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Conventional Techniques (conventional + techniques)
Selected AbstractsAntheraea assama Silk Fibroin-Based Functional Scaffold with Enhanced Blood Compatibility for Tissue Engineering Applications,ADVANCED ENGINEERING MATERIALS, Issue 5 2010Naresh Kasoju Abstract The architecture and surface chemistry of a scaffold determine its utility in tissue engineering (TE). Conventional techniques have limitations in fabricating a scaffold with control over both architecture and surface chemistry. To ameliorate this, in this report, we demonstrate the fabrication of an Antheraea assama silk fibroin (AASF)-based functional scaffold. AASF is a non-mulberry variety having superior qualities to mulberry SF and is largely unexplored in the context of TE. First, a 3D scaffold with biomimetic architecture is fabricated. The scaffold is subsequently made blood compatible by modifying the surface chemistry through a simple sulfation reaction. EDX and FTIR analysis demonstrate the successful sulfation of the scaffold. SEM observations reveal that sulfation has no any effect on the scaffold architecture. TGA reveals that it has increased thermal stability. The sulfation reaction significantly improves the overall hydrophilicity of the scaffold, as is evident from the increase in water holding capacity; this possibly enhances the blood compatibility. The enhancement in blood compatibility of the sulfated scaffold is determined from in vitro haemolysis, protein adsorption and platelet adhesion studies. The sulfated scaffold is non-toxic and supports cell adhesion and growth, as revealed by indirect and direct contact-based in vitro cytotoxicity assays. This study reveals that the AASF-based functional scaffold, which has biomimetic architecture and blood-compatible surface chemistry, could be suitable for TE applications. [source] Abundant Tissue Butyrylcholinesterase and Its Possible Function in the Acetylcholinesterase Knockout MouseJOURNAL OF NEUROCHEMISTRY, Issue 3 2000Bin Li Abstract: We have described recently an acetylcholinesterase (AChE) knockout mouse. While comparing the tissue distribution of AChE and butyrylcholinesterase (BChE), we found that extraction buffers containing Triton X-100 strongly inhibited mouse BChE activity. In contrast, buffers with Tween 20 caused no inhibition of BChE. Conventional techniques grossly underestimated BChE activity by up to 15-fold. In Tween 20 buffer, the intestine, serum, lung, liver, and heart had higher BChE than AChE activity. Only brain had higher AChE than BChE activity in AChE +/+ mice. These findings contradict the dogma, based mainly on observations in Triton X-100 extracts, that BChE is a minor cholinesterase in animal tissues. AChE +/- mice had 50% of normal AChE activity and AChE -/- mice had none, but all mice had similar levels of BChE activity. BChE was inhibited by Triton X-100 in all species tested, except rat and chicken. Inhibition was reversible and competitive with substrate binding. The active site of rat BChE was unique, having an arginine in place of leucine at position 286 (human BChE numbering) in the acyl-binding pocket of the active site, thus explaining the lack of inhibition of rat BChE by Triton X-100. The generally high levels of BChE activity in tissues, including the motor endplate, and the observation that mice live without AChE, suggest that BChE has an essential function in nullizygous mice and probably in wild-type mice as well. [source] Combination of microautoradiography and fluorescence in situ hybridization for identification of microorganisms degrading xenobiotic contaminantsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2003Yanru Yang Abstract One of the central topics in environmental bioremediation research is to identify microorganisms that are capable of degrading the contaminants of interest. Here we report application of combined microautoradiography (MAR) and fluorescence in situ hybridization (FISH). The method has previously been used in a number of systems; however, here we demonstrate its feasibility in studying the degradation of xenobiotic compounds. With a model system (coculture of Pseudomonas putida B2 and Sphingomonas stygia incubated with [14C] o -nitrophenol), combination of MAR and FISH was shown to be able to successfully identify the microorganisms degrading o -nitrophenol. Compared with the conventional techniques, MAR-FISH allows fast and accurate identification of the microorganisms involved in environmental contaminant degradation. [source] Doublecortin expression levels in adult brain reflect neurogenesisEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2005Sebastien Couillard-Despres Abstract Progress in the field of neurogenesis is currently limited by the lack of tools enabling fast and quantitative analysis of neurogenesis in the adult brain. Doublecortin (DCX) has recently been used as a marker for neurogenesis. However, it was not clear whether DCX could be used to assess modulations occurring in the rate of neurogenesis in the adult mammalian central nervous system following lesioning or