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Terms modified by Transverse Selected AbstractsDielectric Characteristics for Radio Frequency Waves in a Laboratory Dipole PlasmaCONTRIBUTIONS TO PLASMA PHYSICS, Issue 4 2006N. I. Grishanov Abstract Transverse and parallel dielectric permittivity elements have been derived for radio frequency waves in a laboratory dipole magnetic field plasma. Vlasov equation is resolved for both the trapped and untrapped particles as a boundary value problem to define their separate contributions to the dielectric tensor components. To estimate the wave power absorbed in the plasma volume the perturbed electric field and current density components are decomposed in a Fourier series over the poloidal angle. In this case, the dielectric characteristics can be analyzed independently of the solution of the Maxwell's equations. As usual, imaginary part of the parallel permittivity elements is necessary to estimate the electron Landau damping of radio frequency waves, whereas imaginary part of the transverse permittivity elements is important to estimate the wave dissipation by the cyclotron resonances. Computations of the imaginary part of the parallel permittivity elements are carried out in a wide range of the wave frequencies. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] CT and Cross-sectional Anatomy of the Normal Head of the Loggerhead Sea Turtle (Caretta caretta)ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 2005A. Arencibia The objective of this study is to describe the CT anatomy of the normal loggerhead sea turtle (Caretta caretta) head using three loggerhead sea turtle heads. CT imaging was performed using the following parameters: K.v.: 120 mAs: 220, and a soft-tissue window (WW 1880, WL 465): Transverse and sagittal CT images were obtained. Detailed anatomy of the head was acquired with the sagittal and transverse series. The heads were frozen and then sectioned using an electric saw, to compare them with the CT images. In CT, the grey scale is directly related to the radiation attenuation of the head structures. The skull and hyoid bones, and the lower jaw were easily identifiable due to the high CT density image compared to adjacent or surrounding structures such as the respiratory system, oral cavity, oesophagus and cranial cavity that appeared as a low opacity. The nervous structures, salt gland, eyeball, ramphoteca structure and different muscles of the head had an intermediate CT density and appeared grey. CT images of the loggerhead sea turtle head provided excellent detail of clinically relevant anatomy and correlated well with corresponding gross specimens. CT of the head has considerable advantages over other techniques: CT provides excellent spatial resolution and good discrimination between bone and soft tissue, and the structures are viewed without superimposition. The planimetric or sectional anatomy of the head allows a correct morphologic and topographic evaluation of the anatomic structures, which is a useful tool for the identification of the CT images. With developing technology, CT imaging may soon become more readily available for exotic animals imaging. In the same way, we consider it quite useful to be able to establish some references on head, in order to scan only selected parts during a clinical or experimental approach. The information presented in this communication should serve as an initial reference to evaluate CT images of the loggerhead sea turtle head and to assist interpretation of lesions of this region. [source] Transverse pattern formation and its control in photorefractive opticsANNALEN DER PHYSIK, Issue 7-8 2004C. Denz Abstract A wealth of periodic transverse patterns is observed in nonlinear optical, photorefractive single-feedback systems. It is the extension of a photorefractive medium in the direction of propagation of the laser beam that allows for the formation of stable hexagons, squares, rhombuses and dodecagons above the first bifurcation of the system. In this article we review the formation of these periodic patterns and present linear and nonlinear stability analyses that predict the type of pattern to appear. Amplitude equations for the interactions of unstable sidebands are introduced. We compare numerical and experimental results on two-dimensional transverse pattern formation. We present control methods for the invasive and non-invasive manipulation of different pattern states using a Fourier filtering technique. [source] Potassium-transporting proteins in skeletal muscle: cellular location and fibre-type differencesACTA PHYSIOLOGICA, Issue 2 2010M. Kristensen Abstract Potassium (K+) displacement in skeletal muscle may be an important factor in the development of muscle fatigue during intense exercise. It has been shown in vitro that an increase in the extracellular K+ concentration ([K+]e) to values higher than approx. 10 mm significantly reduce force development in unfatigued skeletal muscle. Several in vivo studies have shown that [K+]e increases progressively with increasing work intensity, reaching values higher than 10 mm. This increase in [K+]e is expected to be even higher in the transverse (T)-tubules than the concentration reached in the interstitium. Besides the voltage-sensitive K+ (Kv) channels that generate the action potential (AP) it is suggested that the big-conductance Ca2+ -dependent K+ (KCa1.1) channel contributes significantly to the K+ release into the T-tubules. Also the ATP-dependent K+ (KATP) channel participates, but is suggested primarily to participate in K+ release to the interstitium. Because there is restricted diffusion of K+ to the interstitium, K+ released to the T-tubules during AP propagation will be removed primarily by reuptake mediated by transport proteins located in the T-tubule membrane. The most important protein that mediates K+ reuptake in the T-tubules is the Na+,K+ -ATPase ,2 dimers, but a significant contribution of the strong inward rectifier K+ (Kir2.1) channel is also suggested. The Na+, K+, 2Cl, 1 (NKCC1) cotransporter also participates in K+ reuptake but probably mainly from the interstitium. The relative content of the different K+ -transporting proteins differs in oxidative and glycolytic muscles, and might explain the different [K+]e tolerance