bluuebunny/crossref_metadata_2025 huggingface dataset:
Early and late rate of force development: differential adaptive responses to resistance training?
Authors: Andersen L. L. , Andersen J. L. , Zebis M. K. , Aagaard P.
Published: September 2009

The objective of this study is to investigate the potentially opposing influence of qualitative and quantitative muscular adaptations in response to high‐intensity resistance training on contractile rate of force development (RFD) in the early (<100 ms) and later phases (>200 ms) of rising muscle force. Fifteen healthy young males participated in a 14‐week resistance training intervention for the lower body and 10 matched subjects participated as controls. Maximal muscle strength (MVC) and RFD were measured during maximal voluntary isometric contraction of the quadriceps femoris muscle. Muscle biopsies were obtained from the vastus lateralis. The main findings were that RFD in the late phase of rising muscle force increased in response to resistance training whereas early RFD remained unchanged and early relative RFD (i.e., RFD/MVC) decreased. Quantitatively, muscle fiber cross‐sectional area and MVC increased whereas, qualitatively, the relative proportion of type IIX muscle fibers decreased. Multiple regression analysis showed that while increased MVC positively influenced both early and late RFD, decreased‐type IIX negatively influenced early RFD only. In conclusion, early and late RFD responded differently to high‐intensity resistance training due to differential influences of qualitative and quantitative muscular adaptations on early and later phases of rising muscle force.
Corticosteroid injections, eccentric decline squat training and heavy slow resistance training in patellar tendinopathy
Authors: Kongsgaard M. , Kovanen V. , Aagaard P. , Doessing S. , Hansen P. , Laursen A. H. , Kaldau N. C. , Kjaer M. , Magnusson S. P.
Published: September 2009

A randomized‐controlled single‐blind trial was conducted to investigate the clinical, structural and functional effects of peritendinous corticosteroid injections (CORT), eccentric decline squat training (ECC) and heavy slow resistance training (HSR) in patellar tendinopathy. Thirty‐nine male patients were randomized to CORT, ECC or HSR for 12 weeks. We assessed function and symptoms (VISA‐p questionnaire), tendon pain during activity (VAS), treatment satisfaction, tendon swelling, tendon vascularization, tendon mechanical properties and collagen crosslink properties. Assessments were made at 0 weeks, 12 weeks and at follow‐up (half‐year). All groups improved in VISA‐p and VAS from 0 to 12 weeks (P<0.05). VISA‐p and VAS improvements were maintained at follow‐up in ECC and HSR but deteriorated in CORT (P<0.05). In CORT and HSR, tendon swelling decreased (−13±9% and −12±13%,P<0.05) and so did vascularization (−52±49% and −45±23%,P<0.01) at 12 weeks. Tendon mechanical properties were similar in healthy and injured tendons and were unaffected by treatment. HSR yielded an elevated collagen network turnover. At the half‐year follow‐up, treatment satisfaction differed between groups, with HSR being most satisfied. Conclusively, CORT has good short‐term but poor long‐term clinical effects, in patellar tendinopathy. HSR has good short‐ and long‐term clinical effects accompanied by pathology improvement and increased collagen turnover.
Regulation of Insulin Secretion by Phosphatidylinositol‐4,5‐Bisphosphate
Authors: Tomas Alejandra , Yermen Barbara , Regazzi Romano , Pessin Jeffrey E. , Halban Philippe A.
Published: September 2009

The role of PIP2 in pancreatic beta cell function was examined here using the beta cell line MIN6B1. Blocking PIP2 with PH‐PLC‐GFP or PIP5KIγ RNAi did not impact on glucose‐stimulated secretion although susceptibility to apoptosis was increased. Over‐expression of PIP5KIγ improved cell survival and inhibited secretion with accumulation of endocytic vacuoles containing F‐actin, PIP2, transferrin receptor, caveolin 1, Arf6 and the insulin granule membrane protein phogrin but not insulin. Expression of constitutively active Arf6 Q67L also resulted in vacuole formation and inhibition of secretion, which was reversed by PH‐PLC‐GFP co‐expression. PIP2 co‐localized with gelsolin and F‐actin, and gelsolin co‐expression partially reversed the secretory defect of PIP5KIγ‐over‐expressing cells. RhoA/ROCK inhibition increased actin depolymerization and secretion, which was prevented by over‐expressing PIP5KIγ, while blocking PIP2 reduced constitutively active RhoA V14‐induced F‐actin polymerization. In conclusion, although PIP2 plays a pro‐survival role in MIN6B1 cells, excessive PIP2 production because of PIP5KIγ over‐expression inhibits secretion because of both a defective Arf6/PIP5KIγ‐dependent endocytic recycling of secretory membrane and secretory membrane components such as phogrin and the RhoA/ROCK/PIP5KIγ‐dependent perturbation of F‐actin cytoskeleton remodelling.
Magnetic Resonance Imaging of Pulmonary Diseases
Authors: Ley‐Zaporozhan J. , Kauczor H‐U. , Ley S.
Published: September 2009

