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Selected AbstractsRed blood cell quantification microfluidic chip using polyelectrolytic gel electrodesELECTROPHORESIS, Issue 9 2009Kwang Bok Kim Abstract This paper reports on a novel microfluidic chip with polyelectrolytic gel electrodes (PGEs) used to rapidly count the number of red blood cells (RBCs) in diluted whole blood. The proposed microdevice is based on the principle that the impedance across a microchannel between two PGEs varies sensitively as RBCs pass through it. The number and amplitude of impedance peaks provide the information about the number and size of RBCs, respectively. This system features a low-voltage dc detection method and non-contact condition between cells and metal electrodes. Major advantages include stable detection under varying cellular flow rate and position in the microchannel, little chance of cell damage due to high electric field gradient and no surface fouling of the metal electrodes. The performance of this PGEs-based system was evaluated in three steps. First, in order to observe the size-only dependence of the impedance signal, three different sizes of fluorescent microbeads (7.2, 10.0, and 15.0,,m; Bangs laboratories, USA) were used in the experiment. Second, the cell counting performance was evaluated by using 7.2,,m fluorescent microbeads, similar in size to RBCs, in various concentrations and comparing the results with an animal hematoanalyzer (MS 9-5; Melet schloesing laboratories, France). Finally, in human blood sample tests, intravenously collected whole blood was just diluted in a PBS without centrifuge or other pretreatments. The PGE-based system produced almost identical number of RBCs in over 800-fold diluted samples to the results from a commercialized human hematoanalyzer (HST-N402XE; Sysmex, Japan). [source] Screening of the Interactions Between Mg-PSZ and TRIP-Steel and Its Alloys During Sintering,ADVANCED ENGINEERING MATERIALS, Issue 6 2010Christian Weigelt Ceramic,steel compound materials are used in a wide range of applications up to date. Major advantages are the mechanical properties due to the combination of brittle ceramic with tough steel. This study deals with effects of the sintering process on austenitic TRIP-steel/Mg-PSZ composite materials for mechanical load applications. Both, the FeCrNisteel and partially stabilized zirconia offer their special mechanical behavior only in a metastable state. The ability of phase transformation depends mainly on the chemical composition. Mutual interactions of the alloying metals (Cr, Ni, Mn, and Fe) and the ceramic stabilizer (MgO) during sintering may prevent the martensitic phase transformation. This may cause disadvantageous mechanical behavior on mechanical load in use. [source] Photodynamic therapy in dermatology: state-of-the-artPHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 3 2010Philipp Babilas Photodynamic therapy (PDT) has become an established treatment modality for dermatooncologic conditions like actinic keratosis, Bowen's disease, in situ squamous cell carcinoma and superficial basal cell carcinoma. There is also great promise of PDT for many non-neoplastic dermatological diseases like localized scleroderma, acne vulgaris, granuloma anulare and leishmaniasis. Aesthetic indications like photo-aged skin or sebaceous gland hyperplasia complete the range of applications. Major advantages of PDT are the low level of invasiveness and the excellent cosmetic results. Here, we review the principal mechanism of action, the current developments in the field of photosensitizers and light sources, practical aspects of topical PDT and therapeutical applications in oncologic as well as non-oncologic indications. [source] Optimization of Electrochemical and Peroxide-Driven Oxidation of Styrene with Ultrathin Polyion Films Containing Cytochrome P450cam and MyoglobinCHEMBIOCHEM, Issue 1 2003Bernard Munge Abstract The catalytic and electrochemical properties of myoglobin and cytochrome P450camin films constructed with alternate polyion layers were optimized with respect to film thickness, polyion type, and pH. Electrochemical and hydrogen peroxide driven epoxidation of styrene catalyzed by the proteins was used as the test reaction. Ionic synthetic organic polymers such as poly(styrene sulfonate), as opposed to SiO2nanoparticles or DNA, supported the best catalytic and electrochemical performance. Charge transport involving the iron heme proteins was achieved over 40,320 nm depending on the polyion material and is likely to involve electron hopping facilitated by extensive interlayer mixing. However, very thin films (ca. 12,25 nm) gave the largest turnover rates for the catalytic epoxidation of styrene, and thicker films were subject to reactant transport limitations. Classical bell-shaped activity/pH profiles and turnover rates similar to those obtained in solution suggest that films grown layer-by-layer are applicable to turnover rate studies of enzymes for organic oxidations. Major advantages include enhanced enzyme stability and the tiny amount of protein required. [source] Patent Foramen Ovale: Comparison among Diagnostic Strategies in Cryptogenic Stroke and MigraineECHOCARDIOGRAPHY, Issue 5 2009Concetta Zito M.D. Objective: The aim of this study was to compare transthoracic echocardiography (TTE) and transcranial Doppler ultrasonography (TCD) with transesophageal echocardiography (TEE) in order to define the best clinical approach to patent foramen ovale (PFO) detection. Methods: In total, 72 consecutive patients (33 men) with a mean age of 49 ± 13 years were prospectively enrolled. The TEE indication was cryptogenic stroke (36 patients) or migraine (36 patients, 22 with aura). All patients underwent standard TTE, TCD, and TEE examination. For any study, a contrast test was carried on using an agitated saline solution mixed with urea-linked gelatine (Haemaccel), injected as a rapid bolus via a right antecubital vein. A prolonged Valsalva maneuver was performed to improve test