bluuebunny/crossref_metadata_2025_split huggingface dataset:
Administration of insulin‐like growth factor‐I improves fatigue resistance of skeletal muscles from dystrophic mdx mice
Authors: Gregorevic Paul , Plant David R. , Lynch Gordon S. 
Published: July 2004

AbstractMuscle fatigue occurs in many neuromuscular diseases, including the muscular dystrophies, and it contributes to a loss of functional capacity and reduced quality of life for affected patients. An improvement in fatigue resistance has been observed in diaphragm muscles of mdx mice following insulin‐like growth factor‐I (IGF‐I) administration. Whether similar treatment can improve locomotor muscle function in mdx mice is not known. We examined the efficacy of IGF‐I administration (1 mg/kg daily s.c. for 8 weeks) on structural, metabolic, and functional properties of extensor digitorum longus (EDL) and soleus muscles of mdx mice, and tested the hypothesis that IGF‐I treatment would improve function in these muscles. After treatment, muscles were more resistant to fatigue during repeated maximal contractions than muscles from untreated mice, an improvement associated with increased muscle fiber succinate dehydrogenase activity in the absence of changes in cellular (single‐fiber) contractile activation characteristics. The findings have important clinical implications, not just for the dystrophinopathies, but for all neuromuscular pathologies where fatigue of locomotor muscles limits functional capacity and decreases quality of life. Muscle Nerve 30: 295–304, 2004
Muscle loading as a method to isolate the underlying tremor components in essential tremor and Parkinson's disease
Authors: Burne John A. , Blanche Tim , Morris John J. 
Published: July 2004

AbstractTremor is clinically evaluated and classified on the basis of its response to limb posture (resting, postural, and kinetic tremor), but the mechanisms underlying this powerful influence remain unclear and no satisfactory method exists to identify or quantify underlying tremor subtypes. Postural change is closely linked to changes in gravitational load. We therefore assessed the effect of changes in muscle load on essential tremor (ET) and parkinsonian tremor (PT) independently of postural change. A motor accurately delivered a series of constant (0.2–1.2 Nm) flexion and extension torques about the affected wrist while subjects maintained a constant wrist angle by isometrically contracting wrist flexors or extensors against the applied loads. Linear regression of tremulous electromyogram (EMG) spectral peak amplitude against the applied loads estimated the magnitudes of the load‐dependent (LDT) and load‐independent (LIT) tremor components. The amplitude of ET was linearly related to increase in gravitational load. It thus contained a large LDT component and a small or absent LIT component. Muscle loading revealed significant LDT and LIT components in PT. LIT was dominant at zero load (classic rest tremor) but both components were present during loading (classic postural tremor). Muscle loading more clearly identifies tremor subtypes than postural effects alone. The method could be applied in clinical and pathophysiological studies. Muscle Nerve 30: 347–355, 2004
Do F‐wave measurements detect changes in motor neuron excitability?
Authors: Lin Jenny Z. , Floeter Mary Kay 
Published: July 2004

AbstractThe use of F waves to assess motor neuron excitability in experimental paradigms has never been validated. Our objective was to determine whether F‐wave area, amplitude, and persistence measurements change in response to manipulations known to alter the excitability of motor neurons. The effects of muscle vibration, contraction of a remote muscle, and high‐intensity stimulation of ipsilateral or contralateral fingers were assessed in 12 healthy volunteers. F‐wave area, amplitude, and persistence all declined with ipsilateral cutaneous stimulation. The other maneuvers facilitated some, but not all, of the F‐wave measurements. Changes in F‐wave area and amplitude were correlated, but neither correlated with changes in persistence. A sample size of 50–75 F waves was needed to approximate amplitude and area results from 100 F waves with an accuracy of ±25%. We conclude that changes in F waves are better at detecting inhibition than facilitation of motor neurons. F waves reflect motor neuron excitability in a general way but do not allow for accurate measures of short‐term changes in excitability. Muscle Nerve 30: 289–294, 2004
A probabilistic analysis of a fixed partition policy for the inventory‐routing problem
Authors: Anily Shoshana , Bramel Julien 
Published: July 2004

