bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Medical Malpractice on Resource Use and Mortality of AMI Patients
Authors: Dhankhar Praveen , Khan M. Mahmud , Bagga Shalini
Published: March 2007

We estimate the effect of medical malpractice on physician behavior and health outcomes of AMI patients. The National Practitioner Data Bank (NPDB) has been combined with the Nationwide Inpatient Sample (NIS). Frequency of paid claims and claims severity are used as measures of medical malpractice risk in each state. Results suggest that an increase in medical malpractice risk leads to a reduction in resource use and improvement in health outcome for patients with less severe medical conditions. For patients with more severe medical conditions, medical malpractice is associated with an improvement in mortality. Therefore, we find no evidence that the costs of defensive medicine for most AMI patients are escalating. Threat of a malpractice lawsuit lowers the mortality rate of AMI patients, contradicting the widely held view that defensive medicine has no positive effect on health status of patients.
Reducing Medical Malpractice by Targeting Physicians Making Medical Malpractice Payments
Authors: Adams John L. , Garber Steven
Published: March 2007

Some states use physicians' histories of medical malpractice payments to try to reduce the incidence of medical malpractice (and for other reasons). At least two types of policies fall into this category: using payments to decide which physicians will be investigated, and possibly sanctioned, by the state medical board; and making information about individual physicians' payment histories available to the public. Previous literature suggests that such policies will not be very effective because the link between medical malpractice and medical malpractice payments appears weak. Unlike previous researchers, we examine this issue directly and quantitatively. To do so, we develop a micro‐simulation model of the random processes determining medical outcomes, claiming rates, and payment rates, using information from several strands of literature to calibrate its parameters. To examine sensitivity of our predictions to changes in assumptions, we also consider 14 alternative models. For each of the 15 cases, we simulate data for a population of 100,000 physicians and analyze the simulated data. We find that neither type of policy will substantially reduce the population rate of malpractice and that the policy of publicizing payment histories could, in principle, backfire.
Nonlinear taxes for spatially mobile workers
Authors: Blackorby Charles , Brett Craig , Cebreiro Ana
Published: March 2007

This article examines optimal nonlinear taxes with worker mobility. We devise a model in which two qualitatively different types of workers choose to live in either of two jurisdictions. Residence decisions and labor–leisure choices are influenced by the tax schedules operating in the two regions. Within worker category, individuals may differ in attachment to one or the other of the regions. We show how worker mobility affects the optimal tax schedule, and address the spatial distribution of the population under optimal taxation. We examine a special case in which it is possible to make statements about the second‐best distribution of population.
Expression of OePIP2.1 aquaporin gene and water relations of Olea europaea twigs during drought stress and recovery
Authors: Secchi F. , Lovisolo C. , Schubert A.
Published: March 2007

To investigate the effects of drought and recovery on the transcript level of OePIP2.1 (a PIP2 aquaporin gene) in twigs, 2‐year‐old olive trees were subjected to a drought/rewatering treatment (the irrigation was suspended for a period of 4 weeks and restored for the following 4 weeks). Twig water potential, twig hydraulic resistance and incidence of embolisation in the twig were measured in parallel with gene expression under both drought stress and the following recovery. During drought, a decrease in twig water potential, an increase in twig hydraulic resistance and an increase in the extent of xylem vessel embolisation was observed in parallel with a decrease of aquaporin gene expression. Opposite trends were recorded during rewetting. A speculation on a possible contribution of OePIP2.1 aquaporin to modulate shoot embolism during drought and recovery is proposed.
Pythium species associated with cavity spot on carrots in Norway
Authors: Hermansen A. , Herrero M.‐L. , Gauslaa E. , Razzaghian J. , Nærstad R. , Klemsdal S.S.
Published: March 2007

Carrot roots with cavity spot lesions from eight different counties in Norway were sampled and Pythium species were isolated on selective medium. Pythium spp. were characterised morphologically and by species‐specific PCR. Laboratory experiments with inoculations of carrot roots were performed. A total of 130 isolates out of 230 Pythium‐like isolates tested with PCR were identified as pathogenic species of Pythium. These were P. intermedium (29%), P. sulcatum (23%), P. sylvaticum (16%), P. violae (15%) and a possible new Pythium species designated P. ‘vipa’ (18%). There were some differences between geographical regions and ages of cavities regarding the frequency of the different species isolated. When rating sunken lesions in the laboratory inoculation experiments, P.‘vipa’ was the most aggressive and P. violae the least aggressive species. P. intermedium and P.‘vipa’ caused more discolouration of the infected carrot tissue than the other species. The importance of the different Pythium spp. as agents of cavity spot in Norway is discussed.
Asymmetric Wolf–Rayet winds: implications for gamma-ray burst afterglows
Authors: Eldridge J. J.
Published: March 2007

Recent observations of Wolf–Rayet (WR) binaries WR151 and WR155 infer that their stellar winds are asymmetric. We show that such asymmetries can alter the stellar-wind bubble structure, bringing the wind-termination shock closer to the WR star. If the wind asymmetry is caused by rotation, the wind density and distance to the wind-termination shock are both decreased along the rotation axis by a factor of a few for the observed equator-to-pole wind density ratio of WR151. If this asymmetry lasts until core-collapse the time taken to reach the wind-termination shock by supernova ejecta or a gamma-ray burst jet is reduced. This leads to a distorted structure of the supernova ejecta and makes it more likely a constant density environment is inferred from gamma-ray burst afterglow observations.
The ‘Meissner effect’ and the Blandford—Znajek mechanism in conductive black hole magnetospheres
Authors: Komissarov S. S. , McKinney Jonathan C.
Published: March 2007

