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Effects of the constitution of CrON diffusion barrier on the oxidation resistance and interfacial fracture of duplex coating system

Li, W. Z.; Yi, D. Q.; Li, Y. Q.; Liu, H. Q.; Sun, C.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.51%
The duplex coating system of a NiCrAlY overlayer with a CrON diffusion barrier with different phase contents was deposited by AIP method. The duplex coatings were characterized regarding their microstructure, and the ability of the diffusion barrier was evaluated. The oxidation resistance and the interfacial strength of the duplex coatings were investigated. The results indicated that the duplex coating system with a diffusion barrier with an O/N ratio ∼66 and a lower Cr2O3 phase content exhibited more excellent oxidation resistance and lesser interdiffusion than with a diffusion barrier with O/N ∼30.1. The exposed coating samples possessed an improved interfacial strength compared with the annealed samples in the two duplex coating systems. The stronger interfacial strength in the coating system with a diffusion barrier with a low Cr2O3 phase content was related to the fewer defects and lower residual stress in the diffusion barrier.

Chronostratigraphy and radiocarbon age inversion in the Holocene regressive barrier of Parana, southern Brazil

ANGULO, Rodolfo Jose; SOUZA, Maria Cristina de; ASSINE, Mario Luis; PESSENDA, Luiz Carlos Ruiz; DISARO, Sibelle Trevisan
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
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Twenty-two (14)C datings were performed at the central sector of the Parana coast to define Holocene regressive barrier evolution. The barrier Pleistocene substratum was ascribed an age between 40400 and 30000 yr BP, but it can also represent the penultimate sea level highstand during marine isotope stage 5e. The Holocene barrier samples provided ages between 8542-8279 and 2987-2751 cal yr BP, and showed at least six age inversions that were related to age differences between in situ or low-distance transported shells or trunk fragments, and high-distance transported vegetal debris, wood fragments and organic matter samples. The regressive Holocene barrier age was 4402-4135 cal yr BP near the base, and 2987-2751 cal yr BP near the top. Most of the vegetal remains were transported by ebb tidal currents from the estuaries to the inner shelf below wave base level during the mid-Holocene highstand; they were transported onshore by storm waves and littoral currents during the sea level lowering after the sea level maximum, and were deposited mainly as middle shoreface swaley cross-stratification facies. (C) 2008 Published by Elsevier B.V.

Loss minimization by the predictor-corrector modified barrier approach

SOUSA, V. A. de; BAPTISTA, E. C.; COSTA, G. R. M. da
Fonte: ELSEVIER SCIENCE SA Publicador: ELSEVIER SCIENCE SA
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.45%
This paper presents a new approach, predictor-corrector modified barrier approach (PCMBA), to minimize the active losses in power system planning studies. In the PCMBA, the inequality constraints are transformed into equalities by introducing positive auxiliary variables. which are perturbed by the barrier parameter, and treated by the modified barrier method. The first-order necessary conditions of the Lagrangian function are solved by predictor-corrector Newton`s method. The perturbation of the auxiliary variables results in an expansion of the feasible set of the original problem, reaching the limits of the inequality constraints. The feasibility of the proposed approach is demonstrated using various IEEE test systems and a realistic power system of 2256-bus corresponding to the Brazilian South-Southeastern interconnected system. The results show that the utilization of the predictor-corrector method with the pure modified barrier approach accelerates the convergence of the problem in terms of the number of iterations and computational time. (C) 2008 Elsevier B.V. All rights reserved.; Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq); Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)

Sub-barrier fusion of two-neutron halo nuclei

GOMES, P. R. S.; CANTO, L. F.; LUBIAN, J.; HUSSEIN, M. S.
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.48%
The tunneling of composite systems, where breakup may occur during the barrier penetration process, is considered in connection with the fusion of halo-like radioactive, neutron- and proton-rich nuclei, on heavy targets. The large amount of recent and new data clearly indicates that breakup hinders the fusion at energies near and below the Coulomb barrier. However, clear evidence for enhancement due to halo properties seems to over ride the breakup hindrance at lower energies, owing, to a large extent, to the extended matter density distribution. In particular we report here that at sub-barrier energies the fusion cross section of the Borromean two-neutron halo nucleus (6)He with the actinide nucleus (238)U is significantly enhanced as compared to the fusion of a similar projectile with no halo. This conclusion differs from that of the original work, where it was claimed that no such enhancement ensues. This sub-barrier fusion enhancement is also observed in the (6)He + (209)Bi system. (C) 2010 Elsevier B.V. All rights reserved.; FAPERJ; Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ); CNPq; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); FAPESP; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); PRONEX; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Instituto Nacional de Ciencia e Tecnologia de Informacao Quantica-MCT (INCT); Ministério da Ciência...

