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Sample records for blood-testis barrier dynamics

  1. Regulation of Blood-Testis Barrier (BTB) Dynamics, Role of Actin-, and Microtubule-Based Cytoskeletons.

    Science.gov (United States)

    Wen, Qing; Tang, Elizabeth I; Li, Nan; Mruk, Dolores D; Lee, Will M; Silvestrini, Bruno; Cheng, C Yan

    2018-01-01

    The blood-testis barrier (BTB) is an important ultrastructure in the testis that supports meiosis and postmeiotic spermatid development since a delay in the establishment of a functional Sertoli cell barrier during postnatal development in rats or mice by 17-20 day postpartum (dpp) would lead to a delay of the first wave of meiosis. Furthermore, irreversible disruption of the BTB by toxicants also induces infertility in rodents. Herein, we summarize recent findings that BTB dynamics (i.e., disassembly, reassembly, and stabilization) are supported by the concerted efforts of the actin- and microtubule (MT)-based cytoskeletons. We focus on the role of two actin nucleation protein complexes, namely, the Arp2/3 (actin-related protein 2/3) complex and formin 1 (or the formin 1/spire 1 complex) known to induce actin nucleation, respectively, by conferring plasticity to actin cytoskeleton. We also focus on the MT plus (+)-end tracking protein (+TIP) EB1 (end-binding protein 1) which is known to confer MT stabilization. Furthermore, we discuss in particular how the interactions of these proteins modulate BTB dynamics during spermatogenesis. These findings also yield a novel hypothetical concept regarding the molecular mechanism that modulates BTB function.

  2. Why testes are resistant to hydatidosis: Is blood-testis-barrier ...

    African Journals Online (AJOL)

    There was demonstrable hydatid cyst (protoscoleces and germinative layer) in testes of five rabbits from Group A, but in one rabbit, both testes were normal. In Group B, three out of four rabbits developed peritoneal hydatidosis. The mechanism of testicular resistance to echinococcosis could be due to blood-testis barrier ...

  3. The Blood Testis Barrier and Male Sexual Dysfunction following Spinal Cord Injury

    Science.gov (United States)

    2015-10-01

    privileged”. Our focus has been on the blood- spinal cord barrier (BSCB) and how trauma collapses this important spinal vascular specialization...AWARD NUMBER: W81XWH-12-1-0481 TITLE: The Blood-Testis Barrier and Male Sexual Dysfunction following Spinal Cord Injury PRINCIPAL INVESTIGATOR...21702-5012 Approved for Public Release; Distribution Unlimited Nearly 70% of males exhibit a profound loss of fertility following spinal cord injury

  4. Regulation of blood-testis barrier assembly in vivo by germ cells.

    Science.gov (United States)

    Li, Xiao-Yu; Zhang, Yan; Wang, Xiu-Xia; Jin, Cheng; Wang, Yu-Qian; Sun, Tie-Cheng; Li, Jian; Tang, Ji-Xin; Batool, Alia; Deng, Shou-Long; Chen, Su-Ren; Cheng, C Yan; Liu, Yi-Xun

    2018-01-03

    The assembly of the blood-testis barrier (BTB) during postnatal development is crucial to support meiosis. However, the role of germ cells in BTB assembly remains unclear. Herein, Kit W /Kit WV mice were used as a study model. These mice were infertile, failing to establish a functional BTB to support meiosis due to c-Kit mutation. Transplantation of undifferentiated spermatogonia derived from normal mice into the testis of Kit W /Kit WV mice triggered functional BTB assembly, displaying cyclic remodeling during the epithelial cycle. Also, transplanted germ cells were capable of inducing Leydig cell testosterone production, which could enhance the expression of integral membrane protein claudin 3 in Sertoli cells. Early spermatocytes were shown to play a vital role in directing BTB assembly by expressing claudin 3, which likely created a transient adhesion structure to mediate BTB and cytoskeleton assembly in adjacent Sertoli cells. In summary, the positive modulation of germ cells on somatic cell function provides useful information regarding somatic-germ cell interactions.-Li, X.-Y., Zhang, Y., Wang, X.-X., Jin, C., Wang, Y.-Q., Sun, T.-C., Li, J., Tang, J.-X., Batool, A., Deng, S.-L., Chen, S.-R., Cheng, C. Y., Liu, Y.-X. Regulation of blood-testis barrier assembly in vivo by germ cells.

  5. Blood-testis barrier and spermatogenesis: lessons from genetically-modified mice

    Directory of Open Access Journals (Sweden)

    Xiao-Hua Jiang

    2014-08-01

    Full Text Available The blood-testis barrier (BTB is found between adjacent Sertoli cells in the testis where it creates a unique microenvironment for the development and maturation of meiotic and postmeiotic germ cells in seminiferous tubes. It is a compound proteinous structure, composed of several types of cell junctions including tight junctions (TJs, adhesion junctions and gap junctions (GJs. Some of the junctional proteins function as structural proteins of BTB and some have regulatory roles. The deletion or functional silencing of genes encoding these proteins may disrupt the BTB, which may cause immunological or other damages to meiotic and postmeiotic cells and ultimately lead to spermatogenic arrest and infertility. In this review, we will summarize the findings on the BTB structure and function from genetically-modified mouse models and discuss the future perspectives.

  6. Zika Virus Infects Human Sertoli Cells and Modulates the Integrity of the In Vitro Blood-Testis Barrier Model.

    Science.gov (United States)

    Siemann, David N; Strange, Daniel P; Maharaj, Payal N; Shi, Pei-Yong; Verma, Saguna

    2017-11-15

    Confirmed reports of Zika virus (ZIKV) in human seminal fluid for months after the clearance of viremia suggest the ability of ZIKV to establish persistent infection in the seminiferous tubules, an immune-privileged site in the testis protected by the blood-testis barrier, also called the Sertoli cell (SC) barrier (SCB). However, cellular targets of ZIKV in human testis and mechanisms by which the virus enters seminiferous tubules remain unclear. We demonstrate that primary human SCs were highly susceptible to ZIKV compared to the closely related dengue virus and induced the expression of alpha interferon (IFN-α), key cytokines, and cell adhesion molecules (vascular cell adhesion molecule 1 [VCAM-1] and intracellular adhesion molecule 1 [ICAM-1]). Furthermore, using an in vitro SCB model, we show that ZIKV was released on the adluminal side of the SCB model with a higher efficiency than in the blood-brain barrier model. ZIKV-infected SCs exhibited enhanced adhesion of leukocytes that correlated with decreases in SCB integrity. ZIKV infection did not affect the expression of tight and adherens junction proteins such as ZO-1, claudin, and JAM-A; however, exposure of SCs to inflammatory mediators derived from ZIKV-infected macrophages led to the degradation of the ZO-1 protein, which correlated with increased SCB permeability. Taken together, our data suggest that infection of SCs may be one of the crucial steps by which ZIKV gains access to the site of spermatozoon development and identify SCs as a therapeutic target to clear testicular infections. The SCB model opens up opportunities to assess interactions of SCs with other testicular cells and to test the ability of anti-ZIKV drugs to cross the barrier. IMPORTANCE Recent outbreaks of ZIKV, a neglected mosquito-borne flavivirus, have identified sexual transmission as a new route of disease spread, which has not been reported for other flaviviruses. To be able to sexually transmit for months after the clearance of

  7. Impaired function of the blood-testis barrier during aging is preceded by a decline in cell adhesion proteins and GTPases.

    Directory of Open Access Journals (Sweden)

    Catriona Paul

    Full Text Available With increasing age comes many changes in the testis, including germ cell loss. Cell junctions in the testis tether both seminiferous epithelial and germ cells together and assist in the formation of the blood-testis barrier (BTB, which limits transport of biomolecules, ions and electrolytes from the basal to the adluminal compartment and protects post-meiotic germ cells. We hypothesize that as male rats age the proteins involved in forming the junctions decrease and that this alters the ability of the BTB to protect the germ cells. Pachytene spermatocytes were isolated from Brown Norway rat testes at 4 (young and 18 (aged months of age using STA-PUT velocity sedimentation technique. RNA was extracted and gene expression was assessed using Affymetrix rat 230 2.0 whole rat genome microarrays. Microarray data were confirmed by q-RT-PCR and protein expression by Western blotting. Of the genes that were significantly decreased by at least 1.5 fold, 70 were involved in cell adhesion; of these, at least 20 are known to be specifically involved in junction dynamics within the seminiferous epithelium. The mRNA and protein levels of Jam2, Ocln, cdh2 (N-cadherin, ctnna (α-catenin, and cldn11 (involved in adherens junctions, among others, were decreased by approximately 50% in aged spermatocytes. In addition, the GTPases Rac1 and cdc42, involved in the recruitment of cadherins to the adherens junctions, were similarly decreased. It is therefore not surprising that with lower expression of these proteins that the BTB becomes diminished with age. We saw, using a FITC tracer, a gradual collapse of the BTB between 18 and 24 months. This provides the opportunity for harmful substances and immune cells to cross the BTB and cause the disruption of spermatogenesis that is observed with increasing age.

  8. Diet-induced obesity in male C57BL/6 mice decreases fertility as a consequence of disrupted blood-testis barrier.

    Science.gov (United States)

    Fan, Yong; Liu, Yue; Xue, Ke; Gu, Guobao; Fan, Weimin; Xu, Yali; Ding, Zhide

    2015-01-01

    Obesity is a complex metabolic disease that is a serious detriment to both children and adult health, which induces a variety of diseases, such as cardiovascular disease, type II diabetes, hypertension and cancer. Although adverse effects of obesity on female reproduction or oocyte development have been well recognized, its harmfulness to male fertility is still unclear because of reported conflicting results. The aim of this study was to determine whether diet-induced obesity impairs male fertility and furthermore to uncover its underlying mechanisms. Thus, male C57BL/6 mice fed a high-fat diet (HFD) for 10 weeks served as a model of diet-induced obesity. The results clearly show that the percentage of sperm motility and progressive motility significantly decreased, whereas the proportion of teratozoospermia dramatically increased in HFD mice compared to those in normal diet fed controls. Besides, the sperm acrosome reaction fell accompanied by a decline in testosterone level and an increase in estradiol level in the HFD group. This alteration of sperm function parameters strongly indicated that the fertility of HFD mice was indeed impaired, which was also validated by a low pregnancy rate in their mated normal female. Moreover, testicular morphological analyses revealed that seminiferous epithelia were severely atrophic, and cell adhesions between spermatogenic cells and Sertoli cells were loosely arranged in HFD mice. Meanwhile, the integrity of the blood-testis barrier was severely interrupted consistent with declines in the tight junction related proteins, occludin, ZO-1 and androgen receptor, but instead endocytic vesicle-associated protein, clathrin rose. Taken together, obesity can impair male fertility through declines in the sperm function parameters, sex hormone level, whereas during spermatogenesis damage to the blood-testis barrier (BTB) integrity may be one of the crucial underlying factors accounting for this change.

  9. Diet-induced obesity in male C57BL/6 mice decreases fertility as a consequence of disrupted blood-testis barrier.

    Directory of Open Access Journals (Sweden)

    Yong Fan

    Full Text Available Obesity is a complex metabolic disease that is a serious detriment to both children and adult health, which induces a variety of diseases, such as cardiovascular disease, type II diabetes, hypertension and cancer. Although adverse effects of obesity on female reproduction or oocyte development have been well recognized, its harmfulness to male fertility is still unclear because of reported conflicting results. The aim of this study was to determine whether diet-induced obesity impairs male fertility and furthermore to uncover its underlying mechanisms. Thus, male C57BL/6 mice fed a high-fat diet (HFD for 10 weeks served as a model of diet-induced obesity. The results clearly show that the percentage of sperm motility and progressive motility significantly decreased, whereas the proportion of teratozoospermia dramatically increased in HFD mice compared to those in normal diet fed controls. Besides, the sperm acrosome reaction fell accompanied by a decline in testosterone level and an increase in estradiol level in the HFD group. This alteration of sperm function parameters strongly indicated that the fertility of HFD mice was indeed impaired, which was also validated by a low pregnancy rate in their mated normal female. Moreover, testicular morphological analyses revealed that seminiferous epithelia were severely atrophic, and cell adhesions between spermatogenic cells and Sertoli cells were loosely arranged in HFD mice. Meanwhile, the integrity of the blood-testis barrier was severely interrupted consistent with declines in the tight junction related proteins, occludin, ZO-1 and androgen receptor, but instead endocytic vesicle-associated protein, clathrin rose. Taken together, obesity can impair male fertility through declines in the sperm function parameters, sex hormone level, whereas during spermatogenesis damage to the blood-testis barrier (BTB integrity may be one of the crucial underlying factors accounting for this change.

  10. Research Article Flavocoxid Protects Against Cadmium-Induced Disruption of the Blood-Testis Barrier and Improves Testicular Damage and Germ Cell Impairment in Mice.

    Science.gov (United States)

    Minutoli, Letteria; Micali, Antonio; Pisani, Antonina; Puzzolo, Domenico; Bitto, Alessandra; Rinaldi, Mariagrazia; Pizzino, Gabriele; Irrera, Natasha; Galfo, Federica; Arena, Salvatore; Pallio, Giovanni; Mecchio, Anna; Germanà, Antonino; Bruschetta, Daniele; Laurà, Rosaria; Magno, Carlo; Marini, Herbert; Squadrito, Francesco; Altavilla, Domenica

    2015-11-01

    Cadmium (Cd) causes male infertility. There is the need to identify safe treatments counteracting this toxicity. Flavocoxid is a flavonoid that induces a balanced inhibition of cyclooxygenase (COX)-1 and COX-2 peroxidase moieties and of 5-lipoxygenase (LOX) and has efficacy in the male genitourinary system. We investigated flavocoxid effects on Cd-induced testicular toxicity in mice. Swiss mice were divided into 4 groups: 2 control groups received 0.9% NaCl (vehicle; 1 ml/kg/day) or flavocoxid (20 mg/kg/day ip); 2 groups were challenged with cadmium chloride (CdCl2; 2 mg/kg/day ip) and administered with vehicle or flavocoxid. The treatment lasted for 1 or 2 weeks. The testes were processed for biochemical and morphological studies. CdCl2 increased phosphorylated extracellular signal-regulated kinase (p-ERK) 1/2, tumor necrosis factor (TNF)-α, COX-2, 5-LOX, malondialdehyde (MDA), B-cell-lymphoma (Bcl)-2-associated X protein (Bax), follicle-stimulating hormone (FSH), luteinizing hormone (LH), transforming growth factor (TGF) -β3, decreased Bcl-2, testosterone, inhibin-B, occludin, N-Cadherin, induced structural damages in the testis and disrupted the blood-testis barrier. Many TUNEL-positive germ cells and changes in claudin-11, occludin, and N-cadherin localization were present. Flavocoxid administration reduced, in a time-dependent way, p-ERK 1/2, TNF-α, COX-2, 5-LOX, MDA, Bax, FSH, LH, TGF-β3, augmented Bcl-2, testosterone, inhibin B, occludin, N-Cadherin, and improved the structural organization of the testis and the blood-testis barrier. Few TUNEL-positive germ cells were present and a morphological retrieval of the intercellular junctions was observed. In conclusion, flavocoxid has a protective anti-inflammatory, antioxidant, and antiapoptotic function against Cd-induced toxicity in mice testis. We suggest that flavocoxid may play a relevant positive role against environmental levels of Cd, otherwise deleterious to gametogenesis and tubular integrity.

  11. EB1 regulates tubulin and actin cytoskeletal networks at the sertoli cell blood-testis barrier in male rats: an in vitro study.

    Science.gov (United States)

    Tang, Elizabeth I; Mok, Ka-Wai; Lee, Will M; Cheng, C Yan

    2015-02-01

    During spermatogenesis, developing germ cells are transported across the seminiferous epithelium. Studies propose that because microtubules (MTs) serve as the tracks for transporting cell organelles, they may also serve a similar function in the transport of developing germ cells. Polarized MTs may provide the tracks along which polarized actin microfilaments, which act as vehicles to transport cargo, such as preleptotene spermatocytes through the blood-testis barrier (BTB) and spermatids across the epithelium. Yet the molecular mechanism(s) underlying these events remain unknown. Using an established in vitro Sertoli cell system to study BTB function, we demonstrated herein that a MT regulatory protein end-binding protein 1 (EB1) regulates the MT- and also the actin-based cytoskeleton of the Sertoli cell BTB in the rat. EB1 serves as a coordinator between the two cytoskeletons by regulating MT polymerization and actin filament bundling to modulate germ cell transport at the Sertoli cell BTB. A knockdown of EB1 by RNA interference was found to perturb the tight junction (TJ)-permeability barrier, as evidenced by mislocalization of junctional proteins critical for barrier function to facilitate spermatocyte transport, which was likely achieved by two coordinated events. First, EB1 knockdown resulted in changes in MT polymerization, thereby perturbing MT organization in Sertoli cells in which polarized MT no longer stretched properly across the cell cytosol to serve as the tracks. Second, EB1 knockdown perturbed actin organization via its effects on the branched actin polymerization-inducing protein called Arp3 (actin-related protein 3), perturbing microfilament bundling capability based on a biochemical assay, thereby causing microfilament truncation and misorganization, disrupting the function of the vehicle. This reduced actin microfilament bundling capability thus perturbed TJ-protein distribution and localization at the BTB, destabilizing the TJ barrier, leading

  12. c-Yes regulates cell adhesion at the apical ectoplasmic specialization-blood-testis barrier axis via its effects on protein recruitment and distribution

    Science.gov (United States)

    Xiao, Xiang; Mruk, Dolores D.

    2013-01-01

    During spermatogenesis, extensive restructuring takes place at the cell-cell interface since developing germ cells migrate progressively from the basal to the adluminal compartment of the seminiferous epithelium. Since germ cells per se are not motile cells, their movement relies almost exclusively on the Sertoli cell. Nonetheless, extensive exchanges in signaling take place between these cells in the seminiferous epithelium. c-Yes, a nonreceptor protein tyrosine kinase belonging to the Src family kinases (SFKs) and a crucial signaling protein, was recently shown to be upregulated at the Sertoli cell-cell interface at the blood-testis barrier (BTB) at stages VIII–IX of the seminiferous epithelial cycle of spermatogenesis. It was also highly expressed at the Sertoli cell-spermatid interface known as apical ectoplasmic specialization (apical ES) at stage V to early stage VIII of the epithelial cycle during spermiogenesis. Herein, it was shown that the knockdown of c-Yes by RNAi in vitro and in vivo affected both Sertoli cell adhesion at the BTB and spermatid adhesion at the apical ES, causing a disruption of the Sertoli cell tight junction-permeability barrier function, germ cell loss from the seminiferous epithelium, and also a loss of spermatid polarity. These effects were shown to be mediated by changes in distribution and/or localization of adhesion proteins at the BTB (e.g., occludin, N-cadherin) and at the apical ES (e.g., nectin-3) and possibly the result of changes in the underlying actin filaments at the BTB and the apical ES. These findings implicate that c-Yes is a likely target of male contraceptive research. PMID:23169788

  13. Endocrine Disruptors Differentially Target ATP-Binding Cassette Transporters in the Blood-Testis Barrier and Affect Leydig Cell Testosterone Secretion In Vitro

    NARCIS (Netherlands)

    Dankers, A.C.A.; Roelofs, M.J.; Piersma, A.H.; Sweep, F.C.; Russel, F.G.M.; Berg, M. van den; Duursen, M.B. van; Masereeuw, R.

    2013-01-01

    Endocrine-disrupting chemicals (EDCs) are considered to cause testicular toxicity primarily via interference with steroid hormone function. Alternatively, EDCs could possibly exert their effects by interaction with ATP-binding cassette (ABC) transporters that are expressed in the blood-testis

  14. In-vitro formation of the blood-testis barrier during long-term organotypic culture of human prepubertal tissue: comparison with a large cohort of pre/peripubertal boys.

    Science.gov (United States)

    de Michele, F; Poels, J; Giudice, M G; De Smedt, F; Ambroise, J; Vermeulen, M; Gruson, D; Wyns, C

    2018-03-12

    How does the formation of the blood-testis barrier (BTB), as reflected by the expression of connexin 43 and claudin 11 proteins during the pubertal transition period, take place in vitro compared to samples from a large cohort of pre/peripubertal boys? The BTB connexin 43 and claudin 11 expression patterns appeared to be partially achieved in organotypic culture when compared to that in samples from 71 pre/peripubertal patients. Although alterations in the protein expression patterns of the BTB, whose main components are connexin 43 and claudin 11, are known to be associated with impaired spermatogenesis in mice and adult men, there is a lack of knowledge on its formation in pre-peripubertal human tissue both in vitro and in vivo. Moreover, despite Sertoli cell (SC) maturation during long-term organotypic culture of immature testicular tissue (ITT), initiation of spermatogenesis has not yet been achieved. Histological sections from 71 pre-peripubertal patients were evaluated for the formation of the BTB acting as in-vivo controls according to age, SC maturation, clinical signs of puberty and germ cell differentiation. Testicular tissue fragments retrieved from three prepubertal boys were cultured in a long term organotypic system to analyze the BTB formation and expression pattern in correlation with SC maturation. Testicular histological sections from 71 patients aged 0-16 years who underwent a biopsy between 2005 and 2014 to preserve their fertility before gonadotoxic treatment were examined. Immunohistochemistry (IHC) results for connexin 43 and claudin 11 as BTB markers, using a semi-quantitative score for their expression, and for Anti-Mullerian hormone (AMH), as SC maturation marker, were analyzed. Germ cell differentiation was evaluated on Hematoxylin-Eosin sections. Tanner stages at the time of biopsy were recorded from medical files. A longitudinal analysis of connexin 43, claudin 11 and AMH expressions on immunohistological sections of organotypic

  15. Why testes are resistant to hydatidosis: Is blood-testis-barrier ...

    African Journals Online (AJOL)

    Testes are extremely rare sites for echinococcosis. To our knowledge only three cases of testicular hydatid disease have been reported so far. In this laboratory animal model, we studied hydatidosis in rabbit testis. Fourteen male albino rabbits (body weight 2.5-3 kg) were randomized into two groups: Group A (study group), ...

  16. 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.

  17. The Blood-Testis Barrier and Male Sexual Dysfunction following Spinal Cord Injury

    Science.gov (United States)

    2014-10-01

    Naive Single live cells (% ) 0 5 10 15 B cells T cells Neutrophils Dendritic cells Macrophages NK cells NKT cells Age-matched naive 1.5 year post-SCI...antigenic sperm and sperm cell -containing compartments within the testis. We also demonstrated that once failed, the BTB remains permeable, essentially...through mature) as well as sperm precursor/stem cells from the immune system. We reported that a contusive injury to the rat spinal cord causes a

  18. FX barriers with smile dynamics

    NARCIS (Netherlands)

    Baker, Glyn; Beneder, Reimer; Zilber, A.

    2004-01-01

    Our mandate in this work has been to isolate the features of smile consistent models that are most relevant to the pricing of barrier options. We consider the two classical approaches of stochastic and (parametric) local volatility. Although neither has been particularly successful in practice their

  19. Effects of barrier fluctuation on the tunneling dynamics in the ...

    Indian Academy of Sciences (India)

    Abstract. We present a numerical investigation of the tunneling dynamics of a particle moving in a bistable potential with fluctuating barrier which is coupled to a non-integrable classical system and study the interplay between classical chaos and barrier fluctuation in the tunneling dynamics. We found that the coupling of the ...

  20. Nuclear dynamics around the barrier: from fusion to evaporation

    International Nuclear Information System (INIS)

    Simenel, Cedric

    2003-01-01

    This work is devoted to aspects of nuclear dynamics around the barrier. It is shown that for fusion reactions, the Coulomb field couples relative motion of nuclei to rotation of a deformed projectile independently of the energy and the charge of the nuclei. An experimental study of the reaction 6 He + 190 Os via gamma spectroscopy of product nuclei has shown that the break up of the 6 He is coupled to the relative motion too, a strong hindrance resulting in the fusion around and above the fusion barrier. The path to fusion after overcoming the barrier, especially the charge equilibration, have been studied in the framework of the TDHF theory via the preequilibrium GDR excited in N/Z asymmetric reactions. An application to formation of the super-heavy elements has been proposed. Finally, couplings between protons and neutrons have been shown up in mean field calculations. Their main expected effect is an emission of protons under the Coulomb barrier. (author)

  1. Effects of barrier fluctuation on the tunneling dynamics in the ...

    Indian Academy of Sciences (India)

    tic reorientations of a bridge unit or stochastically interrupted electronic pathway as in proteins [6]. So, the fluctuating barrier model can act as a good model for proton or H atom transfer dynamics in biomolecules or proteins where the protonic pathway contains a flipping molecular unit. Iwaniszewski studied the problem of.

  2. Relaxation oscillations and transport barrier dynamics in tokamak edge plasmas

    International Nuclear Information System (INIS)

    Benkadda, Sadruddin; Beyer, Peter; Fuhr-Chaudier, Guillaume; Garbet, Xavier; Ghendrih, Philippe; Sarazin, Yanick

    2004-01-01

    Oscillations of turbulent transport of particles and energy in magnetically confined plasmas can be easily observed in simulations of a variety of turbulence models. These oscillations typically involve a mechanism of energy exchange between fluctuations and a poloidal shear flow. This kind of ''predator-prey'' mechanism is found to be not relevant for transport barrier relaxations. In RBM simulations of resistive ballooning turbulence with transport barrier, relaxation oscillations of the latter are observed even in the case of frozen poloidal shear flow. These relaxations are due to a transitory growth of a mode localized at the barrier center. A one-dimensional model for the evolution of such a mode in the presence of a shear flow describes a transitory growth of an initial perturbation. Oscillations in the case of a finite steady-state shear flow are possible due to the coupling of the mode to the dynamics of the pressure profile. (author)

  3. TGF-betas: their role in testicular function and Sertoli cell tight junction dynamics.

    Science.gov (United States)

    Lui, Wing-Yee; Lee, Will M; Cheng, C Yan

    2003-06-01

    Transforming growth factor-betas (TGF-betas) are known to regulate multiple physiological functions in the testis, which include spermatogenesis, Leydig cell steroidogenesis, extracellular matrix synthesis and testis development. More recent studies have shown that TGF-beta3 also regulates Sertoli cell tight junction (TJ) dynamics in vitro via the p38 mitogen-activated protein (MAP) kinase pathway, suggesting that this cytokine plays a crucial role in regulating the opening and closing of the blood-testis barrier (BTB). This in turn regulates the passage of pre-leptotene and leptotene spermatocytes across the BTB at stages VIII-XI of the seminiferous epithelial cycle. This review summarizes recent advances of studies on TGF-betas in the testis, highlighting their regulatory role in TJ dynamics.

  4. Crossing the entropy barrier of dynamical zeta functions

    Energy Technology Data Exchange (ETDEWEB)

    Aurich, R.; Bolte, J.; Matthies, C.; Sieber, M.; Steiner, F. (Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik)

    1992-01-01

    Dynamical zeta functions are an important tool to quantize chaotic dynamical systems. The basic quantization rules require the computation of the zeta functions on the real energy axis, where the Euler product representations running over the classical periodic orbits usually do not converge due to the existence of the so-called entropy barrier determined by the topological entropy of the classical system. We shown that the convergence properties of the dynamical zeta functions rewritten as Dirichlet series are governed not only by the well-known topological and metric entropy, but depend crucially on subtle statistical properties of the Maslow indices and of the multiplicities of the periodic orbits that are measured by a new parameter for which we introduce the notion of a third entropy. If and only if the third entropy is nonvanishing, one can cross the entropy barrier; if it exceeds a certain value, one can even compute the zeta function in the physical region by means of a convergent Dirichlet series. A simple statistical model is presented which allows to compute the third entropy. Four examples of chaotic systems are studied in detail to test the model numerically. (orig.).

  5. Crossing the entropy barrier of dynamical zeta functions

    International Nuclear Information System (INIS)

    Aurich, R.; Bolte, J.; Matthies, C.; Sieber, M.; Steiner, F.

    1992-01-01

    Dynamical zeta functions are an important tool to quantize chaotic dynamical systems. The basic quantization rules require the computation of the zeta functions on the real energy axis, where the Euler product representations running over the classical periodic orbits usually do not converge due to the existence of the so-called entropy barrier determined by the topological entropy of the classical system. We shown that the convergence properties of the dynamical zeta functions rewritten as Dirichlet series are governed not only by the well-known topological and metric entropy, but depend crucially on subtle statistical properties of the Maslow indices and of the multiplicities of the periodic orbits that are measured by a new parameter for which we introduce the notion of a third entropy. If and only if the third entropy is nonvanishing, one can cross the entropy barrier; if it exceeds a certain value, one can even compute the zeta function in the physical region by means of a convergent Dirichlet series. A simple statistical model is presented which allows to compute the third entropy. Four examples of chaotic systems are studied in detail to test the model numerically. (orig.)

  6. An extreme breaching of a barrier spit: insights on large breach formation and its impact on barrier dynamics

    Science.gov (United States)

    Iulian Zăinescu, Florin; Vespremeanu-Stroe, Alfred; Tătui, Florin

    2017-04-01

    In this study, we document a case of exceptionally large natural breaching of a sandy spit (Sacalin barrier, Danube delta) using Lidar data and satellite imagery, annual (and seasonal) surveys of topography and bathymetry on successive cross-barrier profiles, and hourly datasets of wind and waves. The breach morphology and dynamics was monitored and described from its inception to closure, together with its impact on the adjoining features (upper shoreface, back-barrier lagoon, downdrift coast) and on the local sediment budgets. Breaching is first observed to occur on a beach-length of 0.5 km in April 2012 and two years later reached 3.5 km (May 2014). The barrier translates to a recovery stage dominated by continuous back-barrier deposition through subaqueous cross-breach sediment transport. Soon, the barrier widening triggers a negative feedback which limits the back-barrier sediment transfer. As a result, back-barrier deposition decreases whilst the barrier aggradation through overwash becomes more frequent. The event was found to be a natural experiment which switched the barrier's decadal evolution from low cross-shore transport to high cross-shore transport over the barrier. Although previously considered as constant, the cross-shore transport recorded during the large breach lifespan is an order of magnitude larger than in the non-breach period. 3 x 106 m3 of sediment were deposited in three years which is equivalent to the modelled longshore transport in the region. Nevertheless, the sediment circuits are more complex involving exchanges with the upper shoreface, as indicated by the extensive erosion down to -4m. In the absence of tides, the Sacalin breach closed naturally in 3 years and brings a valuable contribution on how breaches may evolve, as only limited data has been internationally reported until now. The very high deposition rate of sediment in the breach is a testimony of the high sediment volumes supplied by the longshore transport and the high

  7. Diet-Induced Obesity in Male C57BL/6 Mice Decreases Fertility as a Consequence of Disrupted Blood-Testis Barrier

    OpenAIRE

    Fan, Yong; Liu, Yue; Xue, Ke; Gu, Guobao; Fan, Weimin; Xu, Yali; Ding, Zhide

    2015-01-01

    Obesity is a complex metabolic disease that is a serious detriment to both children and adult health, which induces a variety of diseases, such as cardiovascular disease, type II diabetes, hypertension and cancer. Although adverse effects of obesity on female reproduction or oocyte development have been well recognized, its harmfulness to male fertility is still unclear because of reported conflicting results. The aim of this study was to determine whether diet-induced obesity impairs male fe...

  8. Dynamical analysis on heavy-ion fusion reactions near Coulomb barrier

    International Nuclear Information System (INIS)

    Feng Zhaoqing; Jin Genming; Zhang Fengshou

    2008-01-01

    The shell correction is proposed in the improved isospin dependent quantum molecular dynamics (ImIQMD) model, which plays an important role in heavy-ion fusion reactions near Coulomb barrier. By using the ImIQMD model, the static and dynamical fusion barriers, dynamical barrier distribution in the fusion reactions are analyzed systematically. The fusion and capture excitation functions for a series of reaction systems are calculated and compared with experimental data. It is found that the fusion cross sections for neutron-rich systems increase obviously, and the strong shell effects of two colliding nuclei result in a decrease of the fusion cross sections at the sub-barrier energies. The lowering of the dynamical fusion barriers favors the enhancement of the sub-barrier fusion cross sections, which is related to the nucleon transfer and the neck formation in the fusion reactions

  9. Unified Model of Dynamic Forced Barrier Crossing in Single Molecules

    Energy Technology Data Exchange (ETDEWEB)

    Friddle, R W

    2007-06-21

    Thermally activated barrier crossing in the presence of an increasing load can reveal kinetic rate constants and energy barrier parameters when repeated over a range of loading rates. Here we derive a model of the mean escape force for all relevant loading rates--the complete force spectrum. Two well-known approximations emerge as limiting cases; one of which confirms predictions that single-barrier spectra should converge to a phenomenological description in the slow loading limit.

  10. Quantum dynamics of a particle interacting with a double barrier

    International Nuclear Information System (INIS)

    Cacciari, Ilaria; Lantieri, Marco; Moretti, Paolo

    2007-01-01

    Following a previously developed method, the problem of a particle scattered by a double barrier is studied. Instead of the simple transmission or reflection, the more difficult case of the arrival in the region between the barriers is considered and solved explicitly by using matrix methods

  11. Dynamic simulation of collisions of heavy high-speed trucks with concrete barriers

    International Nuclear Information System (INIS)

    Itoh, Yoshito; Liu, Chunlu; Kusama, Ryuichi

    2007-01-01

    Real vehicle collision experiments on full-scale road safety barriers are important to determine the outcome of a vehicle versus barrier impact accident. However, such experiments require large investment of time and money. Numerical simulation has therefore been imperative as an alternative method for testing concrete barriers. In this research, spring subgrade models were first developed to simulate the ground boundary of concrete barriers. Both heavy trucks and concrete barriers were modeled using finite element methods (FEM) to simulate dynamic collision performances. Comparison of the results generated from computer simulations and on-site full-scale experiments demonstrated that the developed models could be applied to simulate the collision of heavy trucks with concrete barriers to provide the data to design new road safety barriers and analyze existing ones

  12. Dynamics of Multi-kinks in the Presence of Wells and Barriers

    International Nuclear Information System (INIS)

    Goatham, S.W.; Mannering, L.E.; Hann, R.; Krusch, S.

    2011-01-01

    Sine-Gordon kinks are non-dispersive solutions in a much studied integrable system. Recent studies on sine-Gordon kinks with space-dependent square-well-type potentials have revealed interesting dynamics of a single kink interacting with wells and barriers. In this paper, we study a class of smooth space-dependent potentials and discuss the dynamics of one kink in the presence of different wells. We also present values for the critical velocity for different types of barriers. Furthermore, we study two kinks interacting with various wells and describe interesting trajectories such as double-trapping, kink knock-out and double-escape. (authors)

  13. Dynamical characterization of transport barriers in nontwist Hamiltonian systems

    Science.gov (United States)

    Mugnaine, M.; Mathias, A. C.; Santos, M. S.; Batista, A. M.; Szezech, J. D.; Viana, R. L.

    2018-01-01

    The turnstile provides us a useful tool to describe the flux in twist Hamiltonian systems. Thus, its determination allows us to find the areas where the trajectories flux through barriers. We show that the mechanism of the turnstile can increase the flux in nontwist Hamiltonian systems. A model which captures the essence of these systems is the standard nontwist map, introduced by del Castillo-Negrete and Morrison. For selected parameters of this map, we show that chaotic trajectories entering in resonances zones can be explained by turnstiles formed by a set of homoclinic points. We argue that for nontwist systems, if the heteroclinic points are sufficiently close, they can connect twin-islands chains. This provides us a scenario where the trajectories can cross the resonance zones and increase the flux. For these cases the escape basin boundaries are nontrivial, which demands the use of an appropriate characterization. We applied the uncertainty exponent and the entropies of the escape basin boundary in order to quantify the degree of unpredictability of the asymptotic trajectories.

  14. Mass-Related Dynamical Barriers in Triatomic Reactions

    Science.gov (United States)

    Yanao, T.; Koon, W. S.; Marsden, J. E.

    2006-06-01

    A methodology is given to determine the effect of different mass distributions for triatomic reactions using the geometry of shape space. Atomic masses are incorporated into the non-Euclidean shape space metric after the separation of rotations. Using the equations of motion in this non-Euclidean shape space, an averaged field of velocity-dependent fictitious forces is determined. This force field, as opposed to the force arising from the potential, dominates branching ratios of isomerization dynamics of a triatomic molecule. This methodology may be useful for qualitative prediction of branching ratios in general triatomic reactions.

  15. Energy Barriers and Driving Forces Associated with the Dynamic Transformation of Ti-6Al-4V (Preprint)

    Science.gov (United States)

    2017-12-11

    AFRL-RX-WP-JA-2017-0516 ENERGY BARRIERS AND DRIVING FORCES ASSOCIATED WITH THE DYNAMIC TRANSFORMATION OF TI-6AL-4V (PREPRINT) S.L...TYPE 3. DATES COVERED (From - To) 11 December 2017 Interim 19 March 2014 – 11 November 2017 4. TITLE AND SUBTITLE ENERGY BARRIERS AND DRIVING FORCES...The energy barriers and driving forces associated with dynamic transformation in Ti-6Al-4V are evaluated. It is shown that the stored energy is less

  16. A new approach to barrier-top fission dynamics

    Directory of Open Access Journals (Sweden)

    Bertsch G.F.

    2016-01-01

    Full Text Available We proposed a calculational framework for describing induced fission that avoids the Bohr-Wheeler assumption of well-defined fission channels. The building blocks of our approach are configurations that form a discrete, orthogonal basis and can be characterized by both energy and shape. The dynamics is to be determined by interaction matrix elements between the states rather than by a Hill-Wheeler construction of a collective coordinate. Within our approach, several simple limits can be seen: diffusion; quantized conductance; and ordinary decay through channels. The specific proposal for the discrete basis is to use the Kπ quantum numbers of the axially symmetric Hartree-Fock approximation to generate the configurations. Fission paths would be determined by hopping from configuration to configuration via the residual interaction. We show as an example the configurations needed to describe a fictitious fission decay 32S → 16 O + 16 O. We also examine the geometry of the path for fission of 236U, measuring distances by the number of jumps needed to go to a new Kπ partition.

  17. Dynamical barrier for the formation of solitary waves in discrete lattices

    International Nuclear Information System (INIS)

    Kevrekidis, P.G.; Espinola-Rocha, J.A.; Drossinos, Y.; Stefanov, A.

    2008-01-01

    We consider the problem of the existence of a dynamical barrier of 'mass' that needs to be excited on a lattice site to lead to the formation and subsequent persistence of localized modes for a nonlinear Schroedinger lattice. We contrast the existence of a dynamical barrier with its absence in the static theory of localized modes in one spatial dimension. We suggest an energetic criterion that provides a sufficient, but not necessary, condition on the amplitude of a single-site initial condition required to form a solitary wave. We show that this effect is not one-dimensional by considering its two-dimensional analog. The existence of a sufficient condition for the excitation of localized modes in the non-integrable, discrete, nonlinear Schroedinger equation is compared to the dynamics of excitations in the integrable, both discrete and continuum, version of the nonlinear Schroedinger equation

  18. Dynamical barrier for the formation of solitary waves in discrete lattices

    Energy Technology Data Exchange (ETDEWEB)

    Kevrekidis, P.G. [Department of Mathematics and Statistics, University of Massachusetts, Amherst, MA 01003 (United States)], E-mail: kevrekid@math.umass.edu; Espinola-Rocha, J.A. [Department of Mathematics and Statistics, University of Massachusetts, Amherst, MA 01003 (United States); Drossinos, Y. [European Commission, Joint Research Centre, I-21020 Ispra (Vatican City State, Holy See,) (Italy); School of Mechanical and Systems Engineering, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU (United Kingdom); Stefanov, A. [Department of Mathematics, University of Kansas, 1460 Jayhawk Blvd., Lawrence, KS 66045-7523 (United States)

    2008-03-24

    We consider the problem of the existence of a dynamical barrier of 'mass' that needs to be excited on a lattice site to lead to the formation and subsequent persistence of localized modes for a nonlinear Schroedinger lattice. We contrast the existence of a dynamical barrier with its absence in the static theory of localized modes in one spatial dimension. We suggest an energetic criterion that provides a sufficient, but not necessary, condition on the amplitude of a single-site initial condition required to form a solitary wave. We show that this effect is not one-dimensional by considering its two-dimensional analog. The existence of a sufficient condition for the excitation of localized modes in the non-integrable, discrete, nonlinear Schroedinger equation is compared to the dynamics of excitations in the integrable, both discrete and continuum, version of the nonlinear Schroedinger equation.

  19. Optimal design of wind barriers using 3D computational fluid dynamics simulations

    Science.gov (United States)

    Fang, H.; Wu, X.; Yang, X.

    2017-12-01

    Desertification is a significant global environmental and ecological problem that requires human-regulated control and management. Wind barriers are commonly used to reduce wind velocity or trap drifting sand in arid or semi-arid areas. Therefore, optimal design of wind barriers becomes critical in Aeolian engineering. In the current study, we perform 3D computational fluid dynamics (CFD) simulations for flow passing through wind barriers with different structural parameters. To validate the simulation results, we first inter-compare the simulated flow field results with those from both wind-tunnel experiments and field measurements. Quantitative analyses of the shelter effect are then conducted based on a series of simulations with different structural parameters (such as wind barrier porosity, row numbers, inter-row spacing and belt schemes). The results show that wind barriers with porosity of 0.35 could provide the longest shelter distance (i.e., where the wind velocity reduction is more than 50%) thus are recommended in engineering designs. To determine the optimal row number and belt scheme, we introduce a cost function that takes both wind-velocity reduction effects and economical expense into account. The calculated cost function show that a 3-row-belt scheme with inter-row spacing of 6h (h as the height of wind barriers) and inter-belt spacing of 12h is the most effective.

  20. Understanding the free energy barrier and multiple timescale dynamics of charge separation in organic photovoltaic cells

    Science.gov (United States)

    Yan, Yaming; Song, Linze; Shi, Qiang

    2018-02-01

    By employing several lattice model systems, we investigate the free energy barrier and real-time dynamics of charge separation in organic photovoltaic (OPV) cells. It is found that the combined effects of the external electric field, entropy, and charge delocalization reduce the free energy barrier significantly. The dynamic disorder reduces charge carrier delocalization and results in the increased charge separation barrier, while the effect of static disorder is more complicated. Simulation of the real-time dynamics indicates that the free charge generation process involves multiple time scales, including an ultrafast component within hundreds of femtoseconds, an intermediate component related to the relaxation of the hot charge transfer (CT) state, and a slow component on the time scale of tens of picoseconds from the thermally equilibrated CT state. Effects of hot exciton dissociation as well as its dependence on the energy offset between the Frenkel exciton and the CT state are also analyzed. The current results indicate that only a small energy offset between the band gap and the lowest energy CT state is needed to achieve efficient free charge generation in OPV devices, which agrees with recent experimental findings.

  1. Understanding the free energy barrier and multiple timescale dynamics of charge separation in organic photovoltaic cells.

    Science.gov (United States)

    Yan, Yaming; Song, Linze; Shi, Qiang

    2018-02-28

    By employing several lattice model systems, we investigate the free energy barrier and real-time dynamics of charge separation in organic photovoltaic (OPV) cells. It is found that the combined effects of the external electric field, entropy, and charge delocalization reduce the free energy barrier significantly. The dynamic disorder reduces charge carrier delocalization and results in the increased charge separation barrier, while the effect of static disorder is more complicated. Simulation of the real-time dynamics indicates that the free charge generation process involves multiple time scales, including an ultrafast component within hundreds of femtoseconds, an intermediate component related to the relaxation of the hot charge transfer (CT) state, and a slow component on the time scale of tens of picoseconds from the thermally equilibrated CT state. Effects of hot exciton dissociation as well as its dependence on the energy offset between the Frenkel exciton and the CT state are also analyzed. The current results indicate that only a small energy offset between the band gap and the lowest energy CT state is needed to achieve efficient free charge generation in OPV devices, which agrees with recent experimental findings.

  2. Assessing the in vivo impact of a gel sanitizer on the epidermal "barrier" dynamics

    Directory of Open Access Journals (Sweden)

    Henrique Silva

    2015-03-01

    Full Text Available Disease prevention and control depend on hand washing, in particular during epidemic surges (e.g. flu. The use of alcohol-based hand sanitizers is strongly recommended due to its high germicide effectiveness. However, its impact on skin physiology, especially on the barrier function, has not been determined, although most of the formulations include different humectants. This study evaluates the impact of a commercially available formulation on in vivo epidermal barrier dynamics. 13 young adult subjects (21.6 ± 2.6 years old were selected after informed consent. Subjects were asked to apply a commercially available alcohol gel sanitizer to one hand for 15 days. TEWL absolute values were measured on days 1, 8 and 15 and a plastic occlusion stress test (POST applied. Evaporation half-life (t1/2 evap and dynamic water mass (DWM values increased significantly on day 15 on the treated hand compared to the control hand suggesting that, in the present experimental conditions, the regular use of an alcohol-based gel sanitizer does changes the epidermal barrier. This study also confirms the usefulness of this kinetic model to detect subtle changes on in vivo TEWL dynamics.

  3. A study of methyl group dynamics and barrier heights in a homologous series of unbranched ketones

    Science.gov (United States)

    Green, R. M.; Horsewill, A. J.

    The temperature dependence of the nuclear (proton) spin-lattice relaxation time, T1, has been measured in the range 10-300 K for the following series of unbranched ketones; 2-butanone to 2-nonanone, 3-pentanone to 3-octanone and 4-heptanone. This data has been analysed to provide estimates for the magnitudes of the three-fold potential barriers to reorientation of all methyl groups in these materials. The corresponding methyl tunnel splittings have also been predicted. Measurements of six tunnel splittings in four of the samples encompassing an energy range of four orders of magnitude confirm these predictions to be accurate and provide refined values for the barrier heights. The tunnelling spectroscopy was performed using the techniques of high-resolution inelastic neutron scattering, field-cycling level-crossing N.M.R. spectroscopy and double sideband irradiation N.M.R. spectroscopy. The observed trends in barrier height within the series of materials have been rationalized in terms of the known molecular structure and inter- and intra-molecular contributions have been separately identified and accounted for. The four measured barrier heights in 2-pentanone have been employed to model the temperature dependence of T1 using Clough et al.'s single parameter theory for methyl dynamics. The agreement with experiment is very good.

  4. Electron dynamics and plasma jet formation in a helium atmospheric pressure dielectric barrier discharge jet

    Energy Technology Data Exchange (ETDEWEB)

    Algwari, Q. Th. [Centre for Plasma Physics, School of Maths and Physics, Queen' s University Belfast, University Road, Belfast, Northern Ireland BT7 1NN (United Kingdom); Electronic Department, College of Electronics Engineering, Mosul University, Mosul 41002 (Iraq); O' Connell, D. [Centre for Plasma Physics, School of Maths and Physics, Queen' s University Belfast, University Road, Belfast, Northern Ireland BT7 1NN (United Kingdom); York Plasma Institute, Department of Physics, University of York, York YO10 5DD (United Kingdom)

    2011-09-19

    The excitation dynamics within the main plasma production region and the plasma jets of a kHz atmospheric pressure dielectric barrier discharge (DBD) jet operated in helium was investigated. Within the dielectric tube, the plasma ignites as a streamer-type discharge. Plasma jets are emitted from both the powered and grounded electrode end; their dynamics are compared and contrasted. Ignition of these jets are quite different; the jet emitted from the powered electrode is ignited with a slight time delay to plasma ignition inside the dielectric tube, while breakdown of the jet at the grounded electrode end is from charging of the dielectric and is therefore dependent on plasma production and transport within the dielectric tube. Present streamer theories can explain these dynamics.

  5. Activated barrier crossing dynamics in the non-radiative decay of NADH and NADPH

    Science.gov (United States)

    Blacker, Thomas S.; Marsh, Richard J.; Duchen, Michael R.; Bain, Angus J.

    2013-08-01

    In live tissue, alterations in metabolism induce changes in the fluorescence decay of the biological coenzyme NAD(P)H, the mechanism of which is not well understood. In this work, the fluorescence and anisotropy decay dynamics of NADH and NADPH were investigated as a function of viscosity in a range of water-glycerol solutions. The viscosity dependence of the non-radiative decay is well described by Kramers and Kramers-Hubbard models of activated barrier crossing over a wide viscosity range. Our combined lifetime and anisotropy analysis indicates common mechanisms of non-radiative relaxation in the two emitting states (conformations) of both molecules. The low frequencies associated with barrier crossing suggest that non-radiative decay is mediated by small scale motion (e.g. puckering) of the nicotinamide ring. Variations in the fluorescence lifetimes of NADH and NADPH when bound to different enzymes may therefore be attributed to differing levels of conformational restriction upon binding.

  6. Human Skin Barrier Structure and Function Analyzed by Cryo-EM and Molecular Dynamics Simulation.

    Science.gov (United States)

    Lundborg, Magnus; Narangifard, Ali; Wennberg, Christian L; Lindahl, Erik; Daneholt, Bertil; Norlén, Lars

    2018-04-24

    In the present study we have analyzed the molecular structure and function of the human skin's permeability barrier using molecular dynamics simulation validated against cryo-electron microscopy data from near native skin. The skin's barrier capacity is located to an intercellular lipid structure embedding the cells of the superficial most layer of skin - the stratum corneum. According to the splayed bilayer model (Iwai et al., 2012) the lipid structure is organized as stacked bilayers of ceramides in a splayed chain conformation with cholesterol associated with the ceramide sphingoid moiety and free fatty acids associated with the ceramide fatty acid moiety. However, knowledge about the lipid structure's detailed molecular organization, and the roles of its different lipid constituents, remains circumstantial. Starting from a molecular dynamics model based on the splayed bilayer model, we have, by stepwise structural and compositional modifications, arrived at a thermodynamically stable molecular dynamics model expressing simulated electron microscopy patterns matching original cryo-electron microscopy patterns from skin extremely closely. Strikingly, the closer the individual molecular dynamics models' lipid composition was to that reported in human stratum corneum, the better was the match between the models' simulated electron microscopy patterns and the original cryo-electron microscopy patterns. Moreover, the closest-matching model's calculated water permeability and thermotropic behaviour were found compatible with that of human skin. The new model may facilitate more advanced physics-based skin permeability predictions of drugs and toxicants. The proposed procedure for molecular dynamics based analysis of cellular cryo-electron microscopy data might be applied to other biomolecular systems. Copyright © 2018. Published by Elsevier Inc.

  7. Triaxial quadrupole dynamics and the inner fission barrier of some heavy even-even nuclei

    Science.gov (United States)

    Benrabia, K.; Medjadi, D. E.; Imadalou, M.; Quentin, P.

    2017-09-01

    Background: Inner fission barriers of actinide nuclei have been known for a long time to be unstable with respect to the axial symmetry. On the other hand, taking into account the effect of the relevant adiabatic mass parameter reduces or even may wash out this instability. A proper treatment of the dynamics for both axial and triaxial modes is thus crucial to accurately determine the corresponding fission barriers. This entails in particular an accurate description of pairing correlations. Purpose: We evaluate the potential energies, moments of inertia, and vibrational mass parameters in a two-dimensional relevant deformation space (corresponding to the usual β and γ quadrupole deformation parameters) for four actinide nuclei (236U, 240Pu, 248Cm, and 252Cf). We assess the relevance of our approach to describe the dynamics for a triaxial mode by computing the low energy spectra (exploring thus mainly the equilibrium deformation region). We evaluate the inner fission barrier heights releasing the axial symmetry constraint. Method: Calculations within the Hartree-Fock plus BCS approach are performed using the SkM* Skyrme effective interaction in the particle-hole channel and a seniority force in the particle-particle channel. The intensity of this residual interaction has been fixed to allow a good reproduction of some odd-even mass differences in the actinide region. Adiabatic mass parameters for the rotational and vibrational modes are calculated using the Inglis-Belyaev formula supplemented by a global renormalization factor taking into account the so-called Thouless-Valatin corrections. Spectra are obtained through the diagonalization of the corresponding Bohr collective Hamiltonian. Results: The experimental low energy spectra are qualitatively well reproduced by our calculations for the considered nuclei. Inner fission barrier heights are calculated and compared with available estimates from various experimental data. The reproduction of the data is better

  8. Globalization of the automobile industry in China. Dynamics and barriers in the greening of road transportation

    Energy Technology Data Exchange (ETDEWEB)

    Gan, Lin

    2001-08-01

    This article describes the state of the automobile industry and urban road transportation management in China. It reviews how the automobile industry is evolving to respond to challenges in economic development, environmental regulations, and technological change. The dynamics and barriers resulting from technological change of the automobile in response to reduction of exhaust emissions and energy-efficiency improvement are analyzed. It is argued that consideration of externality costs should be integrated in automobile industrial policy making and transport management. This paper questions the current government policy of encouraging private car ownership, and suggests that improvement in public transportation systems and stronger emissions control would be relevant to China's drive toward sustainable transportation development. (author)

  9. Globalization of the automobile industry in China: dynamics and barriers in greening of the road transportation

    International Nuclear Information System (INIS)

    Gan Lin

    2003-01-01

    This article describes the state of the automobile industry and urban road transportation management in China. It reviews how the automobile industry is evolving to respond to challenges in economic development, environmental regulations, and technological change. The dynamics and barriers resulting from technological change of automobiles in response to reduction of exhaust emissions and energy-efficiency improvement are analyzed. It is argued that consideration of externality costs should be integrated in automobile industrial policymaking and transportation management. Efforts need to be made to use more economic incentives for emissions reduction, and to promote technological change for cleaner vehicle development. This paper questions the current government policy of encouraging private car ownership, and suggests that improvement in public transportation systems, stronger emissions control, and technology innovation on environmental friendly automobile technologies would be relevant to China's drive toward sustainable transportation development. Social inequities resulted from automobile use is also stressed in the analysis

  10. Plasma dynamics in a packed bed dielectric barrier discharge (DBD) operated in helium

    Science.gov (United States)

    Mujahid, Zaka-ul-Islam; Hala, Ahmed

    2018-03-01

    Packed bed dielectric barrier discharges (DBDs) are very promising for several applications including remediation of environmental pollutants and greenhouse gas conversion. In this work, we have investigated the space and time-resolved emission from a packed bed DBD operated in helium, to understand the plasma dynamics. We have chosen a simple planar DBD arrangement with a patterned dielectric, which mimics the spherical boundaries between the dielectric pellets and allows the optical access to the plasma. The results show that plasma is sustained in a packed bed DBD by three mechanisms: filamentary discharge in the void (between the center of dielectric structures and the opposite electrode), microdischarges at the contact points and surface ionization waves over the dielectric surface. It is observed that for most of the duration plasma is generated at the contact points between the dielectric structures.

  11. Dynamical seasonal prediction of summer sea surface temperatures in the Great Barrier Reef

    Science.gov (United States)

    Spillman, C. M.; Alves, O.

    2009-03-01

    Coral bleaching is a serious problem threatening the world coral reef systems, triggered by high sea surface temperatures (SST) which are becoming more prevalent as a result of global warming. Seasonal forecasts from coupled ocean-atmosphere models can be used to predict anomalous SST months in advance. In this study, we assess the ability of the Australian Bureau of Meteorology seasonal forecast model (POAMA) to forecast SST anomalies in the Great Barrier Reef, Australia, with particular focus on the major 1998 and 2002 bleaching events. Advance warning of potential bleaching events allows for the implementation of management strategies to minimise reef damage. This study represents the first attempt to apply a dynamical seasonal model to the problem of coral bleaching and predict SST over a reef system for up to 6 months lead-time, a potentially invaluable tool for reef managers.

