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Selected AbstractsA Multiresolution Model for Soft Objects Supporting Interactive Cuts and LacerationsCOMPUTER GRAPHICS FORUM, Issue 3 2000Fabio Ganovelli Performing a really interactive and physically-based simulation of complex soft objects is still an open problem in computer animation/simulation. Given the application domain of virtual surgery training, a complete model should be quite realistic, interactive and should enable the user to modify the topology of the objects. Recent papers propose the adoption of multiresolution techniques to optimize time performance by representing at high resolution only the object parts considered more important or critical. The speed up obtainable at simulation time are counterbalanced by the need of a preprocessing phase strongly dependent on the topology of the object, with the drawback that performing dynamic topology modification becomes a prohibitive issue. In this paper we present an approach that couples multiresolution and topological modifications, based on the adoption of a particle systems approach to the physical simulation. Our approach is based on a tetrahedral decomposition of the space, chosen both for its suitability to support a particle system and for the ready availability of many techniques recently proposed for the simplification and multiresolution management of 3D simplicial decompositions. The multiresolution simulation system is designed to ensure the required speedup and to support dynamic changes of the topology, e.g. due to cuts or lacerations of the represented tissue. [source] In vivo proton spectroscopy without solvent suppressionCONCEPTS IN MAGNETIC RESONANCE, Issue 4 2001David B. Clayton Abstract In 1H MR spectroscopy of the human brain, it is common practice to suppress the solvent signal prior to acquisition. This reduces the large dynamic range which is otherwise required of the MR receiver and digitizer in order to detect the dilute metabolite resonances in the presence of the much larger water signal. However, complete solvent suppression is not always obtainable, particularly over large volumes and in superficial regions containing large susceptibility gradients. In this work, it demonstrated that modern commercial MR scanners possess the dynamic range necessary to adequately resolve the 1H metabolites in unsuppressed spectra. Moreover, a postacquisition method is presented which can completely remove the intact water signal and accurately quantitate the metabolite peaks. Preserving the water signal in in vivo spectroscopy has several useful benefits, such as providing a high signal-to-noise ratio internal concentration, frequency, and line shape reference. Comparison is made between suppressed and unsuppressed spectra from both a phantom and the human brain acquired at 4 T. © 2001 John Wiley & Sons, Inc. Concepts Magn Reson 13: 260,275, 2001 [source] Diameter of Involved Nerves Predicts Outcomes in Cutaneous Squamous Cell Carcinoma with Perineural Invasion: An Investigator-Blinded Retrospective Cohort StudyDERMATOLOGIC SURGERY, Issue 12 2009AMY S. ROSS MD BACKGROUND Perineural invasion (PNI) has been associated with poor prognosis in cutaneous squamous cell carcinoma (CSCC), but it is unclear how different degrees of nerve involvement affect prognosis. OBJECTIVE To determine whether the diameter of nerves invaded by CSCC affects outcomes of recurrence, metastasis, and disease-specific and overall survival. METHODS A retrospective cohort study was conducted of patients with CSCC with PNI. Dermatopathologists blinded to subject outcomes determined the diameter of the largest involved nerve. RESULTS Data were obtainable for 48 patients. Small-caliber nerve invasion (SCNI) of nerves less than 0.1 mm in diameter was associated with significantly lower risks of all outcomes of interest. Disease-specific death was 0% in subjects with SCNI, versus 32% in those with large-caliber nerve invasion (LCNI) (p=.003). Other factors associated with significantly worse survival were recurrent or poorly differentiated tumors or tumor diameter of 2 cm or greater or depth of 1 cm or greater. On multivariate analysis, only tumor diameter and age predicted survival. CONCLUSIONS The individual prognostic significance of factors associated with poor survival remains uncertain. Small-caliber nerve invasion may not adversely affect outcomes. Defining PNI as tumor cells within the nerve sheath and routine recording of diameter of involved nerves, tumor depth, and histologic differentiation on pathology reports will facilitate further study. [source] An economic model of the limits to foraging range in central place foragers with numerical solutions for bumblebeesECOLOGICAL ENTOMOLOGY, Issue 3 2000James E. Cresswell Summary 1. A model is described that evaluates the maximum economic foraging range in central place foragers by using optimality criteria to discriminate between foraging sites at different distances from the forager's central place. 2. The basic model can be varied to suit foragers that optimise either their rate of net energy uptake or their foraging efficiency. 3. The model requires specification of the time and energy budgets of travel and foraging, and of the rewards obtainable at potential foraging sites. 4. The specific case of bumblebees, whose foraging ranges are poorly known, is considered. 