The development of blowouts and foredunes in the Ilha Comprida barrier (Southeastern Brazil): the influence of Late Holocene climate changes on coastal sedimentation

Sawakuchi, André Oliveira; KALCHGRUBER, R.; Giannini, Paulo César Fonseca; NASCIMENTO JR., D. R.; GUEDES, C. C. F.; UMISEDO, N. K.
Fonte: PERGAMON-ELSEVIER SCIENCE LTD Publicador: PERGAMON-ELSEVIER SCIENCE LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
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Middle to Late Holocene barriers are conspicuous landforms in southeastern and southern Brazilian regions. The barriers in the coastal zones of northern Santa Catarina, Parana and Sao Paulo states (27 degrees 19`-24 degrees 00`S) are formed mainly by beach ridge alignments and many barriers present foredune and blowout alignments in their seaward portion. The development of these eolian landforms appears to record a regional shift in coastal dynamics and barrier building. In this context, the Ilha Comprida barrier stands out for its well-developed and well-preserved foredunes and blowouts. Based on the presence or not and type of eolian landforms, the Ilha Comprida barrier can be divided seaward into inner, middle and outer units. The inner unit is formed entirely by beach ridges. The middle unit comprises a narrow belt of blowouts (up to 15 m high) aligned alongshore. Blowout lobes pointing NNW are indicative of their generation by southern winds. The outer unit is represented by low (<= 1 m high) active or stabilized foredunes and a small transgressive dunefield (similar to 1 km(2)). Twenty-seven luminescence ages (SAR protocol) obtained for the beach ridges, foredunes, and blowouts of these three units allow definition of a precise chronology of these landforms and calculation of rates of coastal progradation. The inner unit presents ages greater than 1004 +/- 88 years. The blowouts of the middle unit show ages from 575 +/- 47 to 172 +/- 18 years. The ages of the outer unit are less than 108 +/- 10 years. Rates of coastal progradation for the inner and outer units are 0.71-0.82 m/year and 0.86-2.23 m/year...

Impaired blood-brain/spinal cord barrier in ALS patients

Garbuzova-Davis, Svitlana; Hernandez-Ontiveros, Diana G.; Rodrigues, Maria C. O.; Haller, Edward; Frisina-Deyo, Aric; Mirtyl, Santhia; Sallot, Sebastian; Saporta, Samuel; Borlongan, Cesario V.; Sanberg, Paul R.
Fonte: ELSEVIER SCIENCE BV; AMSTERDAM Publicador: ELSEVIER SCIENCE BV; AMSTERDAM
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.45%
Vascular pathology, including blood-brain/spinal cord barrier (BBB/BSCB) alterations, has recently been recognized as a key factor possibly aggravating motor neuron damage, identifying a neurovascular disease signature for ALS. However, BBB/BSCB competence in sporadic ALS (SALS) is still undetermined. In this study, BBB/BSCB integrity in postmortem gray and white matter of medulla and spinal cord tissue from SALS patients and controls was investigated. Major findings include (1) endothelial cell damage and pericyte degeneration, (2) severe intra- and extracellular edema, (3) reduced CD31 and CD105 expressions in endothelium, (4) significant accumulation of perivascular collagen IV, and fibrin deposits (5) significantly increased microvascular density in lumbar spinal cord, (6) IgG microvascular leakage, (7) reduced tight junction and adhesion protein expressions. Microvascular barrier abnormalities determined in gray and white matter of the medulla, cervical, and lumbar spinal cord of SALS patients are novel findings. Pervasive barrier damage discovered in ALS may have implications for disease pathogenesis and progression, as well as for uncovering novel therapeutic targets. (C) 2012 Elsevier B.V. All rights reserved.; Muscular Dystrophy Association [92452]; Muscular Dystrophy Association