Magnetic Resonance Imaging (MRI) of the chest and especially the lung is more and more accepted as a valuable additional imaging modality for several pulmonary diseases. Magnetic Resonance Imaging allows for combined morphological and functional imaging and therefore elucidates perfectly the effect of parenchymal changes and destruction onto pulmonary perfusion and ventilation. This overview presents the current status for the application of pulmonary MRI in chronic obstructive pulmonary disease as well as infectious and neoplastic diseases.
Geostatistical Modeling of a Heterogeneous Site Bordering the Venice Lagoon, Italy
Authors: Trevisani Sebastiano , Fabbri Paolo
Published: September 2009

Geostatistical methods are well suited for analyzing the local and spatial uncertainties that accompany the modeling of highly heterogeneous three‐dimensional (3D) geological architectures. The spatial modeling of 3D hydrogeological architectures is crucial for polluted site characterization, in regards to both groundwater modeling and planning remediation procedures. From this perspective, the polluted site of Porto Marghera, located on the periphery of the Venice lagoon, represents an interesting example. For this site, the available dense spatial sampling network, with 769 boreholes over an area of 6 km2, allows us to evaluate the high geological heterogeneity by means of indicator kriging and sequential indicator simulation. We show that geostatistical methodologies and ad hoc post processing of geostatistical analysis results allow us to effectively analyze the high hydrogeological heterogeneity of the studied site.
Groundwater Modeling in Integrated Water Resources Management—Visions for 2020
Authors: Refsgaard Jens Christian , Højberg Anker Lajer , Møller Ingelise , Hansen Martin , Søndergaard Verner
Published: September 2009

Groundwater modeling is undergoing a change from traditional stand‐alone studies toward being an integrated part of holistic water resources management procedures. This is illustrated by the development in Denmark, where comprehensive national databases for geologic borehole data, groundwater‐related geophysical data, geologic models, as well as a national groundwater‐surface water model have been established and integrated to support water management. This has enhanced the benefits of using groundwater models. Based on insight gained from this Danish experience, a scientifically realistic scenario for the use of groundwater modeling in 2020 has been developed, in which groundwater models will be a part of sophisticated databases and modeling systems. The databases and numerical models will be seamlessly integrated, and the tasks of monitoring and modeling will be merged. Numerical models for atmospheric, surface water, and groundwater processes will be coupled in one integrated modeling system that can operate at a wide range of spatial scales. Furthermore, the management systems will be constructed with a focus on building credibility of model and data use among all stakeholders and on facilitating a learning process whereby data and models, as well as stakeholders' understanding of the system, are updated to currently available information. The key scientific challenges for achieving this are (1) developing new methodologies for integration of statistical and qualitative uncertainty; (2) mapping geological heterogeneity and developing scaling methodologies; (3) developing coupled model codes; and (4) developing integrated information systems, including quality assurance and uncertainty information that facilitate active stakeholder involvement and learning.
A Thermodynamic Approach to the Affinity Optimization of Drug Candidates
Authors: Freire Ernesto
Published: September 2009

High throughput screening and other techniques commonly used to identify lead candidates for drug development usually yield compounds with binding affinities to their intended targets in the mid‐micromolar range. The affinity of these molecules needs to be improved by several orders of magnitude before they become viable drug candidates. Traditionally, this task has been accomplished by establishing structure activity relationships to guide chemical modifications and improve the binding affinity of the compounds. As the binding affinity is a function of two quantities, the binding enthalpy and the binding entropy, it is evident that a more efficient optimization would be accomplished if both quantities were considered and improved simultaneously. Here, an optimization algorithm based upon enthalpic and entropic information generated by Isothermal Titration Calorimetry is presented.
Analysis of Flavonoid‐Based Pharmacophores that Inhibit Aggrecanases (ADAMTS‐4 and ADAMTS‐5) and Matrix Metalloproteinases Through the Use of Topologically Constrained Peptide Substrates
Authors: Cudic Mare , Burstein Gayle D. , Fields Gregg B. , Lauer‐Fields Janelle
Published: September 2009

Polyphenolic natural products from green tea and red wine have been identified as metalloproteinase inhibitors. Members from the flavonoid and stilbene families found to possess metalloproteinase inhibitory activities include (−)‐epigallocatechin gallate, (−)‐epicatechin gallate and piceatannol, but their minimally active pharmacophores have not been evaluated. The present study has examined compounds that are structural components of or structurally related to (−)‐epigallocatechin gallate, (−)‐epicatechin gallate and piceatannol for inhibition of aggrecanases and four representative matrix metalloproteinases. Piceatannol and pyrogallol were found to inhibit all aggrecanases and matrix metalloproteinases studied, indicating a crucial reliance on multiple hydroxyl groups for (−)‐epigallocatechin gallate, (−)‐epicatechin gallate and piceatannol activity. Differences in Ki values for pyrogallol as determined with two structurally distinct substrates indicated the likelihood that this compound binds in a non‐competitive modality. Further analysis showed that pyrogallol acts as an exosite inhibitor, consistent with the action of (−)‐epigallocatechin gallate. In contrast, piceatannol was shown to be a competitive binding inhibitor and showed no differences in apparent Ki values as determined by distinct substrates, illustrating the benefits of using two structurally distinct substrates to assist the analysis of protease inhibitors. The compounds identified here could be utilized to develop novel metalloproteinase probes or as fragment components of more active inhibitors.
Three‐Dimensional Protein–Ligand Interaction Scaling of Two‐Dimensional Fingerprints
Authors: Tan Lu , Vogt Martin , Bajorath Jürgen
Published: September 2009