observed. [source] Geological constraints on Antarctic palaeo-ice-stream retreatEARTH SURFACE PROCESSES AND LANDFORMS, Issue 4 2008Colm Ó Cofaigh Abstract Submarine landforms preserved in bathymetric troughs on the Antarctic continental shelf show that the style of ice stream retreat across the shelf following the last glacial maximum varied between different troughs. Three styles of retreat are inferred from the geological evidence: rapid, episodic and slow. Rapid retreat by ice stream floatation and calving is recorded by the preservation of a landform assemblage of unmodified streamlined subglacial bedforms including mega-scale glacial lineations (MSGLs) that record streaming flow along these troughs. These elongate bedforms are not overprinted by recessional glacial landforms formed transverse to ice flow such as moraines or grounding-zone wedges, and overlying deglacial sediments are thin. A second type of landform assemblage consists of MSGLs overprinted or interrupted by transverse grounding-zone wedges. This assemblage implies episodic retreat between successive grounding-zone positions. The third type of landform assemblage is that of numerous, closely spaced, recessional moraines and intermittent grounding-zone wedges that overlie and interrupt MSGLs. This assemblage records the slow retreat of grounded ice across the shelf. Variation in the style of ice stream retreat between the different bathymetric troughs indicates that Antarctic palaeo-ice-streams did not respond uniformly to external forcing at the end of the last glacial cycle. Rather, their diachronous retreat reflects the dominance of local controls in the form of bathymetry and drainage basin size. More broadly, these data show that retreat of marine-based ice sheets in areas of reverse bed slope is not necessarily catastrophic, and they provide important constraints for numerical models that attempt to predict the dynamics of large polar ice sheets. Copyright © 2008 John Wiley & Sons, Ltd. [source] Influence of Transient Flow on Contaminant BiodegradationGROUND WATER, Issue 2 2001Mario Schirmer The rate of biodegradation in contaminated aquifers depends to a large extent on dispersive mixing processes that are now generally accepted to result from spatial variations in the velocity field. It has been shown, however, that transient flow fields can also contribute to dispersive mixing. The influence of transient flow on biodegrading contaminants is particularly important since it can enhance mixing with electron acceptors, further promoting the reactive process. Using numerical simulations, the effect of transient flow on the behavior of a biodegradable contaminant is evaluated here both with respect to the development of apparently large horizontal transverse dispersion and also with respect to enhanced mixing between the substrate (electron donor) and electron acceptor. The numerical model BIO3D, which solves for advective-dispersive transport coupled with Monod-type biodegradation of substrates in the presence of an electron acceptor, was used for the simulations. The model was applied in a two-dimensional plan view mode considering a single substrate. Transient flow fields were found to yield larger apparent transverse dispersion because the longitudinal dispersivity also acts transverse to the mean flow direction. In the reactive case, the transient flow field increases substrate-oxygen mixing, which in turn enhances the overall rate of biodegradation. The results suggest that in the case of moderate changes of flow directions, a steady-state flow field can be justified, thereby avoiding the higher computational costs of a fully transient simulation. The use of a higher transverse horizontal dispersivity in a steady flow field can, under these conditions, adequately forecast plume development. [source] Anisotropic Optical Properties of Semitransparent Coatings of Gold Nanocaps,ADVANCED FUNCTIONAL MATERIALS, Issue 11 2006J. Liu Abstract An ordered array of cap-shaped gold nanoparticles has been prepared by vapor deposition onto polystyrene nanospheres supported on a glass substrate. The method of fabrication used imparts a significant anisotropy to the geometric and optical properties of the coating. The optical-absorption properties of these deposits have been measured using UV-vis spectrometry and simulated using a code based on the discrete dipole approximation. Because the nanocaps are not interconnected, they interact with incident light as individual particles with a plasmon resonance that depends upon wavelength and the polarization vector of the light. The resulting extinction peaks manifest in the upper visible and near-infrared regions of the electromagnetic spectrum. Surprisingly, varying the angle of incidence of the light (for a fixed polarization) has no effect on the optical properties of individual nanocaps. Calculations show that these phenomena may be readily interpreted in terms of dipole resonances excited across the longitudinal, transverse, and short-transverse directions of the nanocaps. Coatings comprised of arrays of these particles have the potential to serve as angularly and spectrally selective filters. [source] Difference in somatosensory evoked fields elicited by mechanical and electrical stimulations: Elucidation of the human homunculus by a noninvasive methodHUMAN BRAIN MAPPING, Issue 4 2005Ken Inoue Abstract We recently recorded somatosensory evoked fields (SEFs) elicited by compressing the glabrous skin of the finger and decompressing it by using a photosensor trigger. In that study, the equivalent current dipoles (ECDs) for these evoked fields appeared to be physiologically similar to the ECDs of P30m in median nerve stimulation. We sought to determine the relations of evoked fields elicited by mechanically stimulating the glabrous skin of the great toe and those of electrically produced P40m. We studied SEFs elicited by mechanical and electrical stimulations from the median and tibial nerves. The orientations of dipoles from the mechanical stimulations were from anterior-to-posterior, similar to the orientations of dipoles for P30m. The direction of the dipole around the peak of N20m from median nerve electrical stimulation was opposite to these directions. The orientations of dipoles around the peak of P40m by tibial