Cassava starch biodegradable films: Influence of glycerol and clay nanoparticles content on tensile and barrier properties and glass transition temperature

Souza, A. C.; Benze, R.; Ferrão, E. S.; Ditchfield, C.; Coelho, A. C. V.; Tadini, C. C.
Fonte: ELSEVIER SCIENCE BV; AMSTERDAM Publicador: ELSEVIER SCIENCE BV; AMSTERDAM
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.48%
In this this study, glycerol content and its incorporation method on tensile and barrier properties of biodegradable films (BF) based on cassava starch were analyzed. ANOVA showed that the glycerol incorporation method did not influence the results (P > 0.05), however the glycerol content influenced significantly the tensile and barrier properties of the films (P < 0.05). Films prepared with lower glycerol content presented better tensile and barrier properties than films with higher content. Films were then prepared with addition of clay nanoparticles and their tensile and barrier properties and glass transition temperature were measured. ANOVA indicated that both glycerol and clay nanoparticles influenced significantly the tensile and barrier properties (P < 0.05), diminishing film permeability when clay nanoparticles were present, while the glass transition temperature was not influenced (P > 0.05). (C) 2011 Elsevier Ltd. All rights reserved.; FAPESP (The State of Sao Paulo Research Foundation); CAPES (Brazilian Committee for Postgraduate Courses in Higher Education)

The double gaussian distribution of inhomogeneous barrier heights in Al/GaN/p-GaAs (MIS) schottky diodes in wide temperature range

Zeyrek,S.; Bülbül,M. M.; Altındal,Ş.; Baykul,M. C.; Yüzer,H.
Fonte: Sociedade Brasileira de Física Publicador: Sociedade Brasileira de Física
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2008 EN
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The current-voltage (I-V) characteristics of metal-insulator-semiconductor (Al/GaN/p-GaAs) Schottky barrier diodes (SBDs) were investigated over a wide temperature range of 80-380 K. By using the thermionic emission (TE) theory, the zero bias barrier height ΦB0 calculated from I-V characteristics was found to increase with increasing temperature as the ideality factor n decreases with increasing temperature, and especially the activation energy plot is nonlinear at low temperatures. The observed variation in the ΦB0 and n is attributed to the spatial barrier inhomogeneities in SBD by assuming a Gaussian distribution (GD) of barrier heights (BHs). The experimental I-V-T characteristics of the SBDs have shown a double Gaussian distribution having mean barrier heights $ar{phi}$B of 0.854 eV and 0.395 eV and standard deviations σs for 0.142 V and 0.059 V, respectively. The modified ln(Io/T²)-q²σo2/2(kT)² vs q/kT plot gives ΦB0 and Richardson constant A* as 0.858 eV and 0.364 eV, and 78.5 and 128 A/cm²K², respectively, without using the temperature coefficient of the barrier height. Hence, the results have shown that the I-V-T characteristics of the Al/GaN/p-GaAs SBDs can be successfully explained on the basis of TE mechanism with a double Gaussian distribution of the barrier heights.

Analysis of quantum dot skin penetration in a barrier compromised in vivo model

Mortensen, Luke Jonathan (1982 - ); DeLouise, Lisa
Fonte: University of Rochester Publicador: University of Rochester
Tipo: Tese de Doutorado Formato: Number of Pages:xix, 219 leaves; Illustrations:ill. (some col.)
ENG
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Thesis (Ph. D.)--University of Rochester. Dept. of Biomedical Engineering, 2011.; Exposure to engineered nanoparticles (NPs) is becoming near-inescapable as their unique size dependent properties have ensured integration into a wide range of consumer products and research tools. One of the most biologically impactful of these applications is in consumer products such as sunscreens and other cosmetics, where consumer use commonly consists of topical application to UVB damaged skin. A number of studies have investigated the ability of NPs to penetrate the skin barrier, but very few are available on NP permeation differences that result from clinically relevant skin barrier disruptions such as UVB. This thesis uses semiconductor quantum dots (QDs) as a model nanoparticle to investigate the impact of UVB on skin permeability. QDs are NPs with advantageous fluorescence properties including high quantum yield, broad excitability, and narrow emission bandwidth. This doctoral dissertation evaluates the impact of UVB on QD skin penetration, investigates the effects of UVB primary keratinocyte QD cellular interaction, and expands the technical palette with whole tissue confocal imaging development. UVB radiation causes a host of biological changes in the skin...