The expulsion of axisymmetric magnetic fields from the event horizons of rapidly rotating black holes has been seen as an astrophysically important effect that may significantly reduce or even nullify the efficiency of the Blandford–Znajek mechanism of powering the relativistic jets in active galactic nuclei and gamma-ray bursts. However, this Meissner-like effect is seen in the vacuum solutions of black hole electrodynamics, whereas the Blandford–Znajek mechanism is concerned with plasma-filled magnetospheres. In this Letter we argue that conductivity dramatically changes the properties of axisymmetric electromagnetic solutions – even for a maximally rotating Kerr black hole, the magnetic field is pulled inside the event horizon. Moreover, the conditions resulting in an outgoing Poynting flux in the Blandford–Znajek mechanism exist not on the event horizon but everywhere within the black hole ergosphere. Thus, the ‘Meissner effect’ is unlikely to be of interest in the astrophysics of black holes, at least not in the way this has been suggested so far. These conclusions are supported by the results of time-dependent numerical simulations that used three different computer codes. The test problems involve black holes with the rotation parameter ranging from a = 0.999 to a = 1. The pure electrodynamic simulations deal with the structure of conductive magnetospheres of black holes placed in a uniform-at-infinity magnetic field (Wald's problem) and the magnetohydrodynamic simulations are used to study the magnetospheres arising in the problem of disc accretion.
Conformational Stability of Aβ‐(25–35) in the Presence of Thiazolidine Derivatives
Authors: Campiglia Pietro , Esposito Cinzia , Scrima Mario , Gomez‐Monterrey Isabel , Bertamino Alessia , Grieco Paolo , Novellino Ettore , D'Ursi Anna Maria
Published: March 2007

In the attempt to identify a new lead compound able to modify the conformational preferences of the β‐amyloid peptides, a set of new compounds characterized by a thiazolidine ring linked to several different aryl moieties were synthesized. The ability of these compounds to prevent the β‐amyloid aggregation was evaluated using circular dichroism and nuclear magnetic resonance techniques. Molecular docking procedure allowed an interpretation of spectroscopic in the key of molecular interaction.
Engineering Metal Complexes of Chiral Pentaazacrowns as Privileged Reverse‐turn Scaffolds
Authors: Che Ye , Brooks Bernard R. , Riley Dennis P. , Reaka Andrea J. H. , Marshall Garland R.
Published: March 2007

Reverse turns are common structural motifs and recognition sites in protein/protein interactions. The design of peptidomimetics is often based on replacing the amide backbone of peptides by a non‐peptidic scaffold while retaining the biologic mode of action. This study evaluates the potential of metal complexes of chiral pentaazacrowns conceptually derived by reduction of cyclic pentapeptides as reverse‐turn mimetics. The possible conformations of metal complexes of chiral pentaazacrown scaffolds have been probed by analysis of 28 crystal structures complexed with six different metals (Mn, Fe, Co, Ni, Cu, and Zn). The solvated structures as well as the impact of complexation with different metals/oxidation states have been examined with density functional theory (DFT) calculation as explicitly represented by interactions with a single water molecule. The results suggest that most reverse‐turn motifs seen in proteins could be mimicked effectively with a subset of metal complexes of chiral pentaazacrown scaffolds with an RMSD of approximately 0.3 Å. Due to the relatively fixed orientation of the pendant chiral side groups in these metal complexes, one can potentially elicit information about the receptor‐bound conformation of the parent peptide from their binding affinities. The presence of 20 H‐atoms on the pentaazacrown ring that could be functionalized as well as the conformational perturbations available from complexation with different metals offer a desirable diversity to probe receptors for reverse‐turn recognition.
STRONTIUM ISOTOPE STRATIGRAPHY OF THE ASMARI FORMATION (OLIGOCENE ‐ LOWER MIOCENE), SW IRAN
Authors: Ehrenberg S. N. , Pickard N. A. H. , Laursen G. V. , Monibi S. , Mossadegh Z. K. , Svånå T. A. , Aqrawi A. A. M. , McArthur J. M. , Thirlwall M. F.
Published: March 2007

The Asmari Formation has been studied in the subsurface at the Bibi Hakimeh, Marun and Ahwaz oilfields and in an outcrop section from the Khaviz anticline. It consists of approximately 400 m of cyclic platform limestones and dolostones with subordinate intervals of sandstone and shale. The method of Sr‐isotope stratigraphy is well suited for dating these strata because of the rapid rate of change of marine 87Sr/86Sr during Asmari deposition (roughly 32‐18 Ma) and the common presence of well‐preserved macrofossils.

Profiles of age against depth in the four areas show a decrease from higher stratigraphic accumulation rates in the lower Asmari to lower rates in the middle to upper part of the formation. There is also a trend towards less open‐marine depositional conditions and increasing early dolomitization and anhydrite abundance above the lower part of the formation. These changes reflect the dynamics of platform progradation across the areas studied, from early deposition along relatively high accommodation margin to slope settings to later conditions of lower accommodation on the shelf top.

