bluuebunny/crossref_metadata_2025 huggingface dataset:
Decentralized Control of Elastic Limbs in Closed Kinematic Chains
Authors: Schneider Axel , Cruse Holk , Schmitz Josef
Published: August 2006

The generation of movements in closed kinematic chains as opposed to open kinematic chains is a challenging task because all participating joints have to be moved in a highly coordinated manner in order to avoid destructive tensions in the limb. In this paper we present a new decentral joint controller which uses low level interactions between a moving joint and its environment consisting of neighboring joints, the body and the surroundings the agent is placed in. This local joint controller is based on a Local Positive Velocity Feedback (LPVF) mechanism which exploits the elastic properties of the joint. The control strategy is inspired by biological findings in the walking system of stick insects. We will show that a closed kinematic chain consisting of several LPVF controlled joints, though lacking a central controller, can solve tasks which need a high level of inter-joint coordination. As an example, a planar manipulator turning a crank is presented. In a further step, the LPVF algorithm is extended to switched LPVF in order to improve the mechanical power conversion. The extended capabilities are proven in a second experiment in which a 3DoF test leg generates powerful stance movements.
Three-dimensional Translational Dynamics and Stability of Multi-legged Runners
Authors: Seipel Justin , Holmes Philip
Published: August 2006

The spring-loaded inverted pendulum (SLIP) is a simple, passively-elastic two-degree-of-freedom model for legged locomotion that describes the center-of-mass dynamics of many animal species and some legged robots. Conventionally, SLIP models employ a single support leg during stance and, while they can exhibit stable steady gaits when motions are confined to the sagittal plane, three-dimensional gaits are unstable to lateral toppling. In this paper it is shown that multiple stance legs can confer stability. Three SLIP-inspired models are studied: a passive bipedal kangaroo-hopper, an actuated insect model, and passive and actuated versions of a hexapedal robot model. The latter models both employ tripod stance phases. The sources of lateral stability are identified and, for the passive systems, analytical estimates of critical parameters are provided. Throughout, rotations are ignored and only center-of-mass translational dynamics are considered.
Kinematic Model of a New Staircase Climbing Wheelchair and its Experimental Validation
Authors: Morales R. , Feliu V. , González A. , Pintado P.
Published: August 2006

This paper describes the mechanical devices, the movements and the associated kinematic models of a novel wheelchair prototype capable of climbing staircases. The key feature of the mechanical design is the use of two decoupled mechanisms in each axle, one used to negotiate steps, and the other to position the axle with respect to the chair to accommodate the overall slope. This decoupling makes possible many different climbing strategies, the overall mechanism being extraordinarily versatile from a control point of view. Kinematic models have been developed for the different mechanical configurations that appear during all the ascend/descend processes. These models are required to control the actuators of the wheelchair in such a way that its centre of mass is able to follow arbitrary spatial trajectories. This is very important as one has to design very smooth spatial trajectories, keeping a near null inclination of the seat all the time in order to guarantee the comfort of the passenger, usually a handicapped or injured person. A real prototype is presented, and experimental results are reported that show the efficiency of the mechanism and the accuracy of the kinematic models developed.
iSprawl: Design and Tuning for High-speed Autonomous Open-loop Running
Authors: Kim Sangbae , Clark Jonathan E. , Cutkosky Mark R.
Published: August 2006

We describe the design features that underlie the operation of iSprawl, a small (0.3 kg) autonomous, bio-inspired hexapod that runs at 15 body-lengths/second (2.3 m/s). These features include a tuned set of leg compliances for efficient running and a light and flexible power transmission system. This transmission system permits high speed rotary power to be converted to periodic thrusting and distributed to the tips of the rapidly swinging legs. The specific resistance of iSprawl is approximately constant at 1.75 for speeds between 1.25 m/s and 2.5 m/s. Examination of the trajectory of the center of mass and the ground reaction forces for iSprawl show that it achieves a stable, bouncing locomotion similar to that seen in insects and in previous (slower) bio-inspired robots, but with an unusually high stride frequency for its size.
Control Strategy for the Robust Dynamic Walk of a Biped Robot
Authors: Sabourin Christophe , Bruneau Olivier , Buche Gabriel
Published: August 2006

This paper presents the main simulation and experimental results from studies of the robustness of a proposed new control strategy for the under-actuated robot RABBIT. The disturbances studied include modifications of the characteristics of the foot/ground interaction and the application of external forces to the trunk of the robot. These two kinds of disturbance correspond to those most frequently encountered by biped robots during walking in an unknown environment.
Reliable, Built-in, High-Accuracy Force Sensing for Legged Robots
Authors: Montes Hector , Nabulsi Samir , Armada Manuel A.
Published: August 2006

