bluuebunny/crossref_metadata_2025 huggingface dataset:
Heterosynaptic Plasticity Prevents Runaway Synaptic Dynamics
Authors: Chen Jen-Yung , Lonjers Peter , Lee Christopher , Chistiakova Marina , Volgushev Maxim , Bazhenov Maxim
Published: October 2013

Spike timing-dependent plasticity (STDP) and other conventional Hebbian-type plasticity rules are prone to produce runaway dynamics of synaptic weights. Once potentiated, a synapse would have higher probability to lead to spikes and thus to be further potentiated, but once depressed, a synapse would tend to be further depressed. The runaway synaptic dynamics can be prevented by precisely balancing STDP rules for potentiation and depression; however, experimental evidence shows a great variety of potentiation and depression windows and magnitudes. Here we show that modifications of synapses to layer 2/3 pyramidal neurons from rat visual and auditory cortices in slices can be induced by intracellular tetanization: bursts of postsynaptic spikes without presynaptic stimulation. Induction of these heterosynaptic changes depended on the rise of intracellular calcium, and their direction and magnitude correlated with initial state of release mechanisms. We suggest that this type of plasticity serves as a mechanism that stabilizes the distribution of synaptic weights and prevents their runaway dynamics. To test this hypothesis, we develop a cortical neuron model implementing both homosynaptic (STDP) and heterosynaptic plasticity with properties matching the experimental data. We find that heterosynaptic plasticity effectively prevented runaway dynamics for the tested range of STDP and input parameters. Synaptic weights, although shifted from the original, remained normally distributed and nonsaturated. Our study presents a biophysically constrained model of how the interaction of different forms of plasticity—Hebbian and heterosynaptic—may prevent runaway synaptic dynamics and keep synaptic weights unsaturated and thus capable of further plastic changes and formation of new memories.
Facilitation of Inferior Frontal Cortex by Transcranial Direct Current Stimulation Induces Perceptual Learning of Severely Degraded Speech
Authors: Sehm Bernhard , Schnitzler Tim , Obleser Jonas , Groba Agnes , Ragert Patrick , Villringer Arno , Obrig Hellmuth
Published: October 2013

Perceptual learning requires the generalization of categorical perceptual sensitivity from trained to untrained items. For degraded speech, perceptual learning modulates activation in a left-lateralized network, including inferior frontal gyrus (IFG) and inferior parietal cortex (IPC). Here we demonstrate that facilitatory anodal transcranial direct current stimulation (tDCSanodal) can induce perceptual learning in healthy humans. In a sham-controlled, parallel design study, 36 volunteers were allocated to the three following intervention groups: tDCSanodalover left IFG, IPC, or sham. Participants decided on the match between an acoustically degraded and an undegraded written word by forced same-different choice. Acoustic degradation varied in four noise-vocoding levels (2, 3, 4, and 6 bands). Participants were trained to discriminate between minimal (/Tisch/-FISCH) and identical word pairs (/Tisch/-TISCH) over a period of 3 d, and tDCSanodalwas applied during the first 20 min of training. Perceptual sensitivity (d′) for trained word pairs, and an equal number of untrained word pairs, was tested before and after training. Increases ind′ indicate perceptual learning for untrained word pairs, and a combination of item-specific and perceptual learning for trained word pairs. Most notably for the lowest intelligibility level, perceptual learning occurred only when tDCSanodalwas applied over left IFG. For trained pairs, improvedd′ was seen on all intelligibility levels regardless of tDCS intervention. Over left IPC, tDCSanodaldid not modulate learning but instead introduced a response bias during training. Volunteers were more likely to respond “same,” potentially indicating enhanced perceptual fusion of degraded auditory with undegraded written input. Our results supply first evidence that neural facilitation of higher-order language areas can induce perceptual learning of severely degraded speech.
ChemR23 knockout mice display mild obesity but no deficit in adipocyte differentiation
Authors: Rouger Laurie , Denis G Raphaël , Luangsay Souphalone , Parmentier Marc
Published: October 2013

Chemerin was initially described as a chemoattractant factor for leukocyte populations. More recently, the protein has also been reported to be an adipokine, regulating adipocyte differentiation in vitro via its receptor ChemR23, and to be correlated with BMI and other parameters of the metabolic syndrome in humans. The aim of this study was to investigate the role of the chemerin/ChemR23 axis in the regulation of metabolism in vivo, using a mouse knockout (KO) model for ChemR23 (Cmklr1) in a C57BL/6 genetic background. Body weight and adipose tissue mass did not differ significantly in young animals, but were significantly higher in ChemR23 KO mice aged above 12 months. Glucose tolerance was unaffected. No significant modifications in the levels of blood lipids were observed and no increase in the levels of inflammatory markers was observed in the adipose tissue of KO mice. A high-fat diet did not exacerbate the obese phenotype in ChemR23 KO mice. No obvious defect in adipocyte differentiation was detected, while a marker of lipogenic activity (GPD1 expression) was found to be elevated. In conclusion, the chemerin/ChemR23 system does not appear to play a major role in adipocyte differentiation in vivo, but it may be involved in adipose tissue homeostasis.
Georges Teissier (1900–1972) and the Modern Synthesis in France
Authors: Loison Laurent
Published: October 2013