5. Numerical solutions of the model for parameter values that represent bumblebees and their forage predict economic foraging ranges exceeding several kilometres. The model demonstrates that economics alone can explain extensive flight ranges in bees. [source] The lay subsidies and the distribution of wealth in medieval England, 1275,1334ECONOMIC HISTORY REVIEW, Issue 1 2004Pamela Nightingale This article examines the evidence that between 1275 and 1334 the lay subsidies provide a yardstick with which to measure the English economy. It compares their evidence with the chronological and geographical pattern of wealth obtainable from the Statute Merchant records of debt and concludes that the main discrepancies can be explained by the progressive exclusion from the tax valuations of wool, coin, and credit. Accordingly, from c. 1300 the lay subsidies cannot be used as a guide to the distribution of wealth in England and they can offer only a limited comparison with the wealth revealed by the Tudor subsidies. [source] High-Temperature Electrochemistry: A ReviewELECTROANALYSIS, Issue 6 2004Gregory Abstract High-temperature electrochemistry remains a relatively unexplored field of research, although in recent years significant developments have been made. This report details the main experimental methods and approaches to heating an electrochemical system under both isothermal and non-isothermal conditions and gives an insight into the experimental and electroanalytical results obtainable under such conditions. It has been shown that the promotion of mass transport at high-temperatures, through diffusion or convection, often results in increased current signals. This increase benefits electroanalytical measurements by lowering detection limits. High temperatures also usefully enhance the sensitivity of systems with sluggish kinetics. [source] Capillary electrophoresis-mass spectrometry characterisation of secondary metabolites from the antihyperglycaemic plant Genista teneraELECTROPHORESIS, Issue 11 2006Emma L. Edwards Abstract Genista tenera is endemic to the Portuguese island of Madeira, where an infusion of the aerial parts of the plant is used in folk medicine as an antidiabetic agent. Consequently the medicinal properties of the secondary metabolites of this plant have been the subject of an ongoing study. A recently reported LC-MS method using a 100,min separation allowed identification of five flavonoid components in an extract of the aerial parts of this plant. In order to obtain additional information on the range and complexity of the plant's secondary metabolite components a CE-MS method has been developed and applied for the analysis of an extract of G.,tenera. Twenty-six different components are distinguished in an analysis time of only 10,min. Results demonstrate that CE-MS/MS rapidly generates data complementary to those obtainable by LC-MS/MS and is particularly suited to the analysis of plant metabolites where concentration is not limiting. [source] On the efficiency of PGPS-based packet and cell switching technologies for traffic with guaranteed delayEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 4 2003Fulvio Risso Circuit switching, suited to providing real-time services due to the low and fixed switching delay, is not cost effective for building integrated services networks because it is based on static allocation of resources which is not efficient with bursty data traffic. Moreover it cannot handle flows that are not integer multiple of 64,Kb/s, preventing the usage of low bit rate codecs. This work explores the most suitable alternatives to the circuit switching technology (i.e. packet/cell switching) from the efficiency point of view, assuming that a PGPS scheduler is deployed in the network nodes. The paper defines an index to measure the efficiency of packet telephony, i.e. the volume of real-time traffic with deterministically guaranteed quality plus the amount of data carried related to the amount of network resources used. Furthermore it determines the maximum efficiency obtainable by packet networks, compares different network technologies and explores the problems of the deploying of low bit-rate codecs. Copyright © 2003 AEI. [source] The relationship between fishing methods, fisheries management and the estimation of maximum sustainable yieldFISH AND FISHERIES, Issue 4 2002Mark N Maunder Abstract The allocation of effort among fishing gears is as important as controlling effort with respect to both sustainable yield and ecosystem management. Differences in age-specific vulnerability to the fishing method can modify the maximum sustainable yield (MSY) that is obtainable from a fish stock. Different gears or methods are more or less selective for the species targeted, and MSY is rarely, if ever, attainable simultaneously for all species. The different fishing methods capture different types of nontarget species. Some methods will often be more profitable than others, and different user groups will prefer different methods. In many fisheries, it is unlikely that fishing can be limited to a single gear or method, so compromises among them will be required. Global MSY is discussed as a possible reference point for fisheries management. The yellowfin tuna fishery in the eastern Pacific Ocean (EPO) shows all the above characteristics and is used to illustrate effort allocation among fishing methods. [source] The sedimentary records in Mediterranean rockshelters