An approach for achieving reliable, built-in, high-accuracy force sensing for legged robots is presented, based on direct exploitation of the properties of a robot’s mechanical structure. The proposed methodology relies on taking account of force-sensing requirements at the robot design stage, with a view to embedding force-sensing capability within the mechanical structure of the robot itself. The test case is ROBOCLIMBER, a bulky, quadruped climbing and walking machine whose weighty legs enable it to carry out heavy-duty drilling operations. The paper shows that, with finite-element analysis of ROBOCLIMBER’s mechanical configuration during the design stage, candidate positions can be selected for the placement of force transducers to measure indirectly the contact forces between the feet and the ground. Force sensors are then installed at the theoretically best positions on the mechanical structure, and several experiments are carried out to calibrate all sensors within their operational range of interest. After calibration, the built-in sensors are subjected to experimental performance evaluation, and the final best sensor option is found. The built-in force-sensing capability thus implemented is subjected to its first test of usability when it is employed to compute the actual centre of gravity of ROBOCLIMBER. The method is shown to be useful for determining variation during a gait (due to the non-negligible weight of the legs). Afterwards the force sensors are shown to be useful for controlling foot-ground interaction, and several illustrative experiments confirm the high sensitivity, reliability and accuracy of the selected approach. Lastly, the built-in sensors are used to measure ground-reaction forces and to compute the zero-moment point for ROBOCLIMBER in real time, both while standing and while executing a dynamically balanced gait.
Controlling the Walking Period of a Pneumatic Muscle Walker
Authors: Takuma Takashi , Hosoda Koh
Published: August 2006

In this paper, we investigate the limit cycle of a biped walker driven by pairs of pneumatic artificial muscles. We show, experimentally, that the period of the limit cycle changes when different control parameters are applied and estimate the relationship between the period and the parameters through trials. A step-by-step feedback controller is proposed to stabilize walking based on the estimated relation. The stability of the feedback controller is demonstrated by showing that the biped can walk down a stair.
Trajectory Planning for the Walking Biped “Lucy”
Authors: Vermeulen J. , Verrelst B. , Vanderborght B. , Lefeber D. , Guillaume P.
Published: August 2006

A real-time joint trajectory generator for planar walking bipeds is proposed. In the near future this trajectory planner will be implemented on the robot “Lucy”, which is actuated by pleated pneumatic artificial muscles. The trajectory planner generates dynamically stable motion patterns by using a set of objective locomotion parameters as its input, and by tuning and exploiting the natural upper body dynamics. The latter can be determined and manipulated by using the angular momentum equation. Basically, trajectories for hip and swing foot motion are generated, which guarantee that the objective locomotion parameters attain certain prescribed values. Additionally, the hip trajectories are slightly modified such that the upper body motion is steered naturally, meaning that it requires practically no actuation. This has the advantage that the upper body actuation hardly influences the position of the Zero Moment Point. The effectiveness of the strategy developed is demonstrated by simulation results. A first simulation is performed under the assumption of perfect tracking by the controllers of the different actuators. This allows one to verify the effectiveness of the trajectory planner and to evaluate the postural stability. A second simulation is performed while taking the control architecture of the real robot into account. In order to have a more realistic simulation the proposed control architecture is evaluated with a full hybrid dynamic simulation model of the biped “Lucy”. This simulator combines the dynamical behaviour of the robot with the thermodynamical effects that take place in the muscle-valves actuation system. The observed hardware limitations of the real robot and expected model errors are taken into account in order to give a realistic qualitative evaluation of the control performance and to test the robustness.
Altered Neuromuscular Control and Ankle Joint Kinematics during Walking in Subjects with Functional Instability of the Ankle Joint
Authors: Delahunt Eamonn , Monaghan Kenneth , Caulfield Brian
Published: August 2006

Background

The ankle joint requires very precise neuromuscular control during the transition from terminal swing to the early stance phase of the gait cycle. Altered ankle joint arthrokinematics and muscular activity have been cited as potential factors that may lead to an inversion sprain during the aforementioned time periods. However, to date, no study has investigated patterns of muscle activity and 3D joint kinematics simultaneously in a group of subjects with functional instability compared with a noninjured control group during these phases of the gait cycle.

Purpose

To compare the patterns of lower limb 3D joint kinematics and electromyographic activity during treadmill walking in a group of subjects with functional instability with those observed in a control group.

Study Design

Controlled laboratory study.

Methods

Three-dimensional angular velocities and displacements of the hip, knee, and ankle joints, as well as surface electromyography of the rectus femoris, peroneus longus, tibialis anterior, and soleus muscles, were recorded simultaneously while subjects walked on a treadmill at a velocity of 4 km/h.

Results

Before heel strike, subjects with functional instability exhibited a decrease in vertical foot-floor clearance (12.62 vs 22.84 mm; P <. 05), as well as exhibiting a more inverted position of the ankle joint before, at, and immediately after heel strike (1.69°, 2.10°, and -0.09° vs -1.43°, -1.43°, and -2.78°, respectively [minus value = eversion]; P <. 05) compared with controls. Subjects with functional instability were also observed to have an increase in peroneus longus integral electromyography during the post–heel strike time period (107.91%[.dotmath]millisecond vs 64.53%[.dotmath]millisecond; P <. 01).