This Perspectives is devoted to the ideas of the French zoologist Georges Teissier about the mechanisms of evolution and the relations between micro- and macroevolution. Working in an almost universally neo-Lamarckian context in France, Teissier was one of the very few Darwinians there at the time of the evolutionary synthesis. The general atmosphere of French zoology during the 1920s and the 1930s will first be recalled, to understand the specific conditions in which Teissier became a zoologist. After a brief overview of his joint work with Philippe L’Héritier on the experimental genetics of Drosophila, this article describes the ways Teissier, during the 1950s, conceptualized the mechanisms that could allow for macroevolutionary transitions.
Study of the effect of abiotic stress on the antioxidant enzyme activity of cereals under regulated environmental conditions
Authors: Varga B. , Bencze S. , Janda T. , Veisz O.
Published: October 2013

The impacts of climate modification were examined in terms of changes in the stress tolerance of winter wheat varieties. The enzyme reactions of two winter wheat varieties to drought stress, simulated by water withholding in three different phenophases, were analysed in a phytotron experiment in the Centre for Agricultural Research, Hungarian Academy of Sciences. Plants were raised either at ambient CO2 level or at twice this concentration. The quantities of glutathione reductase (GR), glutathione-S-transferase (GST), catalase (CAT), guaiacol peroxidase (POD) and ascorbate peroxidase (APX) were determined from leaf samples collected at the end of the drought treatment.The results showed that antioxidant enzymes may help to counterbalance the reactive oxygen species induced by stress during various stages of the vegetation period. Although there were substantial differences in the changes induced in the activity of individual enzymes by modifications in environmental factors, this activity and its response to stress depended not only on these factors, but also on the developmental stage of the plant. Modifications in enzyme activity could indicate that enhanced CO2 concentration delayed the development of drought stress up to first node appearance, and stimulated antioxidant enzyme activity when drought occurred during ripening.
Retinoids for prevention and treatment of actinic keratosis
Authors: Ianhez Mayra , Fleury Junior Luiz Fernando Fróes , Miot Hélio Amante , Bagatin Edileia
Published: October 2013

Actinic keratosis is a common cause of dermatological consultations and it presents a strong association with squamous cell carcinoma. Many substances are used for treatment and prevention, such as retinoids. Nevertheless, many studies on retinoids emphasize their application in treating and preventing non melanoma skin cancers. In this article, we reviewed studies about systemic and topical retinoids used with immunocompetent patients and organ transplant recipients with actinic keratosis, as primary or secondary outcomes. The majority of these papers pointed to a reduction in actinic keratosis count after treatment with retinoids. However, studies need to be better-defined in order to address the lack of a standardized dose, the absence of control groups, the low number of patients and short follow-up periods. Blind, randomized and controlled clinical trials with adequate sample sizes, specifically focused on actinic keratosis, are needed to clarify the real benefit of topical and/or oral retinoids. Comparison of efficacy and safety between oral and topical retinoids in the prevention and treatment of non-melanoma skin cancers and actinic keratosis is an essential pre requisite to establish new strategies to control these conditions.
Cutaneous mucinosis in mixed connective tissue disease*
Authors: Favarato Maria Helena Sampaio , Miranda Sofia Silveira de Castro , Caleiro Maria Teresa Correia , Assad Ana Paula Luppino , Halpern Ilana , Fuller Ricardo
Published: October 2013

Cutaneous mucinosis is a group of conditions involving an accumulation of mucin or glycosaminoglycan in the skin and its annexes. It is described in some connective tissue diseases but never in association with mixed connective tissue disease. This report concerns two cases of cutaneous mucinosis in patients with mixed connective tissue disease in remission; one patient presented the papular form, and the other reticular erythematous mucinosis. These are the first cases of mucinosis described in mixed connective tissue disease. Both cases had skin lesions with no other clinical or laboratorial manifestations, with clinical response to azathioprine in one, and to an association of chloroquine and prednisone in the other.
Occupational and non-occupational allergic contact dermatitis and quality of life: a prospective study
Authors: Brutti Catiussa Spode , Bonamigo Renan Rangel , Cappelletti Taciana , Martins-Costa Gabriela Mynarski , Menegat Ana Paula Salin
Published: October 2013

Attempted to evaluate and compare the impact on quality of life of occupational and non-occupational ACD and to identify the most frequently involved allergens. A quality of life questionnaire was applied. We noted moderate impact on the quality of life of both groups, without a statistical difference. Our study corroborates previous general data on the prevalence of nickel sulphate and paraphenylenediamine as the most common allergens. Potassium bichromate was shown to be one of the main occupational allergens and thimerosal as the main non-occupational allergen in our sample.
Severe Multi-Resistant Pemphigus vulgaris: prolonged remission with a single cycle of Rituximab
Authors: Corral Isabela Soubhia , Freitas Thais Helena Proença de , Aquino Renata Telles Rudge de , Koller Daniella Abbruzzini S. , Magliari Maria Elisa Ruffolo , Muller Helena
Published: October 2013

