bluuebunny/crossref_metadata_2025 huggingface dataset:
Non-linear Dynamic Analysis of a Piezoelectrically Actuated Flapping Wing
Authors: Mukherjee Sujoy , Ganguli Ranjan
Published: July 2010

An energy method is used in order to derive the non-linear equations of motion of a smart flapping wing. Flapping wing is actuated from the root by a PZT unimorph in the piezofan configuration. Dynamic characteristics of the wing, having the same size as dragonfly Aeshna Multicolor, are analyzed using numerical simulations. It is shown that flapping angle variations of the smart flapping wing are similar to the actual dragonfly wing for a specific feasible voltage. An unsteady aerodynamic model based on modified strip theory is used to obtain the aerodynamic forces. It is found that the smart wing generates sufficient lift to support its own weight and carry a small payload. It is therefore a potential candidate for flapping wing of micro air vehicles.
“Taking Care of Business”: Alcohol as Currency in Transactional Sexual Relationships Among Players in Cape Town, South Africa
Authors: Townsend Loraine , Ragnarsson Anders , Mathews Catherine , Johnston Lisa Grazina , Ekström Anna Mia , Thorson Anna , Chopra Mickey
Published: July 2010

In this article we examine the dynamics of social relationships in which alcohol use and risky sexual behaviors cooccur. As part of a larger biological and behavioral HIV surveillance survey, 20 men who lived in an urban, informal settlement on the outskirts of Cape Town, South Africa participated in in-depth interviews. Interview transcripts were analyzed according to a latent content analysis. Findings highlight the latent association between alcohol and transactional sex, and enable an in-depth examination of the normative role that alcohol plays in the formation of casual sexual partnerships characterized by exchange. We build on an existing conceptual model that traces the potential pathways by which alcohol use and transactional sex are linked to sexual risk behaviors. The study findings point to the need for multilevel HIV risk-reduction interventions among men to reduce excessive alcohol use, risky sexual behaviors, and underlying perceptions of ideal masculinity.
A Comparative Analysis of Three Online Appraisal Instruments’ Ability to Assess Validity in Qualitative Research
Authors: Hannes Karin , Lockwood Craig , Pearson Alan
Published: July 2010

The concept of validity has been a central component in critical appraisal exercises evaluating the methodological quality of quantitative studies. Reactions by qualitative researchers have been mixed in relation to whether or not validity should be applied to qualitative research and if so, what criteria should be used to distinguish high-quality articles from others. We compared three online critical appraisal instruments’ ability to facilitate an assessment of validity. Many reviewers have used the critical appraisal skills program (CASP) tool to complete their critical appraisal exercise; however, CASP appears to be less sensitive to aspects of validity than the evaluation tool for qualitative studies (ETQS) and the Joanna Briggs Institute (JBI) tool. The ETQS provides detailed instructions on how to interpret criteria; however, it is the JBI tool, with its focus on congruity, that appears to be the most coherent.
What Goes Around Comes Around? Experimental Evidence of the Effect of Rewards on Tax Compliance
Authors: Kastlunger Barbara , Muehlbacher Stephan , Kirchler Erich , Mittone Luigi
Published: July 2010

The current experimental study examined the effect of monetary rewards on tax compliance. Eighty-six participants were randomly assigned to one control and two reward conditions (low vs. high reward). Overall, tax compliance was not affected by the rewards. However, a change in compliance strategies was observed. It seems that rewards provoked an all-or-nothing behavior. Whereas in the reward conditions, participants were either completely honest or evaded all of their income, in the control condition, the amount of evasion varied more strongly. Furthermore, audited compliant taxpayers who are rewarded evaded less in the following period compared with audited compliant taxpayers who experienced no rewards.
High risk of MS in Iranian immigrants in Gothenburg, Sweden
Authors: Ahlgren C. , Lycke J. , Odén A. , Andersen O.
Published: July 2010

Background: In this study we investigated the risk of multiple sclerosis (MS) in migrants who had moved from Iran to Gothenburg, Sweden.

Methods: Patients born in Iran were retrieved from a population-based cohort, which included 534 MS and clinically isolated syndrome patients, born 1959—1990, aged 10—39 years at disease onset in Gothenburg. The expected versus observed number of migrants from Iran was calculated.

Results: The MS risk in the Iranian migrants in Gothenburg was several times higher than in Isfahan, Iran (hazard ratio 3.88, 95% confidence interval 2.17—6.40). Compared with the general population of Gothenburg, the observed number of 17 Iranian patients was higher than the expected value of 9.89 (hazard ratio 1.72, 95% confidence interval 1.00—2.75). Conclusion: Migration from a medium-risk to a high-risk area may increase the MS risk to that of the high-risk area.
Cortical functional reorganization and its relationship with brain structural damage in patients with benign multiple sclerosis
Authors: Giorgio Antonio , Portaccio Emilio , Stromillo Maria Laura , Marino Silvia , Zipoli Valentina , Battaglini Marco , Blandino Anita , Bartolozzi Maria Letizia , Siracusa Gianfranco , Amato Maria Pia , De Stefano Nicola
Published: July 2010

Background: Patients with multiple sclerosis (MS) who have a favourable clinical status several years after disease onset are classified as ‘benign’. In many cases brain tissue damage does not differ between benign MS and the ‘classical’ MS forms.