Conclusion

The altered kinematics observed in this study could explain the reason subjects with functional instability experience repeated episodes of ankle inversion injury in situations with only slight or no external provocation. It is hypothesized that the observed increase in peroneus longus activity may be the result of a change in preprogrammed feed-forward motor control.
Immobilization of β-galactosidase on Tamarind Gum and Chitosan Composite Microspheres
Authors: Zhang Ji , Zeng Jiayu , Zhang Shengtang , Wang Yunpu , Wang Yongfeng
Published: August 2006

A new composite microsphere support was prepared and characterized using tamarind gum and chitosan as a source. These new composite microspheres were prepared as well-shaped spheres in range of 230 to 460 m by suspension cross-linking technique. The composite microspheres had better stability in acid and alkaline environments with a swelling volume of 2.34mL/g; the thermal stability of the spheres was better than pure chitosan microspheres. The optimal pH of the immobilized enzyme is pH 8.3 and the optimal temperature is 42°C. The specific activity was 1.6u/g of microspheres and the Michaelis constant was 6.62 10 4. A modified and immobilized enzyme was characterized by means of infrared spectrometry, X-ray photoelectron spectroscopy, and elementary analysis.
Repair of Segmental Defects with Nano-hydroxyapatite/Collagen/PLA Composite Combined with Mesenchymal Stem Cells
Authors: Zhou D. S. , Zhao K. B. , Li Y. , Cui F. Z. , Lee I. S.
Published: August 2006

The aim of the present study was to investigate and compare the capacity of fresh-frozen allogeneic bone, nano-hydroxyapatite/collagen/PLA (nHAC/PLA) scaffold, and nHAC/PLA scaffold loaded with bone marrow mesenchymal stem cells (BMSCs) in inducing bone formation. A 10mm segmental rabbit radial defect was surgically created. The animals were divided into four groups in which the defect was either left untreated, or filled with the abovementioned three grafts. The animals were euthanized at 2, 4, 6, 8, 12, and 18 weeks. Radiographic and histologic analyses were performed on the harvested tissue. We show that nHAC/PLA composite combined with mesenchymal stem cells could enhance and accelerate bone formation in segmental defects of rabbits. nHAC/PLA composite is an ideal bone graft; implanting nHAC/PLA composite combined with mesenchymal stem cells is a potential method for surgical treatment of bone defects.
Synthesis of Pendent Carbonate Ester Groups onto Aliphatic Polycarbonates
Authors: Ben-Shaba Shimon , Domb Abraham J.
Published: August 2006

The reactions of mono- -bromo ethyl carbonate with carboxylic acids, amines, and alcohols were investigated as a model tool for the preparation of novel aliphatic polycarbonate esters. The formation of the corresponding carbonate ester, carbamate, and carbonate derivatives, showed that of the three types of groups chosen to react with -bromo ethyl carbonate, only the carboxylate anions displaced the bromo group to form the corresponding -carbonate ester bond (R—COO—CH(CH3)—O—CO—CH2—CH3). This approach was applied to the synthesis of pendent carbonate ester groups onto aliphatic polycarbonates. The synthetic pathway involved partial bromination of polytrimethylene carbonate (PTMC) to Br-PTMC, which was then reacted with benzoic acid or acetic acid to form the corresponding benzoate and acetate pendent polycarbonate, respectively. The hydrolysis of Br-PTMC and its derivatives as possible biodegradable polymers were investigated. The benzoate group was more susceptible to hydrolysis than the carbonate group hence degradation of the ester catalyzed the hydrolysis of the polymer and improved its biodegradability. The decrease in molecular weight, the release profile for benzoic acid from the grafted polymer and the degradation of Br-PTMC, ACPTMC and PTMC, in terms of the change in pH, were evaluated.
Synthesis of N, N-dimethyl N-ethyl Chitosan as a Carrier for Oral Delivery of Peptide Drugs
Authors: Bayat A. , Sadeghi A. M.M. , Avadi M. R. , Amini M. , Rafiee-Tehrani M. , Shafiee A. , Majlesi R. , Junginger H. E.
Published: August 2006

N, N-dimethyl N-ethyl chitosan (DMEC), a quanternized derivative of chitosan was synthesized based on a modified two-step method via a 22 factorial design to optimize the preparative conditions. The degree of deacetylation of the starting chitosan was determined by FTIR and NMR methods and was 95%. In the first step of the synthesis, mono-ethyl chitosan was prepared by introducing an ethyl group onto the amine group of chitosan via a Schiff base and in the next step methyl iodide was added to produce DMEC which was water soluble in a pH range of 4-8. The DMEC polymers with different degrees of quaternization were obtained and fully characterized using FTIR and 1H-NMR spectroscopic methods. Based on 1H-NMR calculations, the degree of quaternization was 52% by optimizing the two-step process.
Osteoblast Growth on Poly(L-lactic acid)-Negative Ion Powder Composite Films
Authors: Guan Y. T. , Li Y. , Jin Z. H.
Published: August 2006

Composite films made from poly(L-lactic acid) (PLLA) and negative ion powder (NIP, opal powder) were fabricated and the growth of human osteoblasts cultured in vitro on these composite films was assessed. The surface properties of the composite film and the control (100% PLLA) were investigated by contact angle and scanning electron microscopy (SEM). The former indicated that hydrophilicity did not change significantly, whereas the latter indicated that the surface of the composite films was not as smooth as the control, but without holes or caves. After osteoblast cells were seeded on the composite and control films, the cell densities and the morphology on these films were studied by light microscopy and SEM. The differential function of the cells was assessed by testing their alkaline phosphatase (ALP) activity. These results indicate that the addition of powder improved the adhesion between the osteoblasts and the composite films. The improvement came from the negative ions which were given off by the negative ion powder. The mechanism of negative ion was reviewed and a model of the mechanism was developed. This paper provides the first evidence that negative powder (functional material) can be used to fabricate composite films with PLLA for better cell growth.
On Hilbert-Huang Transform Approach for Structural Health Monitoring
Authors: Liu Jianbo , Wang Xinwei , Yuan Shenfang , Li Gang
Published: August 2006

