bluuebunny/crossref_metadata_2025 huggingface dataset:
Expression Profile of Nerve Growth Factor after Muscle Incision in the Rat
Authors: Wu Chaoran , Erickson Mark A. , Xu Jun , Wild Kenneth D. , Brennan Timothy J.
Published: December 2008

Background

Previous studies have demonstrated that nerve growth factor (NGF) is an important mediator of pathologic pain. Many studies have focused on cutaneous mechanisms for NGF-induced hyperalgesia; few have examined its contribution in deeper tissues like muscle. This study examined pain behaviors and the expression of NGF in incised hind paw flexor digitorum brevis muscle.

Methods

Adult Sprague-Dawley rats were pretreated with anti-NGF peptibody and underwent skin or skin plus deep fascia and muscle incision. Guarding pain behaviors were measured. Muscle NGF messenger RNA (mRNA) was measured by reverse-transcriptase polymerase chain reaction. Changes in NGF protein expression were measured using Western blot, enzyme-linked immunosorbent assay, and immunohistochemistry. In situ hybridization for NGF mRNA was also performed.

Results

Pretreatment with anti-NGF peptibody (100 mg/kg) decreased the guarding behavior caused by deep fascia and muscle incision. Muscle NGF mRNA increased abruptly 2 h after incision and was the same as control by postoperative day 1. NGF protein increased from 4 h after incision and was sustained for several days. NGF was localized in many calcitonin gene-related peptide-positive axons, few N52-positive axons, but not isolectin B4-positive axons in incised muscle. The sources of NGF mRNA included keratinocytes in epidermis and fibroblasts in deeper tissues.

Conclusion

Fibroblasts adjacent to the injury are sources of NGF in incised muscle. NGF is upregulated by incision of muscle and contributes to guarding pain behavior.
Liability Associated with Obstetric Anesthesia
Authors: Davies Joanna M. , Posner Karen L. , Lee Lorri A. , Cheney Frederick W. , Domino Karen B.
Published: December 2008

Background

Obstetrics carries high medical liability risk. Maternal death and newborn death/brain damage were the most common complications in obstetric anesthesia malpractice claims before 1990. As the liability profile may have changed over the past two decades, the authors reviewed recent obstetric claims in the American Society of Anesthesiologists Closed Claims database.

Methods

Obstetric anesthesia claims for injuries from 1990 to 2003 (1990 or later claims; n = 426) were compared to obstetric claims for injuries before 1990 (n = 190). Chi-square and z tests compared categorical variables; payment amounts were compared using the Kolmogorov-Smirnov test.

Results

Compared to pre-1990 obstetric claims, the proportion of maternal death (P = 0.002) and newborn death/brain damage (P = 0.048) decreased, whereas maternal nerve injury (P < 0.001) and maternal back pain (P = 0.012) increased in 1990 or later claims. In 1990 or later claims, payment was made on behalf of the anesthesiologist in only 21% of newborn death/brain damage claims compared to 60% of maternal death/brain damage claims (P < 0.001). These payments in both groups were associated with an anesthesia contribution to the injury (P < 0.001) and substandard anesthesia care (P < 0.001). Anesthesia-related newborn death/brain damage claims had an increased proportion of delays in anesthetic care (P = 0.001) and poor communication (P = 0.007) compared to claims unrelated to anesthesia.

Conclusion

Newborn death/brain damage has decreased, yet it remains a leading cause of obstetric anesthesia malpractice claims over time. Potentially preventable anesthetic causes of newborn injury included delays in anesthesia care and poor communication between the obstetrician and anesthesiologist.
CU-2010—A Novel Small Molecule Protease Inhibitor with Antifibrinolytic and Anticoagulant Properties
Authors: Dietrich Wulf , Nicklisch Silke , Koster Andreas , Spannagl Michael , Giersiefen Helmut , van de Locht Andreas
Published: December 2008

Background

In cardiac surgery, the contact of blood with the artificial surfaces of the cardiopulmonary bypass results in activation of coagulation, fibrinolysis, and platelets, which is recognized as reason for increased bleeding tendency. Antifibrinolytics like tranexamic acid or the broad-spectrum protease inhibitor aprotinin attenuate this response. The marketing of aprotinin has been suspended after a recent clinical trial suggested increased risks associated with aprotinin. Moreover, aprotinin is a protein of animal origin and has antigenic properties. As a result, alternative antifibrinolytic compounds are desirable.

Methods

This in vitro study compared the antifibrinolytic efficacy of the synthetic small molecule CU-2010 with aprotinin and tranexamic acid. Antifibrinolytic activity in plasma and whole blood of ten healthy volunteers was examined with a turbidometric method and with tissue factor-activated thromboelastometry (ROTEM; Pentapharm, Munich, Germany). In addition, anticoagulant effects were assessed through measurement of plasma and whole blood clotting times and thrombin generation.

Results

With its high affinity for plasmin (Ki, 2 nM), CU-2010 inhibited fibrinolysis comparable to aprotinin (Ki, 4 nM) and was ten times more potent than tranexamic acid. CU-2010 also inhibited plasma kallikrein (Ki < 1 nM) and factors Xa (Ki, 45 nM) and XIa (Ki, 18nM), which was reflected in prolongation of coagulation times and an attenuation of thrombin generation.

