Current Work (current + work)

Distribution by Scientific Domains


Selected Abstracts


Sequential Monte Carlo methods for multi-aircraft trajectory prediction in air traffic management

INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 10 2010
I. Lymperopoulos
Abstract Accurate prediction of aircraft trajectories is an important part of decision support and automated tools in air traffic management. We demonstrate that by combining information from multiple aircraft at different locations and time instants, one can provide improved trajectory prediction (TP) accuracy. To perform multi-aircraft TP, we have at our disposal abundant data. We show how this multi-aircraft sensor fusion problem can be formulated as a high-dimensional state estimation problem. The high dimensionality of the problem and nonlinearities in aircraft dynamics and control prohibit the use of common filtering methods. We demonstrate the inefficiency of several sequential Monte Carlo algorithms on feasibility studies involving multiple aircraft. We then develop a novel particle filtering algorithm to exploit the structure of the problem and solve it in realistic scale situations. In all studies we assume that aircraft fly level (possibly at different altitudes) with known, constant, aircraft-dependent airspeeds and estimate the wind forecast errors based only on ground radar measurements. Current work concentrates on extending the algorithms to non-level flights, the joint estimation of wind forecast errors and the airspeed and mass of the different aircraft and the simultaneous fusion of airborne and ground radar measurements. Copyright © 2010 John Wiley & Sons, Ltd. [source]


A personal account of the role of peptide research in drug discovery: the case of hepatitis C,

JOURNAL OF PEPTIDE SCIENCE, Issue 1 2001
Antonello Pessi
Abstract Although peptides themselves are not usually the end products of a drug discovery effort, peptide research often plays a key role in many aspects of this process. This will be illustrated by reviewing the experience of peptide research carried out at IRBM in the course of our study of hepatitis C virus (HCV). The target of our work is the NS3/4A protease, which is essential for maturation of the viral polyprotein. After a thorough examination of its substrate specificity we fine-tuned several substrate-derived peptides for enzymology studies, high-throughput screening and as fluorescent probes for secondary binding assays. In the course of these studies we made the key observation: that the protease is inhibited by its own cleavage products. Single analog and combinatorial optimization then derived potent peptide inhibitors. The crucial role of the NS4A cofactor was also addressed. NS4A is a small transmembrane protein, whose central domain is the minimal region sufficient for enzyme activation. Structural studies were performed with a peptide corresponding to the minimal activation domain, with a series of product inhibitors and with both. We found that NS3/4A is an induced fit enzyme, requiring both the cofactor and the substrate to acquire its bioactive conformation; this explained some puzzling results of ,serine-trap' type inhibitors. A more complete study on NS3 activation, however, requires the availability of the full-length NS4A protein. This was prepared by native chemical ligation, after sequence engineering to enhance its solubility; structural studies are in progress. Current work is focused on the P, region of the substrate, which, at variance with the P region, is not used for ground state binding to the enzyme and might give rise to inhibitors showing novel interactions with the enzyme. Copyright © 2001 European Peptide Society and John Wiley & Sons, Ltd. [source]


Developing Language Awareness Materials for Nonlinguists: Lessons Learned from the Do You Speak American?

LINGUISTICS & LANGUAGE COMPASS (ELECTRONIC), Issue 3 2007
Curriculum Development Project
Current work in linguistics is not well represented in the school curriculum in the USA, partly because of a mismatch with traditional foci in the K-12 (kindergarten through twelfth grade) standard course of studies and because there are very few materials for teaching about the nature of language and language variation. This article sketches the process of developing curricular materials to accompany the 3-hour video documentary, Do You Speak American? and suggests some of the decisions that must be made in developing materials for educational settings concerning scientific knowledge about language. [source]


Preparation of parents by teaching of distraction techniques does not reduce child anxiety at anaesthetic induction.