Ages of sequence boundaries are estimated from the age‐depth profiles at each locality, providing a framework for stratigraphic correlation. Asmari deposition began in early Rupelian time (34‐33 Ma) in the Bibi Hakimeh area, when the studied areas to the NW were accumulating basinal marl facies. Progradation of the platform across the Marun and Ahwaz areas took place in mid‐Chattian time (27‐26 Ma) and somewhat later (26‐25 Ma) in the more basinward Khaviz area. Depositional sequences have durations of 1‐3 Ma, whereas component cycles represent average time intervals of 100‐300 Ky.

Sr analyses of most dolomite, anhydrite and celestite samples plot close to or below the macrofossil age‐depth trend for each locality, indicating formation from waters preserving seawater 87Sr/86Sr approximately contemporaneous with or slightly younger than the time of sediment deposition. Local deviations from this trend are interpreted as indicating episodes of seepage‐reflux and also a contribution of Sr from non‐marine sources during formation of the Gachsaran cap rock anhydrite.
FLOW UNIT CLASSIFICATION FOR GEOLOGICAL MODELLING OF A HETEROGENEOUS CARBONATE RESERVOIR: CRETACEOUS SARVAK FORMATION, DEHLURAN FIELD, SW IRAN
Authors: Taghavi A. A. , Mørk A. , Kazemzadeh E.
Published: March 2007

Flow unit classifications can be used in reservoir characterization and modelling of heterogeneous carbonate reservoirs where there is uncertainty and variability in the distribution of porosity and permeability. A flow unit classification requires the integration of geological and petrophysical data, together with reservoir engineering and production data. In this study, cores and thin sections from the upper part of the Cretaceous Sarvak Formation at the Dehluran field, SW Iran, were studied to identify flow units which were then used in reservoir modelling.

Eight flow units were defined based on a classification of depositional environments and diagenetic processes and an evaluation of porosity and permeability. In lagoonal deposits, two flow units were distinguished in terms of dissolution effects (i.e. low or high values of vuggy porosity). In shoal/reef deposits, three flow units were distinguished in terms of cementation volumes and grain frequency. In open‐marine deposits, two flow units were identified with different degrees of dissolution; while intrashelf basinal deposits were characterized by a single flow unit with no observable reservoir potential.

Each flow unit was characterized by unique values of porosity, permeability, water saturation and pore throat distribution. Grain‐supported deposits from high energy depositional environments (shoals) had the highest porosities and permeabilities. However, these rocks were frequently cemented with a consequent reduction in porosity and permeability. By contrast, low permeability mud‐supported deposits had undergone dissolution, forming highly permeable flow units. Capillary pressure curves from mercury injection were used to determine the distribution of pore throat sizes and the pore characteristics of the flow units, and were used to give an indication of the productivity of each flow unit.

Flow units were modelled using a pixel‐based modelling tool. Modelled reservoir characteristics were mainly controlled by facies changes in the vertical direction, and by diagenetic variations in the horizontal direction. Input values for the geometry of the flow units were based on information from geological and diagenetic models of the reservoir, and from thickness maps of the flow units derived from well data.
PERMEABILITY ANISOTROPY DISTRIBUTIONS IN AN UPPER JURASSIC CARBONATE RESERVOIR, EASTERN SAUDI ARABIA
Authors: Sahin A. , Ali A. Z. , Saner S. , Menouar H.
Published: March 2007

Most classical reservoir engineering concepts are based on homogeneous reservoirs despite the fact that homogeneous reservoirs are the exception rather than the rule. This is especially true of carbonate reservoirs in the Middle East which are known to be highly heterogeneous. The realistic petrophysical characterization of these kinds of reservoirs is not an easy task and must include the study of directional variations of permeability. Such variation can be incorporated into engineering calculations as the square root of the ratio of horizontal to vertical permeability, a parameter known as the anisotropy ratio.

This paper addresses the distribution of anisotropy ratio values in an Upper Jurassic carbonate reservoir in the Eastern Province of Saudi Arabia. Based on whole core data from a number of vertical wells, statistical distributions of horizontal and vertical permeability measurements as well as anisotropy ratios were determined. The distributions of both permeability measurements and anisotropy ratios have similar patterns characterized by considerable positive skewness. The coefficients of variation for these distributions are relatively high, indicating their very heterogeneous nature.

Comparison of plots of anisotropy ratios against depth for the wells and the corresponding core permeability values indicate that reservoir intervals with lower vertical permeability yield consistently higher ratios with considerable fluctuations. These intervals are represented by lower porosity mud‐rich and/or mud‐rich/granular facies. Granular facies, on the other hand, yielded considerably lower ratios without significant fluctuations.
Making generalizations about vectors: Is there a physiology of “the mosquito”?
Authors: KLOWDEN Marc J.
Published: March 2007

Many of the generalizations made about mosquito behavior and physiology are based on the extensive research on the yellow fever mosquito, Aedes aegypti (L.). However, sufficient differences exist among the numerous species of mosquitoes that make many of these generalizations unwarranted. Some of the specific differences between Ae. aegypti and other mosquito species, particularly the important malaria vector Anopheles gambiae, are discussed.
Why pest management needs behavioral ecology and vice versa
Authors: ROITBERG Bernard D.
Published: March 2007

