bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulation of motorcycle crashes with w-beam guardrail: Injury patterns and analysis
Authors: Ibitoye A B , Hamouda A M S , Wong S V , Umar R S Radin
Published: September 2009

This study uses computer simulations to study the impact of a motorcycle with the conventional w-beam guardrail. A three-dimensional computer simulation of a scaled hybrid III 50th-percentile male dummy mounted on a motorcycle and colliding with a w-beam guardrail is carried out. A multi-body model of the motorcycle and finite element model of the guardrail are developed using commercially available software. The simulation model is validated with a physical crash test conducted with same initial impact configurations. Impacts at speeds of 32, 48, and 60 km/h at an impact angle at 45° are considered. The predicted forces and accelerations are compared with the biomechanical limits for each body part and the risk of injury to the rider are evaluated. Speed was found to have a significant influence on the level of injury to the head, neck, chest, and femur. A significant reduction of the severity of injuries was found when the impact speed was reduced from 60 to 32 km/h. The accelerations experienced by the head and chest are found to be higher than safe levels for impact speeds of 48 and 60 km/h. The biomechanical limit for the right femur is exceeded at all three considered impact speeds. Neck injuries are also a concern, with the predicted tension values and neck bending extent being higher than the biomechanical limit for the 60 km/h impact speed. In light of these results, it is suggested that the design of guardrails should be reviewed with a focus on the safety of motorcyclists.
Mechanical response of infant brain to manually inflicted shaking
Authors: Couper Z , Albermani F
Published: September 2009

Shaken baby syndrome (SBS) is a contentious issue on both biomechanical and medical fronts, primarily due to a lack of understanding of the loading—injury relationship of infant shaking and the parameters that are deterministic to its nature. In order to address this lack, a finite element (FE) representation of a three month infant head was developed to apply kinematics derived from physical testing with an anthropomorphic infant surrogate. The FE mesh was derived from a three-dimensional geometric basis, allowing for mesh size grading in regions of high importance, and future patient-specific adaptation. Cerebrospinal fluid (CSF) was represented through static pressure equilibration in combination with a locally based squeezing resistance. The results of the simulation indicate that anteroposterior shaking will lead to specific patterns of brain matter motion, increased likelihood of focal axonal injury at contact locations and deep brain structures, and a capacity for the development of subdural hematomas (SDH) due to rupture of central bridging veins.
Automated identification of diabetes type-2 subjects with and without neuropathy using eigenvalues
Authors: See C K , Acharya U R , Zhu K , Lim T-C , Yu W-W , Subramaniam T , Law C
Published: September 2009

Diabetes is a disorder of metabolism and has been a leading healthcare burden throughout the world. The most typical form of diabetes is type-2 diabetes. It is commonly developed in adults of age 40 and older. The purpose of this study is to identify the plantar pressure distribution in normal subjects, diabetic type-2 subjects with neuropathy, and diabetic type-2 subjects without neuropathy. Foot scan images were obtained using the F-Scan (Tekscan USA) in-shoe measurement system. The eigenvalues were evaluated from principal-component analysis after performing continuous wavelets transformation (CWT). The eigenvalues of CWT in regions 5 and 7 had shown excellent p values of more than 95 per cent confidence level when subjected to an analysis-of-variance test. These parameters were then presented to an artificial neural network (ANN) and a Gaussian mixture model (GMM) for automatic classification. The results show that the ANN classifier performs better than the GMM and is able to identify the unknown class with a sensitivity of 100 per cent and a specificity of 72 per cent.
The Pathfinder image-guided surgical robot
Authors: Deacon G , Harwood A , Holdback J , Maiwand D , Pearce M , Reid I , Street M , Taylor J
Published: September 2009

This paper first describes the workflow of the Pathfinder image-guided surgical robot that has been designed to replace the stereotactic frame in neurosurgery, and then details the calibration stages employed in order to achieve submillimetre positioning accuracy of a tool tip. The process uses non-linear parameter identification techniques in conjunction with some procedures for camera calibration, which exploit the fact that the camera is mounted to a calibrated robot arm that executes precise motions.
Effect of long-term physiological activity on the long-term stem stability of cemented hip arthroplasty: in vitro comparison of three commercial bone cements
Authors: Bialoblocka-Juszczyk E , Cristofolini L , Erani P , Viceconti M
Published: September 2009