PEDIATRIC ANESTHESIA, Issue 9 2002
A. Watson
Introduction For those children having surgery, induction of anaesthesia is one of the most stressful procedures the child experiences perioperatively. Current work has failed to show a benefit of parental presence at induction of anaesthesia for all children. The reasons for lack of effect may include the high anxiety levels of some parents and also that the role for parents at their child's induction is not delineated. The main aim of this study was to see if parental preparation by teaching of distraction techniques could reduce their child's anxiety during intravenous induction of anaesthesia. Methods After ethics committee approval 40 children aged 2,10 years old, ASA status I or II undergoing daycase surgery under general anaesthesia were enrolled into the study. To avoid possible confounding factors children with a history of previous, surgery, chronic illness or developmental delay were excluded form participation. No children were given sedative premedication. After written informed consent by the parent, each child and parent was randomly assigned to an intervention or control group. Parents in the intervention group received preparation from a play specialist working on the children's surgical ward. It involved preparation for events in the anaesthetic room and instruction on methods of distraction for their child during induction using novel toys, books or blowing bubbles appropriate to the child's age. Preoperative information collected included demographic and baseline data. The temperament of the child was measured using the EASI (Emotionality, Activity, Sociability, Impulsivity) instrument of child temperament(l). In the anaesthetic room all children were planned to have intravenous induction of anaesthesia after prior application of EMLA cream. Anxiety of the child was measured by the modified Yale Preoperative Anxiety Scale (mYPAS)(2) by a blinded independent observer at three time points: entrance to the anaesthetic room, intravenous cannulation and at anaesthesia induction. Cooperation of the child was measured by the Induction Compliance Checklist (ICC) by the same observer (3). Postoperative data collected included parental satisfaction and anxiety scores measured by the Stait Trait Anxiety Inventory (STAI)(4) and at one week the behaviour of the child was measured Using the Posthospitalisation Behavioural Questionnaire (PHBQ)(5). Normally distributed data were analysed by a two-sample t-test, categorical data by Pearson's Chi-squared test and non-parametric data by the Wilcoxon rank-sum test. Results One parent withdrew after enrolment. This left 22 children in the control group and 17 in the intervention group. There were no significant differences in demographic and baseline data of the children between the two groups including ethnic origin, number of siblings, birth order of the child, recent stressful events in the child's life, previous hospital admissions and the temperament of the child. Parent demographics were also similar between groups including parent's age, sex, relationship to child and level of education. There were no significant differences in child anxiety or cooperation during induction measured by mYPAS and ICC between the control and intervention groups. More parents in the preparation group distracted their child than those without preparation but this did not reach significance. Parental anxiety immediately postinduction was similar between groups as was the level of parental satisfaction. The incidence of development of new negative postoperative behaviour of the child at one week was not significantly different between groups. Discussion This study shows that giving an active role for parents in the induction room, particularly by instructing them on distracting techniques for their child, does not reduce their child's anxiety compared to conventional parental presence. We conclude resources should not be directed at this type of parental preparation. Further work should examine the usefulness of distraction by nursing staff or play specialists during anaesthetic induction. [source]


The role of integrated geophysical survey methods in the assessment of archaeological landscapes: the case of Portus

ARCHAEOLOGICAL PROSPECTION, Issue 3 2009
Simon Keay
Abstract The regular application of geophysical, geochemical and topographical survey techniques to evaluate archaeological sites is well established as a method for locating, defining and mapping buried archaeological materials. However, it is not always feasible to apply a range of different methods over a particular site or landscape due to constraints in time or funding. This paper addresses the integrated application of a variety of survey techniques over different sites and landscapes in Italy and elsewhere, focusing on the recent results from the ongoing survey and excavations at Portus, the port of Imperial Rome. An integration of methods, including magnetometry, resistance survey, ground-penetrating radar (GPR) and electrical resistivity tomography (ERT) has been used at the site to fulfil a number of different research objectives. Results of the magnetometer survey have successfully recorded the nature and extent of archaeological material over an area of 220,ha, allowing a plan of the port and related structures to be produced and variations in archaeological potential across the entire landscape to be assessed. The integration of several techniques in one area of the site between the Porto di Claudio and the Porto di Traiano has mapped the structural remains of this area of the port prior to and during investigation of the zone through excavation. Current work on the geophysical survey data, using different software programs for the processing of survey data and merging different datasets using geographical information system packages, has allowed the results of the work to be visualized and presented to archaeologists in a comprehensive and unambiguous fashion, facilitating the future management and preservation of the site. In addition ongoing research is using different statistical and visual methods of integration to refine the archaeological interpretation of the study area. Copyright © 2009 John Wiley & Sons, Ltd. [source]


Ecological perspectives on the sequenced genome collection

ECOLOGY LETTERS, Issue 12 2005
Jennifer B. Hughes Martiny
Abstract Our complete genome collection is one of our most valuable biological resources. A key challenge for the future is the interpretation of these genomes from an ecological perspective. In this review, we discuss current work at this increasingly important interface. In particular, we review ongoing work aimed at developing high quality data sets that combine ecological, environmental, evolutionary and genomic information. Such data will help to identify biases in the sequence collection and facilitate future discoveries about the nature of ecological adaptation at the genome level. These efforts will be greatly enhanced by the contributions of ecologists. [source]