and caves: Archives of environmental changeGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 4 2001Jamie C. Woodward It is important to develop rigorous methods and robust conceptual models for the interpretation of rockshelter and cave sediment records so that the cultural sequences they contain can be considered in their proper environmental context. Much of what we know about the prehistory of the Mediterranean region and adjacent areas has largely been pieced together from materials excavated from sedimentary sequences in these environments. The rockshelters and caves of the region form important environmental and sedimentary archives. Recent work has begun to consider if the remarkable climatic variability evident in the high resolution lacustrine and ice core records is manifest in the rockshelter and cave sediment records of the area. In this context, the two main characteristics of a rockshelter or cave site which control its usefulness as an archive of environmental change are the temporal resolution of the sedimentary record and the environmental sensitivity of the site. Many rockshelters and caves can be described as either Active Karst Settings (AKS) or Passive Karst Settings (PKS) and site type is an important influence on climatic sensitivity with a direct influence upon the usefulness of the sedimentary sequence as a proxy record of climate change. It is now clear that some sites may preserve detailed paleoclimatic records and the climatic signal may be represented by distinctive suites of micromorphological features, by variations in the input of allogenic sediment, or by fluctuations in the mineral magnetic properties of the fine sediment fraction. It can be argued that data derived from the analysis of bulk coarse-grained samples often lacks the stratigraphic resolution and environmental sensitivity that can be obtained from other approaches. The most favorable sites for detailed paleoclimatic reconstruction appear to be in active karst settings such as Theopetra Cave (Greece) and Pigeon Cave (Morocco) where micromorphological analyses offer insights into the stratigraphic record that are not otherwise obtainable. The temporal resolution of a site can only be established through a rigorous stratigraphic analysis and a comprehensive dating program. These are fundamental considerations in the study of rockshelter sediment records, especially when attempting to correlate between sites and draw comparisons with other proxy records of environmental change derived from sedimentary environments with rather different characteristics. Rockshelters and caves are part of a wider sediment system, and their investigation must be accompanied by detailed geomorphological, sedimentological, paleoecological, and geochronological studies of the off-site Quaternary record. © 2001 John Wiley & Sons, Inc. [source] A Combined Cluster and Interaction Model: The Hierarchical Assignment ProblemGEOGRAPHICAL ANALYSIS, Issue 3 2005Mark W. Horner This article presents a new spatial modeling approach that deals with interactions between individual geographic entities. The developed model represents a generalization of the transportation problem and the classical assignment problem and is termed the hierarchical assignment problem (HAP). The HAP optimizes the spatial flow pattern between individual origin and destination locations, given that some grouping, or aggregation of individual origins and destinations is permitted to occur. The level of aggregation is user specified, and the aggregation step is endogenous to the model itself. This allows for the direct accounting of aggregation costs in pursuit of optimal problem solutions. The HAP is formulated and solved with several sample data sets using commercial optimization software. Trials illustrate how HAP solutions respond to changes in levels of aggregation, as well as reveal the diverse network designs and allocation schemes obtainable with the HAP. Connections between the HAP and the literature on the p-median problem, cluster analysis, and hub-and-spoke networks are discussed and suggestions for future research are made. [source] Cover Picture: Colloidal Synthesis of Hollow Cobalt Sulfide Nanocrystals (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 11 2006Mater. Abstract Hollow nanocrystals have been synthesized through a mechanism analogous to the Kirkendall Effect. When a cobalt nanocrystal reacts with sulfur in solution, the outward diffusion of cobalt atoms is faster than the inward diffusion of sulfur atoms through the sulfide shell. The dominating outward diffusion of cobalt cations produces vacancies that can condense into a single void in the center of the nanocrystal at high temperatures. This process provides a general route to the synthesis of hollow nanostructures of a large number of compounds and is described in the Full Paper by A.,P. Alivisatos and co-workers on p.,1389. Formation of cobalt sulfide hollow nanocrystals through a mechanism similar to the Kirkendall Effect has been investigated in detail. It is found that performing the reaction at >,120,°C leads to fast formation of a single void inside each shell, whereas at room temperature multiple voids are formed within each shell, which can be attributed to strongly temperature-dependent diffusivities for vacancies. The void formation process is dominated by outward diffusion of cobalt cations; still, the occurrence of significant