Pemphigus vulgaris is an autoimmune bullous disease whose therapy is based on systemic corticosteroids, with or without immunosuppressants. Rituximab is a chimeric monoclonal antibody of the IgG class, directed at a specific CD20 B cell surface antigen, used in pemphigus vulgaris empirically since 2002, with success in 90% of the cases and long periods of remission. Male patient, 33 years old, diagnosed with pemphigus vulgaris, confirmed by histopathology and direct immunofluorescence. He was treated for seven months with numerous treatments, including immunosuppressive drugs, with an unsatisfactory response, until he had complete remission with the use of rituximab. During a 34-month follow-up period, the patient presented a slight clinical relapse, which was successfully controlled with prednisone in a daily dose of 120mg, soon reduced to 20mg.
Case for diagnosis
Authors: Tiengo Adriana , Barros Hugo Rocha , Carvalho Daniele Bueno , Oliveira Gabriela Mantovanelli de , Romiti Ney
Published: October 2013

Childhood Granulomatous Periorificial Dermatitis is an acneiform facial rash that affects the periorificial area in children. The clinical aspectare asymptomatic 1-3 mm papules of, monomorphic, erythematous or hypopigmented in periorificial areas - mouth, nose and eyes. It's a benign and self-limited disease that heals spontaneously without scarring and specific therapy. Differential diagnoses include perioral dermatitis, granulomatous-rosacea, sarcoidosis, and lupus miliaris disseminatus faciei. We present the case of a 4-year-old boy, presenting papules in periorificials areas. Due to its low incidence and low number of publications we report the present case.
Time needed to schedule dermatological consultations in Brazil
Authors: Miot Helio Amante , Miot Luciane Donida Bartoli
Published: October 2013

BACKGROUND: It is not clear what the population's demand for dermatologists is, nor how many professionals are needed in order to provide adequate care in this area of expertise. Knowledge of the flow of patients at dermatological clinics throughout the country allows for the formation of expansion and distribution policies regarding professionals, and provides backing for the decision to increase medical residency places. OBJECTIVES: To evaluate the time it takes to schedule a private dermatological consultation in Brazil, and other factors concerning consultations. METHODS: Survey with a random sample of 14% of Brazilian dermatologists, simulating the scheduling of emergency clinical and cosmetic consultations, and botulinum toxin procedures. Also, details relating to cost and professionals, were studied. Data were adjusted for each region of the country. RESULTS: A total of 873 dermatologists were evaluated. Full SBD members represented 85%, and 66% were women. The median time to schedule a consultation ranged from 6 (out-of-pocket payment) to 7 (medical insurance) consecutive working days. Times varied depending on the region. A multivariate analysis showed that out-of-pocket consultations and procedures were scheduled sooner than with medical insurance, regardless of whether they were clinical or cosmetic. CONCLUSION: The characteristics of dermatologists are varied throughout regions of the country. Private consultations and procedures are scheduled sooner than with insurance companies.
Tungiasis under dermoscopy: in vivo and ex vivo examination of the cutaneous infestation due to Tunga penetrans
Authors: Criado Paulo Ricardo , Landman Gilles , Reis Vitor Manoel Silva dos , Belda Junior Walter
Published: October 2013

The female flea Tunga penetrans is responsible for a cutaneous parasitosis known as Tungiasis. We report the clinical case of a 12 year-old Caucasian boy who sought treatment in a dermatological private office due to a painful lesion in the plantar area and whose dermoscopic examination, without skin contact, allowed the visualization of parasite's movement inside the skin. The diagnosis of tungiasis is clinical, but it can be aided by in vivo and ex vivo dermoscopic examination of the lesion.
Environmental dermatology: skin manifestations of injuries caused by invertebrate aquatic animals
Authors: Haddad Junior Vidal
Published: October 2013

Contact between humans and coastal areas has increased in recent decades, which has led to an increase in injuries from aquatic animals. The majority of these present dermatological manifestations, and some of them show typical lesions. The highest percentages of injuries that occur in marine environments are associated with invertebrates such as sea urchins, jellyfish and Portuguese men-of-war (echinoderms and cnidarians). In this review, we discuss the clinical, therapeutic and preventive aspects of injuries caused by marine and freshwater invertebrates, focusing on first aid measures and diagnosis for dermatologists and professionals in coastal areas.
Análise de agrupamento da variabilidade espacial da produtividade da soja e variáveis agrometeorológicas na região oeste do Paraná
Authors: Araújo Everton C. de , Uribe-Opazo Miguel A. , Johann Jerry A.
Published: September 2013

O presente trabalho realizou uma análise de agrupamentos espacial por meio da estatística multivariada, no intuito de investigar a relação entre a produtividade da soja e as seguintes variáveis agrometeorológicas: precipitação pluvial, temperatura média do ar, radiação solar global e índice local de Moran (LISA) da produtividade. O estudo foi realizado com os dados das safras dos anos agrícolas de 2000/2001 a 2007/2008 da região oeste do Estado do Paraná. A identificação do número adequado de clusters para cada ano-safra foi obtida utilizando a minimização de desvios. O estudo mostrou a formação de grupos de municípios utilizando as similaridades das variáveis em análise. A análise de agrupamento foi um instrumento útil para melhor gestão das atividades de produção da agricultura, em função de que, com o agrupamento, foi possível estabelecer similaridades que proporcionem parâmetros para melhor gestão dos processos de produção que traga, quantitativa e qualitativamente, resultados almejados pelo agricultor.
Pedological characterization and land use and occupation: influences on water quality in a watershed located in the zona da mata (MG)
Authors: Andrade Luana C. R. , Marques Eduardo A. G. , Felicori Thaís de C.
Published: September 2013

