bluuebunny/crossref_metadata_2025 huggingface dataset:
Non‐invasive in vivo imaging of pancreatic β‐cell function and survival – a perspective
Authors: Leibiger I. B. , Caicedo A. , Berggren P.‐O.
Published: April 2011

A major problem in medical research is to translate in vitro observations into the living organism. In this perspective, we discuss ongoing efforts to non‐invasively image pancreatic islets/β‐cells by techniques, such as magnetic resonance imaging and positron emission tomography, and present an experimental platform, which allows in vivo imaging of pancreatic β‐cell mass and function longitudinally and at the single‐cell level. Following transplantation of pancreatic islets into the anterior chamber of the eye of mice and rats, these islets are studied by functional microscopic imaging. This imaging platform can be utilized to address fundamental aspects of pancreatic islet cell biology in vivo in health and disease. These include the dynamics of pancreatic islet vascularization, islet cell innervation, signal‐transduction, change in functional β‐cell mass and immune responses. Moreover, we discuss the feasibility of studying human islet cell physiology and pathology in vivo as well as the potential of using the anterior chamber of the eye as a site for therapeutic transplantation in type 1 diabetes mellitus.
Structural Changes in Marinated Fillets of Gilthead Sea Bream (Sparus aurata L.) during Vacuum Storage at Refrigerated Temperature
Authors: Ayala María D. , Gil Francisco , Vázquez José M. , Latorre Rafael , Ramírez Gregorio , López Octavio
Published: April 2011

Abstract:  Fillets of Sparus aurata were marinated in a mixture of salt (5.5%) and citric acid (48.9 g/kg) for 1 h, then vacuum packed and refrigerated for 1, 5, 16, and 21 d. Structural and ultrastructural parameters were evaluated in 6 specimens per time period. At day 1, the preservative solution appeared among the muscle fibers, thus increasing the interfibrillar spaces; cytoplasmic organelles were swollen and the sarcolemma‐endomysium appeared very altered and electron‐dense. At 5 to 10 d, the marinade solution had penetrated into the muscle fibers. The subsarcolemmal and intermyofibrillar spaces were dilated and granular lines of electron‐dense material appeared among the fibers. From 16 d, broad interfibrillar spaces were occupied by granular material derived from denatured sarcolemma‐endomysium and denatured myofibrils. Sarcomeres were already altered from initial stages, mainly at the I‐band level. The Z‐line also appeared disrupted. Such alterations were more severe from 10 d on, such that most of the sarcomeres showed disintegration of myofilaments.
Constitutive Smad linker phosphorylation in melanoma: a mechanism of resistance to transforming growth factor‐β‐mediated growth inhibition
Authors: Cohen‐Solal Karine A. , Merrigan Kim T. , Chan Joseph L.‐K. , Goydos James S. , Chen Wenjin , Foran David J. , Liu Fang , Lasfar Ahmed , Reiss Michael
Published: April 2011

Melanoma cells are resistant to transforming growth factor‐β (TGFβ)‐induced cell‐cycle arrest. In this study, we investigated a mechanism of resistance involving a regulatory domain, called linker region, in Smad2 and Smad3, main downstream effectors of TGFβ. Melanoma cells in culture and tumor samples exhibited constitutive Smad2 and Smad3 linker phosphorylation. Treatment of melanoma cells with the MEK1/2 inhibitor, U0126, or the two pan‐CDK and GSK3 inhibitors, Flavopiridol and R547, resulted in decreased linker phosphorylation of Smad2 and Smad3. Overexpression of the linker phosphorylation‐resistant Smad3 EPSM mutant in melanoma cells resulted in an increase in expression of p15INK4B and p21WAF1, as compared with cells transfected with wild‐type (WT) Smad3. In addition, the cell numbers of EPSM Smad3‐expressing melanoma cells were significantly reduced compared with WT Smad3‐expressing cells. These results suggest that the linker phosphorylation of Smad3 contributes to the resistance of melanoma cells to TGFβ‐mediated growth inhibition.
Dynamical Models: An Alternative or Complement to Mechanistic Explanations?
Authors: Kaplan David M. , Bechtel William
Published: April 2011

AbstractWhile agreeing that dynamical models play a major role in cognitive science, we reject Stepp, Chemero, and Turvey's contention that they constitute an alternative to mechanistic explanations. We review several problems dynamical models face as putative explanations when they are not grounded in mechanisms. Further, we argue that the opposition of dynamical models and mechanisms is a false one and that those dynamical models that characterize the operations of mechanisms overcome these problems. By briefly considering examples involving the generation of action potentials and circadian rhythms, we show how decomposing a mechanism and modeling its dynamics are complementary endeavors.
Dynamic contrast enhanced‐magnetic resonance imaging study of the nutrition pathway for lumbar intervertebral disk cartilage of normal goats
Authors: Du Heng , Ma Shao‐hui , Guan Min , Han Bo , Yang Guang‐fu , Zhang Ming , Liu Miao
Published: April 2011

Objective:  Study of the nutrition pathway for lumbar intervertebral disk cartilage of normal goats.

