Blood-brain barrier disruption by continuous-wave radio frequency radiation.

Science.gov (United States)

Sirav, Bahriye; Seyhan, Nesrin

2009-01-01

The increasing use of cellular phones and the increasing number of associated base stations are becoming a widespread source of non ionizing electromagnetic radiation. Some biological effects are likely to occur even at low-level EM fields. This study was designed to investigate the effects of 900 and 1,800 MHz Continuous Wave Radio Frequency Radiation (CW RFR) on the permeability of Blood Brain Barrier (BBB) of rats. Results have shown that 20 min RFR exposure of 900 and 1,800 MHz induces an effect and increases the permeability of BBB of male rats. There was no change in female rats. The scientific evidence on RFR safety or harm remains inconclusive. More studies are needed to demonstrate the effects of RFR on the permeability of BBB and the mechanisms of that breakdown.

Information barriers

International Nuclear Information System (INIS)

Fuller, J.L.; Wolford, J.

2001-01-01

Full text: An information barrier (IB) consists of procedures and technology that prevent the release of sensitive information during a joint inspection of a sensitive nuclear item, and provides confidence that the measurement system into which it has been integrated functions exactly as designed and constructed. Work in the U.S. on radiation detection system information barriers dates back at least to 1990, even though the terminology is more recent. In January 1999 the Joint DoD-DOE Information Barrier Working Group was formed in the United States to help coordinate technical efforts related to information barrier R and D. This paper presents an overview of the efforts of this group, by its Chairs, as well as recommendations for further information barrier R and D. Progress on the demonstration of monitoring systems containing IBs is also provided. From the U.S. perspective, the basic, top-level functional requirements for the information barrier portion of an integrated radiation signature-information barrier inspection system are twofold: The host must be assured that his classified information is protected from disclosure to the inspecting party; and The inspecting party must be confident that the integrated inspection system measures, processes, and presents the radiation-signature-based measurement conclusion in an accurate and reproducible manner. It is the position of the United States that in the absence of any agreement to share classified nuclear weapons design information in the conduct of an inspection regime, the requirement to protect host country classified warhead design information is paramount and admits no tradeoff versus the confidence provided to the inspecting party in the accuracy and reproducibility of the measurements. The U.S. has reached an internal consensus on several critical design elements that define a general standard for radiation signature information barrier design. These criteria have stood the test of time under intense

Impaired Skin Barrier Due to Sebaceous Gland Atrophy in the Latent Stage of Radiation-Induced Skin Injury: Application of Non-Invasive Diagnostic Methods

Directory of Open Access Journals (Sweden)

Hyosun Jang

2018-01-01

Full Text Available Radiation-induced skin injury can take the form of serious cutaneous damage and have specific characteristics. Asymptomatic periods are classified as the latent stage. The skin barrier plays a critical role in the modulation of skin permeability and hydration and protects the body against a harsh external environment. However, an analysis on skin barrier dysfunction against radiation exposure in the latent stage has not been conducted. Thus, we investigated whether the skin barrier is impaired by irradiation in the latent stage and aimed to identify the molecules involved in skin barrier dysfunction. We analyzed skin barrier function and its components in SKH1 mice that received 20 and 40 Gy local irradiation. Increased transepidermal water loss and skin pH were observed in the latent stage of the irradiated skin. Skin barrier components, such as structural proteins and lipid synthesis enzymes in keratinocyte, increased in the irradiated group. Interestingly, we noted sebaceous gland atrophy and increased serine protease and inflammatory cytokines in the irradiated skin during the latent period. This finding indicates that the main factor of skin barrier dysfunction in the latent stage of radiation-induced skin injury is sebaceous gland deficiency, which could be an intervention target for skin barrier impairment.

[Blood-brain barrier part III: therapeutic approaches to cross the blood-brain barrier and target the brain].

Science.gov (United States)

Weiss, N; Miller, F; Cazaubon, S; Couraud, P-O

2010-03-01

Over the last few years, the blood-brain barrier has come to be considered as the main limitation for the treatment of neurological diseases caused by inflammatory, tumor or neurodegenerative disorders. In the blood-brain barrier, the close intercellular contact between cerebral endothelial cells due to tight junctions prevents the passive diffusion of hydrophilic components from the bloodstream into the brain. Several specific transport systems (via transporters expressed on cerebral endothelial cells) are implicated in the delivery of nutriments, ions and vitamins to the brain; other transporters expressed on cerebral endothelial cells extrude endogenous substances or xenobiotics, which have crossed the cerebral endothelium, out of the brain and into the bloodstream. Recently, several strategies have been proposed to target the brain, (i) by by-passing the blood-brain barrier by central drug administration, (ii) by increasing permeability of the blood-brain barrier, (iii) by modulating the expression and/or the activity of efflux transporters, (iv) by using the physiological receptor-dependent blood-brain barrier transport, and (v) by creating new viral or chemical vectors to cross the blood-brain barrier. This review focuses on the illustration of these different approaches. Copyright (c) 2009 Elsevier Masson SAS. All rights reserved.

Ultraviolet-B radiation enhancement in dielectric barrier discharge based xenon chloride exciplex source by air

Energy Technology Data Exchange (ETDEWEB)

Gulati, P., E-mail: pgulati1512@gmail.com [CSIR-Central Electronics Engineering Research Institute (CSIR-CEERI), Pilani, Rajasthan-333031 (India); Department of Physics, Banasthali University, P.O. Banasthali Vidyapith, Rajasthan 304022 (India); Prakash, R.; Pal, U. N.; Kumar, M. [CSIR-Central Electronics Engineering Research Institute (CSIR-CEERI), Pilani, Rajasthan-333031 (India); Vyas, V. [Department of Physics, Banasthali University, P.O. Banasthali Vidyapith, Rajasthan 304022 (India)

2014-07-07

A single barrier dielectric barrier discharge tube of quartz with multi-strip Titanium-Gold (Ti-Au) coatings have been developed and utilized for ultraviolet-B (UV-B) radiation production peaking at wavelength 308 nm. The observed radiation at this wavelength has been examined for the mixtures of the Xenon together with chlorine and air admixtures. The gas mixture composition, chlorine gas content, total gas pressure, and air pressure dependency of the UV intensity, has been analyzed. It is found that the larger concentration of Cl{sub 2} deteriorates the performance of the developed source and around 2% Cl{sub 2} in this source produced optimum results. Furthermore, an addition of air in the xenon and chlorine working gas environment leads to achieve same intensity of UV-B light but at lower working gas pressure where significant amount of gas is air.

Ultraviolet-B radiation enhancement in dielectric barrier discharge based xenon chloride exciplex source by air

Science.gov (United States)

Gulati, P.; Prakash, R.; Pal, U. N.; Kumar, M.; Vyas, V.

2014-07-01

A single barrier dielectric barrier discharge tube of quartz with multi-strip Titanium-Gold (Ti-Au) coatings have been developed and utilized for ultraviolet-B (UV-B) radiation production peaking at wavelength 308 nm. The observed radiation at this wavelength has been examined for the mixtures of the Xenon together with chlorine and air admixtures. The gas mixture composition, chlorine gas content, total gas pressure, and air pressure dependency of the UV intensity, has been analyzed. It is found that the larger concentration of Cl2 deteriorates the performance of the developed source and around 2% Cl2 in this source produced optimum results. Furthermore, an addition of air in the xenon and chlorine working gas environment leads to achieve same intensity of UV-B light but at lower working gas pressure where significant amount of gas is air.

Expression of ICAM-1 in blood-spinal cord barrier disruption and CNS radiation injury

International Nuclear Information System (INIS)

Nordal, R.A.; Li, Y.-Q.; Wong, C.S.

2003-01-01

Full text: Intercellular adhesion molecule-1 (ICAM-1) expression is increased following a number of CNS insults in association with blood-brain barrier (BBB) disruption. While disruption of ICAM-1 expression reduces injury in diverse pathologies ranging from trauma to ischemia, its role in CNS radiation injury is not understood. Adult rats received 0 to 22 Gy to a 1.6 cm length of the cervical spinal cord. Expression of ICAM-1 was studied using immunohistochemistry (IHC). Blood-spinal cord barrier (BSCB) disruption was detected by IHC for endogenous albumin and the BBB protein endothelial barrier antigen (EBA). To assess the role of ICAM-1 in the mechanisms of BSCB disruption, animals received IV injections of an ICAM-1-specific blocking antibody (IA-29) or vehicle control, and BSCB disruption was examined by albumin IHC. ICAM-1, albumin, and EBA staining areas were quantified by digital image analysis. ICAM-1 expression localized predominantly to endothelium in non-irradiated spinal cord sections. Some expression was also identified in astrocytes. ICAM-1 expression was increased in white matter, but not in grey matter following radiation. After 22 Gy, ICAM-1 protein increased at 24 hours, and increased again from baseline at 17-20 weeks. Induction was seen in both the total immunostained area, and in the number of ICAM-1 positive glia. A dose response was observed in ICAM-1 expression 20 weeks after 16-20 Gy. BSCB disruption also increased with doses 16-20 Gy at 20 weeks. Blocking ICAM-1 with IA-29 significantly decreased BSCB leakage of albumin at 24 hours (p=0.03). Regions with both increased ICAM-1 expression and BSCB disruption were identified in white matter. Thus the dose response and spatial distribution of increased ICAM-1 expression parallels that for BSCB disruption. These results are consistent with a role for increased ICAM-1 expression in radiation-induced BSCB disruption. The effect of blocking ICAM-1 with a neutralizing antibody suggests its

Effects of GSM modulated radio-frequency electromagnetic radiation on permeability of blood-brain barrier in male & female rats.

Science.gov (United States)

Sırav, Bahriye; Seyhan, Nesrin

2016-09-01

With the increased use of mobile phones, their biological and health effects have become more important. Usage of mobile phones near the head increases the possibility of effects on brain tissue. This study was designed to investigate the possible effects of pulse modulated 900MHz and 1800MHz radio-frequency radiation on the permeability of blood-brain barrier of rats. Study was performed with 6 groups of young adult male and female wistar albino rats. The permeability of blood-brain barrier to intravenously injected evans blue dye was quantitatively examined for both control and radio-frequency radiarion exposed groups. For male groups; Evans blue content in the whole brain was found to be 0.08±0.01mg% in the control, 0.13±0.03mg% in 900MHz exposed and 0.26±0.05mg% in 1800MHz exposed animals. In both male radio-frequency radiation exposed groups, the permeability of blood-brain barrier found to be increased with respect to the controls (pradiation exposure was found more effective on the male animals (p0.01). However 900MHz pulse modulated radio-frequency exposure was found effective on the permeability of blood-brain barrier of female animals. Results have shown that 20min pulse modulated radio-frequency radiation exposure of 900MHz and 1800MHz induces an effect and increases the permeability of blood-brain barrier of male rats. For females, 900MHz was found effective and it could be concluded that this result may due to the physiological differences between female and male animals. The results of this study suggest that mobile phone radation could lead to increase the permeability of blood-brain barrier under non-thermal exposure levels. More studies are needed to demonstrate the mechanisms of that breakdown. Copyright © 2015 Elsevier B.V. All rights reserved.

Interleukin-12 Preserves the Cutaneous Physical and Immunological Barrier after Radiation Exposure

Science.gov (United States)

Gerber, Scott A.; Cummings, Ryan J.; Judge, Jennifer L.; Barlow, Margaret L.; Nanduri, Julee; Milano Johnson, Doug E.; Palis, James; Pentland, Alice P.; Lord, Edith M.; Ryan, Julie L.

2015-01-01

The United States continues to be a prime target for attack by terrorist organizations in which nuclear detonation and dispersal of radiological material are legitimate threats. Such attacks could have devastating consequences to large populations, in the form of radiation injury to various human organ systems. One of these at risk organs is the cutaneous system, which forms both a physical and immunological barrier to the surrounding environment and is particularly sensitive to ionizing radiation. Therefore, increased efforts to develop medical countermeasures for treatment of the deleterious effects of cutaneous radiation exposure are essential. Interleukin-12 (IL-12) was shown to elicit protective effects against radiation injury on radiosensitive systems such as the bone marrow and gastrointestinal tract. In this article, we examined if IL-12 could protect the cutaneous system from a combined radiation injury in the form of sublethal total body irradiation and beta-radiation burn (β-burn) directly to the skin. Combined radiation injury resulted in a breakdown in skin integrity as measured by transepidermal water loss, size of β-burn lesion and an exacerbated loss of surveillant cutaneous dendritic cells. Interestingly, intradermal administration of IL-12 48 h postirradiation reduced transepidermal water loss and burn size, as well as retention of cutaneous dendritic cells. Our data identify IL-12 as a potential mitigator of radiation-induced skin injury and argue for the further development of this cytokine as a radiation countermeasure. PMID:25564716

On a model-based approach to radiation protection

International Nuclear Information System (INIS)

Waligorski, M.P.R.

2002-01-01

There is a preoccupation with linearity and absorbed dose as the basic quantifiers of radiation hazard. An alternative is the fluence approach, whereby radiation hazard may be evaluated, at least in principle, via an appropriate action cross section. In order to compare these approaches, it may be useful to discuss them as quantitative descriptors of survival and transformation-like endpoints in cell cultures in vitro - a system thought to be relevant to modelling radiation hazard. If absorbed dose is used to quantify these biological endpoints, then non-linear dose-effect relations have to be described, and, e.g. after doses of densely ionising radiation, dose-correction factors as high as 20 are required. In the fluence approach only exponential effect-fluence relationships can be readily described. Neither approach alone exhausts the scope of experimentally observed dependencies of effect on dose or fluence. Two-component models, incorporating a suitable mixture of the two approaches, are required. An example of such a model is the cellular track structure theory developed by Katz over thirty years ago. The practical consequences of modelling radiation hazard using this mixed two-component approach are discussed. (author)

AN ACTIVITY THEORY APPROACH TO STUDY BARRIERS OF FACULTY REGARDING TECHNOLOGY INTEGRATION IN HIGHER EDUCATION

DEFF Research Database (Denmark)

Castro Guzman, Willy

2016-01-01

technology. Ertmer’s approach establishes first-order and second-orders barriers as hinderers for teacher’s adoption of technology. The study intends to answer what are the barriers existing in the socalled enthusiastic faculty teachers regarding technology integration in Education? Findings call...... dichotomies between enthusiastic-resistant teachers, the intrinsic-extrinsic barriers, and claims for passing from an individual to a collective approach to ICT integration in education......Information and communication technologies are instruments for supporting new ways of teaching and learning. Nevertheless, its impact concerning scope has not reached the expected level. This strain between benefits and impact has been inquired from the perspective of barriers of teachers to use...

Effect of potential barrier growth of auto-localized excitons decay on radiation defects in AHC at low lattice symmetry

International Nuclear Information System (INIS)

Shunkeev, K.; Sagimbaeva, Sh.; Shunkeev, S.

2007-01-01

Effect of auto-localized excitons (ALE) luminescence strengthening is conditioned by two mechanisms: either decrease of potential barrier divided of quasi-free states and auto-localized states or decrease of emission-less channel effectiveness of exciton decay on primary radiation defects. In considered range (80 K) all excitons are only in auto-localized state. Therefore a realization of the first mechanism is improbable, For instant, in KI crystal at 80-100 K luminescence of free exciton is completely putting out, and ALE luminescence has maximal intensity. It is known that in the temperature range when ALE luminescence putting out is beginning an effectiveness of radiation defects is beginning to grow. This effect is related with predominating at that time emission-less exciton decay on radiation defects (F-H pairs). Experimentally by luminescence spectroscopy method activation energy of temperature putting out of ALE in AHC under uniaxial deformation. It is revealed, that increase of activation energy value has observed in a number of crystals: KBr→NaCl→KI→Na Br→CsBr→RbI. It is concluded, that effect of ALE intensity building-up and decrease of effectiveness of radiation defect formation are interpreted by growth of potential barrier of ALE decay into radiation defects under low symmetry of AHC lattice of low-temperature uniaxial deformation

Short and long-term lifestyle coaching approaches used to address diverse participant barriers to weight loss and physical activity adherence.

Science.gov (United States)

Venditti, Elizabeth M; Wylie-Rosett, Judith; Delahanty, Linda M; Mele, Lisa; Hoskin, Mary A; Edelstein, Sharon L

2014-02-12

Individual barriers to weight loss and physical activity goals in the Diabetes Prevention Program, a randomized trial with 3.2 years average treatment duration, have not been previously reported. Evaluating barriers and the lifestyle coaching approaches used to improve adherence in a large, diverse participant cohort can inform dissemination efforts. Lifestyle coaches documented barriers and approaches after each session (mean session attendance = 50.3 ± 21.8). Subjects were 1076 intensive lifestyle participants (mean age = 50.6 years; mean BMI = 33.9 kg/m²; 68% female, 48% non-Caucasian). Barriers and approaches used to improve adherence were ranked by the percentage of the cohort for whom they applied. Barrier groupings were also analyzed in relation to baseline demographic characteristics. Top weight loss barriers reported were problems with self-monitoring (58%); social cues (58%); holidays (54%); low activity (48%); and internal cues (thought/mood) (44%). Top activity barriers were holidays (51%); time management (50%); internal cues (30%); illness (29%), and motivation (26%). The percentage of the cohort having any type of barrier increased over the long-term intervention period. A majority of the weight loss barriers were significantly associated with younger age, greater obesity, and non-Caucasian race/ethnicity (p-values vary). Physical activity barriers, particularly thought and mood cues, social cues and time management, physical injury or illness and access/weather, were most significantly associated with being female and obese (p  90% long term) and regularly reviewed self-monitoring skills. More costly approaches were used infrequently during the first 16 sessions (≤10%) but increased over 3.2 years. Behavioral problem solving approaches have short and long term dissemination potential for many kinds of participant barriers. Given minimal resources, increased attention to training lifestyle coaches in the consistent use of these

Modeling approaches for concrete barriers used in low-level waste disposal

International Nuclear Information System (INIS)

Seitz, R.R.; Walton, J.C.

1993-11-01

A series of three NUREGs and several papers addressing different aspects of modeling performance of concrete barriers for low-level radioactive waste disposal have been prepared previously for the Concrete Barriers Research Project. This document integrates the information from the previous documents into a general summary of models and approaches that can be used in performance assessments of concrete barriers. Models for concrete degradation, flow, and transport through cracked concrete barriers are discussed. The models for flow and transport assume that cracks have occurred and thus should only be used for later times in simulations after fully penetrating cracks are formed. Most of the models have been implemented in a computer code. CEMENT, that was developed concurrently with this document. User documentation for CEMENT is provided separate from this report. To avoid duplication, the reader is referred to the three previous NUREGs for detailed discussions of each of the mathematical models. Some additional information that was not presented in the previous documents is also included. Sections discussing lessons learned from applications to actual performance assessments of low-level waste disposal facilities are provided. Sensitive design parameters are emphasized to identify critical areas of performance for concrete barriers, and potential problems in performance assessments are also identified and discussed

Calculation of the Electronic Parameters of an Al/DNA/p-Si Schottky Barrier Diode Influenced by Alpha Radiation

Directory of Open Access Journals (Sweden)

Hassan Maktuff Jaber Al-Ta'ii

2015-02-01

Full Text Available Many types of materials such as inorganic semiconductors have been employed as detectors for nuclear radiation, the importance of which has increased significantly due to recent nuclear catastrophes. Despite the many advantages of this type of materials, the ability to measure direct cellular or biological responses to radiation might improve detector sensitivity. In this context, semiconducting organic materials such as deoxyribonucleic acid or DNA have been studied in recent years. This was established by studying the varying electronic properties of DNA-metal or semiconductor junctions when exposed to radiation. In this work, we investigated the electronics of aluminium (Al/DNA/silicon (Si rectifying junctions using their current-voltage (I-V characteristics when exposed to alpha radiation. Diode parameters such as ideality factor, barrier height and series resistance were determined for different irradiation times. The observed results show significant changes with exposure time or total dosage received. An increased deviation from ideal diode conditions (7.2 to 18.0 was observed when they were bombarded with alpha particles for up to 40 min. Using the conventional technique, barrier height values were observed to generally increase after 2, 6, 10, 20 and 30 min of radiation. The same trend was seen in the values of the series resistance (0.5889–1.423 Ω for 2–8 min. These changes in the electronic properties of the DNA/Si junctions could therefore be utilized in the construction of sensitive alpha particle detectors.

Radiation safety standards : an environmentalist's approach

International Nuclear Information System (INIS)

Murthy, M.S.S.S.

1977-01-01

An integrated approach to the problem of environmental mutagenic hazards leads to the recommendation of a single dose-limit to the exposure of human beings to all man-made mutagenic agents including chemicals and radiation. However, because of lack of : (1) adequate information on chemical mutagens, (2) sufficient data on their risk estimates and (3) universally accepted dose-limites, control of chemical mutagens in the environment has not reached that advanced stage as that of radiation. In this situation, the radiation safety standards currently in use should be retained at their present levels. (M.G.B.)

"I sleep better at night:" How peer review of radiation treatment plans indirectly improves quality of care across radiation treatment programs.

Science.gov (United States)

Brundage, Michael D; Hart, Margaret; O'Donnell, Jennifer; Reddeman, Lindsay; Gutierrez, Eric; Foxcroft, Sophie; Warde, Padraig

Peer review of radiation oncology treatment plans is increasingly recognized as an important component of quality assurance in radiation treatment planning and delivery. Peer review of treatment plans can directly improve the quality of those plans and can also have indirect effects on radiation treatment programs. We undertook a systematic, qualitative approach to describing the indirect benefits of peer review, factors that were seen to facilitate or act as barriers to the implementation of peer review, and strategies to address these barriers across a provincial jurisdiction of radiation oncology programs (ROPs). Semistructured qualitative interviews were held with radiation oncology department heads and radiation therapy managers (or delegates) in all 14 ROPs in Ontario, Canada. We used a theoretically guided phenomenological qualitative approach to design and analyze the interview content. Themes were recorded by 2 independent reviewers, and any discordance was resolved by consensus. A total of 28 interviews were completed with 32 interviewees. Twenty-two unique themes addressed perceived benefits of peer review, relating to either peer review structure (n = 3), process (n = 9), or outcome (n = 10). Of these 22 themes, 19 related to indirect benefits to ROPs. In addition, 18 themes related to factors that facilitated peer review activities and 30 themes related to key barriers to implementing peer review were identified. Findings were consistent with, and enhanced the understanding of, previous survey-based assessments of the benefits and challenges of implementing peer review programs. Although challenges and concerns regarding the implementation of peer review were evident, the indirect benefits to radiation programs are numerous, far outweigh the implementation challenges, and strongly complement the direct individual-patient benefits that result from peer review quality assurance of radiation treatment plans. Copyright © 2016. Published by Elsevier Inc.

Beyond mean-field approach to heavy-ion reactions around the Coulomb barrier

Directory of Open Access Journals (Sweden)

Ayik Sakir

2011-10-01

Full Text Available Dissipation and fluctuations of one-body observables in heavy-ion reactions around the Coulomb barrier are investigated with a microscopic stochastic mean-field approach. By projecting the stochastic meanfield dynamics on a suitable collective path, transport coefficients associated with the relative distance between colliding nuclei and a fragment mass are extracted. Although microscopic mean-field approach is know to underestimate the variance of fragment mass distribution, the description of the variance is much improved by the stochastic mean-field method. While fluctuations are consistent with the empirical (semiclassical analysis of the experimental data, concerning mean values of macroscopic variables the semiclassical description breaks down below the Coulomb barrier.

Practical protective tools for occupational exposure: 1) double focus spectacles for the aged with highly refracted glass lens 2) remodeled barrier for radiation protection.

Science.gov (United States)

Kurokawa, S; Yabe, S; Takamura, A; Ishizaki, H; Aizawa, S

2000-11-30

Two practical protective tools for occupational exposure for neurointerventional radiologists are presented. The first purpose of this study was to investigate the effectiveness of double focus spectacles for the aged with a highly refracted glass lens (special spectacles for the aged) for radiation protection of the crystalline lens of the eye in comparison with other spectacles on the market, based on the measurement of film density which was obtained by exposure of X-ray through those spectacles. As a result of the film densitometry mentioned above, the effectiveness of special spectacles for the aged in radiation protection was nearly equal to the effectiveness of a goggle type shield which is made with a 0.07 mm lead-equivalent plastic lens. The second purpose of this study was to investigate the effectiveness of the protective barrier, which we remodeled for cerebral angiography or neuroendovascular therapy, for radiation exposure, based on the measurement in a simulated study with a head phantom, and on the measurement of radiation exposure in operaters during procedures of clinical cases. In the experimental study radiation exposure in supposed position of the crystalline lens was reduced to about one third and radiation exposure in supposed position of the gonadal glands was reduced to about one seventh, compared to radiation exposure without employing the barrier. The radiation exposure was monitored at the left breast of three radiologists, in 215 cases of cerebral angiography. Employing the barrier in cerebral angiography, average equivalent dose at the left breast measured 1.49mu Sv during 10 min of fluoroscopy. In three kinds of neuroendovascular therapy in 40 cases, radiation exposure in an operator was monitored in the same fashion and the dose was recorded less than the result reported in previous papers in which any protective barrier have not been employed in the procedure (1,2). As a result, the two above mentioned protective tools are

A systems approach to the management of radiation accidents

International Nuclear Information System (INIS)

Richter, L.L.; Berk, H.W.; Teates, C.D.; Larkham, N.E.; Friesen, E.J.; Edlich, R.F.

1980-01-01

Management of radiation accident patients should have a multidisciplinary approach that includes all health professionals as well as members of public safety agencies. Emergency plans for radiation accidents include detection of the ionizing radiation, patient evacuation, resuscitation, and decontamination. The resuscitated patient should be transported to a radiation control area located outside but adjacent to the emergency department. Ideally this area is accessed through an entrance separate from that used for the main flow of daily emergency department patients. The hospital staff, provided with protective clothing, dosimeters, and preprinted guidelines, continues the resuscitation and definitive care of the patient. This system approach to the management of radiation accidents may be tailored to meet the specific needs of other emergency medical systems

Analyzing internal barriers for automotive parts remanufacturers in China using grey-DEMATEL approach

DEFF Research Database (Denmark)

Xia, Xiqiang; Govindan, Kannan; Zhu, Qinghua

2015-01-01

analyzes internal barriers met by automotive parts remanufacturers and evaluates causal barriers by a proposed model framework. This objective is illustrated by employing the Grey Decision Making Trial and Evaluation Laboratory (DEMATEL) approach. By virtue of these findings, remanufacturers can eradicate......Automotive industries have attracted attention from international sectors recently. This attention to the industry results in many innovative technologies being integrated in these manufacturing arenas. In developing countries such as the BRIC (Brazil, Russia, India, and China) countries...

Systems study on engineered barriers: barrier performance analysis

International Nuclear Information System (INIS)

Stula, R.T.; Albert, T.E.; Kirstein, B.E.; Lester, D.H.

1980-09-01

A performance assessment model for multiple barrier packages containing unreprocessed spent fuel has been modified and applied to several package designs. The objective of the study was to develop information to be used in programmatic decision making concerning engineered barrier package design and development. The assessment model, BARIER, was developed in previous tasks of the System Study on Engineered Barriers (SSEB). The new version discussed in this report contains a refined and expanded corrosion rate data base which includes pitting, crack growth, and graphitization as well as bulk corrosion. Corrosion rates for oxic and anoxic conditions at each of the two temperature ranges are supplied. Other improvements include a rigorous treatment of radionuclide release after package failure which includes resistance of damaged barriers and backfill, refined temperature calculations that account for convection and radiation, a subroutine to calculate nuclear gamma radiation field at each barrier surface, refined stress calculations with reduced conservatism and various coding improvements to improve running time and core usage. This report also contains discussion of alternative scenarios to the assumed flooded repository as well as the impact of water exclusion backfills. The model was used to assess post repository closure performance for several designs which were all variation of basic designs from the Spent Unreprocessed Fuel (SURF) program. Many designs were found to delay the onset of leaching by at least a few hundreds of years in all geologic media. Long delay times for radionuclide release were found for packages with a few inches of sorption backfill. Release of uranium, plutonium, and americium was assessed

Systems study on engineered barriers: barrier performance analysis

Energy Technology Data Exchange (ETDEWEB)

Stula, R.T.; Albert, T.E.; Kirstein, B.E.; Lester, D.H.

1980-09-01

A performance assessment model for multiple barrier packages containing unreprocessed spent fuel has been modified and applied to several package designs. The objective of the study was to develop information to be used in programmatic decision making concerning engineered barrier package design and development. The assessment model, BARIER, was developed in previous tasks of the System Study on Engineered Barriers (SSEB). The new version discussed in this report contains a refined and expanded corrosion rate data base which includes pitting, crack growth, and graphitization as well as bulk corrosion. Corrosion rates for oxic and anoxic conditions at each of the two temperature ranges are supplied. Other improvements include a rigorous treatment of radionuclide release after package failure which includes resistance of damaged barriers and backfill, refined temperature calculations that account for convection and radiation, a subroutine to calculate nuclear gamma radiation field at each barrier surface, refined stress calculations with reduced conservatism and various coding improvements to improve running time and core usage. This report also contains discussion of alternative scenarios to the assumed flooded repository as well as the impact of water exclusion backfills. The model was used to assess post repository closure performance for several designs which were all variation of basic designs from the Spent Unreprocessed Fuel (SURF) program. Many designs were found to delay the onset of leaching by at least a few hundreds of years in all geologic media. Long delay times for radionuclide release were found for packages with a few inches of sorption backfill. Release of uranium, plutonium, and americium was assessed.

The Electromagnetic Dipole Radiation Field through the Hamiltonian Approach

Science.gov (United States)

Likar, A.; Razpet, N.

2009-01-01

The dipole radiation from an oscillating charge is treated using the Hamiltonian approach to electrodynamics where the concept of cavity modes plays a central role. We show that the calculation of the radiation field can be obtained in a closed form within this approach by emphasizing the role of coherence between the cavity modes, which is…

A new approach to performance assessment of barriers in a repository. Executive summary, draft, technical appendices. Final report

International Nuclear Information System (INIS)

Mueller-Hoeppe, N.; Krone, J.; Niehues, N.; Poehler, M.; Raitz von Frentz, R.; Gauglitz, R.

1999-06-01

Multi-barrier systems are accepted as the basic approach for long term environmental safe isolation of radioactive waste in geological repositories. Assessing the performance of natural and engineered barriers is one of the major difficulties in producing evidence of environmental safety for any radioactive waste disposal facility, due to the enormous complexity of scenarios and uncertainties to be considered. This report outlines a new methodological approach originally developed basically for a repository in salt, but that can be transferred with minor modifications to any other host rock formation. The approach is based on the integration of following elements: (1) Implementation of a simple method and efficient criteria to assess and prove the tightness of geological and engineered barriers; (2) Using the method of Partial Safety Factors in order to assess barrier performance at certain reasonable level of confidence; (3) Integration of a diverse geochemical barrier in the near field of waste emplacement limiting systematically the radiological consequences from any radionuclide release in safety investigations and (4) Risk based approach for the assessment of radionuclide releases. Indicative calculations performed with extremely conservative assumptions allow to exclude any radiological health consequences from a HLW repository in salt to a reference person with a safety level of 99,9999% per year. (orig.)

Self-regulation of turbulence bursts and transport barriers

International Nuclear Information System (INIS)

Floriani, E; Ciraolo, G; Ghendrih, Ph; Sarazin, Y; Lima, R

2013-01-01

The interplay between turbulent bursts and transport barriers is analyzed with a simplified model of interchange turbulence in magnetically confined plasmas. The turbulent bursts spread into the transport barriers and, depending on the competing magnitude of the burst and stopping capability of the barrier, can burn through. Simulations of two models of transport barriers are presented: a hard barrier where interchange turbulence modes are stable in a prescribed region and a soft barrier with external plasma biasing. The response of the transport barriers to the non-linear perturbations of the turbulent bursts, addressed in a predator–prey approach, indicates that the barriers monitor an amplification factor of the turbulent bursts, with amplification smaller than one for most bursts and, in some cases, amplification factors that can significantly exceed unity. The weak barriers in corrugated profiles and magnetic structures, as well as the standard barriers, are characterized by these transmission properties, which then regulate the turbulent burst transport properties. The interplays of barriers and turbulent bursts are modeled as competing stochastic processes. For different classes of the probability density function (PDF) of these processes, one can predict the heavy tail properties of the bursts downstream from the barrier, either exponential for a leaky barrier, or with power laws for a tight barrier. The intrinsic probing of the transport barriers by the turbulent bursts thus gives access to the properties of the barriers. The main stochastic variables are the barrier width and the spreading distance of the turbulent bursts within the barrier, together with their level of correlation. One finds that in the case of a barrier with volumetric losses, such as radiation or particle losses as addressed in our present simulations, the stochastic model predicts a leaky behavior with an exponential PDF of escaping turbulent bursts in agreement with the simulation

An integrated artificial neural networks approach for predicting global radiation

International Nuclear Information System (INIS)

Azadeh, A.; Maghsoudi, A.; Sohrabkhani, S.

2009-01-01

This article presents an integrated artificial neural network (ANN) approach for predicting solar global radiation by climatological variables. The integrated ANN trains and tests data with multi layer perceptron (MLP) approach which has the lowest mean absolute percentage error (MAPE). The proposed approach is particularly useful for locations where no available measurement equipment. Also, it considers all related climatological and meteorological parameters as input variables. To show the applicability and superiority of the integrated ANN approach, monthly data were collected for 6 years (1995-2000) in six nominal cities in Iran. Separate model for each city is considered and the quantity of solar global radiation in each city is calculated. Furthermore an integrated ANN model has been introduced for prediction of solar global radiation. The acquired results of the integrated model have shown high accuracy of about 94%. The results of the integrated model have been compared with traditional angstrom's model to show its considerable accuracy. Therefore, the proposed approach can be used as an efficient tool for prediction of solar radiation in the remote and rural locations with no direct measurement equipment.

Machine Learning Approaches for Predicting Radiation Therapy Outcomes: A Clinician's Perspective

International Nuclear Information System (INIS)

Kang, John; Schwartz, Russell; Flickinger, John; Beriwal, Sushil

2015-01-01

Radiation oncology has always been deeply rooted in modeling, from the early days of isoeffect curves to the contemporary Quantitative Analysis of Normal Tissue Effects in the Clinic (QUANTEC) initiative. In recent years, medical modeling for both prognostic and therapeutic purposes has exploded thanks to increasing availability of electronic data and genomics. One promising direction that medical modeling is moving toward is adopting the same machine learning methods used by companies such as Google and Facebook to combat disease. Broadly defined, machine learning is a branch of computer science that deals with making predictions from complex data through statistical models. These methods serve to uncover patterns in data and are actively used in areas such as speech recognition, handwriting recognition, face recognition, “spam” filtering (junk email), and targeted advertising. Although multiple radiation oncology research groups have shown the value of applied machine learning (ML), clinical adoption has been slow due to the high barrier to understanding these complex models by clinicians. Here, we present a review of the use of ML to predict radiation therapy outcomes from the clinician's point of view with the hope that it lowers the “barrier to entry” for those without formal training in ML. We begin by describing 7 principles that one should consider when evaluating (or creating) an ML model in radiation oncology. We next introduce 3 popular ML methods—logistic regression (LR), support vector machine (SVM), and artificial neural network (ANN)—and critique 3 seminal papers in the context of these principles. Although current studies are in exploratory stages, the overall methodology has progressively matured, and the field is ready for larger-scale further investigation.

Experimental evaluation of optimization method for developing ultraviolet barrier coatings

Science.gov (United States)

Gonome, Hiroki; Okajima, Junnosuke; Komiya, Atsuki; Maruyama, Shigenao

2014-01-01

Ultraviolet (UV) barrier coatings can be used to protect many industrial products from UV attack. This study introduces a method of optimizing UV barrier coatings using pigment particles. The radiative properties of the pigment particles were evaluated theoretically, and the optimum particle size was decided from the absorption efficiency and the back-scattering efficiency. UV barrier coatings were prepared with zinc oxide (ZnO) and titanium dioxide (TiO2). The transmittance of the UV barrier coating was calculated theoretically. The radiative transfer in the UV barrier coating was modeled using the radiation element method by ray emission model (REM2). In order to validate the calculated results, the transmittances of these coatings were measured by a spectrophotometer. A UV barrier coating with a low UV transmittance and high VIS transmittance could be achieved. The calculated transmittance showed a similar spectral tendency with the measured one. The use of appropriate particles with optimum size, coating thickness and volume fraction will result in effective UV barrier coatings. UV barrier coatings can be achieved by the application of optical engineering.

The "1"2C("1"6O,γ"2"8Si) radiative capture reaction at sub-barrier energies

International Nuclear Information System (INIS)

Goasduff, A.; Courtin, S.; Haas, F.; Lebhertz, D.; Jenkins, D.G.; Fallis, J.; Ruiz, C.; Hutcheon, D.A.; Amandruz, P.A.; Davis, C.; Hager, U.; Ottewell, D.; Ruprecht, G.

2014-01-01

The heavy-ion radiative capture "1"2C("1"6O,γ"2"8Si) was measured at the sub-Coulomb barrier bombarding energy E(lab) = 15.7 MeV, which corresponds to the lowest important resonance observed in the "1"2C + "1"6O fusion excitation function. Thanks to combination of the bismuth germanate (BGO) γ-ray array and the 0 degree DRAGON electromagnetic spectrometer at TRIUMF, the γ-decay spectrum from the entrance channel down to the ground state of "2"8Si was measured. Comparisons of the experimental spectrum to γ spectrum extracted from Monte-Carlo simulations of the complete setup suggest a J"π = 2"+ spin-parity assignment to the entrance channel and yield the radiative capture cross section σ(RC) = 0.22 ± 0.04 μb. Combining this present spin assignment with previous data on radiative capture, a J (J + 1) systematics was constructed, and it indicated a moment of inertia commensurate with the "1"2C+"1"6O grazing angular momentum. Strong dipole transitions are observed from the entrance channel to T = 1 states around 11.5 MeV and are found to result from enhanced M1_I_V transitions to states exhausting a large part of the M1 sum rule built on the ground state of "2"8Si. This specific decay was also reported at bombarding energies close to the Coulomb barrier in our previous study of the "1"2C("1"2C,γ"2"4Mg) heavy-ion radiative capture reaction. Similarities between both systems are investigated. (authors)

Machine Learning Approaches for Predicting Radiation Therapy Outcomes: A Clinician's Perspective.

Science.gov (United States)

Kang, John; Schwartz, Russell; Flickinger, John; Beriwal, Sushil

2015-12-01

Radiation oncology has always been deeply rooted in modeling, from the early days of isoeffect curves to the contemporary Quantitative Analysis of Normal Tissue Effects in the Clinic (QUANTEC) initiative. In recent years, medical modeling for both prognostic and therapeutic purposes has exploded thanks to increasing availability of electronic data and genomics. One promising direction that medical modeling is moving toward is adopting the same machine learning methods used by companies such as Google and Facebook to combat disease. Broadly defined, machine learning is a branch of computer science that deals with making predictions from complex data through statistical models. These methods serve to uncover patterns in data and are actively used in areas such as speech recognition, handwriting recognition, face recognition, "spam" filtering (junk email), and targeted advertising. Although multiple radiation oncology research groups have shown the value of applied machine learning (ML), clinical adoption has been slow due to the high barrier to understanding these complex models by clinicians. Here, we present a review of the use of ML to predict radiation therapy outcomes from the clinician's point of view with the hope that it lowers the "barrier to entry" for those without formal training in ML. We begin by describing 7 principles that one should consider when evaluating (or creating) an ML model in radiation oncology. We next introduce 3 popular ML methods--logistic regression (LR), support vector machine (SVM), and artificial neural network (ANN)--and critique 3 seminal papers in the context of these principles. Although current studies are in exploratory stages, the overall methodology has progressively matured, and the field is ready for larger-scale further investigation. Copyright © 2015 Elsevier Inc. All rights reserved.

Maximum dose angle for oblique incidence on primary beam protective barriers in the design of medical radiation therapy facilities

International Nuclear Information System (INIS)

Fondevila, Damian; Arbiser, Silvio; Sansogne, Rosana; Brunetto, Monica; Dosoretz, Bernardo

2008-01-01

Primary barrier determinations for the shielding of medical radiation therapy facilities are generally made assuming normal beam incidence on the barrier, since this is geometrically the most unfavorable condition for that shielding barrier whenever the occupation line is allowed to run along the barrier. However, when the occupation line (for example, the wall of an adjacent building) runs perpendicular to the barrier (especially roof barrier), then two opposing factors come in to play: increasing obliquity angle with respect to the barrier increases the attenuation, while the distance to the calculation point decreases, hence, increasing the dose. As a result, there exists an angle (α max ) for which the equivalent dose results in a maximum, constituting the most unfavorable geometric condition for that shielding barrier. Based on the usual NCRP Report No. 151 model, this article presents a simple formula for obtaining α max , which is a function of the thickness of the barrier (t E ) and the equilibrium tenth-value layer (TVL e ) of the shielding material for the nominal energy of the beam. It can be seen that α max increases for increasing TVL e (hence, beam energy) and decreases for increasing t E , with a range of variation that goes from 13 to 40 deg for concrete barriers thicknesses in the range of 50-300 cm and most commercially available teletherapy machines. This parameter has not been calculated in the existing literature for radiotherapy facilities design and has practical applications, as in calculating the required unoccupied roof shielding for the protection of a nearby building located in the plane of the primary beam rotation

Maximum dose angle for oblique incidence on primary beam protective barriers in the design of medical radiation therapy facilities.

Science.gov (United States)

Fondevila, Damián; Arbiser, Silvio; Sansogne, Rosana; Brunetto, Mónica; Dosoretz, Bernardo

2008-05-01

Primary barrier determinations for the shielding of medical radiation therapy facilities are generally made assuming normal beam incidence on the barrier, since this is geometrically the most unfavorable condition for that shielding barrier whenever the occupation line is allowed to run along the barrier. However, when the occupation line (for example, the wall of an adjacent building) runs perpendicular to the barrier (especially roof barrier), then two opposing factors come in to play: increasing obliquity angle with respect to the barrier increases the attenuation, while the distance to the calculation point decreases, hence, increasing the dose. As a result, there exists an angle (alpha(max)) for which the equivalent dose results in a maximum, constituting the most unfavorable geometric condition for that shielding barrier. Based on the usual NCRP Report No. 151 model, this article presents a simple formula for obtaining alpha(max), which is a function of the thickness of the barrier (t(E)) and the equilibrium tenth-value layer (TVL(e)) of the shielding material for the nominal energy of the beam. It can be seen that alpha(max) increases for increasing TVL(e) (hence, beam energy) and decreases for increasing t(E), with a range of variation that goes from 13 to 40 deg for concrete barriers thicknesses in the range of 50-300 cm and most commercially available teletherapy machines. This parameter has not been calculated in the existing literature for radiotherapy facilities design and has practical applications, as in calculating the required unoccupied roof shielding for the protection of a nearby building located in the plane of the primary beam rotation.

Nuclear Safety and Radiation Protection in Europe - a common approach

International Nuclear Information System (INIS)

McGarry, Ann

2010-01-01

In Europe, the European Union has adopted directives and implemented other measures which form the basis of a common approach to nuclear safety and radiation protection across all Member States. In particular, there are EU directives setting out radiation protection standards and establishing a Community framework for the nuclear safety of nuclear installations. There are also arrangements in place to provide for an effective response to nuclear emergencies and to facilitate high quality research into nuclear and radiation protection related topics. Inevitably the stage of development in each area is somewhat different, but generally progress is ongoing in each area. From the point of view of a small country like Ireland, the development of common standards and arrangements across Europe is beneficial as they are based on the best available knowledge and expertise; they provide for greater transparency; they facilitate public confidence and make best use of the available resources. However, there are some areas in which common approaches could be further advanced. For example, the medical exposure of patients is increasingly of concern across Europe and the further development of common approaches in this area would be helpful. It would also be useful to develop a more integrated approach to nuclear safety and radiation protection regulation and to better integrate nuclear and radiation issues with other public health and environment concerns. (author)

Multiscale approach to the physics of radiation damage with ions

Energy Technology Data Exchange (ETDEWEB)

Surdutovich, Eugene [Physics Department, Oakland University, 2200 N. Squirrel Rd., Rochester MI 48309 (United States); Solov' yov, Andrey V. [Frankfurt Institute for Advanced Studies, Goethe University, Ruth-Moufang-Str. 1, Frankfurt am Main 60438 (Germany)

2013-04-19

We review a multiscale approach to the physics of ion-beam cancer therapy, an approach suggested in order to understand the interplay of a large number of phenomena involved in radiation damage scenario occurring on a range of temporal, spatial, and energy scales. We briefly overview its history and present the current stage of its development. The differences of the multiscale approach from other methods of understanding and assessment of radiation damage are discussed as well as its relationship to other branches of physics, chemistry and biology.

Large germinoma in basal ganglia treated by intraarterial chemotherapy with ACNU following osmotic blood-brain barrier disruption and radiation therapy

Energy Technology Data Exchange (ETDEWEB)

Miyagami, Mitsusuke; Tsubokawa, Takashi; Kobayashi, Makio.

1988-10-01

A rare case of large germinoma in the basal ganglia is reported which was effectively treated by intracarotid chemotherapy with ACNU following osmotic blood-brain barrier disruption using 20 % mannitol and radiation therapy. A 19-year-old man displayed slowly progressive right hemiparesis, motor aphasia and predementia on admission. Plain CT demonstrated a tumor which had a slightly high density with intratumoral calcification and a small cyst, and slight to moderate enhancement was observed following intravenous injection of contrast medium, but there was no unilateral ventricular enlargement. Cerebral angiography revealed hypervascular tumor staining with early draining veins. After biopsy, and as a result of intracarotid chemotherapy with ACNU following osmotic blood-brain barrier disruption and radiation therapy, the tumor decreased rapidly to about 20 % of its original mass. After discharge, tumor progression was observed. However, the enlarged tumor mass almost disappeared (except for calcification) on CT with clinical improvement in response to intracarotid chemotherapy with ACNU following 20 % mannitol.

Training in ionizing radiation metrology: a systematic approach

International Nuclear Information System (INIS)

Peixoto, J.G.P.; Sales, E.; Wieland, P.

2001-01-01

This paper presents the systematic approach to training applied to the determination of backscattering factor of the mammography radiation qualities implemented at LNMRI/IRD/CNEN. The strategy for training includes the procedures described at the IAEA Safety Reports Series 201, i.e. analysis, design, implementation and evaluation with feedback . The training included theoretical and practical classes on dosimetry tools, interaction of radiation with matter, radiation protection, laboratory rules, and measurements and uncertainty analysis. At the end the trainee presents a seminar to show the competency acquired and to improve the scientific communication skills. (author)

Magnetic Nanoparticles Cross the Blood-Brain Barrier: When Physics Rises to a Challenge

Directory of Open Access Journals (Sweden)

Maria Antònia Busquets

2015-12-01

Full Text Available The blood-brain barrier is a physical and physiological barrier that protects the brain from toxic substances within the bloodstream and helps maintain brain homeostasis. It also represents the main obstacle in the treatment of many diseases of the central nervous system. Among the different approaches employed to overcome this barrier, the use of nanoparticles as a tool to enhance delivery of therapeutic molecules to the brain is particularly promising. There is special interest in the use of magnetic nanoparticles, as their physical characteristics endow them with additional potentially useful properties. Following systemic administration, a magnetic field applied externally can mediate the capacity of magnetic nanoparticles to permeate the blood-brain barrier. Meanwhile, thermal energy released by magnetic nanoparticles under the influence of radiofrequency radiation can modulate blood-brain barrier integrity, increasing its permeability. In this review, we present the strategies that use magnetic nanoparticles, specifically iron oxide nanoparticles, to enhance drug delivery to the brain.

Influence of ionizing radiation and use of plasticizers on the mechanical properties and barrier properties of biodegradable films

International Nuclear Information System (INIS)

Ponce, Patricia; Parra, Duclerc F.; Carr, Laura G.; Sato, Juliana S.; Lugao, Ademar B.

2005-01-01

This work reports the influence of radiation and plasticizers on the barrier properties [water vapour permeability (WVP)] and mechanical properties (tensile strength and elongation) of edible films made of starch. These films were prepared with 4 g of starch/100 mL of water; 2-10 g polyethylene glycol (PEG)/100 g starch; and at natural pH. Tensile strength and percentage elongation were measured using a Mechanical Universal Testing Machine Instron 4400R and the water vapour permeability was determined according to ASTM E96-80 (ASTM, 1989). The mechanical properties of starch films are influenced by the plasticizer concentration. An increase in PEG content showed a considerable increase in elongation percentage and a decrease in the tensile strength of the films, also increase the permeability of the films in water. After irradiation, the barrier properties [water vapour permeability (WVP)] and mechanical properties (tensile strength and elongation) of the films were improved due to chemical reactions among polymer molecules. The films were irradiated at room temperature with gamma radiation. Irradiated starch cassava films with polyethylene glycol (PEG) as plasticizer have good flexibility and low water permeability, which indicate potential application as edible films (author)

Method of moments approach to pricing double barrier contracts in polynomial jump-diffusion models

NARCIS (Netherlands)

Eriksson, B.; Pistorius, M.

2011-01-01

Abstract: We present a method of moments approach to pricing double barrier contracts when the underlying is modelled by a polynomial jump-diffusion. By general principles the price is linked to certain infinite dimensional linear programming problems. Subsequently approximating these by finite

Influence of radiation on the blood-brain barrier and optimum time of chemotherapy

International Nuclear Information System (INIS)

Qin, D.X.; Zheng, R.; Tang, J.; Li, J.X.; Hu, Y.H.

1990-01-01

A pilot study of the destructive effects of radiation on the blood-brain barrier (BBB) was made on 14 patients with localized and limited brain tumors by 99MTc-GH imaging from August 1988 to November 1989. Count/pixel data were obtained from the unirradiated, irradiated, and tumor areas before and after radiotherapy of 30-40 Gy. It was observed that the BBB in the unirradiated area outside the radiation portal was not changed and the degree of destructive effect on the BBB in the irradiated normal area was directly proportional to the radiation dose. For 30-40 Gy, the count/pixel change enhances to average 24.7% [(147.6-118.4)/118.4], and (c) the BBB in the tumor area is partially destroyed on an average of 22.1% [(206.8-169.4)/169.4] by the tumor. The radiotherapy further enhances this effect to an average of 74.7% [(206.8-118.4)/118.4]. Case 3 showed that before radiation, the degree of destructive effect on the BBB in the tumor area was 22% [(167-137)/137] higher than normal brain tissue. After a dose of 30 Gy of irradiation, it increased to 76.7% [(242-137)/137]; 8 months later it decreased to 17% [(160.3-137)/137]. It has been proven that the BBB can recover at least partially. Based on these observations, the authors believe that in the combined treatment of operated brain tumors, radiotherapy should precede chemotherapy so as to enhance the destruction of the BBB, facilitating the incorporation of drugs into the tumor. The dose at which to start chemotherapy is 20-30 Gy

''In sutu'' radiation cleaning of underground water contaminated with cyanides - six years of experience

International Nuclear Information System (INIS)

Pastuszek, F.; Vacek, K.; Vondruska, V.

1993-01-01

Underground water, contaminated with cyanides, has been successfully cleaned using the hydraulic barrier method (assembly of pumped wells) since 1986. The average cyanide concentrations in the outflow exceeded 35 mg per litre. Contamination had to be eliminated before the discharge into the sewer system. The radiation approach ''in situ'' i.e. decomposition of cyanides by barrier, was applied and is still being used today. The cyanide concentration was lowered more than one order of magnitude. This process was approved by the Czechoslovak radiation security authorities and further applications of ''in situ'' regeneration of underground water contamination is anticipated. (author)

Risk approaches in setting radiation standards

International Nuclear Information System (INIS)

Whipple, C.

1984-01-01

This paper discusses efforts to increase the similarity of risk regulation approaches for radiation and chemical carcinogens. The risk assessment process in both cases involves the same controversy over the extrapolation from high to low doses and dose rates, and in both cases the boundaries between science and policy in risk assessment are indistinct. Three basic considerations are presented to approach policy questions: the economic efficiency of the regulatory approach, the degree of residual risk, and the technical opportunities for risk control. It is the author's opinion that if an agency can show that its standard-setting policies are consistent with those which have achieved political and judicial acceptance in other contexts, the greater the predictability of the regulatory process and the stability of this process

Accelerated regression of brain metastases in patients receiving whole brain radiation and the topoisomerase II inhibitor, lucanthone

International Nuclear Information System (INIS)

Rowe, John D. del; Bello, Jacqueline; Mitnick, Robin; Sood, Brij; Filippi, Christopher; Moran, Justin Ph.D.; Freeman, Katherine; Mendez, Frances; Bases, Robert

1999-01-01

Purpose: To determine if lucanthone crossed the blood-brain barrier in experimental animals; and to determine accelerated tumor regression of human brain metastases treated jointly with lucanthone and whole brain radiation. Methods and Materials: The organ distribution of 3 H lucanthone in mice and 125 I lucanthone in rats was determined to learn if lucanthone crossed the blood-brain barrier. Size determinations were made of patients' brain metastases from magnetic resonance images or by computed tomography before and after treatment with 30 Gy whole brain radiation alone or with lucanthone. Results: The time course of lucanthone's distribution in brain was identical to that in muscle and heart after intraperitoneal or intravenous administration in experimental animals. Lucanthone, therefore, readily crossed the blood-brain barrier in experimental animals. Conclusion: Compared with radiation alone, the tumor regression in patients with brain metastases treated with lucanthone and radiation was accelerated, approaching significance using a permutation test at p = 0.0536

Machine Learning Approaches for Predicting Radiation Therapy Outcomes: A Clinician's Perspective

Energy Technology Data Exchange (ETDEWEB)

Kang, John [Medical Scientist Training Program, University of Pittsburgh-Carnegie Mellon University, Pittsburgh, Pennsylvania (United States); Schwartz, Russell [Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania (United States); Flickinger, John [Departments of Radiation Oncology and Neurological Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania (United States); Beriwal, Sushil, E-mail: beriwals@upmc.edu [Department of Radiation Oncology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania (United States)

2015-12-01

Radiation oncology has always been deeply rooted in modeling, from the early days of isoeffect curves to the contemporary Quantitative Analysis of Normal Tissue Effects in the Clinic (QUANTEC) initiative. In recent years, medical modeling for both prognostic and therapeutic purposes has exploded thanks to increasing availability of electronic data and genomics. One promising direction that medical modeling is moving toward is adopting the same machine learning methods used by companies such as Google and Facebook to combat disease. Broadly defined, machine learning is a branch of computer science that deals with making predictions from complex data through statistical models. These methods serve to uncover patterns in data and are actively used in areas such as speech recognition, handwriting recognition, face recognition, “spam” filtering (junk email), and targeted advertising. Although multiple radiation oncology research groups have shown the value of applied machine learning (ML), clinical adoption has been slow due to the high barrier to understanding these complex models by clinicians. Here, we present a review of the use of ML to predict radiation therapy outcomes from the clinician's point of view with the hope that it lowers the “barrier to entry” for those without formal training in ML. We begin by describing 7 principles that one should consider when evaluating (or creating) an ML model in radiation oncology. We next introduce 3 popular ML methods—logistic regression (LR), support vector machine (SVM), and artificial neural network (ANN)—and critique 3 seminal papers in the context of these principles. Although current studies are in exploratory stages, the overall methodology has progressively matured, and the field is ready for larger-scale further investigation.

Barriers to Low Vision Rehabilitation: A Qualitative Approach

Science.gov (United States)

Southall, Kenneth; Wittich, Walter

2012-01-01

Introduction: This study sought to describe and better understand barriers to accessing low vision rehabilitation services. Methods: A qualitative description research paradigm was employed. Focus group participants were recruited through their involvement in the Montreal Barriers Study in Montreal, Canada. Six focus groups (n = 21 participants)…

Identifying and prioritizing barriers to implementation of smart energy city projects in Europe: An empirical approach

International Nuclear Information System (INIS)

Mosannenzadeh, Farnaz; Di Nucci, Maria Rosaria; Vettorato, Daniele

2017-01-01

Successful implementation of smart energy city projects in Europe is crucial for a sustainable transition of urban energy systems and the improvement of quality of life for citizens. We aim to develop a systematic classification and analysis of the barriers hindering successful implementation of smart energy city projects. Through an empirical approach, we investigated 43 communities implementing smart and sustainable energy city projects under the Sixth and Seventh Framework Programmes of the European Union. Validated through literature review, we identified 35 barriers categorized in policy, administrative, legal, financial, market, environmental, technical, social, and information-and-awareness dimensions. We prioritized these barriers, using a novel multi-dimensional methodology that simultaneously analyses barriers based on frequency, level of impact, causal relationship among barriers, origin, and scale. The results indicate that the key barriers are lacking or fragmented political support on the long term at the policy level, and lack of good cooperation and acceptance among project partners, insufficient external financial support, lack of skilled and trained personnel, and fragmented ownership at the project level. The outcome of the research should aid policy-makers to better understand and prioritize implementation barriers to develop effective action and policy interventions towards more successful implementation of smart energy city projects. - Highlights: • A solid empirical study on the implementation of European smart energy city projects. • We found 35 barriers in nine dimensions; e.g. policy, legal, financial, and social. • We suggested a new multi-dimensional methodology to prioritize barriers. • Lacking or fragmented political support on the long term is a key barrier. • We provided insights for action for project coordinators and policy makers.

Alternative approaches to reliability modeling of a multiple engineered barrier system

International Nuclear Information System (INIS)

Ananda, M.M.A.; Singh, A.K.

