bluuebunny/crossref_metadata_2025 huggingface dataset:
Delineating the “Ease of Doing Business” Construct within the Supplier–Customer Interface
Authors: Stading Gary , Altay Nezih
Published: April 2007

The current research provides insight into the “ease of doing business” construct. Factor analysis of survey responses of supply managers in the electronics industry was used to test the proposed “ease of doing business” construct, which includes the three dimensions — information and material services, financial contract services and personal relations services. Results support a link between a customer's assessment of a supplier's “ease of doing business” and the amount of business conducted with that supplier. The attributes supported by this research provide the means for managers to improve and grow business with customers.
The Working Postures Among Schoolchildren—A Controlled Intervention Study on the Effects of Newly Designed Workstations
Authors: Saarni Lea , Nygård Clas‐Håkan , Rimpelä Arja , Nummi Tapio , Kaukiainen Anneli
Published: April 2007

Background:  School workstations are often inappropriate in not offering an optimal sitting posture. The aim of this study was to investigate the effects of individually adjustable saddle‐type chairs with wheels and desks with comfort curve and arm support on schoolchildren’s working postures compared to conventional workstations.

Methods:  Ninety‐seven participants aged 12‐16 years were followed for 1 year, 47 at an intervention school and 50 at a control school. Anthropometrics and workstation dimensions were measured and working postures analyzed for a part of each group (n = 21, both groups) by means of video recording at baseline, before new workstations were introduced, and during follow‐up.

Results:  There was a significant increase in upright back (p= .012) and neck (p= .019) postures in the intervention group compared to controls during follow‐up. The saddle‐type chairs allowed significantly greater trunk‐thigh angles (p < .001) among participants than conventional chairs.

Conclusions:  In schoolchildren, using individually adjustable saddle‐type chairs and desks with comfort curve, a better match between workstations and anthropometric dimensions and improved working postures are obtained than using conventional workstations.
Chronic Pain in the Classroom: Teachers’ Attributions About the Causes of Chronic Pain*
Authors: Logan Deirdre E. , Catanese Sarah P. , Coakley Rachael M. , Scharff Lisa
Published: April 2007

Background:  School absenteeism and other impairments in school function are significant problems among children with chronic pain syndromes; yet, little is known about how chronic pain is perceived in the school setting. The purpose of this study was to examine teachers’ attributions about the causes of chronic pain in adolescent students.

Methods:  Classroom teachers (n = 260) read vignettes describing a hypothetical student with limb pain. They were presented with a list of possible physical and psychological causes for the pain and asked to identify the causes to which they attributed the pain. Vignettes varied by the presence or absence of (1) documented medical evidence for the pain and (2) communication from the medical team. Teachers also responded to questions assessing their responses to the student in terms of support for academic accommodations and sympathy for the student.

Results:  Teachers tended to endorse a dualistic (ie, either physical or psychological) model for pain rather than a biopsychosocial model. Documented medical evidence supporting the pain was the most influential factor affecting teachers’ attributions about chronic pain. Teachers who attributed the pain to physical causes—either in isolation or in combination with psychological causes—responded more positively toward the student.

Conclusions:  Many teachers lack a biopsychosocial framework through which to understand chronic pain syndromes in students. How chronic pain is described to school personnel may affect how teachers understand the pain and respond to it.
School Counselors and Student Self‐Injury
Authors: Roberts‐Dobie Susan , Donatelle Rebecca J.
Published: April 2007

Background:  The purpose of this study was to examine the experience, knowledge, and needs of school counselors in relation to students’ self‐injurious behaviors.

Methods:  One thousand members of the American School Counselor Association were randomly selected to receive a questionnaire on the study of self‐injury. Four hundred forty‐three school counselors returned usable questionnaires.

Results:  Most (81%) reported working with a self‐injurer during their career, and 51% reported working with a self‐injurer during the 2002‐2003 school year. Findings suggest that counselors feel they are the appropriate person to work with students who self‐injure but need more training to identify self‐injurers and refer them to appropriate resources outside of the school. Counselors identified a number of barriers to successfully working with students who self‐injure, such as lack of training, lack of cooperation with school personnel, and lack of policy on school injury.

Conclusions:  The authors suggest a model where the school counselor acts as a liaison to ensure the coordination of education about self‐injury for students, parents, and school staff and as a conduit to refer students to therapists in the community.
Legal Liability: The Consequences of School Injury
Authors: Barrios Lisa C. , Jones Sherry Everett , Gallagher Susan S.
Published: April 2007

Background:  Approximately 10‐25% of child and adolescent injuries occur at school. Little is known about school‐related injuries to teachers and other adults or about the direct cost of injuries to schools. This study examined the characteristics of cases involving injuries resulting in lawsuits against schools, compared cases in which schools paid awards with those in which schools did not pay awards, and compared student and nonstudent injuries resulting in lawsuits against schools.

Methods:  Descriptions of cases of school liability for personal injury that were tried or settled between July 1996 and May 2002 were purchased from Jury Verdict Research, which maintains a national database of verdicts and settlements. The 455 cases reviewed were coded according to the characteristics of the case, school, award, and injured party.