Objective: To assess whether the favourable clinical course in benign MS could be explained by the presence of an efficient functional cortical reorganization.

Method: Twenty-five right-handed patients with benign MS (defined as having Expanded Disability Status Scale ≤ 3 and disease duration >15 years) underwent functional MRI during a simple motor task (right-hand tapping) to assess movement-associated brain activation. This was compared with that of 10 patients with relapsing—remitting MS and 10 normal controls. Benign MS patients also underwent conventional brain MRI and magnetization transfer imaging, which was compared with an identical examination obtained 1 year before. Quantitative structural magnetic resonance measures were baseline and changes over time in T2-lesion volume, magnetization transfer ratio in T2 lesions and normal-appearing brain and total brain volume.

Results: Movement-related activation was greater in patients with benign MS than in those with relapsing—remitting MS or normal controls, extensively involving bilateral regions of the sensorimotor network as well as basal ganglia, insula and cerebellum. Greater activation correlated with lower T2-lesion magnetization transfer ratio, and with decreasing brain volume and increasing T2 lesion volume.

Conclusions: The results suggest that bilateral brain networks, beyond those normally engaged in motor tasks, are recruited during a simple hand movement in patients with benign MS. This increased activation is probably the expression of an extensive, compensatory and tissue-damage related functional cortical reorganization. This can explain, at least in part, the favourable clinical expression of patients with benign MS.
Analysis of crystallisation and growth behaviour of NbC on solidification process of SUS347H weld metal
Authors: Osuki T. , Yonemura M. , Ogawa K.
Published: July 2010

In order to investigate the solidification cracking susceptibilities of SUS347H weld metal containing high niobium and carbon contents, the crystallisation behaviours of niobium carbide as well as those of and γ phases during welding solidification were numerically analysed to compare with the results from in situ observations of the behaviour of the phase selection for γ, and niobium carbide phases for Fe–18Cr–0·2C–1Nb–(5–12)Ni weld metals. The in situ observation was carried out during tungsten inert gas welding using synchrotron radiation. On the other hand, to evaluate the segregation in liquid phase, which has significant influences on the solidification cracking susceptibility, a numerical model to calculate the segregation in liquid phase considering the crystallisation of γ, and niobium carbide phases was developed. The developed numerical model was verified by the comparison with experimental results from the in situ observation. It was suggested that the solidification cracking susceptibilities of Fe–18Cr–0·2C–1Nb–(5–12)Ni weld metals estimated from the results of the developed numerical model coincided with the experimental results evaluated by transverse Varestraint test.
Effect of magnetic stirring on grain structure refinement Part 2 – Nickel alloy weld overlays
Authors: Lim Y. C. , Yu X. , Cho J. H. , Sosa J. , Farson D. F. , Babu S. S. , McCracken S. , Flesner B.
Published: July 2010

The formation of a columnar grain structure in high chromium nickel based alloy welds can be associated with cracking and poor resolution for ultrasonic non-destructive examination. The objective of this research was to characterise the effects of circular magnetic arc deflection (arc stirring) on grain structure of gas tungsten arc weld overlays made on Inconel 690 substrates with 52M filler wire. Welds and weld overlays were made at various arc stirring frequencies, and microstructures were analysed using optical and electron backscattered diffraction microscopy. Significant refinement of grain size occurred at a stirring frequency of 7 Hz. Ultrasonic non-destructive examination confirmed 100% improvement in signal/noise ratio in weld overlays made with magnetic stirring.
Coating composition, weld parameter and consumable conditioning effects on weld metal composition in shielded metal arc welding
Authors: Coniglio N. , Linton V. , Gamboa E.
Published: July 2010

Pipeline construction has been moving towards the use of higher strength low carbon steels as these become available. In order to achieve the required high strength and toughness to match those of the parent pipe, girth weld metals have to rely mostly on their composition. The aim of the present study was to characterise the influence of the consumable chemistry and moisture content, and the welding parameters on the composition of weld metals produced by E8010 and E9010 shielded metal arc (SMA) cellulosic consumables. The alloying compounds in the consumable coating were isolated using a caustic soda solution, analysed with electron backscattered diffraction and identified as a variety of oxides. Making use of a mechanised SMA welding machine, the effect on weld metal alloying element contents of the welding conditions was evaluated. Smaller welding arc voltages and lower consumable coating moisture content produced weld metals with richer chemistry. The element transfer mechanisms from the consumable coating to the weld metal are also discussed.
Friction stir welding of pure titanium lap joint
Authors: Liu H. , Nakata K. , Yamamoto N. , Liao J.
Published: July 2010

The effects of welding parameters on friction stir welding of pure titanium lap joint were investigated together with the microstructural characteristics of the sound joint. Three kinds of welding defects were found under the condition of tool load control, namely, the groove-like defect, the inner cavity defect and the overheating rough surface and tool penetration defect with increasing heat input. The tool plunge depth control effectively increased the lap width compared with the tool load control, so the sound joints fractured in the base metal were acquired at 250 rev min–1–75 mm min–1 and 200 rev min–1–50 mm min–1. The sound joint consisted of the thermomechanically affected zone, the stir zone, the lap zone and the top layer. The microstructure was fined obviously after welding, and finer grains were observed in the lap zone and top layer.
RuleMonkey: software for stochastic simulation of rule-based models
Authors: Colvin Joshua , Monine Michael I , Gutenkunst Ryan N , Hlavacek William S , Von Hoff Daniel D , Posner Richard G
Published: July 2010