inward transport of sulfur anions can be inferred as the final voids are smaller in diameter than the original cobalt nanocrystals. Comparison of volume distributions for initial and final nanostructures indicates excess apparent volume in shells, implying significant porosity and/or a defective structure. Indirect evidence for fracture of shells during growth at lower temperatures was observed in shell-size statistics and transmission electron microscopy images of as-grown shells. An idealized model of the diffusional process imposes two minimal requirements on material parameters for shell growth to be obtainable within a specific synthetic system. [source] Prison health care: is contracting out healthy?HEALTH ECONOMICS, Issue 11 2009Kelly Bedard Abstract US prison health care has recently been in the news and in the courts. A particular issue is whether prisons should contract out for health care. Contracting out has been growing over the past few decades. The stated motivation for this change ranges from a desire to improve the prison healthcare system, sometimes in response to a court mandate, to a desire to reduce costs. This study is a first attempt to quantify the impact of this change on inmate health. As morbidity measures are not readily obtainable, we focus on mortality. More specifically, we use a panel of state prisons from 1979 to 1990 and a fixed effects Poisson model to estimate the change in mortality associated with increase in the percentage of medical personnel employed under contract. In contrast to the first stated aim of contracting, we find that a 13% increase in percentage of medical personnel employed under contract increases mortality by 1.3%. Copyright © 2009 John Wiley & Sons, Ltd. [source] A Report Card to Grade Helicobacter pylori TherapyHELICOBACTER, Issue 4 2007David Y. Graham Helicobacter pylori causes a serious bacterial infectious disease, and the expectations of therapy should reflect this fact. Increasing antibiotic resistance, especially to clarithromycin, has significantly undermined the effectiveness of legacy triple therapy consisting of a proton pump inhibitor, clarithromycin, and amoxicillin. Current cure rates are consistently below 80% intention-to-treat, the accepted threshold separating acceptable from unacceptable treatment results. Grading clinical studies into effectiveness categories using prespecified criteria would allow clinicians to objectively identify and compare regimens. We offer a therapy report card similar to that used to grade the performance of school children. The intention-to-treat cure rate categories are: F or unacceptable ( 80%), D or poor (81,84%), C or fair (85,89%), B or good (90,95%), and A or excellent (95,100%). The category of "excellent" is based on the cure rates expected with other prevalent bacterial infectious diseases. We propose that only therapies that score "excellent" (grade = A) should be prescribed. Regimens scoring as B or "good" can be used if "excellent" results are not obtainable. In most regions legacy triple therapy should be abandoned as unacceptable. Quadruple therapy and sequential therapy are reasonable alternatives for initial therapy. [source] Torsion of orthotropic bars with L -shaped or cruciform cross-sectionINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 3 2001Y. Z. Chen Abstract For an orthotropic torsion bar with L -shaped or cruciform cross-section, the studied torsion problem can be reduced to a boundary value problem of elliptic partial differential equation. The studied region is separated into several rectangular sub-regions, and the series solution is suggested to solve the problem for the individual sub-region. By using the continuation condition for the functions on the neighbouring sub-regions, the investigated solution is obtainable. Finally, numerical results for the torsion rigidities of bars are given to demonstrate the influence of the degree of orthotropy. Copyright © 2001 John Wiley & Sons, Ltd. [source] Generation and classification of Kerwin,Huelsman,Newcomb circuits using the DVCCINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 7 2009Ahmed M. Soliman Abstract New circuits realizing the Kerwin,Huelsman,Newcomb (KHN) and using three or four differential voltage current conveyor (DVCC) are generated from the basic KHN and inverted KHN block diagrams. The circuits are classified into two types, type A employs three DVCC and type B employs four DVCC. Each type includes four classes of circuits depending on the four possible integrator polarities. Each class can be realized by several circuits as will be demonstrated in the paper. All the eight possible sign combinations of the output voltages polarities are obtainable from the two types; four sign combinations from each type. The eight block diagrams are included to demonstrate the difference between each class of circuits. Spice simulation results demonstrating the practicality of the proposed filters are included. Copyright © 2008 John Wiley & Sons, Ltd. [source] Adaptive directional-aware location update strategyINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 2 2004Tracy Tung Abstract In this paper, a new tracking strategy, the directivity-aware location updating scheme was developed to better utilize the distinct characteristics of individual users on travelling directions. In this new adaptive scheme, an optimal distance-based update threshold is selected