1994-01-01

The lifetime of the engineered barrier system used for containment of high-level radioactive waste will significantly impact the total performance of a geological repository facility. Currently two types of designs are under consideration for an engineered barrier system, single engineered barrier system and multiple engineered barrier system. Multiple engineered barrier system consists of several metal barriers and the waste form (cladding). Some recent work show that a significant improvement of performance can be achieved by utilizing multiple engineered barrier systems. Considering sequential failures for each barrier, we model the reliability of the multiple engineered barrier system. Weibull and exponential lifetime distributions are used through out the analysis. Furthermore, the number of failed engineered barrier systems in a repository at a given time is modeled using a poisson approximation

MO-D-213-07: RadShield: Semi- Automated Calculation of Air Kerma Rate and Barrier Thickness

International Nuclear Information System (INIS)

DeLorenzo, M; Wu, D; Rutel, I; Yang, K

2015-01-01

Purpose: To develop the first Java-based semi-automated calculation program intended to aid professional radiation shielding design. Air-kerma rate and barrier thickness calculations are performed by implementing NCRP Report 147 formalism into a Graphical User Interface (GUI). The ultimate aim of this newly created software package is to reduce errors and improve radiographic and fluoroscopic room designs over manual approaches. Methods: Floor plans are first imported as images into the RadShield software program. These plans serve as templates for drawing barriers, occupied regions and x-ray tube locations. We have implemented sub-GUIs that allow the specification in regions and equipment for occupancy factors, design goals, number of patients, primary beam directions, source-to-patient distances and workload distributions. Once the user enters the above parameters, the program automatically calculates air-kerma rate at sampled points beyond all barriers. For each sample point, a corresponding minimum barrier thickness is calculated to meet the design goal. RadShield allows control over preshielding, sample point location and material types. Results: A functional GUI package was developed and tested. Examination of sample walls and source distributions yields a maximum percent difference of less than 0.1% between hand-calculated air-kerma rates and RadShield. Conclusion: The initial results demonstrated that RadShield calculates air-kerma rates and required barrier thicknesses with reliable accuracy and can be used to make radiation shielding design more efficient and accurate. This newly developed approach differs from conventional calculation methods in that it finds air-kerma rates and thickness requirements for many points outside the barriers, stores the information and selects the largest value needed to comply with NCRP Report 147 design goals. Floor plans, parameters, designs and reports can be saved and accessed later for modification and recalculation

MO-D-213-07: RadShield: Semi- Automated Calculation of Air Kerma Rate and Barrier Thickness

Energy Technology Data Exchange (ETDEWEB)

DeLorenzo, M [Oklahoma University Health Sciences Center, Oklahoma City, OK (United States); Wu, D [University of Oklahoma Health Sciences Center, Oklahoma City, Ok (United States); Rutel, I [University of Oklahoma Health Science Center, Oklahoma City, OK (United States); Yang, K [Massachusetts General Hospital, Boston, MA (United States)

2015-06-15

Purpose: To develop the first Java-based semi-automated calculation program intended to aid professional radiation shielding design. Air-kerma rate and barrier thickness calculations are performed by implementing NCRP Report 147 formalism into a Graphical User Interface (GUI). The ultimate aim of this newly created software package is to reduce errors and improve radiographic and fluoroscopic room designs over manual approaches. Methods: Floor plans are first imported as images into the RadShield software program. These plans serve as templates for drawing barriers, occupied regions and x-ray tube locations. We have implemented sub-GUIs that allow the specification in regions and equipment for occupancy factors, design goals, number of patients, primary beam directions, source-to-patient distances and workload distributions. Once the user enters the above parameters, the program automatically calculates air-kerma rate at sampled points beyond all barriers. For each sample point, a corresponding minimum barrier thickness is calculated to meet the design goal. RadShield allows control over preshielding, sample point location and material types. Results: A functional GUI package was developed and tested. Examination of sample walls and source distributions yields a maximum percent difference of less than 0.1% between hand-calculated air-kerma rates and RadShield. Conclusion: The initial results demonstrated that RadShield calculates air-kerma rates and required barrier thicknesses with reliable accuracy and can be used to make radiation shielding design more efficient and accurate. This newly developed approach differs from conventional calculation methods in that it finds air-kerma rates and thickness requirements for many points outside the barriers, stores the information and selects the largest value needed to comply with NCRP Report 147 design goals. Floor plans, parameters, designs and reports can be saved and accessed later for modification and recalculation

Impurity transport in internal transport barrier discharges on JET

International Nuclear Information System (INIS)

Dux, R.

2002-01-01

In JET plasmas with internal transport barrier (ITB) the behaviour of metallic and low-Z impurities (C, Ne) was investigated. In ITB discharges with reversed shear, the metallic impurities accumulate in cases with too strong peaking of the density profile, while the concentration of low-Z elements C and Ne is only mildly peaked. The accumulation might be so strong, that the central radiation approximately equals the central heating power followed by a radiative collapse of the transport barrier. The radial location with strong impurity gradients (convective barrier) was identified to be situated inside (not at!) the heat flux barrier. Calculations of neo-classical transport were performed for these discharges, including impurity-impurity collisions. It was found, that the observed Z-dependence of the impurity peaking and the location of the impurity 'barrier' can be explained with neo-classical transport. ITB discharges with monotonic shear show less inward convection and seem to be advantageous with respect to plasma purity. (author)

Multiscale approach to the physics of radiation damage with ions

International Nuclear Information System (INIS)

Surdutovich, E.; Solov'yov, A.

2014-01-01

The multiscale approach to the assessment of bio-damage resulting upon irradiation of biological media with ions is reviewed, explained and compared to other approaches. The processes of ion propagation in the medium concurrent with ionization and excitation of molecules, transport of secondary products, dynamics of the medium, and biological damage take place on a number of different temporal, spatial and energy scales. The multiscale approach, a physical phenomenon-based analysis of the scenario that leads to radiation damage, has been designed to consider all relevant effects on a variety of scales and develop an approach to the quantitative assessment of biological damage as a result of irradiation with ions. Presently, physical and chemical effects are included in the scenario while the biological effects such as DNA repair are only mentioned. This paper explains the scenario of radiation damage with ions, overviews its major parts, and applies the multiscale approach to different experimental conditions. On the basis of this experience, the recipe for application of the multiscale approach is formulated. The recipe leads to the calculation of relative biological effectiveness. (authors)

Radiation protection/shield design: a need for a systems approach

International Nuclear Information System (INIS)

Disney, R.K.

1977-01-01

Radiation protection/shielding design of a nuclear facility requires a coordinated effort of many engineering disciplines to meet the requirements imposed by regulations. The system approach to Clinch River Breeder Reactor Plant (CRBRP) radiation protection is described, and the program developed to implement this approach is defined. In addition, the principal shielding design problems for LMFBR nuclear reactor systems are discussed in relation to LWR nuclear reactor system shielding designs. The methodology used to analyze these problems in the U.S. LMFBR program, the resultant design solutions, and the experimental verification of these designs and/or methods are discussed

Overview Of The U.S. Department Of Energy And Nuclear Regulatory Commission Performance Assessment Approaches: Cementitious Barriers Partnership

International Nuclear Information System (INIS)

Langton, C.; Burns, H.

2009-01-01

Engineered barriers including cementitious barriers are used at sites disposing or contaminated with low-level radioactive waste to enhance performance of the natural environment with respect to controlling the potential spread of contaminants. Drivers for using cementitious barriers include: high radionuclide inventory, radionuclide characteristics (e.g., long half-live, high mobility due to chemical form/speciation, waste matrix properties, shallow water table, and humid climate that provides water for leaching the waste). This document comprises the first in a series of reports being prepared for the Cementitious Barriers Partnership. The document is divided into two parts which provide a summary of: (1) existing experience in the assessment of performance of cementitious materials used for radioactive waste management and disposal and (2) sensitivity and uncertainty analysis approaches that have been applied for assessments. Each chapter is organized into five parts: Introduction, Regulatory Considerations, Specific Examples, Summary of Modeling Approaches and Conclusions and Needs. The objective of the report is to provide perspective on the state of the practice for conducting assessments for facilities involving cementitious barriers and to identify opportunities for improvements to the existing approaches. Examples are provided in two contexts: (1) performance assessments conducted for waste disposal facilities and (2) performance assessment-like analyses (e.g., risk assessments) conducted under other regulatory regimes. The introductory sections of each section provide a perspective on the purpose of performance assessments and different roles of cementitious materials for radioactive waste management. Significant experience with assessments of cementitious materials associated with radioactive waste disposal concepts exists in the US Department of Energy Complex and the commercial nuclear sector. Recently, the desire to close legacy facilities has created

OVERVIEW OF THE U.S. DEPARTMENT OF ENERGY AND NUCLEAR REGULATORY COMMISSION PERFORMANCE ASSESSMENT APPROACHES: CEMENTITIOUS BARRIERS PARTNERSHIP

Energy Technology Data Exchange (ETDEWEB)

Langton, C.; Burns, H.

2009-05-29

Engineered barriers including cementitious barriers are used at sites disposing or contaminated with low-level radioactive waste to enhance performance of the natural environment with respect to controlling the potential spread of contaminants. Drivers for using cementitious barriers include: high radionuclide inventory, radionuclide characteristics (e.g., long half-live, high mobility due to chemical form/speciation, waste matrix properties, shallow water table, and humid climate that provides water for leaching the waste). This document comprises the first in a series of reports being prepared for the Cementitious Barriers Partnership. The document is divided into two parts which provide a summary of: (1) existing experience in the assessment of performance of cementitious materials used for radioactive waste management and disposal and (2) sensitivity and uncertainty analysis approaches that have been applied for assessments. Each chapter is organized into five parts: Introduction, Regulatory Considerations, Specific Examples, Summary of Modeling Approaches and Conclusions and Needs. The objective of the report is to provide perspective on the state of the practice for conducting assessments for facilities involving cementitious barriers and to identify opportunities for improvements to the existing approaches. Examples are provided in two contexts: (1) performance assessments conducted for waste disposal facilities and (2) performance assessment-like analyses (e.g., risk assessments) conducted under other regulatory regimes. The introductory sections of each section provide a perspective on the purpose of performance assessments and different roles of cementitious materials for radioactive waste management. Significant experience with assessments of cementitious materials associated with radioactive waste disposal concepts exists in the US Department of Energy Complex and the commercial nuclear sector. Recently, the desire to close legacy facilities has created

Approaches to formalization of the informal waste sector into municipal solid waste management systems in low- and middle-income countries: Review of barriers and success factors.

Science.gov (United States)

Aparcana, Sandra

2017-03-01

The Municipal Solid Waste Management (MSWM) sector represents a major challenge for low-and middle-income countries due to significant environmental and socioeconomic issues involving rapid urbanization, their MSWM systems, and the existence of the informal waste sector. Recognizing its role, several countries have implemented various formalization measures, aiming to address the social problems linked to this sector. However, regardless of these initiatives, not all attempts at formalization have proved successful due to the existence of barriers preventing their implementation in the long term. Along with this, there is a frequent lack of knowledge or understanding regarding these barriers and the kind of measures that may enable formalization, thereby attaining a win-win situation for all the stakeholders involved. In this context, policy- and decision-makers in the public and private sectors are frequently confronted with the dilemma of finding workable approaches to formalization, adjusted to their particular MSWM contexts. Building on the review of frequently implemented approaches to formalization, including an analysis of the barriers to and enabling measures for formalization, this paper aims to address this gap by explaining to policy- and decision-makers, and to waste managers in the private sector, certain dynamics that can be observed and that should be taken into account when designing formalization strategies that are adapted to their particular socioeconomic and political-institutional context. This includes possible links between formalization approaches and barriers, the kinds of barriers that need to be removed, and enabling measures leading to successful formalization in the long term. This paper involved a literature review of common approaches to formalization, which were classified into three categories: (1) informal waste workers organized in associations or cooperatives; (2) organized in CBOs or MSEs; and (3) contracted as individual

The Employers' Perspective on Barriers and Facilitators to Employment of People with Intellectual Disability: A Differential Mixed-Method Approach

Science.gov (United States)

Kocman, Andreas; Fischer, Linda; Weber, Germain

2018-01-01

Background: Obtaining employment is among the most important ambitions of people with intellectual disability. Progress towards comprehensive inclusive employment is hampered by numerous barriers. Limited research is available on these barriers and strategies to overcome them. Method: A mixed method approach in a sample of 30 HR-managers was used…

Photochemical approach to high-barrier films for the encapsulation of flexible laminary electronic devices

Energy Technology Data Exchange (ETDEWEB)

Prager, L., E-mail: lutz.prager@iom-leipzig.de [Leibniz-Institut für Oberflächenmodifizierung e.V., Permoserstr. 15, 04318 Leipzig (Germany); Helmstedt, U. [Leibniz-Institut für Oberflächenmodifizierung e.V., Permoserstr. 15, 04318 Leipzig (Germany); Herrnberger, H. [Solarion AG, Pereser Höhe 1, Breitscheidstraße 45, 04442 Zwenkau (Germany); Kahle, O. [Fraunhofer-Einrichtung für Polymermaterialien und Composite PYCO, Kantstraße 55, 14513 Teltow (Germany); Kita, F. [AZ Electronic Materials Germany GmbH, Rheingaustraße 190-196, 65203 Wiesbaden (Germany); Münch, M. [Solarion AG, Pereser Höhe 1, Breitscheidstraße 45, 04442 Zwenkau (Germany); Pender, A.; Prager, A.; Gerlach, J.W. [Leibniz-Institut für Oberflächenmodifizierung e.V., Permoserstr. 15, 04318 Leipzig (Germany); Stasiak, M. [Fraunhofer-Einrichtung für Polymermaterialien und Composite PYCO, Kantstraße 55, 14513 Teltow (Germany)

2014-11-03

Based on results of preceding research and development, thin gas barriers were made by wet application of perhydropolysilazane solution onto polymer films and its subsequent photo-initiated conversion to dense silica layers applying vacuum ultraviolet irradiation. Compared to the state of the art, these layers were sufficiently improved and characterized by spectroscopic methods, by scanning electron microscopy and by gas permeation measurements. Water vapor transmission rates (WVTR) below 10{sup −2} g m{sup −2} d{sup −1} were achieved. In this way, single barrier films were developed and produced on a pilot plant from roll to roll, 250 mm wide, at speeds up to 10 m min{sup −1}. Two films were laminated using adhesives curable with ultraviolet (UV) light and evaluated by peel tests, gas permeation measurement and climate testing. It could be shown that the described high-barrier laminates which exhibit WVTR ≈ 5 × 10{sup −4} g m{sup −2} d{sup −1}, determined by the calcium mirror method, are suitable for encapsulation of flexible thin-film photovoltaic modules. Durability of the encapsulated modules could be verified in several climate tests including damp-heat, thermo-cycle (heating, freezing, wetting) and UV exposures which are equivalent to more than 20 years of endurance at outdoor conditions in temperate climate. In the frame of further research and technical development it seems to be possible to design a cost efficient industrial scale process for the production of encapsulation films for photovoltaic applications. - Highlights: • Dense silica barrier layers were developed by a photochemical approach. • Polymer based barrier films were laminated yielding flexible high-barrier films. • Using these laminates photovoltaic test modules were encapsulated and tested. • A durability of more than 20 years at outdoor conditions could be proved.

Air barrier systems: Construction applications

Energy Technology Data Exchange (ETDEWEB)

Perrault, J.C

1989-01-01

An examination is presented of how ordinary building materials can be used in an innovative manner to design, detail, and construct effective air barrier systems for common types of walls. For residential construction, the air drywall approach uses the interior gypsum board as the main component of the wall air barrier system. Joints between the gypsum board and adjacent materials or assemblies are sealed by gaskets. In commercial construction, two different techniques are employed for using gypsum board as air barrier material: the accessible drywall and non-accessible drywall approaches. The former is similar to the air drywall approach except that high performance sealants are used instead of gaskets. In the latter approach, exterior drywall sheathing is the main component of the air barrier system; joints between boards are taped and joints between boards and other components are sealed using elastomeric membrane strips. For various types of commercial and institutional buildings, metal air barrier systems are widely used and include pre-engineered curtain walls or sheet metal walls. Masonry wall systems are regarded as still the most durable, fireproof, and soundproof wall type available but an effective air barrier system has typically been difficult to implement. Factory-made elastomeric membranes offer the potential to provide airtightness to masonry walls. These membranes are applied on the entire masonry wall surface and are used to make airtight connections with other building components. Two types of product are available: thermofusible and peel-and-stick membranes. 5 figs.

A fuzzy regression with support vector machine approach to the estimation of horizontal global solar radiation

International Nuclear Information System (INIS)

Baser, Furkan; Demirhan, Haydar

2017-01-01

Accurate estimation of the amount of horizontal global solar radiation for a particular field is an important input for decision processes in solar radiation investments. In this article, we focus on the estimation of yearly mean daily horizontal global solar radiation by using an approach that utilizes fuzzy regression functions with support vector machine (FRF-SVM). This approach is not seriously affected by outlier observations and does not suffer from the over-fitting problem. To demonstrate the utility of the FRF-SVM approach in the estimation of horizontal global solar radiation, we conduct an empirical study over a dataset collected in Turkey and applied the FRF-SVM approach with several kernel functions. Then, we compare the estimation accuracy of the FRF-SVM approach to an adaptive neuro-fuzzy system and a coplot supported-genetic programming approach. We observe that the FRF-SVM approach with a Gaussian kernel function is not affected by both outliers and over-fitting problem and gives the most accurate estimates of horizontal global solar radiation among the applied approaches. Consequently, the use of hybrid fuzzy functions and support vector machine approaches is found beneficial in long-term forecasting of horizontal global solar radiation over a region with complex climatic and terrestrial characteristics. - Highlights: • A fuzzy regression functions with support vector machines approach is proposed. • The approach is robust against outlier observations and over-fitting problem. • Estimation accuracy of the model is superior to several existent alternatives. • A new solar radiation estimation model is proposed for the region of Turkey. • The model is useful under complex terrestrial and climatic conditions.

Permeable Reactive Barriers: a multidisciplinary approach of a new emerging sustainable groundwater treatment technology

Energy Technology Data Exchange (ETDEWEB)

Diels, L.; Bastiaens, L. [Vito, Mol (BL); O' Hannessin, S. [EnviroMetal Technologies Inc., Ontario (Canada); Cortina, J.L. [Univ. Politecnica de Catalunya, Barcelona (Spain). Dept. d' Enginyeria Quimica; Alvarez, P.J. [Univ. of Iowa, Iowa-City (United States). Center for Biocatalysis and Bioprocessing; Ebert, M. [Christian-Albrechts Univ. Kiel (Germany). Inst. fuer Geowissenschaften; Schad, H. [I.M.E.S. GmbH, Amtzell (Germany)

2003-07-01

Permeable reactive barriers or zones are becoming an interesting sustainable and cost-effective technology for in situ treatment of contaminated groundwater. The technology is based on chemical processes as the dehalogenating activity of zerovalent iron, biological processes in bioscreens or reactive zones and on sorption technology (e.g. heavy metal adsorption or adsorption on granular activated carbon). Three technical sessions will be devoted to this nowadays becoming mature technology. This special session intends to pay attention to the discussion about some questions related to PRBs. These include the sustainability (e.g. life time and clogging) especially for zerovalent iron barriers, the need and quality of feasibility tests, drawbacks and restrictions of PRBs. Combined with long term performance monitoring os these systems will be discussed. Further attention will be paid to cost evaluation and the relationship between zerovalent barriers and bacterial growth. Also attention will be paid to new reactive materials (e.g. activated carbon for organics and inorganic materials for heavy metals) and consequences (e.g. environmental impact). Finally the session will combine al these approaches in a discussion about combined barriers or multibarriers for treatment of mixed pollution (e.g. landfill leachates contaminated groundwater). Specialists involved in these subjects will introduce these topics and allow for a large and intensive discussion to improve future applications of this technology. (orig.)

A novel approach for barriers to industrial energy efficiency

NARCIS (Netherlands)

Cagno, E.; Worrell, E.; Trianni, A.; Pugliese, G.

2013-01-01

A critical review of the literature highlighted the need for a new taxonomy encompassing the most relevant barriers stemmed from previous studies, and accounting for interactions and independences of the barriers to avoid overlaps and implicit interactions. Based on an extensive literature review

Promising approaches to circumvent the blood-brain barrier: progress, pitfalls and clinical prospects in brain cancer

OpenAIRE

Papademetriou, Iason T; Porter, Tyrone

2015-01-01

Brain drug delivery is a major challenge for therapy of central nervous system (CNS) diseases. Biochemical modifications of drugs or drug nanocarriers, methods of local delivery, and blood–brain barrier (BBB) disruption with focused ultrasound and microbubbles are promising approaches which enhance transport or bypass the BBB. These approaches are discussed in the context of brain cancer as an example in CNS drug development. Targeting to receptors enabling transport across the BBB offers non...

Approaches for protection standards for ionizing radiation and combustion pollutants

International Nuclear Information System (INIS)

Butler, G.C.

1978-01-01

The question ''can the approach used for radiation protection standards, i.e., to extrapolate dose--response relationships to low doses, be applied to combustion pollutants'' provided a basis for discussion. The linear, nonthreshold model postulated by ICRP and UNSCEAR for late effects of ionizing radiation is described and discussed. The utility and problems of applying this model to the effects of air pollutants constitute the focus of this paper. The conclusion is that, in the absence of evidence to the contrary, one should assume the same type of dose--effect relation for chemical air pollutants as for ionizing radiation

Semiclassical and quantum-electrodynamical approaches in nonrelativistic radiation theory

International Nuclear Information System (INIS)

Milonni, P.W.

1976-01-01

Theoretical aspects of the interaction of atoms with the radiation field are reviewed with emphasis on those features of the interaction requiring field quantization. The approach is nonrelativistic, with special attention given to the theory of spontaneous emission. (Auth.)

Teaching about radioactivity and ionising radiation: an alternative approach

International Nuclear Information System (INIS)

Millar, R.; Klaassen, K.; Eijkelhof, H.

1990-01-01

This article reviews children's ideas about radiation and radioactivity and identifies several common areas of misunderstanding. A new approach to teaching the topic at school level, which seeks specifically to address these known difficulties, is then proposed and outlined. (author)

BENCHMARKING THE INTERACTIONS AMONG BARRIERS IN DAIRY SUPPLY CHAIN: AN ISM APPROACH

Directory of Open Access Journals (Sweden)

Rahul S Mor

2018-06-01

Full Text Available The purpose of this paper is to explore the key barriers in dairy supply chain and to analyze their interactions in the context of Indian dairy industry. A total of eight barriers have been identified through literature review and the opinions of an expert team consisting of managerial and technical experts from dairy industry and academics. A questionnaire has been developed for identified barriers and responses were collected from select dairy industries located at northern India. Interpretive structure modeling (ISM is used to analyze the interactions among barriers and to propose a structural model. Further, the importance of barriers is determined based on their driving and dependence power using MICMAC analysis. The ISM-based model allocates to 'traceability, unbalanced production line, over-processing' as key barriers, 'wastages and high production downtime' comes next. MICMAC analysis depicts one autonomous barrier, one dependent barrier and six linkage barriers. The ISM-based model and MICMAC analysis will support the decision makers in dairy industry for planning their supply chain activities in an efficient way by managing the identified barriers.

Patient radiation exposure in right versus left trans-radial approach for coronary procedures

Energy Technology Data Exchange (ETDEWEB)

Rigattieri, Stefano; Di Russo, Cristian; Cera, Maria; Fedele, Silvio; Sciahbasi, Alessandro [Interventional Cardiology Unit, Sandro Pertini Hospital, Rome (Italy); Pugliese, Francesco Rocco [Emergency Department Sandro Pertini Hospital, Rome (Italy)

2015-01-15

Objectives: The aim of this study was to compare radiation exposure, assessed by dose-area product (DAP), in right trans-radial approach (RR) versus left trans-radial approach (LR) for coronary procedures. Background: In LR the catheter course is more similar to trans-femoral approach, thus allowing an easier negotiation of coronary ostia which, in turn, might translate into reduced fluoroscopy time (FT) and radiation exposure as compared to RR. Methods: We retrospectively selected diagnostic and interventional procedures (PCI) performed by RR or LR at our center from May 2009 to May 2014. We only included in the analysis the procedures in which DAP values were available. Results: We analyzed 1464 procedures, 1175 of which performed by RR (80.3%) and 289 by LR (19.7%). Median DAP values were significantly higher in RR as compared to LR for diagnostic and interventional procedures (4482 vs. 3540 cGy.cm{sup 2} and 11523 vs. 10086 cGy.cm{sup 2}, respectively; p < 0.05). No significant differences were observed in FT and in contrast volume (CV). In the propensity-matched cohort, consisting of 269 procedures for each group, no significant differences between LR and RR were observed in median DAP values for both diagnostic and interventional procedures (3990 vs. 3542 cGy.cm{sup 2} and 9964 vs. 10216 cGy.cm{sup 2}, respectively; p = ns); FT and CV were also similar. At multiple linear regression analysis laterality of trans-radial approach was not associated with DAP. Conclusions: In an experienced trans-radial center LR is not associated with a reduction in radiation exposure, FT or CV as compared to RR. - Highlights: • Right trans-radial approach is by far more commonly used than left trans-radial approach. • Left trans-radial approach has the advantage of an easier catheter manipulation, more similar to trans-femoral approach. • This could reduce fluoroscopy time and radiation exposure. • We conducted a retrospective study to investigate patient radiation

Environmental Radiation Effects on Mammals A Dynamical Modeling Approach

CERN Document Server

Smirnova, Olga A

2010-01-01

This text is devoted to the theoretical studies of radiation effects on mammals. It uses the framework of developed deterministic mathematical models to investigate the effects of both acute and chronic irradiation in a wide range of doses and dose rates on vital body systems including hematopoiesis, small intestine and humoral immunity, as well as on the development of autoimmune diseases. Thus, these models can contribute to the development of the system and quantitative approaches in radiation biology and ecology. This text is also of practical use. Its modeling studies of the dynamics of granulocytopoiesis and thrombocytopoiesis in humans testify to the efficiency of employment of the developed models in the investigation and prediction of radiation effects on these hematopoietic lines. These models, as well as the properly identified models of other vital body systems, could provide a better understanding of the radiation risks to health. The modeling predictions will enable the implementation of more ef...

Markovian approach: From Ising model to stochastic radiative transfer

International Nuclear Information System (INIS)

Kassianov, E.; Veron, D.

2009-01-01

The origin of the Markovian approach can be traced back to 1906; however, it gained explicit recognition in the last few decades. This overview outlines some important applications of the Markovian approach, which illustrate its immense prestige, respect, and success. These applications include examples in the statistical physics, astronomy, mathematics, computational science and the stochastic transport problem. In particular, the overview highlights important contributions made by Pomraning and Titov to the neutron and radiation transport theory in a stochastic medium with homogeneous statistics. Using simple probabilistic assumptions (Markovian approximation), they have introduced a simplified, but quite realistic, representation of the neutron/radiation transfer through a two-component discrete stochastic mixture. New concepts and methodologies introduced by these two distinguished scientists allow us to generalize the Markovian treatment to the stochastic medium with inhomogeneous statistics and demonstrate its improved predictive performance for the down-welling shortwave fluxes. (authors)

Assessment of radiation emitted by the colour video monitors using a silicon surface-barrier detection system

International Nuclear Information System (INIS)

Tykva, R.; Sabol, J.

1998-01-01

About 5% of the commonly used colour monitors tested showed radiation levels on the screen surface approaching the dose rate of 5 μGy/h. There is practically no difference between 'low radiation' monitors and other monitors. The level of radiation emitted to the sides is generally higher than that of X-ray photons emerging from the surface of the screen. Although the contribution to the effective dose of a person exposed to radiation from the monitors may be below the limit set for the general public, the skin and eye lens dose may reach significant levels, taking into account some factors such as a high density of monitors in small rooms, short distance, long exposure time, etc. (M.D.)

Test and evaluation of semiconductor components in mixed field radiation monitoring

International Nuclear Information System (INIS)

Cardenas, Jose Patricio N.; Madi Filho, Tufic; Rodrigues, Leticia L.C.

2009-01-01

Silicon components have found extensive use in nuclear spectroscopy and counting, as described in many articles in the last three decades. These devices have found utility in radiation dosimetry because a diode, for instance, produces a current approximately 18000 times higher than any ionization chamber of equal sensitive volume. This reduces stringent requirements from the electronics used to amplify or integrate the current and / or allows approaching the ideal detector point for the mapping of radiation fields. For better performance, in the case of diodes, they are normally used with high inverse polarity to obtain a deeper barrier, less noise and shorter transit time. The aim of this work was the evaluation of these semiconductor components for application in ionizing radiation fields monitoring, in nuclear research reactors and radiotherapy facilities, for radiation protection and health physics purposes. Experimental configurations to analyze the performance of commercial semiconductors, such as silicon PIN Photodiodes and Silicon Surface Barrier Detectors, were developed and the performance of three different configurations of charge preamplifier with silicon components was also studied. Components were evaluated for application as neutron detectors, using some types of radiators (converters). The radiation response of these silicon components to neutron fields from nuclear research reactors IEA-R1 and IPEN-MB1 (thermal, epithermal and fast neutrons), from beam holes, experimental halls and AmBe neutron sources in laboratory was investigated. (author)

Advanced house air-barrier systems

Energy Technology Data Exchange (ETDEWEB)

Lee, R.K. [Natural Resources Canada, Ottawa, ON (Canada)

1996-08-01

Air barrier systems used in modern Canadian airtight homes were discussed. The Advanced Houses Program sets its airtightness requirements at 1.5 air changes per hour at 50 Pascals pressure difference (ACH{sub 5}0). In recent tests of 10 houses, it was suggested that a better airtightness level was attainable with average airtightness of about 1.0 ACH{sub 5}0. Six of the homes tested did not use the traditional polyethylene approach. Two of the houses used the airtight drywall approach, one used a foam system, and three used exterior air barriers. The advantages and disadvantages of each system was described, including cost effectiveness, cost reduction, performance and installation advantages. The confusion between an air barrier and a vapour diffusion retarder was explained. Exterior air barriers showed the greatest potential for meeting airtightness requirements at reasonable cost. 5 refs., 3 tabs.

The impact of farmers’ participation in field trials in creating awareness and stimulating compliance with the World Health Organization’s farm-based multiple-barrier approach

DEFF Research Database (Denmark)

Amponsah, Owusu; Vigre, Håkan; Schou, Torben Wilde

2016-01-01

-barrier approach field trials. The results of the study show that participation in the field trials has statistically significant effects on farmers’ awareness of the farm-based multiple-barrier approach. Compliance has, however, been undermined by the farmers’ perception that the cost of compliance is more......The results of a study aimed as assessing the extent to which urban vegetable farmers’ participation in field trials can impact on their awareness and engender compliance with the World Health Organization’s farm-based multiple-barrier approach are presented in this paper. Both qualitative...... and quantitative approaches have been used in this paper. One hundred vegetable farmers and four vegetable farmers’ associations in the Kumasi Metropolis in Ghana were covered. The individual farmers were grouped into two, namely: (1) participants and (2) non-participants of the farm-based multiple...

Complementary Health Approaches: Overcoming Barriers to Open Communication During Cancer Therapy
.

Science.gov (United States)

Wanchai, Ausanee; Armer, Jane M; Smith, Kandis M; Rodrick, Julia

2017-12-01

Complementary health approaches (CHAs) have been widely used by patients with cancer for many reasons. However, some patients choose not to disclose their use of CHAs to their nurses, fearing that this use will be viewed as unacceptable. Nurses may be uncomfortable talking about CHAs because of a lack of evidence-based research on the subject.
. This article promotes ways in which nurses can overcome barriers to open communication about CHAs with patients during cancer therapy.
. The literature related to CHAs and communication was reviewed.
. To encourage open communication between nurses and patients regarding the use of CHAs, nurses need to be more knowledgeable about CHAs through training or by conducting research related to CHAs.

Sound transmission analysis of plate structures using the finite element method and elementary radiator approach with radiator error index

DEFF Research Database (Denmark)

Jung, Jaesoon; Kook, Junghwan; Goo, Seongyeol

2017-01-01

combines the FEM and Elementary Radiator Approach (ERA) is proposed. The FE-ERA method analyzes the vibrational response of the plate structure excited by incident sound using FEM and then computes the transmitted acoustic pressure from the vibrating plate using ERA. In order to improve the accuracy...... and efficiency of the FE-ERA method, a novel criterion for the optimal number of elementary radiators is proposed. The criterion is based on the radiator error index that is derived to estimate the accuracy of the computation with used number of radiators. Using the proposed criterion a radiator selection method...... is presented for determining the optimum number of radiators. The presented radiator selection method and the FE-ERA method are combined to improve the computational accuracy and efficiency. Several numerical examples that have been rarely addressed in previous studies, are presented with the proposed method...

Systematic approach to training for competence building in radiation safety

International Nuclear Information System (INIS)

Asiamah, S.D.; Schandorf, C.; Darko, E.O.

2003-01-01

Competence building involves four main attributes, namely, knowledge, skills, operating experience and attitude to radiation safety. These multi-attribute requirements demand a systematic approach to education and training of regulatory staff, licensees/registrants and service providers to ensure commensurate competence in performance of responsibilities and duties to specified standards. In order to address issues of competencies required in radiation safety a national programme for qualification and certification has been initiated for regulatory staff, operators, radiation safety officers and qualified experts. Since the inception of this programme in 1993, 40 training events have been organized involving 423 individuals. This programme is at various levels of implementation due to financial and human resource constraints. A department for Human Resource Development and Research was established in 2000 to enhance and ensure the sustainability of the effectiveness of capacity building in radiation safety. (author)

A hybrid computational approach to estimate solar global radiation: An empirical evidence from Iran

International Nuclear Information System (INIS)

Mostafavi, Elham Sadat; Ramiyani, Sara Saeidi; Sarvar, Rahim; Moud, Hashem Izadi; Mousavi, Seyyed Mohammad

2013-01-01

This paper presents an innovative hybrid approach for the estimation of the solar global radiation. New prediction equations were developed for the global radiation using an integrated search method of genetic programming (GP) and simulated annealing (SA), called GP/SA. The solar radiation was formulated in terms of several climatological and meteorological parameters. Comprehensive databases containing monthly data collected for 6 years in two cities of Iran were used to develop GP/SA-based models. Separate models were established for each city. The generalization of the models was verified using a separate testing database. A sensitivity analysis was conducted to investigate the contribution of the parameters affecting the solar radiation. The derived models make accurate predictions of the solar global radiation and notably outperform the existing models. -- Highlights: ► A hybrid approach is presented for the estimation of the solar global radiation. ► The proposed method integrates the capabilities of GP and SA. ► Several climatological and meteorological parameters are included in the analysis. ► The GP/SA models make accurate predictions of the solar global radiation.

RCA - a regional approach to radiation protection

International Nuclear Information System (INIS)

Griffith, R.; Easey, J.

1996-01-01

The Regional Cooperative Agreement (RCA) for Asia and Oceania is the oldest of four International Atomic Energy Agency Member State regional programs. Organized in 1972, 17 countries are now members of RCA - Australia, Bangladesh, Peoples Republic of China, India, Indonesia, Japan, Republic of Korea, Malaysia, Mongolia, Myanmar, New Zealand, Pakistan, Philippines, Singapore, Sri Lanka, Thailand, and Viet Nam. A number of projects related to the application of a wide range of nuclear technologies are conducted through RCA. The program is established by national coordinators for each project area, in consultation with IAEA technical officers. Most of the funding comes directly from RCA regional donor countries, with about one third supplied through the IAEA Technical Cooperation program. In 1986, following the Chernobyl accident, national coordinators and the IAEA staff recognized the value of establishing an RCA project aimed at strengthening regional radiation protection programs. The potential importance of RCA involvement in radiation protection is underscored by the fact that its member states comprise more than half of the world's population. The regional approach to addressing radiation protection issues allows member states to take advantage of regional resources to solve common regional problems. RCA provides the opportunity for specialists who may have few professional colleagues in their country to develop valuable contacts with regional radiation protection experts. In a very real way, specialists can network with their neighbours, often establishing bilateral programs outside of the RCA auspices. The current five year RCA Project to strengthen radiation protection infrastructure, with the IAEA designation - RAS/9/006, will be completed at the end of 1997. The project was developed to address five mayor areas of activity: Off-site emergency response; individual monitoring, internal and external; characterization of the physical, anatomical, physiological

Barriers to the future

Energy Technology Data Exchange (ETDEWEB)

Massey, C T

1986-09-01

Opportunities for the British coal industry seem vast yet there are still barriers to progress. Seven areas are identified and discussed: mining mobility (for example, longwall mining systems are rigid and inflexible compared with American stall and pillar working); mine structure (many mines are more suitable to pit ponies than to large pieces of equipment); financial barriers (Government requires the industry to break even in 1987/88); personnel barriers (less specialization, better use of skills); safety barriers (increased use of remote control, ergonomics and robotics to protect workers); microelectronic management (nationalization has cushioned management from the market place; there is a need for a more multidisciplinary approach to the industry); and legal barriers (most legislation in the past has been in response to accidents; legislation external to the industry but affecting it is more fundamental).

Radiation-induced gastrointestinal toxicity. Pathophysiologie, approaches to treatment and prophylaxis

International Nuclear Information System (INIS)

Classen, J.; Belka, C.; Paulsen, F.; Budach, W.; Hoffmann, W.; Bamberg, M.

1998-01-01

Background: Gastrointestinal toxicity is frequently observed during radiotherapy of malignancies in the abdomen and pelvis. The proposed pathophysiology of radiation enteritis is complex and a variety of different treatment strategies have been suggested for the management of acute radiation-induced diarrhea. Material and methods: Data are presented from an extensive review of the current literature. Results: Radiation-induced diarrhea results from a variety of different pathophysiological mechanisms including malabsorption of bile salts and lactose, imbalances in local bacterial flora and changes in the intestinal patterns of motility. Up to date acute radiation diarrhea is predominantly treated symptomatically using opioide derivates (loperamide) or adsorbants of bile salts such as smectite. Clinical trials have been performed using L. acidophilus, smectite or sucralfate for diarrhea prophylaxis with moderate reduction of acute symptoms. Conclusions: Further evaluation of strategies for diarrhea prophylaxis is warranted. Due to the complex nature of radiation enteritis a multimodal approach taking into account alterations in intestinal motility patterns, malabsorption of bile salts and an imbalance of mucosal bacterial flora may offer new perspectives. (orig.) [de

[Systemic approach to ecologic safety at objects with radiation jeopardy, involved into localization of low and medium radioactive waste].

Science.gov (United States)

Veselov, E I

2011-01-01

The article deals with specifying systemic approach to ecologic safety of objects with radiation jeopardy. The authors presented stages of work and algorithm of decisions on preserving reliability of storage for radiation jeopardy waste. Findings are that providing ecologic safety can cover 3 approaches: complete exemption of radiation jeopardy waste, removal of more dangerous waste from present buildings and increasing reliability of prolonged localization of radiation jeopardy waste at the initial place. The systemic approach presented could be realized at various radiation jeopardy objects.

Radiative characterization of random fibrous media with long cylindrical fibers: Comparison of single- and multi-RTE approaches

Science.gov (United States)

Randrianalisoa, Jaona; Haussener, Sophia; Baillis, Dominique; Lipiński, Wojciech

2017-11-01

Radiative heat transfer is analyzed in participating media consisting of long cylindrical fibers with a diameter in the limit of geometrical optics. The absorption and scattering coefficients and the scattering phase function of the medium are determined based on the discrete-level medium geometry and optical properties of individual fibers. The fibers are assumed to be randomly oriented and positioned inside the medium. Two approaches are employed: a volume-averaged two-intensity approach referred to as multi-RTE approach and a homogenized single-intensity approach referred to as the single-RTE approach. Both approaches require effective properties, determined using direct Monte Carlo ray tracing techniques. The macroscopic radiative transfer equations (for single intensity or two volume-averaged intensities) with the corresponding effective properties are solved using Monte Carlo techniques and allow for the determination of the radiative flux distribution as well as overall transmittance and reflectance of the medium. The results are compared against predictions by the direct Monte Carlo simulation on the exact morphology. The effects of fiber volume fraction and optical properties on the effective radiative properties and the overall slab radiative characteristics are investigated. The single-RTE approach gives accurate predictions for high porosity fibrous media (porosity about 95%). The multi-RTE approach is recommended for isotropic fibrous media with porosity in the range of 79-95%.

Evaluation of the potential of PV noise barrier technology for electricity production and market share. Final report

International Nuclear Information System (INIS)

Goetzberger, A.; Kleiss, G.; Castello, S.; Hille, G.; Reise, C.; Wiemken, E.; Betcke, J.W.H.; Van Dijk, V.A.P.; Pearsall, N.; Hynes, K.; Gaidddon, B.; Nordmann, T.; Froelich, A.

1999-06-01

The analysis of existing and planned noise barriers along rails and roads has been carried out by the national partners together with national authorities, which are experts and responsible for the required data. The methodical approach of this study includes the set-up of a grid along longitude and latitudes with 1 by 1 degrees for Germany, Italy, France, United Kingdom and 0.5 by 0.5 degrees for the Netherlands and Switzerland. For each degree the length and orientation of rails and roads, the existing and planned noise barriers are registered and grouped according to their orientations. The solar radiation is based on data of a METEONORM data set. This includes the solar radiation on horizontal orientation as well as various inclination angles for all possible orientations. Moreover, possible shading has been considered. The technical specifications of noise barriers (PVNB) are based on the comprehensive knowledge of TNC GmbH and TNC AG with various plants realised. Technologies have been considered for both state-of-the-art and innovative concepts such as bifacial PVNB. In bifacial PVNB the PV-module is mounted vertically on both sides and is used at the same time as noise reflecting material. Installed PV power and produced electricity have been calculated for: 1. theoretical potential 2. technical potential 3. short-term resp. European extrapolated potential 4. anticipated potential 5. EU-member assessment The result of this study confirms the current activities to implement PV on noise barriers as an important share in the PV market.The report is subdivided into two volumes: Volume 1 contains the main topics and results, and Volume 2 contains additional information on the solar radiation, typical concepts as an excerpt of the various potentials and all country maps with the required explanations. 95 refs

The Argentine Approach to Radiation Safety: Its Ethical Basis

International Nuclear Information System (INIS)

Gonzalez, A.J.

2011-01-01

The ethical bases of Argentina's radiation safety approach are reviewed. The applied principles are those recommended and established internationally, namely: the principle of justification of decisions that alters the radiation exposure situation; the principle of optimization of protection and safety; the principle of individual protection for restricting possible inequitable outcomes of optimized safety; and the implicit principle of inter generational prudence for protection future generations and the habitat. The principles are compared vis-a-vis the prevalent ethical doctrines: justification vis-a-vis teleology; optimization vis-a-vis utilitarianism; individual protection vis-a-vis de ontology; and, inter generational prudence vis-a-vis aretaicism (or virtuosity). The application of the principles and their ethics in Argentina is analysed. These principles are applied to All exposure to radiation harm; namely, to exposures to actual doses and to exposures to actual risk and potential doses, including those related to the safety of nuclear installations, and they are harmonized and applied in conjunction. It is concluded that building a bridge among all available ethical doctrines and applying it to radiation safety against actual doses and actual risk and potential doses is at the roots of the successful nuclear regulatory experience in Argentina.

Exploring Barriers to Medication Safety in an Ethiopian Hospital Emergency Department: A Human Factors Engineering Approach

Directory of Open Access Journals (Sweden)

Ephrem Abebe

2018-02-01

Full Text Available Objective: To describe challenges associated with the medication use process and potential medication safety hazards in an Ethiopian hospital emergency department using a human factors approach. Methods: We conducted a qualitative study employing observations and semi-structured interviews guided by the Systems Engineering Initiative for Patient Safety model of work system as an analytical framework. The study was conducted in the emergency department of a teaching hospital in Ethiopia. Study participants included resident doctors, nurses, and pharmacists. We performed content analysis of the qualitative data using accepted procedures. Results: Organizational barriers included communication failures, limited supervision and support for junior staff contributing to role ambiguity and conflict. Compliance with documentation policy was minimal. Task related barriers included frequent interruptions and work-related stress resulting from job requirements to continuously prioritize the needs of large numbers of patients and family members. Person related barriers included limited training and work experience. Work-related fatigue due to long working hours interfered with staff’s ability to document and review medication orders. Equipment breakdowns were common as were non-calibrated or poorly maintained medical devices contributing to erroneous readings. Key environment related barriers included overcrowding and frequent interruption of staff’s work. Cluttering of the work space compounded the problem by impeding efforts to locate medications, medical supplies or medical charts. Conclusions: Applying a systems based approach allows a context specific understanding of medication safety hazards in EDs from low-income countries. When developing interventions to improve medication and overall patient safety, health leaders should consider the interactions of the different factors. Conflict of Interest We declare no conflicts of interest or

A coagulation-powdered activated carbon-ultrafiltration - Multiple barrier approach for removing toxins from two Australian cyanobacterial blooms

International Nuclear Information System (INIS)

Dixon, Mike B.; Richard, Yann; Ho, Lionel; Chow, Christopher W.K.; O'Neill, Brian K.; Newcombe, Gayle

2011-01-01

Cyanobacteria are a major problem for the world wide water industry as they can produce metabolites toxic to humans in addition to taste and odour compounds that make drinking water aesthetically displeasing. Removal of cyanobacterial toxins from drinking water is important to avoid serious illness in consumers. This objective can be confidently achieved through the application of the multiple barrier approach to drinking water quality and safety. In this study the use of a multiple barrier approach incorporating coagulation, powdered activated carbon (PAC) and ultrafiltration (UF) was investigated for the removal of intracellular and extracellular cyanobacterial toxins from two naturally occurring blooms in South Australia. Also investigated was the impact of these treatments on the UF flux. In this multibarrier approach, coagulation was used to remove the cells and thus the intracellular toxin while PAC was used for extracellular toxin adsorption and finally the UF was used for floc, PAC and cell removal. Cyanobacterial cells were completely removed using the UF membrane alone and when used in conjunction with coagulation. Extracellular toxins were removed to varying degrees by PAC addition. UF flux deteriorated dramatically during a trial with a very high cell concentration; however, the flux was improved by coagulation and PAC addition.

Information on radiation protection: an anthropological approach

International Nuclear Information System (INIS)

Van Nuffelen, D.

1996-01-01

It is necessary to prepare the messages on radiation protection before a nuclear accident arises, i.e. in a normal radiological situation. The approach discussed in this paper is based on hypothesis that any communication is a relationship between different actors (such as a transmitter and a receiver) whose semantic frames of reference, mainly defined by social and cultural determinants of knowledge, cannot be completely identical. To work out messages correctly intended for a given receiver, one has consequently to bring out the common semantic references to both the transmitter and the receiver. (author)

Approaches to assign security levels for radioactive substances and radiation sources

International Nuclear Information System (INIS)

Ivanov, M.V.; Petrovskij, N.P.; Pinchuk, G.N.; Telkov, S.N.; Kuzin, V.V.

2011-01-01

The article contains analyzed provisions on categorization of radioactive substances and radiation sources according to the extent of their potential danger. Above provisions are used in the IAEA documents and in Russian regulatory documents for differentiation of regulatory requirements to physical security. It is demonstrated that with the account of possible threats of violators, rules of physical protection of radiation sources and radioactive substances should be amended as regards the approaches to assign their categories and security levels [ru

Computing the blood brain barrier (BBB) diffusion coefficient: A molecular dynamics approach

Energy Technology Data Exchange (ETDEWEB)

Shamloo, Amir, E-mail: shamloo@sharif.edu; Pedram, Maysam Z.; Heidari, Hossein; Alasty, Aria, E-mail: aalasti@sharif.edu

2016-07-15

Various physical and biological aspects of the Blood Brain Barrier (BBB) structure still remain unfolded. Therefore, among the several mechanisms of drug delivery, only a few have succeeded in breaching this barrier, one of which is the use of Magnetic Nanoparticles (MNPs). However, a quantitative characterization of the BBB permeability is desirable to find an optimal magnetic force-field. In the present study, a molecular model of the BBB is introduced that precisely represents the interactions between MNPs and the membranes of Endothelial Cells (ECs) that form the BBB. Steered Molecular Dynamics (SMD) simulations of the BBB crossing phenomenon have been carried out. Mathematical modeling of the BBB as an input-output system has been considered from a system dynamics modeling viewpoint, enabling us to analyze the BBB behavior based on a robust model. From this model, the force profile required to overcome the barrier has been extracted for a single NP from the SMD simulations at a range of velocities. Using this data a transfer function model has been obtained and the diffusion coefficient is evaluated. This study is a novel approach to bridge the gap between nanoscale models and microscale models of the BBB. The characteristic diffusion coefficient has the nano-scale molecular effects inherent, furthermore reducing the computational costs of a nano-scale simulation model and enabling much more complex studies to be conducted. - Highlights: • Molecular dynamics simulation of crossing nano-particles through the BBB membrane at different velocities. • Recording the position of nano-particle and the membrane-NP interaction force profile. • Identification of a frequency domain model for the membrane. • Calculating the diffusion coefficient based on MD simulation and identified model. • Obtaining a relation between continuum medium and discrete medium.

A Strategic Approach to Establishing and Strengthening National Infrastructure for Radiation, Transport and Waste Safety

International Nuclear Information System (INIS)

Mastauskas, A.

2016-01-01

In Lithuania, as in the other countries of the world, in various areas, such as medicine, industry, education and training, agriculture the different technologies with the radioactive substances or devices, which generate ionizing radiation, are used. The responsibilities of each party and concern is to ensure the safe use ensure the radiation protection of the population and the environment. For every IAEA Member State in order to ensure the radiation safety, it is necessary to create the States radiation safety infrastructure: legislation, Regulatory Authority, technical support organizations. The International Atomic Energy Agency (IAEA) develops safety standards and assists Member States to create radiation safety infrastructure according the IAEA safety standards requirements. Noting that many Member States would benefit from bringing their radiation safety infrastructure more in line with IAEA Safety Standards, the Secretariat organized a meeting in May of 2014 of senior radiation safety experts from Africa, Asia & the Pacific, Europe, Latin America and North America, with the aim of developing a model strategic approach to establishing and strengthening national radiation safety infrastructure, with a special focus on Member States receiving assistance from the Agency. This model approach was presented to a wider audience on the margins of the IAEA General Conference in September 2014, where it was well received. This paper describes how the key elements of the model strategic approach were applied in Lithuania. The outcome of which showed that there is an adequate radiation safety infrastructure in place covering more than 50 legal acts, the establishment and empowerment of a Regulatory Authority – Radiation Protection Centre, technical support organizations – metrology and dosimetry services, and training centres. In Lithuania there exists a State registry of sources of ionizing radiation and occupational doses of exposure, a strong system of the

Evolution of Radiation Induced Defects in SiC: A Multiscale Simulation Approach

Science.gov (United States)

Jiang, Hao

Because of various excellent properties, SiC has been proposed for many applications in nuclear reactors including cladding layers in fuel rod, fission products container in TRISO fuel, and first wall/blanket in magnetic controlled fusion reactors. Upon exposure to high energy radiation environments, point defects and defect clusters are generated in materials in amounts significantly exceeding their equilibrium concentrations. The accumulation of defects can lead to undesired consequences such as crystalline-to-amorphous transformation1, swelling, and embrittlement, and these phenomena can adversely affect the lifetime of SiC based components in nuclear reactors. It is of great importance to understand the accumulation process of these defects in order to estimate change in properties of this material and to design components with superior ability to withstand radiation damages. Defect clusters are widely in SiC irradiated at the operation temperatures of various reactors. These clusters are believed to cause more than half of the overall swelling of irradiated SiC and can potentially lead to lowered thermal conductivity and mechanical strength. It is critical to understand the formation and growth of these clusters. Diffusion of these clusters is one importance piece to determine the growth rate of clusters; however it is unclear so far due to the challenges in simulating rare events. Using a combination of kinetic Activation Relaxation Technique with empirical potential and ab initio based climbing image nudged elastic band method, I performed an extensive search of the migration paths of the most stable carbon tri-interstitial cluster in SiC. This research reveals paths with the lowest energy barriers to migration, rotation, and dissociation of the most stable cluster. Based on these energy barriers, I concluded defect clusters are thermally immobile at temperatures lower than 1500 K and can dissociate into smaller clusters and single interstitials at

The natural background approach to setting radiation standards

International Nuclear Information System (INIS)

Adler, H.I.; Federow, H.; Weinberg, A.M.

1979-01-01

The suggestion has often been made that an additional radiation exposure imposed on humanity as a result of some important activity such as electricity generation would be acceptable if the exposure was 'small' compared to the natural background. In order to make this concept quantitative and objective, we propose that 'small compared with the natural background' be interpreted as the standard deviation (weighted with the exposed population) of the natural background. We believe that this use of the variation in natural background radiation is less arbitrary and requires fewer unfounded assumptions than some current approaches to standard-setting. The standard deviation is an easily calculated statistic that is small compared with the mean value for natural exposures of populations. It is an objectively determined quantity and its significance is generally understood. Its determination does not omit any of the pertinent data. When this method is applied to the population of the USA, it implies that a dose of 20 mrem/year would be an acceptable standard. This is closely comparable to the 25 mrem/year suggested by the Environmental Protection Agency as the maximum allowable exposure to an individual in the general population as a result of the operation of the complete uranium fuel cycle. Other agents for which a natural background exists can be treated in the same way as radiation. In addition, a second method for determining permissible exposure levels for agents other than radiation is presented. This method makes use of the natural background radiation data as a primary standard. Some observations on benzo(a)pyrene, using this latter method, are presented. (author)

An approach to controlling radiation exposures of probabilities less than one

International Nuclear Information System (INIS)

Ahmed, J.U.; Gonzalez, A.J.

1988-01-01

IAEA efforts to develop guidelines for a unified approach for the application of radiation protection principles to radiation exposures assumed to occur with certainty and exposures which are not certain to occur are discussed. A useful criterion is that of a limit on individual risk. A simple approach would be to define separate limits for normal and accident situations. For waste disposal ICRP has suggested a risk limit for accident situations to be of the same magnitude as that for normal operation. The IAEA is considering a risk limit of 10 -5 in a year for consistency with general safety standards of dose limitation. A source-related upper bound is needed which has to be apportioned from the risk limit in order to take into account the presence of other sources

Scientific substantiation of approaches to organization and conducting radiation surveys at the rehabilitated radiation sites

Directory of Open Access Journals (Sweden)

I. K. Romanovich

2017-01-01

Full Text Available The article is concerned with the scientific justification of approaches to the organization of the final radiation survey of facilities having radioactive contamination, after their rehabilitation. Scientific publications on the previous experience in rehabilitation of facilities contaminated with radionuclides, the organization and conducting a radiation survey before the start of the decontamination, during its implementation and after its completion were analyzed. The experience in the rehabilitation of the site for the temporary storage of spent fuel and radioactive waste in Andreeva Bay in the North-West region of Russia, the locations of peaceful nuclear explosions, experimental nuclear power plants, a radiochemical laboratory, and metallurgical plants, that do not belong to radiation facilities, has been studied. It has been established that, besides the surface contamination of the soil, areas of radioactive contamination on sites of decommissioned radiation facilities with significant depth up to 15 m along the profile are available. These local zones with depth soil contamination are persistent contaminants of the groundwater. The experience in the radiation survey of the peaceful nuclear explosions sites shows the removal of radionuclides from cavities, formed with the use of nuclear explosive technologies for peaceful purposes, on the earth’s surface. An optimized list of radionuclides to be monitored during the radiological survey of rehabilitated facilities was proposed based on the analysis of the composition of radionuclides detected at radiation sites subjected to decontamination. The optimized list includes 14 radionuclides with the half-lives of more than three years. 

ESR statement on radiation protection: globalisation, personalised medicine and safety (the GPS approach).

Science.gov (United States)

2013-12-01

In keeping with its responsibility for the radiation protection of patients undergoing radiological examinations and procedures, as well as of staff who are getting exposed, and with due regard to requirements under European Directives, the European Society of Radiology (ESR) issues this statement. It provides a holistic approach, termed as Globalisation (indicating all the steps and involving all stakeholders), Personalisation (referring to patient-centric) and Safety-thus called GPS. While being conscious that there is need to increase access of radiological imaging, ESR is aware about the increasing inappropriate medical exposures to ionising radiation and wide variation in patient doses for the same examination. The ESR is convinced that the different components of radiation protection are often interrelated and cannot be considered in isolation The ESR's GPS approach stands for: Globalisation (indicating all the steps and involving all stakeholders), Personalisation (referring to patient-centric) and Safety-thus called GPS It can be anticipated that enhanced protection of patients in Europe will result through the GPS approach. Although the focus is on patient safety, staff safety issues will find a place wherever pertinent.

Silicon surface barrier detectors used for liquid hydrogen density measurement

Science.gov (United States)

James, D. T.; Milam, J. K.; Winslett, H. B.

1968-01-01

Multichannel system employing a radioisotope radiation source, strontium-90, radiation detector, and a silicon surface barrier detector, measures the local density of liquid hydrogen at various levels in a storage tank. The instrument contains electronic equipment for collecting the density information, and a data handling system for processing this information.

Analysis of interactions among the barriers to JIT production: interpretive structural modelling approach

Science.gov (United States)

Jadhav, J. R.; Mantha, S. S.; Rane, S. B.

2015-09-01

`Survival of the fittest' is the reality in modern global competition. Organizations around the globe are adopting or willing to embrace just-in-time (JIT) production to reinforce the competitiveness. Even though JIT is the most powerful inventory management methodologies it is not free from barriers. Barriers derail the implementation of JIT production system. One of the most significant tasks of top management is to identify and understand the relationship between the barriers to JIT production for alleviating its bad effects. The aims of this paper are to study the barriers hampering the implementation of successful JIT production and analysing the interactions among the barriers using interpretive structural modelling technique. Twelve barriers have been identified after reviewing literature. This paper offers a roadmap for preparing an action plan to tackle the barriers in successful implementation of JIT production.