AbstractWe consider the Inventory‐Routing Problem (IRP) where n geographically dispersed retailers must be supplied by a central facility. The retailers experience demand for the product at a deterministic rate, and incur holding costs for keeping inventory. Distribution is performed by a fleet of capacitated vehicles. The objective is to minimize the average transportation and inventory costs per unit time over the infinite horizon. We focus on the set of Fixed Partition Policies (FPP). In an FPP, the retailers are partitioned into disjoint and collectively exhaustive sets. Each set of retailers is served independently of the others and at its optimal replenishment rate. Previous research has measured the effectiveness of an FPP solution relative to a lower bound over all policies. We propose an additional measure that is relative to the optimal FPP. In this paper we construct a polynomial‐time partitioning scheme that is shown to yield an FPP whose cost is asymptotically within 1.5% + ϵ of the cost of an optimal FPP, for arbitrary ϵ > 0. In addition, in some cases, our polynomial‐time scheme yields an FPP whose cost is asymptotically within 1.5% + ϵ of the minimal policy's cost (over all feasible policies). © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004
Structure‐property relationships in polymer blend nanocomposites
Authors: Lee Keun Yong , Goettler Lloyd A. 
Published: July 2004

AbstractNanocomposites comprising nanoscale platelets derived from layered silicates treated with an organic modifier in thermoplastic vulcanizates (TPV) and PP/EPDM blends were prepared by direct melt intercalation. The interlayer spacing and dispersion of the nanoclay are greatly affected by polar forces between the nanoclay and the polymeric matrix material. The mechanical properties strongly depend on the structure and morphology of the nanocomposites, which can be modified by phase partitioning of the reinforcements. Morphology characterization by X‐ray diffraction (XRD) and transmission electron microscopy (TEM) provides the basis for understanding the observed structure‐property relationships in this class of materials. With the increase of organoclay loading, the tensile modulus of TPV/clay nanocomposites increases by up to 170% at 8 wt% organoclay loading, while tensile strength gradually decreases with increase of organoclay loading. In the physical blend systems, the tensile modulus increases for all PP/EPDM blend compositions and generally shows higher values in the case of selectively reinforced phases in blends having a continuous PP matrix. The tensile strength of those blends decreases at higher nanoclay content no matter how blending is performed. However, the tensile strength may increase when sufficient selectively reinforced EPDM phase is present. Polym. Eng. Sci. 44:1103–1111, 2004. © 2004 Society of Plastics Engineers.
Addressing the interface in polymer‐clay nanocomposites by electron paramagnetic resonance spectroscopy on surfactant probes
Authors: Jeschke G. , Panek G. , Schleidt S. , Jonas U. 
Published: July 2004

AbstractThe structure and dynamics of the surfactant layer in organoclays prepared from synthetic clays (Laponites, expandable fluoromica) and in their composites with polystyrene are studied in order to understand the influence of the interface layer on composite properties and composite formation from melt or solution. Electron paramagnetic resonance spectroscopy of nitroxide‐labeled surfactants is used to examine length scales between a few Ångstrøms and a few nanometers and time scales between 10 ps and 1 μs. The nitroxide labels are stable up to at least 433 K, so that dynamics can be studied at temperatures relevant for melt intercalation. For organoclays prepared with an excess of surfactant with respect to cation exchange capacity, two or three fractions of surfactants with different mobility exist, the number of fractions, their relative amount, and the mobility differences being determined by the type of clay. Dynamics close to the region of the anchor groups depends on the type of clay and, for large clay particles, on the presence and molecular weight of polystyrene. For dispersions of organoclay in toluene‐d8, deuterium electron spin echo envelope modulation evidences penetration of solvent molecules into the surfactant layer down to the region of the anchor groups. Changes in spatial distribution of the anchor groups caused by intercalation can be detected. Polym. Eng. Sci. 44:1112–1121, 2004. © 2004 Society of Plastics Engineers.
Polypropylene/graphite nanocomposites by thermo‐kinetic mixing
Authors: Gopakumar T. G. , Pagé D. J. Y. S. 
Published: July 2004