DERRIDA'S RIGHT TO PHILOSOPHY, THEN AND NOW

EDUCATIONAL THEORY, Issue 3 2009
John Willinsky
In this essay, a tribute to Jacques Derrida's educational efforts at expanding access to current work in philosophy, John Willinsky examines his efforts as both a public right and an element of academic freedom that bear on the open access movement today. Willinsky covers Derrida's extension and outreach work with the Groupe de Recherches pour l'Enseignement de la Philosophie in the 1970s and a decade later with Collčge International de Philosophie that provided public access to ongoing and leading-edge philosophical work, as well as supporting the teaching of philosophy in the schools. Willinsky also relates Derrida's dedicated, practical educational work, his historical analysis of Descartes's decision to write in French, and more recent initiatives that are using Internet technologies to increase public and educational access to published scholarly work in the humanities in a very similar spirit. [source]


Coaxial Aerodynamically Assisted Bio-jets: A Versatile Paradigm for Directly Engineering Living Primary Organisms

ENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 6 2007
S. Irvine
Abstract In this paper, a coaxial jetting methodology is demonstrated as a first example (non-electric field driven) completely run by aerodynamic forces which are brought about by the application of a differential pressure for the safe handling of primary living organisms by means of jets as encapsulated droplets. Previously this jetting technique in this configuration has only been investigated for processing combinations of liquid-liquid and liquid-gas systems. These developmental studies into aerodynamically assisted jets (AAJ) have unearthed a versatile bio-jetting approach referred to here as coaxial aerodynamically assisted bio-jetting (CAABJ). In the current work, this flexible approach is demonstrated to handle two primary cell types for drop-and-placing onto several different substrates. Furthermore, the study assesses cellular viability of the post-treated cells in comparison to controls by way of flow cytometry. These first steps demonstrate the promise this protocol has in exploring the creation of biologically viable structures to form encapsulations of cells which would be useful as a direct tissue engineering to the immuno-hinding methodology in bio-repair and therapeutics. Therefore, these investigations place CAABJ into the cell jetting pursuit together with bio-electrosprays, which will undergo an explosive developmental research. [source]


Central nervous system neurons acquire mast cell products via transgranulation

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 9 2005
M. Wilhelm
Abstract Resting and actively degranulating mast cells are found on the brain side of the blood,brain barrier. In the periphery, exocytosis of mast cell granules results in the release of soluble mediators and insoluble granule remnants. These mast cell constituents are found in a variety of nearby cell types, acquired by fusion of granule and cellular membranes or by cellular capture of mast cell granule remnants. These phenomena have not been studied in the brain. In the current work, light and electron microscopic studies of the medial habenula of the dove brain revealed that mast cell-derived material can enter neurons in three ways: by direct fusion of the granule and plasma membranes (mast cell and neuron); by capture of insoluble granule remnants and, potentially, via receptor-mediated endocytosis of gonadotropin-releasing hormone, a soluble mediator derived from the mast cell. These processes result in differential subcellular localization of mast cell material in neurons, including free in the neuronal cytoplasm, membrane-bound in granule-like compartments or in association with small vesicles and the trans-Golgi network. Capture of granule remnants is the most frequently observed form of neuronal acquisition of mast cell products and correlates quantitatively with mast cells undergoing piecemeal degranulation. The present study indicates that mast cell-derived products can enter neurons, a process termed transgranulation, indicating a novel form of brain,immune system communication. [source]


Fracture analysis of composite co-cured structural joints using decohesion elements

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 9 2004
P. P. CAMANHO
ABSTRACT Delamination is one of the predominant forms of failure in laminated composite structures, especially when there is no reinforcement in the thickness direction. To develop composite structures that are more damage tolerant, it is necessary to understand how delamination develops, and how it can affect the residual performance. A number of factors such as residual thermal stresses, matrix-curing shrinkage and manufacturing defects affect how damage will grow in a composite structure. It is important to develop computationally efficient analysis methods that can account for all such factors. The objective of the current work is to apply a newly developed decohesion element to investigate the debond strength of skin-stiffener composite specimens. The process of initiation of delaminations and the propagation of delamination fronts is investigated. The numerical predictions are compared with published experimental results. [source]


Biochemical characterization and inhibitor discovery of shikimate dehydrogenase from Helicobacter pylori