Long-term endurance of the cement mantle is fundamental for the survival of cemented hip prostheses. Current protocols to characterize bone cements are unsuitable to predict the actual clinical outcome. The aim of this study was to assess if it is possible to rank cement types having diverse clinical outcome by using a simplified in vitro physiological test. Composite femurs were implanted with identical stems (Lubinus-SPII), using different commercial cement types: CMW1 to represent cement with poor clinical outcome; Simplex-P and Cemex-RX to represent cements with a positive clinical outcome. Implanted femurs were subjected to a validated protocol that simulated a demanding but physiological loading spectrum. Inducible micromotions and permanent migrations were recorded throughout the test. After test completion, the cement mantles were sectioned and inspected with dye penetrants to quantify the fatigue-induced cracks. Micromotions did not differ significantly between cement types (possibly because a successful prosthesis was chosen that is very stable in the host bone). Significant differences were observed in terms of cement cracks: CMW1 induced significantly more numerous and larger cracks than Simplex-P and Cemex-RX; no difference was observed between Simplex-P and Cemex-RX. This indicates that this protocol: (a) can discriminate between ‘good’ and ‘bad’ cements and (b) yields consistent results when comparable cements are tested. The proposed protocol overcomes the limitations of existing standardized material tests for bone cements. New cements can be assessed in comparison with other cements with known (positive/negative) clinical outcome, tested with the same protocol.
In-vitro study on haemodiluted blood flow in a sinusoidal microstenosis
Authors: Kang M J , Ji H-S , Lee S J
Published: September 2009

In-vitro experiments were carried out to investigate the haemodynamic and haemorheological behaviours of haemodiluted blood flow through a microstenosis using a micro-particle image velocimetry (PIV) technique. The micro-PIV system employed in this study consisted of a two-head neodymium:yttrium-aluminium-garnet (Nd:YAG) laser, a cooled charge-coupled device camera, and a delay generator. To simulate blood flow in a stenosed vascular vessel, a polydimethylsiloxane (PDMS) microchannel with a sinusoidal throat of 80 per cent severity was employed. The width and depth of the microchannel were 100 μm and 50 μm, respectively. To compare the flow characteristics in the microstenosis, the same experiments were repeated in a straight microchannel under the same flow conditions. Using a syringe pump, human blood with 5 per cent haematocrit was supplied into the microstenosis channel. The flow characteristics and transport of blood cells through the microstenosis were investigated with various flowrates. The mean velocity fields were nearly symmetric with respect to the channel centreline. In the contraction section, the oncoming blood flow was accelerated rapidly, and the maximum velocity at the throat was almost 4.99 times faster than that of the straight microchannel without stenosis. In the diffusion section, the blood cells show rolling, deformation, twisting, and tumbling motion due to the flow-choking characteristics at the stenotic region. The results from this study will provide useful basic data for comparison with those obtained by clinical researchers.
Computational assessment of press-fit acetabular implant fixation: The effect of implant design, interference fit, bone quality, and frictional properties
Authors: Janssen D , Zwartelé R E , Doets H C , Verdonschot N
Published: September 2009

Patients suffering from rheumatoid arthritis typically have a poor subchondral bone quality, endangering implant fixation. Using finite element analysis (FEA) an investigation was made to find whether a press-fit acetabular implant with a polar clearance would reduce interfacial micromotions and improve fixation compared with a standard hemispherical design. In addition, the effects of interference fit, friction, and implant material were analysed. Cups were introduced into an FEA model of a human pelvis with simulated subchondral bone plasticity. The models were loaded with a loading configuration simulating two cycles of normal walking, during which contact stresses and interfacial micromotions were monitored. Subsequently, a lever-out simulation was performed to assess the fixation strength of the various cases. A flattened cup with good bone quality produced the lowest interfacial micromotions. Poor bone decreased the fixation strength regardless of the geometry of the cup. Increasing the interference fit of the flattened cup compensated for the loss of fixation strength caused by poor bone quality. In conclusion, a flattened cup did not significantly improve implant fixation over a hemispherical cup in the case of poor bone quality. However, implant fixation can be optimized by increasing interference fit and avoiding inferior frictional properties and low-stiffness implants.
The effect of vertebral material description during vertebroplasty
Authors: Chae S-W , Kang H D , Lee M K , Lee T S , Park J-Y
Published: September 2009

Vertebroplasty has attracted much attention as a medical treatment for the collapse of the spine by strengthening the vertebral body, correcting deformities, and relieving pain in patients through the injection of bone cement. The finite element method has become popular for analysing vertebroplasty. The numerical modelling of vertebrae under loading, as in many other cases of representing a composite bone with anatomically scattered properties through a simplified material model, entails difficulties in material assignment for analysis. The aim of this study is to compare and contrast material-assignment methods in the course of modelling through a tetrahedral meshing algorithm. In particular, the study seeks to contrast the element-wise material model with a uniform material assignment for trabecular bone and the bone—poly(methyl methacrylate) (PMMA) composite. The geometries of the vertebral body are constructed from computed tomography image data, which are obtained through scanning at intervals of 1 mm. The finite element models are constructed through a tetrahedral meshing algorithm. Various types of material assignment, which encompass the case of normal persons as well as the case of patients following vertebroplastic surgery, are analysed. The results clearly show that the oversimplification of the trabecular bone and the bone—PMMA composite body may lead to significant deviations in the assessment of the effectiveness of vertebroplastic surgery.
A novel tactile sensation measurement system for qualifying touch perception
Authors: Shao F , Chen X-J , Barnes C J , Henson B
Published: September 2009