sensitivity. Results: TEE identified a PFO in 65% of the whole population: 56.5% in the migraine cohort and 43.5% in the cryptogenic stroke cohort. TTE was able to detect a PFO in 55% of patients positive at TEE (54% negative predictive value, 100% positive predictive value, 55% sensitivity, and 100% specificity). TCD was able to identify a PFO in 97% of patients positive at TEE (89% negative predictive value, 98% positive predictive value, 94% sensitivity, and 96% specificity). Conclusions: In patients with cryptogenic stroke and migraine, there is a fair concordance (k = 0.89) between TCD and TEE in PFO recognition. Accordingly, TCD should be recommended as a simple, noninvasive, and reliable technique, whereas TEE indication should be restricted to selected patients. TTE is a very specific technique, whose major advantage is the ability to detect a large right-to-left shunt, particularly if associated with an atrial septal aneurysm. [source] Quaternary Ammonium-Supported Scavenger Reagents for Acids and ElectrophilesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 1 2004Noha Ghanem Abstract The present article describes how we devised new quaternary ammonium-supported quench reagents (TAMA-Cl and BAX-sulfate) for scavenging acids and excess electrophiles from crude reaction mixtures. TAMA-Cl is liquid at room temperature, but is very glutinous and has to be used in aqueous solution. It removes unchanged electrophiles very efficiently. An aqueous preparation of TAMA-Cl may be easily added in automated syntheses, and high-throughput phase-separation techniques should allow purification of scavenger-containing reaction mixtures. However, workup with TAMA-Cl is more complex than simple filtration. Recognizing this major advantage of solid-phase syntheses, we designed BAX-sulfate, a highly crystalline scavenger reagent that allows reaction workup to be simplified to a single filtration and evaporation of solvent. BAX-sulfate reacts with electrophiles, quenches acids and precipitates quantitatively when diethyl ether is added. It even precipitates from methanol solutions. With BAX-sulfate the workup stage uses simple filtration to make crude separations. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Temperature-Responsive Substrates: Adhesion and Mechanical Properties of PNIPAM Microgel Films and Their Potential Use as Switchable Cell Culture Substrates (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 19 2010Mater. Abstract Thermoresponsive poly(N -isopropylacrylamide) (PNIPAM) microgel films are shown to allow controlled detachment of adsorbed cells via temperature stimuli. Cell response occurs on the timescale of several minutes, is reversible, and allows for harvesting of cells in a mild fashion. The fact that microgels are attached non-covalently allows using them on a broad variety of (charged) surfaces and is a major advantage as compared to approaches relying on covalent attachment of active films. In the following, the microgels' physico-chemical parameters in the adsorbed state and their changes upon temperature variation are studied in order to gain a deeper understanding of the involved phenomena. By means of atomic force microscopy (AFM), the water content, mechanical properties, and adhesion forces of the microgel films are studied as a function of temperature. The analysis shows that these properties change drastically when crossing the critical temperature of the polymer film, which is the basis of the fast cell response upon temperature changes. Furthermore, nanoscale mechanical analysis shows that the films posses a nanoscopic gradient in mechanical properties. [source] Adhesion and Mechanical Properties of PNIPAM Microgel Films and Their Potential Use as Switchable Cell Culture SubstratesADVANCED FUNCTIONAL MATERIALS, Issue 19 2010Stephan Schmidt Abstract Thermoresponsive poly(N -isopropylacrylamide) (PNIPAM) microgel films are shown to allow controlled detachment of adsorbed cells via temperature stimuli. Cell response occurs on the timescale of several minutes, is reversible, and allows for harvesting of cells in a mild fashion. The fact that microgels are attached non-covalently allows using them on a broad variety of (charged) surfaces and is a major advantage as compared to approaches relying on covalent attachment of active films. In the following, the microgels' physico-chemical parameters in the adsorbed state and their changes upon temperature variation are studied in order to gain a deeper understanding of the involved phenomena. By means of atomic force microscopy (AFM), the water content, mechanical properties, and adhesion forces of the microgel films are studied as a function of temperature. The analysis shows that these properties change drastically when crossing the critical temperature of the polymer film, which is the basis of the fast cell response upon temperature changes. Furthermore, nanoscale mechanical analysis shows that the films posses a nanoscopic gradient in mechanical properties. [source] The major- and trace-element whole-rock fingerprints of Egyptian basalts and the provenance of Egyptian artefactsGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 7 2001John D. Greenough Discrimination diagrams have been developed that source Egyptian basaltic artefacts using whole-rock major element geochemistry. These include K2O versus SiO2, TiO2 and P2O5 against MgO/Fe2O3t (total Fe as Fe2O3), and a discriminant analysis diagram using SiO2, Fe2O3t, CaO, and MnO. A complementary set of diagrams uses easily obtained trace element data (Nb/Y versus Zr/Nb; Zr [ppm] versus Rb/Sr; TiO2 [wt % volatile free] versus V; and Cr [ppm] versus Zr/Y) to determine the bedrock sources. These diagrams have been applied to seven First Dynasty basalt vessels (Abydos), two Fourth Dynasty basalt paving stones (Khufu's funerary temple, Giza), and two Fifth Dynasty paving stones (Sahure's complex, Abu Sir). They show that the bedrock source for all the artefacts was the Haddadin flow in northern Egypt. Multidimensional scaling