Electron microscope study of blood-brain barrier opening induced by immunological targeting of the endothelial barrier antigen

Ghabriel, M.; Zhu, C.; Leigh, C.
Fonte: Elsevier Science Bv Publicador: Elsevier Science Bv
Tipo: Artigo de Revista Científica
Publicado em //2002 EN
Relevância na Pesquisa
36.48%
Barrier vessels in the central nervous system are lined with endothelial cells which constitute the blood–brain barrier (BBB) and show selective expression of certain biochemical markers. One of these, the endothelial barrier antigen (EBA), is specific to the rat. The exact role of EBA in the BBB is not known, although several studies have shown a correlation between the reduction in EBA expression in endothelial cells and the opening of the BBB. However, in these studies it was not possible to determine if EBA reduction was a primary event or was secondary to opening of the BBB. A recent light microscope study demonstrated that immunological targeting of EBA in vivo, by intravenous injection of a monoclonal antibody (anti-EBA), leads to acute and widespread opening of the BBB. In the current study we have employed this model together with tracer application and immunoperoxidase electron microscopy to determine the site of binding of the injected antibody and the route of opening of the BBB. The results showed that (a) the anti-EBA injected in vivo became bound to brain endothelial cells, principally to luminal membranes. (b) Endothelial cells showed widened intercellular junctions and increased cytoplasmic vesicles and vacuoles. (c) Many perivascular astrocytic processes were swollen. (d) The macromolecular tracer HRP was present in vesicles...

A narrow time-window for access to the brain by exogenous protein after immunological targeting of a blood-brain barrier antigen

Ghabriel, M.; Lu, J.; Tadros, R.; Hermanis, G.
Fonte: Academic Press Inc Elsevier Science Publicador: Academic Press Inc Elsevier Science
Tipo: Artigo de Revista Científica
Publicado em //2004 EN
Relevância na Pesquisa
36.51%
The endothelial barrier antigen (EBA) is a membrane protein expressed by endothelial cells of the rat blood–brain barrier (BBB). A previous short-term non-recovery study demonstrated that immunological targeting of EBA by intravenous administration of a monoclonal antibody (anti-EBA) led to acute opening of the BBB to exogenous and endogenous tracers. The aims of the present study were to determine whether opening of the BBB was reversible and compatible with survival, and whether a “therapeutic window” existed. A single intravenous injection of one of three doses (high, medium and low) of anti-EBA was used. Animals were allowed to survive for periods ranging from 17 min to 4 days. The tracer horseradish peroxidase (HRP) was administered intravenously 10 min before perfusion fixation, and its distribution was assessed in Vibratome sections of the brain and spinal cord. Leakage of HRP into the central nervous system was dose- and time-dependent. The medium dose produced incipient HRP leakage at 17 min and widespread pronounced leakage at 30 min. Progressive reduction in HRP permeability occurred from 45 min to 2 h, with barrier restoration by 3 h. At all subsequent time intervals (6 h–4 days) the BBB remained impermeable to HRP. The low and high doses produced less and greater HRP leakage...

The Blood-brain barrier in normal and pathological conditions / by Chunni Zhu.

Zhu, Chunni
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado Formato: 170535 bytes; application/pdf
Publicado em //2001 EN
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Examines the blood-brain barrier in normal and pathological conditions induced by intravascular and extravascular insults. Intravascular insults were induced by administration of Clostridium perfringens prototoxin; extravascular insults were induced by an impact acceleration model for closed head injury to induce traumatic brain injury. Also examines the integrity of the blood-brain barrier ultrastructurally and by its ability to exclude endogenous and exogenous tracers. Also studies the expression of 2 blood-brain barrier specific proteins, endothelial barrier antigen (EBA) and glucose transporter 1 (GLUT1); Thesis (Ph.D.)--University of Adelaide, Dept. of Anatomical Sciences, 2002?; Bibliography: leaves 318-367.; x, 367 leaves : ill. ; 30 cm.; Title page, contents and abstract only. The complete thesis in print form is available from the University Library.