  12. A Novel Dynamic Neonatal Blood-Brain Barrier on a Chip.

    Directory of Open Access Journals (Sweden)

    Sudhir P Deosarkar

    Full Text Available Studies of neonatal neural pathologies and development of appropriate therapeutics are hampered by a lack of relevant in vitro models of neonatal blood-brain barrier (BBB. To establish such a model, we have developed a novel blood-brain barrier on a chip (B3C that comprises a tissue compartment and vascular channels placed side-by-side mimicking the three-dimensional morphology, size and flow characteristics of microvessels in vivo. Rat brain endothelial cells (RBEC isolated from neonatal rats were seeded in the vascular channels of B3C and maintained under shear flow conditions, while neonatal rat astrocytes were cultured under static conditions in the tissue compartment of the B3C. RBEC formed continuous endothelial lining with a central lumen along the length of the vascular channels of B3C and exhibited tight junction formation, as measured by the expression of zonula occludens-1 (ZO-1. ZO-1 expression significantly increased with shear flow in the vascular channels and with the presence of astrocyte conditioned medium (ACM or astrocytes cultured in the tissue compartment. Consistent with in vivo BBB, B3C allowed endfeet-like astrocyte-endothelial cell interactions through a porous interface that separates the tissue compartment containing cultured astrocytes from the cultured RBEC in the vascular channels. The permeability of fluorescent 40 kDa dextran from vascular channel to the tissue compartment significantly decreased when RBEC were cultured in the presence of astrocytes or ACM (from 41.0 ± 0.9 x 10-6 cm/s to 2.9 ± 1.0 x 10-6 cm/s or 1.1±0.4 x 10-6 cm/s, respectively. Measurement of electrical resistance in B3C further supports that the addition of ACM significantly improves the barrier function in neonatal RBEC. Moreover, B3C exhibits significantly improved barrier characteristics compared to the transwell model and B3C permeability was not significantly different from the in vivo BBB permeability in neonatal rats. In summary, we

  13. Dynamic Characteristics of Positive Pulsed Dielectric Barrier Discharge for Ozone Generation in Air

    International Nuclear Information System (INIS)

    Wei Linsheng; Peng Bangfa; Li Ming; Zhang Yafang; Hu Zhaoji

    2016-01-01

    A comprehensive dynamic model consisting of 66 reactions and 24 species is developed to investigate the dynamic characteristics of ozone generation by positive pulsed dielectric barrier discharge (DBD) using parallel-plate reactor in air. The electron energy conservation equation is coupled to the electron continuity equation, the heavy species continuity equation, and Poisson's equation for a better description. The reliability of the model is experimentally confirmed. The model can be used to predict the temporal and spatial evolution of species, as well as streamer propagation. The simulation results show that electron density increases nearly exponentially in the direction to the anode at the electron avalanche. Streamer propagation velocity is about 5.26 × 10 4 m/s from anode to cathode in the simulated condition. The primary positive ion, negative ion, and excited species are O 2 + , O 3 − and O 2 ( 1 Δg) in pulsed DBD in air, respectively. N 2 O has the largest density among nitrogen oxides. e and N 2 + densities in the streamer head increase gradually to maximum values with the development of the streamer. Meanwhile, the O 2 + , O, O 3 , N 2 (A 3 Σ) and N 2 O densities reach maximum values in the vicinity of the anode. (paper)

  14. Trajectory approach to dissipative quantum phase space dynamics: Application to barrier scattering

    International Nuclear Information System (INIS)

    Hughes, Keith H.; Wyatt, Robert E.

    2004-01-01

    The Caldeira-Leggett master equation, expressed in Lindblad form, has been used in the numerical study of the effect of a thermal environment on the dynamics of the scattering of a wave packet from a repulsive Eckart barrier. The dynamics are studied in terms of phase space trajectories associated with the distribution function, W(q,p,t). The equations of motion for the trajectories include quantum terms that introduce nonlocality into the motion, which imply that an ensemble of correlated trajectories needs to be propagated. However, use of the derivative propagation method (DPM) allows each trajectory to be propagated individually. This is achieved by deriving equations of motion for the partial derivatives of W(q,p,t) that appear in the master equation. The effects of dissipation on the trajectories are studied and results are shown for the transmission probability. On short time scales, decoherence is demonstrated by a swelling of trajectories into momentum space. For a nondissipative system, a comparison is made of the DPM with the 'exact' transmission probability calculated from a fixed grid calculation

  15. Dynamic model based on voltage transfer curve for pattern formation in dielectric barrier glow discharge

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ben; He, Feng; Ouyang, Jiting, E-mail: jtouyang@bit.edu.cn [School of Physics, Beijing Institute of Technology, Beijing 100081 (China); Duan, Xiaoxi [Research Center of Laser Fusion, CAEP, Mianyang 621900 (China)

    2015-12-15

    Simulation work is very important for understanding the formation of self-organized discharge patterns. Previous works have witnessed different models derived from other systems for simulation of discharge pattern, but most of these models are complicated and time-consuming. In this paper, we introduce a convenient phenomenological dynamic model based on the basic dynamic process of glow discharge and the voltage transfer curve (VTC) to study the dielectric barrier glow discharge (DBGD) pattern. VTC is an important characteristic of DBGD, which plots the change of wall voltage after a discharge as a function of the initial total gap voltage. In the modeling, the combined effect of the discharge conditions is included in VTC, and the activation-inhibition effect is expressed by a spatial interaction term. Besides, the model reduces the dimensionality of the system by just considering the integration effect of current flow. All these greatly facilitate the construction of this model. Numerical simulations turn out to be in good accordance with our previous fluid modeling and experimental result.

  16. Dynamic behaviour of a flexible membrane tsunami Barrier with Dyneema®

    NARCIS (Netherlands)

    Hofland, B.; Marissen, R.; Bergsma, O.K.

    2016-01-01

    Proof-of-concept model tests on a novel self-deploying on-shore tsunami barrier were executed. The tsunami barrier consists of a membrane, floater and cables that are stored underground. Due to buoyancy the barrier self-deploys when struck by a tsunami. The membrane and cables consist of the strong,

  17. Zebrafish as a visual and dynamic model to study the transport of nanosized drug delivery systems across the biological barriers.

    Science.gov (United States)

    Li, Ye; Miao, Xiaoqing; Chen, Tongkai; Yi, Xiang; Wang, Ruibing; Zhao, Haitao; Lee, Simon Ming-Yuen; Wang, Xueqing; Zheng, Ying

    2017-08-01

    With the wide application of nanotechnology to drug delivery systems, a simple, dynamic and visual in vivo model for high-throughput screening of novel formulations with fluorescence markers across biological barriers is desperately needed. In vitro cell culture models have been widely used, although they are far from a complimentary in vivo system. Mammalian animal models are common predictive models to study transport, but they are costly and time consuming. Zebrafish (Danio rerio), a small vertebrate model, have the potential to be developed as an "intermediate" model for quick evaluations. Based on our previously established coumarin 6 nanocrystals (C6-NCs), which have two different sizes, the present study investigates the transportation of C6-NCs across four biological barriers, including the chorion, blood brain barrier (BBB), blood retinal barrier (BRB) and gastrointestinal (GI) barrier, using zebrafish embryos and larvae as in vivo models. The biodistribution and elimination of C6 from different organs were quantified in adult zebrafish. The results showed that compared to 200nm C6-NCs, 70nm C6-NCs showed better permeability across these biological barriers. A FRET study suggested that intact C6-NCs together with the free dissolved form of C6 were absorbed into the larval zebrafish. More C6 was accumulated in different organs after incubation with small sized NCs via lipid raft-mediated endocytosis in adult zebrafish, which is consistent with the findings from in vitro cell monolayers and the zebrafish larvae model. C6-NCs could be gradually eliminated in each organ over time. This study demonstrated the successful application of zebrafish as a simple and dynamic model to simultaneously assess the transport of nanosized drug delivery systems across several biological barriers and biodistribution in different organs, especially in the brain, which could be used for central nervous system (CNS) drug and delivery system screening. Copyright © 2017 Elsevier B

  18. Complete and incomplete fusion dynamics of {sup 6,7}Li + {sup 159}Tb reactions near the Coulomb barrier

    Energy Technology Data Exchange (ETDEWEB)

    Gautam, Manjeet Singh [Thapar University, School of Physics and Materials Science, Patiala (India); Indus Degree College, Department of Physics, Kinana, Jind, Haryana (India); Grover, Neha; Sharma, Manoj K. [Thapar University, School of Physics and Materials Science, Patiala (India)

    2017-01-15

    The complete fusion (CF) and incomplete fusion (ICF) cross-sections are estimated for {sup 6,} {sup 7}Li + {sup 159}Tb reactions using the energy-dependent Woods-Saxon potential model (EDWSP model) and dynamical cluster-decay model (DCM). The CF data of the {sup 6}Li + {sup 159}Tb({sup 7}Li + {sup 159}Tb) reaction at above barrier energies is suppressed with reference to expectations of the EDWSP model by 25% (20%) which is smaller than the reported data by ∝ 9% (6%). This suppression is correlated with the projectile breakup effect. The projectiles {sup 6,7}Li are loosely bound systems, which may break up into charged fragments prior to reaching the fusion barrier and subsequently one of the fragment is captured by the target leading to the suppression of fusion data at above barrier energies. The sum of CF and ICF, which is termed as total fusion cross-section (TF), removes the discrepancies between theoretical predictions and the above barrier complete fusion data and hence is adequately explained via the EDWSP model over a wide range of energy spread across the Coulomb barrier. In addition to fusion, the decay mechanism of {sup 6}Li + {sup 159}Tb reaction is studied within the framework of the dynamical cluster-decay model (DCM). The breakup of the projectile ({sup 6}Li) in the entrance channel indicates the presence of ICF, which is investigated further using the collective clusterization approach of DCM. The present theoretical analysis suggests that a larger barrier modification is needed to address the fusion data of chosen reactions in the below barrier energy region. (orig.)

  19. Dynamic Characteristics of Positive Pulsed Dielectric Barrier Discharge for Ozone Generation in Air

    Science.gov (United States)

    Wei, Linsheng; Peng, Bangfa; Li, Ming; Zhang, Yafang; Hu, Zhaoji

    2016-02-01

    A comprehensive dynamic model consisting of 66 reactions and 24 species is developed to investigate the dynamic characteristics of ozone generation by positive pulsed dielectric barrier discharge (DBD) using parallel-plate reactor in air. The electron energy conservation equation is coupled to the electron continuity equation, the heavy species continuity equation, and Poisson's equation for a better description. The reliability of the model is experimentally confirmed. The model can be used to predict the temporal and spatial evolution of species, as well as streamer propagation. The simulation results show that electron density increases nearly exponentially in the direction to the anode at the electron avalanche. Streamer propagation velocity is about 5.26 × 104 m/s from anode to cathode in the simulated condition. The primary positive ion, negative ion, and excited species are O2+, O3- and O2(1Δg) in pulsed DBD in air, respectively. N2O has the largest density among nitrogen oxides. e and N2+ densities in the streamer head increase gradually to maximum values with the development of the streamer. Meanwhile, the O2+, O, O3, N2(A3Σ) and N2O densities reach maximum values in the vicinity of the anode. supported by National Natural Science Foundation of China (Nos. 51366012 and 11105067), Jiangxi Province Young Scientists (Jinggang Star) Cultivation Plan of China (No. 20133BCB23008), Natural Science Foundation of Jiangxi, China (No. 20151BAB206047) and Jiangxi Province Higher School Science and Technology Landing Plan of China (No. KJLD-14015)

  20. Disturbance and the dynamics of coral cover on the Great Barrier Reef (1995-2009).

    Science.gov (United States)

    Osborne, Kate; Dolman, Andrew M; Burgess, Scott C; Johns, Kerryn A

    2011-03-10

    Coral reef ecosystems worldwide are under pressure from chronic and acute stressors that threaten their continued existence. Most obvious among changes to reefs is loss of hard coral cover, but a precise multi-scale estimate of coral cover dynamics for the Great Barrier Reef (GBR) is currently lacking. Monitoring data collected annually from fixed sites at 47 reefs across 1300 km of the GBR indicate that overall regional coral cover was stable (averaging 29% and ranging from 23% to 33% cover across years) with no net decline between 1995 and 2009. Subregional trends (10-100 km) in hard coral were diverse with some being very dynamic and others changing little. Coral cover increased in six subregions and decreased in seven subregions. Persistent decline of corals occurred in one subregion for hard coral and Acroporidae and in four subregions in non-Acroporidae families. Change in Acroporidae accounted for 68% of change in hard coral. Crown-of-thorns starfish (Acanthaster planci) outbreaks and storm damage were responsible for more coral loss during this period than either bleaching or disease despite two mass bleaching events and an increase in the incidence of coral disease. While the limited data for the GBR prior to the 1980's suggests that coral cover was higher than in our survey, we found no evidence of consistent, system-wide decline in coral cover since 1995. Instead, fluctuations in coral cover at subregional scales (10-100 km), driven mostly by changes in fast-growing Acroporidae, occurred as a result of localized disturbance events and subsequent recovery.

  1. Disturbance and the dynamics of coral cover on the Great Barrier Reef (1995-2009.

    Directory of Open Access Journals (Sweden)

    Kate Osborne

    Full Text Available Coral reef ecosystems worldwide are under pressure from chronic and acute stressors that threaten their continued existence. Most obvious among changes to reefs is loss of hard coral cover, but a precise multi-scale estimate of coral cover dynamics for the Great Barrier Reef (GBR is currently lacking. Monitoring data collected annually from fixed sites at 47 reefs across 1300 km of the GBR indicate that overall regional coral cover was stable (averaging 29% and ranging from 23% to 33% cover across years with no net decline between 1995 and 2009. Subregional trends (10-100 km in hard coral were diverse with some being very dynamic and others changing little. Coral cover increased in six subregions and decreased in seven subregions. Persistent decline of corals occurred in one subregion for hard coral and Acroporidae and in four subregions in non-Acroporidae families. Change in Acroporidae accounted for 68% of change in hard coral. Crown-of-thorns starfish (Acanthaster planci outbreaks and storm damage were responsible for more coral loss during this period than either bleaching or disease despite two mass bleaching events and an increase in the incidence of coral disease. While the limited data for the GBR prior to the 1980's suggests that coral cover was higher than in our survey, we found no evidence of consistent, system-wide decline in coral cover since 1995. Instead, fluctuations in coral cover at subregional scales (10-100 km, driven mostly by changes in fast-growing Acroporidae, occurred as a result of localized disturbance events and subsequent recovery.

  2. Mesoscale plasma dynamics, transport barriers and zonal flows: simulations and paradigms

    Energy Technology Data Exchange (ETDEWEB)

    Thyagaraja, A.; Knight, P.J. [Euratom/Ukaea Fusion Association, Culham Science Centre, Abingdon, OX (United Kingdom); Loureiro, N. [Plasma Physics Group, Imperial College of Science, Technology and Medicine, London (United Kingdom)

    2004-06-01

    Tokamaks are magnetic confinement fusion devices which seek to produce power from fusion reactions between the isotopes of hydrogen (deuterium and tritium). The understanding of turbulent transport processes which govern the energy, momentum and current distributions in tokamak plasmas is important to optimising the economically viable design of future power plants based on the tokamak concept. With the advent of powerful modern computers it has become possible to model the plasma dynamics on the so-called 'mesoscale' which consists of electromagnetic turbulence with wavelengths intermediate to the ion gyro radius and the system size of typical tokamaks. This paper attempts to describe one such approach which evolves the two-fluid model of a tokamak plasma globally (i.e., both on the macro-scale and the mesoscale), using a nonlinear, electromagnetic, three-dimensional code CUTIE. Recent researches, both theoretical and experimental, on tokamaks indicate the spontaneous (or, externally induced) generation of so-called 'zonal flows', which, under well-defined conditions, can lead to substantial reduction of turbulent transport in localized regions known as transport barriers. This type of confinement enhancement is of great importance in the design and construction of practical fusion power plants and has been the subject of intensive study. In addition to the computational approach based on CUTIE simulations, we also describe some simpler paradigmatic models which are designed to illustrate the genesis of zonal flows by characteristic drift wave fluctuations and the effects of such highly sheared advective flows on the system dynamics. These models help one to understand in a much clearer fashion the rather complex processes simulated by CUTIE. (authors)

  3. Atomic oxygen dynamics in an air dielectric barrier discharge: a combined diagnostic and modeling approach

    Science.gov (United States)

    Baldus, Sabrina; Schröder, Daniel; Bibinov, Nikita; Schulz-von der Gathen, Volker; Awakowicz, Peter

    2015-06-01

    Cold atmospheric pressure plasmas are a promising alternative therapy for treatment of chronic wounds, as they have already shown in clinical trials. In this study an air dielectric barrier discharge (DBD) developed for therapeutic use in dermatology is characterized with respect to the plasma produced reactive oxygen species, namely atomic oxygen and ozone, which are known to be of great importance to wound healing. To understand the plasma chemistry of the applied DBD, xenon-calibrated two-photon laser-induced fluorescence spectroscopy and optical absorption spectroscopy are applied. The measured spatial distributions are shown and compared to each other. A model of the afterglow chemistry based on optical emission spectroscopy is developed to cross-check the measurement results and obtain insight into the dynamics of the considered reactive oxygen species. The atomic oxygen density is found to be located mostly between the electrodes with a maximum density of {{n}\\text{O}}=6× {{10}16} cm-3 . Time resolved measurements reveal a constant atomic oxygen density between two high voltage pulses. The ozone is measured up to 3 mm outside the active plasma volume, reaching a maximum value of {{n}{{\\text{O}3}}}=3× {{10}16} cm-3 between the electrodes.

  4. Challenging fission dynamics around the barrier: The case of {sup 34}S + {sup 186}W

    Energy Technology Data Exchange (ETDEWEB)

    Kozulin, E.M.; Itkis, I.; Knyazheva, G.; Novikov, K.; Bogachev, A.; Dmitriev, S.; Loktev, T. [Joint Institute for Nuclear Research, Flerov Laboratory of Nuclear Reactions, Dubna (Russian Federation); Vardaci, E. [Dipartamento di Scienze Fisiche, Napoli (Italy); INFN, Napoli (Italy); Harca, I.M. [Joint Institute for Nuclear Research, Flerov Laboratory of Nuclear Reactions, Dubna (Russian Federation); Horia Hulubei National Institute for R and D in Physics and Nuclear Engineering (IFIN-HH), Bucharest - Magurele (Romania); Universitatea din Bucuresti, Facultatea de Fizica, Bucharest (Romania); Schmitt, C.; Piot, J. [GANIL, CEA/DSM-CNRS/IN2P3, Bd Henri Becquerel, BP 55027, Caen (France); Azaiez, F.; Matea, I.; Verney, D.; Gottardo, A. [Universite Paris-Saclay, IPN, CNRS/IN2P3, Orsay (France); Dorvaux, O. [Universite de Strasbourg, IPHC, CNRS/IN2P3, Strasbourg (France); Chubarian, G. [Texas A and M University, Cyclotron Institute, College Station, TX (United States); Trzaska, W.H. [Accelerator Laboratory of University of Jyvaskyla (JYFL), Jyvaskyla (Finland); Hanappe, F. [Universite Libre de Bruxelles (ULB), Bruxelles (Belgium); Borcea, C.; Calinescu, S.; Petrone, C. [Horia Hulubei National Institute for R and D in Physics and Nuclear Engineering (IFIN-HH), Bucharest - Magurele (Romania)

    2016-09-15

    The current status of fission dynamics studies in heavy-ion collisions around the Coulomb barrier is illustrated with the {sup 34}S + {sup 186}W reaction. The fission-fragment mass and total kinetic energy were measured at the ALTO facility at IPN Orsay, France, with a dedicated set-up using the (v, E) approach. The measurement reveals the presence of an asymmetric fission component on top of a predominantly symmetric distribution. The asymmetric structure, pointed out for the first time, is discussed along with results of previous experiments studying the same reaction. While these analyses suggested the contribution from either quasi-fission or pre-equilibrium fission, we offer an alternative interpretation, in terms of shell-driven compound-nucleus fission. The present measurement demonstrates the critical influence of resolution when addressing puzzling cases, situated at the crossroads of the various channels opened in a heavy-ion collision. Current status in the field clearly calls for innovative measurements involving manifold correlations and new observables. The outcome of the attempt done in this work in this direction, based on the coincident measurement of prompt γ-rays is reported, and encouraging perspectives are discussed. (orig.)

  5. Modulating the skin barrier function by DMSO: molecular dynamics simulations of hydrophilic and hydrophobic transmembrane pores

    NARCIS (Netherlands)

    den Otter, Wouter K.; Notman, R.; Anwar, J.; Noro, M.G.; Briels, Willem J.

    2008-01-01

    The dense lipid bilayers at the outer surface of the skin represent the primary barrier to molecules penetrating the human skin. One approach to overcome this barrier, with promising applications in administering medicinal drugs to the body, is to employ chemical permeability enhancers. How these

  6. Assessment of blood–brain barrier disruption using dynamic contrast-enhanced MRI. A systematic review

    Directory of Open Access Journals (Sweden)

    Anna K. Heye

    2014-01-01

    Full Text Available There is increasing recognition of the importance of blood–brain barrier (BBB disruption in aging, dementia, stroke and multiple sclerosis in addition to more commonly-studied pathologies such as tumors. Dynamic contrast-enhanced MRI (DCE-MRI is a method for studying BBB disruption in vivo. We review pathologies studied, scanning protocols and data analysis procedures to determine the range of available methods and their suitability to different pathologies. We systematically review the existing literature up to February 2014, seeking studies that assessed BBB integrity using T1-weighted DCE-MRI techniques in animals and humans in normal or abnormal brain tissues. The literature search provided 70 studies that were eligible for inclusion, involving 417 animals and 1564 human subjects in total. The pathologies most studied are intracranial neoplasms and acute ischemic strokes. There are large variations in the type of DCE-MRI sequence, the imaging protocols and the contrast agents used. Moreover, studies use a variety of different methods for data analysis, mainly based on model-free measurements and on the Patlak and Tofts models. Consequently, estimated KTrans values varied widely. In conclusion, DCE-MRI is shown to provide valuable information in a large variety of applications, ranging from common applications, such as grading of primary brain tumors, to more recent applications, such as assessment of subtle BBB dysfunction in Alzheimer's disease. Further research is required in order to establish consensus-based recommendations for data acquisition and analysis and, hence, improve inter-study comparability and promote wider use of DCE-MRI.

  7. Foliation impact on the dynamic properties of selected samples of the barrier dam site Prvonek: Right side

    Directory of Open Access Journals (Sweden)

    Majstorović Jelena

    2016-01-01

    Full Text Available The 'Prvonek' dam was built in tight asymmetric Banjska river valley about 100 meters downstream from the river Gradasnica. Barrier at the dam site built predominantly slate series of high crystallinity Vranjska Banja, alternately layered double mica, gneiss, leptinolite and micaschist. For the construction of this place were carried out extensive field and laboratory geotechnical investigations. Part of laboratory geotechnical investigations related to the testing of dynamic properties in the perpendicular and parallel direction to the foliation of gneiss and micashist samples on the right side. The aim of investigations is definition of anisotropy tested dynamic parameters.

  8. 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)

  9. Chemical dynamics between wells across a time-dependent barrier: Self-similarity in the Lagrangian descriptor and reactive basins

    Science.gov (United States)

    Junginger, Andrej; Duvenbeck, Lennart; Feldmaier, Matthias; Main, Jörg; Wunner, Günter; Hernandez, Rigoberto

    2017-08-01

    In chemical or physical reaction dynamics, it is essential to distinguish precisely between reactants and products for all times. This task is especially demanding in time-dependent or driven systems because therein the dividing surface (DS) between these states often exhibits a nontrivial time-dependence. The so-called transition state (TS) trajectory has been seen to define a DS which is free of recrossings in a large number of one-dimensional reactions across time-dependent barriers and thus, allows one to determine exact reaction rates. A fundamental challenge to applying this method is the construction of the TS trajectory itself. The minimization of Lagrangian descriptors (LDs) provides a general and powerful scheme to obtain that trajectory even when perturbation theory fails. Both approaches encounter possible breakdowns when the overall potential is bounded, admitting the possibility of returns to the barrier long after the trajectories have reached the product or reactant wells. Such global dynamics cannot be captured by perturbation theory. Meanwhile, in the LD-DS approach, it leads to the emergence of additional local minima which make it difficult to extract the optimal branch associated with the desired TS trajectory. In this work, we illustrate this behavior for a time-dependent double-well potential revealing a self-similar structure of the LD, and we demonstrate how the reflections and side-minima can be addressed by an appropriate modification of the LD associated with the direct rate across the barrier.

  10. Analysis of dynamic characteristics of SiC Schottky barrier diodes at high switching frequency based on junction capacitance

    Science.gov (United States)

    Maeda, Ryosuke; Okuda, Takafumi; Hikihara, Takashi

    2018-04-01

    In this paper, we focus on relationships between dynamic characteristics and device structures of SiC Schottky barrier diodes (SBDs) to investigate their switching capabilities. A device model based on junction capacitance and thermionic emission theory is proposed. To measure the dynamic characteristics of SiC SBD, a high-frequency (10 MHz) and high-voltage (200 Vpp) wave generator is fabricated. By comparing simulated results with experimental results, it is found that the proposed model can represent the dynamic characteristics at 10 MHz and 200 °C, and the simple device model based on junction capacitance and thermionic emission theory well describes the switching behaviors of SiC SBDs at full operational temperature. The proposed device model is beneficial for designing high-power converters, at both wide temperature and wide frequency ranges.

  11. A submesoscale coherent vortex in the Ligurian Sea: From dynamical barriers to biological implications

    Science.gov (United States)

    Bosse, Anthony; Testor, Pierre; Mayot, Nicolas; Prieur, Louis; D'Ortenzio, Fabrizio; Mortier, Laurent; Le Goff, Hervé; Gourcuff, Claire; Coppola, Laurent; Lavigne, Héloïse; Raimbault, Patrick

    2017-08-01

    In June 2013, a glider equipped with oxygen and fluorescence sensors has been used to extensively sample an anticyclonic Submesoscale Coherent Vortex (SCV) in the Ligurian Sea (NW Mediterranean Sea). Those measurements are complemented by full-depth CTD casts (T, S, and oxygen) and water samples documenting nutrients and phytoplankton pigments within the SCV and outside. The SCV has a very homogeneous core of oxygenated waters between 300 and 1200 m formed 4.5 months earlier during the winter deep convection event. It has a strong dynamical signature with peak velocities at 700 m depth of 13.9 cm s-1 in cyclogeostrophic balance. The eddy has a small radius of 6.2 km corresponding to high Rossby number of -0.45. The vorticity at the eddy center reaches -0.8f. Cross-stream isopycnic diffusion of tracers between the eddy core and the surroundings is found to be very limited due to dynamical barriers set by the SCV associated with a diffusivity coefficient of about 0.2 m2 s-1. The deep core is nutrients-depleted with concentrations of nitrate, phosphate, and silicate, 13-18% lower than the rich surrounding waters. However, the nutriclines are shifted of about 20-50 m toward the surface thus increasing the nutrients availability for phytoplankton. Chlorophyll-a concentrations at the deep chlorophyll maximum are subsequently about twice bigger as compared to outside. Pigments further reveal the predominance of nanophytoplankton inside the eddy and an enhancement of the primary productivity. This study demonstrates the important impact of postconvective SCVs on nutrients distribution and phytoplankton community, as well as on the subsequent primary production and carbon sequestration.Plain Language SummaryDue to harsh meteorological conditions in winter, a few places of the world's ocean experience an intense cooling of their surface waters that start to sink in a process called oceanic deep convection. It is crucial for the functioning of the ocean, but also the marine

  12. Exercise-induced oxidative-nitrosative stress is associated with impaired dynamic cerebral autoregulation and blood-brain barrier leakage.

    Science.gov (United States)

    Bailey, Damian M; Evans, Kevin A; McEneny, Jane; Young, Ian S; Hullin, David A; James, Philip E; Ogoh, Shigehiko; Ainslie, Philip N; Lucchesi, Céline; Rockenbauer, Antal; Culcasi, Marcel; Pietri, Sylvia

    2011-11-01

    The present study examined whether dynamic cerebral autoregulation and blood-brain barrier function would become compromised as a result of exercise-induced oxidative-nitrosative stress. Eight healthy men were examined at rest and after an incremental bout of semi-recumbent cycling exercise to exhaustion. Changes in a dynamic cerebral autoregulation index were determined during recovery from continuous recordings of blood flow velocity in the middle cerebral artery (MCAv) and mean arterial pressure during transiently induced hypotension. Electron paramagnetic resonance spectroscopy and ozone-based chemiluminescence were employed for direct detection of spin-trapped free radicals and nitric oxide metabolites in venous blood. Neuron-specific enolase, S100β and 3-nitrotyrosine were determined by ELISA. While exercise did not alter MCAv, it caused a mild reduction in the autoregulation index (from 6.9 ± 0.6 to 5.5 ± 0.9 a.u., P brain barrier permeability without causing structural brain damage subsequent to a free radical-mediated impairment in dynamic cerebral autoregulation.

  13. New Dynamic Approach of a Safety Barrier Wall for a Civil Transport Aircraft

    OpenAIRE

    Merz, Ludger

    2010-01-01

    One of the challenges for Airbus preparing a new freighter development process was the design of a solid freighter barrier, which separates the courier area from the cargo compartment. The major task of such a barrier is to protect the passengers against all risks caused due to cargo impact by a justifiable design. These risks may result from all kind of survivable incident and accident scenarios. Real aircraft crashes were analyzed to get away from a static book-case and come to a more reali...

  14. The fusion of membranes and vesicles: pathway and energy barriers from Dissipative Particle Dynamics

    DEFF Research Database (Denmark)

    Shillcock, Julian C.

    2009-01-01

    are simulated using the optimized parameter set. In the observed fusion pathway, configurations of individual lipids play an important role. Fusion starts with individual lipids assuming a splayed tail configuration with one tail inserted in each membrane. To determine the corresponding energy barrier, we...

  15. Dynamics of the edge transport barrier at plasma biasing on the CASTOR tokamak

    Czech Academy of Sciences Publication Activity Database

    Stöckel, Jan; Spolaore, M.; Peleman, P.; Brotánková, Jana; Horáček, Jan; Dejarnac, Renaud; Devynck, P.; Ďuran, Ivan; Gunn, J. P.; Hron, Martin; Kocan, M.; Martines, E.; Pánek, Radomír; Sharma, A.; Van Oost, G.

    2006-01-01

    Roč. 12, č. 6 (2006), s. 19-23 ISSN 1562-6016. [International Conference on Plasma Physics and Technology/11th./. Alushta, 11.9.2006-16.9.2006] Institutional research plan: CEZ:AV0Z20430508 Keywords : tokamak * plasma * transport barrier * relaxations Subject RIV: BL - Plasma and Gas Discharge Physics http:// vant .kipt.kharkov.ua/TABFRAME.html

  16. Dynamical barrier and isotope effects in the simplest substitution reaction via Walden inversion mechanism

    Science.gov (United States)

    Zhao, Zhiqiang; Zhang, Zhaojun; Liu, Shu; Zhang, Dong H.

    2017-02-01

    Reactions occurring at a carbon atom through the Walden inversion mechanism are one of the most important and useful classes of reactions in chemistry. Here we report an accurate theoretical study of the simplest reaction of that type: the H+CH4 substitution reaction and its isotope analogues. It is found that the reaction threshold versus collision energy is considerably higher than the barrier height. The reaction exhibits a strong normal secondary isotope effect on the cross-sections measured above the reaction threshold, and a small but reverse secondary kinetic isotope effect at room temperature. Detailed analysis reveals that the reaction proceeds along a path with a higher barrier height instead of the minimum-energy path because the umbrella angle of the non-reacting methyl group cannot change synchronously with the other reaction coordinates during the reaction due to insufficient energy transfer from the translational motion to the umbrella mode.

  17. Seasonal Dynamical Prediction of Coral Bleaching in the Great Barrier Reef, Australia

    Science.gov (United States)

    Spillman, C. M.; Alves, O.

    2009-05-01

    Sea surface temperature (SST) is now recognised as the primary cause of mass coral bleaching events. Coral bleaching occurs during times of stress, particularly when SSTs exceed the coral colony's tolerance level. Global warming is potentially a serious threat to the future of the world's reef systems with predictions by the international community that bleaching will increase in both frequency and severity. Advance warning of anomalous sea surface temperatures, and thus potential bleaching events, would allow for the implementation of management strategies to minimise reef damage. Seasonal SST forecasts from the coupled ocean-atmosphere model POAMA (Bureau of Meteorology) have skill in the Great Barrier Reef (Australia) several months into the future. We will present model forecasts and probabilistic products for use in reef management, and assess model skill in the region. These products will revolutionise the way in which coral bleaching events are monitored and assessed in the Great Barrier Reef and Australian region.

  18. Blood epididymal barrier to [3H]-inulin in intact and vasectomized hamsters

    International Nuclear Information System (INIS)

    Turner, T.T.; D'Addario, D.A.; Howards, S.S.

    1981-01-01

    The net transport of [ 3 H]-inulin into the fluids of the hamster seminiferous and caput, corpus, and cauda epididymal tubules was examined in both intact animals and those vasectomized 10 months previously. Mean isotope concentrations in reproductive tract tubule fluids did not exceeded 10 per cent of blood plasma isotope concentrations during the experiment. There were no significant differences in net transport of [ 3 H]-inulin into any of the tubule fluids sampled. Ten months after vasectomy, the seminiferous tubule, and all regions of the epididymal tubule retain the capacity to exclude [ 3 H]-insulin. Thus in the hamster 10 months after vasectomy, the blood testis and blood epididymal barriers to inulin are intact

  19. Barrier Systems

    NARCIS (Netherlands)

    Heteren, S. van

    2015-01-01

    Barrier-system dynamics are a function of antecedent topography and substrate lithology, Relative sea-level (RSL) changes, sediment availability and type, climate, vegetation type and cover, and various aero- and hydrodynamic processes during fair-weather conditions and extreme events. Global change

  20. Professional perspectives on systemic barriers to admission avoidance: learning from a system dynamics study of older people's admission pathways.

    Science.gov (United States)

    Walsh, Bronagh; Lattimer, Valerie; Wintrup, Julie; Brailsford, Sally

    2015-06-01

    There is debate worldwide about the best way to manage increased healthcare demand within ageing populations, particularly rising rates of unplanned and avoidable hospital admissions. To understand health and social care professionals' perspectives on barriers to admission avoidance throughout the admissions journey, in particular: the causes of avoidable admissions in older people; drivers of admission and barriers to use of admission avoidance strategies; and improvements to reduce unnecessary admissions. A qualitative framework analysis of interview data from a System dynamics (SD) modelling study. Semi-structured interviews were conducted with twenty health and social care professionals with experience of older people's admissions. The interviews were used to build understanding of factors facilitating or hindering admission avoidance across the admissions system. Data were analysed using framework analysis. Three overarching themes emerged: understanding the needs of the patient group; understanding the whole system; and systemwide access to expertise in care of older people. There were diverse views on the underlying reasons for avoidable admissions and recognition of the need for whole-system approaches to service redesign. Participants recommended system redesign that recognises the specific needs of older people, but there was no consensus on underlying patient needs or specific service developments. Access to expertise in management of older and frailer patients was seen as a barrier to admission avoidance throughout the system. Providing access to expertise and leadership in care of frail older people across the admissions system presents a challenge for service managers and nurse educators but is seen as a prerequisite for effective admission avoidance. System redesign to meet the needs of frail older people requires agreement on causes of avoidable admission and underlying patient needs. © 2014 John Wiley & Sons Ltd.

  1. Reaction dynamics studies for the system 7Be + 208Pb at Coulomb barrier energies

    Directory of Open Access Journals (Sweden)

    Mazzocco M.

    2017-01-01

    Full Text Available The scattering process of the Radioactive Ion Beam 7Be from a 208Pb target was measured at three near-barrier energies. The quasi-elastic angular distributions were analyzed within the framework of the optical model to extract the reaction cross sections. The results are compared with those obtained for the reactions induced by the mirror projectile 7Li and by the lightest particle-stable lithium isotope 6Li on the same target. The angular distributions for the production of the two 7Be constituent clusters, namely 3He and 4He, were also measured. In agreement with what observed for the interaction of 7Be with lighter targets, the production of the heavier helium isotope resulted to be much more abundant than that of its lighter counterpart.

  2. Reaction dynamics studies for the system 7Be + 208Pb at Coulomb barrier energies

    Science.gov (United States)

    Mazzocco, M.; Boiano, A.; Boiano, C.; La Commara, M.; Manea, C.; Parascandolo, C.; Pierroutsakou, D.; Strano, E.; Torresi, D.; Acosta, L.; Di Meo, P.; Fernandez-Garcia, J. P.; Glodariu, T.; Grebosz, J.; Guglielmetti, A.; Marquinez-Duran, G.; Martel, I.; Nicoletto, M.; Pakou, A.; Sánchez-Benítez, A. M.; Sava, T.; Sgouros, O.; Signorini, C.; Soramel, F.; Soukeras, V.; Stroe, L.

    2017-11-01

    The scattering process of the Radioactive Ion Beam 7Be from a 208Pb target was measured at three near-barrier energies. The quasi-elastic angular distributions were analyzed within the framework of the optical model to extract the reaction cross sections. The results are compared with those obtained for the reactions induced by the mirror projectile 7Li and by the lightest particle-stable lithium isotope 6Li on the same target. The angular distributions for the production of the two 7Be constituent clusters, namely 3He and 4He, were also measured. In agreement with what observed for the interaction of 7Be with lighter targets, the production of the heavier helium isotope resulted to be much more abundant than that of its lighter counterpart.

  3. Consequences of unburned hydrocarbons on microstreamer dynamics and chemistry during plasma remediation of NO sub x using dielectric barrier discharges

    CERN Document Server

    Dorai, R

    2003-01-01

    Atmospheric pressure plasmas, and dielectric barrier discharges (DBDs) in particular, are being investigated for their use in the remediation of nitrogen oxides (NO sub x) from automotive exhausts. In their normal mode of operation, DBDs consist of a large density of short-lived filamentary microdischarges. Localized energy deposition results in spatially nonuniform gas temperatures and species densities which initiate advective and diffusive transport. Diesel exhausts, one of the major sources of NO sub x , typically contain unburned hydrocarbons (UHCs) which significantly influence the NO sub x chemistry during plasma remediation. In this paper, we discuss results from a computational investigation of the consequences of UHC chemistry on radial transport dynamics and remediation of NO sub x. In the presence of UHCs, radicals such as O and OH are dominantly consumed in the microstreamer region and their transport to larger radii is reduced. As a result, the conversion of NO to NO sub 2 is mainly restricted t...

  4. The influence of shape on the glassy dynamics of hard nonspherical particle fluids. II. Barriers, relaxation, fragility, kinetic vitrification, and universality

    Science.gov (United States)

    Tripathy, Mukta; Schweizer, Kenneth S.

    2009-06-01

    We extend and apply the nonlinear Langevin equation theory of activated barrier hopping dynamics in glassy fluids and colloidal suspensions to study broad families of one-, two-, and three-dimensional hard nonspherical particles. Beyond the ideal kinetic arrest volume fraction, entropic barriers emerge with heights (alpha relaxation times, inverse diffusion constants) that increase nonlinearly (nonexponentially) with volume fraction and in a manner that becomes stronger with particle dimensionality. Partial collapse of the volume fraction dependence of barrier heights and reduced relaxation times of different particle shapes within a fixed dimensionality class are achieved based on a difference volume fraction variable that quantifies the distance from the ideal mode coupling theory dynamic crossover. However, the barrier, alpha relaxation time, and self-diffusion constant results of all shapes are remarkably well collapsed onto a single universal master curve based on a theoretically motivated coupling constant which quantifies the renormalized mean square force on a tagged particle. The latter is determined mainly by the square of the intermolecular site-site contact value of the pair correlation function, thereby providing an explicit microscopic connection between local packing, binary collisions, and slow dynamics. A large variation of the dynamic fragility with particle shape is found with compact cluster particles being the most fragile. A kinetic glass transition map is constructed that is relevant to vitrification of laboratory colloidal suspensions. The possible relevance of the hard particle results for understanding the dynamic fragility of thermal van der Waals liquids is discussed.

  5. Superresolution and Fluorescence Dynamics Evidence Reveal That Intact Liposomes Do Not Cross the Human Skin Barrier.

    Directory of Open Access Journals (Sweden)

    Jes Dreier

    Full Text Available In this study we use the combination of super resolution optical microscopy and raster image correlation spectroscopy (RICS to study the mechanism of action of liposomes as transdermal drug delivery systems in human skin. Two different compositions of liposomes were applied to newly excised human skin, a POPC liposome and a more flexible liposome containing the surfactant sodium cholate. Stimulated emission depletion microscopy (STED images of intact skin and cryo-sections of skin treated with labeled liposomes were recorded displaying an optical resolution low enough to resolve the 100 nm liposomes in the skin. The images revealed that virtually none of the liposomes remained intact beneath the skin surface. RICS two color cross correlation diffusion measurements of double labeled liposomes confirmed these observations. Our results suggest that the liposomes do not act as carriers that transport their cargo directly through the skin barrier, but mainly burst and fuse with the outer lipid layers of the stratum corneum. It was also found that the flexible liposomes showed a greater delivery of the fluorophore into the stratum corneum, indicating that they functioned as chemical permeability enhancers.

  6. On the possibility of high-velocity tidal sterams as dynamic barriers to longshore sediment transport: evidence from the continental shelf off the Gulf of Kutch, India

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, R.R.; Hashimi, N.H.; Rao, V.P.

    and clay minerals. The distinct differences have resulted because the high-velocity (2 to 2.5 knots) tidal stream at the gulf mouth acts as a dynamic barrier inhibiting sediment transport across the month. Differences in the distribution of sand size...

  7. Seasonal organic matter dynamics in the Great Barrier Reef lagoon: Contribution of carbohydrates and proteins

    Science.gov (United States)

    Lønborg, Christian; Doyle, Jason; Furnas, Miles; Menendez, Patricia; Benthuysen, Jessica A.; Carreira, Cátia

    2017-04-01

    Organic matter (OM) plays a fundamental role in sustaining the high productivity of coral reef ecosystems. Carbohydrates and proteins constitute two of the major chemical classes identified in the OM pool and are used as indicators of bioavailability due to their fast turn-over. We conducted three cruises across the southern shelf of the Great Barrier Reef (GBR) during the early dry, late dry and wet seasons in 2009-2010 to 1) assess the relative bioavailability of particulate (POM) and dissolved (DOM) organic matter, 2) track the temporal and spatial variability in the carbohydrate and protein contribution to the OM pool, and 3) assess factors influencing protein and carbohydrate fractions of the OM pool. Generally, higher concentrations of particulate carbohydrates were found during the wet season, while similar concentrations of particulate protein were found during the three seasons. Both the dissolved carbohydrates and proteins had highest levels during the early dry season and lowest during the wet season, suggesting seasonal variations in the chemical composition of the DOM pool. Spatially, carbohydrates showed higher concentrations at the inshore stations, while no clear spatial pattern was found for the protein concentrations. On average carbohydrates and proteins accounted for a similar fraction (13±5 and 12±6% respectively) of POM, while carbohydrates accounted for a smaller fraction of the DOM than the proteins (6±3 and 13±10%). This suggests that the POM bioavailability was similar between seasons, while the DOM bioavailability varied seasonally with highest levels during the early dry season. This demonstrates that carbohydrates and proteins in the GBR have temporal and spatial variations. Our statistical analysis showed that 1) both carbohydrates and proteins were related with the POM and DOM C:N:P stoichiometry, demonstrating that both bulk estimates (stoichiometry) and specific compounds (CHO and Prot) provide useful measures of OM

  8. PLATYPUS: A code for reaction dynamics of weakly-bound nuclei at near-barrier energies within a classical dynamical model

    Science.gov (United States)

    Diaz-Torres, Alexis

    2011-04-01

    A self-contained Fortran-90 program based on a three-dimensional classical dynamical reaction model with stochastic breakup is presented, which is a useful tool for quantifying complete and incomplete fusion, and breakup in reactions induced by weakly-bound two-body projectiles near the Coulomb barrier. The code calculates (i) integrated complete and incomplete fusion cross sections and their angular momentum distribution, (ii) the excitation energy distribution of the primary incomplete-fusion products, (iii) the asymptotic angular distribution of the incomplete-fusion products and the surviving breakup fragments, and (iv) breakup observables, such as angle, kinetic energy and relative energy distributions. Program summaryProgram title: PLATYPUS Catalogue identifier: AEIG_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEIG_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 332 342 No. of bytes in distributed program, including test data, etc.: 344 124 Distribution format: tar.gz Programming language: Fortran-90 Computer: Any Unix/Linux workstation or PC with a Fortran-90 compiler Operating system: Linux or Unix RAM: 10 MB Classification: 16.9, 17.7, 17.8, 17.11 Nature of problem: The program calculates a wide range of observables in reactions induced by weakly-bound two-body nuclei near the Coulomb barrier. These include integrated complete and incomplete fusion cross sections and their spin distribution, as well as breakup observables (e.g. the angle, kinetic energy, and relative energy distributions of the fragments). Solution method: All the observables are calculated using a three-dimensional classical dynamical model combined with the Monte Carlo sampling of probability-density distributions. See Refs. [1,2] for further details. Restrictions: The

  9. Examples of Department of Energy Successes for Remediation of Contaminated Groundwater: Permeable Reactive Barrier and Dynamic Underground Stripping ASTD Projects

    International Nuclear Information System (INIS)

    Purdy, C.; Gerdes, K.; Aljayoushi, J.; Kaback, D.; Ivory, T.

    2002-01-01

    Since 1998, the Department of Energy's (DOE) Office of Environmental Management has funded the Accelerated Site Technology Deployment (ASTD) Program to expedite deployment of alternative technologies that can save time and money for the environmental cleanup at DOE sites across the nation. The ASTD program has accelerated more than one hundred deployments of new technologies under 76 projects that focus on a broad spectrum of EM problems. More than 25 environmental restoration projects have been initiated to solve the following types of problems: characterization of the subsurface using chemical, radiological, geophysical, and statistical methods; treatment of groundwater contaminated with DNAPLs, metals, or radionuclides; and other projects such as landfill covers, purge water management systems, and treatment of explosives-contaminated soils. One of the major goals of the ASTD Program is to deploy a new technology or process at multiple DOE sites. ASTD projects are encouraged to identify subsequent deployments at other sites. Some of the projects that have successfully deployed technologies at multiple sites focusing on cleanup of contaminated groundwater include: Permeable Reactive Barriers (Monticello, Rocky Flats, and Kansas City), treating uranium and organics in groundwater; and Dynamic Underground Stripping (Portsmouth, and Savannah River), thermally treating DNAPL source zones. Each year more and more new technologies and approaches are being used at DOE sites due to the ASTD program. DOE sites are sharing their successes and communicating lessons learned so that the new technologies can replace the baseline or standard approaches at DOE sites, thus expediting cleanup and saving money

  10. Examples of Department of Energy Successes for Remediation of Contaminated Groundwater: Permeable Reactive Barrier and Dynamic Underground Stripping ASTD Projects

    Energy Technology Data Exchange (ETDEWEB)

    Purdy, C.; Gerdes, K.; Aljayoushi, J.; Kaback, D.; Ivory, T.

    2002-02-27

    Since 1998, the Department of Energy's (DOE) Office of Environmental Management has funded the Accelerated Site Technology Deployment (ASTD) Program to expedite deployment of alternative technologies that can save time and money for the environmental cleanup at DOE sites across the nation. The ASTD program has accelerated more than one hundred deployments of new technologies under 76 projects that focus on a broad spectrum of EM problems. More than 25 environmental restoration projects have been initiated to solve the following types of problems: characterization of the subsurface using chemical, radiological, geophysical, and statistical methods; treatment of groundwater contaminated with DNAPLs, metals, or radionuclides; and other projects such as landfill covers, purge water management systems, and treatment of explosives-contaminated soils. One of the major goals of the ASTD Program is to deploy a new technology or process at multiple DOE sites. ASTD projects are encouraged to identify subsequent deployments at other sites. Some of the projects that have successfully deployed technologies at multiple sites focusing on cleanup of contaminated groundwater include: Permeable Reactive Barriers (Monticello, Rocky Flats, and Kansas City), treating uranium and organics in groundwater; and Dynamic Underground Stripping (Portsmouth, and Savannah River), thermally treating DNAPL source zones. Each year more and more new technologies and approaches are being used at DOE sites due to the ASTD program. DOE sites are sharing their successes and communicating lessons learned so that the new technologies can replace the baseline or standard approaches at DOE sites, thus expediting cleanup and saving money.

  11. Spatial patterns in benthic communities and the dynamics of a mosaic ecosystem on the Great Barrier Reef, Australia

    Science.gov (United States)

    Ninio, R.; Meekan, M.

    2002-04-01

    The benthic communities of the Great Barrier Reef (GBR) have been characterized as a mosaic with patches at scales of tens to hundreds of kilometres formed by clusters of reefs with comparable environmental settings and histories of disturbance. We use data sets of changes in cover of abundant benthic organisms to examine the relationship between community composition and the dynamics of this mosaic. Our data were compiled from seven annual video surveys of permanent transects on the north-east flanks of up to 52 reefs at different shelf positions throughout most of the GBR. Classification analysis of these data sets identified three distinct groups of reefs, the first dominated by poritid hard corals and alcyoniid soft corals, the second by hard corals of the genus Acropora, and the third by xeniid soft corals. These groups underwent different amounts of change in cover during the period of our study. As acroporan corals are fast growing but susceptible to mortality due to predators and wave action, the group of reefs dominated by this genus displayed rapid rates of growth and loss of cover. In contrast, cover in the remaining groups changed very slowly or remained stable. Some evidence suggests that competition for space may limit growth of acroporan corals and thus rates of change in the group dominated by xeniid soft corals. These contrasting patterns imply that susceptibility to, and recovery from, disturbances such as cyclones, predators, and bleaching events will differ among these groups of reefs.

  12. Converse Barrier Certificate Theorem

    DEFF Research Database (Denmark)

    Wisniewski, Rafael; Sloth, Christoffer

    2013-01-01

    This paper presents a converse barrier certificate theorem for a generic dynamical system.We show that a barrier certificate exists for any safe dynamical system defined on a compact manifold. Other authors have developed a related result, by assuming that the dynamical system has no singular...... points in the considered subset of the state space. In this paper, we redefine the standard notion of safety to comply with generic dynamical systems with multiple singularities. Afterwards, we prove the converse barrier certificate theorem and illustrate the differences between ours and previous work...

  13. Converse Barrier Certificate Theorems

    DEFF Research Database (Denmark)

    Wisniewski, Rafael; Sloth, Christoffer

    2016-01-01

    This paper shows that a barrier certificate exists for any safe dynamical system. Specifically, we prove converse barrier certificate theorems for a class of structurally stable dynamical systems. Other authors have developed a related result by assuming that the dynamical system has neither...... singular points nor closed orbits. In this paper, we redefine the standard notion of safety to comply with dynamical systems with multiple singular elements. Hereafter, we prove the converse barrier certificate theorems and highlight the differences between our results and previous work by a number...

  14. Mapping of barley alpha-amylases and outer subsite mutants reveals dynamic high-affinity subsites and barriers in the long substrate binding cleft

    DEFF Research Database (Denmark)

    Kandra, L.; Abou Hachem, Maher; Gyemant, G.

    2006-01-01

    Subsite affinity maps of long substrate binding clefts in barley alpha-amylases, obtained using a series of maltooligosaccharides of degree of polymerization of 3-12, revealed unfavorable binding energies at the internal subsites -3 and -5 and at subsites -8 and +3/+4 defining these subsites...... as binding barriers. Barley a-amylase I mutants Y105A and T212Y at subsite -6 and +4 resulted in release or anchoring of bound substrate, thus modifying the affinities of other high-affinity subsites (-2 and +2) and barriers. The double mutant Y105A-T212Y displayed a hybrid subsite affinity profile......, converting barriers to binding areas. These findings highlight the dynamic binding energy distribution and the versatility of long maltooligosaccharide derivatives in mapping extended binding clefts in a-amylases....

  15. Dynamic, size-selective effects of protamine sulfate and hyaluronidase on the rat glomerular filtration barrier in vivo.

    Science.gov (United States)

    Sverrisson, Kristinn; Axelsson, Josefin; Rippe, Anna; Asgeirsson, Daniel; Rippe, Bengt

    2014-11-15

    The proteinuric actions of protamine sulfate (PS) have classically been, at least partly, attributed to alterations of the negatively charged glomerular endothelial glycocalyx. To investigate whether the charge-selective properties of the glomerular filtration barrier (GFB) would be altered by PS, we assessed the glomerular sieving of conventional, uncharged, polydispersed Ficoll (n-Ficoll) compared with charge modified, conformationally intact, anionic (carboxymethylated) Ficoll (a-Ficoll) before and after systemic infusions of PS in rats. For comparison, we also investigated the impact of hyaluronidase (hyase), which partially degrades the glycocalyx, on GFB permeability. In anaesthetized Wistar rats, blood access was achieved, and the left ureter was cannulated for urine collection. Rats were infused with either n-Ficoll or a-Ficoll before and during systemic infusions with either PS or hyase. Plasma and urine samples were taken repeatedly and analyzed by high-performance size exclusion chromatography to assess glomerular sieving coefficients (θ) for Ficoll (radius 10-80 Å). The GFB showed a significant glomerular charge selectivity for Ficoll molecules of radius 20-35 Å. PS and hyase infusions reversibly increased θ for large Ficoll molecules (Ficoll molecules of radius 50-80 Å). Thus, for PS, θ for a-Ficoll molecules of radius 70 Å increased from 2.47 × 10(-5) ± 1.1(-5) to 7.25 × 10(-5) ± 1.1(-5) (P < 0.05) at 15 min. For hyase, changes in a-Ficoll molecules of radius 50-80 Å were, however, not statistically significant. Neither PS nor hyase had any effect on θ for n-Ficoll molecules of radius 20-45 Å or a-Ficoll molecules of radius 20-45 Å. It is concluded that systemically administered PS and hyase in moderate doses dynamically decreased the size selectivity of the rat GFB without affecting its charge selective properties. Copyright © 2014 the American Physiological Society.

  16. The importance of large benthic foraminifera to reef island sediment budget and dynamics at Raine Island, northern Great Barrier Reef

    Science.gov (United States)

    Dawson, John L.; Smithers, Scott G.; Hua, Quan

    2014-10-01

    Low-lying reef islands are among the most vulnerable environments on earth to anthropogenic-induced climate change and sea-level rise over the next century because they are low, composed of unconsolidated sediment that is able to be mobilised by waves and currents, and depend on sediments supplied by reef organisms that are particularly sensitive to environmental changes (e.g. ocean temperatures and chemistry). Therefore, the spatial and temporal links between active carbonate production and island formation and dynamics are fundamental to predicting future island resilience, yet remain poorly quantified. In this paper we present results of a detailed geomorphological and sedimentological study of a reef and sand cay on the northern Great Barrier Reef. We provide an empirical investigation of the temporal linkages between sediment production and reef island development using a large collection of single grain AMS 14C dates. Large benthic foraminifera (LBF) are the single most important contributor to contemporary island sand mass (47%; ranging from 36% to 63%) at Raine Island, reflecting rapid rates of sediment production and delivery. Standing stock data reveal extremely high production rates on the reef (1.8 kg m- 2 yr- 1), while AMS 14C dates of single LBF tests indicate rapid rates of sediment transferral across the reef. We also demonstrate that age is statistically related to preservation and taphonomic grade (severely abraded tests > moderately abraded tests > pristine tests). We construct a contemporary reef and island sediment budget model for Raine Island that shows that LBF (Baculogypsina, Marginopora and Amphistegina) contribute 55% of the sediment produced on the reef annually, of which a large proportion (54%) contribute to the net annual accretion of the island. The tight temporal coupling between LBF growth and island sediment supply combined with the sensitivity of LBF to bleaching and ocean acidification suggests that islands dominated by LBF are

  17. Computational fluid dynamics modeling to assess the impact of roadside barriers on near-road air quality

    Science.gov (United States)

    Near-road air quality is an issue of emerging concern, with field studies consistently showing elevated air pollutant concentrations adjacent to major roads, usually decreasing to background levels within several hundred meters. Roadside barriers, both vegetative and structural, ...

  18. Combining substrate dynamics, binding statistics, and energy barriers to rationalize regioselective hydroxylation of octane and lauric acid by CYP102A1 and mutants.