AbstractPolypropylene (PP)/graphite nanocomposites have been prepared by melt‐mixing PP with different levels of graphite (G) and graphite oxide (GO) using maleated PP(PP‐g‐MA) and graphite oxide (GO) as interface modifiers. Melt‐mixing was achieved using a Gelimat, a high‐speed thermo‐kinetic mixer. The Gelimat system is specifically designed to handle difficult compounding and dispersion applications by completely mixing, heating and compounding products within a few minutes. Therefore, the thermal history of the compounded polymer is very short, which limits degradation. Interfacial modification by addition of maleated PP and graphite oxide is essential for producing PP/G nanocomposite. The graphite oxide then interacts with the maleic anhydride group of the PP‐g‐MA. The structure and properties of PP/PP‐g‐MA/GO/G nanocomposites were compared by different techniques. Evidence of the nanoscale dispersion of graphite sheets within the PP were provided by wide‐angle X‐ray diffraction (WAXD) and supported by scanning electron microscopy (SEM). The high mechanical shear stresses generated by the Gelimat greatly reduced the ordering initially measured by WAXD between graphite sheets and sheet aggregates, indicating a dispersion of the graphite in the polymer to the extent that graphite particles could hardly be observed by SEM. It was found that the addition of PP‐g‐MA and GO leads to excellent dispersion of G within the PP matrix. The flow behavior of the material was also studied by means of a parallel‐plate rheometer. The addition of graphite to PP caused a drastic change in the flow behavior of PP. The thermal degradation behavior, studied using thermogravimetric analysis (TGA), showed higher thermal stability of the nanocomposite than that of pure polypropylene. The dispersion of the graphite in the resin promoted the nucleation of β crystallites in PP. The β crystallites, normally less abundant than α crystallites in pure PP, were found to constitute the dominant phase in the nanocomposite. Polym. Eng. Sci. 44:1162–1169, 2004. © 2004 Society of Plastics Engineers.
Estimation of stress for separation of two platelets
Authors: Cho Yong G. , Kamal Musa R. 
Published: July 2004

AbstractA theoretical model is proposed to describe the exfoliation process of clays in polymer melt flows. It shows that exfoliation is a function of shear rate, viscosity of the matrix, the Hamaker constant, overlapped fraction, gallery spacing, and aspect ratio. The stress ratios (i.e., stretching stress/van der Waals' stress) are significantly dependent on the orientation of the connector vector. Tactoids with more clay layers can be broken more easily. The predictions of the model appear to be in harmony with experimental observations reported in the literature. Polym. Eng. Sci. 44:1187–1195, 2004. © 2004 Society of Plastics Engineers.
Intramolecular structural relaxation in excited hetarylazole cations
Authors: Volchkov Valery V. , Hoa Gaston Hui Bon , Kossanyi Jean A. , Gromov Sergey P. , Alfimov Mikhail V. , Uzhinov Boris M. 
Published: July 2004

AbstractNeutral quinolyl‐and pyridyl‐substituted hetarylazoles and their protonated (ethylated) cations with anomalously high Stokes shifts were investigated. Fluorescence measurements at different temperatures and pressures confirmed the viscosity‐dependent activation relaxation of the latter. Fluorescence kinetic analyses at various temperatures showed that in the range 293–77 K, the k̄f values of cations increase 2–8‐fold whereas those of neutral molecules change only 0.3–1.5‐fold. The low‐temperature time‐resolved emission spectra of 1a, 1H+ and 5a were found to be consistent with the model: A→A*↔B*, where A* is the local excited planar and B* is the relaxed twisted state of the molecule. Copyright © 2004 John Wiley & Sons, Ltd.
A General Model for Prediction of Caco‐2 Cell Permeability
Authors: Nordqvist Anneli , Nilsson Jonas , Lindmark Tuulikki , Eriksson Alf , Garberg Per , Kihlén Mats 
Published: July 2004

AbstractPermeability across the epithelium is one of the major barriers to drug absorption and is one property subject to in silico prediction attempts. Prediction models provide a possibility to address absorption issues, early in drug discovery, for a large number of compounds. The aim of this study was to develop a general comprehensive partial least square projection to latent structures (PLS)‐model for prediction of Caco‐2 cell permeability using theoretically calculated descriptors suited for large virtual libraries. In order to deal with current issues of data quantity and quality the well‐established Caco‐2 cell model was used to generate accurate permeability data of apparent passive transport for a large set of structurally diverse compounds. PLS statistics was used to correlate calculated descriptors to log Papp. This new prediction model for Caco‐2 cell permeability has incorporated many different descriptor types to deal with the multivariate nature of permeability. The model is designed to classify discovery compounds as low, medium or high permeable. A good statistical model was derived (R2=0.79, Q2=0.65, n=46) using 70 descriptors including lipophilicity, hydrogen bonding, polar surface area, size and charge descriptors and some nonlinear terms. The model has been tested and proved valid on two different external test sets (n=5 and n=125 respectively). Root mean square error of prediction (RMSEP) was 0.45 for the small external test set. The model predicted 82% of the compounds in the test sets as members to the correct class, 18% were classified wrong. No low permeable compounds were classified as high permeable and only one high permeable compound was classified as low permeable. With this model it has been shown that the in silico prediction models for Caco‐2 cell permeability has taken a step closer to meet the expectations of a high throughput filter tool applied in early phase drug discovery.
Verbundbrücke Pöcking – Innovative VFT‐Träger mit Betondübeln
Authors: Schmitt Victor , Seidl Günter , Hever Marc , Zapfe Cedrik 
Published: July 2004