We introduce a computational scaling methodology that utilizes protein–ligand interaction information extracted from complex crystal structures to enrich similarity searching using structural fingerprints with compound class‐specific information. Scaling factors are derived to emphasize fingerprint bit positions that result from interacting fragments of bound ligands and correspond to frequently occurring structural features. Through interaction‐based scaling, this information is transferred to standard fingerprints of multiple reference compounds. In systematic search calculations, fingerprints scaled on the basis of three‐dimensional information are found to produce higher recall rates of active compounds than alternative types of scaled and non‐scaled fingerprints.
Utility of hematologic and volume, conductivity, and scatter parameters from umbilical cord blood in predicting chorioamnionitis
Authors: LEE J. C. , AHERN T. P. , CHAVES F. P. , QUILLEN K.
Published: September 2009

We evaluated the utility of routine hematologic parameters and volume, conductivity, and scatter (VCS) parameters from umbilical cord blood in predicting pathologically confirmed chorioamnionitis. Chorioamnionitis is strongly associated with early neonatal sepsis and is the major in utero source of infectious exposure. We prospectively identified mothers who had placenta submitted for pathology and subsequently identified corresponding neonate cord blood sent for routine blood typing (n = 99). Cord blood was then sent for routine complete blood count with differential (CBCD). Among the same neonates, we retrospectively identified those who had peripheral blood sent for CBCD. We collected VCS parameter data, which are used in determining an automated leukocyte differential, from our hematology analyzer. Routine hematologic as well as VCS parameters from both cord and peripheral blood were then evaluated for predicting pathologically confirmed chorioamnionitis. In the study population, the absolute neutrophil count, neutrophil differential, mean neutrophil conductivity, and neutrophil conductivity standard deviation (SD) from cord blood showed the best predictive ability for chorioamnionitis. Among neonates with intrapartum antibiotic prophylaxis exposure, the band differential, immature neutrophil precursor differential, and neutrophil conductivity SD showed the best predictive ability. Lastly, among the neonates who had peripheral blood CBCD, the band differential and immature neutrophil precursor differential showed the best predictive ability. Overall, the peripheral blood band differential and immature neutrophil precursor differential showed better specificity and positive predictive value for chorioamnionitis than the cord blood parameters. However, the cord blood absolute neutrophil count, neutrophil differential, and mean neutrophil conductivity showed better negative predictive value. Cord blood can be a valuable source of diagnostic laboratory testing for neonates because of their small blood volume. This is the first study demonstrating that routine hematologic and VCS parameters from cord blood can be used to predict pathologically confirmed chorioamnionitis.
Facile fingerstick insulin analysis: Application to monitoring postprandial insulin responses to snack foods
Authors: MEGDAL Peter A. , SIEMSEN Daniel , SANDS David , DRATZ Edward A. , HANDELMAN Garry J.
Published: September 2009

Background: Energy intake from snacks has been increasing in the American diet, but insulin and glucose responses to foods are generally reported for meal‐sized portions (800–1200 kJ). Established methods for insulin determination routinely use indwelling catheters and radioimmunoassay (RIA). The aim of the present study was to develop a more facile method, collecting fingerstick blood samples and measuring insulin with precise ELISA, and then applying this method to determine responses to snack‐sized food portions.

Methods: Six healthy, fasting adult volunteers consumed seven different snack foods on separate days, containing approximately 400 kJ/portion. Insulin was measured by ELISA and glucose was measured with the hexokinase procedure in samples collected by fingerstick at 0, 30, and 60 min after consumption of the snack food.

Results: A portion of doughnut (half a glazed doughnut) led to marked changes in insulin and glucose; skim milk, an apple, and oatmeal changed insulin significantly; wrinkled peas resulted in a lower glucose response than smooth peas; and walnuts led to non‐significant changes in both insulin and glucose over a 60‐min period.

