagnostics discrepancies from the physical interpretation of the parameters, and (iv) obtain analytic corrections due to kinetic effects given by a small number of terms and removing the numerical error of the evaluation of velocity phase space integrals. This work does not attempt to derive new physical effects even if it could be possible to discover one from the better understandings of some unsolved problems, but here we focus on the analytic prediction of kinetic corrections from analytic non-Maxwellians. As applications, examples of analytic kinetic corrections are shown for the secondary electron emission, the Langmuir probe characteristic curve, and the entropy. This is done by using three analytic representations of the distribution function: the Kappa distribution function, the bi-modal or a new interpreted non-Maxwellian distribution function (INMDF). The existence of INMDFs is proved by new understandings of the experimental discrepancy of the measured electron temperature between two diagnostics in JET. As main
Kinetic corrections from analytic non-Maxwellian distribution functions in magnetized plasmas
NASA Astrophysics Data System (ADS)
Izacard, Olivier
2016-08-01
In magnetized plasma physics, almost all developed analytic theories assume a Maxwellian distribution function (MDF) and in some cases small deviations are described using the perturbation theory. The deviations with respect to the Maxwellian equilibrium, called kinetic effects, are required to be taken into account especially for fusion reactor plasmas. Generally, because the perturbation theory is not consistent with observed steady-state non-Maxwellians, these kinetic effects are numerically evaluated by very central processing unit (CPU)-expensive codes, avoiding the analytic complexity of velocity phase space integrals. We develop here a new method based on analytic non-Maxwellian distribution functions constructed from non-orthogonal basis sets in order to (i) use as few parameters as possible, (ii) increase the efficiency to model numerical and experimental non-Maxwellians, (iii) help to understand unsolved problems such as diagnostics discrepancies from the physical interpretation of the parameters, and (iv) obtain analytic corrections due to kinetic effects given by a small number of terms and removing the numerical error of the evaluation of velocity phase space integrals. This work does not attempt to derive new physical effects even if it could be possible to discover one from the better understandings of some unsolved problems, but here we focus on the analytic prediction of kinetic corrections from analytic non-Maxwellians. As applications, examples of analytic kinetic corrections are shown for the secondary electron emission, the Langmuir probe characteristic curve, and the entropy. This is done by using three analytic representations of the distribution function: the Kappa distribution function, the bi-modal or a new interpreted non-Maxwellian distribution function (INMDF). The existence of INMDFs is proved by new understandings of the experimental discrepancy of the measured electron temperature between two diagnostics in JET. As main results, it
More than Ten Years After: Identity and Direction in Library Preservation.
ERIC Educational Resources Information Center
Jones, Maralyn
1991-01-01
Reviews the literature of preservation for 1990. Topics addressed include preservation in original format; conservation treatment; pest management; deterioration of paper, deacidification, and paper strengthening; preservation replacement; newer reformatting technologies; the management of preservation programs; education for preservation…
Whale Preservation. Grades Five to Nine.
ERIC Educational Resources Information Center
Racicot, Darlene
Dedicated to the conservation and preservation of whales, dolphins, and porpoises through public education, this instructional unit for grades 5-9 provides current (1993) facts, lesson plans, activities, and conservation and preservation techniques. Interdisciplinary activities involve students in debates, critical thinking, research, and…
NASA Technical Reports Server (NTRS)
Moore, Reagan W.
2004-01-01
The long-term preservation of digital entities requires mechanisms to manage the authenticity of massive data collections that are written to archival storage systems. Preservation environments impose authenticity constraints and manage the evolution of the storage system technology by building infrastructure independent solutions. This seeming paradox, the need for large archives, while avoiding dependence upon vendor specific solutions, is resolved through use of data grid technology. Data grids provide the storage repository abstractions that make it possible to migrate collections between vendor specific products, while ensuring the authenticity of the archived data. Data grids provide the software infrastructure that interfaces vendor-specific storage archives to preservation environments.
Preserving Library Materials in the South Pacific.
ERIC Educational Resources Information Center
Kivia, Ivarature
1994-01-01
Discusses problems of preservation and conservation of library materials in the South Pacific, including environmental factors, insect and animal pests, and mishandling. Describes the situation in national, public, and academic libraries in the region; factors in planning library buildings to promote preservation; and preservation efforts at the…
The Preservation of Paper Collections in Archives.
ERIC Educational Resources Information Center
Adams, Cynthia Ann
The preservation methods used for paper collections in archives were studied through a survey of archives in the metropolitan Atlanta (Georgia) area. The preservation policy or program was studied, and the implications for conservators and preservation officers were noted. Twelve of 15 archives responded (response rate of 80 percent). Basic…
NASA Technical Reports Server (NTRS)
Smith, Scott M. (Inventor); Nillen, Jeannie (Inventor)
2001-01-01
Disclosed is CPG, a combination of a chlorhexidine salt (such as chlorhexidine digluconate, chlorhexidine diacetate, or chlorhexidine dichloride) and n-propyl gallate that can be used at ambient temperatures as a urine preservative.
Sub- and super-Maxwellian evaporation of simple gases from liquid water
NASA Astrophysics Data System (ADS)
Kann, Z. R.; Skinner, J. L.
2016-04-01
Non-Maxwellian evaporation of light atoms and molecules (particles) such as He and H2 from liquids has been observed experimentally. In this work, we use simulations to study systematically the evaporation of Lennard-Jones particles from liquid water. We find instances of sub- and super-Maxwellian evaporation, depending on the mass of the particle and the particle-water interaction strength. The observed trends are in qualitative agreement with experiment. We interpret these trends in terms of the potential of mean force and the effectiveness and frequency of collisions during the evaporation process. The angular distribution of evaporating particles is also analyzed, and it is shown that trends in the energy from velocity components tangential and normal to the liquid surface must be understood separately in order to interpret properly the angular distributions.
Sub- and super-Maxwellian evaporation of simple gases from liquid water.
Kann, Z R; Skinner, J L
2016-04-21
Non-Maxwellian evaporation of light atoms and molecules (particles) such as He and H2 from liquids has been observed experimentally. In this work, we use simulations to study systematically the evaporation of Lennard-Jones particles from liquid water. We find instances of sub- and super-Maxwellian evaporation, depending on the mass of the particle and the particle-water interaction strength. The observed trends are in qualitative agreement with experiment. We interpret these trends in terms of the potential of mean force and the effectiveness and frequency of collisions during the evaporation process. The angular distribution of evaporating particles is also analyzed, and it is shown that trends in the energy from velocity components tangential and normal to the liquid surface must be understood separately in order to interpret properly the angular distributions. PMID:27389228
H to Zn Ionization Equilibrium for the Non-Maxwellian Electron κ-distributions: Updated Calculations
NASA Astrophysics Data System (ADS)
Dzifčáková, E.; Dudík, J.
2013-05-01
New data for the calculation of ionization and recombination rates have been published in the past few years, most of which are included in the CHIANTI database. We used these data to calculate collisional ionization and recombination rates for the non-Maxwellian κ-distributions with an enhanced number of particles in the high-energy tail, which have been detected in the solar transition region and the solar wind. Ionization equilibria for elements H to Zn are derived. The κ-distributions significantly influence both the ionization and recombination rates and widen the ion abundance peaks. In comparison with the Maxwellian distribution, the ion abundance peaks can also be shifted to lower or higher temperatures. The updated ionization equilibrium calculations result in large changes for several ions, notably Fe VIII-Fe XIV. The results are supplied in electronic form compatible with the CHIANTI database.
Relaxation rates in the Maxwellian collision model and its variable hard sphere surrogate
NASA Astrophysics Data System (ADS)
Rubinstein, Robert
2015-08-01
The variable hard sphere and related models have proven to be accurate and computationally convenient replacements for the inverse power law model of classical kinetic theory in direct simulation Monte Carlo calculations. We attempt to provide theoretical support for this remarkable success by comparing the relaxation rates in the linearized Boltzmann equation for the Maxwellian collision model with those of its variable hard sphere surrogate. The comparison demonstrates that the linearized collision operator with variable hard sphere interactions can accurately approximate the linearized collision operator with Maxwellian inverse power law interactions under well-defined and broadly applicable conditions. Extensions of the analysis to the general inverse power law model and to more realistic intermolecular potentials are briefly discussed.
L{sup 2}-stability of the Vlasov-Maxwell-Boltzmann system near global Maxwellians
Ha, Seung-Yeal Xiao, Qinghua; Xiong, Linjie Zhao, Huijiang
2013-12-15
We present a L{sup 2}-stability theory of the Vlasov-Maxwell-Boltzmann system for the two-species collisional plasma. We show that in a perturbative regime of a global Maxwellian, the L{sup 2}-distance between two strong solutions can be controlled by that between initial data in a Lipschitz manner. Our stability result extends earlier results [Ha, S.-Y. and Xiao, Q.-H., “A revisiting to the L{sup 2}-stability theory of the Boltzmann equation near global Maxwellians,” (submitted) and Ha, S.-Y., Yang, X.-F., and Yun, S.-B., “L{sup 2} stability theory of the Boltzmann equation near a global Maxwellian,” Arch. Ration. Mech. Anal. 197, 657–688 (2010)] on the L{sup 2}-stability of the Boltzmann equation to the Boltzmann equation coupled with self-consistent external forces. As a direct application of our stability result, we show that classical solutions in Duan et al. [“Optimal large-time behavior of the Vlasov-Maxwell-Boltzmann system in the whole space,” Commun. Pure Appl. Math. 24, 1497–1546 (2011)] and Guo [“The Vlasov-Maxwell-Boltzmann system near Maxwellians,” Invent. Math. 153(3), 593–630 (2003)] satisfy a uniform L{sup 2}-stability estimate. This is the first result on the L{sup 2}-stability of the Boltzmann equation coupled with self-consistent field equations in three dimensions.
On heat conduction in multicomponent, non-Maxwellian spherically symmetric solar wind plasmas
NASA Technical Reports Server (NTRS)
Cuperman, S.; Dryer, M.
1985-01-01
A generalized expression for the steady-state heat flux in multicomponent, moderately non-Maxwellian spherically symmetric plasmas is presented and discussed. The work was motivated by the inability of the simple, Fourier-type formula for the thermal conductivity to explain the observed correlations in the solar wind. The results hold for situations not far from local thermodynamic equilibrium. The generalized expression includes not only correlations that have been observed but also correlations not sought for previously.
Maps of precipitating electron spectra characterized by Maxwellian and kappa distributions
NASA Astrophysics Data System (ADS)
McIntosh, R. C.; Anderson, P. C.
2014-12-01
Maps of characterized auroral electron spectra, developed using 8 years of particle spectrometer data from the Defense Meteorological Satellite Program (DMSP) suite of polar-orbiting spacecraft are presented. The electron spectra, which were sampled from both hemispheres, are categorized as either diffuse or accelerated. Diffuse spectra were best-fit with Maxwellian or kappa distributions, and accelerated spectra were identified as displaying characteristics of either monoenergetic or broadband acceleration. A total of 30 million spectra were characterized, with 47.05% being best-fit with Maxwellian distributions, 31.37% being best-fit with kappa distributions, 12.20% as monoenergetic, and 9.38% as broadband. The spectra from both hemispheres were then binned in MLAT-MLT using a bin size of (MLAT, MLT) = (1°, 0.25 h), for the ranges of 50° ≤ MLAT < 90° and 0000 ≤ MLT < 2400, and further separated into seven levels of Kp. Within each MLAT-MLT-Kp bin, the fraction of the bin total number of accelerated and best-fit spectra corresponding to each spectral type was calculated. Consideration of the global distribution of these fractions showed the following results. For Kp< 2, diffuse electron spectra were predominantly best-fit by Maxwellian distributions. With increasing Kp, more of the diffuse spectra were best-fit by kappa distributions, especially within 0000 < MLT < 0600. For Kp< 2, monoenergetic spectra occurred throughout the oval at MLAT > 70° and broadband spectra occurred within 75° < MLAT < 80° and the local time regions of 0600 < MLT < 1000 and 1300 < MLT < 1500. For Kp≥ 2, coverage of accelerated spectra varied with Kp. For low levels of Kp, accelerated spectra, primarily monoenergetic spectra, predominated above 70°. With increasing activity, broadband spectra covered more of the daytime MLT sectors, while diffuse spectra (Maxwellian and Lorentzian) became increasingly frequent on the nightside due to the poleward expansion of the diffuse
Interaction of impurity ions with a weakly non-Maxwellian simple hydrogenic plasma. [None
Terry, W.K.
1988-03-01
The average acceleration of an ensemble of /open quotes/test particles/close quotes/ in a plasma is called the /open quotes/dynamical friction/close quotes/; the average rate at which their velocity vectors spread out in velocity-space diffusion-rate tensor. These quantities are derived for impurity ions intereacting with a weakly non-Maxwellian simple hydrogenic plasma. The distribution functions for the plasma ions and electrons are written explicitly.
Quasi-linear heating and acceleration in bi-Maxwellian plasmas
Hellinger, Petr; Trávníček, Pavel M.
2013-12-15
Quasi-linear acceleration and heating rates are derived for drifting bi-Maxwellian distribution functions in a general nonrelativistic case for arbitrary wave vectors, propagation angles, and growth/damping rates. The heating rates in a proton-electron plasma due to ion-cyclotron/kinetic Alfvén and mirror waves for a wide range of wavelengths, directions of propagation, and growth or damping rates are explicitly computed.
NASA Astrophysics Data System (ADS)
Ou, Jing; Lin, Binbin; Zhao, Xiaoyun; Yang, Youlei
2016-07-01
The formation of a sheath in front of a carbon or tungsten material plane immersed in a plasma containing non-Maxwellian energetic electrons and secondary emission electrons is studied using a 1D model. In the model, energetic electrons are described by the electron energy distribution function (EEDF) and secondary electron emission (SEE) is produced by the electrons impinging on the wall. It is found that SEE coefficient depends on not only the sheath potential but also the EEDF profile of energetic electrons when a non-Maxwellian energetic electron component is present. The energetic electrons and associated secondary emission electrons can strongly modify ion velocity at sheath edge, floating potential and I–V probe characteristic. Due to the interdependence between SEE coefficient originating from the impact of non-Maxwellian energetic electrons on the wall and the sheath potential, with the increase in the energy of energetic electrons, a sudden jump phenomenon can be found in the profiles of SEE coefficient and other quantities such as floating potential and ion velocity at the sheath edge for tungsten wall, while for carbon wall they are the continuous variation. To begin with, the energetic electron component does not dominate the sheath, and I–V probe characteristic depends on both the EEDF profile of energetic electrons and material properties. Once the energetic electron component dominates the sheath, the analysis of I–V probe characteristic will yield the energy of energetic electrons.