Behavior manipulation is becoming an accepted tactic in pest management, however, there are many ways in which the approach can be improved. In this review, I explain how and why insect behavioral response to various stimuli can vary dramatically under different conditions and that it is this variable response that must be understood before behavior manipulation becomes widely accepted in pest management programs. I propose that entomologists use concepts from behavioral ecology to manipulate pest behavior in a predictable manner. The key is to study behaviors that maximize fitness in natural environments and then exploit these behaviors in agriculture. I provide examples from a range of behavior manipulation tactics, including use of attracticides, kairomone‐mediated biological control, use of marking pheromones, and push‐pull manipulation.
New record of Trisuloides rotundipennis Sugi (Lepidoptera: Noctuidae: Pantheinae) from Korea
Authors: HAN Hui Lin , LI Cheng‐De , BYUN Bong‐Kyu
Published: March 2007

In the present study, a noctuid species, Trisuloides rotundipennis Sugi, is reported for the first time from Korea. External characteristics and female genitalia and habitus of this species are illustrated, and information on host plant and distributional range is provided.
Seasonal phenology and stage‐specific parasitism of the apple ermine moth, Yponomeuta malinellus Zeller, in Korea
Authors: LEE Jang‐Hoon , PEMBERTON Robert W.
Published: March 2007

The apple ermine moth, Yponomeuta malinellus Zeller (Lepidoptera: Yponomeutidae), is a tent caterpillar that feeds on Malus spp. in Korea. Populations of the moth in native areas appeared to be regulated by the assemblage of parasitoids. Phenological associations between host stages and parasitoids, susceptible stage(s) of the host for each parasitoid, and stage‐specific parasitism were studied. The egg larval parasitoid Ageniaspis fuscicollis (Dalman) had highest parasitism of first instar larvae (24%), with 14% parasitism of other larval stages. Dolichogenidea delecta (Haliday) was recovered from all larval instars with the highest parasitism rate of second instar larvae (20.1%), followed by 19.9% parasitism of mid‐larval hosts. Herpestomus brunicornis Gravenhorst was reared from second instar larvae through to pupal collection, and had the highest parasitism rate (29.9%) at the pupal stage. The larval pupal parasitoid Zenillia dolosa (Meigen) was recovered from mid‐larval to pupal stages with the highest parasitism rate (5.5%) occurring in third to fourth instar larvae. The host stages for developing A. fuscicollis completely overlap with those of D. delecta, and with those of H. brunicornis to some degree. A statistically significant negative correlation exists between A. fuscicollis and these dominant parasitoids, indicating competitive interaction within the host.
Receptor‐mediated endocytosis of lipid and lipophorin by the larval fat body, adult ovary and testis in the wax moth Galleria mellonella
Authors: JUNG Eun‐Suk , YUN Hwa‐Kyung
Published: March 2007

Lipophorin (Lp) in the hemolymph of insects is known to selectively deliver lipids from sites of absorption or synthesis to sites of storage and utilization, such as the fat body, ovary and testis; however, no study regarding this has been reported in Galleria mellonella. In the present study, we examined the process by which Lp is taken up into the larval fat body, adult ovary and adult testis, and the transfer of lipid by Lp to these tissues in Galleria mellonella. To investigate the involvement of a receptor in Lp endocytosis, the larval fat body, adult ovary and adult testis were incubated for 1 h at room temperature with fluorescein isothiocyanate (FITC)‐Lp, FITC‐Lp plus unlabeled Lp, and FITC‐Lp plus suramin, a receptor endocytic inhibitor. The amounts of FITC‐Lp in the three tissues were significantly decreased in the presence of unlabeled Lp and suramin, indicating that endocytosis of Lp by the tissues is mediated by a receptor. To examine the transfer of lipid by Lp, the tissues were incubated for 1 h at room temperature with 1,1′‐dilinoleyl‐3,3,3′,3′‐tetramethylindocarbocyanine perchlorate (DiI)‐Lp, DiI‐Lp plus unlabeled Lp, and DiI‐Lp plus suramin. The transfer of lipid by Lp was inhibited in the presence of unlabeled Lp and suramin, which is consistent with a receptor‐mediated process. Our results show that the transfer process of lipid by Lp and uptake of Lp itself is by receptor‐mediated endocytosis.
Mechanical Properties of a Biodegradable Balloon-expandable Stent From Poly(L-lactide) for Peripheral Vascular Applications
Authors: Grabow Niels , Bünger Carsten M. , Sternberg Katrin , Mews Steffen , Schmohl Kathleen , Schmitz Klaus-Peter
Published: March 2007