Conclusion

These findings suggest that CU-2010 has similar antifibrinolytic potency compared to aprotinin, is more potent than tranexamic acid, and possesses some anticoagulant effects.
Bacillus subtilis MinC destabilizes FtsZ-rings at new cell poles and contributes to the timing of cell division
Authors: Gregory James A. , Becker Eric C. , Pogliano Kit
Published: December 2008

Division site selection in rod-shaped bacteria depends on nucleoid occlusion, which prevents division over the chromosome and MinCD, which prevent division at the poles. MinD is thought to localize MinC to the cell poles where it prevents FtsZ assembly. Time-lapse microscopy demonstrates that in Bacillus subtilis transient polar FtsZ rings assemble adjacent to recently completed septa and that in minCD strains these persist and are used for division, producing a minicell. This suggests that MinC acts when division proteins are released from newly completed septa to prevent their immediate reassembly at new cell poles. The minCD mutant appears to uncouple FtsZ ring assembly from cell division and thus shows a variable interdivisional time and a rapid loss of cell cycle synchrony. Functional MinC-GFP expressed from the chromosome minCD locus is dynamic. It is recruited to active division sites before septal biogenesis, rotates around the septum, and moves away from completed septa. Thus high concentrations of MinC are found primarily at the septum and, more transiently, at the new cell pole. DivIVA and MinD recruit MinC to division sites, rather than mediating the stable polar localization previously thought to restrict MinC activity to the pole. Together, our results suggest that B. subtilis MinC does not inhibit FtsZ assembly at the cell poles, but rather prevents polar FtsZ rings adjacent to new cell poles from supporting cell division.
Arabidopsis Synaptotagmin 1 Is Required for the Maintenance of Plasma Membrane Integrity and Cell Viability
Authors: Schapire Arnaldo L. , Voigt Boris , Jasik Jan , Rosado Abel , Lopez-Cobollo Rosa , Menzel Diedrik , Salinas Julio , Mancuso Stefano , Valpuesta Victoriano , Baluska Frantisek , Botella Miguel A.
Published: December 2008

Plasma membrane repair in animal cells uses synaptotagmin 7, a Ca2+-activated membrane fusion protein that mediates delivery of intracellular membranes to wound sites by a mechanism resembling neuronal Ca2+-regulated exocytosis. Here, we show that loss of function of the homologous Arabidopsis thaliana Synaptotagmin 1 protein (SYT1) reduces the viability of cells as a consequence of a decrease in the integrity of the plasma membrane. This reduced integrity is enhanced in the syt1-2 null mutant in conditions of osmotic stress likely caused by a defective plasma membrane repair. Consistent with a role in plasma membrane repair, SYT1 is ubiquitously expressed, is located at the plasma membrane, and shares all domains characteristic of animal synaptotagmins (i.e., an N terminus-transmembrane domain and a cytoplasmic region containing two C2 domains with phospholipid binding activities). Our analyses support that membrane trafficking mediated by SYT1 is important for plasma membrane integrity and plant fitness.
Determinants of the discrepancy in patient‐ and caregiver‐rated quality of life for persons with dementia
Authors: Huang Hsiu‐Li , Chang Mei Yeh , Tang John Sai‐Hung , Chiu Yi‐Chen , Weng Li‐Chueh
Published: December 2008

Aims. To determine factors related to the discrepancy in patient‐ and proxy‐rated quality of life for patients with dementia; whether this discrepancy is associated with characteristics of patients, caregivers or the caregiver–patient relationship; and which characteristics best predict this discrepancy.

Background. To increase the reliability of quality of life measurements for persons with dementia, many researchers have incorporated proxy reports. However, their investigations have indicated that caregiver‐rated quality of life is not the same as the patient’s own rating. The factors related to this discrepancy have previously been explored, but studies rarely focussed on the quality of the caregiver–patient relationship as a determinant of the discrepancy.

Design. A cross‐sectional design was used.

Methods. Data were gathered from community‐based interviews with 120 dyads of patients with Alzheimer’s disease or related dementia and their caregivers in Taipei. A structured questionnaire was used to collect data, and the main variable (quality of life–Alzheimer’s disease) was rated separately by patients and caregivers. The data were analysed using intraclass correlation coefficients and multivariate regression methods.

Results. The agreement between patients’ and caregivers’ quality of life–Alzheimer’s disease ratings was low. This discrepancy was significantly associated with disturbing dementia behaviour, caregivers’ perceived distress for problem behaviours, caregivers’ overall quality of life and quality of the caregiver–patient relationship.

Conclusions. The observed discrepancy between caregiver‐ and patient‐rated quality of life for persons with dementia was largely predicted by the quality of the caregiver–patient relationship.