The Hilbert-Huang Transform (HHT) approach is used for signal processing to discover the possible damages existing in a structure. A program is written in Fortran and in Matlab, and then verified by two simple cases with known solutions. The HHT method is then utilized to analyze the actual benchmark data of UBC (University of British Columbia) for the purposes of structural health monitoring. The results demonstrate that HHT method has the capability of: (a) recovering the actual signals’ time-frequency feature; (b) detecting and locating the actual structural damages; (c) detecting the instant of the impact load or of the damage taking place in active structural health monitoring. The method of Empirical Mode Decomposition (EMD) is used to eliminate noise. Results show that EMD method is better than the Wavelet method for the de-noising purpose.
Reenvisioning Gerontological Mental Health Nursing Education: A Commentary
Authors: Butcher Howard Karl
Published: August 2006

Reenvisioning gerontological mental health nursing begins with reinterpreting the meaning of aging and radically transforming the curriculum of the subspecialty. The commentary suggests 11 specific recommendations that expand on Morris and Mentes’s article as a way of reenvisioning and rerooting gerontological mental health nursing. Among the recommendations are renaming the subspecialty “gerontological mental health nursing” as a means to more appropriately reflect the multidisciplinary focus and mental health perspective, placing an equal emphasis on positive aspects of healthy aging, developing a standardized model curriculum, increasing the number of programs offering specialization in gerontological mental health nursing, and reinvigorating continuing education about gerontological mental health care for currently practicing nurses.
Geropsychiatric Nursing: The State of the Science
Authors: Kolanowski Ann , Piven Mary Lynn
Published: August 2006

Increasing longevity, a rising prevalence of psychiatric and medical comorbidities, and dramatic changes in the nature and organization of health care delivery systems have direct implications for the theoretical frameworks and methods that will be needed to shape future geropsychiatric nursing (GPN) science. This article reviews scientific advances and persisting gaps in the knowledge base in 17 discrete areas. Topics encompass specific disorders associated with aging as well as health and quality-of-life considerations that are prominent in the geropsychiatric nursing research literature of the past two decades. The unique interests and capabilities of nurse scientists suggest broad themes for future GPN specialty and interdisciplinary research.
Recommendations for Building Geropsychiatric Nursing Science: A Commentary
Authors: Garand Linda
Published: August 2006

Setting a robust research agenda for geropsychiatric nursing science will encompass both short-term methodologic goals and longer term funding, knowledge development, and dissemination goals. This article identifies immediate needs in the areas of multidisciplinary training, collaborative research models, and selection of research designs appropriate to the types of studies that are the particular province of geropsychiatric nursing scientists, for example, prevention, translational, and effectiveness evaluation of different interventions for aging populations. Longer term goals include nurturance of productive research mentor-mentee relationships within the specialty and development of innovative means for disseminating the yield of nursing research.
Collaborative Learning with Group Interactive Technology
Authors: Jones Catherine , Connolly Michael , Gear Anthony , Read Martin
Published: August 2006

Learning is not just about the acquisition of knowledge but is an activity contributing to change and enrichment of the individual. The focus in this article on the socio-cultural aspects of learning has been influenced by the work of Vygotsky and Leont’ev. Engeström’s triangle was used as a framework to conceptualize the effect of the technology on postgraduate tutorials. It helped in the analysis and understanding of the impact of using group process technology to support the social dimensions of learning. The framework in this article builds on the interrelationships between three themes: individual and collective learning in groups; conversational learning; and the role of technology as an aid to learning. The article discusses explorations into improving debate, increasing participation, and supporting a cooperative learning environment with interactive technology with postgraduate business students.
Agency
Authors: Frank Katherine
Published: August 2006

Many contemporary arguments about agency rely on implicit psychologies or conceptions of human mental functioning even as they attempt to direct attention away from the idea of a freely acting, completely autonomous individual. This article argues that even when the concept of agency is ‘displaced’ or reinterpreted away from the liberal subject, the concept always draws on such a psychological base whether those debts are hidden or declared. Drawing on literature from feminist theory, anthropology, and sociology on women's decisions to undergo elective cosmetic surgery, the first section of the article explores ways that agency has been conceptualized with regard to beauty culture and disciplinary bodily technologies in a US context. The second section of this article takes up women's religious practice in Saba Mahmood's Politics of Piety (2005).
Resistance
Authors: Seymour Susan
Published: August 2006

Since the late 1970s and early 1980s the concept of resistance has become ubiquitous within contemporary cultural anthropology. Theorizing resistance, however, has been problematic from the start and, as I shall argue, a significant part of the problem resides in the anti-psychological position taken by most cultural anthropologists. How can actors protest and resist hegemonic powers if they are not endowed with internalized cultural understandings that motivate such actions? This article briefly reviews some of the resistance literature in cultural anthropology and then focuses upon three ethnographies of resistance, representing three different decades of research and three different theoretical approaches within resistance studies, to demonstrate how different branches of psychological anthropology can enhance our understanding of some of the behaviors that have been labeled ‘resistance’.
The Imaginary
Authors: Strauss Claudia
Published: August 2006