and cluster analysis applied to the whole-rock data (major elements and trace elements together) and previously published mineral fingerprinting studies confirm these results. Comparing mineral versus whole-rock fingerprinting techniques, a major advantage of the former is the small sample size required (0.001 g compared to , 0.1 g). Analytical costs are similar for both methods assuming that a comparison (bedrock) database can be assembled from the literature. For most archaeological problems, a whole-rock bedrock database is more likely to exist than a mineral database, and whole-rock analyses on artefacts will generally be easier to obtain than mineral analyses. Whole-rock fingerprinting may be more sensitive than mineral-based fingerprinting. Thus, if sample quantity is not an issue, whole-rock analysis may have a slight cost, convenience, and technical advantage over mineral-based methods. Our results also emphasize that the Egyptians cherished their Haddadin basalt flow and used it extensively and exclusively for manufacturing basalt vessels and paving stones for at least 600 years (,3150 B.C. to 2500 B.C., approximate ages of the vessels and Abu Sir paving stones, respectively). © 2001 John Wiley & Sons, Inc. [source] Prospective evaluation of the retrograde percutaneous translaryngeal tracheostomy (Fantoni procedure) in a surgical intensive care unit: Technique and results of the Fantoni tracheostomyHEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 4 2006Ralf Konopke MD Abstract Background. Controversy surrounds the safety and practicality of the retrograde percutaneous translaryngeal tracheostomy (Fantoni procedure) compared with other percutaneous methods. Methods. We used the Fantoni tracheostomy for 245 patients in our intensive care unit (ICU) over a period of 3 years 6 months and conducted a prospective analysis. Results. We are able to report a low incidence of complications (1.2%) with the Fantoni procedure. Advantages of the method are reduced tissue trauma and optimal adaptation of the stoma to the cannula, leading to less stomal bleeding and fewer infectious complications. We observed no procedure-related mortality. Under mandatory bronchoscopic control, proper puncture location and cannula placement are ensured, which prevents tracheal wall injury and paratracheal placement of the cannula. Conclusions. Our experience shows that the major advantage of the use of the Fantoni tracheostomy is the retrograde dilatation of the stoma, which prevents serious complications compared with other techniques. © 2005 Wiley Periodicals, Inc. Head Neck28: 355,359, 2006 [source] Pair bond and breeding success in Blue Tits Parus caeruleus and Great Tits Parus majorIBIS, Issue 1 2005MIRIAM PAMPUS Data from 939 nests of the Blue Tit Parus caeruleus and 1008 nests of the Great Tit P. major from nestboxes provided in superabundance in mixed forest study sites between 1976 and 2001 were analysed to examine the effects of mate retention on breeding success and the relationship between mate fidelity and site fidelity. Most birds retained their former partner (76% in Great Tits and 65% in Blue Tits). The probability of a pair divorcing was affected by male age in Great Tits, divorce being more likely in pairs with first-year males. Great Tit pairs breeding together for a second season bred earlier, but had no higher breeding success than pairs breeding together for the first time. In Blue Tits laying date and start of incubation tended to be earlier in pairs breeding together for a second season, but hatching and fledging dates were not earlier than in other pairs. Great Tit pairs breeding together for two consecutive seasons bred earlier in the second season than in the first, but breeding success did not differ significantly between years. In both species, breeding performance did not differ between pairs that divorced after a season and pairs that stayed together. Thus breeding success did not determine whether a pair divorced or bred together again. Neither Blue Tits nor Great Tits improved their breeding performance through divorce. Blue Tit females even had fewer fledglings in the year after divorce than in the year before. Mate retention affected breeding site fidelity. Blue Tit females had greater breeding dispersal distances between consecutive years when re-mating than when breeding again with the same mate. In Great Tits both males and females dispersed more when re-mating than when retaining the former partner, suggesting that mate retention increased the chance of retaining the breeding site. In both species, breeding dispersal distances did not differ between pairs that divorced and pairs in which one mate disappeared. Because no major advantage of mate retention was evident, we suggest that mate retention evolved under different conditions than those found in study sites with high breeding densities and a superabundance of artificial nesting sites. [source] Simple and efficient integration of rigid rotations suitable for constraint solversINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 9 2010Tomasz Koziara Abstract Simple and efficient way of integrating rigid rotations is presented. The algorithm is stable, second-order accurate, and in its explicit version involves evaluation of only two exponential maps per time step. The semi-explicit version of the proposed scheme improves upon the long-term stability, while it retains the explicitness in the force evaluation. The algebraic structure of both schemes makes them suitable forthe analysis of constrained multi-body systems. The explicit algorithm is specifically aimed at the analysis involving small incremental rotations, where its modest computational cost becomes the major advantage. The semi-explicit scheme naturally broadens the scope of possible applications. Copyright © 2009 John Wiley & Sons, Ltd. [source] Efficient packet classification on network processorsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 1 2008Koert Vlaeminck Abstract Always-on networking and a