Methods:  Four lumbar intervertebral disks from each of eight 24‐month‐old goats (32 disks) were studied. After the goats had been anesthetized, signal intensity changes in the regions of interest (ROI) were observed by dynamic contrast enhanced magnetic resonance scanning. Before and after enhancement at the time points of 0, 5, 10, and 30 mins, and 1.0, 1.5, 2.0, 2.5, 3.0, and 3.5 hs, the ROI signal intensity was measured, and the time‐signal intensity curve and peak times analyzed.

Results:  Signal intensity in the vertebral bodies reached a peak at 0 min and decreased quickly thereafter. Signal intensity in the cartilage endplate zones reached the first peak at 30 mins and then went down slightly before increasing to a second peak at 2 hs. Signal intensity in the nuclei pulposus was negative within 5 mins, increased slowly to a peak at 2 hs, and declined thereafter.

Conclusion:  Nutrient metabolism of the lumbar intervertebral disks of normal goats occurs mainly through the cartilage end‐plate pathway.
Management of femoral diaphyseal nonunion after nailing with augmentative locked plating and bone graft
Authors: Gao Kan‐da , Huang Jian‐hua , Tao Jie , Li Fan , Gao Wei , Li Hao‐qing , Wang Qiu‐gen
Published: April 2011

Objectives:  Exchange nailing (EN) for aseptic femoral shaft nonunion is currently a standard orthopaedic treatment modality. However, according to recent studies there is occasionally a high failure rate when EN is used. In the present study, augmentative locked plating and bone graft was used as an alternative method for treating such cases. The purpose of this study was to report the treatment outcomes of selected femoral diaphyseal nonunions that had initially been treated by nailing.

Methods:  Thirteen patients with femoral diaphyseal nonunions underwent revision surgery with locked plate and bone graft. The inclusion criteria were: (a) nonisthmic nonunion; (b) atrophic/oligotrophic nonunion. All patients were managed by augmentative locked plating and bone graft.

Results:  All patients were followed up for a mean of 1.2 years (range, 1–2 years). After revision surgery all nonunions achieved bony union, the average union time being 7.5 months (range, 6–12 months). No major complications were observed in this case series.

Conclusion:  Augmentative locked plating is an effective and simple technique for treatment of femoral diaphyseal nonunion after nailing in selected cases.
Civilian gunshot extremity fractures with neurologic injury
Authors: Beidas Omar E , Rehman Saqib
Published: April 2011

Objective:  To verify the hypothesis that neurologic injuries are less prevalent in civilian gunshot injuries than that reported in the military literature, and are more likely to occur with concomitant fracture.

Methods:  In order to investigate the incidence and patient variables of gunshot injury with neurologic injury, a retrospective chart review was performed at a single urban trauma center over a five‐year period.

Results:  One thousand eight hundred and fifty‐one patients with gunshot injuries were treated at our center over the five year study period. Of these, 895 patients (48%) had involvement of at least one extremity and 382 (21%) had concomitant fractures. Seventy‐four had concomitant neurologic injury. There was a statistically significant difference of 14% (53/382) and 4% (21/513) (P < 0.0001) between the group with fracture (53 patients) and the group without fracture (21 patients), respectively, in the occurrence of neurologic insult.

Conclusion:  This incidence of neurologic injuries in civilian gunshot injuries is lower than that previously reported in the military population and the presence of a fracture is clearly an additional risk factor for neurologic injury.
Effective in-vivo utilization of lipid-based nanoparticles as drug carrier for carvedilol phosphate
Authors: Chakraborty Subhashis , Shukla Dali , Vuddanda Parameswara Rao , Mishra Brahmeshwar , Singh Sanjay
Published: April 2011

Objectives

Lipid nanoparticles as carrier for oral drug administration improve gastrointestinal solubility of poorly soluble drugs and thus enhance bioavailability. However, basic drugs may undergo rapid dissolution from such solid dispersions in the stomach and precipitate in the intestine due to their higher solubility in acidic medium. Therefore, the objective of this work was to study the enhancement in bioavailability of carvedilol phosphate (basic drug) by providing an alkaline gastric environment to drug-loaded solid lipid nanoparticles.