In order to verify the influence of class and use and occupation of land on water quality, it was performed the characterization and analyzes of land use and monitoring of seven springs inserted in a watershed located in the rural of Viçosa city - Minas Gerais (MG) state, in Brazil. Through soil analyzes, carried out in five different profiles, it was possible to identify three distinct pedological classes: Argisol, Cambisol and Latosol. Furthermore, the concentrations of Fe, Mn, Cu, Zn, Cr, Cd, Pb and Ni were identified in each of the horizons in the considered profiles. Water samples were collected and analyzed monthly, over eight months, twenty two parameters of water quality. Comparing the results of each survey, it was possible to identify a relation between water quality and land use in the round of the springs, considering color, BOD, DO, E. coli and Mn as the most affected parameters, influenced mainly by soil characteristics and the presence of a large percentage of pasture in the study area.
Evaluation of the heating of broilers in shed by means of gas hoods and underfloor heating
Authors: Leva Flávia F. de , Camacho José R. , Oliveira Filho Delly
Published: September 2013

This study was conducted to evaluate and compare the behavior of the heating inside poultry shed through gas hood and underfloor heating. The experiment was conducted in poultry shed belonging to the Federal Institute of Education, Science and Technology of Triângulo Mineiro Region, Uberlândia city Â– state of Minas Gerais (MG), Brazil. The dimensions of the shed are 24 meters long and 9.6 meters wide and with a ceiling height of 3.2 meters. The temperature was measured with an optical thermometer of Minipa brand, MT 350 model. It was used, to the analysis of temperature behavior, the public domain software FEMM 4.2, which uses finite elements techniques, with data collected from two lots. Underfloor heating is made using hot water flowing through a serpentine type system, which is installed below the bed; this hot water is from solar heaters. An energetic and economic assessment of the warming shed for raising chickens was realized. From the results obtained with the simulations, it may observe that the heating through the floor provides a more homogeneous distribution of temperature when compared with the hood heating. The flow of heat is upwards supplying, thus, the greatest need of heating of the bird, which is the pectoral part.
Definição de características críticas na implementação de serviços customizados em massa
Authors: Vidor Gabriel , Medeiros Janine Fleith de , Fogliatto Flávio Sanson
Published: September 2013

O objetivo deste trabalho é definir quais características de customização em massa (CM) presentes em sistemas de manufatura podem ser priorizadas no projeto de serviços customizados em massa. Propõe-se uma classificação de importância de características de customização a serem priorizadas na implementação de serviços customizados, tendo-se como critérios os habilitadores de CM e os habilitadores de serviços combinados através de uma matriz de relacionamentos característica do QFD (desdobramento da função qualidade) e corrigidos, a partir da ponderação dos gestores do serviço, usando-se um procedimento de QFD reverso. No final do estudo foi possível determinar as características prioritárias do serviço customizado em massa. Dois casos de estudo foram realizados para exemplificar a operacionalização da metodologia, um em uma distribuidora de energia elétrica e outro em uma universidade privada.
Homogeneidade espacial da precipitação pluvial na bacia hidrográfica do Rio Vacacaí, RS
Authors: Buriol Galileo Adeli , Stefanel Valduíno , Swarowsky Alexandre , Cademartori Rafael Tatsch de Oliveira
Published: September 2013

O objetivo, neste trabalho, foi determinar o número mínimo de anos com observações necessários para a obtenção de valores médios dos totais mensais de precipitação pluvial consistentes e a área de abrangência das estações pluviométricas, localizadas na bacia hidrográfica do Rio Vacacaí, estado do Rio Grande do Sul. Foram utilizadas as séries históricas de dados dos totais mensais de 13 estações pluviométricas localizadas na área e no entorno da referida bacia hidrográfica. O número mínimo de anos foi calculado pela relação entre o número de anos com observações e a estabilidade dos coeficientes de determinação. A abrangência das estações foi determinada pela relação dos coeficientes de determinação dos totais mensais de precipitação pluvial entre cada estação e a estação base, no caso Santa Maria, e as distâncias lineares entre a estação base e essas estações. A partir dessas equações, foram determinadas as distâncias entre estações em que há 80%, 85%, 90%, 95% e 99% de concordância dos valores. Constatou-se que, para ter uma razoável precisão nos totais mensais de precipitação pluvial na área da bacia hidrográfica do Rio Vacacaí, são necessários em torno de 30 a 40 anos de observação e que, nos meses de dezembro, janeiro e fevereiro, a abrangência das estações pluviométricas é menor do que 1,0km e nos outros meses uma concordância de 99% é obtida para distâncias de 1,3 a 2,2km, de 95% para distâncias de 6,3 a 11,1km e de 90% para distâncias de 12,5 a 22,2km.
Lukács e Marx contra o "ecologismo acrítico": por uma ética ambiental materialista
Authors: Medeiros João Leonardo , Barreto Eduardo Sá
Published: September 2013