Geophysical characterization of subsurface barriers

International Nuclear Information System (INIS)

Borns, D.J.

1995-08-01

An option for controlling contaminant migration from plumes and buried waste sites is to construct a subsurface barrier of a low-permeability material. The successful application of subsurface barriers requires processes to verify the emplacement and effectiveness of barrier and to monitor the performance of a barrier after emplacement. Non destructive and remote sensing techniques, such as geophysical methods, are possible technologies to address these needs. The changes in mechanical, hydrologic and chemical properties associated with the emplacement of an engineered barrier will affect geophysical properties such a seismic velocity, electrical conductivity, and dielectric constant. Also, the barrier, once emplaced and interacting with the in situ geologic system, may affect the paths along which electrical current flows in the subsurface. These changes in properties and processes facilitate the detection and monitoring of the barrier. The approaches to characterizing and monitoring engineered barriers can be divided between (1) methods that directly image the barrier using the contrasts in physical properties between the barrier and the host soil or rock and (2) methods that reflect flow processes around or through the barrier. For example, seismic methods that delineate the changes in density and stiffness associated with the barrier represents a direct imaging method. Electrical self potential methods and flow probes based on heat flow methods represent techniques that can delineate the flow path or flow processes around and through a barrier

Phonic Attenuation due to Screen-Barriers

Directory of Open Access Journals (Sweden)

Vasile Bacria

2011-10-01

Full Text Available The technique of noise decreasing admits two basic approaches: an active approach and a passive one. In the frame of passive method one can count the employment of screen-barriers. In this paper we present some considerations on sound attenuation due to screen-barriers emphasizing the elements which influence it. The elucidation of these elements is made by measurements. The obtained results can be applied in every other practical situation concerning the protection against noise.

Radiation oncology: An Irish hospitals approach to supporting patients

Energy Technology Data Exchange (ETDEWEB)

Miller, Caragh [Cork University Hospital (Ireland)], E-mail: caragh.miller@tcd.ie

2009-02-15

Despite advances in medical technology, cancer is still one of the leading causes of death globally, leaving many patients to deal with the emotional and psychological aspects associated with cancer and its treatment [Department of Health and Children. A strategy for cancer control in Ireland. National Cancer Forum. Dublin; 2006]. The recognition and management of psychological conditions are an integral part of comprehensive cancer care. As a result, the Health Services Executive as part of the continuing expansion of Cork Radiation Oncology Department created the role of Information and Support Radiation Therapist. This post was specially created during June 2005 to facilitate the smooth entry into the treatment for patients and family members experiencing radiotherapy for the first time. Working alongside the oncology nurses and other health professionals the Information and Support Radiation Therapist aims to provide vital education/information and support to patients and their families. The provision of this new service for patients enables departments to adopt a holistic approach to treatment. This research identifies the cancer services and psychological support services in Ireland. Up-to-date audits of the new patient services established in the Cork Radiation Oncology Department and their psychological contribution towards cancer development and treatment are also discussed.

Radiation oncology: An Irish hospitals approach to supporting patients

International Nuclear Information System (INIS)

Miller, Caragh

2009-01-01

Despite advances in medical technology, cancer is still one of the leading causes of death globally, leaving many patients to deal with the emotional and psychological aspects associated with cancer and its treatment [Department of Health and Children. A strategy for cancer control in Ireland. National Cancer Forum. Dublin; 2006]. The recognition and management of psychological conditions are an integral part of comprehensive cancer care. As a result, the Health Services Executive as part of the continuing expansion of Cork Radiation Oncology Department created the role of Information and Support Radiation Therapist. This post was specially created during June 2005 to facilitate the smooth entry into the treatment for patients and family members experiencing radiotherapy for the first time. Working alongside the oncology nurses and other health professionals the Information and Support Radiation Therapist aims to provide vital education/information and support to patients and their families. The provision of this new service for patients enables departments to adopt a holistic approach to treatment. This research identifies the cancer services and psychological support services in Ireland. Up-to-date audits of the new patient services established in the Cork Radiation Oncology Department and their psychological contribution towards cancer development and treatment are also discussed

Group consensus peer review in radiation oncology: commitment to quality.

Science.gov (United States)

Duggar, W Neil; Bhandari, Rahul; Yang, Chunli Claus; Vijayakumar, Srinivasan

2018-03-27

Peer review, especially prospective peer review, has been supported by professional organizations as an important element in optimal Radiation Oncology practice based on its demonstration of efficacy at detecting and preventing errors prior to patient treatment. Implementation of peer review is not without barriers, but solutions do exist to mitigate or eliminate some of those barriers. Peer review practice at our institution involves three key elements: new patient conference, treatment planning conference, and chart rounds. The treatment planning conference is an adaptation of the group consensus peer review model from radiology which utilizes a group of peers reviewing each treatment plan prior to implementation. The peer group in radiation oncology includes Radiation Oncologists, Physician Residents, Medical Physicists, Dosimetrists, and Therapists. Thus, technical and clinical aspects of each plan are evaluated simultaneously. Though peer review is held in high regard in Radiation Oncology, many barriers commonly exist preventing optimal implementation such as time intensiveness, repetition, and distraction from clinic time with patients. Through the use of automated review tools and commitment by individuals and administration in regards to staffing, scheduling, and responsibilities, these barriers have been mitigated to implement this Group Consensus Peer Review model into a Radiation Oncology Clinic. A Group Consensus Peer Review model has been implemented with strategies to address common barriers to effective and efficient peer review.

Mouse genetic approaches applied to the normal tissue radiation response

International Nuclear Information System (INIS)

Haston, Christina K.

2012-01-01

The varying responses of inbred mouse models to radiation exposure present a unique opportunity to dissect the genetic basis of radiation sensitivity and tissue injury. Such studies are complementary to human association studies as they permit both the analysis of clinical features of disease, and of specific variants associated with its presentation, in a controlled environment. Herein I review how animal models are studied to identify specific genetic variants influencing predisposition to radiation-induced traits. Among these radiation-induced responses are documented strain differences in repair of DNA damage and in extent of tissue injury (in the lung, skin, and intestine) which form the base for genetic investigations. For example, radiation-induced DNA damage is consistently greater in tissues from BALB/cJ mice, than the levels in C57BL/6J mice, suggesting there may be an inherent DNA damage level per strain. Regarding tissue injury, strain specific inflammatory and fibrotic phenotypes have been documented for principally, C57BL/6 C3H and A/J mice but a correlation among responses such that knowledge of the radiation injury in one tissue informs of the response in another is not evident. Strategies to identify genetic differences contributing to a trait based on inbred strain differences, which include linkage analysis and the evaluation of recombinant congenic (RC) strains, are presented, with a focus on the lung response to irradiation which is the only radiation-induced tissue injury mapped to date. Such approaches are needed to reveal genetic differences in susceptibility to radiation injury, and also to provide a context for the effects of specific genetic variation uncovered in anticipated clinical association studies. In summary, mouse models can be studied to uncover heritable variation predisposing to specific radiation responses, and such variations may point to pathways of importance to phenotype development in the clinic.

Calcium phosphate barrier for augmentation of bone in noncontained periodontal osseous defects: a novel approach.

Science.gov (United States)

Chopra, Aditi; Sivaraman, Karthik; Awataramaney, Tarun K

2014-11-01

The aim of this technique is to augment bone in non-contained osseous deformities using a unique self-sustaining calcium phosphate barrier. Bone has the inherent ability to regenerate completely if it is provided with a fracture space or an undisturbed enclosed scaffold. A secluded environment is essential as it provides a secured, sterile and stable wound system that regenerates lost bone by a process of osteopromotion. Reconstructive techniques using bone grafts and barrier membranes utilize this principle for augmentation of deficient bony sites by providing a closed environment that promotes clot stability, graft retention, and facilitates correct cell repopulation. However, in noncontained bone defects like one walled infrabony periodontal defect or sites with horizontal bone loss, regeneration of bone still remains an unrealistic situation since osseous topography at such sites does not favor membrane stability or bone grafts retention. This case report presents a promising technique to augment bone in areas with horizontal loss. Augmentation of bone in the interdental area with horizontal bone loss was accomplished by building a contained defect using a unique self sustaining calcium phosphate cement formulation. The calcium phosphate barrier stimulates the lost cortical plates and promotes graft retention and clot stability. At 6 months, there was a significant bone fill and trabecular formation in the interdental area and reduction in tooth mobility. This promising technique could prove to be a good alternative to the conventional approaches for treating osseous deformities. Calcium phosphate is a promising barrier graft for repair of noncontained periodontal osseous defect. This technique cues both the clinicians and manufacturers to develop moldable tissue engineered constructs for osseous repair.

Microscopic approach of molecular dynamics. Applications to reactions near the barrier; Approches microscopiques de la dynamique nucleaire. Applications aux reactions autour de la barriere

Energy Technology Data Exchange (ETDEWEB)

Simenel, C.; Avez, B. [CEA Saclay, Dept. d' Astrophysique, de Physique des Particules de Physique Nucleaire et de l' Instrumentation Associee (DSM/DAPNIA/SPhN), 91- Gif sur Yvette (France); Lacroix, D. [GANIL, 14 - Caen (France)

2007-07-01

This lecture introduces several microscopic approaches to nuclear dynamics. Our goal is to provide a good description of low energy heavy ions collisions. We study both the formalism and the practical application of the time-dependent Hartree-Fock (TDHF) theory. The TDHF approach gives a mean field dynamics of the system under the assumption of independent particles. As an example, we study the fusion of both spherical and deformed nuclei with TDHF. We also show that nucleon transfer may occur between nuclei below the barrier. These studies allow us to specify the field of applications of TDHF in one hand, and, in the other hand, its intrinsic limitations, as for instance the fact that there is no fusion by tunnel effect with TDHF. It is then important to get rid of the independent particle assumption. We finally present some approaches to go beyond TDHF, including for instance pairing and/or collision term between nucleons, though only few realistic applications have been performed so far. (authors)

Innovative approach to training radiation safety regulatory professionals

International Nuclear Information System (INIS)

Gilley, Debbie Bray

2008-01-01

Full text: The supply of human resources required to adequately manage a radiation safety regulatory program has diminished in the last five years. Competing professional opportunities and a reduction in the number of health physics secondary schools have made it necessary to look at alternative methods of training. There are limited educational programs in the US that prepare our professionals for careers in the Radiation Regulatory Programs. The state of Florida's radiation control program embraced a new methodology using a combination of didactic and work experience using qualification journals, subject matter experts, and formalized training to develop a qualified pool of employees to perform the regulatory functions and emergency response requirements of a state radiation control program. This program uses a task-based approach to identify training needs and draws upon current staff to develop and implement the training. This has led to a task-oriented staff capable of responding to basic regulatory and emergency response activities within one year of employment. Florida's program lends itself to other states or countries with limited resources that have experienced staff attrition due to retirement or competing employment opportunities. Information on establishing a 'task-based' pool of employees that can perform basic regulatory functions and emergency response after one year of employment will be described. Initial task analysis of core functions and methodology is used to determine the appropriate training methodology for these functions. Instructions will be provided on the methodology used to 'mentor' new employees and then incorporate the new employees into the established core functions and be a useful employee at the completion of the first year of employment. New training philosophy and regime may be useful in assisting in the development of programs in countries and states with limited resources for training radiation protection personnel. (author)

Reusable radiation monitor

International Nuclear Information System (INIS)

Fanselow, D.L.; Ersfeld, D.A.

1978-01-01

An integrating, reusable device for monitoring exposure to actinic radiation is disclosed. The device comprises a substrate having deposited thereon at least one photochromic aziridine compound which is sealed in an oxygen barrier to stabilize the color developed by the aziridine compound in response to actinic radiation. The device includes a spectral response shaping filter to transmit only actinic radiation of the type being monitored. A color standard is also provided with which to compare the color developed by the aziridine compound

Model-free approach to the estimation of radiation hazards. I. Theory

International Nuclear Information System (INIS)

Zaider, M.; Brenner, D.J.

1986-01-01

The experience of the Japanese atomic bomb survivors constitutes to date the major data base for evaluating the effects of low doses of ionizing radiation on human populations. Although numerous analyses have been performed and published concerning this experience, it is clear that no consensus has emerged as to the conclusions that may be drawn to assist in setting realistic radiation protection guidelines. In part this is an inherent consequences of the rather limited amount of data available. In this paper the authors address an equally important problem; namely, the use of arbitrary parametric risk models which have little theoretical foundation, yet almost totally determine the final conclusions drawn. They propose the use of a model-free approach to the estimation of radiation hazards

Understanding barriers to glycaemic control from the patient's perspective

Directory of Open Access Journals (Sweden)

Janes R

2013-06-01

Full Text Available INTRODUCTION: To better understand barriers to glycaemic control from the patient's perspective. METHODS: An interpretative phenomenological approach was used to study the experiences of 15 adults with Type 2 diabetes. Participants each gave a semi-structured interview of their experiences of living with diabetes. Interviews were transcribed, and themes extracted and organised using a patientcentred framework. FINDINGS: Participants' stories confirmed many of the barriers in the literature, particularly those related to context, such as family, finances, work. Barriers also related to negative emotional reactions to diabetes: fear of new events (diagnosis, starting pills/insulin; guilt about getting diabetes and not controlling it; and shame about having diabetes. Barriers also related to unscientific beliefs and personal beliefs. There were additional barriers related to poor clinician-patient relationships. Overall, participants had a poor understanding of diabetes, and complained that their clinician simply 'told them what to do'. CONCLUSION: Using a patient-centred approach, this study identified many barriers to glycaemic control. We suggest that a key barrier is clinician ignorance of their patients' fears, beliefs, expectations, context; of what constitutes a positive therapeutic relationship; and of the limitations of a biomedical approach to patient non-adherence. Faced with both a worsening diabetes epidemic and increasing health care workforce shortages, clinicians urgently need to understand that it is they, not their patients, who must change their approach if diabetes care is to be improved.

Electronically Induced Redox Barriers for Treatment of Groundwater

National Research Council Canada - National Science Library

Sale, Tom; Gilbert, David

2006-01-01

...) and Colorado State University (CSU). The focus is an innovative electrolytic approach for managing redox-sensitive contaminants in groundwater, referred to as electrically induced redox barrier (e-barriers...

A Robot Trajectory Optimization Approach for Thermal Barrier Coatings Used for Free-Form Components

Science.gov (United States)

Cai, Zhenhua; Qi, Beichun; Tao, Chongyuan; Luo, Jie; Chen, Yuepeng; Xie, Changjun

2017-10-01

This paper is concerned with a robot trajectory optimization approach for thermal barrier coatings. As the requirements of high reproducibility of complex workpieces increase, an optimal thermal spraying trajectory should not only guarantee an accurate control of spray parameters defined by users (e.g., scanning speed, spray distance, scanning step, etc.) to achieve coating thickness homogeneity but also help to homogenize the heat transfer distribution on the coating surface. A mesh-based trajectory generation approach is introduced in this work to generate path curves on a free-form component. Then, two types of meander trajectories are generated by performing a different connection method. Additionally, this paper presents a research approach for introducing the heat transfer analysis into the trajectory planning process. Combining heat transfer analysis with trajectory planning overcomes the defects of traditional trajectory planning methods (e.g., local over-heating), which helps form the uniform temperature field by optimizing the time sequence of path curves. The influence of two different robot trajectories on the process of heat transfer is estimated by coupled FEM models which demonstrates the effectiveness of the presented optimization approach.

Review of NASA approach to space radiation risk assessments for Mars exploration.

Science.gov (United States)

Cucinotta, Francis A

2015-02-01

Long duration space missions present unique radiation protection challenges due to the complexity of the space radiation environment, which includes high charge and energy particles and other highly ionizing radiation such as neutrons. Based on a recommendation by the National Council on Radiation Protection and Measurements, a 3% lifetime risk of exposure-induced death for cancer has been used as a basis for risk limitation by the National Aeronautics and Space Administration (NASA) for low-Earth orbit missions. NASA has developed a risk-based approach to radiation exposure limits that accounts for individual factors (age, gender, and smoking history) and assesses the uncertainties in risk estimates. New radiation quality factors with associated probability distribution functions to represent the quality factor's uncertainty have been developed based on track structure models and recent radiobiology data for high charge and energy particles. The current radiation dose limits are reviewed for spaceflight and the various qualitative and quantitative uncertainties that impact the risk of exposure-induced death estimates using the NASA Space Cancer Risk (NSCR) model. NSCR estimates of the number of "safe days" in deep space to be within exposure limits and risk estimates for a Mars exploration mission are described.

A Systems Genetic Approach to Identify Low Dose Radiation-Induced Lymphoma Susceptibility/DOE2013FinalReport

Energy Technology Data Exchange (ETDEWEB)

Balmain, Allan [University of California, San Francisco; Song, Ihn Young [University of California, San Francisco

2013-05-15

The ultimate goal of this project is to identify the combinations of genetic variants that confer an individual's susceptibility to the effects of low dose (0.1 Gy) gamma-radiation, in particular with regard to tumor development. In contrast to the known effects of high dose radiation in cancer induction, the responses to low dose radiation (defined as 0.1 Gy or less) are much less well understood, and have been proposed to involve a protective anti-tumor effect in some in vivo scientific models. These conflicting results confound attempts to develop predictive models of the risk of exposure to low dose radiation, particularly when combined with the strong effects of inherited genetic variants on both radiation effects and cancer susceptibility. We have used a Systems Genetics approach in mice that combines genetic background analysis with responses to low and high dose radiation, in order to develop insights that will allow us to reconcile these disparate observations. Using this comprehensive approach we have analyzed normal tissue gene expression (in this case the skin and thymus), together with the changes that take place in this gene expression architecture a) in response to low or high- dose radiation and b) during tumor development. Additionally, we have demonstrated that using our expression analysis approach in our genetically heterogeneous/defined radiation-induced tumor mouse models can uniquely identify genes and pathways relevant to human T-ALL, and uncover interactions between common genetic variants of genes which may lead to tumor susceptibility.

A new insert sample approach to paper spray mass spectrometry: a paper substrate with paraffin barriers.

Science.gov (United States)

Colletes, T C; Garcia, P T; Campanha, R B; Abdelnur, P V; Romão, W; Coltro, W K T; Vaz, B G

2016-03-07

The analytical performance for paper spray (PS) using a new insert sample approach based on paper with paraffin barriers (PS-PB) is presented. The paraffin barrier is made using a simple, fast and cheap method based on the stamping of paraffin onto a paper surface. Typical operation conditions of paper spray such as the solvent volume applied on the paper surface, and the paper substrate type are evaluated. A paper substrate with paraffin barriers shows better performance on analysis of a range of typical analytes when compared to the conventional PS-MS using normal paper (PS-NP) and PS-MS using paper with two rounded corners (PS-RC). PS-PB was applied to detect sugars and their inhibitors in sugarcane bagasse liquors from a second generation ethanol process. Moreover, the PS-PB proved to be excellent, showing results for the quantification of glucose in hydrolysis liquors with excellent linearity (R(2) = 0.99), limits of detection (2.77 mmol L(-1)) and quantification (9.27 mmol L(-1)). The results are better than for PS-NP and PS-RC. The PS-PB was also excellent in performance when compared with the HPLC-UV method for glucose quantification on hydrolysis of liquor samples.

Photodetector of ultraviolet radiation

International Nuclear Information System (INIS)

Dorogan, V.; Branzari, V.; Vieru, T.; Manole, M.; Canter, V.

2000-01-01

The invention relates to photodetectors on base of semiconductors of ultraviolet radiation and may be used in optoelectronic system for determining the intensity and the dose of ultraviolet radiation emitted by the Sun or other sources. Summary of the invention consists in the fact that in the photodetector of ultraviolet radiation the superficial potential barrier is divided into two identical elements, electrically isolated each of the other, one of them being covered with a layer of transparent material for visible and infrared radiation and absorption the ultra violet radiation. The technical result consists in mutual compensation of visible and infrared components of the radiation spectrum

Natural background approach to setting radiation standards

International Nuclear Information System (INIS)

Adler, H.I.; Federow, H.; Weinberg, A.M.

1979-01-01

The suggestion has often been made that an additional radiation exposure imposed on humanity as a result of some important activity such as electricity generation would be acceptable if the exposure was small compared to the natural background. In order to make this concept quantitative and objective, we propose that small compared with the natural background be interpreted as the standard deviation (weighted with the exposed population) of the natural background. This use of the variation in natural background radiation is less arbitrary and requires fewer unfounded assumptions than some current approaches to standard-setting. The standard deviation is an easily calculated statistic that is small compared with the mean value for natural exposures of populations. It is an objectively determined quantity and its significance is generally understood. Its determination does not omit any of the pertinent data. When this method is applied to the population of the United States, it suggests that a dose of 20 mrem/year would be an acceptable standard. This is comparable to the 25 mrem/year suggested as the maximum allowable exposure to an individual from the complete uranium fuel cycle

Natural and Synthetic Barriers to Immobilize Radionuclides

International Nuclear Information System (INIS)

Um, W.

2011-01-01

The experiments of weathering of glass waste form and the reacted sediments with simulated glass leachates show that radionuclide sequestration can be significantly enhanced by promoting the formation of secondary precipitates. In addition, synthetic phosphate-bearing nanoporous material exhibits high stability at temperature and has a very high K d value for U(VI) removal. Both natural and synthetic barrier materials can be used as additional efficient adsorbents for retarding transport of radionuclides for various contaminated waste streams and waste forms present at U. S. Department of Energy clean-up sites and the proposed geologic radioactive waste disposal facility. In the radioactive waste repository facility, natural or synthetic materials are planned to be used as a barrier material to immobilize and retard radionuclide release. The getter material can be used to selectively scavenge the radionuclide of interest from a liquid waste stream and subsequently incorporate the loaded getters in a cementitious or various monolithic waste forms. Also, the getter material is to reduce the release of radionuclides from monolithic waste forms. Also, the getter material is to reduce the release of radionuclides from monolithic waste forms. Also, the getter material is to reduce the release of radionuclides form monolithic waste forms by being emplaced as a backfill barrier material around the wastes or waste form to minimize the potential around the wastes or waste form to minimize the potential hazard of leached radioactive wastes. The barrier material should be highly efficient to sequester radionuclides and possess physical and chemical stability for long-term exposure to severe weathering conditions. Because potential leaching of radionuclides depends on various environmental and weathering conditions of the near-field repository, the barrier materials must be durable and not disintegrate under a range of moisture, temperature, pressure, radiation, Eh, ph. and

Identifying barriers to and facilitators of tuberculosis contact investigation in Kampala, Uganda: a behavioral approach.

Science.gov (United States)

Ayakaka, Irene; Ackerman, Sara; Ggita, Joseph M; Kajubi, Phoebe; Dowdy, David; Haberer, Jessica E; Fair, Elizabeth; Hopewell, Philip; Handley, Margaret A; Cattamanchi, Adithya; Katamba, Achilles; Davis, J Lucian

2017-03-09

The World Health Organization recommends routine household tuberculosis contact investigation in high-burden countries but adoption has been limited. We sought to identify barriers to and facilitators of TB contact investigation during its introduction in Kampala, Uganda. We collected cross-sectional qualitative data through focus group discussions and interviews with stakeholders, addressing three core activities of contact investigation: arranging household screening visits through index TB patients, visiting households to screen contacts and refer them to clinics, and evaluating at-risk contacts coming to clinics. We analyzed the data using a validated theory of behavior change, the Capability, Opportunity, and Motivation determine Behavior (COM-B) model, and sought to identify targeted interventions using the related Behavior Change Wheel implementation framework. We led seven focus-group discussions with 61 health-care workers, two with 21 lay health workers (LHWs), and one with four household contacts of newly diagnosed TB patients. We, in addition, performed 32 interviews with household contacts from 14 households of newly diagnosed TB patients. Commonly noted barriers included stigma, limited knowledge about TB among contacts, insufficient time and space in clinics for counselling, mistrust of health-center staff among index patients and contacts, and high travel costs for LHWs and contacts. The most important facilitators identified were the personalized and enabling services provided by LHWs. We identified education, persuasion, enablement, modeling of health-positive behaviors, incentivization, and restructuring of the service environment as relevant intervention functions with potential to alleviate barriers to and enhance facilitators of TB contact investigation. The use of a behavioral theory and a validated implementation framework provided a comprehensive approach for systematically identifying barriers to and facilitators of TB contact

A sensitivity-based approach to optimize the surface treatment of a low-height tramway noise barrier

Science.gov (United States)

Jolibois, Alexandre

Transportation noise has become a main nuisance in urban areas, in the industrialized world and across the world, to the point that according to the World Health Organization 65% of the European population is exposed to excessive noise and 20% to night-time levels that may harm their health. There is therefore a need to find new ways to mitigate transportation noise in urban areas. In this work, a possible device to achieve this goal is studied: a low-height noise barrier. It consists of a barrier typically less than one meter high placed close to the source, designed to decrease significantly the noise level for nearby pedestrians and cyclists. A numerical method which optimizes the surface treatment of a low-height barrier in order to increase its insertion loss is presented. Tramway noise barriers are especially studied since the noise sources are in this case close to the ground and would be attenuated more by the barrier. The acoustic behavior of the surface treatment is modeled via its admittance. It can be itself described by a few parameters (flow resistivity, geometrical dimensions...), which can then be optimized. It is proposed to couple porous layers and micro-perforated panel (MPP) resonators in order to take advantage of their different acoustic properties. Moreover, the optimization is achieved using a sensitivity-based method, since in this framework the gradient of the attenuation can be evaluated accurately and efficiently. Several shapes are considered: half-cylinder, quarter-cylinder, straight wall, T-shape and square shape. In the case of a half-cylindrical geometry, a semi-analytical solution for the sound field in terms of a series of cylindrical waves is derived, which simplifies the sensitivity calculation and optimization process. The boundary element method (BEM) is used to evaluate the attenuation for the remaining shapes, and in this case the sensitivity is evaluated using the adjoint state approach. For all considered geometries, it is

Approach to the problem of combined radiation and environmental effect standardization

International Nuclear Information System (INIS)

Burykina, L.N.; Ajzina, N.L.; Vasil'eva, L.A.; Veselovskaya, K.A.; Likhachev, Yu.P.; Ponomareva, V.L.; Satarina, S.M.; Shmeleva, E.V.

1978-01-01

Rats were used to study combined forms of damage caused by radioactive substances with varioUs types of distribution ( 131 I and 147 Pm) and by external radiation sources (γ, X). Damage caused by radiation and dust factors was also studied. Synergism of the combined effect of the tolerance dose of 147 Pm introduced and preceding external general γ-irradiation was determined. The combined action of 131 I and external γ- and X-ray radiation exhibited an additional effect on rat thyroid glands. The combined action of dust and radiation factors showed that the biological effect depended on the dose abs.orbed in a critical organ (lungs). The results of the investigations point to an important role of critical organs (systems) and the degree of their radiosensitivity in response of body to combined internal and external irradiations. The facts presented show that the approach to standardizing radiation factors from the position of partial summation should be changed. This may be accomplished by using a combination factor which is determined experimentally and reflects a relative biological efficiency of the combined effects as compared to separate ones

Australia's proactive approach to radiation protection of the environment: how integrated is it with radiation protection of humans?

Science.gov (United States)

Hirth, G A; Grzechnik, M; Tinker, R; Larsson, C M

2018-01-01

Australia's regulatory framework has evolved over the past decade from the assumption that protection of humans implies protection of the environment to the situation now where radiological impacts on non-human species (wildlife) are considered in their own right. In an Australian context, there was a recognised need for specific national guidance on protection of non-human species, for which the uranium mining industry provides the major backdrop. National guidance supported by publications of the Australian Radiation Protection and Nuclear Safety Agency (Radiation Protection Series) provides clear and consistent advice to operators and regulators on protection of non-human species, including advice on specific assessment methods and models, and how these might be applied in an Australian context. These approaches and the supporting assessment tools provide a mechanism for industry to assess and demonstrate compliance with the environmental protection objectives of relevant legislation, and to meet stakeholder expectations that radiological protection of the environment is taken into consideration in accordance with international best practice. Experiences from the past 5-10 years, and examples of where the approach to radiation protection of the environment has been well integrated or presented some challenges will be discussed. Future challenges in addressing protection of the environment in existing exposure situations will also be discussed.

One-way Ponderomotive Barrier in a Uniform Magnetic Field

International Nuclear Information System (INIS)

Dodin, I.Y.; Fisch, N.J.

2005-01-01

The possibility of an asymmetric ponderomotive barrier in a nonuniform dc magnetic field by high-frequency radiation near the cyclotron resonance for selected plasma species was contemplated in Physics of Plasmas 11 (November 2004) 5046-5064. Here we show that a similar one-way barrier, which reflects particles incident from one side while transmitting those incident from the opposite side, can be produced also in a uniform magnetic field, entirely due to inhomogeneity of high-frequency drive

Air barrier details: How effective are they

Energy Technology Data Exchange (ETDEWEB)

A project was initiated to measure the air leakage through three typical details in wood frame walls: the header joist, electric outlets, and window openings. Three construction methods were tested: the poly approach, where a sealed internal polyethylene sheet and caulking provide the air barrier; an external air barrier approach using a continuous vapor permeable membrane sandwiched between two layers of external wall sheathing; and the airtight drywall approach (ADA), where the interior gypsum board finish along with framing and gaskets are the air barrier. Twelve sample panels using each of the three details were built using each of the construction approaches. A traditional wood-frame wall construction detail, with no effort made to create a continuous air barrier, was also built and tested for comparison. The samples were put in a test chamber so that air pressures could create infiltration or exfiltration through the panel under loads similar to those due to wind action. Measurements were made at several stages during construction of each sample to see the effect of different components on the air leakage. Overall, all but the traditional samples and the ADA electrical outlet panel exceeded the current tightness standards for glass and aluminum curtain walls. All three approaches could meet the airtightness standards of the R-2000 program. The total air leakage calculated for each approach is under 20% of that in traditional construction. Of the details tested, window detailing offers the greatest potential for increasing overall airtightness compared to traditional methods. 1 ref., 2 figs., 1 tab.

Identifying barriers to chronic disease reporting in Chicago Public Schools: a mixed-methods approach.

Science.gov (United States)

Rivkina, Victoria; Tapke, David E; Cardenas, Lilliana D; Harvey-Gintoft, Blair; Whyte, Stephanie A; Gupta, Ruchi S

2014-12-06

Chronic disease among school-aged children is a public health concern, particularly for asthma and food allergy. In Chicago Public Schools (CPS), rates of asthma and food allergy among students are underreported. The aim of this study was to determine the barriers to chronic disease reporting as experienced by CPS parents and school nurses. A mixed-methods approach included focus groups and key informant interviews with parents and school nurses, and a cross-sectional survey was completed by parents. Qualitative data analysis was performed and survey data were analyzed to determine the significant demographic and knowledge variables associated with successfully completing the reporting process. The three main barriers identified were 1) a lack of parental process knowledge; 2) limited communication from schools; and 3) insufficient availability of school nurses. Parents were significantly more likely to successfully complete the reporting process if they knew about special accommodations for chronic diseases, understood the need for physician verification, and/or knew the school nurse. These findings suggest that increasing parental knowledge of the reporting process will allow schools to better identify and manage their students' chronic conditions. A parent-focused intervention informed by these results has been completed.

Novel targeted approach to better understand how natural structural barriers govern carotenoid in vitro bioaccessibility in vegetable-based systems.

Science.gov (United States)

Palmero, Paola; Lemmens, Lien; Ribas-Agustí, Albert; Sosa, Carola; Met, Kristof; de Dieu Umutoni, Jean; Hendrickx, Marc; Van Loey, Ann

2013-12-01

An experimental approach, allowing us to understand the effect of natural structural barriers (cell walls, chromoplast substructures) on carotenoid bioaccessibility, was developed. Different fractions with different levels of carotenoid bio-encapsulation (carotenoid-enriched oil, chromoplasts, small cell clusters, and large cell clusters) were isolated from different types of carrots and tomatoes. An in vitro method was used to determine carotenoid bioaccessibility. In the present work, a significant decrease in carotenoid in vitro bioaccessibility could be observed with an increasing level of bio-encapsulation. Differences in cell wall material and chromoplast substructure between matrices influenced carotenoid release and inclusion in micelles. For carrots, cell walls and chromoplast substructure were important barriers for carotenoid bioaccessibility while, in tomatoes, the chromoplast substructure represented the most important barrier governing bioaccessibility. The highest increase in carotenoid bioaccessibility, for all matrices, was obtained after transferring carotenoids into the oil phase, a system lacking cell walls and chromoplast substructures that could hamper carotenoid release. Copyright © 2013 Elsevier Ltd. All rights reserved.

Barriers to improvements in energy efficiency

Energy Technology Data Exchange (ETDEWEB)

Reddy, A.K.N.

1991-10-01

To promote energy-efficiency improvements, actions may be required at one or more levels -- from the lowest level of the consumer (residential, commercial, industrial, etc.) through the highest level of the global agencies. But barriers to the implementation of energy-efficiency improvements exist or can arise at all these levels. Taking up each one of these barriers in turn, the paper discusses specific measures that can contribute to overcoming the barriers. However, a one-barrier-one-measure approach must be avoided. Single barriers may in fact involve several sub-barriers. Also, combinations of measures are much more effective in overcoming barriers. In particular, combinations of measures that simultaneously overcome several barriers are most successful. The paper discusses the typology of barriers, explores their origin and suggests measures that by themselves or in combination with other measures, will overcome these barriers. Since most of the barriers dealt with can be found in the barriers'' literature, any originality in the paper lies in its systematic organization, synoptic view and holistic treatment of this issue. This paper is intended to initiate a comprehensive treatment of barriers, their origins and the measures that contribute to overcoming them. Hopefully, such a treatment will facilitate the implementation of energy-efficiency improvements involving a wide diversity of ever-changing energy end uses and consumer preferences.

Barriers to improvements in energy efficiency

Energy Technology Data Exchange (ETDEWEB)

Reddy, A.K.N.

1991-10-01

To promote energy-efficiency improvements, actions may be required at one or more levels -- from the lowest level of the consumer (residential, commercial, industrial, etc.) through the highest level of the global agencies. But barriers to the implementation of energy-efficiency improvements exist or can arise at all these levels. Taking up each one of these barriers in turn, the paper discusses specific measures that can contribute to overcoming the barriers. However, a one-barrier-one-measure approach must be avoided. Single barriers may in fact involve several sub-barriers. Also, combinations of measures are much more effective in overcoming barriers. In particular, combinations of measures that simultaneously overcome several barriers are most successful. The paper discusses the typology of barriers, explores their origin and suggests measures that by themselves or in combination with other measures, will overcome these barriers. Since most of the barriers dealt with can be found in the ``barriers`` literature, any originality in the paper lies in its systematic organization, synoptic view and holistic treatment of this issue. This paper is intended to initiate a comprehensive treatment of barriers, their origins and the measures that contribute to overcoming them. Hopefully, such a treatment will facilitate the implementation of energy-efficiency improvements involving a wide diversity of ever-changing energy end uses and consumer preferences.

COMPETENCE APPROACH TO TRAINING OF EXPERTS IN RADIATION HYGIENE

Directory of Open Access Journals (Sweden)

T. B. Baltrukova

2015-01-01

Full Text Available Modification of attitude to labor in the society, in professional communities and among people is necessary for further development of society and national economy. This goal may be achieved if the system of professional training is modified: switched to competence approach which should include training of experts, including those in radiation hygiene, with a set of general cultural and professional competences. The system of future experts training should be based on traditions of domestic and international education; it should use modern forms of active and interactive education (computer simulations, business games and role-playing, analysis of concrete situations, portfolio, psychological and other trainings, remote education, etc. It should consider actuality of knowledge and skills and develop independence and responsibility that will enable the young expert to be competitive at the modern labor market and to meet employers’ expectations. Under the new federal educational standard on radiation hygiene accepted in 2014 at present primary specialization in radiation hygiene takes place in internship. At training of experts the new standard provides great use of on-the-job training, independent work, scientific and practical work. Employers should play an important role in training of experts.

A novel approach for introducing cloud spatial structure into cloud radiative transfer parameterizations

Science.gov (United States)

Huang, Dong; Liu, Yangang

2014-12-01

Subgrid-scale variability is one of the main reasons why parameterizations are needed in large-scale models. Although some parameterizations started to address the issue of subgrid variability by introducing a subgrid probability distribution function for relevant quantities, the spatial structure has been typically ignored and thus the subgrid-scale interactions cannot be accounted for physically. Here we present a new statistical-physics-like approach whereby the spatial autocorrelation function can be used to physically capture the net effects of subgrid cloud interaction with radiation. The new approach is able to faithfully reproduce the Monte Carlo 3D simulation results with several orders less computational cost, allowing for more realistic representation of cloud radiation interactions in large-scale models.

New approaches to quantifying aerosol influence on the cloud radiative effect.

Science.gov (United States)

Feingold, Graham; McComiskey, Allison; Yamaguchi, Takanobu; Johnson, Jill S; Carslaw, Kenneth S; Schmidt, K Sebastian

2016-05-24

The topic of cloud radiative forcing associated with the atmospheric aerosol has been the focus of intense scrutiny for decades. The enormity of the problem is reflected in the need to understand aspects such as aerosol composition, optical properties, cloud condensation, and ice nucleation potential, along with the global distribution of these properties, controlled by emissions, transport, transformation, and sinks. Equally daunting is that clouds themselves are complex, turbulent, microphysical entities and, by their very nature, ephemeral and hard to predict. Atmospheric general circulation models represent aerosol-cloud interactions at ever-increasing levels of detail, but these models lack the resolution to represent clouds and aerosol-cloud interactions adequately. There is a dearth of observational constraints on aerosol-cloud interactions. We develop a conceptual approach to systematically constrain the aerosol-cloud radiative effect in shallow clouds through a combination of routine process modeling and satellite and surface-based shortwave radiation measurements. We heed the call to merge Darwinian and Newtonian strategies by balancing microphysical detail with scaling and emergent properties of the aerosol-cloud radiation system.

Nuclear energy technology transfer: the security barriers

International Nuclear Information System (INIS)

Rinne, R.L.

1975-08-01

The problems presented by security considerations to the transfer of nuclear energy technology are examined. In the case of fusion, the national security barrier associated with the laser and E-beam approaches is discussed; for fission, the international security requirements, due to the possibility of the theft or diversion of special nuclear materials or sabotage of nuclear facilities, are highlighted. The paper outlines the nuclear fuel cycle and terrorist threat, examples of security barriers, and the current approaches to transferring technology. (auth)

Energy barrier to decoherence

International Nuclear Information System (INIS)

Mizel, Ari; Mitchell, M. W.; Cohen, Marvin L.

2001-01-01

We propose a ground-state approach to realizing quantum computers. This scheme is time-independent and inherently defends against decoherence by possessing an energy barrier to excitation. We prove that our time-independent qubits can perform the same algorithms as their time-dependent counterparts. Advantages and disadvantages of the time-independent approach are described. A model involving quantum dots is provided for illustration

Richards Barrier LA Reference Design Feature Evaluation

International Nuclear Information System (INIS)

N.E. Kramer

1999-01-01

The Richards Barrier is one of the design features of the repository to be considered for the License Application (LA), Richards was a soil scientist who first described the diversion of moisture between two materials with different hydrologic properties. In this report, a Richards Barrier is a special type of backfill with a fine-grained material (such as sand) overlaying a coarse-grained material (such as gravel). Water that enters an emplacement drift will first encounter the fine-grained material and be transported around the coarse-grained material covering the waste package, thus protecting the waste package from contact with most of the groundwater. The objective of this report is to discuss the benefits and liabilities to the repository by the inclusion of a Richards Barrier type backfill in emplacement drifts. The Richards Barrier can act as a barrier to water flow, can reduce the waste package material dissolution rate, limit mobilization of the radionuclides, and can provide structural protection for the waste package. The scope of this report is to: (1) Analyze the behavior of barrier materials following the intrusion of groundwater for influxes of 1 to 300 mm per year. The report will demonstrate diversion of groundwater intrusions into the barrier over an extended time period when seismic activity and consolidation may cause the potential for liquefaction and settlement of the Richards Barrier. (2) Review the thermal effects of the Richards Barrier on material behavior. (3) Analyze the effect of rockfall on the performance of the Richards Barrier and the depth of the barrier required to protect waste packages under the barrier. (4) Review radiological and heating conditions on placement of multiple layers of the barrier. Subsurface Nuclear Safety personnel will perform calculations to determine the radiation reduction-time relationship and shielding capacity of the barrier. (5) Evaluate the effects of ventilation on cooling of emplacement drifts and

Barriers and post-closure monitoring (AL121125)

International Nuclear Information System (INIS)

Bostick, K.V.; Janecky, D.

1995-01-01

This project focuses on the rapid implementation of near-surface barriers, biotreatment, and post-closure monitoring technology. It uses water-permeable and biologic barriers that chemically capture and/or degrade contaminants without significantly altering the natural water flow regime. Barrier approaches are being tested for two different applications. The first is the use of barriers for confinement of chemical contaminants for in-trench treatments with leach systems or an in-place bioreactor. The second is an enhancement of the current practice of emplacing grout or clay slurry walls into direct horizontal surface and subsurface water flows around a contaminated area by integrating permeable reactive barriers and petroleum reservoir gel/foam/polymer technology

Theoretical analysis of the rotational barrier of ethane.

Science.gov (United States)

Mo, Yirong; Gao, Jiali

2007-02-01

The understanding of the ethane rotation barrier is fundamental for structural theory and the conformational analysis of organic molecules and requires a consistent theoretical model to differentiate the steric and hyperconjugation effects. Due to recently renewed controversies over the barrier's origin, we developed a computational approach to probe the rotation barriers of ethane and its congeners in terms of steric repulsion, hyperconjugative interaction, and electronic and geometric relaxations. Our study reinstated that the conventional steric repulsion overwhelmingly dominates the barriers.

Promising approaches to circumvent the blood-brain barrier: progress, pitfalls and clinical prospects in brain cancer.

Science.gov (United States)

Papademetriou, Iason T; Porter, Tyrone

2015-01-01

Brain drug delivery is a major challenge for therapy of central nervous system (CNS) diseases. Biochemical modifications of drugs or drug nanocarriers, methods of local delivery, and blood-brain barrier (BBB) disruption with focused ultrasound and microbubbles are promising approaches which enhance transport or bypass the BBB. These approaches are discussed in the context of brain cancer as an example in CNS drug development. Targeting to receptors enabling transport across the BBB offers noninvasive delivery of small molecule and biological cancer therapeutics. Local delivery methods enable high dose delivery while avoiding systemic exposure. BBB disruption with focused ultrasound and microbubbles offers local and noninvasive treatment. Clinical trials show the prospects of these technologies and point to challenges for the future.

A novel approach for introducing cloud spatial structure into cloud radiative transfer parameterizations

International Nuclear Information System (INIS)

Huang, Dong; Liu, Yangang

2014-01-01

Subgrid-scale variability is one of the main reasons why parameterizations are needed in large-scale models. Although some parameterizations started to address the issue of subgrid variability by introducing a subgrid probability distribution function for relevant quantities, the spatial structure has been typically ignored and thus the subgrid-scale interactions cannot be accounted for physically. Here we present a new statistical-physics-like approach whereby the spatial autocorrelation function can be used to physically capture the net effects of subgrid cloud interaction with radiation. The new approach is able to faithfully reproduce the Monte Carlo 3D simulation results with several orders less computational cost, allowing for more realistic representation of cloud radiation interactions in large-scale models. (letter)

A theoretical approach to photosynthetically active radiation silicon sensor

International Nuclear Information System (INIS)

Tamasi, M.J.L.; Martínez Bogado, M.G.

2013-01-01

This paper presents a theoretical approach for the development of low cost radiometers to measure photosynthetically active radiation (PAR). Two alternatives are considered: a) glass optical filters attached to a silicon sensor, and b) dielectric coating on a silicon sensor. The devices proposed are based on radiometers previously developed by the Argentine National Atomic Energy Commission. The objective of this work is to adapt these low cost radiometers to construct reliable instruments for measuring PAR. The transmittance of optical filters and sensor response have been analyzed for different dielectric materials, number of layers deposited, and incidence angles. Uncertainties in thickness of layer deposition were evaluated. - Highlights: • Design of radiometers to measure photosynthetically active radiation • The study has used a filter and a Si sensor to modify spectral response. • Dielectric multilayers on glass and silicon sensor • Spectral response related to different incidence angles, materials and spectra

Different Approaches in Radiation Therapy

Directory of Open Access Journals (Sweden)

Rolf-Dieter eKortmann

2011-12-01

Full Text Available Radiation therapy is a cornerstone in the therapeutic management of craniopharyngioma. The close proximity to neighbouring eloquent structures pose a particular challenge to radiation therapy. Modern treatment technologies including fractionated 3-d conformal radiotherapy, intensity modulated radiation therapy and recently proton therapy are able to precisely cover the target while preserving surrounding tissue,Tumour controls between 80 and in access of 90 % can be achieved. Alternative treatments consisting of radiosurgery, intracavitary application of isotopes and brachytherapy also offer an acceptable tumour control and might be given in selected cases. More research is needed to establish the role of each treatment modality.

Bayesian approach in MN low dose of radiation counting

International Nuclear Information System (INIS)

Serna Berna, A.; Alcaraz, M.; Acevedo, C.; Navarro, J. L.; Alcanzar, M. D.; Canteras, M.

2006-01-01

The Micronucleus assay in lymphocytes is a well established technique for the assessment of genetic damage induced by ionizing radiation. Due to the presence of a natural background of MN the net MN is obtained by subtracting this value to the gross value. When very low doses of radiation are given the induced MN is close even lower than the predetermined background value. Furthermore, the damage distribution induced by the radiation follows a Poisson probability distribution. These two facts pose a difficult task to obtain the net counting rate in the exposed situations. It is possible to overcome this problem using a bayesian approach, in which the selection of a priori distributions for the background and net counting rate plays an important role. In the present work we make a detailed analysed using bayesian theory to infer the net counting rate in two different situations: a) when the background is known for an individual sample, using exact value value for the background and Jeffreys prior for the net counting rate, and b) when the background is not known and we make use of a population background distribution as background prior function and constant prior for the net counting rate. (Author)

A Bayesian approach to in silico blood-brain barrier penetration modeling.

Science.gov (United States)

Martins, Ines Filipa; Teixeira, Ana L; Pinheiro, Luis; Falcao, Andre O

2012-06-25

The human blood-brain barrier (BBB) is a membrane that protects the central nervous system (CNS) by restricting the passage of solutes. The development of any new drug must take into account its existence whether for designing new molecules that target components of the CNS or, on the other hand, to find new substances that should not penetrate the barrier. Several studies in the literature have attempted to predict BBB penetration, so far with limited success and few, if any, application to real world drug discovery and development programs. Part of the reason is due to the fact that only about 2% of small molecules can cross the BBB, and the available data sets are not representative of that reality, being generally biased with an over-representation of molecules that show an ability to permeate the BBB (BBB positives). To circumvent this limitation, the current study aims to devise and use a new approach based on Bayesian statistics, coupled with state-of-the-art machine learning methods to produce a robust model capable of being applied in real-world drug research scenarios. The data set used, gathered from the literature, totals 1970 curated molecules, one of the largest for similar studies. Random Forests and Support Vector Machines were tested in various configurations against several chemical descriptor set combinations. Models were tested in a 5-fold cross-validation process, and the best one tested over an independent validation set. The best fitted model produced an overall accuracy of 95%, with a mean square contingency coefficient (ϕ) of 0.74, and showing an overall capacity for predicting BBB positives of 83% and 96% for determining BBB negatives. This model was adapted into a Web based tool made available for the whole community at http://b3pp.lasige.di.fc.ul.pt.

Proceedings of the international conference on radiation biology and clinical applications: a molecular approach towards innovations in applied radiobiology and a workshop on strategies in radiation research

International Nuclear Information System (INIS)

2013-10-01

Innovations in radiotherapy approaches to cancer and radiation biology research is of growing interest in radiation researchers to conduct preclinical studies at their centers and translating the results as soon as possible to clinical radiotherapy practice. Recent papers have greatly enriched the current knowledge of radiation oncology, especially radiobiology and molecular oncology, and this has radically changed the oncology practice in radiation therapy in just a few years. The conference theme highlights the molecular and cellular responses within tissue and higher levels of mammalian biological organization. New experimental radiobiology research to underpin current and future regulatory decisions setting workplace exposure limits. To develop rapid, high-precision analytical methods that assess radiation exposure doses from clinical samples and thus aid in the triage and medical management of radiological casualties. Innovative approaches to improve the accuracy, dose range, ease of use, and speed of classical biodosimetry. Papers relevant to INIS are indexed separately

Radiation transmission data for radionuclides and materials relevant to brachytherapy facility shielding.

Science.gov (United States)

Papagiannis, P; Baltas, D; Granero, D; Pérez-Calatayud, J; Gimeno, J; Ballester, F; Venselaar, J L M

2008-11-01

To address the limited availability of radiation shielding data for brachytherapy as well as some disparity in existing data, Monte Carlo simulation was used to generate radiation transmission data for 60Co, 137CS, 198Au, 192Ir 169Yb, 170Tm, 131Cs, 125I, and 103pd photons through concrete, stainless steel, lead, as well as lead glass and baryte concrete. Results accounting for the oblique incidence of radiation to the barrier, spectral variation with barrier thickness, and broad beam conditions in a realistic geometry are compared to corresponding data in the literature in terms of the half value layer (HVL) and tenth value layer (TVL) indices. It is also shown that radiation shielding calculations using HVL or TVL values could overestimate or underestimate the barrier thickness required to achieve a certain reduction in radiation transmission. This questions the use of HVL or TVL indices instead of the actual transmission data. Therefore, a three-parameter model is fitted to results of this work to facilitate accurate and simple radiation shielding calculations.

Blood-brain barrier permeation in the rat during exposure to low-power 1.7-GHz microwave radiation

International Nuclear Information System (INIS)

Ward, T.R.; Ali, J.S.

1985-01-01

The permeability of the blood-brain barrier to high-and low-molecular-weight compounds has been measured as a function of continuous-wave (CW) and pulsed-microwave radiation. Adult rats, anesthetized with pentobarbital and injected intravenously with a mixture of [ 14 C] sucrose and [ 3 H] inulin, were exposed for 30 min at a specific absorption rate of 0.1 W/kg to 1.7-GHz CW and pulsed (0.5-microseconds pulse width, 1,000 pps) microwaves. After exposure, the brain was perfused and sectioned into nine regions, and the radioactivity in each region was counted. During identical exposure conditions, temperatures of rats were measured in eight of the brain regions by a thermistor probe that did not perturb the field. No change in uptake of either tracer was found in any of the eight regions as compared with those of sham-exposed animals

Nuclear reorganization barriers to electron transfer

International Nuclear Information System (INIS)

Sutin, N.; Brunschwig, B.S.; Creutz, C.; Winkler, J.R.

1988-01-01

The nuclear barrier to electron transfer arises from the need for reorganization of intramolecular and solvent internuclear distances prior to electron transfer. For reactions with relatively small driving force (''normal'' free-energy region) the nuclear factors and rates increase as intrinsic inner-shell and outer-shell barriers decrease; this is illustrated by data for transition metal complexes in their ground electronic states. By contrast, in the inverted free-energy region, rates and nuclear factors decrease with decreasing ''intrinsic'' barriers; this is illustrated by data for the decay of charge-transfer excited states. Several approaches to the evaluation of the outer-shell barrier are explored in an investigation of the distance dependence of the nuclear factor in intramolecular electron-transfer processes. 39 refs., 14 figs., 3 tabs

Comparative evaluation of different approaches to environmental protection against ionising radiation in view of practicability and consistency

International Nuclear Information System (INIS)

Steiner, M.; Hornung, L.; Mundigl, S.; Kirchner, G.

2006-01-01

International organisations, including ICRP, IAEA and UNSCEAR, and the international scientific community are currently engaged in work on the protection of non-human species against ionising radiation as a complement to the existing framework centred on humans. The basic ideas and conceptual approaches developed during the last decade substantially agree with each other. The EC funded FASSET project (Framework for Assessment of Environmental Impact) summarizes and reviews the current knowledge of radiation effects on biota, provides basic dosimetric models for fauna and flora and suggests an assessment framework. Protection of the environment against ionising radiation, on the one hand, aims to close a conceptual gap in radiation protection. Therefore, current frameworks for environmental protection conceptually follow radiation protection of man. On the other hand, preservation of natural resources, habitats and the biological diversity are common objectives of environmental protection against radioactive as well as chemical pollutants, suggesting an integrated approach based on the fundamental ideas of conventional environmental protection. In essence, a conceptual framework encompassing protection of man as well as of fauna and flora against chemical and radioactive pollutants would be highly desirable in view of coherence, consistency and transparency. Such an umbrella concept communicates the positive message that similar issues are treated in a conceptually similar manner, thus facilitating scientific justification and public communication and increasing acceptance. This paper discusses different concepts and approaches to radiation protection of man, radiation protection of non-human biota and environmental protection against chemical pollutants, identifies common principles and differences, addresses conflicting requirements and evaluates the feasibility and limitations of such an encompassing framework. (authors)

Barriers to guideline-compliant psoriasis care: analyses and concepts.

Science.gov (United States)

Eissing, L; Radtke, M A; Zander, N; Augustin, M

2016-04-01

Despite the availability of effective therapeutics and evidence-based treatment guidelines, a substantial proportion of patients with moderate-to-severe psoriasis does not receive appropriate care. This under-provision of health care may cause further worsening of health, remarkable limitations of the patient's quality of life, and indirect costs for the health care system. In order to provide guideline-compliant care for every psoriasis patient, it is important to identify barriers obstructing optimal care. Studies have identified various barriers on the physician's and on the patient's side; however, respective studies approached only single barriers, and not all of them in the context of psoriasis. Other publications that describe barriers systematically did not focus on psoriasis either. The objective of this literature review was to identify barriers and facilitators, based on studies analysing quality of care and single barriers, resulting in a comprehensive model of causal factors. Our analyses revealed three categories of barriers - patient-related, physician-related and external factors: On the patient side, we found non-adherence to therapies to be an important barrier, often in close association with psychiatric factors. Barriers on the physician's side predominantly are incomplete knowledge of the guidelines as well as the complexity of psoriasis comorbidity. In some countries, payment for patients with complex disease status is poor and inconsistent reimbursement regulations potentially interfere with optimal care. The current analysis indicates that most barriers are interdependent. Thus, measures approaching related barriers simultaneously are required. To improve care for psoriasis patients, further studies systematically addressing all potentially relevant barriers in conjoint are needed. © 2015 European Academy of Dermatology and Venereology.

Radiation-Induced Astrogliosis and Blood-Brain Barrier Damage Can Be Abrogated Using Anti-TNF Treatment

International Nuclear Information System (INIS)

Wilson, Christy M.; Gaber, M. Waleed; Sabek, Omaima M.; Zawaski, Janice A.; Merchant, Thomas E.

2009-01-01

Purpose: In this article, we investigate the role of tumor necrosis factor-alpha (TNF) in the initiation of acute damage to the blood-brain barrier (BBB) and brain tissue following radiotherapy (RT) for CNS tumors. Methods and Materials: Intravital microscopy and a closed cranial window technique were used to measure quantitatively BBB permeability to FITC-dextran 4.4-kDa molecules, leukocyte adhesion (Rhodamine-6G) and vessel diameters before and after 20-Gy cranial radiation with and without treatment with anti-TNF. Immunohistochemistry was used to quantify astrogliosis post-RT and immunofluorescence was used to visualize protein expression of TNF and ICAM-1 post-RT. Recombinant TNF (rTNF) was used to elucidate the role of TNF in leukocyte adhesion and vessel diameter. Results: Mice treated with anti-TNF showed significantly lower permeability and leukocyte adhesion at 24 and 48 h post-RT vs. RT-only animals. We observed a significant decrease in arteriole diameters at 48 h post-RT that was inhibited in TNF-treated animals. We also saw a significant increase in activated astrocytes following RT that was significantly lower in the anti-TNF-treated group. In addition, immunofluorescence showed protein expression of TNF and ICAM-1 in the cerebral cortex that was inhibited with anti-TNF treatment. Finally, administration of rTNF induced a decrease in arteriole diameter and a significant increase in leukocyte adhesion in venules and arterioles. Conclusions: TNF plays a significant role in acute changes in BBB permeability, leukocyte adhesion, arteriole diameter, and astrocyte activation following cranial radiation. Treatment with anti-TNF protects the brain's microvascular network from the acute damage following RT.

Ethics, genetics and dynamics: an emerging systematic approach to radiation protection of the environment

International Nuclear Information System (INIS)

Pentreath, R.J.

2004-01-01

There is now a general consensus of opinion that an explicit approach is necessary to demonstrate radiation protection of the environment, and that this approach needs to be developed in a systematic way. The framework that is emerging links ethical and moral issues (anthropocentric, biocentric, and ecocentric) to broad-based principles and objectives of environmental protection (sustainable development, maintaining biological diversity, and habitat protection) and then links these, in turn, to the needs of current environmental management practices, such as environmental exploitation, pollution control, and nature conservation. The relevance of this to radiation is that its effects (such as causing early mortality, morbidity, reduced reproductive success, as well as resulting in observable (scorable) cytogenetic damage) are those that may have a bearing on these same environmental management practices. The devise that would appear to be most useful to bridge the gap between our disparate data on radiation effects and the needs of environmental management, is that of adding to the concept of Reference Man in the shape of a small set of Reference Animals and Plants. This approach has now been adopted by the ICRP, adding new dynamics--the motive forces, both moral and physical--to the subject. The way is now clear for rapid progress to be made on a number of fronts

Approach and organisation of radiation sources safety and security of installations

International Nuclear Information System (INIS)

Al-Hilali, S.