Conclusions: The fingerstick sampling and insulin measurement procedure is simple, economical, and more precise than established RIA. The method can be applied to children and adults to monitor insulin responses following food consumption, as well as during therapeutic assessments or intervention trials. Public health advisories regarding snacks that minimize increases in insulin are desirable for individuals trying to reduce or maintain their weight, because elevated insulin stimulates carbohydrate conversion to fat and suppresses the mobilization of stored triglycerides for energy generation.
Imaging of ovarian teratomas: Appearances and complications
Authors: Choudhary S , Fasih N , Innes M Mc , Marginean C
Published: September 2009

Ovarian teratomas are the most common germ cell neoplasm. Subtypes of teratoma include mature cystic, immature and the monodermal teratomas. The benign cystic teratoma shows typical imaging manifestations and can be complicated by torsion, rupture and uncommonly malignant degeneration. Uncommon subtypes of teratomas include the immature, which is usually malignant at diagnosis. The growing teratoma syndrome is an uncommon complication reported in patients treated for immature teratomas. The monodermal teratomas which include the struma ovarii may also have specific imaging characteristics that should be recognised on imaging. This paper aims to provide a comprehensive review describing the spectrum of imaging findings of these ovarian tumours and associated complications
Acute megakaryoblastic leukemia in a German Shepherd dog
Authors: Ameri Mehrdad , Wilkerson Melinda J. , Stockham Steven L. , Almes Kelli M. , Patton Kristin M. , Jackson Tracey
Published: September 2009

Abstract:An 11‐year‐old spayed‐female German Shepherd dog was presented to the Veterinary Medical Teaching Hospital at Kansas State University with a history of weight loss, anorexia, depression, and lethargy for 2–3 weeks. Radiographic examination revealed a mass in the spleen and several round radiodense foci in the liver. CBC results included normocytic normochromic anemia, marked thrombocytopenia, and low numbers of neoplastic cells that frequently had cytoplasmic projections or blebs. A bone marrow aspirate contained about 80% neoplastic megakaryoblasts with the same microscopic features as those observed in peripheral blood. Using flow cytometry, cells of large size were identified in peripheral blood that expressed CD41/61, CD45, CD61, and CD62P (P‐selectin) and were negative for markers of T cells, B cells, monocyte/macrophages, and dendritic cells. Because of the poor prognosis, euthanasia and subsequently necropsy were performed. On histopathologic examination, neoplastic megakaryoblasts were identified in spleen, liver, mesenteric lymph node, and the pulmonary vasculature. Using immunohistochemistry, the neoplastic megakaryoblasts weakly expressed von Willebrand factor. Based on microscopic and immunophenotypic findings, a diagnosis of acute megakaryoblastic leukemia (AMegL) was made. To our knowledge, this is the first report of AMegL in a domestic animal in which immunophenotyping by flow cytometry and a panel of antibodies against CD41/61, CD61, and CD62P were used to support the diagnosis.
Appearance of granulated cells in blood films stained by automated aqueous versus methanolic Romanowsky methods
Authors: Allison Robin W. , Velguth Karen E.
Published: September 2009

Background: Romanowsky stains are used routinely by veterinary clinical pathology laboratories for cytologic and blood film evaluations. Automated stainers are available for both aqueous and methanolic Romanowsky stains. Mast cell granules and canine distemper virus inclusions are known to stain differently by these 2 methods, but we have noticed differences in the staining characteristics of other granulated cells.

Objective: The aim of this study was to investigate and document the variable appearance of basophils and large granular lymphocytes in blood films stained using aqueous and methanolic Romanowsky methods.

Methods: Cytologic preparations from 1 canine mast cell tumor and blood films from 8 dogs, 1 cat, 1 rabbit, and 1 ostrich were stained using an automated aqueous stain (Aerospray 7120, with and without a predip fixative) and an automated methanolic stain (Hematek). Staining quality and intensity of the cytoplasmic granules in mast cells, basophils, and large granular lymphocytes was evaluated subjectively.

Results: Cytoplasmic granules of mast cells, basophils, and large granular lymphocytes stained poorly or not at all with the automated aqueous stain but stained prominently and were readily identified with the automated methanolic stain. Use of the predip fixative with the Aerospray method improved the visibility of basophil granules but not mast cell granules, and had a variable affect on the visibility of granules in large granular lymphocytes.

Conclusion: Clinical pathologists should be aware of the staining methodology used on the slides they evaluate to avoid incorrect interpretation of granulated cell populations.
Burma's Economy 2009: Disaster, Recovery . . . and Reform?
Authors: Turnell Sean , Bradford Wylie , Vicary Alison
Published: September 2009

This article analyzes the current state of Burma's economy and the possibilities for reform. The serial underperformer of the region, Burma's emergence in recent years as a significant regional exporter of natural gas has created the potential for economic progress. Thus far this potential has yet to be realized, however, in a country whose economic policy‐making framework remains one of dirigisme. In 2008, Burma's economy was dealt a further blow when the country was struck by Cyclone Nargis. This article begins by examining the economic impact of Nargis before moving on to examine the longer‐term reforms required to restore prosperity to this all‐too‐often forgotten country.
Lessons of Defeat: A Comparison of Taiwanese Ruling Parties' Responses to Electoral Defeat
Authors: Fell Dafydd
Published: September 2009

In the last decade Taiwan has witnessed two changes in ruling party through elections. First, in 2000 the Kuomintang (KMT) was defeated by the Democratic Progressive Party (DPP) in the presidential election. Then after eight years of DPP rule, the KMT regained control of central government in the parliamentary and presidential elections of 2008. This study compares the two parties' reactions to disastrous defeat. Have the parties learned the lessons of defeat by responding with rational reforms? In addition to this comparison, I assess the effectiveness of the KMT's reforms in contributing to its return to power. Although the DPP's fall from power is only just over a year old, this study can offer some insights into whether one can expect the DPP to recover sufficiently to offer a serious political challenge to KMT domination.
Intellectual Property Rights and Foreign Investment: The Political Economy of Taiwan's Technology‐Intensive Foreign Direct Investment
Authors: Fuller Douglas B.
Published: September 2009