Relevance to clinical practice. Medical professionals should cautiously deliberate when using caregiver‐reported quality of life to substitute for patient‐reported quality of life. When using a proxy report or a combined caregiver–patient rating, medical professionals should assess the quality of the relationship between patient and proxy.
Non‐invasive ventilation during arm exercise and ground walking in patients with chronic hypercapnic respiratory failure
Authors: MENADUE Collette , ALISON Jennifer A. , PIPER Amanda J. , FLUNT Daniel , ELLIS Elizabeth R.
Published: December 2008

Background and objective:  People with chronic hypercapnic respiratory failure (HRF) often have a ventilatory limitation to exercise with difficulty performing activities of daily living. Although non‐invasive ventilation (NIV) appears to reduce the ventilatory limitation and improve exercise performance in people with severe COPD, the effect of NIV during functional activities such as unsupported arm exercise (UAE) and ground walking in people with chronic HRF is unclear.

Methods:  Seventeen patients with chronic HRF (PaCO2 52.1 ± 5.3 mm Hg) performed a series of UAE tests, and 15 patients (PaCO2 51.7 ± 3.8 mm Hg) performed a series of endurance shuttle walk tests, with and without NIV in a randomized cross‐over design.

Results:  NIV during UAE increased endurance time by a mean of 91 s (95% confidence interval (CI): 10–172, P = 0.031) and reduced dyspnoea by a mean of 2.3 on the Borg scale (95% CI: 1.0–3.7, P = 0.002) compared with exercise without NIV. There was a non‐significant increase in walking endurance time with NIV during exercise (119 s, 95% CI: −17 to 254, P = 0.081); however, isotime dyspnoea was unchanged compared with walking without NIV (−1.0, 95% CI: −3.0 to 1.0, P = 0.29).

Conclusion:  NIV during UAE increased endurance time and reduced dyspnoea compared with exercise without NIV in patients with chronic HRF. Investigation of the role of NIV as an adjunct to UAE training is warranted. In contrast, NIV during ground walking did not improve exercise capacity. However, the pressure support provided may have been inadequate as dyspnoea was not reduced.
Changes in lung function and health status in patients with COPD treated with tiotropium or salmeterol plus fluticasone
Authors: KURASHIMA Kazuyoshi , HARA Kenichirou , YONEDA Kouichirou , KANAUCHI Tetsu , KAGIYAMA Naho , TOKUNAGA Daido , TAKAYANAGI Noboru , UBUKATA Mikio , SUGITA Yutaka
Published: December 2008

Background and objective: The effects of tiotropium, a long‐acting anticholinergic drug, were compared with those of the combination of salmeterol, a long‐acting β2‐agonist, and fluticasone, an inhaled corticosteroid, in patients with COPD.

Methods: A 4‐month, randomized, open cross‐over study of tiotropium, 18 µg once daily, versus salmeterol, 50 µg, plus fluticasone, 200 µg, twice daily, was conducted in patients with COPD. Efficacy was assessed by spirometry and responses to the St George's Respiratory Questionnaire (SGRQ). After 4 months, patients were asked to select their subsequent therapy and indicate the reasons for their selection.

Results: A total of 78 patients completed the study. There were no significant differences in the improvements in FEV1or SGRQ scores between the therapies. Similar numbers of patients selected tiotropium (42.3%) and salmeterol plus fluticasone (57.7%). However, those who preferred one of the therapies demonstrated greater improvements in SGRQ scores with that therapy. One subgroup of patients (30.8%) showed greater improvements in dyspnoea and FEV1in response to tiotropium, and the other subgroup of patients (35.9%) showed greater improvements in dyspnoea and FEV1in response to salmeterol plus fluticasone. Some patients (14.1%) selected salmeterol plus fluticasone because of positive effects on sputum expectoration.

Conclusions: The study was unblinded and the results need to be interpreted with caution. However, tiotropium and salmeterol plus fluticasone had similar overall effects on pulmonary function and SGRQ scores in patients with COPD. Responses to the two therapies were heterogeneous, and the patients who showed greater improvements in FEV1or SGRQ scores with one of the therapies preferred it for their subsequent treatment.
Performance monitoring in children following traumatic brain injury
Authors: Ornstein Tisha J. , Levin Harvey S. , Chen Shirley , Hanten Gerri , Ewing‐Cobbs Linda , Dennis Maureen , Barnes Marcia , Max Jeffrey E. , Logan Gordon D. , Schachar Russell
Published: December 2008

Background:  Executive control deficits are common sequelae of childhood traumatic brain injury (TBI). The goal of the current study was to assess a specific executive control function, performance monitoring, in children following TBI.

Methods:  Thirty‐one children with mild–moderate TBI, 18 with severe TBI, and 37 control children without TBI, of comparable age and sex, performed the stop signal task, a speeded choice reaction time task. On occasion, they were presented with a signal to stop their responses. Performance monitoring was defined as the extent of slowing in go‐task reaction time following failure to stop responses.

Results:  The TBI group as a whole demonstrated less post‐error slowing than did controls. This finding suggested impaired error monitoring performance. In addition, time since injury and socioeconomic status predicted less slowing after stopped responses.