Background: Biodegradable polymeric stents represent a competitive approach to permanent and absorbable metallic stents for vascular applications. Despite major challenges resulting from the mechanical properties of polymeric biomaterials, these stent concepts gain their attraction from their intrinsic potential for controlled biodegradation and facile drug incorporation. This study demonstrates the mechanical properties of a novel balloon-expandable slotted tube stent from PLLA. Method of Approach: Polymeric balloon-expandable slotted tube stents (nominal dimensions: 6.0×25mm) were manufactured by laser machining of solution cast tubes (I.D.=2.8mm, d=270±20μm) from biodegradable (1) PLLA and (2) PLLA/PCL/TEC. The stents were tested in vitro for their mechanical properties: deployment, recoil, shortening, collapse, and creep behavior under a static load of 100mmHg. In vitro degradation was performed in Sørensen buffer solution at 37°C. After 0∕2∕4∕8∕12∕24 weeks the remaining collapse stability and molecular weight were assessed. Results: All stents could be deployed by balloon inflation to 8bar at 1bar∕min (PLLA) and 3bar∕min (PLLA/PCL/TEC). Recoil, shortening, and collapse pressure were: 2.4%∕3.4%∕0.67bar (PLLA), and 8.8%∕2.3%∕0.23bar (PLLA/PCL/TEC). A static load of 100mmHg induced pronounced creep processes in the PLLA/PCL/TEC stent. The PLLA stent remained patent and exhibited no creep propensity. During in vitro degradation an increase in collapse pressure was observed (maxima at 12w: 1.3bar (PLLA), 0.7bar (PLLA/PCL/TEC)). At 24 weeks, molecular weight was decreased by 28% (PLLA), and 52% (PLLA/PCL/TEC). Conclusions: Stents fabricated from pure PLLA exhibited adequate mechanical properties. The slow permissible deployment rate, however, limits their potential application range and demands further development.
A Redundant Accelerometric Cluster for the Measurement of Translational and Angular Acceleration and Angular Velocity of the Head
Authors: Cappa Paolo , Patanè Fabrizio , Rossi Stefano
Published: March 2007

This paper reports the development and the experimental verification of a new helmet based on the use of a redundant array of accelerometers (ACs) which enables the measurement of angular velocity, angular acceleration and translational (a−g) component of the head during normal activity through an unconstrained workspace. Taking into account the outcome of a numerical simulation previously conducted, a lightweight foam bicycle helmet is equipped with ten biaxial, low-cost MEMS ACs. Validation tests were carried out by means of an instrumented pendulum, which allows the evaluation of the accuracy in the measurement of angular velocity, angular acceleration and (a−g) component over a range of 300deg∕s, 1300deg∕s2, and 7m∕s2. The effects induced by the sensor redundancy in the metrological performances of the helmet were also analyzed; in fact, by adopting an optimal selection criterion, some of the cemented ACs were ignored in the data processing, so that, in addition to the 20 axis configuration, also the clusters equipped by a total number of 18, 16, 14, or 12 sensing axes were analyzed and comparatively examined. The results clearly indicate that the redundancy reduces the effect of the noise level of the single transducers to the acceleration measurements; consequently the bandwidth of the device may be increased, because higher cutoff frequency can be chosen for the low pass filtering. The redundancy is also useful to reduce the angular velocity drift that is further decreased by adopting a drift compensation method. The results of the present experiments revealed that the presented helmet can be considered a viable tool in the measurement of head angular and translational acceleration for the assessment of equilibrium control capability. In case the evaluation of the angular velocity is required, time-limited routine clinical application (few seconds) must be performed due to the presence of relevant drift.
A First-Order Mechanical Device to Model Traumatized Craniovascular Biodynamics
Authors: Kohles Sean S. , Mangan Ryan W. , Stan Edward , McNames James
Published: March 2007

Mathematical models currently exist that explore the physiology of normal and traumatized intracranial function. Mechanical models are used to assess harsh environments that may potentially cause head injuries. However, few mechanical models are designed to study the adaptive physiologic response to traumatic brain injury. We describe a first-order physical model designed and fabricated to elucidate the complex biomechanical factors associated with dynamic intracranial physiology. The uni-directional flow device can be used to study interactions between the cranium, brain tissue, cerebrospinal fluid, vasculature, blood, and the heart. Solid and fluid materials were selected to simulate key properties of the cranial system. Total constituent volumes (solid and fluid) and volumetric flow (650ml∕min) represent adult human physiology, and the lengths of the individual segments along the flow-path are in accord with Poiseuille’s equation. The physical model includes a mechanism to simulate autoregulatory vessel dynamics. Intracranial pressures were measured at multiple locations throughout the model during simulations with and without post-injury brain tissue swelling. Two scenarios were modeled for both cases: Applications of vasodilation/constriction and changes in the head of bed position. Statistical results indicate that all independent variables had significant influence over fluid pressures measured throughout the model (p<0.0001) including the vasoconstriction mechanism (p=0.0255). The physical model represents a first-order design realization that helps to establish a link between mathematical and mechanical models. Future designs will provide further insight into traumatic head injury and provide a framework for unifying the knowledge gained from mathematical models, injury mechanics, clinical observations, and the response to therapies.
An Inexpensive Weight Bearing Indicator Used for Rehabilitation of Patients With Lower Extremity Injuries
Authors: Walczyk Daniel F. , Bartlet John P.
Published: March 2007