It is common in anthropology now to speak of imaginaries instead of cultural beliefs. This article examines the way Cornelius Castoriadis, Jacques Lacan, Benedict Anderson, and Charles Taylor analyzed this concept. For Castoriadis, the imaginary is a culture's ethos, for Lacan, it is a fantasy, for Anderson and Taylor, it is a shared cognitive schema. Then Marilyn Ivy's application of these theories to Japanese ‘national-cultural imaginaries’ is examined. Finally, a more person-centered analysis is sketched, focusing on US Americans’ explanations of the Columbine school shootings. Current anthropological uses of the imaginary inherit from Castoriadis a tendency toward cultural abstraction, reification, and homogenization. Lacan's, Anderson's, and Taylor's applications of the imaginary are potentially valuable if we use person-centered methods to study real rather than abstract cultural subjects, if we insist on a deeper understanding of the psychological processes involved, and if we respect complexity at both the psychological and social levels.
Subjectivity
Authors: Luhrmann T. M.
Published: August 2006

Anthropologists use the word ‘subjectivity’ loosely, often to refer to the emotional life of the political subject. In this article I argue that a psychological model of emotion helps us to create a clearer anthropological theory of subjectivity, and in the process helps us to make sense of some of the anthropological quarrels about emotion as well. The article concludes with a discussion of the subjectivity of homeless, often psychotic women, which I call ‘social defeat’.
The self
Authors: Quinn Naomi
Published: August 2006

This article advocates an extensive definition of self as the totality of what an organism is physically, biologically, psychologically, socially, and culturally. This definition departs from the narrower definition of self as self-representation – as culturally shaped constructs of the self that one applies to oneself – that is current in cultural anthropology today. The article goes on to elucidate recent neurobiological thinking – specifically, the model of the interpreter developed by Michael Gazzinaga and his colleagues, and Joseph LeDoux's idea of the synaptic self – in support of the extensive definition favored here. Finally, the article compares two divergent analyses by Katherine Ewing of the same case material, showing that the second analysis, that implicitly assumes an extensive definition of the self, provides a more satisfying explanation of the case than the earlier analysis, that is explicitly framed by a definition of the self as self-representation.
Nonpalpable Purpura Within a Setting of Anticoagulant Therapy and Metastatic Carcinoma
Authors: Grenier Nicole , Chen-Tsai Catherine
Published: August 2006

The anticoagulant warfarin can produce a skin necrosis that is clinically indistinguishable from the skin necrosis caused by purpura fulminans associated with disseminated intravascular coagulation (DIC) and heparin-induced thrombocytopenia (HIT). The similar clinical and histologic findings observed in each of these skin necroses create a challenge for diagnosis and eventual treatment. The authors report a patient with significant risk factors for warfarin-induced skin necrosis, DIC, and HIT presenting with painful, purpuric patches beginning on her feet and extending proximally before becoming hemorrhagic bullae on her lower extremities.
Effect of Centella asiatica L (Umbelliferae) on Normal and Dexamethasone-Suppressed Wound Healing in Wistar Albino Rats
Authors: Shetty B. Somashekar , Udupa S. L. , Udupa A. L. , Somayaji S. N.
Published: August 2006

Centella asiatica is a reputed medicinal plant used in the treatment of various skin diseases in the Indian system of medicine. The objective of the study presented in this article was to evaluate the wound-healing potential of the ethanolic extract of the plant in both normal and dexamethasone-suppressed wound healing. The study was done on Wistar albino rats using incision, excision, and dead space wounds models. The extract of C asiatica significantly increased the wound breaking strength in incision wound model compared to controls (P < .001). The extract-treated wounds were found to epithelize faster, and the rate of wound contraction was significantly increased as compared to control wounds (P < .001). Wet and dry granulation tissue weights, granulation tissue breaking strength, and hydroxyproline content in a dead space wound model also increased at statistically significant levels as shown. The extract of the leaves had the effect of attenuating the known effects of dexamethasone healing in all wound models (P < .001, P < .05). The results indicated that the leaf extract promotes wound healing significantly and is able to overcome the wound-healing suppressing action of dexamethasone in a rat model. These observations were supported by histology findings.
Clinical and Microbiological Efficacy of Colistin Therapy in Combination With Rifampin and Imipenem in Multidrug-Resistant Pseudomonas aeruginosa Diabetic Foot Infection With Osteomyelitis
Authors: Tascini Carlo , Menichetti F. , Gemignani G. , Palumbo F. , Leonildi A. , Tedeschi A. , Piaggesi A.
Published: August 2006