A Revisiting of the -Stability Theory of the Boltzmann Equation Near Global Maxwellians
NASA Astrophysics Data System (ADS)
Ha, Seung-Yeal; Xiao, Qinghua
2015-07-01
We study the -stability theory of the Boltzmann equation near a global Maxwellian. When an initial datum is a perturbation of a global Maxwellian, we show that the -distance between two classical solutions can be controlled by the initial data in a Lipschitz manner, which illustrates the Lipschitz continuity of the solution operator for the Boltzmann equation in -topology. Our local-in-time -stability results cover cutoff very soft potentials as well as non-cutoff hard and soft potentials. These cases were not treated in the previous work (Ha et al. in Arch Ration Mech Anal 197:657-688, 2010). Thus, our results together with the results in Ha et al. (2010) complete the -stability theory for the Boltzmann equation near a global Maxwellian. For this -stability estimate, we use the coercivity estimate of the linearized collision operator, the smallness of perturbation in a mixed Lebesgue norm, and Strichartz-type estimates of perturbation. We also show that for all classical solutions available in the literature, the Lipschitz constant can be chosen as independent of time to obtain the uniform -stability of the Boltzmann equation.
NASA Astrophysics Data System (ADS)
Mirza, Arshad M.; Masood, W.; Iqbal, Javed; Batool, Nazia
2015-09-01
Nonlinear equations which govern the dynamics of low-frequency toroidal ion-temperature-gradient driven modes (i.e., ω ≪ ω c i , where ωci is the ion gyro-frequency) are derived in the presence of equilibrium density, temperature, and magnetic field gradients. In the nonlinear case, solutions in the form of dipolar vortices and vortex street are presented for a plasma comprising of Maxwellian ions and nonthermal electrons that are embedded in an external magnetic field. By using Braginskii's transport equations for the Maxwellian ions and Kappa distributed electrons, the coupled mode equations for the system under consideration are derived. The results have been applied in Tokamak plasmas, and it has been observed that the scale lengths over which the nonlinear vortex structures form get modified in the presence of Kappa distributed electrons. The present study is also applicable to tokamaks and stellarators where non-Maxwellian population has been observed in resonant frequency heating, electron cyclotron heating experiments, and in runaway electrons.
Conservation of Library Materials.
ERIC Educational Resources Information Center
Illinois Libraries, 1985
1985-01-01
Twelve articles cover books as artifacts; workstations for conservation of library materials; care of scrapbooks, albums, and photographs; map preservation; library environment; flood recovery; disaster prevention and preparedness; incorporating preservation into library organization; and bibliography of Chester Public Library (Illinois) First…
Technology Transfer Automated Retrieval System (TEKTRAN)
Plant conservation has several objectives the main ones include safeguarding our food supply, preserving crop wild relatives for breeding and selection of new cultivars, providing material for industrial and pharmaceutical uses and preserving the beauty and diversity of our flora for generations to ...
ERIC Educational Resources Information Center
Noriega, Chon A.
2005-01-01
One must undertake multi-institutional efforts that include universities, archives, museums, libraries and community-based arts organizations and the artists to preserve Latino art history. Arts infrastructure can be strengthened by various Chicano Studies Research Center projects that are concerned with archive building and scholarship, and with…
ERIC Educational Resources Information Center
Yakel, Elizabeth
2001-01-01
Reviews research on digital preservation issues, including born-digital and digitally recreated documents. Discusses electronic records research; metadata and other standards; electronic mail; Web-based documents; moving images media; selection of materials for digitization, including primary sources; administrative issues; media stability…
NASA Technical Reports Server (NTRS)
1989-01-01
A new class of polyimides, synthesized by Langley Research Center, has been evaluated by the Getty Conservation Institute's Materials Science Group for possible art conservation applications. Polyimides are noted for resistance to high temperature, wear and radiation. They are thermally stable and soluble in some common solvents. After testing under simulated exposures for changes in color, permeability and flexibility, one coating, ODPA-3, 3-ODA may be used to protect bronze statues from corrosion. A test on stained glass windows was unsuccessful.
Huh, Sung-Ryul; Kim, Nam-Kyun; Jung, Bong-Ki; Chung, Kyoung-Jae; Hwang, Yong-Seok; Kim, Gon-Ho
2015-03-15
A global model was developed to investigate the densities of negative ions and the other species in a low-pressure inductively coupled hydrogen plasma with a bi-Maxwellian electron energy distribution. Compared to a Maxwellian plasma, bi-Maxwellian plasmas have higher populations of low-energy electrons and highly vibrationally excited hydrogen molecules that are generated efficiently by high-energy electrons. This leads to a higher reaction rate of the dissociative electron attachment responsible for negative ion production. The model indicated that the bi-Maxwellian electron energy distribution at low pressures is favorable for the creation of negative ions. In addition, the electron temperature, electron density, and negative ion density calculated using the model were compared with the experimental data. In the low-pressure regime, the model results of the bi-Maxwellian electron energy distributions agreed well quantitatively with the experimental measurements, unlike those of the assumed Maxwellian electron energy distributions that had discrepancies.
An asymptotic preserving Monte Carlo method for the multispecies Boltzmann equation
NASA Astrophysics Data System (ADS)
Zhang, Bin; Liu, Hong; Jin, Shi
2016-01-01
An asymptotic preserving (AP) scheme is efficient in solving multiscale kinetic equations with a wide range of the Knudsen number. In this paper, we generalize the asymptotic preserving Monte Carlo method (AP-DSMC) developed in [25] to the multispecies Boltzmann equation. This method is based on the successive penalty method [26] originated from the BGK-penalization-based AP scheme developed in [7]. For the multispecies Boltzmann equation, the penalizing Maxwellian should use the unified Maxwellian as suggested in [12]. We give the details of AP-DSMC for multispecies Boltzmann equation, show its AP property, and verify through several numerical examples that the scheme can allow time step much larger than the mean free time, thus making it much more efficient for flows with possibly small Knudsen numbers than the classical DSMC.
Ne IX line G-ratio in a non-Maxwellian and anisotropic plasma
NASA Astrophysics Data System (ADS)
Ferouani, A. K.; Inal, M. K.; Csanak, G.
2013-04-01
We have theoretically studied how the presence of a small proportion of energetic beam electrons mixed to a bulk of Maxwellian electrons in a hot plasma affects the temperature-dependent intensity ratio G = (x + y + z)/w of the helium-like triplet intercombination (x, y) and forbidden (z) lines to the singlet resonance line (w). By modelling the electron distribution function as a combination of a Maxwellian isotropic component and a monoenergetic beam component, detailed calculations of the G ratio of the Ne8 + lines have been performed for temperatures Te of the Maxwellian component and kinetic energies e0 of the beam component in the ranges 106-107 K and 1.5-25 keV, respectively. A magnetic sublevel-to-magnetic sublevel collisional-radiative model has been used for determining the populations of the upper magnetic sublevels of the four lines at an electron density below 1013 cm-3. Excitations from the ground 1s2 1S0 and metastable 1s2s 3S1 magnetic sublevels to the 1snl (n = 2-4) magnetic sublevels as well as the inner-shell ionization of the lithium-like ion in its ground level were taken into account. All basic atomic data, including the radiative transition probabilities and the collisional excitation and ionization cross sections, were computed using the flexible atomic code. It is found that the contribution of a 5% fraction of the beam component can reduce the G ratio by a factor of 30 at Te = 106 K and of 2.4 at Te = 3 × 106 K. Our calculations also indicate that the effect of directionality of the beam component on G is negligible for e0 above ˜10 keV and that for a given Te, G is practically insensitive to variations in e0 above ˜7 keV.
NASA Astrophysics Data System (ADS)
Vafin, S.; Schlickeiser, R.; Yoon, P. H.
2016-05-01
The general electromagnetic fluctuation theory for magnetized plasmas is used to calculate the steady-state wave number spectra and total electromagnetic field strength of low-frequency collective weakly damped eigenmodes with parallel wavevectors in a Maxwellian electron-proton plasma. These result from the equilibrium of spontaneous emission and collisionless damping, and they represent the minimum electromagnetic fluctuations guaranteed in quiet thermal space plasmas, including the interstellar and interplanetary medium. Depending on the plasma beta, the ratio of |δB |/B0 can be as high as 10-12 .
Dormant bud preservation for germplasm conservation
Technology Transfer Automated Retrieval System (TEKTRAN)
The suitability of dormant buds (DB) for cryopreservation of different plant species has been demonstrated in several reports. For the majority of the species, processing DB for long-term liquid nitrogen storage does not involve establishing tissue cultures and the time for growing out post-cryo mat...
On the rogue waves propagation in non-Maxwellian complex space plasmas
NASA Astrophysics Data System (ADS)
El-Tantawy, S. A.; El-Awady, E. I.; Tribeche, M.
2015-11-01
The implications of the non-Maxwellian electron distributions (nonthermal/or suprathermal/or nonextensive distributions) are examined on the dust-ion acoustic (DIA) rogue/freak waves in a dusty warm plasma. Using a reductive perturbation technique, the basic set of fluid equations is reduced to a nonlinear Schrödinger equation. The latter is used to study the nonlinear evolution of modulationally unstable DIA wavepackets and to describe the rogue waves (RWs) propagation. Rogue waves are large-amplitude short-lived wave groups, routinely observed in space plasmas. The possible region for the rogue waves to exist is defined precisely for typical parameters of space plasmas. It is shown that the RWs strengthen for decreasing plasma nonthermality and increasing superthermality. For nonextensive electrons, the RWs amplitude exhibits a bit more complex behavior, depending on the entropic index q. Moreover, our numerical results reveal that the RWs exist with all values of the ion-to-electron temperature ratio σ for nonthermal and superthermal distributions and there is no limitation for the freak waves to propagate in both two distributions in the present plasma system. But, for nonextensive electron distribution, the bright- and dark-type waves can propagate in this case, which means that there is a limitation for the existence of freak waves. Our systematic investigation should be useful in understanding the properties of DIA solitary waves that may occur in non-Maxwellian space plasmas.
NASA Astrophysics Data System (ADS)
Ahmad, Ali; Masood, W.
2016-05-01
Linear and nonlinear electrostatic ion acoustic waves in a weakly relativistic magnetorotating plasma in the presence of non-Maxwellian electrons and warm ions have been examined. The system under consideration has yielded two solutions, namely, the fast and slow acoustic modes which have been observed to depend on the streaming velocity, ion to electron temperature ratio, and the nonthermality parameter of the non-Maxwellian electrons. Using the multiple time scale analysis, we have derived the three dimensional nonlinear Zakharov-Kuznetsov equation and also presented its solution. Both compressive and rarefactive solitary structures have been found in consonance with the satellite observations. It has been observed that although the linear dispersion relation gives both fast and slow ion acoustic waves, the solitary structures form only for the fast acoustic mode. The dependence of the characteristics of the solitary structures on several plasma parameters has also been explored. The present investigation may be beneficial to understanding the rotating plasma environments such as those found in the planetary magnetospheres of Saturn and Jupiter.
On the rogue waves propagation in non-Maxwellian complex space plasmas
El-Tantawy, S. A. El-Awady, E. I.; Tribeche, M. E-mail: mtribeche@usthb.dz
2015-11-15
The implications of the non-Maxwellian electron distributions (nonthermal/or suprathermal/or nonextensive distributions) are examined on the dust-ion acoustic (DIA) rogue/freak waves in a dusty warm plasma. Using a reductive perturbation technique, the basic set of fluid equations is reduced to a nonlinear Schrödinger equation. The latter is used to study the nonlinear evolution of modulationally unstable DIA wavepackets and to describe the rogue waves (RWs) propagation. Rogue waves are large-amplitude short-lived wave groups, routinely observed in space plasmas. The possible region for the rogue waves to exist is defined precisely for typical parameters of space plasmas. It is shown that the RWs strengthen for decreasing plasma nonthermality and increasing superthermality. For nonextensive electrons, the RWs amplitude exhibits a bit more complex behavior, depending on the entropic index q. Moreover, our numerical results reveal that the RWs exist with all values of the ion-to-electron temperature ratio σ for nonthermal and superthermal distributions and there is no limitation for the freak waves to propagate in both two distributions in the present plasma system. But, for nonextensive electron distribution, the bright- and dark-type waves can propagate in this case, which means that there is a limitation for the existence of freak waves. Our systematic investigation should be useful in understanding the properties of DIA solitary waves that may occur in non-Maxwellian space plasmas.
Choi, Ikjin; Chung, ChinWook; Youn Moon, Se
2013-08-15
In plasma diagnostics with a single Langmuir probe, the electron temperature T{sub e} is usually obtained from the slope of the logarithm of the electron current or from the electron energy probability functions of current (I)-voltage (V) curve. Recently, Chen [F. F. Chen, Phys. Plasmas 8, 3029 (2001)] suggested a derivative analysis method to obtain T{sub e} by the ratio between the probe current and the derivative of the probe current at a plasma potential where the ion current becomes zero. Based on this method, electron temperatures and electron densities were measured and compared with those from the electron energy distribution function (EEDF) measurement in Maxwellian and bi-Maxwellian electron distribution conditions. In a bi-Maxwellian electron distribution, we found the electron temperature T{sub e} obtained from the method is always lower than the effective temperatures T{sub eff} derived from EEDFs. The theoretical analysis for this is presented.
15 CFR 923.22 - Areas for preservation or restoration.
Code of Federal Regulations, 2012 CFR
2012-01-01
... (Continued) NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE OCEAN AND COASTAL... designated for the purpose of preserving or restoring them for their conservation, recreational,...
15 CFR 923.22 - Areas for preservation or restoration.
Code of Federal Regulations, 2014 CFR
2014-01-01
... (Continued) NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE OCEAN AND COASTAL... designated for the purpose of preserving or restoring them for their conservation, recreational,...
15 CFR 923.22 - Areas for preservation or restoration.
Code of Federal Regulations, 2010 CFR
2010-01-01
... (Continued) NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE OCEAN AND COASTAL... designated for the purpose of preserving or restoring them for their conservation, recreational,...
15 CFR 923.22 - Areas for preservation or restoration.
Code of Federal Regulations, 2013 CFR
2013-01-01
... (Continued) NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE OCEAN AND COASTAL... designated for the purpose of preserving or restoring them for their conservation, recreational,...
15 CFR 923.22 - Areas for preservation or restoration.
Code of Federal Regulations, 2011 CFR
2011-01-01
... (Continued) NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE OCEAN AND COASTAL... designated for the purpose of preserving or restoring them for their conservation, recreational,...
National and International Policies for Preservation.
ERIC Educational Resources Information Center
Feather, John
1990-01-01
Discusses the preservation and conservation of materials in libraries and archives and describes national and international policies that have been developed to deal with preservation problems. Highlights include managerial responsibility; paper-making and book production standards; the role of national libraries; coordination of policies;…
Abbasi, H.; Hakimi Pajouh, H.
2008-09-15
The satellite observations of the magnetosphere in the low-frequency ion dynamics revealed several facts: (1) localized structures for electric field signal parallel to the magnetic field; (2) anisotropy for the electron velocity distribution such that T{sub perpendicular}<
Pritychenko, B.
2010-07-19
Present contribution represents a significant improvement of our previous calculation of Maxwellian-averaged cross sections and astrophysical reaction rates. Addition of newly-evaluated neutron reaction libraries, such as ROSFOND and Low-Fidelity Covariance Project, and improvements in data processing techniques allowed us to extend it for entire range of sprocess nuclei, calculate Maxwellian-averaged cross section uncertainties for the first time, and provide additional insights on all currently available neutron-induced reaction data. Nuclear reaction calculations using ENDF libraries and current Java technologies will be discussed and new results will be presented.