Results:  In two thirds of the cases, schools or school districts paid an award to plaintiffs (mean =$562,915, median =$50,000). In most cases, the injured party was male (57.1%) and younger than 18 years of age (79.9%). Fractures (38.9%) were the most common type of injury. Falls (21.9%) were the most common cause of injury. Among cases of intentional injury, 93.2% involved an injury to a student; among cases of unintentional injury, 74.6% involved injury to a student.

Conclusions:  Preventing school‐related injuries is an ethical and legal obligation for schools and school districts. Prevention is also critical because a wide range of injuries are litigated, and such lawsuits often require schools and school districts to pay costly awards to injured parties.
DIVERSITY AND PERVERSITY
Authors: Mendoza Steven
Published: April 2007

abstract  Biological diversity is presented as a model of psychic diversity. Perversity, the general form of perversion which pervades, to some extent, the psyches of us all, is not presented as a diversity of lifestyle, as political correctness might have it. It is presented as a psychopathology causing suffering and needing help. The reprehension of perversity is suggested, through the work of Bion, as itself an aspect of perversity. The difficulties of analysing perversity through the general condition of narcissism is addressed emotionally through the universality of some measure of narcissism and theoretically through the work of Bion on ‘without‐ness’, frustration and the disappointment of constant conjunction, and through Meltzer’s distinction between polymorphous and perverse and through his concept of aesthetic conflict.
ON THE SLOPES OF BROKEBACK MOUNTAIN: COUNTERTRANSFERENCE IMPEDIMENTS TO AN ANALYTIC ATTITUDE IN WORK WITH GAY MEN
Authors: Flower Steven
Published: April 2007

abstract  There have been many debates about psychoanalytic and Jungian views of homosexuality. As part of these it has often been recognized that analysts have appeared reluctant to comment on their own countertransference responses to gay patients. Yet these responses must inevitably have a significant bearing on the way the work is conceptualized and undertaken. This paper highlights ways in which homophobia and related countertransference difficulties influenced the author’s ability to engage with one male patient. It traces the process by which the analyst became aware of his own discomfort and the nature of his struggle to find a more helpful and reflective position in the analytic work. The process was prompted by a dream which depicted some of the difficulties the analytic pair was experiencing and by a heightened scrutiny of the countertransference. The progress of the work is marked by three further dreams which trace the development of the analytic relationship.
‘THOSE THAT THE GODS WISH TO DESTROY, THEY FIRST MAKE MAD’*: AN ANALYTIC DISCUSSION OF THE DEPICTION OF SADO‐MASOCHISM IN THE FILM THE NIGHT PORTER
Authors: Valentine Marguerite
Published: April 2007

abstract  While the film The Night Porter, which was originally released in 1974, ostensibly portrays a detailed account of the development of a sado‐masochistic relationship, it may also be read as a political metaphor. The film’s director and writer, Liliana Cavani, explicitly links the two protagonists’ obsession with each other as originating in an earlier shared experience within a concentration camp. This is to become re‐enacted years later following a chance meeting. This paper is a detailed psychoanalytic exposition of the development and nature of that relationship, but read within the context of a political and sociological framework. It notes how Cavani uses visual symbolization to represent the increasing perverse control and symbiotic complicity between Max, the Nazi guard, and Lucia, the young Jewish woman. The film’s power lies in the implicit: it is an allegory of a society’s descent into barbarism, and a portentous critique of authoritarianism, however expressed.
Prospective targeting and control of end‐tidal CO2 and O2 concentrations
Authors: Slessarev Marat , Han Jay , Mardimae Alexandra , Prisman Eitan , Preiss David , Volgyesi George , Ansel Cliff , Duffin James , Fisher Joseph A.
Published: April 2007

Current methods of forcing end‐tidal PCO2 (PETCO2) and PO2 (PETO2) rely on breath‐by‐breath adjustment of inspired gas concentrations using feedback loop algorithms. Such servo‐control mechanisms are complex because they have to anticipate and compensate for the respiratory response to a given inspiratory gas concentration on a breath‐by‐breath basis. In this paper, we introduce a low gas flow method to prospectively target and control PETCO2 and PETO2 independent of each other and of minute ventilation in spontaneously breathing humans. We used the method to change PETCO2 from control (40 mmHg for PETCO2 and 100 mmHg for PETO2) to two target PETCO2 values (45 and 50 mmHg) at iso‐oxia (100 mmHg), PETO2 to two target values (200 and 300 mmHg) at normocapnia (40 mmHg), and PETCO2 with PETO2 simultaneously to the same targets (45 with 200 mmHg and 50 with 300 mmHg). After each targeted value, PETCO2 and PETO2 were returned to control values. Each state was maintained for 30 s. The average difference between target and measured values for PETCO2 was ± 1 mmHg, and for PETO2 was ± 4 mmHg. PETCO2 varied by ± 1 mmHg and PETO2 by ± 5.6 mmHg (s.d.) over the 30 s stages. This degree of control was obtained despite considerable variability in minute ventilation between subjects (± 7.6 l min−1). We conclude that targeted end‐tidal gas concentrations can be attained in spontaneously breathing subjects using this prospective, feed‐forward, low gas flow system.
Feedforward versus feedback modulation of human vestibular‐evoked balance responses by visual self‐motion information
Authors: Day Brian L. , Guerraz Michel
Published: April 2007