O artigo desenvolve uma crítica às concepções conservadoras da ecologia, partindo de uma reinterpretação da teoria do valor de Marx baseada na obra de G. Lukács. São enfatizadas, nesta crítica, as implicações dessas concepções para o plano da ética.
Restrição externa, nível da taxa real de câmbio e crescimento em um modelo com progresso técnico endógeno
Authors: Missio Fabricio Jose , Jayme Jr. Frederico G.
Published: September 2013

O objetivo deste trabalho é apresentar considerações preliminares da relação entre nível da taxa real de câmbio, restrição externa e crescimento econômico a partir de um modelo formal que considera duas regiões, uma desenvolvida e outra em desenvolvimento, que interagem via comércio internacional. Admite-se que a restrição externa atue sobre a economia em desenvolvimento e que esta é afetada por variações no nível da taxa real de câmbio, uma vez que essas variações alteram a distribuição funcional da renda e, com isso, as decisões planejadas dos gastos em investimento e inovação das empresas. As conclusões caminham no sentido de mostrar que variações no nível da taxa real de câmbio têm efeitos sobre o crescimento econômico de longo prazo dos países em desenvolvimento.
Hibridismo na música instrumental do Grupo Medusa: associação de gêneros musicais distintos em Pé no chão
Authors: Freire Guilherme Araújo , Santos Rafael dos
Published: September 2013

Na década de 1980, o jazz fusion tinha grande repercussão internacional. Baseando-se na mistura das linguagens musicais do jazz com outros gêneros, o estilo incorporava construções harmônicas modais associadas ao uso da tecnologia a favor de uma busca a novos timbres. No Brasil, era visto como símbolo de modernidade e considerado como vanguarda musical pela crítica especializada, influenciando sensivelmente grupos de música instrumental. Este estudo tem como foco a produção musical do Grupo Medusa, formado na cidade São Paulo por músicos instrumentistas renomados do cenário da música popular brasileira. Através da análise dos aspectos rítmicos, melódicos, harmônicos e estruturais da música Pé no Chão, pretende-se compreender o modo pelo qual o Grupo Medusa articula elementos da linguagem musical de gêneros populares brasileiros e norte-americanos, obtendo uma sonoridade híbrida e, buscando também identificar apropriações de procedimentos musicais do fusion realizadas.
Management of dysphagia in Parkinson's disease and amyotrophic lateral sclerosis
Authors: Luchesi Karen Fontes , Kitamura Satoshi , Mourão Lucia Figueiredo
Published: September 2013

PURPOSE: To describe swallowing management in patients with amyotrophic lateral sclerosis (ALS) and Parkinson' disease (PD), to investigate whether physiopathology determines the choice of therapeutic approaches, and to investigate whether the disease duration modifies the therapeutic approaches. METHODS: This is a long-term study comprising 24 patients with idiopathic PD and 27 patients with ALS. The patients were followed-up in a dysphagia outpatient clinic between 2006 and 2011. The patients underwent clinic evaluation and Fiberoptic Endoscopic Evaluation of Swallowing, Functional Oral Intake Scale, and therapeutic intervention every 3 months. The swallowing management was based on orientation about the adequate food consistency and volume, besides the necessary maneuvers or exercises to improve swallowing functionality. An exploratory analysis of data was used to investigate associations between the groups of disease (PD or ALS) and clinic aspects and to know about the association between the groups of diseases and the application of maneuver or exercises over the follow-up. RESULTS: The most frequent recommended maneuvers in PD were bolus effect (83.3%), bolus consistency (79.2%), and swallowing frequency (79%). To patients with ALS, the bolus consistency (92%) and the bolus effect (74.1%) were more recommended. Strengthening-tongue (p=0.01), tongue control (p=0.05), and vocal exercises (p<0.001) were significantly more recommended in PD than in ALS. CONCLUSION: Compensatory and sensorial maneuvers are more recommended to rehabilitee program in both diseases. The physiopathology of the diseases determined the choice of therapeutic approaches. The disease duration of the patients did not interfere directly in the therapeutic approaches.
Lower Lip Pits: Van der Woude or Kabuki Syndrome?
Authors: David-Paloyo Ferri P. , Yang Xuecai , Lin Ju-Li , Wong Fen-Hwa , Wu-Chou Yah-Huei , Lo Lun-Jou
Published: October 2013

Kabuki syndrome (KS) is a multiple congenital anomaly/mental retardation syndrome with characteristic facial features. Despite more than 350 documented cases and recent correlation of MLL2 mutations as a genetic cause, its full clinical spectrum is still being defined. This report describes two patients who were initially diagnosed with Van der Woude syndrome (VWS) based on the presence of lower lip pits. However, this finding can occur with KS, albeit infrequently. For patients with lower lip pits, a thorough evaluation should be made to distinguish between VWS and KS, as there are differences in long-term prognosis.
Cytocompatibility of magnesium alloys with adult human endothelial cells
Authors: Niederlaender Jan , Rudi Philipp , Schweizer Ernst , Post Marcell , Schille Christine , Krajewski Stefanie , Wendel Hans P. , Geis-Gerstorfer Juergen
Published: October 2013