    Science.gov (United States)

    Feenstra, K Anton; Starikov, Eugene B; Urlacher, Vlada B; Commandeur, Jan N M; Vermeulen, Nico P E

    2007-03-01

    Hydroxylations of octane and lauric acid by Cytochrome P450-BM3 (CYP102A1) wild-type and three active site mutants--F87A, L188Q/A74G, and F87V/L188Q/A74G--were rationalized using a combination of substrate orientation from docking, substrate binding statistics from molecular dynamics simulations, and barrier energies for hydrogen atom abstraction from quantum mechanical calculations. Wild-type BM3 typically hydroxylates medium- to long-chain fatty acids on subterminal (omega-1, omega-2, omega-3) but not the terminal (omega) positions. The known carboxylic anchoring site Y51/R47 for lauric acid, and hydrophobic interactions and steric exclusion, mainly by F87, for octane as well as lauric acid, play a role in the binding modes of the substrates. Electrostatic interactions between the protein and the substrate strongly modulate the substrate's regiodependent activation barriers. A combination of the binding statistics and the activation barriers of hydrogen-atom abstraction in the substrates is proposed to determine the product formation. Trends observed in experimental product formation for octane and lauric acid by wild-type BM3 and the three active site mutants were qualitatively explained. It is concluded that the combination of substrate binding statistics and hydrogen-atom abstraction barrier energies is a valuable tool to rationalize substrate binding and product formation and constitutes an important step toward prediction of product ratios.

  19. Influence of pairing correlations on the probability and dynamics of tunneling through the barrier in fission and fusion of complex nuclei

    International Nuclear Information System (INIS)

    Lazarev, Yu.A.

    1986-01-01

    An analytically solvable model is used to study the potential barrier penetrability in the case when the gap parameter Δ is treated as a dynamical variable governed by the least action principle. It is found that, as compared to the standard (BCS) approach, the dynamical treatment of pairing results in a considerably weakened dependence of the fission barrier penetrability on the intensity of pairing correlations in the initial state (Δ 0 ), on the barrier height, and on the energy of the initial state. On this basis, a more adequate explanation is proposed for typical order-of-magnitude values of the empirical hidrance factors for groun-state spontaneous fission of odd nuclei. It is also shown that a large enhancement of superfluidity in tunneling - the inherent effect of the dynamical treatment of pairing - strongly facilitates deeply subbarier fusion of complex nuclei. Finally, an analysis is given for the probability of spontaneous fission from K-isomeric quasiparticle (q-p) states in even-even heavy nuclei. The relative change of the partial spontaneous fission half-life in going from the ground-state to a high-spin q-p isomeric state, T* sf /T sf , is found to be strongly dependent on whether or not there takes place the dynamically induced enhancement of superfluidity in tunneling. Measurements of T* sf /T sf provide thus a unique possibility of verifying theoretical predictions about the strong, inverse-square Δ dependence of the effective inertia associated with large-scale subbarrier rearrangements of nuclei

  20. Quantum dynamics study of energy requirement on reactivity for the HBr + OH reaction with a negative-energy barrier

    Science.gov (United States)

    Wang, Yuping; Li, Yida; Wang, Dunyou

    2017-01-01

    A time-dependent, quantum reaction dynamics approach in full dimensional, six degrees of freedom was carried out to study the energy requirement on reactivity for the HBr + OH reaction with an early, negative energy barrier. The calculation shows both the HBr and OH vibrational excitations enhance the reactivity. However, even this reaction has a negative energy barrier, the calculation shows not all forms of energy are equally effective in promoting the reactivity. On the basis of equal amount of total energy, the vibrational energies of both the HBr and OH are more effective in enhancing the reactivity than the translational energy, whereas the rotational excitations of both the HBr and OH hinder the reactivity. The rate constants were also calculated for the temperature range between 5 to 500 K. The quantal rate constants have a better slope agreement with the experimental data than quasi-classical trajectory results.

  1. The interplay between interpersonal dynamics, treatment barriers, and larger social forces: an exploratory study of drug-using couples in Hartford, CT

    Directory of Open Access Journals (Sweden)

    Simmons Janie

    2006-05-01

    Full Text Available Abstract Background The drug treatment field tends to place emphasis on the individual rather than the individual in social context. While there are a growing number of studies indicating that drug-using intimate partners are likely to play an important role in determining treatment options, little attention has been given to the experience and complex treatment needs of illicit drug-using (heroin, cocaine, crack couples. Methods This exploratory study used in-depth interviews and ethnographic engagement to better understand the relationship between interpersonal dynamics and the treatment experience of ten relatively stable drug-using couples in Hartford, CT. Semi-structured and open-ended qualitative interviews were conducted with each couple and separately with each partner. Whenever possible, the day-to-day realities and contexts of risk were also observed via participant and non-participant observation of these couples in the community. A grounded theory approach was used to inductively code and analyze nearly 40 transcripts of 60–90 minute interviews as well as fieldnotes. Results This study builds on a concept of complex interpersonal dynamics among drug users. Interpersonal dynamics of care and collusion were identified: couples cared for each other and colluded to acquire and use drugs. Care and collusion operate at the micro level of the risk environment. Treatment barriers and inadequacies were identified as part of the risk environment at the meso or intermediate level of analysis, and larger social forces such as gender dynamics, poverty and the "War on Drugs" were identified at the macro level. Interpersonal dynamics posed problems for couples when one or both partners were interested in accessing treatment. Structural barriers presented additional obstacles with the denial of admittance of both partners to treatment programs which had a sole focus on the individual and avoided treating couples. Conclusion Detoxification and

  2. Hurricane Harvey rapid response: observations of infragravity wave dynamics and morphological change during inundation of a barrier island cut

    Science.gov (United States)

    Anarde, K.; Figlus, J.; Dellapenna, T. M.; Bedient, P. B.

    2017-12-01

    Prior to landfall of Hurricane Harvey on August 25, 2017, instrumentation was deployed on the seaward and landward sides of a barrier island on the central Texas Gulf Coast to collect in-situ hydrodynamic measurements during storm impact. High-resolution devices capable of withstanding extreme conditions included inexpensive pressure transducers and tilt current meters mounted within and atop (respectively) shallow monitoring wells. In order to link measurements of storm hydrodynamics with the morphological evolution of the barrier, pre- and post-storm digital elevation models were generated using a combination of unmanned aerial imagery, LiDAR, and real-time kinematic GPS. Push-cores were collected and analyzed for grain size and sedimentary structure to relate hydrodynamic observations with the local character of storm-generated deposits. Observations show that at Hog Island, located approximately 160 miles northeast of Harvey's landfall location, storm surge inundated an inactive storm channel. Infragravity waves (0.003 - 0.05 Hz) dominated the water motion onshore of the berm crest over a 24-hour period proximate to storm landfall. Over this time, approximately 50 cm of sediment accreted vertically atop the instrument located in the backshore. Storm deposits at this location contained sub-parallel alternating laminae of quartz and heavy mineral-enriched sand. While onshore progression of infragravity waves into the back-barrier was observed over several hours prior to storm landfall, storm deposits in the back-barrier lack the characteristic laminae preserved in the backshore. These field measurements will ultimately be used to constrain and validate numerical modeling schemes that explore morphodynamic conditions of barriers in response to extreme storms (e.g., XBeach, CSHORE). This study provides a unique data set linking extreme storm hydrodynamics with geomorphic changes during a relatively low surge, but highly dissipative wave event.

  3. Barrier Island Dynamics Using Mass Center Analysis: A New Way to Detect and Track Large-Scale Change

    Directory of Open Access Journals (Sweden)

    Paul Paris

    2014-01-01

    Full Text Available A geographic information system (GIS was used to introduce and test a new method for quantitatively characterizing topographic change. Borrowing from classic Newtonian mechanics, the concept of a body’s center of mass is applied to the geomorphic landscape, and the barrier island environment in particular, to evaluate the metric’s potential as a proxy for detecting, tracking and visualizing change. Two barrier islands along North Carolina’s Outer Banks are used to test this idea: Core Banks, uninhabited and largely-undeveloped, and Hatteras Island, altered by the presence of a protective dune system. Findings indicate that for Core Banks, the alongshore change in the center of mass is in accord with dominate littoral transport and wind conditions. Cross-shore change agrees with independent estimates for the island migration rates. This lends credence to our assertion that the mass center metric has the potential to be a viable proxy for describing wholesale barrier migration and would be a valuable addition to the already-established ocean shoreline and subaerial volume metrics. More research is, however, required to demonstrate efficacy.

  4. Recycler barrier RF buckets

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, C.M.; /Fermilab

    2011-03-01

    The Recycler Ring at Fermilab uses a barrier rf systems for all of its rf manipulations. In this paper, I will give an overview of historical perspective on barrier rf system, the longitudinal beam dynamics issues, aspects of rf linearization to produce long flat bunches and methods used for emittance measurements of the beam in the RR barrier rf buckets. Current rf manipulation schemes used for antiproton beam stacking and longitudinal momentum mining of the RR beam for the Tevatron collider operation are explained along with their importance in spectacular success of the Tevatron luminosity performance.

  5. Assessing blood brain barrier dynamics or identifying or measuring selected substances or toxins in a subject by analyzing Raman spectrum signals of selected regions in the eye

    Science.gov (United States)

    Lambert, James L. (Inventor); Borchert, Mark S. (Inventor)

    2003-01-01

    A non-invasive method for analyzing the blood-brain barrier includes obtaining a Raman spectrum of a selected portion of the eye and monitoring the Raman spectrum to ascertain a change to the dynamics of the blood brain barrier. Also, non-invasive methods for determining the brain or blood level of an analyte of interest, such as glucose, drugs, alcohol, poisons, and the like, comprises: generating an excitation laser beam (e.g., at a wavelength of 600 to 900 nanometers); focusing the excitation laser beam into the anterior chamber of an eye of the subject so that aqueous humor, vitreous humor, or one or more conjunctiva vessels in the eye is illuminated; detecting (preferably confocally detecting) a Raman spectrum from the illuminated portion of the eye; and then determining the blood level or brain level (intracranial or cerebral spinal fluid level) of an analyte of interest for the subject from the Raman spectrum. In certain embodiments, the detecting step may be followed by the step of subtracting a confounding fluorescence spectrum from the Raman spectrum to produce a difference spectrum; and determining the blood level and/or brain level of the analyte of interest for the subject from that difference spectrum, preferably using linear or nonlinear multivariate analysis such as partial least squares analysis. Apparatus for carrying out the foregoing methods are also disclosed.

  6. Building barriers.

    Science.gov (United States)

    Turksen, Kursad

    2017-10-02

    Formation of tissue barriers starts in early development where it is critical for normal cell fate selection, differentiation and organogenesis. Barrier maintenance is critical to the ongoing function of organs during adulthood and aging. Dysfunctional tissue barrier formation and function at any stage of the organismal life cycle underlies many disease states.

  7. Dynamic behavior of transport in normal and reversed shear plasmas with internal barriers in JT-60U

    International Nuclear Information System (INIS)

    Neudatchin, Sergi V.; Takizuka, Tomonori; Shirai, Hiroshi; Fujita, Takaaki; Isayama, Akihiko; Kamada, Yutaka; Koide, Yoshihiko

    2001-12-01

    Transport evolution in normal shear (NrS) and reversed shear (RS) JT-60U tokamak plasmas with internal transport barrier (ITB) is described as a combination of various fast and slow time scale processes. Abrupt in time (ms time scale) and wide in space (∼0.3 of minor radius) variations of electron and ion heat diffusivities χ e,i (δχ e,i ), which are called ITB-events and seen as simultaneous rise and decay of electron and ion temperatures in two spatial zones, are found for weak ITBs in both NrS and RS plasmas. Profiles of δχ e in RS plasmas with strong ITBs are usually localized near ITB foot inside smaller space region. The maximum of the heat flux variation is located near position of the minimum of safety factor in various RS plasmas, and variation is extended in positive shear region. Inward and outward heat pulse propagations created by the jump of χ e and the sawtooth-like crash are analyzed. Small values of χ e and the absence of heat pinch are found inside strong ITBs. Another non-local abrupt variations of χ e inside most of the plasma volume, including significant part of weak ITB inside RS zone of RS plasmas, are seen at the ELM-induced H-L transition and the L-H recovery. (author)

  8. Numerical investigation on the dynamics and evolution mechanisms of multiple-current-pulse behavior in homogeneous helium dielectric-barrier discharges at atmospheric pressure

    Science.gov (United States)

    Zhang, Yuhui; Ning, Wenjun; Dai, Dong

    2018-03-01

    A systematic investigation on the dynamics and evolution mechanisms of multiple-current-pulse (MCP) behavior in homogeneous dielectric barrier discharge (HDBD) is carried out via fluid modelling. Inspecting the simulation results, two typical discharge regimes, namely the MCP-Townsend regime and MCP-glow regime, are found prevailing in MCP discharges, each with distinctive electrical and dynamic properties. Moreover, the evolution of MCP behavior with external parameters altering are illustrated and explicitly discussed. It is revealed that the discharge undergoes some different stages as external parameters vary, and the discharge in each stage follows a series of distinctive pattern in morphological characteristics and evolution trends. Among those stages, the pulse number per half cycle is perceived to observe non-monotonic variations with applied voltage amplitude (Vam) and gap width (dg) increasing, and a merging effect among pulses, mainly induced by the enhanced contribution of sinusoidal component to the total current, is considered responsible for such phenomenon. The variation of incipient discharge peak phase (Φpm) is dominated by the value of Vam as well as the proportion of total applied voltage that drops across the gas gap. Moreover, an abnormal, dramatic elevation in Jpm with dg increasing is observed, which could be evinced by the strengthened glow discharge structure and therefore enhanced space charge effect.

  9. Numerical investigation on the dynamics and evolution mechanisms of multiple-current-pulse behavior in homogeneous helium dielectric-barrier discharges at atmospheric pressure

    Directory of Open Access Journals (Sweden)

    Yuhui Zhang

    2018-03-01

    Full Text Available A systematic investigation on the dynamics and evolution mechanisms of multiple-current-pulse (MCP behavior in homogeneous dielectric barrier discharge (HDBD is carried out via fluid modelling. Inspecting the simulation results, two typical discharge regimes, namely the MCP-Townsend regime and MCP-glow regime, are found prevailing in MCP discharges, each with distinctive electrical and dynamic properties. Moreover, the evolution of MCP behavior with external parameters altering are illustrated and explicitly discussed. It is revealed that the discharge undergoes some different stages as external parameters vary, and the discharge in each stage follows a series of distinctive pattern in morphological characteristics and evolution trends. Among those stages, the pulse number per half cycle is perceived to observe non-monotonic variations with applied voltage amplitude (Vam and gap width (dg increasing, and a merging effect among pulses, mainly induced by the enhanced contribution of sinusoidal component to the total current, is considered responsible for such phenomenon. The variation of incipient discharge peak phase (Φpm is dominated by the value of Vam as well as the proportion of total applied voltage that drops across the gas gap. Moreover, an abnormal, dramatic elevation in Jpm with dg increasing is observed, which could be evinced by the strengthened glow discharge structure and therefore enhanced space charge effect.

  10. Rapid survey protocol that provides dynamic information on reef condition to managers of the Great Barrier Reef.

    Science.gov (United States)

    Beeden, R J; Turner, M A; Dryden, J; Merida, F; Goudkamp, K; Malone, C; Marshall, P A; Birtles, A; Maynard, J A

    2014-12-01

    Managing to support coral reef resilience as the climate changes requires strategic and responsive actions that reduce anthropogenic stress. Managers can only target and tailor these actions if they regularly receive information on system condition and impact severity. In large coral reef areas like the Great Barrier Reef Marine Park (GBRMP), acquiring condition and impact data with good spatial and temporal coverage requires using a large network of observers. Here, we describe the result of ~10 years of evolving and refining participatory monitoring programs used in the GBR that have rangers, tourism operators and members of the public as observers. Participants complete Reef Health and Impact Surveys (RHIS) using a protocol that meets coral reef managers' needs for up-to-date information on the following: benthic community composition, reef condition and impacts including coral diseases, damage, predation and the presence of rubbish. Training programs ensure that the information gathered is sufficiently precise to inform management decisions. Participants regularly report because the demands of the survey methodology have been matched to their time availability. Undertaking the RHIS protocol we describe involves three ~20 min surveys at each site. Participants enter data into an online data management system that can create reports for managers and participants within minutes of data being submitted. Since 2009, 211 participants have completed a total of more than 10,415 surveys at more than 625 different reefs. The two-way exchange of information between managers and participants increases the capacity to manage reefs adaptively, meets education and outreach objectives and can increase stewardship. The general approach used and the survey methodology are both sufficiently adaptable to be used in all reef regions.

  11. Dynamics of seawater carbonate chemistry, production, and calcification of a coral reef flat, central Great Barrier Reef

    Directory of Open Access Journals (Sweden)

    R. Albright

    2013-10-01

    Full Text Available Ocean acidification is projected to shift coral reefs from a state of net accretion to one of net dissolution this century. Presently, our ability to predict global-scale changes to coral reef calcification is limited by insufficient data relating seawater carbonate chemistry parameters to in situ rates of reef calcification. Here, we investigate diel and seasonal trends in carbonate chemistry of the Davies Reef flat in the central Great Barrier Reef and relate these trends to benthic carbon fluxes by quantifying net ecosystem calcification (nec and net community production (ncp. Results show that seawater carbonate chemistry of the Davies Reef flat is highly variable over both diel and seasonal cycles. pH (total scale ranged from 7.92 to 8.17, pCO2 ranged from 272 to 542 μatm, and aragonite saturation state (Ωarag ranged from 2.9 to 4.1. Diel cycles in carbonate chemistry were primarily driven by ncp, and warming explained 35% and 47% of the seasonal shifts in pCO2 and pH, respectively. Daytime ncp averaged 37 ± 19 mmol C m−2 h−1 in summer and 33 ± 13 mmol C m−2 h−1 in winter; nighttime ncp averaged −30 ± 25 and −7 ± 6 mmol C m−2 h−1 in summer and winter, respectively. Daytime nec averaged 11 ± 4 mmol CaCO3 m−2 h−1 in summer and 8 ± 3 mmol CaCO3 m−2 h−1 in winter, whereas nighttime nec averaged 2 ± 4 mmol and −1 ± 3 mmol CaCO3 m−2 h−1 in summer and winter, respectively. Net ecosystem calcification was highly sensitive to changes in Ωarag for both seasons, indicating that relatively small shifts in Ωarag may drive measurable shifts in calcification rates, and hence carbon budgets, of coral reefs throughout the year.

  12. Ring flips revisited: (13)C relaxation dispersion measurements of aromatic side chain dynamics and activation barriers in basic pancreatic trypsin inhibitor.

    Science.gov (United States)

    Weininger, Ulrich; Modig, Kristofer; Akke, Mikael

    2014-07-22

    Intramolecular motions of proteins are critical for biological function. Transient structural fluctuations underlie a wide range of processes, including enzyme catalysis, ligand binding to buried sites, and generic protein motions, such as 180° rotation of aromatic side chains in the protein interior, but remain poorly understood. Understanding the dynamics and molecular nature of concerted motions requires characterization of their rates and energy barriers. Here we use recently developed (13)C transverse relaxation dispersion methods to improve our current understanding of aromatic ring flips in basic pancreatic trypsin inhibitor (BPTI). We validate these methods by benchmarking ring-flip rates against the three previously characterized cases in BPTI, namely, Y23, Y35, and F45. Further, we measure conformational exchange for one additional aromatic ring, F22, which can be interpreted in terms of a flip rate of 666 s(-1) at 5 °C. Upon inclusion of our previously reported result that Y21 also flips slowly [Weininger, U., et al. (2013) J. Phys. Chem. B 117, 9241-9247], the (13)C relaxation dispersion experiments thus reveal relatively slow ring-flip rates for five of eight aromatic residues in BPTI. These results are in contrast with previous reports, which have estimated that all rings, except Y23, Y35, and F45, flip with a high rate at ambient temperature. The (13)C relaxation dispersion data result in an updated rank order of ring-flip rates in BPTI, which agrees considerably better with that estimated from a recent 1 ms molecular dynamics trajectory than do previously published NMR data. However, significant quantitative differences remain between experiment and simulation, in that the latter yields flip rates that are in many cases too fast by 1-2 orders of magnitude. By measuring flip rates across a temperature range of 5-65 °C, we determined the activation barriers of ring flips for Y23, Y35, and F45. Y23 and F45 have identical activation parameters

  13. Measurement of brain perfusion, blood volume, and blood-brain barrier permeability, using dynamic contrast-enhanced T(1)-weighted MRI at 3 tesla.

    Science.gov (United States)

    Larsson, Henrik B W; Courivaud, Frédéric; Rostrup, Egill; Hansen, Adam E

    2009-11-01

    Assessment of vascular properties is essential to diagnosis and follow-up and basic understanding of pathogenesis in brain tumors. In this study, a procedure is presented that allows concurrent estimation of cerebral perfusion, blood volume, and blood-brain permeability from dynamic T(1)-weighted imaging of a bolus of a paramagnetic contrast agent passing through the brain. The methods are applied in patients with brain tumors and in healthy subjects. Perfusion was estimated by model-free deconvolution using Tikhonov's method (gray matter/white matter/tumor: 72 +/- 16/30 +/- 8/56 +/- 45 mL/100 g/min); blood volume (6 +/- 2/4 +/- 1/7 +/- 6 mL/100 g) and permeability (0.9 +/- 0.4/0.8 +/- 0.3/3 +/- 5 mL/100 g/min) were estimated by using Patlak's method and a two-compartment model. A corroboration of these results was achieved by using model simulation. In addition, it was possible to generate maps on a pixel-by-pixel basis of cerebral perfusion, cerebral blood volume, and blood-brain barrier permeability. (c) 2009 Wiley-Liss, Inc.

  14. Delineation and segmentation of cerebral tumors by mapping blood-brain barrier disruption with dynamic contrast-enhanced CT and tracer kinetics modeling-a feasibility study

    International Nuclear Information System (INIS)

    Bisdas, S.; Vogl, T.J.; Yang, X.; Koh, T.S.; Lim, C.C.T.

    2008-01-01

    Dynamic contrast-enhanced (DCE) imaging is a promising approach for in vivo assessment of tissue microcirculation. Twenty patients with clinical and routine computed tomography (CT) evidence of intracerebral neoplasm were examined with DCE-CT imaging. Using a distributed-parameter model for tracer kinetics modeling of DCE-CT data, voxel-level maps of cerebral blood flow (F), intravascular blood volume (v i ) and intravascular mean transit time (t 1 ) were generated. Permeability-surface area product (PS), extravascular extracellular blood volume (v e ) and extraction ratio (E) maps were also calculated to reveal pathologic locations of tracer extravasation, which are indicative of disruptions in the blood-brain barrier (BBB). All maps were visually assessed for quality of tumor delineation and measurement of tumor extent by two radiologists. Kappa (κ) coefficients and their 95% confidence intervals (CI) were calculated to determine the interobserver agreement for each DCE-CT map. There was a substantial agreement for the tumor delineation quality in the F, v e and t 1 maps. The agreement for the quality of the tumor delineation was excellent for the v i , PS and E maps. Concerning the measurement of tumor extent, excellent and nearly excellent agreement was achieved only for E and PS maps, respectively. According to these results, we performed a segmentation of the cerebral tumors on the base of the E maps. The interobserver agreement for the tumor extent quantification based on manual segmentation of tumor in the E maps vs. the computer-assisted segmentation was excellent (κ = 0.96, CI: 0.93-0.99). The interobserver agreement for the tumor extent quantification based on computer segmentation in the mean images and the E maps was substantial (κ = 0.52, CI: 0.42-0.59). This study illustrates the diagnostic usefulness of parametric maps associated with BBB disruption on a physiology-based approach and highlights the feasibility for automatic segmentation of

  15. Influence of a BGaN back-barrier on DC and dynamic performances of an AlGaN/GaN HEMT: simulation study

    Science.gov (United States)

    Guenineche, Lotfi; Hamdoune, Abdelkader

    2016-05-01

    In this paper, we study the effect of a BGaN back-barrier on the DC and RF performances of an AlGaN/GaN high electron mobility transistor. Using TCAD Silvaco, we examine some variations of thickness and boron concentration in the BGaN back-barrier layer. First, we fix the thickness of the back-barrier layer at 5 nm and we vary the concentration of the boron in BGaN from 1% to 4%. Second, we fix the concentration of the boron in BGaN to only 2% and we vary the thickness of the back-barrier layer from 20 nm to 110 nm. The BGaN back-barrier layer creates an electrostatic barrier under the channel layer and improves the performances of the device by improving the electron confinement in the two-dimensional electron gas. The DC and AC characteristics are improved, respectively, by a greater concentration of boron and by a thicker BGaN layer. For 4% boron concentration and 5 nm thick back-barrier layer, we obtain a maximum drain current of 1.1 A, a maximum transconductance of 480 mS mm-1, a cut-off frequency of 119 GHz, and a maximum oscillation frequency of 311 GHz.

  16. Histamine activates p38 MAP kinase and alters local lamellipodia dynamics, reducing endothelial barrier integrity and eliciting central movement of actin fibers

    Science.gov (United States)

    Adderley, Shaquria P.; Lawrence, Curtis; Madonia, Eyong; Olubadewo, Joseph O.

    2015-01-01

    The role of the actin cytoskeleton in endothelial barrier function has been debated for nearly four decades. Our previous investigation revealed spontaneous local lamellipodia in confluent endothelial monolayers that appear to increase overlap at intercellular junctions. We tested the hypothesis that the barrier-disrupting agent histamine would reduce local lamellipodia protrusions and investigated the potential involvement of p38 mitogen-activated protein (MAP) kinase activation and actin stress fiber formation. Confluent monolayers of human umbilical vein endothelial cells (HUVEC) expressing green fluorescent protein-actin were studied using time-lapse fluorescence microscopy. The protrusion and withdrawal characteristics of local lamellipodia were assessed before and after addition of histamine. Changes in barrier function were determined using electrical cell-substrate impedance sensing. Histamine initially decreased barrier function, lamellipodia protrusion frequency, and lamellipodia protrusion distance. A longer time for lamellipodia withdrawal and reduced withdrawal distance and velocity accompanied barrier recovery. After barrier recovery, a significant number of cortical fibers migrated centrally, eventually resembling actin stress fibers. The p38 MAP kinase inhibitor SB203580 attenuated the histamine-induced decreases in barrier function and lamellipodia protrusion frequency. SB203580 also inhibited the histamine-induced decreases in withdrawal distance and velocity, and the subsequent actin fiber migration. These data suggest that histamine can reduce local lamellipodia protrusion activity through activation of p38 MAP kinase. The findings also suggest that local lamellipodia have a role in maintaining endothelial barrier integrity. Furthermore, we provide evidence that actin stress fiber formation may be a reaction to, rather than a cause of, reduced endothelial barrier integrity. PMID:25948734

  17. Assessment of Blood-Brain Barrier Permeability by Dynamic Contrast-Enhanced MRI in Transient Middle Cerebral Artery Occlusion Model after Localized Brain Cooling in Rats

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun Soo [Department of Radiology, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang 14068 (Korea, Republic of); Lee, Seung-Koo [Department of Radiology, Yonsei University College of Medicine, Seoul 03722 (Korea, Republic of); Kwon, Mi Jung [Department of Pathology, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang 14068 (Korea, Republic of); Lee, Phil Hye [Department of Neurology, Yonsei University College of Medicine, Seoul 03722 (Korea, Republic of); Ju, Young-Su [Department of Industrial Medicine, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang 14068 (Korea, Republic of); Yoon, Dae Young [Department of Radiology, Hallym University Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul 05355 (Korea, Republic of); Kim, Hye Jeong [Department of Radiology, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul 07441 (Korea, Republic of); Lee, Kwan Seop [Department of Radiology, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang 14068 (Korea, Republic of)

    2016-11-01

    The purpose of this study was to evaluate the effects of localized brain cooling on blood-brain barrier (BBB) permeability following transient middle cerebral artery occlusion (tMCAO) in rats, by using dynamic contrast-enhanced (DCE)-MRI. Thirty rats were divided into 3 groups of 10 rats each: control group, localized cold-saline (20℃) infusion group, and localized warm-saline (37℃) infusion group. The left middle cerebral artery (MCA) was occluded for 1 hour in anesthetized rats, followed by 3 hours of reperfusion. In the localized saline infusion group, 6 mL of cold or warm saline was infused through the hollow filament for 10 minutes after MCA occlusion. DCE-MRI investigations were performed after 3 hours and 24 hours of reperfusion. Pharmacokinetic parameters of the extended Tofts-Kety model were calculated for each DCE-MRI. In addition, rotarod testing was performed before tMCAO, and on days 1-9 after tMCAO. Myeloperoxidase (MPO) immunohisto-chemistry was performed to identify infiltrating neutrophils associated with the inflammatory response in the rat brain. Permeability parameters showed no statistical significance between cold and warm saline infusion groups after 3-hour reperfusion 0.09 ± 0.01 min{sup -1} vs. 0.07 ± 0.02 min{sup -1}, p = 0.661 for K{sup trans}; 0.30 ± 0.05 min{sup -1} vs. 0.37 ± 0.11 min{sup -1}, p = 0.394 for kep, respectively. Behavioral testing revealed no significant difference among the three groups. However, the percentage of MPO-positive cells in the cold-saline group was significantly lower than those in the control and warm-saline groups (p < 0.05). Localized brain cooling (20℃) does not confer a benefit to inhibit the increase in BBB permeability that follows transient cerebral ischemia and reperfusion in an animal model, as compared with localized warm-saline (37℃) infusion group.

  18. Assessment of blood-brain barrier permeability by dynamic contrast-enhanced MRI in transient middle cerebral artery occlusion model after localized brain cooling in rats

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun Soo; Lee, Kwan Seop; Kwon, Mi Jung; Ju, Young Su [Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang (Korea, Republic of); Lee, Seung Koo; Lee, Phil Hye [Yonsei University College of Medicine, Seoul (Korea, Republic of); Yoon, Dae Young [Dept. of Radiology, Hallym University Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul (Korea, Republic of); Kim, Hye Jeong [Dept. of Radiology, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul (Korea, Republic of)

    2016-09-15

    The purpose of this study was to evaluate the effects of localized brain cooling on blood-brain barrier (BBB) permeability following transient middle cerebral artery occlusion (tMCAO) in rats, by using dynamic contrast-enhanced (DCE)-MRI. Thirty rats were divided into 3 groups of 10 rats each: control group, localized cold-saline (20 .deg. ) infusion group, and localized warm-saline (37 .deg. ) infusion group. The left middle cerebral artery (MCA) was occluded for 1 hour in anesthetized rats, followed by 3 hours of reperfusion. In the localized saline infusion group, 6 mL of cold or warm saline was infused through the hollow filament for 10 minutes after MCA occlusion. DCE-MRI investigations were performed after 3 hours and 24 hours of reperfusion. Pharmacokinetic parameters of the extended Tofts-Kety model were calculated for each DCE-MRI. In addition, rotarod testing was performed before tMCAO, and on days 1-9 after tMCAO. Myeloperoxidase (MPO) immunohisto-chemistry was performed to identify infiltrating neutrophils associated with the inflammatory response in the rat brain. Permeability parameters showed no statistical significance between cold and warm saline infusion groups after 3-hour reperfusion 0.09 ± 0.01 min{sup -1} vs. 0.07 ± 0.02 min{sup -1},p = 0.661 for K{sup trans}; 0.30 ± 0.05 min{sup -1} vs. 0.37 ± 0.11 min{sup -1},p = 0.394 for kep, respectively. Behavioral testing revealed no significant difference among the three groups. However, the percentage of MPO-positive cells in the cold-saline group was significantly lower than those in the control and warm-saline groups (p < 0.05). Localized brain cooling (20 .deg. ) does not confer a benefit to inhibit the increase in BBB permeability that follows transient cerebral ischemia and reperfusion in an animal model, as compared with localized warm-saline (37 .deg. ) infusion group.

  19. Assessment of Blood-Brain Barrier Permeability by Dynamic Contrast-Enhanced MRI in Transient Middle Cerebral Artery Occlusion Model after Localized Brain Cooling in Rats

    International Nuclear Information System (INIS)

    Kim, Eun Soo; Lee, Seung-Koo; Kwon, Mi Jung; Lee, Phil Hye; Ju, Young-Su; Yoon, Dae Young; Kim, Hye Jeong; Lee, Kwan Seop

    2016-01-01

    The purpose of this study was to evaluate the effects of localized brain cooling on blood-brain barrier (BBB) permeability following transient middle cerebral artery occlusion (tMCAO) in rats, by using dynamic contrast-enhanced (DCE)-MRI. Thirty rats were divided into 3 groups of 10 rats each: control group, localized cold-saline (20℃) infusion group, and localized warm-saline (37℃) infusion group. The left middle cerebral artery (MCA) was occluded for 1 hour in anesthetized rats, followed by 3 hours of reperfusion. In the localized saline infusion group, 6 mL of cold or warm saline was infused through the hollow filament for 10 minutes after MCA occlusion. DCE-MRI investigations were performed after 3 hours and 24 hours of reperfusion. Pharmacokinetic parameters of the extended Tofts-Kety model were calculated for each DCE-MRI. In addition, rotarod testing was performed before tMCAO, and on days 1-9 after tMCAO. Myeloperoxidase (MPO) immunohisto-chemistry was performed to identify infiltrating neutrophils associated with the inflammatory response in the rat brain. Permeability parameters showed no statistical significance between cold and warm saline infusion groups after 3-hour reperfusion 0.09 ± 0.01 min -1 vs. 0.07 ± 0.02 min -1 , p = 0.661 for K trans ; 0.30 ± 0.05 min -1 vs. 0.37 ± 0.11 min -1 , p = 0.394 for kep, respectively. Behavioral testing revealed no significant difference among the three groups. However, the percentage of MPO-positive cells in the cold-saline group was significantly lower than those in the control and warm-saline groups (p < 0.05). Localized brain cooling (20℃) does not confer a benefit to inhibit the increase in BBB permeability that follows transient cerebral ischemia and reperfusion in an animal model, as compared with localized warm-saline (37℃) infusion group

  20. Barrier island facies models and recognition criteria

    Science.gov (United States)

    Mulhern, J.; Johnson, C. L.

    2017-12-01

    Barrier island outcrops record transgressive shoreline motion at geologic timescales, providing integral clues to understanding how coastlines respond to rising sea levels. However, barrier island deposits are difficult to recognize. While significant progress has been made in understanding the modern coastal morphodynamics, this insight is not fully leveraged in existing barrier island facies models. Excellent outcrop exposures of the paralic Upper Cretaceous Straight Cliffs Formation of southern Utah provide an opportunity to revise facies models and recognition criteria for barrier island deposits. Preserved barrier islands are composed of three main architectural elements (shorefaces, tidal inlets, and tidal channels) which occur independently or in combination to create larger-scale barrier island deposits. Barrier island shorefaces record progradation, while barrier island tidal inlets record lateral migration, and barrier island tidal channels record aggradation within the tidal inlet. Four facies associations are used to describe and characterize these barrier island architectural elements. Barrier islands occur in association with backarrier fill and internally contain lower and upper shoreface, high-energy upper shoreface, and tidal channel facies. Barrier islands bound lagoons or estuaries, and are distinguished from other shoreface deposits by their internal facies and geometry, association with backbarrier facies, and position within transgressive successions. Tidal processes, in particular tidal inlet migration and reworking of the upper shoreface, also distinguish barrier island deposits. Existing barrier island models highlight the short term heterogeneous and dynamic nature of barrier island systems, yet overlook processes tied to geologic time scales, such as multi-directional motion, erosion, and reworking, and their expressions in preserved barrier island strata. This study uses characteristic outcrop expressions of barrier island successions to

  1. Dynamics

    CERN Document Server

    Goodman, Lawrence E

    2001-01-01

    Beginning text presents complete theoretical treatment of mechanical model systems and deals with technological applications. Topics include introduction to calculus of vectors, particle motion, dynamics of particle systems and plane rigid bodies, technical applications in plane motions, theory of mechanical vibrations, and more. Exercises and answers appear in each chapter.

  2. Fine-scale genetic breaks driven by historical range dynamics and ongoing density-barrier effects in the estuarine seaweed Fucus ceranoides L.

    Directory of Open Access Journals (Sweden)

    Neiva João

    2012-06-01

    Full Text Available Abstract Background Factors promoting the emergence of sharp phylogeographic breaks include restricted dispersal, habitat discontinuity, physical barriers, disruptive selection, mating incompatibility, genetic surfing and secondary contact. Disentangling the role of each in any particular system can be difficult, especially when species are evenly distributed across transition zones and dispersal barriers are not evident. The estuarine seaweed Fucus ceranoides provides a good example of highly differentiated populations along its most persistent distributional range at the present rear edge of the species distribution, in NW Iberia. Intrinsic dispersal restrictions are obvious in this species, but have not prevented F. ceranoides from vastly expanding its range northwards following the last glaciation, implying that additional factors are responsible for the lack of connectivity between neighbouring southern populations. In this study we analyze 22 consecutive populations of F. ceranoides along NW Iberia to investigate the processes generating and maintaining the observed high levels of regional genetic divergence. Results Variation at seven microsatellite loci and at mtDNA spacer sequences was concordant in revealing that Iberian F. ceranoides is composed of three divergent genetic clusters displaying nearly disjunct geographical distributions. Structure and AFC analyses detected two populations with an admixed nuclear background. Haplotypic diversity was high in the W sector and very low in the N sector. Within each genetic cluster, population structure was also pervasive, although shallower. Conclusions The deep divergence between sectors coupled with the lack of support for a role of oceanographic barriers in defining the location of breaks suggested 1 that the parapatric genetic sectors result from the regional reassembly of formerly vicariant sub-populations, and 2 that the genetic discontinuities at secondary contact zones (and elsewhere

  3. Storm impacts on small barrier islands

    DEFF Research Database (Denmark)

    Kroon, Aart; Fruergaard, Mikkel

    The shorelines of the Baltic Sea and the inner coastal waters in Denmark consist of many barrier islands. These sandy barrier islands were mainly formed in the Holocene and are still very dynamic. The present day changes in the morphology are dominantly governed by storm waves and associated high...... water levels. These storms induce collision, overwash or inundation of the barrier crest and generate wash-over fans and barrier breaching. In this presentation, we focus on the present-day morphologic evolution of these barrier islands, couple these to extreme events, and we will predict the potential...... changes in this evolution due to changes in the climate and associated sea levels. We analyzed the morphologic evolution of a series of barrier islands over the last decades using maps, aerial photographs and satellite images. This decadal morphologic evolution was coupled to the frequency and intensity...

  4. Combining substrate dynamics, binding statistics, and energy barriers to rationalize regioselective hydroxylation of octane and lauric acid by CYP102A1 and mutants

    NARCIS (Netherlands)

    Feenstra, K Anton; Starikov, Eugene B; Urlacher, Vlada B; Commandeur, Jan N M; Vermeulen, Nico P E

    Hydroxylations of octane and lauric acid by Cytochrome P450-BM3 (CYP102A1) wild-type and three active site mutants--F87A, L188Q/A74G, and F87V/L188Q/A74G--were rationalized using a combination of substrate orientation from docking, substrate binding statistics from molecular dynamics simulations,

  5. CLDN5 affects lncRNAs acting as ceRNA dynamics contributing to regulating blood‑brain barrier permeability in tumor brain metastasis.

    Science.gov (United States)

    Ma, Shun-Chang; Li, Qi; Peng, Jia-Yi; Zhouwen, Jian-Long; Zhang, Dai-Nan; Zhang, Chuan-Bao; Jiang, Wen-Guo; Jia, Wang

    2018-03-01

    The blood‑brain barrier (BBB) constitutes an efficient organization of tight junctions that limits the delivery of tumor to the brain. The principal tight junction protein in BBB is claudin‑5 (CLDN5), but its mechanism of action remains largely unknown. Long non‑coding RNAs (lncRNAs) are aberrantly expressed in many cancers, some lncRNAs play key roles in regulating BBB permeability and are involved in tumor brain metastasis. In particular, lncRNAs can function as competing endogenous RNAs (ceRNAs). Herein, we investigated whether ceRNA dysregulation is associated with alterations of the level of CLDN5 in human brain vascular endothelial hCMEC/D3 cells. The Affymetrix Human Transcriptome Array 2.0 and Affymetrix GeneChip miRNA 4.0 Array were used to detect the expression levels of 2,578 miRNAs, 22,829 lncRNAs, and 44,699 mRNAs in pLL3.7‑CLDN5‑transfected and pLL3.7 control hCMEC/D3 cells. The distinctly expressed miRNAs, lncRNAs, and mRNAs were subjected to construction of miRNA‑lncRNA‑mRNA interaction network. A total of 41 miRNAs, 954 lncRNAs, and 222 mRNAs were found to be differentially expressed between the CLDN5‑overexpressing and control group. 148 lncRNA acting as ceRNAs were identified based on the miRNA‑lncRNA‑mRNA interaction network. The function of differential mRNA in the network was determined by GO and pathway analysis. The potential roles of the 27 ceRNAs were revealed, the possible biology functions of these regulatory ceRNAs mainly included tight junction, focal adhesion, cell‑cell adhesion, cell growth and apoptosis. The identified sets of miRNAs, lncRNAs and mRNAs specific to CLDN5‑overexpressing hCMEC/D3 cells were verified by quantitative real‑time RT‑PCR experiment. Our study predicts the biological functions of a multitude of ceRNAs associated with the alteration of CLDN5 in brain vascular endothelial cells. Our data suggest that these dysregulated ceRNAs, in conjunction with the high CLDN5 levels, could serve

  6. BE-SONOS flash memory along with metal gate and high-k dielectrics in tunnel barrier and its impact on charge retention dynamics

    Science.gov (United States)

    Jain, Sonal; Gupta, Deepika; Neema, Vaibhav; Vishwakarma, Santosh

    2016-03-01

    We investigate the effect of a high-k dielectric in the tunnel layer to improve the erase speed-retention trade-off. Here, the proposed stack in the tunnel layer is AlLaO3/HfAlO/SiO2. These proposed materials possess low valence band offset with high permittivity to improve both the erase speed and retention time in barrier engineered silicon-oxide-nitride-oxide-silicon (BE-SONOS). In the proposed structure HfAlO and AlLaO3 replace Si3N4 and the top SiO2 layer in a conventional oxide/nitride/oxide (ONO) tunnel stack. Due to the lower conduction band offset (CBO) and high permittivity of the proposed material in the tunnel layer, it offers better program/erase (P/E) speed and retention time. In this work the gate length is also scaled down from 220 to 55 nm to observe the effect of high-k materials while scaling, for the same equivalent oxide thickness (EOT). We found that the scaling down of the gate length has a negligible impact on the memory window of the devices. Hence, various investigated tunnel oxide stacks possess a good memory window with a charge retained up to 87.4% (at room temperature) after a period of ten years. We also examine the use of a metal gate instead of a polysilicon gate, which shows improved P/E speed and retention time.

  7. BE-SONOS flash memory along with metal gate and high-k dielectrics in tunnel barrier and its impact on charge retention dynamics

    International Nuclear Information System (INIS)

    Jain, Sonal; Neema, Vaibhav; Gupta, Deepika; Vishwakarma, Santosh

    2016-01-01

    We investigate the effect of a high-k dielectric in the tunnel layer to improve the erase speed-retention trade-off. Here, the proposed stack in the tunnel layer is AlLaO 3 /HfAlO/SiO 2 . These proposed materials possess low valence band offset with high permittivity to improve both the erase speed and retention time in barrier engineered silicon-oxide-nitride-oxide-silicon (BE-SONOS). In the proposed structure HfAlO and AlLaO 3 replace Si 3 N 4 and the top SiO 2 layer in a conventional oxide/nitride/oxide (ONO) tunnel stack. Due to the lower conduction band offset (CBO) and high permittivity of the proposed material in the tunnel layer, it offers better program/erase (P/E) speed and retention time. In this work the gate length is also scaled down from 220 to 55 nm to observe the effect of high-k materials while scaling, for the same equivalent oxide thickness (EOT). We found that the scaling down of the gate length has a negligible impact on the memory window of the devices. Hence, various investigated tunnel oxide stacks possess a good memory window with a charge retained up to 87.4% (at room temperature) after a period of ten years. We also examine the use of a metal gate instead of a polysilicon gate, which shows improved P/E speed and retention time. (paper)

  8. Static and dynamic characteristics of Lg 50 nm InAlN/AlN/GaN HEMT with AlGaN back-barrier for high power millimeter wave applications

    Directory of Open Access Journals (Sweden)

    P. Murugapandiyan

    2017-12-01

    Full Text Available A novel 50 nm recessed T-gate AlN spacer based InAlN/GaN HEMT with AlGaN back-barrier is designed. The static and dynamic characteristics of the proposed device structure are investigated using Synopsys TCAD tool. The remarkable potential device features such as heavily doped source/drain region, Al2O3 passivated device surface helped the device to suppress the parasitic resistances and capacitances of the transistor for enhancing the microwave characteristics. The designed InAlN/GaN HEMT exhibits the sheet carrier density (ns of 1.9 × 1013 cm−2, the drain current density (Ids of 2.1 A/mm, the transconductance (gm of 800 mS/mm, the breakdown voltage (VBR of 40 V, the current gain cut-off frequency (ft of 221 GHz and the power gain cut-off frequency (fmax of 290 GHz. The superior static and dynamic characteristics of obtained InAlN/GaN HEMTs undoubtedly placed the device at the forefront for high power millimeter wave applications.

  9. Dynamic genome wide expression profiling of Drosophila head development reveals a novel role of Hunchback in retinal glia cell development and blood-brain barrier integrity.

    Directory of Open Access Journals (Sweden)

    Montserrat Torres-Oliva

    2018-01-01

    Full Text Available Drosophila melanogaster head development represents a valuable process to study the developmental control of various organs, such as the antennae, the dorsal ocelli and the compound eyes from a common precursor, the eye-antennal imaginal disc. While the gene regulatory network underlying compound eye development has been extensively studied, the key transcription factors regulating the formation of other head structures from the same imaginal disc are largely unknown. We obtained the developmental transcriptome of the eye-antennal discs covering late patterning processes at the late 2nd larval instar stage to the onset and progression of differentiation at the end of larval development. We revealed the expression profiles of all genes expressed during eye-antennal disc development and we determined temporally co-expressed genes by hierarchical clustering. Since co-expressed genes may be regulated by common transcriptional regulators, we combined our transcriptome dataset with publicly available ChIP-seq data to identify central transcription factors that co-regulate genes during head development. Besides the identification of already known and well-described transcription factors, we show that the transcription factor Hunchback (Hb regulates a significant number of genes that are expressed during late differentiation stages. We confirm that hb is expressed in two polyploid subperineurial glia cells (carpet cells and a thorough functional analysis shows that loss of Hb function results in a loss of carpet cells in the eye-antennal disc. Additionally, we provide for the first time functional data indicating that carpet cells are an integral part of the blood-brain barrier. Eventually, we combined our expression data with a de novo Hb motif search to reveal stage specific putative target genes of which we find a significant number indeed expressed in carpet cells.

  10. Dynamic Observation on Opening of the Blood-Brain Barrier in the Primary Stage of Severely Scalded Rabbits, a Multimodal Study.

    Science.gov (United States)

    Hu, Jun; Zhang, Yanwei; Ding, Shiyi; Li, Haitao

    2016-01-01

    The aim of this study was to characterize the opening of the blood-brain barrier (BBB) in the primary stage of 50% total burn surface area in third degree scalded rabbits. Thirty healthy male New Zealand white rabbits were randomly assigned to 1, 2, 3 and 4 hours post scald groups and an untreated control were used to establish a 50% total burn surface area third degree scalded model. I-labeled bovine serum albumin was used as a tracer to identify the earliest time point of BBB opening after a severe scald. Dual source CT and magnetic resonance imaging were used to visualize cerebral changes in vivo. Samples taken from the bilateral frontal, temporal, posterior cortex, cerebellum, brain stem, and basal ganglia were examined by light microscopy and transmission electron microscopy. Transmission electron microscopy observations confirmed that BBB had begun to open at 2 hours post scald. Intracellular edema of basal lamina and gliocytes, and the breakdown and an indistinct appearance of the tight junction of vascular endotheliocytes were observed at 3 hours post scald. A marked increase of I-labeled bovine serum albumin intake was recorded at 3 hours post scald in all parts of the brain. Significantly reduced apparent diffusion coefficient values calculated from diffusion-weighted imaging were measured at 4 hours post scald within region of interests in all parts of the brain applied on apparent diffusion coefficient images. No significant alteration was seen in CT, diffusion-weighted imaging, T1 or T2 weighted images. Opening of the BBB had begun at 2 hours post scald; ie, before the occurrence of edema. The results of this study suggest that opening of the BBB might be a prerequisite for brain edema.

  11. Dynamic monitoring of blood-brain barrier integrity using water exchange index (WEI) during mannitol and CO2 challenges in mouse brain.

    Science.gov (United States)

    Huang, Shuning; Farrar, Christian T; Dai, Guangping; Kwon, Seon Joo; Bogdanov, Alexei A; Rosen, Bruce R; Kim, Young R

    2013-04-01

    The integrity of the blood-brain barrier (BBB) is critical to normal brain function. Traditional techniques for the assessment of BBB disruption rely heavily on the spatiotemporal analysis of extravasating contrast agents. However, such methods based on the leakage of relatively large molecules are not suitable for the detection of subtle BBB impairment or for the performance of repeated measurements in a short time frame. Quantification of the water exchange rate constant (WER) across the BBB using strictly intravascular contrast agents could provide a much more sensitive method for the quantification of the BBB integrity. To estimate WER, we have recently devised a powerful new method using a water exchange index (WEI) biomarker and demonstrated BBB disruption in an acute stroke model. Here, we confirm that WEI is sensitive to even very subtle changes in the integrity of the BBB caused by: (i) systemic hypercapnia and (ii) low doses of a hyperosmolar solution. In addition, we have examined the sensitivity and accuracy of WEI as a biomarker of WER using computer simulation. In particular, the dependence of the WEI-WER relation on changes in vascular blood volume, T1 relaxation of cellular magnetization and transcytolemmal water exchange was explored. Simulated WEI was found to vary linearly with WER for typically encountered exchange rate constants (1-4 Hz), regardless of the blood volume. However, for very high WER (>5 Hz), WEI became progressively more insensitive to increasing WER. The incorporation of transcytolemmal water exchange, using a three-compartment tissue model, helped to extend the linear WEI regime to slightly higher WER, but had no significant effect for most physiologically important WERs (WER < 4 Hz). Variation in cellular T1 had no effect on WEI. Using both theoretical and experimental approaches, our study validates the utility of the WEI biomarker for the monitoring of BBB integrity. Copyright © 2012 John Wiley & Sons, Ltd.

  12. Dynamic genome wide expression profiling of Drosophila head development reveals a novel role of Hunchback in retinal glia cell development and blood-brain barrier integrity

    Science.gov (United States)

    Torres-Oliva, Montserrat; Schneider, Julia; Wiegleb, Gordon

    2018-01-01

    Drosophila melanogaster head development represents a valuable process to study the developmental control of various organs, such as the antennae, the dorsal ocelli and the compound eyes from a common precursor, the eye-antennal imaginal disc. While the gene regulatory network underlying compound eye development has been extensively studied, the key transcription factors regulating the formation of other head structures from the same imaginal disc are largely unknown. We obtained the developmental transcriptome of the eye-antennal discs covering late patterning processes at the late 2nd larval instar stage to the onset and progression of differentiation at the end of larval development. We revealed the expression profiles of all genes expressed during eye-antennal disc development and we determined temporally co-expressed genes by hierarchical clustering. Since co-expressed genes may be regulated by common transcriptional regulators, we combined our transcriptome dataset with publicly available ChIP-seq data to identify central transcription factors that co-regulate genes during head development. Besides the identification of already known and well-described transcription factors, we show that the transcription factor Hunchback (Hb) regulates a significant number of genes that are expressed during late differentiation stages. We confirm that hb is expressed in two polyploid subperineurial glia cells (carpet cells) and a thorough functional analysis shows that loss of Hb function results in a loss of carpet cells in the eye-antennal disc. Additionally, we provide for the first time functional data indicating that carpet cells are an integral part of the blood-brain barrier. Eventually, we combined our expression data with a de novo Hb motif search to reveal stage specific putative target genes of which we find a significant number indeed expressed in carpet cells. PMID:29360820

  13. 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.

  14. Safety-barrier diagrams

    DEFF Research Database (Denmark)

    Duijm, Nijs Jan

    2007-01-01

    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...

  15. Skin barrier function

    DEFF Research Database (Denmark)

    2016-01-01

    barrier integrity, factors influencing the penetration of the skin, influence of wet work, and guidance for prevention and saving the barrier. Distinguished researchers have contributed to this book, providing a comprehensive and thorough overview of the skin barrier function. Researchers in the field...... on the subject. It covers new basic research on skin markers, including results on filaggrin and on methods for the assessment of the barrier function. Biological variation and aspects of skin barrier function restoration are discussed as well. Further sections are dedicated to clinical implications of skin...

  16. Safety- barrier diagrams

    DEFF Research Database (Denmark)

    Duijm, Nijs Jan

    2008-01-01

    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 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...

  17. 3-methylcyclohexanone thiosemicarbazone: determination of E/Z isomerization barrier by dynamic high-performance liquid chromatography, configuration assignment and theoretical study of the mechanisms involved by the spontaneous, acid and base catalyzed processes.

    Science.gov (United States)

    Carradori, Simone; Cirilli, Roberto; Dei Cicchi, Simona; Ferretti, Rosella; Menta, Sergio; Pierini, Marco; Secci, Daniela

    2012-12-21

    Here, we report on the simultaneous direct HPLC diastereo- and enantioseparation of 3-methylcyclohexanone thiosemicarbazone (3-MCET) on a polysaccharide-based chiral stationary phase under normal-phase conditions. The optimized chromatographic system was employed in dynamic HPLC experiments (DHPLC), as well as detection technique in a batch wise approach to determine the rate constants and the corresponding free energy activation barriers of the spontaneous, base- and acid-promoted E/Z diastereomerization of 3-MCET. The stereochemical characterization of four stereoisomers of 3-MCET was fully accomplished by integrating the results obtained by chemical correlation method with those derived by theoretical calculations and experimental investigations of circular dichroism (CD). As a final goal, a deepened analysis of the perturbing effect exercised by the stationary phase on rate constant values measured through DHPLC determinations as a function of the chromatographic separation factor α of the interconverting species was successfully accomplished. This revealed quite small deviations from the equivalent kinetic values obtained by off-column batch wise procedure, and suggested a possible effective correction of rate constants measured by DHPLC approach. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. 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 network...... analysis with operational safety management.......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...

  19. 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.

  20. Stochastic transport of particles across single barriers

    International Nuclear Information System (INIS)

    Kreuter, Christian; Siems, Ullrich; Henseler, Peter; Nielaba, Peter; Leiderer, Paul; Erbe, Artur

    2012-01-01

    Transport phenomena of interacting particles are of high interest for many applications in biology and mesoscopic systems. Here we present measurements on colloidal particles, which are confined in narrow channels on a substrate and interact with a barrier, which impedes the motion along the channel. The substrate of the particle is tilted in order for the particles to be driven towards the barrier and, if the energy gained by the tilt is large enough, surpass the barrier by thermal activation. We therefore study the influence of this barrier as well as the influence of particle interaction on the particle transport through such systems. All experiments are supported with Brownian dynamics simulations in order to complement the experiments with tests of a large range of parameter space which cannot be accessed in experiments.

  1. Thermal barriers for compartments

    Science.gov (United States)

    Kreutzer, Cory J.; Lustbader, Jason A.

    2017-10-17

    An aspect of the present disclosure is a thermal barrier that includes a core layer having a first surface, a second surface, and a first edge, and a first outer layer that includes a third surface and a second edge, where the third surface substantially contacts the first surface, the core layer is configured to minimize conductive heat transfer through the barrier, and the first outer layer is configured to maximize reflection of light away from the barrier.

  2. Tunnel barrier schottky

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Rongming; Cao, Yu; Li, Zijian; Williams, Adam J.

    2018-02-20

    A diode includes: a semiconductor substrate; a cathode metal layer contacting a bottom of the substrate; a semiconductor drift layer on the substrate; a graded aluminum gallium nitride (AlGaN) semiconductor barrier layer on the drift layer and having a larger bandgap than the drift layer, the barrier layer having a top surface and a bottom surface between the drift layer and the top surface, the barrier layer having an increasing aluminum composition from the bottom surface to the top surface; and an anode metal layer directly contacting the top surface of the barrier layer.

  3. Continuously monitored barrier options under Markov processes

    NARCIS (Netherlands)

    Mijatović, A.; Pistorius, M.

