2,583 research outputs found
A Unified Theory of Quasibound States
We have developed a formalism that includes both quasibound states with real
energies and quantum resonances within the same theoretical framework, and that
admits a clean and unambiguous distinction between these states and the states
of the embedding continuum. States described broadly as 'quasibound' are
defined as having a connectedness (in the mathematical sense) to true bound
states through the growth of some parameter. The approach taken here builds on
our earlier work by clarifying several crucial points and extending the
formalism to encompass a variety of continuous spectra, including those with
degenerate energy levels. The result is a comprehensive framework for the study
of quasibound states. The theory is illustrated by examining several cases
pertinent to applications widely discussed in the literature
Noncariogenic Sweeteners: Sugar Substitutes for Caries Control
The evidence is clear that the incidence of dental caries is related to the frequency of eating sugar. The use of sugar substitutes is a suggested way of reducing sugar intake. A variety of noncariogenic sweeteners exists, but most have no practical value for caries control because of their technical or safety problems, taste, or cost. Urinary bladder tumorigenic effects have been reported in experimental animals treated with saccharin and cyclamates. Because of concerns for human safety, cyclamates were banned in the U.S., and saccharin use was permitted only by special legislation. The polyalcohols sorbitol and xylitol are important sugar substitutes since they are not efficient substrates for plaque bacteria and therefore produce only minimal plaque pH drop.
Aspartame, with its sugar-like taste, is an excellent low-calorie sweetener now used in over 100 products under the name NutraSweet. Consumption of aspartame by normal humans is safe and does not promote tooth decay. Individuals with a need to control their phenylalanine intake should handle aspartame like any other source of phenylalanine
Neurologische und funktionelle Erholung nach Querschnittlähmung: Verlaufs- und Beurteilungsstandards in der Paraplegiologie
Zusammenfassung: Fortschritte experimenteller neurobiologischer Behandlungen—erzielt an Tiermodellen—eröffnen in den nächsten Jahren mögliche neue Therapieansätze in der Behandlung von Patienten mit Querschnittlähmung. Hierbei werden sowohl Strategien zur Reparation verletzter neuronaler Strukturen als auch Regenerationsmechanismen als Behandlungsziele unterschieden. Um die möglichen therapeutischen Effekte klinisch zu erfassen und in ihrer Wirkung zu beurteilen, müssen die klinischen Untersuchungsstandards angepasst werden. Die klinischen Verlaufsuntersuchungen und die Differenzierung der neurologischen und funktionellen Defizite bei Querschnittlähmung sollen einerseits die therapeutische Wirksamkeit (Qualität und Quantität der Verbesserungen) als auch mögliche unerwünschte Effekte (Nebenwirkungen systemisch oder fokal neurologisch) erfassen. In der vorliegenden Arbeit werden Ansätze zu diesen klinischen Untersuchungsstandards dargestell
Evaluation of cover crops in high tunnel vegetable rotation
Organic vegetable production within high tunnels allows for an extended growing season, crop protection, and environmental control. The USDA National Organic Program (NOP) standards mandate evidence that the soil has been maintained and improved over the course of production. Previous studies have indicated the potential of cover crops for reducing competitive vegetation, and improving soil quality, thus resulting in greater plant growth, nutrient uptake, and yield. However, there has been limited work in the confines of high tunnels as part of a tunnel-system rotation. Ten nitrogen-fixing and ten non-legume cover crops were established under a high tunnel and evaluated for their effects on the yield of ‘De Cicco’ broccoli (Brassica oleracea L. var. italica) and ‘Champion’ collards (Brassica oleracea L. var. acephala), aboveground biomass, and plant C and N contents. All treatments received recommended levels of appropriate certified organic fertilizers, water status was maintained, and vegetables received standard organic maintenance for insects and disease. The cover crops hairy indigo (Indigofera hirsuta L.), Catjang cowpea (Viana unguicalata L.), and Sunn hemp (Crotalaria juncea L.) consistently produced higher yields than Tifleaf III hybrid pearl millet (Pennisetum glaucum L.), Dairymaster brown midrib (BMR) hybrid grain sorghum (Sorghum spp.), and Wild Game Food sorghum (Sorghum bicolor L.). Nitrogenfixing legumes produced horticulturally significantly higher yields than the non-nitrogen-fixing grass species. This experiment demonstrated that not all cover crops are equal; they created variation in response. Cover crops provide a viable option for organic producers to maintain or improve soil quality over the course of production
Linked Open Data in the Global Change Information System (GCIS)
The U.S. Global Change Research Program (http://globalchange.gov) coordinates and integrates federal research on changes in the global environment and their implications for society. The USGCRP is developing a Global Change Information System (GCIS) that will centralize access to data and information related to global change across the U.S. federal government. The first implementation will focus on the 2013 National Climate Assessment (NCA) . (http://assessment.globalchange.gov) The NCA integrates, evaluates, and interprets the findings of the USGCRP; analyzes the effects of global change on the natural environment, agriculture, energy production and use, land and water resources, transportation, human health and welfare, human social systems, and biological diversity; and analyzes current trends in global change, both human-induced and natural, and projects major trends for the subsequent 25 to 100 years. The NCA has received over 500 distinct technical inputs to the process, many of which are reports distilling and synthesizing even more information, coming from thousands of individuals around the federal, state and local governments, academic institutions and non-governmental organizations. The GCIS will present a web-based version of the NCA including annotations linking the findings and content of the NCA with the scientific research, datasets, models, observations, etc. that led to its conclusions. It will use semantic tagging and a linked data approach, assigning globally unique, persistent, resolvable identifiers to all of the related entities and capturing and presenting the relationships between them, both internally and referencing out to other linked data sources and back to agency data centers. The developing W3C PROV Data Model and ontology will be used to capture the provenance trail and present it in both human readable web pages and machine readable formats such as RDF and SPARQL. This will improve visibility into the assessment process, increase understanding and reproducibility, and ultimately increase credibility and trust of the resulting report. Building on the foundation of the NCA, longer term plans for the GCIS include extending these capabilities throughout the U.S. Global Change Research Program, centralizing access to global change data and information across the thirteen agencies that comprise the program
Dynamics of Transcapillary Fluid Exchange
Fluid balance at the capillary level has been simulated with an analogue computer program, based on experimental data on regional differences in capillary permeability, surface areas, and hydrostatic pressures. The program takes into account fluid and protein fluxes into and out of the interstitial space. Solutions are obtained for tissue hydrostatic pressure, tissue fluid osmotic pressure, interstitial space volume, and lymph flow. Simulation of a variety of physiological experiments and clinical disease states has yielded reasonable agreement between experimental data and data obtained by computer analysis. Dilution of the interstitial plasma protein pool with a consequent reduc6tion of its oncotic pressure appears to be a major factor, which prevents edema unless plasma oncotic pressures are reduced by 10–15 mm Hg or, alternatively, venous pressures are elevated by a similar amount. The computer analysis in all instances yields positive values for tissue pressure, in agreement with experimental data obtained by needle puncture. The negative tissue pressures observed in subcutaneous capsules can be reproduced in the computer program, if the interface between the capsule and the surrounding interstitial space is assumed to have the properties of a semipermeable membrane
Digital Wars -- Legal Battles and Economic Bottlenecks in the Digital Information Industries
The Digital Age has spawned major legal battles over the fundamental principles of intellectual property law and antitrust law. These diverse struggles can best be analyzed using the basic norm of value added from neo-classical normative economics. This analysis suggests that current intellectual property doctirnes provide excessive protection and current antitrust doctrines remain awkward in dealing with the cross-market leveraging of monopoly power in the presence of natural monopolies created by network effects
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