Supsar, Markus; Schlickeiser, Reinhard E-mail: rsch@tp4.rub.de
2014-03-10
The distant universe is opaque to γ radiation from blazars due to gamma-gamma attenuation with extragalactic background light. This process produces electron-positron pair beams that interact with the intergalactic medium and are unstable to linear instabilities, particularly the electrostatic and Weibel instabilities. The electrostatic instability grows faster and so determines the dissipation of the free energy of the beam. Here, we generalize the calculation of the electrostatic growth rate to a beam plasma system with a Maxwellian perpendicular momentum spread and allow for oblique propagation directions. We show that the growth rate for the oblique electrostatic mode has a maximum value that is even higher than for a cold beam or for one with a constant perpendicular momentum spread.
Observation of Non-Maxwellian Electron Distributions in th e NSTX Divertor
M.A. Jaworski, et. al.
2013-03-07
The scrape-off layer plasma at the tokamak region is characterized by open field lines and often contains large variations in plasma properties along these field-lines. Proper characterization of local plasma conditions is critical to assessing plasma-material interaction processes occuring at the target. Langmuir probes are frequently employed in tokamak divertors but are challenging to interpretation. A kinetic interpretation for Langmuir probes in NSTX has yielded non-Maxwellian electron distributions in the divertor characterized by cool bulk populations and energetic tail populations with temperatures of 2-4 times the bulk. Spectroscopic analysis and modeling confirms the bulk plasma temperature and density which can only be obtained with the kinetic interpretation
Linear and nonlinear dynamics of electron temperature gradient mode in non-Maxwellian plasmas
Zakir, U.; Qamar, A.; Haque, Q.
2013-05-15
The effect of non-Maxwellian distributed ions on electron temperature gradient mode is investigated. The linear dispersion relation of η{sub e}−mode is obtained which shows that the behavior of this mode changes in the presence of superthermal ions. The growth rate of η{sub e}−mode driven linear instability is found and is observed to modify due to nonthermal ions. However, it is found that this leaves the electron energy transport coefficient unchanged. In the nonlinear regime, a dipolar vortex solution is derived which indicates that the dynamic behavior of the vortices changes with the inclusion of kappa distributed ions. The importance of present study with respect to space and laboratory plasmas is also pointed out.
Rarefaction shock in plasma with a bi-Maxwellian electron distribution function
Diaw, A.; Mora, P.
2011-09-15
The one-dimensional collisionless expansion into a vacuum of a plasma with a bi-Maxwellian electron distribution function and a single ion species is studied both theoretically and numerically. A shock wave occurs when the ratio of the temperatures between the hot and the cold electrons is larger than 5+{radical}(24)[B. Bezzerides, D. W. Forslund, and E. L. Lindman, Phys. Fluids 21, 2179 (1978)]. The theoretical model presented here gives a coherent and complete description of the rarefaction shock and its effects on the ion acceleration process. Analytical expressions of the characteristics of the shock are given. The analytical findings are compared to the results of a hybrid code describing the plasma expansion, and an excellent agreement is obtained.
Rarefaction shock in plasma with a bi-Maxwellian electron distribution function.
Diaw, A; Mora, P
2011-09-01
The one-dimensional collisionless expansion into a vacuum of a plasma with a bi-Maxwellian electron distribution function and a single ion species is studied both theoretically and numerically. A shock wave occurs when the ratio of the temperatures between the hot and the cold electrons is larger than 5+√24 [B. Bezzerides, D. W. Forslund, and E. L. Lindman, Phys. Fluids 21, 2179 (1978)]. The theoretical model presented here gives a coherent and complete description of the rarefaction shock and its effects on the ion acceleration process. Analytical expressions of the characteristics of the shock are given. The analytical findings are compared to the results of a hybrid code describing the plasma expansion, and an excellent agreement is obtained. PMID:22060508
Collisional relaxation of bi-Maxwellian plasma temperatures in magnetized plasmas
NASA Astrophysics Data System (ADS)
Yoon, Peter H.
2016-07-01
In the literature, collisional processes are customarily discussed within the context of the Boltzmann-Balescu-Lenard-Landau type of collision integral, but such an equation is strictly valid for unmagnetized plasmas. For plasmas immersed in the ambient magnetic field, the foundational equation that describes binary collisions must be generalized to include the effects of magnetic field. The present paper makes use of such an equation in order to describe the collisional relaxation of temperatures under the assumption of bi-Maxwellian velocity distribution function. The formalism derived in the present paper may be useful for studying the effects of binary collisions on the isotropization of temperatures in the solar wind plasma, among possible applications.
Salm, M; Lücke, M
2012-10-01
The structure formation of convection rolls in Maxwellian fluids that are heated from below in a Rayleigh-Bénard setup is investigated close to onset with a simple few-modes ansatz and by solving the hydrodynamic field equations with a finite-difference method. Depending on the magnitude of the viscoelastic relaxation time one can have besides stationary convection also oscillatory patterns in the form of standing or traveling waves. The existence and stability regions of these convection structures are determined. The convection behavior of the model is compared with the results of full numerical simulations. Furthermore, the effect of modulating the heating periodically in time on the stability of the quiescent conductive state of the fluid and on its convection behavior is investigated as a function of the fluid's viscoelasticity. PMID:23214682
X-ray analysis of nonMaxwellian distributions (current drive)
von Goeler, S.; Stevens, J.; Stodiek, W.
1983-06-01
The plasma bremsstrahlung emission is utilized to determine the shape of the electron velocity distribution in situations where it deviates strongly from a Maxwellian distribution. The instrumentation used to measure the hard x-ray emission is briefly discussed. Model calculations show that polarization measurements give best results for unrelativistic tails with tail temperatures T/sub b/ < 50 keV, whereas measurements of the angular distribution of the x-ray emission based on the forward scattering of bremsstrahlung for relativistic electrons yields the best information for T/sub b/ > 50 keV. The techniques were originally developed in order to analyze runaway discharges. Recently, they found new interest because of the formation of energetic electron tails during current drive. The first x-ray results from the current drive during LH heating on PLT are discussed.
Electron acoustic wave driven vortices with non-Maxwellian hot electrons in magnetoplasmas
Haque, Q.; Mirza, Arshad M.; Zakir, U.
2014-07-15
Linear dispersion characteristics of the Electron Acoustic Wave (EAW) and the corresponding vortex structures are investigated in a magnetoplasma in the presence of non-Maxwellian hot electrons. In this regard, kappa and Cairns distributed hot electrons are considered. It is noticed that the nonthermal distributions affect the phase velocity of the EAW. Further, it is found that the phase velocity of EAW increases for Cairns and decreases for kappa distributed hot electrons. Nonlinear solutions in the form of dipolar vortices are also obtained for both stationary and non-stationary ions in the presence of kappa distributed hot electrons and dynamic cold electrons. It is found that the amplitude of the nonlinear vortex structures also reduces with kappa factor like the electron acoustic solitons.
Two-stream Maxwellian kinetic theory of cloud droplet growth by condensation
NASA Technical Reports Server (NTRS)
Robinson, N. F.; Scott, W. T.
1981-01-01
A new growth rate formula (NGRF) is developed for the rate of growth of cloud droplets by condensation. The theory used is a modification of the Lees-Shankar theory in which the two-stream Maxwellian distribution function of Lees is used in Maxwell's method of moments to determine the transport of water vapor to and heat away from the droplet. Boundary conditions at the droplet are the usual conditions set in terms of accommodation coefficients, and the solution passes smoothly into diffusion flow in the far region. Comparisons are given between NGRF and the conventional formula showing close agreement (approximately 0.1%) for large radii with significant difference (approximately 5%) for small radii (not greater than 1 micron). Growth times for haze droplets in a Laktionov chamber are computed.
Planning for Preservation during Mass Digitization Projects
ERIC Educational Resources Information Center
Teper, Jennifer Hain; Shaw, Emily F.
2011-01-01
In anticipation of current and future mass digitization projects in which the University of Illinois at Urbana-Champaign's Library will participate, the Library's Conservation Unit began to gather data on the "scannability" of our general book collections to anticipate potential effects on conservation and preservation work flows. The findings…
Whistler Cyclotron Electromagnetic Fluctuations in a Maxwellian and Tsallis-kappa-like Plasma
NASA Astrophysics Data System (ADS)
Vinas, A. F.; Moya, P. S.; Navarro, R.; Araneda, J. A.
2014-12-01
Observed electron velocity distributions in the Earth's magnetosphere and the solar wind exhibit a variety of non-thermal features which deviate from thermal equilibrium, for example, in the form of temperature anisotropies, suprathermal tail extensions, and field aligned beams. The state close to thermal equilibrium and its departure from it provides a source for spontaneous emissions of electromagnetic fluctuations, such as the whistler. Here we present a comparative analysis of whistler-cyclotron fluctuations based upon anisotropic plasma modeled with Maxwellian and Tsallis kappa-like particle distributions, to explain the correspondence relationship of the magnetic fluctuations as a function of the electron temperature and thermal anisotropy in the solar wind and magnetosphere plasmas. The analysis presented here considers correlation theory of the fluctuation-dissipation theorem and the dispersion relation of transverse fluctuations, with wave vectors parallel to the uniform background magnetic field, in a finite temperature anisotropic thermal bi-Maxwellian and non-thermal Tsallis-kappa-like magnetized electron-proton plasma. Dispersion analysis and stability thresholds are derived for these thermal and non-thermal distributions using plasma and field parameters relevant to the solar wind and magnetosphere environments. Our results indicate that there is an enhancement of the fluctuations level in the case of non-thermal distributions due to the effective higher-temperature and the excess of suprathermal particles. These results suggest that a comparison of the electromagnetic fluctuations due to thermal and non-thermal distributions provides a diagnostic signature by which inferences about the nature of the particle velocity distribution function can be ascertained without in-situ particle measurements.
Deeba, F.; Ahmad, Zahoor; Murtaza, G.
2006-08-15
The electrostatic potentials (Debye and wake) and energy loss due to a charged projectile propagating through an unmagnetized collisionless dusty plasma are derived employing kappa and generalized (r,q) velocity distributions for the dust acoustic wave. It is found that these quantities in general differ from their Maxwellian counterparts and are sensitive to the values of spectral index, {kappa} in the case of kappa distribution and to r, q in the case of generalized (r,q) distribution. The amplitudes of these quantities are less for small values of the spectral index ({kappa}, r=0, q) but approach the Maxwellian in the limit {kappa}{yields}{infinity} (for kappa distribution) and for r=0, q{yields}{infinity} [for generalized (r,q) distribution]. For any nonzero value of r, the potential and the energy loss grow beyond the Maxwellian results. The effect of kappa and generalized (r,q) distributions on potential and energy loss is also studied numerically and the results are compared with those of the Maxwellian distribution.
Preservation of Digital Objects.
ERIC Educational Resources Information Center
Galloway, Patricia
2004-01-01
Presents a literature review that covers the following topics related to preservation of digital objects: practical examples; stakeholders; recordkeeping standards; genre-specific problems; trusted repository standards; preservation methods; preservation metadata standards; and future directions. (Contains 82 references.) (MES)
The Vlasov-Maxwell-Boltzmann system with a uniform ionic background near Maxwellians
NASA Astrophysics Data System (ADS)
Lei, Yuanjie; Zhao, Huijiang
2016-02-01
The two-species Vlasov-Maxwell-Boltzmann system is an important model for plasma physics describing the time evolution of dilute charged particles consisting of electrons and ions under the influence of the self-consistent internally generated Lorentz forces. In physical situations the ion mass is usually much larger than the electron mass so that the electrons move much faster than the ions. Thus, the ions are often described by a fixed ion background and only the electrons move. For such a simple case, the two-species Vlasov-Maxwell-Boltzmann system is reduced to the one-species Vlasov-Maxwell-Boltzmann system. Although the one-species Vlasov-Maxwell-Boltzmann system is a simplified model of the two-species Vlasov-Maxwell-Boltzmann system, its global well-posedness theory near a given global Maxwellian in the perturbative framework is more difficult than the two-species case, which is partially due to the slow-decay of the electromagnetic field and up to now, the problem on the construction of global in time solutions near a given global Maxwellian in the perturbative framework for the Cauchy problem of the one-species Vlasov-Maxwell-Boltzmann system with cutoff non-hard sphere intermolecular collisions remains unsolved. It is shown in this paper that the Cauchy problem of the one-species Vlasov-Maxwell-Boltzmann system with cutoff non-hard sphere intermolecular collisions including the cutoff inverse power law potentials is globally well-posed provided that the perturbative initial data satisfies certain regularity, smallness, and integrability conditions. Our analysis is based on a new time-velocity weighted energy method with two key technical parts: one is to introduce the exponentially weighted estimates into the cutoff Boltzmann operator and the other is to design a delicate temporal energy X (t)-norm to obtain its uniform bound. As a by-product of our analysis, we can also deduce certain temporal decay estimates on the global solutions constructed above
Technology Transfer Automated Retrieval System (TEKTRAN)
Ferns are a diverse and important group of plants, but diversity of species and populations are at risk from increasing social pressures, loss of habitat and climate change. Ex situ conservation is a useful strategy to limit decline in genetic diversity and requires technologies to preserve fern ger...
E.J. Valeo, C.K. Phillips, H. Okuda, J.C. Wright, P.T. Bonoli, L.A. Berry, and the RF SciDAC Team
2007-07-18
At the power levels required for signicant heating and current drive in magnetically-con ned toroidal plasma, modi cation of the particle distribution function from a Maxwellian shape is likely [T.H. Stix, Nucl. Fusion, 15:737 1975], with consequent changes in wave propagation and in the location and amount of absorption. In order to study these e ects computationally, the nite-Larmor-radius, full-wave, hot-plasma toroidal simulation code, TORIC [M. Brambilla. Plasma Phys. Controlled Fusion, 41:1, 1999], has been extended to allow the prescription of arbitrary velocity distributions of the form ƒ (ν||, ν⊥, Ψ, θ). For H minority heating of a D-H plasma with anisotropic Maxwellian H distributions, the fractional H absorption varies signi cantly with changes in parallel temperature but is essentially independent of perpendicular temperature.
Haque, Q.; Zakir, U.; Qamar, A.
2015-12-15
Linear and nonlinear dynamics of electron temperature gradient mode along with parallel electron dynamics is investigated by considering hydrodynamic electrons and non-Maxwellian ions. It is noticed that the growth rate of η{sub e}-mode driven linear instability decreases by increasing the value of spectral index and increases by reducing the ion/electron temperature ratio along the magnetic field lines. The eigen mode dispersion relation is also found in the ballooning mode limit. Stationary solutions in the form of dipolar vortices are obtained for both circular and elliptic boundary conditions. It is shown that the dynamics of both circular and elliptic vortices changes with the inclusion of inhomogeneity and non-Maxwellian effects.
Evolution of a Maxwellian plasma driven by ion-beam-induced ionization of a gas
Oliver, B.V.; Ottinger, P.F.; Rose, D.V.