    2011-01-01

    In this paper, we present an algorithm for pricing barrier options in one-dimensional Markov models. The approach rests on the construction of an approximating continuous-time Markov chain that closely follows the dynamics of the given Markov model. We illustrate the method by implementing it for a

  4. Determination of the cis-trans isomerization barriers of L-alanyl-L-proline in aqueous solutions and at water/hydrophobic interfaces by on-line temperature-jump relaxation HPLC and dynamic on-column reaction HPLC.

    Science.gov (United States)

    Shibukawa, Masami; Miyake, Ayaka; Eda, Sayaka; Saito, Shingo

    2015-09-15

    Proline cis-trans isomerization is known to play a key role in the rate-determining steps of protein folding. It is thus very important to understand the influence of environments, not only bulk solutions but also microenvironments such as interfaces, on the isomerization reaction of proline peptides. Here we present two HPLC methods for measurements of kinetic and equilibrium parameters for the isomerization reactions in bulk solutions and at liquid/solid interfaces. On-line temperature-jump relaxation HPLC (T-jump HPLC) allows the determination of forward and reverse rate constants of the isomerization in a bulk solution by monitoring the whole time course of conversion of pure isomers from both sides of the reaction, in contrast to other HPLC and capillary zone electrophoresis as well as spectrometric and calorimetric methods, which use a mixture of the isomers. We can then determine cis-trans isomerization barriers of the peptide at liquid/solid interfaces from the kinetic data obtained by dynamic on-column reaction HPLC and T-jump HPLC. We observed that the interconversion around the peptide bond for l-alanyl-l-proline (Ala-Pro) in water is accelerated at the surfaces of an alkyl-bonded silica and a poly(styrene-divinylbenzene) copolymer resin, and this is caused by a remarkable decrease in the enthalpy of activation. The molecular structures of the cis and trans forms of Ala-Pro estimated by quantum mechanics calculation reveal that an equilibrium shift toward the cis form as well as the rapid isomerization of Ala-Pro at the water/hydrophobic interfaces can be attributed to the lower polarity of the interfacial water at the surfaces of the hydrophobic materials compared to that of bulk water.

  5. 7Li breakup polarization potential at near barrier energies

    International Nuclear Information System (INIS)

    Lubian, J. . E-mail lubian@if.uff.br; Correa, T.; Paes, B.; Figueira, J.M.; Abriola, D.; Fernandez Niello, J.O.; Arazi, A.; Capurro, O.A.; de Barbara, E.; Marti, G.V.; Martinez Heinmann, D.; Negri, A.E.; Pacheco, A.J.; Padron, I.; Gomes, P.R.S.

    2007-01-01

    Inelastic and one neutron transfer cross sections at energies around the Coulomb barrier were used to derive dynamic polarization potential (DPP) for the 7 Li + 27 Al system. The DPP due to breakup, obtained in a simple way, indicates that its real part is repulsive at near barrier energies

  6. Record dynamics

    DEFF Research Database (Denmark)

    Robe, Dominic M.; Boettcher, Stefan; Sibani, Paolo

    2016-01-01

    When quenched rapidly beyond their glass transition, colloidal suspensions fall out of equilibrium. The pace of their dynamics then slows down with the system age, i.e., with the time elapsed after the quench. This breaking of time translational invariance is associated with dynamical observables......-facto irreversible and become increasingly harder to achieve. Thus, a progression of record-sized dynamical barriers are traversed in the approach to equilibration. Accordingly, the statistics of the events is closely described by a log-Poisson process. Originally developed for relaxation in spin glasses...

  7. Transforming Education: Overcoming Barriers.

    Science.gov (United States)

    David, Jane L.; Goren, Paul D.

    Barriers to progress in educational reform exist inside and outside the education system. Some arise where new practices encounter traditional expectations and boundaries, but others go much deeper than education, such as poverty, racism, local political conflicts, and human resistance to change. The following five categories of barriers are…

  8. Catalytic thermal barrier coatings

    Science.gov (United States)

    Kulkarni, Anand A.; Campbell, Christian X.; Subramanian, Ramesh

    2009-06-02

    A catalyst element (30) for high temperature applications such as a gas turbine engine. The catalyst element includes a metal substrate such as a tube (32) having a layer of ceramic thermal barrier coating material (34) disposed on the substrate for thermally insulating the metal substrate from a high temperature fuel/air mixture. The ceramic thermal barrier coating material is formed of a crystal structure populated with base elements but with selected sites of the crystal structure being populated by substitute ions selected to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a higher rate than would the base compound without the ionic substitutions. Precious metal crystallites may be disposed within the crystal structure to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a lower light-off temperature than would the ceramic thermal barrier coating material without the precious metal crystallites.

  9. Near-Surface Engineered Environmental Barrier Integrity

    International Nuclear Information System (INIS)

    Piet, S.J.; Breckenridge, R.P.

    2002-01-01

    The INEEL Environmental Systems Research and Analysis (ESRA) program has launched a new R and D project on Near-Surface Engineered Environmental Barrier Integrity to increase knowledge and capabilities for using engineering and ecological components to improve the integrity of near-surface barriers used to confine contaminants from the public and the environment. The knowledge gained and the capabilities built will help verify the adequacy of past remedial decisions and enable improved solutions for future cleanup decisions. The research is planned to (a) improve the knowledge of degradation mechanisms (weathering, biological, geological, chemical, radiological, and catastrophic) in times shorter than service life, (b) improve modeling of barrier degradation dynamics, (c) develop sensor systems to identify degradation prior to failure, and (d) provide a better basis for developing and testing of new barrier systems to increase reliability and reduce the risk of failure. Our project combine s selected exploratory studies (benchtop and field scale), coupled effects accelerated aging testing and the meso-scale, testing of new monitoring concepts, and modeling of dynamic systems. The performance of evapo-transpiration, capillary, and grout-based barriers will be examined

  10. 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

  11. Compositional Safety Analysis using Barrier Certificates

    DEFF Research Database (Denmark)

    Sloth, Christoffer; Pappas, George J.; Wisniewski, Rafael

    2012-01-01

    This paper proposes a compositional method for verifying the safety of a dynamical system, given as an interconnection of subsystems. The safety verification is conducted by the use of the barrier certificate method; hence, the contribution of this paper is to show how to obtain compositional...... conditions for safety verification. We show how to formulate the verification problem, as a composition of coupled subproblems, each given for one subsystem. Furthermore, we show how to find the compositional barrier certificates via linear and sum of squares programming problems. The proposed method makes...

  12. Optimistic barrier synchronization

    Science.gov (United States)

    Nicol, David M.

    1992-01-01

    Barrier synchronization is fundamental operation in parallel computation. In many contexts, at the point a processor enters a barrier it knows that it has already processed all the work required of it prior to synchronization. The alternative case, when a processor cannot enter a barrier with the assurance that it has already performed all the necessary pre-synchronization computation, is treated. The problem arises when the number of pre-sychronization messages to be received by a processor is unkown, for example, in a parallel discrete simulation or any other computation that is largely driven by an unpredictable exchange of messages. We describe an optimistic O(log sup 2 P) barrier algorithm for such problems, study its performance on a large-scale parallel system, and consider extensions to general associative reductions as well as associative parallel prefix computations.

  13. Barrier Infrared Detector (BIRD)

    Data.gov (United States)

    National Aeronautics and Space Administration — A recent breakthrough in MWIR detector design, has resulted in a high operating temperature (HOT) barrier infrared detector (BIRD) that is capable of spectral...

  14. Protective barrier development: Overview

    International Nuclear Information System (INIS)

    Wing, N.R.; Gee, G.W.

    1990-01-01

    Protective barrier and warning marker systems are being developed to isolate wastes disposed of near the earth's surface at the Hanford Site. The barrier is designed to function in an arid to semiarid climate, to limit infiltration and percolation of water through the waste zone to near-zero, to be maintenance free, and to last up to 10,000 yr. Natural materials (e.g., fine soil, sand, gravel, riprap, clay, asphalt) have been selected to optimize barrier performance and longevity and to create an integrated structure with redundant features. These materials isolate wastes by limiting water drainage; reducing the likelihood of plant, animal, and human intrusion; controlling emission of noxious gases; and minimizing erosion. Westinghouse Hanford Company and Pacific Northwest Laboratory efforts to assess the performance of various barrier and marker designs will be discussed

  15. The progression of replication forks at natural replication barriers in live bacteria

    NARCIS (Netherlands)

    Moolman, M.C.; Tiruvadi Krishnan, S; Kerssemakers, J.W.J.; de Leeuw, R.; Lorent, V.J.F.; Sherratt, David J.; Dekker, N.H.

    2016-01-01

    Protein-DNA complexes are one of the principal barriers the replisome encounters during replication. One such barrier is the Tus-ter complex, which is a direction dependent barrier for replication fork progression. The details concerning the dynamics of the replisome when encountering these

  16. Barrier transgression driven by aeolian processes along the Portuguese coast

    Science.gov (United States)

    Costas, Susana; Ferreira, Óscar; Roelvink, Dano

    2017-04-01

    Coastal barriers around the world developed following sea level stabilization about 7000 years ago. Along the Southwestern European coast, this fact was largely supported by recent works exploring the sedimentary record of coastal lagoons and estuaries. However, direct evidences of barrier evolution/age obtained from the actual coastal barriers are rare, limiting our understanding about the dynamics and life time of these systems at long time scales. Here, we reconstruct the evolution of three coastal barriers located along the western Portuguese coast, determining their age, trends and life cycles. For that, we integrate information (stratigraphy and ages) from different coastal deposits indicative of major shifts on evolutionary trends, including published and unpublished data. Examined beach deposits set the age of the explored sand barriers between 6400 and 300 years ago, suggesting the coexistence of very mature and very recent coastal barriers. In addition, the results document the occurrence of transgressive dunefields with ages older than the preserved coastal barriers, supporting the existence of former barriers from which the dunes could derive and migrate inland. The latter suggests the occurrence of episodes of barrier building and shoreline progradation alternating with episodes of inland migration of transgressive dunefields and thus barrier rollover. Resultant trends are carefully examined to identify the major factors driving barrier evolution, with special attention to climate variability and local boundary conditions. Indeed, the episodic response of the explored sand barriers provides indications for shifting wave and wind conditions as a consequence of climate variability. Additionally, inter-site comparison provides significant insights into regional trends and allows rating the identified factors, based on the degree of direct influence over the evolution of the coast. In this regard, the exposure to wind and wave climate, usually linked to

  17. Understanding and predicting decadal behaviour of sandy barriers

    Science.gov (United States)

    Cooper, Andrew

    2017-04-01

    Developing geological/morphodynamic models of geomorphic systems involves the identification of common attributes from numerous examples or case studies and the distillation away of local variability. Barrier and barrier island systems share many common features, but there is a wide range of variability that strongly influences how they behave at historical timescales. Much morphodynamic modelling is centred on the relationship between dynamic driving forces on the one hand, and geomorphic response on the other. Some models take into account the feedback that exists between these. Less often considered are factors related to sediment volume and supply, underlying geology and the geological setting, and self-organization. Consideration of 'unusual' barrier island systems, where one or more of these factors is particularly important, highlights their role in barrier behaviour. Barrier islands on bedrock in Scotland demonstrate a primary control on evolution of antecedent topography. The low volume of sand in barrier islands in Chesapeake Bay is primarily responsible for very rapid migration rates. Episodic fluvial sediment supply to some South African barriers controls their historical scale behaviour. The high volume of sand in southern Brazil Barriers is a major constraint on their morphological evolution. These and other examples highlight the importance of factors that are often regarded as 'noise' in morphodynamic modelling. The nature of 'local variability' in barriers and barrier islands is diverse, but its important, and even dominant role in their evolution, urges caution in the application of generic modellling approaches in predicting future shoreline behavior.

  18. Religious culture as a barrier?

    DEFF Research Database (Denmark)

    Agergaard, Sine

    2016-01-01

    Political interventions, media coverage and research often refer to the underrepresentation of ethnic minorities, particularly girls and women, participating in physical activity and organised sports. In both public and academic debates, reference is made to the religious culture as a particular...... barrier to participation in sports among Muslim girls and women. This article aims to provide a counter-narrative by focusing on young Muslim girls who simultaneously practice their religion and sports. The main research question was: How do young Danish Muslim girls align participation in sports...... religion as hegemonic, embodied and dynamic cultural phenomena, the analysis points to the diversity through which Muslim girls and women participate and engage in sports. Finally, the article discusses the extent to which counter-narratives may contribute to changing perspectives on so-called hard...

  19. 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.

  20. Intestinal Barrier and Behavior.

    Science.gov (United States)

    Julio-Pieper, M; Bravo, J A

    2016-01-01

    The intestinal barrier function contributes to gut homeostasis by modulating absorption of water, electrolytes, and nutrients from the lumen into the circulation while restricting the passage of noxious luminal substances and microorganisms. Chronic conditions such as rheumatoid arthritis, inflammatory bowel disease, and celiac disease are associated to intestinal barrier dysfunction. Here, the hypothesis is that a leaky intestinal wall allowing for indiscriminate passage of intraluminal compounds to the vascular compartment could in turn lead to systemic inflammation. An increasing number of studies are now investigating the association between gut permeability and CNS disorders, under the premise that translocation of intestinal luminal contents could affect CNS function, either directly or indirectly. Still, it is unknown whether disruption of intestinal barrier is a causative agent or a consequence in these situations. Here, we discuss the latest evidence pointing to an association between increased gut permeability and disrupted behavioral responses. © 2016 Elsevier Inc. All rights reserved.

  1. Skin barrier in rosacea*

    Science.gov (United States)

    Addor, Flavia Alvim Sant'Anna

    2016-01-01

    Recent studies about the cutaneous barrier demonstrated consistent evidence that the stratum corneum is a metabolically active structure and also has adaptive functions, may play a regulatory role in the inflammatory response with activation of keratinocytes, angiogenesis and fibroplasia, whose intensity depends primarily on the intensity the stimulus. There are few studies investigating the abnormalities of the skin barrier in rosacea, but the existing data already show that there are changes resulting from inflammation, which can generate a vicious circle caused a prolongation of flare-ups and worsening of symptoms. This article aims to gather the most relevant literature data about the characteristics and effects of the state of the skin barrier in rosacea. PMID:26982780

  2. Health Barriers to Learning

    Directory of Open Access Journals (Sweden)

    Delaney Gracy

    2014-01-01

    Full Text Available This article summarizes the results from a 2013 online survey with 408 principals and assistant principals in New York City public elementary and middle schools. The survey assessed three primary areas: health issues in the school, health issues perceived as barriers to learning for affected students, and resources needed to address these barriers. Eighteen of the 22 health conditions listed in the survey were considered a moderate or serious issue within their schools by at least 10% of respondents. All 22 of the health issues were perceived as a barrier to learning by between 12% and 87% of the respondents. Representatives from schools that serve a higher percentage of low-income students reported significantly higher levels of concern about the extent of health issues and their impact on learning. Respondents most often said they need linkages with organizations that can provide additional services and resources at the school, especially for mental health.

  3. Chaos near the Coulomb barrier. Nuclear molecules

    International Nuclear Information System (INIS)

    Strayer, M.R.

    1984-01-01

    The present work examines in detail the classical behavior of the α + 14 C and the 12 C + 12 C(O + ) collison at energies near the Coulomb barrier. The long-time motion of the compound nuclear system is identified in terms of its classical quasiperiodic and chaotic behavior. The consequences of this motion are discussed and interpreted in terms of the evolution of the system along a dynamical energy surface. 45 references

  4. Crossing the Salt Barrier

    Indian Academy of Sciences (India)

    Fry. RIVER. To cross the salt barrier is, therefore, an obligatory part of every amphihaline fish cycle. Figure 2a. Life Cycle of. Salmon. Adult salmon migrate from sea towards the river. After reaching their hatching ground, the eggs are laid in the gravel. The spawned fishes are called kelts. Alevin is a stage from hatching to fry.

  5. Great Barrier Reef

    Science.gov (United States)

    2002-01-01

    A better than average view of the Great Barrier Reef was captured by SeaWiFS on a recent overpass. There is sunglint northeast of the reef and there appears to be some sort of filamentous bloom in the Capricorn Channel.

  6. Sound trapping and dredging barriers.

    Science.gov (United States)

    Wang, Xu; Wang, Xiaonan; Yu, Wuzhou; Jiang, Zaixiu; Mao, Dongxing

    2017-06-01

    When sound barriers are installed on both sides of a noise source, degradation in performance is observed. Barriers having negative-phase-gradient surfaces successfully eliminate this drawback by trapping sound energy in between the barriers. In contrast, barriers can also be designed to "dredge" the energy flux out. An extended model considering higher-order diffractions, which resulted from the interplay of the induced surface wave and barrier surface periodicity, is presented. It is found that the sound dredging barriers provide a remarkable enhancement over the trapping ones, and hence have the potential to be widely used in noise control engineering.

  7. 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

  8. Apoplastic Diffusion Barriers in Arabidopsis

    Science.gov (United States)

    Schreiber, Lukas; Franke, Rochus Benni; Geldner, Niko; Reina-Pinto, José J.; Kunst, Ljerka

    2013-01-01

    During the development of Arabidopsis and other land plants, diffusion barriers are formed in the apoplast of specialized tissues within a variety of plant organs. While the cuticle of the epidermis is the primary diffusion barrier in the shoot, the Casparian strips and suberin lamellae of the endodermis and the periderm represent the diffusion barriers in the root. Different classes of molecules contribute to the formation of extracellular diffusion barriers in an organ- and tissue-specific manner. Cutin and wax are the major components of the cuticle, lignin forms the early Casparian strip, and suberin is deposited in the stage II endodermis and the periderm. The current status of our understanding of the relationships between the chemical structure, ultrastructure and physiological functions of plant diffusion barriers is discussed. Specific aspects of the synthesis of diffusion barrier components and protocols that can be used for the assessment of barrier function and important barrier properties are also presented. PMID:24465172

  9. Performance of engineered barriers

    International Nuclear Information System (INIS)

    Rajaram, V.; Dean, P.V.; McLellan, S.A.

    1997-01-01

    Engineered barriers, both vertical and horizontal, have been used to isolate hazardous wastes from contact, precipitation, surface water and groundwater. The primary objective of this study was to determine the performance of subsurface barriers installed throughout the U.S. over the past 20 years to contain hazardous wastes. Evaluation of Resource Conservation and Recovery Act (RCRA) Subtitle C or equivalent caps was a secondary objective. A nationwide search was launched to select hazardous waste sites at which vertical barrier walls and/or caps had been used as the containment method. None of the sites selected had an engineered floor. From an initial list of 130 sites, 34 sites were selected on the basis of availability of monitoring data for detailed analysis of actual field performance. This paper will briefly discuss preliminary findings regarding the design, construction quality assurance/construction quality control (CQA/CQC), and monitoring at the 34 sites. In addition, the short-term performance of these sites (less than 5 years) is presented since very little long-term performance data was available

  10. 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.

  11. Role of the dielectric for the charging dynamics of the dielectric/barrier interface in AlGaN/GaN based metal-insulator-semiconductor structures under forward gate bias stress

    International Nuclear Information System (INIS)

    Lagger, P.; Steinschifter, P.; Reiner, M.; Stadtmüller, M.; Denifl, G.; Ostermaier, C.; Naumann, A.; Müller, J.; Wilde, L.; Sundqvist, J.; Pogany, D.

    2014-01-01

    The high density of defect states at the dielectric/III-N interface in GaN based metal-insulator-semiconductor structures causes tremendous threshold voltage drifts, ΔV th , under forward gate bias conditions. A comprehensive study on different dielectric materials, as well as varying dielectric thickness t D and barrier thickness t B , is performed using capacitance-voltage analysis. It is revealed that the density of trapped electrons, ΔN it , scales with the dielectric capacitance under spill-over conditions, i.e., the accumulation of a second electron channel at the dielectric/AlGaN barrier interface. Hence, the density of trapped electrons is defined by the charging of the dielectric capacitance. The scaling behavior of ΔN it is explained universally by the density of accumulated electrons at the dielectric/III-N interface under spill-over conditions. We conclude that the overall density of interface defects is higher than what can be electrically measured, due to limits set by dielectric breakdown. These findings have a significant impact on the correct interpretation of threshold voltage drift data and are of relevance for the development of normally off and normally on III-N/GaN high electron mobility transistors with gate insulation.

  12. Linguistic Barriers and Bridges

    DEFF Research Database (Denmark)

    Thuesen, Frederik

    2016-01-01

    The influence of language on social capital in low-skill and ethnically diverse workplaces has thus far received very limited attention within the sociology of work. As the ethnically diverse workplace is an important social space for the construction of social relations bridging different social...... and intercultural communication, this article analyses interviews with 31 employees from two highly ethnically diverse Danish workplaces. The article shows how linguistic barriers such as different levels of majority language competence and their consequent misunderstandings breed mistrust and hostility, whilst...... communication related to collaboration and ‘small talk’ may provide linguistic bridges to social capital formation....

  13. [Barrier methods of contraception].

    Science.gov (United States)

    Goldsmith, A; Edelman, D A

    1982-01-01

    Vaginal methods of contraception were the earliest types used and some references to them date back to antiquity. Most of the vaginal contraceptive agents identified by the ancient Greeks, Indians, Japanese, and Chinese have been found in modern laboratory tests to have spermicidal properties, but it is doubtful that the methods were fully reliable or were used by many people. During the 19th century the condom, vaginal spermicides, and diaphragm became available. The development of nonoxynol-9 and other nonirritating but effective spermicidal agents improved vaginal contraceptives greatly by the 1950s, but starting in the 1960s newer methods began to replace the vaginal methods. Interest in barrier methods has been reawakened somewhat by concern about the health effects of hormonal methods. At present all barrier methods leave something to be desired. Failure rates of 3-30% for barrier methods in general have been estimated, but the higher rates are believed due to incorrect or inconsistent use. Theoretical failure rates of condoms and diaphragms have been estimated at 3/100 women-years, but in actual use failure rates may reach 15 for condoms and 13 for diaphragms used with spermicides. Use-effectiveness rates are greatly influenced by motivation. For a variety of reasons, the acceptability of barrier methods is low, especially in developing countries. New developments in spermicidal agents include sperm inhibitors, which impede the fertilizing capacity of sperm rather than attempting a spermicidal effect; a number of such agents have been studied and have proven more effective in animal tests than conventional spermicides. Neosampoon, a new spermicidal foam, has attracted an increasing number of users, especially in developing countries. A new condom, made of thin polymers and containing a standard dose of nonoxynol-9, has been designed to dissolve in the vaginal fluid. Further studies are needed of its acceptability, efficacy, and side effects before it becomes

  14. Support or Barrier?

    DEFF Research Database (Denmark)

    Sanden, Guro Refsum; Lønsmann, Dorte

    employees use to cross language boundaries in their everyday work, and, secondly, how these practices relate to top-down language management in the case companies. Our findings show that employees are often dependent on ad hoc and informal solutions in cross- language situations, which leads us......This study offers a critical look at how corporate-level language management influences front-line language practices among employees in three multinational corporations (MNCs) headquartered in Scandinavia. Based on interview and document data, we examine, firstly, what front-line practices...... to a discussion of how a company’s language policy may be seen as both support and a barrier....

  15. DNA nanovehicles and the biological barriers

    DEFF Research Database (Denmark)

    Okholm, Anders Hauge; Kjems, Jørgen

    2016-01-01

    DNA is emerging as a smart material to construct nanovehicles for targeted drug delivery. The programmability of Watson-Crick base paring enables construction of defined and dynamic DNA nanostructures of almost arbitrary shape and DNA can readily be functionalized with a variety of molecular...... be overcome. Here, we highlight recent strategies for DNA nanostructures in drug delivery, DNA nanovehicles, to facilitate targeting and crossing of the biological barriers. In light of this, we discuss future solutions and challenges for DNA nanovehicles to unravel their great potential to facilitate...

  16. Performing a local barrier operation

    Science.gov (United States)

    Archer, Charles J; Blocksome, Michael A; Ratterman, Joseph D; Smith, Brian E

    2014-03-04

    Performing a local barrier operation with parallel tasks executing on a compute node including, for each task: retrieving a present value of a counter; calculating, in dependence upon the present value of the counter and a total number of tasks performing the local barrier operation, a base value, the base value representing the counter's value prior to any task joining the local barrier; calculating, in dependence upon the base value and the total number of tasks performing the local barrier operation, a target value of the counter, the target value representing the counter's value when all tasks have joined the local barrier; joining the local barrier, including atomically incrementing the value of the counter; and repetitively, until the present value of the counter is no less than the target value of the counter: retrieving the present value of the counter and determining whether the present value equals the target value.

  17. The implications of trade policy and 'natural' barriers induced protection for aggregate demand for imports: Evidence for Malawi

    OpenAIRE

    Zgovu, Evious K.

    2003-01-01

    This paper analyses the relative importance of trade policy and ‘natural’ trade barriers in the demand for imports for Malawi, a geographically landlocked sub-Saharan African economy, using an augmented dynamic import demand model. Incidence analysis of protection shows that pre-liberalisation trade policy barriers were greater than ‘natural’ barriers but in post-liberalisation ‘natural’ barriers were greater. Econometric analysis of the import demand model shows that ‘true’ protection of imp...

  18. ANALYSIS OF FLEXIBLE BARRIERS USED AS SAFETY PROTECTION IN WOODWORKING

    Directory of Open Access Journals (Sweden)

    Ana Pavlovic

    2016-03-01

    Full Text Available Machine tools use physical barriers, made by flexible thermoplastic materials, to protect the environment and the operators against the projections of wood chips and parts of cutting tools. These barriers constitute a partial closure and allow the passage of the workpiece, being simultaneously able to contain sharp fragments projected at high speed. The present research was conducted with the aim to evaluate the real effectiveness of these barriers, to investigate their dynamic behaviour by numerical simulations. Results showed that these barriers, if properly considered, could retain heavier masses and higher speeds. The research also allowed, in fact, to investigate the influence of several factors in design, selection and use, as material, shape, position, assemblages and many others, highlighting weaknesses and identifying possible measures to increase its effectiveness.

  19. Quantum coherence in the reflection of above barrier wavepackets.

    Science.gov (United States)

    Petersen, Jakob; Pollak, Eli

    2018-02-21

    The quantum phenomenon of above barrier reflection is investigated from a time-dependent perspective using Gaussian wavepackets. The transition path time distribution, which in principle is experimentally measurable, is used to study the mean flight times ⟨t⟩ R and ⟨t⟩ T associated with the reflection and the transmission over the barrier paying special attention to their dependence on the width of the barrier. Both flight times, and their difference Δt, exhibit two distinct regimes depending on the ratio of the spatial width of the incident wavepacket and the length of the barrier. When the ratio is larger than unity, the reflection and transmission dynamics are coherent and dominated by the resonances above the barrier. The flight times ⟨t⟩ R/T and the flight time difference Δt oscillate as a function of the barrier width (almost in phase with the transmission probability). These oscillations reflect a momentum filtering effect related to the coherent superposition of the reflected and transmitted waves. For a ratio less than unity, the barrier reflection and transmission dynamics are incoherent and the oscillations are absent. The barrier width which separates the coherent and incoherent regimes is identified analytically. The oscillatory structure of the time difference Δt as a function of the barrier width in the coherent regime is absent when considered in terms of the Wigner phase time delays for reflection and transmission. We conclude that the Wigner phase time does not correctly describe the temporal properties of above barrier reflection. We also find that the structure of the reflected and transmitted wavepackets depends on the coherence of the process. In the coherent regime, the wavepackets can have an overlapping peak structure, but the peaks are not fully resolved. In the incoherent regime, the wavepackets split in time into distinct separated Gaussian like waves, each one reflecting the number of times the wavepacket crosses the

  20. Quantum coherence in the reflection of above barrier wavepackets

    Science.gov (United States)

    Petersen, Jakob; Pollak, Eli

    2018-02-01

    The quantum phenomenon of above barrier reflection is investigated from a time-dependent perspective using Gaussian wavepackets. The transition path time distribution, which in principle is experimentally measurable, is used to study the mean flight times ⟨t⟩R and ⟨t⟩T associated with the reflection and the transmission over the barrier paying special attention to their dependence on the width of the barrier. Both flight times, and their difference Δt, exhibit two distinct regimes depending on the ratio of the spatial width of the incident wavepacket and the length of the barrier. When the ratio is larger than unity, the reflection and transmission dynamics are coherent and dominated by the resonances above the barrier. The flight times ⟨t⟩R/T and the flight time difference Δt oscillate as a function of the barrier width (almost in phase with the transmission probability). These oscillations reflect a momentum filtering effect related to the coherent superposition of the reflected and transmitted waves. For a ratio less than unity, the barrier reflection and transmission dynamics are incoherent and the oscillations are absent. The barrier width which separates the coherent and incoherent regimes is identified analytically. The oscillatory structure of the time difference Δt as a function of the barrier width in the coherent regime is absent when considered in terms of the Wigner phase time delays for reflection and transmission. We conclude that the Wigner phase time does not correctly describe the temporal properties of above barrier reflection. We also find that the structure of the reflected and transmitted wavepackets depends on the coherence of the process. In the coherent regime, the wavepackets can have an overlapping peak structure, but the peaks are not fully resolved. In the incoherent regime, the wavepackets split in time into distinct separated Gaussian like waves, each one reflecting the number of times the wavepacket crosses the barrier

  1. Exposure, Uptake, and Barriers

    Science.gov (United States)

    Baeza-Squiban, Armelle; Lanone, Sophie

    The nanotechnologies market is booming, e.g., in the food industry (powder additives, etc.) and in medical applications (drug delivery, prosthetics, diagnostic imaging, etc.), but also in other industrial sectors, such as sports, construction, cosmetics, and so on. In this context, with an exponential increase in the number of current and future applications, it is particularly important to evaluate the problem of unintentional (i.e., non-medical) exposure to manufactured nanoparticles (so excluding nanoparticles found naturally in the environment). In this chapter, we begin by discussing the various parameters that must be taken into account in any serious assessment of exposure to man-made nanoparticles. We then list the potential routes by which nanoparticles might enter into the organism, and outline the mechanisms whereby they could get past the different biological barriers. Finally, we describe the biodistribution of nanoparticles in the organism and the way they are eliminated.

  2. Countermeasures and barriers

    International Nuclear Information System (INIS)

    Petersen, Johannes

    2005-10-01

    In 1973 Haddon proposed ten strategies for reducing and avoiding damages based on a model of potential harmful energy transfer (Haddon, 1973). The strategies apply to a large variety of unwanted phenomena. Haddon's pioneering work on countermeasures has had a major influence on later thinking about safety. Considering its impact it is remarkable that the literature offers almost no discussions related to the theoretical foundations of Haddon's countermeasure strategies. The present report addresses a number of theoretical issues related to Haddon's countermeasure strategies, which are: 1) A reformulation and formalization of Haddon's countermeasure strategies. 2) An identification and description of some of the problems associated with the term 'barrier'. 3) Suggestions for a more precise terminology based on the causal structure of countermeasures. 4) Extending the scope of countermeasures to include sign-based countermeasures. (au)

  3. Countermeasures and barriers

    Energy Technology Data Exchange (ETDEWEB)

    Petersen, Johannes [Oersted - DTU, Automation, Kgs. Lyngby (Denmark)

    2005-10-01

    In 1973 Haddon proposed ten strategies for reducing and avoiding damages based on a model of potential harmful energy transfer (Haddon, 1973). The strategies apply to a large variety of unwanted phenomena. Haddon's pioneering work on countermeasures has had a major influence on later thinking about safety. Considering its impact it is remarkable that the literature offers almost no discussions related to the theoretical foundations of Haddon's countermeasure strategies. The present report addresses a number of theoretical issues related to Haddon's countermeasure strategies, which are: 1) A reformulation and formalization of Haddon's countermeasure strategies. 2) An identification and description of some of the problems associated with the term 'barrier'. 3) Suggestions for a more precise terminology based on the causal structure of countermeasures. 4) Extending the scope of countermeasures to include sign-based countermeasures. (au)

  4. Overwash threshold experiment for gravel barriers

    Science.gov (United States)

    Matias, Ana; Williams, Jon; Bradbury, Andrew; Masselink, Gerhard; Ferreira, Óscar

    2010-05-01

    action show those formulas underestimate the run-up limit. The discrepancy, which can reach almost 1m, is attributed to several causes, including: (1) scale effects of the prototype; (2) applicability of most run-up formulae only to sandy barriers and beaches; and (3) important, infrequent (K., Bradbury, A., 2008. A laboratory study of overtopping and breaching of shingle barrier beaches. Proc. Coastal Engineering, Hannover, Germany, pp. 1497-1508. Orford, J. And Carter, R.W.G., 1982. Crestal overtop and washover sedimentation on a fringing sandy gravel barrier coast, Carnsore Point, Southeast Ireland. J. Sedim. Petrology, 52, 265-278. Powell, K.A., 1990. Predicting short term profile response for shingle beaches. HR Wallingford SR Report, vol. 219. Stockdon, H.F., Sallenger, A.H., Holman, R.A., Howd, P.A., 2007. A simple model for the spatially-variable coastal response to hurricanes. Mar. Geol., 238, 1-20. Williams, J.J., Masselink, G., Buscombe, D., Turner, I.L., Matias, A., Ferreira, A. Metje, N., Coates, L., Chapman, D., Bradbury, A., Albers, A. & Pan, S., 2009. BARDEX (Barrier Dynamics Experiment): taking the beach into the laboratory. J. Coastal Res., SI 56, 158-162.

  5. Fission barrier heights in the A ∼ 200 mass region

    Indian Academy of Sciences (India)

    not only to understand the heavy-ion-induced fusion–fission dynamics and prediction of superheavy elements, but also other areas, such as stellar nucleosynthesis and nuclear energy applications. In the actinide region, the fission barrier heights are comparable to the neutron separation energies and could be determined ...

  6. Li breakup polarization potential at near barrier energies

    International Nuclear Information System (INIS)

    Lubian, F. J.; Correa, T.; Gomes, P.R.S.; Paes, B; Figueira, J. M.; Abriola, D.; Fernandez, J. O.; Capurro, O. A.; Marti, G.V.; Martinez, D.; Heimann; Negri, A.; Pacheco, A. J.; Padron, I.

    2007-01-01

    Inelastic and one neutron transfer cross sections at energies around the Coulomb barrier were used to derive dynamic polarization potential (DPP) for the 7 Li + 27 Al system. The DPP due to breakup, obtained in a simple way, indicates that its real part is repulsive at nearbarrier energies. (Author)

  7. Emotional and behavioural barriers to learning and development in ...

    African Journals Online (AJOL)

    Objective: The interaction between teachers, classroom strategies and learners experiencing emotional and behavioural barriers to learning and development in a system of inclusive education results in multiple dynamics on different levels. Many teachers in mainstream education lack training to deal with learners ...

  8. Breaking the Sound Barrier

    Science.gov (United States)

    Brown, Tom; Boehringer, Kim

    2007-01-01

    Students in a fourth-grade class participated in a series of dynamic sound learning centers followed by a dramatic capstone event--an exploration of the amazing Trashcan Whoosh Waves. It's a notoriously difficult subject to teach, but this hands-on, exploratory approach ignited student interest in sound, promoted language acquisition, and built…

  9. Thames barrier (flood protection barriers on the Thames)

    International Nuclear Information System (INIS)

    Ilkovic, J.

    2005-01-01

    In this paper the flood protection barriers on the Thames are presented. The flood protection system on the Thames in 1984 was commissioned. During two decades this barrier was used 54 times against to the high water and 34 times against storm-sewage. There is installed buttress type hydroelectric power plant

  10. Update on the glomerular filtration barrier.

    Science.gov (United States)

    Jarad, George; Miner, Jeffrey H

    2009-05-01

    The nephrology community lacks a unified view of protein sieving through the glomerular capillary wall. The glomerular capillary wall consists of three distinct but closely interacting layers: the fenestrated endothelium, with its glycocalyx; the podocytes, with their interdigitated foot processes and slit diaphragms; and the intervening glomerular basement membrane. Proteinuria is associated with abnormalities in any one layer, suggesting that each contributes to the glomerular filtration barrier (GFB). Proteinuria can also be induced in the context of a normal glomerular capillary wall. Here, we review some classic studies as well as some newer concepts and present competing hypotheses about the GFB. Two almost forgotten concepts have recently emerged. One group has challenged the exquisite selectivity of the GFB to albumin and suggested that proteinuria is the result of abnormal tubular uptake. There has also been a reemphasis on diffusion through the glomerular basement membrane as the driving force behind macromolecular filtration. New evidence suggests that the endothelial glycocalyx is an important charge-selective barrier. We suggest viewing the GFB as a dynamic rather than as a rigid barrier, requiring three healthy layers and a hemodynamic steady state. Multiple challenges to studying the endothelium, the tubular handling of albumin, and the role of hemodynamic forces will require new tools, new hypotheses, and open minds.

  11. Tunneling through a time-dependent barrier – a numerical study

    Indian Academy of Sciences (India)

    biomolecules have received serious attention in recent years. The emphasis has been on the dynamics of escape over fluctuating barriers which could arise as a result of stochastic re- orientations of a bridge unit or stochastically interrupted electronic pathway as in proteins. So the fluctuating barrier can act as good model ...

  12. Moisture monitoring in waste disposal surface barriers.

    Science.gov (United States)

    Brandelik, Alex; Huebner, Christof

    2003-05-01

    Surface barriers for waste disposal sites should prevent waste water and gas emission into the environment. It is necessary to assess their proper operation by monitoring the water regime of the containment. A set of three new water content measuring devices has been developed that provide an economical solution for monitoring the moisture distribution and water dynamic. They will give an early warning service if the barrier system is at risk of being damaged. The cryo soil moisture sensor 'LUMBRICUS' is an in situ self-calibrating absolute water content measuring device. It measures moisture profiles at spot locations down to 2.5 m depth with an accuracy of better than 1.5% and a depth resolution of 0.03 m. The sensor inherently measures density changes and initial cracks of shrinking materials like clay minerals. The large area soil moisture sensor 'TAUPE' is a moisture sensitive electric cable network to be buried in the mineral barrier material of the cover. A report will be given with results and experiences on an exemplary installation at the Waste Disposal Facility Karlsruhe-West. 800 m2 of the barrier construction have been continuously monitored since December 1997. Volumetric water content differences of 1.5% have been detected and localised within 4 m. This device is already installed in two other waste disposal sites. A modified 'TAUPE' was constructed for the control of tunnels and river dams as well. Thin sheet moisture sensor 'FORMI' is specifically designed for moisture measurements in liners like bentonite, textile and plastic. Due to its flexibility it follows the curvature of the liner. The sensor measures independently from neighbouring materials and can be matched to a wide range of different thickness of the material. The sensors are patented in several countries.

  13. Informal export barriers and poverty

    OpenAIRE

    Porto, Guido G.

    2004-01-01

    The author investigates the poverty impacts of informal export barriers like transport costs, cumbersome customs practices, costly regulations, and bribes. He models these informal barriers as export taxes that distort the efficient allocation of resources. In low-income agricultural economies, this distortion lowers wages and household agricultural income, thereby leading to higher pover...

  14. Barriers to Women in Science

    Science.gov (United States)

    Butler, Rosemary

    2013-01-01

    The Presiding Officer of the National Assembly for Wales, Rosemary Butler AM, has put the issue of barriers to women in public life at the top of the political agenda in Wales. She has held sessions with women across Wales to find out what those barriers are and how they can be tackled. On International Women's Day in February, she invited…

  15. Seismic waves and seismic barriers

    Science.gov (United States)

    Kuznetsov, S. V.

    2011-05-01

    The basic idea of seismic barrier is to protect an area occupied by a building or a group of buildings from seismic waves. Depending on nature of seismic waves that are most probable in a specific region, different kinds of seismic barriers are suggested. For example, vertical barriers resembling a wall in a soil can protect from Rayleigh and bulk waves. The FEM simulation reveals that to be effective, such a barrier should be (i) composed of layers with contrast physical properties allowing "trapping" of the wave energy inside some of the layers, and (ii) depth of the barrier should be comparable or greater than the considered seismic wave length. Another type of seismic barrier represents a relatively thin surface layer that prevents some types of surface seismic waves from propagating. The ideas for these barriers are based on one Chadwick's result concerning non-propagation condition for Rayleigh waves in a clamped half-space, and Love's theorem that describes condition of non-existence for Love waves. The numerical simulations reveal that to be effective the length of the horizontal barriers should be comparable to the typical wavelength.

  16. Structure information from fusion barriers

    Indian Academy of Sciences (India)

    It is shown that the analysis of fusion barrier distributions is not always an unambiguous test or a 'fingerprint' of the structure information of the colliding nuclei. Examples are presented with same fusion barrier distributions for nuclei having different structures. The fusion excitation functions for 16O+208Pb, using the coupled ...

  17. BARRIERS OF STRATEGIC ALLIANCES ORGANIZATION

    Directory of Open Access Journals (Sweden)

    Vladislav M. Sannikov

    2014-01-01

    Full Text Available General barriers of organization of different types of strategic alliances have beenconsidered in the article. There are several recommendations for overcoming themin cases of international alliances, and in case of work in one state. The article also identified goals and tasks of single coordination center of alliance to overcome organization barriers.

  18. Organizational Barriers to Transition: Summary.

    Science.gov (United States)

    Haynes, John; Justice, Thomas I., Ed.

    This study sought to identify the barriers that negatively impact the ability of disabled youth to successfully make a transition from school into employment and a quality adult life, and sought to specifically define organizational disincentives to successful transition. Current research is reviewed relating to organizational barriers to…

  19. Epistemological barriers to radical behaviorism.

    Science.gov (United States)

    O'Donohue, W T; Callaghan, G M; Ruckstuhl, L E

    1998-01-01

    The historian and philosopher of science Gaston Bachelard proposed the concept of epistemological barriers to describe the intellectual challenges encountered by scientists in their work. In order to embrace novel ways of approaching a problem in science, scientists must overcome barriers or obstacles posed by their prior views. For example, Einsteinian physics presents scientists with claims that space is curved and that time and space are on the same continuum. We utilize Bachelard's concept of epistemological barriers to describe the differences between the intellectual journeys students pursuing advanced studies face when attempting to accept cognitive psychology or radical behaviorism. We contend that the folk psychological beliefs that students typically hold when entering these studies pose less challenge to cognitive psychology than to radical behaviorism. We also suggest that these barriers may also partly be involved in the problematic exegesis that has plagued radical behaviorism. In close, we offer some suggestions for dealing with these epistemological barriers.

  20. Epistemological barriers to radical behaviorism

    Science.gov (United States)

    O'Donohue, William T.; Callaghan, Glenn M.; Ruckstuhl, L. E.

    1998-01-01

    The historian and philosopher of science Gaston Bachelard proposed the concept of epistemological barriers to describe the intellectual challenges encountered by scientists in their work. In order to embrace novel ways of approaching a problem in science, scientists must overcome barriers or obstacles posed by their prior views. For example, Einsteinian physics presents scientists with claims that space is curved and that time and space are on the same continuum. We utilize Bachelard's concept of epistemological barriers to describe the differences between the intellectual journeys students pursuing advanced studies face when attempting to accept cognitive psychology or radical behaviorism. We contend that the folk psychological beliefs that students typically hold when entering these studies pose less challenge to cognitive psychology than to radical behaviorism. We also suggest that these barriers may also partly be involved in the problematic exegesis that has plagued radical behaviorism. In close, we offer some suggestions for dealing with these epistemological barriers. PMID:22478314

  1. Barriers for recess physical activity

    DEFF Research Database (Denmark)

    Pawlowski, Charlotte Skau; Tjørnhøj-Thomsen, Tine; Schipperijn, Jasper

    2014-01-01

    . This was verified by a thematic analysis of transcripts from the open discussions and go-along interviews. RESULTS: The most frequently identified barriers for both boys and girls were weather, conflicts, lack of space, lack of play facilities and a newly-found barrier, use of electronic devices. While boys......BACKGROUND: Many children, in particular girls, do not reach the recommended amount of daily physical activity. School recess provides an opportunity for both boys and girls to be physically active, but barriers to recess physical activity are not well understood. This study explores gender...... differences in children's perceptions of barriers to recess physical activity. Based on the socio-ecological model four types of environmental barriers were distinguished: natural, social, physical and organizational environment. METHODS: Data were collected through 17 focus groups (at 17 different schools...

  2. Hanford Protective Barriers Program asphalt barrier studies -- FY 1988

    International Nuclear Information System (INIS)

    Freeman, H.D.; Gee, G.W.

    1989-05-01

    The Hanford Protective Barrier (HPB) Program is evaluating alternative barriers to provide a means of meeting stringent water infiltration requirements. One type of alternative barrier being considered is an asphalt-based layer, 1.3 to 15 cm thick, which has been shown to be very effective as a barrier for radon gas and, hence, should be equally effective as a barrier for the larger molecules of water. Fiscal Year 1988 studies focused on the selection and formulation of the most promising asphalt materials for further testing in small-tube lysimeters. Results of laboratory-scale formulation and hydraulic conductivity tests led to the selection of a rubberized asphalt material and an admixture of 24 wt% asphalt emulsion and concrete sand as the two barriers for lysimeter testing. Eight lysimeters, four each containing the two asphalt treatments, were installed in the Small Tube Lysimeter Facility on the Hanford Site. The lysimeter tests allow the performance of these barrier formulations to be evaluated under more natural environmental conditions

  3. Development of engineered barrier

    Energy Technology Data Exchange (ETDEWEB)

    Chun, Kwan Sik; Cho, Won Jin; Lee, Jae Owan; Kim, Seung Soo; Kang, Mu Ja

    1999-03-01

    Engineered barrier development was carried out into the three research fields : waste form, disposal container, and buffer. The waste form field dealt with long-term leaching tests with borosilicate waste glasses surrounded by compacted bentonite. The leach rate decreased with increasing time, and was higher for the waste specimen rich in U and Na. In the container field, preliminary concepts of disposal containers were recommended by conducting structural analysis, thermal analysis, and shielding analysis, and major properties of stainless steel, copper, and titanium as a container material were surveyed. The sensitization degrees of SUS 316 and316L were lower than those of SUS 304 and 304L, respectively. The crevice corrosion of sensitized stainless steel was sensitive to the content of salt. Researches into the buffer included establishment of its performance criteria followed by investigating major properties of buffer using potential material in Korea. Experiments were made for measuring hydraulic conductivities, swelling properties, mechanical properties, thermal conductivities, pore-water chemistry properties, and adsorption properties was also investigated. (author)

  4. Alternative geochemical barrier materials

    International Nuclear Information System (INIS)

    1991-07-01

    Previous investigations of the effects of neutralization and reduction on uranium mill tailings pore fluids by the Technical Support Contractor indicated that arsenic, selenium, and molybdenum continue to remain in solution in all but reducing conditions. These hazardous constituents are present in groundwaters as oxyanions and, therefore, are not expected to be removed by adsorption into clays and most other soil constituents. It was decided to investigate the attenuation capacity of two commonly available crystalline iron oxides, taconite and scoria, and a zeolite, a network aluminosilicate with a cage structure. Columns of the candidate materials were exposed to solutions of individual constituents, including arsenic, molybdenum, selenium, and, uranium, and to the spiked tailings pore fluid from the Bodo Canyon disposal cell near Durango, Colorado. In addition to the single material columns, a homogeneous blend of the three materials and layers of the materials were exposed to spiked tailings pore fluids. The results of these experiments indicate that with the exception of molybdenum, the constituents of concern are attenuated by the taconite; however, they are not sufficiently attenuated to meet the groundwater protection standards applicable to the UMTRA Project. Therefore, the candidate barrier materials did not prove to be useful to the UMTRA Project for the cleanup of groundwaters

  5. Omnidirectional ventilated acoustic barrier

    Science.gov (United States)

    Zhang, Hai-long; Zhu, Yi-fan; Liang, Bin; Yang, Jing; Yang, Jun; Cheng, Jian-chun

    2017-11-01

    As an important problem in acoustics, sound insulation finds applications in a great variety of situations. In the existing schemes, however, there has always been a trade-off between the thinness of sound-insulating devices and their ventilating capabilities, limiting their potentials in the control of low-frequency sound in high ventilation environments. Here, we design and experimentally implement an omnidirectional acoustic barrier with a planar profile, subwavelength thickness ( 0.18 λ ), yet high ventilation. The proposed mechanism is based on the interference between the resonant scattering of discrete states and the background scattering of continuous states which induces a Fano-like asymmetric transmission profile. Benefitting from the binary-structured design of the coiled unit and hollow pipe, it maximally simplifies the design and fabrication while ensuring the ventilation for all the non-resonant units with open tubes. The simulated and measured results agree well, showing the effectiveness of our proposed mechanism to block low frequency sound coming from various directions while allowing 63% of the air flow to pass. We anticipate our design to open routes to design sound insulators and to enable applications in traditionally unattainable cases such as those calling for noise reduction and cooling simultaneously.

  6. Chasing boundaries and cascade effects in a coupled barrier - marshes - lagoon system

    Science.gov (United States)

    Lorenzo Trueba, J.; Mariotti, G.

    2015-12-01

    Low-lying coasts are often characterized by barriers islands, shore-parallel stretches of sand separated from the mainland by marshes and lagoons. We built an exploratory numerical model to examine the morphological feedbacks within an idealized barrier - marshes -lagoon system and predict its evolution under projected rates of sea level rise and sediment supply to the backbarrier environment. Our starting point is a recently developed morphodynamic model, which couples shoreface evolution and overwash processes in a dynamic framework. As such, the model is able to capture dynamics not reproduced by morphokinematic models, which advect geometries without specific concern to processes. These dynamics include periodic barrier retreat due to time lags in the shoreface response to barrier overwash, height drowning due to insufficient overwash fluxes as sea level rises, and width drowning, which occurs when the shoreface response rate is insufficient to maintain the barrier geometry during overwash-driven landward migration. We extended the model by coupling the barrier model with a model for the evolution of the marsh platform and the boundary between the marsh and the adjacent lagoon. The coupled model explicitly describes marsh edge processes and accounts for the modification of the wave regime associated with lagoon width (fetch). Model results demonstrate that changes in factors that are not typically associated with the dynamics of coastal barriers, such as the lagoon width and the rate of export/import of sediments from and to the lagoon, can lead to previously unidentified complex responses of the coupled system. In particular, a wider lagoon in the backbarrier, and/or a reduction in the supply of muddy sediments to the backbarrier, can increase barrier retreat rates and even trigger barrier drowning. Overall, our findings highlight the importance of incorporating backbarrier dynamics in models that aim at predicting the response of barrier systems.

  7. Controlling ferrofluid permeability across the blood-brain barrier model

    Science.gov (United States)

    Shi, Di; Sun, Linlin; Mi, Gujie; Sheikh, Lubna; Bhattacharya, Soumya; Nayar, Suprabha; Webster, Thomas J.

    2014-02-01

    In the present study, an in vitro blood-brain barrier model was developed using murine brain endothelioma cells (b.End3 cells). Confirmation of the blood-brain barrier model was completed by examining the permeability of FITC-Dextran at increasing exposure times up to 96 h in serum-free medium and comparing such values with values from the literature. After such confirmation, the permeability of five novel ferrofluid (FF) nanoparticle samples, GGB (ferrofluids synthesized using glycine, glutamic acid and BSA), GGC (glycine, glutamic acid and collagen), GGP (glycine, glutamic acid and PVA), BPC (BSA, PEG and collagen) and CPB (collagen, PVA and BSA), was determined using this blood-brain barrier model. All of the five FF samples were characterized by zeta potential to determine their charge as well as TEM and dynamic light scattering for determining their hydrodynamic diameter. Results showed that FF coated with collagen passed more easily through the blood-brain barrier than FF coated with glycine and glutamic acid based on an increase of 4.5% in permeability. Through such experiments, diverse magnetic nanomaterials (such as FF) were identified for: (1) MRI use since they were less permeable to penetrate the blood-brain barrier to avoid neural tissue toxicity (e.g. GGB) or (2) brain drug delivery since they were more permeable to the blood-brain barrier (e.g. CPB).

  8. The Blood-Brain Barrier: An Engineering Perspective

    Directory of Open Access Journals (Sweden)

    Andrew eWong

    2013-08-01

    Full Text Available It has been more than 100 years since Paul Ehrlich reported that various water-soluble dyes injected into the circulation did not enter the brain. Since Ehrlich’s first experiments, only a small number of molecules, such as alcohol and caffeine have been found to cross the blood-brain barrier, and it remains the major roadblock to treatment of many central nervous system diseases. At the same time, many central nervous system diseases are associated with disruption of the blood-brain barrier that can lead to changes in permeability, modulation of immune cell transport, and trafficking of pathogens into the brain. Therefore advances in our understanding of the structure and function of the blood-brain barrier are key to advances in treatment of a wide range of central nervous system diseases. Over the past 10 years it has become recognized that the blood-brain barrier is a complex dynamic system that involves biomechanical and biochemical signaling between the vascular system and the brain. Here we reconstruct the structure, function, and transport properties of the blood-brain barrier from an engineering perspective. New insight into the physics of the blood-brain barrier could ultimately lead to clinical advances in the treatment of central nervous system diseases.

  9. Fusion barrier characteristics of actinides

    Science.gov (United States)

    Manjunatha, H. C.; Sridhar, K. N.

    2018-03-01

    We have studied fusion barrier characteristics of actinide compound nuclei with atomic number range 89 ≤ Z ≤ 103 for all projectile target combinations. After the calculation of fusion barrier heights and positions, we have searched for their parameterization. We have achieved the empirical formula for fusion barrier heights (VB), positions (RB), curvature of the inverted parabola (ħω) of actinide compound nuclei with atomic number range 89 ≤ Z ≤ 103 for all projectile target combinations (6 actinides with the simple inputs of mass number (A) and atomic number (Z) of projectile-targets.

  10. Penetration through the Skin Barrier

    DEFF Research Database (Denmark)

    Nielsen, Jesper Bo; Benfeldt, Eva; Holmgaard, Rikke

    2016-01-01

    -through diffusion cells) as well as in vivo methods (microdialysis and microperfusion). Then follows a discussion with examples of how different characteristics of the skin (age, site and integrity) and of the penetrants (size, solubility, ionization, logPow and vehicles) affect the kinetics of percutaneous......The skin is a strong and flexible organ with barrier properties essential for maintaining homeostasis and thereby human life. Characterizing this barrier is the ability to prevent some chemicals from crossing the barrier while allowing others, including medicinal products, to pass at varying rates...

  11. Vehicle barrier with access delay

    Science.gov (United States)

    Swahlan, David J; Wilke, Jason

    2013-09-03

    An access delay vehicle barrier for stopping unauthorized entry into secure areas by a vehicle ramming attack includes access delay features for preventing and/or delaying an adversary from defeating or compromising the barrier. A horizontally deployed barrier member can include an exterior steel casing, an interior steel reinforcing member and access delay members disposed within the casing and between the casing and the interior reinforcing member. Access delay members can include wooden structural lumber, concrete and/or polymeric members that in combination with the exterior casing and interior reinforcing member act cooperatively to impair an adversarial attach by thermal, mechanical and/or explosive tools.

  12. A LOOK AT CULTURAL BARRIERS

    Directory of Open Access Journals (Sweden)

    Carmen A. VRÂNCEANU

    2015-06-01

    Full Text Available Nowadays the global market allows each individual to work in foreign countries. This fact is a great opportunity for business development, but also puts into light the problem of cultural barriers. Ineffective cross-cultural communication and collaboration can harm employees, customers, and other stakeholders. A company with employees from different cultures must acknowledge and understand these barriers in order to overcome them and to obtain the desired performance. The present study aims to expose the cultural barriers encountered by foreigners in a multinational company from Romania.

  13. Modelling the HIV persistence through the network of lymphocyte recirculation in vivo

    Directory of Open Access Journals (Sweden)

    Ying Huang

    2017-02-01

    Full Text Available Human Immunodeficiency Virus (HIV is able to persist in cellular and/or anatomical viral reservoirs, despite the effective inhibition of virus replication by the antiretroviral therapy (ART. Here we develop a mathematical model to gain some insights of HIV persistence relevant to the lymphocyte recirculation network of immune system and the central nervous system (CNS. Our simulations and analyses illustrate the role of the CNS as a virus reservoir to prevent antiretroviral drugs from penetrating the blood-brain (or blood-testis barrier, and we examine the long-term impact of this reservoir on the transmissibility of an infected individual. We observe numerically that level of HIV in peripheral blood may not accurately reflect the true mechanisms occurring within other organs. Keywords: HIV reservoirs, Blood-brain barrier, Dynamical model, Lymphocyte recirculation network, 2010 MSC: 39A11, 92D30

  14. Time as a trade barrier

    Science.gov (United States)

    2001-07-01

    International trade occurs in physical space and moving goods requires time. This paper examines the importance of time as a trade barrier, estimates the magnitude of time costs, and relates these to patterns of trade and the international organizati...