Conclusions:  We suggest that alterations in performance monitoring expressed as the inability to notice, regulate and adjust behavior to changing situations are an effect of TBI in children.
The structure of the Autism Diagnostic Interview‐Revised: diagnostic and phenotypic implications
Authors: Snow Anne V. , Lecavalier Luc , Houts Carrie
Published: December 2008

Background:  Multivariate statistics can assist in refining the nosology and diagnosis of pervasive developmental disorders (PDD) and also contribute important information for genetic studies. The Autism Diagnostic Interview‐Revised (ADI‐R) is one of the most widely used assessment instruments in the field of PDD. The current study investigated its factor structure and convergence with measures of adaptive, language, and intellectual functioning.

Methods:  Analyses were conducted on 1,861 individuals with PDD between the ages of 4 and 18 years (mean = 8.3, SD = 3.2). ADI‐R scores were submitted to confirmatory factor analysis (CFA) and exploratory factor analysis (EFA). Analyses were conducted according to verbal status (n = 1,329 verbal, n = 532 nonverbal) and separately for algorithm items only and for all items. ADI‐R scores were correlated with scores on measures of adaptive, language, and intellectual functioning.

Results:  Several factor solutions were examined and compared. CFAs suggested that two‐ and three‐factor solutions were similar, and slightly superior to a one‐factor solution. EFAs and measures of internal consistency provided some support for a two‐factor solution consisting of social and communication behaviors and restricted and repetitive behaviors. Measures of functioning were not associated with ADI‐R domain scores in nonverbal children, but negatively correlated in verbal children.

Conclusions:  Overall, data suggested that autism symptomatology can be explained statistically with a two‐domain model. It also pointed to different symptoms susceptible to be helpful in linkage analyses. Implications of a two‐factor model are discussed.
Material Flows in Latin America
Authors: Russi Daniela , Gonzalez‐Martinez Ana C. , Silva‐Macher José Carlos , Giljum Stefan , Martínez‐Alier Joan , Vallejo Maria Cristina
Published: December 2008

In this article we compare the resource flows of Chile, Ecuador, Mexico, and Peru between 1980 and 2000. Our objective is to analyze the structure of social metabolism of extractive countries and the consequences of the neoliberal economic structural reforms on the use of natural resources. In two decades, the domestic extraction of materials increased considerably in the four countries, mainly due to the mining sector in Chile and Peru, biomass and oil in Ecuador, and construction minerals in Mexico. Imports and exports also increased, because of the increasingly deeper integration in international markets, prompted by liberalization policies implemented in the four countries between the late 1970s and the late 1990s. All four countries had a negative physical trade balance for most of the period analyzed, with exports exceeding imports in terms of weight. However, parallel growth of imports reduced the physical deficit in Chile, Mexico, and Peru. Ecuador's physical deficit was the highest and did not decrease during the last two decades. A diversification of exports away from bulk commodities could be observed in Chile and Mexico and to a lesser extent in Peru, whereas in Ecuador the export sector remained mainly based on oil and biomass. More research is needed to explore the environmental and social impacts of the neoliberal economic reforms. Also, the indirect flows associated with direct physical imports and exports deserve to be subjected to further analysis.
Australia's Resource Use Trajectories
Authors: Schandl Heinz , Poldy Franzi , Turner Graham M. , Measham Thomas G. , Walker Daniel H. , Eisenmenger Nina
Published: December 2008

Australia's export‐oriented large natural resources sectors of agriculture and mining, the ways large‐scale services, such as nutrition, water, housing, transport and mobility, and energy are organized, and the consumption patterns of Australia's wealthy urban households, create a unique pattern of overall resource use in Australia. In an attempt to contribute to a new environmental information system compatible with economic accounts, we represent Australia's resource use by employing standard biophysical indicators for resource use developed within the Organisation for Economic Co‐operation and Development (OECD) context. We look at the last 3 decades of resource use and the economic, social, and environmental implications. We also discuss scenarios of future resource use patterns based on a stocks and flows model of the Australian economy. We argue that current extractive economic patterns have contributed to the recent economic boom in Australia but will eventually lead to negative social and environmental outcomes. Although there is currently little evidence of political support for changing the economic focus on export‐oriented agriculture and mining industries, there is significant potential for improvements in socio‐technological systems and room for more sustainable household consumption.
Industrialization, Fossil Fuels, and the Transformation of Land Use
Authors: Erb Karl‐Heinz , Gingrich Simone , Krausmann Fridolin , Haberl Helmut
Published: December 2008

Human‐induced changes in global stocks and flows of carbon are major drivers of global climate change. This article presents a comprehensive and systemic account of a nation's carbon budget, comprising socioeconomic as well as ecological carbon flows in a historic time series. The example of Austria 1830–2000, for which excellent databases facilitate a comprehensive assessment, suggests that changes in socioeconomic metabolism during the agrarian−industrial transition are intimately linked with changes in land use and natural carbon flows. In the preindustrial agrarian colonization of Austria (during the thousands of years before 1830), a huge amount of carbon was released due to the expansion of agricultural land. At the dawn of Austria's industrialization (1830–1880), this process was terminated, and carbon inflows and outflows of ecosystems were approximately balanced. With rising fossil fuel consumption, Austria's socioeconomic system added growing amounts of carbon to the atmosphere each year. At the same time, fossil‐fuel‐powered surges in the productivity of agro‐ecosystems facilitated the production of growing amounts of agricultural biomass on shrinking agricultural areas. This greatly enhanced ecological carbon flows and, together with decreasing pressures on forests, allowed ecosystems to recover from past depletion and absorb increasing amounts of carbon. The systematic interlinkage between the socioeconomic energy system and carbon flows in ecosystems, as documented in this study, underlines the need for comprehensive and consistent analyses of society−nature interaction to develop monitoring tools and support strategies aimed at a more sustainable future.
Changes in Materials Use in Transition Economies
Authors: Kovanda Jan , Hak Tomas
Published: December 2008