The feel of films, wrapping paper, cardboards, and other packaging materials are important to the commercial success of foods. It is known from people's self-report studies that different surfaces provoke different subjective responses. There are several mechanical parameters, including friction, roughness, compliance, and thermal properties, which are important to the sensory feel. This paper describes the design, construction, and use of a multi-sensory measurement system for tactile sensation that can be used to evaluate the feel of different packaging materials. The experiments were conducted by sliding or pressing an artificial fingertip with embedded sensors against the surfaces of different samples which were fixed on a force table. The roughness, friction coefficients, compliance, and rate of change in the temperature were obtained. Forty volunteers were asked to touch and rate the samples by filling in questionnaires about how they felt. Strong correlations were found between people's feelings and the physical measurements.
Initial stability of type-2 tibial defect treatments
Authors: Frehill B , Crocombe A , Cirovic S , Agarwal Y , Bradley N
Published: September 2009

Treatment of proximal tibial defects is important to the survival of tibial prosthesis after total knee replacement. The objective of this finite element study was to determine a better understanding of the stresses produced by different treatment options for moderate uncontained type-2 defects. Methods analysed were the use of metal wedges, metal blocks, cement wedges, and cement blocks for the two defect angles 15° and 30°. The effect of a stem extension on the stress profiles was also analysed for each defect treatment and angle to establish the necessity of these extensions and consequent bone removal on the stability of the augments. Equivalent stresses in two regions of interest (ROIs) adjacent to the augments and shear stresses along the bone—cement interface of the defect were investigated. The lowest equivalent stresses were found in the metal block augment for both defect angles and ROIs. The highest equivalent stress in the ROIs and shear stress values along the bone—cement interface of the defect were found in the cement wedge augment model for both defect angles. Stem extensions were shown to increase equivalent stresses in the bone closer to the tibial stem but to decrease equivalent stresses closer to the cortical bone. The use of a stem extension significantly increased the shear stresses in the cement in all cases except in the metal block model. It is recommended that metal block augments are used without a stem extension in small-defect (i.e. peripheral defect angle of 15°) total knee replacement procedures.
Effect of high-pressure hydrogen exposure on wear of polytetrafluoroethylene sliding against stainless steel
Authors: Nakashima K , Yamaguchi A , Kurono Y , Sawae Y , Murakami T , Sugimura J
Published: September 2009

Mechanical components in hydrogen energy systems, such as a fuel cell vehicle and related infrastructures, will operate in high-purity hydrogen. Especially, some seals and valves in fuel cell vehicles should articulate against metal counterface within a pressurized hydrogen gas. However, the effect of high-pressure hydrogen gas on tribological behaviour of materials used in sliding surfaces has not been identified yet. In this study, unfilled polytetrafluoroethylene (PTFE) pins and 316L austenitic stainless-steel discs were exposed to high-pressure hydrogen gas and then the chemical and physical changes in their surface and the tribological characteristics were investigated.

The results of an X-ray photoelectron spectrometer analysis of the exposed stainless-steel surface indicated that metal oxides in the passive surface layer of stainless steel can be reduced significantly during the high-pressure hydrogen exposure. Increased metal contents of the stainless surface resulted in enhanced metal fluoride formation and subsequent development of a PTFE transfer film. Consequently, the exposed PTFE specimens showed lower specific wear rate when compared to the unexposed specimen.
Effects of surface topography on lubrication film formation within elastohydrodynamic and mixed lubricated non-conformal contacts
Authors: Krupka I , Hartl M , Svoboda P
Published: September 2009

This article focuses on the effects of surface topography modifications on lubrication film thickness within non-conformal lubricated contact. An optical test rig is used to study lubricant film behaviour between the flat surface of a chromium-coated glass disc and a steel ball. An array of micro-dents was produced on the ball surface to be able to demonstrate the effect of surface topography on lubrication film formation. Experiments were carried out under elastohydrodynamic and mixed lubrication using steady-state and transient operational conditions (start-up and reversal motion). The obtained results showed that surface texturing could represent a method of increasing the lubrication efficiency of rolling/sliding non-conformal contacts under operational conditions when the lubrication film is not able to separate rubbing surfaces. Lubricant emitted from the micro-dent helps in reducing asperities interaction. Moreover, the effect of surface micro-cavities has been observed within starved non-conformal contact under pure rolling conditions. An increase in film thickness within severe starved contact was localized upstream of the micro-dents, and was recently predicted numerically. This effect was further amplified as lubricant released from micro-dents remains on the ball surface and again enters into contact after the ball turns round.
Theoretical analysis of an infinitely wide rigid cylinder rotating over a grooved surface in hydrodynamic conditions
Authors: Marian V G , Predescu A , Pascovici M D
Published: September 2009