Background

The system-level dynamics of many molecular interactions, particularly protein-protein interactions, can be conveniently represented using reaction rules, which can be specified using model-specification languages, such as the BioNetGen language (BNGL). A set of rules implicitly defines a (bio)chemical reaction network. The reaction network implied by a set of rules is often very large, and as a result, generation of the network implied by rules tends to be computationally expensive. Moreover, the cost of many commonly used methods for simulating network dynamics is a function of network size. Together these factors have limited application of the rule-based modeling approach. Recently, several methods for simulating rule-based models have been developed that avoid the expensive step of network generation. The cost of these "network-free" simulation methods is independent of the number of reactions implied by rules. Software implementing such methods is now needed for the simulation and analysis of rule-based models of biochemical systems.

Results

Here, we present a software tool called RuleMonkey, which implements a network-free method for simulation of rule-based models that is similar to Gillespie's method. The method is suitable for rule-based models that can be encoded in BNGL, including models with rules that have global application conditions, such as rules for intramolecular association reactions. In addition, the method is rejection free, unlike other network-free methods that introduce null events, i.e., steps in the simulation procedure that do not change the state of the reaction system being simulated. We verify that RuleMonkey produces correct simulation results, and we compare its performance against DYNSTOC, another BNGL-compliant tool for network-free simulation of rule-based models. We also compare RuleMonkey against problem-specific codes implementing network-free simulation methods.

Conclusions

RuleMonkey enables the simulation of rule-based models for which the underlying reaction networks are large. It is typically faster than DYNSTOC for benchmark problems that we have examined. RuleMonkey is freely available as a stand-alone application http://public.tgen.org/rulemonkey. It is also available as a simulation engine within GetBonNie, a web-based environment for building, analyzing and sharing rule-based models.
Precision and accuracy of the subjective haptic vertical in the roll plane
Authors: Schuler Jeanine R , Bockisch Christopher J , Straumann Dominik , Tarnutzer Alexander A
Published: July 2010

Background

When roll-tilted, the subjective visual vertical (SVV) deviates up to 40° from earth-vertical and trial-to-trial variability increases with head roll. Imperfections in the central processing of visual information were postulated to explain these roll-angle dependent errors. For experimental conditions devoid of visual input, e.g. adjustments of body posture or of an object along vertical in darkness, significantly smaller errors were noted. Whereas the accuracy of verticality adjustments seems to depend strongly on the paradigm, we hypothesize that the precision, i.e. the inverse of trial-to-trial variability, is less influenced by the experimental setup and mainly reflects properties of the otoliths. Here we measured the subjective haptic vertical (SHV) and compared findings with previously reported SVV data. Twelve healthy right-handed human subjects (handedness assessed based on subjects' verbal report) adjusted a rod with the right hand along perceived earth-vertical during static head roll-tilts (0-360°, steps of 20°).

Results

SHV adjustments showed a tendency for clockwise rod rotations to deviate counter-clockwise and for counter-clockwise rod rotations to deviate clockwise, indicating hysteresis. Clockwise rod rotations resulted in counter-clockwise shifts of perceived earth-vertical up to -11.7° and an average counter-clockwise SHV shift over all roll angles of -3.3° (± 11.0°; ± 1 StdDev). Counter-clockwise rod rotations yielded peak SHV deviations in clockwise direction of 8.9° and an average clockwise SHV shift over all roll angles of 1.8° (± 11.1°). Trial-to-trial variability was minimal in upright position, increased with increasing roll (peaking around 120-140°) and decreased to intermediate values in upside-down orientation. Compared to SVV, SHV variability near upright and upside-down was non-significantly (p > 0.05) larger; both showed an m-shaped pattern of variability as a function of roll position.

Conclusions

The reduction of adjustment errors by eliminating visual input supports the notion that deviations between perceived and actual earth-vertical in roll-tilted positions arise from central processing of visual information. The shared roll-tilt dependent modulation of trial-to-trial variability for both SVV and SHV, on the other hand, indicates that the perception of earth-verticality is dominated by the same sensory signal, i.e. the otolith signal, independent of whether the line/rod setting is under visual or tactile control.
Sex differences in the combined effect of chronic stress with impaired vascular endothelium functioning and the development of early atherosclerosis: The Cardiovascular Risk in Young Finns study
Authors: Chumaeva Nadja , Hintsanen Mirka , Juonala Markus , Raitakari Olli T , Keltikangas-Järvinen Liisa
Published: July 2010

Background

The syndrome of vital exhaustion (VE), characterized by fatigue and irritability, may contribute to an increased risk of atherosclerosis. The aim of the study was to explore sex differences in the interactions of VE with endothelial dysfunction and VE with reduced carotid elasticity, the important contributors to the development of early atherosclerosis, on preclinical atherosclerosis.