1998-01-01

Development of application of techniques using radiation sources was fact in all public domains. Although all these techniques were meant for so called peaceful uses they should respect safety regulations in order to ensure safety of personnel, public and the environment. Security system for installations adopted by CNESTEN is based on establishing administrative and technical protection of the installation against external or internal aggression on one hand and protection of the environment by confining radioactivity, on the other hand. Application of Methode Organisee et Systematique d'analyse de risque (MOSAR) at the installations of CNESTEN showed weak points in order to define barriers for prevention and means necessary for management and dealing with accidental situations. At the first stage this attitude was limited to qualitative considerations adopting macroscopic analysis of each installation. Experience obtained from operation of these installation, which have started operation hardly a few months ago, would establish a real database indispensable for complete risk analysis including quantification of possible risks

Representing solute transport through the multi-barrier disposal system by simplified concepts

International Nuclear Information System (INIS)

Poteri, A.; Nordman, H.; Pulkkanen, V-M.; Kekaelaeinen, P.; Hautojaervi, A.

2012-02-01

The repository system chosen in Finland for spent nuclear fuel is composed of multiple successive transport barriers. If a waste canister is leaking, this multi-barrier system retards and limits the release rates of radionuclides into the biosphere. Analysis of radionuclide migration in the previous performance assessments has largely been based on numerical modelling of the repository system. The simplified analytical approach introduced here provides a tool to analyse the performance of the whole system using simplified representations of the individual transport barriers. This approach is based on the main characteristics of the individual barriers and on the generic nature of the coupling between successive barriers. In the case of underground repository the mass transfer between successive transport barriers is strongly restricted by the interfaces between barriers leading to well-mixed conditions in these barriers. The approach here simplifies the barrier system so that it can be described with a very simple compartment model, where each barrier is represented by a single, or in the case of buffer, by not more than two compartments. This system of compartments could be solved in analogy with a radioactive decay chain. The model of well mixed compartments lends itself to a very descriptive way to represent and analyse the barrier system because the relative efficiency of the different barriers in hindering transport of solutes can be parameterised by the solutes half-times in the corresponding compartments. In a real repository system there will also be a delay between the start of the inflow and the start of the outflow from the barrier. This delay can be important for the release rates of the short lived and sorbing radionuclides, and it was also included in the simplified representation of the barrier system. In a geological multi-barrier system, spreading of the outflowing release pulse is often governed by the typical behaviour of one transport barrier

Representing solute transport through the multi-barrier disposal system by simplified concepts

Energy Technology Data Exchange (ETDEWEB)

Poteri, A.; Nordman, H.; Pulkkanen, V-M. [VTT Technical Research Centre of Finland, Espoo (Finland); Kekaelaeinen, P. [Jyvaeskylae Univ. (Finland). Dept. pf Physics; Hautojaervi, A.

2012-02-15

The repository system chosen in Finland for spent nuclear fuel is composed of multiple successive transport barriers. If a waste canister is leaking, this multi-barrier system retards and limits the release rates of radionuclides into the biosphere. Analysis of radionuclide migration in the previous performance assessments has largely been based on numerical modelling of the repository system. The simplified analytical approach introduced here provides a tool to analyse the performance of the whole system using simplified representations of the individual transport barriers. This approach is based on the main characteristics of the individual barriers and on the generic nature of the coupling between successive barriers. In the case of underground repository the mass transfer between successive transport barriers is strongly restricted by the interfaces between barriers leading to well-mixed conditions in these barriers. The approach here simplifies the barrier system so that it can be described with a very simple compartment model, where each barrier is represented by a single, or in the case of buffer, by not more than two compartments. This system of compartments could be solved in analogy with a radioactive decay chain. The model of well mixed compartments lends itself to a very descriptive way to represent and analyse the barrier system because the relative efficiency of the different barriers in hindering transport of solutes can be parameterised by the solutes half-times in the corresponding compartments. In a real repository system there will also be a delay between the start of the inflow and the start of the outflow from the barrier. This delay can be important for the release rates of the short lived and sorbing radionuclides, and it was also included in the simplified representation of the barrier system. In a geological multi-barrier system, spreading of the outflowing release pulse is often governed by the typical behaviour of one transport barrier

Protecting the radiation-damaged skin from friction: a mini review

International Nuclear Information System (INIS)

Herst, Patries M

2014-01-01

Radiation-induced skin reactions are an unavoidable side effect of external beam radiation therapy, particularly in areas prone to friction and excess moisture such as the axilla, head and neck region, perineum and skin folds. Clinical studies investigating interventions for preventing or managing these reactions have largely focussed on formulations with moisturising, anti-inflammatory, anti-microbial and wound healing properties. However, none of these interventions has emerged as a consistent candidate for best practice. Much less emphasis has been placed on evaluating ways to protect the radiation-damaged skin from friction and excess moisture. This mini review analyses the clinical evidence for barrier products that form a protective layer by adhering very closely to the skin folds and do not cause further trauma to the radiation-damaged skin upon removal. A database search identified only two types of barrier products that fitted these criteria and these were tested in two case series and six controlled clinical trials. Friction protection was most effective when the interventions were used from the start of treatment and continued for several weeks after completion of treatment. Soft silicone dressings (Mepilex Lite and Mepitel Film) and Cavilon No Sting Barrier Film, but not Cavilon Moisturizing Barrier Cream, decreased skin reaction severity, most likely due to differences in formulation and skin build-up properties. It seems that prophylactic use of friction protection of areas at risk could be a worthwhile addition to routine care of radiation-damaged skin

Assessment of psychological barriers to cervical cancer screening ...

African Journals Online (AJOL)

EB

among women in Kumasi, Ghana using a mixed methods approach. *Williams M1 ... Conclusion: The results of this study can be used to inform the development of culturally relevant cervical cancer education ... psychological barriers, and specific cultural barriers to ... Technology reviewed the interview guide to establish.

Women leadership barriers in healthcare, academia and business

OpenAIRE

Kalaitzi, S.; Czabanowska, K.; Fowler-Davis, S.; Brand, H.

2017-01-01

Purpose\\ud \\ud \\ud \\ud This paper maps the barriers to women leadership across healthcare, academia and business, and identifies barriers prevalence across sectors. A Barriers Thematic Map (BTM), with quantitative logic, and a prevalence chart have been developed, with the aim to uncover inequalities and provide orientation to develop inclusion and equal opportunity strategies within different work environments.\\ud \\ud \\ud \\ud \\ud Design/methodology/approach\\ud \\ud \\ud A systematic literature...

Efficient weakly-radiative wireless energy transfer: An EIT-like approach

International Nuclear Information System (INIS)

Hamam, Rafif E.; Karalis, Aristeidis; Joannopoulos, J.D.; Soljacic, Marin

2009-01-01

Inspired by a quantum interference phenomenon known in the atomic physics community as electromagnetically induced transparency (EIT), we propose an efficient weakly radiative wireless energy transfer scheme between two identical classical resonant objects, strongly coupled to an intermediate classical resonant object of substantially different properties, but with the same resonance frequency. The transfer mechanism essentially makes use of the adiabatic evolution of an instantaneous (so called 'dark') eigenstate of the coupled 3-object system. Our analysis is based on temporal coupled mode theory (CMT), and is general enough to be valid for various possible sorts of coupling, including the resonant inductive coupling on which witricity-type wireless energy transfer is based. We show that in certain parameter regimes of interest, this scheme can be more efficient, and/or less radiative than other, more conventional approaches. A concrete example of wireless energy transfer between capacitively-loaded metallic loops is illustrated at the beginning, as a motivation for the more general case. We also explore the performance of the currently proposed EIT-like scheme, in terms of improving efficiency and reducing radiation, as the relevant parameters of the system are varied.

Decommissioning an uranium and thorium facility: a radiation protection approach

International Nuclear Information System (INIS)

Feijo Vasques, Francisco Mario; Saburo Todo, Alberto; Mestre, Paulo Antonio

2008-01-01

Decommissioning means actions taken at the end of the useful life of a facility in retiring it from service with adequate regard for the health and safety of workers and members of the public. In the present work, we introduce a radiation protection approach for the removal of radioactive material to the extent that the facility or site becomes available for use without restriction. The facility to be decommissioned is a fuel cycle pilot plant that operated with natural uranium and thorium for almost two decades and then, kept inactive for about 10 years at the Nuclear and Energy Research Institute - IPEN. Even after this long period of inactivity, it has presented significant levels of radiation and contamination spread over the floor, walls, windows, doors and ceiling. The fuel cycle pilot plant was completely dismantled, remaining only the walls and the concrete structures. In this work we present the job done to restore the area. According to each step of dismantling a continuous monitoring of the contaminated surfaces was carried out including the survey of the deep material from the floor and walls. The material identified as radioactive waste was stored into appropriated metal drums. A radiation protection team guided this stage of the work, prescribing the tasks, and the amount of material that should be removed from floors, windows and ceiling. For this, repetitive surveys had to be done. The results of monitoring and contamination levels were analysed, thus guiding the next steps of the job. In this way radiation protection team took over the tasks, running the work with the purpose of achieving acceptable levels of radiation, restoring the area for unrestricted use. (author)

Barriers to Education for the Marginalized Adult Learner

Science.gov (United States)

Flynn, Sarah; Brown, Jason; Johnson, Andrew; Rodger, Susan

2011-01-01

This qualitative study examines barriers to adult education by the marginalized adult learner. We adopted an inclusive approach by interviewing potential adult learners who had not participated in adult education programs due to illiteracy. Five overlapping themes related to barriers emerged and were categorized as: family values and…

Herbal medicines that benefit epidermal permeability barrier function

Directory of Open Access Journals (Sweden)

Lizhi Hu

2015-06-01

Full Text Available Epidermal permeability barrier function plays a critical role in regulating cutaneous functions. Hence, researchers have been searching for effective and affordable regimens to enhance epidermal permeability barrier function. In addition to topical stratum corneum lipids, peroxisome proliferator-activated receptor, and liver X receptor ligands, herbal medicines have been proven to benefit epidermal permeability barrier function in both normal and diseased skin, including atopic dermatitis, glucocorticoid-induced skin damage, and UVB-damaged skin. The potential mechanisms by which herbal medicines improve the permeability barrier include stimulation of epidermal differentiation, lipid production, antimicrobial peptide expression, and antioxidation. Therefore, utilization of herbal medicines could be a valuable alternative approach to enhance epidermal permeability barrier function in order to prevent and/or treat skin disorders associated with permeability barrier abnormalities.

12C+16O: Properties of sub-barrier resonance γ-decay

International Nuclear Information System (INIS)

Goasduff, A.; Courtin, S.; Haas, F.; Lebhertz, D.; Jenkins, D. G.; Fallis, J.; Ruiz, C.; Hutcheon, D. A.; Amandruz, P.-A.; Davis, C.; Hager, U.; Ottewell, D.; Ruprecht, G.

2012-01-01

In a recent experiment performed at Triumf using the Dragon 0° spectrometer and its associated BGO array, the complete γ-decay of the radiative capture channel below the Coulomb barrier has been measured for the first time. This measurement has been performed at two energies E c.m. = 6.6 and 7.2 MeV. A selective contribution of the entrance spins 2 + and 3 − has been evidenced which is consistent with existing results above the barrier.

Benchmarking the interactions among barriers in third-party logistics implementation

DEFF Research Database (Denmark)

Diabat, A.; Khreishah, A.; Govindan, Kannan

2013-01-01

Purpose: The purpose of this paper is to analyze the interaction among some of the major barriers that may hinder the implementation of third-party logistics (TPL) in manufacturing industries. Design/methodology/approach: This paper uses an interpretive structural modeling (ISM) methodology...... to analyze the interactions among the barriers. Findings: It is beneficial for the management of any firm to be aware of significant barriers and to diagnose those that could be integral to the organization's future survival. Many works have focused on identifying barriers for TPL implementation, but a model...... for such barriers is lacking. This paper attempts to develop a model for the barriers using an ISM methodology and analyzes the mutual interactions among the barriers. The model differentiates between the barriers so that driving barriers, which can intensify other barriers, and dependent barriers are identified...

Theoretical modeling of transport barriers in helical plasmas

International Nuclear Information System (INIS)

Toda, S.; Itoh, K.; Ohyabu, N.

2008-10-01

A unified transport modelling to explain electron Internal Transport Barriers (e-ITB) in helical plasmas and Internal Diffusion Barriers (IDB) observed in Large Helical Device (LHD) is proposed. The e-ITB can be predicted with the effect of zonal flows to obtain the e-ITB in the low collisional regime when the radial variation of the particle anomalous diffusivity is included. Transport analysis in this article can newly show that the particle fuelling induces the IDB formation when this unified transport modelling is used in the high collisional regime. The density limit for the IDB in helical plasmas is also examined including the effect of the radiation loss. (author)

Mine support, radiation and ventiliation control with spray-on barriers

International Nuclear Information System (INIS)

Archibald, J.F.; De Souza, E.M.

1993-01-01

The use of spray-on linear agents to provide localized excavation support in place of traditional techniques as shotcrete or bolts-and-screen has been the subject of extensive investigation. Several agent materials have been assessed for use in underground excavation support situations, with optimal performance being shown by a polyurethane-based composition designated Mineguard trademark by its developer. In addition to demonstrating exceptional rock support capabilities, this material has also been shown to be capable of significantly reducing levels of radon flux and diffusion flow occurring from highly emanating source environments. The radon impermeability characteristics of Mineguard trademark offers potential for its use in creating effective barriers to naturally-occurring radon flows which typically develop both in underground uranium and non-uranium mines. Laboratory, ventilation investigations have also provided detailed information concerning Mineguard trademark material friction factor, surface roughness and airflow resistance characteristics. The evaluation of friction factor conditions was used to determine potential power and ventilation cost reduction capabilities possible to be achieved when airways may be lined with such spray-on-barrier materials

Modeling of a Ne/Xe dielectric barrier discharge excilamp for improvement of VUV radiation production

Science.gov (United States)

Khodja, K.; Belasri, A.; Loukil, H.

2017-08-01

This work is devoted to excimer lamp efficiency optimization by using a homogenous discharge model of a dielectric barrier discharge in a Ne-Xe mixture. The model includes the plasma chemistry, electrical circuit, and Boltzmann equation. In this paper, we are particularly interested in the electrical and kinetic properties and light output generated by the DBD. Xenon is chosen for its high luminescence in the range of vacuum UV radiation around 173 nm. Our study is motivated by interest in this type of discharge in many industrial applications, including the achievement of high light output lamps. In this work, we used an applied sinusoidal voltage, frequency, gas pressure, and concentration in the ranges of 2-8 kV, 10-200 kHz, 100-800 Torr, and 10-50%, respectively. The analyzed results concern the voltage V p across the gap, the dielectric voltage V d, the discharge current I, and the particles densities. We also investigated the effect of the electric parameters and xenon concentration on the lamp efficiency. This investigation will allow one to find out the appropriate parameters for Ne/Xe DBD excilamps to improve their efficiency.

Cross-Cultural Differences in Undergraduate Students' Perceptions of Online Barriers

Science.gov (United States)

Olesova, Larisa; Yang, Dazhi; Richardson, Jennifer C.

2011-01-01

The intent of this study was to learn about students' perceived barriers and the impact of those barriers on the quality of online discussions between two distinct cultural groups in Eastern and Northern Siberia (Russia). A mixed-methods approach utilizing surveys and interviews was used to investigate (1) the types of barriers the students…

Radiation protection training award - an innovative approach of testing radiation protection skills in catastrophe management

International Nuclear Information System (INIS)

Geringer, T.

2003-01-01

own emergency planning. ARCS Bronze award consists of 4 practical exercises followed by a theoretical test. The praxis requirements include the detection and identification of a radioactive source, application of a low level gamma monitor, principles of personnel monitoring, control of external hazard as well as taking environmental samples. Theoretical testing ranges from the nature of radioactivity and radiation units to the legislation related to radiological protection. Evaluation is given in an objective numeric grading. The Silver award includes the treatment of nuclear emergencies such as the detonation of a nuclear weapon, an accident in a radionuclid/ isotop lab or an accident in a nuclear plant. The candidates have also to present their skills in handling an transportation accident, arranging immediate catastrophe management. The candidates' background ranged from security force members to academics. The problem of harmonized training standards is, especially since the September 11 th attacks, a worldwide need. Security forces have to show their practical knowledge and secure their theoretical background to eventually update their skills. The protection of the general population can only be ensured by a homogenous training as well as perfect collaboration of the security units. Therefore an intensive training of the security guards performed by specialists must be guaranteed. ARCS radiation protection awards can be seen as the motivational background to this approach. Also the social component must not be neglected since the period of training at ARCS offers a perfect environment for interdisciplinary discussion. Safety culture and training experiences in the field of radiation protection in Austria depend an such an information system and ARCS has shown experience in that field for decades. Innovative approaches in training and sharing information as well as experience are seen as important tools to maintain safety culture. Harmonization and national

Therapeutic benefits of enhancing permeability barrier for atopic eczema

Directory of Open Access Journals (Sweden)

George Man

2015-06-01

Full Text Available The regulatory role of epidermal permeability barrier function in cutaneous inflammation has been well appreciated. While barrier disruption induces cutaneous inflammation, improvement of permeability barrier function alleviates inflammation. Studies have demonstrated that improvement of epidermal permeability barrier function not only prevents the development of atopic eczema, but also delays the relapse of these diseases. Moreover, enhancing the epidermal permeability barrier also alleviates atopic eczema. Furthermore, co-applications of barrier enhancing products with glucocorticoids can increase the therapeutic efficacy and reduce the adverse effects of glucocorticoids in the treatment of atopic eczema. Therefore, utilization of permeability barrier enhancing products alone or in combination with glucocorticoids could be a valuable approach in the treatment of atopic eczema. In this review, we discuss the benefits of improving the epidermal permeability barrier in the management of atopic eczema.

Multidisciplinary approach to radiation late effects in the brain circulatory system: First results

International Nuclear Information System (INIS)

Keyeux, A.J.M.; Reinhold, H.S.; Gerber, G.B.; Maisin, J.R.; Reyners, H.; Gianfelici de Reyners, E.; Calvo, W.

1976-01-01

Although acute vascular damage and the early functional impairment of the central nervous system has been studied relatively frequently, the pathophysiological mechanisms of late radiation effects and their relevance to vascular damage, are less well investigated and are poorly understood. As the possibility of later radiation damage is a factor which limits the therapist in the radiation dose, he can give to effect a local tumour cure, it is essential that the mechanisms and importance of vascular irradiation damage be determined before late effects can either be treated or avoided. In view of the inconclusive results obtained by previous authors, it was felt that a multidisciplinary approach might better be suited to solve this problem. Thus, in 1973 a research project was initiated by EULEP to investigate the origins and consequences of radiation induced vascular changes after local irradiation of the brain. In this preliminary report, data on morphological, circulatory and biochemical parameters are presented and discussed. (GC)

A modelling approach to designing microstructures in thermal barrier coatings

International Nuclear Information System (INIS)

Gupta, M.; Nylen, P.; Wigren, J.

2013-01-01

Thermomechanical properties of Thermal Barrier Coatings (TBCs) are strongly influenced by coating defects, such as delaminations and pores, thus making it essential to have a fundamental understanding of microstructure-property relationships in TBCs to produce a desired coating. Object-Oriented Finite element analysis (OOF) has been shown previously as an effective tool for evaluating thermal and mechanical material behaviour, as this method is capable of incorporating the inherent material microstructure as input to the model. In this work, OOF was used to predict the thermal conductivity and effective Young's modulus of TBC topcoats. A Design of Experiments (DoE) was conducted by varying selected parameters for spraying Yttria-Stabilised Zirconia (YSZ) topcoat. The microstructure was assessed with SEM, and image analysis was used to characterize the porosity content. The relationships between microstructural features and properties predicted by modelling are discussed. The microstructural features having the most beneficial effect on properties were sprayed with a different spray gun so as to verify the results obtained from modelling. Characterisation of the coatings included microstructure evaluation, thermal conductivity and lifetime measurements. The modelling approach in combination with experiments undertaken in this study was shown to be an effective way to achieve coatings with optimised thermo-mechanical properties.

Barriers of lean construction implementation in the Moroccan construction industry

Science.gov (United States)

Bajjou, Mohamed Saad; Chafi, Anas

2018-04-01

Improving the production system performance has become a fundamental pillar that must be taken into consideration in the construction industry. Recent developments in the construction sector have led to renewed interest in new techniques of management. Lean Construction is a very effective approach that has gained a high popularity by its ability to eliminate waste and maximize the value for the customer. Although both developed and developing countries have gained large benefits by implementing Lean Construction approach, several experiences showed many barriers that are hindering its implementation especially in developing countries. This paper aims to assess the critical barriers to the successful implementation in the Moroccan construction industry. Based on a literature review, followed by an analysis of data collected from a questionnaire survey which targeted 330 practitioners in the Moroccan construction field, several barriers were identified as key barriers. The findings of this investigation revealed that there are significant barriers such as Lack of knowledge about Lean Construction concepts, Unskilled Human Resources, and insufficient financial resources.

Barriers to and Facilitators of the Evaluation of Integrated Community-Wide Overweight Intervention Approaches: A Qualitative Case Study in Two Dutch Municipalities

Science.gov (United States)

van Koperen, Tessa M.; de Kruif, Anja; van Antwerpen, Lisa; Hendriks, Anna-Marie; Seidell, Jacob C.; Schuit, Albertine J.; Renders, Carry M.

2016-01-01

To prevent overweight and obesity the implementation of an integrated community-wide intervention approach (ICIA) is often advocated. Evaluation can enhance implementation of such an approach and demonstrate the extent of effectiveness. To be able to support professionals in the evaluation of ICIAs we studied barriers to and facilitators of ICIA evaluation. In this study ten professionals of two Dutch municipalities involved in the evaluation of an ICIA participated. We conducted semi-structured interviews (n = 12), observed programme meetings (n = 4) and carried out document analysis. Data were analyzed using a thematic content approach. We learned that evaluation is hampered when it is perceived as unfeasible due to limited time and budget, a lack of evaluation knowledge or a negative evaluation attitude. Other barriers are a poor understanding of the evaluation process and its added value to optimizing the programme. Sufficient communication between involved professionals on evaluation can facilitate evaluation, as does support for evaluation of ICIAs together with stakeholders at a strategic and tactical level. To stimulate the evaluation of ICIAs, we recommend supporting professionals in securing evaluation resources, providing tailored training and tools to enhance evaluation competences and stimulating strategic communication on evaluation. PMID:27043600

Population-genetic approach to standardization of radiation and non-radiation factors

International Nuclear Information System (INIS)

Telnov, I.

2006-01-01

population level. Of 65 analyses of association between diseases and unfavorable effects and various genetic polymorphic systems, 27 had negative results. Other 38 had significant, i.e. positive results. Respective G.S.R.R. varied accordingly in the range from 1.2 to 2.5. Averaged G.S.R.R. for some genetic systems ranged from 1.4 to 1.9. More stable and closer values of averaged G.S.R.R. calculated for various categories of effects: pathologies due to radiation and non-radiation factors - 1.51; non-tumor (1,47) and tumor (1,54) diseases; average life expectancy - 1.34. Population-averaged or integral value of G.S.R.R. was about 1.5. This value can be used as genetic predisposition coefficient (C.G.P.) for correction in averaging of environmental population level factors. Such correction can be done by decreasing of permissible standard value by the value of C.G.P. to calculate population-genetic standard. It should be noted that population-genetic standards decrease risk of development of unfavorable consequences due to effect of environmental factors in individuals with genetic predisposition to the general population level. An important advantage of this approach is that there is no need to account for all existing variations of genetic predisposition to multiform unfavorable environmental factors

Could tight junctions regulate the barrier function of the aged skin?

Science.gov (United States)

Svoboda, Marek; Bílková, Zuzana; Muthný, Tomáš

2016-03-01

The skin is known to be the largest organ in human organism creating interface with outer environment. The skin provides protective barrier against pathogens, physical and chemical insults, and against uncontrolled loss of water. The barrier function was primarily attributed to the stratum corneum (SC) but recent studies confirmed that epidermal tight junctions (TJs) also play important role in maintaining barrier properties of the skin. Independent observations indicate that barrier function and its recovery is impaired in aged skin. However, trans-epidermal water loss (TEWL) values remains rather unchanged in elderly population. UV radiation as major factor of photoageing impairs TJ proteins, but TJs have great self-regenerative potential. Since it may be possible that TJs can compensate TEWL in elderly due to its regenerative and compensatory capabilities, important question remains to be answered: how are TJs regulated during skin ageing? This review provides an insight into TJs functioning as epidermal barrier and summarizes current knowledge about the impact of ageing on the barrier function of the skin and epidermal TJs. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Radiated Emissions Test Approach

Science.gov (United States)

2015-10-02

1. Draft Department of Transportation (DOT) Test Plan to Develop : Interference Tolerance Masks for GNSS Receivers in the L1 : Radiofrequency Band (1559 1610 MHz) provides high level : overview of radiated emissions test setup : 2. Presenta...

Thermal Conductivity of Ceramic Thermal Barrier and Environmental Barrier Coating Materials

Science.gov (United States)

Zhu, Dong-Ming; Bansal, Narottam P.; Lee, Kang N.; Miller, Robert A.

2001-01-01

Thermal barrier and environmental barrier coatings (TBC's and EBC's) have been developed to protect metallic and Si-based ceramic components in gas turbine engines from high temperature attack. Zirconia-yttria based oxides and (Ba,Sr)Al2Si2O8(BSAS)/mullite based silicates have been used as the coating materials. In this study, thermal conductivity values of zirconia-yttria- and BSAS/mullite-based coating materials were determined at high temperatures using a steady-state laser heat flux technique. During the laser conductivity test, the specimen surface was heated by delivering uniformly distributed heat flux from a high power laser. One-dimensional steady-state heating was achieved by using thin disk specimen configuration (25.4 mm diam and 2 to 4 mm thickness) and the appropriate backside air-cooling. The temperature gradient across the specimen thickness was carefully measured by two surface and backside pyrometers. The thermal conductivity values were thus determined as a function of temperature based on the 1-D heat transfer equation. The radiation heat loss and laser absorption corrections of the materials were considered in the conductivity measurements. The effects of specimen porosity and sintering on measured conductivity values were also evaluated.

New approach to radiation monitoring: citizen based radiation measurement

International Nuclear Information System (INIS)

Kuca, P.; Helebrant, J.

2016-01-01

Both the Fukushima Dai-chi NPP accident in Japan in 2011 and the Chernobyl NPP accident in USSR in 1986 similarly to the first one have shown a necessity to find a way how to improve confidence of the public to official authorities. It is important especially in such a case of severe accidents with significant consequences in large inhabited areas around the damaged NPP. A lack of public confidence to officials was caused mostly by rather poor communication between official authorities and the public, as well by restricted access to the information for the public. It may have extremely negative impacts on the public understanding of actual situation and its possible risks, on public acceptance of necessary protective measures and participation of the public in remediation of the affected areas. One of possible ways to improve the situation can be implementation of citizen radiation monitoring on voluntary basis. Making sure, the official results are compatible with public self-measured ones, the public probably has more confidence in them. In the Czech Republic the implementation of such an approach is tested in the framework of security research founded by the Czech Ministry of the Interior - the research project RAMESIS solved by SURO. (authors)

Gynecologic radiation therapy. Novel approaches to image-guidance and management

Energy Technology Data Exchange (ETDEWEB)

Viswanathan, Akila N. [Harvard Medical School, Boston, MA (United States). Dept. of Radiation Oncology; Kirisits, Christian; Poetter, Richard (eds.) [Vienna General Hospital Medical Univ. (Austria). Dept. of Radiotherapy; Erickson, Beth E. [Medical College of Wisconsin Clinics Froedtert Hospital, Milwaukee, WI (United States). Dept. of Radiation Oncology

2011-07-01

Recent advances in the treatment of gynecologic malignancies led to a new worldwide consensus to introduce image guidance to gynecologic radiation therapy, particularly to brachytherapy. The book summarizes the changed practice of management: treatment planning for cervical cancer, not modified for over 60 years, has been shifted to an image-based approach, endometrial cancer management with an increase in the use of chemotherapy and vaginal brachytherapy, and vaginal cancer therapy including image guidance and high-dose delivery with IMRT. (orig.)

A functional genomics approach using radiation-induced changes in gene expression to study low dose radiation effects in vitro and in vivo

Energy Technology Data Exchange (ETDEWEB)

Fornace, Jr, A J

2007-03-03

Abstract for final report for project entitled A functional genomics approach using radiation-induced changes in gene expression to study low dose radiation effects in vitro and in vivo which has been supported by the DOE Low Dose Radiation Research Program for approximately 7 years. This project has encompassed two sequential awards, ER62683 and then ER63308, in the Gene Response Section in the Center for Cancer Research at the National Cancer Institute. The project was temporarily suspended during the relocation of the Principal Investigators laboratory to the Dept. of Genetics and Complex Diseases at Harvard School of Public Health at the end of 2004. Remaining support for the final year was transferred to this new site later in 2005 and was assigned the DOE Award Number ER64065. The major aims of this project have been 1) to characterize changes in gene expression in response to low-dose radiation responses; this includes responses in human cells lines, peripheral blood lymphocytes (PBL), and in vivo after human or murine exposures, as well as the effect of dose-rate on gene responses; 2) to characterize changes in gene expression that may be involved in bystander effects, such as may be mediated by cytokines and other intercellular signaling proteins; and 3) to characterize responses in transgenic mouse models with relevance to genomic stability. A variety of approaches have been used to study transcriptional events including microarray hybridization, quantitative single-probe hybridization which was developed in this laboratory, quantitative RT-PCR, and promoter microarray analysis using genomic regulatory motifs. Considering the frequent responsiveness of genes encoding cytokines and related signaling proteins that can affect cellular metabolism, initial efforts were initiated to study radiation responses at the metabolomic level and to correlate with radiation-responsive gene expression. Productivity includes twenty-four published and in press manuscripts

An efficient approach to characterizing and calculating carrier loss due to heating and barrier height variation in vertical-cavity surface-emitting lasers

International Nuclear Information System (INIS)

Jian, Wu; Summers, H. D.

2010-01-01

It is important to determine quantitatively the internal carrier loss arising from heating and barrier height variation in a vertical-cavity surface-emitting quantum well laser (VCSEL). However, it is generally difficult to realize this goal using purely theoretical formulas due to difficulty in deriving the parameters relating to the quantum well structure. In this paper, we describe an efficient approach to characterizing and calculating the carrier loss due to the heating and the barrier height change in the VCSEL. In the method, the thermal carrier loss mechanism is combined with gain measurement and calculation. The carrier loss is re-characterized in a calculable form by constructing the threshold current and gain detuning-related loss current using the measured gain data and then substituting them for the quantum well-related parameters in the formula. The result can be expressed as a product of an exponential weight factor linked to the barrier height change and the difference between the threshold current and gain detuning-related loss current. The gain variation at cavity frequency due to thermal carrier loss and gain detuning processes is measured by using an AlInGaAs–AlGaAs VCSEL structure. This work provides a useful approach to analysing threshold and loss properties of the VCSEL, particularly, gain offset design for high temperature operation of VCSELs. (classical areas of phenomenology)

Exploring Approaches to Drivers and Barriers of Corporate Social Responsibility Implementation in Academic Literature

Directory of Open Access Journals (Sweden)

Govindasamy Vimala

2017-01-01

Full Text Available CSR implementation is a relatively untapped area of study. Barriers are components that block and test the execution of CSR in an organization while drivers are positive CSR performance indicators. There is a dearth of academic literature of exploration of barriers and drivers of CSR in developing economies. This paper focuses on synthesizing existing scholarly research literature on drivers and barriers of Corporate Social Responsibility from the perspectives of developed and developing economies. With most companies around the world joining the CSR bandwagon in a bid to positively influence their relationships with employees and stakeholders, it is imperative that CSR research addresses the barriers and drivers that companies are likely to face during the implementation of their CSR strategies.

Electromagnetic signatures of far-field gravitational radiation in the 1 + 3 approach

International Nuclear Information System (INIS)

Chua, Alvin J K; Cañizares, Priscilla; Gair, Jonathan R

2015-01-01

Gravitational waves (GWs) from astrophysical sources can interact with background electromagnetic fields, giving rise to distinctive and potentially detectable electromagnetic signatures. In this paper, we study such interactions for far-field gravitational radiation using the 1 + 3 approach to relativity. Linearized equations for the electromagnetic field on perturbed Minkowski space are derived and solved analytically. The inverse Gertsenshteĭn conversion of GWs in a static electromagnetic field is rederived, and the resultant electromagnetic radiation is shown to be significant for highly magnetized pulsars in compact binary systems. We also obtain a variety of nonlinear interference effects for interacting gravitational and electromagnetic waves, although wave–wave resonances previously described in the literature are absent when the electric–magnetic self-interaction is taken into account. The fluctuation and amplification of electromagnetic energy flux as the GW strength increases towards the gravitational–electromagnetic frequency ratio is a possible signature of gravitational radiation from extended astrophysical sources. (paper)

Vulnerability of multiple-barrier systems

International Nuclear Information System (INIS)

Lind, N.C.

1996-01-01

'Vulnerability' is defined as the ratio of the probability of failure of a damaged system to the probability of failure of the undamaged system. This definition applies to all engineered systems and can be specialized to particular system types. Some disastrous failures (e.g., Chernobyl) have shown that systems can be highly vulnerable. open-quotes Defense in depthclose quotes is a powerful design principle, reducing vulnerability when the consequences of failure can be catastrophic. In the nuclear industry, defense in depth is widely used in radiation protection, reactor control, and shutdown systems. A multiple-barrier system is a simple example of a system that has defense in depth. The idea is that the system is not vulnerable. It cannot fail if one barrier fails because there is another to take its place. This idea is untenable in waste management, but a quantified vulnerability of a system can help owners, designers, and regulators decide how much defense in depth is desirable or enough. Many multiple-barrier systems can be modeled as systems of components physically in a series, each individually able to prevent failure. Components typically have bimodal distributions of the service time to failure, as illustrated by an example of application to a hypothetical nuclear fuel waste repository

Experimental Approach of Fault Movement on an Engineered Barrier System

International Nuclear Information System (INIS)

Lee, Minsoo; Choi, Heuijoo; Kim, Heuna

2012-01-01

Safety evaluation of an engineered barrier system against fault movement at underground disposal region for high level waste (HLW) is tried using a miniature bore-shear apparatus. For the purpose, a miniature bore-shear apparatus simulating an EBS (engineered barrier system) was manufactured in 1/30 scale. And using the developed apparatus, bore-shear tests were performed twice. During the tests, pressure variations were checked at 6 points around buffer zone, and then a rotational angle of the test vessel was checked. The achieved pressure data were compared with those from analytical modeling, which is based on Drucker-Prager model. At initial shearing step, high pressure was recorded at some point but it decreased rapidly. For the better understanding of fault movement, the modification of an analytical model and the accumulation of experimental experience were required

Experimental Approach of Fault Movement on an Engineered Barrier System

Energy Technology Data Exchange (ETDEWEB)

Lee, Minsoo; Choi, Heuijoo; Kim, Heuna [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2012-03-15

Safety evaluation of an engineered barrier system against fault movement at underground disposal region for high level waste (HLW) is tried using a miniature bore-shear apparatus. For the purpose, a miniature bore-shear apparatus simulating an EBS (engineered barrier system) was manufactured in 1/30 scale. And using the developed apparatus, bore-shear tests were performed twice. During the tests, pressure variations were checked at 6 points around buffer zone, and then a rotational angle of the test vessel was checked. The achieved pressure data were compared with those from analytical modeling, which is based on Drucker-Prager model. At initial shearing step, high pressure was recorded at some point but it decreased rapidly. For the better understanding of fault movement, the modification of an analytical model and the accumulation of experimental experience were required.

A new approach to radiative transfer theory using Jones's vectors. I

International Nuclear Information System (INIS)

Fymat, A.L.; Vasudevan, R.

1975-01-01

Radiative transfer of partially polarized radiation in an anisotropically scattering, inhomogeneous atmosphere containing arbitrary polydispersion of particles is described using Jones's amplitude vectors and matrices. This novel approach exploits the close analogy between the quantum mechanical states of spin 1/2 systems and the polarization states of electromagnetic radiation described by Jones's vector, and draws on the methodology of such spin 1/2 systems. The complete equivalence between the transport equation for Jones's vectors and the classical radiative transfer equation for Stokes's intensity vectors is demonstrated in two independent ways after deriving the transport equations for the polarization coherency matrices and for the quaternions corresponding to the Jones's vectors. A compact operator formulation of the theory is provided, and used to derive the necessary equations for both a local and a global description of the transport of Jones's vectors. Lastly, the integro-differential equations for the amplitude reflection and transmission matrices are derived, and related to the usual corresponding equations. The present formulation is the most succinct and the most convenient one for both theoretical and experimental studies. It yields a simpler analysis than the classical formulation since it reduces by a factor of two the dimensionality of transfer problems. It preserves information on phases, and thus can be used directly across the entire electromagnetic spectrum without any further conversion into intensities. (Auth.)

Diabatic shifts and fluctuations of heavy-ion fusion barriers

International Nuclear Information System (INIS)

Berdichevsky, D.; Lukasiak, A.; Noerenberg, W.; Rozmej, P.

1988-01-01

The fusion process for heavy nuclei is studied within a generalized formulation of the diabatic approach to collective nuclear motion. It is shown that the coupled equations of motion decouple during the approach if appropriate diabatic channels are used. Thus the mean value and the variance of the barrier are completely determined from an ensemble of diabatic channel barriers, the ensemble being defined by the initial correlations. The mean shift with respect to the adiabatic barrier and the variance are calculated from the splitting of the diabatic single-particle levels at the barrier and the initial occupation probabilities given by the pairing wavefunctions of the separated nuclei. Results are presented for 23 systems of nuclei with masses around 100. Comparison with experimental data shows good agreement, in particular also for the isotopic trends. Additional effects from the destruction of pairing correlations and the diabatic screening of the fusion pocket for heavier nuclei with Z 1 Z 2 > or approx. 2000 are discussed. (orig.)

New Type Far IR and THz Schottky Barrier Detectors for Scientific and Civil Application

Directory of Open Access Journals (Sweden)

V. G. Ivanov

2011-01-01

Full Text Available The results of an experimental investigation into a new type of VLWIR detector based on hot electron gas emission and architecture of the detector are presented and discussed. The detectors (further referred to as HEGED take advantage of the thermionic emission current change effect in a semiconductor diode with a Schottky barrier (SB as a result of the direct transfer of the absorbed radiation energy to the system of electronic gas in the quasimetallic layer of the barrier. The possibility of detecting radiation having the energy of quantums less than the height of the Schottky diode potential barrier and of obtaining a substantial improvement of a cutoff wavelength to VLWIR of the PtSi/Si detector has been demonstrated. The complementary contribution of two physical mechanisms of emanation detection—“quantum” and hot electrons gas emission—has allowed the creation of a superwideband IR detector using standard silicon technology.

Epigenetic approaches towards radiation countermeasure

International Nuclear Information System (INIS)

Agrawala, Paban K.

2012-01-01

In the recent years, histone deacetylase inhibitors (HDACi) have gained tremendous attention for their anticancer, tumor radiosensitising and chemosensitising properties. HDACi enhance the acetylation status of histone proteins of the chromatin besides other non-histone target proteins, an effect that is regulated by the HDACs (histone deacetylases) and HATs (histone acetyltransferases) in the cells. HDACi affect the cell cycle progression, differentiation, DNA damage and repair processes and cell death which contributes to their anticancer properties. One of the main reasons for HDACi gaining attention as potential anticancer therapeutics is their profound action on cancer cells with minimal or no effect on normal cells. However, in recent years, the possible non-oncological applications of HDACi are being explored extensively viz, in neurodegenerative diseases. Ionizing radiation exposure leads to significant alterations in signal transduction processes, changes gene expression patterns, affects DNA damage and repair processes, cell cycle progression and the underlying epigenetic changes (acetylation of histones and methylation of DNA and histones in particular) are now emerging. Some recent literatures suggest that HDACi can render cytoprotective properties in normal tissues. We at INMAS evaluated certain weak HDACi molecules of dietary origin for their ability to modulate cellular radiation in normal cells and animals. As per our expectations, post irradiation treatment with selected HDACi molecules rendered significant reduction in radiation induced damages. The possible mechanisms of action of HDACi in reducing radiation injuries with be discussed based on our won results and recent reports. (author)

SOME OBSERVATIONS ON THE DESIGN OF NOISE BARRIERS

Directory of Open Access Journals (Sweden)

Arkadiusz BOCZKOWSKI

2013-04-01

Full Text Available The issue connected with effectiveness of noise barriers has been the subject of numerous considerations among acousticians. On the one hand, noise barriers are still the most popular and the most frequently used protection against traffic noise, on the other hand, however, the excessive number of noise barriers and the results of research focusing on effectiveness of the existing barriers make us reflect whether it is reasonable to use them. Very often low effectiveness of noise barriers is related to a badly conducted designing process. This article presents the basic mistakes made by noise barriers’ designers and the consequences thereof. Next, the paper describes the appropriate approach to the process of the noise barriers’ design which consists in the use of computer methods and conducting of a detailed analysis of the acoustic field’s distribution both behind the barrier and on the facades of the acoustically protected buildings.

Cancer pain management by radiotherapists: a survey of radiation therapy oncology group physicians

International Nuclear Information System (INIS)

Cleeland, Charles S.; Janjan, Nora A.; Scott, Charles B.; Seiferheld, Wendy F.; Curran, Walter J.

2000-01-01

Purpose: Radiation Therapy Oncology Group (RTOG) physicians were surveyed to determine their approach to and attitudes toward cancer pain management. Methods and Materials: Physicians completed a questionnaire assessing their estimates of the magnitude of pain as a specific problem for cancer patients, their perceptions of the adequacy of pain management, and their report of how they manage pain in their own practice setting. Results: Eighty-three percent believed the majority of cancer patients with pain were undermedicated. Forty percent reported that pain relief in their own practice setting was poor or fair. Assessing a case scenario, 23% would wait until the patient's prognosis was 6 months or less before starting maximal analgesia. Adjuvants and prophylactic side effect management were underutilized in the treatment plan. Barriers to pain management included poor pain assessment (77%), patient reluctance to report pain (60%), patient reluctance to take analgesics (72%), and staff reluctance to prescribe opioids (41%). Conclusions: Physicians' perceptions of barriers to cancer pain management remain quite stable over time, and physicians continue to report inadequate pain treatment education. Future educational efforts should target radiation oncologists as an important resource for the treatment of cancer pain

Barriers to implementing evidence-based practices in addiction treatment programs: comparing staff reports on Motivational Interviewing, Adolescent Community Reinforcement Approach, Assertive Community Treatment, and Cognitive-behavioral Therapy.

Science.gov (United States)

Amodeo, M; Lundgren, L; Cohen, A; Rose, D; Chassler, D; Beltrame, C; D'Ippolito, M

2011-11-01

This qualitative study explored barriers to implementing evidence-based practices (EBPs) in community-based addiction treatment organizations (CBOs) by comparing staff descriptions of barriers for four EBPs: Motivational Interviewing (MI), Adolescent Community Reinforcement Approach (A-CRA), Assertive Community Treatment (ACT), and Cognitive-behavioral Therapy (CBT). The CBOs received CSAT/SAMHSA funding from 2003 to 2008 to deliver services using EBPs. Phone interview responses from 172 CBO staff directly involved in EBP implementation were analyzed using content analysis, a method for making inferences and developing themes from the systematic review of participant narratives (Berelson, 1952). Staff described different types of barriers to implementing each EBP. For MI, the majority of barriers involved staff resistance or organizational setting. For A-CRA, the majority of barriers involved specific characteristics of the EBP or client resistance. For CBT, the majority of barriers were associated with client resistance, and for ACT, the majority of barriers were associated with resources. EBP designers, policy makers who support EBP dissemination and funders should include explicit strategies to address such barriers. Addiction programs proposing to use specific EBPs must consider whether their programs have the organizational capacity and community capacity to meet the demands of the EBP selected. Copyright © 2011 Elsevier Ltd. All rights reserved.

SKYSHIN: A computer code for calculating radiation dose over a barrier

International Nuclear Information System (INIS)

Atwood, C.L.; Boland, J.R.; Dickman, P.T.

1986-11-01

SKYSHIN is a computer code for calculating the radioactive dose (mrem), when there is a barrier between the point source and the receptor. The two geometrical configurations considered are: the source and receptor separated by a rectangular wall, and the source at the bottom of a cylindrical hole in the ground. Each gamma ray traveling over the barrier is assumed to be scattered at a single point. The dose to a receptor from such paths is numerically integrated for the total dose, with symmetry used to reduce the triple integral to a double integral. The buildup factor used along a straight line through air is based on published data, and extrapolated in a stable way to low energy levels. This buildup factor was validated by comparing calculated and experimental line-of-sight doses. The entire code shows good agreement to limited field data. The code runs on a CDC or on a Vax computer, and could be modified easily for others

Radiation protection training programmes Spanish approach

International Nuclear Information System (INIS)

Arboli, M. Marco; Suarez, M. Rodriguez; Cabrera, S. Falcon

2002-01-01

Radiation Protection Programmes are being considered the best way to promote safety culture and to spread and propagate European basic safety standards. It is widely accepted that training is an important tool to upgrade competence for radiation exposed workers. The Spanish Radiation Protection Education and Training Programmes provide a solid and integrated educational model, which takes into account the variety of applied fields, the different levels of responsibilities, the technological and methodological advances, as well as the international tendencies. The needs for a specialised training on Radiation Protection (RP) for exposed workers appears into the Spanish regulation in 1964. National initial training programmes are well established since 1972. Individual certifications, based on personal licences are required for exposed workers. The Spanish regulation also includes continuous and on the job RP training. The educational programmes are being continuously updating and improving. CIEMAT plays an important role in RP Spanish training, improving and modifying the previous RP courses and developing new programmes in order to complete the RP training levels. To achieve Radiation Protection objectives, new technological media for educational methods and material are taking into account. Nevertheless, Spanish RP education and training model has to be improved in some aspects. The purpose of this paper is to analyse the situation and the future needs to be considered in order to complete the RP training processes

COMPASS: A source term code for investigating capillary barrier performance

International Nuclear Information System (INIS)

Zhou, Wei; Apted, J.J.

1996-01-01

A computer code COMPASS based on compartment model approach is developed to calculate the near-field source term of the High-Level-Waste repository under unsaturated conditions. COMPASS is applied to evaluate the expected performance of Richard's (capillary) barriers as backfills to divert infiltrating groundwater at Yucca Mountain. Comparing the release rates of four typical nuclides with and without the Richard's barrier, it is shown that the Richard's barrier significantly decreases the peak release rates from the Engineered-Barrier-System (EBS) into the host rock

Merger of waste of lead in polyester resin for application of protection barriers

International Nuclear Information System (INIS)

Barros, Frieda Saicla; Paredes, Ramon Siguifredo Cortes

2010-01-01

This paper's main objective is the use of powdered lead waste obtained from the recycling of batteries embedded in polyester resin to be used as a protective barrier in environments subject to radiation. The aim is to enable a more economical procedure which is faster and more practical for use in walls where it is necessary to use protective barrier. This justification is reinforced having in sight the use of byproducts generated by industries, recycling them and using them as components in the development of barriers against ionizing radiation. In this study, we observed the morphological and physical-chemical properties of isolated and associated materials and performance analysis of the composite with respect to the attenuation properties for gamma rays, by means of experimental tests. For mixtures with 40% of waste lead, value referenced in mass, we obtained satisfactory results on the screen. Thus, we were able to combine the good performance of the composite with the reduction of environmental liabilities, in view of the recycling process of lead. (author)

Microscopic study on dynamic barrier in fusion reactions

International Nuclear Information System (INIS)

Wu Xizhen; Tian Junlong; Zhao Kai; Li Zhuxia; Wang Ning

2004-01-01

The authors briefly review the fusion process of very heavy nuclear systems and some theoretical models. The authors propose a microscopic transport dynamic model, i.e. the Improved Quantum Molecular Dynamic model, for describing fusion reactions of heavy systems, in which the dynamical behavior of the fusion barrier in heavy fusion systems has been studied firstly. The authors find that with the incident energy decreasing the lowest dynamic barrier is obtained which approaches to the adiabatic static barrier and with increase of the incident energy the dynamic barrier goes up to the diabatic static barrier. The authors also indicate that how the dynamical fusion barrier is correlated with the development of the configuration of fusion partners along the fusion path. Associating the single-particle potentials obtained at different stages of fusion with the Two Center Shell Model, authors can study the time evolution of the single particle states of fusion system in configuration space of single particle orbits along the fusion path. (author)

Barriers to Business Model Innovation in Swedish Agriculture

Directory of Open Access Journals (Sweden)

Olof Sivertsson

2015-02-01

Full Text Available Swedish agricultural companies, especially small farms, are struggling to be profitable in difficult economic times. It is a challenge for Swedish farmers to compete with imported products on prices. The agricultural industry, however, supports the view that through business model innovation, farms can increase their competitive advantage. This paper identifies and describes some of the barriers Swedish small farms encounter when they consider business model innovation. A qualitative approach is used in the study. Agriculture business consultants were interviewed. In a focus group led by the researchers, farmers discussed business model innovation, including the exogenous and endogenous barriers to such innovation. The paper concludes many barriers exist when farmers consider innovation of agricultural business models. Some barriers are caused by human factors, such as individuals’ attitudes, histories, and traditions. Other barriers are more contextual in nature and relate to a particular industry or company setting. Still other barriers, such as government regulations, value chain position, and weather, are more abstract. All barriers, however, merit attention when Swedish agricultural companies develop new business models.

Analysing black phosphorus transistors using an analytic Schottky barrier MOSFET model.

Science.gov (United States)

Penumatcha, Ashish V; Salazar, Ramon B; Appenzeller, Joerg

2015-11-13

Owing to the difficulties associated with substitutional doping of low-dimensional nanomaterials, most field-effect transistors built from carbon nanotubes, two-dimensional crystals and other low-dimensional channels are Schottky barrier MOSFETs (metal-oxide-semiconductor field-effect transistors). The transmission through a Schottky barrier-MOSFET is dominated by the gate-dependent transmission through the Schottky barriers at the metal-to-channel interfaces. This makes the use of conventional transistor models highly inappropriate and has lead researchers in the past frequently to extract incorrect intrinsic properties, for example, mobility, for many novel nanomaterials. Here we propose a simple modelling approach to quantitatively describe the transfer characteristics of Schottky barrier-MOSFETs from ultra-thin body materials accurately in the device off-state. In particular, after validating the model through the analysis of a set of ultra-thin silicon field-effect transistor data, we have successfully applied our approach to extract Schottky barrier heights for electrons and holes in black phosphorus devices for a large range of body thicknesses.

Information and energetic approaches to the influence of ionizing radiation on the organism

International Nuclear Information System (INIS)

Bulanova, K.Ya.; Lobanok, L.M.; Kundas, S.P.; Konoplya, E.F.

2005-01-01

In order to reveal the regularities of interaction of organism with low-intensive ionizing radiation, cybernetic approaches are needed. The living organisms are self-regulating system of a behavioural type. The complexity of the organization is determined by the hierarchy of controlling system. Relation between systems are not of physico-chemical nature; they are based on control, i.e. on information processes. In information system, all the weak influences (including ionizing radiation ) are perceived in the form of signal. Signal information of a natural radiation background is vitally important for organisms as in conversed type, as bioradiation, it is used for management initiation, i. e. self-regulation, self-development and so on. In the case of a superfluous surge of information at man-caused impacts of ionizing radiation (up to 10 Gr) the information system loses its ability to solve information tasks quickly and begins to experience the state of tension. Brought to a very tensed state it is able to lose its balance, its stability, i.e. to die. The signal-information perception of radiation explains the effects of its low dose, non-linear character of dependence of biologic response of irradiated dose, hormesis phenomenon, apoptosis, remote consequences of irradiation, bystander effect and other postradiation effects. (authors)

electromagnetic radiation exposure from cellular base station

African Journals Online (AJOL)

eobe

2DEPARTMENT OF ELECTRICAL/ELECTRONIC ENGINEERING, FEDERAL ... equipment comply with international standards and thus the radiated field propagated from their installation ... adverse health effects such as blood brain barrier,.

The Gendered International School: Barriers to Women Managers' Progression

Science.gov (United States)

Sanderson, Ruth Elizabeth; Whitehead, Stephen

2016-01-01

Purpose: The purpose of this paper is to examine the barriers women identify to their promotion in international schools and also the ways in which women can overcome these barriers. Design/methodology/approach: The field of enquiry is international schools, with the study drawing on qualitative research. The researchers interviewed 11 women from…

New approach to far field analysis for radiation pattern estimation using FDTD method

Directory of Open Access Journals (Sweden)

Nikolić Bojana

2014-01-01

Full Text Available In this paper an approach to efficient computation of radiation pattern in FDTD simulation environment is presented. A necessary large distance from the radiating object is achieved by multigrid space discretization with unilaterally connected subdomains. A numerical dispersion is reduced using more general complex-envelope finite difference time domain (CE-FDTD formulation and high order accuracy FDTD schemes where possible. In order to examine how much the introduced algorithm complexity and increased demands concerning computational power and memory are justified by the gain in accuracy, several different scenarios were considered. [Projekat Ministarstva nauke Republike Srbije, br. TR-32051 i br. TR-33008

Evaluation of Erosion Resistance of Advanced Turbine Thermal Barrier Coatings

Science.gov (United States)

Zhu, Dongming; Kuczmarski, Maria A.; Miller, Robert A.; Cuy, Michael D.

2007-01-01

The erosion resistant turbine thermal barrier coating system is critical to aircraft engine performance and durability. By demonstrating advanced turbine material testing capabilities, we will be able to facilitate the critical turbine coating and subcomponent development and help establish advanced erosion-resistant turbine airfoil thermal barrier coatings design tools. The objective of this work is to determine erosion resistance of advanced thermal barrier coating systems under simulated engine erosion and/or thermal gradient environments, validating advanced turbine airfoil thermal barrier coating systems based on nano-tetragonal phase toughening design approaches.

Radiation profile measurements for edge transport barrier discharges in Compact Helical System using AXUV photodiode arrays

International Nuclear Information System (INIS)

Suzuki, C.; Okamura, S.; Minami, T.; Akiyama, T.; Fujisawa, A.; Ida, K.; Isobe, M.; Matsuoka, K.; Nagaoka, K.; Nishimura, S.; Peterson, B. J.; Shimizu, A.; Takahashi, C.; Toi, K.; Yoshimura, Y.

2005-01-01

The formation of edge transport barrier (ETB) has recently been found in Compact Helical System (CHS) plasmas heated by co-injected neutral beam injection (NBI) with strong gas puffing. This regime is characterized by the appearance of the steep gradient of the electron density near the edge following the abrupt drop of hydrogen Balmer alpha (H α ) line intensity. In addition to single channel pyroelectric detector as a conventional bolometer, we have employed unfiltered absolute extreme ultraviolet (AXUV) photodiode arrays as a simple and low-cost diagnostic to investigate spatial and temporal variations of radiation emissivity in the ETB discharges. A compact mounting module for a 20 channel AXUV photodiode array including an in-vacuum preamplifier for immediate current-voltage conversion has successfully been designed and fabricated. Two identical modules installed in the upper and lower viewports provide 40 lines of sight covering the inboard and outboard sides within the horizontally elongated cross section of the CHS plasma with wide viewing angle. Although spectral uniformity of the detector sensitivity of the AXUV photodiode is unsatisfied for photon energies lower than 200 eV, it has been confirmed that the signals of AXUV photodiode and pyroelectric detector in the ETB discharges show roughly the same behavior except for the very beginning and end of the discharges. The results of the measurements in typical ETB discharges show that the signals of all the channels of the AXUV photodiode arrays begin to increase more rapidly at the moment of the transition than before. The rate of the increase is larger for the edge viewing chords than for the center viewing ones, which indicates the flattening of the radiation profile following the change in the electron density profile after the formation of the ETB. However, the signals for the edge chords tend to saturate after several tens of milliseconds, while they still continue to increase for the central chords

Barriers to energy efficiency in shipping: A triangulated approach to investigate the principal agent problem

International Nuclear Information System (INIS)

Rehmatulla, Nishatabbas; Smith, Tristan

2015-01-01

Energy efficiency is a key policy strategy to meet some of the challenges being faced today and to plan for a sustainable future. Numerous empirical studies in various sectors suggest that there are cost-effective measures that are available but not always implemented due to existence of barriers to energy efficiency. Several cost-effective energy efficient options (technologies for new and existing ships and operations) have also been identified for improving energy efficiency of ships. This paper is one of the first to empirically investigate barriers to energy efficiency in the shipping industry using a novel framework and multidisciplinary methods to gauge implementation of cost-effective measures, perception on barriers and observations of barriers. It draws on findings of a survey conducted of shipping companies, content analysis of shipping contracts and analysis of energy efficiency data. Initial results from these methods suggest the existence of the principal agent problem and other market failures and barriers that have also been suggested in other sectors and industries. Given this finding, policies to improve implementation of energy efficiency in shipping need to be carefully considered to improve their efficacy and avoid unintended consequences. -- Highlights: •We provide the first analysis of the principal agent problem in shipping. •We develop a framework that incorporates methodological triangulation. •Our results show the extent to which this barrier is observed and perceived. •The presence of the barrier has implications on the policy most suited to shipping

Barriers to Banking - Towards an Inclusive Banking Environment in South Africa.