1996-09-01
The ionization of gas by intense (MeV, kA/cm{sup 2}) ion beams is investigated for the purpose of obtaining scaling relations for the rate of rise of the electron density, temperature, and conductivity of the resulting plasma. Various gases including He, N, and Ar at pressures of order 1 torr have been studied. The model is local and assumes a drifting Maxwellian electron distribution. In the limit that the beam to gas density ratio is small, the initial stage of ionization occurs on the beam impact ionization time and lasts on the order of a few nanoseconds. Thereafter, ionization of neutrals by the thermal electrons dominates electron production. The electron density does not grow exponentially, but proceeds linearly on a fast time scale {ital t}{sub th}={ital U}/({ital v}{sub {ital b}}{rho}{ital dE}/{ital dx}) associated with the time taken for the beam to lose energy {ital U} via collisional stopping in the gas, where {ital U} is the ionization potential of the gas, {ital v}{sub {ital b}} is the beam velocity, {rho} is the gas mass density, and {ital dE}/{ital dx} is the mass stopping power in units of eVcm{sup 2}/g. This results in a temperature with a slow time dependence and a conductivity with a linear rise time proportional to {ital t}{sub th}. {copyright} {ital 1996 American Institute of Physics.}
Thomson Scattering Observation of Non-Maxwellian EEDF and the Effect of Local Electron Heating
NASA Astrophysics Data System (ADS)
Kono, A.; Funahashi, H.
2001-10-01
Laser Thomson scattering measurements were carried out to study electron energy distribution function (EEDF) of inductively coupled plasmas using C_4F_8/Ar and CF_4/Ar mixture gases. The plasma was produced using a one-turn coil antenna immersed in the plasma at a total pressure of 25 mTorr. A specially designed triple-grating spectrometer was used, which produces Thomson spectra on the output focal plane with the interfering Rayleigh and stray components highly suppressed; an ICCD camera operated in the photon-counting mode was used for multichannel detection of the spectrum. At a RF (13.56 MHz) input power of 300 W in the case of pure Ar plasma, EEDF was Maxwellian with an enectron density >10^12 cm-3. Upon mixing of C_4F8 as well as CF_4, decrease in the electron density and upward bend of the plot of the Thomson spectrum (energy vs. logarithmic scattering intensity) at energies around 5 eV was observed. The mechanism for producing this bend was studied via Monte-Carlo particle simulation. The results indicate that electron heating in a uniform electric field does not lead to upward bend; electrons should be heated locally near the antenna surface where the RF electric field is strong and cooled in other part of the plasma by inelastic collisions.
Non-Maxwellian electron distributions by direct laser acceleration in near-critical plasmas
NASA Astrophysics Data System (ADS)
Toncian, T.; Wang, C.; Arefiev, A.; McCary, E.; Meadows, A.; Blakeney, J.; Chester, C.; Roycroft, R.; Fu, H.; Yan, X. Q.; Schreiber, J.; Pomerantz, I.; Quevedo, H.; Dyer, G.; Gaul, E.; Ditmire, T.; Hegelich, B. M.
2015-11-01
The irradiation of few nm thick targets by a finite-contrast high-intensity short-pulse laser results in a strong pre-expansion of these targets at the arrival time of the main pulse. The targets will decompress to near and lower than critical electron densities plasmas extending over lengths of few micrometers. The laser-matter interaction of the main pulse with such a highly localized but inhomogeneous the target leads to the generation of a channel and further self focussing of the laser beam. As measured in a experiment conducted with the GHOST laser system at UT Austin, 2D PIC simulations predict Direct Laser Acceleration of non-Maxwellian electron distribution in the laser propagation direction for such targets. The hereby high density electron bunches have potential applications as injector beams for a further wakefield acceleration stage. This work was supported by NNSA cooperative agreement DE-NA0002008, the DARPA's PULSE program (12-63-PULSE-FP014) and the AFOSR (FA9550-14-1-0045).
Observations of odd-half cyclotron harmonic emissions in a shell-Maxwellian laboratory plasma
NASA Technical Reports Server (NTRS)
Urrutia, J. M.; Stenzel, R. L.
1983-01-01
During the last 14 years, the subject of odd-half electron cyclotron harmonic emission from plasma has been given considerable attention. It was apparently first reported to occur in a beam plasma machine. The existence of the emission in space has been well documented through observations made with satellites. Because wavelengths are difficult to observe in space, no wave number spectrum has ever been obtained for the half-odd harmonic emission. Such a spectrum together with a frequency spectrum might provide the basis for a successful modeling of the instability. The present investigation is concerned with the design of a laboratory experiment in which a plasma with an anisotropic velocity distribution is produced and measured. In addition, the dispersion relation is directly measured, and a noise analysis is conducted. The obtained plasma, a mixture of shell and Maxwellian distributions, is found to emit waves within the Bernstein wave branches. By correlation measurements, a mode is found which is essentially an absolute instability in a narrow frequency band.
Dust-ion-acoustic Gardner solitons in a dusty plasma with bi-Maxwellian electrons
Masud, M. M.; Asaduzzaman, M.; Mamun, A. A.
2012-10-15
The nonlinear propagation of dust-ion-acoustic (DIA) waves in a dusty plasma with bi-Maxwellian electrons, namely, lower and higher temperature electrons (composed of negatively charged stationary dust, inertial ions, and non-inertial two-temperature-electrons) is investigated by deriving the Gardner equation using the reductive perturbation technique. The basic features (amplitude, width, etc.) of the hump (positive potential) and dip (negative potential) shaped DIA solitons (Gardner solitons, i.e., GSs) are found to exist beyond the Korteweg-de Vries (K-dV) limit. These DIA-GSs are qualitatively different from the K-dV and modified K-dV solitons. It is also shown that depending on the parameter {sigma} (where {sigma}=T{sub e1}/T{sub e2}, T{sub e1} and T{sub e2} being the temperatures of two distinct electrons and T{sub e1} Much-Less-Than T{sub e2}), the DIA-GSs exhibit hump and dip shape solitary structures. The implications of our results in understanding the localized nonlinear electrostatic perturbations observed in double-plasma machines, rf discharge plasma, noctilucent cloud region in Earths atmosphere, etc., where population of two thermal electrons can significantly dominate the wave dynamics, are also briefly addressed.
Full wave simulation of lower hybrid waves in Maxwellian plasma based on the finite element method
Meneghini, O.; Shiraiwa, S.; Parker, R.
2009-09-15
A full wave simulation of the lower-hybrid (LH) wave based on the finite element method is presented. For the LH wave, the most important terms of the dielectric tensor are the cold plasma contribution and the electron Landau damping (ELD) term, which depends only on the component of the wave vector parallel to the background magnetic field. The nonlocal hot plasma ELD effect was expressed as a convolution integral along the magnetic field lines and the resultant integro-differential Helmholtz equation was solved iteratively. The LH wave propagation in a Maxwellian tokamak plasma based on the Alcator C experiment was simulated for electron temperatures in the range of 2.5-10 keV. Comparison with ray tracing simulations showed good agreement when the single pass damping is strong. The advantages of the new approach include a significant reduction of computational requirements compared to full wave spectral methods and seamless treatment of the core, the scrape off layer and the launcher regions.
The influence of thermal radiation on MHD flow of Maxwellian fluids above stretching sheets
NASA Astrophysics Data System (ADS)
Aliakbar, V.; Alizadeh-Pahlavan, A.; Sadeghy, K.
2009-03-01
Flow induced in a viscoelastic fluid by a linearly stretched sheet is investigated assuming that the fluid is Maxwellian and the sheet is subjected to a transverse magnetic field. The objective is to investigate the effects of parameters such as elasticity number, magnetic number, radiative heat transfer, Prandtl number, and Eckert number on the temperature field above the sheet. To do this, boundary layer theory will be used to simplify energy and momentum equations assuming that fluid physical/rheological properties remain constant. A suitable similarity transformation will be used to transform boundary layer equations from PDEs into ODEs. Homotopy analysis method (HAM) will be invoked to find an analytical solution for the temperature field above the sheet knowing the velocity profiles (see Alizadeh-Pahlavan et al. [Alizadeh-Pahlavan A, Aliakbar V, Vakili-Farahani F, Sadeghy K. MHD flows of UCM fluids above porous stretching sheets using two-auxiliary parameter homotopy analysis method. Commun. Nonlinear Sci Numer Simulat, in press]). The importance of manipulating the transverse velocity component, v, will be discussed on the temperature field above the sheet.
On the high Mach number shock structure singularity caused by overreach of Maxwellian molecules
Myong, R. S.
2014-05-15
The high Mach number shock structure singularity arising in moment equations of the Boltzmann equation was investigated. The source of the singularity is shown to be the unbalanced treatment between two high order kinematic and dissipation terms caused by the overreach of Maxwellian molecule assumption. In compressive gaseous flow, the high order stress-strain coupling term of quadratic nature will grow far faster than the strain term, resulting in an imbalance with the linear dissipation term and eventually a blow-up singularity in high thermal nonequilibrium. On the other hand, the singularity arising from unbalanced treatment does not occur in the case of velocity shear and expansion flows, since the high order effects are cancelled under the constraint of the free-molecular asymptotic behavior. As an alternative method to achieve the balanced treatment, Eu's generalized hydrodynamics, consistent with the second law of thermodynamics, was revisited. After introducing the canonical distribution function in exponential form and applying the cumulant expansion to the explicit calculation of the dissipation term, a natural platform suitable for the balanced treatment was derived. The resulting constitutive equation with the nonlinear factor was then shown to be well-posed for all regimes, effectively removing the high Mach number shock structure singularity.
Evolution of ion-acoustic solitary waves in Maxwellian dusty plasmas
Das, G. C.; Choudhury, Balen; Bora, M. P.
2010-12-15
The nonlinear wave phenomena in the vicinity of Korteweg-de Vries (KdV) equation have been derived to study the salient features of solitons in a complex plasma consisting of Maxwellian electrons, ions, and cold dust with the effect of dust charge fluctuation. The reductive perturbation method has been applied to the dynamical system causeway and the derived KdV equation predicts different natures of solitons in complex plasma. The dynamics of the soliton propagation in the considered plasma constituents in ionospheric auroral regions exhibits rarefactive solitons, which is an interesting feature. The dust charge fluctuation by the increasing impact of electrons leads the nonlinear effect to be tending to zero. Because of which, the formation of a narrow solitary wave packet with the generation of high energy becomes possible and results in the phenomena of soliton radiation. In order to probe this further, we derive a modified KdV equation to study soliton propagation which, in turn, indicates the possibility of the shock formation in solitary waves.
Alfvenic modes in a bi-Maxwellian electron-ion plasma
Bashir, M. F.; Iqbal, Z.; Aslam, I.; Murtaza, G.
2010-10-15
Employing linearized Vlasov-Maxwell system, we derive a generalized dielectric tensor for a magnetized nonrelativistic bi-Maxwellian electron-ion plasma. Assuming low frequency waves in a low {beta} plasma, a new dispersion relation describing oblique propagation of the Alfvenic modes is determined, incorporating the temperature anisotropies of both the electrons and ions and their finite Larmor radii effects. From the resulting dispersion relation for kinetic Alfven waves, analytical expressions are determined for both the kinetic (v{sub t||}){sub i}<<{omega}/k{sub ||}<
Electron heat conduction under non-Maxwellian distribution in hohlraum simulation
Wen Yihuo; Ke Lan; Pei Jungu; Heng Yong; Qing Hongzeng
2012-01-15
An electron transport model based on the non-Maxwellian distribution f{sub 0}{proportional_to}e{sup -{nu}{sup m}} (NM model), caused by the inverse bremsstrahlung heating, is used in 1-D plane target and 2-D hohlraum simulations. In the NM model, the electron heat flux depends not only on the gradient of electron temperature T{sub e} but also on the gradients of electron number density and the index m. From 1-D simulations, the spatial distribution of T{sub e} is dune-like and T{sub e} decreases obviously in the flux-heated region, which is very different from the flat profile obtained by using the flux limit model (FL model) but similar to the experimental observations [Gregori et al., Phys. Rev. Lett. 92, 205006 (2004)] and the nonlocal results [Rosen et al., High Energy Density Phys. 7, 180 (2011)]. The reason which causes the dune-like profile of T{sub e} is discussed in the paper. From 2-D hohlraum simulations, the NM results of the plasma status, the emission peak and profile inside hohlraum are very different from the FL model results. Finally, it is hard to use an average flux limiter in the FL model to obtain the same hohlraum plasma status and emission with those under the NM model.
NASA Technical Reports Server (NTRS)
Burkhart, G. R.; Chen, J.
1989-01-01
The integrodifferential equation describing the linear tearing instability in the bi-Maxwellian neutral sheet is solved without approximating the particle orbits or the eigenfunction psi. Results of this calculation are presented. Comparison between the exact solution and the three-region approximation motivates the piecewise-straight-line approximation, a simplification that allows faster solution of the integrodifferential equation, yet retains the important features of the exact solution.
NASA Astrophysics Data System (ADS)
Choudhury, S.; Duerr, R. E.
2009-12-01
NSF's Sustainable Digital Data Preservation and Access Network Partners program is an ambitious attempt to integrate a wide variety of expertise and infrastructure into a network for providing "reliable digital preservation, access, integration, and analysis capabilities for science." One of the first two DataNet award recipients, the Data Conservancy, is itself a network of widely diverse partners led by the libraries at the Johns Hopkins University. The Data Conservancy is built on existing exemplar scientific projects, communities, and virtual organizations that have deep engagement with their user communities, and extensive experience with large-scale distributed system development. Data Conservancy members embrace a shared vision that data curation is not an end, but rather a means to collect, organize, validate, and preserve data needed to address the grand research challenges that face society. Data Conservancy members holdings encompass the entire range of earth, life, and space science data. New to the Data Conservancy is the concept that University libraries will be part of the distributed network of data centers and that data science will become a path in the library and information science curricula. As noted by Winston Tabb (JHU Dean of Libraries) "Data Centers are the new library stacks."
Shielding effect and wakefield pattern of a moving test charge in a non-Maxwellian dusty plasma
Ali, S.; Khan, S.
2013-07-15
By using the Vlasov-Poisson equations, we calculate an expression for the electrostatic potential caused by a test charge in an unmagnetized non-Maxwellian dusty plasma, whose constituents are the superthermal hot-electrons, the mobile cold-electrons with a neutralizing background of cold ions, and charge fluctuating isolated dust grains. The superthermality effects due to hot electrons not only modify the dielectric constant of the electron-acoustic waves but also significantly affect the electrostatic potential. The latter can be decomposed into the Debye-Hückel and oscillatory wake potentials. Analytical and numerical results reveal that the Debye-Hückel and wakefield potentials converge to the Maxwellian case for large values of superthermality parameter. Furthermore, the plasma parameters play a vital role in the formation of shielding and wakefield pattern in a two-electron temperature plasma. The present results should be important for laboratory and space dusty plasmas, where hot-electrons can be assumed to follow the non-Maxwellian distribution function.
NASA Technical Reports Server (NTRS)
Demars, H. G.; Schunk, R. W.
1990-01-01
The purpose of this paper is to study the possible types of velocity distributions that can be obtained from the bi-Maxwellian based 16-moment expansion of the distribution function, assuming macroscopic parameter values characteristic of the range of solar wind conditions. While previous studies also took heat flow into account, the theoretical expansions for f and the definitions of the physical moments adopted in these studies were different from those used in this paper. The choice of the 16-moment expansion and corresponding moment definitions was motivated by the fact that this is the correct generalization of the widely-used Maxwellian-based 13-moment expansion to the case where the zeroth-order distribution is a bi-Maxwellian. It is found that most of the features characteristic of solar wind proton distributions can be reproduced with the 16-moment distribution, including the appearance of secondary peaks. It is also shown how each of the physically significant velocity moments affects the shape of the distribution function.