This article employs Taiwan's institutions for intellectual property rights (IPR) to explain two aspects of Taiwan's foreign direct investment behavior: the location of offshore sites for Taiwanese research and development, and investment by Taiwanese venture capitalists. The article first describes the evolution of Taiwan's informal IPR practices that differ from the ideal typical IPR regime supposedly required for economies as technologically sophisticated as Taiwan's. Essentially, Taiwan has developed informal practices to protect corporate IPR that are centered on internal corporate mechanisms rather than external formal legal mechanisms. Relying on these informal practices, the article discusses how Taiwan has invested in technology‐intensive activities in locations where IPR protection is weak. This behavior stands in sharp contrast to the behavior of multinationals from the Organisation for Economic Co‐operation and Development countries.
What Role Can Trust Play? Conflicts and Trust‐Building in East Asia
Authors: Reinke de Buitrago Sybille
Published: September 2009

The article explores the concept of trust and its relevance to conflicts and their solution. In conflicts, threat perceptions are a driving force for action. Trust fulfills a psychological need and acts as a stabilizer in human interaction. It is important in efforts of building a cooperative environment and peaceful relations as well as in situations of conflict. Different kinds of trust exist, but all involve some risk‐taking. Structural conditions and institutional mechanisms conducive to trust‐building, education for trust, and confidence‐building measures can reduce uncertainty and allow actors to trust one another more. The article applies the issue of trust to a case study of East Asia. The East Asian region is in great political movement with various potential and actual conflicts. The significant role that trust and trust‐building can play in reducing tension and fostering dialogue and cooperation in this region is elaborated.
How to Negotiate with North Korea
Authors: Yi Yurim
Published: September 2009

This article evaluates the February 13th agreement at the 2007 six‐party talks that officially is known as “Initial Actions for the Implementation of the Joint Statement.” The agreement's effectiveness is evaluated based on the negotiating and behavioral styles of both Washington and Pyongyang. This article shows that in the pre‐negotiation phase, Washington's Graduated Reciprocation in Tension‐reduction strategies were more effective than the well‐known Tit‐for‐Tat strategies to induce North Korea to engage in the six‐party talks. I also show that principled negotiation strategies were effectively applied, and that the weak Best Alternative to a Negotiated Agreement led the two countries to reach an agreement. Finally, this article demonstrates that several strategic provisions were added in the post‐negotiation phase in order to secure the fulfillment of the agreement.
An Efficient Method for Crack Identification in Simply Supported Euler–Bernoulli Beams
Authors: Rubio L.
Published: September 2009

An effective crack identification procedure has been developed based on the dynamic behavior of a Euler–Bernoulli cracked beam. It is very well known that the presence of a crack in a structure produces a change in its frequency response that can be used to determine the crack properties (position and size) solving what is called an inverse problem. In this work, such an inverse problem has been solved by the use of the classical optimization technique of minimizing the least square criterion applied to the closed-form expression for the frequencies obtained through the perturbation method. The advantage of this method with respect to the ones derived previously is that the knowledge of the material and its properties (Young’s modulus and mass density) is not necessary, not even the behavior of the uncracked element. The methodology has been successfully applied to a simply supported Euler–Bernoulli beam.
Modeling of Fillets in Thin-Walled Beams Using Shell/Plate and Beam Finite Elements
Authors: He K. , Zhu W. D.
Published: September 2009

Fillets are commonly found in thin-walled beams. Ignoring the presence of a fillet in a finite element (FE) model of a thin-walled beam can significantly change the natural frequencies and mode shapes of the structure. A large number of solid elements are required to accurately represent the shape and the stiffness of a fillet in a FE model, which makes the size of the FE model unnecessarily large for global dynamic and static analyses. In this work the equivalent stiffness effects of a fillet in a thin-walled beam are decomposed into in-plane and out-of-plane effects. The in-plane effects of a fillet are analyzed using the wide-beam and curved-beam theories, and the out-of-plane effects of the fillet are analyzed by modeling the whole fillet section as a slender bar with an irregular cross section. A simple shell/plate and beam element model is developed to capture the in-plane and out-of-plane effects of a fillet on a thin-walled beam. The natural frequencies and mode shapes of a thin-walled L-shaped beam specimen calculated using the new methodology are compared with its experimental results for 28 modes. The maximum error between the calculated and measured natural frequencies for all the modes is less than 2%, and the associated modal assurance criterion values are all over 95%. The methodology is also applied to other thin-walled beams, and excellent agreement is achieved between the natural frequencies from the shell/plate and beam element models and those from the solid element models. While the shell/plate and beam element models provide the same level of accuracy as the intensive solid element models, the degrees of freedom of the shell/plate and beam element models of the thin-walled beams are only about 10% or less of those of the solid element models.
Nondispersive Acoustic Wave Reflection on Time Reversal Mirrors
Authors: Hillion Pierre
Published: September 2009