Hematoencephalic barrier. Ultrastructure and histophysiology of the endothelium capillary of the neuronal nuclei of the mesencephalon

González Santander, R.; Martínez Cuadrado, G.; González-Santander Martínez, M.; Toledo Lobo, M.V.; Martínez Alonso, F.J.
Fonte: Murcia : F. Hernández Publicador: Murcia : F. Hernández
Tipo: Artigo de Revista Científica Formato: application/pdf
ENG
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The ultrastucture of the dorsal periaqueductal nucleus capillaries of the mesencephalon in the cat was studied under the electron microscope in relation to the hematoencephalic barrier, and its four structural levels: l. Endothelium; 2. Basa1 membrane; 3, Pericytes; and 4. Glial prolongations. An analysis was performed of what occurs in these four components (in a non-experimental histophysiological state, and without manipulation by markers) in the thinnest capillaries of the centre of the mesencephalic neuronal nucleus. Special attention was placed on the first diffusion barrier formed by the endothelium capillary as the intimate guardian of the Central Nervous System (C.N.S) neurons. The C.N.S. capillaries are formed from the continuous endothelium, with no fenestrations, and hermetic joining complexes, without pinocytosis vesicles on both sides of the plasmatic membrane (adluminal and external), and surrounded by a continuous basal membrane. The non-fenestrated capillaries of the C.N.S. are less permeable than those with similar characteristics located in other areas. In the C.N.S. these capillaries form a selective physiological barrier which determines the size of the molecules that are permitted to cross the capillary wall. It is suggested that the electron-dense globules found in the endothelium cytoplasm may be molecules assimilated from the blood...

Assessment of blood-retina1 barrier integrity

Vinores, S.A.
Fonte: Murcia : F. Hernández Publicador: Murcia : F. Hernández
Tipo: Artigo de Revista Científica Formato: application/pdf
ENG
Relevância na Pesquisa
36.55%
The blood-retina1 barrier consists of two components which are comprised of the retinal vascular endothelium and the retinal pigment epithelium, respectively. Its functional integrity can be recognized by tight junctions between these cells with a paucity of endocytic vesicles within them and the presence of the molecules that regulate the ionic and metabolic gradients that constitute the barrier. The banier is compromised in severa1 disease processes and by a variety of agents, but in most cases the location and mechanism for barrier failure is not understood. Perfusion with a variety of radiolabeled tracer molecules, vitreous fluorophotometry, or magnetic resonance imaging can be used to quantitate blood-retina1 barrier leakage. Fluorescein angiography or magnetic resonance imaging can localize sites of leakage in vivo with limited resolution. Evans blue dye can be used to visualize blood-retina1 barrier failure in gross pathological specimens and immunohistochemical labeling of serum proteins such as albumin or fibrinogen can be used to localize sites of blood-retina1 barrier breakdown by light microscopy. Tracers such as horseradish peroxidase, microperoxidase, or lanthanum, or the immunocytochemical demonstration of albumin can be used to reveal bloodretinal barrier breakdown at the ultrastructural leve1 and provide insights into the mechanisms involved. This review discusses the advantages and lirnitations of each of these methods to aid in selection of the appropriate techniques to derive the desired information.

Anti-adhesion barrier gels following operative hysteroscopy for treating female infertility: a systematic review and meta-analysis