Biodegradable materials such as magnesium alloys have raised great interest in the last few years, since long-term implants such as intravascular stents are associated with various side effects. However, ions released from these alloys can exhibit cytotoxicity, which may have a severe impact on healing after implantation. The authors investigated the cytological effects of eight different magnesium alloys containing varying amounts of aluminum, zinc, neodymium and yttrium. Magnesium alloys were incubated either directly or indirectly with the endothelial cell line EA.Hy926 or primary endothelial cells from different patients, and cell viability was measured. In addition, the concentrations of released metal ions from the alloys were determined. Dependent on the magnesium alloys used and the incubation period, direct or indirect contact with endothelial cells led to various reactions in cell viability. Only the MgAl9Zn1alloy was found to exhibit tolerable cytotoxicity on all endothelial cells tested. The in vitro study revealed that the cytocompatibility of biodegradable magnesium alloys is not predictable only by determining the ion release or by testing the alloys with immortalized cell lines. These data suggest that cytocompatibility properties of new biodegradable material should be tested using primary cells of various donors in order to guarantee safe in vivo application and avoid interindividual differences.
A hierarchical Bayesian model for embedding larval drift and habitat models in integrated life cycles for exploited fish
Authors: Rochette S. , Le Pape O. , Vigneau J. , Rivot E.
Published: October 2013

This paper proposes a hierarchical Bayesian framework for modeling the life cycle of marine exploited fish with a spatial perspective. The application was developed for a nursery‐dependent fish species, the common sole (Solea solea), on the Eastern Channel population (Western Europe). The approach combined processes of different natures and various sources of observations within an integrated framework for life‐cycle modeling: (1) outputs of an individual‐based model for larval drift and survival that provided yearly estimates of the dispersion and mortality of eggs and larvae, from spawning grounds to settlement in several coastal nurseries; (2) a habitat suitability model, based on juvenile trawl surveys coupled with a geographic information system, to estimate juvenile densities and surface areas of suitable juvenile habitat in each nursery sector; (3) a statistical catch‐at‐age model for the estimation of the numbers‐at‐age and the fishing mortality on subadults and adults. The approach provided estimates of hidden variables and parameters of key biological significance. A simulation approach provided insight to the robustness of the approach when only weak data are available. Estimates of spawning biomass, fishing mortality, and recruitment were close to the estimations derived from stock‐assessment working groups. In addition, the model quantified mortality along the life cycle, and estimated site‐specific density‐dependent mortalities between settled larvae and age‐0 juveniles in each nursery ground. This provided a better understanding of the productivity and the specific contribution of each nursery ground toward recruitment and population renewal. Perspectives include further development of the modeling framework on the common sole and applications to other fish species to disentangle the effects of multiple interacting stress factors (e.g., estuarine and coastal nursery habitat degradation, fishing pressure) on population renewal and to develop risk analysis in the context of marine spatial planning for sustainable management of fish resources.
Interactions between conventional and organic farming for biocontrol services across the landscape
Authors: Bianchi F. J. J. A , Ives A. R. , Schellhorn N. A.
Published: October 2013

While the area of organic crop production increases at a global scale, the potential interactions between pest management in organic and conventionally managed systems have so far received little attention. Here, we evaluate the landscape‐level co‐dependence of insecticide‐based and natural enemy‐based pest management using a simulation model for parasitoid–host interactions in landscapes consisting of conventionally and organically managed fields. In our simulations conventional management consists of broad‐spectrum or selective insecticide application, while organic management involves no insecticides. Simulations indicate that insecticide use can easily result in lose–lose scenarios whereby both organically and conventionally managed fields suffer from increased pest loads as compared to a scenario where no insecticides are used, but that under some conditions insecticide use can be compatible with biocontrol. Simulations also suggest that the pathway to achieve the insecticide reduction without triggering additional pest pressure is not straightforward, because increasing the proportion of organically managed fields or reducing the spray frequency in conventional fields can potentially give rise to dramatic increases in pest load. The disruptive effect of insecticide use, however, can be mitigated by spatially clustering organic fields and using selective insecticides, although the effectiveness of this mitigation depends on the behavioral traits of the biocontrol agents. Poorly dispersing parasitoids and parasitoids with high attack rates required a lower amount of organically managed fields for effective pest suppression. Our findings show that the transition from a landscape dominated by conventionally managed crops to organic management has potential pitfalls; intermediate levels of organic management may lead to higher pest burdens than either low or high adoption of organic management.
Stochastic Fusion of Information for Characterizing and Monitoring the Vadose Zone
Authors: Yeh Tian‐Chyi J. , Šimůnek Jirka
Published: October 2013