Using an integral equation approach, we investigate the reflection of focus wave modes on conventional and time reversal mirrors when the total field, incident plus reflected, satisfies on these mirrors the Neumann boundary condition. It is also shown that the form of the incident pulse as a function of time has a strong effect on the behavior of time reversal mirrors.
Torsional Vibration Suppression by Roller Type Centrifugal Vibration Absorbers
Authors: Ishida Yukio , Inoue Tsuyoshi , Fukami Tomohiko , Ueda Motohiko
Published: September 2009

Centrifugal pendulum vibration absorbers (CPVA) have been used for a long time as a method to suppress torsional vibration. Recently, roller type CPVA, that has a similar characteristic but simpler structure, have been investigated and started to be used in some automobile engines. However, only the linear dynamical characteristics of the roller type CPVA have been focused, and the influence of the nonlinearity affecting on vibration suppression has not been clarified. This study mainly focuses on the explanation of nonlinear dynamical characteristics of roller type CPVA. Especially, it clarifies the importance of consideration of nonlinearity in the design of the roller type CPVA, both theoretically and experimentally. Furthermore, the difference between the pendulum type CPVA and roller type CPVA are discussed from the viewpoint of the effect of vibration suppression.
On Veering of Eigenvalue Loci
Authors: Stephen N. G.
Published: September 2009

Eigenvalue veering is studied in the context of two simple oscillators coupled by a (presumed weak) spring, variants of which have been considered by several authors. The concept of a center of veering is introduced, leading to a coordinate translation; a subsequent coordinate rotation, dependent on the degree of asymmetry of the system, reduces the frequency equation to a standard north-south opening hyperbola. Thus veering occurs even when coupling is strong, and may be characterized by these coordinate transformations and geometric features of the hyperbola, rather than eigenvalue and eigenvector derivatives.
Triple Stance Phase Displacement Analysis With Redundant and Nonredundant Sensing in a Novel Three-Legged Mobile Robot Using Parallel Kinematics
Authors: Ren Ping , Hong Dennis
Published: September 2009

This paper presents the forward and inverse displacement analysis of a novel three-legged walking robot Self-excited Tripedal Dynamic Experimental Robot (STriDER) in its triple stance phase. STriDER utilizes the concept of passive dynamic locomotion to walk, but when all three feet of the robot are on the ground, the kinematic configuration of the robot behaves like an in-parallel manipulator. To plan and control its change in posture, the kinematics of its forward and inverse displacement must be analyzed. First, the concept of this novel walking robot and its unique tripedal gait are discussed, followed by the overall kinematic configuration and definitions of its coordinate frames. When all three feet of the robot are on the ground, by assuming there is no slipping at the feet, each foot contact point is treated as a passive spherical joint. Kinematic analysis methods for in-parallel manipulators are briefly reviewed and adopted for the forward and inverse displacement analysis for this mobile robot. Both loop-closure equations based on geometric constraints and the intersection of the loci of the feet are utilized to solve the forward displacement problem. Analytical solutions are identified and discussed in the cases of redundant sensing with displacement information from nine, eight, and seven joint angle sensors. For the nonredundant sensing case using information from six joint angle sensors, it is shown that analytical solutions can only be obtained when the displacement information is available from unequally distributed joint angle sensors among the three legs. As for the case when joint angle sensors are equally distributed among the three legs, it will result in a 16th-order polynomial with respect to a single variable, and closed-form forward displacement solutions can be obtained. Finally, results from the simulations are presented for both inverse displacement analysis and the nonredundant sensing case with equally distributed joint angle sensors. It is found that at most 16 forward displacement solutions exist if displacement information from two joint angle sensors per leg are used and one is not used.
Workspace Analysis of a Three DOF Cable-Driven Mechanism
Authors: Alikhani Alireza , Behzadipour Saeed , Vanini S. Ali Sadough , Alasty Aria
Published: September 2009

A cable-driven mechanism based on the idea of BetaBot (2005, “A New Cable-Based Parallel Robot With Three Degrees of Freedom,” Multibody Syst. Dyn., 13, pp. 371–383) is analyzed and geometrical description of its workspace boundary is found. In this mechanism, the cable arrangement eliminates the rotational motions leaving the moving platform with three translational motions. The mechanism has potentials for large scale manipulation and robotics in harsh environments. A detailed analysis of the tensionable workspace of the mechanism is presented. The mechanism, in a tensionable position, can develop tensile forces in all cables to maintain its rigidity under arbitrary external loading. A set of conditions on the geometry of the mechanism is proposed for which the tensionable workspace becomes a well defined convex polyhedron. The geometrical shape of the workspace is then described and the tensionability of the mechanism inside the workspace is proved. The proof is quite general and based on a geometrical approach.
Comparison of Various Dynamic Balancing Principles Regarding Additional Mass and Additional Inertia
Authors: van der Wijk Volkert , Herder Just L. , Demeulenaere Bram
Published: September 2009