nerve stimulation were transverse, whereas those by the compression and decompression stimulation of the toe were directed from anterior-to-posterior. The concordance of the orientations in ECDs for evoked fields elicited by mechanical and electrical stimulations suggests that the ECDs of P40m are physiologically similar to those of P30m but not to those of N20m. The discrepancy in orientations in ECDs for evoked field elicited by these stimulations in the lower extremity suggests that electrical and compression stimulations elicit evoked fields responding to fast surface rubbing stimuli and/or stimuli to the muscle and joint. Hum. Brain Mapping 24:274,283, 2005. © 2005 Wiley-Liss, Inc. [source] A comparison between clearing and radiographic techniques in the study of the root-canal anatomy of maxillary first and second molarsINTERNATIONAL ENDODONTIC JOURNAL, Issue 5 2004O. E. Omer Abstract Aim, To compare a clearing technique with conventional radiography in studying certain features of the root-canal system of maxillary right first and second molars. A secondary aim was to assess interexaminer agreement for these features using radiographs. Methodology, Eighty-three recently extracted permanent maxillary right first molars and 40 recently extracted maxillary right second molars from an Irish population were included. Standard periapical radiographs were taken from a buccolingual and mesiodistal direction. The specimens were then decoronated, demineralized in 10% hydrochloric acid for 8 days and then cleared using methyl salicylate. The cleared teeth were examined using a dissecting microscope (×20), and data relating to number of roots, canal type following Vertucci's classification, presence of lateral canals, presence of transverse anastomoses and position/number of apical foramina were collected. The radiographs were examined by two independent trained endodontists using an X-ray viewer and a magnifying lens (×2) in a dark room for the same features studied using the clearing technique. Results, The Kappa values for the agreement between the radiographic examiners A and B and the clearing technique and between the two examiners for the number of roots were 0.60, 0.64 and 0.53; for the root-canal type, 0.37, 0.41 and 0.42; for the number of roots with lateral canals, 0.21, 0.18 and 0.14; and for the transverse anastomoses, 0.29 for radiographic Examiner A. Radiographic Examiner B did not feel capable of accurately recognizing transverse anastomoses from the radiographs. For the position/number of apical foramina, the Kappa values were 0.33 and 0.24, respectively. In general, the Kappa values were low to modest for all comparisons. Conclusions, It is concluded that the agreement between the two radiographic examiners and the agreement between either radiographic examiner and the clearing technique were poor to moderate, indicating the limited value of radiographs alone when studying certain aspects of the root-canal system. [source] Template Synthesis of Hierarchically Structured Composites,ADVANCED MATERIALS, Issue 15 2008Wei Wei Abstract The subtle performance of a virus is closely related to its specific hierarchical structure, which is composed of a rigid shell and transverse, responsive, nanometer-sized channels. Virus-like structured colloids are of great interest for their potential applications, for example in drug delivery. Adequate knowledge of the structure and composition control of both colloids and mesoporous materials is significant in the design and synthesis of hierarchically structured colloids to mimic viruses. Some recent developments in the synthesis of composite colloids and mesoporous materials are summarized. Template synthesis is a major tool to control both the macroscopic morphology and microstructures of these composites, in which gel colloids and supramolecular structures from amphiphilic species are used as templates. [source] Hyperchaotic behaviour of two bi-directionally coupled Chua's circuitsINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 6 2002Barbara Cannas Abstract In this paper, a non-linear bi-directional coupling of two Chua's circuits is presented. The coupling is obtained by using polynomial functions that are symmetric with respect to the state variables of the two Chua's circuits. Both a transverse and a tangent system are studied to ensure a global validity of the results in the state space. First, it is shown that the transverse system is an autonomous Chua's circuit, which directly allows the evaluation of the conditions on its chaotic behaviour, i.e. the absence of synchronization between the coupled circuits. Moreover, it is demonstrated that the tangent system is also a Chua's circuit, forced by the transverse system; therefore, its dynamics is ruled by a time-dependent equation. Thus, the calculus of conditional Lyapunov exponents is necessary in order to exclude antisynchronization along the tangent manifold. The properties of the transverse and tangent systems simplify the study of the coupled Chua's circuits and the determination of the conditions on their hyperchaotic behaviour. In particular, it is shown that hyperchaotic behaviour occurs for proper values of the coupling strength between the two Chua's circuits. Finally, numerical examples are given and discussed. Copyright © 2002 John Wiley & Sons, Ltd. [source] Metastatic cutaneous leiomyosarcoma from primary neoplasm of the mesenteryINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 8 2001Kyoung Jin Kim MD A 31-year-old South Korean woman was referred to the dermatology department from the oncology department for the evaluation of a subcutaneous nodular lesion on the back. Three years before, she noted a palpable, fingertip-sized, nontender mass on her right lower abdomen. The mass had increased in size slowly. One year ago, she visited a local clinic and physical examination revealed a 7 × 8 × 7 cm, slightly tender, deep-seated mass on the right lower quadrant of the abdomen. The mass on the ilial mesentery was resected by surgical exploration and tissue examination revealed leiomyosarcoma. She refused adjuvant chemotherapy. Approximately 3 months later, she re-visited the clinic with a tender, subcutaneous nodule on the back. Cutaneous examination revealed a solitary, 2 × 2 