Background. Partial or nonweight bearing is a useful treatment prescribed by medical professionals (e.g., orthopedists, podiatrists) for patients rehabilitating from lower extremity injuries However, there is significant variability in patient conformance with the commonly used, but very imprecise “weight scale method.” Furthermore, the few commercially available load monitoring devices are rarely used because of their high cost. Method of Approach. As a simple and inexpensive alternative to current load monitoring methods and commercial products, a new medical device called a snap dome weight bearing indicator (WBI) has been developed to gently warn a patient when they have exceeded a limited percentage of their body weight on the recovering leg or foot. When installed in a patient’s shoe or medical appliance, the device does so by utilizing the reversible buckling phenomena of a snap dome to provide a tactile and audible feedback when the prescribed weight has been exceeded. To demonstrate the feasibility of this new device, the performance of (1) the snap dome by itself and (2) several WBI designs developed were tested. The most useful of the new designs include one incorporating a heel cup for loose fitting medical appliances and a podiatric off-loading indicator (POLI). In addition, a pilot study and manufacturing cost analysis of the POLI device were performed to investigate patient usability and affordability issues. Results. The particular four-leg snap domes used in device prototypes performed quite well with regards to buckling load consistency between domes, the linearity of buckling load by stacking domes in a parallel arrangement, and buckling load repeatability of a single dome. The performance of each WBI prototype was tested with regards to load transfer, tactile, and audible feedback to the patient, patient comfort, and ease of installation. Prototype performance was generally very good or excellent except for the POLI device, which does not provide sufficient tactile or audible feedback for many patients. A costing analysis of the POLI device suggests that it can be manufactured in the U.S. for around one dollar. Conclusions. The generally positive results from performance testing of commercially available snap domes and WBI prototypes suggest that this new medical device will indeed be an inexpensive, yet effective conformance tool for orthopedists and podiatrists to use in prescribing partial or no weight bearing for a patient.
A Removable Precision Device for In-Vivo Mechanical Compression of Rat Tail Intervertebral Discs
Authors: Stinnett-Donnelly Justin M. , MacLean Jeffrey J. , Iatridis James C.
Published: March 2007

The rat tail intervertebral disc has emerged as an important model to examine the mechanisms for mechanically induced degeneration and remodeling. Previous methods used to apply high precision axial compressive loading to a rat tail intervertebral disc in vivo either required anesthesia, or the permanent mounting of a loading device to the animal, and were not well described in the literature. Therefore, a new device to apply compressive loading to the rat tail intervertebral disc was developed and validated. The rat tail compressive loading system utilized a pneumatically driven device weighing 18g, and was capable of delivering a 12.6N sinusoidal or square waveform at frequencies up to 1.0Hz. The system improved on previous methods in its modular construction, relative ease of fabrication, compatibility with existing tail model technology and overall cost effectiveness. The removable system eliminated the need for anesthesia and through a modular, cost effective, design allowed for the simultaneous loading of multiple animals. This system expanded the ability to accurately, ethically, and efficiently apply dynamic compressive loads to the rat tail intervertebral disc for extended periods of time in order to address questions related to disc mechanobiology.
Design of an Endoscopic Biopsy Needle With Flexural Members
Authors: Figueredo Stacy L. , Brugge William R. , Slocum Alexander H.
Published: March 2007

As a minimally invasive means of extracting a tissue sample from a patient, current endoscopic biopsy needles generally do not preserve tissue histology and often require multiple attempts to obtain a tissue sample. This paper presents an endoscopic biopsy needle with internal flexures that enables tissue to enter the hollow needle and then be severed from the surrounding tissue when the needle is withdrawn. Using force-deflection and sample weight data from 10× scaled prototypes, variations of a flexural design captured 1.1grams of a tissue phantom on average, as compared to wedge-type designs that averaged 0.7-0.8grams. Sample mass exhibited an increase in mass as the feature angle decreased. Peak entrance forces (P2) for the flexure design were lower than for both wedge and extended wedge designs, and resistance forces (S2) were higher upon needle extraction. A low-angle (15 and 30deg) feature also produced a lower entrance friction (S1) and higher exit resistance (S2) compared with 45 and 60deg features. These results suggest that a biopsy needle with 15deg flexures could increase sample length and mass as well as sampling success rates for core biopsy procedures. Future tests of the flexural biopsy needle design will use this information to determine dimensions for laser cut features of 1× scale needles.
A Fluid Actuator for Thin-Film Electrodes
Authors: Arcand Benjamin , Shyamsunder Sudeep , Friedrich Craig
Published: March 2007

Background. Cochlear implants have become an accepted and successful treatment for profound sensorineural deafness in both children and adults. Essential to the effective and efficient localized stimulation of the auditory nerves, is the position of the implant electrode array stimulating sites within the scala tympani (ST). However, the small size, delicate internal structures and helical shape of the cochlear chambers complicate the matter of precise positioning of the implant electrode array. The design, fabrication process, and in vitro testing of a fluid actuator to steer a thin-film electrode array is presented. The application chosen to show feasibility is for a cochlear implant, however, the actuator might be used for cortical electrode arrays, for example. Method of Approach. The actuator functions by a change of internal fluid pressure within one or more flattened and curled polymer microtubes, expanding the highly elliptical cross section of each tube thereby stiffening it and causing a change in its curling radius. The straightening from an initially helical shape allows insertion of an attached electrode array into the basal end of the in vitro cochlea and as the insertion proceeds the pressure is decreased allowing the straightened electrode array to controllably return to its initial helical shape. The allowable envelope of the scala tympani of a guinea pig was determined from published data and the actuator was designed and fabricated accordingly. Results. Multiple actuators were fabricated and tested in vitro. The insertion tests helped to confirm the viability of using this type of actuation to facilitate the insertion of an electrode array into the ST. These tests were performed in a minimal amount of time and often on the first attempt. The actuator reached the furthest extent of the in vitro cavity and achieved a position adjacent to the modiolus. Conclusions. In vitro insertion tests show that the actuator can deliver a thin-film electrode array to a depth of more than one turn into the in vitro scala tympani within a few minutes under open-loop, manual control.
Design, Build, and Test of a Bobsled Simulator for Olympic Athletes
Authors: Wacker Mark , Erdman Arthur , Nickel Troy , Johnson Marie Guion
Published: March 2007