FEBS JOURNAL, Issue 20 2006
Cong Han
Shikimate dehydrogenase (SDH) is the fourth enzyme involved in the shikimate pathway. It catalyzes the NADPH-dependent reduction of 3-dehydroshikimate to shikimate, and has been developed as a promising target for the discovery of antimicrobial agent. In this report, we identified a new aroE gene encoding SDH from Helicobacter pylori strain SS1. The recombinant H. pylori shikimate dehydrogenase (HpSDH) was cloned, expressed, and purified in Escherichia coli system. The enzymatic characterization of HpSDH demonstrates its activity with kcat of 7.7 s,1 and Km of 0.148 mm toward shikimate, kcat of 7.1 s,1 and Km of 0.182 mm toward NADP, kcat of 5.2 s,1 and Km of 2.9 mm toward NAD. The optimum pH of the enzyme activity is between 8.0 and 9.0, and the optimum temperature is around 60 °C. Using high throughput screening against our laboratory chemical library, five compounds, curcumin (1), 3-(2-naphthyloxy)-4-oxo-2-(trifluoromethyl)-4H -chromen-7-yl 3-chlorobenzoate (2), butyl 2-{[3-(2-naphthyloxy)-4-oxo-2-(trifluoromethyl)-4H -chromen-7-yl]oxy}propanoate (3), 2-({2-[(2-{[2-(2,3-dimethylanilino)-2-oxoethyl]sulfanyl}-1,3-benzothiazol-6-yl)amino]-2-oxoethyl}sulfanyl)- N -(2-naphthyl)acetamide (4), and maesaquinone diacetate (5) were discovered as HpSDH inhibitors with IC50 values of 15.4, 3.9, 13.4, 2.9, and 3.5 µm, respectively. Further investigation indicates that compounds 1, 2, 3, and 5 demonstrate noncompetitive inhibition pattern, and compound 4 displays competitive inhibition pattern with respect to shikimate. Compounds 1, 4, and 5 display noncompetitive inhibition mode, and compounds 2 and 3 show competitive inhibition mode with respect to NADP. Antibacterial assays demonstrate that compounds 1, 2, and 5 can inhibit the growth of H. pylori with MIC of 16, 16, and 32 µg·mL,1, respectively. This current work is expected to favor better understanding the features of SDH and provide useful information for the development of novel antibiotics to treat H. pylori -associated infection. [source]


Using Websites to Disseminate Research on Urban Spatialities

GEOGRAPHY COMPASS (ELECTRONIC), Issue 6 2009
Gillian Rose
This paper reviews a selection of websites that explore urban geographies. Many sites use the web as a depository for large amounts of research data. However, many are using websites to disseminate research findings, and the paper focuses on these. It suggests that, thus far, there are three significant ways in which urban researchers are exploiting the potentialities of web technologies to interpret urban spaces: by evoking a sense of the complexity of urban spatialities; by inviting site visitors to engage actively and performatively with the research materials; and by emphasising the sensory qualities of urban spaces. The paper discusses how one website in particular invites its visitors to engage with complex, sensory urban spatialities. The paper compares geographers' use of collage and montage as part of this discussion, and ends by reflecting on current work and commenting on its future development. [source]


Agency, Postmodernism, and the Causes of Change

HISTORY AND THEORY, Issue 4 2001
Michael L. Fitzhugh
This theme issue's call for papers notes that "several prevalent and influential historical practices of the last thirty years have limited agency's significance, . . . seeing the human as the patient of History rather than its agent." The questions implicit in this statement are nowhere more urgent than in those practices collectively known as the "linguistic turn." Yet such questions have been explored sparsely enough in relation to this movement that some adherents can still insist that the ideas they favor do not devalue agency, while many simply ignore the issue and incorporate agency as an integral part of their work. By examining a largely unremarked episode in Michel Foucault's highly influential thought and considering its connections to foundational assumptions of the linguistic turn, we seek to demonstrate in detail why the premises that underlie both structuralism and poststructuralism (the theoretical movements most deeply implicated in the direction the linguistic turn has taken in history) logically require the denial of agency as a causal force and ultimately compel the conclusion that no change can occur in realities as interpreted by humans. We illustrate the intractability of these logical problems by analyzing unsatisfactory defenses from some of the few linguistic-turn historians who have discussed relevant issues, after which we conclude by suggesting that attention to current work in linguistics and cognitive science may help resolve such difficulties. [source]


Scaffold Design and Manufacturing: From Concept to Clinic

ADVANCED MATERIALS, Issue 32-33 2009
Scott J. Hollister
Abstract Since Robert Langer and colleagues pioneered the concept of reconstructing tissue using cells transplanted on synthetic polymer matrices in the early 1990s, research in the field of tissue engineering and regenerative medicine has exploded. This is especially true in the development of new materials and structures that serve as scaffolds for tissue reconstruction. The basic tenet of the last two decades holds scaffolds as degradable materials providing temporary function while enhancing tissue regeneration through the delivery of biologics. Although a number of new scaffolding materials and structures have been developed in research laboratories, the application of such materials practice even has been extremely limited. This paper argues that better integration of all these factors is needed to bring scaffolds from "concept to clinic". It reviews current work in all these areas and suggests where future work and funding is needed. [source]


Remeshing for metal forming simulations,Part I: Two-dimensional quadrilateral remeshing