Methods

The participants were 1002 women and 719 men aged 24-39 examined in the Cardiovascular Risk in Young Finns study. Vital exhaustion was measured using the Maastricht Questionnaire. Preclinical atherosclerosis was assessed by carotid intima-media thickness (IMT), endothelial function was measured by brachial flow-mediated dilatation (FMD), and arterial elasticity by carotid artery compliance (CAC) using ultrasound techniques.

Results

We found a significant CAC x VE interaction for IMT only for the men. Our results imply that high VE level significantly related to high IMT levels among the men with low CAC, but not among the women with low CAC or among the women or men with high CAC. No significant FMD x VE interactions for IMT for the women or men were found.

Conclusions

High VE may exert an effect on IMT for men with impaired arterial elasticity. The results suggest that high vitally exhausted men with reduced arterial elasticity are at increased risk of atherosclerosis in early life and imply men's decreased stress coping in relation to stressful psychological coronary risk factors.
Water and sanitation infrastructure for health: The impact of foreign aid
Authors: Botting Marianne J , Porbeni Edoye O , Joffres Michel R , Johnston Bradley C , Black Robert E , Mills Edward J
Published: July 2010

Background

The accessibility to improved water and sanitation has been understood as a crucial mechanism to save infants and children from the adverse health outcomes associated with diarrheal disease. This knowledge stimulated the worldwide donor community to develop a specific category of aid aimed at the water and sanitation sector. The actual impact of this assistance on increasing population access to improved water and sanitation and reducing child mortality has not been examined.

Methods

We performed a country-level analysis of the relationship between water and sanitation designated official development assistance (WSS-ODA) per capita, water and sanitation coverage, and infant and child mortality in low-income countries as defined by the World Bank. We focused our inquiry to aid effectiveness since the establishment of the Millennium Development Goals (MDGs).

Results

Access to improved water has consistently improved since 2002. Countries receiving the most WSS-ODA ranged from odds ratios of 4 to 18 times more likely than countries in the lowest tertile of assistance to achieve greater gains in population access to improved water supply. However, while there were modestly increased odds of sanitation access, these were largely non-significant. The countries with greatest gains in sanitation were 8-9 times more likely to have greater reductions in infant and child mortality.

Conclusions

Official development assistance is importantly impacting access to safe water, yet access to improved sanitation remains poor. This highlights the need for decision-makers to be more intentional with allocating WSS-ODA towards sanitation projects.
Some considerations for analyzing biodiversity using integrative metagenomics and gene networks
Authors: Bittner Lucie , Halary Sébastien , Payri Claude , Cruaud Corinne , de Reviers Bruno , Lopez Philippe , Bapteste Eric
Published: July 2010

Background

Improving knowledge of biodiversity will benefit conservation biology, enhance bioremediation studies, and could lead to new medical treatments. However there is no standard approach to estimate and to compare the diversity of different environments, or to study its past, and possibly, future evolution.

Presentation of the hypothesis

We argue that there are two conditions for significant progress in the identification and quantification of biodiversity. First, integrative metagenomic studies - aiming at the simultaneous examination (or even better at the integration) of observations about the elements, functions and evolutionary processes captured by the massive sequencing of multiple markers - should be preferred over DNA barcoding projects and over metagenomic projects based on a single marker. Second, such metagenomic data should be studied with novel inclusive network-based approaches, designed to draw inferences both on the many units and on the many processes present in the environments.

Testing the hypothesis

We reached these conclusions through a comparison of the theoretical foundations of two molecular approaches seeking to assess biodiversity: metagenomics (mostly used on prokaryotes and protists) and DNA barcoding (mostly used on multicellular eukaryotes), and by pragmatic considerations of the issues caused by the 'species problem' in biodiversity studies.

Implications of the hypothesis

Evolutionary gene networks reduce the risk of producing biodiversity estimates with limited explanatory power, biased either by unequal rates of LGT, or difficult to interpret due to (practical) problems caused by type I and type II grey zones. Moreover, these networks would easily accommodate additional (meta)transcriptomic and (meta)proteomic data.

Reviewers

This article was reviewed by Pr. William Martin, Dr. David Williams (nominated by Pr. J Peter Gogarten) & Dr. James McInerney (nominated by Pr. John Logsdon).
A heuristic approach and heretic view on the technical issues and pitfalls in the management of penetrating abdominal injuries
Authors: Yilmaz Tugba H , Ndofor Brown C , Smith Martin D , Degiannis Elias
Published: July 2010

There is a general decline in penetrating abdominal trauma throughout the western world. As a result of that, there is a significant loss of expertise in dealing with this type of injury particularly when the patient presents to theatre with physiological instability. A significant percentage of these patients will not be operated by a trauma surgeon but, by the "occasional trauma surgeon", who is usually trained as a general surgeon. Most general surgeons have a general knowledge of operating penetrating trauma, knowledge originating from their training years and possibly enhanced by reading operative surgery textbooks. Unfortunately, the details included in most of these books are not extensive enough to provide them with enough armamentaria to tackle the difficult case. In this scenario, their operative dexterity and knowledge cannot be compared to that of their trauma surgeon colleagues, something that is taken for granted in the trauma textbooks. Techniques that are considered basic and easy by the trauma surgeons can be unfamiliar and difficult to general surgeons.