Visual information modulates the balance response evoked by a pure vestibular perturbation (galvanic vestibular stimulation, GVS). Here we investigate two competing hypotheses underlying this visual–vestibular interaction. One hypothesis assumes vision acts in a feedforward manner by altering the weight of the vestibular channel of balance control. The other assumes vision acts in a feedback manner through shifts in the retinal image produced by the primary response. In the first experiment we demonstrate a phenomenon that is predicted by both hypotheses: the GVS‐evoked balance response becomes progressively smaller as the amount of visual self‐motion information is increased. In the second experiment we independently vary the pre‐stimulus and post‐stimulus visual environments. The rationale is that feedback effects would depend only upon the post‐stimulus visual environment. Although the post‐stimulus visual environment did affect later parts of the response (after ∼400 ms), the pre‐stimulus visual environment had a strong influence on the size of the early part of the response. We conclude that both feedforward and feedback mechanisms act in concert to modulate the GVS‐evoked response. We suggest this dual interaction that we observe between visual and vestibular channels is likely to apply to all sensory channels that contribute to balance control.
Characterization of the molecular and electrophysiological properties of the T‐type calcium channel in human myometrium
Authors: Blanks Andrew M. , Zhao Zheng‐Hang , Shmygol Anatoly , Bru‐Mercier Gilles , Astle Shirley , Thornton Steven
Published: April 2007

Rises in intracellular calcium are essential for contraction of human myometrial smooth muscle (HMSM) and hence parturition. The T‐type calcium channel may play a role in this process. The aim was to investigate the role of the T‐type calcium channel in HMSM by characterizing mRNA expression, protein localization, electrophysiological properties and function of the channel subunits Cav3.1(α1G), Cav3.2(α1H), and Cav3.3(α1I). QRT‐PCR, immunohistochemistry, electrophysiology and invitro contractility were performed on human myometrial samples from term, preterm, labour and not in labour. QRT‐PCR analysis of Cav3.1, Cav3.2 and Cav3.3 demonstrated expression of Cav3.1 and Cav3.2 with no significant change (P > 0.05) associated with gestation or labour status. Immunohistochemistry localized Cav3.1 to myometrial and vascular smooth muscle cells whilst Cav3.2 localized to vascular endothelial cells and invading leucocytes. Voltage clamp studies demonstrated a T‐type current in 55% of cells. Nickel block of T‐type current was voltage sensitive (IC50 of 118.57 ± 68.9 μm at −30 mV). Activation and inactivation curves of ICa currents in cells expressing T‐type channels overlapped demonstrating steady state window currents at the resting membrane potential of myometrium at term. Current clamp analysis demonstrated that hyperpolarizing pulses to a membrane potential greater than −80 mV elicited rebound calcium spikes that were blocked reversibly by 100 μm nickel. Contractility studies demonstrated a reversible decrease in contraction frequency during application of 100 μm nickel (P < 0.05). We conclude that the primary T‐type subunit expressed in some MSMCs is Cav3.1. We found that application of 100 μm nickel to spontaneously contracting human myometrium reversibly slows contraction frequency.
Activation of AMP kinase α1 subunit induces aortic vasorelaxation in mice
Authors: Goirand Françoise , Solar Myriam , Athea Yoni , Viollet Benoit , Mateo Philippe , Fortin Dominique , Leclerc Jocelyne , Hoerter Jacqueline , Ventura‐Clapier Renée , Garnier Anne
Published: April 2007

Vasodilatation is a vital mechanism of systemic blood flow regulation that occurs during periods of increased energy demand. The AMP‐dependent protein kinase (AMPK) is a serine/threonine kinase that is activated by conditions that increase the AMP‐to‐ATP ratio, such as exercise and metabolic stress. We hypothesized that AMPK could trigger vasodilatation and participate in blood flow regulation. Rings of thoracic aorta were isolated from C57Bl6 mice and mice deficient in the AMPK catalytic α1 (AMPKα1−/−) or α2 (AMPKα2−/−) subunit and their littermate controls, and mounted in an organ bath. Aortas were preconstricted with phenylephrine (1 μm) and activation of AMPK was induced by addition of increasing concentrations of 5‐aminoimidazole‐4‐carboxamide‐1‐β‐d‐ribofuranoside (AICAR). AICAR (0.1–3 mm) dose‐dependently induced relaxation of precontracted C57BL6, AMPKα1+/+ and α2+/+ aorta (P < 0.001, n= 5–7 per group). This AICAR induced vasorelaxation was not inhibited by the addition of adenosine receptor antagonists. Moreover, when aortic rings were freed of endothelium by gentle rubbing, AICAR still induced aortic ring relaxation, suggesting a direct effect of AICAR on smooth muscle cells. When aortic rings were pretreated with l‐NMMA (30 μm) to inhibit nitric oxide synthase activity, AICAR still induced relaxation. Western blot analysis of C57Bl6 mice denuded aorta showed that AMPK was phosphorylated after incubation with AICAR and that AMPKα1 was the main catalytic subunit expressed. Finally, AICAR‐induced relaxation of aortic rings was completely abolished in AMPKα1−/− but not AMPKα2−/− mice. Taken together, the results show that activation of AMPKα1 but not AMPKα2 is able to induce aortic relaxation in mice, in an endothelium‐ and eNOS‐independent manner.
Inspiratory bursts in the preBötzinger complex depend on a calcium‐activated non‐specific cation current linked to glutamate receptors in neonatal mice
Authors: Pace Ryland W. , Mackay Devin D. , Feldman Jack L. , Del Negro Christopher A.
Published: April 2007