A theoretical model that evaluates the frictional properties of an infinitely wide rigid cylinder rotating over a grooved surface in a hydrodynamic lubrication regime is presented in this article. The parabolic approximation of the film thickness is used in order to analytically compute the pressure distribution in the fluid film. At the discontinuities of the grooved surface, the conservation of the flowrate is applied. The pressure distribution was also computed using a commercial CFD software. Different groove depths are tested using the two methods in order to establish whether the Reynolds equation is valid for low dimple aspect ratios. It is found that the Reynolds equation is not valid when the depth of the groove is comparable with its width. In the case where the width of the grooves is much larger than their depth, the obtained results (CFD and analytical) are perfectly similar. The load-carrying capacity and the friction force of the couple are also computed.
Nanoscratch resistance of human tooth enamel treated by Nd: YAG laser irradiation
Authors: Gao S , Huang S , Qian L , Yu H
Published: September 2009

The purpose of this study was to investigate the friction behaviour of human tooth enamel irradiated by Nd:YAG laser. Forty specimens were randomly divided into four groups, and received the Nd:YAG laser irradiation with different energy densities (without irradiation; 20, 40, and 80 J/cm2). Subsequently, nano-scratch tests were conducted on the treated enamel surfaces, with progressive loads from 0.1 to 80 mN. The morphologies of the treated enamel surfaces and the scratch scars were observed via a field emission scanning electron microscope and an AMBIOS XP-2 stylus profilometer. The results indicated that the Nd:YAG laser promoted slight morphological alterations under a lower energy density (20 J/cm2), but different morphologies occurred under a higher energy density (40 and 80 J/cm2). The irradiated enamel surfaces had inferior nano-scratch resistance, and the nano-scratch resistance decreased as the energy density increased. Nd:YAG laser irradiation decreased the nano-scratch resistance of the enamel. The main damage mechanisms of the irradiated enamel under nano-scratch consisted of brittle delaminations and formation of cracks.
Enhancement of journal bearings characteristics using novel elliptical grooves
Authors: Yen R-H , Chen C-Y
Published: September 2009

Most studies in the past employed straight-line herringbone-grooved journal bearings (HGJB) to improve their performance. However, no study has analysed numerically or experimentally the improved effects of curved grooves. This work utilizes novel elliptical grooves on a journal bearing and analyses the characteristics of the elliptical-grooved journal bearings (EGJB) numerically. Spectral element method is employed to analyse the curved geometries on a journal bearing. Load capacity, stability parameter, and total side leakage of the EGJB are compared with those of the HGJB. The comparison shows that the introduced EGJB have higher radial force, higher load capacity, and lower side leakage than the conventional HGJB. The optimum geometrical parameters of the groove of EGJB are investigated based on the maximum radial force. Finally, the load distributions of several grooved journal bearings are compared to elucidate how elliptical grooves enhance load characteristics. The load distribution along the axial direction in EGJB is more uniform than that in the HGJB. The low load near the bearing centre for the EGJB may be offset by the load away from the bearing centre; thus, a higher total load capacity than that of HGJB is achieved. On the other hand, the investigation, which increases the number of groove sides of the HGJB to resemble the elliptical grooves asymptotically, shows that the load capacities and side leakages of a grooved journal bearing with four sides and eight sides are close to those of the EGJB. Hence if manufacturing elliptical grooves is difficult, an alternative is to use multi-sided grooves with four sides. However, resembling an elliptical shape with grooves with more than four sides to increase load is unnecessary.
Use of the floating frame of reference formulation in large deformation analysis: Experimental and numerical validation
Authors: Nada A A , Hussein B A , Megahed S M , Shabana A A
Published: September 2009

The finite-element floating frame of reference (FFR) formulation is used, for the most part, in the small deformation analysis of flexible bodies that undergo large reference displacements. This formulation allows for filtering out systematically complex shapes associated with high frequencies that have no significant effect on the solution in the case of small deformations. The resulting low-order FFR models have been widely used to obtain efficient and accurate solutions for many engineering and physics applications. In this investigation, the use of the FFR formulation in the large deformation analysis is examined, and it is demonstrated that large deformation FFR models can be accurate in applications, where the deformation can be described using simple shapes as it is the case in robot system manipulators. In these cases, the standard finite-element FFR formulation must be used with non-linear strain—displacement relationships that account for the geometric non-linearities. The results obtained using the large deformation FFR models are compared with the results obtained using the large deformation absolute nodal coordinate formulation (ANCF), which does not allow for the use of linear modes. The ANCF models are developed using two different methods for formulating the elastic forces: the basic continuum mechanics approach (ANCF-BC) and the elastic line method (ANCF-EL). While the explicit Adams method can be used to obtain the numerical solution of the FFR model, two implicit integration methods are implemented in order to be able to obtain an efficient solution of the FFR and ANCF models. These implicit integration methods are the RADAU5 method and the Hilber—Hughes—Taylor (HHT) method. In the case of simple large deformation shapes, the simulation results obtained in this study show a good agreement between the FFR and the ANCF solutions. The results also show that, in the case of thin and stiff beams, the coupled deformation modes that result from the use of the ANCF-BC can be a source of numerical and locking problems, as reported in the literature. These ANCF-BC numerical problems can be circumvented using the implicit HHT integration method. Nonetheless, the HHT integrator does not capture high-frequency FFR axial modes which are necessary in order to obtain accurate solutions for high-speed rotating beams. In addition to the comparison with the ANCF solutions, experimental results of a forward dynamics model are used in this study to validate the large deformation FFR numerical solutions. The experimental set-up used in the validation of the numerical solutions is also described in this investigation.
Influence of tyre transience on anti-lock braking
Authors: Jaiswal M , Mavros G , Rahnejat H , King P D
Published: September 2009

