Analyzing static three-dimensional elastic domains with a new infinite boundary element formulation

A new two-dimensionally mapped infinite boundary element (IBE) is presented. The formulation is based on a triangular boundary element (BE) with linear shape functions instead of the quadrilateral IBEs usually found in the literature. The infinite solids analyzed are assumed to be three-dimensional, linear-elastic and isotropic, and Kelvin fundamental solutions are employed. One advantage of the proposed formulation over quadratic or higher order elements is that no additional degrees of freedom are added to the original BE mesh by the presence of the IBEs. Thus, the IBEs allow the mesh to be reduced without compromising the accuracy of the result. Two examples are presented, in which the numerical results show good agreement with authors using quadrilateral IBEs and analytical solutions. (C) 2010 Elsevier Ltd. All rights reserved.

A comparison of dynamic and quasi-static results for the flow towards a well

The present analysis takes into account the acceleration term in the differential equation of motion to obtain exact dynamic solutions concerning the groundwater flow towards a well in a confined aquifer. The results show that the error contained in the traditional quasi-static solution is very small in typical situations.

DEVELOPMENT OF STATIC MIXERS FOR MISCIBLE FLUIDS IN LAMINAR FLOW WITH THE USE OF COMPUTATIONAL FLUID DYNAMICS (CFD)

Static mixers with improved performance were developed from CFD simulations in a stepwise approach. The relevant geometric features of simple mixer designs and the corresponding mixing mechanisms-laminar shear, elongational flow, and distributive mixing-were identified first. This information was used to formulate guidelines for the development of new geometries. The solid elements of the static mixer should: (a) provide restrictions to the flow; (b) deflect the flow; (c) be sequentially rotated around the flow direction to provide symmetry; (d) extend from the center of the pipe to the vicinity of the walls to avoid short-circuiting; and (e) distribute and remix the flow. Based on these guidelines, two improved mixer designs were developed: the DS A-I mixer has a good mixing efficiency and an acceptable pressure drop; the Fins 35 degrees mixer is more efficient and compact, but requires a larger pressure drop. Their performance indicates that their use is possible on industrial applications.

Low-frequency noise and static analysis of the impact of the TiN metal gate thicknesses on n- and p-channel MuGFETs

The impact of the titanium nitride (TIN) gate electrode thickness has been investigated in n and p channel SOI multiple gate field effect transistors (MuGFETs) through low frequency noise charge pumping and static measurements as well as capacitance-voltage curves The results suggest that a thicker TIN metal gate electrode gives rise to a higher EOT a lower mobility and a higher interface trap density The devices have also been studied for different back gate biases where the GIFBE onset occurs at lower front-gate voltage for thinner TIN metal gate thickness and at higher V(GF) In addition it is demonstrated that post deposition nitridation of the MOCVD HfSiO gate dielectric exhibits an unexpected trend with TIN gate electrode thickness where a continuous variation of EOT and an increase on the degradation of the interface quality are observed (C) 2010 Elsevier Ltd All rights reserved

Reachability of the synchronous state in a mutually connected PLL network

Second-order phase locked loops (PLLs) are devices that are able to provide synchronization between the nodes in a network even under severe quality restrictions in the signal propagation. Consequently, they are widely used in telecommunication and control. Conventional master-slave (M-S) clock-distribution systems are being, replaced by mutually connected (MC) ones due to their good potential to be used in new types of application such as wireless sensor networks, distributed computation and communication systems. Here, by using an analytical reasoning, a nonlinear algebraic system of equations is proposed to establish the existence conditions for the synchronous state in an MC PLL network. Numerical experiments confirm the analytical results and provide ideas about how the network parameters affect the reachability of the synchronous state. The phase-difference oscillation amplitudes are related to the node parameters helping to design PLL neural networks. Furthermore, estimation of the acquisition time depending on the node parameters allows the performance evaluation of time distribution systems and neural networks based on phase-locked techniques. (c) 2008 Elsevier GmbH. All rights reserved.

Some remarks on static-feedback linearization for time-varying systems

This work summarizes some results about static state feedback linearization for time-varying systems. Three different necessary and sufficient conditions are stated in this paper. The first condition is the one by [Sluis, W. M. (1993). A necessary condition for dynamic feedback linearization. Systems & Control Letters, 21, 277-283]. The second and the third are the generalizations of known results due respectively to [Aranda-Bricaire, E., Moog, C. H., Pomet, J. B. (1995). A linear algebraic framework for dynamic feedback linearization. IEEE Transactions on Automatic Control, 40, 127-132] and to [Jakubczyk, B., Respondek, W. (1980). On linearization of control systems. Bulletin del` Academie Polonaise des Sciences. Serie des Sciences Mathematiques, 28, 517-522]. The proofs of the second and third conditions are established by showing the equivalence between these three conditions. The results are re-stated in the infinite dimensional geometric approach of [Fliess, M., Levine J., Martin, P., Rouchon, P. (1999). A Lie-Backlund approach to equivalence and flatness of nonlinear systems. IEEE Transactions on Automatic Control, 44(5), 922-937]. (C) 2008 Elsevier Ltd. All rights reserved.