Inspiratory neurons of the preBötzinger complex (preBötC) form local excitatory networks and display 10–30 mV transient depolarizations, dubbedinspiratory drive potentials, with superimposed spiking. AMPA receptors are critical for rhythmogenesis under normal conditionsin vitrobut whether other postsynaptic mechanisms contribute to drive potential generation remains unknown. We examined synaptic and intrinsic membrane properties that generate inspiratory drive potentials in preBötC neurons using neonatal mouse medullary slice preparations that generate respiratory rhythm. We found that NMDA receptors, group I metabotropic glutamate receptors (mGluRs), but not group II mGluRs, contributed to inspiratory drive potentials. Subtype 1 of the group I mGluR family (mGluR1) probably regulates a K+channel, whereas mGluR5 operates via an inositol 1,4,5‐trisphosphate (IP3) receptor‐dependent mechanism to augment drive potential generation. We tested for and verified the presence of a Ca2+‐activated non‐specific cation current (ICAN) in preBötC neurons. We also found that high concentrations of intracellular BAPTA, a high‐affinity Ca2+chelator, and theICANantagonist flufenamic acid (FFA) decreased the magnitude of drive potentials. We conclude thatICANunderlies robust inspiratory drive potentials in preBötC neurons, and is only fully evoked by ionotropic and metabotropic glutamatergic synaptic inputs, i.e. by network activity.
An Approach for Fatigue Life Prediction
Authors: Jiang Yanyao , Ding Fei , Feng Miaolin
Published: April 2007

Fatigue process is described as the nucleation and growth of cracks to final failure. These two stages are generally modeled with completely different methods with no quantitative relationships between them. A number of fitting parameters are needed to consider different effects. The current work is aimed at developing a robust approach to predicting fatigue life from crack initiation to final fracture. Fatigue damage is related to the stresses and strains. Both crack nucleation and crack growth are governed by the same fatigue damage mechanisms and a single fatigue damage criterion can model both stages. A basic rule is that any material point fails to form a fresh crack if the total accumulated fatigue damage reaches a limit. The approach consists of two steps. Elastic-plastic stress analysis is conducted to obtain the detailed stress-strain responses. A general fatigue criterion is used to predict both fatigue crack nucleation and growth. Notched specimens made of 1070 steel were experimentally tested from crack initiation until fracture. The approach was applied to predict the fatigue life of 1070 steel and the predicted fatigue lives were in excellent agreement with the experimental observations.
Average Strain in Fiber Bundles and Its Effect on NCF Composite Stiffness
Authors: Mattsson H. David , Varna Janis
Published: April 2007

Transverse strain in bundles governs transverse cracking in noncrimp fabric (NCF) composites. Finite element (FE) analysis shows that this strain may be significantly lower than the applied macroscopic strain component in the same direction. This feature is important for damage evolution modeling. The isostrain assumption which in different combinations is widely used in stiffness models is inadequate because the strain in different mesoelements (bundles of different orientation and matrix regions) is assumed the same. Analyzing by FEM the importance of media surrounding the bundle on average transverse strain it was found that an increasing ratio of the bundle transverse stiffness to the matrix stiffness leads to a decrease of the strain in the bundle. An increase of the stiffness in the same direction in adjacent layers leads to an increase of the transverse strain in the bundle. Higher bundle volume fraction in the layer leads to larger transverse strain in the bundle. These trends are described by a power law and used to predict the average strain in bundles. The calculated H matrix which establishes the relationship between strains in the mesoelement and representative volume element strains is used to calculate the “effective stiffness” of the bundle. This effective stiffness is the main element in simple but exact expressions derived to calculate the stiffness matrix of NCF composites. Considering the three-dimensional (3D) FE model as the reference, it was found that all homogenization methods used in this study have sufficient accuracy for stiffness calculations, but only the presented method gives reliable predictions of strains in bundles.
Pressure Sensitive Nonassociative Plasticity Model for DRA Composites
Authors: Lei Xin , Lissenden Cliff J.
Published: April 2007

Discontinuously reinforced aluminum (DRA) is currently used where design considerations include specific stiffness, tailorable coefficient of thermal expansion, or wear resistance. Plastic deformation plays a role in failures due to low cycle fatigue or simple ductile overload. DRA is known to exhibit pressure dependent yielding. Plastic deformation in metals is widely regarded to be incompressible, or very nearly so. A continuum plasticity model is developed that includes a Drucker–Prager pressure dependent yield function, plastic incompressibility via a nonassociative Prandtl–Reuss flow rule, and a generalized Armstrong–Frederick kinematic hardening law. The model is implemented using a return mapping algorithm with backward Euler integration for stability and the Newton method to determine the plastic multiplier. Material parameters are characterized from uniaxial tension and uniaxial compression experimental results. Model predictions are compared to experimental results for a nonproportional compression–shear load path. The tangent stiffness tensor is nonsymmetric because the flow rule is not associated with the yield function, which means that the commonly used algorithms that require symmetric matrices cannot be used with this material model. Model correlations with tension and compression loadings are excellent. Model predictions of shear and nonproportional compression–shear loadings are reasonably good. The nonassociative flow rule could not be validated by comparison of the plastic strain rate direction with the yield function and the flow potential due to scatter in the experimental results. The model is capable of predicting the material response obtained in the experiments, but additional validation is necessary for the condition of high hydrostatic pressure.
Weld Distortion Control During Welding Process With Reverse-Side Heating
Authors: Mochizuki Masahito , Toyoda Masao
Published: April 2007