Transient tyre characteristics can have significant influence in vehicle handling, particularly in anti-lock braking system (ABS), which involves wheel speed oscillations as a result of rapid changes in wheel brake pressure. Hitherto, ABS studies have been conducted mostly with straight-line motion. Relatively simple vehicle models have been used which cannot capture the interactions between non-linear handling dynamics and tyre behaviour. This article takes such interactions into account, using a non-linear 14-degrees-of-freedom vehicle model in combination with three different single-point contact tyre models with transient characteristics. They include a stretched-string-based model, a modified stretched-string model, and a contact mass model. The particularly demanding situation of combined cornering/ABS braking is investigated. It is shown that although all tyre models are of similar bandwidth (maximum frequency ≈ 15 Hz), the simple string tyre model fails to cope with the non-linearities involved in combined braking/cornering and predicts greater braking distances than the two more enhanced tyre models.
Buckling of laser-welded sandwich panels: Ultimate strength and experiments
Authors: Kolsters H , Zenkert D
Published: September 2009

This is the last of three companion papers which examine the elastic buckling and collapse of laser-welded sandwich panels with an adhesively bonded core and unidirectional vertical webs. By evaluation of the buckling stress in the first two papers it has been found that the buckling stress in compression parallel and normal to the webs typically reaches the proportional limit of the face plate and web material well before elastic buckling occurs. Hence, this paper presents an extension of the buckling model into the elastoplastic regime, with the aim of determining the ultimate (local) strength of the sandwich and of allowing experimental verification of the results. Using tangent modulus theory to ‘plasticize’ the elastic buckling model, the ultimate strength is evaluated for a sandwich configuration with high-strength steel face plates and a broad range of core moduli. The critical load predicted by the inelastic buckling model agrees well with non-linear finite element results and experimental values obtained from compression testing.
A procedure to optimize ship side structures for crashworthiness
Authors: Ehlers S
Published: September 2009

This paper presents a procedure to optimize a conceptual ship side structure from a crashworthiness point of view. As an example, this procedure is presented for a chemical or product tanker. A particle swarm optimization algorithm is used for the procedure. The classification society compliance of the conceptual design is checked through service loads that are applied to the ship's hull girder according to Det Norske Veritas. The collision simulations to assess the crashworthiness are carried out with the non-linear finite element solver LS-DYNA. An element length-dependent constant-strain failure criterion is chosen to simulate rupture. A numerical simulation of a stiffened plate serves to validate the material relation until failure. This material relation and failure definition makes possible an accurate prediction of the structural energy absorbed until inner plate rupture. The procedure is adjustable and applicable to other ship types and scenarios.
Development and evaluation of a surrogate ankle for use with a rotational traction measurement apparatus
Authors: Villwock M R , Meyer E G , Powell J W , Haut R C
Published: September 2009

Biofidelic devices are used in the automobile industry to assess injury risk during a vehicular accident. Similar biofidelic devices may have broad applicability in the field of sports injury prevention and could be used to enhance player safety. Ankle sprains constitute one of the most common sports injuries. Past studies have suggested that high rotational traction at the shoe—surface interface may increase the likelihood of lower-extremity injury. Researchers have assessed this risk by measuring the peak torque during an applied rotation. On the other hand, ankle sprains may be dependent upon the amount of strain developed in the ankle ligaments during rotation of the foot—ankle complex and not the magnitude of torque. The current study quantifies the torsional stiffness of the human foot—ankle complex based on cadaver experiments. The development of a surrogate foot—ankle complex is then detailed and compared with the human response. Finally, the results of a rotational traction study on a couple of football shoe—surface interfaces are presented using the surrogate ankle. The testing resulted in a new outcome variable, namely the peak twist of the ankle, that may allow assessment of the risk of injury to the ankle due to excessive rotational traction at the shoe—surface interface.
A three-dimensional model for the dynamics and hydrodynamics of rowing boats
Authors: Formaggia L , Mola A , Parolini N , Pischiutta M
Published: September 2009

This paper proposes a new model describing the dynamics of a rowing boat for general three-dimensional motions. The complex interaction between the different components of the rowers—oars—boat system is analysed and reduced to a set of ordinary differential equations governing the rigid motion along the six degrees of freedom. To treat the unstable nature of the physical problem, a rather simple (but effective) control model is included, which mimics the main active control techniques adopted by the rowers during their action.
On the Optimal Policy Structure in Serial Inventory Systems with Lost Sales
Authors: Huh Woonghee Tim , Janakiraman Ganesh
Published: September 2009