Knowing the danger points and pitfalls that will be encountered in penetrating trauma to the abdomen, will help the occasional trauma surgeons to avoid intraoperative errors and improve patient care. This manuscript provides a heuristic approach from surgeons working in a high volume penetrating trauma centers in South African. Some of the statements could be considered heretic by the "accepted" trauma literature. We believe that this heuristic ("rule of thumb" approach, that originating from "try and error" experience) can help surgical trainees or less experienced in penetrating trauma surgeons to improve their surgical decision making and technique, resulting in better patient outcome.
Retrospective agreement and consent to neurocritical care is influenced by functional outcome
Authors: Kiphuth Ines C , Köhrmann Martin , Kuramatsu Joji B , Mauer Christoph , Breuer Lorenz , Schellinger Peter D , Schwab Stefan , Huttner Hagen B
Published: July 2010

Introduction

Only limited data are available on consent and satisfaction of patients receiving specialized neurocritical care. In this study we (i) analyzed the extent of retrospective consent to neurocritical care--given by patients or their relatives--depending on functional outcome one year after hospital stay, and (ii) identified predisposing factors for retrospective agreement to neurocritical care.

Methods

We investigated 704 consecutive patients admitted to a nonsurgical neurocritical care unit over a period of 2 years (2006 through 2007). Demographic and clinical parameters were analyzed, and the patients were grouped according to their diagnosis. Functional outcome, retrospective consent to neurocritical care, and satisfaction with hospital stay was obtained by mailed standardized questionnaires. Logistic regression analyses were calculated to determine independent predictors for consent.

Results

High consent and satisfaction after neurointensive care (91% and 90%, respectively) was observed by those patients who reached an independent life one year after neurointensive care unit (ICU) stay. However, only 19% of surviving patients who were functionally dependent retrospectively agreed to neurocritical care. Unfavorable functional outcome and the diagnosis of stroke were independent predictors for missing retrospective consent.

Conclusions

Retrospective agreement to neurocritical care is influenced by functional outcome. Especially in severely affected stroke patients who cannot communicate their preferences regarding life-sustaining therapy, neurocritical care physicians should balance the expected burdens and benefits of treatment to meet the patients' putative wishes. Efforts should be undertaken to identify predictors for severe disability after neurocritical care.
Unmasking the Janus face of myoglobin in health and disease
Authors: Hendgen-Cotta U. B. , Flögel U. , Kelm M. , Rassaf T.
Published: July 2010

For more than 100 years, myoglobin has been among the most extensively studied proteins. Since the first comprehensive review on myoglobin function as a dioxygen store by Millikan in 1939 and the discovery of its structure 50 years ago, multiple studies have extended our understanding of its occurrence, properties and functions. Beyond the two major roles, the storage and the facilitation of dioxygen diffusion, recent physiological studies have revealed that myoglobin acts as a potent scavenger of nitric oxide (NO•) representing a control system that preserves mitochondrial respiration. In addition, myoglobin may also protect the heart against reactive oxygen species (ROS), and, under hypoxic conditions, deoxygenated myoglobin is able to reduce nitrite to NO• leading to a downregulation of the cardiac energy status and to a decreased heart injury after reoxygenation. Thus, by controlling the NO• bioavailability via scavenging or formation, myoglobin serves as part of a sensitive dioxygen sensory system. In this review, the physiological relevance of these recent findings are delineated for pathological states where NO• and ROS bioavailability are known to be critical determinants for the outcome of the disease, e.g. ischemia/reperfusion injury. Detrimental and beneficial effects of the presence of myoglobin are discussed for various states of tissue oxygen tension within the heart and skeletal muscle. Furthermore, the impact of myoglobin on parasite infection, rhabdomyolysis, hindlimb and liver ischemia, angiogenesis and tumor growth are considered.
Regulation of myoglobin expression
Authors: Kanatous Shane B. , Mammen Pradeep P. A.
Published: July 2010

Myoglobin is a well-characterized, cytoplasmic hemoprotein that is expressed primarily in cardiomyocytes and oxidative skeletal muscle fibers. However, recent studies also suggest low-level myoglobin expression in various non-muscle tissues. Prior studies incorporating molecular, pharmacological, physiological and transgenic technologies have demonstrated that myoglobin is an essential oxygen-storage hemoprotein capable of facilitating oxygen transport and modulating nitric oxide homeostasis within cardiac and skeletal myocytes. Concomitant with these studies, scientific investigations into the transcriptional regulation of myoglobin expression have been undertaken. These studies have indicated that activation of key transcription factors (MEF2, NFAT and Sp1) and co-activators (PGC-1α) by locomotor activity, differential intracellular calcium fluxes and low intracellular oxygen tension collectively regulate myoglobin expression. Future studies focused on tissue-specific transcriptional regulatory pathways and post-translational modifications governing myoglobin expression will need to be undertaken. Finally, further studies investigating the modulation of myoglobin expression under various myopathic processes may identify myoglobin as a novel therapeutic target for the treatment of various cardiac and skeletal myopathies.
Keeping the heart in balance: the functional interactions of myoglobin with nitrogen oxides
Authors: Flögel Ulrich , Fago Angela , Rassaf Tienush
Published: July 2010