growing interest in multimedia- and conversational-IP services offer an opportunity to network providers to participate in the service layer, if they increase functional intelligence in their networks. An important prerequisite to providing advanced services in IP access networks is the availability of a high-speed packet classification module in the network nodes, necessary for supporting any IP service imaginable. Often, access nodes are installed in remote offices, where they terminate a large number of subscriber lines. As such, technology adding processing power in this environment should be energy-efficient, whilst maintaining the flexibility to cope with changing service requirements. Network processor units (NPUs) are designed to overcome these operational restrictions, and in this context this paper investigates their suitability for wireline and robust packet classification in a firewalling application. State-of-the-art packet classification algorithms are examined, whereafter the performance and memory requirements are compared for a Binary Decision Diagram (BDD) and sequential search approach. Several space optimizations for implementing BDD classifiers on NPU hardware are discussed and it is shown that the optimized BDD classifier is able to operate at gigabit wirespeed, independent of the ruleset size, which is a major advantage over a sequential search classifier. Copyright © 2007 John Wiley & Sons, Ltd. [source] Methodological issues in online data collectionJOURNAL OF ADVANCED NURSING, Issue 5 2007Mary Ann Cantrell Abstract Title.,Methodological issues in online data collection Aim., This paper is a report of a study to evaluate the use of an online data collection method to survey early survivors of childhood cancer about their physical and psychosocial characteristics and health-related quality of life. Background., A major advantage in conducting web-based nursing research is the ability to involve participants who are challenging to study because of their small numbers or inaccessibility because of geographic location. As paediatric oncology patients and early survivors of childhood cancer are often not easily accessible because of their small numbers at single institutions, web-based research methods have been proposed as a potentially effective approach to collect data in studies involving these clinical populations. Method., Guided by published literature on using the Internet for data collection, an online protocol was developed; this included construction of a website, development of a homepage and interactive HyperText Markup Language pages and the posting of the study link on various websites. Data collection occurred over a 6-month period between December 2005 and May 2006. Findings., Despite using strategies in conducting online research cited in published literature, the recruitment of subjects was very prolonged and the volume of missing data among many respondents excluded them from the study and created bias within the study's results. Conclusion., Web-based, online data collection methods create opportunities to conduct research globally, especially among difficult to access populations. However, web-based research requires careful consideration of how the study will be advertized and how data will be collected to ensure high quality data and validity of the findings. [source] A simple and low-cost solution for the automation of X-ray powder diffractometers with chart recorder outputJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 4 2006M. Jayaprakasan X-ray powder diffraction is an established method for the qualitative identification of crystalline materials and their quantitative analysis. The new generation of X-ray diffraction systems are based on expensive digital/embedded control technology and computer interfaces. Yet many laboratories use conventional manual-controlled systems with XY strip-chart recorders. Since the output spectrum is a strip chart (hard copy), raw data, essential for structural and qualitative analysis, are not readily available for further analysis. Upgrading to modern computerized diffractometers is very expensive. The proposed automation design described here is intended to enable the conventional diffractometer user to collect, store and analyze data quickly. The design also improves the resolution by five times compared with the conventional setup. For the automation, a PC add-on card has been designed to control and collect the timing and intensity counts from the conventional X-ray diffractometer, and suitable software has been developed to collect, process and present the X-ray diffraction data for both qualitative and quantitative analysis. Moreover, a major advantage of this design is that it does not warrant any physical modification of the hardware of the conventional setup; it is simply an extension to enhance the performance of collecting raw data with a higher resolution at desired intervals/timings. [source] Clinical education facilitators: a literature reviewJOURNAL OF CLINICAL NURSING, Issue 6 2005Veronica Lambert BNS Aims and objectives., The aim of this literature review, set within an Irish context, is to present a broad overview of former and existing clinical support personnel, explore the concept of facilitation and examine what is known about the role of the clinical education facilitator. Background., The importance of providing a supportive clinical environment to enhance clinical teaching and learning is strongly portrayed in the literature. While the past two decades have borne witness to various clinical support personnel, the literature identifies conflicting demands that these personnel face. No suggestions are advanced as to how to overcome these difficulties, which inevitably influence the quality and quantity of their clinical teaching role. An identifiable gap exists over who has prime responsibility for clinical teaching. It is timely that alternative possibilities for organizing clinical teaching are investigated. A new post emerging in practice