Science.gov (United States)

Martinson, Estelle; Martinson, Johannes

2016-01-01

A recent study in South Africa on the barriers to banking which involved customers in three disability groups namely mobility, hearing and vision has highlighted that currently banking in South Africa is not accessible. Customers with a disability are unable to independently use banking services across a wide range of channels. Exclusion from something as fundamental as managing their own financial affairs raise serious human rights concerns and requires committed action from decision-makers to address this. The fact that solutions to all of the identified barriers have been successfully implemented in banks in other parts of the world for many years emphasize that this is not a technical challenge. While some solutions require complex or expensive changes such as removing physical access barriers and ensuring that digital channels meet internationally accepted standards of accessibility, there are many simple and low-cost solutions which can be implemented immediately and would make a world of difference to these customers and their experience of banking. One key barrier which emerged in all the focus groups and surveys is attitudinal barriers - staff who are unwilling to assist, impatient, interact with the customer's assistant instead of directly with them and lack basic skills on how to interact with someone who has a disability. A comprehensive framework of banking was used to identify a wide range of barriers. The barriers were classified as attitudinal, barriers to physical access, digital access barriers, barriers to information, communication barriers and some generic concerns such as safe evacuation during emergencies and alternative authentication. Both the barriers and the solutions where ranked by participants. From a theoretical perspective, the benefit of a customer-centric approach to understanding these barriers and the innovation potential of a Universal Design approach is affirmed by this study.

Noninvasive evaluation of the barrier properties of the skin

Directory of Open Access Journals (Sweden)

Utz S.R.

2014-09-01

Full Text Available Skin as an organ of protection covers the body and accomplishes multiple defensive functions. The intact skin represents a barrier to the uncontrolled loss of water, proteins, and plasma components from the organism. Due to its complex structure, the epidermal barrier with its major component, stratum corneum, is the rate-limiting unit for the penetration of exogenous substances through the skin. The epidermal barrier is not a static structure. The permeability barrier status can be modified by different external and internal factors such as climate, physical stressors, and a number of skin and systemic diseases. Today, different non-invasive approaches are used to monitor the skin barrier physical properties in vivo. The quantification of parameters such as transepidermal water loss, stratum corneum hydration, and skin surface acidity is essential for the integral evaluation of the epidermal barrier status. This paper will allow the readership to get acquainted with the non-invasive, in vivo methods for the investigation of the skin barrier.

An ISM approach for the barrier analysis in implementing green supply chain management

DEFF Research Database (Denmark)

Mathiyazhagan, K.; Govindan, Kannan; NoorulHaq, A.

2013-01-01

As customers are becoming more environmental conscious and governments are making stricter environmental regulations, the industries need to reduce the environmental impact of their supply chain. Indian auto component manufacturing industries especially SMEs (Small and Medium Enterprises......) are focused to cleaner production by implementing Green Supply Chain Management (GSCM) in their industries. But they are struggling to implement GSCM concept. The present research analyzes the barriers for the implementation of GSCM concept which has been divided into two phases such as identification...... dominant one for the adoption of green supply chain management and this result is helpful for industries to make easier the adoption of green concept in their supply chain by removing the dominant barrier. It indicates that different Indian auto component manufacturing industries have differing barriers...

Thermal radiation transfer calculations in combustion fields using the SLW model coupled with a modified reference approach

Science.gov (United States)

Darbandi, Masoud; Abrar, Bagher

2018-01-01

The spectral-line weighted-sum-of-gray-gases (SLW) model is considered as a modern global model, which can be used in predicting the thermal radiation heat transfer within the combustion fields. The past SLW model users have mostly employed the reference approach to calculate the local values of gray gases' absorption coefficient. This classical reference approach assumes that the absorption spectra of gases at different thermodynamic conditions are scalable with the absorption spectrum of gas at a reference thermodynamic state in the domain. However, this assumption cannot be reasonable in combustion fields, where the gas temperature is very different from the reference temperature. Consequently, the results of SLW model incorporated with the classical reference approach, say the classical SLW method, are highly sensitive to the reference temperature magnitude in non-isothermal combustion fields. To lessen this sensitivity, the current work combines the SLW model with a modified reference approach, which is a particular one among the eight possible reference approach forms reported recently by Solovjov, et al. [DOI: 10.1016/j.jqsrt.2017.01.034, 2017]. The combination is called "modified SLW method". This work shows that the modified reference approach can provide more accurate total emissivity calculation than the classical reference approach if it is coupled with the SLW method. This would be particularly helpful for more accurate calculation of radiation transfer in highly non-isothermal combustion fields. To approve this, we use both the classical and modified SLW methods and calculate the radiation transfer in such fields. It is shown that the modified SLW method can almost eliminate the sensitivity of achieved results to the chosen reference temperature in treating highly non-isothermal combustion fields.

Observation of microwave radiation using low-cost detectors at the ANKA storage ring*

CERN Document Server

Judin, V; Hofmann, A; Huttel, E; Kehrer, B; Klein, M; Marsching, S; Müller, A S; Nasse, M; Smale, N; Caspers, F; Peier, P

2011-01-01

Synchrotron light sources emit Coherent Synchrotron Radiation (CSR) for wavelengths longer than or equal to the bunch length. At most storage rings CSR cannot be observed, because the vacuum chamber cuts off radiation with long wavelengths. There are different approaches for shifting the CSR to shorter wavelengths that can propagate through the beam pipe, e.g.: the accelerator optics can be optimized for a low momentum compaction factor, thus reducing the bunch length. Alternatively, laser slicing can modulate substructures on long bunches [1]. Both techniques extend the CSR spectrum to shorter wavelengths, so that CSR is emitted at wavelengths below the waveguide shielding cut off. Usually fast detectors, like superconducting bolometer detector systems or Schottky barrier diodes, are used for observation of dynamic processes in accelerator physics. In this paper, we present observations of microwave radiation at ANKA using an alternative detector, a LNB (Low Noise Block) system. These devices are usually use...

Radiation dose in mammography: an energy-balance approach

International Nuclear Information System (INIS)

Shrivastava, P.N.

1981-01-01

An energy-balance approach for calculation of mean, integral, and midpoint doses in mammography is introduced. Estimation of mean absorbed dose for individual applications is described. Calculations made for a range of xeromammographic techniques used at various breast cancer detection centers show that although increasing the beam h.v.l. dramatically decreases breast surface exposure, it is insignificant in lowering mean breast dose or radiation risk. Thus selection of a moderate h.v.l. to optimize image quality in xeromammography may be more beneficial than unduly increasing h.v.l. merely to reduce surface exposure. The mean breast dose per mammogram with low h.v.l. screen-film techniques was 3 to 9 times lower than for xeromammography, suggesting that general acceptance of screen-film techniques can significantly reduce the risk associated with mammography

High rates of hybridisation reveal fragile reproductive barriers between endangered Australian sea snakes

DEFF Research Database (Denmark)

Sanders, Kate L; Redsted Rasmussen, Arne; Guinea, Michael L.

2014-01-01

designations, but revealed high frequencies of hybrids on all four reefs and individuals of pure A. fuscus ancestry only at Scott and (historically) Ashmore. Most unexpectedly, 95% of snakes sampled at Hibernia were hybrids that resembled A. laevis in phenotype, revealing a collapse of reproductive barriers...... (‘reverse speciation’) at this reef. These results have dire implications for the conservation status of A. fuscus, and highlight the fragility of reproductive barriers in a recent marine radiation....

Barytes board: a cost effective radiation barrier material for use in diagnostic x-ray suites

International Nuclear Information System (INIS)

Coalter, G.C.; Metcalfe, P.E.

1987-01-01

The use of barium based products in protective barrier materials proved successful for many years until their cost of manufacture and increases in labour costs for fixing and stopping saw the introduction of lead ply as the material of choice in diagnostic X-ray suites. Whilst the advantage of sheet lead as a barrier for diagnostic X-rays, where the photoelectric effect predominates is recognised, this precedence is somewhat negated by the high cost of manufacture and delays in supply. Lead lined ply also requires external cladding after erection for an acceptable finish to be obtained. Such cost increases have prompted us to re-evaluate the use of precast barium plaster sheets (Barytes Board) as an alternative barrier material

Barriers to Using Nonpharmacologic Approaches and Reducing Opioid Use in Primary Care.

Science.gov (United States)

Giannitrapani, Karleen F; Ahluwalia, Sangeeta C; McCaa, Matthew; Pisciotta, Maura; Dobscha, Steven; Lorenz, Karl A

2017-10-20

Opioid prescribing for chronic pain, including the potential for over-reliance and misuse, is a public health concern. In the context of Veterans Administration (VA) primary care team-based pain management, we aimed to understand providers' perceptions of barriers to reducing opioid use and improving the use of nonpharmacologic pain management therapies (NPTs) for chronic pain. A semistructured interview elucidated provider experiences with assessing and managing pain. Emergent themes were mapped to known dimensions of VA primary care access. Informants included 60 primary care providers, registered nurses, licensed practical nurses, clerks, psychologists, and social workers at two VA Medical Centers. Nine multidisciplinary focus groups. Provider perceptions of barriers to reducing opioids and improving use of NPTs for patients with chronic pain clustered around availability and access. Barriers to NPT access included the following subthemes: geographical (patient distance from service), financial (out-of-pocket cost to patient), temporal (treatment time delays), cultural (belief that NPTs increased provider workload, perception of insufficient training on NPTs, perceptions of patient resistance to change, confrontation avoidance, and insufficient leadership support), and digital (measure used for pain assessment, older patients hesitant to use technology, providers overwhelmed by information). Decreasing reliance on opioids for chronic pain requires a commitment to local availability and provider-facing strategies that increase efficacy in prescribing NPTs. Policies and interventions for decreasing utilization of opioids and increasing use of NPTs should comprehensively consider access barriers. 2017 American Academy of Pain Medicine. This work is written by US Government employees and is in the public domain in the US.

Radiation shelter

International Nuclear Information System (INIS)

Crookes, T.A.

1982-01-01

This patent application describes a shelter comprising a cavity for receiving life to be sheltered; a roof for covering at least a portion of said cavity, and at least one aqueous, protective barrier layer adapted to prevent transmission through said roof and into said cavity of at least a portion of radiation in a predetermined spectrum. The cavity walls may be impregnated with an oil suitable for dressing burns. (author)

Brain tumors and synchrotron radiation: Methodological developments in quantitative brain perfusion imaging and radiation therapy

International Nuclear Information System (INIS)

Adam, Jean-Francois

2005-01-01

High-grade gliomas are the most frequent type of primary brain tumors in adults. Unfortunately, the management of glioblastomas is still mainly palliative and remains a difficult challenge, despite advances in brain tumor molecular biology and in some emerging therapies. Synchrotron radiation opens fields for medical imaging and radiation therapy by using monochromatic intense x-ray beams. It is now well known that angiogenesis plays a critical role in the tumor growth process and that brain perfusion is representative of the tumor mitotic activity. Synchrotron radiation quantitative computed tomography (SRCT) is one of the most accurate techniques for measuring in vivo contrast agent concentration and thus computing precise and accurate absolute values of the brain perfusion key parameters. The methodological developments of SRCT absolute brain perfusion measurements as well as their preclinical validation are detailed in this thesis. In particular, absolute cerebral volume and blood brain barrier permeability high-resolution (pixel size 2 ) parametric maps were reported. In conventional radiotherapy, the treatment of these tumors remains a delicate challenge, because the damages to the surrounding normal brain tissue limit the amount of radiation that can be delivered. One strategy to overcome this limitation is to infuse an iodinated contrast agent to the patient during the irradiation. The contrast agent accumulates in the tumor, through the broken blood brain barrier, and the irradiation is performed with kilovoltage x rays, in tomography mode, the tumor being located at the center of rotation and the beam size adjusted to the tumor dimensions. The dose enhancement results from the photoelectric effect on the heavy element and from the irradiation geometry. Synchrotron beams, providing high intensity, tunable monochromatic x rays, are ideal for this treatment. The beam properties allow the selection of monochromatic irradiation, at the optimal energy, for a

Trends and barriers to lateral gene transfer in prokaryotes.

Science.gov (United States)

Popa, Ovidiu; Dagan, Tal

2011-10-01

Gene acquisition by lateral gene transfer (LGT) is an important mechanism for natural variation among prokaryotes. Laboratory experiments show that protein-coding genes can be laterally transferred extremely fast among microbial cells, inherited to most of their descendants, and adapt to a new regulatory regime within a short time. Recent advance in the phylogenetic analysis of microbial genomes using networks approach reveals a substantial impact of LGT during microbial genome evolution. Phylogenomic networks of LGT among prokaryotes reconstructed from completely sequenced genomes uncover barriers to LGT in multiple levels. Here we discuss the kinds of barriers to gene acquisition in nature including physical barriers for gene transfer between cells, genomic barriers for the integration of acquired DNA, and functional barriers for the acquisition of new genes. Copyright © 2011 Elsevier Ltd. All rights reserved.

Relationship between cloud radiative forcing, cloud fraction and cloud albedo, and new surface-based approach for determining cloud albedo

OpenAIRE

Y. Liu; W. Wu; M. P. Jensen; T. Toto

2011-01-01

This paper focuses on three interconnected topics: (1) quantitative relationship between surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo; (2) surfaced-based approach for measuring cloud albedo; (3) multiscale (diurnal, annual and inter-annual) variations and covariations of surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo. An analytical expression is first derived to quantify the relationship between cloud radiative forcing, cloud fractio...

Combined action of ionizing radiation with another factor: common rules and theoretical approach

International Nuclear Information System (INIS)

Kim, Jin Kyu; Roh, Changhyun; Komarova, Ludmila N.; Petin, Vladislav G.

2013-01-01

Two or more factors can simultaneously make their combined effects on the biological objects. This study has focused on theoretical approach to synergistic interaction due to the combined action of radiation and another factor on cell inactivation. A mathematical model for the synergistic interaction of different environmental agents was suggested for quantitative prediction of irreversibly damaged cells after combined exposures. The model takes into account the synergistic interaction of agents and based on the supposition that additional effective damages responsible for the synergy are irreversible and originated from an interaction of ineffective sub lesions. The experimental results regarding the irreversible component of radiation damage of diploid yeast cells simultaneous exposed to heat with ionizing radiation or UV light are presented. A good agreement of experimental results with model predictions was demonstrated. The importance of the results obtained for the interpretation of the mechanism of synergistic interaction of various environmental factors is discussed. (author)

Combined action of ionizing radiation with another factor: common rules and theoretical approach

Energy Technology Data Exchange (ETDEWEB)

Kim, Jin Kyu; Roh, Changhyun, E-mail: jkkim@kaeri.re.kr [Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of); Komarova, Ludmila N.; Petin, Vladislav G., E-mail: vgpetin@yahoo.com [Medical Radiological Research Center, Obninsk (Russian Federation)

2013-07-01

Two or more factors can simultaneously make their combined effects on the biological objects. This study has focused on theoretical approach to synergistic interaction due to the combined action of radiation and another factor on cell inactivation. A mathematical model for the synergistic interaction of different environmental agents was suggested for quantitative prediction of irreversibly damaged cells after combined exposures. The model takes into account the synergistic interaction of agents and based on the supposition that additional effective damages responsible for the synergy are irreversible and originated from an interaction of ineffective sub lesions. The experimental results regarding the irreversible component of radiation damage of diploid yeast cells simultaneous exposed to heat with ionizing radiation or UV light are presented. A good agreement of experimental results with model predictions was demonstrated. The importance of the results obtained for the interpretation of the mechanism of synergistic interaction of various environmental factors is discussed. (author)

Engineered barrier development for a nuclear waste repository in basalt

International Nuclear Information System (INIS)

Smith, M.J.

1980-05-01

The BWIP Engineered Barrier Program has been developed to provide an integrated approach to the development of site-specific Engineered Barrier assemblages for a repository located in basalt. The goal of this program is to specify engineered and natural barriers which will ensure that nuclear and non-radioactive hazardous materials emplaced in a repository in basalt do not exceed acceptable rates of release to the biosphere. A wide range of analytical and experimental activities related to the basalt repository environment, waste package environment, waste/barrier/rock interactions, and barrier performance assessment provide the basis for selection of systems capable of meeting licensing requirements. Work has concentrated on specifying and testing natural and man-made materials which can be used to plug boreholes in basalt and which can be used as multiple barriers to surround nuclear waste forms and containers. The Engineered Barriers Program is divided into two major activities: multiple barrier studies and borehole plugging. 8 figures, 4 tables

Barriers to Liposomal Gene Delivery: from Application Site to the Target.

Science.gov (United States)

Saffari, Mostafa; Moghimi, Hamid Reza; Dass, Crispin R

2016-01-01

Gene therapy is a therapeutic approach to deliver genetic material into cells to alter their function in entire organism. One promising form of gene delivery system (DDS) is liposomes. The success of liposome-mediated gene delivery is a multifactorial issue and well-designed liposomal systems might lead to optimized gene transfection particularly in vivo. Liposomal gene delivery systems face different barriers from their site of application to their target, which is inside the cells. These barriers include presystemic obstacles (epithelial barriers), systemic barriers in blood circulation and cellular barriers. Epithelial barriers differ depending on the route of administration. Systemic barriers include enzymatic degradation, binding and opsonisation. Both of these barriers can act as limiting hurdles that genetic material and their vector should overcome before reaching the cells. Finally liposomes should overcome cellular barriers that include cell entrance, endosomal escape and nuclear uptake. These barriers and their impact on liposomal gene delivery will be discussed in this review.

Perceived barriers to online education by radiologic science educators.

Science.gov (United States)

Kowalczyk, Nina K

2014-01-01

Radiologic science programs continue to adopt the use of blended online education in their curricula, with an increase in the use of online courses since 2009. However, perceived barriers to the use of online education formats persist in the radiologic science education community. An electronic survey was conducted to explore the current status of online education in the radiologic sciences and to identify barriers to providing online courses. A random sample of 373 educators from radiography, radiation therapy, and nuclear medicine technology educational programs accredited by the Joint Review Committee on Education in Radiologic Technology and Joint Review Committee on Educational Programs in Nuclear Medicine Technology was chosen to participate in this study. A qualitative analysis of self-identified barriers to online teaching was conducted. Three common themes emerged: information technology (IT) training and support barriers, student-related barriers, and institutional barriers. Online education is not prevalent in the radiologic sciences, in part because of the need for the clinical application of radiologic science course content, but online course activity has increased substantially in radiologic science education, and blended or hybrid course designs can effectively provide opportunities for student-centered learning. Further development is needed to increase faculty IT self-efficacy and to educate faculty regarding pedagogical methods appropriate for online course delivery. To create an excellent online learning environment, educators must move beyond technology issues and focus on providing quality educational experiences for students.

A photoemission study of the effectiveness of nickel, manganese, and cobalt based corrosion barriers for silicon photo-anodes during water oxidation

Energy Technology Data Exchange (ETDEWEB)

O' Connor, Robert; Bogan, Justin; McCoy, Anthony; Byrne, Conor; Hughes, Greg [School of Physical Sciences, Dublin City University, Dublin 9 (Ireland)

2016-05-21

Silicon is an attractive material for solar water splitting applications due to its abundance and its capacity to absorb a large fraction of incident solar radiation. However, it has not received as much attention as other materials due to its tendency to oxidize very quickly in aqueous environments, particularly when it is employed as the anode where it drives the oxygen evolution reaction. In recent years, several works have appeared in the literature examining the suitability of thin transition metal oxide films grown on top of the silicon to act as a corrosion barrier. The film should be transparent to solar radiation, allow hole transport from the silicon surface to the electrolyte, and stop the diffusion of oxygen from the electrolyte back to the silicon. In this work, we compare Mn-oxide, Co-oxide, and Ni-oxide thin films grown using physical vapor deposition in order to evaluate which material offers the best combination of photocurrent and corrosion protection. In addition to the electrochemical data, we also present a detailed before-and-after study of the surface chemistry of the films using x-ray photoelectron spectroscopy. This approach allows for a comprehensive analysis of the mechanisms by which the corrosion barriers protect the underlying silicon, and how they degrade during the water oxidation reaction.

Hanford Permanent Isolation Barrier Program: Asphalt technology development

International Nuclear Information System (INIS)

Freeman, H.D.; Romine, R.A.

1994-11-01

An important component of the Hanford Permanent Isolation Barrier is the use of a two-layer composite asphalt system, which provides backup water diversion capabilities if the primary capillary barrier fails to meet infiltration goals. Because of asphalt's potential to perform to specification over the 1000-year design life criterion, a composite asphalt barrier (HMAC/fluid-applied polymer-modified asphalt) is being considered as an alternative to the bentonite clay/high density poly(ethylene) barriers for the low-permeability component of the Hanford Permanent Isolation Barrier. The feasibility of using asphalt as a long-term barrier is currently being studied. Information that must be known is the ability of asphalt to retain desirable physical properties over a period of 1000 years. This paper presents the approach for performing accelerated aging tests and evaluating the performance of samples under accelerated conditions. The results of these tests will be compared with asphalt artifact analogs and the results of modeling the degradation of the selected asphalt composite to make life-cycle predictions

Interventions to prevent skin cancer by reducing exposure to ultraviolet radiation: a systematic review.

Science.gov (United States)

Saraiya, Mona; Glanz, Karen; Briss, Peter A; Nichols, Phyllis; White, Cornelia; Das, Debjani; Smith, S Jay; Tannor, Bernice; Hutchinson, Angela B; Wilson, Katherine M; Gandhi, Nisha; Lee, Nancy C; Rimer, Barbara; Coates, Ralph C; Kerner, Jon F; Hiatt, Robert A; Buffler, Patricia; Rochester, Phyllis

2004-12-01

The relationship between skin cancer and ultraviolet radiation is well established. Behaviors such as seeking shade, avoiding sun exposure during peak hours of radiation, wearing protective clothing, or some combination of these behaviors can provide protection. Sunscreen use alone is not considered an adequate protection against ultraviolet radiation. This report presents the results of systematic reviews of effectiveness, applicability, other harms or benefits, economic evaluations, and barriers to use of selected interventions to prevent skin cancer by reducing exposure to ultraviolet radiation. The Task Force on Community Preventive Services found that education and policy approaches to increasing sun-protective behaviors were effective when implemented in primary schools and in recreational or tourism settings, but found insufficient evidence to determine effectiveness when implemented in other settings, such as child care centers, secondary schools and colleges, and occupational settings. They also found insufficient evidence to determine the effectiveness of interventions oriented to healthcare settings and providers, media campaigns alone, interventions oriented to parents or caregivers of children, and community-wide multicomponent interventions. The report also provides suggestions for areas for future research.

A conversion method of air kerma from the primary, scatter, and leakage radiations to effective dose for calculating x-ray shielding barriers in mammography

International Nuclear Information System (INIS)

Kharrati, Hedi

2005-01-01

In this study, a new approach has been introduced for derivation of the effective dose from air kerma to calculate shielding requirements in mammography facilities. This new approach has been used to compute the conversion coefficients relating air kerma to the effective dose for the mammography reference beam series of the Netherlands Metrology Institute Van Swinden Laboratorium, National Institute of Standards and Technology, and International Atomic Energy Agency laboratories. The results show that, in all cases, the effective dose in mammography energy range is less than 25% of the incident air kerma for the primary and the scatter radiations and does not exceed 75% for the leakage radiation

Occupational radiation protection around medical linear accelerators: measurements and semi-analytical approaches

International Nuclear Information System (INIS)

Donadille, L.; Derreumaux, S.; Mantione, J.; Robbes, I.; Trompier, F.; Amgarou, K.; Asselineau, B.; Martin, A.

2008-01-01

Full text: X-rays produced by high-energy (larger than 6 MeV) medical electron linear accelerators create secondary neutron radiation fields mainly by photonuclear reactions inside the materials of the accelerator head, the patient and the walls of the therapy room. Numerous papers were devoted to the study of neutron production in medical linear accelerators and resulting decay of activation products. However, data associated to doses delivered to workers in treatment conditions are scarce. In France, there are more than 350 external radiotherapy facilities representing almost all types of techniques and designs. IRSN carried out a measurement campaign in order to investigate the variation of the occupational dose according the different encountered situations. Six installations were investigated, associated with the main manufacturers (Varian, Elekta, General Electrics, Siemens), for several nominal energies, conventional and IMRT techniques, and bunker designs. Measurements were carried out separately for neutron and photon radiation fields, and for radiation associated with the decay of the activation products, by means of radiometers, tissue-equivalent proportional counters and spectrometers (neutron and photon spectrometry). They were performed at the positions occupied by the workers, i.e. outside the bunker during treatments, inside between treatments. Measurements have been compared to published data. In addition, semi-empirical analytical approaches recommended by international protocols were used to estimate doses inside and outside the bunkers. The results obtained by both approaches were compared and analysed. The annual occupational effective dose was estimated to about 1 mSv, including more than 50 % associated with the decay of activation products and less than 10 % due to direct exposure to leakage neutrons produced during treatments. (author)

Bridging Plant and Human Radiation Response and DNA Repair through an In Silico Approach

Directory of Open Access Journals (Sweden)

Zacharenia Nikitaki

2017-06-01

Full Text Available The mechanisms of response to radiation exposure are conserved in plants and animals. The DNA damage response (DDR pathways are the predominant molecular pathways activated upon exposure to radiation, both in plants and animals. The conserved features of DDR in plants and animals might facilitate interdisciplinary studies that cross traditional boundaries between animal and plant biology in order to expand the collection of biomarkers currently used for radiation exposure monitoring (REM in environmental and biomedical settings. Genes implicated in trans-kingdom conserved DDR networks often triggered by ionizing radiation (IR and UV light are deposited into biological databases. In this study, we have applied an innovative approach utilizing data pertinent to plant and human genes from publicly available databases towards the design of a ‘plant radiation biodosimeter’, that is, a plant and DDR gene-based platform that could serve as a REM reliable biomarker for assessing environmental radiation exposure and associated risk. From our analysis, in addition to REM biomarkers, a significant number of genes, both in human and Arabidopsis thaliana, not yet characterized as DDR, are suggested as possible DNA repair players. Last but not least, we provide an example on the applicability of an Arabidopsis thaliana—based plant system monitoring the role of cancer-related DNA repair genes BRCA1, BARD1 and PARP1 in processing DNA lesions.

Perceived barriers and enablers of physical activity in postpartum women: a qualitative approach

OpenAIRE

Saligheh, Maryam; McNamara, Beverley; Rooney, Rosanna

2016-01-01

Background Postpartum women?s recovery from birth can be assisted through increased physical activity (PA). However, women face substantial barriers to participating in exercise and require support to enable them to benefit from increased PA. Methods This study sought to explore women?s beliefs about and experiences of PA and exercise during the 6?weeks to 12?months postpartum period. A cohort of 14 postpartum women from a survey study of the barriers and enablers to exercise participation ag...

Comparative analysis of different approaches to the computation of long-wave radiation balance of water air systems

International Nuclear Information System (INIS)

Zhukovskii, K.; Nourani, Y.; Monte, L.

1999-01-01

In the present paper, the net long-wave radiation balance of the water-air environmental systems is analysed on the base of several semi-empirical approaches. Various theoretical models of infrared atmospheric radiation are reviewed. Factors, affecting their behavior are considered. Special attention is paid to physical conditions under which those models are applicable. Atmospheric and net infrared radiation fluxes are computed and compared under clear and cloudy sky. Results are presented in graphical form. Conclusions are made on the applicability of models considered for evaluating infrared radiation fluxes in environmental conditions of Central Italy. On the base of present analysis Anderson's model is chosen for future calculations of heat budget of lakes in Central Italy [it

Comparative studies for different proximity potentials applied to sub-barrier fusion reactions

Energy Technology Data Exchange (ETDEWEB)

Zhang, G.L. [Beihang University, School of Physics and Nuclear Energy Engineering, Beijing (China); Beihang University, Key Laboratory of Micro-Nano Measurement-Manipulation and Physics (Ministry of Education), Beijing (China); Qu, W.W. [Medical College of Soochow University, School of Radiation Medicine and Protection, Soochow (China); Guo, M.F.; Qian, J.Q. [Beihang University, School of Physics and Nuclear Energy Engineering, Beijing (China); Zhang, H.Q. [China Institute of Atomic Energy, Beijing (China); Wolski, R. [Henryk Niewodniczanski Institute of Nuclear Physics PAS, Cracow (Poland)

2016-02-15

Coulomb barrier heights calculated by using 14 different versions of proximity potentials are studied and applied for experimental data of fusion in terms of a recently proposed energy scaling approach. The results show that the descriptions of proximity potentials 77 and 88 for the barrier heights seem to be closest to the values required by the systematics. On the basis of proximity potential 77, the parameterized formulas of the barrier height and radius are obtained. These formulas can calculate the barrier positions and barrier heights reasonably well within the error, respectively. Thus it provides a simple and direct way to calculate the barrier positions and barrier heights for heavy-ion fusion reactions. (orig.)

A unified approach for radiative losses and backscattering in optical waveguides

International Nuclear Information System (INIS)

Melati, D; Morichetti, F; Melloni, A

2014-01-01

Sidewall roughness in optical waveguides represents a severe impairment for the proper functionality of photonic integrated circuits. The interaction between the propagating mode and the roughness is responsible for both radiative losses and distributed backscattering. In this paper, a unified vision on these extrinsic loss phenomena is discussed, highlighting the fundamental role played by the sensitivity of the effective index n eff of the optical mode to waveguide width variations. The n w model presented applies to both 2D slab waveguides and 3D laterally confined waveguides and is in very good agreement with existing models that individually describe radiative loss or backscattering only. Experimental results are presented, demonstrating the validity of the n w model for arbitrary waveguide geometries and technologies. This approach enables an accurate description of realistic optical waveguides and provides simple design rules for optimization of the waveguide geometry in order to reduce the propagation losses generated by sidewall roughness. (paper)

Sprache als Barriere (Language as a Barrier)

Science.gov (United States)

Mattheier, Klaus

1974-01-01

The concept of language barrier has its derivations in the fields of dialectology, sociology and psychology. In contemporary usage however, the concept has two meanings i.e. regional-cultural barrier and socio-cultural barrier. (Text is in German.) (DS)

A decision model to allocate protective safety barriers and mitigate domino effects

International Nuclear Information System (INIS)

Janssens, Jochen; Talarico, Luca; Reniers, Genserik; Sörensen, Kenneth

2015-01-01

In this paper, we present a model to support decision-makers about where to locate safety barriers and mitigate the consequences of an accident triggering domino effects. Based on the features of an industrial area that may be affected by domino accidents, and knowing the characteristics of the safety barriers that can be installed to stall the fire propagation between installations, the decision model can help practitioners in their decision-making. The model can be effectively used to decide how to allocate a limited budget in terms of safety barriers. The goal is to maximize the time-to-failure of a chemical installation ensuring a worst case scenario approach. The model is mathematically stated and a flexible and effective solution approach, based on metaheuristics, is developed and tested on an illustrative case study representing a tank storage area of a chemical company. We show that a myopic optimization approach, which does not take into account knock-on effects possibly triggered by an accident, can lead to a distribution of safety barriers that are not effective in mitigating the consequences of a domino accident. Moreover, the optimal allocation of safety barriers, when domino effects are considered, may depend on the so-called cardinality of the domino effects. - Highlights: • A model to allocate safety barriers and mitigate domino effects is proposed. • The goal is to maximize the escalation time of the worst case scenario. • The model provides useful recommendations for decision makers. • A fast metaheuristic approach is proposed to solve such a complex problem. • Numerical simulations on a realistic case study are shown

Adaptive management in the context of barriers in European freshwater ecosystems.

Science.gov (United States)

Birnie-Gauvin, Kim; Tummers, Jeroen S; Lucas, Martyn C; Aarestrup, Kim

2017-12-15

Many natural habitats have been modified to accommodate for the presence of humans and their needs. Infrastructures - such as hydroelectric dams, weirs, culverts and bridges - are now a common occurrence in streams and rivers across the world. As a result, freshwater ecosystems have been altered extensively, affecting both biological and geomorphological components of the habitats. Many fish species rely on these freshwater ecosystems to complete their lifecycles, and the presence of barriers has been shown to reduce their ability to migrate and sustain healthy populations. In the long run, barriers may have severe repercussions on population densities and dynamics of aquatic animal species. There is currently an urgent need to address these issues with adequate conservation approaches. Adaptive management provides a relevant approach to managing barriers in freshwater ecosystems as it addresses the uncertainties of dealing with natural systems, and accommodates for future unexpected events, though this approach may not be suitable in all instances. A literature search on this subject yielded virtually no output. Hence, we propose a step-by-step guide for implementing adaptive management, which could be used to manage freshwater barriers. Copyright © 2017 Elsevier Ltd. All rights reserved.

Patients' reports of barriers to expressing concerns during cancer consultations.

Science.gov (United States)

Brandes, Kim; Linn, Annemiek J; Smit, Edith G; van Weert, Julia C M

2015-03-01

To identify cancer patients' most influential barriers to expressing concerns during cancer consultations in a new manner by examining patients' reports of perceived barriers and perceived occurrence of barriers in consultations. Two online focus groups (N=16) and an online survey (N=236) were conducted among cancer patients and cancer survivors. The online focus groups and survey were used to examine two elements of patients' barriers, i.e., patients' reports of perceived barriers and perceived occurrence of barriers in consultations. Composite scores of these two elements were calculated to determine influential barriers. Results showed that the most influential barriers were related to providers' behavior (e.g., providers do not explicitly invite patients to express concerns) and the environment where the consultation takes place (e.g., perceived lack of time). The results of this study indicate that influential barriers to expressing concerns are barriers that patients cannot overcome themselves (i.e., they are related to providers' behavior or the environment of the consultation). A collaborative approach between researchers, providers and policy makers is needed to overcome these barriers. The results of this study can be used to develop strategies to overcome barriers to patients expressing concerns. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Shottky-barrier formation

International Nuclear Information System (INIS)

Guines, F.; Sanchez-Dehesa, J.; Flores, F.

1983-01-01

In this paper a realistic selfconsistent calculation of an abrupt metal-semiconductor junction is presented by means of a tight-binding approach. A specific Si-Ag junction has been considered, and the charge neutrality level as well as the barrier height have been determined in good agreement with experiments. For a generaljunction it is shown that the interface properties depend essentially on the characteristics of the first metal layer and its interaction with the semiconductor. (Author) [pt

Barrier performance researches for the safety evaluation

International Nuclear Information System (INIS)

Niibori, Yuichi

2004-01-01

So far, many researches were conducted to propose a scientific evidence (a safety case) for the realization of geological disposal in Japan. In order to regulate the geological disposal system of radioactive wastes, on the other hand, we need also a holistic approach to integrate various data related for the performance evaluations of the engineered barrier system and the natural barrier system. However, the scientific bases are not sufficient to establish the safety regulation for such a natural system. For example, we often apply the specific probability density function (PDF) to the uncertainty of barrier system due to the essential heterogeneity. However, the applicability is not clear in the regulation point of view. A viewpoint to understand such an applicability of PDFs has been presented. (author)

A qualitative, interprofessional analysis of barriers to and facilitators of implementation of the Department of Veterans Affairs' Clostridium difficile prevention bundle using a human factors engineering approach.

Science.gov (United States)

Yanke, Eric; Moriarty, Helene; Carayon, Pascale; Safdar, Nasia

2018-03-01

Clostridium difficile infection (CDI) is increasingly prevalent, severe, and costly. Adherence to infection prevention practices remains suboptimal. More effective strategies to implement guidelines and evidence are needed. Interprofessional focus groups consisting of physicians, resident physicians, nurses, and health technicians were conducted for a quality improvement project evaluating adherence to the Department of Veterans Affairs' (VA) nationally mandated C difficile prevention bundle. Qualitative analysis with a visual matrix display identified barrier and facilitator themes guided by the Systems Engineering Initiative for Patient Safety model, a human factors engineering approach. Several themes, encompassing both barriers and facilitators to bundle adherence, emerged. Rapid turnaround time of C difficile polymerase chain reaction testing was a facilitator of timely diagnosis. Too few, poorly located, and cluttered sinks were barriers to appropriate hand hygiene. Patient care workload and the time-consuming process of contact isolation precautions were also barriers to adherence. Multiple work system components serve as barriers to and facilitators of adherence to the VA CDI prevention bundle among an interprofessional group of health care workers. Organizational factors appear to significantly influence bundle adherence. Interprofessional perspectives are needed to identify barriers to and facilitators of bundle implementation, which is a necessary first step to address adherence to bundled infection prevention practices. Published by Elsevier Inc.

A new hybrid support vector machine–wavelet transform approach for estimation of horizontal global solar radiation

International Nuclear Information System (INIS)

Mohammadi, Kasra; Shamshirband, Shahaboddin; Tong, Chong Wen; Arif, Muhammad; Petković, Dalibor; Ch, Sudheer

2015-01-01

Highlights: • Horizontal global solar radiation (HGSR) is predicted based on a new hybrid approach. • Support Vector Machines and Wavelet Transform algorithm (SVM–WT) are combined. • Different sets of meteorological elements are used to predict HGSR. • The precision of SVM–WT is assessed thoroughly against ANN, GP and ARMA. • SVM–WT would be an appealing approach to predict HGSR and outperforms others. - Abstract: In this paper, a new hybrid approach by combining the Support Vector Machine (SVM) with Wavelet Transform (WT) algorithm is developed to predict horizontal global solar radiation. The predictions are conducted on both daily and monthly mean scales for an Iranian coastal city. The proposed SVM–WT method is compared against other existing techniques to demonstrate its efficiency and viability. Three different sets of parameters are served as inputs to establish three models. The results indicate that the model using relative sunshine duration, difference between air temperatures, relative humidity, average temperature and extraterrestrial solar radiation as inputs shows higher performance than other models. The statistical analysis demonstrates that SVM–WT approach enjoys very good performance and outperforms other approaches. For the best SVM–WT model, the obtained statistical indicators of mean absolute percentage error, mean absolute bias error, root mean square error, relative root mean square error and coefficient of determination for daily estimation are 6.9996%, 0.8405 MJ/m 2 , 1.4245 MJ/m 2 , 7.9467% and 0.9086, respectively. Also, for monthly mean estimation the values are 3.2601%, 0.5104 MJ/m 2 , 0.6618 MJ/m 2 , 3.6935% and 0.9742, respectively. Based upon relative percentage error, for the best SVM–WT model, 88.70% of daily predictions fall within the acceptable range of −10% to +10%

Introducing Meta-models for a More Efficient Hazard Mitigation Strategy with Rockfall Protection Barriers

Science.gov (United States)

Toe, David; Mentani, Alessio; Govoni, Laura; Bourrier, Franck; Gottardi, Guido; Lambert, Stéphane

2018-04-01

The paper presents a new approach to assess the effecctiveness of rockfall protection barriers, accounting for the wide variety of impact conditions observed on natural sites. This approach makes use of meta-models, considering a widely used rockfall barrier type and was developed from on FE simulation results. Six input parameters relevant to the block impact conditions have been considered. Two meta-models were developed concerning the barrier capability either of stopping the block or in reducing its kinetic energy. The outcome of the parameters range on the meta-model accuracy has been also investigated. The results of the study reveal that the meta-models are effective in reproducing with accuracy the response of the barrier to any impact conditions, providing a formidable tool to support the design of these structures. Furthermore, allowing to accommodate the effects of the impact conditions on the prediction of the block-barrier interaction, the approach can be successfully used in combination with rockfall trajectory simulation tools to improve rockfall quantitative hazard assessment and optimise rockfall mitigation strategies.

Intestinal barrier integrity and inflammatory bowel disease

DEFF Research Database (Denmark)

Holmberg, Fredrik Eric Olof; Pedersen, Jannie; Jørgensen, Peter

2018-01-01

Disruption of normal barrier function is a fundamental factor in the pathogenesis of inflammatory bowel disease, which includes increased epithelial cell death, modified mucus configuration, altered expression and distribution of tight junction-proteins, along with a decreased expression of antim......Disruption of normal barrier function is a fundamental factor in the pathogenesis of inflammatory bowel disease, which includes increased epithelial cell death, modified mucus configuration, altered expression and distribution of tight junction-proteins, along with a decreased expression...... of antimicrobial peptides. Inflammatory bowel disease is associated with life-long morbidity for affected patients, and both the incidence and prevalence is increasing globally, resulting in substantial economic strain for society. Mucosal healing and re-establishment of barrier integrity is associated......, novel treatment strategies to accomplish mucosal healing and to re-establish normal barrier integrity in inflammatory bowel disease are warranted, and luminal stem cell-based approaches might have an intriguing potential. Transplantation of in vitro expanded intestinal epithelial stem cells derived...

Utilizing Schottky barriers to suppress short-channel effects in organic transistors

Science.gov (United States)

Fernández, Anton F.; Zojer, Karin

2017-10-01

Transistors with short channel lengths exhibit profound deviations from the ideally expected behavior. One of the undesired short-channel effects is an enlarged OFF current that is associated with a premature turn on of the transistor. We present an efficient approach to suppress the OFF current, defined as the current at zero gate source bias, in short-channel organic transistors. We employ two-dimensional device simulations based on the drift-diffusion model to demonstrate that intentionally incorporating a Schottky barrier for injection enhances the ON-OFF ratio in both staggered and coplanar transistor architectures. The Schottky barrier is identified to directly counteract the origin of enlarged OFF currents: Short channels promote a drain-induced barrier lowering. The latter permits unhindered injection of charges even at reverse gate-source bias. An additional Schottky barrier hampers injection for such points of operations. We explain how it is possible to find the Schottky barrier of the smallest height necessary to exactly compensate for the premature turn on. This approach offers a substantial enhancement of the ON-OFF ratio. We show that this roots in the fact that such optimal barrier heights offer an excellent compromise between an OFF current diminished by orders of magnitude and an only slightly reduced ON current.

Approaches to radiation guidelines for space travel

International Nuclear Information System (INIS)

Fry, R.J.M.

1984-01-01

There are obvious risks in space travel that have loomed larger than any risk from radiation. Nevertheless, NASA has maintained a radiation program that has involved maintenance of records of radiation exposure, and planning so that the astronauts' exposures are kept as low as possible, and not just within the current guidelines. These guidelines are being reexamined currently by NCRP Committee 75 because new information is available, for example, risk estimates for radiation-induced cancer and about the effects of HZE particles. Furthermore, no estimates of risk or recommendations were made for women in 1970 and must now be considered. The current career limit is 400 rem. The appropriateness of this limit and its basis are being examined as well as the limits for specific organs. There is now considerably more information about age-dependency for radiation and this will be taken into account. Work has been carried out on the so-called microlesions caused by HZE particles and on the relative carcinogenic effect of heavy ions, including iron. A remaining question is whether the fluence of HZE particles could reach levels of concern in missions under consideration. Finally, it is the intention of the committee to indicate clearly the areas requiring further research. 21 references, 1 figure, 7 tables

Cerebrovascular Acute Radiation Syndrome : Radiation Neurotoxins, Mechanisms of Toxicity, Neuroimmune Interactions.

Science.gov (United States)

Popov, Dmitri; Maliev, Slava

Introduction: Cerebrovascular Acute Radiation Syndrome (CvARS) is an extremely severe in-jury of Central Nervous System (CNS) and Peripheral Nervous System (PNS). CvARS can be induced by the high doses of neutron, heavy ions, or gamma radiation. The Syndrome clinical picture depends on a type, timing, and the doses of radiation. Four grades of the CvARS were defined: mild, moderate, severe, and extremely severe. Also, four stages of CvARS were developed: prodromal, latent, manifest, outcome -death. Duration of stages depends on the types, doses, and time of radiation. The CvARS clinical symptoms are: respiratory distress, hypotension, cerebral edema, severe disorder of cerebral blood microcirculation, and acute motor weakness. The radiation toxins, Cerebro-Vascular Radiation Neurotoxins (SvARSn), determine development of the acute radiation syndrome. Mechanism of action of the toxins: Though pathogenesis of radiation injury of CNS remains unknown, our concept describes the Cv ARS as a result of Neurotoxicity and Excitotoxicity, cell death through apoptotic necrosis. Neurotoxicity occurs after the high doses radiation exposure, formation of radiation neuro-toxins, possible bioradicals, or group of specific enzymes. Intracerebral hemorrhage can be a consequence of the damage of endothelial cells caused by radiation and the radiation tox-ins. Disruption of blood-brain barrier (BBB)and blood-cerebrospinal fluid barrier (BCFB)is possibly the most significant effect of microcirculation disorder and metabolic insufficiency. NMDA-receptors excitotoxic injury mediated by cerebral ischemia and cerebral hypoxia. Dam-age of the pyramidal cells in layers 3 and 5 and Purkinje cell layer the cerebral cortex , damage of pyramidal cells in the hippocampus occur as a result of cerebral ischemia and intracerebral bleeding. Methods: Radiation Toxins of CV ARS are defined as glycoproteins with the molec-ular weight of RT toxins ranges from 200-250 kDa and with high enzymatic activity

Perception of community pharmacists towards the barriers to enhanced pharmacy services in the healthcare system of Dubai: a quantitative approach.

Science.gov (United States)

Rayes, Ibrahim K; Hassali, Mohamed A; Abduelkarem, Abduelmula R

2015-01-01

In many developing countries, pharmacists are facing many challenges while they try to enhance the quality of services provided to patients approaching community pharmacies. To explore perception of community pharmacists in Dubai regarding the obstacles to enhanced pharmacy services using a part of the results from a nation-wide quantitative survey. A questionnaire was distributed to 281 full-time licensed community pharmacists in Dubai. The questionnaire had 5 inter-linked sections: demographic information, information about the pharmacy, interaction with physicians, pharmacists' current professional role, and barriers to enhanced pharmacy services. About half of the respondents (45.4%, n=90) agreed that pharmacy clients under-estimate them and 52.5% (n=104) felt the same by physicians. About 47.5% (n=94) of the respondents felt that they are legally unprotected against profession's malpractice. Moreover, 64.7% (n=128) stated that pharmacy practice in Dubai turned to be business-focused. In addition, 76.8% (n=252) found that one of the major barriers to enhanced pharmacy services is the high business running cost. Pharmacists screened tried to prove that they are not one of the barriers to optimized pharmacy services as 62.7% (n=124) disagreed that they lack appropriate knowledge needed to serve community and 67.7% (n=134) gave the same response when asked whether pharmacy staff lack confidence when treating consumers or not. Although being well established within the community, pharmacists in Dubai negatively perceived their own professional role. They stated that there are number of barriers which hinder optimized delivery of pharmacy services like under-estimation by pharmacy clients and other healthcare professionals, pressure to make sales, and high running cost.

Injury of the blood-testies barrier after low-dose-rate chronic radiation exposure

Energy Technology Data Exchange (ETDEWEB)

Sohn, Young Hoon; Bae Min Ji; Lee, Chang Geun; Yang, Kwang Mo; Jur, Kyu; Kim, Jong Sun [Dongnam Institute of Radiological and Medical Science, Busan (Korea, Republic of)

2014-04-15

The systemic effect of radiation increases in proportionally with the dose and dose rate. Little is known concerning the relationships between harmful effects and accumulated dose, which is derived from continuous low-dose rate radiation exposure. Recent our studies show that low-dose-rate chronic radiation exposure (3.49 mGy/h) causes adverse effects in the testis at a dose of 2 Gy (6 mGy/h). However, the mechanism of the low-dose-rate 2 Gy irradiation induced testicular injury remains unclear. The present results indicate that low-dose rate chronic radiation might affect the BTB permeability, possibly by decreasing levels of ZO-1, Occludin-1, and NPC-2. Furthermore, our results suggest that there is a risk of male infertility through BTB impairment even with low-dose-rate radiation if exposure is continuous.

Barrier mechanisms in the Drosophila blood-brain barrier

Directory of Open Access Journals (Sweden)

Samantha Jane Hindle

2014-12-01

Full Text Available The invertebrate blood-brain barrier field is growing at a rapid pace and, in recent years, studies have shown a physiologic and molecular complexity that has begun to rival its vertebrate counterpart. Novel mechanisms of paracellular barrier maintenance through GPCR signaling were the first demonstrations of the complex adaptive mechanisms of barrier physiology. Building upon this work, the integrity of the invertebrate blood-brain barrier has recently been shown to require coordinated function of all layers of the compound barrier structure, analogous to signaling between the layers of the vertebrate neurovascular unit. These findings strengthen the notion that many blood-brain barrier mechanisms are conserved between vertebrates and invertebrates, and suggest that novel findings in invertebrate model organisms will have a significant impact on the understanding of vertebrate BBB functions. In this vein, important roles in coordinating localized and systemic signaling to dictate organism development and growth are beginning to show how the blood-brain barrier can govern whole animal physiologies. This includes novel functions of blood-brain barrier gap junctions in orchestrating synchronized neuroblast proliferation, and of blood-brain barrier secreted antagonists of insulin receptor signaling. These advancements and others are pushing the field forward in exciting new directions. In this review, we provide a synopsis of invertebrate blood-brain barrier anatomy and physiology, with a focus on insights from the past 5 years, and highlight important areas for future study.

Enhancement of Hole Confinement by Monolayer Insertion in Asymmetric Quantum-Barrier UVB Light Emitting Diodes

KAUST Repository

Janjua, Bilal

2014-04-01

We study the enhanced hole confinement by having a large bandgap AlGaN monolayer insertion (MLI) between the quantum well (QW) and the quantum barrier (QB). The numerical analysis examines the energy band alignment diagrams, using a self-consistent 6 × 6 k ·p method and, considering carrier distribution, recombination rates (Shockley-Reed-Hall, Auger, and radiative recombination rates), under equilibrium and forward bias conditions. The active region is based on AlaGa1-aN (barrier)/AlbGa1-bN (MLI)/AlcGa1-cN (well)/AldGa1-dN (barrier), where b > d > a > c. A large bandgap AlbGa1-bN mono layer, inserted between the QW and QB, was found to be effective in providing stronger hole confinement. With the proposed band engineering scheme, an increase of more than 30% in spatial overlap of carrier wavefunction was obtained, with a considerable increase in carrier density and direct radiative recombination rates. The single-QW-based UV-LED was designed to emit at 280 nm, which is an effective wavelength for water disinfection.

Sustainable Supply Chain Management Implementation–Enablers and Barriers in the Textile Industry

Directory of Open Access Journals (Sweden)

Nelly Oelze

2017-08-01

Full Text Available The distinct definition of accordance in the perceived barriers and enablers for sustainable supply chain management (SSCM policy implementation has been the subject of various research studies, but a distinct focus on the textile sector has been the object of limited previous attention. However, it has been found that it affects the approach to developments in company approaches to sustainable supply chain management within that industry. This article presents the results of an in-depth comparative case study analysis, drawing on 23 interviews with managers of 10 companies from the textile industry. The analysis demonstrates that specific modes of collaboration can both enable an effective SSCM and diminish barriers for policy implementation. The width and depth varies between a collaborative management approach for an effective internal SSCM versus industry collaboration and buyer supplier collaboration to address external barriers and enablers.

Novel approach to analyzing the carcinogenic effect of ionizing radiations.

Science.gov (United States)

Gregoire, O; Cleland, M R

2006-01-01

Cancer incidence of ionizing radiations exposure is considered to be proportional to the absorbed dose. However, there are disagreements between substantial amounts of epidemiological studies. In this study, we question the basic relationship of the risk estimate with total accumulated dose, and reanalyse available data on the basis of a daily dose concept. The data analysed were relative mortality risk from all cancers vs. total-body dose on a daily basis. References have been selected on the basis of objective criteria. We found that this relationship removes major discrepancies. It revises estimates of low-level exposures, with consequences regarding nuclear power plants safety, wastes management, medical applications or homeland security. The idea that the dose rate may have a significant impact on health effects of ionizing radiations is not new, but has always been considered as a parameter in models based on integrated dose. The novel approach in this paper is to consider the primary relevant parameter as an average of dose rate over a time period of one day. This is an argument to revise the whole philosophy in radioprotection, and place regulatory limits on specific locations instead of annual limits relevant to individual persons.

CMHC research project: Testing of air barrier construction details, II: Report

Energy Technology Data Exchange (ETDEWEB)

1993-01-01

Air leakage control through the building envelope of wood framed houses is more important than ever. The leakage of air is controlled by the air barrier system. There are several new technologies to construct an air barrier system for the building envelope. These are the Poly Approach, the Air Drywall Approach and the EASE system. The development of these systems was undertaken primarily by the building community without significant research and development. The purpose of this study was to determine the actual performance of several different types of construction details for each of the different approaches. Each of these details was designed and constructed using one of the air barrier methods and tested in the laboratory. The test details included the sill plate, the partition wall, the stair stringer, the electrical outlets, the bathtub detail, the plumbing stack detail, the metal chimney detail, the bathroom fan detail and the EASE wall system.

Pion Production from Proton Synchrotron Radiation under Strong Magnetic Field in Relativistic Quantum Approach

Directory of Open Access Journals (Sweden)

Maruyama Tomoyuki

2016-01-01

Full Text Available We study pion production from proton synchrotron radiation in the presence of strong magnetic fields by using the exact proton propagator in a strong magnetic field and explicitly including the anomalous magnetic moment. Results in this exact quantum-field approach do not agree with those obtained in the semi-classical approach. Furthermore, we also find that the anomalous magnetic moment of the proton greatly enhances the production rate about by two orders of magnitude, and that the polar angle of an emitted pion is the same as that of an initial proton.

Photodetector of ultra-violet radiation

International Nuclear Information System (INIS)

Dorogan, V.; Vieru, T.; Coseac, V.; Chirita, F.

1999-01-01

The invention relates to photodetectors on the semiconductors base, in particular, to photodetectors of ultra-violet radiation and can be used in the optoelectronics systems for determining the intensity and dose of ultraviolet radiation emitted by the Sun and other sources. In the structure of the photodetector of ultraviolet radiation with a superficial potential barrier formed of semiconductors A 3 B 5 with the prohibited power width Eg 1 , solid solutions thereof with the prohibited power width Eg 2 and SnO 2 or ITO, in the semiconductors A 3 B 5 at a surface distance less than the absorption length of the visible radiation it is formed an isotype heterojunction between the semiconductors A 3 B 5 and solid solutions thereof with the prohibited power width Eg 2 > Eg 1 . The technical result consists in manufacturing of a photodetector sensitive solely to the ultraviolet radiation

A concept mapping approach to identifying the barriers to implementing an evidence-based sports injury prevention programme.

Science.gov (United States)

Donaldson, Alex; Callaghan, Aisling; Bizzini, Mario; Jowett, Andrew; Keyzer, Patrick; Nicholson, Matthew

2018-01-20

Understanding the barriers to programme use is important to facilitate implementation of injury prevention programmes in real-word settings. This study investigated the barriers to coaches of adolescent female soccer teams, in Victoria, Australia, implementing the evidence-based FIFA 11+ injury prevention programme. Concept mapping with data collected from 19 soccer coaches and administrators. Brainstorming generated 65 statements as barriers to 11+ implementation. After the statements were synthesised and edited, participants sorted 59 statements into groups (mean, 6.2 groups; range, 3-10 groups). Multidimensional scaling and hierarchical cluster analysis identified a six-cluster solution: Lack of 11+ knowledge among coaches (15 statements), Lack of player enjoyment and engagement (14), Lack of link to football-related goals (11), Lack of facilities and resources (8), Lack of leadership (6) and Lack of time at training (5). Statements in the 'Lack of 11+ knowledge among coaches' cluster received the highest mean importance (3.67 out of 5) and feasibility for the Football Federation to address (3.20) rating. Statements in the 'Lack of facilities and resources' cluster received the lowest mean importance rating (2.23), while statements in the 'Lack of time at training' cluster received the lowest mean feasibility rating (2.19). A multistrategy, ecological approach to implementing the 11+-with specific attention paid to improving coach knowledge about the 11+ and how to implement it, linking the 11+ to the primary goal of soccer training, and organisational leadership-is required to improve the uptake of the 11+ among the targeted coaches. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Radioactivity induced by neutrons: Enrico Fermi and a thermodynamic approach to radiative capture

Science.gov (United States)

De Gregorio, Alberto

2006-07-01

When Fermi learned that slow neutrons are much more effective than fast ones in inducing radioactivity, he explained this phenomenon by mentioning the well-known scattering cross section between neutrons and protons. At this early stage, he did not refer to the capture cross section by target nuclei. At the same time a thermodynamic approach to neutron-proton capture was being discussed by physicists: neutron capture was interpretated as the reverse of deuteron photodissociation and detailed balance among neutrons, protons, deuterons, and radiation was invoked. This thermodynamic approach might underlie Fermi's early explanation of the great efficiency of slow neutrons. Fermi repeatedly used a thermodynamic approach that had been used in describing some of the physical properties of conductors by Richardson and had been influential in Fermi's youth.

Barrier for cold-fusion production of superheavy elements

International Nuclear Information System (INIS)

Ichikawa, Takatoshi; Iwamoto, Akira; Moeller, Peter; Sierk, Arnold J.