The evaluation of the safety and effectiveness of colistin in association with rifampin and imipenem in 1 diabetic patient with severe diabetic foot infection (DFI) due to multidrug-resistant (MDR) Pseudomonas aeruginosa, complicated by osteomyelitis, is presented in this “Case Report”. The patient received colistin after other ineffective antimicrobial treatment when an MDR P aeruginosa strain was isolated by cultural examination, together with a multidisciplinary care approach including surgical debridement and adequate offloading. The efficacy of combination colistin plus rifampin plus imipenem was observed with a checkerboard method and bactericidal activity of the serum. The patient received colistin combination therapy for 6 weeks with cure of the infection and without renal toxicity. These data suggest that colistin, in combination with rifampin and imipenem, is safe and effective, in promoting healing in DFI due to MDR P aeruginosa and suggest the need for controlled clinical studies.
Charcot Neuroarthropathy: An Unusual Case and a Review of the Literature
Authors: Salgami Eleanna V. , Bowling Frank L. , Whitehouse Richard W. , Boulton Andrew J. M.
Published: August 2006

Charcot neuroarthropathy is a devastating consequence of diabetes, requiring early identification and immediate management. A differentiation should be made from osteomyelitis and other pathologies. The authors describe a case of Charcot foot with radiological findings of complete fragmentation of the calcaneum. Further investigation with magnetic resonance and white cell-labeled imaging revealed osteomyelitis. Below-knee amputation was the only therapeutic option in this hindfoot collapse complicated with osteomyelitis.
Role of the Microcirculation in Diabetic Foot Ulceration
Authors: Korzon-Burakowska Anna , Edmonds Michael
Published: August 2006

The concept of microcirculation being implicated in the pathogenesis of diabetic foot disease is being challenged by evidence that fails to confirm it. However, there is evidence of structural changes with capillary and in the basement membrane that do not permit the concept to be denied either. The lack of evidence should not be a reason to argue against surgery in the diabetic foot.
Microvascular Changes in the Diabetic Foot
Authors: Schramm Jordan C. , Dinh Thanh , Veves Aristidis
Published: August 2006

Impairment of the microcirculation of diabetic patients may contribute to secondary complications in the lower extremity, such as foot infections and ulcerations. These microcirculatory changes, which are mainly functional rather than structural, are responsible for the impaired ability of the microvasculature to vasodilate in response to injury. Dysfunction of vascular endothelial cells and vascular smooth muscle cells both contribute to the reduction in vasodilation that is observed in diabetic patients. Nerve-axon reflex related microvascular vasodilation is also impaired in the diabetic population, and there is a growing belief that both the failure of the vessels to dilate and the impairment of the nerve axon reflex are major causes for impaired wound healing in diabetic patients. Further studies are necessary to clarify the precise etiology of endothelial and smooth muscle dysfunction in diabetic patients so that potential therapeutic interventions may be identified.
A Review of Microvascular Measurements in Wound Healing
Authors: Iabichella M. L. , Melillo E. , Mosti G.
Published: August 2006

The microcirculatory evaluation in patients affected by arteriopathic or venous ulcers is usually carried out using laser Doppler flowmetry, transcutaneous oxygen (transcutaneous pressure of oxygen, TcPO2), and carbon dioxide (transcutaneous pressure of carbon dioxide, TcPCO2) measurements and capillaroscopy. These techniques provide significant pathophysiologic and prognostic information. TcPO2 and TcPCO2 diagnose and classify the extent of arterial disease in the leg ulcers caused by arterial disease; the prognostic value is recognized, though doubts about its prognostic potential exist in the case of leg ulcer. Laser Doppler flowmetry is able to identify the first functional impairment in the early stages of the arterial disease and in the complicated venous insufficiency. Capillaroscopy gives us morphological and quantitative parameters of the capillary bed that is damaged in arteriopathic and venous ulcers; nevertheless, it does not provide us with definite prognostic indexes. Combining the 3 methods may contribute to yield objective measures in the clinical management of lower extremity ulcers.
Changing HIV Infection–Related Mortality Rate and Causes of Death Among Persons With HIV Infection Before and After the Introduction of Highly Active Antiretroviral Therapy
Authors: Kumar Alok , Kilaru Krishna R. , Forde Sheila , Roach Timothy C.
Published: August 2006

Objectives: To compare the trends in death rates and the causes of deaths before and after the introduction of highly active antiretroviral therapy. Methods: This is a retrospective study based on chart review of all HIV-related deaths between January 1997 and December 2005. Results: The HIV-specific death rate declined from 34.12 per 100 000 adult population during 1997-1999 to 17.21 per 100 000 adult population during 2003-2005 when highly active anti-retroviral therapy was available. The proportion of all HIV-related deaths among persons newly diagnosed with HIV during the terminal hospitalization decreased from 93% during 1997-1999 to 28% during 2003-2005. Opportunistic infection was at least one of the causes of death in nearly half of all cases. Conclusions: Although, the HIV-specific death rates have declined significantly since the introduction of highly active antiretroviral therapy, HIV infection continues to contribute to the premature deaths among adults, mainly because of the late presentation.
Lessons Learned From a Paying Antiretroviral Therapy Service in the Public Health Sector at Kamuzu Central Hospital, Malawi
Authors: Hosseinipour Mina C. , Neuhann Florian H. , Kanyama Cecelia C. , Namarika Dan C. , Weigel Ralf , Miller William , Phiri Sam J. P.
Published: August 2006