This article examines the development of material consumption in three transition economies during the years 1990–2002. We compare the Czech Republic, Hungary, and Poland and benchmark their material consumption against average values for the 15 member states of the European Union (formation as of 1995) representing a typical market economy. The article compares consumption of materials in these countries and relates them to relevant socioeconomic variables, using the IPAT equation as a starting point. The article tries to answer whether there has been a convergence in per capita material consumption in these transition economies, in order to identify commonalities associated with the transition from a centrally planned to a market economy in terms of the development of material consumption. We investigate the relation between material consumption, population development, economic growth, and technological change during the transition.

We show that the three transition economies, in general, experienced a convergence in per capita material consumption, including a common decrease in the consumption of biomass. Two out of three countries further recorded a decrease in the consumption of fossil fuels and an increase in the consumption of minerals. We found a general trend of increasing dependence on foreign resources during the transition. On the basis of the IPAT analysis, we found that the development of material consumption was mostly driven by the growth in consumption and by technological change. Although gross domestic product (GDP) growth contributed to a growth in material consumption, the influence of technology supported a reverse effect. In some of the countries, however, the factors decreasing material consumption (i.e., shifts to services and technological change) were not able to outweigh those factors causing material consumption to grow (i.e., increase in GDP).
Administration in a national aboriginal organization: Impacts of cultural adaptations
Authors: DeGagné Mike
Published: December 2008

Abstract: The Aboriginal Healing Foundation, established in 1998, is a self‐governing organization that administers a $350‐million fund for community initiatives across Canada to heal the legacy of physical and sexual abuse in Indian residential schools, including inter‐generational impacts. The foundation is required to adhere to terms of a funding agreement with the federal government, reporting to Indian Residential Schools Resolution Canada, Indian and Northern Affairs Canada. Drawing on the Aboriginal Healing Foundation's final report on its first mandate, 1998–2005, this article details adaptations of administrative practice introduced by the foundation, with the objective of clarifying how respect for cultural context can be implemented while maintaining high standards of administrative practice. Modified approaches and their impacts are examined in terms of effectiveness, efficiency and accountability.
Efficient Nonlinear Vibration Analysis of the Forced Response of Rotating Cracked Blades
Authors: Saito Akira , Castanier Matthew P. , Pierre Christophe , Poudou Olivier
Published: December 2008

The efficient nonlinear vibration analysis of a rotating elastic structure with a crack is examined. In particular, the solution of the forced vibration response of a cracked turbine engine blade is investigated. Starting with a finite element model of the cracked system, the Craig–Bampton method of component mode synthesis is used to generate a reduced-order model that retains the nodes of the crack surfaces as physical degrees of freedom. The nonlinearity due to the intermittent contact of the crack surfaces, which is caused by the opening and closing of the crack during each vibration cycle, is modeled with a piecewise linear term in the equations of motion. Then, the efficient solution procedure for solving the resulting nonlinear equations of motion is presented. The approach employed in this study is a multiharmonic hybrid frequency∕time-domain technique, which is an extension of the traditional harmonic balance method. First, a simple beam model is used to perform a numerical validation by comparing the results of the new method to those from transient finite element analysis (FEA) with contact elements. It is found that the new method retains good accuracy relative to FEA while reducing the computational costs by several orders of magnitude. Second, a representative blade model is used to examine the effects of crack length and rotation speed on the resonant frequency response. Several issues related to the rotation are investigated, including geometry changes of the crack, shifts in resonant frequencies, and the existence of multiple solutions. For the cases considered, it is found that the nonlinear vibration response exhibits the jump phenomenon only when rotation is included in the model.
On the Modeling of Leg Constraints in the Dynamic Analysis of Gough/Stewart-Type Platforms
Authors: Carricato Marco , Gosselin Clément
Published: December 2008

This paper investigates the dynamic model of Gough/Stewart-type platforms, focusing on aspects concerning the proper modeling of leg constraints that seem to have been overlooked in a nonnegligible part of the available literature related to the subject. It shows, in particular, how failure in correctly modeling the arrangement of the universal joints connecting the legs to the base may cause positional, kinematic, and dynamic miscalculations. The effects of these errors are investigated and assessed for relevant cases of leg geometries. Numerical simulations are provided to validate the theory.
Bifurcation Analysis of a Microactuator Using a New Toolbox for Continuation of Hybrid System Trajectories
Authors: Kang Wonmo , Thota Phanikrishna , Wilcox Bryan , Dankowicz Harry
Published: December 2008