The major disadvantage of existing dynamic balancing principles is that a considerable amount of mass and inertia is added to the system. The objectives of this article are to summarize, to compare, and to evaluate existing complete balancing principles regarding the addition of mass and the addition of inertia and to introduce a normalized indicator to judge the balancing performance regarding the addition of mass and inertia. The balancing principles are obtained from a survey of literature and applied to a double pendulum for comparison, both analytically and numerically. The results show that the duplicate mechanisms principle has the least addition of mass and also a low addition of inertia and is most advantageous for low-mass and low-inertia dynamic balancing if available space is not a limiting factor. Applying countermasses and separate counter-rotations with or without an idler loop both increase the mass and inertia considerably, with idler loop being the better of the two. Using the force-balancing countermasses also as moment-balancing counterinertias leads to significantly less mass addition as compared with the use of separate counter-rotations. For low transmission ratios, also the addition of inertia then is smaller.
A Screw Theory Approach for the Conceptual Design of Flexible Joints for Compliant Mechanisms
Authors: Su Hai-Jun , Dorozhkin Denis V. , Vance Judy M.
Published: September 2009

This paper presents a screw theory based approach for the analysis and synthesis of flexible joints using wire and sheet flexures. The focus is on designing flexure systems that have a simple geometry, i.e., a parallel constraint pattern. We provide a systematic formulation of the constraint-based approach, which has been mainly developed by precision engineering experts in designing precision machines. The two fundamental concepts in the constraint-based approach, constraint and freedom, can be represented mathematically by a wrench and a twist in screw theory. For example, an ideal wire flexure applies a translational constraint, which can be described by a wrench of pure force. As a result, the design rules of the constraint-based approach can be systematically formulated in the format of screws and screw systems. Two major problems in compliant mechanism design, constraint pattern analysis, and constraint pattern design are discussed with examples in details. Lastly, a case study is provided to demonstrate the application of this approach to the design of compliant prismatic joints. This innovative method paves the way for introducing computational techniques into the constraint-based approach for the synthesis and analysis of compliant mechanisms.
Decoupled and Homokinetic Transmission of Rotational Motion via Constant-Velocity Joints in Closed-Chain Orientational Manipulators
Authors: Carricato Marco
Published: September 2009

This paper presents novel 2DOF and 3DOF closed-chain orientational manipulators, whose end-effector motion is actuated in a decoupled and homokinetic way by frame-located motors via holonomic transmissions based on constant-velocity couplings. The functioning of these couplings is investigated and the conditions applying for homokinetic transmission to be preserved during simultaneous motor drive are revealed and implemented. As a result, decoupled and configuration-independent relations between the motor rates and the time-derivatives of the variables describing the end-effector orientation are achieved. The attainment of analogous relations between the motor speeds and the components of the end-effector angular velocity is conversely proven to be unfeasible. The problem of singularities is furthermore examined, showing that input-output homokinesis is not a sufficient condition for a globally uniform kinetostatic behavior of the mechanism, which may, indeed, possibly reach uncertainty singular configurations. The connecting chains of the most typical constant-velocity couplings are analyzed, in order to obtain analytical expressions for the functions on which such singularities depend. The influence of design parameters is accordingly inspected. The results are valuable for the type and dimension synthesis of closed-chain wrists free from direct kinematic singularities, and characterized by simple kinematics and regular input-output kinetostatic relations.
New algorithm to simulate organ movement and deformation for four‐dimensional dose calculation based on a three‐dimensional CT and fluoroscopy of the thorax
Authors: Miyabe Yuki , Narita Yuichiro , Mizowaki Takashi , Matsuo Yukinori , Takayama Kenji , Takahashi Kunio , Kaneko Shuji , Kawada Noriyuki , Maruhashi Akira , Hiraoka Masahiro
Published: September 2009

Purpose:

The aim of this study was to develop a 4D‐modeling algorithm, designated “,” to simulate organ movement and deformation for 4D dose calculation without the need for 4D‐CT or deformable image registration and to assess the validity of this algorithm.

Methods:

This algorithm virtually creates 4D‐CT images by deforming static 3D‐CT data according to a typical motion model and motion data at multiple observation points collected via fluoroscopy. A typical motion model intended for patients with lung tumors immobilized with a vacuum pillow inside a stereotactic body frame was constructed. The geometric accuracy of virtual 4D‐CT images created using this algorithm was evaluated in eight patients by comparing the simulated results with actual 4D‐CT images in terms of visual assessment, landmark analysis, and comparison of the radial distance from the tumor centroid to the body or lung surface.

Results:

The average accuracy for all patients, as determined via landmark analysis, was, very similar to results obtained through 4D‐CT and deformable image registrations. Error in the radial distance from the tumor centroid to the body or lung surface was generally within 1.0 or 2.0 mm, respectively, in virtual versus actual 4D‐CT images. Therefore, it is assumed that these geometric errors would have only negligible effects on dose calculation.