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 11 2002
Dae-Young Kwak
Abstract In this paper, a general framework of practical two-dimensional quadrilateral remeshing, which includes the determination of remeshing time, automatic quadrilateral mesh generation, and data transfer process, will be formulated. In particular, the current work contains new algorithms of mesh density specification according to the distribution of effective strain-rate gradients, mesh density smoothing by fast Fourier transform (FFT) and low-pass filtering techniques, coarsening it by node placement scheme, and a modified Laplacian mesh smoothing technique. The efficiency of the developed remeshing scheme was tested through three practical two-dimensional metal forming simulations. The results clearly indicate that the algorithms proposed in this study make it possible to simulate two-dimensional metal forming problems efficiently and automatically. Copyright © 2002 John Wiley & Sons, Ltd. [source]


Experimental investigation of the intermediates of isooctane during ignition

INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 9 2007
X. He
Direct measurements of intermediates of ignition are challenging experimental objectives, yet such measurements are critical for understanding fuel decomposition and oxidation pathways. In the current work, a new gas-sampling system is used to provide quantitative discrete measurements of 30 hydrocarbon and oxygenate species during rapid compression facility studies of isooctane ignition. Two target conditions and equivalence ratios (based on molar fuel to oxygen ratio) were studied (P = 5.2 atm, T = 1000 K, , = 0.4 and P = 4.8 atm, T = 975 K, , = 1.2). The results are compared with model predictions that use the detailed reaction mechanism developed by Curran et al. (Combust Flame 2002, 129, 253,280). In general, the model predictions are in excellent agreement with the experimental data, including several trace species. Isobutene (i-C4H8) and propene (C3H6) were the major olefin species identified in the experiments. The results are consistent with an intermediate temperature reaction path sequence, where isooctane is consumed by H-atom abstraction to yield isooctyl radicals that undergo ,-scission to form olefin and alkyl radical species. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 498,517, 2007 [source]


Pre-handover signalling for QoS aware mobility management

INTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 6 2004
Hakima Chaouchi
In this paper we present a new approach to provide fast handover in Mobile IP. A new Pre-Handover Signalling (PHS) protocol is proposed to allow the network to achieve accurate handover decisions considering different constraints such as QoS, load balancing in the base stations, the user profile, the mobile node service requirements, etc. In addition we propose to minimize the time discovery of the new base station in order to minimize the handover latency. We propose to start the PHS as soon as the mobile node crosses a predefined critical zone area in its current location, this signalling will provide a list of candidate cells to the mobile node with corresponding priorities; the mobile node will select the highest priority base station as soon as the layer two handover occurs. We propose in the current work to use an extension of COPS (Common Open Policy Service) to support the proposed PHS mechanism and overcome the blind handover decisions of Mobile IP and improve the handover performance.,Copyright © 2004 John Wiley & Sons, Ltd. [source]


Evaluation of numerical simulation methods in reactive extrusion

ADVANCES IN POLYMER TECHNOLOGY, Issue 3 2005
Linjie Zhu
Abstract Reactive extrusion is a complex process, and numerical simulation is an important method in optimizing operational parameters. In the current work, two different simulation methods, one-dimensional (1D) model and three-dimensional (3D) model, were introduced to predict the polymerization of ,-caprolactone in fully filled screw elements. The predicted results of polymerization progression under different simulation conditions based on these two methods were compared. The simulation results show that the simplifications and assumptions in 1D model make it difficult to capture the complex mixing mechanism, heat generation, and heat loss in reactive extrusion. 1D model is feasible only under particular conditions, such as low screw rotating speed, small heat from reaction, and small screw diameter, whereas 3D model is a more powerful simulation tool for much wider processing conditions. © 2005 Wiley Periodicals, Inc. Adv Polym Techn 24: 183,193, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20041 [source]


The effect of viscosity on surface tension measurements by the drop weight method

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007
T. Kaully
Abstract Viscosity is one of the parameters affecting the measured surface tension, as fluid mechanics affects the measurement process using conventional methods. Several methods including the selected planes (SPM) and WDSM which combines the weight drop method (WDM) and SPM, are applied to surface tension measurement of high viscous liquids. Yet, none of them treats the viscosity effect separately. The current publication presents a simple, easy to apply empirical approach of satisfactory accuracy, for evaluation of surface tension of liquids having wide range of viscosities up to 10 Pa s. The proposed method is based on Tate's law and the "drop weight" method using calibration curves of known liquids having similar surface tensions but different viscosities. Drop weight of liquids having viscosity ,0.05 Pa s, was found to be significantly affected by the liquid viscosity. The shape factor, f, of high viscosity liquids was found to correlate linearly with the logarithm of viscosity, pointing the importance of viscosity correction. The experimental correlation presented in the current work can be used as a tool for the evaluation of surface tension for high viscosity liquids such as prepolymers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source]