settings is that of the clinical education facilitator who is meant to be the key linchpin in clinical areas for reducing the theory,practice gap. Method., Relevant literature for this review was sourced using the computerized databases CINAHL, Medline and Synergy. Manual searching of relevant nursing journals and sourcing of secondary references extended the search. Government reports and other relevant documents were obtained through pertinent websites. Results., Papers that explicitly examined the concept of facilitation and explored the posts of clinical education facilitators were included; six research papers were accessed and reviewed. In addition seven non-empirical papers were included. Conclusions., It is clear that considerable lack of role clarity resides over what constitutes clinical facilitation and the role of the clinical facilitator. Thus, it is paramount to strengthen this support role with Irish empirical evidence. Relevance to clinical practice., A major advantage in having a ward-based clinical education facilitator is the benefit of having access to someone who can concentrate solely on clinical education and support with attempts to narrow the theory,practice divide. [source] Comparison of transperineal and transvaginal sonography in predicting preterm deliveryJOURNAL OF CLINICAL ULTRASOUND, Issue 5 2004Gurkan Yazici MD Abstract Purpose A major advantage of transperineal sonography (TPUS) is its ability to evaluate the cervix without causing any distortion. This study was performed to compare transvaginal sonography (TVUS) and TPUS at 24 weeks of gestation in predicting preterm delivery in low-risk pregnancy. Methods Three hundred fifty-seven pregnant women underwent TVUS and TPUS at 24 weeks of gestation. The relationship between cervical length and preterm delivery was assessed. Accuracy values of TVUS and TPUS at 24 weeks of gestation were compared in predicting preterm delivery. Results Preterm delivery (before 36 weeks of gestation) occurred in 22 pregnancies (6.2%). Mean cervical lengths measured by TVUS and TPUS were significantly different in preterm and term delivery groups (P < 0.05). Areas under the curves were 0.801 and 0.857 for the transvaginal and transperineal measurements, respectively. The coefficient of correlation between the transvaginal and transperineal cervical length measurements was 0.83. TPUS had a sensitivity of 77% in predicting preterm delivery, with a false-positive rate of 17% and a relative risk of 4.5 at the 32.5-mm cutoff value. Conclusions When the cervix is well visualized, TPUS can predict preterm delivery as accurately as TVUS. © 2004 Wiley Periodicals, Inc. J Clin Ultrasound 32:225,230, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jcu. 20027 [source] The accuracy of the FIB-4 index for the diagnosis of mild fibrosis in chronic hepatitis BALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 4 2009V. MALLET Summary Background, The Fib-4 index is a simple and inexpensive biomarker to delineate liver fibrosis in chronic hepatitis C. Aim, To assess the accuracy of the FIB-4 index in chronic hepatitis B. Methods, We compared the FIB-4 index with 138 synchronous liver biopsies and with 372 synchronous FibroTest performed either in France or in an endemic area (Mayotte, an overseas collectivity of France). Results, The FIB-4 index allowed the correct identification of patients with nil-to-moderate fibrosis with an area under the receiving operating characteristic curve of 0.81 (P < 0.001), increasing as a function of the length of the liver biopsy (up to 0.94 for liver biopsies ,20 mm). A cut-off value ,1.45 differentiated moderate fibrosis from severe fibrosis with a negative predictive value of 86%, a sensitivity of 71.1% and a specificity of 73.1%. Beyond 1.45, the FIB-4 index was not informative. The FIB-4 index was more precise than the AST-to-platelet ratio index and correlated with the FibroTest in 89% of the cases (, = 0.27, P < 0.001) to exclude severe fibrosis. Conclusion, The FIB-4 index is a simple, accurate and inexpensive method to exclude significant liver fibrosis in chronic hepatitis B, a major advantage in HBV-endemic developing countries. [source] Acrylic embedding of Stardust particles encased in aerogelMETEORITICS & PLANETARY SCIENCE, Issue 11 2006G. Matrajt In this report we describe a new embedding technique that uses acrylic resin instead of epoxy. This method offers several important advantages for sectioning small extraterrestrial samples. One is that the acrylic resin is soluble and can be removed after ultramicrotomy to leave a sample that is free of the mounting media. This is important for studying carbon and insoluble organic components. A second major advantage of acrylic is that, when combined with pre-embedding compression, it provides a very effective method of mounting samples collected in silica aerogel. Acrylic embedding is currently being used to mount comet particles collected by NASA's Stardust mission. Combined with a flattening process, the acrylic embedding and sectioning preserves all pieces of collected samples in their collection matrix. In addition to Stardust, acrylic may be applied to other samples collected in aerogel such as those from the Russian Mir space station (Hörz et al. 2000) and future missions such as Sample Collection for Investigation of Mars (SCIM) (Leshin 2003), a proposed mission to collect atmospheric dust particles from Mars. [source] A new time domain solution for the multiple diffraction of spherical waves by an array of nonperfectly conducting wedges for UWB signalsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2010Peng Liu Abstract A time domain (TD) solution for the analysis of multiple diffraction of spherical waves after an array of nonperfectly conducting wedges with different interior angles is presented. The proposed TD solution is based on the representation of the inverse Laplace transform of the corresponding frequency domain solution in closed form, as it is given by a hybrid of the uniform theory of diffraction (UTD)-physic optics (PO) solution. The new formulation, validated with the results from technical literature, does not need to incorporate the TD version of the higher-order diffraction coefficients and allows for the calculation of large number of wedges. It has the major advantage in terms of the mathematical complexity and computation efficiency when compared with other TD solutions. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1006,1008, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25094 [source] Muscle ultrasound in neuromuscular disordersMUSCLE AND NERVE, Issue 6 2008Sigrid Pillen MD Abstract Muscle ultrasound is a useful tool in the diagnosis of neuromuscular disorders, as these disorders result in muscle atrophy and intramuscular fibrosis and fatty infiltration, which can be visualized with ultrasound. Several prospective studies have reported high sensitivities and specificities in the detection of neuromuscular disorders. Although not investigated in large series of patients, different neuromuscular disorders tend to show specific changes on muscle ultrasound, which can be helpful in differential diagnosis. For example, Duchenne muscular dystrophy results in a severe, homogeneous increase of muscle echo intensity with normal muscle thickness, whereas spinal muscular atrophy shows an inhomogeneous increase of echo intensity with severe atrophy. A major advantage of muscle ultrasound, compared to other imaging techniques, is its ability to visualize muscle movements, such as muscle contractions and fasciculations. This study reviews the possibilities and limitations of ultrasound in muscle imaging and its value as a diagnostic tool in neuromuscular disorders. Muscle Nerve, 2008 [source] In press conditions and their effect on runnability and convertability in digital package printingPACKAGING TECHNOLOGY AND SCIENCE, Issue 4 2005Veronica Gidlöf Abstract A major advantage of digital printing is that printing can be performed on demand, but like all printing techniques it suffers from specific runnability problems. This study reports on an investigation of problems during printing and how to improve the runnability, with the aim of pointing out the most critical factors. Test printing has been performed on three different paperboard types in digital print units, based on both dry and liquid toner electrophotographic technology. The results show that the three main problems during printing were feeding in sheet-fed print units, cutting in web-fed print units, and increasing curl after printing. Feeding problems in sheet-fed print units were mainly explained by curl and varying format size of the paperboard, but also by exceeding thicknesses limits for the press. Curl after printing principally occurred due to high temperature loads caused by, for example, fusing and conditioning. Copyright © 2005 John Wiley & Sons, Ltd. [source] (217) Selective Nerve Root Injections Can Accurately Predict Level of Nerve Impairment and Outcome for Surgical Decompression: A Retrospective AnalysisPAIN MEDICINE, Issue 3 2001Kevin Macadaeg There remains significant controversy regarding the use of a vertebral selective nerve root injection (SNI) as a diagnostic and therapeutic tool. In addition, the frequency of use of such procedures in patients with radiculopathy has increased dramatically in the last few years. Based on a Medline review there has been no studies combining cervical and lumbar SNI results and comparing preoperative diagnosis to surgical findings and outcome. The purpose of this paper is to retrospectively examine and compare the sensitivity, specificity and predictive value of a good surgical outcome in patients who had an SNI and subsequent surgical intervention. 101 patients from a 1996 thru 1999 database, who were referred to 10 spine surgeons (2 orthopedic and 8 neurosurgeon) for either cervical or lumbar radiculopathy, and had SNI and various imagery studies and subsequent surgery. Patients receive SNIs at our institution if there is a discrepancy between physical exam and radiologic imagery or to confirm a putative pain generator in multilevel pathology. These patients were then retrospectively analyzed with regard to correlation to surgical level and surgical outcome. SNIs were performed by one of three pain specialists in our clinic. Approximation of the appropriate nerve root sleeve was performed using fluoroscopic imagery, a nerve stimulator and contrast. After nerve root stimulation and neurography, 0.5,0.75 cc of lidocaine 2% was injected. Pre- and post-procedural visual analog scale (VAS) pain scores were obtained from the non-sedated patient. A SNI was considered positive or negative if the patient had immediate appendicular pain relief of greater or less then ninety percent respectively. The study was designed to include only those patients that had a SNI, regardless of result, and subsequently had surgical decompression in an attempt to treat the pain that initially prompted the SNI. A statistical analysis was then performed comparing preoperative data to surgical findings and outcome. Overall, 101 patients had SNIs who subsequently underwent surgical decompression. Average duration of symptoms prior to SNI was 1.5,12 months (4 months mean). Fifteen patients presented with cervical and 86 with lumbar radiculopathy. There were a total of 110 procedures performed on these patients. VAS scores of <2 and overall pain reduction openface> 90% with respect to their pre-procedural appendicular were used to determine if a SNI was positive, negative or indeterminate. All of these patients had an MRI or CT with or without a myelogram and all went to surgery. The results yield that SNIs are able to predict surgical findings with 94% and 90% sensitivity and specificity, respectively. A good surgical outcome was determined if the patient would do the surgery again, if they were satisfied or very satisfied and had a VAS of <3 at 6- and 12-month intervals. Our data revealed that a positive SNI was able to predict a good 