Conclusions:

4D modeling of the thorax utilizing the algorithm shows acceptable accuracy and is more suited for routine clinical use in terms of processing time than conventional 4D‐CT and deformable image registration. The algorithm may be useful for simulating dose distribution for advanced beam delivery techniques, such as real‐time tumor tracking irradiation and adaptive radiation therapy.
Modeling and interpretation of the bioelectrical impedance signal for the determination of the local arterial stiffness
Authors: Collette Mathieu , Leftheriotis Georges , Humeau Anne
Published: September 2009

Purpose:

Stiffness of the large arteries (e.g., aorta) plays an important role in the pathogenesis of cardiovascular diseases. To date, the reference method for the determination of regional arterial stiffness is the measurement of the carotid‐femoral pulse wave velocity (PWV) by tonometric techniques. However, this method suffers from several drawbacks and it remains limited in clinical routine.

Methods:

In the present study, the authors propose a new method based on the analysis of bioelectrical impedance (BI) signals for the determination of the local arterial stiffness. They show, from a theoretical model, a novel interpretation of the BI signals and they establish the relationship between the variations in the BI signal and the kinetic energy of the blood flow in large arteries. From this model, BI signals are simulated in the thigh and compared to experimental BI data. Finally, from the model, they propose a new index related to the properties of the large artery for the determination of the local arterial stiffness.

Results:

The results show a good correlation between the simulated and the experimental BI signals. The same variations for both of them with different characteristics for rigid and elastic arteries can be observed. The measurement of the index on 20 subjects at rest (mean age of ) for the determination of the local aortic stiffness presents a significant correlation with the PWV reference method (; with the Spearman correlation coefficient and ).

Conclusions:

All the results suggest that the theoretical model and the new index could give a reliable estimate of local arterial stiffness.
Patient‐specific quality assurance method for VMAT treatment delivery
Authors: Schreibmann Eduard , Dhabaan Anees , Elder Eric , Fox Tim
Published: September 2009

Volumetric modulated arc therapy (VMAT) is a system for intensity‐modulated radiotherapy treatment delivery that achieves high dose conformality by optimizing the dose rate, gantry speed, and the leaf positions of the dynamic multileaf collimator (DMLC). The aim of this work is to present a practical approach for patient‐specific volumetric reconstruction of the dose delivered of a VMAT treatment using the DMLC and treatment controller log (Dynalog) files. The accuracy of VMAT delivery was analyzed for five prostate patients. For each patient, a clinical treatment was delivered and values recorded in the log files for the gantry angle, dose rate, and leaf positions were converted to a new DICOM‐compliant plan using a custom‐developed software system. The plan was imported in a treatment planning system and the dose distribution was recreated on the original CT by simply recomputing the dose. Using the standard evaluation tools, it is straightforward to assess if reconstructed dose meets clinical endpoints, as well as to compare side‐by‐side reconstructed and original plans. The study showed that log files can be directly used for dose reconstruction without resorting to phantom measurements or setups. In all cases, analysis of the leaf positions showed a maximum error of (mean of ). Gantry angle deviation was less than 1° and the total MU was within 0.5 from the planned value. Differences between the reconstructed and the intended dose matrices were less than 1.46% for all cases. Measurements using the MATRIXX system in a phantom were used to validate the dosimetric accuracy of the proposed method, with an agreement of at least 96% in all pixels as measured using the gamma index. The methodology provides a volumetric evaluation of the dose reconstructed by VMAT plans which is easily achieved by automated analysis of Dynalog files without additional measurements or phantom setups. This process provides a valuable platform for adaptive therapy in the future.
Modeling acute and chronic hypoxia using serial images of PET
Authors: Wang Kelin , Yorke Ellen , Nehmeh Sadek A. , Humm John L. , Ling C. Clifton
Published: September 2009

Purpose:

Two types of tumor hypoxia most likely exist in human cancers: Chronic hypoxia due to the paucity of blood capillaries and acute hypoxia due to temporary shutdown of microvasculatures or fluctuation in the red cell flux. In a recent hypoxia imaging study using PET, the authors observed variation in tracer uptake in two sequential images and hypothesized that variation in acute hypoxia may be the cause. In this study, they develop an iterative optimization method to delineate chronic and acute hypoxia based on the PET serial images.

Methods:

They assume that (1) chronic hypoxia is the same in the two scans and can be represented by a Gaussian distribution, while (2) acute hypoxia varies in the two scans and can be represented by Poisson distributions. For validation, they used Monte Carlo simulations to generate pairs of PET images with known proportion of chronic and acute hypoxia and then applied the optimization method to the simulated serial images, yielding excellent fit between the input and the fitted results. They then applied this method to the serial PET images of 14 patients with head and neck cancers.

Results:

The results show good fit of the chronic hypoxia to Gaussian distributions for 13 out of 14 patients (with). Similarly, acute hypoxia appears to be well described by the Poisson distribution with three exceptions. The model calculation yielded the amount of acute hypoxia, which differed among the patients, ranging from to 52%, with an average of .

Conclusions:

This is the first effort to separate acute and chronic hypoxia from serial PET images of cancer patients.