This paper presents the application of a newly developed computational toolbox, TC-HAT(TCˆ), for bifurcation analysis of systems in which continuous-in-time dynamics are interrupted by discrete-in-time events, here referred to as hybrid dynamical systems. In particular, new results pertaining to the dynamic behavior of a sample hybrid dynamical system, an impact microactuator, are obtained using this software program. Here, periodic trajectories of the actuator with single or multiple impacts per period and associated saddle-node, period-doubling, and grazing bifurcation curves are documented. The analysis confirms previous analytical results regarding the presence of co-dimension-two grazing bifurcation points from which saddle-node and period-doubling bifurcation curves emanate.
Geometric Modeling and Synthesis of Spatial Multimaterial Compliant Mechanisms and Structures Using Three-Dimensional Multilayer Wide Curves
Authors: Zhou Hong , Ting Kwun-Lon
Published: December 2008

A 3D multilayer wide curve is a spatial curve with variable cross sections and multiple materials. The performance of multimaterial compliant mechanisms and structures is enhanced by integrating multiple materials into one-piece configurations. This paper introduces a geometric modeling method for spatial multimaterial compliant mechanisms and structures by using 3D multilayer wide curves. Based on the introduced modeling method, a geometric synthesis approach is proposed. In this paper, every connection in a spatial multimaterial compliant mechanism or structure is represented by a 3D multilayer wide curve and the whole compliant mechanism or structure is modeled as a set of connected wide curves. The geometric modeling and synthesis are considered as the generation and optimization of the control parameters of the corresponding 3D multilayer wide curves. The performance of spatial multimaterial compliant mechanisms and structures is evaluated by the isoparametric degenerate-continuum nonlinear finite element procedure. The problem-dependent objectives are optimized and the practical constraints are imposed during the synthesis process. The effectiveness of the proposed geometric modeling and synthesis procedures is verified by the demonstrated examples.
Separating Design Optimization Problems Into Decision-Based Design Processes
Authors: Karimian Peyman , Herrmann Jeffrey W.
Published: December 2008

This paper introduces the technique of separation, which replaces a design optimization problem with a set of subproblems. This separation is similar to decomposition but does not require a second-level coordination. We identify conditions under which this separation yields an exact solution and other conditions under which the error can be bounded. We show that the decision-based design framework, which seeks to find the most profitable design, can be separated into a sequence of subproblems. We also apply separation to a motor design problem and demonstrate how the surrogate constraints and objective functions affect the solution quality. These results indicate a way to apply the principles of decision-based design to design processes.
Minimum Vibration Mechanism Design Via Convex Programming
Authors: Lim Bokman , Park Frank C.
Published: December 2008

One means of designing reduced vibration mechanisms is to ensure that the mechanism’s natural frequency be sufficiently greater than the driving frequencies of the actuators. In this paper we consider the problem of determining a mechanism’s mass, inertial, and joint stiffness parameters so as to maximize the lowest natural frequency of the mechanism. We show that this leads to a convex programming problem, which is characterized by a global optima that can be found with efficient interior point algorithms. Several case studies involving open and closed chain mechanisms demonstrate the viability of the design methodology.
Should Designers Worry About Market Systems?
Authors: Shiau Ching-Shin Norman , Michalek Jeremy J.
Published: December 2008

We examine how profit-maximizing designs are influenced by two structural aspects of market systems: (1) the structure of manufacturer-retailer interactions and (2) the structure of heterogeneity in consumer preference modeling. We first model firms as players in a profit-seeking game that compete on product attributes and prices offered. We then model the interactions of manufacturers and retailers in Nash competition under alternative channel structures and compare the equilibrium conditions for each case. We find that under linear logit consumer choice, optimal design can be decoupled from the game, and design decisions can be made without regard to price, competition, or channel structure. However, when consumer preference coefficients are heterogeneous over the population, channel structure is key to determining which designs are most profitable. We examine the extent of this influence in a vehicle design case study from the literature and find that the presence of heterogeneity leads different channel structures to imply different profit-maximizing designs. These findings imply that the common assumption that manufacturers set retail prices may produce suboptimal designs with respect to alternative channel structures. The results highlight the need for coordination between engineering design and product planning decision-makers and the importance that the structure of market systems plays in making design tradeoffs optimally.
Accuracy Analysis of Parallel Manipulators With Joint Clearance
Authors: Meng Jian , Zhang Dongjun , Li Zexiang
Published: December 2008

Due to joint clearance, a parallel manipulator’s end-effector exhibits position and orientation (or collectively referred to as pose) errors of various degrees. This paper aims to provide a systematic study of the error analysis problem for a general parallel manipulator influenced by joint clearance. We propose an error prediction model that is applicable to planar or spatial parallel manipulators that are either overconstrained or nonoverconstrained. By formulating the problem as a standard convex optimization problem, the maximal pose error in a prescribed workspace can be efficiently computed. We present several numerical examples to show the applicability and the efficiency of the proposed method.
Design of Centric Drag-Link Mechanisms for Delay Generation With Focus on Space Occupation
Authors: Al-Dwairi Abdullah F.
Published: December 2008