Inverse problems for hydrological processes in the vadose zone are often perceived as being ill posed and intractable. Consequently, solutions to the inverse problems are frequently subject to skepticism. In this paper, we examine the necessary and sufficient conditions for the inverse problems to be well posed and discuss difficulties associated with solving the inverse problems. We subsequently explain the need for a stochastic conceptualization of inverse problems of the vadose zone. Principles of geostatistically based inverse approaches, which rely on stochastic concepts, are then illustrated, including cokriging, a sequential linear estimator, and a successive linear estimator. We then discuss applications involved in the approaches to classical vadose zone inversion problems (using observed pressure heads, moisture contents, concentrations, and arrival times), hydraulic tomography, and electrical resistivity tomography for vadose zone characterization and monitoring. Finally, we present a stochastic information fusion technology that assimilates information from both unsaturated hydraulic tomography and electrical resistivity tomography. Preliminary results suggest that this fusion technology is a promising tool for effectively characterizing heterogeneity, monitoring processes in the vadose zone, and quantifying uncertainties associated with vadose zone characterization and monitoring.
Adaptive Grid Refinement in Numerical Models for Water Flow and Chemical Transport in Soil: A Review
Authors: Mansell R. S. , Ma Liwang , Ahuja L. R. , Bloom S. A.
Published: October 2013

Insufficient spatial or temporal resolution is a common source of errors in numerical solutions for both water flow and solute transport in the variably unsaturated vadose zone. Evaporation near the surface, as well as infiltration into initially dry soil profiles, typically create mobile local regions with large gradients of the pressure head. Convection‐dominant transport of solutes during water flow in soil also tends to create steep moving fronts of concentration with large localized concentration gradients. Groundwater flow and solute transport in highly heterogeneous aquifers similarly tend to be preferentially channeled through regions of high flow rates. Without due consideration of special resolution requirements for such critical cases of flow and transport, simulations using traditional finite difference (FDM) and finite element (FEM) numerical methods typically provide inaccurate solutions characterized by undesirable features such as oscillation and numerical dispersion. Incorporation of local adaptive grid refinement (LAGR) algorithms in numerical models for solving such cases is an effective approach that has been used to provide accurate numerical approximations by automated adjustment of local spatial resolution. Local error estimates are typically utilized to optimize spatial resolution. Definite advantages, as well as some limitations, exist for using LAGR algorithms in FDM and FEM numerical models for flow and transport in soils.
Water‐Retention of Fractal Soil Models Using Continuum Percolation Theory: Tests of Hanford Site Soils
Authors: Hunt Allen G. , Gee Glendon W.
Published: October 2013

For 43 Hanford site soils, we use fractal analysis and assume proportionality of pore radii to particle radii to generate water‐retention curves, h(θ), from particle‐size distributions. The air‐entry head is used as an adjustable parameter to optimize the fit to experimental data for h(θ). At a low moisture content, θd, the predicted and observed water‐retention curves deviate. It is shown here that the moisture content at which this deviation occurs is in most cases probably the same value, at which previous experiments found a vanishing of solute diffusion. Where this correlation is indicated, we interpret θd as a critical moisture content for percolation of capillary flow paths, and the relevance of other mechanisms of water transport, such as film flow, to equilibration at lower moisture contents. In other individual cases, however, the deviation is correlated with very low values of the hydraulic conductivity associated with capillary flow. In either case, we infer that the deviation from fractal predictions is due to the lack of equilibration of the medium. Our work thus exploits theoretical and analytical gains from percolation theory and fractal analysis to define the equilibrium limits on water retention curves.
New Field Method to Determine Streamflow Timing Using Electrical Resistance Sensors
Authors: Blasch Kyle W. , Ferré Ty P. A. , Christensen Allen H. , Hoffmann John P.
Published: October 2013

Electrical resistance (ER) sensors were constructed to monitor streambed saturation to infer ephemeral streamflow timing. The sensors were evaluated in an ephemeral stream through comparison with temperature‐based methods, a stream gauge, and soil water content sensors. The ER sensors were more accurate at estimating streamflow timing and the resultant data required less interpretation than data from temperature‐based methods. Accuracy was equivalent to timing methods using stream gauge and soil water content measurements. The ER sensors are advantageous for use in ephemeral stream channels because they are inexpensive, deployable above or below the sediment surface, insensitive to depth, and do not require connecting wires to an external datalogger or power source. On the basis of these results, we conclude that ER sensors may be used to monitor changes in soil water content within the vadose zone. Additionally, the sensors can be used to infer the presence of surface water in diversion canals, storm‐water sewers, and in the form of overland runoff.
The Early Development of TDR for Soil Measurements
Authors: Topp G. Clarke , Davis J. Les , Annan A. Peter
Published: October 2013

The early development of time‐domain reflectometry (TDR) for measuring water content in soils began somewhat by chance and continued almost in spite of the lack of support for the work from the sponsoring organizations. Following their first meeting, mutually supportive relationships quickly developed among the authors to sustain the research and development (R&D) program through the early difficult stages. The consistency across varied soils in the early findings buoyed up the authors' enthusiasm, but there was considerable reluctance by others to accept that one relative permittivity vs. water content relationship would apply as widely as claimed. The development of the first TDR instrument specifically for soil measurement highlighted a number of difficulties that may occur during the translation of scientific concepts and results to the instrumentation stage. An important method of dissemination of TDR results was the personal demonstration of the technique at conferences and workshops. These direct personal contacts often assisted others to pursue diverse applications, such as multiplexing for better spatial coverage, estimating liquid water in frozen soil, electrical conductivity, and solute movement. By 1987, TDR in soil had come of age with the presentation of five TDR papers from four nations at the Utah State Centennial Symposium. These experiences are offered as inspiration for others working on development research or perhaps as a warning of possible difficulties. In spite of which, this proved to be one of the most exciting and rewarding projects for the authors.
Development of Thermo‐Time Domain Reflectometry for Vadose Zone Measurements
Authors: Ren Tusheng , Ochsner Tyson E. , Horton Robert
Published: October 2013