2005-01-01

We estimate the fusion-barrier height B fu (two-body) for approaching ions in cold-fusion reactions in a model where the projectile deformation and quadrupole zero-point vibrational energy are taken into account. This barrier height is defined as the barrier energy at the target and projectile separation distance where an original oblate deformation of projectile and/or target caused by a repulsive Coulomb force turns into a large prolate deformation caused by the attractive nuclear force as the target and projectile come closer. The instability develops before touching because the attractive short-range nuclear force overcomes the repulsive Coulomb force and the shape-stabilizing effect of shell structure. The shell structure of the doubly magic 208 Pb target is sufficiently strong that its shape remains very close to spherical in all cases studied here. The fusion potential for approaching ions in the two-body channel is calculated in the macroscopic-microscopic model with the quadrupole vibrational zero-point energy obtained in the WKB approximation. We compare our results with data from 10 experimental cold-fusion reactions and with the Bass barriers. Differences and similarities between the Yukawa-plus-exponential model and the Bass model are discussed. We also calculate five-dimensional potential-energy surfaces for the single compound system and show that well-established fission and fusion valleys are both present. For heavy systems, B fu (two-body) becomes lower than the fission barrier just beyond the ground state of the compound system. In the vicinity of this transition, the optimum collision energy for formation of evaporation residues can be expected to depend in a delicate fashion on the interplay among B fu (two-body) , the fusion valley, the fission barrier of the compound system, and the one- and two-neutron separation energies S 1n and S 2n . We discuss these issues in detail and calculate fission-barrier heights. Except for reactions in which

Implementation of renewable energy technologies - Opportunities and barriers. Ghana country study

Energy Technology Data Exchange (ETDEWEB)

Edjekumhene, I.; Atakora, S.B.; Atta-Konadu, R.; Brew-Hammond, A. [Kumasi Inst. og Technology and Environment (Ghana)

2001-07-01

This report presents the experience of Ghana in the development, utilisation and promotion of Renewable Energy Technologies (RETs). The report gives a general overview of the state of RETs, describes past/existing institutional, regulatory and policy framework, identifies key barriers to and opportunities for RETs, and recommends directional changes needed to remove barriers and promote wide-scale adoption of RETs in Ghana. A total of eight RETs - biomass-fired dryers, sawdust stoves, sawdust briquette, biogas, solar crop dryer, solar water heater, solar water pump and small hydro power - are covered in the report. Analyses of barriers to the eight RETs are carried out using a framework approach that categorises barriers into socio-technical, economic and crosscutting barriers. Financial analyses, as opposed to economic analyses, have been carried out for all the selected RETs. The report also incorporates stake holders' perspectives and views on barriers and how they can be removed. Ghana is endowed with several renewable energy resources like solar radiation, small hydro, biomass, and wind. Exploitation of Ghana's renewable energy resources has been carried out under two main policy regimes - PND Law 62 (1983) and the Energy Sector Development Programme (ESDP). Several measures and instruments have been employed in the implementation of renewable energy policies. The main measures used are research and development, information and eduction, and some normative measures (like the passing of PNDC Law 62 and the Energy Commission Law). Some economic instruments, such as subsidies, taxes, pricing, financing and duty waiver/reduction, have been used as well but only to a limited extent. The effective development, implementation and dissemination of all the RETs studied are hampered by several barriers, which can be grouped into three main categories - Socio-technical barriers, economic barriers and crosscutting barriers. Socio-technical barriers refer to

Implementation of renewable energy technologies - Opportunities and barriers. Ghana country study

Energy Technology Data Exchange (ETDEWEB)

Edjekumhene, I; Atakora, S B; Atta-Konadu, R; Brew-Hammond, A [Kumasi Inst. og Technology and Environment (Ghana)

2001-07-01

This report presents the experience of Ghana in the development, utilisation and promotion of Renewable Energy Technologies (RETs). The report gives a general overview of the state of RETs, describes past/existing institutional, regulatory and policy framework, identifies key barriers to and opportunities for RETs, and recommends directional changes needed to remove barriers and promote wide-scale adoption of RETs in Ghana. A total of eight RETs - biomass-fired dryers, sawdust stoves, sawdust briquette, biogas, solar crop dryer, solar water heater, solar water pump and small hydro power - are covered in the report. Analyses of barriers to the eight RETs are carried out using a framework approach that categorises barriers into socio-technical, economic and crosscutting barriers. Financial analyses, as opposed to economic analyses, have been carried out for all the selected RETs. The report also incorporates stake holders' perspectives and views on barriers and how they can be removed. Ghana is endowed with several renewable energy resources like solar radiation, small hydro, biomass, and wind. Exploitation of Ghana's renewable energy resources has been carried out under two main policy regimes - PND Law 62 (1983) and the Energy Sector Development Programme (ESDP). Several measures and instruments have been employed in the implementation of renewable energy policies. The main measures used are research and development, information and eduction, and some normative measures (like the passing of PNDC Law 62 and the Energy Commission Law). Some economic instruments, such as subsidies, taxes, pricing, financing and duty waiver/reduction, have been used as well but only to a limited extent. The effective development, implementation and dissemination of all the RETs studied are hampered by several barriers, which can be grouped into three main categories - Socio-technical barriers, economic barriers and crosscutting barriers. Socio-technical barriers refer to resource

A spectral blanking-out controller for demonstration of information barrier technology

International Nuclear Information System (INIS)

Liu Suping; Gong Jian; Hu Guangchun; Zhang Jianhua

2006-01-01

Information barrier technology has become more and more important in the R and D of radiation fingerprint verification associated with classified items such as nuclear warheads, nuclear components and military-used nuclear materials. The function of information barriers is two-fold: one is to prevent the classified information from leaking out; the other is to provide creditable verification. To fulfill these two functions, the information barriers for a viable verification system (including all its hardware and software) must be designed on the basic principles of protecting classified information and the ability to authenticate. The Spectral Blanking-out Controller (SBC) is developed to illustrate the two functions of the information barriers and to explore some practice measures to meet the required design fundamentals. This paper briefs the task assigned to the SBC, the specific design concerns and the practical information barrier measures. The R and D of the SBC embodies the concepts of information barrier technology and has to conform to the basic guidelines: If a verification system is expected to possess strict information barriers, the design of the system must be integrative with due considerations given to the factors such as the efficiency of the verification technique, the possible measures to protect the classified information from directly or indirectly leaking out, the complete openness in all aspects of the system for the inspectors to authenticate the system for the sake of achieving certain degree of confidence on the verification results. (authors)

Polymers for subterranean containment barriers for underground storage tanks (USTs)

International Nuclear Information System (INIS)

Heiser, J.H.; Colombo, P.; Clinton, J.

1992-12-01

The US Department of Energy (DOE) set up the Underground Storage Tank Integrated Demonstration Program (USTID) to demonstrate technologies for the retrieval and treatment of tank waste, and closure of underground storage tanks (USTs). There are more than 250 underground storage tanks throughout the DOE complex. These tanks contain a wide variety of wastes including high level, low level, transuranic, mixed and hazardous wastes. Many of the tanks have performed beyond the designed lifetime resulting in leakage and contamination of the local geologic media and groundwater. To mitigate this problem it has been proposed that an interim subterranean containment barrier be placed around the tanks. This would minimize or prevent future contamination of soil and groundwater in the event that further tank leakages occur before or during remediation. Use of interim subterranean barriers can also provide sufficient time to evaluate and select appropriate remediation alternatives. The DOE Hanford site was chosen as the demonstration site for containment barrier technologies. A panel of experts for the USTID was convened in February, 1992, to identify technologies for placement of subterranean barriers. The selection was based on the ability of candidate grouts to withstand high radiation doses, high temperatures and aggressive tank waste leachates. The group identified and ranked nine grouting technologies that have potential to place vertical barriers and five for horizontal barriers around the tank. The panel also endorsed placement technologies that require minimal excavation of soil surrounding the tanks

Development of Diffusion barrier coatings and Deposition Technologies for Mitigating Fuel Cladding Chemical Interactions (FCCI)

Energy Technology Data Exchange (ETDEWEB)

Sridharan, Kumar; Allen, Todd; Cole, James

2013-02-27

The goal of this project is to develop diffusion barrier coatings on the inner cladding surface to mitigate fuel-cladding chemical interaction (FCCI). FCCI occurs due to thermal and radiation enhanced inter-diffusion between the cladding and fuel materials, and can have the detrimental effects of reducing the effective cladding wall thickness and lowering the melting points of the fuel and cladding. The research is aimed at the Advanced Burner Reactor (ABR), a sodium-cooled fast reactor, in which higher burn-ups will exacerbate the FCCI problem. This project will study both diffusion barrier coating materials and deposition technologies. Researchers will investigate pure vanadium, zirconium, and titanium metals, along with their respective oxides, on substrates of HT-9, T91, and oxide dispersion-strengthened (ODS) steels; these materials are leading candidates for ABR fuel cladding. To test the efficacy of the coating materials, the research team will perform high-temperature diffusion couple studies using both a prototypic metallic uranium fuel and a surrogate the rare-earth element lanthanum. Ion irradiation experiments will test the stability of the coating and the coating-cladding interface. A critical technological challenge is the ability to deposit uniform coatings on the inner surface of cladding. The team will develop a promising non-line-of-sight approach that uses nanofluids . Recent research has shown the feasibility of this simple yet novel approach to deposit coatings on test flats and inside small sections of claddings. Two approaches will be investigated: 1) modified electrophoretic deposition (MEPD) and 2) boiling nanofluids. The coatings will be evaluated in the as-deposited condition and after sintering.

Radiation protection in nuclear facilities. Complexity versus systematic approach; Strahlenschutz in Kernanlagen. Komplexitaet versus Systematik

Energy Technology Data Exchange (ETDEWEB)

Jahn, S.G. [Eidgenoessisches Nuklearsicherheitsinspektorat (ENSI), Brugg (Switzerland)

2016-07-01

Considering the amount of radiation sources in nuclear power plants, their chemical and physical state, the miscellaneous exposure pathways as well as varying limits, reference values and constraints for the protection of persons, tissues and environment, the number of different exposure situations per year ranges up to several thousands. With this complexity a systematic approach for planning a new facility, modification, decommissioning or operation is necessary to ensure complete radiation protection without gaps. The Swiss federal nuclear safety inspectorate (ENSI) is developing and testing a system of safety objectives, functions and measures, which is complementary to the IAEA fundamental safety objectives and requirements.

Spectral Kernel Approach to Study Radiative Response of Climate Variables and Interannual Variability of Reflected Solar Spectrum

Science.gov (United States)

Jin, Zhonghai; Wielicki, Bruce A.; Loukachine, Constantin; Charlock, Thomas P.; Young, David; Noeel, Stefan

2011-01-01

The radiative kernel approach provides a simple way to separate the radiative response to different climate parameters and to decompose the feedback into radiative and climate response components. Using CERES/MODIS/Geostationary data, we calculated and analyzed the solar spectral reflectance kernels for various climate parameters on zonal, regional, and global spatial scales. The kernel linearity is tested. Errors in the kernel due to nonlinearity can vary strongly depending on climate parameter, wavelength, surface, and solar elevation; they are large in some absorption bands for some parameters but are negligible in most conditions. The spectral kernels are used to calculate the radiative responses to different climate parameter changes in different latitudes. The results show that the radiative response in high latitudes is sensitive to the coverage of snow and sea ice. The radiative response in low latitudes is contributed mainly by cloud property changes, especially cloud fraction and optical depth. The large cloud height effect is confined to absorption bands, while the cloud particle size effect is found mainly in the near infrared. The kernel approach, which is based on calculations using CERES retrievals, is then tested by direct comparison with spectral measurements from Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) (a different instrument on a different spacecraft). The monthly mean interannual variability of spectral reflectance based on the kernel technique is consistent with satellite observations over the ocean, but not over land, where both model and data have large uncertainty. RMS errors in kernel ]derived monthly global mean reflectance over the ocean compared to observations are about 0.001, and the sampling error is likely a major component.

Legislating for occupational exposure to sources of natural radiation- the UK approach

International Nuclear Information System (INIS)

Higham, N.; Walker, S.; Thomas, G.

2004-01-01

Title VII of EC Directive 96/29/Euratom (the 1996 BSS Directive) for the first time requires Member States to take action in relation to work activities within which the presence of natural radiation sources leads to a significant increase in the exposure of workers or members of the public which cannot be disregarded from the radiation protection point of view. The UK in fact has had legal requirements relating to occupational exposure to natural radiation sources since 1985, in the Ionising Radiations Regulations 1985, made to implement the bulk of the provisions of the previous BSS Directive (80/836/Euratom, as amended by 84/467/Euratom). The Ionising Radiations Regulations 1999, that implement the worker protection requirements of the 1996 Euratom BSS Directive, include similar provisions. The definition of radioactive substance includes any substance which contains one or more radionuclides whose activity cannot be disregarded for the purposes of radiation protection. This means that some low specific activity ores and sands fall within this definition and are therefore subject to relevant requirements of the Regulations. Further advice is given on circumstances in which this may apply. Radon is covered more explicitly by applying the regulations to any work carried out in an atmosphere containing radon 222 gas at a concentration in air, averaged over any 24 hour period, exceeding 400 Bq m-3 except where the concentration of the short-lived daughters of radon 222 in air averaged over any 8 hour working period does not exceed 6.24 x 10-7Jm-3. The Health and Safety Executive pursues a policy of raising awareness of the potential for exposure to radon in the workplace and targeting those employers likely to have a radon problem (based on the use of existing information on homes). The regulatory approach has been to seek remedial building measures so that the workplace is removed from control. HSE is able to offer advice about getting their workplace tested and

Applying radiation approaches to the control of public risks from chemical agents

International Nuclear Information System (INIS)

Alexander, R.E.

1989-01-01

IF a hazardous agent has a threshold, prevention is the obvious measure of success. To the eyes of this author, success is also achieveable for a hazardous agent that may have no threshold and that causes its effects in a probabilistic manner. First, the technical people responsible for protection must be given a reasonable, well defined risk objective by governmental authorities. To the extent that they meet that objective (1) without unnecessarily increasing operational costs, (2) without interfering unnecessarily with operational activities, and (3) without diverting resources away from greater risks, they are successful. Considering these three qualifications, radiation protection for members of the public can hardly be presented as the panacea for other hazardous agents. It would be an error to dismiss the improvement opportunities discussed above as being of acdemic interest only. Decades of experience with radiation have demonstrated that these problems are both real adn significant. In the US the axioms discussed above are accepted as scientific fact for radiation by many policy makers, the news media and the public. For any operation the collective dose is calculated using zero dose as the lower limit of integration, the results are converted to cancer deaths using the risk coefficients, and decisions are made as though these deaths would actually occur without governmental intervention. As a result, billions of dollars and a very large number of highly skilled persons are being expended to protect against radiation doses far smaller than geographical variations in the natural radiation background. These expenditures are demanded by, and required for well-meaning, nontechnical people who have been misled. It is often stated by knowledgeable people that if the degree of protection required for radiation were also to be requested for the other hazards, human progress would come to a halt. If the radiation approaches are to be used in the control of public

Acute radiation sickness - morphology of CNS syndrome

International Nuclear Information System (INIS)

Kamarad, V.

1989-01-01

The effect was studied of supralethal doses of 60 Co gamma radiation on morphological changes in the brains of laboratory animals. For experiments, female rats irradiated with doses of 15 to 960 Gy, female mice irradiated with doses of 50 to 300 Gy and dogs irradiated with 6 to 500 Gy were used. For evaluation of the changes, light microscopy, electron microscopy and histochemistry were employed. The findings generally agreed with the results by other authors whose numerous studies are reviewed in detail. They included brain edema, alterations in enzyme activities, dystrophic changes and hemorrhages in nerve cells, marked structural changes in blood capillaries, damage of endothelial cells, etc. The observed changes in the activities of blood-brain barrier enzymes, increased pinocytotic activity and the formation of endothelial tunnels accompanied with necrosis of part of endothelial cells are clear morphological manifestations of marked alterations in the function of the blood-brain barrier that result in brain edema development. The increased permeability of the blood-brain barrier significantly worsens primary changes induced by radiation, especially in nerve cels, and adversely affects possible repair processes. (L.O.). 146 figs., 8 tabs., 352 refs

On the porosity of barrier layers

Directory of Open Access Journals (Sweden)

J. Mignot

2009-09-01

Full Text Available Barrier layers are defined as the layer between the pycnocline and the thermocline when the latter are different as a result of salinity stratification. We present a revisited 2-degree resolution global climatology of monthly mean oceanic Barrier Layer (BL thickness first proposed by de Boyer Montégut et al. (2007. In addition to using an extended data set, we present a modified computation method that addresses the observed porosity of BLs. We name porosity the fact that barrier layers distribution can, in some areas, be very uneven regarding the space and time scales that are considered. This implies an intermittent alteration of air-sea exchanges by the BL. Therefore, it may have important consequences for the climatic impact of BLs. Differences between the two computation methods are small for robust BLs that are formed by large-scale processes. However, the former approach can significantly underestimate the thickness of short and/or localized barrier layers. This is especially the case for barrier layers formed by mesoscale mechanisms (under the intertropical convergence zone for example and along western boundary currents and equatorward of the sea surface salinity subtropical maxima. Complete characterisation of regional BL dynamics therefore requires a description of the robustness of BL distribution to assess the overall impact of BLs on the process of heat exchange between the ocean interior and the atmosphere.

CMHC research project: Testing of air barriers construction details: Report

Energy Technology Data Exchange (ETDEWEB)

1991-01-01

This project was conducted to quantify the air leakage characteristics of the header joist, the electric outlets, and the window openings in wood-frame walls. The study evaluated the sealed internal membrane method, where polyethylene sheet and sealant provide the air barrier; the external air barrier method, which uses a continuous vapour permeable membrane (spun-bonded olefin film), sandwiched between two layers of external wall sheathing; and the airtight drywall method, where the interior gypsum board finish, together with framing materials and gaskets, are used as the air barrier. In addition, the traditional approach to wood-frame wall construction, where no special attention is given to achieving a continuous air barrier, was evaluated for comparison.

Barriers to and Facilitators of Inter-Organizational Coordination in Response to Disasters: A Grounded Theory Approach.

Science.gov (United States)

Bahadori, Mohammadkarim; Khankeh, Hamid Reza; Zaboli, Rouhollah; Ravangard, Ramin; Malmir, Isa

2017-06-01

Coordination is a major challenge in the field of health in disasters, mostly because of the complex nature of health-related activities. This was a qualitative study based on the grounded theory approach. A total of 22 experts in the field of health in disasters participated in the study. The data were collected through in-depth interviews and literature review. The collected data were then analyzed by use of MAXQDA 2010 software (VERBI Software GmbH). The lack of a strategic view in the field of health in disasters, a lack of coordination of necessities and infrastructures, insufficient enforcement, a higher priority given to an organizational approach rather than a national approach, and the field of disasters not being a priority in the health system were noted as barriers to inter-organizational coordination. The facilitators of inter-organizational coordination noted were the importance of public participation in the field of health in disasters, having a process and systematic view in the field of health in disasters, the necessity of understanding and managing resources and information in the field of health in disasters, and having a feedback and evaluation system in the health system after disasters. It is recommended that developing common beliefs and goals be given priority in making plans and policies in the field of health in disasters. (Disaster Med Public Health Preparedness. 2017;11:318-325).

Reduction of occupational radiation exposure to staff - a quality management approach

International Nuclear Information System (INIS)

Crouch, J.

2007-01-01

Positron Emission. Tomography (PET) imaging has expanded in Australia in recent years and is a recognised technique to diagnose cancer, neurological and heart disease. The high-energy gamma rays (51 I KeV) produced from the annihilation reaction in PET and their increased penetration compared to Tc- 99 m (HOKeV) emissions results in a higher radiation exposure to staff compared to other types of imaging such as X-Ray, CT (computer tomography) and MR1 (magnetic resonance imaging) and general nuclear medicine. The project scope was to reduce the occupational radiation exposure to staff working within the imaging section of the WA PET/Cyclotron Service by utilising a continuous quality improvement, process. According to the Australian Council on Healthcare Standards (ACHS) continual quality improvement is critical for healthcare in Australia (The EQUIP Guide, 2002, p. 1-1 ). The continuous quality improvement approach selected is appropriate for the organisation and the PET imaging process based on the Evaluation and Quality Improvement Program (EQUIP) which is the recognised standard for the health care industry in Australia

Dispersion relation approach to sub-barrier heavy ion fusion reactions

International Nuclear Information System (INIS)

Franzin, V.L.M.; Hussein, M.S.

1986-07-01

With the aid of an inverse dispersion relation, which gives the imaginary part of the fusion inclusive polarization potential (IPP) in terms of the principal part integral involving the real part of the IPP, the sub-barrier fusion of heavy ions is discussed. The system 16 O+ A Sm is taken as an example. The reactive content of the extracted IPP is analysed within the coupled channels theory. (Author) [pt

Radiation and Homeostasis

International Nuclear Information System (INIS)

Sugahara, T.; Nikaido, O.; Niwa, O.

2002-01-01

These proceedings aim to promote the understanding of the health hazard of radiation at low dose range and to construct a more solid basis for radiation safety policy. Radiation hazard has been the central issue of investigation in the field of radiation research. The two major approaches are mechanistic analysis by laboratory investigation and phenomenological analysis of radiation-exposed population as represented by epidemiology. In an increasingly safety-conscious society, the extremely low level risk associated with low dose of radiation has become an important issue. In this area, the phenomenological approach has a limit. DNA damage is the primary and direct cause of the risk. Tremendous progress has been made recently in the basic understanding of radiation effects on cells and tissues and the importance of damage response rather than damage itself. This challenges the classical linear non-threshold hypothesis

Adaptive management in the context of barriers in European freshwater ecosystems

DEFF Research Database (Denmark)

Birnie-Gauvin, Kim; Tummers, Jeroen S.; Lucas, Martyn C.

2017-01-01

Many natural habitats have been modified to accommodate for the presence of humans and their needs. Infrastructures e such as hydroelectric dams, weirs, culverts and bridges e are now a common occurrence in streams and rivers across the world. As a result, freshwater ecosystems have been altered...... extensively, affecting both biological and geomorphological components of the habitats. Many fish species rely on these freshwater ecosystems to complete their lifecycles, and the presence of barriers has been shown to reduce their ability to migrate and sustain healthy populations. In the long run, barriers...... may have severe repercussions on population densities and dynamics of aquatic animal species. There is currently an urgent need to address these issues with adequate conservation approaches. Adaptive management provides a relevant approach to managing barriers in freshwater ecosystems as it addresses...

Approaches to radiation guidelines for space travel

International Nuclear Information System (INIS)

Fry, R.J.M.

1984-01-01

There are obvious risks in space travel that have loomed larger than any risk from radiation. Nevertheless, NASA has maintained a radiation program that has involved maintenance of records of radiation exposure, and planning so that the astronauts' exposures are kept as low as possible, and not just within the current guidelines. These guidelines are being reexamined currently by NCRP Committee 75 because new information is available, for example, risk estimates for radiation-induced cancer and about the effects of HZE particles. The current career limit is 400 rem to the blood forming organs. The appropriateness of this limit and its basis are being examined as well as the limits for specific organs. There is now considerably more information about age-dependency for radiation effects and this will be taken into account. In 1973 a committee of the National Research Council made a separate study of HZE particle effects and it was concluded that the attendant risks did not pose a hazard for low inclination near-earth orbit missions. Since that time work has been carried out on the so-called microlesions caused by HZE particles and on the relative carcinogenic effect of heavy ions, including iron. A remaining question is whether the fluence of HZE particles could reach levels of concern in missions under consideration. Finally, it is the intention of the committee to indicate clearly the areas requiring further research. 26 references, 1 figure, 7 tables

Investigation of aluminised steel as a barrier to tritium using accelerator-based and hydrogen permeation techniques

Energy Technology Data Exchange (ETDEWEB)

Sokhi, R S; Forcey, K S; Ross, D K; Earwaker, L G [Birmingham Univ. (UK). School of Physics and Space Research

1989-04-01

Aluminised steel has been proposed as a barrier to tritium permeation in fusion reactors. The properties of these materials as tritium barriers have been studied using accelerator-based techniques and hydrogen permeation methods. The aluminide layers has been characterised by Rutherford backscattering spectroscopy (RBS) and nuclear reaction analysis (NRA) techniques using the 3 MV Dynamitron accelerator based at the School of Physics and Space Research Radiation Centre. The effectiveness of the aluminide layer as a tritium barrier has been measured directly by a conventional permeation apparatus over a range of temperatures. The effect of high temperatures on the structure of the aluminide layer has been examined. Any correlation between the composition of the layer and its effectiveness as a tritium barrier is also discussed. (orig.).

Perception of community pharmacists towards the barriers to enhanced pharmacy services in the healthcare system of Dubai: a quantitative approach

Directory of Open Access Journals (Sweden)

Rayes IK

2015-06-01

Full Text Available Background: In many developing countries, pharmacists are facing many challenges while they try to enhance the quality of services provided to patients approaching community pharmacies. Objective: To explore perception of community pharmacists in Dubai regarding the obstacles to enhanced pharmacy services using a part of the results from a nation-wide quantitative survey. Methods: A questionnaire was distributed to 281 full-time licensed community pharmacists in Dubai. The questionnaire had 5 inter-linked sections: demographic information, information about the pharmacy, interaction with physicians, pharmacists’ current professional role, and barriers to enhanced pharmacy services. Results: About half of the respondents (45.4%, n=90 agreed that pharmacy clients under-estimate them and 52.5% (n=104 felt the same by physicians. About 47.5% (n=94 of the respondents felt that they are legally unprotected against profession’s malpractice. Moreover, 64.7% (n=128 stated that pharmacy practice in Dubai turned to be business-focused. In addition, 76.8% (n=252 found that one of the major barriers to enhanced pharmacy services is the high business running cost. Pharmacists screened tried to prove that they are not one of the barriers to optimized pharmacy services as 62.7% (n=124 disagreed that they lack appropriate knowledge needed to serve community and 67.7% (n=134 gave the same response when asked whether pharmacy staff lack confidence when treating consumers or not. Conclusions: Although being well established within the community, pharmacists in Dubai negatively perceived their own professional role. They stated that there are number of barriers which hinder optimized delivery of pharmacy services like under-estimation by pharmacy clients and other healthcare professionals, pressure to make sales, and high running cost.

Radiation dose in mammography: an energy-balance approach

International Nuclear Information System (INIS)

Shrivastava, P.N.

1981-01-01

An energy-balance approach for calculation of mean, integral, and midpoint doses in mammography is introduced. Estimation of mean absorbed dose for individual applications is described. Differences in breast composition and thickness are accounted for by simple measurements of entrance and exit exposures. Calculations made for a range of xeromammographic techniques used at various breast cancer detection centers show that although increasing the beam h.v.l. dramatically decreases breast surface exposure, it is insignificant in lowering mean breast dose or radiation risk. Thus selection of a moderate h.v.l. to optimize image quality (soft-tissue contrast) in xeromammography may be more beneficial than unduly increasing h.v.l. merely to reduce surface exposure. The mean breast dose per mammogram with low-h.v.l. screen-film techniques was 3 to 9 times lower than for xeromammography, suggesting that general acceptance of screen-film techniques can significantly reduce the risk associated with mammography

Radiation dose and intra-articular access: comparison of the lateral mortise and anterior midline approaches to fluoroscopically guided tibiotalar joint injections

Energy Technology Data Exchange (ETDEWEB)

Huang, Ambrose J.; Torriani, Martin; Bredella, Miriam A.; Chang, Connie Y.; Simeone, Frank J.; Palmer, William E. [Massachusetts General Hospital, Department of Radiology, Division of Musculoskeletal Imaging and Intervention, Boston, MA (United States); Balza, Rene [Centro Medico de Occidente, Department of Radiology, Maracaibo (Venezuela, Bolivarian Republic of)

2016-03-15

To compare the lateral mortise and anterior midline approaches to fluoroscopically guided tibiotalar joint injections with respect to successful intra-articular needle placement, fluoroscopy time, radiation dose, and dose area product (DAP). This retrospective study was IRB-approved and HIPAA-compliant. 498 fluoroscopically guided tibiotalar joint injections were performed or supervised by one of nine staff radiologists from 11/1/2010-12/31/2013. The injection approach was determined by operator preference. Images were reviewed on a PACS workstation to determine the injection approach (lateral mortise versus anterior midline) and to confirm intra-articular needle placement. Fluoroscopy time (minutes), radiation dose (mGy), and DAP (μGy-m{sup 2}) were recorded and compared using the student's t-test (fluoroscopy time) or the Wilcoxon rank sum test (radiation dose and DAP). There were 246 lateral mortise injections and 252 anterior midline injections. Two lateral mortise injections were excluded from further analysis because no contrast was administered. Intra-articular location of the needle tip was documented in 242/244 lateral mortise injections and 252/252 anterior midline injections. Mean fluoroscopy time was shorter for the lateral mortise group than the anterior midline group (0.7 ± 0.5 min versus 1.2 ± 0.8 min, P < 0.0001). Mean radiation dose and DAP were less for the lateral mortise group than the anterior midline group (2.1 ± 3.7 mGy versus 2.5 ± 3.5 mGy, P = 0.04; 11.5 ± 15.3 μGy-m{sup 2} versus 13.5 ± 17.3 μGy-m{sup 2}, P = 0.006). Both injection approaches resulted in nearly 100 % rates of intra-articular needle placement, but the lateral mortise approach used approximately 40 % less fluoroscopy time and delivered 15 % lower radiation dose and DAP to the patient. (orig.)

Large-scale fabrication of BN tunnel barriers for graphene spintronics

International Nuclear Information System (INIS)

Fu, Wangyang; Makk, Péter; Maurand, Romain; Bräuninger, Matthias; Schönenberger, Christian

2014-01-01

We have fabricated graphene spin-valve devices utilizing scalable materials made from chemical vapor deposition (CVD). Both the spin-transporting graphene and the tunnel barrier material are CVD-grown. The tunnel barrier is realized by Hexagonal boron nitride, used either as a monolayer or bilayer and placed over the graphene. Spin transport experiments were performed using ferromagnetic contacts deposited onto the barrier. We find that spin injection is still greatly suppressed in devices with a monolayer tunneling barrier due to resistance mismatch. This is, however, not the case for devices with bilayer barriers. For those devices, a spin relaxation time of ∼260 ps intrinsic to the CVD graphene material is deduced. This time scale is comparable to those reported for exfoliated graphene, suggesting that this CVD approach is promising for spintronic applications which require scalable materials

Drywall plates evaluation as protection barriers in dental X-rays and mammography facilities

International Nuclear Information System (INIS)

Guevara R, V. Y.; Romero C, N.; Berrocal T, M.

2014-08-01

In the dental X-rays and mammography facilities, usually lead shielded walls as protective barriers are used. Lead is a good attenuator for X-rays, but has toxic properties and its cost is high. Mammography equipment s emit low-energy photons in the range of 25 keV to 35 keV, on current computers; the primary radiation beam is intercepted by the image receptor. Peri apical dental equipment s emit photons in the range of 50 to 90 keV, their filtration is fixed. These devices emit a collimated beam whose diameter is slightly larger than the diagonal dimension of a standard film of dental X-rays. When a dental x-ray is performed, the radiation beam is partially attenuated by the patient. Drywall is a material consisting of plasterboard between two cardboard layers, being its components gypsum and cellulose generally. It is used in construction for execution of interior walls, ceilings and wall coverings, could also serve as a replacement for lead as well as other materials. In this paper three drywall prototypes (Giplac), formed with 02, 04 and 06 drywall layers (13, 16 and 20 cm of thickness respectively) were tested as barriers against primary and secondary X-ray radiation that come from dental and mammography equipment s. The results show that the drywall prototype, 02 layers, efficiently attenuates the secondary radiation beam produced by conventional mammography equipment. And the prototype 04 and 06 layers, efficiently attenuates the primary radiation beam produced by peri apical dental equipment. (author)

New approach to determine the radiative width of the Hoyle state

International Nuclear Information System (INIS)

Kibedi, T.; Stuchbery, A. E.; Dracoulis, G. D.; Devlin, A.; Teh, A.; Robertson, K.

2009-01-01

The triple alpha process leading to the formation of stable carbon in the Universe is one of the most important nuclear astrophysical processes. The radiative width of the so called Hoyle-state, involving the 7.654 MeV E0 and the 3.215 MeV E2 transitions, is known with 10% accuracy. A novel, more direct approach is proposed here, based on the measurement of the E0 and the E2 internal pair conversion intensities. We report on the development of a new type of magnetic pair spectrometer with high sensitivity for electron-positron pairs and with excellent energy resolution.

Powerful highly efficient KrF lamps excited by surface and barrier discharges

International Nuclear Information System (INIS)

Borisov, V M; Vodchits, V A; El'tsov, A V; Khristoforov, O B

1998-01-01

An investigation was made of the characteristics of KrF lamps with different types of excitation by surface and barrier discharges in which the dielectric material was sapphire. The conditions were determined for the attainment of an extremely high yield of the KrF* fluorescence with the internal efficiency η in ∼30 % and 22% for pulsed surface and barrier discharges, respectively. A homogeneous surface discharge was maintained without gas circulation when the pulse repetition rate was 5 x 10 4 Hz. Quasicontinuous excitation of a surface discharge at near-atmospheric pressure made it possible to reach a KrF* fluorescence power density of about 80 W cm -3 , which was close to the limit set by the kinetics of the gaseous medium. Under prolonged excitation conditions the intensity of the UV output radiation was limited by the permissible heating of the gas to a temperature above which the operating life of the gaseous mixture containing fluorine fell steeply. This was the reason for the advantage of surface over barrier discharges: the former were characterised by a high thermal conductivity of a thin (∼0.2 mm) plasma layer on the surface of the cooled dielectric, which made it possible to construct powerful highly efficient KrF and ArF lamps emitting UV radiation of up to 1 W cm -2 intensity. (laser system components)

Barriers to innovation in service SMEs: Evidence from Mexico

OpenAIRE

Maldonado Guzman, G.; Garza-Reyes, J. A.; Pinzón-Castro, S. Y.; Kumar, V.

2017-01-01

Purpose – Specific research related to the study of innovation barriers in service SMEs in the Latin American region is limited. This study thus investigates the effects that external environmental, financial and human barriers have on innovation activities, particularly, within the context of Mexican service SMEs.\\ud \\ud Design/methodology/approach – Three hypotheses were formulated and tested using structural equation modelling (SEM). Data were collected through an instrument that was devel...

Many-nucleon transfer reactions at the coulomb barrier

International Nuclear Information System (INIS)

Wegmann, H.

1974-01-01

The aim of the present work was to investigate the many-nucleon transfer with heavy ion radiation near the coulomb barrier. The neutron-rich targets 76 Ge, sup(92,94,96)Zr and 100 Mo were thus irradiated with 32 S and 34 S radiation. By measuring the activity of the back-scattered light reaction products in the transfer, total cross sections were determined for the 3p, 4p, 3pn, 4pn, 3n, 4n and 6n transfer. Excitation functions for the 3p, 4p, 3pn and 4pn transfer were measured for the target-projectile combination 96 Zr- 32 S. Differential cross sections could be determined with 96 Zr and 100 Mo. The results were compared with various theoretical calculations. (orig./LH) [de

The temperature in Hawking radiation as tunneling

International Nuclear Information System (INIS)

Zhang Baocheng; Cai Qingyu; Zhan Mingsheng

2009-01-01

The quasi-classical method of deriving Hawking radiation under the consideration of canonical invariance is investigated. We find that the horizon should be regarded as a two-way barrier and the ingoing amplitude should be calculated according to the negative energy particles tunneling into the black hole because of the whole space-time interchange and thus the standard Hawking temperature is recovered. We also discuss the advantage of the Painleve coordinates in Hawking radiation as tunneling

Pion Production from Proton Synchrotron Radiation under Strong Magnetic Field in a Relativistic Quantum Approach

Directory of Open Access Journals (Sweden)

Maruyama Tomoyuki

2016-01-01

Full Text Available We study pion production from proton synchrotron radiation in the presence of strong magnetic fields by using the exact proton propagator in a strong magnetic field and explicitly including the anomalous magnetic moment. Results in this exact quantum approach do not agree with those obtained in the semi-classical approach. Then, we find that the anomalous magnetic moment of the proton greatly enhances the production rate by about two orders magnitude, and that the decay width satisfies a robust scaling law.

Finite-time barriers to front propagation in two-dimensional fluid flows

Science.gov (United States)

Mahoney, John R.; Mitchell, Kevin A.

2015-08-01

Recent theoretical and experimental investigations have demonstrated the role of certain invariant manifolds, termed burning invariant manifolds (BIMs), as one-way dynamical barriers to reaction fronts propagating within a flowing fluid. These barriers form one-dimensional curves in a two-dimensional fluid flow. In prior studies, the fluid velocity field was required to be either time-independent or time-periodic. In the present study, we develop an approach to identify prominent one-way barriers based only on fluid velocity data over a finite time interval, which may have arbitrary time-dependence. We call such a barrier a burning Lagrangian coherent structure (bLCS) in analogy to Lagrangian coherent structures (LCSs) commonly used in passive advection. Our approach is based on the variational formulation of LCSs using curves of stationary "Lagrangian shear," introduced by Farazmand et al. [Physica D 278-279, 44 (2014)] in the context of passive advection. We numerically validate our technique by demonstrating that the bLCS closely tracks the BIM for a time-independent, double-vortex channel flow with an opposing "wind."

Effect of ionising radiation exposure on structure and permeability of epithelial junctions in rat ileum

International Nuclear Information System (INIS)

Lebrum, F.; Dublineau, I.; Grison, S.; Strup, C.; Griffiths, N.M.

2002-01-01

Exposure of the digestive tract to ionising radiation results in both morphological and functional alterations of the small intestine. However little is known about the effect of irradiation on the junctions playing a major role in the maintenance of epithelial barrier integrity. Thus the aim of this study was to investigate, in rat ileum, the effect of radiation exposure on the permeability of the epithelial barrier in parallel with the localization of certain inter- and intra-cellular proteins of tight and adherent junctions

Impact of imaging approach on radiation dose and associated cancer risk in children undergoing cardiac catheterization.

Science.gov (United States)

Hill, Kevin D; Wang, Chu; Einstein, Andrew J; Januzis, Natalie; Nguyen, Giao; Li, Jennifer S; Fleming, Gregory A; Yoshizumi, Terry K

2017-04-01

To quantify the impact of image optimization on absorbed radiation dose and associated risk in children undergoing cardiac catheterization. Various imaging and fluoroscopy system technical parameters including camera magnification, source-to-image distance, collimation, antiscatter grids, beam quality, and pulse rates, all affect radiation dose but have not been well studied in younger children. We used anthropomorphic phantoms (ages: newborn and 5 years old) to measure surface radiation exposure from various imaging approaches and estimated absorbed organ doses and effective doses (ED) using Monte Carlo simulations. Models developed in the National Academies' Biological Effects of Ionizing Radiation VII report were used to compare an imaging protocol optimized for dose reduction versus suboptimal imaging (+20 cm source-to-image-distance, +1 magnification setting, no collimation) on lifetime attributable risk (LAR) of cancer. For the newborn and 5-year-old phantoms, respectively ED changes were as follows: +157% and +232% for an increase from 6-inch to 10-inch camera magnification; +61% and +59% for a 20 cm increase in source-to-image-distance; -42% and -48% with addition of 1-inch periphery collimation; -31% and -46% with removal of the antiscatter grid. Compared with an optimized protocol, suboptimal imaging increased ED by 2.75-fold (newborn) and fourfold (5 years old). Estimated cancer LAR from 30-min of posteroanterior fluoroscopy using optimized versus suboptimal imaging, respectively was 0.42% versus 1.23% (newborn female), 0.20% versus 0.53% (newborn male), 0.47% versus 1.70% (5-year-old female) and 0.16% versus 0.69% (5-year-old male). Radiation-related risks to children undergoing cardiac catheterization can be substantial but are markedly reduced with an optimized imaging approach. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Optimal systematics of single-humped fission barriers for statistical calculations

International Nuclear Information System (INIS)

Mashnik, S.G.

1993-01-01

A systematic comparison of the existing phenomenological approaches and models for describing single-humped fast-computing fission barriers are given. The experimental data on excitation energy dependence of the fissility of compound nuclei are analyzed in the framework of the statistical approach by using different models for fission barriers, shell and pairing corrections and level-density parameter in order to identify their reliability and region of applicability for Monte Carlo calculations of evaporative cascades. The energy dependence of fission cross-sections for reactions induced by intermediate energy protons has been analyzed in the framework of the cascade-exiton model. 53 refs., 15 figs., 3 tabs

Comparison of Electron Transmittance and Tunneling Current through a Trapezoidal Potential Barrier with Spin Polarization Consideration by using Analytical and Numerical Approaches

Science.gov (United States)

Nabila, Ezra; Noor, Fatimah A.; Khairurrijal

2017-07-01

In this study, we report an analytical calculation of electron transmittance and polarized tunneling current in a single barrier heterostructure of a metal-GaSb-metal by considering the Dresselhaus spin orbit effect. Exponential function, WKB method and Airy function were used in calculating the electron transmittance and tunneling current. A Transfer Matrix Method, as a numerical method, was utilized as the benchmark to evaluate the analytical calculation. It was found that the transmittances calculated under exponential function and Airy function is the same as that calculated under TMM method at low electron energy. However, at high electron energy only the transmittance calculated under Airy function approach is the same as that calculated under TMM method. It was also shown that the transmittances both of spin-up and spin-down conditions increase as the electron energy increases for low energies. Furthermore, the tunneling current decreases with increasing the barrier width.

Safety-barrier diagrams as a tool for modelling safety of hydrogen applications

DEFF Research Database (Denmark)

Duijm, Nijs Jan; Markert, Frank

2009-01-01

Safety-barrier diagrams have proven to be a useful tool in documenting the safety measures taken to prevent incidents and accidents in process industry. Especially during the introduction of new hydrogen technologies or applications, as e.g. hydrogen refuelling stations, safety-barrier diagrams...... are considered a valuable supplement to other traditional risk analysis tools to support the communication with authorities and other stakeholders during the permitting process. Another advantage of safety-barrier diagrams is that they highlight the importance of functional and reliable safety barriers in any...... system and here is a direct focus on those barriers that need to be subject to safety management in terms of design and installation, operational use, inspection and monitoring, and maintenance. Safety-barrier diagrams support both quantitative and qualitative approaches. The paper will describe...

Radiation processing of polyethylene and polymethylmethacrylate for construction industry and architecture

International Nuclear Information System (INIS)

Knizhnik, E.I.; Gordienko, V.P.; Il'yenko, R.E.; Onisko, A.D.; AN Ukrainskoj SSR, Kiev. Inst. Fizicheskoj Khimii)

1983-01-01

Radiation processing of relief-forming molds made of filled high-density polyethylene enables them to be used for shaping concrete and ferroconcrete barrier constructions of buildings; radiation processing of polymethylmethacrylate in unit form makes it possible to produce large-size decorative elements of building interior. The subject is discussed and examples presented. (author)

Modeling solar radiation of Mediterranean region in Turkey by using fuzzy genetic approach

International Nuclear Information System (INIS)

Kisi, Ozgur

2014-01-01

The study investigates the ability of FG (fuzzy genetic) approach in modeling solar radiation of seven cities from Mediterranean region of Anatolia, Turkey. Latitude, longitude, altitude and month of the year data from the Adana, K. Maras, Mersin, Antalya, Isparta, Burdur and Antakya cities are used as inputs to the FG model to estimate one month ahead solar radiation. FG model is compared with ANNs (artificial neural networks) and ANFIS (adaptive neruro fuzzzy inference system) models with respect to RMSE (root mean square errors), MAE (mean absolute errors) and determination coefficient (R 2 ) statistics. Comparison results indicate that the FG model performs better than the ANN and ANFIS models. It is found that the FG model can be successfully used for estimating solar radiation by using latitude, longitude, altitude and month of the year information. FG model with RMSE = 6.29 MJ/m 2 , MAE = 4.69 MJ/m 2 and R 2 = 0.905 in the test stage was found to be superior to the optimal ANN model with RMSE = 7.17 MJ/m 2 , MAE = 5.29 MJ/m 2 and R 2 = 0.876 and ANFIS model with RMSE = 6.75 MJ/m 2 , MAE = 5.10 MJ/m 2 and R 2 = 0.892 in estimating solar radiation. - Highlights: • SR (Solar radiation) of seven cities from Mediterranean region of Turkey is predicted. • FG (Fuzzy genetic) models are developed for accurately estimation of SR. • The ability of the FG models used in the study is found to be satisfactory. • FG models are compared with commonly used ANNs (artificial neural networks). • FG models are found to perform better than the ANNs models

Scaffolding proteins in the development and maintenance of the epidermal permeability barrier.

Science.gov (United States)

Crawford, Melissa; Dagnino, Lina

2017-10-02

The skin of mammals and other terrestrial vertebrates protects the organism against the external environment, preventing heat, water and electrolyte loss, as well as entry of chemicals and pathogens. Impairments in the epidermal permeability barrier function are associated with the genesis and/or progression of a variety of pathological conditions, including genetic inflammatory diseases, microbial and viral infections, and photodamage induced by UV radiation. In mammals, the outside-in epidermal permeability barrier is provided by the joint action of the outermost cornified layer, together with assembled tight junctions in granular keratinocytes found in the layers underneath. Tight junctions serve as both outside-in and inside-out barriers, and impede paracellular movements of ions, water, macromolecules and microorganisms. At the molecular level, tight junctions consist of integral membrane proteins that form an extracellular seal between adjacent cells, and associate with cytoplasmic scaffold proteins that serve as links with the actin cytoskeleton. In this review, we address the roles that scaffold proteins play specifically in the establishment and maintenance of the epidermal permeability barrier, and how various pathologies alter or impair their functions.

Influence of intestinal early enteral nutrition therapy on intestinal barrier function and immune response of patients with radiation enteritis

International Nuclear Information System (INIS)

Liu Guohui; Kang Xin; Chen Gong; Wang Guangyi

2012-01-01

Objective: To investigate the influence of early enteral nutrition therapy on the intestinal barrier function and immune response of the patients with radiation enteritis (ER) so as to find a relatively simple and effective method to treat RE. Methods: Fifty-six patients with radiation enteritis (RE) diagnosed by colonoscopy, X-rays, and pathology were randomly divided into 2 equal groups: experimental group undergoing enteral nutrition therapy, and control group undergoing conventional therapy only. Peripheral blood samples were collected 1, 11, and 21 days after admission. Plasma diamine oxidase (DAO), D-lactic acid, endotoxin, and lactulose/mannitol (L/M) ratio, and levels of IgG, IgM, and IgA, and CD4/CD8 ratio were examined. Five cases from the experimental group and 5 cases from the control group underwent second-time operation because of incomplete intestinal obstruction, intestinal stenosis, or recurrent tumor respectively. The biopsy specimens of the terminal ileum or distal descending colon taken during the first and second operations underwent pathological examination. Peripheral blood samples were collected 1, 11, and 21 days after admission. Plasma diamine oxidase (DAO), D-lactic acid, endotoxin, and lactulose/mannitol (L/M) ratio, and levels of IgG, IgM, and IgA, and CD4/CD8 ratio were examined. Results: There were no significant differences in the intestinal function and blood immunological indices between these 2 groups. The levels of DAO, D-lactic acid, and endotoxin,and the L/M ratio 11 days after admission of the experiment group were all significantly lower than those of the control group (t=2.568, 2.427, 2.143, 2.443, P<0.05), and all those indices 21 days after admission of the experiment group were all much more significantly lower in comparison with the control group (t=6.019, 12.834, 7.837, 7.997, P<0.01). The levels of IgG, IgM, and IgA, and CD4/CD8 ratio 11 days after admission of the experimental group were all significantly higher than

Pathogenesis of acute radiation effects in the urinary bladder. Experimental results

International Nuclear Information System (INIS)

Doerr, W.; Eckhardt, M.; Ehme, A.; Koi, S.

1998-01-01

Purpose: The present review summarizes experimental studies of the pathogenesis of acute radiation-induced changes in urinary bladder function. Material and methods: Transurethral cystometry was used for longitudinal assessment of bladder function in mice. With this technique, radiation-induced changes in storage capacity can be quantified. In histological studies, changes in urothelial cell density and in urothelial protein expression during the acute radiation response were determined. Acetylsalicylic acid (ASA) was used for the treatment of acute functional changes. Results: The histological studies did not reveal any systematic fluctuations in urothelial cell density during the time of the acute radiation response. However, characteristic changes in the expression of proteins associated with urothelial cell function, differentiation and cell contact were observed, which correlated with the functional impairment. By local or systemical application of ASA, a significant restoration of bladder function compared to placebo treatment could be achieved. Conclusion: Acute functional radiation effects in the urinary bladder are not based on urothelial denudation. However, changes in protein expression indicate an impairment of the urothelial barrier function. The results of ASA treatment demonstrate that prostaglandins are involved in the response. Alterations in urothelial or endothelial prostaglandin metabolism may be primarily radiation-induced or secondary because of the impaired urothelial barrier. (orig.) [de

Smart parking barrier

KAUST Repository

Alharbi, Abdulrazaq M.

2016-05-06

Various methods and systems are provided for smart parking barriers. In one example, among others, a smart parking barrier system includes a movable parking barrier located at one end of a parking space, a barrier drive configured to control positioning of the movable parking barrier, and a parking controller configured to initiate movement of the parking barrier, via the barrier drive. The movable parking barrier can be positioned between a first position that restricts access to the parking space and a second position that allows access to the parking space. The parking controller can initiate movement of the movable parking barrier in response to a positive identification of an individual allowed to use the parking space. The parking controller can identify the individual through, e.g., a RFID tag, a mobile device (e.g., a remote control, smartphone, tablet, etc.), an access card, biometric information, or other appropriate identifier.

Adaptive radiation versus 'radiation' and 'explosive diversification': why conceptual distinctions are fundamental to understanding evolution.

Science.gov (United States)

Givnish, Thomas J

2015-07-01

Adaptive radiation is the rise of a diversity of ecological roles and role-specific adaptations within a lineage. Recently, some researchers have begun to use 'adaptive radiation' or 'radiation' as synonymous with 'explosive species diversification'. This essay aims to clarify distinctions between these concepts, and the related ideas of geographic speciation, sexual selection, key innovations, key landscapes and ecological keys. Several examples are given to demonstrate that adaptive radiation and explosive diversification are not the same phenomenon, and that focusing on explosive diversification and the analysis of phylogenetic topology ignores much of the rich biology associated with adaptive radiation, and risks generating confusion about the nature of the evolutionary forces driving species diversification. Some 'radiations' involve bursts of geographic speciation or sexual selection, rather than adaptive diversification; some adaptive radiations have little or no effect on speciation, or even a negative effect. Many classic examples of 'adaptive radiation' appear to involve effects driven partly by geographic speciation, species' dispersal abilities, and the nature of extrinsic dispersal barriers; partly by sexual selection; and partly by adaptive radiation in the classical sense, including the origin of traits and invasion of adaptive zones that result in decreased diversification rates but add to overall diversity. © 2015 The Author. New Phytologist © 2015 New Phytologist Trust.

A Voxel-Based Approach to Explore Local Dose Differences Associated With Radiation-Induced Lung Damage

Energy Technology Data Exchange (ETDEWEB)

Palma, Giuseppe [Institute of Biostructure and Bioimaging, National Research Council, Naples (Italy); Monti, Serena [IRCCS SDN, Naples (Italy); D' Avino, Vittoria [Institute of Biostructure and Bioimaging, National Research Council, Naples (Italy); Conson, Manuel [Institute of Biostructure and Bioimaging, National Research Council, Naples (Italy); Department of Advanced Biomedical Sciences, Federico II University School of Medicine, Naples (Italy); Liuzzi, Raffaele [Institute of Biostructure and Bioimaging, National Research Council, Naples (Italy); Pressello, Maria Cristina [Department of Health Physics, S. Camillo-Forlanini Hospital, Rome (Italy); Donato, Vittorio [Department of Radiation Oncology, S. Camillo-Forlanini Hospital, Rome (Italy); Deasy, Joseph O. [Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY (United States); Quarantelli, Mario [Institute of Biostructure and Bioimaging, National Research Council, Naples (Italy); Pacelli, Roberto [Institute of Biostructure and Bioimaging, National Research Council, Naples (Italy); Department of Advanced Biomedical Sciences, Federico II University School of Medicine, Naples (Italy); Cella, Laura, E-mail: laura.cella@cnr.it [Institute of Biostructure and Bioimaging, National Research Council, Naples (Italy)

2016-09-01

Purpose: To apply a voxel-based (VB) approach aimed at exploring local dose differences associated with late radiation-induced lung damage (RILD). Methods and Materials: An interinstitutional database of 98 patients who were Hodgkin lymphoma (HL) survivors treated with postchemotherapy supradiaphragmatic radiation therapy was analyzed in the study. Eighteen patients experienced late RILD, classified according to the Radiation Therapy Oncology Group scoring system. Each patient's computed tomographic (CT) scan was normalized to a single reference case anatomy (common coordinate system, CCS) through a log-diffeomorphic approach. The obtained deformation fields were used to map the dose of each patient into the CCS. The coregistration robustness and the dose mapping accuracy were evaluated by geometric and dose scores. Two different statistical mapping schemes for nonparametric multiple permutation inference on dose maps were applied, and the corresponding P<.05 significance lung subregions were generated. A receiver operating characteristic (ROC)-based test was performed on the mean dose extracted from each subregion. Results: The coregistration process resulted in a geometrically robust and accurate dose warping. A significantly higher dose was consistently delivered to RILD patients in voxel clusters near the peripheral medial-basal portion of the lungs. The area under the ROC curves (AUC) from the mean dose of the voxel clusters was higher than the corresponding AUC derived from the total lung mean dose. Conclusions: We implemented a framework including a robust registration process and a VB approach accounting for the multiple comparison problem in dose-response modeling, and applied it to a cohort of HL survivors to explore a local dose–RILD relationship in the lungs. Patients with RILD received a significantly greater dose in parenchymal regions where low doses (∼6 Gy) were delivered. Interestingly, the relation between differences in the high

Recent experimental studies of edge and internal transport barriers in the DIII-D tokamak

International Nuclear Information System (INIS)

Gohil, P; Baylor, L R; Burrell, K H; Casper, T A; Doyle, E J; Greenfield, C M; Jernigan, T C; Kinsey, J E; Lasnier, C J; Moyer, R A; Murakami, M; Rhodes, T L; Rudakov, D L; Staebler, G M; Wang, G; Watkins, J G; West, W P; Zeng, L

2003-01-01

Results from recent experiments on the DIII-D tokamak have revealed many important details on transport barriers at the plasma edge and in the plasma core. These experiments include: (a) the formation of the H-mode edge barrier directly by pellet injection; (b) the formation of a quiescent H-mode edge barrier (QH-mode) which is free from edge localized modes, but which still exhibits good density and radiative power control; (c) the formation of multiple transport barriers, such as the quiescent double barrier (QDB) which combines an internal transport barrier with the quiescent H-mode edge barrier. Results from the pellet-induced H-mode experiments indicate that: (a) the edge temperature (electron or ion) does not need to attain a critical value for the formation of the H-mode barrier, (b) pellet injection leads to an increased gradient in the radial electric field, E r , at the plasma edge; (c) the experimentally determined edge parameters at barrier transition are well below the predictions of several theories on the formation of the H-mode barrier, (d) pellet injection can lower the threshold power required to form the H-mode barrier. The quiescent H-mode barrier exhibits good density control as the result of continuous magnetohydrodynamic activity at the plasma edge called the edge harmonic oscillation (EHO). The EHO enhances the edge particle transport whilst maintaining a good energy transport barrier. The ability to produce multiple barriers in the QDB regime has led to long duration, high-performance plasmas with β N H 89 values of 7 for up to 10 times the confinement time. Density profile control in the plasma core of QDB plasmas has been demonstrated using on-axis electron cyclotron heating

Nucleus-size pinning for determination of nucleation free-energy barriers and nucleus geometry

Science.gov (United States)

Sharma, Abhishek K.; Escobedo, Fernando A.

2018-05-01

Classical Nucleation Theory (CNT) has recently been used in conjunction with a seeding approach to simulate nucleation phenomena at small-to-moderate supersaturation conditions when large free-energy barriers ensue. In this study, the conventional seeding approach [J. R. Espinosa et al., J. Chem. Phys. 144, 034501 (2016)] is improved by a novel, more robust method to estimate nucleation barriers. Inspired by the interfacial pinning approach [U. R. Pedersen, J. Chem. Phys. 139, 104102 (2013)] used before to determine conditions where two phases coexist, the seed of the incipient phase is pinned to a preselected size to iteratively drive the system toward the conditions where the seed becomes a critical nucleus. The proposed technique is first validated by estimating the critical nucleation conditions for the disorder-to-order transition in hard spheres and then applied to simulate and characterize the highly non-trivial (prolate) morphology of the critical crystal nucleus in hard gyrobifastigia. A generalization of CNT is used to account for nucleus asphericity and predict nucleation free-energy barriers for gyrobifastigia. These predictions of nuclei shape and barriers are validated by independent umbrella sampling calculations.

Chaotic correlations in barrier billiards with arbitrary barriers

International Nuclear Information System (INIS)

Osbaldestin, A H; Adamson, L N C

2013-01-01

We study autocorrelation functions in symmetric barrier billiards for golden mean trajectories with arbitrary barriers. Renormalization analysis reveals the presence of a chaotic invariant set and thus that, for a typical barrier, there are chaotic correlations. The chaotic renormalization set is the analogue of the so-called orchid that arises in a generalized Harper equation. (paper)

Barriers and Promoters to Participation in the Era of Shared Treatment Decision-Making.

Science.gov (United States)

McCarter, Sarah P; Tariman, Joseph D; Spawn, Nadia; Mehmeti, Enisa; Bishop-Royse, Jessica; Garcia, Ima; Hartle, Lisa; Szubski, Katharine

2016-10-01

This study aimed to identify the barriers and promoters for participation in cancer treatment decision in the era of shared decision-making (SDM) process. A qualitative design was utilized. Nineteen nurses and 11 nurse practitioners from oncology inpatient and outpatient settings participated in semi-structured interviews. Data were analyzed using directed content analysis. The findings include practice barrier, patient barrier, institutional policy barrier, professional barrier, scope of practice barrier, insurance coverage barrier, and administrative barrier. Multidisciplinary team approach, having a nursing voice during SDM, high level of knowledge of the disease and treatment, and personal valuation of SDM participation were perceived as promoters. Oncology nurses and nurse practitioners face many barriers to their participation during SDM. Organizational support and system-wide culture of SDM are essential to achieve better cancer treatment decisions outcome. Additional studies are needed to determine the factors that can promote more participation among nurses and nurse practitioners. © The Author(s) 2016.