according to the call-to-mobility ratio and a transitional directivity index, introduced to give indications of the mobile's travelling patterns. It is found that as far as mobility characteristics are concerned, the actual transitional direction of roaming mobiles plays a significant role in selecting the optimal threshold in addition to the usual perception about mobility rate. Its advantage becomes even more visible when an optimal threshold is not theoretically obtainable due to certain restrictions imposed by the network during times of high system loadings. Simulation results show that the additional information made available about roaming mobile's transitional directivity is critical to ensure that the best available sub-optimal threshold is realizable. Other advances in this paper include the simplification of existing Markovian movement model. With the improved model presentation, the number of states necessary to simulate such memoryless movements is reduced. Consequently, the computational complexity involved is also lessened. Copyright © 2004 John Wiley & Sons, Ltd. [source] Bandwidth-efficient turbo coding over Rayleigh fading channelsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 7 2002Stéphane Y. Le Goff Abstract Introduced in 1993, turbo codes can achieve high coding gains close to the Shannon limit. In order to design power and bandwidth-efficient coding schemes, several approaches have been introduced to combine high coding rate turbo codes with multilevel modulations. The coding systems thus obtained have been shown to display near-capacity performance over additive white Gaussian noise (AWGN) channels. For communications over fading channels requiring large coding gain and high bandwidth efficiency, it is also interesting to study bit error rate (BER) performance of turbo codes combined with high order rectangular QAM modulations. To this end, we investigate, in this paper, error performance of several bandwidth-efficient schemes designed using the bit-interleaved coded modulation approach that has proven potentially very attractive when powerful codes, such as turbo codes, are employed. The structure of these coding schemes, termed ,bit-interleaved turbo-coded modulations' (BITCMs), is presented in a detailed manner and their BER performance is investigated for spectral efficiencies ranging from 2 to 7 bit/s/Hz. Computer simulation results indicate that BITCMs can achieve near-capacity performance over Rayleigh fading channels, for all spectral efficiencies considered throughout the paper. It is also shown that the combination of turbo coding and rectangular QAM modulation with Gray mapping constitutes inherently a very powerful association, since coding and modulation functions are both optimized for operation in the same signal-to-noise ratio region. This means that no BER improvement is obtainable by employing any other signal constellation in place of the rectangular ones. Finally, the actual influence of the interleaving and mapping functions on error performance of BITCM schemes is discussed. Copyright © 2002 John Wiley & Sons, Ltd. [source] Palliative care patients' experiences of healthcare treatmentINTERNATIONAL JOURNAL OF SOCIAL WELFARE, Issue 3 2010Cynthia Kennett Kennett C, Payne M. Palliative care patients' experiences of healthcare treatment Int J Soc Welfare 2010: 19: 262,271 © 2009 The Author(s), Journal compilation © 2009 Blackwell Publishing Ltd and the International Journal of Social Welfare. This article reports on a thematic analysis of the opinions of 34 palliative care patients about medical and healthcare treatment expressed in comments, narratives and discussions during a series of facilitated group discussions undertaken as part of training events for medical students. Palliative care patients often have long healthcare careers, which enables them to compare different professionals and services, thus offering a more powerful and complex analysis of patient experience than that obtainable from analysis of complaints or satisfaction surveys, and permits some understanding to be obtained of the attitudes that condition evaluations of services. The patients balanced negative views with positive experiences. They appreciated open, listening, equal and friendly relationships with professionals in which careful explanation fostered their confidence in the overall service. They criticised inflexible services that did not consider their broad needs, and in which relationships with professionals were characterised by busy-ness and professional distance. [source] Stem cells for enhancing recovery after stroke: a reviewINTERNATIONAL JOURNAL OF STROKE, Issue 2 2009Tim England The potential application for stem cell therapy is vast, and development for use in ischaemic stroke is still in its infancy. Access to stem cells for research is contentious; however, stem cells are obtainable from both animal and human. Despite a limited understanding of their mechanisms of action, clinical trials assessing stem cells in human stroke have been performed. Trials are also underway evaluating haematopoietic precursors mobilised with granulocyte-colony stimulating factor, an approach offering an autologous means of administrating stem cells for therapeutic purposes. This review summarises current knowledge in regard to stem cells and their potential for helping improve recovery after stroke. [source] Ab initio structure