cm, well-defined, hard, movable, subcutaneous nodule on the upper back without skin color change (Fig. 1). She complained of tenderness on touching the lesion. Histologic examination of a biopsy specimen showed irregularly arranged spindle cells scattered throughout the dermis. They were arranged in haphazardly oriented or interweaving fascicles. Most of the spindle cells possessed elongated nuclei with blunt ends and some cells had a polygonal outline with irregularly shaped nuclei (Fig. 2). There were many mitoses: 3,4 per high-power (× 400) field. Immunohistochemically, smooth muscle actin and desmin were positive in most of the tumor cells (Fig. 3). S-100 reactivity was not observed. A diagnosis of metastatic leiomyosarcoma was made. About 1 month later, computed tomography showed two, ill-defined, heterogeneous, low attenuation masses in the right lobe of the liver, suggesting liver metastasis. The patient was treated with chemotherapy for 2 months and remains in good condition. Figure 1. 2 × 2 cm, solitary, well-defined, hard, movable, subcutaneous nodule without any overlying skin change Figure 2. (a) Characteristic findings of cutaneous leiomyosarcoma with markedly high cellularity and densely packed transverse and longitudinal fascicles of cells (hematoxylin and eosin, × 40). (b) High magnification of the neoplasm revealing spindle cells with blunt-ended nuclei, pleomorphism, and mitotic figures (hematoxylin and eosin, × 200) Figure 3. Dense cytoplasmic reactivity for smooth muscle actin is apparent (smooth muscle actin, × 200) [source] An investigation into time domain Doppler modelling using the TLM numerical methodINTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 5 2007I. J. G. Scott Abstract The effects observed by a moving source and stationary receiver, or conversely stationary source and moving receiver are well known to physicists. The Doppler effect as it is commonly known is recognized as a perceived change in frequency of the incident signal upon the receiver, caused by the motion of either the source or receiver with respect to the stationary component, occurring in both electromagnetic (transverse) and acoustic (longitudinal) waves. This paper will primarily focus on the acoustic Doppler effect in the time domain, simulating a variety of scenarios using transmission line matrix (TLM) modelling in which the effect can be observed, proceeding to compare the accuracy of the various models generated. A new technique to allow arbitrary placement of boundaries of a TLM mesh will also be introduced and analysed allowing accurate placement of the moving walls within the simulation. Copyright © 2007 John Wiley & Sons, Ltd. [source] Limb bones asymmetry and stress in medieval and recent populations of Central EuropeINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 5 2008M. Kujanová Abstract Monitoring the degree of asymmetry in different parts of the human body can contribute to population studies, as it may be connected indirectly with the social structure, living conditions, and also with biomechanical stress affecting the person. Analysis of asymmetry may also assess preferential use of the right or left of the body during specific activities. This study is based on the measurements of bones of the upper and lower limbs of skeletons derived from the remarkable medieval cemeteries of Mikul,ice-Kostelisko (78 male, 132 female) and Pru,ánky (66 male, 69 female) (9th,12th centuries AD), and a series of skeletons representing a recent population from Bohemia (143 male, 157 female). The objective was to assess directional asymmetry (DA), fluctuating asymmetry (FA) and antisymmetry (AS) of the dimensions of the evaluated bones, and to use these data to compare the characteristics of the medieval and recent populations. DA was recorded in most dimensions. In the upper limb, the humerus exhibited the greatest expression of asymmetry, and, with the exception of the clavicle, DA was always more pronounced on the right side. Conversely, DA was less prevalent in the lower limb bones. It was more pronounced on the transverse, sagittal and circumferential dimensions of the diaphyses and epiphyses than on the length, and in most cases it was on the left side. The FA values were very low, and almost negligible in relation to the size. Nevertheless, FA was markedly more frequent on the lower than on the upper limb. In contrast to the medieval population, the recent population had higher FA and DA values. Thus, we propose that people from this medieval population were subjected to lower developmental stress than the recent sample. Copyright © 2008 John Wiley & Sons, Ltd. [source] Determination by high-resolution X-ray diffraction of shape, size and lateral separation of buried empty channels in silicon-on-nothing architecturesJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2 2007Marco Servidori High-resolution multi-crystal X-ray diffraction was employed to characterize silicon-on-nothing samples made by a one-dimensional periodic planar array of buried empty channels. When the channels are normal to the scattering plane, under the constraint of lattice continuity from the perfect substrate to the surface, this periodic array gives rise to a well defined Fraunhofer diffraction in a scan crossing a selected reciprocal lattice point and normal to the reciprocal lattice vector (transverse or , scan). In a longitudinal scan (,/2, scan crossing the reciprocal lattice point and parallel to the reciprocal lattice vector) interference fringes are observed. By analysis of the , scan and numerical fit of the ,/2, scan, the period of the buried empty channels and their shape, size and lateral gap were easily determined, thanks to the high-resolution optics used for the measurements. [source] Effect of neutron irradiation on the structural, mechanical, and thermal properties of jute fiberJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008E. Sinha Abstract This article describes the effect of neutron irradiation on jute fiber (Corchorus olitorius). The jute fibers (4.0 tex) were irradiated by fast neutrons with an energy of 4.44 MeV at different fluences ranging from 2 × 109 to 2 × 1013 n/cm2. An important aspect of neutron irradiation is that the fast neutrons can produce dense ionization at deep levels in the materials. Structural