An in-process method for controlling welding distortion in fillet welds is developed. It particularly reduces angular distortion by performing reverse-side Tungsten inert gas (TIG) heating of the weld line at a fixed distance ahead of metal inert gas (MIG) welding during the weld process. Various heating conditions are examined by experiment and by the finite-element analysis in order to determine appropriate conditions and to study the mechanism by which welding distortion is reduced. It is consequently found that this mechanism is a result of two main effects: TIG heating effect on the reverse side, which produces the opposite angular distortion, and preheating effect.
Behavior of Nonhomogeneous Materials Subjected to Bearing Load
Authors: Batra Varun , Rousseau Carl-Ernst
Published: April 2007

The behavior of homogeneous and nonhomogenous materials with linearly varying material property subjected to line loading is investigated using the optical method of coherent gradient sensing. A three-dimensional finite element solution to the problem is first undertaken to establish the scope of the region within which the optical data can be considered to be valid. The numerical results are also used to uncover information beyond that which can be obtained from the experimental method, therefore fostering better understanding of the material behavior. The results suggest structural superiority of materials loaded on the stiff side of the material gradient due to the fact that this loading configuration attenuates stress concentration effects.
On Serrated Plastic Flow in an AA5052-H32 Sheet
Authors: Tong Wei , Zhang Nian
Published: April 2007

Temporal and spatial characteristics of serrated plastic flow or the so-called Portevin-Le Chatelier (PLC) deformation bands in a commercial Al-2.5%Mg sheet metal due to dynamic strain aging effects were investigated experimentally under quasi-static uniaxial tension. It was found that the thickness and width of test coupons, applied loading conditions (machine stiffness and crosshead speed), and mechanical polishing had an observable effect on the temporal characteristics of the serrated plastic flow while short and long interruptions during the tensile tests with stress relaxation and even completely unloading show minimal effects on the subsequent serrated flow behavior. Serrations in axial load in AA5052-H32 were found to associate with the appearance of discrete narrow deformation bands in the tensile test coupons with the bands aligned 59±1deg with respect to the tensile loading axis. The detailed strain distribution across the deformation bands showed a bell-like instead of steplike shape, indicating that the formation of these deformation bands was controlled by a local nucleation and growth process at a cross section in the polycrystalline sheet.
Evidence of Ductile Tearing Ahead of the Cutting Tool and Modeling the Energy Consumed in Material Separation in Micro-Cutting
Authors: Subbiah Sathyan , Melkote Shreyes N.
Published: April 2007

Orthogonal cutting experiments using a quick-stop device are performed on Al2024-T3 and OFHC copper to study the chip–workpiece interface in a scanning electron microscope. Evidence of ductile tearing ahead of the tool at cutting speeds of 150m∕min has been found. A numerical finite element model is then developed to study the energy consumed in material separation in micro-cutting. The ductile fracture of Al2024-T3 in a complex stress state ahead of the tool is captured using a damage model. Chip formation is simulated via the use of a sacrificial layer and sequential elemental deletion in this layer. Element deletion is enforced when the accumulated damage exceeds a predetermined value. A Johnson–Cook damage model that is load history dependent and with strain-to-fracture dependent on stress, strain rate, and temperature is used to model the damage. The finite element model is validated using the cutting forces obtained from orthogonal micro-cutting experiments. Simulations are performed over a range of uncut chip thickness values. It is found that at lower uncut chip thickness values, the percentage of energy expended in material separation is higher than at higher uncut chip thicknesses. This work highlights the importance of the energy associated with material separation in the nonlinear scaling effect of specific cutting energy in micro-cutting.
Four Phase Model: A New Formulation to Predict the Effective Elastic Moduli of Composites
Authors: Barhdadi El H. , Lipinski P. , Cherkaoui M.
Published: April 2007

We consider a linearly elastic composite medium, which consists of a homogeneous matrix containing coated spherical inclusions. The composite is modeled by a four phase pattern consisting of inclusion, interphase, matrix layer, and equivalent homogeneous medium. The overall elastic moduli are obtained using a micromechanical approach based on the Green function techniques and the interfacial operators. The four phase model assumes that all constituents are elastic and perfectly bonded. The model is used to derive the effective elastic properties of representative volume element using classical averaging schemes assuming the isotropy of constituent. Finally, effect of the thickness and stiffness of interphase on the global behavior of real composite materials are examined. Comparisons with experimental results show a good agreement.
A Comprehensive Theory of Yielding and Failure for Isotropic Materials
Authors: Christensen Richard M.
Published: April 2007