stimulatory factors. Using two paradigms increasing neurogenesis levels (physical activity and epileptic seizures), we demonstrate that quantification of DCX-expressing cells allows for an accurate measurement of modulations in the rate of adult neurogenesis. Importantly, we excluded induction of DCX expression during physiological or reactive gliogenesis and excluded also DCX re-expression during regenerative axonal growth. Our data validate DCX as a reliable and specific marker that reflects levels of adult neurogenesis and its modulation. We demonstrate that DCX is a valuable alternative to techniques currently used to measure the levels of neurogenesis. Importantly, in contrast to conventional techniques, analysis of neurogenesis through the detection of DCX does not require in vivo labelling of proliferating cells, thereby opening new avenues for the study of human neurogenesis under normal and pathological conditions. [source] Total upper lip reconstruction with a free temporal scalp flap: Long-term follow-up ,HEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 7 2003Kao-Ping Chang MD Abstract Background. In men, reconstruction of large full-thickness defects of the upper lip requires both an inner layer to replace the mucosal lining and an outer hair-bearing layer. Methods. When locating the superficial temporal vessels, the design of the temporal flap is marked following the hairline needed. After meticulously dissecting the flap, it is inset and microanastomosed with the facial blood vessels. The internal mucosal layer of the flap is grafted on. During the follow-up period, the sensory recovery and motor functions are examined and recorded. Results. The postoperative courses were uneventful, and patients were satisfied with the results. One patient has a long follow-up period of 18 years. Conclusions. The free temporal scalp hair-bearing flap offers a reasonable alternative to conventional techniques in the reconstruction of large defects of the male upper lip or even a total upper lip. It is a single-staged, relatively simple method of providing hair-bearing skin to the upper lip. © 2003 Wiley Periodicals, Inc. Head Neck 25: 602,605, 2003 [source] Anterior cranial base reconstruction using free tissue transfer: Changing trends,HEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 2 2003Joseph Califano MD Abstract Introduction. A consecutive series of 135 patients undergoing resection for malignant tumors involving the anterior cranial base between 1976 and 1999 was reviewed. Patient and Methods. In the years from 1976,1991, free-tissue transfer was used in 5 of 76 or 6.6% of cases, whereas free-tissue reconstruction was used in 24 of 59 or 40% of cases in the years 1992,1999. Of those cases reconstructed with free-tissue transfer in 1976,1991, 60% (three of five) underwent a complex resection defined as involving dura, brain, or more than one major structure adjacent to skull base. Of those patients reconstructed with conventional (pericranial or pericranial/galeal) pedicled flaps in this time period, 35% (25 of 71) underwent a complex resection. From 1992,1999, 75% (18 of 24) of patients reconstructed with free-tissue transfer received a complex resection, whereas only 6% (2 of 35) of patients reconstructed by other means received a complex resection. Outcomes. For those patients reconstructed by free-tissue transfer, there were no instances of flap loss. Comparison of these two time periods was notable for a similar patient composition in terms of age, histologic findings, and extent of resection. Major complication rates for patients who are reconstructed with free-tissue transfer for anterior cranial base resections (31%) are similar compared with patients who have been reconstructed with conventional pedicled flaps (35%). This was noted despite an increased extent and complexity of resection in those patients who underwent free-tissue transfer reconstruction (72%) compared with those patients reconstructed by more conventional means (26%) p < .001. Conclusion. In our institution, the use of vascularized, free-tissue transfer has replaced pedicled flaps as the preferred modality for reconstructing complex anterior cranial base defects involving resection of dura, brain, or multiple major structures adjacent to local skull base, including the orbit, palate, and other structures. Complication rates for patients reconstructed with free-tissue transfer techniques is similar to those patients reconstructed by conventional techniques, despite an increase in complexity of resection in this group. © 2002 Wiley Periodicals, Inc. Head Neck 24: 000,000, 2002 [source] Comparison of intensity modulated radiation therapy (IMRT) treatment techniques for nasopharyngeal carcinomaINTERNATIONAL JOURNAL OF CANCER, Issue 2 2001Jason Chia-Hsien Cheng M.D. Abstract We studied target volume coverage and normal tissue sparing of serial tomotherapy intensity modulated radiation therapy (IMRT) and fixed-field IMRT for nasopharyngeal carcinoma (NPC), as compared with those of conventional beam arrangements. Twelve patients with NPC (T2-4N1-3M0) at Mallinckrodt