  15. Coastal Structures and Barriers 2012

    Data.gov (United States)

    California Department of Resources — This dataset is a compilation of the UCSC Sand Retention Structures, MC Barriers, and USACE Coastal Structures. UCSC Sand Retention Structures originate from a...

  16. Coastal Structures and Barriers 2012

    Data.gov (United States)

    California Natural Resource Agency — This dataset is a compilation of the UCSC Sand Retention Structures, MC Barriers, and USACE Coastal Structures. UCSC Sand Retention Structures originate from a...

  17. Low Conductivity Thermal Barrier Coatings

    Science.gov (United States)

    Zhu, Dong-Ming

    2005-01-01

    Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future engine higher fuel efficiency and lower emission goals. In this presentation, thermal barrier coating development considerations and requirements will be discussed. An experimental approach is established to monitor in real time the thermal conductivity of the coating systems subjected to high-heat-flux, steady-state and cyclic temperature gradients. Advanced low conductivity thermal barrier coatings have also been developed using a multi-component defect clustering approach, and shown to have improved thermal stability. The durability and erosion resistance of low conductivity thermal barrier coatings have been improved utilizing advanced coating architecture design, composition optimization, in conjunction with more sophisticated modeling and design tools.

  18. Engineered barriers: current status 1989

    International Nuclear Information System (INIS)

    Atkinson, A.; Marsh, G.B.

    1989-06-01

    This report summarises the current state of research relevant to assessing the performance of engineered barriers made of steel and concrete in radioactive waste repositories. The objective of these barriers is to contain substantially the radionuclides within them by providing both physical and chemical impediment to their release. The physical barriers are of most value for highly soluble isotopes with relatively short half-lives (eg 137 Cs), since they can provide a measure of containment until a large fraction of the activity has decayed. In addition they can facilitate retrievability for some period after disposal. The chemical barriers operate by beneficial conditioning of the near field groundwater and providing sites for sorption of radionuclides. Both of these reduce the aqueous concentration of radionuclides in the near field. (author)

  19. Great Barrier Reef, Queensland, Australia

    Science.gov (United States)

    1990-01-01

    This detailed view of the Great Barrier Reef, Queensland, Australia (19.5S, 149.5E) shows several small patch reefs within the overall reef system. The Great Barrier Reef, largest in the world, comprises thousands of individual reefs of great variety and are closely monitored by marine ecologists. These reefs are about 6000 years old and sit on top of much older reefs. The most rapid coral growth occurs on the landward side of the reefs.

  20. Patient advocacy: barriers and facilitators

    OpenAIRE

    Nikravesh Mansoure; Ahmadi Fazlollah; Oskouie Fatemeh; Negarandeh Reza; Hallberg Ingalill

    2006-01-01

    Abstract Background During the two recent decades, advocacy has been a topic of much debate in the nursing profession. Although advocacy has embraced a crucial role for nurses, its extent is often limited in practice. While a variety of studies have been generated all over the world, barriers and facilitators in the patient advocacy have not been completely identified. This article presents the findings of a study exploring the barriers and facilitators influencing the role of advocacy among ...

  1. Barriers to Cyber Information Sharing

    Science.gov (United States)

    2014-12-01

    finding out relationships or no relationships. It is more equivalent with this study’s epistemology and methodology than free-mapping or pure...and industry remain educated on and sensitive to methods that can mitigate this concern and ensure antitrust compliance.151 4. Technology...legal scholars. One way to overcome the legal barriers is through education and clarity about the laws that are currently barriers such as anti-trust

  2. 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.

  3. Economic alternatives for containment barriers

    International Nuclear Information System (INIS)

    Nicholson, P.J.; Jasperse, B.H.; Fisher, M.J.

    1997-01-01

    Fixation, barriers, and containment of existing landfills and other disposal areas are often performed by insitu auger type soil mixing and jet grouting. Cement or other chemical reagents are mixed with soil to form both vertical and horizontal barriers. Immobilization of contaminants can be economically achieved by mixing soil and the contaminants with reagents that solidify or stabilize the contaminated area. Developed in Japan, and relatively new to the United States, the first large scale application was for a vertical barrier at the Jackson Lake Dam project in 1986. This technology has grown in both the civil and environmental field since. The paper describes current United States practice for Deep Soil Mixing (over 12 meters in depth), and Shallow Soil Mixing for vertical barriers and stabilization/solidification, and Jet Grouting for horizontal and vertical barriers. Creating very low permeability barriers at depth with minimal surface return often makes these techniques economical when compared to slurry trenches. The paper will discuss equipment, materials, soil and strength parameters, and quality control

  4. 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.

  5. 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.

  6. Controlling the spin-torque efficiency with ferroelectric barriers

    KAUST Repository

    Useinov, A.

    2015-02-11

    Nonequilibrium spin-dependent transport in magnetic tunnel junctions comprising a ferroelectric barrier is theoretically investigated. The exact solutions of the free electron Schrödinger equation for electron tunneling in the presence of interfacial screening are obtained by combining Bessel and Airy functions. We demonstrate that the spin transfer torque efficiency, and more generally the bias dependence of tunneling magneto- and electroresistance, can be controlled by switching the ferroelectric polarization of the barrier. In particular, the critical voltage at which the in-plane torque changes sign can be strongly enhanced or reduced depending on the direction of the ferroelectric polarization of the barrier. This effect provides a supplementary way to electrically control the current-driven dynamic states of the magnetization and related magnetic noise in spin transfer devices.

  7. Collective spectra along the fission barrier

    Directory of Open Access Journals (Sweden)

    Pigni M. T.

    2012-12-01

    Full Text Available Discrete and continuous spectra of fissioning nuclei at the humps of fission barriers (Bohr transition states and in the intermediate wells (superdeformed and hyperdeformed states play a key role in the calculation of fission cross sections. A theoretical evaluation of the collective parts of the spectra is possible within the framework of the dinuclear system model, which treats the wave function of the fissioning nucleus as a superposition of a mononucleus configuration and two–cluster configurations in a dynamical way, permitting exchange of upper–shell nucleons between clusters. The impact of theoretical spectra on neutron–induced fission cross sections and, in combination with an improved version of the scission–point model, on angular distribution of fission fragments is evaluated for plutonium isotopes of interest to nuclear energy applications.

  8. Collective spectra along the fission barrier

    Science.gov (United States)

    Shneidman, T. M.; Andreev, A. V.; Pigni, M. T.; Massimi, C.; Vannini, G.; Ventura, A.

    2012-12-01

    Discrete and continuous spectra of fissioning nuclei at the humps of fission barriers (Bohr transition states) and in the intermediate wells (superdeformed and hyperdeformed states) play a key role in the calculation of fission cross sections. A theoretical evaluation of the collective parts of the spectra is possible within the framework of the dinuclear system model, which treats the wave function of the fissioning nucleus as a superposition of a mononucleus configuration and two-cluster configurations in a dynamical way, permitting exchange of upper-shell nucleons between clusters. The impact of theoretical spectra on neutron-induced fission cross sections and, in combination with an improved version of the scission-point model, on angular distribution of fission fragments is evaluated for plutonium isotopes of interest to nuclear energy applications.

  9. Diabetes and diet : managing dietary barriers

    NARCIS (Netherlands)

    Friele, R.D.

    1989-01-01

    This thesis reports on the barriers diabetic patients experience with their diet, and the ways they cope with these barriers. A dietary barrier is a hinderance to a person's well-being, induced by being advised a diet. First inventories were made of possible dietary barriers and ways of

  10. Instantaneous Tunneling Flight Time for Wavepacket Transmission through Asymmetric Barriers.

    Science.gov (United States)

    Petersen, Jakob; Pollak, Eli

    2018-04-12

    The time it takes a particle to tunnel through the asymmetric Eckart barrier potential is investigated using Gaussian wavepackets, where the barrier serves as a model for the potential along a chemical reaction coordinate. We have previously shown that the, in principle experimentally measurable, tunneling flight time, which determines the time taken by the transmitted particle to traverse the barrier, vanishes for symmetric potentials like the Eckart and square barrier [ Petersen , J. ; Pollak , E. J. Phys. Chem. Lett. 2017 , 9 , 4017 ]. Here we show that the same result is obtained for the asymmetric Eckart barrier potential, and therefore, the zero tunneling flight time seems to be a general result for one-dimensional time-independent potentials. The wavepacket dynamics is simulated using both an exact quantum mechanical method and a classical Wigner prescription. The excellent agreement between the two methods shows that quantum coherences are not important in pure one-dimensional tunneling and reinforces the conclusion that the tunneling flight time vanishes.

  11. Chasing boundaries and cascade effects in a coupled barrier-marsh-lagoon system

    Science.gov (United States)

    Lorenzo-Trueba, Jorge; Mariotti, Giulio

    2017-08-01

    The long-term dynamic evolution of an idealized barrier-marsh-lagoon system experiencing sea-level rise is studied by coupling two existing numerical models. The barrier model accounts for the interaction between shoreface dynamics and overwash flux, which allows the occurrence of barrier drowning. The marsh-lagoon model includes both a backbarrier marsh and an interior marsh, and accounts for the modification of the wave regime associated with changes in lagoon width and depth. Overwash, the key process that connects the barrier shoreface with the marsh-lagoon ecosystems, is formulated to account for the role of the backbarrier marsh. Model results show that a number of factors that are not typically associated with the dynamics of coastal barriers can enhance the rate of overwash-driven landward migration by increasing backbarrier accommodation space. For instance, lagoon deepening could be triggered by marsh edge retreat and consequent export of fine sediment via tidal dispersion, as well as by an expansion of inland marshes and consequent increase in accommodation space to be filled in with sediment. A deeper lagoon results in a larger fraction of sediment overwash being subaqueous, which coupled with a slow shoreface response sending sediment onshore can trigger barrier drowning. We therefore conclude that the supply of fine sediments to the back-barrier and the dynamics of both the interior and backbarrier marsh can be essential for maintaining the barrier system under elevated rates of sea-level rise. Our results highlight the importance of considering barriers and their associated backbarriers as part of an integrated system in which sediment is exchanged.

  12. Skin Barrier Function and Allergens

    DEFF Research Database (Denmark)

    Engebretsen, Kristiane Aasen; Thyssen, Jacob Pontoppidan

    2016-01-01

    and skin barrier status. Psoriasis has traditionally been regarded a Th1-dominated disease, but the discovery of Th17 cells and IL-17 provides new and interesting information regarding the pathogenesis of the disease. Research suggests an inverse relationship between psoriasis and CA, possibly due......The skin is an important barrier protecting us from mechanical insults, microorganisms, chemicals and allergens, but, importantly, also reducing water loss. A common hallmark for many dermatoses is a compromised skin barrier function, and one could suspect an elevated risk of contact sensitization...... to increased levels of Th17 cells and its associated cytokines. As for AD, a positive association to CS has been established in epidemiological studies, but is still unresolved. Experimental studies show, however, an inverse relationship between AD and CS. The opposing and antagonistic influences of Th1 (CS...

  13. Generation of the vortex train using plasma barrier discharge actuator

    Czech Academy of Sciences Publication Activity Database

    Procházka, Pavel P.; Uruba, Václav

    2011-01-01

    Roč. 11, č. 1 (2011), s. 667-668 ISSN 1617-7061 R&D Projects: GA ČR GA101/08/1112; GA ČR GAP101/10/1230 Institutional research plan: CEZ:AV0Z20760514 Keywords : dielectric barrier discharge * vortex train * boundary layer control Subject RIV: BK - Fluid Dynamics http://onlinelibrary.wiley.com/doi/10.1002/pamm.201110323/abstract

  14. Barrier mechanisms in the Drosophila blood-brain barrier.

    Science.gov (United States)

    Hindle, Samantha J; Bainton, Roland J

    2014-01-01

    The invertebrate blood-brain barrier (BBB) 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 G-protein coupled receptor signaling were the first demonstrations of the complex adaptive mechanisms of barrier physiology. Building upon this work, the integrity of the invertebrate BBB 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 BBB 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 BBB can govern whole animal physiologies. This includes novel functions of BBB gap junctions in orchestrating synchronized neuroblast proliferation, and of BBB 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 BBB anatomy and physiology, with a focus on insights from the past 5 years, and highlight important areas for future study.

  15. Communication barriers in the family

    Directory of Open Access Journals (Sweden)

    BARBARA KOC-KOZŁOWIEC

    2017-10-01

    Full Text Available The art of communication – listening and speaking – is a major life skill, with a thorough influence on every human life. Remaining silent while the interlocutor speaks is not all that there is to the act of listening to messages. True listening is based on an intention to get involved in understanding of the other person, enjoying his or her presence, learning something from the conversation, giving assistance, or comforting the interlocutor. In the article the author describes obstacles (barriers, which render true listening impossible. These barriers have been identified by a group of young adults.

  16. 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

  17. 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.

  18. Roadside vegetation barrier designs to mitigate near-road air pollution impacts.

    Science.gov (United States)

    Tong, Zheming; Baldauf, Richard W; Isakov, Vlad; Deshmukh, Parikshit; Max Zhang, K

    2016-01-15

    With increasing evidence that exposures to air pollution near large roadways increases risks of a number of adverse human health effects, identifying methods to reduce these exposures has become a public health priority. Roadside vegetation barriers have shown the potential to reduce near-road air pollution concentrations; however, the characteristics of these barriers needed to ensure pollution reductions are not well understood. Designing vegetation barriers to mitigate near-road air pollution requires a mechanistic understanding of how barrier configurations affect the transport of traffic-related air pollutants. We first evaluated the performance of the Comprehensive Turbulent Aerosol Dynamics and Gas Chemistry (CTAG) model with Large Eddy Simulation (LES) to capture the effects of vegetation barriers on near-road air quality, compared against field data. Next, CTAG with LES was employed to explore the effects of six conceptual roadside vegetation/solid barrier configurations on near-road size-resolved particle concentrations, governed by dispersion and deposition. Two potentially viable design options are revealed: a) a wide vegetation barrier with high Leaf Area Density (LAD), and b) vegetation-solid barrier combinations, i.e., planting trees next to a solid barrier. Both designs reduce downwind particle concentrations significantly. The findings presented in the study will assist urban planning and forestry organizations with evaluating different green infrastructure design options. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. The progression of replication forks at natural replication barriers in live bacteria.

    Science.gov (United States)

    Moolman, M Charl; Tiruvadi Krishnan, Sriram; Kerssemakers, Jacob W J; de Leeuw, Roy; Lorent, Vincent; Sherratt, David J; Dekker, Nynke H

    2016-07-27

    Protein-DNA complexes are one of the principal barriers the replisome encounters during replication. One such barrier is the Tus-ter complex, which is a direction dependent barrier for replication fork progression. The details concerning the dynamics of the replisome when encountering these Tus-ter barriers in the cell are poorly understood. By performing quantitative fluorescence microscopy with microfuidics, we investigate the effect on the replisome when encountering these barriers in live Escherichia coli cells. We make use of an E. coli variant that includes only an ectopic origin of replication that is positioned such that one of the two replisomes encounters a Tus-ter barrier before the other replisome. This enables us to single out the effect of encountering a Tus-ter roadblock on an individual replisome. We demonstrate that the replisome remains stably bound after encountering a Tus-ter complex from the non-permissive direction. Furthermore, the replisome is only transiently blocked, and continues replication beyond the barrier. Additionally, we demonstrate that these barriers affect sister chromosome segregation by visualizing specific chromosomal loci in the presence and absence of the Tus protein. These observations demonstrate the resilience of the replication fork to natural barriers and the sensitivity of chromosome alignment to fork progression. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

  20. Barriers against psychosocial communication: oncologists' perceptions.

    Science.gov (United States)

    Fagerlind, Hanna; Kettis, Åsa; Glimelius, Bengt; Ring, Lena

    2013-10-20

    To explore oncologists' psychosocial attitudes and beliefs and their perceptions regarding barriers against psychosocial communication. A questionnaire was distributed to oncologists in Sweden (n = 537). Questions covered demography, the Physician Psychosocial Beliefs Scale (PPBS), and barriers against psychosocial communication. Stepwise multiple regression was used to determine what factors contribute the most to the PPBS score and the total number of barriers and barriers affecting clinical practice, respectively. Spearman rank-order correlation was used to determine correlation between PPBS score and number of barriers. Questionnaire response rate was 64%. Mean PPBS value was 85.5 (range, 49 to 123; SD, 13.0). Most oncologists (93%) perceived one or more barriers in communicating psychosocial aspects with patients. On average, five different communication barriers were perceived, of which most were perceived to affect clinical practice. These barriers included insufficient consultation time, lack of resources for taking care of problems discovered, and lack of methods to evaluate patients' psychosocial health in clinical practice. There was a positive correlation (rs = 0.490; P barriers (ie, less psychosocially oriented oncologists perceived more barriers). Oncologists with supplementary education with a psychosocial focus perceived fewer barriers/barriers affecting clinical practice (P barriers affecting psychosocial communication in clinical practice. Interventions aiming to improve psychosocial communication must therefore be multifaceted and individualized to clinics and individual oncologists. It is important to minimize barriers to facilitate optimal care and treatment of patients with cancer.

  1. Plastic Schottky barrier solar cells

    Science.gov (United States)

    Waldrop, James R.; Cohen, Marshall J.

    1984-01-24

    A photovoltaic cell structure is fabricated from an active medium including an undoped, intrinsically p-type organic semiconductor comprising polyacetylene. When a film of such material is in rectifying contact with a magnesium electrode, a Schottky-barrier junction is obtained within the body of the cell structure. Also, a gold overlayer passivates the magnesium layer on the undoped polyacetylene film.

  2. Structure information from fusion barriers

    Indian Academy of Sciences (India)

    test or a 'fingerprint' of the structure information of the colliding nuclei. Examples are presented with same fusion barrier distributions for nuclei having different structures. The fusion excitation functions for. ½. O+ ѕј. Pb, using the coupled reaction channel (CRC) method and correct structure information, have been analysed.

  3. Functional barriers: Properties and evaluation

    NARCIS (Netherlands)

    Feigenbaum, A.; Dole, P.; Aucejo, S.; Dainelli, D.; Cruz Garcia, C. de la; Hankemeier, T.; N'Gono, Y.; Papaspyrides, C.D.; Paseiro, P.; Pastorelli, S.; Pavlidou, S.; Pennarun, P.Y.; Saillard, P.; Vidal, L.; Vitrac, O.; Voulzatis, Y.

    2005-01-01

    Functional barriers are multilayer structures deemed to prevent migration of some chemicals released by food-contact materials into food. In the area of plastics packaging, different migration behaviours of mono- and multilayer structures are assessed in terms of lag time and of their influence of

  4. Structure information from fusion barriers

    Indian Academy of Sciences (India)

    effects on the fusion excitation function. However, a simultaneous analysis of the fusion, elastic and quasi-elastic channels would fix the structure and the reaction unambiguously. Keywords. Heavy ion fusion; fusion barrier distributions; nuclear structure; coupled reaction chan- nel calculations. PACS Nos 25.70.Bc; 25.70.

  5. Results of falling barrier analyses

    International Nuclear Information System (INIS)

    Fox, G.L.

    1994-01-01

    This document assesses the consequences if the isolation barrier plate is dropped and falls over on the fuel stored in the water-filled K-East basin. The water slows the rate of fall and some canister bending is expected but only a few rods, if any, would get crushed. The basin criticality calculations will not be affected

  6. Seasonal breaching of coastal barriers

    NARCIS (Netherlands)

    Tuan, Thieu Quang

    2007-01-01

    Natural or unintended breaching can be catastrophic, causing loss of human lives and damage to infrastructures, buildings and natural habitats. Quantitative understand-ing of coastal barrier breaching is therefore of great importance to vulnerability as-sessment of protection works as well as to

  7. Reaction rates when barriers fluctuate

    OpenAIRE

    Reimann, Peter

    1999-01-01

    Reaction rates when barriers fluctuate : a path integral approach / P. Hänggi and P. Reimann. - In: International Conference on Path Integrals from peV to TeV : Proceedings of the ... / eds.: R. Casalbuoni ... - Singapore u.a. : World Scientific, 1999. - S. 407-409

  8. Altered permeability barrier structure in cholesteatoma matrix

    DEFF Research Database (Denmark)

    Svane-Knudsen, Viggo; Halkier-Sørensen, Lars; Rasmussen, Gurli

    2002-01-01

    lipid structures filling the intercellular spaces mainly control the barrier function. The barrier in cholesteatoma epithelium is several times thicker than in unaffected skin but presents distinctive features of a defective barrier as seen in other scaling skin diseases. The intercellular spaces appear...... frequently occur. The corneocytes are shed in clusters, not as single cells. Further, lipid droplets and intracellular membranous material are occasionally seen. In spite of these clear signs of barrier dysfunction, it is unknown whether the thickness of the barrier compensates for the defect in barrier...

  9. Optimization by record dynamics

    DEFF Research Database (Denmark)

    Barettin, Daniele; Sibani, Paolo

    2014-01-01

    Large dynamical changes in thermalizing glassy systems are triggered by trajectories crossing record sized barriers, a behavior revealing the presence of a hierarchical structure in configuration space. The observation is here turned into a novel local search optimization algorithm dubbed record...... dynamics optimization,or RDO. RDO uses the Metropolis rule to accept or reject candidate solutions depending on the value of a parameter akin to the temperature and minimizes the cost function of the problem at hand through cycles where its ‘temperature’ is raised and subsequently decreased in order...

  10. A new physical barrier system for seawater intrusion control

    Science.gov (United States)

    Abdoulhalik, Antoifi; Ahmed, Ashraf; Hamill, G. A.

    2017-06-01

    The construction of subsurface physical barriers is one of various methods used to control seawater intrusion (SWI) in coastal aquifers. This study proposes the mixed physical barrier (MPB) as a new barrier system for seawater intrusion control, which combines an impermeable cutoff wall and a semi-permeable subsurface dam. The effect of the traditionally-used physical barriers on transient saltwater wedge dynamics was first explored for various hydraulic gradients, and the workability of the MPB was thereafter thoroughly analysed. A newly developed automated image analysis based on light-concentration conversion was used in the experiments, which were completed in a porous media tank. The numerical code SEAWAT was used to assess the consistency of the experimental data and examine the sensitivity of the performance of the barriers to various key parameters. The results show that the MPB induced a visible lifting of the dense saline flux upward towards the outlet by the light freshwater. This saltwater lifting mechanism, observed for the first time, induced significant reduction to the saline water intrusion length. The use of the MPB yielded up to 62% and 42% more reduction of the saltwater intrusion length than the semi-permeable dam and the cutoff wall, respectively. The performance achieved by the MPB with a wall depth of 40% of the aquifer thickness was greater than that of a single cutoff wall with a penetration depth of 90% of the aquifer thickness (about 13% extra reduction). This means that the MPB could produce better seawater intrusion reduction than the traditionally used barriers at even lower cost.

  11. Not Only Enthalpy: Large Entropy Contribution to Ion Permeation Barriers in Single-File Channels

    OpenAIRE

    Portella, Guillem; Hub, Jochen S.; Vesper, Martin D.; de Groot, Bert L.

    2008-01-01

    The effect of channel length on the barrier for potassium ion permeation through single-file channels has been studied by means of all-atom molecular dynamics simulations. Using series of peptidic gramicidin-like and simplified ring-structured channels, both embedded in model membranes, we obtained two distinct types of behavior: saturation of the central free energy barriers for peptidic channels and a linear increase in simplified ring-structured channels with increasing channel length. The...

  12. Highway renewable energy : photovoltaic noise barriers

    Science.gov (United States)

    2017-07-01

    Highway photovoltaic noise barriers (PVNBs) represent the combination of noise barrier systems and photovoltaic systems in order to mitigate traffic noise while simultaneously producing renewable energy. First deployed in Switzerland in 1989, PVNBs a...

  13. Prototype Hanford Surface Barrier: Design basis document

    International Nuclear Information System (INIS)

    Myers, D.R.; Duranceau, D.A.

    1994-11-01

    The Hanford Site Surface Barrier Development Program (BDP) was organized in 1985 to develop the technology needed to provide a long-term surface barrier capability for the Hanford Site and other arid sites. This document provides the basis of the prototype barrier. Engineers and scientists have momentarily frozen evolving barrier designs and incorporated the latest findings from BDP tasks. The design and construction of the prototype barrier has required that all of the various components of the barrier be brought together into an integrated system. This integration is particularly important because some of the components of the protective barreir have been developed independently of other barreir components. This document serves as the baseline by which future modifications or other barrier designs can be compared. Also, this document contains the minutes of meeting convened during the definitive design process in which critical decisions affecting the prototype barrier's design were made and the construction drawings

  14. Export Barriers for Small and Medium-sized Enterprises: A Literature Review based on Leonidou’s Model

    Directory of Open Access Journals (Sweden)

    Vijay Narayanan

    2015-06-01

    Full Text Available The purpose of this article is to understand the barriers faced by small and medium-sized enterprises in their path to internationalization. The intention of this paper is to provide an overview about the barriers faced by SMEs in their path to internationalization and discuss in detail different approaches taken by SMEs to overcome these barriers. This article is a literature review on the barriers faced by SMEs in internationalization and new approaches in this domain based on Leonidou’s (1995, 1998, 2004 model of export barrier classification. Modern approaches by SMEs are effective in handling most of the traditional challenges posed in internationalization. Firms have evolved in handling internal barriers by finding dynamic solutions from within. SMEs need support from governmental and policy makers to overcome external barriers. Indications on the work to be done in overcoming certain barriers which impede the internationalization of SMEs are more in the context of external barriers. The originality of this work is in creating a framework of barriers and finding solutions to some of the identified barriers.

  15. Numerical modelling of barrier discharge

    International Nuclear Information System (INIS)

    Kozlov, K.V.

    1990-01-01

    A survey is given of the theory of the barrier discharge in oxygen at atmospheric pressure. The discharge consists of a number of randomly distributed microdischarges of nanosecond duration. This complicated space-time structure must be taken into account in any numerical model of the barrier discharge. In a single discharge channel, three consequent phases can be distinguished; 1) electric breakdown and electron-time-scale processes; 2) ion drift and ion-time-scale processes; 3) slow chemical processes, diffusion of chemical products and heat transfer. The scheme of such a three-phase model is presented and the results of simulation are discussed and compared with experimental data. (J.U.) 9 figs., 15 refs

  16. Security barriers with automated reconnaissance

    Science.gov (United States)

    McLaughlin, James O; Baird, Adam D; Tullis, Barclay J; Nolte, Roger Allen

    2015-04-07

    An intrusion delaying barrier includes primary and secondary physical structures and can be instrumented with multiple sensors incorporated into an electronic monitoring and alarm system. Such an instrumented intrusion delaying barrier may be used as a perimeter intrusion defense and assessment system (PIDAS). Problems with not providing effective delay to breaches by intentional intruders and/or terrorists who would otherwise evade detection are solved by attaching the secondary structures to the primary structure, and attaching at least some of the sensors to the secondary structures. By having multiple sensors of various types physically interconnected serves to enable sensors on different parts of the overall structure to respond to common disturbances and thereby provide effective corroboration that a disturbance is not merely a nuisance or false alarm. Use of a machine learning network such as a neural network exploits such corroboration.

  17. Barriers to nursing advocacy: a concept analysis.

    Science.gov (United States)

    Hanks, Robert G

    2007-01-01

    Advocacy for clients is viewed as an essential function of nursing; however, to be effective advocates for patients, the nurse must often overcome barriers to being an effective advocate. This concept analysis of barriers to nursing advocacy uses the Walker and Avant method of concept analysis. By analyzing the barriers to effective nursing advocacy for clients, nursing can then find strategies to manage those barriers and maximize the nurse's advocacy efforts.

  18. Perceptions regarding strategic and structural entry barriers

    OpenAIRE

    Lutz, C.H.M.; Kemp, R.G.M.; Dijkstra, S.G.

    2010-01-01

    This article uses factor analysis to identify the underlying dimensions of strategic and structural entry barriers. We find that, in the perception of firms, both types of barriers are important and that the effectiveness of strategic barriers depends on attributes of the market structure. Based on the seven generic factors, a conjoint analysis is carried out to identify the most important factors perceived by firms. The conjoint analysis shows that in particular the barriers rooted in three ...

  19. Sea sand for reactive barriers

    International Nuclear Information System (INIS)

    Garcia R, G.; Ordonez R, E.; Ordonez R, En.

    2002-01-01

    Some phosphates have the property to suck in radioactive metals in solution, what it is taken in advance to make reactive barriers which are placed in the nuclear waste repositories. In an effort for contributing to the study of this type of materials, it has been obtained the zirconium silicate (ZrSiO 4 ) and the alpha zirconium hydrogen phosphate (Zr(HPO 4 ) 2H 2 O) starting from sea sand in an easy and economic way. (Author)

  20. Distributions of methyl group rotational barriers in polycrystalline organic solids

    Energy Technology Data Exchange (ETDEWEB)

    Beckmann, Peter A., E-mail: pbeckman@brynmawr.edu, E-mail: wangxianlong@uestc.edu.cn [Department of Physics, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, Pennsylvania 19010-2899 (United States); Conn, Kathleen G. [Department of Physics, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, Pennsylvania 19010-2899 (United States); Division of Education and Human Services, Neumann University, One Neumann Drive, Aston, Pennsylvania 19014-1298 (United States); Mallory, Clelia W. [Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323 (United States); Department of Chemistry, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, Pennsylvania 19010-2899 (United States); Mallory, Frank B. [Department of Chemistry, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, Pennsylvania 19010-2899 (United States); Rheingold, Arnold L. [Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Dr., La Jolla, California 92093-0358 (United States); Rotkina, Lolita [Regional Nanotechnology Facility, Laboratory for Research on the Structure of Matter, University of Pennsylvania, 3231 Walnut Street, Philadelphia, Pennsylvania 19104-6202 (United States); Wang, Xianlong, E-mail: pbeckman@brynmawr.edu, E-mail: wangxianlong@uestc.edu.cn [Key Laboratory for NeuroInformation of Ministry of Education, School of Life Science and Technology, University of Electronic Science and Technology, 4 North Jianshe Rd., 2nd Section, Chengdu 610054 (China)

    2013-11-28

    We bring together solid state {sup 1}H spin-lattice relaxation rate measurements, scanning electron microscopy, single crystal X-ray diffraction, and electronic structure calculations for two methyl substituted organic compounds to investigate methyl group (CH{sub 3}) rotational dynamics in the solid state. Methyl group rotational barrier heights are computed using electronic structure calculations, both in isolated molecules and in molecular clusters mimicking a perfect single crystal environment. The calculations are performed on suitable clusters built from the X-ray diffraction studies. These calculations allow for an estimate of the intramolecular and the intermolecular contributions to the barrier heights. The {sup 1}H relaxation measurements, on the other hand, are performed with polycrystalline samples which have been investigated with scanning electron microscopy. The {sup 1}H relaxation measurements are best fitted with a distribution of activation energies for methyl group rotation and we propose, based on the scanning electron microscopy images, that this distribution arises from molecules near crystallite surfaces or near other crystal imperfections (vacancies, dislocations, etc.). An activation energy characterizing this distribution is compared with a barrier height determined from the electronic structure calculations and a consistent model for methyl group rotation is developed. The compounds are 1,6-dimethylphenanthrene and 1,8-dimethylphenanthrene and the methyl group barriers being discussed and compared are in the 2–12 kJ mol{sup −1} range.

  1. Improved performance thermal barrier coatings

    International Nuclear Information System (INIS)

    Levine, S.R.; Miller, R.A.; Stecura, S.

    1983-01-01

    Thermal barrier coatings offer an attractive approach to improving the durability and efficiency of the hot section of heat engines. The coatings typically consist of an inner alloy bond coating about 0.01 cm thick resistant to oxidation and hot corrosion and an outer ceramic layer, usually a stabilized zirconia, 0.01-0.05 cm thick. Here, the materials, thermomechanical stress, and hot corrosion problems associated with thermal barrier coatings are reviewed along with the capabilities and limitations of current technology. The coatings discussed include ZrO2-Y2O3/NiCrAlY, ZrO2-Y2O3/NiCoCrAlY, ZrO2-MgO/NiCoCrAlY, CaO-SiO2/Co-Cr-Al-Y, and CaO-SiO2/NiCrAlY systems. It is emphasized that the performance of thermal barrier coatings is governed by many complex and interrelated factors, so that optimization of these coatings always involves certain tradeoffs. 27 references

  2. Addressing barriers to safe abortion.

    Science.gov (United States)

    Culwell, Kelly R; Hurwitz, Manuelle

    2013-05-01

    The latest World Health Organization data estimate that the total number of unsafe abortions globally has increased to 21.6 million in 2008. There is increasing recognition by the international community of the importance of the contribution of unsafe abortion to maternal mortality. However, the barriers to delivery of safe abortion services are many. In 68 countries, home to 26% of the world's population, abortion is prohibited altogether or only permitted to save a woman's life. Even in countries with more liberal abortion legal frameworks, additional social, economic, and health systems barriers and the stigma surrounding abortion prevent adequate access to safe abortion services and postabortion care. While much has been achieved to reduce the barriers to comprehensive abortion care, much remains to be done. Only through the concerted action of public, private, and civil society partners can we ensure that women have access to services that are safe, affordable, confidential, and stigma free. Copyright © 2013 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.

  3. Market barriers to welfare product innovations

    NARCIS (Netherlands)

    Binnekamp, M.H.A.; Ingenbleek, P.T.M.

    2006-01-01

    New products that are based on higher animal welfare standards encounter several barriers on the road to market acceptance. The authors focus on the Dutch poultry sector and distinguish between retailer and consumer barriers. Retailer barriers include the powerful position of retailers, the price

  4. Barriers to Mammography among Inadequately Screened Women

    Science.gov (United States)

    Stoll, Carolyn R. T.; Roberts, Summer; Cheng, Meng-Ru; Crayton, Eloise V.; Jackson, Sherrill; Politi, Mary C.

    2015-01-01

    Mammography use has increased over the past 20 years, yet more than 30% of women remain inadequately screened. Structural barriers can deter individuals from screening, however, cognitive, emotional, and communication barriers may also prevent mammography use. This study sought to identify the impact of number and type of barriers on mammography…

  5. Perceptions regarding strategic and structural entry barriers

    NARCIS (Netherlands)

    Lutz, C.H.M.; Kemp, R.G.M.; Dijkstra, S.G.

    2010-01-01

    This article uses factor analysis to identify the underlying dimensions of strategic and structural entry barriers. We find that, in the perception of firms, both types of barriers are important and that the effectiveness of strategic barriers depends on attributes of the market structure. Based on

  6. Perceptions regarding strategic and structural entry barriers

    NARCIS (Netherlands)

    Lutz, Clemens H. M.; Kemp, Ron G. M.; Dijkstra, S. Gerhard

    This article uses factor analysis to identify the underlying dimensions of strategic and structural entry barriers. We find that, in the perception of firms, both types of barriers are important and that the effectiveness of strategic barriers depends on attributes of the market structure. Based on

  7. Article Including Environmental Barrier Coating System

    Science.gov (United States)

    Lee, Kang N. (Inventor)

    2015-01-01

    An enhanced environmental barrier coating for a silicon containing substrate. The enhanced barrier coating may include a bond coat doped with at least one of an alkali metal oxide and an alkali earth metal oxide. The enhanced barrier coating may include a composite mullite bond coat including BSAS and another distinct second phase oxide applied over said surface.

  8. The Barriers and Needs of Online Learners

    Science.gov (United States)

    Srichanyachon, Napaporn

    2014-01-01

    This study investigated some specific barriers and needs that online students are facing when learning English through WebEx system. It compared students' barriers and needs with their background including gender, computer ownership, and monthly allowance. It also investigated the relationship among computer aptitude, barriers and needs of online…

  9. Advanced transport modeling of toroidal plasmas with transport barriers

    International Nuclear Information System (INIS)

    Fukuyama, A.; Murakami, S.; Honda, M.; Izumi, Y.; Yagi, M.; Nakajima, N.; Nakamura, Y.; Ozeki, T.

    2005-01-01

    Transport modeling of toroidal plasmas is one of the most important issue to predict time evolution of burning plasmas and to develop control schemes in reactor plasmas. In order to describe the plasma rotation and rapid transition self-consistently, we have developed an advanced scheme of transport modeling based on dynamical transport equation and applied it to the analysis of transport barrier formation. First we propose a new transport model and examine its behavior by the use of conventional diffusive transport equation. This model includes the electrostatic toroidal ITG mode and the electromagnetic ballooning mode and successfully describes the formation of internal transport barriers. Then the dynamical transport equation is introduced to describe the plasma rotation and the radial electric field self-consistently. The formation of edge transport barriers is systematically studied and compared with experimental observations. The possibility of kinetic transport modeling in velocity space is also examined. Finally the modular structure of integrated modeling code for tokamaks and helical systems is discussed. (author)

  10. Debris flow impact estimation on a rigid barrier

    Science.gov (United States)

    Vagnon, Federico; Segalini, Andrea

    2016-07-01

    The aim of this paper is to analyse debris flow impact against rigid and undrained barrier in order to propose a new formulation for the estimation of acting force after the flow impact to safe design protection structures. For this reason, this work concentrates on the flow impact, by performing a series of small scale tests in a specifically created flume. Flow characteristics (flow height and velocity) and applied loads (dynamic and static) on barrier were measured using four ultrasonic devices, four load cells and a contact surface pressure gauge. The results obtained were compared with main existing models and a new equation is proposed. Furthermore, a brief review of the small scale theory was provided to analyse the scale effects that can affect the results.

  11. Computational Design and Experimental Validation of New Thermal Barrier Systems

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Shengmin; Yang, Shizhong; Khosravi, Ebrahim

    2012-10-01

    This project (10/01/2010-9/30/2013), “Computational Design and Experimental Validation of New Thermal Barrier Systems”, originates from Louisiana State University (LSU) Mechanical Engineering Department and Southern University (SU) Department of Computer Science. This project will directly support the technical goals specified in DEFOA- 0000248, Topic Area 3: Turbine Materials, by addressing key technologies needed to enable the development of advanced turbines and turbine-based systems that will operate safely and efficiently using coal-derived synthesis gases. We will develop and implement novel molecular dynamics method to improve the efficiency of simulation on novel TBC materials; perform high performance computing (HPC) on complex TBC structures to screen the most promising TBC compositions; perform material characterizations and oxidation/corrosion tests; and demonstrate our new thermal barrier coating (TBC) systems experimentally under integrated gasification combined cycle (IGCC) environments. The durability of the coating will be examined using the proposed Durability Test Rig.

  12. Computational design and experimental validation of new thermal barrier systems

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Shengmin [Louisiana State Univ., Baton Rouge, LA (United States)

    2015-03-31

    The focus of this project is on the development of a reliable and efficient ab initio based computational high temperature material design method which can be used to assist the Thermal Barrier Coating (TBC) bond-coat and top-coat design. Experimental evaluations on the new TBCs are conducted to confirm the new TBCs’ properties. Southern University is the subcontractor on this project with a focus on the computational simulation method development. We have performed ab initio density functional theory (DFT) method and molecular dynamics simulation on screening the top coats and bond coats for gas turbine thermal barrier coating design and validation applications. For experimental validations, our focus is on the hot corrosion performance of different TBC systems. For example, for one of the top coatings studied, we examined the thermal stability of TaZr2.75O8 and confirmed it’s hot corrosion performance.

  13. Chemical barriers for controlling groundwater contamination

    International Nuclear Information System (INIS)

    Morrison, S.J.; Spangler, R.R.

    1993-01-01

    Chemical barriers are being explored as a low-cost means of controlling groundwater contamination. The barrier can intercept a contaminant plume and prevent migration by transferring contaminants from the groundwater to immobile solids. A chemical barrier can be emplaced in a landfill liner or in an aquifer cutoff wall or can be injected into a contaminant plume. Chemical barriers can be classified as either precipitation barriers or sorption barriers depending upon the dominant mode of contaminant extraction. In a precipitation barrier, contaminants are bound in the structures of newly formed phases; whereas, in a sorption barrier, contaminants attach to the surfaces of preexisting solids by adsorption or some other surface mechanism. Sorption of contaminants is pH dependent. A precipitation barrier can control the pH of the system, but alkaline groundwater may dominate the pH in a sorption barrier. A comparison is made of the characteristics of precipitation and sorption barriers. Experimental data on the extraction of uranium and molybdenum from simulated groundwater are used to demonstrate these concepts. 10 refs., 9 figs., 1 tab

  14. Dynamic modeling of oil boom failure using computational fluid dynamics

    International Nuclear Information System (INIS)

    Goodman, R. H.; Brown, H. M.; An, C. F.; Rowe, R. D.

    1997-01-01

    Oil retention boom failure mechanisms have been identified and studied using computational fluid dynamics (CFD), a powerful modeling tool combining fluid dynamics and mathematics with high speed computer technology. This study utilized a commercially available CFD package, 'Fluent', to simulate the oil-water flow around a barrier. 'Drainage failure', 'droplet entrainment' and 'critical accumulation' were modeled using this software. Flow characteristics were found to be different for different failure mechanisms. In the drainage failure process, the oil slick was compressed against the barrier until the slick was deep enough for the oil to leak under the barrier. During boom failure due to droplet entrainment, the oil-water interface of the oil slick was wavy and unstable. During boom failure due to critical accumulation, the oil remained a single mass and moved under the barrier readily. The most significant observation, however, was that flow patterns around barriers are modified by the presence of oil. Therefore, towing and wave-conformity tests of booms will not be meaningful unless such tests are conducted with oil present. 15 refs., 11 figs

  15. Mediated Intercultural Communication Barrier in No Drama Zone! Group

    OpenAIRE

    Lizal, Valentino

    2015-01-01

    This research study aimed to describe the mediated intercultural communication barriers in the No Drama Zone! group. This study is a qualitative descriptive type of research, with case study method. By doing in depth interview and observation, researcher found two barriers that generates other barriers in the group's mediated intercultural communication. The two big barriers were: language and physical barriers. Language barriers in this group generated two barriers, emotional barrier and pe...

  16. A prospective examination of exercise and barrier self-efficacy to engage in leisure-time physical activity during pregnancy.

    Science.gov (United States)

    Cramp, Anita G; Bray, Steven R

    2009-06-01

    Pregnant women without medical contraindications should accumulate 30 min of moderate exercise on most days of the week, yet many pregnant women do not exercise at recommended levels. The purpose the study was to examine barriers to leisure-time physical activity (LTPA) and investigate barrier and exercise self-efficacy as predictors of self-reported LTPA during pregnancy. Pregnant women (n = 160) completed questionnaires eliciting barriers to LTPA, measures of exercise and barrier self-efficacy, and 6-week LTPA recall at gestational weeks 18, 24, 30, and 36. A total of 1,168 barriers were content-analyzed, yielding nine major themes including fatigue, time constraints, and physical limitations. Exercise self-efficacy predicted LTPA from gestational weeks 18 to 24 (beta = 0.32, R(2) = 0.26) and weeks 30 to 36 (beta = 0.41, R(2) = 0.37), while barrier self-efficacy predicted LTPA from weeks 24 to 30 (beta = 0.40, R(2) = 0.32). Pregnant women face numerous barriers to LTPA during pregnancy, the nature of which may change substantially over the course of pregnancy. Higher levels of self-efficacy to exercise and to overcome exercise barriers are associated with greater LTPA during pregnancy. Research and interventions to understand and promote LTPA during pregnancy should explore the dynamic nature of exercise barriers and foster women's confidence to overcome physical activity barriers.

  17. THE BARRIERS AND NEEDS OF ONLINE LEARNERS

    Directory of Open Access Journals (Sweden)

    Napaporn SRICHANYACHON

    2014-07-01

    Full Text Available This study investigated some specific barriers and needs that online students are facing when learning English through WebEx system. It compared students’ barriers and needs with their background including gender, computer ownership, and monthly allowance. It also investigated the relationship among computer aptitude, barriers and needs of online learners. The samples were 211 undergraduate students enrolled in Fundamental English course. The instrument in this study was a questionnaire. Results indicated that the levels of needs and barriers of online learners in general were moderate. There were no statistically significant differences at .05 level found in barriers and needs of online learners as classified by gender, computer ownership, and computer aptitude. As hypothesised, there was a negative relationship between computer aptitude and barriers of online learners at .01 level. Students with high computer aptitude had fewer barriers to learn online than those with low computer aptitude. In addition, there was a positive relationship between barriers and needs of online learners at .01 levels. Students with more barriers were found to have more needs to help them to learn online than those with few barriers. Teachers and institutions can take the results of this study into consideration when developing online courses.

  18. Subsurface barrier verification technologies, informal report

    International Nuclear Information System (INIS)

    Heiser, J.H.

    1994-06-01

    One of the more promising remediation options available to the DOE waste management community is subsurface barriers. Some of the uses of subsurface barriers include surrounding and/or containing buried waste, as secondary confinement of underground storage tanks, to direct or contain subsurface contaminant plumes and to restrict remediation methods, such as vacuum extraction, to a limited area. To be most effective the barriers should be continuous and depending on use, have few or no breaches. A breach may be formed through numerous pathways including: discontinuous grout application, from joints between panels and from cracking due to grout curing or wet-dry cycling. The ability to verify barrier integrity is valuable to the DOE, EPA, and commercial sector and will be required to gain full public acceptance of subsurface barriers as either primary or secondary confinement at waste sites. It is recognized that no suitable method exists for the verification of an emplaced barrier's integrity. The large size and deep placement of subsurface barriers makes detection of leaks challenging. This becomes magnified if the permissible leakage from the site is low. Detection of small cracks (fractions of an inch) at depths of 100 feet or more has not been possible using existing surface geophysical techniques. Compounding the problem of locating flaws in a barrier is the fact that no placement technology can guarantee the completeness or integrity of the emplaced barrier. This report summarizes several commonly used or promising technologies that have been or may be applied to in-situ barrier continuity verification

  19. Barriers to Medical Error Reporting.

    Science.gov (United States)

    Poorolajal, Jalal; Rezaie, Shirin; Aghighi, Negar

    2015-01-01

    This study was conducted to explore the prevalence of medical error underreporting and associated barriers. This cross-sectional study was performed from September to December 2012. Five hospitals, affiliated with Hamadan University of Medical Sciences, in Hamedan, Iran were investigated. A self-administered questionnaire was used for data collection. Participants consisted of physicians, nurses, midwives, residents, interns, and staffs of radiology and laboratory departments. Overall, 50.26% of subjects had committed but not reported medical errors. The main reasons mentioned for underreporting were lack of effective medical error reporting system (60.0%), lack of proper reporting form (51.8%), lack of peer supporting a person who has committed an error (56.0%), and lack of personal attention to the importance of medical errors (62.9%). The rate of committing medical errors was higher in men (71.4%), age of 50-40 years (67.6%), less-experienced personnel (58.7%), educational level of MSc (87.5%), and staff of radiology department (88.9%). This study outlined the main barriers to reporting medical errors and associated factors that may be helpful for healthcare organizations in improving medical error reporting as an essential component for patient safety enhancement.

  20. Antibiotic stewardship: overcoming implementation barriers.

    Science.gov (United States)

    Bal, Abhijit M; Gould, Ian M

    2011-08-01

    Antimicrobial stewardship is now recognized as a formal strategy for curbing the upward trend in antibiotic resistance. Literature on antimicrobial stewardship has focused on areas of strategic importance and operational delivery. A number of barriers have been recognized in the implementation of successful programs. These include lack of physician participation, lack of diagnostic facility, absence of formal mechanism of data collection, variation between countries, and lack of cooperative strategies. In this review, we suggest strategies to overcome these barriers. In the last few years, it has been recognized that an executive program is necessary for successful implementation of strategies to control the growing antibiotic resistance. Efforts have been made at higher levels of government through organizations such as the European Centre for Disease Prevention and Control. The need for community healthcare involvement has also been recognized. At a local level, strategies to promote cooperation between various committees (e.g. infection control and antimicrobial management teams) have been proposed and adopting antibiotic care bundles as part of patient safety and healthcare is being explored. We suggest that executive level planning, local cooperation, sustained education, emphasis on de-escalation, and use of care bundles could stem the tide of growing resistance.

  1. Barriers to medical error reporting

    Directory of Open Access Journals (Sweden)

    Jalal Poorolajal

    2015-01-01

    Full Text Available Background: This study was conducted to explore the prevalence of medical error underreporting and associated barriers. Methods: This cross-sectional study was performed from September to December 2012. Five hospitals, affiliated with Hamadan University of Medical Sciences, in Hamedan,Iran were investigated. A self-administered questionnaire was used for data collection. Participants consisted of physicians, nurses, midwives, residents, interns, and staffs of radiology and laboratory departments. Results: Overall, 50.26% of subjects had committed but not reported medical errors. The main reasons mentioned for underreporting were lack of effective medical error reporting system (60.0%, lack of proper reporting form (51.8%, lack of peer supporting a person who has committed an error (56.0%, and lack of personal attention to the importance of medical errors (62.9%. The rate of committing medical errors was higher in men (71.4%, age of 50-40 years (67.6%, less-experienced personnel (58.7%, educational level of MSc (87.5%, and staff of radiology department (88.9%. Conclusions: This study outlined the main barriers to reporting medical errors and associated factors that may be helpful for healthcare organizations in improving medical error reporting as an essential component for patient safety enhancement.

  2. Barriers over time to full implementation of health information exchange in the United States.

    Science.gov (United States)

    Kruse, Clemens Scott; Regier, Verna; Rheinboldt, Kurt T

    2014-09-30

    Although health information exchanges (HIE) have existed since their introduction by President Bush in his 2004 State of the Union Address, and despite monetary incentives earmarked in 2009 by the health information technology for economic and clinical health (HITECH) Act, adoption of HIE has been sparse in the United States. Research has been conducted to explore the concept of HIE and its benefit to patients, but viable business plans for their existence are rare, and so far, no research has been conducted on the dynamic nature of barriers over time. The aim of this study is to map the barriers mentioned in the literature to illustrate the effect, if any, of barriers discussed with respect to the HITECH Act from 2009 to the early months of 2014. We conducted a systematic literature review from CINAHL, PubMed, and Google Scholar. The search criteria primarily focused on studies. Each article was read by at least two of the authors, and a final set was established for evaluation (n=28). The 28 articles identified 16 barriers. Cost and efficiency/workflow were identified 15% and 13% of all instances of barriers mentioned in literature, respectively. The years 2010 and 2011 were the most plentiful years when barriers were discussed, with 75% and 69% of all barriers listed, respectively. The frequency of barriers mentioned in literature demonstrates the mindfulness of users, developers, and both local and national government. The broad conclusion is that public policy masks the effects of some barriers, while revealing others. However, a deleterious effect can be inferred when the public funds are exhausted. Public policy will need to lever incentives to overcome many of the barriers such as cost and impediments to competition. Process improvement managers need to optimize the efficiency of current practices at the point of care. Developers will need to work with users to ensure tools that use HIE resources work into existing workflows.

  3. Perspective: chemical dynamics simulations of non-statistical reaction dynamics.

    Science.gov (United States)

    Ma, Xinyou; Hase, William L

    2017-04-28

    Non-statistical chemical dynamics are exemplified by disagreements with the transition state (TS), RRKM and phase space theories of chemical kinetics and dynamics. The intrinsic reaction coordinate (IRC) is often used for the former two theories, and non-statistical dynamics arising from non-IRC dynamics are often important. In this perspective, non-statistical dynamics are discussed for chemical reactions, with results primarily obtained from chemical dynamics simulations and to a lesser extent from experiment. The non-statistical dynamical properties discussed are: post-TS dynamics, including potential energy surface bifurcations, product energy partitioning in unimolecular dissociation and avoiding exit-channel potential energy minima; non-RRKM unimolecular decomposition; non-IRC dynamics; direct mechanisms for bimolecular reactions with pre- and/or post-reaction potential energy minima; non-TS theory barrier recrossings; and roaming dynamics.This article is part of the themed issue 'Theoretical and computational studies of non-equilibrium and non-statistical dynamics in the gas phase, in the condensed phase and at interfaces'. © 2017 The Author(s).

  4. Controlling the quantum rotational dynamics of a driven planar rotor ...

    Indian Academy of Sciences (India)

    Archana Shukla

    quantum dynamics as well. In particular, the efficiency of the phase space barriers towards controlling dynamical tunneling in the system is explored. Our studies are relevant to understanding the role of the chaotic regions in dynamical tunneling and for molecular alignment using bichromatic fields. Keywords. Rigid rotor ...

  5. Barrier experiment: Shock initiation under complex loading

    Energy Technology Data Exchange (ETDEWEB)

    Menikoff, Ralph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-01-12

    The barrier experiments are a variant of the gap test; a detonation wave in a donor HE impacts a barrier and drives a shock wave into an acceptor HE. The question we ask is: What is the trade-off between the barrier material and threshold barrier thickness to prevent the acceptor from detonating. This can be viewed from the perspective of shock initiation of the acceptor subject to a complex pressure drive condition. Here we consider key factors which affect whether or not the acceptor undergoes a shock-to-detonation transition. These include the following: shock impedance matches for the donor detonation wave into the barrier and then the barrier shock into the acceptor, the pressure gradient behind the donor detonation wave, and the curvature of detonation front in the donor. Numerical simulations are used to illustrate how these factors affect the reaction in the acceptor.

  6. Barrier-protective effects of activated protein C in human alveolar epithelial cells.

    Directory of Open Access Journals (Sweden)

    Ferranda Puig

    Full Text Available Acute lung injury (ALI is a clinical manifestation of respiratory failure, caused by lung inflammation and the disruption of the alveolar-capillary barrier. Preservation of the physical integrity of the alveolar epithelial monolayer is of critical importance to prevent alveolar edema. Barrier integrity depends largely on the balance between physical forces on cell-cell and cell-matrix contacts, and this balance might be affected by alterations in the coagulation cascade in patients with ALI. We aimed to study the effects of activated protein C (APC on mechanical tension and barrier integrity in human alveolar epithelial cells (A549 exposed to thrombin. Cells were pretreated for 3 h with APC (50 µg/ml or vehicle (control. Subsequently, thrombin (50 nM or medium was added to the cell culture. APC significantly reduced thrombin-induced cell monolayer permeability, cell stiffening, and cell contraction, measured by electrical impedance, optical magnetic twisting cytometry, and traction microscopy, respectively, suggesting a barrier-protective response. The dynamics of the barrier integrity was also assessed by western blotting and immunofluorescence analysis of the tight junction ZO-1. Thrombin resulted in more elongated ZO-1 aggregates at cell-cell interface areas and induced an increase in ZO-1 membrane protein content. APC attenuated the length of these ZO-1 aggregates and reduced the ZO-1 membrane protein levels induced by thrombin. In conclusion, pretreatment with APC reduced the disruption of barrier integrity induced by thrombin, thus contributing to alveolar epithelial barrier protection.

  7. International medical graduate-patient communication: a qualitative analysis of perceived barriers.

    Science.gov (United States)

    Dorgan, Kelly A; Lang, Forrest; Floyd, Michael; Kemp, Evelyn

    2009-11-01

    International medical graduates (IMGs) represent a substantial portion of all medical residents in the United States. Yet, IMGs may be disadvantaged in their communications with U.S. patients for a variety of reasons. The authors conducted a qualitative study to examine IMGs' perceptions of the barriers to their communication with patients. A convenience sample of 12 IMGs participated in interviews that lasted 1 to 1.5 hours. Residents from the Caribbean, Colombia, Denmark, India, Iran, Pakistan, and Peru participated in individual interviews conducted on-site at one of three clinics. Interviews were transcribed and then coded independently and jointly. The authors used a qualitative analysis of interview transcripts to identify primary and secondary themes. IMGs' perceptions of the barriers to communication with their Appalachian patients fit into two broad themes: educational barriers and interpersonal barriers. Within each of these themes, the authors identified secondary themes: education-related barriers were science immersion and lack of communication training, and interpersonally related barriers were unfamiliar dialects, new power dynamics, and different rapport-building expectations. The analysis of the interview data yielded several important findings that residency programs should consider when designing orientations, training curricula, and communication interventions. Programs may need to address challenges related to regional dialect and "informal" English use, as well as communication barriers associated with cross-cultural differences in norms, values, and beliefs. Programs also need to draw on multilayered interventions to address the multidimensional challenges of cross-cultural physician-patient communication.