A theory of yielding and failure for homogeneous and isotropic materials is given. The theory is calibrated by two independent, measurable properties and from those it predicts possible failure for any given state of stress. It also differentiates between ductile yielding and brittle failure. The explicit ductile-brittle criterion depends not only upon the material specification through the two properties, but also and equally importantly depends upon the type of imposed stress state. The Mises criterion is a special (limiting) case of the present theory. A close examination of this case shows that the Mises material idealization does not necessarily imply ductile behavior under all conditions, only under most conditions. When the first invariant of the yield/failure stress state is sufficiently large relative to the distortional part, brittle failure will be expected to occur. For general material types, it is shown that it is possible to have a state of spreading plastic flow, but as the elastic-plastic boundary advances, the conditions for yielding on it can change over to conditions for brittle failure because of the evolving stress state. The general theory is of a three-dimensional form and it applies to full density materials for which the yield/failure strength in uniaxial tension is less than or at most equal to the magnitude of that in uniaxial compression.
Blastocyst Axis Is Specified Independently of Early Cell Lineage But Aligns with the ZP Shape
Authors: Kurotaki Yoko , Hatta Kohei , Nakao Kazuki , Nabeshima Yo-ichi , Fujimori Toshihiko
Published: April 2007

The mechanisms controlling the establishment of the embryonic-abembryonic (E-Ab) axis of the mammalian blastocyst are controversial. We used in vitro time-lapse imaging and in vivo lineage labeling to provide evidence that the E-Ab axis of the mouse blastocyst is generated independently of early cell lineage. Rather, both the boundary between two-cell blastomeres and the E-Ab axis of the blastocyst align relative to the ellipsoidal shape of the zona pellucida (ZP), an extraembryonic structure. Lack of correlation between cell lineage and the E-Ab axis can be explained by the rotation of the embryo within the ZP.
Developmentally Regulated piRNA Clusters Implicate MILI in Transposon Control
Authors: Aravin Alexei A. , Sachidanandam Ravi , Girard Angelique , Fejes-Toth Katalin , Hannon Gregory J.
Published: April 2007

Nearly half of the mammalian genome is composed of repeated sequences. In
Drosophila
, Piwi proteins exert control over transposons. However, mammalian Piwi proteins, MIWI and MILI, partner with Piwi-interacting RNAs (piRNAs) that are depleted of repeat sequences, which raises questions about a role for mammalian Piwi's in transposon control. A search for murine small RNAs that might program Piwi proteins for transposon suppression revealed developmentally regulated piRNA loci, some of which resemble transposon master control loci of
Drosophila
. We also find evidence of an adaptive amplification loop in which MILI catalyzes the formation of piRNA 5′ ends.
Mili
mutants derepress LINE-1 (L1) and intracisternal A particle and lose DNA methylation of L1 elements, demonstrating an evolutionarily conserved role for PIWI proteins in transposon suppression.
Tropheryma whipplei
Infective Endocarditis as the Only Manifestation of Whipple's Disease
Authors: Marín Mercedes , Muñoz Patricia , Sánchez Mónica , del Rosal Marina , Rodríguez-Créixems Marta , Bouza E.
Published: April 2007

Here we describe a case of infective endocarditis caused by
Tropheryma whipplei
in a patient with no other symptoms of Whipple's disease. The case was diagnosed using broad-range PCR and confirmed by specific PCRs. We review the cases of infective endocarditis presenting as the only manifestation of Whipple's disease reported in the literature.
THERMOACOUSTIC TOMOGRAPHY AND THE CIRCULAR RADON TRANSFORM: EXACT INVERSION FORMULA
Authors: HALTMEIER MARKUS , SCHERZER OTMAR , BURGHOLZER PETER , NUSTER ROBERT , PALTAUF GUENTHER
Published: April 2007

Thermoacoustic computed tomography (TACT) is an emerging hybrid imaging method for non-invasive medical diagnosis and fully three-dimensional visualization of biological probes. Within this modality electromagnetic illumination is used to induce acoustic waves inside an object of interest. In this paper, we assume that a cylindrical array of line detectors is used to record the acoustical data. This leads to the mathematical problem of inverting the circular Radon transform.

The circular Radon transform arises in several other up-to-date imaging modalities, such as RADAR imaging or ultrasound tomography. In this paper we prove a novel stable formula for recovering a planar function from its circular Radon transform. We apply this formula to obtain an exact three-dimensional imaging algorithm for TACT. Numerical reconstructions from real and synthetic data demonstrate the potential and robustness of our algorithm.
DEFAULTABLE LÉVY LIBOR RATES AND CREDIT DERIVATIVES
Authors: HUEHNE FLORIAN
Published: April 2007

We introduce the intensity-based defaultable Lévy Libor model, which generalizes the default-free Lévy Libor model introduced by Eberlein and Özkan in [The defaultable Lévy term structure: Ratings and restructuring, Mathematical Finance13(2) (2003) 277–300], and the intensity-based defaultable model presented by Bielecki and Rutkowski in [Credit Risk: Modeling, Valuation and Hedging, Springer Finance (Springer-Verlag, 2002)] by embedding it in the defaultable HJM framework introduced by Eberlein and Özkan in [The defaultable Lévy term structure: Ratings and restructuring, Mathematical Finance13(2) (2003) 277–300]. We also derive some additional results for defaultable HJM models such as the dynamics of credit spreads. We then go on and model the default-free Libor rates and credit spreads as the primal variable and derive the dynamics of the defaultable Libor rates under the defaultable forward measure. Finally, we derive an explicit formula for options on credit default swaps, using an idea introduced by Raible in [Lévy Processes in finance: Theory, numerics and empirical facts, PhD thesis, University of Freiburg i. Brsg. (2000)].
ON PORTFOLIO SELECTION UNDER EXTREME RISK MEASURE: THE HEAVY-TAILED ICA MODEL
Authors: CLÉMENÇON STÉPHAN , SLIM SKANDER
Published: April 2007