We study a periodically reviewed, serial inventory system in which excess demand from external customers is lost. We derive elementary properties of the vector of optimal order quantities in this system. In particular, we derive bounds on the sensitivity (or, more mathematically, the derivative) of the optimal order quantity at each stage to the vector of the current inventory levels. Our analysis uses the concept of L-natural-convexity, which was studied in discrete convex analysis and recently used in the study of single-stage inventory systems with lost sales. We also remark on how our analysis extends to models with capacity constraints and/or backordering.
Structural Logic of Intraorganizational Networks
Authors: Rank Olaf N. , Robins Garry L. , Pattison Philippa E.
Published: September 2009

In this study we examine the structural logic underlying complex intraorganizational networks. Drawing on different propositions about structural regularities in networks and using a comparative case study, we empirically investigate the structural logic of collaborative networks for the strategic decision process in two German corporations. In both organizations, data were gathered on cooperative relationships between all managers belonging to the top two management levels. We model structural regularities at the dyadic and the extradyadic level by applying a class of multivariate exponential random graph models. Our findings contribute to the existing literature in three ways: (1) Although networks are particularly likely to exhibit some types of structural regularities (e.g., reciprocity and transitivity), there are other relational forms such as cycles that seem to be of limited relevance. (2) Structural regularities are not limited to a single type of relation but may comprise instrumental and affective relational ties simultaneously. (3) An organization's formal cooperation structure has surprisingly limited influence on the structural patterns of cooperation, whereas friendship ties are embedded in managers' regular interaction patterns in many different ways.
The Interactive Effects of Mood and Trait Negative Affect in Group Decision Making
Authors: van Knippenberg Daan , Kooij-de Bode Hanneke J. M. , van Ginkel Wendy P.
Published: September 2009

Extending the growing interest in affect in work groups, we propose that groups with distributed information make higher quality decisions when they are in a negative rather than a positive mood, but that these effects are moderated by group members' trait negative affect. In support of this hypothesis, an experiment (N = 175 groups) showed that positive mood led to lower quality decisions than did negative or neutral moods when group members were low in trait negative affect, whereas such mood effects were not observed in groups higher in trait negative affect. Mediational analysis based on behavioral observations of group process confirmed that group information elaboration mediated this effect. These results provide an important caveat on the benefits of positive moods in work groups, and suggest that the study of trait × state affect interactions is an important avenue for future research.
Unlocking Knowledge Transfer Potential: Knowledge Demonstrability and Superordinate Social Identity
Authors: Kane Aimée A.
Published: September 2009

This study presents a conceptual model of when and how knowledge demonstrability and superordinate social identity impact the likelihood that organizations capitalize on their knowledge resources. To test the model, an experimental methodology was used in which a member transfers from one group to another, transmitting knowledge in the form of a production routine. As predicted, work groups unlocked the knowledge transfer potential arising from personnel movement more often when they shared a superordinate identity than when they did not share such an identity, and this identity effect was moderated by knowledge demonstrability. When knowledge was less demonstrable with concealed merits, it was more likely to transfer between groups that shared a superordinate identity, compared to groups that did not share such an identity. By contrast, when knowledge was more demonstrable with apparent merits, it was as likely to transfer between groups that shared a superordinate identity compared to groups that did not share such an identity. As predicted, superordinate identity induced knowledge consideration, the focusing of group attention on determining the value of another's knowledge. Mediated moderation analyses revealed that this process underlies knowledge transfer. Superordinate social identity induced thorough knowledge consideration, which was more important for recognizing the value of knowledge when its merits were concealed rather than apparent. Because the merits of many organizational routines and practices are concealed and superordinate identity appears to be a key to unlocking the knowledge transfer potential of less demonstrable knowledge, this study has important implications for managing knowledge resources.
Minding the Gaps: Understanding Technology Interdependence and Coordination in Knowledge Work
Authors: Bailey Diane E. , Leonardi Paul M. , Chong Jan
Published: September 2009

In this paper, we broaden the concept of interdependence beyond its focus on task to include technology, defining technology interdependence as technologies' interaction with and dependence on one another in the course of carrying out work. With technologies increasingly aiding knowledge work, understanding technology interdependence may be as important as understanding task interdependence for theories of organizing, but the literature has yet to develop ways of thinking about technology interdependence or its impact on the social dynamics of work. We define a technology gap as the space in a workflow between two technologies wherein the output of the first technology is meant to be the input to the second one. Using data from an inductive study of two engineering occupations (hardware engineering and structural engineering), we analyzed engineers' gap encounters (episodes in which a technology gap appeared in the course of action) and found striking differences in how engineers minded the gaps. Hardware engineers minded the gaps by coordinating technologies via “bridges” that automated data transfers between technologies. Structural engineers, in contrast, allowed technology gaps to persist even though traversing gaps consumed significant time and effort. Our findings highlight a difference between task and technology in the degree of coordination necessary for success. Managers in our study designed policies around technology interdependence and coordination not to manage technology most efficiently, but to manage work and workers in a manner consistent with occupational structures and industry constraints. We discuss the implications of our findings for theories of organizing work.
Quantitative computed tomographic assessment of the effects of 24 months of teriparatide treatment on 3D femoral neck bone distribution, geometry, and bone strength: Results from the EUROFORS study
Authors: Borggrefe Jan , Graeff Christian , Nickelsen Thomas N , Marin Fernando , Glüer Claus C
Published: September 2009

