bluuebunny/crossref_metadata_2025 huggingface dataset:
Micromechanics of the Deformation and Damage of Steel Fiber-reinforced Concrete
Authors: Ouaar A. , Doghri I. , Delannay L. , Thimus J.-F.
Published: April 2007

This article presents a study of steel fiber-reinforced concrete (SFRC). In its first part, a four-point bending test performed on both plain concrete and SFRC is investigated. The collected nonlinear load—deflection curves are transformed into stress—strain curves with the help of an incremental method, which the authors developed in the nonlinear regime. In the second part of this article, the authors present a micromechanical approach based on Mori—Tanaka/ Voigt mean-field homogenization schemes in order to model the effective nonlinear behavior of the three-phase brittle composite materials. The first phase (concrete matrix) is assumed to obey Ju's brittle damage model. The second phase (fibers) is modeled with classical J 2 plasticity, while the third phase represents cavities. Numerical algorithms enable the simulation of SFRC within reasonable CPU time and memory requirements. The homogenization module is interfaced to the finite element package ABAQUS. A two-scale simulation of the bending test is validated against the experimental results.
Cooperative Client-Side File Caching for MPI Applications
Authors: Liao Wei-keng , Coloma Kenin , Choudhary Alok , Ward Lee
Published: April 2007

Client-side file caching is one of many I/O strategies adopted by today's parallel file systems that were initially designed for distributed systems. Most of these implementations treat each client independently because clients' computations are seldom related to each other in a distributed environment. However, it is misguided to apply the same assumption directly to high-performance computers where many parallel I/O operations come from a group of processes working within the same parallel application. Thus, file caching could perform more effectively if the scope of processes sharing the same file is known. In this paper, we propose a client-side file caching system for MPI applications that perform parallel I/O operations on shared files. In our design, an I/O thread is created and runs concurrently with the main thread in each MPI process. The MPI processes that collectively open a shared file use the I/O threads to cooperate with each other to handle file requests, cache page access, and coherence control. By bringing the caching subsystem closer to the applications as a user space library, it can be incorporated into an MPI I/O implementation to increase its portability. Performance evaluations using three I/O benchmarks demonstrate a significant improvement over traditional methods that use either byte-range file locking or rely on coherent I/O provided by the file system.
A Portable Method for Finding User Errors in the Usage of MPI Collective Operations
Authors: Falzone Christopher , Chan Anthony , Lusk Ewing , Gropp William
Published: April 2007

An MPI profiling library is a standard mechanism for intercepting MPI calls by applications. Profiling libraries are so named because they are commonly used to gather runtime information about performance characteristics. Here we present a profiling library whose purpose is to detect user errors in the use of MPI's collective operations. While some errors can be detected locally (by a single process), other errors involving the consistency of arguments passed to MPI collective functions must be tested for in a collective fashion. While the idea of using such a profiling library does not originate here, we take the idea further than it has been taken before (we detect more errors, including those involving datatype inconsistencies) and present an open-source library that can be used with any MPI implementation. We describe the tests carried out, provide some details of the implementation, illustrate the usage of the library, and present performance tests.
Compensation of Measurement Overhead in Parallel Performance Profiling
Authors: Malony Allen D. , Shende Sameer , Morris Alan , Wolf Felix
Published: April 2007

Performance profiling generates measurement overhead during parallel program execution. Measurement overhead, in turn, introduces intrusion in a program's runtime performance behavior. Intrusion can be mitigated by controlling instrumentation degree, allowing a tradeoff of accuracy for detail. Alternatively, the accuracy in profile results can be improved by reducing the intrusion error due to measurement overhead. Models for compensation of measurement overhead in parallel performance profiling are described. An approach based on rational reconstruction is used to understand properties of compensation solutions for different parallel scenarios. From this analysis, a general algorithm for on-the-fly overhead assessment and compensation is derived.
Regular Paper: Load-Balanced Drift-Diffusion Model Simulation: Cluster Software Performance Evaluation
Authors: Bounanos Stylianos , Fleury Martin , Nicolas Sebastien , Vickers Anthony
Published: April 2007

Design of an avalanche photodiode with high gain and low noise that can achieve single photon counting is a research application of the drift-diffusion model. System-level load balancing when combined with application-level load balancing is shown to improve the performance of simulation code on a Linux cluster supercomputer. The two forms of load balancing are required to approach a smooth increase in performance with scaling. Centralized and distributed organization of the adaptive simulation code reflected the choice of system software. Marked performance differences were observed when two contrasting cluster software parallelization systems, MOSIX and Charm++, were applied. The paper compares the two dynamically load-balanced systems to MPI implementations (LAM and MPICH), which are statically load balanced. Also considered is AMPI, which is based on Charm++ and includes system-level load balancing but additionally implements all MPI calls.
Climacteric Redux?
Authors: Marshall Barbara L.
Published: April 2007