Radiation safety infrastructure in developing countries: a proactive approach for integrated and continuous improvement

International Nuclear Information System (INIS)

Mrabit, Khammar

2008-01-01

The International Atomic Energy Agency (the Agency) is authorized, by its statute, to establish or adopt safety standards for the protection of health and minimization of danger to life and property, and to provide for their application to its own operations as well as to operations under its control or supervision. The Agency has been assisting, since the mid 1960 's, its Member States through mainly its Technical Cooperation Programme (TCP) to improve their national radiation safety infrastructures. However up to the early nineties, assistance was specific and mostly ad hoc and did not systematically utilize an integrated and harmonized approach to achieving effective and sustainable national radiation safety infrastructures in Member States. An unprecedented and integrated international cooperative effort was launched by the Agency in 1994 to establish and/or upgrade the national radiation safety infrastructure in more than 90 countries within the framework of its TCP through the so-called Model project on upgrading radiation protection infrastructure. In this project proactive co-operation with Member States was used in striving towards achieving an effective and sustainable radiation safety infrastructure, compatible with the International basic safety standards for protection against ionizing radiation and for the safety of radiation sources (the BSS) and related standards. Extension to include compatibility with the guidance of the Code of Conduct on the Safety and Security of Radioactive Sources occurred towards the end of the Model Project in December 2004, and with the more recent ensuing follow up projects that started in 2005. The Model Project started with 5 countries in 1994 and finished with 91 countries in 2004. Up to the end of 2007 more than one hundred Member States had been participating in follow up projects covering six themes - namely: legislative and regulatory infrastructure; occupational radiation protection; radiation protection in

Knowledge Exchange and Management Research: Barriers and Potentials

DEFF Research Database (Denmark)

Bager, Torben

2018-01-01

Purpose: The growing involvement of management researchers in knowledge exchange activities and collaborative research does not seem to be reflected in a growing academic output. The purpose of this paper is to explore barriers for academic output from these activities as well as the potential...... for ‘interesting’ papers. Design/methodology/approach: The paper uses secondary data and statistics as well as an illustrative case study to trace knowledge exchange activities and barriers for academic output based on these activities. Findings: The paper identifies a number of barriers for the turning of data...... derived from knowledge exchange activities and Mode 2 research into academic papers such as low priority of case study research in leading management journals, a growing practice orientation in the research funding systems, methodological challenges due to limited researcher control, and disincentives...

Trench Safety–Using a Qualitative Approach to Understand Barriers and Develop Strategies to Improve Trenching Practices

Science.gov (United States)

FLYNN, MICHAEL A.; SAMPSON, JULIE M.

2015-01-01

Despite efforts to ensure workplace safety and health, injuries and fatalities related to trenching and excavation remain alarmingly high in the construction industry. Because properly installed trenching protective systems can potentially reduce the significant number of trenching fatalities, there is clearly a need to identify the barriers to the use of these systems and to develop strategies to ensure these systems are utilized consistently. The current study reports on the results of focus groups with construction workers and safety management personnel to better understand these barriers and to identify solutions. The results suggest several factors, from poor planning to pressures from experienced workers and supervisors, which present barriers to safe trenching practices. Based on the results, it is recommended that safety trainings incorporate unique messages for new workers, experienced workers and management in an effort to motivate each group to work safely as well as provide them with solutions to overcome the identified barriers. PMID:26550006

New approach to high energy SU/sub 2L/ /times/ U1 radiative corrections

International Nuclear Information System (INIS)

Ward, B.F.L.

1988-07-01

We present a new approach to SU/sub 2L/ /times/ U 1 radiative corrections at high energies. Our approach is based on the infrared summation methods of Yennie, Frautschi and Suura, taken together with the Weinberg-'t Hooft renormalization group equation. Specific processes which have been realized via explicit Monte Carlo algorithms are e + e/sup /minus// → f/bar f/' + n(γ), f = μ, /tau/, d, s, u, c, b or t and e + e/sup /minus// → e + e/sup /minus// + n(γ), where n(γ), denotes multiple photo emission on an event-by-event basis. Exemplary Monte Carlo data are presented. 16 refs., 4 figs

Long-term climate change assessment study plan for the Hanford Site permanent isolation Barrier Development Program

International Nuclear Information System (INIS)

Petersen, K.L.; Chatters, J.C.; Waugh, W.J.

1992-07-01

The Hanford Site Permanent Isolation Barrier Development Program (Barrier Development Program) was organized to develop the technology needed to provide an in-place disposal capability for the Hanford Site (Adams and Wing 1986; Wig and Gee 1990). The goal of the Barrier Development Program is to provide defensible evidence that final barrier design(s) will adequately control water infiltration; plant and animal intrusion; and wind and water erosion for a minimum of 1,000 yr and isolate wastes from the accessible environment and warm inadvertent human intruders using markers. This document describes the long-term climate change studies planned to support the Barrier Development Program. The plan outlines a multi-year and multi-discipline approach to assess long-term climate change issues and to help optimize the design of the permanent isolation barriers. A multi-disciplinary approach to climatic data acquisition will be responsible for obtaining needed information for concurrent barrier tasks and for developing a local climate forecast model. This model will couple past climate patterns with models of regional and global climate drivers to provide bounding conditions for barrier performance assessment analyses

A theoretical study of cold nuclear fusion using barrier penetration approach

International Nuclear Information System (INIS)

Gupta, S.K.; Gupta, R.K.

1989-06-01

The cold nuclear fusion process is investigated in terms of barrier penetration calculations by considering both the deuteron-molecule and colliding deuteron-deuteron atoms. Atomic collisions with strongly screened interatomic potential and the resonant state formation can bring agreement with present experimental results. Analysis of the data in terms of the reaction rates is also discussed. (author). 13 refs, 1 tab

Roentgen's heritage and radiation phobia, a challenge to radiation research and radiation protection

International Nuclear Information System (INIS)

Feinendegen, L.E.

1996-01-01

Present practice of applying linearity to assessing risk even from very low dose exposure of complex tissues to ionising radiation has been evaluated in terms of microdosimetric approach to energy deposition in tissues, nature of radiation and also the magnitudes of conditioning and challenging doses. This paper discusses the probability of radiation risk at quite low doses on the tissues in terms of simple mathematical terms. (author). 13 refs., 2 figs., 1 tab

Anatomy of an adaptive radiation: Blepharoneura fruit flies

Science.gov (United States)

Insect herbivores have often been linked to the ecological theory of adaptive radiation, which postulates that divergent selection on phenotypes in different habitats or environments results in the evolution of reproductive barriers between populations and subsequent speciation. An expected result o...

Impedance-based cell monitoring: barrier properties and beyond

Directory of Open Access Journals (Sweden)

Benson Kathrin

2013-01-01

for barrier forming cells. Another impedance-based approach requires cells to be grown directly on solid, micro-structured electrodes. Here, we will discuss the physical background of the different techniques; advantages, disadvantages, and applications will be scrutinized. The aim is to give the reader a comprehensive understanding concerning the range and limits of the application, mainly focusing on endothelial cells.

The blood-brain barrier: structure, function and therapeutic approaches to cross it.

Science.gov (United States)

Tajes, Marta; Ramos-Fernández, Eva; Weng-Jiang, Xian; Bosch-Morató, Mònica; Guivernau, Biuse; Eraso-Pichot, Abel; Salvador, Bertrán; Fernàndez-Busquets, Xavier; Roquer, Jaume; Muñoz, Francisco J

2014-08-01

The blood-brain barrier (BBB) is constituted by a specialized vascular endothelium that interacts directly with astrocytes, neurons and pericytes. It protects the brain from the molecules of the systemic circulation but it has to be overcome for the proper treatment of brain cancer, psychiatric disorders or neurodegenerative diseases, which are dramatically increasing as the population ages. In the present work we have revised the current knowledge on the cellular structure of the BBB and the different procedures utilized currently and those proposed to cross it. Chemical modifications of the drugs, such as increasing their lipophilicity, turn them more prone to be internalized in the brain. Other mechanisms are the use of molecular tools to bind the drugs such as small immunoglobulins, liposomes or nanoparticles that will act as Trojan Horses favoring the drug delivery in brain. This fusion of the classical pharmacology with nanotechnology has opened a wide field to many different approaches with promising results to hypothesize that BBB will not be a major problem for the new generation of neuroactive drugs. The present review provides an overview of all state-of-the-art of the BBB structure and function, as well as of the classic strategies and these appeared in recent years to deliver drugs into the brain for the treatment of Central Nervous System (CNS) diseases.

A conversion method of air-kerma from the primary, scatter and leakage radiations to ambient dose equivalent for calculating the mamography x-ray shielding barrier

International Nuclear Information System (INIS)

Kharrati, H.

2005-01-01

The primary, scatter, and leakage doses(in Gy), which constitute the data base for calculating shielding requirements for x-ray facilities, are often converted to the equivalent dose (in sievert) by using a constant of conversion of 1.145Sv/Gy. This constant is used for diagnostic radiology as well as for mammography spectra, and is derived by considering an exposure of 1 R corresponds to an air kerma of 8.73 m Gy, which renders by tradition an equivalent dose of 10 mSv. However, this conversion does not take into account the energy dependence of the conversion coefficients relating air kerma to the equivalent dose as described in ICRU report. Moreover, current radiation protection standards propose the use of the quantity ambient dose equivalent in order to qualify the efficiently of given radiation shielding. Therefore, in this study, a new approach has been introduced for derivation ambient dose equivalent from air kerma to calculate shielding requirements in mammography facilities. This new approach has been used to compute the conversion coefficients relating air kerma to ambient dose equivalent for mammography reference beam series of the Netherlands Metrology Institute Van Swinden Laboratorium (NMi), National Institute of Standards and Technology (NIST), and International Atomic Energy Agency (AIEA) laboratories. The calculation has been performed by the means of two methods which show a maximum deviation less than 10%2 for the primary, scatter, and leakage radiations. The results show that the conversion coefficients vary from 0.242 Sv/ Gy to 0.692 Sv/Gy with an average value of 0.436 Sv/Gy for the primary and the scatter radiations, and form 0.156 Sv/Gy to 1.329 Sv/Gy with an average value of 0.98 Sv/Gy for the leakage radiation. Simpkin et al. using an empirical approach propose a conversion value of 0.50 Sv/Gy for the mammography x-ray spectra. This value approximately coincides with the average conversion value of 0.436 Sv/Gy obtained in this work for

Smart parking barrier

KAUST Repository

Alharbi, Abdulrazaq M.

2016-01-01

positioning of the movable parking barrier, and a parking controller configured to initiate movement of the parking barrier, via the barrier drive. The movable parking barrier can be positioned between a first position that restricts access to the parking

Applications of Skyrme energy-density functional to fusion reactions spanning the fusion barriers

International Nuclear Information System (INIS)

Liu Min; Wang, Ning; Li Zhuxia; Wu Xizhen; Zhao Enguang

2006-01-01

The Skyrme energy density functional has been applied to the study of heavy-ion fusion reactions. The barriers for fusion reactions are calculated by the Skyrme energy density functional with proton and neutron density distributions determined by using restricted density variational (RDV) method within the same energy density functional together with semi-classical approach known as the extended semi-classical Thomas-Fermi method. Based on the fusion barrier obtained, we propose a parametrization of the empirical barrier distribution to take into account the multi-dimensional character of real barrier and then apply it to calculate the fusion excitation functions in terms of barrier penetration concept. A large number of measured fusion excitation functions spanning the fusion barriers can be reproduced well. The competition between suppression and enhancement effects on sub-barrier fusion caused by neutron-shell-closure and excess neutron effects is studied

Dismountable wall for radiation shielding and screen realized from this wall

International Nuclear Information System (INIS)

Blomart, P.

1988-01-01

The wall for protection against neutrons and gamma radiations is made of bricks with a shoulder on the upper and side faces and the complementary shape on the lower face to provide a barrier to radiations. Bricks are made of a heavy material for gamma absorption and of epoxy resin, boric acid and hydrated alumina [fr

Anterograde-retrograde rendezvous approach for radiation-induced complete upper oesophageal sphincter stenosis: case report and literature review

NARCIS (Netherlands)

Kos, M.P.; David, E.F.; Mahieu, H.F.

2011-01-01

Background: Strictures of the hypopharynx and oesophagus are frequently observed following (chemo)radiation. Anterograde dilatation of a complete stenosis carries a high risk of perforation. An alternative is described: a combined anterograde-retrograde approach.Case report: A 75-year-old man

Project Work Plan: Hanford 100-D Area Treatability Demonstration - In Situ Biostimulation for Reducing Barrier

Energy Technology Data Exchange (ETDEWEB)

Fruchter, Jonathan S.; Truex, Michael J.; Vermeul, Vince R.; Long, Philip E.

2006-05-31

This work plan supports a new, integrated approach to accelerate cleanup of chromium in the Hanford 100 Areas. This new approach will provide supplemental treatment upgradient of the ISRM barrier by directly treating chromium and other oxidizing species in groundwater (i.e., nitrate and dissolved oxygen), thereby increasing the longevity of the ISRM barrier and protecting the ecological receptors and human health at the river boundary.

Tacit Knowledge Barriers in Franchising: Practical Solutions

Science.gov (United States)

Cumberland, Denise; Githens, Rod

2012-01-01

Purpose: The purpose of this paper is to identify barriers that hinder tacit knowledge transfer in a franchise environment and offer a compendium of solutions that encourage franchisees and franchisors to leverage tacit knowledge as a resource for competitive advantage. Design/methodology/approach: Drawing from the research on franchise…

Impedance model for quantum-mechanical barrier problems

International Nuclear Information System (INIS)

Nelin, Evgenii A

2007-01-01

Application of the impedance model to typical quantum-mechanical barrier problems, including those for structures with resonant electron tunneling, is discussed. The efficiency of the approach is illustrated. The physical transparency and compactness of the model and its potential as a teaching and learning tool are discussed. (methodological notes)

Study protocol for an approach based on diagnosis and therapy of cutaneous radiation induced lesions

International Nuclear Information System (INIS)

Di Giorgio, Marina; Vallerga, Maria B.; Radl, Analia; Portas, Mercedes

2008-01-01

Full text: In the frame of an agreement between the 'Hospital de Quemados del Gobierno de la Ciudad de Buenos Aires'-Burn Center- (a reference hospital of the Medical Radiological Emergency Response Network of Argentina) and the Nuclear Regulatory Authority, a research project for diagnostic and therapeutic approach of cutaneous radiation syndrome (CRS) is in progress. Sixty seven persons, which developed acute and/or late CRS, were included in this protocol from 1997 to 2007, treated with an equivalent therapeutic scheme and evaluated through clinical follow-up, serial photographic record and complementary tests (tele-thermography and high frequency ultrasonography). There exist individual variations that could condition the response to ionizing radiation (IR) in not only accidental but also planned exposures (such as radiotherapy and interventional radiology). Deficiencies in DNA repair mechanisms would be involved on hypersensitivity to deterministic effects of IR. Consequently, the characterization of DNA repair capacity in lymphocytes through cytokinesis blocked micronucleus (MN) and alkaline single-cell microgel electrophoresis (comet) assays could be suitable approaches to evaluate in vitro individual radiosensitivity. Under this context, individual radiosensitivity assessment was conducted in patients included in this research protocol that showed acute and/or late cutaneous reactions with grades 3 and 4 of the Toxicity Criteria of the Radiation Therapy Oncology Group and the European Organization for Research and Treatment of Cancer. DNA repair capacity was evaluated through MN and comet assay for initial damage and after specific times of repair (0-120 minutes). DNA damage and repair capacity were quantified by the Olive tail moment. Previous own studies have identified three subpopulations, characterized by the mean values of their repair mean half-time: healthy controls (2.6 ± 0.3 minutes), average-reactor cancer patients (4.7 ± 2.9 minutes) and over

Study Protocol for an Approach Based on Diagnosis and Therapy of Cutaneous Radiation Induced Lesions

International Nuclear Information System (INIS)

Di Giorgio, M.; Vallerga, M.B.; Radl, A.; Portas, M.

2011-01-01

In the frame of an agreement between the 'Hospital de Quemados del Gobierno de la Ciudad de Buenos Aires' - Burn Center - (a reference hospital of the Medical Radiological Emergency Response Network of Argentina) and the Nuclear Regulatory Authority, a research project for diagnostic and therapeutic approach of cutaneous radiation syndrome (CRS) is in progress. Sixty seven persons, which developed acute and/or late CRS, were included in this protocol from 1997 to 2007, treated with an equivalent therapeutic scheme and evaluated through clinical follow-up, serial photographic record and complementary tests (telethermography and high frequency ultrasonography). There exist individual variations that could condition the response to ionizing radiation (IR) in not only accidental but also planned exposures (such as radiotherapy and interventional radiology). Deficiencies in DNA repair mechanisms would be involved on hypersensitivity to deterministic effects of IR. Consequently, the characterization of DNA repair capacity in lymphocytes through cytokinesis blocked micronucleus (MN) and alkaline single-cell microgel electrophoresis (comet) assays could be suitable approaches to evaluate in vitro individual radiosensitivity. Under this context, individual radiosensitivity assessment was conducted in patients included in this research protocol that showed acute and/or late cutaneous reactions with grades 3 and 4 of the Toxicity Criteria of the Radiation Therapy Oncology Group and the European Organization for Research and Treatment of Cancer. DNA repair capacity was evaluated through MN and comet assay for initial damage and after specific times of repair (0-120 minutes). DNA damage and repair capacity were quantified by the Olive tail moment. Previous own studies have identified three subpopulations, characterized by the mean values of their repair mean half-time: healthy controls (2.6 ± 0.3 minutes), average-reactor cancer patients (4.7 ± 2.9 minutes) and over

ALARA and an integrated approach to radiation protection

International Nuclear Information System (INIS)

Hendee, W.R.; Edwards, F.M.

1986-01-01

Exposures of individuals to ionizing radiation have been restricted for many years by a number of guidelines and rules developed by various advisory and regulatory groups. Accompanying these restrictions has been an evolving principle that exposures to individuals and groups should be kept as low as reasonably achievable (ALARA), consistent with provision of the benefits of radiation use to society. Although the ALARA concept is a laudable goal in principle, its implementation in a clinical facility has not been a straightforward process. Problems of implementing ALARA have been confounded further by the efforts of regulatory agencies to incorporate the ALARA concept into regulations governing radiation exposures. To facilitate the implementation of ALARA as a workable construct in a clinical facility, guidelines are needed for its application to both individual and collective exposures to radiation. The provision of such guidelines, including action and inaction levels for both individual and collective exposures, are presented here

Numerical investigation of dielectric barrier discharges

Science.gov (United States)

Li, Jing

1997-12-01

A dielectric barrier discharge (DBD) is a transient discharge occurring between two electrodes in coaxial or planar arrangements separated by one or two layers of dielectric material. The charge accumulated on the dielectric barrier generates a field in a direction opposite to the applied field. The discharge is quenched before an arc is formed. It is one of the few non-thermal discharges that operates at atmospheric pressure and has the potential for use in pollution control. In this work, a numerical model of the dielectric barrier discharge is developed, along with the numerical approach. Adaptive grids based on the charge distribution is used. A self-consistent method is used to solve for the electric field and charge densities. The Successive Overrelaxation (SOR) method in a non-uniform grid spacing is used to solve the Poisson's equation in the cylindrically-symmetric coordinate. The Flux Corrected Transport (FCT) method is modified to solve the continuity equations in the non-uniform grid spacing. Parametric studies of dielectric barrier discharges are conducted. General characteristics of dielectric barrier discharges in both anode-directed and cathode-directed streamer are studied. Effects of the dielectric capacitance, the applied field, the resistance in external circuit and the type of gases (O2, air, N2) are investigated. We conclude that the SOR method in an adaptive grid spacing for the solution of the Poisson's equation in the cylindrically-symmetric coordinate is convergent and effective. The dielectric capacitance has little effect on the g-factor of radical production, but it determines the strength of the dielectric barrier discharge. The applied field and the type of gases used have a significant role on the current peak, current pulse duration and radical generation efficiency, discharge strength, and microstreamer radius, whereas the external series resistance has very little effect on the streamer properties. The results are helpful in

Radiation protection - thirty years after

International Nuclear Information System (INIS)

Ninkovic, M.M.

1989-01-01

In this paper is discussed some questions in the field of Radiation Protection as like: historical prologue of radiations discovery and it's systematics; radiation and radiation protection; ALARA principle and 'de minimis' approach; radiation risks and dose limits and radiation and chemicals a risk comparison (author)

Radiation protection - thirty years after

Energy Technology Data Exchange (ETDEWEB)

Ninkovic, M M [Institute of Nuclear Sciences Boris Kidric, Vinca, Beograd (Serbia and Montenegro)

1989-07-01

In this paper is discussed some questions in the field of Radiation Protection as like: historical prologue of radiations discovery and it's systematics; radiation and radiation protection; ALARA principle and 'de minimis' approach; radiation risks and dose limits and radiation and chemicals a risk comparison (author)

Modeling radiation loads in the ILC main linac and a novel approach to treat dark current

Energy Technology Data Exchange (ETDEWEB)

Mokhov, Nilolai V. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Rakhno, Igor L. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Tropin, Igor S. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

2017-09-11

Electromagnetic and hadron showers generated by electrons of dark current (DC) can represent a significant radiation threat to the ILC linac equipment and personnel. In this study, a commissioning scenario is analysed which is considered as the worst-case scenario for the main linac regarding the DC contribution to the radiation environment in the tunnel. A normal operation scenario is analysed as well. An emphasis is made on radiation load to sensitive electronic equipment—cryogenic thermometers inside the cryomodules. Prompt and residual dose rates in the ILC main linac tunnels were also calculated in these new high-statistics runs. A novel approach was developed—as a part of general purpose Monte Carlo code MARS15—to model generation, acceleration and transport of DC electrons in electromagnetic fields inside SRF cavities. Comparisons were made with a standard approach when a set of pre-calculated DC electron trajectories is used, with a proper normalization, as a source for Monte Carlo modelling. Results of MARS15 Monte Carlo calculations, performed for the current main linac tunnel design, reveal that the peak absorbed dose in the cryogenic thermometers in the main tunnel for 20 years of operation is about 0.8 MGy. The calculated contact residual dose on cryomodules and tunnel walls in the main tunnel for typical irradiation and cooling conditions is 0.1 and 0.01 mSv/hr, respectively.

Testing of isolation barrier sealing surfaces

Energy Technology Data Exchange (ETDEWEB)

Graves, C.E.

1994-12-15

Isolation barrier doors are to be installed in the 105KE and 105KW basins as part of the 1994 unreviewed safety question (USQ) resolution plan to isolate the fuel storage basin from the fuel discharge chute. Included in this installation is the placement of new sealing surfaces for the barriers by affixing stainless steel plates to existing carbon steel angle bars with a specially formulated epoxy adhesive/sealant material. The sealant is a two-part component consisting of an epoxy resin (the condensation product of bisphenol A and epichlorohydrin) and a curing agent (a proprietary cycloaliphatic polyamine). The sealant is solvent free (complying with air pollution regulations) and capable of withstanding the surrounding radiation fields over an estimated 15-year service life. The epoxy sealant experiences negligible water damage partly because of its hydrophobic (water-repelling) nature. With bond tensile strengths measured at greater than 862 kPa (125 lbf/in{sup 2}), the epoxy sealant is judged acceptable for its intended application. The four-hour pot life of the epoxy sealant provides sufficient time to apply the epoxy, examine the epoxy bead for continuity, and position the stainless steel sealing plates.

Testing of isolation barrier sealing surfaces

International Nuclear Information System (INIS)

Graves, C.E.

1994-01-01

Isolation barrier doors are to be installed in the 105KE and 105KW basins as part of the 1994 unreviewed safety question (USQ) resolution plan to isolate the fuel storage basin from the fuel discharge chute. Included in this installation is the placement of new sealing surfaces for the barriers by affixing stainless steel plates to existing carbon steel angle bars with a specially formulated epoxy adhesive/sealant material. The sealant is a two-part component consisting of an epoxy resin (the condensation product of bisphenol A and epichlorohydrin) and a curing agent (a proprietary cycloaliphatic polyamine). The sealant is solvent free (complying with air pollution regulations) and capable of withstanding the surrounding radiation fields over an estimated 15-year service life. The epoxy sealant experiences negligible water damage partly because of its hydrophobic (water-repelling) nature. With bond tensile strengths measured at greater than 862 kPa (125 lbf/in 2 ), the epoxy sealant is judged acceptable for its intended application. The four-hour pot life of the epoxy sealant provides sufficient time to apply the epoxy, examine the epoxy bead for continuity, and position the stainless steel sealing plates

Permeating disciplines: Overcoming barriers between molecular simulations and classical structure-function approaches in biological ion transport.

Science.gov (United States)

Howard, Rebecca J; Carnevale, Vincenzo; Delemotte, Lucie; Hellmich, Ute A; Rothberg, Brad S

2018-04-01

Ion translocation across biological barriers is a fundamental requirement for life. In many cases, controlling this process-for example with neuroactive drugs-demands an understanding of rapid and reversible structural changes in membrane-embedded proteins, including ion channels and transporters. Classical approaches to electrophysiology and structural biology have provided valuable insights into several such proteins over macroscopic, often discontinuous scales of space and time. Integrating these observations into meaningful mechanistic models now relies increasingly on computational methods, particularly molecular dynamics simulations, while surfacing important challenges in data management and conceptual alignment. Here, we seek to provide contemporary context, concrete examples, and a look to the future for bridging disciplinary gaps in biological ion transport. This article is part of a Special Issue entitled: Beyond the Structure-Function Horizon of Membrane Proteins edited by Ute Hellmich, Rupak Doshi and Benjamin McIlwain. Copyright © 2017 Elsevier B.V. All rights reserved.

Tunneling time through a barrier using the tempus operator

Energy Technology Data Exchange (ETDEWEB)

Kobe, Donald H.; Aguilera-Navarro, Valdir C. [North Texas Univ., Denton, TX (United States). Dept. of Physics

1996-11-01

The time a particle spends in a classically forbidden region of a potential barrier is expressed as an expectation value of the time operator in that region. Classically, time is canonically conjugate to the energy and is equal to the time a conservative system. The tunneling time is calculated by this approach for a rectangular barrier, which gives a complex time. The imaginary part of the time is non negative, so it is interpreted as a tunneling time. The real part gives a negative value for some values of the parameters, and is therefore rejected because it violates causality. This tunneling time is compared with other tunneling times that have been suggested by also calculating them for the rectangular barrier. 58 refs., 7 figs.

Tunneling time through a barrier using the tempus operator

International Nuclear Information System (INIS)

Kobe, Donald H.; Aguilera-Navarro, Valdir C.

1996-11-01

The time a particle spends in a classically forbidden region of a potential barrier is expressed as an expectation value of the time operator in that region. Classically, time is canonically conjugate to the energy and is equal to the time a conservative system. The tunneling time is calculated by this approach for a rectangular barrier, which gives a complex time. The imaginary part of the time is non negative, so it is interpreted as a tunneling time. The real part gives a negative value for some values of the parameters, and is therefore rejected because it violates causality. This tunneling time is compared with other tunneling times that have been suggested by also calculating them for the rectangular barrier. 58 refs., 7 figs

Effects of UVA (320-400 nm) on the barrier characteristics of the skin

International Nuclear Information System (INIS)

McAuliffe, D.J.; Blank, I.H.

1991-01-01

The stratum corneum serves as the major barrier to the entrance of most molecules into the skin. In the studies presented here, the effects of UVA radiation (320-400 nm) on the barrier capacity of human stratum corneum were examined. Penetration of a homologous series of primary alcohols through unirradiated (control) and UVA-irradiated (test) human epidermis was determined in vitro. Permeability constants, kp, were calculated. Mean ratios of permeability constants for UVA-irradiated and unirradiated epidermis (mean kp test)/(mean kp control) ranged from 2.3 to 3.0 for methanol and from 2.2 to 2.5 for ethanol. These mean ratios were determined using different pieces of epidermis from the same piece of skin for test and control samples. When kp control and kp test were determined on the same piece of epidermis on successive days, the ratios (kp test/kp control) were similar to the mean ratios determined on different pieces of epidermis. For other primary alcohols, propanol, butanol, hexanol, and heptanol, UVA radiation did not alter their permeability constants significantly. Partition coefficients, Km, were determined for ethanol and heptanol using UVA-irradiated and unirradiated stratum corneum. For ethanol, irradiation resulted in a 1.5 to 2.6 times increase in Km. For heptanol, irradiation caused no change in Km. These results demonstrate that the barrier capacity of stratum corneum for small, polar, primary alcohols is diminished (permeability increases) and for higher molecular weight less polar alcohols, is unaffected by small doses of UVA radiation. This increased permeability of small polar alcohols through human skin may be due to enhanced partitioning into UVA-irradiated stratum corneum, which was not apparent for a higher molecular weight less polar alcohol

Perceived barriers and enablers of physical activity in postpartum women: a qualitative approach.

Science.gov (United States)

Saligheh, Maryam; McNamara, Beverley; Rooney, Rosanna

2016-06-02

Postpartum women's recovery from birth can be assisted through increased physical activity (PA). However, women face substantial barriers to participating in exercise and require support to enable them to benefit from increased PA. This study sought to explore women's beliefs about and experiences of PA and exercise during the 6 weeks to 12 months postpartum period. A cohort of 14 postpartum women from a survey study of the barriers and enablers to exercise participation agreed to take part in interview sessions to provide an in-depth understanding of the women's perceptions of the postpartum period and their physical activity during this time. Findings are presented with reference to the social ecological framework and indicate postpartum women face substantial personal and environmental barriers to PA and exercise participation: fatigue, a lack of motivation and confidence, substantial time constraints, lack of access to affordable and appropriate activities and poor access to public transport. In contrast, enablers such as possessing greater social support, in particular partner support, improved PA and exercise participation. The findings encourage facilitation of exercise through mothers' groups, mothers' exercise clubs or postnatal classes suggesting behavioral and social change is needed. Interaction between individuals, community, organizations and policy makers is required. In addition, the provision of specifically tailored and appropriate exercise programs could potentially enable increased PA in postpartum women, thereby improving their health.

Stability of barrier buckets with zero RF-barrier separations

Energy Technology Data Exchange (ETDEWEB)

Ng, K.Y.; /Fermilab

2005-03-01

A barrier bucket with very small separation between the rf barriers (relative to the barrier widths) or even zero separation has its synchrotron tune decreasing rather slowly from a large value towards the boundary of the bucket. As a result, large area at the bucket edges can become unstable under the modulation of rf voltage and/or rf phase. In addition, chaotic regions may form near the bucket center and extend outward under increasing modulation. Application is made to those barrier buckets used in the process of momentum mining at the Fermilab Recycler Ring.

Community Participation and Barriers in Rural Tourism: A Case Study in Kiulu, Sabah

OpenAIRE

Velnisa Paimin N. F.; Modilih S.; Mogindol S. H.; Johnny C.; Thamburaj J. A.

2014-01-01

The paper presents an investigation on local community participation and barriers in rural tourism. It identifies two sides of community participation in tourism as identified by Timothy [5], which are; the benefits point of view and from the decision making process perspective. It also identifies the communities’ barriers in engaging in tourism and uses Tosun’s [18] approach in examining the barriers. A total of eighty-three questionnaire forms were completed by respondents from seven villag...

Test validation of environmental barrier coating (EBC) durability and damage tolerance modeling approach

Science.gov (United States)

Abdul-Aziz, Ali; Najafi, Ali; Abdi, Frank; Bhatt, Ramakrishna T.; Grady, Joseph E.

2014-03-01

Protection of Ceramic Matrix Composites (CMCs) is rather an important element for the engine manufacturers and aerospace companies to help improve the durability of their hot engine components. The CMC's are typically porous materials which permits some desirable infiltration that lead to strength enhancements. However, they experience various durability issues such as degradation due to coating oxidation. These concerns are being addressed by introducing a high temperature protective system, Environmental Barrier Coating (EBC) that can operate at temperature applications1, 3 In this paper, linear elastic progressive failure analyses are performed to evaluate conditions that would cause crack initiation in the EBC. The analysis is to determine the overall failure sequence under tensile loading conditions on different layers of material including the EBC and CMC in an attempt to develop a life/failure model. A 3D finite element model of a dogbone specimen is constructed for the analyses. Damage initiation, propagation and final failure is captured using a progressive failure model considering tensile loading conditions at room temperature. It is expected that this study will establish a process for using a computational approach, validated at a specimen level, to predict reliably in the future component level performance without resorting to extensive testing.

Radiation dose optimization research: Exposure technique approaches in CR imaging – A literature review

International Nuclear Information System (INIS)

Seeram, Euclid; Davidson, Rob; Bushong, Stewart; Swan, Hans

2013-01-01

The purpose of this paper is to review the literature on exposure technique approaches in Computed Radiography (CR) imaging as a means of radiation dose optimization in CR imaging. Specifically the review assessed three approaches: optimization of kVp; optimization of mAs; and optimization of the Exposure Indicator (EI) in practice. Only papers dating back to 2005 were described in this review. The major themes, patterns, and common findings from the literature reviewed showed that important features are related to radiation dose management strategies for digital radiography include identification of the EI as a dose control mechanism and as a “surrogate for dose management”. In addition the use of the EI has been viewed as an opportunity for dose optimization. Furthermore optimization research has focussed mainly on optimizing the kVp in CR imaging as a means of implementing the ALARA philosophy, and studies have concentrated on mainly chest imaging using different CR systems such as those commercially available from Fuji, Agfa, Kodak, and Konica-Minolta. These studies have produced “conflicting results”. In addition, a common pattern was the use of automatic exposure control (AEC) and the measurement of constant effective dose, and the use of a dose-area product (DAP) meter

CAPILLARY BARRIERS IN UNSATURATED FRACTURED ROCKS OF YUCCA MOUNTAIN, NEVADA

International Nuclear Information System (INIS)

Wu, Y.S.; Zhang, W.; Pan, L.; Hinds, J.; Bodvarsson, G.

2000-01-01

This work presents modeling studies investigating the effects of capillary barriers on fluid-flow and tracer-transport processes in the unsaturated zone of Yucca Mountain, Nevada, a potential site for storing high-level radioactive waste. These studies are designed to identify factors controlling the formation of capillary barriers and to estimate their effects on the extent of possible large-scale lateral flow in unsaturated fracture rocks. The modeling approach is based on a continuum formulation of coupled multiphase fluid and tracer transport through fractured porous rock. Flow processes in fractured porous rock are described using a dual-continuum concept. In addition, approximate analytical solutions are developed and used for assessing capillary-barrier effects in fractured rocks. This study indicates that under the current hydrogeologic conceptualization of Yucca Mountain, strong capillary-barrier effects exist for significantly diverting moisture flow

A new alternative in vertical barrier wall construction

International Nuclear Information System (INIS)

Rawl, G.F.

1997-01-01

A new proprietary vertical barrier wall system has been developed to revolutionize the construction process by eliminating many of the concerns of conventional installation method's with respect to performance, installation constraints and costs. Vertical barrier walls have been used in the environmental and construction industries for a variety of purposes, usually for cut-off or containment. The typical scenario involves a groundwater contamination problem, in which a vertical barrier wall is utilized to contain or confine the spread of contaminants below the ground surface. Conventional construction techniques have been adequate in many applications, but often fall short of their intended purposes due to physical constraints. In many instances, the economics of these conventional methods have limited the utilization of physical barrier walls. Polywall, the trade name for this new barrier wall technology, was subsequently developed to meet these needs and offer a number of distinct advantages in a variety of scenarios by maximizing confinement and minimizing installation costs. Polywall is constructed from chemically resistant high density polyethylene (HDPE) plastic. It has proven in a half-dozen projects to date to be the most cost-effective and technically sound approach to many containment situations. This paper will cover the development of the technology and will provide a brief synopsis of several installations

Altered Blood-Brain Barrier Permeability in Patients With Systemic Lupus Erythematosus: A Novel Imaging Approach.

Science.gov (United States)

Gulati, Gaurav; Jones, Jordan T; Lee, Gregory; Altaye, Mekibib; Beebe, Dean W; Meyers-Eaton, Jamie; Wiley, Kasha; Brunner, Hermine I; DiFrancesco, Mark W

2017-02-01

To evaluate a safe, noninvasive magnetic resonance imaging (MRI) method to measure regional blood-brain barrier integrity and investigate its relationship with neurocognitive function and regional gray matter volume in juvenile-onset systemic lupus erythematosus (SLE). In this cross-sectional, case-control study, capillary permeability was measured as a marker of blood-brain barrier integrity in juvenile SLE patients and matched healthy controls, using a combination of arterial spin labeling and diffusion-weighted brain MRI. Regional gray matter volume was measured by voxel-based morphometry. Correlation analysis was done to investigate the relationship between regional capillary permeability and regional gray matter volume. Formal neurocognitive testing was completed (measuring attention, visuoconstructional ability, working memory, and psychomotor speed), and scores were regressed against regional blood-brain barrier integrity among juvenile SLE patients. Formal cognitive testing confirmed normal cognitive ability in all juvenile SLE subjects (n = 11) included in the analysis. Regional capillary permeability was negatively associated (P = 0.026) with neurocognitive performance concerning psychomotor speed in the juvenile SLE cohort. Compared with controls (n = 11), juvenile SLE patients had significantly greater capillary permeability involving Brodmann's areas 19, 28, 36, and 37 and caudate structures (P < 0.05 for all). There is imaging evidence of increased regional capillary permeability in juvenile SLE patients with normal cognitive performance using a novel noninvasive MRI technique. These blood-brain barrier outcomes appear consistent with functional neuronal network alterations and gray matter volume loss previously observed in juvenile SLE patients with overt neurocognitive deficits, supporting the notion that blood-brain barrier integrity loss precedes the loss of cognitive ability in juvenile SLE. Longitudinal studies are needed to

The effect of barrier layer-mediated catalytic deactivation in vertically aligned carbon nanotube growth

International Nuclear Information System (INIS)

Patole, S P; Yu, Seong-Man; Shin, Dong-Wook; Yoo, Ji-Beom; Kim, Ha-Jin; Han, In-Taek; Kwon, Kee-Won

2010-01-01

The effect of Al-barrier layer-mediated Fe-catalytic deactivation in vertically aligned carbon nanotube (CNT) growth was studied. The substrate surface morphology, catalytic diffusion and barrier layer oxidation were found to be dependent on the annealing temperature of the barrier layer, which ultimately affects CNT growth. The annealed barrier layer without complete oxidation was found to be suitable for top to bottom super aligned CNT arrays. The highest average CNT growth rate of up to 3.88 μm s -1 was observed using this simple approach. Details of the analysis are also presented.

Where Diffusion of Clean Technologies and Barriers to Innovation Clash: Application to the Global Diffusion of the Electrical Arc Furnace

Directory of Open Access Journals (Sweden)

José Antonio Moya

2017-01-01

Full Text Available This paper analyses the role of barriers preventing the worldwide take-up of a clean technology: the electrical arc furnace. It also identifies which barriers affect a parameter that summarises the combined effect of all of them. The first step, determination of the combined effect of the barriers, is carried out using a novel approach to model the diffusion of innovations. This new approach is composed only by terms that account for the driver of innovations and the parameter that summarises the effect of barriers. The objective quantification of the effect of barriers in the diffusion of innovations opens up new opportunities for designing policies to overcome the barriers identified as the most relevant, for identifying the effect of existing policies, for relating innovation indicators with those barriers or for better incorporating the effect of barriers in bottom-up models that forecast the technological evolution of the economy.

Performance of buffer material under radiation and thermal conditions

International Nuclear Information System (INIS)

Zhao Shuaiwei; Yang Zhongtian; Liu Wei

2012-01-01

Bentonite is generally selected as backfill and buffer material for repositories in the world. Radiation and heat release is the intrinsic properties of high level radioactive waste. This paper made a preliminary research on foreign literature about performance of the engineering barrier material under radiation and at higher temperatures (e. g. above 100℃). As our current research is just budding in this area, we need to draw lessons from foreign experience and methods. (authors)

Lowering Entry Barriers for Multidisciplinary Cyber(e)-Infrastructures

Science.gov (United States)

Nativi, S.

2012-04-01

Multidisciplinarity is more and more important to study the Earth System and address Global Changes. To achieve that, multidisciplinary cyber(e)-infrastructures are an important instrument. In the last years, several European, US and international initiatives have been started to carry out multidisciplinary infrastructures, including: the Spatial Information in the European Community (INSPIRE), the Global Monitoring for Environment and Security (GMES), the Data Observation Network for Earth (DataOne), and the Global Earth Observation System of Systems (GEOSS). The majority of these initiatives are developing service-based digital infrastructures asking scientific Communities (i.e. disciplinary Users and data Producers) to implement a set of standards for information interoperability. For scientific Communities, this has represented an entry barrier which has proved to be high, in several cases. In fact, both data Producers and Users do not seem to be willing to invest precious resources to become expert on interoperability solutions -on the contrary, they are focused on developing disciplinary and thematic capacities. Therefore, an important research topic is lowering entry barriers for joining multidisciplinary cyber(e)-Infrastructures. This presentation will introduce a new approach to achieve multidisciplinary interoperability underpinning multidisciplinary infrastructures and lowering the present entry barriers for both Users and data Producers. This is called the Brokering approach: it extends the service-based paradigm by introducing a new a Brokering layer or cloud which is in charge of managing all the interoperability complexity (e.g. data discovery, access, and use) thus easing Users' and Producers' burden. This approach was successfully experimented in the framework of several European FP7 Projects and in GEOSS.

Quantifying Cancer Risk from Radiation.

Science.gov (United States)

Keil, Alexander P; Richardson, David B

2017-12-06

Complex statistical models fitted to data from studies of atomic bomb survivors are used to estimate the human health effects of ionizing radiation exposures. We describe and illustrate an approach to estimate population risks from ionizing radiation exposure that relaxes many assumptions about radiation-related mortality. The approach draws on developments in methods for causal inference. The results offer a different way to quantify radiation's effects and show that conventional estimates of the population burden of excess cancer at high radiation doses are driven strongly by projecting outside the range of current data. Summary results obtained using the proposed approach are similar in magnitude to those obtained using conventional methods, although estimates of radiation-related excess cancers differ for many age, sex, and dose groups. At low doses relevant to typical exposures, the strength of evidence in data is surprisingly weak. Statements regarding human health effects at low doses rely strongly on the use of modeling assumptions. © 2017 Society for Risk Analysis.

A non-parametric, microdosimetric-based approach to the evaluation of the biological effects of low doses of ionizing radiation

International Nuclear Information System (INIS)

Varma, M.N.; Zaider, M.

1992-01-01

A microdosimetric-based specific quality factor, q(y), is determined for eight sets of experimental data on cellular inactivation, mutation, chromosome aberration and neoplastic transformation. Bias-free Bayesian and maximum entropy approaches were used. A comparison of the curves q(y) thus determined reveals a surprising degree of uniformity. In our view this is prima facie evidence that the spatial pattern of microscopic energy deposition - rather than the specific end point or cellular system - is the quantity which determines the dependency of the cellular response to the quality of the ionizing radiation. For further applications of this approach to radiation protection experimental microdosimetric spectra are urgently needed. Further improvement in the quality of the q(y) functions could provide important clues on fundamental biophysical mechanisms. (author)

Pneumatic radiator of transition radiation for large working area arrangements

International Nuclear Information System (INIS)

Shikhlyarov, K.K.; Gavalyan, V.G.

1993-01-01

An unconventional approach to the constructions of large area regular radiator of X-rays transition radiation is proposed based on the use of a pack of hermetically sealed bags, in which elastic helium layers are formed. A prototype of such a radiator of about 1m 2 area was made for test of the proposed device. 9 refs

Experimental investigation on large-area dielectric barrier discharge in atmospheric nitrogen and air assisted by the ultraviolet lamp.

Science.gov (United States)

Zhang, Yan; Gu, Biao; Wang, Wenchun; Wang, Dezhen; Peng, Xuwen

2009-04-01

In this paper, ultraviolet radiation produced by the ultraviolet lamp is employed to supply pre-ionization for the dielectric barrier discharge in N(2) or air at atmospheric pressure. The effect of the ultraviolet pre-ionization on improving the uniformity of the dielectric barrier discharge is investigated experimentally. The atmospheric pressure glow discharge of the large area (270 mm x 120 mm) is obtained successfully via the ultraviolet pre-ionization in atmospheric DBD in N(2) when the gas gap decrease to 3mm. Based on the emission spectra, the mechanism which ultraviolet pre-ionization improves the uniformity of the dielectric barrier discharge is discussed.

Safety- barrier diagrams

DEFF Research Database (Denmark)

Duijm, Nijs Jan

2008-01-01

Safety-barrier diagrams and the related so-called 'bow-tie' diagrams have become popular methods in risk analysis. This paper describes the syntax and principles for constructing consistent and valid safety-barrier diagrams. The relation of safety-barrier diagrams to other methods such as fault...... trees and Bayesian networks is discussed. A simple method for quantification of safety-barrier diagrams is proposed. It is concluded that safety-barrier diagrams provide a useful framework for an electronic data structure that integrates information from risk analysis with operational safety management....

Safety-barrier diagrams

DEFF Research Database (Denmark)

Duijm, Nijs Jan

2007-01-01

Safety-barrier diagrams and the related so-called "bow-tie" diagrams have become popular methods in risk analysis. This paper describes the syntax and principles for constructing consistent and valid safety-barrier diagrams. The relation with other methods such as fault trees and Bayesian networks...... are discussed. A simple method for quantification of safety-barrier diagrams is proposed, including situations where safety barriers depend on shared common elements. It is concluded that safety-barrier diagrams provide a useful framework for an electronic data structure that integrates information from risk...... analysis with operational safety management....

Survey of Michigan dentists and radiation oncologists on oral care of patients undergoing head and neck radiation therapy.

Science.gov (United States)

Patel, Yoshita; Bahlhorn, Hannah; Zafar, Saniya; Zwetchkenbaum, Samuel; Eisbruch, Avraham; Murdoch-Kinch, Carol Anne

2012-07-01

Oral complications of radiation therapy for head and neck cancer (HNC) are associated with a significant decline in oral health-related quality of life (OHQOL). The dentist, working with the radiation oncologist and the rest of the health care team, plays an important role in the prevention and management of these complications, but patients do not always receive care consistent with current guidelines. This study investigated barriers to recommended care. There is variability in knowledge and practice among dentists and radiation oncologists regarding the dental management of patients treated with head and neck radiotherapy (HNRT), and inadequate communication and collaboration between members of the patient's health care team contribute to inconsistencies in application of clinical care guidelines. There is on interest and need for continuing dental (CDE) and medical education (CME) on this topic. A questionnaire was developed to assess dentists' knowledge and practice of dental management of HNC patients and their interest in CDE on this topic. All members of the Michigan Dental Association (MDA) with email addresses were asked to complete the survey online, and a random sample of MDA members without email addresses was invited to complete a paper version of the same survey. All Michigan members of the American Society for Radiation Oncology (ASTRO) were invited to complete an online version of the survey modified for radiation oncologists. The response rate for dentists was 47.9% and radiation oncologists was 22.3%. Of the dentists who responded, 81% reported that a major barrier to providing dental treatment before radiotherapy was a lack of time between initial dental consultation and the start of radiation; inadequate communication between health care providers was blamed most frequently for this. Ten percent of the dentists and 25% of the radiation oncologists reported that they did not treat HNC patients because they lacked adequate training, and 55% of

The development of new environmental policies and processes in response to a crisis: the case of the multiple barrier approach for safe drinking water

International Nuclear Information System (INIS)

Plummer, Ryan; Velaniskis, Jonas; Grosbois, Danuta de; Kreutzwiser, Reid D.; Loe, Rob de

2010-01-01

While new environmental policies and procedures often are developed incrementally, they can also result from crises or other significant events. In situations where policies and procedures are introduced in response to a crisis, questions about the strengths and weaknesses of existing mechanisms, and the extent to which they can be used to address concerns, may be ignored. This paper explores the complexities of introducing new policies and processes where planning systems and procedures already exist. Drinking water source protection policies that are being developed in response to the tragic events in Walkerton, Ontario, Canada serve as the context for the inquiry. Three case study watersheds were selected to reflect the diversity of municipal jurisdictions and water supply systems in Ontario. A content analysis was undertaken on regulatory and non-regulatory policy documents to determine the extent to which they addressed elements of the multi-barrier approach for drinking water safety. Findings from the research reveal considerable evidence of the multi-barrier approach in the policy and guiding documents analyzed. Policy development in response to a crisis can advance progress on the issue of drinking water safety and coincide with emerging governance strategies. Policy effectiveness may be enhanced by considering existing policies as well as contextual and jurisdictional differences.

Hydraulic performance of permeable barriers for in situ treatment of contaminated groundwater

International Nuclear Information System (INIS)

Smyth, D.J.A.; Shikaze, S.G.; Cherry, J.A.

1997-01-01

The passive interception and in situ treatment of dissolved contaminants in groundwater by permeable reactive barriers has recently gained favor at an increasing number of sites as an alternative to conventional approaches to groundwater remediation such as the pump-and-treat method. Permeable reactive barriers have two essential functions. The first is that the barriers must be installed in a position such that all of the plume passes through the reactive system. The second function is to achieve acceptable treatment of the contamination by physical, chemical or biological means within or downgradient of the barrier. In this paper, issues associated with the hydraulic performance of permeable reaction barriers are evaluated using a three-dimensional groundwater flow model. The efficiency of plume capture by permeable wall and funnel-and-gate systems is examined for some generic and for site-specific hydrogeologic systems. The results have important implications to decisions pertaining to the selection, design and installation of permeable reactive barrier systems

Effective Life Cycle Management in SMEs: Use of a Sector-Based Approach to Overcome Barriers

Directory of Open Access Journals (Sweden)

Helene Seidel-Sterzik

2018-01-01

Full Text Available One approach to incorporate sustainability in organisations is the implementation of life cycle management (LCM. LCM involves sharing responsibility for addressing environmental impacts across the entire supply chain of products and services, extending from raw material extraction to end-of-life of the product. The New Zealand primary sector relies heavily on natural resources and provides about 70% of the country’s export revenue. Most companies in primary industry sectors in New Zealand are small and medium-sized enterprises (SMEs. Successful sector-wide uptake of LCM can potentially facilitate effective measurement and management of environmental impacts caused by this sector. The aim of this research was to identify the barriers and enablers to successful LCM uptake by New Zealand primary sector SMEs within a sector-based context. An extensive review of the literature was undertaken in the areas of change management for SMEs and supply chain management. The main factors influencing successful LCM uptake include owner/manager influence, environmental culture, resource availability, future orientation, knowledge of environmental issues, market requirements, geographical separation of production and consumption, awareness of own environmental issues and communication/information sharing. This paper forms the basis for future research and development of tools for the effective implementation of sector based approaches to LCM in the primary industry. The results of this research include a capability maturity model and the development of a cloud based platform for collaboration and communication around LCM.

Fusion and particle transfer around the Coulomb-Barrier in intermediate systems

International Nuclear Information System (INIS)

Pascholati, P.R.

1989-01-01

The most important characteristics of fusion reactions below and around the Coulomb-barrier are summarized. Experimental fusion cross sections for typical systems are discussed and compared with current formulae obtained from semi-classical and quantum tunneling approaches. The influence of nucleons transfer in the enhancement of the fusion cross section below the Coulomb-barrier is also shown. Sub-barrier fusion cross sections for the systems 35,37 Cl + 58,64 Ni and 33 S + 90,91,92 Zr, and near-barrier cross sections of all important transfer channels have been measured using the XTU-TANDEM at Legnaro, Italy. In 35,37 Cl + 58,64 Ni systems, the motivation further investigated was the influence of the valence proton in the enhancement of the sub-barrier fusion cross section. The data are discussed in comparison with the similar data of 34,36 S + 58,64 Ni with the aim of revealing the influence of coupled proton transfer channels. Calculations were performed using the simplified coupled channel code CCFUS including ''pick-up'' of one and two neutrons and ''stripping'' of two neutrons channels. Signatures of positive Q-values transfer channels coupled to fusion were clearly identified. For the 33 S + 90,91,92 Zr systems taking into account the coupling effects between transfer and fusion and using the semi-classical approach, transfer form-factors were extracted and succesfully employed to described the isotopic effects in fusion enhancement. (Author) [es

Vehicle barrier systems

International Nuclear Information System (INIS)

Sena, P.A.

1986-01-01

The ground vehicle is one of the most effective tools available to an adversary force. Vehicles can be used to penetrate many types of perimeter barriers, transport equipment and personnel rapidly over long distances, and deliver large amounts of explosives directly to facilities in suicide missions. The function of a vehicle barrier system is to detain or disable a defined threat vehicle at a selected distance from a protected facility. Numerous facilities are installing, or planning to install, vehicle barrier systems and many of these facilities are requesting guidance to do so adequately. Therefore, vehicle barriers are being evaluated to determine their stopping capabilities so that systems can be designed that are both balanced and capable of providing a desired degree of protection. Equally important, many of the considerations that should be taken into account when establishing a vehicle barrier system have been identified. These considerations which pertain to site preparation, barrier selection, system integration and operation, and vehicle/barrier interaction, are discussed in this paper

Implementing the Kyoto mechanisms. Political barriers and path dependence

International Nuclear Information System (INIS)

Woerdman, E.

2002-01-01

The objective of the research on the title thesis is to identify and explain political barriers as well as the opportunities to overcome them. Special attention is paid to permit trading, because it is the superior alternative according to neo-classical economic theory. The author's approach is a combination of (1) political science, (2) (neo-)institutional economics and (3) law and economics. An innovative theoretical framework is presented by transforming lock-in theory from a technological and economic context to an institutional context against the background of the political barrier model. This theoretical framework allows to explain the functioning of these political barriers (including institutional, legal and cultural ones), for instance in terms of path-dependencies, positive feedbacks and set-up costs. Empirical analyses are performed to test (parts of) the theory

Trends in drug delivery through tissue barriers containing tight junctions.

Science.gov (United States)

Tscheik, Christian; Blasig, Ingolf E; Winkler, Lars

2013-04-01

A limitation in the uptake of many drugs is the restricted permeation through tissue barriers. There are two general ways to cross barriers formed by cell layers: by transcytosis or by diffusion through the intercellular space. In the latter, tight junctions (TJs) play the decisive role in the regulation of the barrier permeability. Thus, transient modulation of TJs is a potent strategy to improve drug delivery. There have been extensive studies on surfactant-like absorption enhancers. One of the most effective enhancers found is sodium caprate. However, this modulates TJs in an unspecific fashion. A novel approach would be the specific modulation of TJ-associated marvel proteins and claudins, which are the main structural components of the TJs. Recent studies have identified synthetic peptidomimetics and RNA interference techniques to downregulate the expression of targeted TJ proteins. This review summarizes current progress and discusses the impact on TJs' barrier function.

A different approach to evaluating health effects from radiation exposure

International Nuclear Information System (INIS)

Bond, V.P.; Sondhaus, C.A.; Feinendegen, L.E.

1988-01-01

Absorbed dose D is shown to be a composite variable, the product of the fraction of cells hit (I/sub H/) and the mean /open quotes/dose/close quotes/ (hit size) /ovr z/ to those cells. D is suitable for use with high level (HLE) to radiation and its resulting acute organ effects because, since I/sub H/ = 1.0, D approximates closely enough the mean energy density in the cell as well as in the organ. However, with low-level exposure (LLE) to radiation and its consequent probability of cancer induction from a single cell, stochastic delivery of energy to cells results in a wide distribution of hit sizes z, and the expected mean value, /ovr z/, is constant with exposure. Thus, with LLE, only I/sub H/ varies with D so that the apparent proportionality between /open quotes/dose/close quotes/ and the fraction of cells transformed is misleading. This proportionality therefore does not mean that any (cell) dose, no matter how small, can be lethal. Rather, it means that, in the exposure of a population of individual organisms consisting of the constituent relevant cells, there is a small probabililty of particle-cell interactions which transfer energy. The probability of a cell transforming and initiating a cancer can only be greater than zero if the hit size (/open quotes/dose of energy/close quotes/) to the cell is large enough. Otherwise stated, if the /open quotes/dose/close quotes/ is defined at the proper level of biological organization, namely, the cell and not the organ, only a large dose z to that cell is effective. The above precepts are utilized to develop a drastically different approach to evaluation oif risk from LLE, that holds promise of obviating any requirement for the components of the present system: absorbed organ dose, LET, a standard radiation, REB(Q), dose equivalent and rem. 12 refs., 11 figs

A different approach to evaluating health effects from radiation exposure

Energy Technology Data Exchange (ETDEWEB)

Bond, V.P.; Sondhaus, C.A.; Feinendegen, L.E.

1988-01-01

Absorbed dose D is shown to be a composite variable, the product of the fraction of cells hit (I/sub H/) and the mean /open quotes/dose/close quotes/ (hit size) /ovr z/ to those cells. D is suitable for use with high level (HLE) to radiation and its resulting acute organ effects because, since I/sub H/ = 1.0, D approximates closely enough the mean energy density in the cell as well as in the organ. However, with low-level exposure (LLE) to radiation and its consequent probability of cancer induction from a single cell, stochastic delivery of energy to cells results in a wide distribution of hit sizes z, and the expected mean value, /ovr z/, is constant with exposure. Thus, with LLE, only I/sub H/ varies with D so that the apparent proportionality between /open quotes/dose/close quotes/ and the fraction of cells transformed is misleading. This proportionality therefore does not mean that any (cell) dose, no matter how small, can be lethal. Rather, it means that, in the exposure of a population of individual organisms consisting of the constituent relevant cells, there is a small probabililty of particle-cell interactions which transfer energy. The probability of a cell transforming and initiating a cancer can only be greater than zero if the hit size (/open quotes/dose of energy/close quotes/) to the cell is large enough. Otherwise stated, if the /open quotes/dose/close quotes/ is defined at the proper level of biological organization, namely, the cell and not the organ, only a large dose z to that cell is effective. The above precepts are utilized to develop a drastically different approach to evaluation oif risk from LLE, that holds promise of obviating any requirement for the components of the present system: absorbed organ dose, LET, a standard radiation, REB(Q), dose equivalent and rem. 12 refs., 11 figs.