analysis of the raw and irradiated fibers were studied by small-angle X-ray scattering (SAXS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy. Thermal analysis carried out on the raw and irradiated fibers showed that the thermal stability of the fibers decreased after irradiation. The mechanical properties of the jute fibers were found to decrease after irradiation. The SAXS study showed that the average periodicity transverse to the layer decreased after irradiation, which may have been due to the shrinkage of cellulosic particles constituting the fiber. The residual compressive stress developed in the fiber after irradiation resulted in a decrease in crystallite size as supported by our XRD analysis. Observation with SEM did not indicate any change produced in the surface morphology of the fiber due to irradiation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Influence of Orthogonal Overload on Human Vertebral Trabecular Bone Mechanical Properties,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 11 2007Arash Badiei Abstract The aim of this study was to investigate the effects of overload in orthogonal directions on longitudinal and transverse mechanical integrity in human vertebral trabecular bone. Results suggest that the trabecular structure has properties that act to minimize the decrease of apparent toughness transverse to the primary loading direction. Introduction: The maintenance of mechanical integrity and function of trabecular structure after overload remains largely unexplored. Whereas a number of studies have focused on addressing the question by testing the principal anatomical loading direction, the mechanical anisotropy has been overlooked. The aim of this study was to investigate the effects of overload in orthogonal directions on longitudinal and transverse mechanical integrity in human vertebral trabecular bone. Materials and Methods: T12/L1 vertebral bodies from five cases and L4/L5 vertebral bodies from seven cases were retrieved at autopsy. A cube of trabecular bone was cut from the centrum of each vertebral body and imaged by ,CT. Cubes from each T12/L1 and L4/L5 pairs were assigned to either superoinferior (SI) or anteroposterior (AP) mechanical testing groups. All samples were mechanically tested to 10% apparent strain by uniaxial compression according to their SI or AP allocation. To elucidate the extent to which overload in orthogonal directions affects the mechanical integrity of the trabecular structure, samples were retested (after initial uniaxial compression) in their orthogonal direction. After mechanical testing in each direction, apparent ultimate failure stresses (UFS), apparent elastic moduli (E), and apparent toughness moduli (u) were computed. Results: Significant differences in mechanical properties were found between SI and AP directions in both first and second overload tests. Mechanical anisotropy far exceeded differences resulting from overloading the structure in the orthogonal direction. No significant differences were found in mean UFS and mean u for the first or second overload tests. A significant decrease of 35% was identified in mean E for cubes overloaded in the SI direction and then overloaded in the AP direction. Conclusions: Observed differences in the mechanics of trabecular structure after overload suggests that the trabecular structure has properties that act to minimize loss of apparent toughness, perhaps through energy dissipating sacrificial structures transverse to the primary loading direction. [source] Four-dimensional sonography with B-flow imaging and spatiotemporal image correlation for visualization of the fetal heartJOURNAL OF CLINICAL ULTRASOUND, Issue 4 2008Toshiyuki Hata MD Abstract Purpose. To use B-flow imaging with 4-dimensional (4D) sonography and spatiotemporal image correlation (STIC) in the evaluation of normal fetal heart and congenital heart disease during pregnancy. Method. Volume data sets of the fetal heart were acquired with automated transverse and longitudinal sweeps of the anterior chest wall. We studied 13 normal fetuses and 2 fetuses with congenital heart disease (1 double-outlet right ventricle and 1 hypoplastic left heart syndrome) at gestation ages ranging from 13 to 39 weeks using transabdominal 4D B-flow sonography with STIC (4D BF-STIC). Results. 4D BF-STIC demonstrated dynamic angiographic features in both normal and abnormal fetal hearts. 4D BF-STIC images could not be obtained in 2 normal fetuses at 18.1 and 33.1 weeks because of the high fetal heart rate and inappropriate fetal position. In normal fetal heart, characteristic hemodynamic changes in both atria and ventricles were clearly demonstrated in systole and diastole. 4D BF-STIC also allowed visualization of the relationship, size, and course of the outflow tracts, thus helping the examiner to better understand the relationships between the vessels. In a case of hypoplastic left heart syndrome, dramatic hemodynamic changes including the right atrium, right ventricle, and pulmonary artery were evident. In a case of double-outlet right ventricle with ventricular septal defect, left-to-right shunt flow through a ventricular septal defect was clearly shown, as were great arteries originating in parallel from the right ventricle. Conclusion. 4D BF-STIC provides a means of real-time 3-dimensional evaluation of fetal intracardiac and extracardiac hemodynamics in the second and third trimesters. This novel technique assists in the evaluation of fetal cardiac hemodynamics and may play an important role in future fetal cardiac research and in the evaluation of congenital heart disease in the fetus. © 2008 Wiley Periodicals, Inc. J Clin Ultrasound, 2008. [source] Sonographic assessment of clubfootJOURNAL OF CLINICAL ULTRASOUND, Issue 5 2004Cosimo Gigante MD Abstract Purpose This study was performed to develop a standardized methodology for the sonographic assessment of clubfoot at birth and at the end of both conservative treatment and surgical correction. Methods Forty-two congenital clubfeet and 42 normal feet were examined sonographically in the position of spontaneous alignment and during passive manual correction. Scans along 4 planes provided information relevant to the assessment: sagittal posterior, sagittal anterior, coronal lateral, and transverse. Results