Myoglobin (Mb) is an important intracellular oxygen-binding hemoprotein found in the cytoplasm of skeletal and cardiac muscle tissue playing a well-known role in O2 storage and delivery. Within the last decade the knowledge about Mb's function has been considerably extended by the generation of myoglobin-deficient (myo−/−) mice, which for the first time enabled the analysis of Mb's role in physiology without pharmacological intervention. Utilizing the myo−/− mice, it has been demonstrated that beyond its function in O2 supply Mb substantially contributes to nitric oxide (NO) homeostasis in the heart. By a dynamic cycle, in which a decrease in tissue O2 tension drives the conversion of Mb from being a NO scavenger under normoxia to a NO producer during hypoxia, mitochondrial respiration is reversibly adapted to the intracellular O2 tension. Therefore, Mb may act as an important O2 sensor through which NO can regulate muscle energetics and function. As Mb is widespread throughout the fauna, the diverse oxygen-dependent interactions between Mb and nitrogen oxides may not only be of relevance for mammals but also for other vertebrates as evidenced by comparable phenotypes of ‘artificial’ (myo−/− mice) and ‘natural’ Mb knockouts (icefish and amphibians). In conclusion, it seems likely that Mb's multifunctional properties create an environment characterized by a tightly adapted aerobic mitochondrial respiration and low levels of free radicals, and thus serve an essential and beneficial role within the myocardium, which appears to be functionally important over a wide range of species.
Development of a dopaminergic system in sea urchin embryos and larvae
Authors: Katow Hideki , Suyemitsu Takashi , Ooka Shio , Yaguchi Junko , Jin-nai Takayuki , Kuwahara Iku , Katow Tomoko , Yaguchi Shunsuke , Abe Hirokazu
Published: July 2010

The mechanisms that regulate the organized swimming movements of sea urchin blastulae are largely unknown. Using immunohistochemistry, we found that dopamine (DA) and the Hemicentrotus pulcherrimus homolog of the dopamine receptor D1 (Hp-DRD1) were strongly co-localized in 1–2 μm diameter granules (DA/DRD1 granules). Furthermore, these granules were arranged across the entire surface of blastulae as they developed locomotory cilia before hatching, and remained evident until metamorphosis. DA/DRD1 granules were associated with the basal bodies of cilia, and were densely packed in the ciliary band by the eight-arm pluteus stage. The transcription of Hp-DRD1 was detected from the unfertilized egg stage throughout the period of larval development. Treatment with S-(–)-carbidopa, an inhibitor of aromatic-l-amino acid decarboxylase, for 20–24 h (i) from soon after insemination until the 20 h post-fertilization (20 hpf) early gastrula stage and (ii) from the 24 hpf prism larva stage until the 48 hpf pluteus stage, inhibited the formation of DA granules and decreased the swimming activity of blastulae and larvae in a dose-dependent manner. Exogenous DA rescued these deprivations. The formation of DRD1 granules was not affected. However, in 48 hpf plutei, the serotonergic nervous system (5HT-NS) developed normally. Morpholino antisense oligonucleotides directed against Hp-DRD1 inhibited the formation of DRD1 granules and the swimming of larvae, but did not disturb the formation of DA granules. Thus, the formation of DRD1 granules and DA granules occurs chronologically closely but mechanically independently and the swimming of blastulae is regulated by the dopaminergic system. In plutei, the 5HT-NS closely surrounded the ciliary bands, suggesting the functional collaboration with the dopaminergic system in larvae.
Electrolytic lesions within central complex neuropils of the cockroach brain affect negotiation of barriers
Authors: Harley C. M. , Ritzmann R. E.
Published: July 2010

Animals must negotiate obstacles in their path in order to successfully function within natural environments. These actions require transitions from walking to other behaviors, many of which are more involved than simple reflexes. For these behaviors to be successful, insects must evaluate objects in their path and then use that information to change posture or re-direct leg movements. Some of this control may occur within a region of the brain known as the central complex (CC). We used discrete electrolytic lesions to examine the role of certain sub-regions of the CC in various obstacle negotiation behaviors. We found that cockroaches with lesions to the protocerebral bridge (PB) and ellipsoid body (EB) exhibit abnormalities in turning and dealing with shelf-like objects; whereas, individuals with lesions to the fan-shaped body (FB) and lateral accessory lobe (LAL), exhibit abnormalities of those behaviors as well as climbing over blocks and up walls to a horizontal plane. Abnormalities in block climbing include decreased success rate, changes in climbing strategy, and delayed response to the block. Increases in these abnormal behaviors were significant in individuals with lesions to the FB and LAL. Although turning abnormalities are present in individuals with lesions to the LAL, EB and the lateral region of the FB, there are some differences in how these deficits present. For instance, the turning deficits seen in individuals with lateral FB lesions only occurred when turning in the direction opposite to the side of the brain on which the lesion occurred. By contrast, individuals with lesions to the EB and LAL exhibited turning abnormalities in both directions. Lesions in the medial region of the FB did not result in directional turning deficits, but in abnormalities in block climbing.
Tarsal taste neuron activity and proboscis extension reflex in response to sugars and amino acids inHelicoverpa armigera(Hübner)
Authors: Zhang Yun-Feng , van Loon Joop J. A. , Wang Chen-Zhu
Published: July 2010