solution by iterative phase-retrieval methods: performance tests on charge flipping and low-density eliminationJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 1 2010Frank Fleischer Comprehensive tests on the density-modification methods charge flipping [Oszlányi & Süt, (2004). Acta Cryst. A60, 134,141] and low-density elimination [Shiono & Woolfson (1992). Acta Cryst. A48, 451,456] for solving crystal structures are performed on simulated diffraction data of periodic structures and quasicrystals. A novel model-independent figure of merit, which characterizes the reliability of the retrieved phase of each reflection, is introduced and tested. The results of the performance tests show that the quality of the phase retrieval highly depends on the presence or absence of an inversion center and on the algorithm used for solving the structure. Charge flipping has a higher success rate for solving structures, while low-density elimination leads to a higher accuracy in phase retrieval. The best results can be obtained by combining the two methods, i.e. by solving a structure with charge flipping followed by a few cycles of low-density elimination. It is shown that these additional cycles dramatically improve the phases not only of the weak reflections but also of the strong ones. The results can be improved further by averaging the results of several runs and by applying a correction term that compensates for a reduction of the structure-factor amplitudes by averaging of inconsistently observed reflections. It is further shown that in most cases the retrieved phases converge to the best solution obtainable with a given method. [source] Expression of signal transduction proteins during the differentiation of primary human erythroblastsJOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2005Viviana di Giacomo The high number (>108,10) of primary human pro-erythroblasts (CD36high/CD235alow) obtainable in HEMA culture (Migliaccio et al., 2002) is exploited here to analyse the expression of proteins implicated in erythropoietin (EPO)-signalling (STATs, PI-3K, and PLCs) during the process of erythroid maturation. Human pro-erythroblasts progressed in 4 days of culture with EPO into basophilic- (CD36high/CD235amedium, 24 h), polychromatic-(CD36high/CD235ahigh, 48 h), and, finally, orthochromatic-(CD36low/CD235ahigh, 72,96 h) erythroblasts. During this maturation, STAT-1 was expressed up to the orthochromatic stage, expression of STAT-5, as well as of its target proteins BclxL and IRF1, remained constant up to 48 h (polychromatic-erythroblasts) but decreased by 96 h (orthochromatic-erythroblasts), while that of STAT-3 decreased constantly from 24 h on and became undetectable by 96 h. Expression of PI-3K rapidly decreased with differentiation since only 50% of original protein levels were detected by 48 h. On the other hand, among the members of PLC families investigated, PLC ,4 was not expressed, PLC ,2, ,1, and ,2 were expressed at constant levels throughout the maturation process, while expression of PLC ,3 and of PLC ,1 decreased, as PI-3K, by 24 h and that of PLC ,1 was induced by 6 h and became undetectable by 24 h. In conclusion, these data depict the dynamic signalling scenario associated with the maturation of erythroid cells and provide the first indication that members of PLC families (PLC ,1, ,3, and ,1) might e involved in the control of erythroid differentiation in humans. © 2004 Wiley-Liss, Inc. [source] Improvement of enantioselectivity and stability of Klebsiella oxytoca hydrolase immobilized on Eupergit C 250LJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 11 2008Pei-Yun Wang Abstract BACKGROUND: A simple procedure was employed to covalently immobilize a Klebsiella oxytoca hydrolase (SNSM-87) onto epoxy-activated supports of Eupergit C 250L via multipoint covalent attachment. The resultant biocatalyst was explored for the hydrolytic resolution of a variety of (R,S)-2-hydroxycarboxylic acid ethyl esters. RESULTS: With the hydrolytic resolution of (R,S)-ethyl mandelate in biphasic media as the model system, optimal conditions of 55 °C, pH 6 buffer and isooctane as the organic phase were selected for improving the enzyme stability (activity retained from 10% to 50% at 96 h) and enantioselectivity (VSVR,1 value enhanced from 44 to 319) in comparison to the performance of free enzyme. Moreover, the immobilized enzyme retained its activity and enantioselectivity after eight cycles of hydrolysis at 55 °C. When applying the resolution process to other (R,S)-2-hydroxycarboxylic acid ethyl esters, 2.4- to 4.0-fold enhancements of the enantioselectivity in general were obtainable. CONCLUSIONS: The enantioselectivity enhancement, good reusability and easy recovery after reaction indicate that the immobilized SNSM-87 may have the potential as an industrial biocatalyst for the preparation of optically pure 2-hydroxycarboxylic acids. Copyright © 2008 Society of Chemical Industry [source] The ZiReal Post: A New Ceramic Implant AbutmentJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 1 2003URS BRODBECK DMD ABSTRACT Restorations in the anterior esthetic zone present significant challenges in both the surgical and prosthetic phases of implant dentistry. Titanium has been established as the material of choice for endosseous implants, resulting in a high degree of predictability. Many types of implants require transmucosal abutments to retain implant