  8. Trade Barriers in a Global Perspective

    OpenAIRE

    Raihan, Selim

    2004-01-01

    This article develops an index of trade barrier for 119 countries by using the tariff and the import data from TRAINS database of UNCTAD at 6-digit level of HS classifications. Bivariate as well as multivariate econometric models have been estimated to explain cross-country variations in the constructed trade barrier indices. The results show that cross-country variations in trade barrier indices are much influenced by variations in per capita income, population and literacy rate. This articl...

  9. Methyl group dynamics in a confined glass

    OpenAIRE

    Moreno, A. J.; Colmenero, J.; Alegría, A.; Alba-Simionesco, C.; Dosseh, G.; Morineau, D.; Frick, B.

    2002-01-01

    We present a neutron scattering investigation on methyl group dynamics in glassy toluene confined in mesoporous silicates of different pore sizes. The experimental results have been analysed in terms of a barrier distribution model, such a distribution following from the structural disorder in the glassy state. Confinement results in a strong decreasing of the average rotational barrier in comparison to the bulk state. We have roughly separated the distribution for the confined state in a bul...

  10. Barriers for realisation of energy savings in buildings; Barrierer for realisering af energibesparelser i bygninger

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, O.M.

    2004-07-01

    Many years' efforts within the energy labelling area have shown large saving potentials in heating and use of electricity in buildings. At the same time it has been proved that these saving potentials, even when economically advantageous, only are cashed to a limited extent. The reason to this is ascribed to barriers that meet the individual building owner who wants to start saving energy. Most barriers are known and a lot of these have been sought overcome for some time. The questions are how many barriers still exist, have new barriers arisen and the character of these barriers. On this background the objective of this survey has been to concretize and study the barriers, which are blocking reasonable energy savings. Focus has especially been on barriers for realisation of heating savings, but through a general evaluation of energy savings of barriers other forms of energy saving methods have been taken into consideration. Special interest has been directed towards houses, typically one family houses, which are affected by the Energy Labelling Scheme. The concept barriers include all kinds of barriers, also barriers that not are acknowledged as barriers by the individual house owner, or that on closer inspection turn out to be something else than actual barriers. This note suggests an alternative inertia model, in order to create an idea of the inertness characteristic of the many house owners who understand the message but fail to act on it. (BA)

  11. Barriers Approach to Innovation in Academic Libraries

    Directory of Open Access Journals (Sweden)

    Fu-Hsuan Chuang

    2016-11-01

    Full Text Available Innovation in academic libraries is not a brand new issue. Academic libraries can benefit from successful innovation, since innovation is a key contributor to gaining and sustaining competitive advantage for survival. Building on two case studies, 28 participants from leadership teams to practitioners are involved, the qualitative findings identified the specific two types of barriers that academic libraries face by applying a barriers approach to innovation, that’s, environmental and organizational barriers. Especially, seven dimensions of two types of barriers to innovation are found.

  12. Water and contaminant movement: migration barriers

    International Nuclear Information System (INIS)

    Lane, L.J.; Nyhan, J.W.

    1984-11-01

    Migration barriers are used in shallow land burial facilities to slow or stop the movement of water and contaminants and are discussed here as a single component embedded in a complex environmental system. Analytical solutions to solute transport equations are used to approximate the behavior of migration barriers and to derive design criteria for control of subsurface water and contaminant migration. Various types of migration barriers are compared and design recommendations are made for shallow land burial trench caps and liners. Needed improvements and suggested field experiments for future designs of migration barriers are then discussed relative to the management of low-level radioactive wastes

  13. Lattice QCD without topology barriers

    CERN Document Server

    Lüscher, Martin

    2011-01-01

    As the continuum limit is approached, lattice QCD simulations tend to get trapped in the topological charge sectors of field space and may consequently give biased results in practice. We propose to bypass this problem by imposing open (Neumann) boundary conditions on the gauge field in the time direction. The topological charge can then flow in and out of the lattice, while many properties of the theory (the hadron spectrum, for example) are not affected. Extensive simulations of the SU(3) gauge theory, using the HMC and the closely related SMD algorithm, confirm the absence of topology barriers if these boundary conditions are chosen. Moreover, the calculated autocorrelation times are found to scale approximately like the square of the inverse lattice spacing, thus supporting the conjecture that the HMC algorithm is in the universality class of the Langevin equation.

  14. Controlling the quantum rotational dynamics of a driven planar rotor ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 129; Issue 7. Controlling the quantum rotational dynamics of a ... Weestablish that constructing such barriers, equivalent to additional weak fields, can efficiently suppress the chaos leading to the control of various processes. The phase space barriers are shown to be ...

  15. Response of wave-dominated and mixed-energy barriers to storms

    NARCIS (Netherlands)

    Masselink, G.; Heteren, S. van

    2014-01-01

    Wave-dominated and mixed-energy barriers are extremely dynamic landforms, responding to processes operating over a spectrum of time scales, ranging from daily-to-monthly fluctuations related to storm and post-storm conditions, to century-to-millennium-scale evolution driven by relative sea-level

  16. Assessing pre- and post-zygotic barriers between North Atlantic eels (Anguilla anguilla and A. rostrata)

    DEFF Research Database (Denmark)

    Jacobsen, M. W.; Smedegaard, L.; Sørensen, Sune Riis

    2017-01-01

    Elucidating barriers to gene flow is important for understanding the dynamics of speciation. Here we investigate pre- and post-zygotic mechanisms acting between the two hybridizing species of Atlantic eels: Anguilla anguilla and A. rostrata. Temporally varying hybridization was examined by analyz...... in natural hybrids.Heredity advance online publication, 9 November 2016; doi:10.1038/hdy.2016.96....

  17. Barriers of implementation of environmental management accounting in business practice

    Directory of Open Access Journals (Sweden)

    Petra Mísařová

    2010-01-01

    Full Text Available Environmental management accounting is a very important source of information for decision-making management of the company. In many companies there were created a detailed and dynamic system of recording and processing of data on environmental costs that companies mistakenly issued for environmental management accounting. And also today for environmental accounting in the CR it is characteristic that in organizations is not normal monitoring of the environmental costs con­si­de­red as part of an integrated system for monitoring and evaluation of material, energy and financial flows. Companies do not use a wide range of options that the environmental management accounting provides. Why do not companies introduce environmental management accounting into its information system and do not use all the opportunities that EMA provides? In practice there are many barriers that prevent full-fledged process of implementation of environmental management accounting in the information system of companies. Many barriers were identified and were therefore subjected to cluster analysis. Clusters filled by identified barriers under the rules of cluster analysis are the result of cluster analysis.

  18. Permeability Barrier Generation in the Martian Lithosphere

    Science.gov (United States)

    Schools, Joe; Montési, Laurent

    2015-11-01

    Permeability barriers develop when a magma produced in the interior of a planet rises into the cooler lithosphere and crystallizes more rapidly than the lithosphere can deform (Sparks and Parmentier, 1991). Crystallization products may then clog the porous network in which melt is propagating, reducing the permeability to almost zero, i.e., forming a permeability barrier. Subsequent melts cannot cross the barrier. Permeability barriers have been useful to explain variations in crustal thickness at mid-ocean ridges on Earth (Magde et al., 1997; Hebert and Montési, 2011; Montési et al., 2011). We explore here under what conditions permeability barriers may form on Mars.We use the MELTS thermodynamic calculator (Ghiorso and Sack, 1995; Ghiorso et al., 2002; Asimow et al., 2004) in conjunction with estimated Martian mantle compositions (Morgan and Anders, 1979; Wänke and Dreibus, 1994; Lodders and Fegley, 1997; Sanloup et al., 1999; Taylor 2013) to model the formation of permeability barriers in the lithosphere of Mars. In order to represent potential past and present conditions of Mars, we vary the lithospheric thickness, mantle potential temperature (heat flux), oxygen fugacity, and water content.Our results show that permeability layers can develop in the thermal boundary layer of the simulated Martian lithosphere if the mantle potential temperature is higher than ~1500°C. The various Martian mantle compositions yield barriers in the same locations, under matching variable conditions. There is no significant difference in barrier location over the range of accepted Martian oxygen fugacity values. Water content is the most significant influence on barrier development as it reduces the temperature of crystallization, allowing melt to rise further into the lithosphere. Our lower temperature and thicker lithosphere model runs, which are likely the most similar to modern Mars, show no permeability barrier generation. Losing the possibility of having a permeability

  19. Role of tunnelling in complete and incomplete fusion induced by 9Be on 169Tm and 187Re targets at around barrier energies

    Science.gov (United States)

    Kharab, Rajesh; Chahal, Rajiv; Kumar, Rajiv

    2017-04-01

    We have analyzed the complete and incomplete fusion excitation function for 9Be +169Tm, 187Re reactions at around barrier energies using the code PLATYPUS based on classical dynamical model. The quantum mechanical tunnelling correction is incorporated at near and sub barrier energies which significantly improves the matching between the data and prediction.

  20. Opportunities and barriers for international bioenergy trade

    NARCIS (Netherlands)

    Junginger, H.M.|info:eu-repo/dai/nl/202130703; van Dam, J.M.C.; Zarrilli, S.; Mohamed, F.A.; Marchal, D.; Faaij, A.P.C.|info:eu-repo/dai/nl/10685903X

    2011-01-01

    Recently, the international trade of various bioenergy commodities has grown rapidly, yet this growth is also hampered by some barriers. The aim of this paper is to obtain an overview of what market actors currently perceive as major opportunities and barriers for the development of international

  1. Israel's Security Barrier: Effects On Operational Factors

    National Research Council Canada - National Science Library

    2004-01-01

    .... The route of the barrier is tinder intense discussion at this time and if implemented as planned by the Sharon government will negatively affect the factors of space and force. The barrier must be constructed along the correct route in order to maximize operational factors.

  2. Precast concrete barrier crash testing : final report.

    Science.gov (United States)

    2001-12-01

    The objectives of this project were to crash test the Oregon Standard (32-inch) F-shape precast concrete barrier and the Oregon Tall (42-inch) F-shape precast concrete barrier against the new NCHRP Report 350 standards, to ensure compliance of these ...

  3. Barriers to adherence in cystic fibrosis

    DEFF Research Database (Denmark)

    Bregnballe, Vibeke; Schiøtz, Peter Oluf

    2012-01-01

    Danish patients with cystic fibrosis aged 14 to 25 years and their parents. Conclusions: The present study showed that the majority of adolescents with CF and their parents experienced barriers to treatment adherence. Patients and parents agreed that the three most common barriers encountered lack...

  4. K-Basin isolation barrier seal

    International Nuclear Information System (INIS)

    Ruff, E.S.

    1994-10-01

    This report documents various aspects of the design, analysis, procurement, and fabrication of the hydraulic seal on the isolation barriers to be installed in the 100-K Area spent nuclear fuel basin. The isolation barrier is used to keep water in the basin in the event of an earthquake

  5. Origin of methyl torsional potential barrier

    Indian Academy of Sciences (India)

    Inadequacy of one dimensional description of internal rotation has been highlighted in small methyl conjugated molecules in the light of its multidimensional nature. The effect of skeletal flexing on the picture of barrier formation by dissecting the barrier energy into potential type, virial type and symmetry type is described.

  6. Validation of the Performance of Engineered Barriers

    International Nuclear Information System (INIS)

    Choi, Jongwon; Cho, Wonjin; Kwon, Sangki

    2012-04-01

    To study the thermal-hydro-mechanical (THM) and thermal-hydro-mechanical-chemical (THMC) behavior of engineered barrier system (EBS), the engineering scale experiments, KENTEX and KENTEX-C were conducted to investigate THM and THMC behavior in the buffer. The computer modelling and simulation programmes were developed to analyze the distribution of temperature, water content, total pressure and the measured data on the migration behavior of anion and cation. In-situ heater test were performed to investigate the effect of the ventilation, thermal characteristics of EDZ, and effect of the anisotropy of rock mass and joint in addition to the investigation of the thermo-mechanical behavior in rock mass. The geophysics exploration and in-situ field tests were carried out to investigate the range of EDZ and its effects on the mechanical properties of rock. Subsequently, crack propagation characteristics and dynamic material properties of jointed rock mass in KURT were measured. Concurrently, the in-situ experiments were performed in the KURT to investigate the change of hydraulic properties in EDZ. The stainless steel molds are manufactured to fabricate the buffer blocks with various shapes. The experiments are carried out to check the mechanical properties, the workability for installation of the fabricated blocks and to investigate the resaturation processes. The state of the technology on application of cementitious materials to the HLW repository was analysed and the optimized low-pH cement recipe was obtained. And the material properties of low-pH and high-pH cement grouts were evaluated based on the grout recipes of ONKALO in Finland. The KURT was operated, and the various technical supports were provided to the in-situ experiments which were carried at KURT

  7. Barriers to physical activity among working mothers.

    Science.gov (United States)

    Dombrowski, Jill J

    2011-04-01

    Working mothers experience several barriers to physical activity. If these barriers can be identified by occupational health nurses and they can partner with working mothers to reduce these perceived barriers, the health of these workers can be improved and chronic disease risk prevented. The purpose of this study was to measure the effect of self-regulatory efficacy on physical activity among working mothers and to describe specific barriers to physical activity. The Barriers Specific Self-Efficacy Scale (BARSE) and the Kaiser Physical Activity Survey (KPAS) were used to measure the variables. Self-regulatory efficacy was found to be a strong predictor of physical activity in a diverse sample of working mothers who did not meet current recommendations for physical activity. Occupational health nurses can use these findings to design programs for groups and for counseling individuals. Copyright 2011, SLACK Incorporated.

  8. Barrier bucket experiment at the AGS

    Directory of Open Access Journals (Sweden)

    M. Fujieda

    1999-12-01

    Full Text Available A barrier bucket experiment with two dedicated barrier cavities was performed at the Brookhaven AGS. One of the barrier cavities was a magnetic alloy (MA–loaded cavity and the other was a ferrite-loaded cavity. They generated a single sine wave with a peak voltage of 40 kV at a repetition rate of 351 kHz. A barrier rf system was established with these cavities and five bunches from the AGS booster were accumulated. A total of 3×10^{13} protons were stored without beam loss, and were successfully rebunched and accelerated. The longitudinal emittance growth was observed during accumulation by the barrier bucket, the blowup factor of which was about 3. The longitudinal mismatch between the rf bucket and the beam bunch was the main reason for the emittance growth. The potential distortions by beam loading of the ferrite cavity and the overshooting voltage of the MA cavity disturbed the smooth debunching.

  9. Testing the barriers to healthy eating scale.

    Science.gov (United States)

    Fowles, Eileen R; Feucht, Jeanette

    2004-06-01

    Clarifying barriers to dietary intake may identify factors that place pregnant women at risk for complications. This methodological study assessed the psychometric properties of the Barriers to Healthy Eating Scale. Item generation was based on constructs in Pender's health promotion model. The instrument was tested in two separate samples of pregnant women. Content validity was assessed, and construct validity testing resulted in an expected negative relationship between scores on the Barriers to Healthy Eating Scale and the Nutrition subscale of the Health Promoting Lifestyle Profile-II. Factor analysis resulted in a 5-factor scale that explained 73% of the variance. Alpha coefficients for the total scale ranged from.73 to.77, and subscales ranged from.48 to.99. Test-retest reliability for the total scale was.79. The Barriers to Healthy Eating Scale appears to be a reliable and valid instrument to assess barriers that may impede healthy eating in pregnant women.

  10. Barriers in the energy of deformed nuclei

    Directory of Open Access Journals (Sweden)

    V. Yu. Denisov

    2014-06-01

    Full Text Available Interaction energy between two nuclei considering to their deformations is studied. Coulomb and nuclear in-teraction energies, as well as the deformation energies of both nuclei, are taken into account at evaluation of the interaction energy. It is shown that the barrier related to the interaction energy of two nuclei depends on the de-formations and the height of the minimal barrier is evaluated. It is obtained that the heavier nucleus-nucleus sys-tems have large deformation values at the lowest barrier. The difference between the barrier between spherical nuclei and the lowest barrier between deformed nuclei increases with the mass and the charge of the interacting nuclei.

  11. Modeling and Simulation of Long-Term Performance of Near-Surface Barriers

    International Nuclear Information System (INIS)

    Piet, S. J.; Jacobson, J. J.; Martian, P.; Martineau, R.; Soto, R.

    2003-01-01

    Society has and will continue to generate hazardous wastes whose risks must be managed. For exceptionally toxic, long-lived, and feared waste, the solution is deep burial, e.g., deep geological disposal at Yucca Mtn. For some waste, recycle or destruction/treatment is possible. The alternative for other wastes is storage at or near the ground level (in someone's back yard); most of these storage sites include a surface barrier (cap) to prevent migration of the waste due to infiltration of surface water. The design lifespan for such barriers ranges from 30 to 1000 years, depending on hazard and regulations. In light of historical performance, society needs a better basis for predicting barrier performance over long time periods and tools for optimizing maintenance of barriers while in service. We believe that, as in other industries, better understanding of the dynamics of barrier system degradation will enable improved barriers (cheaper, longer-lived, simpler, easier to maintain) and improved maintenance. We are focusing our research on earthen caps, especially those with evapo-transpiration and capillary breaks. Typical cap assessments treat the barrier's structure as static prior to some defined lifetime. Environmental boundary conditions such as precipitation and temperature are treated as time dependent. However, other key elements of the barrier system are regarded as constant, including engineered inputs (e.g., fire management strategy, irrigation, vegetation control), surface ecology (critical to assessment of plant transpiration), capillary break interface, material properties, surface erosion rate, etc. Further, to be conservative, only harmful processes are typically considered. A more holistic examination of both harmful and beneficial processes will provide more realistic pre-service prediction and in-service assessment of performance as well as provide designers a tool to encourage beneficial processes while discouraging harmful processes. Thus, the

  12. Modeling and Simulation of Long-Term Performance of Near-Surface Barriers

    Energy Technology Data Exchange (ETDEWEB)

    Piet, S. J.; Jacobson, J. J.; Martian, P.; Martineau, R.; Soto, R.

    2003-02-25

    Society has and will continue to generate hazardous wastes whose risks must be managed. For exceptionally toxic, long-lived, and feared waste, the solution is deep burial, e.g., deep geological disposal at Yucca Mtn. For some waste, recycle or destruction/treatment is possible. The alternative for other wastes is storage at or near the ground level (in someone's back yard); most of these storage sites include a surface barrier (cap) to prevent migration of the waste due to infiltration of surface water. The design lifespan for such barriers ranges from 30 to 1000 years, depending on hazard and regulations. In light of historical performance, society needs a better basis for predicting barrier performance over long time periods and tools for optimizing maintenance of barriers while in service. We believe that, as in other industries, better understanding of the dynamics of barrier system degradation will enable improved barriers (cheaper, longer-lived, simpler, easier to maintain) and improved maintenance. We are focusing our research on earthen caps, especially those with evapo-transpiration and capillary breaks. Typical cap assessments treat the barrier's structure as static prior to some defined lifetime. Environmental boundary conditions such as precipitation and temperature are treated as time dependent. However, other key elements of the barrier system are regarded as constant, including engineered inputs (e.g., fire management strategy, irrigation, vegetation control), surface ecology (critical to assessment of plant transpiration), capillary break interface, material properties, surface erosion rate, etc. Further, to be conservative, only harmful processes are typically considered. A more holistic examination of both harmful and beneficial processes will provide more realistic pre-service prediction and in-service assessment of performance as well as provide designers a tool to encourage beneficial processes while discouraging harmful processes

  13. Resonant transitions between split energy levels triple-barrier nanostructures and their application perspectives in submillimeter-wave devices

    CERN Document Server

    Golant, E I

    2002-01-01

    A mathematical model has been developed for electronic coherent tunneling through the triple-barrier quantum-dimensional semiconductor heterostructures in the terahertz electric field. Using this model the frequency dependences of the negative dynamic conductivity for triple-barrier structures with coherent electron tunneling through the split energy levels are investigated. It has been shown that these structures can be employed in far-infrared coherent quantum lasers, the wave length being 600 mu m (5 THz)

  14. Shakeoff Ionization near the Coulomb Barrier Energy

    Science.gov (United States)

    Sharma, Prashant; Nandi, T.

    2017-11-01

    We measure the projectile K x-ray spectra as a function of the beam energies around the Coulomb barrier in different collision systems. The energy is scanned in small steps around the barrier aiming to explore the nuclear effects on the elastically scattered projectile ions. The variation of the projectile x-ray energy with the ion-beam energies exhibits an unusual increase in between the interaction barrier and fusion barrier energies. This additional contribution to the projectile ionization can be attributed to the shakeoff of outer-shell electrons of the projectile ions due to the sudden nuclear recoil (˜10-21 sec ) caused by the attractive nuclear potential, which gets switched on near the interaction barrier energy. In the sudden approximation limit, the theoretical shakeoff probability calculation due to the nuclear recoil explains the observed data well. In addition to its fundamental interest, such processes can play a significant role in dark matter detection through the possible mechanism of x-ray emissions, where the weakly interacting massive particle-nucleus elastic scattering can lead to the nuclear-recoil-induced inner-shell vacancy creations. Furthermore, the present work may provide new prospects for atomic physics research at barrier energies as well as provide a novel technique to perform barrier distribution studies for two-body systems.

  15. Overcoming natural replication barriers: differential helicase requirements.

    Science.gov (United States)

    Anand, Ranjith P; Shah, Kartik A; Niu, Hengyao; Sung, Patrick; Mirkin, Sergei M; Freudenreich, Catherine H

    2012-02-01

    DNA sequences that form secondary structures or bind protein complexes are known barriers to replication and potential inducers of genome instability. In order to determine which helicases facilitate DNA replication across these barriers, we analyzed fork progression through them in wild-type and mutant yeast cells, using 2-dimensional gel-electrophoretic analysis of the replication intermediates. We show that the Srs2 protein facilitates replication of hairpin-forming CGG/CCG repeats and prevents chromosome fragility at the repeat, whereas it does not affect replication of G-quadruplex forming sequences or a protein-bound repeat. Srs2 helicase activity is required for hairpin unwinding and fork progression. Also, the PCNA binding domain of Srs2 is required for its in vivo role of replication through hairpins. In contrast, the absence of Sgs1 or Pif1 helicases did not inhibit replication through structural barriers, though Pif1 did facilitate replication of a telomeric protein barrier. Interestingly, replication through a protein barrier but not a DNA structure barrier was modulated by nucleotide pool levels, illuminating a different mechanism by which cells can regulate fork progression through protein-mediated stall sites. Our analyses reveal fundamental differences in the replication of DNA structural versus protein barriers, with Srs2 helicase activity exclusively required for fork progression through hairpin structures.

  16. 200-BP-1 Prototype Hanford Barrier -- 15 Years of Performance Monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Ward, Anderson L.; Draper, Kathryn E.; Link, Steven O.; Clayton, Ray E.

    2011-09-30

    Monitoring is an essential component of engineered barrier system design and operation. A composite capacitive cover, including a capillary break and an evapotranspiration (ET) barrier at the Hanford Site, is generating data that can be used to help resolve these issues. The prototype Hanford barrier was constructed over the 216-B-57 Crib in 1994 to evaluate surface-barrier constructability, construction costs, and physical and hydrologic performance at the field scale. The barrier has been routinely monitored between November 1994 and September 1998 as part of a Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) treatability test of barrier performance for the 200 BP 1 Operable Unit. Since FY 1998, monitoring has focused on a more limited set of key water balance, stability, and biotic parameters. In FY 2009, data collection was focused on: (1) water-balance monitoring, consisting of precipitation, runoff, soil moisture storage, and drainage measurements with evapotranspiration calculated by difference; (2) stability monitoring, consisting of asphalt-layer-settlement, basalt-side-slope-stability, and surface-elevation measurements; (3) vegetation dynamics; and (4) animal use. September 2009 marked 15 years since the start of monitoring and the collection of performance data. This report describes the results of monitoring activities during the period October 1, 2008, through September 30, 2009, and summarizes the 15 years of performance data collected from September 1994 through September 2009.

  17. Permanent isolation surface barrier development plan

    Energy Technology Data Exchange (ETDEWEB)

    Wing, N.R.

    1994-01-01

    The exhumation and treatment of wastes may not always be the preferred alternative in the remediation of a waste site. In-place disposal alternatives, under certain circumstances, may be the most desirable alternatives to use in the protection of human health and the environment. The implementation of an in-place disposal alternative will likely require some type of protective covering that will provide long-term isolation of the wastes from the accessible environment. Even if the wastes are exhumed and treated, a long-term barrier may still be needed to adequately dispose of the treated wastes or any remaining waste residuals. Currently, no {open_quotes}proven{close_quotes} long-term barrier is available. The Hanford Site Permanent Isolation Surface Barrier Development Program (BDP) was organized to develop the technology needed to provide a long-term surface barrier capability for the Hanford Site. The permanent isolation barrier technology also could be used at other sites. Permanent isolation barriers use engineered layers of natural materials to create an integrated structure with redundant protective features. Drawings of conceptual permanent isolation surface barriers are shown. The natural construction materials (e.g., fine soil, sand, gravel, riprap, asphalt) have been selected to optimize barrier performance and longevity. The objective of current designs is to use natural materials to develop a maintenance-free permanent isolation surface barrier that isolates wastes for a minimum of 1,000 years by limiting water drainage to near-zero amounts; reducing the likelihood of plant, animal, and human intrusion; controlling the exhalation of noxious gases; and minimizing erosion-related problems.

  18. Antimicrobial Peptides, Infections and the Skin Barrier

    DEFF Research Database (Denmark)

    Clausen, Maja Lisa; Agner, Tove

    2016-01-01

    immune responses. AMPs play an essential part in maintaining an optimal and functional skin barrier - not only by direct killing of pathogens, but also by balancing immune responses and interfering in wound healing, cell differentiation, reepithelialization and their synergistic interplay with the skin......The skin serves as a strong barrier protecting us from invading pathogens and harmful organisms. An important part of this barrier comes from antimicrobial peptides (AMPs), which are small peptides expressed abundantly in the skin. AMPs are produced in the deeper layers of the epidermis...

  19. Stochastic optimization algorithms for barrier dividend strategies

    Science.gov (United States)

    Yin, G.; Song, Q. S.; Yang, H.

    2009-01-01

    This work focuses on finding optimal barrier policy for an insurance risk model when the dividends are paid to the share holders according to a barrier strategy. A new approach based on stochastic optimization methods is developed. Compared with the existing results in the literature, more general surplus processes are considered. Precise models of the surplus need not be known; only noise-corrupted observations of the dividends are used. Using barrier-type strategies, a class of stochastic optimization algorithms are developed. Convergence of the algorithm is analyzed; rate of convergence is also provided. Numerical results are reported to demonstrate the performance of the algorithm.

  20. Ion-sound emission by Langmuir soliton reflected at density barrier

    International Nuclear Information System (INIS)

    El-Ashry, M.Y.

    1989-07-01

    The emission of ion-sound waves by an accelerated Langmuir soliton is studied. The acceleration of the soliton is due to an inhomogeneous density barrier. On the assumption that the kinetic energy of the Langmuir soliton is smaller than the potential energy created by the barrier. The basic equations describing the dynamic behaviour of the soliton and the emission of the ion-sound waves are formulated. The qualitative spatial distributions of the perturbed concentration in the ion-sound waves are analyzed at different characteristic points of the soliton. The energy lost by the soliton, as a result of the emission, is estimated. (author). 6 refs, 4 figs

  1. Barriers to Adult Learning: Does Anticipation Match Reality?

    Science.gov (United States)

    Richter, Donna L.; Witten, Charles H.

    1984-01-01

    Examined barriers to learning in adult students (N=111) using the Adult Student Survey. Results indicated that in many cases students were able to predict barriers before enrolling. Lack of time was the most difficult barrier to anticipate correctly. (JAC)

  2. Modeling and Simulation of Long-Term Performance of Near-Surface Barriers

    Energy Technology Data Exchange (ETDEWEB)

    Piet, Steven James; Jacobson, Jacob Jordan; Soto, Rafael; Martian, Pete; Martineau, Richard Charles

    2003-02-01

    Society has and will continue to generate hazardous wastes whose risks must be managed. For exceptionally toxic, long-lived, and feared waste, the solution is deep burial, e.g., deep geological disposal at Yucca Mtn. For some waste, recycle or destruction/treatment is possible. The alternative for other wastes is storage at or near the ground level (in someone’s back yard); most of these storage sites include a surface barrier (cap) to prevent migration of the waste due to infiltration of surface water. The design lifespan for such barriers ranges from 30 to 1000 years, depending on hazard and regulations. In light of historical performance, society needs a better basis for predicting barrier performance over long time periods and tools for optimizing maintenance of barriers while in service. We believe that, as in other industries, better understanding of the dynamics of barrier system degradation will enable improved barriers (cheaper, longer-lived, simpler, easier to maintain) and improved maintenance. We are focusing our research on earthen caps, especially those with evapo-transpiration and capillary breaks. Typical cap assessments treat the barrier’s structure as static prior to some defined lifetime. Environmental boundary conditions such as precipitation and temperature are treated as time dependent. However, other key elements of the barrier system are regarded as constant, including engineered inputs (e.g., fire management strategy, irrigation, vegetation control), surface ecology (critical to assessment of plant transpiration), capillary break interface, material properties, surface erosion rate, etc. Further, to be conservative, only harmful processes are typically considered. A more holistic examination of both harmful and beneficial processes will provide more realistic pre-service prediction and in-service assessment of performance as well as provide designers a tool to encourage beneficial processes while discouraging harmful processes. Thus

  3. Market and Policy Barriers to Energy Storage Deployment

    Energy Technology Data Exchange (ETDEWEB)

    Bhatnagar, Dhruv [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Currier, Aileen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hernandez, Jacquelynne [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ma, Ookie [Dept. of Energy (DOE), Washington DC (United States) Office of Energy Efficiency and Renewable Energy; Kirby, Brendan [Consultant

    2013-09-01

    Electric energy storage technologies can provide numerous grid services; there are a number of factors that restrict their current deployment. The most significant barrier to deployment is high capital costs, though several recent deployments indicate that capital costs are decreasing and energy storage may be the preferred economic alternative in certain situations. However, a number of other market and regulatory barriers persist, limiting further deployment. These barriers can be categorized into regulatory barriers, market (economic) barriers, utility and developer business model barriers, cross-cutting barriers and technology barriers.

  4. Message maps for safety barrier awareness

    DEFF Research Database (Denmark)

    Jørgensen, Kirsten; Duijm, Nijs Jan; Troen, Hanne

    2011-01-01

    of requirements for people, work conditions, management, learning, knowledge, experience, motivation etc. The Dutch WORM and RAM projects led to the identification of 64 types of risks and the safety barriers and performance factors linked to these risks. The Danish DanWORM project has transferred this knowledge......All people are exposed to risks in everyday life, but they seldom experience accidents. Therefore, people often believe that these accidents will never happen, and they do not see the risks. By increasing the ability to notice risks, to see safety barriers, and to assess the safety barriers......’ performance parameters continuously, it is possible to create better risk awareness on the part of employers, managers and employees. Better risk awareness by these stakeholders will make it possible to: • acknowledge and continuously control risks; • discover and manage new risks; • keep safety barriers...

  5. Message maps for Safety Barrier Awareness

    DEFF Research Database (Denmark)

    . This Situational Awareness puts a number of requirements on people, work conditions, management, learning, knowledge, experience, motivation, etc. The Dutch WORM and RAM projects led to the identification of 64 types of risks and the safety barriers and performance factors that are linked to these risks......All people are exposed to risks in every-day life, but they seldom experience accidents. Therefore people often believe that these accidents will never happen, and they will see the risks no more. By increasing the ability to notice risks, to see safety barriers, and to assess the safety barriers......’ performance parameters continuously, it is possible to create better risk awareness of employers, managers and employees. Better risk awareness of these stakeholders will make it possible that: • Risks are acknowledged and controlled continuously; • New risks are discovered and managed; • Safety barriers...

  6. Breast cancer screening barriers and disability.

    Science.gov (United States)

    Todd, Ana; Stuifbergen, Alexa

    2012-01-01

    There is evidence that early detection from breast cancer screening is an effective means to reduce overall mortality from breast cancer. Findings from multiple research studies suggest that women with chronic disabling conditions are less likely to participate in breast cancer screening due to the multiple barriers they face. Barriers include those related to finances, environment, physical limitations, health carers' attitudes and lack of knowledge, and psychosocial issues. The purpose of this article is to provide an overview of the existing evidence of the barriers to breast cancer screening experienced by women with physical disabilities. Rehabilitation nurses that work with women who have chronic disabling conditions can be instrumental in eliminating these barriers to breast cancer screening through their efforts to promote health which is consistent with the philosophy of maximizing the health potential and quality of life of these women whose needs are often overlooked. © 2012 Association of Rehabilitation Nurses.

  7. DOE UST interim subsurface barrier technologies workshop

    International Nuclear Information System (INIS)

    1992-09-01

    This document contains information which was presented at a workshop regarding interim subsurface barrier technologies that could be used for underground storage tanks, particularly the tank 241-C-106 at the Hanford Reservation

  8. [THE INTESTINAL BARRIER, THE MICROBIOTA, MICROBIOME].

    Science.gov (United States)

    Mar'yanovich, A T

    2016-01-01

    The review examined modern condition of development directions physiology of digestion, like structure and function of the intestinal barrier, the microbiota of the digestive tract in its relations with the microorganism.

  9. Evapotranspiration studies for protective barriers: Experimental plans

    International Nuclear Information System (INIS)

    Link, S.O.; Waugh, W.J.

    1989-11-01

    This document describes a general theory and experimental plans for predicting evapotranspiration in support of the Protective Barrier Program. Evapotranspiration is the combined loss of water from plants and soil surfaces to the atmosphere. 45 refs., 1 fig., 4 tabs

  10. Evapotranspiration studies for protective barriers: Experimental plans

    Energy Technology Data Exchange (ETDEWEB)

    Link, S.O.; Waugh, W.J.

    1989-11-01

    This document describes a general theory and experimental plans for predicting evapotranspiration in support of the Protective Barrier Program. Evapotranspiration is the combined loss of water from plants and soil surfaces to the atmosphere. 45 refs., 1 fig., 4 tabs.

  11. Overcoming Barriers to Shared Decision Making

    Science.gov (United States)

    ... Barrier: Cultural and religious differences Solution: Culture and religion can influence what care you choose to receive ... questions to ask your doctor about heart failure. Popular Articles 1 Understanding Blood Pressure Readings 2 Sodium ...

  12. Vapor-barrier Vacuum Isolation System

    Science.gov (United States)

    Weinstein, Leonard M. (Inventor); Taminger, Karen M. (Inventor)

    2014-01-01

    A system includes a collimated beam source within a vacuum chamber, a condensable barrier gas, cooling material, a pump, and isolation chambers cooled by the cooling material to condense the barrier gas. Pressure levels of each isolation chamber are substantially greater than in the vacuum chamber. Coaxially-aligned orifices connect a working chamber, the isolation chambers, and the vacuum chamber. The pump evacuates uncondensed barrier gas. The barrier gas blocks entry of atmospheric vapor from the working chamber into the isolation chambers, and undergoes supersonic flow expansion upon entering each isolation chamber. A method includes connecting the isolation chambers to the vacuum chamber, directing vapor to a boundary with the working chamber, and supersonically expanding the vapor as it enters the isolation chambers via the orifices. The vapor condenses in each isolation chamber using the cooling material, and uncondensed vapor is pumped out of the isolation chambers via the pump.

  13. ULTRA BARRIER TOPSHEET (UBT) FOR FLEXIBLE PHOTOVOLTAICS

    Energy Technology Data Exchange (ETDEWEB)

    DeScioli, Derek

    2013-06-01

    This slide-show presents 3M photovoltaic-related products, particularly flexible components. Emphasis is on the 3M Ultra Barrier Solar Films. Topics covered include reliability and qualification testing and flexible photovoltaic encapsulation costs.

  14. Low-impact, high toughness transportation barriers.

    Science.gov (United States)

    2012-10-01

    Alternatives to existing transportation truck escape ramps and crash barriers are examined using arrays of : wood, bamboo, and fiberglass structural elements that act as energy absorbers as they deform. The : behaviors of each material type are analy...

  15. Field Studies of the Electrical Properties of Permeable Reactive Barriers for Monitoring Barrier Aging

    Science.gov (United States)

    Sharpe, R.; Labrecque, D. J.; Slater, L.

    2006-12-01

    Permeable reactive barriers (PRB) are a promising technology for the remediation of groundwater containing a range of organic and inorganic contaminants. Although there are number of different types of reactive barriers, some of the most important are constructed from granular zero valent iron (ZVI). One challenge in the large- scale, long-term implementation of PRBs is to monitor the change in barrier properties over time. For example, mineral precipitates can reduce the effectiveness of the barrier by either insulating the reaction surfaces of the ZVI particles and/or by filling the pore space in the barrier and thus reducing its hydraulic permeability. Previous research has shown that resistivity and induced polarization (IP) measurements are sensitive to corrosion and precipitation due to redox reactions between ions in solution and the ZVI mineral surface. New field studies, supported by additional laboratory studies appear to confirm this work. Resisitivity and IP surveys were conducted at a total of seven barriers at four different sites: the Denver Federal Center; Monticello, Utah; the Kansas City, Missouri Department of Energy site, and the Asarco Smelter Site in East Helena, Montana. These surveys used combinations of surface and borehole surveys to characterized barriers. The surveys are repeated at approximately six-month intervals to provide information on temporal changes. In addition, surveys at the Kansas City barrier followed up on earlier research by providing several years of historical data and a new barrier at East Helena Montana has been instrumented with an autonomous monitoring system allowing continuous monitoring of the barrier electrical properties. Results show an increase in both real and imaginary conductivity as barriers age. For new barriers, the conductivity of ZVI is typically a few tens of mS/m, only modestly higher than that of the background sediments surrounding the barrier. For heavily altered barriers such as the Monticello

  16. Porosity determination of thermal barrier coatings

    Science.gov (United States)

    Van Roode, Mark; Beardsley, Brad

    1988-01-01

    Coating porosity is believed to be a critical factor for the thermal conductivity of thermal barrier coatings (TBCs). A number of different techniques have been used to determine the porosities of thermal barrier coatings for diesel applications as part of a NASA/DOE sponsored study. A comparison is made between methods based on water immersion, optical microscopy, eddy current thickness measurements, and Archimedes principle for TBC porosity determination.

  17. Breaching barriers to collaboration in public spaces

    DEFF Research Database (Denmark)

    Heinemann, Trine; Mitchell, Robb

    2014-01-01

    Technology provoking disparate individuals to collaborate or share experiences in the public space faces a difficult barrier, namely the ordinary social order of urban places. We employed the notion of the breaching experiment to explore how this barrier might be overcome. We analyse responses...... of life in public spaces. Arising from this, we argue for the importance of qualities such as availability, facilitation, perspicuous settings, and perspicuous participants to encourage and support co-located strangers to collaborate and share experiences....

  18. Structural Stability of Tokamak Equilibrium: Transport Barriers

    Energy Technology Data Exchange (ETDEWEB)

    Solano, E. R.

    2001-07-01

    A generalised theory of structural stability of differential equations is introduced and applied to the Grad-Shafranov equation. It is discussed how the formation and loss of transport barrier could be associated with the appearance/disappearance of equilibria. The equilibrium conjecture is presented: transport barriers are associated with locally diamagnetic regions in the plasma, and affected by the paramagnetism of the bootstrap current. (Author) 18 refs.

  19. Immigrant language barriers and house prices

    OpenAIRE

    Fischer, Andreas M.

    2011-01-01

    Are language skills important in explaining the nexus between house prices and immigrant inflows? The language barrier hypothesis says immigrants from a non common language country value amenities more than immigrants from common language countries.> ; In turn, immigrants from non common language countries are less price sensitive to house price changes than immigrants from a common language country. Tests of the language barrier hypothesis with Swiss house prices show that an immigration inf...

  20. Drywall construction as a dental radiation barrier.

    Science.gov (United States)

    MacDonald, J C; Reid, J A; Berthoty, D

    1983-03-01

    Six typical forms of drywall construction have been tested as barriers against primary and secondary dental x-radiation. It is concluded that this widely used type of wall construction is generally effective for this purpose, but with a heavy workload two thicknesses of wallboard on each side of the wall are required to provide a sufficient barrier. In general, no lead need be incorporated in the walls.

  1. Composite Pressure Vessel Including Crack Arresting Barrier

    Science.gov (United States)

    DeLay, Thomas K. (Inventor)

    2013-01-01

    A pressure vessel includes a ported fitting having an annular flange formed on an end thereof and a tank that envelopes the annular flange. A crack arresting barrier is bonded to and forming a lining of the tank within the outer surface thereof. The crack arresting barrier includes a cured resin having a post-curing ductility rating of at least approximately 60% through the cured resin, and further includes randomly-oriented fibers positioned in and throughout the cured resin.

  2. Barriers in EU retail financial markets

    OpenAIRE

    Micuda, Dan

    2007-01-01

    Looking at the retail financial markets and identifing a number of ‘‘natural’’ and ‘‘policy induced’’ obstacles to free trade. We use the term ‘‘natural’’ barriers to refer to those arising as a result of different cultures or consumer preferences, while different state tax policies or regulations are classified as ‘‘policy induced’’ barriers.

  3. 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)

  4. Addressing language barriers to healthcare in India.

    Science.gov (United States)

    Narayan, Lalit

    2013-01-01

    In spite of a growing recognition of the importance of doctor-patient communication, the issue of language barriers to healthcare has received very little attention in India. The Indian population speaks over 22 major languages with English used as the lingua franca for biomedicine. Large-scale internal migration has meant that health workers are encountering increasing instances of language discordance within clinical settings. Research done predominantly in the West has shown language discordance to significantly affect access to care, cause problems of comprehension and adherence, and decrease the satisfaction and quality of care. Addressing language barriers to healthcare in India requires a stronger political commitment to providing non-discriminatory health services, especially to vulnerable groups such as illiterate migrant workers. Research will have to address three broad areas: the ways in which language barriers affect health and healthcare, the efficacy of interventions to overcome language barriers, and the costs of language barriers and efforts to overcome them. There is a need to address such barriers in health worker education and clinical practice. Proven strategies such as hiring multilingual healthcare workers, providing language training to health providers, employing in situ translators or using telephone interpretation services will have to be evaluated for their appropriateness to the Indian context. Internet-based initiatives, the proliferation of mobile phones and recent advances in machine translation promise to contribute to the solution. Copyright 2013, NMJI.

  5. Field study plan for alternate barriers

    International Nuclear Information System (INIS)

    Freeman, H.D.; Gee, G.W.; Relyea, J.F.

    1989-05-01

    Pacific Northwest Laboratory (PNL) is providing technical assistance in selecting, designing, evaluating, and demonstrating protective barriers. As part of this technical assistance effort, asphalt, clay, and chemical grout will be evaluated for use as alternate barriers. The purpose of the subsurface layer is to reduce the likelihood that extreme events (i.e., 100-year maximum storms, etc.) will cause significant drainage through the barrier. The tests on alternate barriers will include laboratory and field analysis of the subsurface layer performance. This field test plan outlines the activities required to test and design subsurface moisture barriers. The test plan covers activities completed in FY 1988 and planned through FY 1992 and includes a field-scale test of one or more of the alternate barriers to demonstrate full-scale application techniques and to provide performance data on a larger scale. Tests on asphalt, clay, and chemical grout were initiated in FY 1988 in small (30.5 cm diameter) tube-layer lysimeters. The parameters used for testing the materials were different for each one. The tests had to take into account the differences in material characteristics and response to change in conditions, as well as information provided by previous studies. 33 refs., 8 figs., 1 tab

  6. Sports participation after rehabilitation: Barriers and facilitators.

    Science.gov (United States)

    Jaarsma, Eva A; Dekker, Rienk; Geertzen, Jan H B; Dijkstra, Pieter U

    2016-01-01

    To analyse barriers to, and facilitators of, sports participation among people with physical disabilities after rehabilitation and to compare differences between inactive and active participants regarding these experienced barriers and facilitators. Participants were 1,223 adults (mean age 51.6 years, standard deviation 15.1 years) treated in the Rehabilitation Centre of the University Medical Center Groningen, who completed a questionnaire. The questionnaire consisted of a self-constructed questionnaire regarding barriers and facilitators. Fifty-eight percent of the participants were active in sports after their rehabilitation. Younger age and a higher level of education were positively associated with sports participation, whereas using assistive devices and experiencing environmental barriers were negatively associated. Facilitators of sports participation were health, fun and increasing physical strength, and advice from rehabilitation professionals. Rehabilitation professionals should emphasize the health benefits of, and enjoyment from, sports participation for people with physical disabilities. They should repeatedly remind people with physical disabilities to stay/become active after completing their rehabilitation programme. Rehabilitation professionals should also provide information about strategies to reduce environmental barriers to sports participation, which could help people using assistive devices to overcome these barriers.

  7. Attitudinal barriers to participation in oncology clinical trials: factor analysis and correlates of barriers.

    Science.gov (United States)

    Manne, S; Kashy, D; Albrecht, T; Wong, Y-N; Lederman Flamm, A; Benson, A B; Miller, S M; Fleisher, Linda; Buzaglo, J; Roach, N; Katz, M; Ross, E; Collins, M; Poole, D; Raivitch, S; Miller, D M; Kinzy, T G; Liu, T; Meropol, N J

    2015-01-01

    Patient participation in cancer clinical trials is low. Little is known about attitudinal barriers to participation, particularly among patients who may be offered a trial during an imminent initial oncology consult. The aims of the present study were to confirm the presence of proposed subscales of a recently developed cancer clinical trial attitudinal barriers measure, describe the most common cancer clinical trials attitudinal barriers, and evaluate socio-demographic, medical and financial factors associated with attitudinal barriers. A total of 1256 patients completed a survey assessing demographic factors, perceived financial burden, prior trial participation and attitudinal barriers to clinical trials participation. Results of a factor analysis did not confirm the presence of the proposed four attitudinal barriers subscale/factors. Rather, a single factor represented the best fit to the data. The most highly-rated barriers were fear of side-effects, worry about health insurance and efficacy concerns. Results suggested that less educated patients, patients with non-metastatic disease, patients with no previous oncology clinical trial participation, and patients reporting greater perceived financial burden from cancer care were associated with higher barriers. These patients may need extra attention in terms of decisional support. Overall, patients with fewer personal resources (education, financial issues) report more attitudinal barriers and should be targeted for additional decisional support. © 2014 John Wiley & Sons Ltd.

  8. Delay time in a single barrier for a movable quantum shutter

    International Nuclear Information System (INIS)

    Hernandez, Alberto

    2010-01-01

    The transient solution and delay time for a δ potential scatterer with a movable quantum shutter is calculated by solving analytically the time-dependent Schroedinger equation. The delay time is analyzed as a function of the distance between the shutter and the potential barrier and also as a function of the distance between the potential barrier and the detector. In both cases, it is found that the delay time exhibits a dynamical behavior and that it tends to a saturation value Δt sat in the limit of very short distances, which represents the maximum delay produced by the potential barrier near the interaction region. The phase time τ θ , on the other hand, is not an appropriate time scale for measuring the time delay near the interaction region, except if the shutter is moved far away from the potential. The role played by the antibound state of the system on the behavior of the delay time is also discussed.

  9. Increased brainstem perfusion, but no blood-brain barrier disruption, during attacks of migraine with aura

    DEFF Research Database (Denmark)

    Hougaard, Anders; Amin, Faisal M; Christensen, Casper E

    2017-01-01

    symptoms are related to the headache phase of migraine. Animal studies suggest that cortical spreading depression, the likely mechanism of migraine aura, causes disruption of the blood-brain barrier and noxious stimulation of trigeminal afferents leading to activation of brainstem nuclei and triggering...... of migraine headache. We used the sensitive and validated technique of dynamic contrast-enhanced high-field magnetic resonance imaging to simultaneously investigate blood-brain barrier permeability and tissue perfusion in the brainstem (at the level of the lower pons), visual cortex, and brain areas......-free day. The mean time from attack onset to scanning was 7.6 h. We found increased brainstem perfusion bilaterally during migraine with aura attacks. Perfusion also increased in the visual cortex and posterior white matter following migraine aura. We found no increase in blood-brain barrier permeability...

  10. Trade Barriers and Countermeasures for Export of China’s Agricultural Products

    OpenAIRE

    WU, Lijing

    2013-01-01

    At present, export of China’s agricultural products is faced with many trade barriers, especially technological barriers. Trade barriers include (1) technological barriers (such as quarantine and inspection barrier, identity certification/authentication barrier and labeling rules barrier); (2) trade remedy barrier; (3) other non-tariff barriers (NTB). Through positioning and analysis of trade barriers of China’s agricultural products, it is known that technological barriers should not be ...

  11. Debris flow impact on mitigation barriers: a new method for particle-fluid-structure interactions

    Science.gov (United States)

    Marchelli, Maddalena; Pirulli, Marina; Pudasaini, Shiva P.

    2016-04-01

    Channelized debris-flows are a type of mass movements that involve water-charged, predominantly coarse-grained inorganic and organic material flowing rapidly down steep confined pre-existing channels (Van Dine, 1985). Due to their rapid movements and destructive power, structural mitigation measures have become an integral part of counter measures against these phenomena, to mitigate and prevent damages resulting from debris-flow impact on urbanized areas. In particular, debris barriers and storage basins, with some form of debris-straining structures incorporated into the barrier constructed across the path of a debris-flow, have a dual role to play: (1) to stimulate deposition by presenting a physical obstruction against flow, and (2) to guarantee that during normal conditions stream water and bedload can pass through the structure; while, during and after an extreme event, the water that is in the flow and some of the fine-grained sediment can escape. A new method to investigate the dynamic interactions between the flowing mass and the debris barrier is presented, with particular emphasis on the effect of the barrier in controlling the water and sediment content of the escaping mass. This aspect is achieved by implementing a new mechanical model into an enhanced two-phase dynamical mass flow model (Pudasaini, 2012), in which solid particles mixture and viscous fluid are taken into account. The complex mechanical model is defined as a function of the energy lost during impact, the physical and geometrical properties of the debris barrier, separate but strongly interacting dynamics of boulder and fluid flows during the impact, particle concentration distribution, and the slope characteristics. The particle-filtering-process results in a large variation in the rheological properties of the fluid-dominated escaping mass, including the substantial reduction in the bulk density, and the inertial forces of the debris-flows. Consequently, the destructive power and run

  12. Overcoming barriers to Clean Development Mechanism projects

    Energy Technology Data Exchange (ETDEWEB)

    Ellis, J. [OECD, Paris (France); Kamel, S. [UNEP Risoe Centre on Energy, Climate and Sustainable Development URC, Roskilde (Denmark)

    2007-05-15

    The market for Clean Development Mechanism (CDM) projects is continuing to grow rapidly, with the current portfolio expecting to deliver 2 billion tons of CO2-eq greenhouse gas (GHG) emission reductions by 2012, equivalent to 17% of Annex I Parties' base year GHG emissions. In total, governments and companies have earmarked over USD11 billion for CDM funding to 2012. This study analyses the various barriers to CDM market expansion in developing countries, and makes recommendations on how some of them can be removed or reduced. It also examines the distribution of CDM projects amongst regions and sectors. Different types of barriers can impede the development of CDM projects. These include: National-level barriers not related specifically to the CDM such as the policy or legislative framework within which a CDM project operates, e.g. electricity-related regulations that constrain generation by independent power producers; National-level CDM-related barriers such as institutional capability/effectiveness or lack of awareness about CDM potential. For example, delays in host country approval of CDM projects can dampen interest in CDM project development; Project-related issues including availability (or not) of underlying project finance, or other country or project-related risks that render the performance of the project uncertain; International-level barriers such as constraints on project eligibility (e.g. on land use and forestry projects), available guidance and decisions (e.g. with respect to the inclusion of carbon capture and storage projects), etc. Thus, barriers to CDM development can arise at different parts of the CDM project cycle. The relative importance of particular barriers varies between countries as well as over time. A combination of factors is needed to drive growth in a country's CDM activity. This includes the presence of attractive CDM opportunities, a positive investment climate, and an enabling policy and legislative framework (in

  13. 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

  14. Computational Design and Experimental Validation of New Thermal Barrier Systems

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Shengmin; Yang, Shizhong; Khosravi, Ebrahim

    2011-12-31

    This project (10/01/2010-9/30/2013), “Computational Design and Experimental Validation of New Thermal Barrier Systems”, originates from Louisiana State University (LSU) Mechanical Engineering Department and Southern University (SU) Department of Computer Science. This proposal will directly support the technical goals specified in DE-FOA-0000248, Topic Area 3: Turbine Materials, by addressing key technologies needed to enable the development of advanced turbines and turbine-based systems that will operate safely and efficiently using coal-derived synthesis gases. We will develop novel molecular dynamics method to improve the efficiency of simulation on novel TBC materials; we will perform high performance computing (HPC) on complex TBC structures to screen the most promising TBC compositions; we will perform material characterizations and oxidation/corrosion tests; and we will demonstrate our new Thermal barrier coating (TBC) systems experimentally under Integrated gasification combined cycle (IGCC) environments. The durability of the coating will be examined using the proposed High Temperature/High Pressure Durability Test Rig under real syngas product compositions.

  15. 8B + 208Pb Elastic Scattering at Coulomb Barrier Energies

    Science.gov (United States)

    La Commara, M.; Mazzocco, M.; Boiano, A.; Boiano, C.; Manea, C.; Parascandolo, C.; Pierroutsakou, D.; Signorini, C.; Strano, E.; Torresi, D.; Yamaguchi, H.; Kahl, D.; Di Meo, P.; Grebosz, J.; Imai, N.; Hirayama, Y.; Ishiyama, H.; Iwasa, N.; Jeong, S. C.; Jia, H. M.; Kim, Y. H.; Kimura, S.; Kubono, S.; Lin, C. J.; Miyatake, H.; Mukai, M.; Nakao, T.; Nicoletto, M.; Sakaguchi, Y.; Sánchez-Benítez, A. M.; Soramel, F.; Teranishi, T.; Wakabayashi, Y.; Watanabe, Y. X.; Yang, L.; Yang, Y. Y.

    2018-02-01

    The scattering process of weakly-bound nuclei at Coulomb barrier energies provides deep insights on the reaction dynamics induced by exotic nuclei. Within this framework, we measured for the first time the scattering process of the short-lived Radioactive Ion Beam (RIB) 8B (Sp = 0.1375 MeV) from a 208Pb target at 50 MeV beam energy. The 8B RIB was produced by means of the in-flight facility CRIB (RIKEN, Japan) with an average intensity on target of 10 kHz and a purity about 25%. Elastically scattering ions were detected in the angular range θc.m. = 10°-160° by means of the detector array EXPADES. A preliminary optical model analysis indicates a total reaction cross section of about 1 b, a value, once reduced, 2-3 times larger than those obtained for the reactions induced by the stable weakly-bound projectiles 6,7Li on a 208Pb target in the energy range around the Coulomb barrier.

  16. Thermophysical and Thermomechanical Properties of Thermal Barrier Coating Systems

    Science.gov (United States)

    Zhu, Dongming; Miller, Robert A.

    2000-01-01

    Thermal barrier coatings have been developed for advanced gas turbine and diesel engine applications to improve engine reliability and fuel efficiency. However, the issue of coating durability under high temperature cyclic conditions is still of major concern. The coating failure is closely related to thermal stresses and oxidation in the coating systems. Coating shrinkage cracking resulting from ceramic sintering and creep at high temperatures can further accelerate the coating failure process. The purpose of this paper is to address critical issues such as ceramic sintering and creep, thermal fatigue and their relevance to coating life prediction. Novel test approaches have been established to obtain critical thermophysical and thermomechanical properties of the coating systems under near-realistic temperature and stress gradients encountered in advanced engine systems. Emphasis is placed on the dynamic changes of the coating thermal conductivity and elastic modulus, fatigue and creep interactions, and resulting failure mechanisms during the simulated engine tests. Detailed experimental and modeling results describing processes occurring in the thermal barrier coating systems provide a framework for developing strategies to manage ceramic coating architecture, microstructure and properties.