In adult female Helicoverpa armigera (Hübner), the fifth tarsomere of the prothoracic legs bears 14 gustatory trichoid chemosensilla. These chemosensilla were characterized through electrophysiological experiments by stimulating with sucrose, glucose, fructose, maltose, myo-inositol and 20 common amino acids. In electrophysiological recordings from nine sensilla, responses were obtained to certain compounds tested at 100 mmol l−1, and the response spectra differed from broad to narrow. The four sugars excited the same receptor neuron in sensillum a and sensillum b; sucrose and myo-inositol, sucrose and lysine, myo-inositol and lysine excited two different receptor neurons respectively in sensillum a; fructose and lysine excited two different receptor neurons in sensillum n. Furthermore, the four sugars, myo-inositol and lysine all elicited concentration-dependent electrophysiological responses. These six compounds also induced the proboscis extension reflex (PER) followed by ingestion of the solution when they were applied on the tarsi. Lysine and sucrose caused the strongest electrophysiological responses. However, sucrose had the strongest stimulatory effect on the PER whereas lysine had the weakest. Mixtures of sucrose with the other sugars or with lysine had a similar stimulatory effect on the PER as sucrose alone. The electrophysiological and behavioural responses caused by a range of sucrose concentrations were positively correlated. We conclude that the tarsal gustatory sensilla play an essential role in perceiving sugars available in floral nectar and provide chemosensory information determining feeding behaviour. Tarsal taste-receptor-neuron responses to lysine are implicated in oviposition behaviour.
Myoglobin's old and new clothes: from molecular structure to function in living cells
Authors: Gros Gerolf , Wittenberg Beatrice A. , Jue Thomas
Published: July 2010

Myoglobin, a mobile carrier of oxygen, is without a doubt an important player central to the physiological function of heart and skeletal muscle. Recently, researchers have surmounted technical challenges to measure Mb diffusion in the living cell. Their observations have stimulated a discussion about the relative contribution made by Mb-facilitated diffusion to the total oxygen flux. The calculation of the relative contribution, however, depends upon assumptions, the cell model and cell architecture, cell bioenergetics, oxygen supply and demand. The analysis suggests that important differences can be observed whether steady-state or transient conditions are considered. This article reviews the current evidence underlying the evaluation of the biophysical parameters of myoglobin-facilitated oxygen diffusion in cells, specifically the intracellular concentration of myoglobin, the intracellular diffusion coefficient of myoglobin and the intracellular myoglobin oxygen saturation. The review considers the role of myoglobin in oxygen transport in vertebrate heart and skeletal muscle, in the diving seal during apnea as well as the role of the analogous leghemoglobin of plants. The possible role of myoglobin in intracellular fatty acid transport is addressed. Finally, the recent measurements of myoglobin diffusion inside muscle cells are discussed in terms of their implications for cytoarchitecture and microviscosity in these cells and the identification of intracellular impediments to the diffusion of proteins inside cells. The recent experimental data then help to refine our understanding of Mb function and establish a basis for future investigation.
An experimental—numerical investigation of a metal spinning process
Authors: Beni H R , Beni Y T , Biglari F R
Published: July 2010

Spinning process is an advanced plastic working method, which is frequently used for manufacturing of axisymmetric shapes, especially those that cannot be easily produced with deep drawing method. In this article, a three-dimensional explicit finite-element (FE) analysis is employed to simulate the spinning process of an aluminium circular sheet. To achieve a wide range of strain distribution in different directions, a hemispherical cup has been chosen as the final product shape. In addition, a theoretical shear forming as well as a conventional model has been employed to estimate strain distribution in the spinning hemispherical cup. Experimental tests are carried out using a spinning machine and a hemispherical mandrel. Finally, FE and theoretical calculations are compared with the experimental results. A good agreement has been demonstrated between numerical and experimental results but a relative agreement with theoretical calculations.
Supervisory cascaded controller design: experiment test on a remotely operated vehicle
Authors: Chin C S , Lau M W S , Low E
Published: July 2010

The article proposes a cascaded multi-controllers switching scheme for stabilization and pipeline tracking of a remotely operated vehicle (ROV) under hydrodynamic uncertainties. The ROV is inherently non-linear, highly coupled in motions, and vulnerable to hydrodynamic uncertainties. With controllers that cancel the non-linear dynamics, the system is robust against the pre-defined perturbations on the hydrodynamic added mass and the damping terms. The values used in these perturbed terms were obtained numerically using the WAMITTM software. Compared with other controllers such as proportional-integral and backstepping methods, the pool test showed that the proposed method gives better time domain response and robustness against the perturbed terms.
Effect of Magnitudes and Directions (Mono-Axis and Multi-Axis) of Whole Body-Vibration Exposures and Subjects Postures on the Sketching Performance
Authors: Bhiwapurkar M K , Saran V H , Harsha S P , Goel V K , Berg M
Published: July 2010