Sagittal posterior sonograms demonstrated the progressive gain of dorsiflexion ability during the different steps of treatment for clubfoot. Sagittal anterior sonograms could not demonstrate the normal alignment of the navicular in clubfeet because of the bone's medial displacement. On transverse sonograms, the talar head and the medially displaced navicular may lie on the same plane, depending on the severity of the deformity. Coronal lateral sonograms provided for estimation of the relationships between the calcaneus and cuboid, which were described by the calcaneal-cuboid angle. Conclusions Sonography is a promising technique for assessment and monitoring of clubfoot during treatment. The method described here yields accurate and reproducible information about the anatomy of the nonossified clubfoot, helping the orthopedic team decide on appropriate treatment steps. © 2004 Wiley Periodicals, Inc. J Clin Ultrasound 32:235,242, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jcu.20022 [source] A simple method for orienting silk and other flexible fibres in transmission electron microscopy specimensJOURNAL OF MICROSCOPY, Issue 3 2001J. E. Trancik When microstructures are characterized by transmission electron microscopy (TEM), the interpretation of results is facilitated if the material can be sectioned in defined orientations. In the case of fibres, it is especially useful if transverse and longitudinal sections can be obtained reliably. Here we describe a procedure for orienting spider silk and other flexible fibres for TEM investigation. Prior to embedding in epoxy resin, the silk is wound around a notched support made from polyester film. No glue is required. After the silk and its supporting film have been embedded and the resin has been cured the film can be peeled away to reveal nearly perfectly orientated silk threads. Both transverse and longitudinal sections can then be cut with a microtome. The method can be extended to obtain sections at any intermediate orientation. [source] Venous Infarction of Brainstem and CerebellumJOURNAL OF NEUROIMAGING, Issue 4 2001Yakup Krespi MD ABSTRACT The authors describe 2 cases of posterior fossa venous infarction. A 56-year-old woman with essential thrombocytemia presented with fluctuating complaints of headache, nausea, vomiting, left-sided numbness-weakness, and dizziness and became progressively stuporous. Cranial magnetic resonance imaging (MRI) showed bilateral parasagittal frontoparietal and left cerebellar contrast-enhancing hemorrhagic lesions. On magnetic resonance venography, the left transverse and sigmoid sinuses were occluded. The second patient, a 39-year-old woman, presented with acute onset of diplopia, numbness of the tongue, vertigo, and right-sided weakness following a gestational age stillbirth. MRI revealed lesions in the right half of midbrain and pons and in the superior part of the right cerebellar hemisphere. Digital subtraction angiography showed right transverse and sigmoid sinus occlusion. The authors suggest that one should investigate the possibility of venous infarction in the presence of posterior fossa lesions that are often hemorrhagic and are not within any arterial territory distribution but respect a known venous drainage pattern. Recognition of the observed clinical and neuroimaging features can lead to earlier diagnosis and, potentially, more effective management. [source] The effect of the addition of poly(methyl methacrylate) fibres on some properties of high strength heat-cured acrylic resin denture base materialJOURNAL OF ORAL REHABILITATION, Issue 3 2003D. Jagger summary, The self-reinforcement of acrylic resin with butadiene styrene surface treated poly(methyl methacrylate) fibres has been reported to have the potential to substantially improve the transverse bend strength of conventional heat-cured acrylic resin. The aim of this study was to investigate the effect of the addition of butadiene styrene surface treated poly(methyl methacrylate) fibres in cross-ply arrangement to high impact acrylic resin on the transverse and impact strength. Specimens were prepared as specified in the International Standard Organization and British Standards for the Testing of Denture Base Resins (ISO 1567, 1988; BS 2487, 1989) and the British Standard Specification for Orthodontic resins (BS 6747, 1987) for transverse bend and impact testing. The impact strength was measured using a Zwick pendulum impact tester and the transverse bend strength measured using a Lloyds Instruments testing machine. The results showed that the impact strength was not improved with the addition of fibres, high impact acrylic resin with fibres (LF) 11·1 kJ m,2 and high impact acrylic resin (L) (12·5 kJ m,2). The modulus of rupture was decreased with the addition of fibres (57·8 MPa) for (LF) compared with (60·4 MPa) for (L). The modulus of elasticity was also reduced with the addition of fibres (1834·9 MPa) (LF) and 2086·2 MPa (L) as was the peak load (LF) (50·8 N) and (L) (55·8 N). It was concluded that the addition of surface treated poly(methyl methacrylate) fibres in cross-ply arrangement to high strength acrylic resin did not produce an improvement in the impact or transverse strength and cannot be recommended as a method of reinforcement. [source] Sex differences in coupled knee motions during the transition from non-weight bearing to weight bearingJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 6 2009Sandra J. Shultz Abstract Knee ligament injuries frequently happen when the joint transitions from non-weight bearing (NWB) to weight bearing (WB). To gain insight into the mechanism that produces these injuries, physically active females (N,=,41) and males (N,=,39) underwent measurement of coupled tibiofemoral joint displacements [anterior tibial translation (ATT) and varus,valgus and internal,external rotations] and neuromuscular responses as the knee transitioned from NWB to WB in response to a 40% body weight load applied under the control of gravity. The transition from NWB to WB produced no difference in ATT between males and females; however, significant sex-based differences were noted for both transverse and frontal plane knee motions. With the knee NWB, females were in a greater absolute valgus compared to males (6.6 vs. 5.0°), and moved through greater varus motion than males during the transition from NW to WB (2.3 vs. 1.4°), resulting in similar valgus alignment for both sexes at peak WB (4.3 vs. 3.6°). In the transverse plane, the knees of females were positioned in more external rotation compared to males when NWB (1.4 vs. ,0.3°), then females externally rotated their knees while males internally rotated their knees during the transition from NWB to WB. This resulted in a 3.4° difference in transverse plane knee position at peak WB (2.3 vs. ,1.1°). Our findings suggest that the coupled knee motions produced during the transition from NWB to WB are sex dependent, and may provide insight into the knee motion patterns that place females at increased risk of knee ligament injury. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27: 717,723, 2009 [source] Transcallosal White Matter Degradation Detected With Quantitative Fiber Tracking in Alcoholic Men and Women: Selective Relations to Dissociable FunctionsALCOHOLISM, Issue 7 2010Adolf Pfefferbaum Introduction:, Excessive alcohol consumption can adversely affect white matter fibers and disrupt transmission of neuronal signals. Here, we examined six anatomically defined transcallosal white matter fiber bundles and asked whether any bundle was specifically vulnerable to alcohol, what aspect of white matter integrity was most affected, whether women were more vulnerable than men, and whether evidence of compromise in specific bundles was associated with deficits in balance, sustained attention, associative learning, and psychomotor function, commonly affected in alcoholics. Methods:, Diffusion tensor imaging quantitative fiber tracking assessed integrity of six transcallosal white matter bundles in 87 alcoholics (59 men, 28 women) and 88 healthy controls (42 men, 46 women). Measures included orientational diffusion coherence (fractional anisotropy, FA) and magnitude of diffusion, quantified separately for axial (longitudinal; ,L) and radial (transverse; ,T) diffusivity. The Digit Symbol Test and a test of ataxia were also administered. Results:, Alcoholism negatively affected callosal FA and ,T of all but the sensory-motor bundle. Women showed no evidence for greater vulnerability to alcohol than men. Multiple regression analyses confirmed a double dissociation: higher diffusivity in sensory-motor and parietal bundles was associated with poorer balance but not psychomotor speed, whereas higher diffusivity in prefrontal and temporal bundles was associated with slower psychomotor speed but not balance. Conclusions:, This study revealed stronger alcohol effects for FA and radial diffusivity than axial diffusivity, suggesting myelin degradation, but no evidence for greater vulnerability to alcohol in women than men. The presence of brain-behavior relationships provides support for the role of alcoholism-related commissural white matter degradation as a substrate of cognitive and motor impairment. Identification of a double dissociation provides further support for the role of selective white matter integrity in specific domains of performance. [source] SEXUAL REPRODUCTION, MATING SYSTEM, AND PROTOPLAST DYNAMICS OF SEMINAVIS (BACILLARIOPHYCEAE)1JOURNAL OF PHYCOLOGY, Issue 5 2002Victor A. Chepurnov Cell division, the mating system, and auxosporulation were studied in the marine epipelic diatom Seminavis cf. robusta Danielidis & D. G. Mann. The interphase protoplast contains two girdle-appressed chloroplasts, each with an elongate bar-like pyrenoid, and also a central nucleus, located in a bridge between two vacuoles. Before cell division, the chloroplasts divide transversely and translocate onto the valves. The nucleus relocates to the ventral side for mitosis. After cytokinesis and valve formation, the chloroplasts move back to the girdle, showing a constant clockwise movement relative to the epitheca of the daughter cell. Seminavis cf. robusta is dioecious, and sexual reproduction is possible once cells are less than 50 ,m. In crosses of compatible clones, gametangia pair laterally, without the formation of a copulation envelope, and produce two gametes apiece. The intensity of sexualization increases as cells reduce further in size below the 50-,m threshold. At plasmogamy, the gametangia dehisce fully and the gametes, which were morphologically and behaviorally isogamous, fuse in the space between the gametangial thecae. The auxospore forms a transverse and longitudinal perizonium. After expansion is complete, there is an unequal contraction of the protoplast within the perizonium, creating the asymmetrical shape of the vegetative cell. Apart from this last feature, almost all characteristics exhibited by the live cell and auxospores of Seminavis agree with what is found in Navicula sensu stricto, supporting the classification of both in the Naviculaceae. Haploid parthenogenesis and polyploid auxospores were found, lending support to the view that change in ploidy may be a significant mechanism in diatom evolution. [source] A dynamic model of colonic concentrations of delayed-release 5-aminosalicylic acid (Asacol)ALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 11 2009M. P. THORPE Summary Backround, 5-ASA in a pH sensitive tablet (Asacol) is administered as three doses/day to treat ulcerative colitis. Once daily dosing may improve patient adherence. Simulation of colonic levels of 5-ASA can be used to compare dosing regimens. Aim, To create a dynamic model of colonic concentrations of delayed-release 5-aminosalicylic acid (Asacol). Methods, Using published data, we created a computer model with STELLA software to simulate amounts of colonic 5-ASA in the total colon, right, transverse, descending and sigmoid/rectum after daily and three time/day Asacol. Results, The model predicted similar total and regional amounts of 5-ASA with both regimens. Distribution of 5-ASA was 38% in the right colon, 33% in the transverse colon and 14% each in the descending and sigmoid/rectal colon. Simulated increases in colonic motility and defecation rate exaggerated this 5-ASA distribution, resulting in negligible amounts of 5-ASA in the sigmoid/rectal region. Conclusions, This computer model suggests that Asacol can be administered as a single daily dose. The model supports experimental and clinical observations that alternate