This paper is devoted to the application of the Independent Component Analysis (ICA) methodology to the problem of selecting portfolio strategies, so as to provide against extremal movements in financial markets. A specific ICA model for describing the extreme fluctuations of asset prices is introduced, stipulating that the distributions of the ICs are heavy tailed (i.e., with power law behavior at infinity). An inference method based on conditional maximum likelihood estimation is proposed for our model, which permits to determine practically optimal investment strategies with respect to extreme risk. Empirical studies based on this modeling are carried out to illustrate our approach.
THE LINEAR DEPENDENCE AND FEEDBACK SPECTRA BETWEEN STOCK MARKET AND ECONOMY
Authors: PAN XIA
Published: April 2007

Geweke studied the measure of linear dependence and spectral feedback for grouped multivariate time series. This paper applies the measure of linear dependence and spectral feedback to examining the relationship between grouped variables of economy and stock market indices. Putting economic variables into one group and stock market variables into another, we examine the between-group relationship within the US, within Japan, and within the European Union. Using a self-developed computing program, the feedback spectra for grouped variables are calculated and displayed. Although risk might exist in that the significance levels for test may not be reliable because the feedback spectra are measured on possibly nonstationary variables in level, the patterns of the feedback spectra still provide information about the cyclical effect between the variable groups.
Lipopolysaccharide disrupts tight junctions in cholangiocyte monolayers by a c-Src-, TLR4-, and LBP-dependent mechanism
Authors: Sheth P. , Delos Santos N. , Seth A. , LaRusso N. F. , Rao R. K.
Published: April 2007

Bile duct epithelium forms a barrier to the backflow of bile into the liver parenchyma. However, the structure and regulation of the tight junctions in bile duct epithelium is not well understood. In the present study, we evaluated the effect of lipopolysaccharide on tight junction integrity and barrier function in normal rat cholangiocyte monolayers. Lipopolysaccharide disrupts barrier function and increases paracellular permeability in a time- and dose-dependent manner. Lipopolysaccharide induced a redistribution of tight junction proteins, occludin, claudin-1, claudin-4, and zonula occludens (ZO)-1 from the intercellular junctions and reduced the level of ZO-1. Tyrosine kinase inhibitors (genistein and PP2) prevented lipopolysaccharide-induced increase in permeability and subcellular redistribution of ZO-1. Reduced expression of c-Src, TLR4, or LBP by specific small interfering RNA attenuated lipopolysaccharide-induced permeability and redistribution of ZO-1. ML-7, a myosin light chain kinase inhibitor, attenuated LPS-induced permeability. Lipopolysaccharide treatment rapidly increased the phosphorylation of occludin and ZO-1 on tyrosine residues, which was prevented by genistein and PP2. Occludin and ZO-1 were found to be highly phosphorylated on threonine residues in intact cell monolayers. Threonine-phosphorylation of occludin was rapidly reduced by lipopolysaccharide administration. Lipopolysaccharide-induced dephosphorylation of occludin on Thr residues was prevented by genistein and PP2. In conclusion, lipopolysaccharide disrupts the tight junction of a bile duct epithelial monolayer by a c-Src-, TLR4-, LBP-, and myosin light chain kinase-dependent mechanism.
Effects of pulmonary ischemia on lung morphology
Authors: Fields Michael J. , Bishai John M. , Mitzner Wayne , Wagner Elizabeth M.
Published: April 2007

Pulmonary ischemia resulting from chronic pulmonary embolism leads to proliferation of the systemic circulation within and surrounding the lung. However, it is not clear how well alveolar tissue is sustained during the time of complete pulmonary ischemia. In the present study, we investigated how pulmonary ischemia after left pulmonary artery ligation (LPAL) would alter lung mechanical properties and morphology. In this established mouse model of lung angiogenesis after chronic LPAL ( 10 ), we evaluated lung function and structure before (3 days) and after (14 days) a functional systemic circulation to the left lung is established. Age-matched naïve and sham-operated C57Bl/6 mice and mice undergoing chronic LPAL were studied. Left and right lung pressure-volume relationships were determined. Next, lungs were inflated in situ with warmed agarose (25–30 cmH2O) and fixed, and mean chord lengths (MCL) of histological sections were quantified. MCL of naïve mice averaged 43.9 ± 1.8 μm. No significant changes in MCL were observed at either time point after LPAL. Left lung volumes and specific compliances were significantly reduced 3 days after LPAL. However, by 14 days after LPAL, lung pressure-volume relationships were not different from controls. These results suggest that severe pulmonary ischemia causes changes in lung mechanics early after LPAL that are reversed by the time a new systemic vasculature is known to perfuse pulmonary capillaries. The LPAL model thus affords a unique opportunity to study lung functional responses to tissue ischemia and subsequent recovery.
Effects of extracellular HCO3−on fatigue, pHi, and K+efflux in rat skeletal muscles
Authors: Broch-Lips Martin , Overgaard Kristian , Praetorius Helle A. , Nielsen Ole Bækgaard
Published: April 2007