Whole-body vibrations in trains are known to affect the performance of sedentary activities such as reading, writing, sketching, working on a computer, etc. The objective of the study was to investigate the extent of disturbance perceived in sketching task by seated subjects in two postures under mono- and multi-axis Gaussian random vibration environment. The study involved 21 healthy male subjects in the age group of 23—32 years. Random vibrations were generated both in mono- and multi-axial directions in the frequency range of 1—10 Hz at 0.5, 1.0, and 1.5 m/s2 rms (root mean square) amplitude. The subjects were required to sketch given geometric figures such as a circle, triangle, rectangle, and square with the help of ball-point pen under given vibration stimuli in two postures (sketch pad on lap and sketch pad on table). The deviation in distortion with respect to the given figure is represented in terms of percentage distortion. The influence of vibrations on the sketching activity was investigated both subjectively and by two specifically designed objective methods, namely, RMS (root mean square methodology) and area methods. The judgements of perceived difficulty to sketch were rated using seven-point semantic judgement scale. The percentage distortion and difficulty in sketching activity increased with an increase in vibration magnitude. Both subjective evaluation and the RMS method revealed that the task was affected more while sketching on the table. The percentage distortion was affected similarly and maximum in all the vibration directions except for the vertical, while sketching difficulty was found to be higher only with longitudinal and multi-axis vibration direction. The subjective evaluation also revealed that there was no effect of the type of entity chosen on the sketching difficulty.
Reduction of Total Knee Replacement Wear with Vitamin E Blended Highly Cross-Linked Ultra-High Molecular Weight Polyethylene
Authors: Vaidya C , Alvarez E , Vinciguerra J , Bruce D A , DesJardins J D
Published: July 2010

Ultra-high molecular weight polyethylene (UHMWPE) is a common bearing component in total knee replacement (TKR) implants, and its susceptibility to wear continues to be the long-term limiting factor in the life of these implants. This study hypothesized that in TKR systems, a highly cross-linked (HXL) UHMWPE blended with vitamin E will result in reduced wear as compared to a direct compression-moulded (DCM) UHMWPE. A wear simulation study was conducted using an asymmetric lateral pivoting ‘3D Knee’ design to compare the two inserts. The highly cross-linked UHMWPE was aged prior to the testing and force-controlled wear testing was carried out for 5 million cycles using a load-controlled ISO-14243 standard at a frequency of 1Hz on both groups. Gravimetric measurements of DCM UHMWPE (4.4±3.0mg/million cycles) and HXL UHMWPE with vitamin E (1.9±1.9mg/ million cycles) showed significant statistical differences (p<0.01) between the wear rates. Wear modes and surface roughness for both groups revealed no significant dissimilarities.
The Influence of the Mechanical Behaviour of the Middle Ear Ligaments: A Finite Element Analysis
Authors: Gentil F , Parente M , Martins P , Garbe C , Jorge R N , Ferreira A , Tavares João Manuel R. S.
Published: July 2010

The interest in computer modelling of biomechanical systems, mainly by using the finite element method (FEM), has been increasing, in particular for analysis of the mechanical behaviour of the human ear. In this work, a finite element model of the middle ear was developed to study the dynamic structural response to harmonic vibrations for distinct sound pressure levels applied on the eardrum. The model includes different ligaments and muscle tendons with elastic and hyperelastic behaviour for these supportive structures. Additionally, the nonlinear behaviour of the ligaments and muscle tendons was investigated, as they are the connection between ossicles by contact formulation. Harmonic responses of the umbo and stapes footplate displacements, between 100 Hz and 100 kHz, were obtained and compared with previously published work. The stress state of ligaments (superior, lateral, and anterior of malleus and superior and posterior of incus) was analysed, with the focus on balance of the supportive structures of the middle ear, as ligaments make the link between the ossicular chain and the walls of the tympanic cavity. The results obtained in this work highlight the importance of using hyperelastic models to simulate the mechanical behaviour for the ligaments and tendons.
Alteration of Scapula Lateral Rotation for Subjects with the Reversed Anatomy Shoulder Replacement and its Influence on Glenohumeral Joint Contact Force
Authors: Masjedi M , Johnson G R
Published: July 2010

It has previously been reported that motion of the scapula varies for subjects with shoulder joint pathologies and is different from that of normal subjects. In this study, an electromagnetic tracking device was used to measure the three-dimensional scapula motion of nine patients with Bayley—Walker (B—W) reverse anatomy joint replacements. The data were then compared to scapula kinematics of 12 normal subjects with no known shoulder pathology. The scapula kinematics for each subject was determined and a regression analysis to find the mean scapula lateral rotation (SLR) for B—W and normal subjects was performed. The regression model which showed the highest change compared to normal was identified and was used in the biomechanical shoulder model to predict the glenohumeral joint contact force.

A high variability of the scapula kinematics was observed, with some subjects having a maximum SLR smaller than that of the normal subjects and some similar to the normal subjects. It was found that scapula may move in such a way to keep the deltoid length at its optimum. The change in the scapula kinematics affected the predicted joint force and its point of application. Hence, knowledge of scapular kinematics is essential for realistic modelling of implanted shoulders.