In a bobsled race, the difference between a winning and losing time can be less than thousandths of a second. These fractions of seconds are typically gained or lost at the start. The athletes must be keenly aware of their time and ability to accelerate the sled. Since bobsledders will only complete three or four runs a day during training, optimization of their mechanics and timing must all be done in a few training sessions. Also, the bobsled tracks are only available for a portion of the year and there is great demand for the facility, when seasonal temperatures allow the ice to be maintained. Unlike other sports they cannot rely upon “muscle memory,” where optimization is achieved through repetition. The “Bobsled Start Simulator” was designed to give bobsledders a tool to optimize the start variables without having to train on a track. The result was a high-tech treadmill with a computerized velocity control, a bobsled handle attached to a six-degree of freedom load cell and an adjustable attachment mechanism for mounting to the load cell and bobsled handle to the treadmill. The device was tested and proved successful in improving not only pushing force but also timing for six U.S. Olympic Team athletes. The work presented in this paper was completed in 2001 for the 2002 Olympics. At the time, the U.S. Olympic Bobsled Committee asked us to not make the information public until after the 2006 Olympics.
GRAVITATIONAL ORIGIN OF PHANTOM DARK ENERGY AND LATE COSMIC ACCELERATION
Authors: SRIVASTAVA S. K.
Published: March 2007

Here, dark energy is obtained using dual roles of the Ricci scalar (as a physical field as well as geometry). Dark energy density, obtained in this model, mimics phantom and the derived Friedmann equation contains a term [Formula: see text] with ρ de being the dark energy density and λ, called as cosmic tension. It is like brane-gravity inspired Friedmann equation, which arises here without using the brane-gravity theory. It is found that acceleration is a transient phenomenon for λ< 0, but for λ> 0 accelerated expansion is found to encounter the big-rip problem. It is shown that this problem can be avoided if the dark energy behaves as barotropic fluid and generalized Chaplygin gas simultaneously. Moreover, time for transition (from deceleration to acceleration of the universe) is derived as a function of equation of state parameter w de = p de /ρ de with p de being the pressure for dark energy fluid.
GRAND CANONICAL MIXED-STATE WIGNER FUNCTION IN A MAGNETIC FIELD: de HAAS–van ALPHEN OSCILLATIONS
Authors: MATERDEY TOMAS B.
Published: March 2007

Kohn proved in 1961 that interactions between electrons did not change the de Haas–van Alphen (dHvA) oscillation frequency for single electrons in the nondegenerate ground-state [Phys. Rev.123(4), 1242 (1961)]. It was proved recently that the pure-state Wigner function for an electron in a magnetic field carries this quantum and physical oscillation, and a quantum dielectric function, so the conductance can be calculated from the Wigner function [Int. J. Mod. Phys. B17(25), 4555 (2003)], [Int. j. Mod. Phys. B17(26), 4683 (2003)]. We present the first complete proof that at a finite temperature, the mixed-state Wigner function also shows dHvA oscillations with the same frequency. The Wigner function is a fundamental quantity, the fact that it carries observable physical information shows a great potential in the design of new quantum materials at the nanoscale.

The definition of the mixed-state Wigner function involves a grand canonical partition function (GCPF). Although dHvA is a well-known phenomenon, we present the first complete proof of it happening in degenerate mixed-states, based on a GCPF, which requires reconciliation between the dHvA experimental condition of a fixed number of particles and the GCPF's sum over number of particles. The GCPF is applied to one of the two spin species, while both the spin and spin-magnetic moment interaction are considered. We show that the contour integration in ω(ε) leads to a non-oscillatory term that is much larger than an oscillatory term, in the dHvA experimental conditions of high fields and low temperatures. This dominance of the non-oscillatory term explains the constancy of the chemical potential, allowing it to reduce to the Fermi energy in the limit of zero temperature. The obtained mixed-state Wigner function shows a fundamental period of oscillation with respect to B-1 that reduces to the Onsager's period for dHvA oscillations. This indicates that in mixed-states, dHvA oscillations depend on electrons of one spin species, this means the population of electrons of each spin species oscillates with the magnetic field.