  17. A High-Powered View of the Filtration Barrier

    Science.gov (United States)

    Peti-Peterdi, János; Sipos, Arnold

    2015-01-01

    Multiphoton excitation fluorescence microscopy is a powerful noninvasive imaging technique for the deep optical sectioning of living tissues. Its application in several intact tissues is a significant advance in our understanding of organ function, including renal pathophysiological mechanisms. The glomerulus, the filtering unit in the kidney, is one good example of a relatively inaccessible and complex structure, with cell types that are otherwise difficult to study at high resolution in their native environment. In this article, we address the application, advantages, and limitations of this imaging technology for the study of the glomerular filtration barrier and the controversy it recently generated regarding the glomerular filtration of macromolecules. More advanced and accurate multiphoton determinations of the glomerular sieving coefficient that are presented here dismiss previous claims on the filtration of nephrotic levels of albumin. The sieving coefficient of 70-kD dextran was found to be around 0.001. Using a model of focal segmental glomerulosclerosis, increased filtration barrier permeability is restricted only to areas of podocyte damage, consistent with the generally accepted role of podocytes and the glomerular origin of albuminuria. Time-lapse imaging provides new details and important in vivo confirmation of the dynamics of podocyte movement, shedding, replacement, and the role of the parietal epithelial cells and Bowman's capsule in the pathology of glomerulosclerosis. PMID:20576805

  18. Semiclassical dynamics

    International Nuclear Information System (INIS)

    Balazs, N.L.

    1979-01-01

    It is pointed out that in semiclassical dynamics one is encouraged to study the evolution of those curves in phase space which classically represent ensembles corresponding to wave functions. It is shown that the fixed points generate new time scales so that for times longer than the critical times, quantum dynamics will profoundly differ from classical dynamics. (P.L.)

  19. Dynamical Languages

    Science.gov (United States)

    Xie, Huimin

    The following sections are included: * Definition of Dynamical Languages * Distinct Excluded Blocks * Definition and Properties * L and L″ in Chomsky Hierarchy * A Natural Equivalence Relation * Symbolic Flows * Symbolic Flows and Dynamical Languages * Subshifts of Finite Type * Sofic Systems * Graphs and Dynamical Languages * Graphs and Shannon-Graphs * Transitive Languages * Topological Entropy

  20. Probing cluster structures through sub-barrier transfer reactions

    Directory of Open Access Journals (Sweden)

    Rafferty D. C.

    2016-01-01

    Full Text Available Multinucleon transfer probabilities and excitation energy distributions have been measured in 16,18O, 19F + 208Pb at energies between 90% - 100% of the Coulomb barrier. A strong 2p2n enhancement is observed for all reactions, though most spectacularly in the 18O induced reaction. Results are interpreted in terms of the Semiclassical model, which seems to suggest α-cluster transfer in all studied systems. The relation to cluster-states in the projectile is discussed, with the experimental results consistent with previous structure studies. Dissipation of energy in the collisions of 18O is compared between different reaction modes, with cluster transfer associated with dissipation over a large number of internal states. Cluster transfer is shown to be a long range dissipation mechanism, which will inform the development of future models to treat these dynamic processes in reactions.

  1. Physical insights into the blood-brain barrier translocation mechanisms

    Science.gov (United States)

    Theodorakis, Panagiotis E.; Müller, Erich A.; Craster, Richard V.; Matar, Omar K.

    2017-08-01

    The number of individuals suffering from diseases of the central nervous system (CNS) is growing with an aging population. While candidate drugs for many of these diseases are available, most of these pharmaceutical agents cannot reach the brain rendering most of the drug therapies that target the CNS inefficient. The reason is the blood-brain barrier (BBB), a complex and dynamic interface that controls the influx and efflux of substances through a number of different translocation mechanisms. Here, we present these mechanisms providing, also, the necessary background related to the morphology and various characteristics of the BBB. Moreover, we discuss various numerical and simulation approaches used to study the BBB, and possible future directions based on multi-scale methods. We anticipate that this review will motivate multi-disciplinary research on the BBB aiming at the design of effective drug therapies.

  2. Visual selective attention with virtual barriers.

    Science.gov (United States)

    Schneider, Darryl W

    2017-07-01

    Previous studies have shown that interference effects in the flanker task are reduced when physical barriers (e.g., hands) are placed around rather than below a target flanked by distractors. One explanation of this finding is the referential coding hypothesis, whereby the barriers serve as reference objects for allocating attention. In five experiments, the generality of the referential coding hypothesis was tested by investigating whether interference effects are modulated by the placement of virtual barriers (e.g., parentheses). Modulation of flanker interference was found only when target and distractors differed in size and the virtual barriers were beveled wood-grain objects. Under these conditions and those of previous studies, the author conjectures that an impression of depth was produced when the barriers were around the target, such that the target was perceived to be on a different depth plane than the distractors. Perception of depth in the stimulus display might have led to referential coding of the stimuli in three-dimensional (3-D) space, influencing the allocation of attention beyond the horizontal and vertical dimensions. This 3-D referential coding hypothesis is consistent with research on selective attention in 3-D space that shows flanker interference is reduced when target and distractors are separated in depth.

  3. Understanding employment barriers among older Korean immigrants.

    Science.gov (United States)

    Rhee, Min-Kyoung; Chi, Iris; Yi, Jaehee

    2015-06-01

    This study involved an in-depth exploration of the employment barriers of older Korean immigrants in Los Angeles. This qualitative study used data obtained from 6 focus groups and 5 individual interviews. Participants were 36 older Korean immigrants living in Los Angeles, aged 50 years and older, and either unemployed or employed in part-time or full-time work. A grounded theory analytical approach and constant comparison method were used. Ten major themes emerged as employment barriers for older Korean immigrants and were categorized as stereotype, human capital, and acculturation barriers. Ageism among employers specific to Korean culture, lack of English proficiency, separation from U.S. culture, marginalization from both Korean and U.S. cultures, and lack of social networks were important themes. In addition, older Korean immigrants experienced multiple interconnected barriers. The findings highlight the importance of using a multidimensional approach to explore employment barriers among older Korean immigrants who face multiple obstacles in finding jobs. Implications for local governments and Korean communities and potential services to support employment opportunities for older Korean immigrants are discussed. © The Author 2013. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. Surface stability test plan for protective barriers

    International Nuclear Information System (INIS)

    Ligotke, M.W.

    1989-01-01

    Natural-material protective barriers for long-term isolation of buried waste have been identified as integral components of a plan to isolate a number of Hanford defense waste sites. Standards currently being developed for internal and external barrier performance will mandate a barrier surface layer that is resistant to the eolian erosion processes of wind erosion (deflation) and windborne particle deposition (formation of sand dunes). Thus, experiments are needed to measure rates of eolian erosion processes impacting those surfaces under different surface and climatological conditions. Data from these studies will provide information for use in the evaluation of selected surface layers as a means of providing stable cover over waste sites throughout the design life span of protective barriers. The multi-year test plan described in this plan is directed at understanding processes of wind erosion and windborne particle deposition, providing measurements of erosion rates for models, and suggesting construction materials and methods for reducing the effect of long-term eolian erosion on the barrier. Specifically, this plan describes possible methods to measure rates of eolian erosion, including field and laboratory procedure. Advantages and disadvantages of laboratory (wind tunnel) tests are discussed, and continued wind tunnel tests are recommended for wind erosion studies. A comparison between field and wind tunnel erosive forces is discussed. Plans for testing surfaces are described. Guidance is also presented for studying the processes controlling sand dune and blowout formation. 24 refs., 7 figs., 3 tabs

  5. Safety barriers for motorways : shoulder and bridge safety barriers and impact attenuators surveyed and assessed.

    NARCIS (Netherlands)

    Schoon, C.C. Heijer, T. Pol, W.H.M. van de & Jordaan, D.J.R.

    1986-01-01

    The various types and practical qualities of deformable and non-deformable safety barriers are listed. The main conclusions drawn from tests based on several safety criteria are : various types of deformable barriers (steel guide rails) perform well when hit by cars; various types of deformable

  6. Qualitative analysis of barriers and facilitators encountered by HIV patients in an ART adherence programme.

    Science.gov (United States)

    Krummenacher, Isabelle; Spencer, Brenda; Du Pasquier, Sophie; Bugnon, Olivier; Cavassini, Matthias; Schneider, Marie P

    2014-08-01

    Medication adherence is a complex, dynamic and changing behaviour that is affected by a variety of factors, including the patient's beliefs and life circumstances. Studies have highlighted barriers to medication adherence (e.g., unmanaged side effects or a lack of social support), as well as facilitators of medication adherence (e.g., technical simplicity of treatment and psychological acceptance of the disease). Since August 2004, in Lausanne (Switzerland), physicians have referred patients who are either experiencing or are at risk of experiencing problems with their HIV antiretroviral treatment (ART) to a routine interdisciplinary ART adherence programme. This programme consists of multifactorial intervention including electronic drug monitoring (MEMS™). This study's objective was to identify the barriers and facilitators encountered by HIV patients with suboptimal medication adherence (≤90 % adherence over the study period). The community pharmacy of the Department of Ambulatory Care and Community Medicine in Lausanne (Switzerland). The study consisted of a retrospective, qualitative, thematic content analysis of pharmacists' notes that were taken during semi-structured interviews with patients and conducted as part of the ART adherence programme between August 2004 and May 2008. Barriers and facilitators encountered by HIV patients. Barriers to and facilitators of adherence were identified for the 17 included patients. These factors fell into three main categories: (1) cognitive, emotional and motivational; (2) environmental, organisational and social; and (3) treatment and disease. The pharmacists' notes revealed that diverse barriers and facilitators were discussed during medication adherence interviews. Indeed, the results showed that the 17 non-adherent patients encountered barriers and benefited from facilitators. Therefore, pharmacists should inquire about all factors, regardless of whether they have a negative or a positive impact on medication

  7. Placing barrier-island transgression in a blue-carbon context

    Science.gov (United States)

    Theuerkauf, Ethan J.; Rodriguez, Antonio B.

    2017-07-01

    Backbarrier saltmarshes are considered carbon sinks; however, barrier island transgression and the associated processes of erosion and overwash are typically not included in coastal carbon budgets. Here, we present a carbon-budget model for transgressive barrier islands that includes a dynamic carbon-storage term, driven by backbarrier-marsh width, and a carbon-export term, driven by ocean and backbarrier shoreline erosion. To examine the impacts of storms, human disturbances and the backbarrier setting of a transgressive barrier island on carbon budgets and reservoirs, the model was applied to sites at Core Banks and Onslow Beach, NC, USA. Results show that shoreline erosion and burial of backbarrier marsh from washover deposition and dredge-spoil disposal temporarily transitioned each site into a net exporter (source) of carbon. The magnitude of the carbon reservoir was linked to the backbarrier setting of an island. Carbon reservoirs of study sites separated from the mainland by only backbarrier marsh (no lagoon) decreased for over a decade because carbon storage could not keep pace with erosion. With progressive narrowing of the backbarrier marsh, these barriers will begin to function more persistently as carbon sources until the reservoir is depleted at the point where the barrier welds with the mainland. Undeveloped barrier islands with wide lagoons are carbon sources briefly during erosive periods; however, at century time scales are net carbon importers (sinks) because new marsh habitat can form during barrier rollover. Human development on backbarrier saltmarsh serves to reduce the carbon storage capacity and can hasten the transition of an island from a sink to a source.

  8. The fate of saharan dust across the atlantic and implications for a central american dust barrier

    Directory of Open Access Journals (Sweden)

    E. Nowottnick

    2011-08-01

    Full Text Available Saharan dust was observed over the Caribbean basin during the summer 2007 NASA Tropical Composition, Cloud, and Climate Coupling (TC4 field experiment. Airborne Cloud Physics Lidar (CPL and satellite observations from MODIS suggest a barrier to dust transport across Central America into the eastern Pacific. We use the NASA GEOS-5 atmospheric transport model with online aerosol tracers to perform simulations of the TC4 time period in order to understand the nature of this barrier. Our simulations are driven by the Modern Era Retrospective-Analysis for Research and Applications (MERRA meteorological analyses. Compared to observations from MODIS and CALIOP, GEOS-5 reproduces the observed location and magnitude of observed dust events, but our baseline simulation does not develop as strong a barrier to dust transport across Central America as observations suggest. Analysis of the dust transport dynamics and loss processes suggest that while both mechanisms play a role in defining the dust transport barrier, loss processes by wet removal of dust are about twice as important as transport. Sensitivity analyses with our model showed that the dust barrier would not exist without convective scavenging over the Caribbean. The best agreement between our model and the observations was obtained when dust wet removal was parameterized to be more aggressive, treating the dust as we do hydrophilic aerosols.

  9. The Fate of Saharan Dust Across the Atlantic and Implications for a Central American Dust Barrier

    Science.gov (United States)

    Nowottnick, E.; Colarco, P.; da Silva, A.; Hlavka, D.; McGill, M.

    2011-01-01

    Saharan dust was observed over the Caribbean basin during the summer 2007 NASA Tropical Composition, Cloud, and Climate Coupling (TC4) field experiment. Airborne Cloud Physics Lidar (CPL) and satellite observations from MODIS suggest a barrier to dust transport across Central America into the eastern Pacific. We use the NASA GEOS-5 atmospheric transport model with online aerosol tracers to perform simulations of the TC4 time period in order to understand the nature of this barrier. Our simulations are driven by the Modem Era Retrospective-Analysis for Research and Applications (MERRA) meteorological analyses. We evaluate our baseline simulated dust distributions using MODIS and CALIOP satellite and ground-based AERONET sun photometer observations. GEOS-5 reproduces the observed location, magnitude, and timing of major dust events, but our baseline simulation does not develop as strong a barrier to dust transport across Central America as observations suggest. Analysis of the dust transport dynamics and lost processes suggest that while both mechanisms play a role in defining the dust transport barrier, loss processes by wet removal of dust are about twice as important as transport. Sensitivity analyses with our model showed that the dust barrier would not exist without convective scavenging over the Caribbean. The best agreement between our model and the observations was obtained when dust wet removal was parameterized to be more aggressive, treating the dust as we do hydrophilic aerosols.

  10. Free energy and hidden barriers of the β-sheet structure of prion protein.

    Science.gov (United States)

    Paz, S Alexis; Abrams, Cameron F

    2015-10-13

    On-the-fly free-energy parametrization is a new collective variable biasing approach akin to metadynamics with one important distinction: rather than acquiring an accelerated distribution via a history-dependent bias potential, sampling on this distribution is achieved from the beginning of the simulation using temperature-accelerated molecular dynamics. In the present work, we compare the performance of both approaches to compute the free-energy profile along a scalar collective variable measuring the H-bond registry of the β-sheet structure of the mouse Prion protein. Both methods agree on the location of the free-energy minimum, but free-energy profiles from well-tempered metadynamics are subject to a much higher degree of statistical noise due to hidden barriers. The sensitivity of metadynamics to hidden barriers is shown to be a consequence of the history dependence of the bias potential, and we detail the nature of these barriers for the prion β-sheet. In contrast, on-the-fly parametrization is much less sensitive to these barriers and thus displays improved convergence behavior relative to that of metadynamics. While hidden barriers are a frequent and central issue in free-energy methods, on-the-fly free-energy parametrization appears to be a robust and preferable method to confront this issue.

  11. Determination of the thickness and structure of the skin barrier by in vivo laser scanning microscopy

    International Nuclear Information System (INIS)

    Lademann, J; Richter, H; Patzelt, A; Knorr, F; Sterry, W; Astner, S; Antoniou, Ch

    2008-01-01

    Normal skin barrier function is an essential aspect of skin homeostasis and regeneration. Dynamic inflammatory, proliferative and neoplastic skin processes such as wound healing, psoriasis and contact dermatitis are associated with a significant disruption of the skin barrier. In recent years, there has been increasing interest in evaluating cosmetic and pharmacologic products for their ability to restore these protective properties. The gold standard for characterization of barrier function has been the measurement of the transepidermal water loss, however the disadvantage of this method is its interference with several endogenous and exogenous factors such as hydration, perspiration and topically applied substances. This study was aimed to test the clinical applicability of a fluorescence confocal laser scanning microscope (LSM) for a systematic morphologic analysis of the structure, integrity and thickness of the stratum corneum in 10 otherwise healthy volunteers. The influence of skin treatment with commercial moisturizing cream on skin barrier function was evaluated in serial non-invasive examinations. Our findings showed that in vivo LSM may represent a simple and efficient method for the characterization of skin barrier properties, such as the thickness and hydration of the stratum corneum

  12. The declared barriers of the large developing countries waste management projects: The STAR model.

    Science.gov (United States)

    Bufoni, André Luiz; Oliveira, Luciano Basto; Rosa, Luiz Pinguelli

    2016-06-01

    The aim of this study is to investigate and describe the barriers system that precludes the feasibility, or limits the performance of the waste management projects through the analysis of which are the declared barriers at the 432 large waste management projects registered as CDM during the period 2004-2014. The final product is a waste management barriers conceptual model proposal (STAR), supported by literature and corroborated by projects design documents. This paper uses the computer assisted qualitative content analysis (CAQCA) methodology with the qualitative data analysis (QDA) software NVivo®, by 890 fragments, to investigate the motives to support our conclusions. Results suggest the main barriers classification in five types: sociopolitical, technological, regulatory, financial, and human resources constraints. Results also suggest that beyond the waste management industry, projects have disadvantages added related to the same barriers inherent to others renewable energies initiatives. The STAR model sheds some light over the interactivity and dynamics related to the main constraints of the industry, describing the mutual influences and relationships among each one. Future researches are needed to better and comprehensively understand these relationships and ease the development of tools to alleviate or eliminate them. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Imaging blood-brain barrier dysfunction as a biomarker for epileptogenesis.

    Science.gov (United States)

    Bar-Klein, Guy; Lublinsky, Svetlana; Kamintsky, Lyn; Noyman, Iris; Veksler, Ronel; Dalipaj, Hotjensa; Senatorov, Vladimir V; Swissa, Evyatar; Rosenbach, Dror; Elazary, Netta; Milikovsky, Dan Z; Milk, Nadav; Kassirer, Michael; Rosman, Yossi; Serlin, Yonatan; Eisenkraft, Arik; Chassidim, Yoash; Parmet, Yisrael; Kaufer, Daniela; Friedman, Alon

    2017-06-01

    A biomarker that will enable the identification of patients at high-risk for developing post-injury epilepsy is critically required. Microvascular pathology and related blood-brain barrier dysfunction and neuroinflammation were shown to be associated with epileptogenesis after injury. Here we used prospective, longitudinal magnetic resonance imaging to quantitatively follow blood-brain barrier pathology in rats following status epilepticus, late electrocorticography to identify epileptic animals and post-mortem immunohistochemistry to confirm blood-brain barrier dysfunction and neuroinflammation. Finally, to test the pharmacodynamic relevance of the proposed biomarker, two anti-epileptogenic interventions were used; isoflurane anaesthesia and losartan. Our results show that early blood-brain barrier pathology in the piriform network is a sensitive and specific predictor (area under the curve of 0.96, P brain barrier pathology as a clinically relevant predictive, diagnostic and pharmaco!dynamics biomarker for acquired epilepsy. © The Author (2017). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  14. Effectiveness of cable barriers, guardrails, and concrete barrier walls in reducing the risk of injury.

    Science.gov (United States)

    Zou, Yaotian; Tarko, Andrew P; Chen, Erdong; Romero, Mario A

    2014-11-01

    Roadway departure crashes tend to be severe, especially when the roadside exposes the occupants of errant vehicles to excessive injury hazards. As a cost-effective method when the clear zone width is insufficient, road barriers are often installed to prevent errant vehicles from colliding with dangerous obstacles or traversing steep slopes. This paper focuses on the safety performance of road barriers in Indiana in reducing the risk of injury. The objective of the study presented here is to compare the risk of injury among different hazardous events faced by an occupant in a single-vehicle crash. The studied hazardous events include rolling over, striking three types of barriers (guardrails, concrete barrier walls, and cable barriers) with different barrier offsets to the edge of the travelled way, and striking various roadside objects. A total of 2124 single-vehicle crashes (3257 occupants) that occurred between 2008 and 2012 on 517 pair-matched homogeneous barrier and non-barrier segments were analyzed. A binary logistic regression model with mixed effects was estimated for vehicle occupants. The segment pairing process and the use of random effects were able to handle the commonality within the same segment pair as well as the heterogeneity across segment pairs. The modeling results revealed that hitting a barrier is associated with lower risk of injury than a high-hazard event (hitting a pole, rollover, etc.). The odds of injury are reduced by 39% for median concrete barrier walls offset 15-18ft from the travelled way, reduced by 65% for a guardrail face offset 5-55ft, reduced by 85% for near-side median cable barriers (offset between 10ft and 29ft), and reduced by 78% with far-side median cable barriers (offset at least 30ft). Comparing different types of barriers is useful where some types of barriers can be used alternatively. This study found that the odds of injury are 43% lower when striking a guardrail instead of a median concrete barrier offset 15-18ft

  15. Devices for overcoming biological barriers: the use of physical forces to disrupt the barriers.

    Science.gov (United States)

    Mitragotri, Samir

    2013-01-01

    Overcoming biological barriers including skin, mucosal membranes, blood brain barrier as well as cell and nuclear membrane constitutes a key hurdle in the field of drug delivery. While these barriers serve the natural protective function in the body, they limit delivery of drugs into the body. A variety of methods have been developed to overcome these barriers including formulations, targeting peptides and device-based technologies. This review focuses on the use of physical methods including acoustic devices, electric devices, high-pressure devices, microneedles and optical devices for disrupting various barriers in the body including skin and other membranes. A summary of the working principles of these devices and their ability to enhance drug delivery is presented. Copyright © 2012. Published by Elsevier B.V.

  16. Potential corridors and barriers for plague spread in Central Asia.

    Science.gov (United States)

    Wilschut, Liesbeth I; Addink, Elisabeth A; Heesterbeek, Hans; Heier, Lise; Laudisoit, Anne; Begon, Mike; Davis, Stephen; Dubyanskiy, Vladimir M; Burdelov, Leonid A; de Jong, Steven M

    2013-10-31

    Plague (Yersinia pestis infection) is a vector-borne disease which caused millions of human deaths in the Middle Ages. The hosts of plague are mostly rodents, and the disease is spread by the fleas that feed on them. Currently, the disease still circulates amongst sylvatic rodent populations all over the world, including great gerbil (Rhombomys opimus) populations in Central Asia. Great gerbils are social desert rodents that live in family groups in burrows, which are visible on satellite images. In great gerbil populations an abundance threshold exists, above which plague can spread causing epizootics. The spatial distribution of the host species is thought to influence the plague dynamics, such as the direction of plague spread, however no detailed analysis exists on the possible functional or structural corridors and barriers that are present in this population and landscape. This study aims to fill that gap. Three 20 by 20 km areas with known great gerbil burrow distributions were used to analyse the spatial distribution of the burrows. Object-based image analysis was used to map the landscape at several scales, and was linked to the burrow maps. A novel object-based method was developed - the mean neighbour absolute burrow density difference (MNABDD) - to identify the optimal scale and evaluate the efficacy of using landscape objects as opposed to square cells. Multiple regression using raster maps was used to identify the landscape-ecological variables that explain burrow density best. Functional corridors and barriers were mapped using burrow density thresholds. Cumulative resistance of the burrow distribution to potential disease spread was evaluated using cost distance analysis. A 46-year plague surveillance dataset was used to evaluate whether plague spread was radially symmetric. The burrow distribution was found to be non-random and negatively correlated with Greenness, especially in the floodplain areas. Corridors and barriers showed a mostly NWSE

  17. Phonon tunneling through a double barrier system

    Energy Technology Data Exchange (ETDEWEB)

    Villegas, Diosdado [Departamento de Física, Universidad Central “Marta Abreu” de Las Villas, CP 54830, Santa Clara, Villa Clara (Cuba); Instituto de Física, Universidad Autónoma de Puebla, 18 Sur y San Claudio, Edif. 110A, Ciudad Universitaria, 72570 Puebla (Mexico); León-Pérez, Fernando de [Centro Universitario de la Defensa de Zaragoza, Ctra. de Huesca s/n, E-50090 Zaragoza (Spain); Pérez-Álvarez, R. [Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, CP 62209 Cuernavaca (Mexico); Arriaga, J., E-mail: arriaga@ifuap.buap.mx [Instituto de Física, Universidad Autónoma de Puebla, 18 Sur y San Claudio, Edif. 110A, Ciudad Universitaria, 72570 Puebla (Mexico)

    2015-04-15

    The tunneling of optical and acoustic phonons at normal incidence on a double-barrier is studied in this paper. Transmission coefficients and resonance conditions are derived theoretically under the assumption that the long-wavelength approximation is valid. It is shown that the behavior of the transmission coefficients for the symmetric double barrier has a Lorentzian form close to resonant frequencies and that Breit–Wigner's formula have a general validity in one-dimensional phonon tunneling. Authors also study the so-called generalized Hartman effect in the tunneling of long-wavelength phonons and show that this effect is a numerical artifact resulting from taking the opaque limit before exploring the variation with a finite barrier width. This study could be useful for the design of acoustic devices.

  18. Barriers faced by Romanian SMEs in exporting

    Directory of Open Access Journals (Sweden)

    Dana BOŞCOR

    2017-07-01

    Full Text Available This study aims to identify the most important barriers faced by Romanians SMEs in the process of exporting. The research was based on a focus group including 12 managers from different exporting companies from Brasov. The most important barriers encountered by companies were linked to currency fluctuations, methods of payment, lack of specialized staff, lack of financial resources and a low level of government support. Results from the study revealed that companies should have access at financing in order to invest in new technologies and to create higher quality products that could meet the requirements of the foreign buyers. In order to reduce the export barriers, small and medium sized exporters should create partnerships for reducing the costs of promotion in foreign markets. The government should also increase its support by offering exporters access at financing and market information at lower costs.

  19. Epidermal Growth Factor and Intestinal Barrier Function

    Directory of Open Access Journals (Sweden)

    Xiaopeng Tang

    2016-01-01

    Full Text Available Epidermal growth factor (EGF is a 53-amino acid peptide that plays an important role in regulating cell growth, survival, migration, apoptosis, proliferation, and differentiation. In addition, EGF has been established to be an effective intestinal regulator helping to protect intestinal barrier integrity, which was essential for the absorption of nutrients and health in humans and animals. Several researches have demonstrated that EGF via binding to the EGF receptor and subsequent activation of Ras/MAPK, PI3K/AKT, PLC-γ/PKC, and STATS signal pathways regulates intestinal barrier function. In this review, the relationship between epidermal growth factor and intestinal development and intestinal barrier is described, to provide a better understanding of the effects of EGF on intestine development and health.

  20. Organizational Barriers to Cultural Competence in Hospice.

    Science.gov (United States)

    Reese, Dona J; Beckwith, Samira K

    2015-11-01

    This national mixed method study with directors of 207 hospices identified major barriers to cultural competence, including (1) lack of funding for additional staff for community outreach or development of culturally competent programs, (2) lack of applications from diverse professionals, and (3) lack of knowledge about diverse cultures and what cultural groups in the community are not being served. Qualitative results indicated that elements of an organizational culture, which create barriers to access included (1) failure to prioritize cultural competence, (2) failure to budget for culturally competent services, and (3) a staff that does not value awareness of cultural differences, is uncomfortable with diversity, and stereotypes diverse individuals. In phase 2, an interactive session with a 100-symposium audience provided strategies to address the barriers. © The Author(s) 2014.

  1. Phonon tunneling through a double barrier system

    International Nuclear Information System (INIS)

    Villegas, Diosdado; León-Pérez, Fernando de; Pérez-Álvarez, R.; Arriaga, J.

    2015-01-01

    The tunneling of optical and acoustic phonons at normal incidence on a double-barrier is studied in this paper. Transmission coefficients and resonance conditions are derived theoretically under the assumption that the long-wavelength approximation is valid. It is shown that the behavior of the transmission coefficients for the symmetric double barrier has a Lorentzian form close to resonant frequencies and that Breit–Wigner's formula have a general validity in one-dimensional phonon tunneling. Authors also study the so-called generalized Hartman effect in the tunneling of long-wavelength phonons and show that this effect is a numerical artifact resulting from taking the opaque limit before exploring the variation with a finite barrier width. This study could be useful for the design of acoustic devices

  2. Mucus as a Barrier to Drug Delivery

    DEFF Research Database (Denmark)

    Bøgh, Marie; Nielsen, Hanne Mørck

    2015-01-01

    -established as essential tools in drug research and development, but traditionally, mucus-containing models have only rarely been applied. However, a number of mucus-containing in vitro models have recently been described in the literature and their properties and applications will be reviewed and discussed. Finally...... barrier to drug delivery. Current knowledge of mucus characteristics and barrier properties, as achieved by state-of-the-art methodologies, is the topic of this MiniReview emphasizing the gastrointestinal mucus and an overall focus on oral drug delivery. Cell culture-based in vitro models are well......, studies of peptide and protein drug diffusion in and through mucus and studies of mucus-penetrating nanoparticles are included to illustrate the mucus as a potentially important barrier to obtain sufficient bioavailability of orally administered drugs, and thus an important parameter to address...

  3. Surface barrier research at the Hanford Site

    International Nuclear Information System (INIS)

    Gee, G.W.; Ward, A.L.; Fayer, M.J.

    1997-01-01

    At the DOE Hanford Site, a field-scale prototype surface barrier was constructed in 1994 over an existing waste site as a part of a CERCLA treatability test. The above-grade barrier consists of a fine-soil layer overlying coarse layers of sands, gravels, basalt rock (riprap), and a low permeability asphalt layer. Two sideslope configurations, clean-fill gravel on a 10:1 slope and basalt riprap on a 2:1 slope, were built and are being tested. Design considerations included: constructability; drainage and water balance monitoring, wind and water erosion control and monitoring; surface revegetation and biotic intrusion; subsidence and sideslope stability, and durability of the asphalt layer. The barrier is currently in the final year of a three-year test designed to answer specific questions related to stability and long-term performance. One half of the barrier is irrigated such that the total water applied, including precipitation, is 480 mm/yr (three times the long-term annual average). Each year for the past two years, an extreme precipitation event (71 mm in 8 hr) representing a 1,000-yr return storm was applied in late March, when soil water storage was at a maximum. While the protective sideslopes have drained significant amounts of water, the soil cover (2-m of silt-loam soil overlying coarse sand and rock) has never drained. During the past year there was no measurable surface runoff or wind erosion. This is attributed to extensive revegetation of the surface. In addition, the barrier elevation has shown a small increase of 2 to 3 cm that is attributed to a combination of root proliferation and freeze/thaw activity. Testing will continue through September 1997. Performance data from the prototype barrier will be used by DOE in site-closure decisions at Hanford

  4. Permanent isolation surface barrier: Functional performance

    Energy Technology Data Exchange (ETDEWEB)

    Wing, N.R.

    1993-10-01

    This document presents the functional performance parameters for permanent isolation surface barriers. Permanent isolation surface barriers have been proposed for use at the Hanford Site (and elsewhere) to isolate and dispose of certain types of waste in place. Much of the waste that would be disposed of using in-place isolation techniques is located in subsurface structures, such as solid waste burial grounds, tanks, vaults, and cribs. Unless protected in some way, the wastes could be transported to the accessible environment via transport pathways, such as water infiltration, biointrusion, wind and water erosion, human interference, and/or gaseous release.

  5. Dielectric barrier discharge image processing by Photoshop

    Science.gov (United States)

    Dong, Lifang; Li, Xuechen; Yin, Zengqian; Zhang, Qingli

    2001-09-01

    In this paper, the filamentary pattern of dielectric barrier discharge has been processed by using Photoshop, the coordinates of each filament can also be obtained. By using Photoshop two different ways have been used to analyze the spatial order of the pattern formation in dielectric barrier discharge. The results show that the distance of the neighbor filaments at U equals 14 kV and d equals 0.9 mm is about 1.8 mm. In the scope of the experimental error, the results from the two different methods are similar.

  6. Electrochemical cell structure including an ionomeric barrier

    Science.gov (United States)

    Lambert, Timothy N.; Hibbs, Michael

    2017-06-20

    An apparatus includes an electrochemical half-cell comprising: an electrolyte, an anode; and an ionomeric barrier positioned between the electrolyte and the anode. The anode may comprise a multi-electron vanadium phosphorous alloy, such as VP.sub.x, wherein x is 1-5. The electrochemical half-cell is configured to oxidize the vanadium and phosphorous alloy to release electrons. A method of mitigating corrosion in an electrochemical cell includes disposing an ionomeric barrier in a path of electrolyte or ion flow to an anode and mitigating anion accumulation on the surface of the anode.

  7. Fusion barrier distributions and fission anisotropies

    International Nuclear Information System (INIS)

    Hinde, D.J.; Morton, C.R.; Dasgupta, M.; Leigh, J.R.; Lestone, J.P.; Lemmon, R.C.; Mein, J.C.; Newton, J.O.; Timmers, H.; Rowley, N.; Kruppa, A.T.

    1995-01-01

    Fusion excitation functions for 16,17 O+ 144 Sm have been measured to high precision. The extracted fusion barrier distributions show a double-peaked structure interpreted in terms of coupling to inelastic collective excitations of the target. The effect of the positive Q-value neutron stripping channel is evident in the reaction with 17 O. Fission and evaporation residue cross-sections and excitation functions have been measured for the reaction of 16 O+ 208 Pb and the fusion barrier distribution and fission anisotropies determined. It is found that the moments of the fusion l-distribution determined from the fusion and fission measurements are in good agreement. ((orig.))

  8. Developments in permeable and low permeability barriers

    International Nuclear Information System (INIS)

    Jefferis, S.A.; Norris, G.H.; Thomas, A.O.

    1997-01-01

    The concept of the reactive treatment zone whereby pollutants are attenuated as they move along a pathway in the ground has enabled a re-thinking of many of the concepts of containment. In particular it offers the potential for the control of the flux from a contaminated area by controlling the contaminant concentration in the pathway(s) as well as or instead of using a low permeability barrier. The paper outlines the basic concepts of the reactive treatment zone and the use of permeable and low permeability reactive systems. The paper then gives a case history of the installation of a permeable barrier using an in-situ reaction chamber

  9. Vehicle barriers: emphasis on natural features

    International Nuclear Information System (INIS)

    Adams, K.G.; Roscoe, B.J.

    1985-07-01

    The recent increase in the use of car and truck bombs by terrorist organizations has led NRC to evaluate the adequacy of licensee security against such threats. As part of this evaluation, one of the factors is the effectiveness of terrain and vegetation in providing barriers against the vehicle entry. The effectiveness of natural features is presented in two contexts. First, certain natural features are presented. Second, the effectiveness of combinations of features is presented. In addition to the discussion of natural features, this report provides a discussion of methods to slow vehicles. Also included is an overview of man-made barrier systems, with particular attention to ditches. 17 refs., 49 figs

  10. Intestinal barrier integrity and inflammatory bowel disease

    DEFF Research Database (Denmark)

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

    2017-01-01

    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...

  11. LGBT Populations' Barriers to Cancer Care.

    Science.gov (United States)

    Boehmer, Ulrike

    2018-02-01

    To describe lesbian, gay, bisexual, and transgender (LGBT) individuals' barriers to accessing and receiving quality cancer care. Published data on cancer care and studies of LGBT individuals. There is a clustering of barriers among LGBT individuals, which suggests multiple inequities exist in LGBT individuals' cancer care, although data on disparities along the cancer control continuum are not consistently available. Nurses can make a difference in LGBT individuals' cancer care by obtaining training on LGBT health and their cancer-related needs and by providing a welcoming and respectful relationship with LGBT patients. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Adiabatic heavy-ion fusion potentials for fusion at deep sub-barrier ...

    Indian Academy of Sciences (India)

    barrier energies has been examined. The adiabatic limit of fusion barriers has been determined from experimental data using the barrier penetration model. These adiabatic barriers are consistent with the adiabatic fusion barriers derived from ...

  13. Proteomics and the dynamic plasma membrane

    DEFF Research Database (Denmark)

    Sprenger, Richard R; Jensen, Ole Nørregaard

    2010-01-01

    plasma membrane is of particular interest, by not only serving as a barrier between the "cell interior" and the external environment, but moreover by organizing and clustering essential components to enable dynamic responses to internal and external stimuli. Defining and characterizing the dynamic plasma...... the challenges in functional proteomic studies of the plasma membrane. We review the recent progress in MS-based plasma membrane proteomics by presenting key examples from eukaryotic systems, including mammals, yeast and plants. We highlight the importance of enrichment and quantification technologies required...... for detailed functional and comparative analysis of the dynamic plasma membrane proteome....

  14. Simulation of crash tests for high impact levels of a new bridge safety barrier

    Science.gov (United States)

    Drozda, Jiří; Rotter, Tomáš

    2017-09-01

    The purpose is to show the opportunity of a non-linear dynamic impact simulation and to explain the possibility of using finite element method (FEM) for developing new designs of safety barriers. The main challenge is to determine the means to create and validate the finite element (FE) model. The results of accurate impact simulations can help to reduce necessary costs for developing of a new safety barrier. The introductory part deals with the creation of the FE model, which includes the newly-designed safety barrier and focuses on the application of an experimental modal analysis (EMA). The FE model has been created in ANSYS Workbench and is formed from shell and solid elements. The experimental modal analysis, which was performed on a real pattern, was employed for measuring the modal frequencies and shapes. After performing the EMA, the FE mesh was calibrated after comparing the measured modal frequencies with the calculated ones. The last part describes the process of the numerical non-linear dynamic impact simulation in LS-DYNA. This simulation was validated after comparing the measured ASI index with the calculated ones. The aim of the study is to improve professional public knowledge about dynamic non-linear impact simulations. This should ideally lead to safer, more accurate and profitable designs.

  15. Design of an improved post for use in a non-proprietary high-tension cable median barrier.

    Science.gov (United States)

    2015-05-01

    The objective of this research study was to develop a revised post section for the non-proprietary high-tension cable : median barrier that improved the safety and function of the post by lowering strong-axis forces. A total of twenty dynamic : compo...

  16. From Metadynamics to Dynamics

    Science.gov (United States)

    Tiwary, Pratyush; Parrinello, Michele

    2013-12-01

    Metadynamics is a commonly used and successful enhanced sampling method. By the introduction of a history dependent bias which depends on a restricted number of collective variables it can explore complex free energy surfaces characterized by several metastable states separated by large free energy barriers. Here we extend its scope by introducing a simple yet powerful method for calculating the rates of transition between different metastable states. The method does not rely on a previous knowledge of the transition states or reaction coordinates, as long as collective variables are known that can distinguish between the various stable minima in free energy space. We demonstrate that our method recovers the correct escape rates out of these stable states and also preserves the correct sequence of state-to-state transitions, with minimal extra computational effort needed over ordinary metadynamics. We apply the formalism to three different problems and in each case find excellent agreement with the results of long unbiased molecular dynamics runs.

  17. 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

  18. Jumping Dynamics

    DEFF Research Database (Denmark)

    Sannino, Francesco

    2013-01-01

    We propose an alternative paradigm to the conjectured Miransky scaling potentially underlying the physics describing the transition from the conformally broken to the conformally restored phase when tuning certain parameters such as the number of flavors in gauge theories. According to the new pa...... without particle interpretation. The jumping scenario, therefore, does not support a near-conformal dynamics of walking type. We will also discuss the impact of jumping dynamics on the construction of models of dynamical electroweak symmetry breaking....

  19. Dynamical systems

    CERN Document Server

    Sternberg, Shlomo

    2010-01-01

    Celebrated mathematician Shlomo Sternberg, a pioneer in the field of dynamical systems, created this modern one-semester introduction to the subject for his classes at Harvard University. Its wide-ranging treatment covers one-dimensional dynamics, differential equations, random walks, iterated function systems, symbolic dynamics, and Markov chains. Supplementary materials offer a variety of online components, including PowerPoint lecture slides for professors and MATLAB exercises.""Even though there are many dynamical systems books on the market, this book is bound to become a classic. The the

  20. Dynamics Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The Dynamics Lab replicates vibration environments for every Navy platform. Testing performed includes: Flight Clearance, Component Improvement, Qualification, Life...

  1. One-week exposure to a free-choice high-fat high-sugar diet does not disrupt blood-brain barrier permeability in fed or overnight fasted rats

    NARCIS (Netherlands)

    Rijnsburger, M.; Unmehopa, U. A.; Eggels, L.; Serlie, M. J.; La Fleur, S. E.

    2017-01-01

    The hypothalamus lies adjacent to the third ventricle and is in close proximity with the median eminence (ME), a circumventricular organ with an incomplete blood-brain barrier (BBB) which controls direct entry of nutrients into the brain. The blood-CSF barrier of the hypothalamus shows dynamic

  2. Removing bridge barriers stimulates suicides: an unfortunate natural experiment.

    Science.gov (United States)

    Beautrais, Annette L; Gibb, Sheree J; Fergusson, David M; Horwood, L John; Larkin, Gregory Luke

    2009-06-01

    Safety barriers to prevent suicide by jumping were removed from Grafton Bridge in Auckland, New Zealand, in 1996 after having been in place for 60 years. This study compared the number of suicides due to jumping from the bridge after the reinstallation of safety barriers in 2003. National mortality data for suicide deaths were compared for three time periods: 1991-1995 (old barrier in place); 1997-2002 (no barriers in place); 2003-2006 (after barriers were reinstated). Removal of barriers was followed by a fivefold increase in the number and rate of suicides from the bridge. These increases led to a decision to reinstall safety barriers. Since the reinstallation of barriers, of an improved design, in 2003, there have been no suicides from the bridge. This natural experiment, using a powerful a-b-a (reversal) design, shows that safety barriers are effective in preventing suicide: their removal increases suicides; their reinstatement prevents suicides.

  3. Use of electrical barriers to deter movement of round goby

    Science.gov (United States)

    Savino, Jacqueline F.; Jude, David J.; Kostich, Melissa J.; Coutant, Charles C.

    2001-01-01

    An electrical barrier was chosen as a possible means to deter movement of round goby Neogobius melanostomus. Feasibility studies in a 2.1-m donut-shaped tank determined the electrical parameters necessary to inhibit round goby from crossing the 1-m stretch of the benthic, electrical barrier. Increasing electrical pulse duration and voltage increased effectiveness of the barrier in deterring round goby movement through the barrier. Differences in activity of round goby during daytime and nocturnal tests did not change the effectiveness of the barrier. In field verification studies, an electrical barrier was placed between two blocking nets in the Shiawassee River, Michigan. The barrier consisted of a 6-m wide canvas on which were laid four cables carrying the electrical current. Seven experiments were conducted, wherein 25 latex paint-marked round goby were introduced upstream of the electrical barrier and recovered 24 h later upstream, on, and downstream of the barrier. During control studies, round goby moved across the barrier within 20 min from release upstream. With the barrier on and using the prescribed electrical settings shown to inhibit passage in the laboratory, the only marked round goby found below the barrier were dead. At reduced pulse durations, a few round goby (mean one/test) were found alive, but debilitated, below the barrier. The electrical barrier could be incorporated as part of a program in reducing movement of adult round goby through artificial connections between watersheds.

  4. Deployment Efficiency and Barrier Effectiveness Testing of a Temporary Anti-Personnel (TAP) Barrier System.

    Energy Technology Data Exchange (ETDEWEB)

    Allen, David James [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hedrick, Charles D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Martinez, Ruben [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-02-01

    This report documents tests conducted by Sandia National Laboratories (SNL) on behalf of the U.S. Department of State to evaluate a temporary anti-personnel (TAP) barrier system developed by Mitigation Technologies. For this, the SNL Denial and Structural Assessment department developed a test protocol for the evaluation of the TAP barrier system on the basis of deployment efficiency and barrier effectiveness against a riotous/mob attack threat. The test protocol was then executed by SNL personnel and the results of the testing are documented.

  5. Motivations and Barriers in Promoting Preschool Education

    Science.gov (United States)

    Küçükturan, A. Güler; Akbaba Altun, Sadegül

    2017-01-01

    This study is designed to explore the reasons for sending and not sending preschool age children to preschools at an early age by exploring the motivations for and barriers towards promoting preschool education in Turkey. It aimed to determine various stakeholders' perceptions, attitudes, and knowledge related to preschool education in order to…

  6. Kiwifruit, mucins, and the gut barrier.

    Science.gov (United States)

    Moughan, Paul J; Rutherfurd, Shane M; Balan, Prabhu

    2013-01-01

    Kiwifruit has long been regarded in China, where it originated from, for its health properties and particularly in relation to digestion and general gut health. There are a number of physical and chemical properties of the fruit, including its dietary fiber content, the presence of raphides, its high water holding capacity and actinidin content, that suggest that kiwifruit may be effective in influencing gut mucin production and thus enhancing the integrity of the gut barrier. The mucous layer, which comprises mucins and other materials, overlying the mucosal epithelium, is an important component of the gut barrier. The gut barrier plays a crucial role in separating the host from the often noxious external environment. The mucous layer, which covers the entire gastrointestinal tract (GIT), is the front line of innate host defense. There have been few direct studies of the effect of kiwifruit ingestion on mucin production in the GIT, and findings that are available using animal models are somewhat inconsistent. Taking results for digesta mucin content, number of goblet cells, and mucin gene expression, together, it would seem that green kiwifruit and possibly gold kiwifruit do influence gut mucin production, and the kiwifruit as part of a balanced diet may help to maintain the mucous layer and gut barrier. More corroborative experimental evidence is needed, and studies need to be undertaken in humans. Copyright © 2013 Elsevier Inc. All rights reserved.

  7. Homoepitaxial graphene tunnel barriers for spin transport

    Directory of Open Access Journals (Sweden)

    Adam L. Friedman

    2016-05-01

    Full Text Available Tunnel barriers are key elements for both charge-and spin-based electronics, offering devices with reduced power consumption and new paradigms for information processing. Such devices require mating dissimilar materials, raising issues of heteroepitaxy, interface stability, and electronic states that severely complicate fabrication and compromise performance. Graphene is the perfect tunnel barrier. It is an insulator out-of-plane, possesses a defect-free, linear habit, and is impervious to interdiffusion. Nonetheless, true tunneling between two stacked graphene layers is not possible in environmental conditions usable for electronics applications. However, two stacked graphene layers can be decoupled using chemical functionalization. Here, we demonstrate that hydrogenation or fluorination of graphene can be used to create a tunnel barrier. We demonstrate successful tunneling by measuring non-linear IV curves and a weakly temperature dependent zero-bias resistance. We demonstrate lateral transport of spin currents in non-local spin-valve structures, and determine spin lifetimes with the non-local Hanle effect. We compare the results for hydrogenated and fluorinated tunnel and we discuss the possibility that ferromagnetic moments in the hydrogenated graphene tunnel barrier affect the spin transport of our devices.

  8. The biological significance of brain barrier mechanisms

    DEFF Research Database (Denmark)

    Saunders, Norman R; Habgood, Mark D; Møllgård, Kjeld

    2016-01-01

    that prevent the entry of many drugs of therapeutic potential into the brain. We outline those that have been tried and discuss why they may so far have been largely unsuccessful. Currently, a promising approach appears to be focal, reversible disruption of the blood-brain barrier using focused ultrasound...

  9. A microfluidic device with a diffusion barrier

    DEFF Research Database (Denmark)

    2014-01-01

    with a common junction via micro channels. To enable amplification of DNA, e.g. by MDA, the device comprises a diffusion barrier at each inlet configured to increase the pressure threshold for a reagent to cross the resistor. The invention further provides a method of mixing liquid reagents by use of the device...

  10. Deep inelastic scattering near the Coulomb barrier

    Energy Technology Data Exchange (ETDEWEB)

    Gehring, J.; Back, B.; Chan, K. [and others

    1995-08-01

    Deep inelastic scattering was recently observed in heavy ion reactions at incident energies near and below the Coulomb barrier. Traditional models of this process are based on frictional forces and are designed to predict the features of deep inelastic processes at energies above the barrier. They cannot be applied at energies below the barrier where the nuclear overlap is small and friction is negligible. The presence of deep inelastic scattering at these energies requires a different explanation. The first observation of deep inelastic scattering near the barrier was in the systems {sup 124,112}Sn + {sup 58,64}Ni by Wolfs et al. We previously extended these measurements to the system {sup 136}Xe + {sup 64}Ni and currently measured the system {sup 124}Xe + {sup 58}Ni. We obtained better statistics, better mass and energy resolution, and more complete angular coverage in the Xe + Ni measurements. The cross sections and angular distributions are similar in all of the Sn + Ni and Xe + Ni systems. The data are currently being analyzed and compared with new theoretical calculations. They will be part of the thesis of J. Gehring.

  11. Breaking the Barriers to the Circular Economy

    NARCIS (Netherlands)

    Kirchherr, J.W.|info:eu-repo/dai/nl/411261487; Hekkert, M.P.|info:eu-repo/dai/nl/143777629; Bour, Ruben; Huijbrechtse-Truijens, Anne; Kostense-Smit, Erica; Muller, Jennifer

    2017-01-01

    The Copernicus Institute of Sustainable Development, Utrecht University, the Netherlands and Deloitte have jointly carried out research on barriers to the Circular Economy (CE) in the European Union. For this research, a survey with 153 businesses, 55 government officials and expert interviews with

  12. Tacit Knowledge Barriers within Franchise Organizations

    Science.gov (United States)

    Cumberland, Denise M.; Githens, Rod P.

    2010-01-01

    This paper reviews knowledge management in the context of a franchise business operation, with a focus on tacit knowledge barriers. In a franchise organization, the transfer of knowledge occurs on multiple levels and has an added level of complexity because of the number of partners and relationships. Tacit knowledge transfer should occur…

  13. 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…

  14. Barriers vs Creativity in Translator Training

    Science.gov (United States)

    Yazici, Mine

    2016-01-01

    This paper discusses translation problems awaiting Turkish students as well as the creative solutions they develop in overcoming them. It consists of two parts; The first part studies the barriers concerning translation procedures from the perspective of translation theory and Turkish translation history; The second parts analyses the impact of…

  15. Reconnaissance level study Mississippi storm surge barrier

    NARCIS (Netherlands)

    Van Ledden, M.; Lansen, A.J.; De Ridder, H.A.J.; Edge, B.

    2012-01-01

    This paper reports a reconnaissance level study of a storm surge barrier in the Mississippi River. Historical hurricanes have shown storm surge of several meters along the Mississippi River levees up to and upstream of New Orleans. Future changes due to sea level rise and subsidence will further

  16. Seismic Barrier Protection of Critical Infrastructure

    Science.gov (United States)

    2017-05-14

    Seismic Barrier Protection of Critical Infrastructure Robert Haupt, Vladimir Liberman, and Mordechai Rothschild MIT Lincoln Laboratory 244...engineering building structural designs and materials have evolved over many years to minimize the destructive effects of seismic surface waves. However...concept and approach to redirect and attenuate the ground motion amplitudes caused by earthquakes by implementing an engineered subsurface seismic

  17. Dielectric barrier discharges applied for optical spectrometry

    Czech Academy of Sciences Publication Activity Database

    Brandt, S.; Schütz, A.; Klute, F. D.; Kratzer, Jan; Franzke, J.

    2016-01-01

    Roč. 123, SEP (2016), s. 6-32 ISSN 0584-8547 R&D Projects: GA ČR GA14-23532S Institutional support: RVO:68081715 Keywords : dielectric barrier discharge * analytical spectroscopy * applications Subject RIV: CB - Analytical Chemistry , Separation Impact factor: 3.241, year: 2016

  18. Innovation drivers and barriers in food processing

    NARCIS (Netherlands)

    Fortuin, F.T.J.M.; Omta, S.W.F.

    2009-01-01

    Purpose - The food processing industry, confronted with increased global competition and more stringent customer demands, is pressurized to improve the pace and quality of its innovation processes. This paper aims to find out what factors constitute the main drivers and barriers to innovation and to

  19. Radon barrier: Method of testing airtightness

    DEFF Research Database (Denmark)

    Rasmussen, Torben Valdbjørn; Buch-Hansen, Thomas Cornelius

    2017-01-01

    to the test method were suggested. A digital stirring and control system, and a method for determining the mean air pressure difference, as well as a method for testing barriers with a very low air infiltration, were provided. The digital stirring and control system ensured automatic control and measuring...

  20. Mechanical control of the endothelial barrier

    NARCIS (Netherlands)

    Oldenburg, Joppe; de Rooij, Johan

    The integrity of the endothelial barrier is controlled by the combined action of chemical and mechanical signaling systems. Permeability-regulating factors signal through small GTPases to regulate the architecture of the cytoskeleton and this has a strong impact on the morphology and stability of

  1. Physical protection system using activated barriers

    International Nuclear Information System (INIS)

    Timm, R.E.; Zinneman, T.E.; Haumann, J.R.; Flaugher, H.A.; Reigle, D.L.

    1984-03-01

    The Argonne National Laboratory has recently installed an activated barrier, the Access Denial System, to upgrade its security. The technology of this system was developed in the late 70's by Sandia National Laboratory-Albuquerque. The Argonne National Laboratory is the first Department of Energy facility to use this device. Recent advancements in electronic components provide the total system support that makes the use of an activated barrier viable and desirable. The premise of an activated barrier is that it is deployed after a positive detection of an adversary is made and before the adversary can penetrate vital area. To accomplish this detection, sophisticated alarms, assessment, and communications must be integrated into a system that permits a security inspector to make a positive evaluation and to activate the barrier. The alarm sensor locations are selected to provide protection in depth. Closed circuit television is used with components that permit multiple video frames to be stored for automated, priority-based playback to the security inspector. Further, algorithms permit look-ahead surveillance of vital areas so that the security inspector can activate the access denial system in a timely manner and not be restricted to following the adversaries' penetration path(s)

  2. BSN completion barriers, challenges, incentives, and strategies.

    Science.gov (United States)

    Duffy, Marie T; Friesen, Mary Ann; Speroni, Karen Gabel; Swengros, Diane; Shanks, Laura A; Waiter, Pamela A; Sheridan, Michael J

    2014-04-01

    The objectives of this study were to explore RN perceptions regarding barriers/challenges and incentives/supports for BSN completion and identify recommendations to increase RN BSN completion. The Institute of Medicine's 2011 The Future of Nursing report recommended the proportion of RNs with a BSN increase to 80% by 2020. This qualitative study included 41 RNs who participated in 1 of 6 focus groups based on their BSN completion status. Primary themes were sacrifices, barriers/challenges, incentives/supports, value, how to begin, and pressure. Primary BSN completion barriers/challenges were work-life balance and economic issues. Incentives/supports identified were financial compensation, assistance from employer and academic institution, and encouragement from family. Institutional strategies recommended for increasing BSN completion rates were improved access to education and financial support facilitated by collaboration between hospitals and academic institutions. Exploring RN barriers/challenges and incentives/supports for BSN completion can lead to implementation of institutional strategies, such as tuition reimbursement and academic collaboration.

  3. Barrier methods of birth control - slideshow

    Science.gov (United States)

    ... gov/ency/presentations/100107.htm Barrier methods of birth control - series—Female normal anatomy To use the sharing ... A.M. Editorial team. Related MedlinePlus Health Topics Birth Control A.D.A.M., Inc. is accredited by ...

  4. Understanding Motivators and Barriers to Physical Activity

    Science.gov (United States)

    Patay, Mary E.; Patton, Kevin; Parker, Melissa; Fahey, Kathleen; Sinclair, Christina

    2015-01-01

    The purpose of this study was to understand the factors that influence physical activity among year-round residents in an isolated summer resort community. Specifically, we explored the personal, environmental, social, and culture-specific perceived motivators and barriers to physical activity. Participants were formally interviewed about their…

  5. The Barrier within: Relational Aggression among Women

    Science.gov (United States)

    Brock, Barbara L.

    2010-01-01

    Relational aggression among women presents an overlooked barrier to women's quest for advancement in the workplace. Although research on women's leadership extols their ability to collaborate and form lasting, supportive relationships, one cannot assume that all women are supportive of other women. Research reveals that relational aggression,…

  6. Open Educational Resources: Removing Barriers from Within

    Science.gov (United States)

    Mishra, Sanjaya

    2017-01-01

    Enthusiasts and evangelists of open educational resources (OER) see these resources as a panacea for all of the problems of education. However, despite its promises, their adoption in educational institutions is slow. There are many barriers to the adoption of OER, and many are from within the community of OER advocates. This commentary calls for…

  7. Dielectric barrier discharges applied for optical spectrometry

    Czech Academy of Sciences Publication Activity Database

    Brandt, S.; Schütz, A.; Klute, F. D.; Kratzer, Jan; Franzke, J.