Basu, B.; Grossbard, N. J.
2011-09-15
Current-driven electrostatic ion-cyclotron instability has so far been studied for Maxwellian plasma with isotropic and anisotropic temperatures. Since satellite-measured particle velocity distributions in space are often better modeled by the generalized Lorentzian (kappa) distributions and since temperature anisotropy is quite common in space plasmas, theoretical analysis of the current-driven, electrostatic ion-cyclotron instability is carried out in this paper for electron-proton plasma with anisotropic temperatures, where the particle parallel velocity distributions are modeled by kappa distributions and the perpendicular velocity distributions are modeled by Maxwellian distributions. Stability properties of the excited ion cyclotron modes and, in particular, their dependence on electron to ion temperature ratio and ion temperature anisotropy are presented in more detail. For comparison, the corresponding results for bi-Maxwellian plasma are also presented. Although the stability properties of the ion cyclotron modes in the two types of plasmas are qualitatively similar, significant quantitative differences can arise depending on the values of {kappa}{sub e} and {kappa}{sub i}. The comparative study is based on the numerical solutions of the respective linear dispersion relations. Quasilinear estimates of the resonant ion heating rates due to ion-cyclotron turbulence in the two types of plasma are also presented for comparison.
Conservative mastectomies: an overview
Nava, Maurizio Bruno; Catanuto, Giuseppe
2015-01-01
Conservative mastectomies provide removal of the entire breast parenchyma, saving the outer covering of the mammary gland with the possibility of performing an immediate reconstruction preserving women body image. We rationalised and systematically organized our reconstructive algorythms giving a new different light to mastectomies, the so-called “conservative mastectomies”, an oxymoron indicating skin-sparing mastectomies (SSM), nipple-areola complex-sparing mastectomies (NSM) and skin-reducing mastectomies (SRM). Eventhough randomized controlled trials comparing conservative mastectomies with traditional mastectomy and breast conserving surgery would be auspicable in order to achieve higher levels of evidence, we could confidently conclude that conservative mastectomies offer the psychological advantages of good cosmesis and maintenance of woman body image without compromising the oncological safety of mastectomy. PMID:26645000
Fertility preservation in female cancer patients.
Kim, Chung-Hoon; Jeon, Gyun-Ho
2012-01-01
With improved survival rates among cancer patients, fertility preservation is now being recognized as an issue of great importance. There are currently several methods of fertility preservation available in female cancer patients and the options and techniques via assisted reproduction and cryopreservation are increasing, but some are still experimental and continues to be evaluated. The established means of preserving fertility include embryo cryopreservation, gonadal shielding during radiation therapy, ovarian transposition, conservative gynecologic surgery such as radical trachelectomy, donor embryos/oocytes, gestational surrogacy, and adoption. The experimental methods include oocyte cryopreservation, ovarian cryopreservation and transplantation, in vitro maturation, and ovarian suppression. With advances in methods for the preservation of fertility, providing information about risk of infertility and possible options of fertility preservation to all young patients with cancer, and discussing future fertility with them should be also considered as one of the important parts of consultation at the time of cancer diagnosis. PMID:22462006
ERIC Educational Resources Information Center
Sheridan, Philip
1978-01-01
A quick, simple method for preserving bird specimens using borax and a formalin solution is described. Procedures for injecting and mounting the specimens are given along with certain restrictions on preserving specimens. (MA)
Current Trends in Preservation Research and Development.
ERIC Educational Resources Information Center
Cunha, George Martin
1990-01-01
Overview of current trends in the preservation of library materials discusses collections conservation and management; climate control; insect and mold control; fire control; the effects of compact shelving; freezing and freeze-drying; space drying; alkaline paper; recycled paper; mass deacidification; and paper strengthening. (27 notes and…
PRESERVATION OF MEDICINAL AND AROMATIC CROPS
Technology Transfer Automated Retrieval System (TEKTRAN)
The NPGS is a cooperative effort by public (State and Federal) and private organizations to preserve the genetic diversity of plants by long-term storage of germplasm, primarily in the form of seeds. The mission of the NPGS includes: 1.) the conservation of diverse crop germplasm through collectio...
12 CFR 627.2730 - Preservation of equity.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 12 Banks and Banking 6 2010-01-01 2010-01-01 false Preservation of equity. 627.2730 Section 627.2730 Banks and Banking FARM CREDIT ADMINISTRATION FARM CREDIT SYSTEM TITLE IV CONSERVATORS, RECEIVERS, AND VOLUNTARY LIQUIDATIONS Receivers and Receiverships § 627.2730 Preservation of equity. (a)...
NASA Astrophysics Data System (ADS)
de Avillez, Miguel A.; Breitschwerdt, Dieter
2015-08-01
Aims: Optically thin plasmas may deviate from thermal equilibrium and thus, electrons (and ions) are no longer described by the Maxwellian distribution. Instead they can be described by κ-distributions. The free-free spectrum and radiative losses depend on the temperature-averaged (over the electrons distribution) and total Gaunt factors, respectively. Thus, there is a need to calculate and make available these factors to be used by any software that deals with plasma emission. Methods: We recalculated the free-free Gaunt factor for a wide range of energies and frequencies using hypergeometric functions of complex arguments and the Clenshaw recurrence formula technique combined with approximations whenever the difference between the initial and final electron energies is smaller than 10-10 in units of z2Ry. We used double and quadruple precisions. The temperature-averaged and total Gaunt factors calculations make use of the Gauss-Laguerre integration with 128 nodes. Results: The temperature-averaged and total Gaunt factors depend on the κ parameter, which shows increasing deviations (with respect to the results obtained with the use of the Maxwellian distribution) with decreasing κ. Tables of these Gaunt factors are provided. Appendices are available in electronic form at http://www.aanda.org
Fertility preservation in female classic galactosemia patients.
van Erven, Britt; Gubbels, Cynthia S; van Golde, Ron J; Dunselman, Gerard A; Derhaag, Josien G; de Wert, Guido; Geraedts, Joep P; Bosch, Annet M; Treacy, Eileen P; Welt, Corrine K; Berry, Gerard T; Rubio-Gozalbo, M Estela
2013-01-01
Almost every female classic galactosemia patient develops primary ovarian insufficiency (POI) as a diet-independent complication of the disease. This is a major concern for patients and their parents, and physicians are often asked about possible options to preserve fertility. Unfortunately, there are no recommendations on fertility preservation in this group. The unique pathophysiology of classic galactosemia with a severely reduced follicle pool at an early age requires an adjusted approach. In this article recommendations for physicians based on current knowledge concerning galactosemia and fertility preservation are made. Fertility preservation is only likely to be successful in very young prepubertal patients. In this group, cryopreservation of ovarian tissue is currently the only available technique. However, this technique is not ready for clinical application, it is considered experimental and reduces the ovarian reserve. Fertility preservation at an early age also raises ethical questions that should be taken into account. In addition, spontaneous conception despite POI is well described in classic galactosemia. The uncertainty surrounding fertility preservation and the significant chance of spontaneous pregnancy warrant counseling towards conservative application of these techniques. We propose that fertility preservation should only be offered with appropriate institutional research ethics approval to classic galactosemia girls at a young prepubertal age. PMID:23866841
Fertility preservation in female classic galactosemia patients
2013-01-01
Almost every female classic galactosemia patient develops primary ovarian insufficiency (POI) as a diet-independent complication of the disease. This is a major concern for patients and their parents, and physicians are often asked about possible options to preserve fertility. Unfortunately, there are no recommendations on fertility preservation in this group. The unique pathophysiology of classic galactosemia with a severely reduced follicle pool at an early age requires an adjusted approach. In this article recommendations for physicians based on current knowledge concerning galactosemia and fertility preservation are made. Fertility preservation is only likely to be successful in very young prepubertal patients. In this group, cryopreservation of ovarian tissue is currently the only available technique. However, this technique is not ready for clinical application, it is considered experimental and reduces the ovarian reserve. Fertility preservation at an early age also raises ethical questions that should be taken into account. In addition, spontaneous conception despite POI is well described in classic galactosemia. The uncertainty surrounding fertility preservation and the significant chance of spontaneous pregnancy warrant counseling towards conservative application of these techniques. We propose that fertility preservation should only be offered with appropriate institutional research ethics approval to classic galactosemia girls at a young prepubertal age. PMID:23866841
[Preservatives in ophthalmology].
Messmer, E M
2012-11-01
Preservatives are a legal requirement for eye drops in multidose containers. Moreover, they are necessary for stabilization and intraocular penetration for a number of ophthalmic preparations. Most preservatives act in a relatively unspecific manner as detergents or by oxidative mechanisms and thereby cause side effects at the ocular surface. They may also affect the lens, trabecular meshwork and the retina. Benzalkonium chloride is the most commonly used preservative in ophthalmology and is more toxic than other or newer preservatives, such as polyquaternium-1 (Polyquad), sodium perborate, oxychloro-complex (Purite®) and SofZia. Preservative-free topical medication is highly recommended for patients with ocular surface disease, frequent eye drop administration, proven allergy to preservatives and contact lens wear. PMID:23179809
Moment preserving adaptive particle weights using octree velocity distributions for PIC simulations
Martin, Robert Scott; Cambier, Jean-Luc
2012-11-27
The ratio of computational to physical particles is of primary concern to statistical particle based simulations such as DSMC and PIC. An adaptive computational particle weight algorithm is presented that conserves mass, momentum, and energy. This algorithm is then enhanced with an octree adaptive mesh in velocity space to mitigate artificial thermalization. The new octree merge is compared to a merge that randomly selects merge partners for a bi-Maxwellian velocity distribution. Results for crossing beams in a fixed potential well along with an electrostatic PIC version with and without MCC collisions based ionizing breakdown show the advantages of the merge algorithm to both fixed particle weights and randomly selected merge partners.
Conservation of helicity in superfluids
NASA Astrophysics Data System (ADS)
Kedia, Hridesh; Kleckner, Dustin; Proment, Davide; Irvine, William T. M.
2015-03-01
Helicity arises as a special conserved quantity in ideal fluids, in addition to energy, momentum and angular momentum. As a measure of the knottedness of vortex lines, Helicity provides an important tool for studying a wide variety of physical systems such as plasmas and turbulent fluids. Superfluids flow without resistance just like ideal (Euler) fluids, making it natural to ask whether their knottedness is similarly preserved. We address the conservation of helicity in superfluids theoretically and examine its consequences in numerical simulations.
Schopf, J.M.
1975-01-01
The processes of geologic preservation are important for understanding the organisms represented by fossils. Some fossil differences are due to basic differences in organization of animals and plants, but the interpretation of fossils has also tended to be influenced by modes of preservation. Four modes of preservation generally can be distinguished: (1) Cellular permineralization ("petrifaction") preserves anatomical detail, and, occasionally, even cytologic structures. (2) Coalified compression, best illustrated by structures from coal but characteristic of many plant fossils in shale, preserves anatomical details in distorted form and produces surface replicas (impressions) on enclosing matrix. (3) Authigenic preservation replicates surface form or outline (molds and casts) prior to distortion by compression and, depending on cementation and timing, may intergrade with fossils that have been subject to compression. (4) Duripartic (hard part) preservation is characteristic of fossil skeletal remains, predominantly animal. Molds, pseudomorphs, or casts may form as bulk replacements following dissolution of the original fossil material, usually by leaching. Classification of the kinds of preservation in fossils will aid in identifying the processes responsible for modifying the fossil remains of both animals and plants. ?? 1975.
Layden, B.; Cairns, Iver H.; Robinson, P. A.
2013-08-15
Electrostatic decay of Langmuir waves into Langmuir and ion sound waves (L→L′+S) and scattering of Langmuir waves off thermal ions (L+i→L′+i′, also called “nonlinear Landau damping”) are important nonlinear weak-turbulence processes. The rates for these processes depend on the quadratic longitudinal response function α{sup (2)} (or, equivalently, the quadratic longitudinal susceptibility χ{sup (2)}), which describes the second-order response of a plasma to electrostatic wave fields. Previous calculations of these rates for an unmagnetized Maxwellian plasma have relied upon an approximate form for α{sup (2)} that is valid where two of the wave fields are fast (i.e., v{sub φ}=ω/k≫V{sub e} where ω is the angular frequency, k is the wavenumber, and V{sub e} is the electron thermal speed) and one is slow (v{sub φ}≪V{sub e}). Recently, an exact expression was derived for α{sup (2)} that is valid for any phase speeds of the three waves in an unmagnetized Maxwellian plasma. Here, this exact α{sup (2)} is applied to the calculation of the three-dimensional rates for electrostatic decay and scattering off thermal ions, and the resulting exact rates are compared with the approximate rates. The calculations are performed using previously derived three-dimensional rates for electrostatic decay given in terms of a general α{sup (2)}, and newly derived three-dimensional rates for scattering off thermal ions; the scattering rate is derived assuming a Maxwellian ion distribution, and both rates are derived assuming arc distributions for the wave spectra. For most space plasma conditions, the approximate rate is found to be accurate to better than 20%; however, for sufficiently low Langmuir phase speeds (v{sub φ}/V{sub e}≈3) appropriate to some spatial domains of the foreshock regions of planetary bow shocks and type II solar radio bursts, the use of the exact rate may be necessary for accurate calculations. The relative rates of electrostatic decay
NASA Astrophysics Data System (ADS)
Kourakis, I.; Williams, G.; Sultana, S.; Hellberg, M.
2014-12-01
Space plasmas are often characterized by the presence of energetic particles in the background, e.g. due to various electron acceleration mechanisms [1]. This phenomenon is associated with a power-law dependence at high (superthermal) velocity values, modeled by a kappa-type distribution function, which reproduces observed data more efficiently that the standard Maxwellian distribution approach [2]. It has been shown from first principles that this ubiquitous superthermal feature of plasmas may alter the propagation characteristics of plasma modes, and modify the plasma screening properties [3]. In this presentation I will review, from first principles, the effects of a non-Maxwellian electron distribution on the characteristics of electrostatic plasma modes. A kappa distribution function [1] is employed to model the deviation of a plasma constituent (electrons, in general) from Maxwellian equlibrium. It will be shown that the excess in superthermal propulation modifies the charge screening mechanism, affecting the dispersion laws of both low- and higher frequency modes significantly. Various experimental observations may thus be interpreted as manifestations of excess superthermality [2]. Focusing on the features of nonlinear excitations (shocks, solitons), we investigate the role of superthermality in their propagation dynamics (existence laws, stability profile) and dynamical profile [3]. The relation to other nonthermal plasma theories is briefly discussed. [1] See V.M. Vasyliunas, J. Geophys. Res. 73, 2839 (1968), for a historical reference; also, V. Pierrard and M. Lazar, Solar Phys. 267, 153 (2010), for a more recent review.[2] M. Hellberg et al, J. Plasma Physics 64, 433 (2000); G. Sarri et al, Physics of Plasmas, 17, 010701/1-4 (2010).[3] S. Sultana, I. Kourakis, N.S. Saini, M.A. Hellberg, Phys. Plasmas 17, 032310 (2010);S. Sultana and I. Kourakis, Plasma Phys. Cont. Fus. 53, 045003 (2011);S. Sultana, G. Sarri and I. Kourakis, Phys. Plasmas 19, 012310
Jamjoom, Amal; Cohen, Robert E.