Caldesmon is a cytoskeletal target for PKC in endothelium

JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 6 2006
Natalia V. Bogatcheva
Abstract We have previously shown that treatment of bovine endothelial cell (EC) monolayers with phorbol myristate acetate (PMA) leads to the thinning of cortical actin ring and rearrangement of the cytoskeleton into a grid-like structure, concomitant with the loss of endothelial barrier function. In the current work, we focused on caldesmon, a cytoskeletal protein, regulating actomyosin interaction. We hypothesized that protein kinase C (PKC) activation by PMA leads to the changes in caldesmon properties such as phosphorylation and cellular localization. We demonstrate here that PMA induces both myosin and caldesmon redistribution from cortical ring into the grid-like network. However, the initial step of PMA-induced actin and myosin redistribution is not followed by caldesmon redistribution. Co-immunoprecipitation experiments revealed that short-term PMA (5 min) treatment leads to the weakening of caldesmon ability to bind actin and, to the lesser extent, myosin. Prolonged incubation (15,60 min) with PMA, however, strengthens caldesmon complexes with actin and myosin, which correlates with the grid-like actin network formation. PMA stimulation leads to an immediate increase in caldesmon Ser/Thr phosphorylation. This process occurs at sites distinct from the sites specific for ERK1/2 phosphorylation and correlates with caldesmon dissociation from the actomyosin complex. Inhibition of ERK-kinase MEK fails to abolish grid-like structure formation, although reducing PMA-induced weakening of the cortical actin ring, whereas inhibition of PKC reverses PMA-induced cytoskeletal rearrangement. Our results suggest that PKC-dependent phosphorylation of caldesmon is involved in PMA-mediated complex cytoskeletal changes leading to the EC barrier compromise. J. Cell. Biochem. 99: 1593,1605, 2006. © 2006 Wiley-Liss, Inc. [source]


The price paid for the second-order advantage when using the generalized rank annihilation method (GRAM)

JOURNAL OF CHEMOMETRICS, Issue 9 2001
Nicolaas (Klaas) M. Faber
Abstract In a ground-breaking paper, Linder and Sundberg developed a statistical framework for the calibration of bilinear data (Chemometrics Intell. Lab. Syst. 1998; 42: 159,178). Within this framework they formulated three different predictor construction methods (J. Chemometrics accepted), namely a so-called naive method, a least squares (LS) method and a refined version of the latter that takes account of the calibration uncertainty. They showed that the naive method is statistically less efficient than the others under the assumption of white noise. In the current work a close relationship is established between the generalized rank annihilation method (GRAM) and the naive method by comparing expressions for prediction variance. The main conclusion is that the relatively poor efficiency of GRAM is the price one pays for obtaining the second-order advantage with a single calibration sample. Copyright © 2001 John Wiley & Sons, Ltd. [source]


Agricultural robot for radicchio harvesting

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 6-7 2006
Mario M. Foglia
In the last few years, robotics has been increasingly adopted in agriculture to improve productivity and efficiency. This paper presents recent and current work at the Politecnico of Bari, in collaboration with the University of Lecce, in the field of agriculture robotics. A cost effective robotic arm is introduced for the harvesting of radicchio, which employs visual localization of the plants in the field. The proposed harvester is composed of a double four-bar linkage manipulator and a special gripper, which fulfills the requirement for a plant cut approximately 10 mm underground. Both manipulator and end-effector are pneumatically actuated, and the gripper works with flexible pneumatic muscles. The system employs computer vision to localize the plants in the field based on intelligent color filtering and morphological operations; we call this algorithm the radicchio visual localization (RVL). Details are provided for the functional and executive design of the robotic arm and its control system. Experimental results are discussed; obtained with a prototype operating in a laboratory testbed showing the feasibility of the system in localizing and harvesting radicchio plants. The performance of the RVL is analyzed in terms of accuracy, robustness to noises, and variations in lighting, and is also validated in field experiments. © 2006 Wiley Periodicals, Inc. [source]