This article analyzes the contemporary construction of male menopause as a clinical disorder. While medical interest in a male climacteric has waxed and waned over the past century, the past decade has witnessed a surge of both scientific and commercial interest in its diagnosis and treatment. In explaining why this is the case, the author suggests that shifting cultural narratives of aging and sexuality, rather than any new scientific evidence, are central to the construction of the aging male body as a pivotal site of biomedical intervention. The clinical and market success of Viagra has been critical in the development of a men's health industry, creating novel discursive and institutional structures that have fostered the medicalization of masculinity in middle and late life. The article analyzes clinical research, popular science reporting, and pharmaceutical marketing to demonstrate how the newly remedicalized male menopause has crystallized anxieties about aging in terms of biochemical de-masculinization.
“Meat vs. Rice”
Authors: Currarino Rosanne
Published: April 2007

This article examines representations of Chinese laborers in the vitriolic anti-Chinese literature produced and consumed nationally in late-nineteenth-century America. Anti-Chinese literature's depictions of the Chinese as excessively frugal and unnaturally abstentious argued that Chinese immigrants contributed nothing to the American economy; indeed, they hurt it. Such depictions facilitated and reflected changing understandings of the relationship between the act of work and manhood, as the proprietary artisan disappeared and wage work became the norm for most working men. Though wage work threatened to sever connections between working men and masculinity both for society at large and for workers themselves, wage workers increasingly reasserted their status as family breadwinner by providing a disposable income for family consumption. In representing true labor negatively through depictions of the Chinese, Americans began to disassociate long-standing correlations between manliness and production. Instead, they suggested that white, working-class manhood might now be located in consumption instead.
Men's Work and Family Reconciliation in Europe
Authors: Holter Øystein Gullvåg
Published: April 2007

Changes from breadwinner masculinities towards caring masculinities are described on the basis of European labour market trends and a recent 6-country study of men in part-time work. Although gender ideals are changing, working life shows a persistent trend towards preservation of breadwinner masculinities, connected to devaluation of men's caregiving. The results highlight the economic and material aspects of change and how work-related gender sanctions operate against men in new roles. Men develop more relational forms of masculinity linked to caregiving and family participation but often face a traditional and deeply ingrained organizational masculinity in their job. However, there is also considerable variation among companies, and some may even take proequality initiatives when the state is passive. Finally, the article presents a broader change model with three main stages (initial, middle, and advanced) and discusses possibilities for more change-oriented research.
London 2012: occupational health in the construction programme
Authors: Waterman Lawrence
Published: April 2007

This article explores the approach to occupational health in the UK construction industry in both broad and narrow contexts. The construction programme for the 2012 Olympic Games and Paralympic Games includes the creation of a large urban park in east London containing many sports venues and served by enhanced infrastructure. The Olympic Delivery Authority (ODA), responsible for the construction programme, is developing plans that seek to assure the health of the thousands of workers who will be engaged in this work. Such plans are not being drafted in a vacuum. In addition to considerable consultation with stakeholders the ODA is also drawing on some of the exciting work that has been undertaken in occupational health in recent years. In particular, the move from a focus on technical health services provided by `experts' to an acceptance that health issues should be managed within employing organizations. Understanding this broad context provides a solid basis for analysing the specific proposals for occupational support during the Olympic Park construction.
Sustainable legacies for the 2012 Olympic Games
Authors: Shipway Richard
Published: April 2007

The London 2012 Olympic and Paralympic Games have the unique potential to deliver sustainable sporting, social, cultural, economic and environmental legacies, not just for London as the host city, but for the whole of Britain. This article focuses primarily on the first three of these potential Olympics legacies. The first area explored is the social legacy as it impacts on host communities; second, the potential educational and cultural legacy of the 2012 Games are examined; and finally, there follows an overview of the health benefits that could result from a sustained increase in mass participation in sport, physical activity and exercise. This appraisal is undertaken through a review of existing Olympic literature and examples are drawn from previous summer and winter Games.

This preliminary exploration is followed by the identification of some key challenges to be overcome if the opportunities available to a wide and diverse range of stakeholders are to be fully optimized. The article suggests that the 2012 Games can act as a catalyst for sports development throughout Britain, while also assisting with government cross-cutting agendas such as tackling crime, antisocial behaviour, developing healthy and active communities, improving educational attainment, and combating barriers to participation. In doing so, this article argues that priority should be placed at supporting grassroots sport through greater access to sport in the community, and not solely elite level sports development.

The article concludes by suggesting that the 2012 Games provide opportunities to deliver real and tangible changes and most importantly, to afford a higher priority to sport, along with the obvious associated health benefits for Britain as a whole. The underlying challenge as we move towards 2012 is to achieve a positive step change in the attitudes towards sport and physical activity in British society. Achieving this would possibly be the greatest legacy of the 2012 Olympic and Paralympic Games.
Access for all: the rise of the Paralympic Games
Authors: Gold John R. , Gold Margaret M.
Published: April 2007