Institute of Radiology underwent computed tomography simulation. Images were then transferred to a virtual simulation workstation computer for target contouring. Target gross tumor volumes (GTV) were primary nasopharyngeal tumor (GTVNP) with a prescription of 70 Gy, grossly enlarged cervical nodes (GTVLN) with a prescription of 70 Gy, and the uninvolved cervical lymphatics [designated as the clinical tumor volume (CTV)] with a prescription of 60 Gy. Critical organs, including the parotid gland, spinal cord, brain stem, mandible, and pituitary gland, were also delineated. Conventional beam arrangements were designed following the guidelines of Intergroup (SWOG, RTOG, ECOG) NPC Study 0099 in which the dose was prescribed to the central axis and the target volumes were aimed to receive the prescribed dose ± 10%. Similar dosimetric criteria were used to assess the target volume coverage capability of IMRT. Serial tomotherapy IMRT was planned using a 0.86-cm wide multivane collimator, while a dynamic multileaf collimator system with five equally spaced fixed gantry angles was designated for fixed-beam IMRT. The fractional volume of each critical organ that received a certain predefined threshold dose was obtained from dose-volume histograms of each organ in either the three-dimensional or IMRT treatment planning computer systems. Statistical analysis (paired t -test) was used to examine statistical significance. We found that serial tomotherapy achieved similar target volume coverage as conventional techniques (97.8 ± 2.3% vs. 98.9 ± 1.3%). The static-field IMRT technique (five equally spaced fields) was inferior, with 92.1 ± 8.6% fractional GTVNP receiving 70 Gy ± 10% dose (P < 0.05). However, GTVLN coverage of 70 Gy was significantly better with both IMRT techniques (96.1 ± 3.2%, 87.7 ± 10.6%, and 42.2 ± 21% for tomotherapy, fixed-field IMRT, and conventional therapy, respectively). CTV coverage of 60 Gy was also significantly better with the IMRT techniques. Parotid gland sparing was quantified by evaluating the fractional volume of parotid gland receiving more than 30 Gy; 66.6 ± 15%, 48.3 ± 4%, and 93 ± 10% of the parotid volume received more than 30 Gy using tomotherapy, fixed-field IMRT, and conventional therapy, respectively (P < 0.05). Fixed-field IMRT technique had the best parotid-sparing effect despite less desirable target coverage. The pituitary gland, mandible, spinal cord, and brain stem were also better spared by both IMRT techniques. These encouraging dosimetric results substantiate the theoretical advantage of inverse-planning IMRT in the management of NPC. We showed that target coverage of the primary tumor was maintained and nodal coverage was improved, as compared with conventional beam arrangements. The ability of IMRT to spare the parotid glands is exciting, and a prospective clinical study is currently underway at our institution to address the optimal parotid dose-volume needs to be spared to prevent xerostomia and to improve the quality of life in patients with NPC. © 2001 Wiley-Liss, Inc. [source] Production of Submicrometer Diameter Fibers by Two-Fluid Electrospinning,ADVANCED MATERIALS, Issue 17 2004H. Yu Electrospinning of nanofibers of materials that are difficult to process using conventional techniques is reported. Two fluids are electrospun (see Figure) into fibers with core/shell morphology. The "electrospinnable" shell fluid serves as a process aid to electrospin the core fluid. Three examples are illustrated: production of fibers with diameters less than 100 nm, fibers formed of low-molecular-weight polyaniline, and non-blended electrospun silk fibers. [source] Bacterial dormancy in Campylobacter: abstract theory or cause for concern?INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 6 2001John E. Moore For the past 100 years, since the birth of modern microbiology, this discipline has predominantly relied on the ability to culture micro-organisms in vitro on artificial synthetic culture media under controlled conditions in the laboratory. However, sometimes it is not possible to detect foodborne pathogens using such conventional techniques. Employment of these techniques can also lead to a delay in detection of pathogens. The ,viable but non-culturable' (VNC) cellular form has been demonstrated in Campylobacter jejuni, representing a resting or dormant stage, which is induced through cell stress including starvation. This form is extremely difficult to detect and generally requires complex and sophisticated technology which is usually not available in most routine food microbiology laboratories. This review aims at examining the role of this cell form in Campylobacter, including their historical evolution, formation, physiology, detection and to discuss the challenges that this form presents to food safety. [source] Surgery for Cardiac Valves and Aortic Root Without Cardioplegic Arrest ("Beating Heart"): Experience with a New Method of Myocardial PerfusionJOURNAL OF CARDIAC SURGERY, Issue 6 2007Tomas A. Salerno M.D. Similarly, beating heart mitral valve surgery via the trans-septal approach with the aorta