2015-01-01
Alveolar ridge bone resorption is a biologic phenomenon that occurs following tooth extraction and cannot be prevented. This paper reviews the vertical and horizontal ridge dimensional changes that are associated with tooth extraction. It also provides an overview of the advantages of ridge preservation as well as grafting materials. A Medline search among English language papers was performed in March 2015 using alveolar ridge preservation, ridge augmentation, and various graft types as search terms. Additional papers were considered following the preliminary review of the initial search that were relevant to alveolar ridge preservation. The literature suggests that ridge preservation methods and augmentation techniques are available to minimize and restore available bone. Numerous grafting materials, such as autografts, allografts, xenografts, and alloplasts, currently are used for ridge preservation. Other materials, such as growth factors, also can be used to enhance biologic outcome. PMID:26262646
Varvaresou, A; Papageorgiou, S; Tsirivas, E; Protopapa, E; Kintziou, H; Kefala, V; Demetzos, C
2009-06-01
Preservatives are added to products for two reasons: first, to prevent microbial spoilage and therefore to prolong the shelf life of the product; second, to protect the consumer from a potential infection. Although chemical preservatives prevent microbial growth, their safety is questioned by a growing segment of consumers. Therefore, there is a considerable interest in the development of preservative-free or self-preserving cosmetics. In these formulations traditional/chemical preservatives have been replaced by other cosmetic ingredients with antimicrobial properties that are not legislated as preservatives according to the Annex VI of the Commission Directive 76/768/EEC and the amending directives (2003/15/EC, 2007/17/EC and 2007/22/EC). 'Hurdle Technology', a technology that has been used for the control of product safety in the food industry since 1970s, has also been applied for the production of self-preserving cosmetics. 'Hurdle Technology' is a term used to describe the intelligent combination of different preservation factors or hurdles to deteriorate the growth of microorganisms. Adherence to current good manufacturing practice, appropriate packaging, careful choice of the form of the emulsion, low water activity and low or high pH values are significant variables for the control of microbial growth in cosmetic formulations. This paper describes the application of the basic principles of 'Hurdle Technology' in the production of self-preserving cosmetics. Multifunctional antimicrobial ingredients and plant-derived essential oils and extracts that are used as alternative or natural preservatives and are not listed in Annex VI of the Cosmetic Directive are also reported. PMID:19302511
NASA Astrophysics Data System (ADS)
Mackovjak, Š.; Dzifčáková, E.; Dudík, J.
2014-04-01
Context. The non-Maxwellian κ-distributions have been detected in the solar wind and can explain intensities of some transition region lines. Presence of such distributions in the outer layers of the solar atmosphere influences the ionization and excitation equilibrium and widens the line contribution functions. This behavior may be reflected on the reconstructed differential emission measure (DEM). Aims: We aim to investigate the influence of κ-distributions on the reconstructed DEMs. Methods: We perform DEM reconstruction for three active region cores and a quiet Sun region using the Withbroe-Sylwester method and the regularization method. Results: We find that the reconstructed DEMs depend on the value of κ. The DEMs of the active region cores show similar behavior with decreasing κ, or an increasing departure from the Maxwellian distribution. For lower κ, the peaks of the DEMs are typically shifted to higher temperatures and the DEMs themselves become more concave. This is caused by the less steep high-temperature slopes for lower κ. However, the low-temperature slopes do not change significantly even for extremely low κ. The behavior of the quiet-Sun DEM distribution is different. It becomes progressively less multithermal for lower κ with the EM-loci plots that indicate near-isothermal plasma for κ = 2. Conclusions: The κ-distributions can influence the reconstructed DEMs. The slopes of the DEM, however, do not change with κ significantly enough to produce different constraints on the heating mechanism in terms of frequency of coronal heating events.
NASA Astrophysics Data System (ADS)
Viñas, Adolfo F.; Moya, Pablo S.; Navarro, Roberto E.; Valdivia, J. Alejandro; Araneda, Jaime A.; Muñoz, Víctor
2015-05-01
Observed electron velocity distributions in the Earth's magnetosphere and the solar wind exhibit a variety of nonthermal features which deviate from thermal equilibrium, for example, in the form of temperature anisotropies, suprathermal tail extensions, and field-aligned beams. The state close to thermal equilibrium and its departure from it provides a source for spontaneous emissions of electromagnetic fluctuations, such as the whistler. Here we present a comparative analysis of the electron whistler-cyclotron and firehose fluctuations based upon anisotropic plasma modeled with Maxwellian and Tsallis-kappa-like particle distributions, to explain the correspondence relationship of the magnetic fluctuations as a function of the electron temperature and thermal anisotropy in the solar wind and magnetosphere plasmas. The analysis presented here considers correlation theory of the fluctuation-dissipation theorem and the dispersion relation of transverse fluctuations, with wave vectors parallel to the uniform background magnetic field, in a finite temperature anisotropic thermal bi-Maxwellian and nonthermal Tsallis-kappa-like magnetized electron-proton plasma. Dispersion analysis and stability thresholds are derived for these thermal and nonthermal distributions using plasma and field parameters relevant to the solar wind and magnetosphere environments. Our results indicate that there is an enhancement of the fluctuations level in the case of nonthermal distributions due to the effective higher temperature and the excess of suprathermal particles. These results suggest that a comparison of the electromagnetic fluctuations due to thermal and nonthermal distributions provides a diagnostic signature by which inferences about the nature of the particle velocity distribution function can be ascertained without in situ particle measurements.
Organ reperfusion and preservation.
Jamieson, Russell W; Friend, Peter J
2008-01-01
Organ transplantation is one of the medical success stories of the 20th century. Transplantation is, however, a victim of its own success with demand for organs far exceeding supply. The ischemia/reperfusion injury associated with organ transplantation is complex with interlinking cellular pathways and cascades. With increasing use of marginal organs and better understanding of the consequences of ischemia/reperfusion, enhanced organ preservation is required. Traditional static cold preservation cannot prevent ischemia/reperfusion injury, the low temperature itself is damaging and viability testing is limited. Donor preconditioning techniques to enhance organ preservation in advance of retrieval are starting to show convergence on several key pathways (HO-1 and cell apoptosis). Microdialysis and bioimpedence techniques may allow viability assessment during cold storage. Hypothermic machine perfusion has a role to play, particularly in preservation of kidneys from non-heart-beating donors although results of clinical trials are awaited. Normothermic preservation offers benefits over cold storage (at least experimentally) by avoiding damage induced by low temperature, minimising ischemia/reperfusion injury and allowing resuscitation of damaged organs. Normothermic preservation is likely to increase as the average quality of donor organs declines and clinical trials are needed. In the long term, normothermic preservation may be used, not just to resuscitate organs, but facilitate organ immunomodulation. PMID:17981540
18 CFR 1312.12 - Relationship to section 106 of the National Historic Preservation Act.
Code of Federal Regulations, 2012 CFR
2012-04-01
... 18 Conservation of Power and Water Resources 2 2012-04-01 2012-04-01 false Relationship to section 106 of the National Historic Preservation Act. 1312.12 Section 1312.12 Conservation of Power and Water... Relationship to section 106 of the National Historic Preservation Act. Issuance of a permit in accordance...
18 CFR 1312.12 - Relationship to section 106 of the National Historic Preservation Act.
Code of Federal Regulations, 2013 CFR
2013-04-01
... 18 Conservation of Power and Water Resources 2 2013-04-01 2012-04-01 true Relationship to section 106 of the National Historic Preservation Act. 1312.12 Section 1312.12 Conservation of Power and Water... Relationship to section 106 of the National Historic Preservation Act. Issuance of a permit in accordance...
18 CFR 1312.12 - Relationship to section 106 of the National Historic Preservation Act.
Code of Federal Regulations, 2010 CFR
2010-04-01
... 18 Conservation of Power and Water Resources 2 2010-04-01 2010-04-01 false Relationship to section 106 of the National Historic Preservation Act. 1312.12 Section 1312.12 Conservation of Power and Water... Relationship to section 106 of the National Historic Preservation Act. Issuance of a permit in accordance...
18 CFR 1312.12 - Relationship to section 106 of the National Historic Preservation Act.
Code of Federal Regulations, 2014 CFR
2014-04-01
... 18 Conservation of Power and Water Resources 2 2014-04-01 2014-04-01 false Relationship to section 106 of the National Historic Preservation Act. 1312.12 Section 1312.12 Conservation of Power and Water... Relationship to section 106 of the National Historic Preservation Act. Issuance of a permit in accordance...
18 CFR 1312.12 - Relationship to section 106 of the National Historic Preservation Act.
Code of Federal Regulations, 2011 CFR
2011-04-01
... 18 Conservation of Power and Water Resources 2 2011-04-01 2011-04-01 false Relationship to section 106 of the National Historic Preservation Act. 1312.12 Section 1312.12 Conservation of Power and Water... Relationship to section 106 of the National Historic Preservation Act. Issuance of a permit in accordance...
Cryopreservation for preservation of potato genetic resources
Niino, Takao; Arizaga, Miriam Valle
2015-01-01
Cryopreservation is becoming a very important tool for the long-term storage of plant genetic resources and efficient cryopreservation protocols have been developed for a large number of plant species. Practical procedures, developed using in vitro tissue culture, can be a simple and reliable preservation option of potato genetic resources rather than maintaining by vegetative propagation in genebanks due their allogamous nature. Cryopreserved materials insure a long-term backup of field collections against loss of plant germplasm. Occurrence of genetic variation, in tissue culture cells during prolonged subcultures, can be avoided with suitable cryopreservation protocols that provide high regrowth, leading and facilitating a systematic and strategic cryo-banking of plant genetic resources. Cryopreservation protocols for potato reviewed here, can efficiently complement field and in vitro conservation, providing for preservation of genotypes difficult to preserve by other methods, wild types and other species decided as priority collections. PMID:25931979
Cryopreservation for preservation of potato genetic resources.
Niino, Takao; Arizaga, Miriam Valle
2015-03-01
Cryopreservation is becoming a very important tool for the long-term storage of plant genetic resources and efficient cryopreservation protocols have been developed for a large number of plant species. Practical procedures, developed using in vitro tissue culture, can be a simple and reliable preservation option of potato genetic resources rather than maintaining by vegetative propagation in genebanks due their allogamous nature. Cryopreserved materials insure a long-term backup of field collections against loss of plant germplasm. Occurrence of genetic variation, in tissue culture cells during prolonged subcultures, can be avoided with suitable cryopreservation protocols that provide high regrowth, leading and facilitating a systematic and strategic cryo-banking of plant genetic resources. Cryopreservation protocols for potato reviewed here, can efficiently complement field and in vitro conservation, providing for preservation of genotypes difficult to preserve by other methods, wild types and other species decided as priority collections. PMID:25931979
ERIC Educational Resources Information Center
Benjamin, Thomas B.; Gannon, David J.
1980-01-01
Described are the creation, development, activities, and programs of Tifft Farm, a 264-acre nature preserve and environmental education center in Buffalo, New York, constructed on a sanitary landfill. (BT)
Mechanism of entanglement preservation
Tong Qingjun; An Junhong; Luo Honggang; Oh, C. H.
2010-05-15
We study the entanglement preservation of two qubits locally interacting with their reservoirs. We show that the existence of a bound state of the qubit and its reservoir and the non-Markovian effect are two essential ingredients and their interplay plays a crucial role in preserving the entanglement in the steady state. When the non-Markovian effect is neglected, the entanglement sudden death (ESD) is reproduced. On the other hand, when the non-Markovian is significantly strong but the bound state is absent, the phenomenon of the ESD and its revival is recovered. Our formulation presents a unified picture about the entanglement preservation and provides a clear clue on how to preserve the entanglement in quantum information processing.
Landscapes, tourism, and conservation
Burger
2000-04-17
One key aspect of global change is a decrease in ecological integrity as more and more landscapes are developed, leaving a mosaic of intact refuges and degraded patches that may not be sufficient for conserving biodiversity. While increases in human population and shifts in the distribution of people affect land use, the temporary movement of people can have major implications for conservation and biodiversity. Three examples are presented where recreation/tourism can enhance the conservation of land on a landscape scale, leading to habitat protection and biodiversity preservation: (1) Shorebirds often require a matrix of different habitat types during migratory stopovers, and ecotourism can serve as a catalyst for landscape scale protection of habitat. (2) Riparian habitats can serve as corridors to link diverse habitat patches, as well as serving as biodiversity hotspots. (3) Remediation and rehabilitation of contaminated lands, such as those of the US Department of Energy, aimed at developing recreational activities on the uncontaminated portions, can be the most economical form of re-development with no increase in human or ecological risk. Since large areas on many DOE sites have been undisturbed since the Second World War, when they were acquired, they contain unique or valuable ecosystems that serve an important role within their regional landscapes. In all three cases the judicious development of recreational/tourist interests can encourage both the conservation of habitats and the wise management of habitats on a landscape scale. While some species or habitats are too fragile for sustained tourism, many can be managed so that species, ecosystems and ecotourists flourish. By contributing to the economic base of regions, ecotourists/recreationists can influence the protection of land and biodiversity on a landscape scale, contributing to ecosystem management. The human dimensions of land preservation and biodiversity protection are key to long
Conservation reaches new heights.
Pepall, J; Khanal, P
1992-10-01
The conservation program with the management assistance of the Woodlands Mountain Institute in 2 contiguous parks, the Mount Everest National Park in Nepal and the Qomolangma Nature Reserve in China, in 2 countries is described. The focus is on conservation of the complex ecosystem with sustainable development by showing local people how to benefit from the park without environmental damage. Cultural diversity is as important as biological diversity. The area has been designated by UNESCO as a World Heritage Site with the "last pure ecological seed" of the Himalayas. The regional geography and culture are presented. Population growth has impacted natural resources through overgrazing, cultivation of marginal land, and deforestation; future plans to build a dam and road bordering the nature reserve pose other threats. Proposed management plans for the Makalu-Barun Nature Park (established in November 1991) and Conservation Area include a division of the park into nature reserve areas free of human activity, protected areas which permit traditional land use, and special sites and trail for tourists and religious pilgrims. The conservation area will act as a buffer for the park and provide economic opportunities; further subdivisions include land use for biodiversity protection, community forest and pasture, agroforestry, and agriculture and settlement. Efforts will be made to increase the welfare of women and local people; proposed projects include the introduction of higher milk-producing animals for stall feeding. Also proposed is a cultural and natural history museum. 70% of the project's resources will be directed to local community participation in consultation and park maintenance. The project is a model of how conservation and protection of natural resources can coexist with local economic development and participation; an integration of preservation of biological diversity, mountain wisdom, and the value of local people as resources for conservation. PMID
NASA Astrophysics Data System (ADS)
Kelly, Cynthia
2008-04-01
The Manhattan Project transformed the course of American and world history, science, politics and society. If we can read about this in books and watch History Channel documentaries, why do we need to preserve some of the properties of this enormous undertaking? The presentation, ``A History Worth Preserving,'' will address why some of the physical properties need to be preserved and which ones we are struggling to maintain for future generations. The story of this effort begins in 1997 as the Department of Energy was posed to demolish the last remaining Manhattan Project properties at the Los Alamos laboratory. Located deep behind security fences, the ``V Site's'' asbestos-shingled wooden buildings looked like humble garages with over-sized wooden doors. The ``V Site'' properties were almost lost twice, first to bulldozers and then the Cerro Grande fire of 2000. Now, visitors can stand inside the building where J. Robert Oppenheimer and his crew once worked and imagine the Trinity ``gadget'' hanging from its hoist shortly before it ushered in the Atomic Age on July 16, 1945. As Richard Rhodes has commented, we preserve what we value of the physical past because it specifically embodies our social past. But many challenge whether the Manhattan Project properties ought to be preserved. Rather than recognize the Manhattan Project as a great achievement worthy of commemoration, some see it as a regrettable event, producing an instrument to take man's inhumanity to man to extremes. While these divergent views will no doubt persist, the significance of the Manhattan Project in producing the world's first atomic bombs is irrefutable. Preserving some of its tangible remains is essential so that future generations can understand what the undertaking entailed from its humble wooden sheds to enormous first-of-a-kind industrial plants with 125,000 people working in secret and living in frontier-like communities. With continuing pressure for their demolition, what progress has
Conservation successes at micro-, meso- and macroscales.