The Paralympic, or Parallel, Games for athletes with disabilities have played a major role over the past half century in changing attitudes towards disability and accelerating the agenda for inclusion. This article charts their development from small beginnings as a competition for disabled ex-servicemen and women in England founded shortly after the Second World War to the present day ambulatory international festival of Summer and Winter Games organized in conjunction with the Olympic Games. The Paralympic Games trace their origins to the work of Dr (later Sir) Ludwig Guttmann at the National Spinal Injuries Unit at Stoke Mandeville Hospital in Buckinghamshire who used sport as an integral part of the treatment of paraplegic patients. A sports competition was held at the hospital to coincide with the Opening Ceremony of the London Games in July 1948. This became an annual event attracting the first international participation in 1952, after which it became the International Stoke Mandeville Games. From 1960 onwards attempts were made to hold every fourth Games in the Olympic host city. Despite initial success in staging the 1960 Games in Rome and the 1964 Games in Tokyo, subsequent host cities refused to host the competitions and alternative locations were found where a package of official support, finance and suitable venues could be assembled. In 1976, the scope of the Games was widened to accept other disabilities. From 1988 onwards, a process of convergence took place that saw the Paralympics brought into the central arena of the Olympics, both literally and figuratively. In the process they have embraced new sports, have encompassed a wider range of disabilities, and helped give credence to the belief that access to sport is available to all. The Paralympics also underline the change from sport as therapeutic competition to that of elite events that carry intrinsic prestige, with growing rivalry over medal tables. For the future, however, questions remain as to whether the current arrangements of separate but supposedly equal festivals assist the continuing development of the Paralympics or perpetuate difference.
Brinkmanship and Beyond: The Political Leadership of Franklin D. Roosevelt
Authors: Hoogenboezem Jaap
Published: April 2007

This article compares two legislative initiatives of President F. D. Roosevelt with the aim of finding an explanation for one of the failures of Roosevelt's presidency: his attempt to change the composition of the Supreme Court in 1937. Comparing Roosevelt's strategy and activities during the Court-packing crisis and drafting and processing the Lend-Lease act it can be concluded that the differences are not structural but gradual. In both cases he pushed the political system to the limits in about the same way, but in the Court-packing case this brinkmanship fails. Roosevelt misinterprets signals and misses good opportunities to come out of it a winner because of specific, and particular circumstances further explored in the article.
Exploring Leadership in Multi-sectoral Partnerships
Authors: Armistead Colin , Pettigrew Paul , Aves Sally
Published: April 2007

This article explores some critical aspects of leadership in the context of multi-sectoral partnerships. It focuses on leadership in practice and asks the question, `How do managers experience and perceive leadership in such partnerships?' The study contributes to the debate on whether leadership in a multi-sectoral partnership context differs from that within a single organization. It is based on the accounts of practising managers working in complex partnerships. The article highlights a number of leadership challenges faced by those working in multi-sectoral partnerships. Partnership practitioners were clear that leadership in partnerships was more complex than in single organizations. However, it was more difficult for them to agree a consensus on the essential nature of leadership in partnership. We suggest that a first-, second- and third-person approach might be a way of better interpreting leadership in the context of partnerships.
Investigation of Microclimate by CFD Modeling of Moisture Interactions between Air and Constructions
Authors: Mortensen Lone H. , Woloszyn Monika , Rode Carsten , Peuhkuri Ruut
Published: April 2007

There is a strong demand for accurate moisture modeling since moisture poses a risk for both the constructions and the indoor climate. This investigation has special focus on moisture modeling. This study describes a new model based on a CFD tool enhanced to include both detailed modeling of airflows in rooms and heat and moisture transfer in walls by applying them as fluid walls. The impacts of different boundary conditions and how these influence microclimates in rooms are investigated, in a 3D configuration. The studied microclimate is a piece of furniture placed near a cold exterior wall.
Thermal Properties of Alkali-activated Slag Subjected to High Temperatures
Authors: Zuda Lucie , Rovnaník Pavel , Bayer Patrik , Černý Robert
Published: April 2007

Alkali-activated slag belongs to prospective materials in the field of fire protection because it exhibits remarkable high-temperature resistance. In this article, specific heat capacity, thermal diffusivity, and thermal conductivity of an alkali-activated slag with sand aggregates are studied as functions of temperature up to 1200°C. The experiments are performed during the material exposure to high temperatures. The irregularities observed on the measured dependences of specific heat capacity and thermal diffusivity on temperature are discussed using the results of DTA and X-ray diffraction analyses. The crystallization of akermanite is identified as the most important factor affecting the properties of the studied material in high-temperature range.
Uncertainty Analysis for Vapor Pressure Measurement
Authors: Shi Xing , Johnson Peggy , Burnett Eric
Published: April 2007

Experimental work in building science/physics involves various kinds of measurements. Uncertainties associated with these measurements are essential for evaluating the accuracy and quality of the experimental work and more importantly, for evaluating the validity of the experimental conclusions. Performing an uncertainty analysis for a complex measurement system that involves various uncertainty sources and requires multiple levels of uncertainty propagation is not an easy task. A general procedure to perform uncertainty analysis of vapor pressure measurements is described. A sensitivity study is included to demonstrate that it can be used to determine the contribution of each uncertainty source. The influence and validity of an important experimental conclusion is evaluated by considering the uncertainty in measurements obtained in an ASHRAE research project.
Radiological and functional changes over 3 years in young children with cystic fibrosis
Authors: Terheggen-Lagro S. W. J. , Arets H. G. M. , van der Laag J. , van der Ent C. K.
Published: April 2007

The aim of the present study was to evaluate airway disease progression assessed by chest radiology, expiratory interrupter resistance (Rint,exp) and spirometry in young children with cystic fibrosis (CF) over a 3-yr period.