unclamped, is a novel technique. We, herein, report a series of 346 patients with a variety of cardiac pathologies who were operated upon utilizing a new modality of myocardial perfusion. Among this group of patients, there were 55 patients who were diagnosed with endocarditis of one or more valves. These patients were excluded from this series of patients. Mean age was 59 ± 12, and there were 196 (67.3%) males and 95 (32.7%) females. There were six aortic root procedures, 90 mitral valve replacements (MVR), 46 mitral valve repairs, 20 MVR+ coronary artery bypass grafting (CABG), 28 tricuspid valve repairs, 106 aortic valve replacements (AVR), 17 AVR+CABG, and 8 AVR/MVR. Crude mortality for the group was 20 of 291 (6.8%). Intra-aortic balloon pump utilization at time of weaning from cardiopulmonary bypass was 6/291 (2.06%), and re-operation for bleeding was needed in 12 of 291 (4.1%) patients. Postoperative stroke occurred in 4 of 291 (1.3%) patients. In these patients, the clinical diagnosis of stroke was made prior to surgery. This initial experience with this new method of myocardial perfusion indicates that results are at least comparable, if not superior, to conventional techniques utilizing intermittent cold blood cardioplegia. [source] Posttraumatic Tricuspid Insufficiency Successfully Repaired by Conventional TechniqueJOURNAL OF CARDIAC SURGERY, Issue 4 2005Ph.D., Shoh Tatebe M.D. Preoperative echocardiography showed severe tricuspid insufficiency (TI) caused by chordal rupture and prolapse of the anterior leaflet. A novel repair technique, the "clover technique," was applied, but was unsuccessful in this case. The valve was then repaired successfully using conventional techniques, that is, insertion of an artificial chordae, plication of the prolapsing leaflet, and DeVega's annuloplasty. We present here a brief review of posttraumatic TI, and discuss effective and less expensive techniques for repair. [source] The membrane emulsification process,a reviewJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 3 2004C Charcosset Abstract Membrane emulsification has received increasing attention over the last 10 years, with potential applications in many fields. In the membrane emulsification process, a liquid phase is pressed through the membrane pores to form droplets at the permeate side of a membrane; the droplets are then carried away by a continuous phase flowing across the membrane surface. Under specific conditions, monodispersed emulsions can be produced using this technique. The purpose of the present paper is to provide a review on the membrane emulsification process including: principles of membrane emulsification, influence of process parameters and industrial applications. Small-scale applications such as drug delivery systems, food emulsions, and the production of monodispersed microspheres are also included. Compared with conventional techniques for emulsification, membrane processes offer advantages such as control of average droplet diameter by average membrane pore size and lower energy input. Copyright © 2004 Society of Chemical Industry [source] Effect of losartan on early liver fibrosis development in a rat model of nonalcoholic steatohepatitisJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 6 2007Patricio Ibañez Abstract Background and Aim:, Nonalcoholic steatohepatitis (NASH) is a metabolic disorder of the liver that may evolve into fibrosis or cirrhosis. Recent studies have shown reduction of experimental liver fibrosis with the use of angiotensin-converting-enzyme inhibitors or angiotensin-receptor antagonists. The aim of this study was to determine whether losartan can influence the early phase of fibrogenesis in an animal model of NASH. Methods:, To induce NASH, a choline-deficient diet (CDD) was given to Sprague-Dawley rats for 12 weeks. These animals were then compared with a control group receiving choline-supplemented diet (CSD) and a group fed a CDD plus losartan (10 mg/kg/day). Biochemical (serum levels of alanine aminotransferase and aspartate aminotransferase) and histological evaluation of fatty liver was performed by conventional techniques. Hydroxyproline content in liver tissue was assayed by spectrophotometry. In addition, mRNA levels of procollagen I and transforming growth factor (TGF)-, were assessed by semiquantitative RT-PCR and stellate cell activation by ,-actin immunofluorescence stain. Results:, After 12 weeks CDD induced a marked elevation of serum aminotranferases, a severe fatty liver infiltration with mild histological inflammation and fibrosis. These findings correlated with a significant increase in mRNA levels of both procollagen I and TGF-, and significant increased liver hydroxyproline content. No differences were seen between rats receiving CDD alone and rats receiving CDD plus losartan with regard to the biochemical, morphological or molecular alterations induced by the CDD. Conclusion:, Losartan does not seem to influence liver injury and fibrogenic events in the CDD model of NASH. [source] Protein crystal growth with a two-liquid system and stirring solutionJOURNAL OF SYNCHROTRON