dose or route of administration may be necessary to achieve adequate 5-ASA amounts in the distal colon during acute exacerbations of ulcerative colitis. This simulation cannot account for all sources of variability in the clinical setting, but provides a rationale for further investigation. [source] GeV-acceleration of electron by a superintense ultrashort laser pulseLASER PHYSICS LETTERS, Issue 8 2004A. Bahari Abstract New mechanism of laser acceleration of a charged particle is discovered and explained. Particle acceleration with focused beam of superintense ultrashort laser pulse is determined by a combination of ponderomotive forces at rising and falling edges of laser pulse and a longitudinal component of laser electric field. We found that acceleration of electron, which moves along the laser wavevector, is crucially depends on whether or not the electron reaches the region z , zR behind the laser focus (here zR is the Rayleigh length). Interpretation of this effect consists in that the laser longitudinal electric field at the electron trajectory in this region is a unidirectional one (oscillatory in the case of laser linear polarization and slowly varying in the case of laser circular polarization). Due to this effect it is possible to overcome the negative influence of a phase slippage in the particle- wave interaction, which substantially suppresses electron acceleration. We revealed also that the physical reason of a unidirectional influence of laser longitudinal electric field on accelerating electron in the region z , zR consists in the difference in phase velocities of transverse and longitudinal components of a focused laser field. Owing to this mechanism, lasers of ultimate present-day parameters enable electron acceleration up to the energy , , 1 GeV. Moreover, electron acceleration along the laser wavevector (in contrast to techniques currently considered) is not sensitive to field initial phase (there is no bunch effect), it is possible to accelerate slow electrons (electrons need not to be preaccelerated to relativistic velocities), and there are no problems with a removal of accelerated electron from the laser field. (© 2004 by ASTRO, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Cooperative interaction of n -butylammonium ion with 1,3-alternate tetrapropoxycalix [4]arene: NMR and theoretical studyMAGNETIC RESONANCE IN CHEMISTRY, Issue 5 2008Jaroslav K Abstract The interaction of 1,3-alternate tetrapropoxycalix[4]arene (1) with n -butylammonium ion (2) in CD2Cl2 was examined using 1H, 13C and 14N NMR spectroscopy and DFT (density functional theory) calculations. NMR shows that 1 forms with 2 an equimolecular hydrogen-bonded complex with the equilibrium constant 5.91 × 103 l/mol at 296 K. The structure of the complex can be shown to be asymmetric at 203 K, with 2 interacting by hydrogen bonds with the two ethereal oxygen atoms of one half of 1 and with the , system of the other half, but is rapidly averaged to an apparent C4h symmetry by chemical exchange at higher temperatures. Using two related but independent techniques based on transverse and rotating-frame proton relaxation, it is shown that only an intermolecular exchange of 2 between the bound and free states takes place, in contrast to previously studied interaction of 1 with H3O+. Its correlation time is 0.169 ms. It is shown by DFT calculations that such swift exchange is not possible without a cooperative interaction of both 2 and 1 with several molecules of water present. Similarities and contrasts between the exchange processes of 2 and H3O+ bound to 1 are discussed, in particular with respect to the apparent quantum tunneling of the latter inside the molecule of the complex. Copyright © 2008 John Wiley & Sons, Ltd. [source] Direct measurement of the transverse and longitudinal 15N chemical shift anisotropy,dipolar cross-correlation rate constants using 1H-coupled HSQC spectraMAGNETIC RESONANCE IN CHEMISTRY, Issue 10 2003Jennifer B. Hall Abstract We describe direct methods for the measurement of the transverse and longitudinal 15N chemical shift anisotropy,dipolar cross-correlation rates based on comparison of the 15N doublet components observed in 1H-coupled 1H,15N HSQC-type spectra. This allows the determination of the cross-correlation rates with no need for correction factors associated with other methods. The signal overlap problem of coupled HSQC spectra is addressed by using the IPAP scheme (Ottiger M, Delaglio F, Bax A. J. Magn. Reson. 1998; 131: 373). The methods proposed here use a conventional t1 evolution period, which allows one to minimize the truncation artifacts observed in a constant-time-type experiment (Hall JB, Dayie K, Fushman D. J. Biomol. NMR 2003; 26: 181). Applications of these measurements to the B3 domain of protein G are discussed. Copyright © 2003 John Wiley & Sons, Ltd. [source] In vivo MR elastography of the prostate gland using a transurethral actuatorMAGNETIC RESONANCE IN MEDICINE, Issue 3 2009Rajiv Chopra Abstract Conventional approaches for MR elastography (MRE) using surface drivers have difficulty achieving sufficient shear wave propagation in the prostate gland due to attenuation. In this study we evaluate the feasibility of generating shear wave propagation in the prostate gland using a transurethral device. A novel transurethral actuator design is proposed, and the performance of this device was evaluated in gelatin phantoms and in a canine prostate gland. All MRI was performed on a 1.5T MR imager using a conventional gradient-echo MRE sequence. A piezoceramic actuator was used to vibrate the transurethral device along its length. Shear wave propagation was measured transverse and parallel to the rod at frequencies between 100 and 250 Hz in phantoms and in the prostate gland. The shear wave propagation was cylindrical, and uniform along the entire length of the rod in the gel experiments. The feasibility of transurethral MRE was demonstrated in vivo in a canine model, and shear wave propagation was observed in the prostate gland as well as along the rod. These experiments demonstrate the technical feasibility of transurethral MRE in vivo. Further development of this technique is warranted. Magn Reson Med, 2009. © 2009 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||||||||||||||||||||