Two chest radiographs combined with twoRint,expmeasurements were performed with a 3-yr interval in 21 preschool children (age (mean±sd)3.2±0.9 yrs) and 30 schoolchildren with CF (age 7.2±1.9 yrs). Chest radiographs were scored using five different CF scoring systems andRint,expmeasurements were expressed as height-adjusted Z-scores. Spirometry was assessed in schoolchildren and the results were expressed as a percentage of predicted values.

Chest radiograph scores worsened significantly over the 3-yr period and a tendency towards more pronounced changes was observed, especially for the Wisconsin score, in preschool children. Most preschool and schoolchildren hadRint,expZ-scores within the normal range at start and follow-up, and the annual change inRint,expZ-score was not significant. In schoolchildren, only the forced expiratory volume in one second as a percentage of forced vital capacity declined significantly during the study period.

In summary, in young children with cystic fibrosis, chest radiograph scores worsen significantly over time even while lung function remains stable.
Upper airway collapsibility, dilator muscle activation and resistance in sleep apnoea
Authors: Pierce R. , White D. , Malhotra A. , Edwards J. K. , Kleverlaan D. , Palmer L. , Trinder J.
Published: April 2007

The calibre of the upper airway is thought to be dependant upon its passive anatomy/collapsibility and the activation of pharyngeal dilator muscles. During awake periods, the more collapsible upper airway in obstructive sleep apnoea (OSA) increases the dilator muscle activity through a negative-pressure reflex.

A direct correlation between the critical closing pressure (Pcrit), as a measure of anatomy/collapsability and electromyogram (EMG) activity of genioglossus EMG (GG-EMG) and tensor palatini EMG (TP-EMG), was hypothesised. The relationship between these indices and pharyngeal resistance (Rphar) was also examined.

The study involved eight males with a mean age of 48 (interquartile range 46–52) yrs with OSA, and an apnoea/hypopnoea index of 75 (65–101)·hr−1on two nights breathing normally and on nasal continuous positive airway pressure (nCPAP). ThePcritwas measured during nonrapid eye movement sleep on nCPAP using brief, incremental reductions in mask pressure. GG-EMG and TP-EMG were measured breath-by-breath, awake, during sleep onset and on nCPAP.Rpharwas measured using airway pressures and flow.

Wakeful GG-EMG, early sleep TP-EMG and the sleep decrement in TP-EMG were directly related toPcrit. Muscle activation was negatively correlated withRpharfor TP-EMG awake and GG-EMG early in sleep.

In conclusion these results confirm that dilator muscle activation is directly related to airway narrowing and reduces resistance across patients with obstructive sleep apnoea.
Hyperleptinaemia, respiratory drive and hypercapnic response in obese patients
Authors: Campo A. , Frühbeck G. , Zulueta J. J. , Iriarte J. , Seijo L. M. , Alcaide A. B. , Galdiz J. B. , Salvador J.
Published: April 2007

Leptin is a powerful stimulant of ventilation in rodents. In humans, resistance to leptin has been consistently associated with obesity. Raised leptin levels have been reported in subjects with sleep apnoea or obesity–hypoventilation syndrome. The aim of the present study was to assess, by multivariate analysis, the possible association between respiratory centre impairment and levels of serum leptin.

In total, 364 obese subjects (body mass index ≥30 kg·m−2) underwent the following tests: sleep studies, respiratory function tests, baseline and hypercapnic response (mouth occlusion pressure (P0.1), minute ventilation), fasting leptin levels, body composition and anthropometric measures. Subjects with airways obstruction on spirometry were excluded.

Out of the 346 subjects undergoing testing, 245 were included in the current analysis. Lung volumes, age, log leptin levels, end-tidal carbon dioxide tension, percentage body fat and minimal nocturnal saturation were predictors for baselineP0.1. The hypercapnic response test was performed by 186 subjects; log leptin levels were predictors for hypercapnic response in males, but not in females.

Hyperleptinaemia is associated with a reduction in respiratory drive and hypercapnic response, irrespective of the amount of body fat. These data suggest the extension of leptin resistance to the respiratory centre.
Peroxisome proliferator-activated receptor expression is reduced in skeletal muscle in COPD
Authors: Remels A. H. , Schrauwen P. , Broekhuizen R. , Willems J. , Kersten S. , Gosker H. R. , Schols A. M.
Published: April 2007

Chronic obstructive pulmonary disease (COPD) is a multiorgan systemic disease. The systemic features are skeletal muscle weakness and cachexia, the latter being associated with systemic inflammation. The exact mechanisms underlying skeletal muscle dysfunction in COPD remain obscure. Recent evidence suggests involvement of the peroxisome proliferator-activated receptors (PPARs) and PPAR-γ coactivator (PGC)-1α in regulation of skeletal muscle morphology and metabolism, and mitochondrial transcription factor A (TFAM) has been implicated in the process of mitochondrial biogenesis. The aim of the present exploratory study was, therefore, to compare these factors in the skeletal muscle of nine healthy control subjects and 14 COPD patients stratified by cachexia.