restorations. Ceramics may be the ideal material to replace natural teeth, but most transmucosal abutments are made of titanium. However, ceramics may also be used as abutments in implant restorations. This combination of ceramics for abutment and crown provides better translucency for the implant restoration than is available with metal abutments and porcelain-fused-to-metal crowns. Ceramic abutments and implant restorations also minimize the gray color associated with metal components that is transmitted through the peri-implant tissues. Customized emergence profiles also may be obtained with ceramic abutments; this generally improves the predictability and consistency of the esthetics obtainable in implant restorations. Zirconia as a ceramic material offers not only outstanding material properties but also a well-documented biocompatibility. CLINICAL SIGNIFICANCE This article discusses the clinical and laboratory features of a new ceramic abutment, ZiRealÔ Post (Implant Innovations, Inc., Palm Beach Gardens, Florida). [source] Population dynamics of fisheries stock enhancementJOURNAL OF FISH BIOLOGY, Issue 2004K. Lorenzen The population dynamics of fisheries stock enhancement, and its potential for generating benefits over and above those obtainable from optimal exploitation of wild stocks alone are poorly understood and highly controversial. I extend the dynamic pool theory of fishing to stock enhancement by unpacking recruitment, incorporating regulation in the recruited stock, and accounting for biological differences between wild and hatchery fish. I then analyse the dynamics of stock enhancement and its potential role in fisheries management, using the candidate stock of North Sea sole as an example. Enhancement through release of recruits or advanced juveniles is predicted to increase total yield and stock abundance, but reduce abundance of the naturally recruited stock component through compensatory responses or overfishing. Release of genetically maladapted fish reduces the effectiveness of enhancement, and is most detrimental overall if fitness of hatchery fish is only moderately compromised. As a temporary measure for rebuilding of depleted stocks, enhancement can not substitute for effort limitation, and is advantageous as an auxiliary measure only if the population has been reduced to a very low proportion of its unexploited biomass. Quantitative analysis of population dynamics is central to the responsible use of stock enhancement in fisheries management, and the necessary tools are available. [source] Y-STR Profiling in Extended Interval (,3 days) Postcoital Cervicovaginal Samples,JOURNAL OF FORENSIC SCIENCES, Issue 2 2008Kathleen A. Mayntz-Press M.S. Abstract:, Depending upon specific situations, some victims of sexual assault provide vaginal samples more than 36,48 h after the incident. We have tested the ability of commercial and in-house Y-STR systems to provide DNA profiles from extended interval (,3 days) postcoital samples. The commercial Y-STR systems tested included the AmpF,STR® YfilerÔ (Applied Biosystems), PowerPlex® Y (Promega) and Y-PLEXÔ 12 (Reliagene) products whereas the in-house systems comprised Multiplex I (MPI) and Multiplex B (MPB). Three donor couples were recruited for the study. Postcoital cervicovaginal swabs (x2) were recovered by each of the three females at specified intervals after sexual intercourse (3,7 days). Each time point sample was collected after a separate act of sexual intercourse and was preceded by a 7-day abstention period. As a negative control, a precoital swab was also recovered prior to coitus for each sampling and only data from postcoital samples that demonstrated a lack of male DNA in the associated precoital sample was used. A number of DNA profile enhancement strategies were employed including sampling by cervical brushing, nondifferential DNA extraction methodology, and post-PCR purification. Full Y-STR profiles from cervicovaginal samples recovered 3,4 days after intercourse were routinely obtained. Profiles were also obtainable 5,6 days postcoitus although by this stage partial profiles rather than full profiles were a more likely outcome. The DNA profiles from the sperm fraction of a differential lysis were superior to that obtained when a nondifferential method was employed in that the allelic signal intensities were generally higher and more balanced and exhibited less baseline noise. The incorporation of a simple post-PCR purification process significantly increased the ability to obtain Y-STR profiles, particularly from 5- to 6-day postcoital samples. Remarkably an 8 locus Y-STR profile was obtained from a 7-day postcoital sample, which is approaching the reported time limit for sperm detection in the cervix. [source] Percent infarct mapping for delayed contrast enhancement magnetic resonance imaging to quantify myocardial viability by Gd(DTPA)JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2010Tamás Simor MD Abstract Purpose To demonstrate the advantages of signal intensity percent-infarct-mapping (SI-PIM) using the standard delayed enhancement (DE) acquisition in assessing viability following myocardial infarction (MI). SI-PIM quantifies MI density with a voxel-by-voxel resolution in clinically used DE images. Materials and Methods In canines (n= 6), 96 hours after reperfused MI and administration of 0.2 mmol/kg Gd(DTPA), ex vivo DE images were acquired and SI-PIMs