Rules, Red Tape, and Paperwork: The Archeology of State Control over Migrants

JOURNAL OF HISTORICAL SOCIOLOGY, Issue 1 2008
DAVID COOK MARTÍN
How and with what consequences did state control over migration become acceptable and possible after the Great War? Existing studies have centered on core countries of immigration and thus underestimate the degree to which legitimate state capacities have developed in a political field spanning sending and receiving countries with similar designs on the same international migrants. Relying on archival research, and an examination of the migratory field constituted by two quintessential emigration countries (Italy and Spain), and a traditional immigration country (Argentina) since the mid-nineteenth century, this article argues that widespread acceptance of migration control as an administrative domain rightfully under states' purview, and the development of attendant capacities have derived from legal, organizational, and administrative mechanisms crafted by state actors in response to the challenges posed by mass migration. Concretely, these countries codified migration and nationality laws, built, took over, and revamped migration-related organizations, and administratively encaged mobile people through official paperwork. The nature of efforts to evade official checks on mobility implicitly signaled the acceptance of migration control as a bona fide administrative domain. In more routine migration management, states legitimate capacity has had unforeseen intermediate- and long-term consequences such as the subjection of migrants (and, because of ius sanguinis nationality laws, sometimes their descendants) to other states' administrative influence and the generation of conditions for dual citizenship. Study findings challenge scholarship that implicitly views states as constant factors conditioning migration flows, rather than as developing institutions with historically variable regulatory abilities and legitimacy. It extends current work by specifying mechanism used by state actors to establish migration as an accepted administrative domain. [source]


The radical scavenger CR-6 protects SH-SY5Y neuroblastoma cells from oxidative stress-induced apoptosis: effect on survival pathways

JOURNAL OF NEUROCHEMISTRY, Issue 3 2006
Nuria Sanvicens
Abstract Reactive oxygen species (ROS) and oxidative stress have long been linked to cell death of neurons in many neurodegenerative conditions. However, the exact molecular mechanisms triggered by oxidative stress in neurodegeneration are at present unclear. In the current work we have used the human neuroblastoma SH-SY5Y cell line as a model for studying the molecular events occurring after inducing apoptosis with H2O2. We show that treatment of SH-SY5Y cells with H2O2 up-regulates survival pathways during early stages of apoptosis. Subsequently, the decline of anti-apoptotic protein levels leads to the activation of the calcium-dependent proteases calpains and the cysteine proteases caspases. Additionally, we demonstrate that CR-6 (3,4-dihydro-6-hydroxy-7-methoxy-2,2-dimethyl-1(2H)-benzopyran) acts as a scavenger of ROS and prevents apoptosis by enhancing and prolonging up-regulation of survival pathways. Furthermore, we show that pre-treatment of SH-SY5Y cells with a cocktail containing CR-6, the pan-caspase inhibitor zVAD-fmk (zVal-Ala-Asp-fluoro-methylketone) and the calpain inhibitor SJA6017 confers almost total protection against apoptosis. In summary, the present work characterizes the molecular mechanisms involved in oxidative stress-induced apoptosis in SH-SY5Y cells. Our findings highlight the relevance of CR-6, alone or in combination with other drugs, as potential therapeutic strategy for the treatment of neurodegenerative diseases. [source]


Preconditioning with thrombin can be protective or worsen damage after endothelin-1-induced focal ischemia in rats

JOURNAL OF NEUROSCIENCE RESEARCH, Issue 3 2006
Petra Henrich-Noack
Abstract The serine protease thrombin has shown direct neuroprotective and neurotoxic effects on brain tissue in cerebral ischemia. Previous data suggested that thrombin-induced protection in vivo can be achieved by preconditioning rather than by acute treatment. In the current work, we used a model of mild ischemia to investigate the effects of preischemic intracerebral thrombin injection on neural damage. By intracerebral injection of endothelin-1 in freely moving animals, we achieved middle cerebral artery occlusion (MCAO), and 7 days postischemia we performed histological quantification of the infarct areas. Thrombin was injected as a preconditioning stimulus intracerebrally 7 days or 2 and 3 days before ischemia. For acute treatment, thrombin was injected 20 min before MCAO. Thrombin induced significant neuroprotection when given 7 days before endothelin-1-induced MCAO but was deleterious when given 2 and 3 days before the insult. The deleterious effect was not seen when thrombin was given acutely before ischemia. Our data demonstrate that preconditioning with thrombin can protect against damage or worsen ischemic damage. Its effect depended on the time interval between thrombin injection and insult. A low dose of thrombin did not induce a major deleterious effect in the acute phase of the infarct development after mild transient ischemia. © 2006 Wiley-Liss, Inc. [source]


Two tachykinin-like peptides from skin secretions of Danio rerio

JOURNAL OF PEPTIDE SCIENCE, Issue 2 2010
Xuhua Mi
Abstract Tachykinin perform multiple physiological functions such as smoothing muscle contraction, vasodilation, inflammation, the processing of nerve signal, neuroprotection and neurodegeneration. Two novel tachykinin-like peptides named tachykinin-DR1 and -DR2 were identified from skin secretions of Danio rerio in current work. Their amino acid sequences were determined as SKSQHFHGLM-NH2 and NKGEIFVGLM-NH2, respectively. They share a conserved FXGLM-NH2C -terminal consensus motif. By cDNA cloning, the precursor encoding both tachykinin-DR1 and -DR2 was screened from the skin cDNA library of D. rerio. Tachykinin-DR1 and -DR2 share the same precursor, which is composed of 108 amino acid (aa) residues. Regarding the biological activity, tachykinin-DRs could induce the contraction of isolated strips of guinea pig ileum just like other tackykinins. To our best knowledge, this is the first report of tachykinin from fish skin. Copyright © 2009 European Peptide Society and John Wiley & Sons, Ltd. [source]