Sodhi, Navjot S; Butler, Rhett; Laurance, William F; Gibson, Luke
2011-11-01
Although large-scale biodiversity declines are ongoing, certain conservation actions have made a positive difference. Rates of extinction and endangerment of vertebrate species, for instance, have probably been reduced via conservation interventions. Such conservation actions operate at different spatial scales. Habitat preservation and endangered species recovery are examples of conservation successes at microscales. Mesoscale conservation includes regional cooperation among neighboring countries that has arrested population declines of endangered species, such as mountain gorillas. At macroscales, public pressure on multinational corporations has sometimes resulted in their abandoning environmentally damaging practices or suppliers with poor environmental records. Overall, conservation projects such as these need more long-term funding and greater political and popular support, and must also include provisions to evaluate and document their outcomes. As we discuss here, a focus on conservation successes achieved at different scales can help to promote these aims and guide future conservation victories. PMID:21824677
Kinetic models in n-dimensional Euclidean spaces: From the Maxwellian to the Poisson kernel.
Zadehgol, Abed
2015-06-01
In this work, minimal kinetic theories based on unconventional entropy functions, H∼ln f (Burg entropy) for 2D and H∼f(1-2/n) (Tsallis entropy) for nD with n≥3, are studied. These entropy functions were originally derived by Boghosian et al. [Phys. Rev. E 68, 025103 (2003)] as a basis for discrete-velocity and lattice Boltzmann models for incompressible fluid dynamics. The present paper extends the entropic models of Boghosian et al. and shows that the explicit form of the equilibrium distribution function (EDF) of their models, in the continuous-velocity limit, can be identified with the Poisson kernel of the Poisson integral formula. The conservation and Navier-Stokes equations are recovered at low Mach numbers, and it is shown that rest particles can be used to rectify the speed of sound of the extended models. Fourier series expansion of the EDF is used to evaluate the discretization errors of the model. It is shown that the expansion coefficients of the Fourier series coincide with the velocity moments of the model. Employing two-, three-, and four-dimensional (2D, 3D, and 4D) complex systems, the real velocity space is mapped into the hypercomplex spaces and it is shown that the velocity moments can be evaluated, using the Poisson integral formula, in the hypercomplex space. For the practical applications, a 3D projection of the 4D model is presented, and the existence of an H theorem for the discrete model is investigated. The theoretical results have been verified by simulating the following benchmark problems: (1) the Kelvin-Helmholtz instability of thin shear layers in a doubly periodic domain and (2) the 3D flow of incompressible fluid in a lid-driven cubic cavity. The present results are in agreement with the previous works, while they show better stability of the proposed kinetic model, as compared with the BGK type (with single relaxation time) lattice Boltzmann models. PMID:26172826
Hydrology and Conservation Ecology
NASA Astrophysics Data System (ADS)
Narayanan, M.
2006-12-01
Responses to change in the behavior of ecological systems are largely governed by interactions at different levels. Research is essential and is to be necessarily designed to gain insights into various interactions at the community level. Sustainable resource management is only possible if conservation of biodiversity can be accomplished by properly using the knowledge discovered. It is well known that the United States Department of Agriculture provides technical information, resources, and data necessary to assist the researchers in addressing their conservation needs. Conservation aims to protect, preserve and conserve the earth's natural resources. These include, but not limited to the conservation of soil, water, minerals, air, plants and all living beings. The United States Department of Agriculture also encourages farmers and ranchers to voluntarily address threats to soil and water. Protection of wetlands and wildlife habitat has been on the radar screen of conservation experts for a very long time. The main objective has always been to help farmers and landowners conform and comply with federal and state environmental laws. During the implementation phase, farmers should be encouraged to make beneficial, cost-effective changes to methods of irrigation systems. In some cases, the hydrologic regime of the project area can be thought of as principally an issue of river flow regimes for floodplain forests. In this presentation, the author tries to focus on the impact of hydrology and conservation ecology on global warming. He also discusses the impact of hydrology and conservation ecology global air concerns such as greenhouse gas concentrations in the atmosphere. References: Chow, V. T, D. R. Maidment, and L. W. Mays. 1988. Applied Hydrology. McGraw-Hill, Inc. U.S. Soil Conservation Service. Technical Release 55: Urban Hydrology for Small Watersheds. USDA (U.S. Department of Agriculture). June 1986. Lehner, B. and P. Döll (2004). Development and validation
Williams, G.; Kourakis, I.
2013-12-15
Electrostatic solitary waves in plasmas are the focus of many current studies of localized electrostatic disturbances in both laboratory and astrophysical plasmas. Here, an investigation of the nonlinear dynamics of plasma evolving in two dimensions, in the presence of excess superthermal background electrons and positrons, is undertaken. We investigate the effect of a magnetic field on weakly nonlinear ion acoustic waves. Deviation from the Maxwellian distribution is effectively modelled by the kappa model. A linear dispersion relation is derived, and a decrease in frequency and phase speed in both parallel and perpendicular modes can be seen, when the proportion of positrons to electrons increases. We show that ion acoustic solitary waves can be generated during the nonlinear evolution of a plasma fluid, and their nonlinear propagation is governed by a Zakharov-Kuznetsov (ZK) type equation. A multiple scales perturbation technique is used to derive the ZK equation. The solitary wave structures are dependent on the relation between the system parameters, specifically the superthermality of the system, the proportion of positron content, magnetic field strength, and the difference between electron and positron temperature. The parametric effect of these on electrostatic shock structures is investigated. In particular, we find that stronger superthermality leads to narrower excitations with smaller potential amplitudes. Increased positron concentration also suppresses both the amplitude and the width of solitary wave structures. However, the structures are only weakly affected by temperature differentials between electrons and positrons in our model.
Family Preservation & Family Functioning.
ERIC Educational Resources Information Center
McCroskey, Jacquelyn; Meezan, William
This book reports a study of the outcomes of home-based family preservation services for abusive and neglectful families in Los Angeles County. Using the Family Assessment Form, the research project evaluated services provided by two voluntary agencies, and focused on changes in family functioning between the opening and closing of services during…
Preserving Southwest Virginia's Folklore.
ERIC Educational Resources Information Center
Burgin, Ramond
1997-01-01
Describes Southwest Virginia's rich tradition of folklore and culture and the need for its preservation. Summarizes the author's time-consuming process of preparing an inventory and indexing the vast archival collections gathered by students in American Folklore classes at Mountain Empire Community College and by the Southwest Virginia Folklore…
Preserving the Seminar Experience
ERIC Educational Resources Information Center
Ramsey, David; Evans, Jocelyn; Levy, Meyer
2016-01-01
This article presents a new approach to online graduate education. With hopes of recruiting a larger cohort in order to preserve a graduate program struggling with low enrollment, we began offering a limited number of seats to students who would attend class in real time but from remote locations, using a videoconferencing platform. Unlike…
ERIC Educational Resources Information Center
Powell, Larry E.; Miller, Larry E.
The publication contains an outline for use by agriculture teachers in developing a teaching plan for a unit on paints and preservatives. The topics included are (1) recognizing, solving, and preventing paint problems and (2) operating and using power spray painting equipment. Items presented for each topic are: the situation, (intended to inform…
Kinetic models in n -dimensional Euclidean spaces: From the Maxwellian to the Poisson kernel
NASA Astrophysics Data System (ADS)
Zadehgol, Abed
2015-06-01
In this work, minimal kinetic theories based on unconventional entropy functions, H ˜lnf (Burg entropy) for 2D and H ˜f1 -2/n (Tsallis entropy) for n D with n ≥3 , are studied. These entropy functions were originally derived by Boghosian et al. [Phys. Rev. E 68, 025103 (2003), 10.1103/PhysRevE.68.025103] as a basis for discrete-velocity and lattice Boltzmann models for incompressible fluid dynamics. The present paper extends the entropic models of Boghosian et al. and shows that the explicit form of the equilibrium distribution function (EDF) of their models, in the continuous-velocity limit, can be identified with the Poisson kernel of the Poisson integral formula. The conservation and Navier-Stokes equations are recovered at low Mach numbers, and it is shown that rest particles can be used to rectify the speed of sound of the extended models. Fourier series expansion of the EDF is used to evaluate the discretization errors of the model. It is shown that the expansion coefficients of the Fourier series coincide with the velocity moments of the model. Employing two-, three-, and four-dimensional (2D, 3D, and 4D) complex systems, the real velocity space is mapped into the hypercomplex spaces and it is shown that the velocity moments can be evaluated, using the Poisson integral formula, in the hypercomplex space. For the practical applications, a 3D projection of the 4D model is presented, and the existence of an H theorem for the discrete model is investigated. The theoretical results have been verified by simulating the following benchmark problems: (1) the Kelvin-Helmholtz instability of thin shear layers in a doubly periodic domain and (2) the 3D flow of incompressible fluid in a lid-driven cubic cavity. The present results are in agreement with the previous works, while they show better stability of the proposed kinetic model, as compared with the BGK type (with single relaxation time) lattice Boltzmann models.
ERIC Educational Resources Information Center
Friday, Gerald
2001-01-01
Introduces a project in which students teach about the importance of recycling and conservation by presenting demonstrations. Includes demonstrations on water, plastic, and other recycling products such as steel. (YDS)
43 CFR 5511.3-3 - Conservation practices.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false Conservation practices. 5511.3-3 Section... § 5511.3-3 Conservation practices. All free-use timber disposed of under the act shall be severed, or removed in accordance with sound forestry and conservation practices so as to preserve to the...
43 CFR 5511.3-3 - Conservation practices.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false Conservation practices. 5511.3-3 Section... § 5511.3-3 Conservation practices. All free-use timber disposed of under the act shall be severed, or removed in accordance with sound forestry and conservation practices so as to preserve to the...
43 CFR 5511.3-3 - Conservation practices.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false Conservation practices. 5511.3-3 Section... § 5511.3-3 Conservation practices. All free-use timber disposed of under the act shall be severed, or removed in accordance with sound forestry and conservation practices so as to preserve to the...
43 CFR 5511.3-3 - Conservation practices.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false Conservation practices. 5511.3-3 Section... § 5511.3-3 Conservation practices. All free-use timber disposed of under the act shall be severed, or removed in accordance with sound forestry and conservation practices so as to preserve to the...
NASA Technical Reports Server (NTRS)
Shoub, E. C.
1977-01-01
The problem of calculating the steady-state free-electron energy distribution in a hydrogen gas is considered in order to study departures of that distribution from a Maxwellian at sufficiently low degrees of ionization. A model kinetic equation is formulated and solved analytically for the one-particle electron distribution function in a steady-state partially ionized hydrogen gas, and it is shown that the formal solution can be accurately approximated by using the WKB method. The solutions obtained indicate that the high-energy tail of the distribution is susceptible to distortion by imbalanced inelastic collisions for ionization fractions not exceeding about 0.1 and that such departures from a Maxwellian can lead to significant changes in the collisional excitation and ionization rates of ground-state hydrogen atoms. Expressions for the electron-hydrogen collision rates are derived which explicitly display their dependence on the hydrogen departure coefficients. The results are applied in order to compare self-consistent predictions with those based on the a priori assumption of a Maxwellian distribution for models of the thermal ionization equilibrium of hydrogen in the optically thin limit, spectral-line formation by a gas consisting of two-level atoms, and radiative transfer in finite slabs by a gas of four-level hydrogen atoms.
Data Preservation in High Energy Physics
Mount, Richard; Brooks, Travis; Le Diberder, Francois; Dubois-Felsmann, Gregory; Neal, Homer; Bellis, Matt; Boehnlein, Amber; Votava, Margaret; White, Vicky; Wolbers, Stephen; Konigsberg, Jacobo; Roser, Robert; Snider, Rick; Lucchesi, Donatella; Denisov, Dmitri; Soldner-Rembold, Stefan; Li, Qizhong; Varnes, Erich; Jonckheere, Alan; Gasthuber, Martin; Gulzow, Volker; /DESY /Marseille, CPPM /Dortmund U. /DESY /Gent U. /DESY, Zeuthen /KEK, Tsukuba /CC, Villeurbanne /CERN /INFN, Bari /Gjovik Coll. Engineering /Karlsruhe, Forschungszentrum /Beijing, Inst. High Energy Phys. /Carleton U. /Cornell U. /Rutherford
2012-04-03
Data from high-energy physics (HEP) experiments are collected with significant financial and human effort and are mostly unique. At the same time, HEP has no coherent strategy for data preservation and re-use. An inter-experimental Study Group on HEP data preservation and long-term analysis was convened at the end of 2008 and held two workshops, at DESY (January 2009) and SLAC (May 2009). This document is an intermediate report to the International Committee for Future Accelerators (ICFA) of the reflections of this Study Group. Large data sets accumulated during many years of detector operation at particle accelerators are the heritage of experimental HEP. These data sets offer unique opportunities for future scientific studies, sometimes long after the shut-down of the actual experiments: new theoretical input; new experimental results and analysis techniques; the quest for high-sensitivity combined analyses; the necessity of cross checks. In many cases, HEP data sets are unique; they cannot and most likely will not be superseded by data from newer generations of experiments. Once lost, or in an unusable state, HEP data samples cannot be reasonably recovered. The cost of conserving this heritage through a collaborative, target-oriented long-term data preservation program would be small, compared to the costs of past experimental projects or to the efforts to re-do experiments. However, this cost is not negligible, especially for collaborations close or past their end-date. The preservation of HEP data would provide today's collaborations with a secure way to complete their data analysis and enable them to seize new scientific opportunities in the coming years. The HEP community will benefit from preserved data samples through reanalysis, combination, education and outreach. Funding agencies would receive more scientific return, and a positive image, from their initial investment leading to the production and the first analysis of preserved data.