calculated. SI-PIM data were compared with data from DE images analyzed with several thresholding levels using SIremote+2SD, SIremote+6SD, SI full width half maximum (SIFWHM), and with triphenyl-tetrazolium-chloride (TTC) staining. SI-PIM was also compared to R1 percent infarct mapping (R1-PIM). Results Left ventricular infarct volumes (IV) in DE images, IVSIremote+2SD and IVSIremote+6SD, overestimated (P < 0.05) TTC by medians of 13.21 mL [10.2; 15.2] and 6.2 mL [3.79; 8.23], respectively. SIFWHM, SI-PIM, and R1-PIM, however, only nonsignificantly underestimated TTC, by medians of ,0.10 mL [,0.12, ,0.06], ,0.86 mL [,1.04; 1.54], and ,1.30 mL [,4.99; ,0.29], respectively. The infarct-involved voxel volume (IIVV) of SI-PIM, 32.4 mL [21.2, 46.3] is higher (P < 0.01) than IIVVs of SIFWHM 8.3 mL [3.79, 19.0]. SI-PIMFWHM, however, underestimates TTC (,5.74 mL [,11.89; ,2.52] (P < 0.01)). Thus, SI-PIM outperforms SIFWHM because larger IIVVs are obtained, and thus PIs both in the rim and the core of the infarcted tissue are characterized, in contradistinction from DE-SIFWHM, which shows mainly the infarct core. Conclusion We have shown here, ex vivo, that SI-PIM has the same advantages as R1-PIM, but it is based on the scanning sequences of DE imaging, and thus it is obtainable within the same short scanning time as DE. This makes it a practical method for clinical studies. J. Magn. Reson. Imaging 2010;32:859,868. © 2010 Wiley-Liss, Inc. [source] Condensation routes to polyaniline and its analogsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2007H. K. Hall Abstract To obtain polyanilines which are more structurally perfect than those obtainable by the oxidation of anilines, polycondensation procedures were investigated. Model reactions gave extensive information about yields and about the physical properties of the putative structural polymer units. Condensation of anthraquinones with aromatic diamines using titanium tetrachloride and the unique base, 1,4-diazabicyclo-[2.2.2]-octane Dabco, gave high molecular weight orange polyquinonimines. Alkoxy groups on the anthraquinone ring aided solubility and molecular weight, and appropriately positioned alkoxy groups afforded stereoregular polymers. A bisthiophene benzoquinone also polymerized successfully. Application of the same procedure to 2,5-dimethyl- p -benzoquinone gave stereoregular poly(arylene benzoquinonimines), close analogs of pernigrani line. The factors causing problems in achieving high yields and high molecular weight were identified. Recent synthetic developments in this field are discussed. Reduction of the obtained polyquinonimines proceeded smoothly to the leucoemeraldine analogs. Unlike the results from pernigraniline obtained by oxidative polymerization, no evidence for the formation of the electrically conductive emeraldine form was obtained. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4751,4763, 2007 [source] Topological polymer chemistry by electrostatic self-assemblyJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 19 2003Yasuyuki Tezuka Abstract Recent developments in topological polymer chemistry are outlined. First, nonlinear polymer topologies are systematically classified on the basis of topological considerations of constitutional isomerism in a series of alkanes (CnH2n+2), monocycloalkanes (CnH2n), and polycycloalkanes (CnH2n,2, CnH2n,4, etc.). Various pairs of topological isomers are identified in randomly coiled, flexible polymer molecules with cyclic and branched structures. An electro- static self-assembly and covalent fixation strategy has subsequently been developed for the efficient synthesis of a variety of topologically unique polymers, including monocyclic and polycyclic polymers, topological isomers, and topological block copolymers. In this process, new telechelics with moderately strained cyclic onium salt groups carrying multifunctional carboxylate counteranions have been designed as key polymeric precursors. Further extensions of topological polymer chem- istry have been achieved by the use of cyclic telechelics (kyklo -telechelics) and cyclic macromonomers, obtainable also by means of the electrostatic self-assembly and covalent fixation process. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2905,2917, 2003 [source] Radial single-shot STEAM MRIMAGNETIC RESONANCE IN MEDICINE, Issue 4 2008Kai Tobias Block Abstract Rapid MR imaging using the stimulated echo acquisition mode (STEAM) technique yields single-shot images without any sensitivity to resonance offset effects. However, the absence of susceptibility-induced signal voids or geometric distortions is at the expense of a somewhat lower signal-to-noise ratio than EPI. As a consequence, the achievable spatial resolution is limited when using conventional Fourier encoding. To overcome the problem, this study combined single-shot STEAM MRI with radial encoding. This approach exploits the efficient undersampling properties of radial trajectories with use of a previously developed iterative image reconstruction method that compensates for the incomplete data by incorporating a priori knowledge. Experimental results for a phantom and human brain in vivo demonstrate that radial single-shot STEAM MRI may exceed the resolution obtainable by a comparable Cartesian acquisition by a factor of four. Magn Reson Med 59:686,691, 2008. © 2008 Wiley-Liss, Inc. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||