Background:In October 2001, a paying antiretroviral therapy service was introduced at a Central Hospital in Malawi using stavudine 40 mg/lamivudine 150 mg/nevirapine 200 mg (triomune). The objective of this study was to determine characteristics of patients seeking antiretroviral therapy, retention in care, clinical outcomes, and outlines for program improvement. Methods: Retrospectively, all patients seeking anti-retroviral therapy initiation (October 2001 to October 2002; follow-up through April 2003) were evaluated for laboratory results, retention in care, toxicity, and mortality. Hazard ratios for factors associated with dropout were determined. Results: Of 757 patients seeking evaluation, 625 began treatment. Documented mortality rate was 61 of 757. Total dropout rate was 50%. Factors associated with dropout include CD4 count <50 cells/mm3 and Kaposi's sarcoma. Twenty-seven of 625 patients discontinued therapy for toxicity. Conclusions: The paying antiretroviral therapy program showed an unacceptable dropout rate associated with advanced baseline disease. Severe toxicity rate was low. Areas for improved program performance include lower cost, wide and earlier access to antiretroviral therapy, and targeted retention strategies.
Significance of Variation Within HIV, EBV, and KSHV Subtypes
Authors: Stebbing Justin , Powles Tom , Nelson Mark , Bower Mark
Published: August 2006

Since their initial transmission to humans, viruses have diversified extensively through recombination and mutation. The presence of intra- and inter-individual viral diversity influences disease progression, drug resistance, and therapy and presumably explains the conflicting results in many studies, including the failure of peptide-based vaccination strategies. Although HIV is a small RNA virus, coin-fection with large DNA viruses, notably the oncogenicγherpesviridae human herpesvirus-8 and Epstein Barr virus, is common. This coinfection occurs secondary to immunosuppression and shared transmission routes with high-risk predisposing behavior. In addition, all 3 of these viruses can lead to chronic infections, long periods of latency, and reactivation characterized by pain and suffering. The efficient targeting of their genetic diversity represents one of the major challenges in their control, both in prophylactic and therapeutic strategies. An understanding of diversity will help delineate whether population-specific vaccine strategies are necessary.
Prevalence of Kaposi's Sarcoma Among Adult HIV-Seropositive Patients Seen in a Designated HIV Treatment and Care Center in Abuja, Nigeria
Authors: Iregbu K. C. , Elegba O. Y.
Published: August 2006

Background: There is a dearth of information on the prevalence of AIDS-associated Kaposi's sarcoma (AAKS) in Nigeria despite the HIV National seroprevalence of 5% and the occurrence of the disease in people living with HIV/AIDS. Objective: To determine the prevalence of AAKS among HIV-seropositive adults seen in an HIV/AIDS treatment and care center in Abuja, Nigeria. Design: This was a retrospective study of all cases seen over a period of 42 months. Method: Medical records of the 1591 patients comprising 857 males and 734 females were reviewed, and relevant data such as age, sex, CD4 count at diagnosis of AAKS were obtained and analyzed. Results: A prevalence of 0.8% was found, with a male:female ratio of 2:1. Females presented at earlier ages and relatively lower CD4 count than did males. Conclusion: Easy access to antiretroviral medications and a well-targeted education and awareness campaign will help reduce the incidence and prevalence of the disease. The inability to perform histologic examinations on all suspected cases calls for a well-designed prospective study to determine the actual prevalence of Kaposi's sarcoma in HIV-seropositive patients in Nigeria.
A Professional Learning Community at Work
Authors: Hackmann Donald G. , Walker Janice M. , Wanat Carolyn L.
Published: August 2006

Due to the state’s recent adoption of the Interstate School Leaders Licensure Consortium standards, all leadership preparation programs are required to develop a standards-based curriculum emphasizing the principal’s responsibility to lead schools committed to student success. The Midwest State University (MSU) educational leadership faculty, which has undergone significant turnover, is faced with the dual challenge of developing collaborative working relationships among department members while revising their principal preparation program to meet the state’s upgraded requirements. The MSU faculty used this opportunity to develop a professional learning community through a series of retreats and sustained work activities throughout the academic year as they reformed their principal preparation program.
Turbulence, Turmoil, and Trauma
Authors: Lugg Catherine A.
Published: August 2006

This case presents an educational leader attempting to institute cultural change in a university department that has long been marked by turbulence, turmoil, and trauma. The case examines the well-intentioned efforts of the newly appointed department chair, John Nitsky, in his quest to “reculture” the department.
Optimizing COF, Blocking Force, and Printability of Low Density Polyethylene
Authors: Zahedi Ali R. , Ranji A. , Asiaban S.
Published: August 2006

Most polyolefins exhibit a degree of ‘tackiness’ which cannot readily be processed into packaging films without the presence of special additives. Many current polyolefin film formulations contain fatty acid amides (slip agents) and inorganic materials (antiblock agents) to reduce friction resistance and lower film-to-film adhesion, respectively. This study demonstrates that it is possible to optimize slip and antiblock additives in order to obtain desirable friction and blocking force while maintaining a good printability.
Experimental Investigation of Film Formation: Film Casting
Authors: Aniunoh Kenneth K. , Harrisony Graham M.
Published: August 2006