RADIATION, Issue 1 2004Hiroaki Adachi We developed two novel methods for growing large, high-quality protein crystals. A two-liquid system enables the convenient extraction of protein crystals without causing mechanical damage due to growth at the interface between two liquids. Since this system does not require limitations on solution volume, it is also suitable for the seed technique, and for growing large crystals. Another new concept is the mild stirring of the solution using the Floating And Stirring Technique (FAST) and the Micro-stirring technique. When compared to conventional techniques, both techniques result in a reduced number of crystals, as well as the growth of large crystals. [source] Impact of Thermal Diffusion on Densification During SPSJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2009Eugene A. Olevsky Spark-plasma sintering (SPS) has the potential for rapid (with heating rates reaching several hundred K/min) and efficient consolidation of a broad spectrum of powder materials. Possible mechanisms of the enhancement of consolidation in SPS versus conventional techniques of powder processing are categorized with respect to their thermal and athermal nature. This paper analyzes the influence of thermal diffusion, which is an SPS consolidation enhancement factor of a thermal nature. The Ludwig,Soret effect of thermal diffusion causes concentration gradients in two-component systems subjected to a temperature gradient. The thermal diffusion-based constitutive mechanism of sintering results from the additional driving force instigated by spatial temperature gradients, which cause vacancy diffusion. This mechanism is a commonly omitted addition to the free-surface curvature-driven diffusion considered in conventional sintering theories. The interplay of three mechanisms of material transport during SPS is considered: surface tension- and external stress-driven grain-boundary diffusion, surface tension- and external stress-driven power-law creep, and temperature gradient-driven thermal diffusion. It is shown that the effect of thermal diffusion can be significant for ceramic powder systems. Besides SPS, the results obtained are applicable to the ample range of powder consolidation techniques, which involve high local temperature gradients. The case study conducted on the alumina powder SPS demonstrates the correlation between the modeling and experimental data. It is noted that this study considers only one of many possible mechanisms of the consolidation enhancement during SPS. Further efforts on the modeling of field-assisted powder processing are necessary. [source] Production of Ceramic Green Bodies Using a Microwave-Reactive Organic BinderJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2007Kimiyasu Sato Because the pyrolysis of organic substances can result in the emission of harmful pollutant gases, a reduction in the use of organic binders is one aim of today's ceramics industry. A novel ceramic-forming process was developed that requires considerably less organic binder than conventional techniques. The process involves immobilizing reactive molecules on the surfaces of the particles, which on subsequent irradiation with microwaves, form bridges that bind the entire particle assembly together. The chemical forces involved produce strong bonds, resulting in a significant reduction in the amount of organic binder that is required to maintain the shape of the ceramic green body. This method will help to decrease emissions of harmful gases produced from pyrolysis of the binder. [source] Synthesis and Characterization of Nanoscaled Cerium (IV) Oxide via a Solid-State Mechanochemical MethodJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2006Jun Lu Solid-state reactions have the potential for direct preparation of ceramic powders and offer a low-temperature and low-cost alternative to conventional techniques for production of oxide powders. This paper describes a simple and effective mechanochemical method based on solid-state reactions during ball milling for synthesis of nanoscaled ceria (CeO2) particles. By using an organic base instead of an inorganic base, metal-ion-free nanoscaled CeO2 can also be made. The effects of annealing temperature on particle sizes and lattice strain are investigated. The results show that the average particle sizes of the particles increases and the average crystal lattice distortion decreases with the annealing temperature. Transmission electron microscopy examinations demonstrate that the CeO2 particles synthesised by this method are near-spherical shaped. [source] AN EVALUATION OF THE AVAILABLE TECHNIQUES FOR ESTIMATING MISSING FECAL COLIFORM DATA,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 6 2004Ashu Jain ABSTRACT: This paper presents the findings of a study aimed at evaluating the available techniques for estimating missing fecal coliform (FC) data on a temporal basis. The techniques investigated include: linear and nonlinear regression analysis and interpolation functions, and the use of artificial neural networks (ANNs). In all, seven interpolation, two regression, and one