PPAR-γ, PPAR-δ and TFAM were measured at the mRNA and protein level by real-time quantitative PCR and Western blotting, respectively. PPAR-α and PGC-1α were meansured at the mRNA level.

PPAR-δ and TFAM protein content, as well as PGC-1α mRNA levels, were decreased in the skeletal muscle of COPD patients compared with healthy controls. The cachectic COPD subgroup was further characterised by decreased PPAR-α mRNA expression and decreased TFAM protein and mRNA levels compared with noncachectic COPD patients. In addition, PPAR-α mRNA levels in skeletal muscle correlated negatively with inflammatory markers in plasma.

Therefore, a disturbed expression of these regulatory factors may well underlie the disturbed skeletal muscle functioning in chronic obstructive pulmonary disease.
Systematic review of noninvasive positive pressure ventilation in severe stable COPD
Authors: Kolodziej M. A. , Jensen L. , Rowe B. , Sin D.
Published: April 2007

The present systematic review examined the effectiveness of bilevel noninvasive positive pressure ventilation (NIPPV) in the management of chronic respiratory failure (CRF) due to severe stable chronic obstructive pulmonary disease (COPD).

Randomised controlled trials (RCTs) and non-RCTs (crossover design) of adults with severe stable COPD and CRF receiving bilevel NIPPVvianasal, oronasal or total face mask were identified from electronic databases and manual screening of journals and reference lists.

Respiratory function (gas exchange, lung function, ventilatory/breathing pattern, respiratory muscle function and work of breathing) and health-related outcomes (dyspnoea, functional status, exercise tolerance, health-related quality of life (HRQOL), morbidity and mortality) were assessed.

In total, 15 studies met the inclusion criteria: six RCTs and nine non-RCTs. RCTs did not find improved gas exchange with bilevel NIPPV, while non-RCTs did. Lung hyperinflation and diaphragmatic work of breathing were reduced in a nonrandomised subset. HRQOL and dyspnoea, the least studied outcomes, showed improvement with bilevel NIPPV.

In a subset of individuals on maximal medical treatment regimes for severe stable chronic obstructive pulmonary disease, bilevel noninvasive positive pressure ventilation may have an adjunctive role in the management of chronic respiratory failure through attenuation of compromised respiratory function and improvement in health-related outcomes.
In Situ Calcium Signaling
Authors: BURDYGA THEODOR , WRAY SUSAN , NOBLE KAREN
Published: April 2007

Abstract:  Controlled uterine smooth muscle activity is essential for our reproductive health. While we understand reasonably well the steps that produce contraction following a rise in intracellular [Ca], the mechanism controlling excitability and thus the rise of Ca, is less well understood. Here we examine the role of the internal Ca sore, the sarcoplasmic reticulum (SR), and its relation to surface membrane ion channels. We show that despite having a well‐developed SR, the rat uterus does not produce the elemental and local Ca signals, known as Ca sparks. This in turn has consequences for excitability, as the negative feedback loop between these Ca signals and Ca‐activated K (BK) channels on the surface membrane is lost. This may be important for producing the powerful long‐lasting contractions of the uterus required during labor.
Mechanobiology of Embryonic Limb Development
Authors: NOWLAN NIAMH C. , MURPHY PAULA , PRENDERGAST PATRICK J.
Published: April 2007

Abstract:  Considerable evidence exists to support the hypothesis that mechanical forces have an essential role in healthy embryonic skeletal development. Clinical observations and experimental data indicate the importance of muscle contractions for limb development. However, the influence of these forces is seldom referred to in biological descriptions of bone development, and perhaps this is due to the fact that the hypothesis that mechanical forces are essential for normal embryonic skeletal development is difficult to test and elaborate experimentally

in vivo

, particularly in humans. Computational modeling has the potential to address this issue by simulating embryonic growth under a range of loading conditions but the potential of such models has yet to be fully exploited. In this article, we review the literature on mechanobiology of limb development in three main sections: (

a

) experimental alteration of the mechanical environment, (

b

) mechanical properties of embryonic tissues, and (

c

) the use of computational models. Then we analyze the main issues, and suggest how experimental and computational fields could work closer together to enhance our understanding of mechanobiology of the embryonic skeleton.
In Vivo Characterization of the Mechanics of Human Uterine Cervices
Authors: BAUER MARGIT , MAZZA EDOARDO , NAVA ALESSANDRO , ZECK WILLIBALD , EDER MARTINA , BAJKA MICHAEL , CACHO FERNANDO , LANG UWE , HOLZAPFEL GERHARD A.
Published: April 2007