The temperature dependence in the Wigner function will allow a combination of phase-space and thermodynamics information for mesoscopic structures, and the study of phase-space density holes such as BGK modes in the quantum domain.
THE MAGNETIC PHASE TRANSFORMATION, MAGNETIC ENTROPY CHANGE OF THE AS-CAST AND HEAT-TREATED Gd5Si2Ge2 ALLOYS
Authors: YANG HONG , XU CHAOQIANG , ZHI LINGYUN
Published: March 2007

The Gd 5 Si 2 Ge 2 alloy is a promising candidate for room temperature magnetic refrigeration. The magnetic phase transformations, magnetic entropy changes, and the microstructure of the arc-melted and heat-treated (1200°/1 h, quenching) Gd 5 Si 2 Ge 2 samples prepared using commercial purity Gd (lower than that of Ames) were compared in this work. X-ray diffraction (XRD) analysis identified that both arc-melted and heat-treated Gd 5 Si 2 Ge 2 are crystallized in the monoclinic Gd 5 Si 2 Ge 2-type structure. The M(T) curves showed that each sample presented two phase transformations near ~280 K and ~300 K and the saturated magnetization (Ms) increased after heat-treatment. According to the XRD and M(T) results, it is more reasonable to ascribe the two phase transformations in the M(T) curves to the different Gd sublattices than to the existence of Gd 5 Si 4-type phase. The phenomenal description for the two transformations in the M(T) curves is given. The magnetic entropy changes are -15.9 and -18.7 (J/kgK) under the 0 ~ 5 T magnetic field change for the as-cast and heat-treated Gd 5 Si 2 Ge 2 respectively, and comparable to that of the other literatures.
PHASE STRING THEORY FOR DOPED ANTIFERROMAGNETS
Authors: WENG ZHENG-YU
Published: March 2007

The recent developments of the phase string theory for doped antiferromagnets will be briefly reviewed. Such theory is built upon a singular phase string effect induced by the motion of holes in a doped antiferromagnet, which as a precise property of the t-J model dictates the novel competition between the charge and spin degrees of freedom. A global phase diagram including the antiferromagnetic, superconducting, lower and upper pseudogap, and high-temperature "normal" phases, as well as a series of anomalous physical properties of these phases will be presented as the self-consistent and systematic consequences of the phase string theory.
THERMODYNAMICS OF MECHANICAL OSCILLATIONS IN CRYSTALLINE SUPERLATTICES
Authors: JAĆIMOVSKI S. K. , ŠETRAJČIĆ J. P. , ZORIĆ V. M. , TOŠIĆ B. S. , SAJFERT V. D. , ILIĆ D. I.
Published: March 2007

Phonon spectra as well as thermodynamic characteristic of superlattice are analyzed using the method of two-time dependent Green's functions. Free and internal energy of the system as well as specific heat and entropy are found. The temperature behavior of superlattice specific heat is compared with specific heats of bulk structures and thin films. It was shown that at extremely low temperature, superlattice and film specific heats are practically equal and considerably lower than specific heat of bulk sample. The consequences of this fact to the thermal, conducting and superconducting properties of materials was discussed.
A STUDY OF STRESS RELAXATION RATE IN UN-IRRADIATED AND NEUTRON-IRRADIATED STAINLESS STEEL
Authors: GHAURI I. M. , AFZAL NAVEED , ZYREK N. A.
Published: March 2007

Stress relaxation rate in un-irradiated and neutron-irradiated 303 stainless steel was investigated at room temperature. The specimens were exposed to 100 mC, Ra-Be neutron source of continuous energy 2–12 MeV for a period ranging from 4 to 16 days. The tensile deformation of the specimens was carried out using a Universal Testing Machine at 300 K. During the deformation, straining was frequently interrupted by arresting the cross head to observe stress relaxation at fixed load. Stress relaxation rate, s, was found to be stress dependent i.e. it increased with increasing stress levels σ0 both in un-irradiated and irradiated specimens, however the rate was lower in irradiated specimens than those of un-irradiated ones. A further decrease in s was observed with increase in exposure time. The experiential decrease in the relaxation rate in irradiated specimens is ascribed to strong interaction of glide dislocations with radiation induced defects. The activation energy for the movement of dislocations was found to be higher in irradiated specimens as compared with the un-irradiated ones.
LIOUVILLE AND BOGOLIUBOV EQUATIONS WITH FRACTIONAL DERIVATIVES
Authors: TARASOV VASILY E.
Published: March 2007

The Liouville equation, first Bogoliubov hierarchy and Vlasov equations with derivatives of non-integer order are derived. Liouville equation with fractional derivatives is obtained from the conservation of probability in a fractional volume element. This equation is used to obtain Bogoliubov hierarchy and fractional kinetic equations with fractional derivatives. Statistical mechanics of fractional generalization of the Hamiltonian systems is discussed. Fractional kinetic equation for the system of charged particles are considered.
COPING WITH COMPLEXITY AND TURBULENCE - AN ENTREPRENEURIAL SOLUTION
Authors: MASON ROGER B.
Published: March 2007

This paper considers the adoption of an entrepreneurial orientation as a paradigm for companies operating in a complex and turbulent environment, viewing the environment as a complex and turbulent system in terms of chaos theory. Approaches suggested by chaos theory are compared with the entrepreneurial orientation to identify if such an orientation matches these suggested approaches.

Literature on chaos theory and entrepreneurship is compared, and a short case is presented, providing an illustration of how a company operating successfully in a complex and turbulent environment has used the principles of an entrepreneurial orientation.

The paper identifies considerable similarity between the management approaches suggested by chaos theory and the principles of the entrepreneurial orientation, indicating that chaos theory may provide the theoretical underpinning of the relationship between entrepreneurial orientation and turbulent environments. The case also shows how an entrepreneurial orientation has been successfully used in a complex and turbulent environment. The conclusion is that companies operating in a complex and turbulent environment could benefit from adopting an entrepreneurial orientation.