ANN model structures were investigated. This paper also investigates the validity of a hypothesis that estimating missing FC data by developing different models using different data corresponding to different dynamics associated with different trends in the FC data may result in a better model performance. The FC data (counts/100 ml) derived from the North Fork of the Kentucky River in Kentucky were employed to calibrate and validate various models. The performance of various models was evaluated using a wide variety of standard statistical measures. The results obtained in this study are able to demonstrate that the ANNs can be preferred over the conventional techniques in estimating missing FC data in a watershed. The regression technique was not found suitable in estimating missing FC data on a temporal basis. Further, it has been found that it is possible to achieve a better model performance by first decomposing the whole data set into different categories corresponding to different dynamics and then developing separate models for separate categories rather than developing a single model for the composite data set. [source] Molecular identification and characterization of rifampicin-resistant Mycobacterium tuberculosis isolates by line probe assay: an approach for rapid diagnosis of multidrug-resistant tuberculosisLETTERS IN APPLIED MICROBIOLOGY, Issue 3 2008C. Bicmen Abstract Aim:, Early identification and characterization of rifampicin-resistant (Rr) Mycobacterium tuberculosis isolates recovered from the samples of tuberculosis (TB) patients in the Aegean (West Anatolian) Region was intended. Methods and Results:, Sixty isolates [47 (78·3%) multidrug-resistant (MDR)], which were identified as M. tuberculosis complex and phenotypically resistant to rifampicin by both BACTEC mycobacteria growth indicator tube (MGIT) 960 and 460 systems were analysed by a commercial line probe assay (INNO-LiPA Rif TB). The concordance of LiPA with the in vitro susceptibility test was found as 98·3%. Among the isolates, S531L (R5 pattern; 46·7%) and L511P/R, S512T, Q513L/K (,S1 pattern; 11·7%) were the most frequent mutation patterns. As compared with the BACTEC systems and conventional techniques for cultivation, identification and in vitro susceptibility testing, INNO-LiPA Rif TB after cultivation in BACTEC MGIT 960 system provided an average of 20 days early diagnosis of RrM. tuberculosis isolates. Conclusions:, Rapid molecular identification and characterization of RrM. tuberculosis isolates after BACTEC MGIT 960 cultivation would be useful for faster diagnosis, infection control and planning of accurate treatment in MDR-TB patients. Significance and Impact of the Study:, Patients with MDR-TB need a specified treatment and efficient follow-up strategies. Rapid and practical methodologies to diagnose and follow these patients should be applied in routine use. [source] General algorithm for automated off-center MRIMAGNETIC RESONANCE IN MEDICINE, Issue 1 2006J. Magland Abstract A general formula was derived that automatically modifies any MRI pulse sequence to realize arbitrary field-of-view (FOV) shifts. Unlike conventional techniques for implementing off-center MRI, the new method is completely automatic and can therefore be incorporated into the scanner hardware or software, thereby simplifying the development of MRI pulse sequences. The algorithm was incorporated into a visual pulse sequence programming environment, and several pulse sequences were programmed and tested at various off-center locations using the new technique. Unless there is significant background field inhomogeneity or gradient nonlinearity, research sequences employing the automatic technique need only be programmed and tested at the gradient isocenter, whereas with conventional methods, artifacts can sometimes depend on the position of the FOV. Magn Reson Med, 2006. © 2006 Wiley-Liss, Inc. [source] Rapid cine MRI of the human heart using reconstruction by estimation of lines and inhibition of fold-inMAGNETIC RESONANCE IN MEDICINE, Issue 5 2002Wolfgang G. Rehwald Abstract A fast imaging method is described that yields an approximately six-fold acquisition time reduction relative to conventional techniques. The method involves: 1) acquisition of every sixth k -space line; 2) shifting of acquired k -space lines between odd and even frames; and 3) a single-frame correction image. Reconstruction is achieved by temporal interpolation for k -space lines not acquired combined with subtraction of stationary fold-in artifacts. Seven patients with heart disease and one volunteer were evaluated. SNR was measured in myocardium and the ventricular cavity for both the conventional and new technique. The method is best suited for fast imaging of moving objects confined to a small region within a larger stationary object, such as the heart within the thoracic cavity. It can be implemented in cine and functional imaging sequences and, in principle, in perfusion sequences. Magn Reson Med 47:844,849, 2002. © 2002 Wiley-Liss, Inc. [source] Rapid T1 mapping using multislice echo planar imagingMAGNETIC RESONANCE