Abstract:  The uterine cervix has to provide mechanical resistance to ensure a normal development of the fetus. This is guaranteed by the composition of its extracellular matrix, which functions as a fiber‐reinforced composite. At term a complex remodeling process allows the cervical canal to open for birth. This remodeling is achieved by changes in the quality and quantity of collagen fibers and ground substance and their interplay, which influences the biomechanical behavior of the cervix but also contributes to pathologic conditions such as cervical incompetence (CI). We start by reviewing the anatomy and histological composition of the human cervix, and discuss its physiologic function and pathologic condition in pregnancy including biomechanical aspects. Established diagnostic methods on the cervix (palpation, endovaginal ultrasound) used in clinics as well as methods for assessment of cervical consistency (light‐induced fluorescence, electrical current, and impedance) are discussed. We show the first clinical application of an aspiration device, which allows in vivo testing of the biomechanical properties of the cervix with the aim to establish the physiological biomechanical changes throughout gestation and to detect pregnant women at risk for CI. In a pilot study on nonpregnant cervices before and after hysterectomy we found no considerable difference in the biomechanical response between in vivo and ex vivo. An outlook on further clinical applications during pregnancy is presented.
Microstructure and Mechanics of the Chorioamnion Membrane with an Emphasis on Fracture Properties
Authors: CALVIN STEVEN E. , OYEN MICHELLE L.
Published: April 2007

Abstract:  The normal mechanical functioning of an intact chorioamnion (CA) membrane is essential to successful human reproduction. The amnion and the chorion, separately and together as the bilayer chorioamnion, serve barrier and container functions throughout gestation, and these two important roles are required from conception to birth. The event associated with the “breaking of waters” is a landmark event in labor and delivery. Mechanical rupture of the CA membrane is part of the natural sequence of term delivery, but has serious implications when rupture occurs prior to term; preterm premature rupture of the CA membrane (PPROM) is associated with one‐third of premature births. The current manuscript reviews PPROM from a clinical, anatomical, and mechanical perspective with a special focus on the clinically relevant fracture properties of these membranes. Emphasis is given to the link between membrane structure and properties at macroscopic and microscopic length scales. Because it has been demonstrated that the mechanical properties of prematurely failed membranes are not different from membranes of the same gestational age that have remained intact, membrane failure is a local process that must be explored in terms of local changes in structure and properties of isolated portions of the membrane. Future diagnostic techniques aimed at detection of changes in membrane structure (including thickness) and altered mechanical stiffness or strength may allow for prefailure diagnosis of membrane weak spots, thus opening the door for potential intervention and treatment techniques for preterm membrane rupture.
Fluid Dynamic Models of Flagellar and Ciliary Beating
Authors: DILLON ROBERT H. , FAUCI LISA J. , OMOTO CHARLOTTE , YANG XINGZHOU
Published: April 2007

Abstract: We have developed a fluid–mechanical model of a eucaryotic axoneme that couples the internal force generation of dynein molecular motors, the passive elastic mechanics of microtubules, and forces due to nexin links with a surrounding incompressible fluid. This model has been used to examine both ciliary beating and flagellar motility. In this article, we show preliminary simulation results for sperm motility in both viscous and viscoelastic fluids, as well as multiciliary interaction with a mucus layer.
Molecular Basis of Sperm Flagellar Axonemes
Authors: INABA KAZUO
Published: April 2007

Abstract:  The axonemes serve as motile machineries in sperm flagella. Although atypical axonemal structures are observed in some cases, 9 + 2 microtubule structure of the axoneme is predominant in many organisms. Several structures are bound to these microtubules and comprise a highly organized protein network. Extensive proteomic analysis of the axonemes has led to find several repeats, domains, and motifs in axonemal proteins. Molecular comparison of subunit composition of axonemal substructures between the ascidian Ciona intestinalis and the green algae Chlamydomonas reinhardtti leads to an intriguing molecular aspect concerning the evolution of intracellular functional complex: The architecture of the axonemes has been well conserved through evolution, but the molecular structure of each axonemal component is not always conserved. In light of domain structure in the axonemal proteins, substructures like outer arm dynein and radial spoke contain a set of domain structures, although some domain‐containing subunits are different between these two organisms. Thus, conservation of protein domains within a substructure seems to take precedence over that of each protein (“module‐dominant conservation”), which may ultimately result in morphological and functional conservation of the axonemes through evolution.
Modeling Acardiac Twin Pregnancies
Authors: De GROOT ROSA , Van Den WIJNGAARD JEROEN P. H. M. , UMUR ASLI , BEEK JOHAN F. , NIKKELS PETER G. J. , Van GEMERT MARTIN J. C.
Published: April 2007