We studied the changes in bone distribution, geometry, and bone strength based on 3D quantitative computed tomography (QCT) of the femoral neck (FN) in subjects receiving teriparatide (TPTD). Fifty-two postmenopausal women with severe osteoporosis were analyzed. Patients were divided into three subgroups based on their prior treatment with osteoporosis drugs: treatment-naive (Tx-naive; n = 8), pretreated (pre-Tx; n = 12), and pretreated showing an inadequate response to treatment (inad. pre-Tx; n = 32). QCT scans were performed at baseline and after 6, 12, and 24 months of treatment and were analyzed with Mindways QCT-PRO BIT software. Minimum and maximum section modulus, buckling ratio (BR), and cross-sectional area (CSA) were calculated as measurements of bending strength, risk of buckling, and bone apposition, respectively. After 24 months of TPTD treatment, areal and volumetric FN BMD increased significantly by 4.0% and 3.0%, respectively, compared with baseline. Decreases in cortical volumetric BMD occurred in locations not adversely affecting minimum bending strength indicators. Cortical CSA increased by 4.3%, whereas total CSA remained unchanged over the study duration, indicating that endosteal but no periosteal growth was observed. Strength parameters for buckling did not change at 6 and 12 months but improved significantly at 24 months. Measures of bending strength showed a trend toward improvement. Changes tended to be larger in individuals at higher risk of buckling failure. Prior antiresorptive treatment may delay response to TPTD, but based on the small magnitude of the mostly insignificant changes at 6 months, this does not appear to lead to an interim phase of reduced bone strength. In summary, FN QCT provides a tool for detailed longitudinal investigation of bone strength indices in vivo for different loading modes, yields insight into underlying structural changes, and provides relevant mechanostructural information beyond dual-energy X-ray absorptiometry. Continuous TPTD treatment for 24 months improves FN bone strength parameters. © 2010 American Society for Bone and Mineral Research
A Hindu to His Body: The Reinscription of Traditional Representations
Authors: Zimmermann Francis
Published: September 2009

This paper is an attempt to put into a historical perspective the knowledge gathered over two centuries, a construction of the knowledge about the representations of the body in the Hindu world. In view of the critical history of Orientalist disciplines that has developed over the last few years we make a clear distinction between two periods in the construction of this knowledge. The representations of the body that emerged from reading, translating and interpreting classical writings of Hindu India, became the subject of two successive reinscriptions beginning in the second half of the nineteenth century. The analysis of these reinscriptions is presented in this paper.
Bodies Filled with Divine Energy: The Indian Dance Odissi
Authors: Schnepel Cornelia
Published: September 2009

This article is based on interviews made with gurus and dancers in Orissa, East India. The Odissi, a classical dance which stands at the centre of attention here, is a mixture of centuries-old traditions and relatively new influences, or even inventions. By discussing the dance′s history, its aesthetic qualities and, most importantly, the emic points of view of contemporary practitioners of the dance, it is shown that today′s Odissi is based on ideas and practices that stem as much from old Sanskrit writings and late-medieval temple practices as they do from the contemporary realms of popular Hinduism and tribal religion and art. For its practitioners, the dance represents a form of devotion to Jagannath, and Odisssi is thus understood as a spiritual dance through which a relationship between the god and his adherents is established or performed. While the attitude exhibited by dancers and audience alike is one of spirituality and bhakti, this spirituality and loving surrender can only be achieved through the bodily practice of the dance, which turns the presence of the deity into a somatic experience in which all the bodily senses are involved.
Hypopituitarism following traumatic brain injury: prevalence is affected by the use of different dynamic tests and different normal values
Authors: Kokshoorn Nieke E , Wassenaar Moniek J E , Biermasz Nienke R , Roelfsema Ferdinand , Smit Johannes W A , Romijn Johannes A , Pereira Alberto M
Published: September 2009

Objective

Traumatic brain injury (TBI) has emerged as an important cause of hypopituitarism. However, considerable variations in the prevalence of hypopituitarism are reported. These can partly be explained by severity of trauma and timing of hormonal evaluation, but may also be dependent on endocrine tests and criteria used for diagnosis of hypopituitarism.

Methods

Systematic review of studies reporting prevalence of hypopituitarism in adults ≥1 year after TBI focusing on used (dynamic) tests and biochemical criteria.

Results

We included data from 14 studies with a total of 931 patients. There was considerable variation in definition of hypopituitarism. Overall, reported prevalences of severe GH deficiency varied between 2 and 39%. Prevalences were 8–20% using the GHRH–arginine test (cutoff <9 μg/l), 11–39% using the glucagon test (cutoff 1–5 μg/l), 2% using the GHRH test (no cutoff), and 15–18% using the insulin tolerance test (ITT; cutoff <3 μg/l).