A synchronous multimedia annotation system for secure collaboratories

In this paper, we describe the Vannotea system - an application designed to enable collaborating groups to discuss and annotate collections of high quality images, video, audio or 3D objects. The system has been designed specifically to capture and share scholarly discourse and annotations about multimedia research data by teams of trusted colleagues within a research or academic environment. As such, it provides: authenticated access to a web browser search interface for discovering and retrieving media objects; a media replay window that can incorporate a variety of embedded plug-ins to render different scientific media formats; an annotation authoring, editing, searching and browsing tool; and session logging and replay capabilities. Annotations are personal remarks, interpretations, questions or references that can be attached to whole files, segments or regions. Vannotea enables annotations to be attached either synchronously (using jabber message passing and audio/video conferencing) or asynchronously and stand-alone. The annotations are stored on an Annotea server, extended for multimedia content. Their access, retrieval and re-use is controlled via Shibboleth identity management and XACML access policies.

Synchronous oogenesis during the semilunar spawning cycle of the tropical abalone Haliotis asinina

On the southern Great Barrier Reef, Haliotis asinina (Vetigastropoda: Pleurotomarioidea) synchronously spawn every 2 wk in a predictable fashion. allowing detailed analysis of reproduction, gametogenesis, and gonad development. Histological examination of the ovaries of members of the Heron Reef population during this semilunar cycle reveals that oogenesis is also synchronous and predictable, and requires more than two spawning cycles (i.e. >28 days) to complete. Shortly after a spawning event the ovary comprises two cohorts of primary oocytes, one of which will be released at the next spawning event, and clusters of oogonia. At this time there is a rapid proliferation and expansion of trabeculae, germinal epithelial, and oogonia, and a dramatic increase in the size of the vitellogenic oocytes to be: spawned at the next spawning event. Within 4 days these oocytes have filled the ovary. On the day of the next spawning a lumen forms in the ovary as a result of localized degradation of trabeculae. The large primary oocytes dissociate from the receding trabeculae. initiate maturation, and accumulate in the lumen; these oocytes become embedded in a jelly coat layer. The next cohort of oocytes remain attached to the trabeculae. The jelly coat appears to be completely dissolved within 30 min of spawning. Comparison of the oogenesis and ovary development in II. asinina with other abalone species indicates that these processes are very similar in tropical and temperate abalone. This suggests that insights into the regulation of reproduction and spawning in H. asinina are likely to be applicable to other haliotids.

STATIC IMAGES WITH DIFFERENT INDUCED INTENSITIES OF HUMAN BODY MOVEMENTS AFFECT SUBJECTIVE TIME

Modulation of subjective time was examined using static images eliciting perceptions of different intensities of body movement. Undergraduate students were exposed to photographs of dancer sculptures in different dance positions for 36 sec. and asked to estimate the exposure duration. Lower movement intensities were related to shorter estimated durations. Mean durations for images of unmoving dancers were underestimated and for dancers taking a ballet step were overestimated. Temporal estimations were also related to the order of presentation of the stimuli, which suggested that subjective time estimations were influenced by the experimental context. Subjective time is related not only to the visual perception of moving images, but also of elicited perceptions of movement in static images, suggesting an embodiment effect on subjective time estimation.

Synchronous adenocarcinoma of the major and minor duodenal papilla

A 50-year-old woman presented with pancreatitis, fluctuant jaundice, weight loss, and abdominal pain. Contrast-enhanced computed tomography and abdominal ultrasound showed slight dilatation of the biliary tree and gallbladder without calculi. Endoscopy demonstrated a tumor protruding from the papilla of Vater. First endoscopically biopsy diagnosed no tumor, and a second biopsy diagnosed as papillary adenocarcinoma. The patient underwent duodenopancreatectomy. The specimen was fixed in formalin (10%). The tissue was processed routinely, and paraffin sections were stained with hematoxylin-eosin and periodic acid Schiff. Gross examination showed two tumors seen as prolapsed nodules growing isolated from the minor and major duodenal papillae measuring 1.5 and 1.0 cm, respectively, both covered by duodenal mucosa and the histologic study of both lesions demonstrated a moderately differentiated tubular adenocarcinoma, which invaded duodenal wall. After surgery, she is alive 24 months without evidence of recurrence.

Rapid computation of static fields produced by thick circular solenoids

A straightforward method is proposed for computing the magnetic field produced by a circular coil that contains a large number of turns wound onto a solenoid of rectangular cross section. The coil is thus approximated by a circular ring containing a continuous constant current density, which is very close to the real situation when sire of rectangular cross section is used. All that is required is to evaluate two functions, which are defined as integrals of periodic quantities; this is done accurately and efficiently using trapezoidal-rule quadrature. The solution can be obtained so rapidly that this procedure is ideally suited for use in stochastic optimization, An example is given, in which this approach is combined with a simulated annealing routine to optimize shielded profile coils for NMR.