6-month outcome with 95% and 64% sensitivity and specificity, respectively. At 12-months, similar results were obtained of 95% and 56%. Preoperative MRI results were also evaluated and revealed a 92% sensitivity in predicting surgical findings. We had 24 false positive MRI results and 0 true negatives. Interestingly we had 8 diabetic (IDDM or NIDDM) patients or nearly 8% of our total. The odds ratio of a diabetic having a bad outcome at 12 months was 5.4 to 1. Diabetics had a 50% likelihood of having a bad 12-month outcome versus 16% for non-diabetics with a p value of 0.066. We also looked at gender, smoking history and presence of cardiovascular disease and found no significant relationship with outcomes. Our data indicate that SNIs, when performed under rigorous method, is a highly valuable tool that can accurately determine level of nerve root impairment and outcome in patients being considered for surgical decompression. With a sensitivity of 94% and a specificity of 90%, SNIs offer a major advantage over other diagnostic modalities in patients with difficult-to-diagnose radiculopathies. [source] Temperature and frequency investigations of the electrical parameters in the TGS ferroelectric transitionPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2010Ciceron Berbecaru Abstract Pure and D: alanina doped triglycin sulphate (TGS) crystals were grown from aqueous solutions. Fresh cleaved, polished and silver paste painted samples were temperature and frequency investigated. Pure crystals show nonreproducible values of the permittivity and dielectric loss crossing up and down the Curie point. More stable and much lower values of the permittivity and dielectric loss could be noticed for D: alanina doped crystals. Permittivity and loss values show different frequencies behavior related to polar or nonpolar state of crystals. Frequency dependence of permittivity and loss behavior could be related to the general picture of relaxation of different polarization mechanisms and their contributions to permittivity and loss values for dielectric materials. Much smaller and stable values of permittivity and loss, vs. temperature and frequency, were found for doped crystals. Experimental results point out for a more stable structure with dipoles mobility decreased of doped vs. pure TGS crystals. Thus, higher figure of merit of doped TGS crystals point to a major advantage for technical applications (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Biodegradable comb polyesters containing polyelectrolyte backbones facilitate the preparation of nanoparticles with defined surface structure and bioadhesive properties,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 10-12 2002A. Breitenbach Abstract A major challenge in oral peptide and protein delivery remains the search for suitable carrier systems. Therefore, a new concept was investigated combining a modified three-dimensional architecture, increased hydrophilicity of poly(lactic- co -glycolic acid) (PLGA) and charged groups in a single polymer. Biodegradable comb PLGA were synthesized by grafting short PLGA chains onto different poly(vinyl alcohol) (PVA) based backbone polyols, poly(2-sulfobutyl-vinyl alcohol) and poly(diethylaminoethyl-vinyl alcohol). The polyelectrolyte backbones were obtained by etherification of PVA with charge-containing pendent groups. The comb polymer structure could be confirmed by nuclear magnetic resonance, infrared spectroscopy, differential scanning calorimetry, elemental analysis and measurement of intrinsic viscosity. Nanoparticles (NP), as potential mucosal carriers systems, were prepared by controlled precipitation and investigated as a function of polymer composition. The amphiphilic character and the three-dimensional architecture of the novel polyesters allowed the preparation of small nanoparticles even without the use of surfactants. Surface NMR, surface charge and hydrophobicity determination indicate a core,corona-like NP structure, especially in the case of negatively charged polyesters. A structural model is proposed for the NP with an inner polyester core and an outer charged-groups-containing surface, depending on polymer composition and backbone charge density. The higher the polymer backbone charge density, the more pronounced its influence on the nanoparticle surface properties. The possibility of preparing NP without the use of a surfactant, as well as of designing the NP surface characteristics by polymer backbone charge density and polymer hydrophilic,hydrophobic balance, will be a major advantage in protein adsorption, bioadhesion and organ distribution. This makes these biodegradable polymers promising candidates for colloidal protein and peptide delivery. Copyright © 2003 John Wiley & Sons, Ltd. [source] High-performance liquid chromatography/mass spectrometric and proton nuclear magnetic resonance spectroscopic studies of the transacylation and hydrolysis of the acyl glucuronides of a series of phenylacetic acids in buffer and human plasmaRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 20 2010Elin S. Karlsson The use of high-performance liquid chromatography/mass spectrometry (HPLC/MS) and proton nuclear magnetic resonance (1H NMR) spectroscopy for the kinetic analysis of acyl glucuronide (AG) isomerisation and hydrolysis of the 1-,- O -acyl glucuronides (1-,- O -AG) of phenylacetic acid, (R)- and (S)-,-methylphenylacetic acid and ,,,-dimethylphenylacetic acid is described and compared. Each AG was incubated in both aqueous buffer, at pH 7.4, and control human plasma at 37°C. Aliquots of these incubations, taken throughout the reaction time-course, were analysed by HPLC/MS and 1H NMR spectroscopy. In buffer, transacylation reactions predominated, with relatively little hydrolysis to the free aglycone observed. In human plasma incubations the calculated rates of reaction were much faster than for buffer and, in contrast to the observations in buffer, hydrolysis to the free aglycone was a significant contributor to the overall reaction. A