Determination of gastrodin and vanillyl alcohol in Gastrodia elata Blume by pressurized liquid extraction at room temperature

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 13 2007
Eng Shi Ong
Abstract Pressurized liquid extraction (PLE) at room temperature with a laboratory-assembled system was applied for the extraction of gastrodin (GA) and vanillyl alcohol (VA) in Gastrodia elata Blume. The proposed system setup for this current work was simpler as no heating and backpressure regulator was required. Extraction with PLE was carried out dynamically at a flow rate of 1.5 mL/min, at room temperature, under an applied pressure of 10,20 bars with an extraction time of 40,50 min. The extraction efficiencies of the proposed method using 20% aqueous ethanol were compared with heating under reflux using organic solvents such as methanol and ethanol/water (20:80) for different batches of medicinal plant materials. For the determination of GA and VA in G. elata Blume, the extraction efficiencies of PLE at room temperature were observed to be comparable with heating under reflux. The method precision was found to vary from 1.6 to 8.6% (RSD, n = 6) on different days. The marker compounds present in the various medicinal plant extracts were determined by gradient elution HPLC and HPLC/MS/MS. Our work demonstrated the possibility of implementation of PLE at room temperature and the advantages of minimizing the use of organic solvents in the extraction process. [source]


Evaluation of HPLC columns: A study on surface homogeneity of chemically bonded stationary phases

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 3-4 2003
Bogus, aw Buszewski
Abstract The aim of the current work is to study the heterogeneity of the adsorbent surface on the basis of physicochemical investigations and chromatographic tests. A series of packing materials with octadecyl chains chemically bonded to a silica matrix were prepared for this purpose. The surface and structural properties of bare silica and silica-based octadecyl phases were characterized by porosimetry, elemental analysis, 29Si CP/MAS NMR, etc. The most advanced characterization methods based on adsorption microcalorimetry (heat of wetting) measurements were employed to obtain information about the heterogeneity and topography of unmodified and modified silica gel. For the chromatographic study, these phases were evaluated on the basis of the retention data under non-aqueous conditions. A test series of solutes with various chemical properties, such as pK a values, was used. It was found that heterogeneity of the packing surface results in low HPLC resolution. Use of a non-aqueous mobile phase (n -hexane) reduces analytical interference by eliminating hydrophobic interactions between alkyl ligands and the analyte. [source]


Revealing Concealable Stigmatized Identities: The Impact of Disclosure Motivations and Positive First-Disclosure Experiences on Fear of Disclosure and Well-Being

JOURNAL OF SOCIAL ISSUES, Issue 3 2010
Stephenie R. Chaudoir
People who live with concealable stigmatized identities face complex decisions regarding disclosure. In the current work, we examine how people's motivations for disclosing a concealable stigmatized identity for the first time affect the quality of their first-disclosure experiences and how these experiences, in turn, affect current well-being. Specifically, we found that people who disclosed for ecosystem, or other-focused, reasons report more positive first-disclosure experiences which, in turn, were related to higher current self-esteem. Analyses suggest that one reason why this first-disclosure experience is related to current well-being is because positive first-disclosure experiences may serve to lessen chronic fear of disclosure. Overall, these results highlight the importance of motivational antecedents for disclosure in impacting well-being and suggest that positive first-disclosure experiences may have psychological benefits over time because they increase level of trust in others. [source]


Thick Nb-Doped Bismuth Titanate Film with Controllable Grain Orientation

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2006
Weiwu Chen
In the current work, we reported a potential approach to obtain thick ceramic films with controllable grain orientation based on magnetic alignment and polymerization techniques. The slurry containing 40 vol% Bi4Ti2.96Nb0.04O12 (BINT) ceramic powder, monomer, initiator, and catalyst was drop coated on a Pt substrate and then moved into a vertical 10 T magnetic field. In 1,2 min, the ceramic particles were aligned by a strong magnetic force in slurry and then in situ locked by polymerization on the substrate. After sintering at 1000°C, a BINT ceramic film (50,80 ,m in thickness) with a highly a/b plane orientation was obtained. Theoretically, the grain orientation in the films can be easily controlled by adjusting the magnetic field direction. This approach is readily applicable to other materials with a non-cubic structure and is expected to facilitate the fast preparation of grain-oriented thick films. [source]