AbstractEine neue Bauweise für Verbundbrücken stellt die Brücke in Pöcking dar. Die seit einigen Jahren eingesetzte VFT®‐Bauweise und der Betondübel finden darin ihre Weiterentwicklung. Betondübel, die durch einen speziellen Trennschnitt des Walzträgers entstehen, verbinden das Betonfertigteil mit dem Stahl zu einem vorgefertigten Stahlverbundträger. Mit einem hohen Grad an Vereinheitlichung und Vorfertigung entsteht ein System mit wirtschaftlichem Materialeinsatz und sehr hoher Qualität. An der nun unter Verkehr stehenden Brücke in Pöcking werden statisch‐konstruktive Details und Gesichtspunkte der Herstellung näher beleuchtet.
FEM‐Berechnungen an geschweißten und gegossenen Knotenpunkten im Stahlbau
Authors: Moschner Thomas 
Published: July 2004

AbstractFiligrane Stahlkonstruktionen werden in ihrer optischen Wirkung hauptsächlich durch die Ausbildung der Knotenpunkte beeinflußt. Neben den rein wirtschaftlichen Betrachtungen sollte daher auch die Gestaltung der Konstruktion bei der Tragwerksplanung eine wichtige Rolle spielen. Anzustreben sind harmonische Übergänge zwischen den einzelnen Bauteilen ohne auftragende Elemente wie Knotenbleche oder Kopfplattenstöße etc.Da es sich bei den Knotenpunkten infolge der Konzentration von Kräften naturgemäß um die am höchsten beanspruchten Bauteile eines Tragwerkes handelt, kommt hier der Optimierung der Konstruktion hinsichtlich der statischen Ausnutzung eine große Bedeutung zu. Im Beitrag werden anhand von einigen ausgeführten Beispielen von Fachwerk‐ und Auflagerknoten die Möglichkeiten und Vorteile einer FEM‐Analyse aufgezeigt.
Schweißen unter Betriebsbeanspruchung – Werkstoffkennwerte für einen S 355 J2G3 unter Temperaturen bis 1200 °C
Authors: Peil Udo , Wichers Michael 
Published: July 2004

AbstractErhaltungs‐ und Erneuerungsmaßnahmen an bestehenden Bauwerken gewinnen zunehmend an Bedeutung. Im Zuge dieser Maßnahmen stellt sich die Frage, ob an unter Beanspruchung stehenden Konstruktionen geschweißt werden darf. Insbesondere gewinnt diese Fragestellung an Bedeutung, wenn eine Bewegung der Schweißnahtflanken während des Fügeprozesses nicht ausgeschlossen oder verhindert werden kann. Mittels schweißtechnischer Versuche sowie numerischer Simulationen soll daher die technische Machbarkeit untersucht werden. Für die Beschreibung des werkstofflichen Modells, innerhalb der numerische Simulation, ist die korrekte Annahme der Werkstoffparameter von entscheidender Bedeutung. In der nachstehenden Ausführung werden die ersten Ergebnisse zum mechanischen Verhalten eines Baustahls S 355 J2G3 bis in den Hochtemperaturbereich dargestellt.
Early Escharotomy as a Measure to Reduce Intraabdominal Hypertension in Full‐Thickness Burns of the Thoracic and Abdominal Area
Authors: Tsoutsos Demosthenis , Rodopoulou Stavroula , Keramidas Evangelos , Lagios Miltiadis , Stamatopoulos Konstantinos , Ioannovich John 
Published: July 2004