Abstract:  Acardiac twin pregnancies are a rare but severe complication of monochorionic twinning, where the acardiac twin lacks cardiac function but nevertheless grows during pregnancy because it is perfused by the pump twin through a set of placental arterioarterial and venovenous anastomoses. Because the acardiac twin's body is only perfused by the pump twin's arterial blood, acardiac twins have reduced blood oxygen saturation (SO2) levels. Furthermore, the pump twin has reduced blood oxygen saturation because the anastomoses merge the blood of the two twins. We suggested that angiogenesis from hypoxia mediated neovascularization increases the capillary density in the acardiac twin and causes a continuously decreasing vascular resistance of the acardiac body. The pump twin therefore has a continuously increasing cardiac output and decreasing oxygen saturation, which may cause a vicious circle of increasing levels of pump twin complications, often leading to intrauterine fetal death. Our aim in this article was twofold. First, to summarize our previous modeling work of acardiac twin pregnancies, and add an estimate of the capillary density in mammals at different levels of SO2 from a literature search on angiogenesis related to SO2, Hypoxia Inducible Factor, and Vascular Endothelial Growth Factor. Second, to speculate that combination of these efforts and our most recent model of monochorionic twin pregnancies and twin–twin transfusion syndrome may result in an improved computational model for acardiac twin pregnancies, aimed at identifying early clinical prognostic markers for pump twin complications.
The Geometric Clutch as a Working Hypothesis for Future Research on Cilia and Flagella
Authors: LINDEMANN CHARLES B.
Published: April 2007

Abstract:  The Geometric Clutch hypothesis contends that the forces transverse to the flagellar axis (t‐forces) act on the axonemal scaffold to regulate flagellar beating. T‐forces develop as the product of the curvature and the accumulated tension or compression on the doublet microtubules. In this respect, t‐force is a mediator of self‐organizing behavior. It arises from the collective action of the assemblage of dynein motors on the structural components of the axoneme and, in turn, imparts order to the sequence of activation and deactivation of the dynein. At the switch point of the flagellar beat, the magnitude of the t‐force per micron of flagellum is approximately equal to the sum total of dynein force that can be generated per micron of flagellum. This suggests that the t‐force could directly overcome the force‐producing dynein bridges and terminate their action. However, many questions remain to be answered concerning the behavior of the axonemal scaffold under stress. Little is known of the force‐bearing capacity of the radial spokes and the central pair (cp) projections. The properties of these structures will determine how t‐force is distributed within the axoneme. The mechanical and elastic properties of the dynein arms and nexin links need to be better understood to determine how they respond to the application of t‐force. In the framework of the Geometric Clutch hypothesis these are the issues that are most important to explore if we are to understand how the flagellum works.
Analysis of Cervical Dynamics by Ultrasound Imaging
Authors: PUGATSCH RIMMA , ELAD DAVID , JAFFA ARIEL J. , EYTAN OSNAT
Published: April 2007

Abstract:  Preterm birth is generally due to cervical ripening during the second trimester of pregnancy. The diagnosis of cervical incompetence is mostly based on the measurement of the shortened cervical length from transvaginal ultrasound (TVUS) images. We investigated the cervical dynamic response to spontaneous or imposed variations of intrauterine pressure, which may induce cervical shortening. The TVUS images of the cervix sagittal cross‐sections were recorded from six women in mid pregnancy. The cervical dynamics was observed while the subject was either in a supine position, kneeling, or had undergone transfundal pressure in a supine position. Each subject was tested in all three positions, but the dynamic response was observed in only one of them. The time‐dependent analysis was performed on consecutive TVUS images at time intervals of 1 s to extract the dynamic response of the funneling geometry and the closed cervical length. The internal os was considered as being a point on the uterine wall and characterized by a sharp gradient of the inner wall of the uterine cavity. Dynamic evaluation of TVUS images revealed that shortening of the cervical length was greater than 30% and that the funneling percentage was greater than 40%. This study demonstrates the clinical potential for dynamic assessment of cervical response due to excessive uterine pressure, in addition to its application for the conventional measurement of cervical length.
Functional Anatomy of the Female Pelvic Floor
Authors: ASHTON‐MILLER JAMES A. , DeLANCEY JOHN O. L.
Published: April 2007

Abstract:  The anatomic structures in the female that prevent incontinence and genital organ prolapse on increases in abdominal pressure during daily activities include sphincteric and supportive systems. In the urethra, the action of the vesical neck and urethral sphincteric mechanisms maintains urethral closure pressure above bladder pressure. Decreases in the number of striated muscle fibers of the sphincter occur with age and parity. A supportive hammock under the urethra and vesical neck provides a firm backstop against which the urethra is compressed during increases in abdominal pressure to maintain urethral closure pressures above the rapidly increasing bladder pressure. This supporting layer consists of the anterior vaginal wall and the connective tissue that attaches it to the pelvic bones through the pubovaginal portion of the levator ani muscle, and the uterosacral and cardinal ligaments comprising the tendinous arch of the pelvic fascia. At rest the levator ani maintains closure of the urogenital hiatus. They are additionally recruited to maintain hiatal closure in the face of inertial loads related to visceral accelerations as well as abdominal pressurization in daily activities involving recruitment of the abdominal wall musculature and diaphragm. Vaginal birth is associated with an increased risk of levator ani defects, as well as genital organ prolapse and urinary incontinence. Computer models indicate that vaginal birth places the levator ani under tissue stretch ratios of up to 3.3 and the pudendal nerve under strains of up to 33%, respectively. Research is needed to better identify the pathomechanics of these conditions.
Kandire in Real Time and Space: Sixteenth-Century Expeditions from the Pantanal to the Andes
Authors: Julien Catherine
Published: April 2007