    2016-01-01

    Roč. 123, SEP (2016), s. 6-32 ISSN 0584-8547 R&D Projects: GA ČR GA14-23532S Institutional support: RVO:68081715 Keywords : dielectric barrier discharge * analytical spectroscopy * applications Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.241, year: 2016

  8. Reducing Cultural Barriers via Internet Courses

    Science.gov (United States)

    Xing, Minjie; Spencer, Ken

    2008-01-01

    A Web-based learning environment has been developed to support students from China who are studying in the UK and are confronted by many cultural barriers, which may impede their academic studies. The electronic environment incorporates a number of approaches to support learning, ranging from a simple text-based presentation to more active…

  9. Photoelectric effect in surface-barrier structures

    International Nuclear Information System (INIS)

    Kononenko, V.K.; Tupenevich, P.A.

    1985-08-01

    Deviations from the Fowler law were observed when investigating photoelectric emission in p-type ZnTe surface-barrier structures. The revealed peculiarities of the structure photosensitivity spectrum are explained by the electron transitions involving surface states at the metal-semiconductor interface. (author)

  10. Barriers and facilitators to antiretroviral medication adherence ...

    African Journals Online (AJOL)

    Medication adherence is a complex behaviour with multiple determinants. Understanding the barriers and facilitators of adherence is invaluable for programme improvement, which assists the foundation of adherence intervention strategies. A qualitative study was conducted in six selected hospitals of Addis Ababa in 2008, ...

  11. Lifetime Modeling of Thermal Barrier Coatings

    NARCIS (Netherlands)

    Hille, T.S.

    2009-01-01

    Thermal barrier coatings (TBCs) are applied in gas turbines to enhance their thermal efficiency by isolating the metallic components from the aggressive hot gas. TBC lifetime is limited by damage processes originating at internal interfaces, which may ultimately lead to delamination and spallation.

  12. Perception, Knowledge Level and Barriers to Reproductive ...

    African Journals Online (AJOL)

    The study also identified barriers to effective women reproductive health knowledge and behaviour among women. Based on these findings, recommendations were made that information on reproductive health rights of women should be provided and that cultural and traditional religious injunctions should be discouraged.

  13. Telehomecare in The Netherlands: Barriers to implementation

    NARCIS (Netherlands)

    HSM Kort; Joost van Hoof

    2012-01-01

    Telehomecare is one of the technological solutions used by older persons to remain living at home in their own community. A selection of 85 Dutch telehomecare projects was examined in terms of the barriers to their implementation. Three categories of telehomecare technologies were distinguished: (i)

  14. Engineered Barrier System: Physical and Chemical Environment

    International Nuclear Information System (INIS)

    Dixon, P.

    2004-01-01

    The conceptual and predictive models documented in this Engineered Barrier System: Physical and Chemical Environment Model report describe the evolution of the physical and chemical conditions within the waste emplacement drifts of the repository. The modeling approaches and model output data will be used in the total system performance assessment (TSPA-LA) to assess the performance of the engineered barrier system and the waste form. These models evaluate the range of potential water compositions within the emplacement drifts, resulting from the interaction of introduced materials and minerals in dust with water seeping into the drifts and with aqueous solutions forming by deliquescence of dust (as influenced by atmospheric conditions), and from thermal-hydrological-chemical (THC) processes in the drift. These models also consider the uncertainty and variability in water chemistry inside the drift and the compositions of introduced materials within the drift. This report develops and documents a set of process- and abstraction-level models that constitute the engineered barrier system: physical and chemical environment model. Where possible, these models use information directly from other process model reports as input, which promotes integration among process models used for total system performance assessment. Specific tasks and activities of modeling the physical and chemical environment are included in the technical work plan ''Technical Work Plan for: In-Drift Geochemistry Modeling'' (BSC 2004 [DIRS 166519]). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system analysis model reports

  15. Physical Environmental Barriers to School Attendance among ...

    African Journals Online (AJOL)

    attendance among children with disabilities and subsequently the overall inclusive education. Key words: Parents/caregivers, children with disabilities, barriers. Introduction. The prevalence of disability increases as war, conflict, and poverty increase. However, the needs of chil- dren with disabilities in developing countries ...

  16. Identifying Barriers to Study Abroad Program Participation

    Science.gov (United States)

    McKinley, Karen E.

    2014-01-01

    University administrators, industry professionals, and government leaders encourage college students to participate in study abroad programs. Despite an increase in the number of students going abroad, the percentage of students participating in global programs remain low. This study identified barriers to study abroad program participation at a…

  17. Thinly disguised contempt: a barrier to excellence.

    Science.gov (United States)

    Brown-Stewart, P

    1987-04-01

    Many elements in contemporary leadership and management convey contempt for employees. "Thinly disguised contempt," a concept introduced by Peters and Austin in A Passion For Excellence, explains many barriers to the achievement of excellence in corporations across disciplines. Health care executives and managers can learn from the errors of corporate management and avoid replicating these errors in the health care industry.

  18. Green FR Cotton Barrier Nonwovens: Progress Report

    Science.gov (United States)

    This green barrier fabric is unique in sense that it is from a renewable resource, biodegradable, economical, employing greige (unbleached) cotton, thus, increasing its marketability. The recent open-flame standard (effective since July, 2007) for residential mattresses 16 CFR 1633 from CPSC has l...

  19. Flame retardant cotton barrier nonwovens for mattresses

    Science.gov (United States)

    According to regulation CPSC 16 CFR 1633, every new residential mattress sold in the United States since July 2007 must resist ignition by open flame. An environmentally benign “green”, inexpensive way to meet this regulation is to use a low-cost flame retardant (FR) barrier fabric. In this study, a...

  20. 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

  1. Mesoscale Coastal Behavior of a Deltaic Barrier Island: Storm-Driven Evolution and Morphodynamic Feedbacks

    Science.gov (United States)

    Vespremeanu-Stroe, Alfred; Zăinescu, Florin; Tătui, Florin; Preoteasa, Luminişa

    2017-04-01

    Barrier islands and spits are among the most dynamic and vulnerable coastal features. Sacalin formed at the southernmost Danube mouth (Sfântu Gheorghe arm), representing the youngest downdrift island/spit of the Sfântu Gheorghe deltaic lobe, which previously formed several similar downdrift barrier islands during its cyclic pattern of long-term development (1400 BP - present). In this study, we document a 120 yr record of coastal changes that occurred since the emergence of Sacalin Island (1897), following a major flood, occasioned by its development through constant elongation (towards south) and backwards migration. The barrier island/spit is frequently breached in the central part (narrow inlets) and it experiences episodes of large elongation and retreat rates (up to 300 m/year and 60 m/year). Using successive georeferenced maps, satellite images and field measurements, we derived several morphodynamic indices which were analysed in correspondence with the storm climate. The coastal storms temporal variability shows four active intervals (1962-1972, 1975-1977, 1995-1998, 2002-2004) with highly intensive erosional and accretional processes, and three calm periods (1989-1994, 1999-2001, 2005-2015), with a decrease of 40-70 % of the shoreline migration rates. On the other hand, the successive barrier configurations show a distinct evolutionary pattern of its central sector, controlled by the (subaerial) barrier widths. Thus, following an extraordinary high storm (or storm season), the narrower barrier sectors will benefit from a new generation of breach deposition and washover fans. They will further contribute to the reconfiguration of the barrier on a backward position, where it attains significantly larger widths (250-500 m for the subaerial part) which for a while will inhibit the new large overwash formation able to expand the barrier into the lagoon. After such a "widening episode", the time intervals of barrier backline stability (i.e. unaffected by

  2. Fluid Dynamics

    DEFF Research Database (Denmark)

    Brorsen, Michael

    These lecture notes are intended mainly for the 7th semester course "Fluid Dynamics" offered by the Study Committee on Civil Engineering, Aalborg University.......These lecture notes are intended mainly for the 7th semester course "Fluid Dynamics" offered by the Study Committee on Civil Engineering, Aalborg University....

  3. Molecular dynamics

    NARCIS (Netherlands)

    Bergstra, J.A.; Bethke, I.

    2002-01-01

    Molecular dynamics is a model for the structure and meaning of object based programming systems. In molecular dynamics the memory state of a system is modeled as a fluid consisting of a collection of molecules. Each molecule is a collection of atoms with bindings between them. A computation is

  4. Temperature dependence of barrier height in Ni/n-GaN Schottky barrier diode

    Science.gov (United States)

    Maeda, Takuya; Okada, Masaya; Ueno, Masaki; Yamamoto, Yoshiyuki; Kimoto, Tsunenobu; Horita, Masahiro; Suda, Jun

    2017-05-01

    The temperature dependence of barrier height in a Ni/n-GaN Schottky barrier diode fabricated on a GaN homoepitaxial layer was investigated by capacitance-voltage, current-voltage, and internal photoemission measurements in the range of 223-573 K. The barrier height obtained by these methods linearly decreased with increasing temperature. The temperature coefficient was -(1.7-2.3) × 10-4 eV/K, which is about half of the temperature coefficient of the band gap reported previously. This indicates that the decrease in the barrier height may mainly reflect the shrinkage of the band gap (lowering of the conduction band edge) in GaN with increasing temperature.

  5. Multilayer barrier films comprising nitrogen spacers between free-standing barrier layers

    Science.gov (United States)

    Granstrom, Jimmy; Villet, Michael; Chatterjee, Tirtha; Gerbec, Jeffrey A.; Jerkunica, Evan; Roy, Anshuman

    2009-08-01

    An encapsulation architecture for organic electronic devices utilizing nitrogen gas-phase spacers between free-standing barrier films is demonstrated. The nitrogen spacers act as sinks for permeating H2O and O2, delaying establishment of steady-state chemical potential gradients across the barriers and thereby reducing permeation rates. Water vapor transmission through nitrogen-spaced barriers was measured via the calcium optical transmission test. Substantial reductions in permeation rate were observed for a variety of barrier materials and configurations, suggesting a general and cost-effective approach for improving encapsulation performance. A low-cost polyethylene terephthalate film increases the calcium lifetime of a Cytop™-Kureha structure from 7000 to 12000 min.

  6. Adapting to climate change by water management organisations: Enablers and barriers

    Science.gov (United States)

    Azhoni, Adani; Jude, Simon; Holman, Ian

    2018-04-01

    Climate change will be particularly experienced though the medium of water. Water organisations, that are managing societal and ecological needs for water, are therefore likely to experience the impact the most. This study reviews the current literature regarding adaptation to climate change by water management organisations and associated barriers. Literature on adaptive capacity is growing and a general consensus is emerging on the determinants of adaptive capacity, although variations exist regarding how it is to be evaluated, enhanced and applied to policy making due to its dynamic, contextual and latent nature. Since adaptive capacity is hard to measure and successful adaptation difficult to define, some studies focus on the existence of adaptation attributes of organisations. Studies reporting successful adaptation are minimal and barriers of adaptation are being discovered as adaptation research transitions into implementation. But the root causes of these barriers are often overlooked and the interconnectedness of the barriers is poorly addressed. Increasingly, combining top-down and bottom-up approaches to adaptation is being recommended due to the limitations of each. However, knowledge regarding how organisations operating at different scales can enhance adaptive capacity of other organisations operating at another scale is lacking due to the few studies of inter-organisational networks across scales. Social networks among actors are recognised as a key factor to enable adaptation. However, network studies generally focus on individual actors and rarely between public agencies/organisations. Moreover, the current literature is inadequate to understand the relationship between adaptation enabling characteristics, barriers and adaptation manifestation. The review demonstrates that research on understanding the emergence and sustenance of barriers is urgently required. Addressing these knowledge gaps will help to improve the design of adaptation strategies

  7. Differential Rollover Risk in Vehicle-to-Traffic Barrier Collisions

    Science.gov (United States)

    Gabauer, Douglas J.; Gabler, Hampton C.

    2009-01-01

    In the roadside safety community, there has been debate over the influence of vehicle and barrier type on rollover rates in traffic barrier crashes. This study investigated rollover rates between sport utility vehicles (SUVs), pickup trucks, and cars in vehicle-traffic barrier crashes and has examined the effect of barrier type on rollover risk for concrete barrier and metal barrier impacts. The analysis included 955 barrier impact cases that were selected from 11-years of in-depth crash data available through the National Automotive Sampling System (NASS) / Crashworthiness Data System (CDS). In real world tow-away level longitudinal barrier collisions, the most important predictors of vehicle rollover were found to be vehicle type and whether the vehicle was tracking prior to barrier impact. Based on binary logistic regression, SUVs were found to have 8 times the risk of rollover as cars in barrier impacts. Although pickups were found to have an increased risk of rollover compared to cars, the risk was not as pronounced as that found for SUVs. This finding has direct implications for the full scale crash testing of longitudinal barriers as the testing procedures have been predicated on the assumption that the pickup truck provides a critical or worst case impact scenario. In towaway crashes, our study does not support the notion that concrete barriers have a higher risk of vehicle rollover than metal beam barriers. PMID:20184839

  8. Impacts of noise barriers on near-road air quality

    Science.gov (United States)

    Baldauf, R.; Thoma, E.; Khlystov, A.; Isakov, V.; Bowker, G.; Long, T.; Snow, R.

    Numerous health studies conducted worldwide suggest an increase in the occurrence of adverse health effects for populations living, working, or going to school near large roadways. A study was designed to assess traffic emission impacts on air quality near a heavily traveled highway. The portion of highway studied included a section of open field and a section with a noise barrier adjacent to the road. In addition, the section containing the noise barrier included a portion with vegetation in the vicinity of the barrier. Thus, this field study provided an opportunity to evaluate near-road air quality with no barriers, with a noise barrier only, and with a noise barrier and vegetation adjacent to the road. Pollutants measured under these scenarios included carbon monoxide (CO) and particulate matter (PM). Measurements showed the effects of a noise barrier on near-road air quality. The presence of this structure often led to pollutant concentration reductions behind the barrier during meteorological conditions with winds directionally from the road. CO and PM number concentrations generally decreased between 15 and 50% behind the barrier. However, conditions occurred when pollutant concentrations were greater behind the barrier than when no barrier was present. These results imply that the presence of a noise barrier can lead to higher pollutant concentrations on the road during certain wind conditions. In addition, the study results suggested that the presence of mature trees in addition to the barrier further lowered PM number concentrations.

  9. Synthesis and dynamic behaviour of new metallo-based sterically overcrowded alkenes

    NARCIS (Netherlands)

    Smid, WI; Schoevaars, AM; Kruizinga, W; Veldman, N; Smeets, WJJ; Spek, AL; Feringa, BL; Smeets, Wilberth J.J.; Spek, Anthony L.; Feringa, Bernard

    1996-01-01

    The synthesis and crystal and molecular structures of novel metallo-based sterically overcrowded alkenes are reported and dynamic H-1 NMR studies reveals that the isomerization barriers are dramatically increased on metal coordination.

  10. Steric Effects of Solvent Molecules on SN2 Substitution Dynamics.

    Science.gov (United States)

    Liu, Xu; Xie, Jing; Zhang, Jiaxu; Yang, Li; Hase, William L

    2017-04-20

    Influences of solvent molecules on S N 2 reaction dynamics of microsolvated F - (H 2 O) n with CH 3 I, for n = 0-3, are uncovered by direct chemical dynamics simulations. The direct substitution mechanism, which is important without microsolvation, is quenched dramatically upon increasing hydration. The water molecules tend to force reactive encounters to proceed through the prereaction collision complex leading to indirect reaction. In contrast to F - (H 2 O), reaction with higher hydrated ions shows a strong propensity for ion desolvation in the entrance channel, diminishing steric hindrance for nucleophilic attack. Thus, nucleophilic substitution avoids the potential energy barrier with all of the solvent molecules intact and instead occurs through the less solvated barrier, which is energetically unexpected because the former barrier has a lower energy. The work presented here reveals a trade-off between reaction energetics and steric effects, with the latter found to be crucial in understanding how hydration influences microsolvated S N 2 dynamics.

  11. Discrete dynamics versus analytic dynamics

    DEFF Research Database (Denmark)

    Toxværd, Søren

    2014-01-01

    For discrete classical Molecular dynamics obtained by the “Verlet” algorithm (VA) with the time increment h there exists a shadow Hamiltonian H˜ with energy E˜(h) , for which the discrete particle positions lie on the analytic trajectories for H˜ . Here, we proof that there, independent of such a......For discrete classical Molecular dynamics obtained by the “Verlet” algorithm (VA) with the time increment h there exists a shadow Hamiltonian H˜ with energy E˜(h) , for which the discrete particle positions lie on the analytic trajectories for H˜ . Here, we proof that there, independent...... of such an analytic analogy, exists an exact hidden energy invariance E * for VA dynamics. The fact that the discrete VA dynamics has the same invariances as Newtonian dynamics raises the question, which of the formulations that are correct, or alternatively, the most appropriate formulation of classical dynamics....... In this context the relation between the discrete VA dynamics and the (general) discrete dynamics investigated by Lee [Phys. Lett. B122, 217 (1983)] is presented and discussed....

  12. Intrinsic barriers for H-atom transfer reactions involving hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Camaioni, D.M.; Autrey, S.T.; Franz, J.A.

    1994-08-01

    Intrinsic barriers (formally the barrier in the absence of driving force) for H-atom transfer reactions are key parameters in Evans-Polyanyi and Marcus equations for estimating exothermic reaction barriers and are fundamentally significant for the insight they provide about bond reorganization energies for formation of transition state structures. Although knowable from experiment, relatively few of these barriers have been measured due to experimental difficulties in measuring rates for identity reactions. Thus, the authors have used semiempirical Molecular Orbital theoretical methods (MNDO/PM3) to calculate barriers for a series of H-atom transfer identity reactions involving alkyl, alkenyl, arylalkyl and hydroaryl radicals and donors. Briefly stated, they find that barriers decrease with the degree of alkyl substitution at the radical site whereas barriers increase with the degree of conjugation with the radical site. Details of the methodology and analyses of how these barrier heights correlate with reactant and transition state properties will be presented and discussed.

  13. Energy analysis of vehicle-to-cable barrier impacts.

    Science.gov (United States)

    2013-06-01

    An accident reconstruction technique was developed for estimating the energy absorbed during an impact with a cable barrier system as well as the initial impact velocity. The kinetic energy absorbed during a cable barrier system impact is comprised o...

  14. Overcoming Barriers to Wind Development in Appalachian Coal Country

    Energy Technology Data Exchange (ETDEWEB)

    Brent Bailey; Evan Hansen

    2012-10-09

    This research project synthesizes existing data and communication from experts to assess barriers to wind development in Pennsylvania, Maryland, West Virginia, Virginia, and Kentucky, and makes recommendations where feasible to reduce or eliminate those barriers.

  15. 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

  16. Improved Barriers to Turbine Engine Fragments: Final Annual Report

    National Research Council Canada - National Science Library

    Shockey, Donald

    2002-01-01

    .... Previous large-scale fragment impact testing of comer peg-mounted fabric barriers indicated that the failure of the fabric around the pegged hole was a significant factor in the barrier's effectiveness...

  17. Can probiotics modulate human disease by impacting intestinal barrier function?

    NARCIS (Netherlands)

    Bron, Peter A.; Kleerebezem, Michiel; Brummer, Robert Jan; Cani, Patrice D.; Mercenier, Annick; MacDonald, Thomas T.; Garcia-Ródenas, Clara L.; Wells, Jerry M.

    2017-01-01

    Intestinal barrier integrity is a prerequisite for homeostasis of mucosal function, which is balanced to maximise absorptive capacity, while maintaining efficient defensive reactions against chemical and microbial challenges. Evidence is mounting that disruption of epithelial barrier integrity is

  18. 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.

  19. Theoretical Compartment Modeling of DCE-MRI Data Based on the Transport across Physiological Barriers in the Brain

    Directory of Open Access Journals (Sweden)

    Laura Fanea

    2012-01-01

    Full Text Available Neurological disorders represent major causes of lost years of healthy life and mortality worldwide. Development of their quantitative interdisciplinary in vivo evaluation is required. Compartment modeling (CM of brain data acquired in vivo using magnetic resonance imaging techniques with clinically available contrast agents can be performed to quantitatively assess brain perfusion. Transport of 1H spins in water molecules across physiological compartmental brain barriers in three different pools was mathematically modeled and theoretically evaluated in this paper and the corresponding theoretical compartment modeling of dynamic contrast enhanced magnetic resonance imaging (DCE-MRI data was analyzed. The pools considered were blood, tissue, and cerebrospinal fluid (CSF. The blood and CSF data were mathematically modeled assuming continuous flow of the 1H spins in these pools. Tissue data was modeled using three CMs. Results in this paper show that transport across physiological brain barriers such as the blood to brain barrier, the extracellular space to the intracellular space barrier, or the blood to CSF barrier can be evaluated quantitatively. Statistical evaluations of this quantitative information may be performed to assess tissue perfusion, barriers' integrity, and CSF flow in vivo in the normal or disease-affected brain or to assess response to therapy.

  20. In pursuit of resilient, low carbon communities: An examination of barriers to action in three Canadian cities

    International Nuclear Information System (INIS)

    Burch, Sarah

    2010-01-01

    This article presents the findings of a study that examined three municipalities in the Lower Mainland of British Columbia, Canada, in order to determine the nature of the socio-cultural and institutional barriers to action on climate change at the local level. The central goals of this paper are: (1) to propose a simple typology of institutional and socio-cultural barriers to action by gathering insights from an inter-disciplinary set of literatures; (2) to explore the ways that these barriers influence the utilization of various forms of capacity to achieve greenhouse gas reduction and resiliency in three case study communities; and (3) to understand the dynamic interactions amongst, and relative importance of, these barriers at the local level. The evidence presented in this paper indicates that barriers are deeply interwoven phenomena, which may reinforce one another and create substantial inertia behind unsustainable patterns of municipal operations. Nevertheless, the same factors that can inhibit action on climate change (such as an organizational culture of combativeness or mutual disrespect) can also facilitate it (as with a culture of collaboration or innovation). This article suggests that a deeper understanding of the ways in which barriers can be transformed into enablers of action is a critical next step in the evolution climate change policy design and implementation at the local level.

  1. Galactic dynamics

    CERN Document Server

    Binney, James

    2008-01-01

    Since it was first published in 1987, Galactic Dynamics has become the most widely used advanced textbook on the structure and dynamics of galaxies and one of the most cited references in astrophysics. Now, in this extensively revised and updated edition, James Binney and Scott Tremaine describe the dramatic recent advances in this subject, making Galactic Dynamics the most authoritative introduction to galactic astrophysics available to advanced undergraduate students, graduate students, and researchers. Every part of the book has been thoroughly overhauled, and many section

  2. Prototype Engineered Barrier System Field Tests

    International Nuclear Information System (INIS)

    Ramirez, A.L.; Beatty, J.; Buscheck, T.A.

    1989-01-01

    This paper presents selected preliminary results obtained during the first 54 days of the Prototype Engineered Barrier System Field Tests (PEBSFT) that are being performed in G-Tunnel within the Nevada Test Site. The test described is a precursor to the Engineered Barrier Systems Field Tests (EBSFT). The EBSFT will consist of in situ tests of the geohydrologic and geochemical environment in the near field (within a few meters) of heaters emplaced in welded tuff to simulate the thermal effects of waste packages. The PEBSFTs are being conducted to evaluate the applicability of measurement techniques, numerical models, and procedures for future investigations that will be conducted in the Exploratory Shaft Facilities of the Yucca Mountain Project (YMP). The paper discusses the evolution of hydrothermal behavior during the prototype test, including rock temperatures, changes in rock moisture content, air permeability of fractures, gas pressures, and rock mass gas-phase humidity. 10 refs., 12 figs

  3. Nuclear reactor vessel fuel thermal insulating barrier

    Energy Technology Data Exchange (ETDEWEB)

    Keegan, C. Patrick; Scobel, James H.; Wright, Richard F.

    2013-03-19

    The reactor vessel of a nuclear reactor installation which is suspended from the cold leg nozzles in a reactor cavity is provided with a lower thermal insulating barrier spaced from the reactor vessel that has a hemispherical lower section that increases in volume from the center line of the reactor to the outer extent of the diameter of the thermal insulating barrier and smoothly transitions up the side walls of the vessel. The space between the thermal insulating harrier and the reactor vessel forms a chamber which can be flooded with cooling water through passive valving to directly cool the reactor vessel in the event of a severe accident. The passive inlet valve for the cooling water includes a buoyant door that is normally maintained sealed under its own weight and floats open when the cavity is Hooded. Passively opening steam vents are also provided.

  4. Decoherence in high barrier quantum cascade structures

    Science.gov (United States)

    Freeman, Will

    2017-07-01

    High barrier AlxGa1-xAs terahertz quantum cascade structures with AlAs compositions up to 30% are studied. The influence of thermally excited leakage scattering to higher bound energy states and decoherence effects are investigated using a density matrix method where the pure dephasing time is self-consistently solved. The lattice temperature dependence of the light output in diagonal optical transition structures is calculated and shown to be consistent with experiment. Scattering from the upper lasing state to higher bound energy states is found to have minimal effects, and rather the decoherence from the calculated reduction of the pure dephasing time due to the impurity interaction is primarily responsible for the temperature dependence of a recently reported structure. This shows that the effects from an increased impurity interaction due to thinner barriers and different well dimensions can dominate over that from the increased interface roughness interaction due to higher potentials.

  5. Decreasing barriers for nurse practitioner social entrepreneurship.

    Science.gov (United States)

    Sharp, Dayle B; Monsivais, Diane

    2014-10-01

    To describe difficulties associated with the business-related aspects of practice in role transition of rural nurse practitioners (NPs), and to give practice implications. This focused ethnographic study derived data from semi-structured interviews. Participants provided information about rural NP practice ownership and barriers. The sample consisted of 24 rural NPs living throughout the United States. The majority were 51-60 years of age (45%) and females (93%) who had been in rural practice for 1 to over 20 years. NP social entrepreneurs experience difficulties related to scope of practice, business skills, and role conflict. To decrease barriers for NP clinic ownership and management, NPs need to receive education related to financing a rural practice, legal/regulatory practices, strategic planning, leadership, and clinic management. ©2014 American Association of Nurse Practitioners.

  6. Markers for blood-brain barrier integrity

    DEFF Research Database (Denmark)

    Saunders, Norman R; Dziegielewska, Katarzyna M; Møllgård, Kjeld

    2015-01-01

    In recent years there has been a resurgence of interest in brain barriers and various roles their intrinsic mechanisms may play in neurological disorders. Such studies require suitable models and markers to demonstrate integrity and functional changes at the interfaces between blood, brain...... known when first introduced, but seem to have been forgotten since. Understanding these limitations is important because Evans blue is still the most commonly used marker of brain barrier integrity and those using it seem oblivious to problems arising from its in vivo application. The introduction...... of HRP in the mid twentieth-century was an important advance because its reaction product can be visualized at the electron microscopical level, but it also has limitations. Advantages and disadvantages of these markers will be discussed together with a critical evaluation of alternative approaches...

  7. On the repair of the dentine barrier.

    Science.gov (United States)

    Fransson, Helena

    2012-01-01

    The overall aim of this thesis was to study some aspects of the repair of the dentine barrier, especially in conjunction with dental pulp capping. Understanding the events leading to the healing of the dentine and pulp, and hence successfully preserving the vitality and functions of the tooth, would lead to a scientific basis for a less invasive treatment of pulp exposures than performing root canal treatments. The surfaces of the body have physiological barrier functions aimed at protecting the body from external noxious agents. In the tooth, the odontoblasts, which line the outermost part of the pulp and are responsible for the formation of dentine, play a central role in the barrier function and thus in the defence mechanisms of the tooth. The micro-organisms in the caries lesion can reach the pulp via the dentinal tubules. However, the barrier function helps to prevent microbial invasion and thereby avoid deleterious inflammation and subsequent necrosis of the pulp. Dentine repair is an important part of the barrier function. There are however doubts as to whether the repair also leads to restitution of the function and the ability to withstand bacterial influx over the longer term. Pulp capping is a treatment method used when the pulp has been exposed in order to stimulate healing of the pulp and dentine. The evidence for repair of the dentine after pulp capping in humans has been studied by means of a systematic review. The focus of the literature search was studies performed in humans where hard tissue formation had been studied with the aid of a microscope. We concluded, based on the limited evidence available, that calcium hydroxide based materials but not bonding agents promote formation of a hard tissue bridge. Scientific evidence was lacking as to whether MTA was better than calcium hydroxide based materials in this regard. A gel (Emdogain Gel) containing amelogenin, known to be involved in dentinogenesis, was evaluated with regard to formation of hard

  8. Mass asymmetric fission barriers for 75Br

    Science.gov (United States)

    Delis, D. N.; Blumenfeld, Y.; Bowman, D. R.; Colonna, N.; Hanold, K.; Jing, K.; Justice, M.; Meng, J. C.; Peaslee, G. F.; Wozniak, G. J.; Moretto, L. G.

    1991-11-01

    Fragments with atomic numbers covering nearly the entire range of the mass-asymmetry coordinate (4 < Z < 27) were observed from the 5.0, 6.2, 6.9, 8.0, 10.2 and 12.7 MeV/A 63Cu + 12C reactions. Energy spectra and angular distributions show the presence of projectile-like and target-like components along with an isotropic component. The isotropic component appears as a Coulomb ring in the invariant cross-section plots indicating the presence of a binary compound nucleus decay which is confirmed by the coincidence data. Excitation functions were constructed for each Z value and a nearly complete set of mass-asymmetric barriers has been extracted for 75Br. There is excellent agreement between the experimentally determined barriers and the finite-range model predictions.

  9. Streptococcus pyogenes translocates across an epithelial barrier.

    Science.gov (United States)

    Sumitomo, Tomoko

    2017-01-01

    Streptococcus pyogenes is a β-hemolytic organism responsible for a wide variety of human diseases that commonly occur as self-limiting purulent diseases of the pharynx and skin. Although the occurrence of invasive infections by S. pyogenes is rare, mortality rates remain high even with progressive medical therapy. As a prerequisite for causing the severe invasive disease, S. pyogenes must invade underlying sterile tissues by translocating across the epithelial barrier. In this study, streptolysin S and SpeB were identified as the novel factors that facilitate bacterial translocation via degradation of intercellular junctions. Furthermore, we found that S. pyogenes exploits host plasminogen for acceleration of bacterial invasion into deeper tissues via tricellular tight junctions. Here, I would like to show our study on bacterial translocation across the epithelial barrier through paracellular route.

  10. Renewable energy costs, potentials, barriers: Conceptual issues

    International Nuclear Information System (INIS)

    Verbruggen, Aviel; Fischedick, Manfred; Moomaw, William; Weir, Tony; Nadai, Alain; Nilsson, Lars J.; Nyboer, John; Sathaye, Jayant

    2010-01-01

    Renewable energy can become the major energy supply option in low-carbon energy economies. Disruptive transformations in all energy systems are necessary for tapping widely available renewable energy resources. Organizing the energy transition from non-sustainable to renewable energy is often described as the major challenge of the first half of the 21st century. Technological innovation, the economy (costs and prices) and policies have to be aligned to achieve full renewable energy potentials, and barriers impeding that growth need to be removed. These issues are also covered by IPCC's special report on renewable energy and climate change to be completed in 2010. This article focuses on the interrelations among the drivers. It clarifies definitions of costs and prices, and of barriers. After reviewing how the third and fourth assessment reports of IPCC cover mitigation potentials and commenting on definitions of renewable energy potentials in the literature, we propose a consistent set of potentials of renewable energy supplies.

  11. The inner CSF-brain barrier

    DEFF Research Database (Denmark)

    Whish, Sophie; Dziegielewska, Katarzyna M; Møllgård, Kjeld

    2015-01-01

    consisting of neuroepithelial cells and later radial glial cells, is characterized by "strap" junctions, which limit the exchange of different sized molecules between cerebrospinal fluid and the brain parenchyma. Here we provide a systematic study of permeability properties of this inner cerebrospinal fluid-brain...... barrier during mouse development from embryonic day, E17 until adult. Results show that at fetal stages exchange across this barrier is restricted to the smallest molecules (286Da) and the diffusional restraint is progressively removed as the brain develops. By postnatal day P20, molecules the size......In the adult the interface between the cerebrospinal fluid and the brain is lined by the ependymal cells, which are joined by gap junctions. These intercellular connections do not provide a diffusional restrain between the two compartments. However, during development this interface, initially...

  12. NATURAL BARRIERS TARGETED THRUST FY 2004 PROJECTS

    International Nuclear Information System (INIS)

    NA

    2005-01-01

    This booklet contains project descriptions of work performed by the Department of Energy (DOE), Office of Civilian Radioactive Waste Management (OCRWM), Office of Science and Technology and International's (OSTandI) Natural Barriers Targeted Thrust during Fiscal Year (FY) 2004. The Natural Barriers Targeted Thrust is part of OSTandI's Science and Technology Program which supports the OCRWM mission to manage and dispose of high-level radioactive waste and spent nuclear fuel in a manner that protects health, safety, and the environment; enhances national and energy security; and merits public confidence. In general, the projects described will continue beyond FY 2004 assuming that the technical work remains relevant to the proposed Yucca Mountain Repository and sufficient funding is made available to the Science and Technology Program

  13. Infiltration barrier demonstration at Maxey Flats, Kentucky

    International Nuclear Information System (INIS)

    Mills, D.; Razor, J.

    1983-01-01

    At the 1982 DOE LLWMP meeting, the Kentucky Natural Resources and Environmental Protection Cabinet presented a history of the Maxey Flats Waste Disposal Facility, its status, and current Commonwealth activities leading toward stabilization and decommissioning. Information was presented at that time on the purpose of the DOE Trench Moisture Barrier Demonstration Grant and the early phases of construction and implementation. In this paper, final construction and implementation of the trench moisture barrier demonstration are discussed. Data including trench water level measurements, lateral liquid flow in experimental sections, and soil moisture measurements are presented and discussed. The Paper is completed with a brief discussion of remediation activities currently being implemented at Maxey Flats. 9 references, 7 figures, 1 table

  14. NATURAL BARRIERS TARGETED THRUST FY 2004 PROJECTS

    Energy Technology Data Exchange (ETDEWEB)

    NA

    2005-07-27

    This booklet contains project descriptions of work performed by the Department of Energy (DOE), Office of Civilian Radioactive Waste Management (OCRWM), Office of Science and Technology and International's (OST&I) Natural Barriers Targeted Thrust during Fiscal Year (FY) 2004. The Natural Barriers Targeted Thrust is part of OST&I's Science and Technology Program which supports the OCRWM mission to manage and dispose of high-level radioactive waste and spent nuclear fuel in a manner that protects health, safety, and the environment; enhances national and energy security; and merits public confidence. In general, the projects described will continue beyond FY 2004 assuming that the technical work remains relevant to the proposed Yucca Mountain Repository and sufficient funding is made available to the Science and Technology Program.

  15. Skin Barrier Dysfunction and the Atopic March

    DEFF Research Database (Denmark)

    Clausen, Maja-Lisa; Agner, Tove; Thomsen, Simon Francis

    2015-01-01

    The atopic diseases: atopic dermatitis, asthma and allergic rhinoconjunctivitis are frequent diseases in the population occurring sequentially in the young (the atopic march).The discovery of filaggrin gene (FLG) mutations and impairments in the skin barrier as predisposing factors for atopic...... dermatitis and subsequent asthma and atopic sensitization in the context of eczema has improved our understanding of the atopic march. The atopic diseases can now be viewed upon as causally related conditions—rather than sequentially occurring manifestations of the same underlying atopic disease state......—with atopic dermatitis and FLG mutations being a prerequisite for the development of the other atopic diseases, particularly asthma. This review discusses the role of the skin barrier function, particularly the role of FLG mutations, in the atopic march....

  16. On the existence of compositional barrier certificates

    DEFF Research Database (Denmark)

    Sloth, Christoffer; Wisniewski, Rafael; Pappas, George J.

    2012-01-01

    This paper provides a necessary and sufficient condition for the compositional verification of a continuous system with additively separable barrier functions. The compositional safety verification enables the verification of an interconnection of subsystems. The idea behind the compositional...... analysis is to allow the verification of systems with a high dimension, by the verification of multiple lower dimensional subproblems. In the compositional safety analysis, a particular structure is imposed on the barrier certificate, restricting the applicability of the method. We show an example...... of a system that cannot be verified using the compositional method, but can be verified using a centralized method. This example highlights how not to decompose systems, and should be used to guide the decomposition of a system into appropriate subsystems. Finally, we provide a second condition...

  17. Investing in Energy Efficiency. Removing the Barriers

    International Nuclear Information System (INIS)

    2004-01-01

    Investing in improving energy efficiency has the clear advantages of reducing energy costs, improving security of supply and mitigating the environmental impacts of energy use. And still, many viable opportunities for higher energy efficiency are not tapped because of the existence of numerous barriers to such investments. These lost opportunities imply costs to the individual energy consumers and to the society as a whole and they are particularly important in economies in transition. This report identifies various types of barriers for making energy efficiency investments (be they of legal, administrative, institutional or financial nature), mainly in buildings, district heating and efficient lighting. The role of various bodies and organisations for the facilitation of energy efficiency investments is analysed, from public authorities and regulators to banks and international financing institutions

  18. Evaluation and analysis of barriers to the innovation activity in the economy of the region

    Directory of Open Access Journals (Sweden)

    D. A. Tomasova

    2017-01-01

    Full Text Available Prospects for the development of the Russian innovative economy largely depend on the successful overcoming of negative factors impeding the effective interaction of institutions in the field of education, science, business, credit and fi nancial sphere regarding the creation, transfer and commercialization of innovations. Deep evaluation of innovative problems needs dynamic analysis of main processes in the spheres accompanying the innovation activity, which determines the topicality of this article. The aim of research consists in elaborating a dynamic approach to complex estimation of problems and barriers to the innovative development of Russia, including their structure and change. In order to do that, this article reviews the main barriers to the development of innovation activity in the region, builds a detailed classifi cation of parameters of innovative economic environment, and analyses their dynamics. The algorithm of innovation barriers assessment is based on economic statistics methods and fuzzy sets theory. This algorithm is determined on the basis of linguistic variables according to the matrix principle and linguistic identifi cation of economic objects. The estimation is based on a dynamic approach, that is, each analyzed indicator represents a rate of growth of one or another factor associated with the level of barriers to the innovation activity and therefore reflects the degree of reduction or strengthening in such barrier for the period under review. The minimax normalization allows providing comparability of all indicators under review. Macroeconomic data and indices of Russian enterprises operation, presented in statistical collections were used as the input data for analysis and estimation. As a result, we evaluated the level of overcoming barriers to innovative development during the past three years on the basis of analyzing research human potential, of development of innovative infrastructure

  19. How to break the barriers to climate awareness

    DEFF Research Database (Denmark)

    Kemp, Peter

    2016-01-01

    In this paper is provided a philosophical analysis of the cognitive barriers that may block the individual citizen’s acknowledgement of a personal responsibility to engage in climate responsible behaviour. The authors distinguish between two types of cognitive barriers; the physical barriers......, that are associated with the way we gain knowledge about climate change and the physical world state; and the psychological barriers, that arise from ideas about ourselves and the nature that surrounds us....

  20. Social Barriers to Effective Communication in Old Age

    OpenAIRE

    Anna Sanecka

    2014-01-01

    Some communication barriers apply particularly to elderly people. The social barriers to effective communication in old age are the barriers caused by stereotypes of old age/elderly people and the barriers arising from limitations in using mass communication by seniors. Stereotypes of old age/elderly people embrace views regarding old people’s communication skills and the ideas about the correct way of communication with them. Therefore the communication problems of old people are correlated ...

  1. Blood-brain barrier permeability imaging using perfusion computed tomography

    Directory of Open Access Journals (Sweden)

    Avsenik Jernej

    2015-06-01

    Full Text Available Background. The blood-brain barrier represents the selective diffusion barrier at the level of the cerebral microvascular endothelium. Other functions of blood-brain barrier include transport, signaling and osmoregulation. Endothelial cells interact with surrounding astrocytes, pericytes and neurons. These interactions are crucial to the development, structural integrity and function of the cerebral microvascular endothelium. Dysfunctional blood-brain barrier has been associated with pathologies such as acute stroke, tumors, inflammatory and neurodegenerative diseases.

  2. Piezotronically modified double Schottky barriers in ZnO varistors.

    Science.gov (United States)

    Raidl, Nadine; Supancic, Peter; Danzer, Robert; Hofstätter, Michael

    2015-03-25

    Double Schottky barriers in ZnO are modified piezotronically by the application of mechanical stresses. New effects such as the enhancement of the potential barrier height and the increase or decrease of the natural barrier asymmetry are presented. Also, an extended model for the piezotronic modification of double Schottky barriers is given. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Plastic Schottky-barrier solar cells

    Science.gov (United States)

    Waldrop, J.R.; Cohen, M.J.

    1981-12-30

    A photovoltaic cell structure is fabricated from an active medium including an undoped polyacetylene, organic semiconductor. When a film of such material is in rectifying contact with a metallic area electrode, a Schottky-barrier junction is obtained within the body of the cell structure. Also, a gold overlayer passivates a magnesium layer on the undoped polyacetylene film. With the proper selection and location of elements a photovoltaic cell structure and solar cell are obtained.

  4. [Barriers to communication between clinicians and immigrants].

    Science.gov (United States)

    Sodemann, Morten; Kristensen, Trine Rønde; Sångren, Henrik; Nielsen, Dorthe

    2015-08-24

    Clinicians lack cultural competencies and communication skills relevant to clinical decision-making in cases of language and cultural barriers. Life course perspectives and basic understanding of life in exile are not integrated in diagnostics, treatment or follow-up resulting in low patient compliance, mistrust, complications, diagnostic errors and delays. Stereotyping and generalizations put patients in a position where they are forced to protect themselves by withholding important information. When in doubt clinicians should ask, listen and avoid guessing.

  5. Thermal barrier coating resistant to sintering

    Science.gov (United States)

    Subramanian, Ramesh; Seth, Brij B.

    2004-06-29

    A device (10) is made, having a ceramic thermal barrier coating layer (16) characterized by a microstructure having gaps (18) with a sintering inhibiting material (22) disposed on the columns (20) within the gaps (18). The sintering resistant material (22) is stable over the range of operating temperatures of the device (10), is not soluble with the underlying ceramic layer (16) and is applied by a process that is not an electron beam physical vapor deposition process.

  6. Collective spectra along the fission barrier

    OpenAIRE

    Pigni M. T.; Andreev A. V.; Shneidman T. M.; Massimi C.; Vannini G.; Ventura A.

    2012-01-01

    Discrete and continuous spectra of fissioning nuclei at the humps of fission barriers (Bohr transition states) and in the intermediate wells (superdeformed and hyperdeformed states) play a key role in the calculation of fission cross sections. A theoretical evaluation of the collective parts of the spectra is possible within the framework of the dinuclear system model, which treats the wave function of the fissioning nucleus as a superposition of a mononucleus configuration and two–cluster co...

  7. GaN nanowire Schottky barrier diodes

    OpenAIRE

    Sabui, Gourab; Zubialevich, Vitaly Z.; White, Mary; Pampili, Pietro; Parbrook, Peter J.; McLaren, Mathew; Arredondo-Arechavala, Miryam; Shen, Z. John

    2017-01-01

    A new concept of vertical gallium nitride (GaN) Schottky barrier diode based on nanowire (NW) structures and the principle of dielectric REduced SURface Field (RESURF) is proposed in this paper. High-threading dislocation density in GaN epitaxy grown on foreign substrates has hindered the development and commercialization of vertical GaN power devices. The proposed NW structure, previously explored for LEDs offers an opportunity to reduce defect density and fabricate low cost vertical GaN pow...

  8. There are many barriers to species' migrations

    Directory of Open Access Journals (Sweden)

    Kenneth J Feeley

    2014-06-01

    Full Text Available Temperature-change trajectories are being used to identify the geographic barriers and thermal ‘cul-de-sacs’ that will limit the ability of many species to track climate change by migrating. We argue that there are many other potential barriers to species’ migrations. These include stable ecotones, discordant shifts in climatic variables, human land use, and species’ limited dispersal abilities. To illustrate our argument, for each 0.5° latitude/longitude grid cell of the Earth’s land surface, we mapped and tallied the number of cells for which future (2060–2080 climate represents an analog of the focal cell’s current climate. We compared results when only considering temperature with those for which both temperature and total annual precipitation were considered in concert. We also compared results when accounting for only geographic barriers (no cross-continental migration with those involving both geographic and potential ecological barriers (no cross-biome migration. As expected, the number of future climate analogs available to each pixel decreased markedly with each added layer of complexity (e.g. the proportion of the Earth’s land surface without any available future climate analogs increased from 3% to more than 36% with the inclusion of precipitation and ecological boundaries. While including additional variables can increase model complexity and uncertainty, we must strive to incorporate the factors that we know will limit species’ ranges and migrations if we hope to predict the effects of climate change at a high-enough degree of accuracy to guide management decisions.

  9. Market Opportunities and Barriers for Smart Buildings

    DEFF Research Database (Denmark)

    Ma, Zheng; Badi, Adrian; Jørgensen, Bo Nørregaard

    2016-01-01

    Buildings consume up to 42% of the global electricity and the primary emitter of greenhouse gas on the planet. Building efficiency is the largest growing segment in the US, the estimated global revenue by the building efficiency sector is around 210 million dollars, and constantly increases since....... Meanwhile, the result shows that the barriers can be eased or solved by open collaboration, information and risk sharing, and self-investment, etc. this paper also categorizes nine influential factors with discussions....

  10. Reconsolidated Salt as a Geotechnical Barrier

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, Francis D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gadbury, Casey [USDOE Carlsbad Field Office, NM (United States)

    2015-11-01

    Salt as a geologic medium has several attributes favorable to long-term isolation of waste placed in mined openings. Salt formations are largely impermeable and induced fractures heal as stress returns to equilibrium. Permanent isolation also depends upon the ability to construct geotechnical barriers that achieve nearly the same high-performance characteristics attributed to the native salt formation. Salt repository seal concepts often include elements of reconstituted granular salt. As a specific case in point, the Waste Isolation Pilot Plant recently received regulatory approval to change the disposal panel closure design from an engineered barrier constructed of a salt-based concrete to one that employs simple run-of-mine salt and temporary bulkheads for isolation from ventilation. The Waste Isolation Pilot Plant is a radioactive waste disposal repository for defense-related transuranic elements mined from the Permian evaporite salt beds in southeast New Mexico. Its approved shaft seal design incorporates barrier components comprising salt-based concrete, bentonite, and substantial depths of crushed salt compacted to enhance reconsolidation. This paper will focus on crushed salt behavior when applied as drift closures to isolate disposal rooms during operations. Scientific aspects of salt reconsolidation have been studied extensively. The technical basis for geotechnical barrier performance has been strengthened by recent experimental findings and analogue comparisons. The panel closure change was accompanied by recognition that granular salt will return to a physical state similar to the halite surrounding it. Use of run-of-mine salt ensures physical and chemical compatibility with the repository environment and simplifies ongoing disposal operations. Our current knowledge and expected outcome of research can be assimilated with lessons learned to put forward designs and operational concepts for the next generation of salt repositories. Mined salt

  11. Lifetime Modeling of Thermal Barrier Coatings

    OpenAIRE

    Hille, T.S.

    2009-01-01

    Thermal barrier coatings (TBCs) are applied in gas turbines to enhance their thermal efficiency by isolating the metallic components from the aggressive hot gas. TBC lifetime is limited by damage processes originating at internal interfaces, which may ultimately lead to delamination and spallation. In the present thesis constitutive models are presented for the coating components and the most detrimental failure mechanisms. To simulate the thermomechanical failure response, the numerical mode...

  12. Reconsolidated Salt as a Geotechnical Barrier

    International Nuclear Information System (INIS)

    Hansen, Francis D.; Gadbury, Casey

    2015-01-01

    Salt as a geologic medium has several attributes favorable to long-term isolation of waste placed in mined openings. Salt formations are largely impermeable and induced fractures heal as stress returns to equilibrium. Permanent isolation also depends upon the ability to construct geotechnical barriers that achieve nearly the same high-performance characteristics attributed to the native salt formation. Salt repository seal concepts often include elements of reconstituted granular salt. As a specific case in point, the Waste Isolation Pilot Plant recently received regulatory approval to change the disposal panel closure design from an engineered barrier constructed of a salt-based concrete to one that employs simple run-of-mine salt and temporary bulkheads for isolation from ventilation. The Waste Isolation Pilot Plant is a radioactive waste disposal repository for defense-related transuranic elements mined from the Permian evaporite salt beds in southeast New Mexico. Its approved shaft seal design incorporates barrier components comprising salt-based concrete, bentonite, and substantial depths of crushed salt compacted to enhance reconsolidation. This paper will focus on crushed salt behavior when applied as drift closures to isolate disposal rooms during operations. Scientific aspects of salt reconsolidation have been studied extensively. The technical basis for geotechnical barrier performance has been strengthened by recent experimental findings and analogue comparisons. The panel closure change was accompanied by recognition that granular salt will return to a physical state similar to the halite surrounding it. Use of run-of-mine salt ensures physical and chemical compatibility with the repository environment and simplifies ongoing disposal operations. Our current knowledge and expected outcome of research can be assimilated with lessons learned to put forward designs and operational concepts for the next generation of salt repositories. Mined salt

  13. Barriers to Clinical Research in Latin America

    OpenAIRE

    Chomsky-Higgins, Kathryn; Miclau, Theodore A.; Mackechnie, Madeline C.; Aguilar, Dino; Avila, Jorge Rubio; dos Reis, Fernando Baldy; Balmaseda, Roberto; Barquet, Antonio; Ceballos, Alfredo; Contreras, Fernando; Escalante, Igor; Elias, Nelson; Vincenti, Sergio Iriarte; Lozano, Christian; Medina, Fryda

    2017-01-01

    Enhancing health research capacity in developing countries is a global health priority. Understanding the orthopedic burden of disease in Latin America will require close partnership between more-developed and less-developed countries. To this end, the Osteosynthesis and Trauma Care Foundation assembled a research consortium of Latin-American orthopedic leaders. Prior to the meeting, we surveyed attendees on perceived barriers to conducting research at their institutions. During the event, wo...

  14. Barrier for Continuous-Crystal-Growth Crucible

    Science.gov (United States)

    Skutch, M. E.; Piotrowski, P. A.

    1983-01-01

    Properly designed openings permit free flow of melt while restraining pellets. Redesigned partition between growth region and melt-replenishment region of crystal-growth crucible makes it less likely crucible will run out of feed material in middle of cycle. Supply of molten silicon is maintained by addition of silicon pellets to compartment at one end of heated crucible, and partition or barrier is required to hold pellets while allowing melted silicon to flow from compartment.

  15. Thermoplastic Starch: Improving their Barrier Properties

    OpenAIRE

    ORTEGA-TORO, RODRIGO; Collazo-Bigliardi, Sofia; Talens Oliag, Pau; Chiralt Boix, Mª Amparo

    2016-01-01

    [EN] There are several strategies for improving functional properties of starch based materials. Blending with more hydrophobic compounds and bilayer formation are the most common methods. Barrier properties of several formulations obtained by different processing methods were measured. The properties of some obtained materials were compared with those usually employed in food packaging. The most promising materials were those starch PCL blends, compatibilized with grafted poly(ε-caprolactone...

  16. Engineered Barrier System: Physical and Chemical Environment

    Energy Technology Data Exchange (ETDEWEB)

    P. Dixon

    2004-04-26

    The conceptual and predictive models documented in this Engineered Barrier System: Physical and Chemical Environment Model report describe the evolution of the physical and chemical conditions within the waste emplacement drifts of the repository. The modeling approaches and model output data will be used in the total system performance assessment (TSPA-LA) to assess the performance of the engineered barrier system and the waste form. These models evaluate the range of potential water compositions within the emplacement drifts, resulting from the interaction of introduced materials and minerals in dust with water seeping into the drifts and with aqueous solutions forming by deliquescence of dust (as influenced by atmospheric conditions), and from thermal-hydrological-chemical (THC) processes in the drift. These models also consider the uncertainty and variability in water chemistry inside the drift and the compositions of introduced materials within the drift. This report develops and documents a set of process- and abstraction-level models that constitute the engineered barrier system: physical and chemical environment model. Where possible, these models use information directly from other process model reports as input, which promotes integration among process models used for total system performance assessment. Specific tasks and activities of modeling the physical and chemical environment are included in the technical work plan ''Technical Work Plan for: In-Drift Geochemistry Modeling'' (BSC 2004 [DIRS 166519]). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system analysis model reports.

  17. Macroscopic quantum tunneling of a Bose-Einstein condensate through double Gaussian barriers

    Science.gov (United States)

    Maeda, Kenji; Urban, Gregor; Weidemüller, Matthias; Carr, Lincoln D.

    2015-05-01

    Macroscopic quantum tunneling is one of the great manifestations of quantum physics, not only showing passage through a potential barrier but also emerging in a many-body wave function. We study a quasi-1D Bose-Einstein condensate of Lithium, confined by two Gaussian barriers, and show that in an experimentally realistic potential tens of thousands of atoms tunnel on time scales of 10 to 100 ms. Using a combination of variational and WKB approximations based on the Gross-Pitaevskii or nonlinear Schrödinger equation, we show that many unusual tunneling features appear due to the nonlinearity, including the number of trapped atoms exhibiting non-exponential decay, severe distortion of the barriers by the mean field, and even formation of a triple barrier in certain regimes. In the first 10ms, nonlinear many-body effects make the tunneling rates significantly larger than background loss rates, from 10 to 70 Hz. Thus we conclude that macroscopic quantum tunneling can be observed on experimental time scales. Funded by NSF, AFOSR, the Alexander von Humboldt foundation, and the Heidelberg Center for Quantum Dynamics.

  18. 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.

  19. Building Information Modelling: Challenges and Barriers in Implement of BIM for Interior Design Industry in Malaysia

    Science.gov (United States)

    Hamid, A. B. Abd; Taib, M. Z. Mohd; Razak, A. H. N. Abdul; Embi, M. R.

    2018-04-01

    Building Information Modelling (BIM) is an innovative approach that has developed crossways the global in architecture, engineering and construction (AEC) industry. The construction industry of Malaysia has undergone a rapid development and dynamic technology adoption in advance and methods between the players industry and stakeholders. Consequently, limited technologies and devices have not been successful as it should have been. This study will be emphasizing scenarios of challenges and barriers in adopting BIM in interior design industry in Malaysia. The study was emphasizing the challenges and barriers in BIM usage from the designer’s perspective. The data are collected through the questionnaires as to identifying the barriers, knowledge, readiness and awareness and distributed to interior design firms were selected randomly. The finding of this research is to examine the barriers and causes of variables BIM usage for interior design industry in Malaysia. The outcome of this study is to identify the constraint of adoption BIM in interior design industry compare to others players in same industry.

  20. Experimental determination of levy flight distributions of the energy barriers in spin glasses

    International Nuclear Information System (INIS)

    Gorham, N.T.; Woodward, R.C.; St Pierre, T.G.; Stamps, R.L.; Walker, M.J.; Greig, D.; Matthew, J.A.D.

    2004-01-01

    Full text: 'Spin glass' was a term originally developed to describe certain magnetic alloys in which there was observed a freezing transition to a low temperature phase where the magnetic moments (or spins) are aligned in fixed but random directions. Although the study of spin glasses is at least three decades old, our current understanding of some very basic issues is still quite limited. Observable characteristics associated with spin glasses are thought to result from the complex dynamics associated with a large number of metastable magnetic states separated by a broad distribution of energy barriers to magnetic reversal. To date, a number of models have been developed which produce this type of energy landscape including the random energy model and the hierarchical energy model. In this study we use a technique previously developed for the study of magnetic nanoparticles to characterise the apparent magnetic energy barrier distribution that results from this complex energy landscape for a series of Pd 40 Ni 40 - x Fe x P 20 (x=10-20) alloys. The distributions observed are best described by a stretched exponential in the form of a truncated Levy flight distribution. This form would appear to suggest a hierarchical landscape of apparent energy barriers arising from interactions between randomly oriented magnetic clusters of spins within the material. The degree of stretching of the exponential form of the energy barrier distributions is found to increase with decreasing iron concentration