Elevated plasma HCO3−can improve exercise endurance in humans. This effect has been related to attenuation of the work-induced reduction in muscle pH, which is suggested to improve performance via at least two mechanisms: 1) less inhibition of muscle enzymes and 2) reduced opening of muscle KATPchannels with less ensuing reduction in excitability. Aiming at determining whether the ergogenic effect of HCO3−is related to effects on muscles, we examined the effect of elevating extracellular HCO3−from 25 to 40 mM (pH from 7.4 to 7.6) on fatigue, intracellular pH (pHi), and K+efflux in isolated rat skeletal muscles contracting isometrically. Fatigue induced by 30-Hz stimulation at 30 and 37°C was similar between soleus muscles incubated in high and normal HCO3−concentrations. In extensor digitorum longus muscles stimulated at 60 Hz, elevated HCO3−did not affect fatigue at 30°C. In soleus muscles, 30-Hz stimulation induced a ∼0.2 unit reduction in pHi, as determined by using the pH-sensitive probe 2′,7′-bis(2-carboxyethyl)-5( 6 )-carboxyfluorescein. This reduction in pHiwas not affected by elevated HCO3−. Estimation of K+efflux using86Rb+showed that elevated HCO3−did not affect K+efflux at rest or during contractions. Similarly, other modifications of the intra- and extracellular pH had little effect on K+efflux during contraction. In conclusion, elevated extracellular HCO3−had no significant effect on muscle fatigue, pHi, and K+efflux. These findings indicate that alternative mechanisms must be considered for the ergogenic effect of HCO3−observed in integral exercise studies.
Quantitative diffusion tensor MRI-based fiber tracking of human skeletal muscle
Authors: Lansdown Drew A. , Ding Zhaohua , Wadington Megan , Hornberger Jennifer L. , Damon Bruce M.
Published: April 2007

Diffusion-tensor magnetic resonance imaging (DT-MRI) offers great potential for understanding structure-function relationships in human skeletal muscles. The purposes of this study were to demonstrate the feasibility of using in vivo human DT-MRI fiber tracking data for making pennation angle measurements and to test the hypothesis that heterogeneity in the orientation of the tibialis anterior (TA) muscle's aponeurosis would lead to heterogeneity in pennation angle. Eight healthy subjects (5 male) were studied. T1-weighted anatomical MRI and DT-MRI data were acquired of the TA muscle. Fibers were tracked from the TA's aponeurosis by following the principal eigenvector. The orientations of the aponeurosis and muscle fiber tracts in the laboratory frame of reference and the orientation of the fiber tracts with respect to the aponeurosis [i.e., the pennation angle (θ)] were determined. The muscle fiber orientations, when expressed relative to the laboratory frame of reference, did not change as functions of superior-to-inferior position. The sagittal and coronal orientations of the aponeurosis did not change in practically significant manners either, but the aponeurosis′ axial orientation changed by ∼40°. As a result, the mean value for θ decreased from 16.3 (SD 6.9) to 11.4° (SD 5.0) along the muscle's superior-to-inferior direction. The mean value of θ was greater in the deep than in the superficial compartment. We conclude that pennation angle measurements of human muscle made using DT-MRI muscle fiber tracking are feasible and reveal that in the foot-head direction, there is heterogeneity in the pennation properties of the human TA muscle.
Alveolar macrophage depletion is associated with increased surfactant pool sizes in adult rats
Authors: Forbes Amy , Pickell Mike , Foroughian Mehry , Yao Li-Juan , Lewis James , Veldhuizen Ruud
Published: April 2007

Pulmonary surfactant is a lipid-protein material that is essential for normal lung function. Maintaining normal and consistent alveolar amounts of surfactant is in part dependent on clearance of surfactant by alveolar macrophages (AM). The present study utilized a rat model of AM depletion to determine the impact on surfactant pool sizes and function over time. Male Sprague-Dawley rats were anesthetized and intratracheally instilled with PBS-liposomes (PBS-L) or dichloromethylene diphosphonic acid (DMDP) containing liposomes (DMDP-L) and were killed at various time points up to 21 days for compliance measurements, AM cell counts, and surfactant analysis. AM numbers were significantly decreased 1, 2, and 3 days after instillation in DMDP-L vs. PBS-L, with 72% depletion at 3 days. AM numbers returned to normal levels by 5 days. In DMDP-L rats, there was a rapid increase in surfactant-phospholipid pools, showing a ninefold increase in the amount of surfactant in the lavage 3 days after liposome instillation. Surfactant accumulation progressed up to 7 days, with pools normalizing by 21 days. The increase in surfactant was due to increases in both subfractions of surfactant, the large aggregates (LA) and small aggregates. Surfactant protein A levels, relative to LA phospholipids, were not increased. There was a decreased extent of surfactant conversion in vitro for LA from DMDP-L rats compared with controls. It is concluded that the procedure of AM depletion significantly affects surfactant metabolism. The increased endogenous surfactant must be considered when utilizing the AM depletion model to study the role of these cells during lung insults.