Overall, the reported prevalence of secondary adrenal insufficiency had a broad range from 0 to 60%. This prevalence was 0–60% with basal cortisol (cutoff <220 or <440 nmol/l), 7–19% using the ACTH test, and 5% with the ITT as first test (cutoff <500 or <550 nmol/l). Secondary hypothyroidism was present in 0–19% (free thyroxine) or 5–15% (thyroid-releasing hormone stimulation). Secondary hypogonadism was present in 0–29%.

Conclusion

The reported variations in the prevalence rates of hypopituitarism after TBI are in part caused by differences in definitions, endocrine assessments of hypopituitarism, and confounding factors. These methodological issues prohibit simple generalizations of results of original studies on TBI-associated hypopituitarism in the perspective of meta-analyses or reviews.
Doenças parasitárias em ruminantes no semi-árido brasileiro
Authors: Costa Valéria Medeiros de M. , Simões Sara V.D. , Riet-Correa Franklin
Published: September 2009

Arquivos de fichas clínicas de ruminantes ou amostras para diagnósticos recebidos pelo Hospital Veterinário da Universidade de Campina Grande, em Patos, Paraíba, de janeiro 2000 a agosto 2007, foram revisados para avaliar alguns aspectos epidemiológicos de doenças parasitárias de ruminantes na região semi-árida da Paraíba e estados vizinhos. A região apresenta precipitações médias anuais de aproximadamente 800mm, com chuvas irregulares concentradas em um período de 3-4 meses e uma temperatura média anual de 26°C. No período, 163 (5,31%) de 3.064 ruminantes foram afetados por alguma doença parasitária clinica. A doença parasitária mais frequente em caprinos e ovinos foi a helmitose gastrointestinal, principalmente a hemonchose, e caprinos foram mais afetados (6,24% dos casos diagnosticados) do que os ovinos (4,7% dos casos diagnosticados). A maior freqüência da doença nos caprinos pode estar associada à maior susceptibilidade destes ou devido a erros no tratamento, como a utilização da mesma dose para as duas espécies, o que para a maioria dos anti-antihelmínticos é insuficiente para caprinos. Bovinos tiveram uma baixa freqüência de helmintoses gastrintestinais (1 de 1.113 casos). Esta baixa freqüência deveu-se, provavelmente, ao sistema de criação no semi-árido, com baixa taxa de lotação, até um animal adulto por hectare a cada 13-16 hectare, e a permanência de bezerros (suscetíveis) com as mães (resistentes) por períodos de até um ano antes da desmama. A ocorrência de eimeriose em caprinos e ovinos foi de 0,76% dos casos, envolvendo apenas os animais jovens. Em bovinos a principal doença foi à tristeza parasitária com 14 surtos. Os surtos de tristeza ocorreram principalmente no final do período chuvoso em áreas de desequilíbrio enzoótico incluindo as montanhas e planaltos da região da Borborema, áreas irrigadas, e áreas das bacias do Rio do Peixe e Rio Piranhas. Nas áreas mais secas do semi-árido o Rhipicephalus (Boophilus) microplus não sobrevive durante o período de seca, mas, tristeza parasitária pode ocorrer quando no início do período chuvoso bovinos com carrapatos são introduzidos e esses se multiplicam durante o mesmo.
Perfil de sensibilidade microbiana in vitro de linhagens de Staphylococcus spp. isoladas de vacas com mastite subclínica
Authors: Medeiros Elizabeth S. , Mota Rinaldo A. , Santos Marcos V. , Freitas Manuela F.L. , Pinheiro Júnior José W. , Teles José Andreey A.
Published: September 2009

Objetivou-se com este estudo avaliar a sensibilidade antimicrobiana in vitro de 291 isolados de Staphylococcus spp. recuperados de amostras de leite de vacas com mastite subclínica, em 15 propriedades rurais localizadas na Região Metropolitana do Recife (A), Agreste (B) e Zona da Mata (C) do estado de Pernambuco. Dos 291 isolados, 170(58,4%) foram classificados como Staphylococcus coagulase negativa (SCN), 84(28,9%) como Staphylococcus aureus e 37(12,7%) como Staphylococcus coagulase positiva (SCP). Para o estudo do perfil de sensibilidade a antimicrobianos empregou-se a técnica de difusão em discos, foram avaliadas 16 drogas antimicrobianas utilizadas no tratamento das mastites. O antibiótico que apresentou melhor eficácia in vitro foi a associação entre neomicina + bacitracina + tetraciclina com percentuais de 98,4%, 99,3%, 89,7% para as regiões A, B e C, respectivamente. O antibiótico menos eficaz foi a ampicilina que apresentou 56,5% de resistência para as amostras da região A, 72,8% para a região B e 71,8% na região C. Os resultados obtidos mostram a necessidade da realização periódica de testes de sensibilidade in vitro, pois existem variações no perfil de sensibilidade e resistência que podem comprometer o tratamento do animal bem como os programas de controle da mastite bovina causada pelo Staphylococcus spp.