Anthropological understandings of past relations between peoples in the interior of South America have been constructed from limited readings of the historical sources. A case in point: the linkage of a hypothesis about the westward migration of Guaraní speakers in search of a “Land-without-Evil” to the Pantanal region on the upper Paraguay River was based on the reading of a single document from the period of exploration. This reading does not stand up when the larger corpus of written materials from this period is taken into account. Interview texts and narrative reports tell about travel from the Pantanal west to the Inca frontier to raid or trade for metals and to free captives taken on previous trips. Those who have suggested that the “Land-without-Evil” explains the dispersal of Guaraní speakers to the foothills and lowlands just east of the Andes adhere to the idea that linguistic relatedness is a conduit for the transmission of culture across all speakers and through time. What is problematic is that the classification of South American peoples on the basis of language was a product of European exploration. When the documents are read for what they tell us about what happened in real time and space, other ideas about social and political groupings and about the movement of peoples and languages begin to emerge.
Chocolate in the Underworld Space of Death: Cacao Seeds from an Early Classic Mortuary Cave
Authors: Prufer Keith M. , Hurst W. Jeffrey
Published: April 2007

Archaeological investigations at a mortuary cave in southern Belize recovered a bowl containing five cacao (chocolate) seeds dating to the fourth or fifth century AD. The context of both the burial and the cacao informs our understanding of the role of chocolate as a ritual substance in pre-Columbian Mesoamerica. Most archaeologists think of cacao as having an economic function as a form of currency or as a prepared beverage whose use was restricted to elites. However, a review of documentary sources at the time of Spanish contact as well as of ethnographic accounts indicates that cacao is an integral component in many rites of passage, including those associated with birth, social personhood, initiation, marriage, and death, as well as the initiation of shamans. As such it becomes an intimate ritual product implicated in areas of social identity and reproduction that transcend economic and political status. Its presence in a burial likely indicates that it was either an important possession of the deceased or intended to provide ritual sustenance during the passage into the afterworld.
Through the Looking Glass: The Politics of the Medicare Prescription Drug, Improvement, and Modernization Act
Authors: Oberlander Jonathan
Published: April 2007

The 2003 Medicare Prescription Drug, Improvement, and Modernization Act (MMA) represents a watershed event in Medicare politics. This essay explores the political lessons and policy legacies of the MMA, focusing on how the MMA fits with and deviates from established patterns in Medicare politics and how it will affect future reform.
Secret Weapon: The “New” Medicare as a Route to Health Security
Authors: Schlesinger Mark , Hacker Jacob S.
Published: April 2007

Over the past twenty years, Medicare has been transformed from a single-payer insurer into a hybrid of complementary public and private insurance arrangements. Despite creating ongoing controversy, these changes have resulted in an ironic and largely overlooked strategic potential: Medicare's evolving hybrid form makes it the most promising vehicle for overcoming the historical obstacles to universal health insurance in the United States. To make this surprising case, we first explore the distinctive political dynamics of programs that, like today's Medicare, are hybrids of public and private arrangements. We then consider how these political dynamics might circumvent past barriers to universal health insurance. Finally, we discuss the strengths and weaknesses of alternative pathways through which Medicare could be expanded to promote health security.
Adrenal gland tumours in two cotton-top tamarins (Saguinus oedipus oedipus)
Authors: Brack M.
Published: April 2007

Two adrenal gland tumours in captive born cotton-top tamarins ( Saguinus oedipus oedipus) are described. One was a pheochromocytoma in a 14-year-old male, the other one a cortical adenoma in a 7.5-year-old female. Both were associated with morphological signs of myocardial damage and circulatory problems. The findings are discussed and compared to adrenal gland tumours in man.
Ten-year long monitoring of laboratory mouse and rat colonies in French facilities: a retrospective study
Authors: Zenner Lionel , Regnault Jean-Pierre
Published: April 2007

From 1988 to 1997, a total of 69 mouse colonies and 36 rat colonies were examined for the presence of antibodies to 14 indigenous viruses of mice and rats. Among mouse viruses, high positivity rates were observed with mouse hepatitis virus (MHV), Theiler's encephalomyelitis virus (THEMV), minute virus of mice (MVM), Sendai virus and pneumonia virus of mice (PVM); the prevalence rates were high in rats with Khilam's rat virus (KRV), THEMV, Toolan's H-1 virus, Sendai virus, Parker's rat coronavirus (RCV/SDA) and PVM. During the last decade, the prevalence of some agents such as MHV, Sendai virus, THEMV, PVM and MVM has apparently decreased although they were still present in 1997 (except for PVM). Another point is the constant increase of colonies found free of viruses through this decade, demonstrating the efforts of the French research community to increase the quality of hygiene in laboratory animals.