IN MEDICINE, Issue 4 2001Stuart Clare Abstract Determination of neurological pathology in white matter disease can be made in a semiquantitative way from T1 - or T2 -weighted images. A higher level of quantification based on measured T1 or T2 values has been either limited to specific regions of interest or to low-resolution maps. Higher-resolution T1 maps have proved difficult to obtain due to the excessively long scan times required using conventional techniques. In this study, clinically acceptable images are obtained by using single-shot echo planar imaging (EPI) with an acquisition scheme that maximizes signal-to-noise while minimizing the scan time. Magn Reson Med 45:630,634, 2001. © 2001 Wiley-Liss, Inc. [source] A Macroeconomic Model with Hysteresis in Foreign TradeMETROECONOMICA, Issue 4 2001Matthias Gocke The continuous non-linear macro-hysteresis loop is approximated by a rhombus shaped path which therefore shows a closer affinity to the genuine concept of hysteresis than conventional techniques via difference equations. This linearized model is applied to implement foreign trade hysteresis in a standard macroeconomic simultaneous equation model demonstrating the persisting consequences of only temporary exogenous shocks on national income, interest rate and the determination of the exchange rate. Since hysteresis in foreign trade is analysed in a macroeconomic framework, the feedback of hysteresis caused by exchange rate variations on the exchange rate itself can be illustrated. [source] New model for simultaneous heart and kidney transplantation in miceMICROSURGERY, Issue 2 2003Minghui Wang M.D. In clinical settings, combined heart and kidney transplantation results in a lower incidence of cardiac graft and renal graft rejection as compared to isolated heart and kidney transplantation. To study the phenomenon in an experimental setting, we developed a model of combined heart and kidney transplantation in mice. According to our technique, we kept the patch of the infrarenal aorta and inferior vena cava (IVC) as long as possible during the donor's kidney explantation, and then, after finishing the kidney implantation with conventional techniques, we anastomosed the innominate artery and pulmonary artery of the heart graft to the patch of the infrarenal aorta and IVC of the renal graft, respectively, instead of the recipient's aorta and IVC. With the use of our method, combined heart and kidney transplantation in mice can be performed to get enough suture room for the second graft, to avoid prolonging the occlusion time of the recipient's circulation, and to profoundly decrease postoperative complications such as paraplegia and mortality. Of the 14 recipients with combined heart-kidney isografting, 10 have been successful (71.4%), surviving over 100 days with normal function of both grafts, and with lack of change in histological appearance. This suggests that the technique is feasible and reliable. © 2003 Wiley-Liss, Inc. MICROSURGERY 23:164,168 2003 [source] A comparative study of transformation of micellar structures in CTAB and TTAB binary systems using Positron Lifetime SpectroscopyPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2009R. Yadav Abstract The micellar structures of cetyl-tri-methyl ammonium bromide (CTAB) and its homologues have been investigated employing several conventional techniques. However, due to lack of sensitivity inherent in these techniques and the perturbation introduced by the probe, the detailed structures of the aggregates in the so-called single phase regions of these systems are far from being fully understood. Positron has been found to be a useful non-destructive probe for investigating micellar structures in surfactant systems [1-3] The present study is an effort to get a better insight into the micellar structures and their transformations in CTAB and TTAB aqueous binary systems Positron lifetime spectroscopy has been employed to study these systems covering a wide range of surfactant concentrations. A comparative study of the results obtained for the two surfactant systems have been discussed in this paper. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effects of cold-girdling on flows in the transport phloem in Ricinus communis: is mass flow inhibited?PLANT CELL & ENVIRONMENT, Issue 1 2006ANDREAS D. PEUKE ABSTRACT The effects of cold girdling of the transport phloem at the hypocotyl of Ricinus communis on solute and water transport were investigated. Effects on the chemical composition of saps of phloem and xylem as well as of stem tissue were studied by conventional techniques and the water flow in the phloem was investigated by NMR imaging. Cold girdling reduced the concentration of sucrose but not that of inorganic solutes or amino acids in phloem saps. The possibility that cold treatment inhibited the retrieval of sucrose into the phloem, following leaching from the sieve tubes along a chemical gradient is discussed. Leaching of other solutes did not occur, as a result of missing promoting gradients in stem tissue. Following 3 d of cold girdling, sugar concentration increased and