diagnostic analytical methodology based on differential mass spectrometric fragmentation of 1-, -O- AGs compared to the 2-, 3- and 4-positional isomers, which enables selective determination of the former, was confirmed and applied. These findings show that HPLC/MS offers a viable alternative to the more commonly used NMR spectroscopic approach for the determination of the transacylation and hydrolysis reactions of these AGs, with the major advantage of having the capability to do so in a complex biological matrix such as plasma. Copyright © 2010 John Wiley & Sons, Ltd. [source] Reformer and membrane modules plant to optimize natural gas conversion to hydrogenASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2009M. De Falco Abstract Membrane technology may play a crucial role in the efficient production of hydrogen from natural gas and heavy hydrocarbons. The present work assesses the performance of a hydrogen production plant utilizing by reformer and membrane modules (RMM), by which the hydrogen produced in reaction units is separated by Pd-based membranes. A major advantage of RMM architecture is the shift of chemical equilibria favoring hydrogen production due to the removal of hydrogen through membranes at each reaction step, thus improving hydrogen yield while simultaneously allowing methane conversion at temperatures below 650 °C. Lower operating temperatures allow location of the modules downstream of a gas turbine, achieving an efficient hybrid system producing electric power and hydrogen with a significant reduction in energy consumption of approximately 10% relative to conventional systems. Fundamental concepts are analyzed and integrated into a process scheme. Effects of variables including reactor temperature outlet, steam-to-carbon ratio and recycle ratio throughout pinch and sensitivity analysis are described. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Cell Population Modeling and Parameter Estimation for Continuous Cultures of Saccharomyces cerevisiaeBIOTECHNOLOGY PROGRESS, Issue 5 2002Prashant Mhaskar Saccharomyces cerevisiae is known to exhibit sustained oscillations in chemostats operated under aerobic and glucose-limited growth conditions. The oscillations are reflected both in intracellular and extracellular measurements. Our recent work has shown that unstructured cell population balance models are capable of generating sustained oscillations over an experimentally meaningful range of dilution rates. A disadvantage of such unstructured models is that they lack variables that can be compared directly to easily measured extracellular variables. Thus far, most of our work in model development has been aimed at achieving qualitative agreement with experimental data. In this paper, a segregated model with a simple structured description of the extracellular environment is developed and evaluated. The model accounts for the three most important metabolic pathways involved in cell growth with glucose substrate. As compared to completely unstructured models, the major advantage of the proposed model is that predictions of extracellular variables can be compared directly to experimental data. Consequently, the model structure is well suited for the application of estimation techniques aimed at determining unknown model parameters from available extracellular measurements. A steady-state parameter selection method developed in our group is extended to oscillatory dynamics to determine the parameters that can be estimated most reliably. The chosen parameters are estimated by solving a nonlinear programming problem formulated to minimize the difference between predictions and measurements of the extracellular variables. The efficiency of the parameter estimation scheme is demonstrated using simulated and experimental data. [source] The physiology of rodent beta-cells in pancreas slicesACTA PHYSIOLOGICA, Issue 1 2009M. Rupnik Abstract Beta-cells in pancreatic islets form complex syncytia. Sufficient cell-to-cell electrical coupling seems to ensure coordinated depolarization pattern and insulin release that can be further modulated by rich innervation. The complex structure and coordinated action develop after birth during fast proliferation of the endocrine tissue. These emergent properties can be lost due to various reasons later in life and can lead to glucose intolerance and diabetes mellitus. Pancreas slice is a novel method of choice to study the physiology of beta-cells still embedded in their normal cellulo-social context. I present major advantages, list drawbacks and provide an overview on recent advances in our understanding of the physiology of beta-cells using the pancreas slice approach. [source] Using the internet to research hidden populations of illicit drug users: a reviewADDICTION, Issue 9 2010Peter G. Miller ABSTRACT Aims To review the current research of hidden populations of illicit drugs users using web-based methods and discuss major advantages and disadvantages. Methods Systematic review of 16 databases, including PubMed, PsycINFO (EBSCOhost), CSA Sociological Abstracts, Expanded Academic ASAP and Google Scholar. Findings Substances researched were most commonly ,party/club drugs' (such as ecstasy) and cannabis. All of the studies reviewed concluded that the internet is a useful tool for reaching hidden populations, but is likely to impose some bias in samples. Advantages include: access to previously under-researched target groups; speed; international applications; increased ease of data entry; and improved confidentiality for respondents. The major disadvantage is a lack of representativeness of samples. Conclusions Internet research is successful at accessing hidden populations of illicit drugs users, when appropriately targeted and provides unprecedented opportunities for research across a wide range of topics within the addictions field. Findings are unlikely to be generalisable to the general public, but appropriate for describing target populations. [source] | |||||||||||||||||||||||||||||||||||||