Planar drag-link mechanism is a Grashofian four-bar chain with the shortest link fixed. In practice, the mechanism is used as a coupling between two shafts to convert uniform rotation of the driving shaft into a nonuniform rotation of the driven shaft. The nonuniformity in rotation is characterized by a cyclically increasing and decreasing delay (or advance) in the displacement of the driven shaft relative to that of the driving shaft. Drag-link synthesis problems include synthesizing the mechanism to generate a specified maximum delay. In a drag-link mechanism, the longer links make a full rotation about fixed pivots, which results in a relatively large installation space. This calls for designing drag-link mechanisms with a focus on space occupation, along with the traditional criteria of quality of motion transmission. Using position analysis, we investigate the relationships among mechanism space occupation, extreme transmission angle, and the generated maximum delay. Space occupation is represented by the link-length ratio of input link to fixed link. Given a desired maximum delay, the proposed approach suggests finding a unique extreme transmission angle value for which this link-length ratio is at a minimum. A closed-form solution to drag-link synthesis to generate a specified maximum delay is developed based on a compromise between quality of motion transmission and space occupation. For any drag-link designed by this compromise, the coupler link and the output crank are of the same length. Based on the obtained design equations, a graphical design solution and a method for evaluating space occupation are provided.
Isolation of Bifidobacteria from Breast Milk and Assessment of the Bifidobacterial Population by PCR-Denaturing Gradient Gel Electrophoresis and Quantitative Real-Time PCR
Authors: Martín Rocío , Jiménez Esther , Heilig Hans , Fernández Leonides , Marín María L. , Zoetendal Erwin G. , Rodríguez Juan M.
Published: December 2008

The objective of this work was to elucidate if breast milk contains bifidobacteria and whether they can be transmitted to the infant gut through breastfeeding. Twenty-three women and their respective infants provided samples of breast milk and feces, respectively, at days 4 to 7 after birth. Gram-positive and catalase-negative isolates from specific media with typical bifidobacterial shapes were identified to the genus level by F6PPK (fructose-6-phosphate phosphoketolase) assays and to the species level by 16S rRNA gene sequencing. Bifidobacterial communities in breast milk were assessed by PCR-denaturing gradient gel electrophoresis (PCR-DGGE), and their levels were estimated by quantitative real-time PCR (qRTi-PCR). Bifidobacteria were present in 8 milk samples and 21 fecal samples.
Bifidobacterium breve
,
B. adolescentis
, and
B. bifidum
were isolated from milk samples, while infant feces also contained
B. longum
and
B. pseudocatenulatum
. PCR-DGGE revealed the presence of one to four dominant bifidobacterial bands in 22 milk samples. Sequences with similarities above 98% were identified as
Bifidobacterium breve
,
B. adolescentis
,
B. longum
,
B. bifidum
, and
B. dentium.
Bifidobacterial DNA was detected by qRTi-PCR in the same 22 milk samples at a range between 40 and 10,000 16S rRNA gene copies per ml. In conclusion, human milk seems to be a source of living bifidobacteria for the infant gut.
MucR, a Novel Membrane-Associated Regulator of Alginate Biosynthesis inPseudomonas aeruginosa
Authors: Hay Iain D. , Remminghorst Uwe , Rehm Bernd H. A.
Published: December 2008

Alginate biosynthesis byPseudomonas aeruginosawas shown to be regulated by the intracellular second messenger bis-(3′-5′)-cyclic-dimeric-GMP (c-di-GMP), and binding of c-di-GMP to the membrane protein Alg44 was required for alginate production. In this study, PA1727, a c-di-GMP-synthesizing enzyme was functionally analyzed and identified to be involved in regulation of alginate production. Deletion of the PA1727 gene in the mucoid alginate-overproducingP. aeruginosastrain PDO300 resulted in a nonmucoid phenotype and an about 38-fold decrease in alginate production; thus, this gene is designatedmucR. The mucoid alginate-overproducing phenotype was restored by introducing themucRgene into the isogenic ΔmucRmutant. Moreover, transfer of the MucR-encoding plasmid into strain PDO300 led to an about sevenfold increase in alginate production, wrinkly colony morphology, increased pellicle formation, auto-aggregation, and the formation of highly structured biofilms as well as the inhibition of swarming motility. Outer membrane protein profile analysis showed that overproduction of MucR mediates a strong reduction in the copy number of FliC (flagellin), required for flagellum-mediated motility. Translational reporter enzyme fusions with LacZ and PhoA suggested that MucR is located in the cytoplasmic membrane with a cytosolic C terminus. Deletion of the proposed C-terminal GGDEF domain abolished MucR function. MucR was purified and identified using tryptic peptide fingerprinting and matrix-assisted laser desorption ionization-time of flight mass spectrometry. Overall, experimental evidence was provided suggesting that MucR specifically regulates alginate biosynthesis by activation of alginate production through generation of a localized c-di-GMP pool in the vicinity of Alg44.
Women's respiratory health in the cotton textile industry: an analysis of respiratory symptoms in 973 non-smoking female workers.
Authors: Beckett W S , Pope C A , Xu X P , Christiani D C
Published: December 2008