Electron Beam Induced Radiation Damage of the Semiconductor Radiation Detector based on Silicon

International Nuclear Information System (INIS)

Kim, Han Soo; Kim, Yong Kyun; Park, Se Hwan; Haa, Jang Ho; Kang, Sang Mook; Chung, Chong Eun; Cho, Seung Yeon; Park, Ji Hyun; Yoon, Tae Hyung

2005-01-01

A Silicon Surface Barrier (SSB) semiconductor detector which is generally used to detect a charged particle such as an alpha particle was developed. The performance of the developed SSB semiconductor detector was measured with an I-V curve and an alpha spectrum. The response for an alpha particle was measured by Pu-238 sources. A SSB semiconductor detector was irradiated firstly at 30sec, at 30μA and secondly 40sec, 40μA with a 2MeV pulsed electron beam generator in KAERI. And the electron beam induced radiation damage of a homemade SSB detector and the commercially available PIN photodiode were investigated. An annealing effect of the damaged SSB and PIN diode detector were also investigated using a Rapid Thermal Annealing (RTA). This data may assist in designing the silicon based semiconductor radiation detector when it is operated in a high radiation field such as space or a nuclear power plant

Flexibility in radiation protection legislation -the UK approach

International Nuclear Information System (INIS)

Beaver, P.F.; Gill, J.R.

1980-01-01

The case for flexibility in the formulation of radiation protection legislation and that for precise invariable requirements which are applicable to all users of ionising radiations are presented. It is asserted that greater participation on the part of persons affected in the shaping of legislation brings with it a commitment to flexibility if consensus is to be achieved. The nature of the participative and consultative processes in the UK is described. The means by which flexibility will be inbuilt into future UK legislation are discussed, taking as examples, three particular areas: a) Notification of use of ionising radiations, where flexibility needs to be introduced to take care of improved knowledge of potential risk, the avoidance of bureaucratic procedures, and the wide variation in practice from one work activity to another; b) The definition of controlled areas, where flexibility is needed to cope with the wide range of potential use situations, yet if controlled areas are to be the route to defining Category A workers, where that flexibility must be restrained to ensure proper categorysation and effective enforcement; c) The criteria for the need to appoint and for the selection of radiation protection advisers where flexibility must be invoked to ensure that any particular task is matched by the quality of the radiation protection adviser concerned. It is concluded that the proposed UK legislation will achieve flexibility where this is appropriate and cost-effective and on the other hand demand adherence to strictly expressed levels of exposure where that is appropriate. (author)

Atomistic simulation of dislocation nucleation barriers from cracktips in α-Fe

International Nuclear Information System (INIS)

Gordon, Peter A; Neeraj, T; Luton, Michael J

2008-01-01

In this work, we demonstrate that activation pathways for dislocation loop nucleation from cracktips can be explored with full atomistic detail using an efficient form of the nudged elastic band method. The approach is demonstrated in detail with an example of edge emission from an Fe crack under mode II loading, wherein activation energy barriers are obtained as a function of sub-critical stress intensity and the energy barriers for loop formation are compared with 2D calculations. Activation energy barriers are also computed for an intrinsically ductile cracktip orientation under mode I loading, from which we can infer the frequency of nucleation from the cracktip

Renormalization-group approach to nonlinear radiation-transport problems

International Nuclear Information System (INIS)

Chapline, G.F.

1980-01-01

A Monte Carlo method is derived for solving nonlinear radiation-transport problems that allows one to average over the effects of many photon absorptions and emissions at frequencies where the opacity is large. This method should allow one to treat radiation-transport problems with large optical depths, e.g., line-transport problems, with little increase in computational effort over that which is required for optically thin problems

Fission barriers of light nuclei

International Nuclear Information System (INIS)

Grotowski, K.; Planeta, R.; Blann, M.; Komoto, T.

1989-01-01

Experimental fission excitation functions for compound nuclei /sup 52/Fe, /sup 49/Cr, /sup 46/V, and /sup 44/Ti formed in heavy-ion reactions are analyzed in the Hauser-Feshbach/Bohr-Wheeler formalism using fission barriers based on the rotating liquid drop model of Cohen et al. and on the rotating finite range model of Sierk. We conclude that the rotating finite range approach gives better reproduction of experimental fission yields, consistent with results found for heavier systems

Tunnel barrier and noncollinear magnetization effects on shot noise in ferromagnetic/semiconductor/ferromagnetic heterojunctions

International Nuclear Information System (INIS)

An Xingtao; Liu Jianjun

2008-01-01

Based on the scattering approach, we investigate transport properties of electrons in a one-dimensional waveguide that contains a ferromagnetic/semiconductor/ferromagnetic heterojunction and tunnel barriers in the presence of Rashba and Dresselhaus spin-orbit interactions. We simultaneously consider significant quantum size effects, quantum coherence, Rashba and Dresselhaus spin-orbit interactions and noncollinear magnetizations. It is found that the tunnel barrier plays a decisive role in the transmission coefficient and shot noise of the ballistic spin electron transport through the heterojunction. When the small tunnel barriers are considered, the transport properties of electrons are quite different from those without tunnel barriers

[Do organizational barriers to pneumococcal and influenza vaccine access exist?].

Science.gov (United States)

Rousseau, Louise; Guay, Maryse; Archambault, Denis; El m'ala, Zahra; Abdelaziz, Nadia

2007-01-01

Despite the implementation of a Quebec immunization program against influenza and pneumococcal disease (PQIIP), vaccine coverage has remained low. There have been many studies on personal barriers to vaccination, but few have explored other kinds of barriers. To explore the presence of barriers in relation to the organization of the health care system and to propose recommendations for increasing vaccine coverage. Within a mixed protocol, a phone survey of 996 people in the target population and a case study implicating the follow-up of the PQIIP with all the site and actor categories via 43 semistructured interviews and 4 focus groups were realized. Survey data underwent a descriptive statistical analysis. Qualitative analysis followed the Miles and Huberman approach. The results indicate the presence of barriers with regard to information accessibility. These include access to: the physicians' recommendation, knowledge of the efficacy or the security of vaccines, and admissibility of clients to the PQIIP. Organizational barriers were also found to limit access to vaccination, especially in terms of restricted choices of time and location. Coordination and incentives mechanisms are not optimal. Removal of organizational barriers depends more on strategic rather than structural factors. Addressing organizational barriers should be an important component of strategies aimed at improving vaccine coverage. Public health authorities should focus on strategic management of the information and inter-organizational environment.

Bluff Body Flow Control Using Dielectric Barrier Discharge Plasma Actuators

Science.gov (United States)

Thomas, Flint; Kozlov, Alexey

2008-11-01

The results of an experimental investigation involving the use of dielectric barrier discharge plasma actuators to control bluff body flow is presented. The motivation for the work is plasma landing gear noise control for commercial transport aircraft. For these flow control experiments, the cylinder in cross-flow is chosen for study since it represents a generic flow geometry that is similar in all essential aspects to a landing gear strut. The current work is aimed both at extending the plasma flow control concept to Reynolds numbers typical of landing approach and take-off and on the development of optimum plasma actuation strategies. The cylinder wake flow with and without actuation are documented in detail using particle image velocimetry (PIV) and constant temperature hot-wire anemometry. The experiments are performed over a Reynolds number range extending to ReD=10^5. Using either steady or unsteady plasma actuation, it is demonstrated that even at the highest Reynolds number Karman shedding is totally eliminated and turbulence levels in the wake decrease by more than 50%. By minimizing the unsteady flow separation from the cylinder and associated large-scale wake vorticity, the radiated aerodynamic noise is also reduced.

Surface-structure dependence of healing radiation-damage mechanism in nanoporous tungsten

Science.gov (United States)

Duan, Guohua; Li, Xiangyan; Sun, Jingjing; Hao, Congyu; Xu, Yichun; Zhang, Yange; Liu, Wei; Liu, C. S.

2018-01-01

Under nuclear fusion environments, displacement damage in tungsten (W) is usually caused by neutrons irradiation through producing large quantities of vacancies (Vs) and self-interstitial atoms (SIAs). These defects not only affect the mechanical properties of W, but also act as the trap sites for implanted hydrogen isotopes and helium. Nano-porous (NP) W with a high fraction of free surfaces has been developed to mitigate the radiation damage. However, the mechanism of the surface reducing defects accumulation is not well understood. By using multi-scale simulation methods, we investigated the interaction of the SIA and V with different surfaces on across length and time scales. We found that, at a typical operation temperature of 1000 K, surface (1 1 0) preferentially heals radiation damage of W compared with surface (1 0 0) and boundary (3 1 0). On surface (1 1 0), the diffusion barrier for the SIA is only 0.68 eV. The annihilation of the SIA-V happens via the coupled motion of the V segregation towards the surface from the bulk and the two-dimensional diffusion of the SIA on the surface. Such mechanism makes the surface (1 1 0) owe better healing capability. On surface (1 0 0), the diffusion energy barrier for the SIA is 2.48 eV, higher than the diffusion energy barrier of the V in bulk. The annihilation of the SIA-V occurs via the V segregation and recombination. The SIA was found to migrate one-dimensionally along a boundary (3 1 0) with a barrier of 0.21 eV, leading to a lower healing efficiency in the boundary. This study suggested that the on-surface process plays an important role in healing radiation damage of NP W in addition to surface-enhanced diffusion and annihilation near the surface. A certain surface structure renders nano-structured W more radiation-tolerant.

Multidisciplinary approach of early breast cancer: The biology applied to radiation oncology

International Nuclear Information System (INIS)

Bourgier, Céline; Ozsahin, Mahmut; Azria, David

2010-01-01

Early breast cancer treatment is based on a multimodality approach with the application of clinical and histological prognostic factors to determine locoregional and systemic treatments. The entire scientific community is strongly involved in the management of this disease: radiologists for screening and early diagnosis, gynecologists, surgical oncologists and radiation oncologists for locoregional treatment, pathologists and biologists for personalized characterization, genetic counselors for BRCA mutation history and medical oncologists for systemic therapies. Recently, new biological tools have established various prognostic subsets of breast cancer and developed predictive markers for miscellaneous treatments. The aim of this article is to highlight the contribution of biological tools in the locoregional management of early breast cancer

Barriers to fusion

International Nuclear Information System (INIS)

Berriman, A.C.; Butt, R.D.; Dasgupta, M.; Hinde, D.J.; Morton, C.R.; Newton, J.O.

1999-01-01

The fusion barrier is formed by the combination of the repulsive Coulomb and attractive nuclear forces. Recent research at the Australian National University has shown that when heavy nuclei collide, instead of a single fusion barrier, there is a set of fusion barriers. These arise due to intrinsic properties of the interacting nuclei such deformation, rotations and vibrations. Thus the range of barrier energies depends on the properties of both nuclei. The transfer of matter between nuclei, forming a neck, can also affect the fusion process. High precision data have been used to determine fusion barrier distributions for many nuclear reactions, leading to new insights into the fusion process

Extremal surface barriers

International Nuclear Information System (INIS)

Engelhardt, Netta; Wall, Aron C.

2014-01-01

We present a generic condition for Lorentzian manifolds to have a barrier that limits the reach of boundary-anchored extremal surfaces of arbitrary dimension. We show that any surface with nonpositive extrinsic curvature is a barrier, in the sense that extremal surfaces cannot be continuously deformed past it. Furthermore, the outermost barrier surface has nonnegative extrinsic curvature. Under certain conditions, we show that the existence of trapped surfaces implies a barrier, and conversely. In the context of AdS/CFT, these barriers imply that it is impossible to reconstruct the entire bulk using extremal surfaces. We comment on the implications for the firewall controversy

Overcoming Barriers in Unhealthy Settings

Directory of Open Access Journals (Sweden)

Michael K. Lemke

2016-03-01

Full Text Available We investigated the phenomenon of sustained health-supportive behaviors among long-haul commercial truck drivers, who belong to an occupational segment with extreme health disparities. With a focus on setting-level factors, this study sought to discover ways in which individuals exhibit resiliency while immersed in endemically obesogenic environments, as well as understand setting-level barriers to engaging in health-supportive behaviors. Using a transcendental phenomenological research design, 12 long-haul truck drivers who met screening criteria were selected using purposeful maximum sampling. Seven broad themes were identified: access to health resources, barriers to health behaviors, recommended alternative settings, constituents of health behavior, motivation for health behaviors, attitude toward health behaviors, and trucking culture. We suggest applying ecological theories of health behavior and settings approaches to improve driver health. We also propose the Integrative and Dynamic Healthy Commercial Driving (IDHCD paradigm, grounded in complexity science, as a new theoretical framework for improving driver health outcomes.

Na+/K+-ATPase α1 identified as an abundant protein in the blood-labyrinth barrier that plays an essential role in the barrier integrity.

Directory of Open Access Journals (Sweden)

Yue Yang

2011-01-01

Full Text Available The endothelial-blood/tissue barrier is critical for maintaining tissue homeostasis. The ear harbors a unique endothelial-blood/tissue barrier which we term "blood-labyrinth-barrier". This barrier is critical for maintaining inner ear homeostasis. Disruption of the blood-labyrinth-barrier is closely associated with a number of hearing disorders. Many proteins of the blood-brain-barrier and blood-retinal-barrier have been identified, leading to significant advances in understanding their tissue specific functions. In contrast, capillaries in the ear are small in volume and anatomically complex. This presents a challenge for protein analysis studies, which has resulted in limited knowledge of the molecular and functional components of the blood-labyrinth-barrier. In this study, we developed a novel method for isolation of the stria vascularis capillary from CBA/CaJ mouse cochlea and provided the first database of protein components in the blood-labyrinth barrier as well as evidence that the interaction of Na(+/K(+-ATPase α1 (ATP1A1 with protein kinase C eta (PKCη and occludin is one of the mechanisms of loud sound-induced vascular permeability increase.Using a mass-spectrometry, shotgun-proteomics approach combined with a novel "sandwich-dissociation" method, more than 600 proteins from isolated stria vascularis capillaries were identified from adult CBA/CaJ mouse cochlea. The ion transporter ATP1A1 was the most abundant protein in the blood-labyrinth barrier. Pharmacological inhibition of ATP1A1 activity resulted in hyperphosphorylation of tight junction proteins such as occludin which increased the blood-labyrinth-barrier permeability. PKCη directly interacted with ATP1A1 and was an essential mediator of ATP1A1-initiated occludin phosphorylation. Moreover, this identified signaling pathway was involved in the breakdown of the blood-labyrinth-barrier resulting from loud sound trauma.The results presented here provide a novel method for

Multi-scale approach to radiation damage induced by ion beams: complex DNA damage and effects of thermal spikes

International Nuclear Information System (INIS)

Surdutovich, E.; Yakubovich, A.V.; Solov'yov, A.V.; Surdutovich, E.; Yakubovich, A.V.; Solov'yov, A.V.

2010-01-01

We present the latest advances of the multi-scale approach to radiation damage caused by irradiation of a tissue with energetic ions and report the calculations of complex DNA damage and the effects of thermal spikes on biomolecules. The multi-scale approach aims to quantify the most important physical, chemical, and biological phenomena taking place during and following irradiation with ions and provide a better means for clinically-necessary calculations with adequate accuracy. We suggest a way of quantifying the complex clustered damage, one of the most important features of the radiation damage caused by ions. This quantification allows the studying of how the clusterization of DNA lesions affects the lethality of damage. We discuss the first results of molecular dynamics simulations of ubiquitin in the environment of thermal spikes, predicted to occur in tissue for a short time after an ion's passage in the vicinity of the ions' tracks. (authors)

Simulation of dose deposition in stereotactic synchrotron radiation therapy: a fast approach combining Monte Carlo and deterministic algorithms

Energy Technology Data Exchange (ETDEWEB)

Smekens, F; Freud, N; Letang, J M; Babot, D [CNDRI (Nondestructive Testing using Ionizing Radiations) Laboratory, INSA-Lyon, 69621 Villeurbanne Cedex (France); Adam, J-F; Elleaume, H; Esteve, F [INSERM U-836, Equipe 6 ' Rayonnement Synchrotron et Recherche Medicale' , Institut des Neurosciences de Grenoble (France); Ferrero, C; Bravin, A [European Synchrotron Radiation Facility, Grenoble (France)], E-mail: francois.smekens@insa-lyon.fr

2009-08-07

A hybrid approach, combining deterministic and Monte Carlo (MC) calculations, is proposed to compute the distribution of dose deposited during stereotactic synchrotron radiation therapy treatment. The proposed approach divides the computation into two parts: (i) the dose deposited by primary radiation (coming directly from the incident x-ray beam) is calculated in a deterministic way using ray casting techniques and energy-absorption coefficient tables and (ii) the dose deposited by secondary radiation (Rayleigh and Compton scattering, fluorescence) is computed using a hybrid algorithm combining MC and deterministic calculations. In the MC part, a small number of particle histories are simulated. Every time a scattering or fluorescence event takes place, a splitting mechanism is applied, so that multiple secondary photons are generated with a reduced weight. The secondary events are further processed in a deterministic way, using ray casting techniques. The whole simulation, carried out within the framework of the Monte Carlo code Geant4, is shown to converge towards the same results as the full MC simulation. The speed of convergence is found to depend notably on the splitting multiplicity, which can easily be optimized. To assess the performance of the proposed algorithm, we compare it to state-of-the-art MC simulations, accelerated by the track length estimator technique (TLE), considering a clinically realistic test case. It is found that the hybrid approach is significantly faster than the MC/TLE method. The gain in speed in a test case was about 25 for a constant precision. Therefore, this method appears to be suitable for treatment planning applications.

Self-reported barriers to medication adherence among chronically ill adolescents

DEFF Research Database (Denmark)

Hanghøj, Signe; Boisen, Kirsten A

2014-01-01

's views. Data was analyzed using a thematic synthesis approach. RESULTS: Of 3,655 records 28 articles with both quantitative, qualitative, and q-methodology study designs were included in the review. The synthesis led to the following key themes: Relations, adolescent development, health and illness......, forgetfulness, organization, medicine complexity, and financial costs. Most reported barriers to adherence were not unique to specific diseases. CONCLUSION: Some barriers seem to be specific to adolescence; for example, relations to parents and peers and adolescent development. Knowledge and assessment...

Perceptions of advantages and barriers to radial-access percutaneous coronary intervention in VA cardiac catheterization laboratories

International Nuclear Information System (INIS)

Helfrich, Christian D.; Tsai, Thomas T.; Rao, Sunil V.; Lemon, Jaclyn M.; Eugenio, Evercita C.; Vidovich, Mladen I.; Shroff, Adhir R.; Speiser, Bernadette S.; Bryson, Chris L.

2014-01-01

Background/Purpose: Compared with trans-femoral percutaneous coronary intervention (TFI), trans-radial PCI (TRI) has a lower risk of bleeding, access site complications and hospital costs, and is preferred by patients. However, TRI accounts for a minority of PCIs in the US, and there is currently little research that explores why. Methods/Material: We conducted a national survey in February 2013 to assess perceptions of TRI vs. TFI, and barriers to TRI adoption and implementation among interventional cardiologists employed by the US Veterans Health Administration (VHA), and linked these data to site-level TRI annual rates for 2013. Results: We received 78 completed surveys (32% response rate). Respondents at sites that perform few or no TRIs identified increased radiation exposure as the greatest barrier while at sites that perform a high percentage of TRIs respondents identified the steep learning curve as the greatest barrier. Majorities of survey respondents at all sites rated TRI as superior on 5 of 7 criteria, including patient comfort and bleeding complications, but rated TFI as superior on procedure time and procedure success. Conclusions: Even interventional cardiologists at sites that perform few or any TRIs recognized the superiority of TRI for patient comfort and safety, but rated it inferior to TFI on procedure time and technical results. Interventional cardiologists at high-TRI labs rated TRI as equivalent on procedure time and technical results. Efforts to increase TRI adoption and implementation may be more successful if they emphasize that procedure times and technical results depend on achieving proficiency. - Highlights: • Sites with few TRIs identified increased radiation exposure as the greatest barrier. • Sites with many TRIs identified the steep learning curve as the greatest barrier. • TFI was rated superior on procedure time and procedure success. • TRI was rated superior on all other criteria

Perceptions of advantages and barriers to radial-access percutaneous coronary intervention in VA cardiac catheterization laboratories

Energy Technology Data Exchange (ETDEWEB)

Helfrich, Christian D., E-mail: Christian.Helfrich@va.gov [VA Puget Sound Health Services Research and Development Center of Innovation, US Department of Veterans Affairs, Seattle, WA (United States); Department of Health Services, University of Washington School of Public Health, Seattle, WA (United States); Tsai, Thomas T. [VA Eastern Colorado Health Care System, Denver, CO (United States); Department of Medicine and the Division of Cardiology, University of Colorado School of Medicine, Aurora, CO (United States); Rao, Sunil V. [Cardiac Catheterization Laboratories, Durham VA Medical Center, Durham, NC (United States); Duke Clinical Research Institute, Durham, NC (United States); Lemon, Jaclyn M.; Eugenio, Evercita C. [VA Puget Sound Health Services Research and Development Center of Innovation, US Department of Veterans Affairs, Seattle, WA (United States); Vidovich, Mladen I.; Shroff, Adhir R. [Department of Cardiology, Jesse Brown VA Medical Center, Chicago, IL (United States); Department of Internal Medicine, Section of Interventional Cardiology, University of Illinois at Chicago, Chicago, IL (United States); Speiser, Bernadette S. [Department of Cardiology, Jesse Brown VA Medical Center, Chicago, IL (United States); Bryson, Chris L. [VA Puget Sound Health Services Research and Development Center of Innovation, US Department of Veterans Affairs, Seattle, WA (United States); Division of General Internal Medicine, Department of Medicine, University of Washington, Seattle, WA (United States)

2014-09-15

Background/Purpose: Compared with trans-femoral percutaneous coronary intervention (TFI), trans-radial PCI (TRI) has a lower risk of bleeding, access site complications and hospital costs, and is preferred by patients. However, TRI accounts for a minority of PCIs in the US, and there is currently little research that explores why. Methods/Material: We conducted a national survey in February 2013 to assess perceptions of TRI vs. TFI, and barriers to TRI adoption and implementation among interventional cardiologists employed by the US Veterans Health Administration (VHA), and linked these data to site-level TRI annual rates for 2013. Results: We received 78 completed surveys (32% response rate). Respondents at sites that perform few or no TRIs identified increased radiation exposure as the greatest barrier while at sites that perform a high percentage of TRIs respondents identified the steep learning curve as the greatest barrier. Majorities of survey respondents at all sites rated TRI as superior on 5 of 7 criteria, including patient comfort and bleeding complications, but rated TFI as superior on procedure time and procedure success. Conclusions: Even interventional cardiologists at sites that perform few or any TRIs recognized the superiority of TRI for patient comfort and safety, but rated it inferior to TFI on procedure time and technical results. Interventional cardiologists at high-TRI labs rated TRI as equivalent on procedure time and technical results. Efforts to increase TRI adoption and implementation may be more successful if they emphasize that procedure times and technical results depend on achieving proficiency. - Highlights: • Sites with few TRIs identified increased radiation exposure as the greatest barrier. • Sites with many TRIs identified the steep learning curve as the greatest barrier. • TFI was rated superior on procedure time and procedure success. • TRI was rated superior on all other criteria.

Multilayer moisture barrier

Science.gov (United States)

Pankow, Joel W; Jorgensen, Gary J; Terwilliger, Kent M; Glick, Stephen H; Isomaki, Nora; Harkonen, Kari; Turkulainen, Tommy

2015-04-21

A moisture barrier, device or product having a moisture barrier or a method of fabricating a moisture barrier having at least a polymer layer, and interfacial layer, and a barrier layer. The polymer layer may be fabricated from any suitable polymer including, but not limited to, fluoropolymers such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), or ethylene-tetrafluoroethylene (ETFE). The interfacial layer may be formed by atomic layer deposition (ALD). In embodiments featuring an ALD interfacial layer, the deposited interfacial substance may be, but is not limited to, Al.sub.2O.sub.3, AlSiO.sub.x, TiO.sub.2, and an Al.sub.2O.sub.3/TiO.sub.2 laminate. The barrier layer associated with the interfacial layer may be deposited by plasma enhanced chemical vapor deposition (PECVD). The barrier layer may be a SiO.sub.xN.sub.y film.

Research program to study the gamma radiation effects in Spanish bentonites

International Nuclear Information System (INIS)

Dies, J.; Tarrasa, F.; Cuevas de las, C.; Miralles, L.; Pueyo, J. J.

2000-01-01

The engineering barrier of a radioactive waste underground disposal facility, placed in a granitic host rock, will consist of a backfill of compacted bentonite blocks. At first, this material will be subjected to a gamma radiation field, from the waste canister, and heat from the spent fuel inside the canister. Moreover, any groundwater that reaches the repository will saturate the bentonite. For these reasons the performance of the engineered barrier must be carefully assessed in laboratory experiments. (Author)

Leadership as a predictor of stigma and practical barriers toward receiving mental health treatment: a multilevel approach.

Science.gov (United States)

Britt, Thomas W; Wright, Kathleen M; Moore, Dewayne

2012-02-01

The present research examined positive and negative leadership behaviors as predictors of stigma and practical barriers to mental health treatment. Soldiers completed measures of noncommissioned officer (NCO) and officer leadership, stigma, and practical barriers to getting mental health treatment at 2, 3, and 4 months following a 15-month deployment to Afghanistan. The results revealed that positive and negative NCO and officer leader behaviors were predictive of overall stigma and barriers to care (collapsed across the three time periods), with only NCO positive and negative behaviors being uniquely predictive of stigma when included in the same model with officer behaviors. In addition, negative and positive NCO leader behaviors were predictive of stigma within participants over the course of the three month time period, and positive NCO leader behaviors were inversely related to practical barriers to mental health treatment within participants across the same time period. The results are discussed in terms of how different leader behaviors may be linked to different factors influencing a soldier's decision to seek mental health treatment.

Overcoming Barriers to Successfully Commercializing Carbon Dioxide Utilization

International Nuclear Information System (INIS)

Kant, Marvin

2017-01-01

The successful transition to a low-carbon economy hinges on innovative solutions and collaborative action on a global scale. Sustainable entrepreneurship is thereby recognized as a key driver in the creation and transformation of ecologically and socially sustainable economic systems. The purpose of this article is to contribute to this topic by understanding commercialization barriers for strong sustainability-oriented new technology ventures and to derive recommendations to overcome them. A qualitative multilevel approach is applied to identify barriers and drivers within the internal dynamic capabilities of the organization and within the organization’s external stakeholders. A model of barriers has been developed based on semi-structured interviews with new carbon dioxide utilization ventures and associated industry players in Canada, the USA, and the European Economic Area. Resulting recommendations to facilitate the (re-)design of a dedicated support system are proposed on four levels: (a) actors, (b) resources, (c) institutional settings, and (d) the coordination of the support system.

Overcoming Barriers to Successfully Commercializing Carbon Dioxide Utilization

Energy Technology Data Exchange (ETDEWEB)

Kant, Marvin, E-mail: marvin.kant@tu-berlin.de [Department of Entrepreneurship and Innovation Management, Technische Universität Berlin, Berlin (Germany)

2017-09-13

The successful transition to a low-carbon economy hinges on innovative solutions and collaborative action on a global scale. Sustainable entrepreneurship is thereby recognized as a key driver in the creation and transformation of ecologically and socially sustainable economic systems. The purpose of this article is to contribute to this topic by understanding commercialization barriers for strong sustainability-oriented new technology ventures and to derive recommendations to overcome them. A qualitative multilevel approach is applied to identify barriers and drivers within the internal dynamic capabilities of the organization and within the organization’s external stakeholders. A model of barriers has been developed based on semi-structured interviews with new carbon dioxide utilization ventures and associated industry players in Canada, the USA, and the European Economic Area. Resulting recommendations to facilitate the (re-)design of a dedicated support system are proposed on four levels: (a) actors, (b) resources, (c) institutional settings, and (d) the coordination of the support system.

Overcoming Barriers to Successfully Commercializing Carbon Dioxide Utilization

Directory of Open Access Journals (Sweden)

Marvin Kant

2017-09-01

Full Text Available The successful transition to a low-carbon economy hinges on innovative solutions and collaborative action on a global scale. Sustainable entrepreneurship is thereby recognized as a key driver in the creation and transformation of ecologically and socially sustainable economic systems. The purpose of this article is to contribute to this topic by understanding commercialization barriers for strong sustainability-oriented new technology ventures and to derive recommendations to overcome them. A qualitative multilevel approach is applied to identify barriers and drivers within the internal dynamic capabilities of the organization and within the organization’s external stakeholders. A model of barriers has been developed based on semi-structured interviews with new carbon dioxide utilization ventures and associated industry players in Canada, the USA, and the European Economic Area. Resulting recommendations to facilitate the (re-design of a dedicated support system are proposed on four levels: (a actors, (b resources, (c institutional settings, and (d the coordination of the support system.

New research opportunities for roadside safety barriers improvement

Science.gov (United States)

Cantisani, Giuseppe; Di Mascio, Paola; Polidori, Carlo

2017-09-01

Among the major topics regarding the protection of roads, restraint systems still represent a big opportunity in order to increase safety performances. When accidents happen, in fact, the infrastructure can substantially contribute to the reduction of consequences if its marginal spaces are well designed and/or effective restraint systems are installed there. Nevertheless, basic concepts and technology of road safety barriers have not significantly changed for the last two decades. The paper proposes a new approach to the study aimed to define possible enhancements of restraint safety systems performances, by using new materials and defining innovative design principles. In particular, roadside systems can be developed with regard to vehicle-barrier interaction, vehicle-oriented design (included low-mass and extremely low-mass vehicles), traffic suitability, user protection, working width reduction. In addition, thanks to sensors embedded into the barriers, it is also expected to deal with new challenges related to the guidance of automatic vehicles and I2V communication.

Magnetization reversal processes of single nanomagnets and their energy barrier

International Nuclear Information System (INIS)

Krone, P.; Makarov, D.; Albrecht, M.; Schrefl, T.; Suess, D.

2010-01-01

Micromagnetic simulations were performed to investigate the influence of geometry and magnetic anisotropy constant on energy barrier and magnetization reversal mechanism of individual bits important for the bit patterned media concept in magnetic data storage. It is shown that dependency of the energy barrier on magnetic and geometric properties of bits can be described by an analytical approach in the case of quasi-coherent magnetization rotation process. However, when the bit size exceeds a critical size, for which an incoherent magnetization reversal is preferred, the analytical approach becomes invalid and no self-consistent theory is available. By systematically investigating the influence of bit size on the magnetization reversal mode, it was found that the transition from quasi-coherent to incoherent magnetization reversal mode can still be described analytically if an activation volume is considered instead of the bit volume. In this case, the nucleation volume is an important parameter determining thermal stability of the bit. If the volume of the bit is larger than twice the activation volume, the energy barrier stays nearly constant; with further increase in bit size, no gain in thermal stability can be achieved.

Understanding barriers to implementation of an adaptive land management program

Science.gov (United States)

Jacobson, S.K.; Morris, J.K.; Sanders, J.S.; Wiley, E.N.; Brooks, M.; Bennetts, R.E.; Percival, H.F.; Marynowski, S.

2006-01-01

The Florida Fish and Wildlife Conservation Commission manages over 650,000 ha, including 26 wildlife management and environmental areas. To improve management, they developed an objective-based vegetation management (OBVM) process that focuses on desired conditions of plant communities through an adaptive management framework. Our goals were to understand potential barriers to implementing OBVM and to recommend strategies to overcome barriers. A literature review identified 47 potential barriers in six categories to implementation of adaptive and ecosystem management: logistical, communication, attitudinal, institutional, conceptual, and educational. We explored these barriers through a bureau-wide survey of 90 staff involved in OBVM and personal interviews with area managers, scientists, and administrators. The survey incorporated an organizational culture assessment instrument to gauge how institutional factors might influence OBVM implementation. The survey response rate was 69%. Logistics and communications were the greatest barriers to implementing OBVM. Respondents perceived that the agency had inadequate resources for implementing OBVM and provided inadequate information. About one-third of the respondents believed OBVM would decrease their job flexibility and perceived greater institutional barriers to the approach. The 43% of respondents who believed they would have more responsibility under OBVM also had greater attitudinal barriers. A similar percentage of respondents reported OBVM would not give enough priority to wildlife. Staff believed that current agency culture was hierarchical but preferred a culture that would provide more flexibility for adaptive management and would foster learning from land management activities. In light of the barriers to OBVM, we recommend the following: (1) mitigation of logistical barriers by addressing real and perceived constraints of staff, funds, and other resources in a participatory manner; (2) mitigation of

THERMAL PROPERTIES OF TRANSPARENT BARRIER MODIFIED WITH ORGANIC PCMS

Directory of Open Access Journals (Sweden)

Michał MUSIAŁ

2016-03-01

Full Text Available Renewable energy sources are increasingly often applied in civil engineering as a mean to reduce buildings energy demand for heating. One of the ways to reduce HVAC energy demand is to limit heat transfer and excessive solar gain through building's glazed barriers. Preliminary results of the research conducted on organic PCM-modified transparent barrier are presented in this paper. Multiple publications concerning PCMs application in structural materials have recently appeared. Most of them are focused on modification of structure of non-transparent sections of buildings' envelope. Augmenting a glazed barrier with PCMs increases its heat capacity and thermal resistance. The most important feature of the assembly is the thermal buffer, a product of PCM's considerable value of specific latent heat. Research were conducted on a triple-pane transparent rectangular barrier, that constituted one of the faces of cubic chamber. Internal volume of the chamber was 1m3. The applied PCM was a mixture of saturated and non-saturated hydrocarbons. The described assembly was subjected to temperature and radiation that occur in Poland during winter. Glazing temperature, melted/total PCM ratio were measured, as well as energy demand for keeping internal temperature at constant level. Measurements were made in steady states, for various PCM layer thickness. The influence of the modification on energy demand was determined, along with the most effective and rational thickness of PCM layer to be applied. Conducted research enabled to develop a basis for further investigation of PCMs application in civil engineering.

Overcoming energy efficiency barriers through systems approach—A conceptual framework

International Nuclear Information System (INIS)

Chai, Kah-Hin; Yeo, Catrina

2012-01-01

In this paper we propose a framework which categorizes energy efficiency barriers based on the stage at which the barriers exist. Barriers to energy efficiency have been widely studied but to our knowledge, except for a few studies, we found inadequate consideration for barrier–barrier interactions when proposing policy measures for improving energy efficiency. Leveraging systems thinking's power as a problem solver which identifies underlying structure that explains (similar) patterns of behavior in a variety of different situations, we attempted to identify patterns of barriers to adoption of energy efficiency measures in industrial companies. Inspired by systems thinking, the proposed framework has four stages, namely, Motivation, Capability, Implementation and Results, as well as a feedback loop. Using a case study, we show that following the four stages will lead to positive feedback for future energy efficiency implementations. The framework highlights the interconnected nature of the barriers and a need for policymakers to address these barriers in a holistic manner. We argue that the overall effectiveness of energy efficiency policies is only as strong as the weakest link in the four-stage framework. This differs from most prior research that addressed barriers in isolation, where a solution is proposed for each of the barriers without considering the relationship between the barriers. Our framework also offers a way to understand the roles and responsibilities of major stakeholders such as governments and energy service companies (ESCOs) in driving energy efficiency. This allows the assessment and identification of weak links in energy efficiency policies. - Highlights: ► We propose a systems approach to overcome energy efficiency barriers. ► Barriers are grouped into Motivation, Capability, Implementation and Results. ► Case study shows that there is a feedback loop from Results to Motivation. ► Current Results will affect future Motivation. �

Radiation-resistant photostructure for Schottky diode based on Cr/In2Hg3Te6

Directory of Open Access Journals (Sweden)

Ashcheulov A. A.

2016-05-01

Full Text Available Ge, Si, InGaAs, GaInAsP photodiodes are used as optical radiation receivers and function in a spectral range of transparency of quartz fiberglass. For the optical systems operated in the increased radioactivity the photodetectors' application on In2Hg3Te6 crystal base characterized by a photosensitivity in the spectral range of 0,5-1,6 mm and also by increased radiation resistance to alpha, beta and gamma radiation is most acceptable. Schottky photodiode structure was designed on the base of this semiconductor formed by a modified floating zone recrystallization technique where the sedimentation effect was leveled. It consists of n-In2Hg3Te6 substrate and deposited by cathode sputtering Cr barrier layer of thickness within a range 10-11 nm choice of Cr is determined by its optimal optical, electric and adhesive features in high quality radiation-resistant photodiode structures manufacturing. Indium and nichrome are used as ohmic contacts. The barrier structures have the contact area of 1,13 mm2 with photo response of 0,6-1,6 mm at the maximal sensitivity 0,43 A/W on the wavelength l,55 mm. Reverse dark current of these structures do not exceed 4 mA at the bias of 1 V (T=295 K, and the potential barrier height is equal to 0,41 eV. The tests of radiation resistance of these structures demonstrated their ability to function at doses of 2⋅108 rem without evident parameters changes. This allows using them in practical aims in the conditions of high radiation.

Randomized comparison of operator radiation exposure comparing transradial and transfemoral approach for percutaneous coronary procedures: rationale and design of the minimizing adverse haemorrhagic events by TRansradial access site and systemic implementation of angioX - RAdiation Dose study (RAD-MATRIX).

Science.gov (United States)

Sciahbasi, Alessandro; Calabrò, Paolo; Sarandrea, Alessandro; Rigattieri, Stefano; Tomassini, Francesco; Sardella, Gennaro; Zavalloni, Dennis; Cortese, Bernardo; Limbruno, Ugo; Tebaldi, Matteo; Gagnor, Andrea; Rubartelli, Paolo; Zingarelli, Antonio; Valgimigli, Marco

2014-06-01

Radiation absorbed by interventional cardiologists is a frequently under-evaluated important issue. Aim is to compare radiation dose absorbed by interventional cardiologists during percutaneous coronary procedures for acute coronary syndromes comparing transradial and transfemoral access. The randomized multicentre MATRIX (Minimizing Adverse Haemorrhagic Events by TRansradial Access Site and Systemic Implementation of angioX) trial has been designed to compare the clinical outcome of patients with acute coronary syndromes treated invasively according to the access site (transfemoral vs. transradial) and to the anticoagulant therapy (bivalirudin vs. heparin). Selected experienced interventional cardiologists involved in this study have been equipped with dedicated thermoluminescent dosimeters to evaluate the radiation dose absorbed during transfemoral or right transradial or left transradial access. For each access we evaluate the radiation dose absorbed at wrist, at thorax and at eye level. Consequently the operator is equipped with three sets (transfemoral, right transradial or left transradial access) of three different dosimeters (wrist, thorax and eye dosimeter). Primary end-point of the study is the procedural radiation dose absorbed by operators at thorax. An important secondary end-point is the procedural radiation dose absorbed by operators comparing the right or left radial approach. Patient randomization is performed according to the MATRIX protocol for the femoral or radial approach. A further randomization for the radial approach is performed to compare right and left transradial access. The RAD-MATRIX study will probably consent to clarify the radiation issue for interventional cardiologist comparing transradial and transfemoral access in the setting of acute coronary syndromes. Copyright © 2014 Elsevier Inc. All rights reserved.

Development of a residency program in radiation oncology physics: an inverse planning approach.

Science.gov (United States)

Khan, Rao F H; Dunscombe, Peter B

2016-03-08

Over the last two decades, there has been a concerted effort in North America to organize medical physicists' clinical training programs along more structured and formal lines. This effort has been prompted by the Commission on Accreditation of Medical Physics Education Programs (CAMPEP) which has now accredited about 90 residency programs. Initially the accreditation focused on standardized and higher quality clinical physics training; the development of rounded professionals who can function at a high level in a multidisciplinary environment was recognized as a priority of a radiation oncology physics residency only lately. In this report, we identify and discuss the implementation of, and the essential components of, a radiation oncology physics residency designed to produce knowledgeable and effective clinical physicists for today's safety-conscious and collaborative work environment. Our approach is that of inverse planning, by now familiar to all radiation oncology physicists, in which objectives and constraints are identified prior to the design of the program. Our inverse planning objectives not only include those associated with traditional residencies (i.e., clinical physics knowledge and critical clinical skills), but also encompass those other attributes essential for success in a modern radiation therapy clinic. These attributes include formal training in management skills and leadership, teaching and communication skills, and knowledge of error management techniques and patient safety. The constraints in our optimization exercise are associated with the limited duration of a residency and the training resources available. Without compromising the knowledge and skills needed for clinical tasks, we have successfully applied the model to the University of Calgary's two-year residency program. The program requires 3840 hours of overall commitment from the trainee, of which 7%-10% is spent in obtaining formal training in nontechnical "soft skills".

A theoretical study of resonant tunneling characteristics in triangular double-barrier diodes

International Nuclear Information System (INIS)

Wang Hongmei; Xu Huaizhe; Zhang Yafei

2006-01-01

Resonant tunneling characteristics of triangular double-barrier diodes have been investigated systematically in this Letter, using Airy function approach to solve time-independent Schroedinger function in triangular double-barrier structures. Originally, the exact analytic expressions of quasi-bound levels and quasi-level lifetime in symmetrical triangular double-barrier structures have been derived within the effective-mass approximation as a function of structure parameters including well width, slope width and barrier height. Based on our derived analytic expressions, numerical results show that quasi-bound levels and quasi-level lifetime vary nearly linearly with the structure parameters except that the second quasi-level lifetime changes parabolically with slope width. Furthermore, according to our improved transmission coefficient of triangular double-barrier structures under external electric field, the current densities of triangular double-barrier diodes with different slope width at 0 K have been calculated numerically. The results show that the N-shaped negative differential resistance behaviors have been observed in current-voltage characteristics and current-voltage characteristics depend on the slope width

Barriers and facilitators to end-of-life communication in advanced chronic organ failure.

Science.gov (United States)

Van den Heuvel, Liza Amc; Spruit, Martijn A; Schols, Jos Mga; Hoving, Ciska; Wouters, Emiel Fm; Janssen, Daisy Ja

2016-05-01

The aim of this quantitative, cross-sectional study was to identify barriers and facilitators to end-of-life communication experienced by family caregivers of patients with advanced chronic organ failure and to examine agreement in barriers and facilitators between family caregivers and patients. Patients and family caregivers were interviewed using the barriers and facilitators questionnaire. Agreement was determined using intraclass correlation coefficients for continuous variables and Cohen's kappa for categorical variables. A total of 158 patients and family caregiver dyads were included. The most important barriers for family caregivers were related to uncertainty about expected care and focus on staying alive instead of dying. The facilitators were related to trust in and competence of their physician and earlier experiences with death in their (social) environment. For most barriers and facilitators, agreement between patients and family caregivers was fair to moderate. Differences in barriers and facilitators between patients and family caregivers ask for an individual approach to facilitate end-of-life communication.

Swedish nurses encounter barriers when promoting healthy habits in children.

Science.gov (United States)

Ljungkrona-Falk, Lena; Brekke, Hilde; Nyholm, Maria

2014-12-01

To increase the understanding of difficulties in promoting healthy habits to parents, we explore barriers in health-care provision. The aim of this study is to describe nurses' perceived barriers when discussing with parents regarding healthy food habits, physical activity and their child's body weight. A mixed method approach was chosen. Nurses (n = 76) working at 29 different Child Health Care Centers' in an area in west Sweden were included in the study. Three focus group interviews were conducted and 17 nurses were selected according to maximum variation. Data were categorized and qualitative content analysis was the chosen analysis method. In the second method, data were obtained from a questionnaire distributed to all 76 nurses. The latent content was formulated into a theme: even with encouragement and support, the nurses perceive barriers of both an external and internal nature. The results identified four main barriers: experienced barriers in the workplace-internal and external; the nurse's own fear and uncertainty; perceived obstacles in nurse-parent interactions and modern society impedes parents' ability to promote healthy habits. The nurses' perceived barriers were confirmed by the results from 62 of the nurses who completed the questionnaire. Despite education and professional support, the health professionals perceived both external and internal barriers in promoting healthy habits to parents when implementing a new method of health promotion in primary care. Further qualitative studies are needed to gain deeper understanding of the perceived barriers when promoting healthy habits to parents. © The Author (2013). Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Constructive and critical approach of the radiation damage simulation

International Nuclear Information System (INIS)

Becquart, Ch.

2002-11-01

This work deals with the problem of radiation damage in materials for applications in development of fission and nuclear fusion technologies. It is organised in 3 sections. In section 1 are presented the mechanisms of formation and the evolution kinetics of the primary damage. Section 2 is devoted to the study of the sensitivity of the radiation damage at different approximations. Section 3 discusses the contribution of the ab initio calculations to the study of radiation damage and more particularly the point defects in a dilute Fe-Cu ferritic alloy. This work is illustrated by several publications added in each section. (O.M.)

Barriers of six sigma in healthcare organizations

Directory of Open Access Journals (Sweden)

Serkan Deniz

2018-09-01

Full Text Available Six Sigma approach is based on decreasing defects and variations in the products and processes, and it provides important benefits to healthcare organizations. This study aims to identify managers’ opinions, who work in private healthcare organizations, about the reasons behind not using Six Sigma in their organizations. The research was performed between December 2016 and March 2018 in private healthcare organizations (private hospitals and medical centers operating in Turkey and not using Six Sigma approach. Data were collected from managers, who have knowledge about Six Sigma, through using surveys. In this study, survey methodology was used to collect data. According to the results, the biggest barrier related to not using Six Sigma is based on the lack of knowledge about Six Sigma. The other important barrier about the diffusion of Six Sigma within this organizations is related to the lack of support from top management and leaders. Another finding about the reasons of not applying Six Sigma approach is that there is not a statistically significant difference among managers in terms of their managerial position. In order to overcome the lack of knowledge about Six Sigma, it is advised that managers should take steps in the direction of promoting Six Sigma within their current organization, and provide necessary support and leadership about the process.

Using Baldrige Performance Excellence Program Approaches in the Pursuit of Radiation Oncology Quality Care, Patient Satisfaction, and Workforce Commitment

Energy Technology Data Exchange (ETDEWEB)

Sternick, Edward S., E-mail: esternick@lifespan.org [Department of Radiation Oncology, Rhode Island Hospital/Brown Alpert Medical School, Providence, RI (United States)

2011-06-20

The Malcolm Baldrige National Quality Improvement Act was signed into law in 1987 to advance US business competitiveness and economic growth. Administered by the National Institute of Standards and Technology, the Act created the Baldrige National Quality Program, recently renamed the Baldrige Performance Excellence Program. The comprehensive analytical approaches referred to as the Baldrige Healthcare Criteria, are very well-suited for the evaluation and sustainable improvement of radiation oncology management and operations. A multidisciplinary self-assessment approach is used for radiotherapy program evaluation and development in order to generate a fact-based, knowledge-driven system for improving quality of care, increasing patient satisfaction, enhancing leadership effectiveness, building employee engagement, and boosting organizational innovation. This methodology also provides a valuable framework for benchmarking an individual radiation oncology practice's operations and results against guidelines defined by accreditation and professional organizations and regulatory agencies.

Using Baldrige Performance Excellence Program Approaches in the Pursuit of Radiation Oncology Quality Care, Patient Satisfaction, and Workforce Commitment

International Nuclear Information System (INIS)

Sternick, Edward S.

2011-01-01

The Malcolm Baldrige National Quality Improvement Act was signed into law in 1987 to advance US business competitiveness and economic growth. Administered by the National Institute of Standards and Technology, the Act created the Baldrige National Quality Program, recently renamed the Baldrige Performance Excellence Program. The comprehensive analytical approaches referred to as the Baldrige Healthcare Criteria, are very well-suited for the evaluation and sustainable improvement of radiation oncology management and operations. A multidisciplinary self-assessment approach is used for radiotherapy program evaluation and development in order to generate a fact-based, knowledge-driven system for improving quality of care, increasing patient satisfaction, enhancing leadership effectiveness, building employee engagement, and boosting organizational innovation. This methodology also provides a valuable framework for benchmarking an individual radiation oncology practice's operations and results against guidelines defined by accreditation and professional organizations and regulatory agencies.

Using baldrige performance excellence program approaches in the pursuit of radiation oncology quality care, patient satisfaction, and workforce commitment.

Science.gov (United States)

Sternick, Edward S

2011-01-01

The Malcolm Baldrige National Quality Improvement Act was signed into law in 1987 to advance US business competitiveness and economic growth. Administered by the National Institute of Standards and Technology, the Act created the Baldrige National Quality Program, recently renamed the Baldrige Performance Excellence Program. The comprehensive analytical approaches referred to as the Baldrige Healthcare Criteria, are very well-suited for the evaluation and sustainable improvement of radiation oncology management and operations. A multidisciplinary self-assessment approach is used for radiotherapy program evaluation and development in order to generate a fact-based, knowledge-driven system for improving quality of care, increasing patient satisfaction, enhancing leadership effectiveness, building employee engagement, and boosting organizational innovation. This methodology also provides a valuable framework for benchmarking an individual radiation oncology practice's operations and results against guidelines defined by accreditation and professional organizations and regulatory agencies.

Planar UV excilamp excited by a surface barrier discharge

Energy Technology Data Exchange (ETDEWEB)

Guivan, N N [Department of Quantum Electronics, Uzhgorod National University, Pidgirna 46, Uzhgorod 88000 (Ukraine); Janca, J [Department of Physical Electronics, Masaryk University, Kotlarska 2, Brno 61137 (Czech Republic); Brablec, A [Department of Physical Electronics, Masaryk University, Kotlarska 2, Brno 61137 (Czech Republic); Stahel, P [Department of Physical Electronics, Masaryk University, Kotlarska 2, Brno 61137 (Czech Republic); SlavIcek, P [Department of Physical Electronics, Masaryk University, Kotlarska 2, Brno 61137 (Czech Republic); Shimon, L L [Department of Quantum Electronics, Uzhgorod National University, Pidgirna 46, Uzhgorod 88000 (Ukraine)

2005-09-07

In this paper, the typical characteristics of a planar excilamp based on KrCl* and XeCl* exciplex molecules are presented. The excitation of the working mixture Kr/Xe/Cl{sub 2} is realized by means of the surface barrier discharge at pressures of 0.1-1 bar. The following properties are measured and discussed: spectra emitted by the plasma in the UV/VIS/NIR spectral range, intensity of emitted light versus total pressure in the discharge, the composition of the working mixture and the power of emitted light. The radiation power versus input electric power, and space distribution of the emitted light including basic electrical parameters of the discharge were also measured. It was shown that the characteristic power of UV radiation emitted in the spectral range 200-400 nm is about 6 mW cm{sup -2} while the efficiency could be about 8%.

Technical Barriers, Gaps, and Opportunities Related to Home Energy Upgrade Market Delivery

Energy Technology Data Exchange (ETDEWEB)

Bianchi, M. V. A.

2011-11-01

This report outlines the technical barriers, gaps, and opportunities that arise in executing home energy upgrade market delivery approaches, as identified through research conducted by the U.S. Department of Energy's Building America program. The objective of this report is to outline the technical1 barriers, gaps, and opportunities that arise in executing home energy upgrade market delivery approaches, as identified through research conducted by the U.S. Department of Energy's (DOE) Building America program. This information will be used to provide guidance for new research necessary to enable the success of the approaches. Investigation for this report was conducted via publications related to home energy upgrade market delivery approaches, and a series of interviews with subject matter experts (contractors, consultants, program managers, manufacturers, trade organization representatives, and real estate agents). These experts specified technical barriers and gaps, and offered suggestions for how the technical community might address them. The potential benefits of home energy upgrades are many and varied: reduced energy use and costs; improved comfort, durability, and safety; increased property value; and job creation. Nevertheless, home energy upgrades do not comprise a large part of the overall home improvement market. Residential energy efficiency is the most complex climate intervention option to deliver because the market failures are many and transaction costs are high (Climate Change Capital 2009). The key reasons that energy efficiency investment is not being delivered are: (1) The opportunity is highly fragmented; and (2) The energy efficiency assets are nonstatus, low-visibility investments that are not properly valued. There are significant barriers to mobilizing the investment in home energy upgrades, including the 'hassle factor' (the time and effort required to identify and secure improvement works), access to financing, and the

[Implementation barriers--commentaries from organisational sociology] Implementeringsbarrierer - en organisationssociologisk nuancering

DEFF Research Database (Denmark)

Kousgaard, Marius Brostrøm; Thorsen, T.

2009-01-01

During the last two decades numerous technologies for improving the quality of care have been introduced in the healthcare sector. The various problems encountered by such endeavours have given rise to a large number of studies attempting to identify the most effective techniques for implementation...... and the most important barriers to change. However, the barrier-centred approach to change has not yet fulfilled the expectations of its promoters and has recently come under criticism from research in organisational change. The article explores the contents and implications of this critique Udgivelsesdato...

Symmetric fusion of heavy ions around the Coulomb barrier energy

International Nuclear Information System (INIS)

Royer, G.; Remaud, B.

1983-01-01

Using the liquid drop model, we have performed a systematic study of the symmetric fusion with a neck degree of freedom and tunnelling effects, the nuclear potential being calculated with the proximity approach. Barrier heights and positions are in very good agreement with experimental data when they are known (light-medium systems); the recent experimental data of the reactions 58 Ni + 58 Ni and 64 Ni + 64 Ni are particularly investigated. For heavier systems double-humped fusion barriers and isomeric states are predicted which strongly limit the complete fusion probability

Understanding the barriers to physician error reporting and disclosure: a systemic approach to a systemic problem.

Science.gov (United States)

Perez, Bianca; Knych, Stephen A; Weaver, Sallie J; Liberman, Aaron; Abel, Eileen M; Oetjen, Dawn; Wan, Thomas T H

2014-03-01

The issues of medical errors and medical malpractice have stimulated significant interest in establishing transparency in health care, in other words, ensuring that medical professionals formally report medical errors and disclose related outcomes to patients and families. However, research has amply shown that transparency is not a universal practice among physicians. A review of the literature was carried out using the search terms "transparency," "patient safety," "disclosure," "medical error," "error reporting," "medical malpractice," "doctor-patient relationship," and "physician" to find articles describing physician barriers to transparency. The current literature underscores that a complex Web of factors influence physician reluctance to engage in transparency. Specifically, 4 domains of barriers emerged from this analysis: intrapersonal, interpersonal, institutional, and societal. Transparency initiatives will require vigorous, interdisciplinary efforts to address the systemic and pervasive nature of the problem. Several ethical and social-psychological barriers suggest that medical schools and hospitals should collaborate to establish continuity in education and ensure that knowledge acquired in early education is transferred into long-term learning. At the institutional level, practical and cultural barriers suggest the creation of supportive learning environments and private discussion forums where physicians can seek moral support in the aftermath of an error. To overcome resistance to culture transformation, incremental change should be considered, for example, replacing arcane transparency policies and complex reporting mechanisms with clear, user-friendly guidelines.

A nested case-control approach to interactions between radiation dose and other factors as causes of cancer

Energy Technology Data Exchange (ETDEWEB)

Land, Charles E [Department of Epidemiology, Radiation Epidemiology Branch, US National Cancer Institute, Bethesda, MD (United States)

1992-04-01

Often a nested case-control study is the most practicable approach to estimating the interaction of two cancer risk factors in a large cohort. If one of the factors has already been evaluated for the entire cohort, however, more information is already available about its relationship to risk than could be obtained from a nested study. A modified case-control approach is proposed, in which information about the second, unknown factor is sought for cases and controls matched on the first factor. The approach requires, for interaction models other than the multiplicative, a nonstandard analytical approach incorporating cohort-based information about the first factor. The problem is discussed in the context of breast cancer risk in a defined cohort of female Japanese atomic bomb survivors, in relation to radiation dose and reproductive history. (author)

Ionizing radiation perception by insects

International Nuclear Information System (INIS)

Campanhola, C.

1980-04-01

The proof of the existence of a perception for ionizing radiation by insects was aimed at, as well as the determination of its processing mechanism. It was tried also to check if such perception induces the insects to keep away from the radiation source, proving therefore a protection against the harms caused by ionizing radiation, or else the stimulus for such behaviour is similar to that caused by light radiations. 60 Co and 241 Am were used as gamma radiation sources, the 60 Co source of 0.435mCi and the 241 Am of 99.68mCi activity. Adult insects were used with the following treatments : exposure to 60 Co and 241 Am radiation and non-exposure (control). A total of approximately 50 insects per replication was released in the central region of an opaque white wooden barrier divided into 3 sections with the same area - 60.0 cm diameter and 7.5 cm height - covered with a nylon screen. 5 replications per treatment were made and the distribution of the insects was evaluated by photographs taken at 15, 30, 45, and 60 minutes after release. Sitophilus oryzae (l., 1763) and Ephestia cautella (Walker, 1864) showed some response to 241 Am gamma radiation, i.e. negative tactism. It was concluded that ionizing radiations can be detected by insects through direct visual stimulus or by visual stimulus reslting from interaction of radiation-Cerenkov radiation - with some other occular component with a refraction index greater than water. Also, the activity of the radioactive source with regard to perception for ionizing radiation, is of relevance in comparison with the energy of the radiation emitted by same, or in other words, what really matters is the radiation dose absorbed. (Author) [pt