Influence of relief on permanent preservation areas.
dos Santos, Alexandre Rosa; Chimalli, Tessa; Peluzio, João Batista Esteves; da Silva, Aderbal Gomes; dos Santos, Gleissy Mary Amaral Dino Alves; Lorenzon, Alexandre Simões; Teixeira, Thaisa Ribeiro; de Castro, Nero Lemos Martins; Soares Ribeiro, Carlos Antonio Alvares
2016-01-15
Many countries have environmental legislation to protecting natural resources on private property. In Brazil, the Brazilian Forestry Code determines specific areas to maintain with natural vegetation cover, known as areas of permanent preservation (APP). Currently, there are few studies that relate topographic variables on APP. In this context, we sought to evaluate the influence of relief on the conservation of areas of permanent preservation (APP) in the areas surrounding Caparaó National Park, Brazil. By using the chi-squared statistical test, we verified that the presence of forest cover is closely associated with altitude. The classes of APP in better conservation status are slopes in addition to hilltops and mountains, whereas APP streams and springs are among the areas most affected by human activities. The most deforested areas are located at altitudes below 1100.00 m and on slopes less than 45°. All orientations of the sides were significant for APP conservation status, with the southern, southeastern, and southwestern sides showing the lower degrees of impact. The methodology can be adjusted to environmental legislation to other countries. PMID:26476068
Symmetry-preserving difference schemes for some heat transfer equations
NASA Astrophysics Data System (ADS)
Bakirova, M. I.; Dorodnitsyn, V. A.; Kozlov, R. V.
1997-12-01
Lie group analysis of differential equations is a generally recognized method, which provides invariant solutions, integrability, conservation laws etc. In this paper we present three characteristic examples of the construction of invariant difference equations and meshes, where the original continuous symmetries are preserved in discrete models. Conservation of symmetries in difference modelling helps to retain qualitative properties of the differential equations in their difference counterparts.
Surgical strategies of fertility preservation in female cancers.
Grynberg, M; Frydman, R
2014-10-01
Conservative and functional surgery is increasingly used in surgical oncology. Although radical surgery remains the gold standard for treatment of cervical, endometrial and ovarian cancers, conservative approaches have been developed, aiming at preserving the potential of fertility of young patients. These procedures are proposed to selected patients, depending on histological parameters and prognostic factors as well. Therefore, a multidisciplinary approach is mandatory to weight the benefits and risks of fertility-sparing surgery. PMID:25245992
Enterocins in food preservation.
Khan, Haider; Flint, Steve; Yu, Pak-Lam
2010-06-30
The Enterococcus genus, a member of the Lactic Acid Bacteria (LAB) is found in various environments, but more particularly in the intestines of humans and other animals. Although sometimes associated with pathogenicity these bacteria have many benefits. They have been found in traditional artisanal fermented products, are used as probiotic cultures and nowadays extensively studied for the production of bacteriocins--the enterocins. Many of these enterocins have been found to be active against Listeria monocytogenes, and a few have also been reported to be active even against Gram negative bacteria, an unusual property for the bacteriocins produced by LAB. These properties have resulted in many studies describing the use of enterocins as preservatives in foods of animal and vegetable origin. This review covers the most recent information on the use of enterocins as food preservatives, either produced in-situ by the addition of enterocin producing strains or as external preservatives in the form of purified or semi-purified extracts, to prevent the growth of spoilage and pathogenic microorganisms. PMID:20399522
Mendoza, C.; Bautista, M. A. E-mail: manuel.bautista@wmich.edu
2014-04-20
The classic optical nebular diagnostics [N II], [O II], [O III], [S II], [S III], and [Ar III] are employed to search for evidence of non-Maxwellian electron distributions, namely κ distributions, in a sample of well-observed Galactic H II regions. By computing new effective collision strengths for all these systems and A-values when necessary (e.g., S II), and by comparing with previous collisional and radiative data sets, we have been able to obtain realistic estimates of the electron-temperature dispersion caused by the atomic data, which in most cases are not larger than ∼10%. If the uncertainties due to both observation and atomic data are then taken into account, it is plausible to determine for some nebulae a representative average temperature while in others there are at least two plasma excitation regions. For the latter, it is found that the diagnostic temperature differences in the high-excitation region, e.g., T{sub e} (O III), T{sub e} (S III), and T{sub e} (Ar III), cannot be conciliated by invoking κ distributions. For the low-excitation region, it is possible in some, but not all, cases to arrive at a common, lower temperature for [N II], [O II], and [S II] with κ ≈ 10, which would then lead to significant abundance enhancements for these ions. An analytic formula is proposed to generate accurate κ-averaged excitation rate coefficients (better than 10% for κ ≥ 5) from temperature tabulations of the Maxwell-Boltzmann effective collision strengths.
NASA Astrophysics Data System (ADS)
O'Leary, B.; Brown, L. F.; Gibson, R. A.; Versluis, J.
2000-12-01
With the first Russian flyby mission in 1959, the quest for robotic, and eventually, manned exploration of the moon became fact rather than fiction. Since then there have been innumerable spacecraft impacts and landers which have left artifacts and created archaeological sites on the lunar surface. One of the most significant events in lunar exploration came with the successful landing of the manned Apollo 11 mission in the Sea of Tranquillity (July 20, 1969). Missions such as these form a transcript of the world's quest to explore space and are evidence of humanity's first steps in this ultimate journey. One would think that, given the historic nature of these endeavors, some process would have been established to preserve sites for future generations. There is certainly little disagreement within the astronomical and archeological communities that lunar landing and impact sites are precious cultural resources containing irreplaceable artifacts that attest to humanity's initial efforts to explore other worlds. But, in fact, there are no federal preservation laws, nor international criteria, which directly address preservation procedures and decisions on other solar system bodies. Although the moon's remoteness and isolation have protected lunar sites to date, recent commercial interests in development, and in private robotic exploration, of the moon, make preservation of these historic sites even more timely. This preliminary study, funded in part by NASA, has begun to document the Apollo 11 landing site by making the first complete inventory of artifacts, and features, and completing an archeological site map of Tranquillity Base. We will discuss the issues in obtaining accurate lists of the cultural resources left behind, in documenting their historic context, and in the problems of selenographic mapping. Detailed information is needed to document the integrity historical importance of any location with the eventual aim of having it listed as a UNESCO World
NASA Astrophysics Data System (ADS)
Liu, Hailiang; Yi, Nianyu
2016-09-01
The invariant preserving property is one of the guiding principles for numerical algorithms in solving wave equations, in order to minimize phase and amplitude errors after long time simulation. In this paper, we design, analyze and numerically validate a Hamiltonian preserving discontinuous Galerkin method for solving the Korteweg-de Vries (KdV) equation. For the generalized KdV equation, the semi-discrete formulation is shown to preserve both the first and the third conserved integrals, and approximately preserve the second conserved integral; for the linearized KdV equation, all the first three conserved integrals are preserved, and optimal error estimates are obtained for polynomials of even degree. The preservation properties are also maintained by the fully discrete DG scheme. Our numerical experiments demonstrate both high accuracy of convergence and preservation of all three conserved integrals for the generalized KdV equation. We also show that the shape of the solution, after long time simulation, is well preserved due to the Hamiltonian preserving property.
ERIC Educational Resources Information Center
Ellis, William B.
1987-01-01
In 1986, Northeast Utilities began helping shool administrators combat school building energy wastage through a program called Energy Alliance. The typical school can reduce its energy bill by 30 percent by adopting a wide range of conservation measures, including cogeneration, relamping, and energy audits. (MLH)
ERIC Educational Resources Information Center
Texas Education Agency, Austin.
Instructional units deal with each aspect of conservation: forests, wildlife, rangelands, water, minerals, and soil. The area of the secondary school curriculum with which each is correlated is indicated. Lists of general and specific objectives are followed by suggested teaching procedures, including ideas for introducing the topic, questions to…
ERIC Educational Resources Information Center
Texas Education Agency, Austin.
Each of the six instructional units deals with one aspect of conservation: forests, water, rangeland, minerals (petroleum), and soil. The area of the elementary school curriculum with which each correlates is indicated. Lists of general and specific objectives are followed by suggested teaching procedures, including ideas for introducing the…
ERIC Educational Resources Information Center
Skophammer, Karen
2011-01-01
Some people only think about conservation on Earth Day. Being in the "art business" however, this author is always conscious of the many products she thinks get wasted when they could be reused, recycled, and restored--especially in a school building and art room. In this article, she describes an art lesson that allows students to paint…
The Once and Future Book: The Preservation Crisis.
ERIC Educational Resources Information Center
Brown, Jay Ward
1985-01-01
Discussion of problem of paper deterioration in books highlights developments in paper industry, acidic and alkaline paper, demand for book paper by publishing industry, library material conservation, and preservation activities in three areas--deacidification (use of alkaline chemicals to neutralize acidic paper), microfilming, and…
Why preserve and evaluate genetic resources in peanut?
Technology Transfer Automated Retrieval System (TEKTRAN)
Peanuts are produced in more than 100 countries with a total global total production in 2010 of 37,953,949 metric tons (FAO statistics, 2010). Because peanut is an important crop, it is imperative that its germplasm be preserved in order to conserve the genetic diversity and provide a resource to i...
12 CFR 627.2797 - Preservation of equity.
Code of Federal Regulations, 2010 CFR
2010-01-01
....2797 Banks and Banking FARM CREDIT ADMINISTRATION FARM CREDIT SYSTEM TITLE IV CONSERVATORS, RECEIVERS, AND VOLUNTARY LIQUIDATIONS Voluntary Liquidation § 627.2797 Preservation of equity. (a) Immediately... Credit Administration Board disapproves the liquidation plan. In the event the resolution to liquidate...
Preserving the Manhattan Project
NASA Astrophysics Data System (ADS)
Kelly, Cynthia
2014-03-01
When future generations look back on the 20th century, few events will rival the harnessing of nuclear energy as a turning point in world history, science and society. Yet, the Department of Energy has not always embraced its Manhattan Project origins. The presentation will focus on the progress made over the last 20 years to preserve the properties and first-hand accounts that for decades have been threatened with demolition and indifference. Since the mid-1950s, most remaining Manhattan Project properties at the Los Alamos National Laboratory had been abandoned. Among them was a cluster of wooden buildings called the ``V Site.'' This is where scientists assembled the ``Gadget,'' the world's first atomic device tested on July 16, 1945. Regardless of its significance, the ``V Site'' buildings like all the rest were slated for demolition. The Advisory Council on Historic Preservation (ACHP) toured the properties in November 1998. Most could not believe that the world's first atomic bomb was designed in such humble structures. The properties were declared to be ``monumental in their lack of monumentality.'' A Save America's Treasures grant for 700,000 was awarded to restore the properties. To raise the required matching funds, I left the Federal government and soon founded the Atomic Heritage Foundation. The presentation will trace the progress made over the last decade to generate interest and support nationwide to preserve the Manhattan Project heritage. Saving both the physical properties and first-hand accounts of the men and women have been a priority. Perhaps our most significant achievement may be legislation now under consideration by Congress to create a Manhattan Project National Historical Park. Seventy years later, the Manhattan Project is finally getting the recognition it deserves.
On preservation of symmetry in r-z staggered Lagrangian schemes
NASA Astrophysics Data System (ADS)
Váchal, Pavel; Wendroff, Burton
2016-02-01
In the focus of this work are symmetry preservation, conservation of energy and volume, and other important properties of staggered Lagrangian hydrodynamic schemes in cylindrical (r-z) geometry. It is well known that on quadrilateral cells in r-z, preservation of spherical symmetry, perfect satisfaction of the Geometrical Conservation Law (GCL), and total energy conservation are incompatible even on conforming grids. This paper suggests a novel staggered grid approach that preserves symmetry, conserves total energy by construction and tries to do its best by diminishing the GCL error to the order of entropy error. In particular, the forces from an existing volume consistent scheme are corrected so that spherical symmetry is preserved. The incorporation of subcell pressure mechanism to reduce spurious grid deformations is described and the relation of the new scheme to popular area-weighted and control volume approaches studied.
Preserving Perishables (Dormavac)
NASA Technical Reports Server (NTRS)
1979-01-01
A new commercial product that can preserve perishable commodities for weeks without freezing, so that they can be shipped fresh without the cost of air freight, has been developed by Grumman Corporation, Bethpage, Long Island, New York. The development benefited from the company's experience in developing the environmental control system for the Lunar Module, which delivered Apollo astronauts to the surface of the moon. Called Dormavac, the system provides a commodity-preserving environment within an aluminum container that can be transported by truck, rail or ship. Dormavac creates a cold-but above freezing-environment with high relative humidity and very low air pressure. The saturated air minimizes commodity weight loss and the air is automatically changed several times an hour to flush away odors and harmful gases released by the commodities. According to company literature, Dormavac significantly extends the transportation life of perishables. For example, pork has a normal cold storage life of about seven days, beef two weeks and tomatoes three weeks; with Dormavac, pork remains fresh for three weeks, beef more than six weeks and tomatoes seven weeks or more. Dormavac is manufactured and marketed by Grumman Allied Industries, Woodbury, New York. In developing the system, Grumman Allied drew upon the technological resources of another company subsidiary, Grumman Aerospace. Engineers who had earlier worked on Lunar Module environmental control brought their know-how and experience to the Dormavac development.
Kronfeld-Schor, Noga
2014-01-01
Global change presents a huge and exciting challenge to the study of thermal physiology. The implication of thermoregulatory strategies and abilities for the survival of individuals and species, are of high importance for predicting species response to global change challenges and ways to mitigate them, and for conservation acts. A good example of such a study is the paper by Cooper and Withers in this issue.1
Comparative genomics for biodiversity conservation
Grueber, Catherine E.
2015-01-01
Genomic approaches are gathering momentum in biology and emerging opportunities lie in the creative use of comparative molecular methods for revealing the processes that influence diversity of wildlife. However, few comparative genomic studies are performed with explicit and specific objectives to aid conservation of wild populations. Here I provide a brief overview of comparative genomic approaches that offer specific benefits to biodiversity conservation. Because conservation examples are few, I draw on research from other areas to demonstrate how comparing genomic data across taxa may be used to inform the characterisation of conservation units and studies of hybridisation, as well as studies that provide conservation outcomes from a better understanding of the drivers of divergence. A comparative approach can also provide valuable insight into the threatening processes that impact rare species, such as emerging diseases and their management in conservation. In addition to these opportunities, I note areas where additional research is warranted. Overall, comparing and contrasting the genomic composition of threatened and other species provide several useful tools for helping to preserve the molecular biodiversity of the global ecosystem. PMID:26106461
2000-01-01
Herons are large, popular and, in many cases, spectacular birds found in wetlands world-wide, both tropical and temperate, natural and man-made. Some populations are very small and localized, some have decreased, some have expanded their ranges, and a few are pests of human activities. In the fifteen years since the publication of the latest monographic treatment of the family, The Herons Handbook, there has been a tremendous increase in our knowledge of heron status and conservation requirements, set against a backdrop of increasing concern about the future of the world?s wetland habitats. This book provides a comprehensive update following two distinct threads. The status and conservation needs of herons are first presented on a regional basis, in a series of chapters set at a continental or subcontinental scale. Over 200 biologists and heron conservationists have contributed to the data summarized here, and the very latest census and survey results provide the most up-to-date and detailed picture of heron populations currently available. Chapters discussing several critical issues in heron conservation follow, tending to focus on the international nature of the problems.