AbstractIntraabdominal hypertension (IAH) can occur in critically ill patients who have undergone surgery, who have required fluid resuscitation after intraabdominal operations, or whose abdominal surgical wound closure was under tension. If IAH remains unrelieved, it can lead to development of the abdominal compartment syndrome (ACS). The latter presents with severe cardiorespiratory and urinary symptoms such as hypotension, hypoventilation, and oliguria, and it can become fatal if it is not diagnosed early and treated properly. Moreover, IAH has been documented in the context of major burns, complicating the initial resuscitation of these patients. This study was set up to investigate the role of full‐thickness burns of the thoracic and abdominal areas in IAH during the early resuscitation period, to determine whether escharotomy could influence its levels. During the past 2 years 10 burn patients were enrolled in this study, as they fulfilled the necessary criteria: >35% total body surface area (TBSA) full‐thickness burn affecting the anterior, lateral, and most of the posterior surface of the thorax and abdomen (torso), no respiratory mechanical support at admission, and initial evaluation at another facility and transfer to our burn center 2–6 h postburn. Upon admission, the following parameters (indicative of intraabdominal hypertension, IAH) were measured: bladder pressure and gastric pressure. Also, we monitored inferior vena cava pressure, and as a routine, central venous pressure, systolic blood pressure, and arterial blood gases. Elevated intraabdominal pressure to hazardous levels was documented in all patients included in our study. The same escharotomy pattern was performed in every case, and 5–10 min after the procedure all measurements were repeated. Immediate improvement of all the parameters measured was recorded, and the alterations were found statistically significant. These results were indicative of significant relief of the elevated intraabdominal pressure in all patients after escharotomy, as well as the efficacy of the procedure. It is thus demonstrated that full‐thickness burns of the thoracic and abdominal areas can cause a significant early increase in intraabdominal pressure that, if left untreated, can lead to the development of ACS. However, the application of simple decompression techniques can offer remarkable, immediate, and often lifesaving results and is absolutely indicated for this reason, as well as for its well‐known beneficial effects on respiratory function.
Risk Management for Laboratory Automation Projects
Authors: McDowall R.D. 
Published: July 2004

This tutorial outlines some of the common risks that may be associated throughout the development and implementation of a laboratory automation project such as a laboratory information management system (LIMS) or another automation project. It presents a scheme for undertaking risk management to help assess and mitigate the degree of risk associated with each of these factors. In the case of high-risk factors, suggestions are presented to manage or help avoid the problem. Risk management is an ongoing process. It begins at the start of a project and should be reassessed at intervals throughout the project to re-evaluate existing risks and to see if any factors have changed or new ones have emerged.
Spatially‐localized correlation of dGEMRIC‐measured GAG distribution and mechanical stiffness in the human tibial plateau
Authors: Samosky Joseph T. , Burstein Deborah , Grimson W. Eric , Howe Robert , Martin Scott , Gray Martha L. 
Published: July 2004

AbstractThe concentration of glycosaminoglycan (GAG) in articular cartilage is known to be an important determinant of tissue mechanical properties based on numerous studies relating bulk GAG and mechanical properties. To date limited information exists regarding the relationship between GAG and mechanical properties on a spatially‐localized basis in intact samples of native tissue. This relation can now be explored by using delayed gadolinium‐enhanced MRI of cartilage (dGEMRIC—a recently available non‐destructive magnetic resonance imaging method for measuring glycosaminoglycan concentration) combined with non‐destructive mechanical indentation testing. In this study, three tibial plateaus from patients undergoing total knee arthroplasty were imaged by dGEMRIC. At 33–44 test locations for each tibial plateau, the load response to focal indentation was measured as an index of cartilage stiffness. Overall, a high correlation was found between the dGEMRIC index (T) and local stiffness (Pearson correlation coefficients r = 0.90, 0.64, 0.81; p < 0.0001) when the GAG at each test location was averaged over a depth of tissue comparable to that affected by the indentation. When GAG was averaged over larger depths, the correlations were generally lower. In addition, the correlations improved when the central and peripheral (submeniscal) areas of the tibial plateau were analyzed separately, suggesting that a factor other than GAG concentration is also contributing to indentation stiffness. The results demonstrate the importance of MRI in yielding spatial localization of GAG concentration in the evaluation of cartilage mechanical properties when heterogeneous samples are involved and suggest the possibility that the evaluation of mechanical properties may be improved further by adding other MRI parameters sensitive to the collagen component of cartilage. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.