Soil and environmental studies in the vadose zone are often restricted by the lack of equipment that can measure the variation of soil physical parameters in space and time. In this paper we demonstrate that thermo‐time domain reflectometry (thermo‐TDR) can be used for a wide range of soil physical measurements. The thermo‐TDR probe combines TDR and heat‐pulse technologies into a single probe. It allows measurements of volumetric soil water content (θ), temperature (T), electrical conductivity (EC), thermal conductivity (λ), thermal diffusivity (α), and volumetric heat capacity (ρc) at the same sampling positions simultaneously. Furthermore, other soil physical parameters, such as bulk density (ρb), air‐filled porosity (na), and degree of saturation (S), can be determined from their relationships with ρc and θ. We examined the performance of the thermo‐TDR using both published data and laboratory measurements on packed columns and intact cores from six soils of varying texture. The results show that the thermo‐TDR provides reliable measurements of θ, EC, ρc, λ, na, and S, but relatively large errors exist in ρb The average standard error between thermo‐TDR measurements and gravimetric measurements is 0.026 m3 m−3 for θ, 0.050 m3 m−3 for na, 0.069 for S, and 0.134 Mg m−3 for ρb The standard error between thermo‐TDR measurements and theoretical predictions of ρc is 0.134 MJ m−3 K−1 These promising findings coupled with the characteristics of small probe size and easy automation make the thermo‐TDR sensor an ideal tool for studying coupled flow processes in the vadose zone. Further improvements in probe design, waveform interpretation, and determination of effective probe length are also noted as steps toward improving accuracy and precision of future thermo‐TDR measurements.
Use of the Dual‐Probe Heat‐Pulse Technique to Monitor Soil Water Content in the Vadose Zone
Authors: Ochsner Tyson E. , Horton Robert , Ren Tusheng
Published: October 2013

The dual‐probe heat‐pulse (DPHP) technique is emerging as a useful technique for measuring soil volumetric water content (θ). However, few published data are available regarding the performance of the DPHP technique under field conditions. The objective of this study is to evaluate the effectiveness of the DPHP technique for measuring θ under field conditions. We used 24 DPHP sensors to monitor θ in a soybean [Glycine max (L.) Merr.] field during the 2001 and 2002 growing seasons. The DPHP sensors demonstrated durability in field conditions and clear sensitivity to temporal and spatial variations of θ at the scale of measurement. The mean θ measured by the DPHP sensors (θDPHP) was on average 0.040 m3 m−3 larger than the mean θ measured by soil sampling (θSS). The response of the DPHP sensors was linear. Regressions of θDPHP vs. θSS yielded r2 values of 0.949 and 0.843 at depths of 7.5 and 37.5 cm. The DPHP technique showed good resolution with RMSE values for the regression of 0.009 and 0.011 m3 m−3 at the two measurement depths. The slopes of the regressions were 0.75 rather than 1.0. Errors in θSS are a likely cause of this low slope. We shifted all the θ values for each sensor up or down by a constant value to make the first θ measurement from each sensor equal θ determined from soil sampling near that sensor at the time of installation. This simple matching point procedure improved the accuracy of the DPHP technique, resulting in a −0.024 m3 m−3 average difference between θDPHP and θSS Also, the matching point procedure markedly reduced the variability between sensors, reducing the average SD from 0.063 to 0.026 m3 m−3 This procedure requires no additional soil sampling and is recommended for field applications of the DPHP technique.
In Situ Measurement of Soil Heat Flux with the Gradient Method
Authors: Cobos Douglas R. , Baker John M.
Published: October 2013

The use of soil heat flux as a critical component of the surface energy balance is routine; however, its accurate quantification is not. The direct measurement of soil heat flux is generally accomplished with soil heat flux plates. However, the presence of heat flux plates causes perturbations in heat and fluid flow in the soil that may give rise to measurement errors. We describe here the direct measurement of soil heat flux with the gradient technique using a tri‐needle instrument, where soil heat flux is the product of the soil thermal conductivity measured by transient heating of the center needle and the soil temperature gradient measured between the outer needles. Soil heat fluxes measured this way were compared with those obtained from commercially available soil heat flux plates. Laboratory trials revealed good precision and accuracy (error generally <5%) in measurements of thermal conductivity and soil heat flux with the heated needle technique in a medium‐textured sand, but exposed occasional errors in the accurate determination of thermal conductivity arising from poor sensor‐soil thermal contact in a coarser medium. Extended field data in a finer‐textured soil showed good agreement among needle sensors and heat flux plates, and surprisingly did not reveal errors associated with fluid blockage by the heat flux plates. Our results indicate that the measurement of soil heat flux with the gradient technique with needle sensors is a viable alternative to heat flux plates, and may improve absolute accuracy of this measurement.