Bosteels, J.; Weyers, S.; Mol, B.; D'Hooghe, T.
Fonte: Springer-Verlag Publicador: Springer-Verlag
Tipo: Artigo de Revista Científica
Publicado em //2014 EN
Relevância na Pesquisa
36.53%
The aim of this study was to assess the effects of any anti-adhesion barrier gel used after operative hysteroscopy for treating infertility associated with uterine cavity abnormalities. Gynecologists might use any barrier gel following operative hysteroscopy in infertile women for decreasing de novo adhesion formation; the use of any barrier gel is associated with less severe de novo adhesions and lower mean adhesion scores. Nevertheless, infertile women should be counseled that there is at the present no evidence for higher live birth or pregnancy rates. There is a lack of data for the outcome miscarriage. Preclinical studies suggest that the use of biodegradable surgical barriers may decrease postsurgical adhesion formation. Observational studies in the human report conflicting results. We searched the Cochrane Menstrual Disorders and Subfertility Specialized Register (10 April 2013), the Cochrane Central Register of Controlled Trials (The Cochrane Library 2013, Issue 1), MEDLINE (1950 to 4 April 2013), EMBASE (1974 to 4 April 2013), and other electronic databases of trials including trial registers, sources of unpublished literature, and reference lists. We handsearched the Journal of Minimally Invasive Gynecology (from 1 January 1992 to 13 April 2013); we also contacted experts in the field. We included the randomized comparisons between any anti-adhesion barrier gel versus another barrier gel...

Expression of a blood-brain barrier-specific antigen in the reproductive tract of the male rat

Ghabriel, M.; Lu, J.; Hermanis, G.; Zhu, C.; Setchell, B.
Fonte: Journals of Reproduction Fertility Ltd Publicador: Journals of Reproduction Fertility Ltd
Tipo: Artigo de Revista Científica
Publicado em //2002 EN
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36.55%
The endothelial barrier antigen (EBA) is a protein expressed specifically by the endothelial cells of the rat brain barrier vessels. This antigen has been described as a 'barrier protein' and is used as a marker for the competent blood-brain barrier. A blood-testis barrier has also been described. However, unlike the blood-brain barrier, which is formed by endothelial cells, the blood-testis barrier is formed mainly by the Sertoli cells, which provide an isolated environment for spermatogenic cells within the seminiferous tubules. Testicular blood vessels express the erythroid glucose transporter protein and other markers, which are strongly expressed in brain blood vessels, and may contribute to the blood-testis barrier. This study was carried out to determine whether Sertoli cells or testicular blood vessels express EBA. Tissues of other organs were used as controls for EBA expression. EBA was expressed by the endothelial cells in most microvessels of the testis, and in a few vessels of the epididymis, seminal vesicle, prostate gland, vas deferens and bladder-neck region. Furthermore, EBA was strongly and consistently detected in epithelial cells of the rete testis and dorsolateral prostate gland, and in a few epithelial cells of the ventral prostate gland...

O método da função Lagrangiana barreira modificada/penalidade; The penalty/modified barrier Lagrangian function method

Pereira, Aguinaldo Aparecido
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 27/09/2007 PT
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Neste trabalho propomos uma abordagem que utiliza o método de barreira modificada/penalidade para a resolução de problemas restritos gerais de otimização. Para isso, foram obtidos dados teóricos, a partir de um levantamento bibliográfico, que explicitaram os métodos primal-dual barreira logarítmica e método de barreira modificada. Nesta abordagem, as restrições de desigualdade canalizadas são tratadas pela função barreira de Frisch modificada, ou por uma extrapolação quadrática e as restrições de igualdade do problema através da função Lagrangiana. A implementação consiste num duplo estágio de aproximação: um ciclo externo, onde o problema restrito é convertido em um problema irrestrito, usando a função Lagrangiana barreira modificada/penalidade; e um ciclo interno, onde o método de Newton é utilizado para a atualização das variáveis primais e duais. É apresentada também uma função barreira clássica extrapolada para a inicialização dos multiplicadores de Lagrange. A eficiência do método foi verificada utilizando um problema teste e em problemas de fluxo de potência ótimo (FPO).; In this paper, we propose an approach that utilizes the penalty/modified barrier method to solve the general constrained problems. On this purpose...

Barrier Island Morphological Response to Natural Disturbances and Human Dune Modifications: A Comparative Analysis of Developed and Undeveloped Regions of the Outer Banks, NC

LaBarbiera, Carolyn
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Masters' project
Publicado em 25/04/2013
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Barrier islands shift dynamically, often influenced by wind, wave, tidal, and storm forces. Overwash occurs naturally from storm surge, but can be hindered by alteration to the coastal landscape by humans, particularly in the form of artificially high frontal dunes. My study compares undeveloped and developed barrier islands of the North Carolina Outer Banks. Undeveloped shorelines illustrate the expected natural evolution of a barrier island and the developed shorelines serve as an example of a human influenced and modified barrier island. I compared both developed and undeveloped regions through quantification of island width, elevation, and overwash occurrence as a result of Hurricane Sandy in 2012. My study reveals the influence that humans have on altering barrier island states and possibly amplifying the continuation of a high relief state through overwash suppression. For the undeveloped region, overwash occurred very frequently (92.5% of study region) and although the average island width was larger (~21-47 m) than the developed region, as expected, the widths varied greatly. The minimum island widths for the developed and undeveloped areas were 197 m and 267 m, respectively, which is narrow when considering the infrastructure in the developed region. For the developed region...