As part of a 1992 survey of both environmental and occupational determinants of health, 973 non-smoking women aged 20-40 years who were employed in three comparable modern Chinese cotton textile mills were given a questionnaire that included questions on standard respiratory history and symptoms. All women had some potential exposure to cotton dust; mean employment was 8.7 years. Comparisons were made between those with lowest or no current exposure (job classification in administration, quality control, and testing, n = 112) and those in the more heavily exposed classifications (yarn production areas, n = 861). Association of symptoms with job was tested by logistic regression, adjusting for age, passive smoking at home, and the use of home coal burning stoves. Odds ratios for prevalence of current frequent symptoms in those working in production jobs, after adjustment for home exposure to passive tobacco smoke and coal heating, were frequent cough 2.23 (95% confidence interval (95% CI) 1.05-4.75), frequent phlegm 3.24 (1.54-6.84), shortness of breath 4.54 (1.40-14.72), and wheeze 2.96 (1.16-7.55). Nine cases with grade I byssinosis (chest tightness or shortness of breath on return to work after two days off) were found; all were in production jobs. In these non-smoking women textile workers, chronic respiratory symptoms were associated with job category after correction for domestic indoor air quality. These data support evidence for an increased prevalence of respiratory disease in populations exposed to cotton dust.
The effect of occupational exposure to mercury vapour on the fertility of female dental assistants.
Authors: Rowland A S , Baird D D , Weinberg C R , Shore D L , Shy C M , Wilcox A J
Published: December 2008

Exposure to mercury vapour or inorganic mercury compounds can impair fertility in laboratory animals. To study the effects of mercury vapour on fertility in women, eligibility questionnaires were sent to 7000 registered dental assistants in California. The final eligible sample of 418 women, who had become pregnant during the previous four years, were interviewed by telephone. Detailed information was collected on mercury handling practices and the number of menstrual cycles without contraception it had taken them to become pregnant. Dental assistants not working with amalgam served as unexposed controls. Women with high occupational exposure to mercury were less fertile than unexposed controls. The fecundability (probability of conception each menstrual cycle) of women who prepared 30 or more amalgams per week and who had five or more poor mercury hygiene factors was only 63% of that for unexposed women (95% CI 42%-96%) after controlling for covariates. Women with low exposure were more fertile, however, than unexposed controls. Possible explanations for the U shaped dose response and limitations of the exposure measure are discussed. Further investigation is needed that uses biological measures of mercury exposure.
Exposure of workers to a mixture of toluene and xylenes. I. Metabolism.
Authors: Huang M Y , Jin C , Liu Y T , Li B H , Qu Q S , Uchida Y , Inoue O , Nakatsuka H , Watanabe T , Ikeda M
Published: December 2008

The urinary excretion of hippuric acid and methylhippuric acid was studied in workers (233 subjects; 122 men and 111 women) exposed to toluene and xylenes in combination and in non-exposed controls (281 subjects; 141 men and 140 women) recruited from the same factories or factories of the same regions. Smoking and drinking habits of the subjects were obtained by medical interviews. From each worker, one urine sample was collected at the end of a shift and analysed for hippuric and methylhippuric acids by high performance liquid chromatography. Air samples for the estimation of toluene and xylenes were collected with diffusive personal samplers. There was a linear correlation between the time weighted average exposure either to toluene or xylene isomers and the concentrations of hippuric acid or methylhippuric acid isomers in urine. Essentially no difference was found in the correlation between quantitative exposure and excretion in the three xylene isomers. Comparison of the slopes of regression lines indicated the absence of metabolic interaction between toluene and xylenes at the measured concentrations. The metabolism of toluene and xylenes was significantly reduced among smokers or drinkers compared with non-smokers and non-drinkers.
Effects of inhaled ceramic fibres on macrophage function of rat lungs.
Authors: Morimoto Y , Yamato H , Kido M , Tanaka I , Higashi T , Fujino A , Yokosaki Y
Published: December 2008

To evaluate the biological effect of ceramic fibres on the clearance function of alveolar macrophages (AMs) morphological changes and phagocytic activity of AMs were assessed. Rats were exposed to respirable ceramic fibres with a mass median aerodynamic diameter of 4.4 microns and a concentration of 20.1 mg/m3 in an exposure chamber. They were killed after one week (group A) and two weeks (group B) of exposure, and four weeks (group C) and 12 weeks (group D) after exposure for two weeks. The AMs recovered by bronchoalveolar lavage (BAL) from each test group were incubated with yeast and phagocytic activity was determined by counting the number of yeast cells in AMs. Morphological features of AMs were assessed by scanning electron microscopy and quantified according to morphological changes. Total cell counts in BAL fluid from exposed rats in group A were higher than in control rats. Phagocytic activity of exposed AMs in group B and C exceeded that of control AMs. Morphological changes of the exposed AMs in groups A, B, and C were greater than those of control AMs. These findings suggest that ceramic fibres induced the phagocytic activity and morphological changes in AMs, and that the clearance function of AMs was stimulated by the inhaled ceramic fibres.