starch was synthesized and accumulated in stem tissue above the cold girdling region and along the cold-treated phloem pathway due to leaching of sugars from the phloem. Only in the very first period of cold girdling (< 15,30 min) was mass flow inhibited, but recovered in the rest of cold treatment period to values similar to the control period before and the recovery period after the cold treatment. It is concluded that cold treatment affected phloem transport through two independent and reversible processes: (1) a permanent leaching of sucrose from the phloem stem without normal retrieval during cold treatment, and (2) a short-term inhibition of mass flow at the beginning of cold treatment, possibly involving P proteins. Possible further mechanisms for reversible inhibition of water flow are discussed. [source] Online light scattering measurements: A method to assess morphology development of polymer blends in a twin-screw extruderPOLYMER ENGINEERING & SCIENCE, Issue 10 2002G. Schlatter Light scattering has proved itself an efficient technique to determine particle diameters in heterogeneous dilute dispersions in the micrometer range. Extrusion of polymer blends is expected to give rise to very small particles, typically in the range from hundreds of nanometers to tens of micrometers. A light scattering device developed in our laboratory has been used to study the morphology of polymer blends obtained in a twin-screw extruder. The main advantage of this technique is the immediate response obtained without any surface or interface modification that can occur during the sample preparation by using more conventional techniques like electron microscopy. To show the possible applications of this light scattering device, preliminary tests have been carried out. First, we present a comparison between experimental measurements and theoretical results for dilute systems. Second, we have investigated the effect of shear flow on the droplet deformation. Finally, we have studied the variations of the light scattering pattern for a reactive blend. [source] Hierarchical structures of dendritic polymersPOLYMER INTERNATIONAL, Issue 2 2010Masaki Ujihara Abstract Dendritic polymers' highly specific and three-dimensional architectures set them apart from linear and slightly branched polymers. Their unique properties also allow them to form hierarchical organizations, which can be classified as planar or non-planar. The preparation of a planar hierarchy consisting of dendritic polymers can be achieved by conventional techniques of adsorption or Langmuir monolayer and Langmuir,Blodgett accumulation, and the resultant hierarchy is well ordered. Non-planar hierarchies are built on non-planar scaffolds, for example by self-assembly. In this mini-review, the practical/potential applications of dendritic polymers such as for electrical or optical devices, sensing systems, or medical diagnosis are also reviewed in association with their structures. Copyright © 2009 Society of Chemical Industry [source] Screen-print selective diffusions for high-efficiency industrial silicon solar cellsPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 1 2008Matthew Edwards Abstract Screen-print diffusion pastes present an industrially applicable alternative to conventional techniques of dopant deposition. Several commercially available screen-print dopant pastes are assessed for their suitability in forming heavy selective diffusions for use under metal contacts in silicon solar cells. Pastes are assessed in terms of their ease of application, their ability to form heavy diffusions with low sheet resistances, and their ability to maintain high post-diffusion wafer lifetimes. Potential for the use of dopant pastes in high-efficiency solar cell devices is investigated using photoconductance (PC) measurements and photoluminescence (PL) images. It is found that under certain conditions, screen-print dopant pastes, particularly phosphorus paste, have potential to form effective selective diffusions without significantly compromising performance in high-efficiency solar cells. Copyright © 2007 John Wiley & Sons, Ltd. [source] Monetary integration in the ex-Soviet Union: A ,union of four'?*THE ECONOMICS OF TRANSITION, Issue 1 2006Vladimir Chaplygin F02; F15; E58 Abstract The governments of four ex-Soviet countries recently discussed forming a currency union. To examine the economic feasibility of this proposition, we use conventional techniques and show that the arrangement is likely to find it difficult to handle the lack of structural symmetry, the asymmetric pattern of shocks, and the lack of market flexibility among the potential participants. Moreover, the union would be a unilateral one. It would require an unusual degree of political commitment to survive. Nonetheless, there are some subtleties in the timing and pattern of mutual dependence between Russia and Kazakhstan, and to a lesser extent in Belarus, which may reduce the strain from a currency union in those countries. Otherwise, the black market will have to provide the necessary market flexibility. [source] | |||||||||||||||||||||||||