Synchronous collision malignant melanoma and adenocarcinoma of the rectum

Collision tumors consist of two independent but coexisting tumors. This uncommon situation might be easily mistaken for a composite tumor where one histogenetic event originates from two apparently distinct neoplasms. Colorectal collisions are particularly unusual; here, we report the exceedingly rare case of a 61-year-old man with malignant melanoma and adenocarcinoma colliding in the rectum. Collision tumors have an idiopathic pathophysiology and in fact ""accidental meeting"" is accepted by many authors. This article discusses the concepts about cancer development, which are overlooked by this hypothesis, another theory to explain that this rare occurrence involves microenvironment changes.

Static Knee Alignment Measurements among Caucasians and African Americans: The Johnston County Osteoarthritis Project

Objective. To determine if knee alignment measures differ between African Americans and Caucasians without radiographic knee osteoarthritis (rOA). Methods. A single knee was randomly selected from 175 participants in the Johnston County Osteoarthritis Project without rOA in either knee. Anatomic axis, condylar, tibia] plateau, and condylar plateau angles were measured by I radiologist; means were compared and adjusted for age and body mass index (BMI). Results. There were no significant differences in knee alignment measurements between Caucasians and African Americans among men or women. Conclusion. Observed differences in knee rOA occurrence between African Americans and Caucasians are not explained by differences in static knee alignment. (First Release July 15 2009; J Rheumatol 2009;36:1987-90; doi: 10.3899/jrheum.081294)

Influence of ventilatory settings on static and functional haemodynamic parameters during experimental hypovolaemia

Background and objective The influence of ventilatory settings on static and functional haemodynamic parameters during mechanical ventilation is not completely known. The purpose of this study was to evaluate the effect of positive end-expiratory pressure, tidal volume and inspiratory to expiratory time ratio variations on haemodynamic parameters during haemorrhage and after transfusion of shed blood. Methods Ten anaesthetized pigs were instrumented and mechanically ventilated with a tidal volume of 8 ml kg(-1), a positive end-expiratory pressure of 5 cmH(2)O and an inspiratory to expiratory ratio of 1 : 2. Then, they were submitted in a random order to different ventilatory settings (tidal volume 16 ml kg(-1), positive end-expiratory pressure 15 cmH(2)O or inspiratory to expiratory time ratio 2: 1). Functional and static haemodynamic parameters (central venous pressure, pulmonary artery occlusion pressure, right ventricular end-diastolic volume and pulse pressure variation) were evaluated at baseline, during hypovolaemia (withdrawal of 20% of estimated blood volume) and after an infusion of withdrawn blood (posttransfusion). Results During baseline, a positive end-expiratory pressure of 15cmH(2)O significantly increased pulmonary artery occlusion pressure from 14.6 +/- 1.6 mmHg to 17.4 +/- 1.7 mmHg (P<0.001) and pulse pressure variation from 15.8 +/- 8.5% to 25.3 +/- 9.5% (P<0.001). High tidal volume increased pulse pressure variation from 15.8 8.5% to 31.6 +/- 10.4% (P<0.001), and an inspiratory to expiratory time ratio of 2: 1 significantly increased only central venous pressure. During hypovolaemia, high positive end-expiratory pressure influenced all studied variables, and high tidal volume strongly increased pulse pressure variation (40.5 +/- 12.4% pre vs. 84.2 +/- 19.1 % post, P<0.001). The inversion of the inspiratory to expiratory time ratio only slightly increased filling pressures during hypovolaemia, without without affecting pulse pressure variation or right ventricle end-diastolic volume. Conclusion We concluded that pulse pressure variation measurement is influenced by cyclic variations in intrathoracic pressure, such as those caused by augmentations in tidal volume. The increase in mean airway pressure caused by positive end-expiratory pressure affects cardiac filling pressures and also pulse pressure variation, although to a lesser extent. Inversion of the inspiratory to expiratory time ratio does not induce significant changes in static and functional haemodynamic parameters. Eur J Anaesthesiol 26:66-72 (c) 2009 European Society of Anaesthesiology.

The association between osteoporosis and static balance in elderly women

This study aimed at answering the question: do people with high bone loss have greater postural instability? Groups were separated into group 1: women with normal bone mineral density, group 2: women with osteopenia, and group 3: women with osteoporosis. The balance was evaluated in four upright postural situations. Osteoporosis group had greater oscillation in the anteroposterior displacement in all situations compared to control group and the greatest mediolateral displacement in all situations compared to other groups. It is not known whether the presence of osteoporosis can be considered a factor aggravating the postural control. This study aimed at answering the question: do people with high bone loss have greater postural instability? This study was divided into three groups: group 1 (n = 20) consisting of women with normal bone mineral density, group 2 (n = 20) women with osteopenia, and group 3 (n = 20) women with osteoporosis. All the participants were submitted to evaluation of the balance using the Polhemus system in four upright postural situations. Osteoporosis group had greater oscillation in the anteroposterior displacement in all situations compared to control group. The osteoporosis group also showed the greatest mediolateral displacement in all situations compared to other groups. The results suggest that osteoporotic women had the worst balance, possibly due to the more pronounced body changes compared to non-osteoporotic women.