In film casting, a polymer melt is extruded through a flat die before rapid cooling on a chill roll. In this article, the effects of process conditions on polypropylene (PP) film formation in the air gap have been studied. Process variables investigated include draw ratio (DR) and die temperature. The temperature, width, and velocity profiles in the air gap are measured. Centerline strain rates initially increase with distance from the die, and the trends observed depend on the DR. The velocity decreases from the centerline value as the film approaches the film edges. The film temperature shows a local minimum along the centerline.
Studies Toward Producing Eco-Friendly Plastics
Authors: Khare Anagha , Deshmukh Sanjay
Published: August 2006

Plastics have become a major factor in modern life and the massive volume of plastics in use has a significant effect on the environment. Major efforts are underway to reduce the impact of plastics on the environment and to make them more eco-friendly. Such efforts include the use of bio-materials instead of nonrenewable resources such as petroleum for manufacturing polymers. There are also studies which are aimed at reducing the impact of discarded plastic products on air and water supplies, as well as on flora, fauna, and landfills.
Simulating Stress Relaxation Effects for Sequential Biaxial Stretching of Optical Films in a Tenter
Authors: Sato Takashi , Sugihara Genki , Arakawa Kouhei , Yamada Toshiro
Published: August 2006

Control of the sequential orientation (tenter) process for optical films is one of the most important factors in developing the retardation films which are needed for large sized liquid crystal displays (LCD). Analysis to predict the thickness distributions and bowing phenomenon during the tentering process is performed by finite element analysis (FEA).

In addition, this study provides a new calculation method to predict the optical axes of stretched films from elastoplastic FEA results. The optical axes have two components. One is a stress-dependent term and the other is a strain-dependent term. To predict the molecular orientation, time-dependent effects are concerned with both. Moreover, polymer relaxation processes are examined. The FEA and optical property calculation are independent in the methods. This method enables one to easily calculate optical axes of films during the tentering process without a change of the conventional FEA calculation process.
P-selectin glycoprotein ligand 1 and β2-integrins cooperate in the adhesion of leukocytes to von Willebrand factor
Authors: Pendu Ronan , Terraube Virginie , Christophe Olivier D. , Gahmberg Carl G. , de Groot Philip G. , Lenting Peter J. , Denis Cecile V.
Published: August 2006

Von Willebrand factor (VWF) is an essential component of hemostasis. However, animal studies using VWF-deficient mice suggest that VWF may also contribute to inflammation. In the present study, we demonstrate that VWF was able to interact with polymorphonuclear leukocytes (PMNs) and monocytes under static and flow conditions. Adhesion under flow was dominated by short-lasting contact with resting PMNs, whereas adhesion of phorbol-12-myristate-13-acetate (PMA)–stimulated PMNs was characterized by firm adhesion. Transient binding of PMNs to VWF appeared to be mediated by P-selectin glycoprotein ligand-1 (PSGL-1). Moreover, recombinant PSGL-1 protein and cell surface–expressed PSGL-1 directly interacted with VWF. As for stable adhesion by PMA-stimulated PMNs, we observed that static adhesion and adhesion under flow were strongly inhibited (greater than 75%) by neutrophil-inhibitory factor, an inhibitor of β2-integrin function. In addition, the isolated I-domain of αMβ2 bound to VWF, and cell lines expressing αLβ2 or αXβ2 adhered efficiently to VWF. Taken together, our data showed that VWF can function as an adhesive surface for various leukocyte subsets (monocytes, PMNs). Analogous to VWF-platelet interaction, VWF provided binding sites for leukocyte receptors involved in rolling (PSGL-1) and stable (β2-integrins) adhesion. VWF is unique in its intrinsic capacity to combine the rolling and the stable adhesion step in the interaction with leukocytes.
Primitive erythropoiesis from mesodermal precursors expressing VE-cadherin, PECAM-1, Tie2, endoglin, and CD34 in the mouse embryo
Authors: Ema Masatsugu , Yokomizo Tomomasa , Wakamatsu Asami , Terunuma Tsumoru , Yamamoto Masayuki , Takahashi Satoru
Published: August 2006

Vascular endothelial (VE) cadherin, PECAM-1 (platelet endothelial cell adhesion molecule-1, CD31), Tie2, CD34, and endoglin are established markers for adult and embryonic endothelial cells (ECs). Here, we report that the expression of these EC markers is initiated in the extraembryonic region at the late-streak stage (nominal stage E6.75). Immunohistochemical analysis shows that EC marker–positive cells arise in a subset of Flk1 (VEGF-R2) mesodermal cells. In contrast, GATA1, a marker for primitive erythropoietic progenitors, is expressed in a more restricted subset of Flk1-positive cells. Using flow cytometry, we observed that the GATA1-positive cell population existed as a subset of the EC marker–positive cell. Consistent with this notion, we showed with the primitive hematopoietic colony assay that primitive erythropoietic progenitors are enriched in PECAM-1– and Tie2-positive cells. These results suggest that primitive hematopoietic cells arise from EC marker–positive cells. Thus, VE-cadherin, PECAM-1, CD34, endoglin, and Tie2 are expressed not only in adult and embryonic ECs but in extraembryonic Flk1-positive cells during gastrulation. The latter cell population includes progenitors that give rise to primitive hematopoietic cells, suggesting that primitive and definitive hematopoietic cells in the mouse embryo arise from EC marker–positive cells.