STRATIGRAPHY AND EVOLUTION OF THE HOLOCENE BARRIER OF RIO GRANDE DO SUL BETWEEN TRAMANDAÍ AND CIDREIRA; ESTRATIGRAFIA E EVOLUÇÃO DA BARREIRA HOLOCÊNICA DO RIO GRANDE DO SUL NO TRECHO TRAMANDAÍ-CIDREIRA

Travessas, Felipe de Almeida; Dillenburg, Sérgio Rebello; Clerot, Luiz Carlos Pinheiro
Fonte: UFPR Publicador: UFPR
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Artigo Avaliado pelos Pares Formato: application/pdf
Publicado em 25/09/2006 POR
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The Holocene coastal barrier (barrier-lagoon system IV) in Rio Grande do Sul evolved differently in the last 6 – 5ka. For instance, to the north (between Tramandaí an Torres, figure 1) the barrier prograded, while to the south (between Mostardas and Estreito) it receded. The studied segment (Tramandaí – Cidreira) is located immediately to the south of Tramandaí. In 2000 and 2001 a drilling campaign was carried out in this segment aiming to figure out its geological nature and evolution. The drill holes were performed along three cross-shore profiles (Tramandaí, Jardim do Éden and Cidreira, figure 2). Based on morphological, lithological, 14C dating, and computer modeling of coastal evolution it was possible to define a non-uniform transgressive nature for this barrier segment (30km long), as well as the barrier evolutionary chronology. In Tramandaí the barrier shows, on its western part, stratigraphic records of a transgressive phase that represents the maximum landward position of the barrier during the final stages of the Postglacial Marine Transgression (Fig. 4). On its eastern part the barrier shows a very discrete regressive stratigraphy, but in general the barrier stayed relatively stabilized during the last 6 – 5ka. Also in Tramandaí the oldest sedimentary record of the Holocene lagoonal system occurs. It corresponds to lagoonal floor mud deposits dated on 11280 – 10510 cal years BP. At the maximum sea-level height of the Postglacial Marine Transgression a barrier was positioned seaward of the present shoreline on both Jardim do Éden and Cidreira. In Jardim do Éden barrier...

The intestinal barrier function and its involvement in digestive disease

Salvo-Romero,Eloísa; Alonso-Cotoner,Carmen; Pardo-Camacho,Cristina; Casado-Bedmar,Maite; Vicario,María
Fonte: Revista Española de Enfermedades Digestivas Publicador: Revista Española de Enfermedades Digestivas
Tipo: info:eu-repo/semantics/article; journal article; info:eu-repo/semantics/publishedVersion Formato: text/html; application/pdf
Publicado em 01/11/2015 ENG
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The gastrointestinal mucosal surface is lined with epithelial cells representing an effective barrier made up with intercellular junctions that separate the inner and the outer environments, and block the passage of potentially harmful substances. However, epithelial cells are also responsible for the absorption of nutrients and electrolytes, hence a semipermeable barrier is required that selectively allows a number of substances in while keeping others out. To this end, the intestine developed the "intestinal barrier function", a defensive system involving various elements, both intra- and extracellular, that work in a coordinated way to impede the passage of antigens, toxins, and microbial byproducts, and simultaneously preserves the correct development of the epithelial barrier, the immune system, and the acquisition of tolerance against dietary antigens and the intestinal microbiota. Disturbances in the mechanisms of the barrier function favor the development of exaggerated immune responses; while exact implications remain unknown, changes in intestinal barrier function have been associated with the development of inflammatory conditions in the gastrointestinal tract. This review details de various elements of the intestinal barrier function...