Methods

An alkaline gastric environment in rats was created and maintained with oral administration of an antacid suspension 5 min before and 30 min post dosing.

Key findings

The formulation administered orally exhibited enhanced bioavailability (∼27%) when compared with drug suspension and sustained release behaviour when compared with formulation under ideal gastric conditions. The enhanced bioavailability is due to the presence of lipid nanoparticles as drug carrier while the sustained-release characteristic may be attributed to the presence of antacid, which resulted in elevation of gastric pH and reduced the drug's solubility.

Conclusions

It may be concluded that although lipid nanoparticles can be instrumental in improving bioavailability, additional sustained release may be achieved by targeting intestinal release of basic drugs from lipid vehicles, which is possible by incorporating them into suitable enteric-coated formulations.
Inhibitory effect of phytoglycoprotein (24 kDa) on hepatocarcinogenesis in N-nitrosodiethylamine-treated ICR mice
Authors: Lee Jin , Lim Kye-Taek
Published: April 2011

Objectives

Hepatocellular carcinoma (HCC) is becoming one of the most prominent types of cancer in the world. For a long time in Korea Zanthoxylum piperitum DC (ZPDC) has been used in folk medicine to cure several cancers and inflammation. This study was designed to investigate whether ZPDC glycoprotein protected liver tissues against hepatocarcinogenic compounds such as N-nitrosodiethylamine (DEN).

Methods

To study the chemopreventive effect of ZPDC glycoprotein on hepatocarcinogenesis, ICR mice were injected intraperitoneally with DEN (50 mg/kg) for four weeks. We evaluated the indicators of liver tissue damage (the activity of lactate dehydrogenase (LDH) and alanine aminotransferase (ALT), and thiobarbituric acid-reactive substances (TBARS)), antioxidative enzymes (activity of superoxide dismutase (SOD) and glutathione peroxidase (GPx)), hepatocarcinogenic indicator (heat shock protein (HSP) 70) and hepatocarcinogenic signals (activity of nuclear factor (NF)-κB, cyclooxygenase (COX)-2, and matrix metalloproteinase (MMP)-9) using biochemical methods and immunoblot analysis.

Key findings

The results obtained from this study revealed that ZPDC glycoprotein (20 mg/kg) decreased the levels of LDH, ALT, and TBARS, whereas the activity of SOD and GPx increased in the DEN-treated ICR mice. With respect to the hepatocarcinogenic indicator and hepatocarcinogenic signals, HSP70, NF-κB, COX-2, and MMP-9 activity decreased.

Conclusion

The findings suggested that ZPDC glycoprotein prevented damage to liver tissue caused by DEN in the experimental mouse model.
Quick approximation of bivariate functions
Authors: Courrieu Pierre
Published: April 2011

This paper presents two experiments where participants had to approximate function values at various generalization points of a square, using given function values at a small set of data points. A representative set of standard function approximation models was trained to exactly fit the function values at data points, and models’ responses at generalization points were compared to those of humans. Then one defined a large class of possible models (including the best two identified predictors) and the class maximal possible prediction accuracy was evaluated. A new model of quick multivariate function approximation belonging to this class was proposed. Its prediction accuracy was close to the maximum possible, and significantly better than that of all other models tested. The new model also provided a significant account of human response variability. Finally, it was shown that this model is more particularly suitable for problems in which the visual system can perform some specific structuring of the data space. This model is therefore considered as a suitable starting point for further investigations into quick multivariate function approximation, which is to date an inadequately explored question in cognitive psychology.
Gaining knowledge via other minds: Children's flexible trust in others as sources of information
Authors: Robinson Elizabeth J. , Butterfill Stephen A. , Nurmsoo Erika
Published: April 2011

In five experiments, we examined 3‐ to 6‐year‐olds’ understanding that they could gain knowledge indirectly from someone who had seen something they had not. Consistent with previous research, children judged that an informant, who had seen inside a box, knew its contents. Similarly, when an informant marked a picture to indicate her suggestion as to the content of the box, 3‐ to 4‐year‐olds trusted this more frequently when the informant had seen inside the box than when she had not. Going beyond previous research, 3‐ to 4‐year‐olds were also sensitive to informants’ relevant experience when they had to look over a barrier to see the marked picture, or ask for the barrier to be raised. Yet when children had to elicit the informant's suggestion, rather than just consult a suggestion already present, even 4‐ to 5‐year‐olds were no more likely to do so when the informant had seen the box's content than when she had not, and no more likely to trust the well‐informed suggestion than the uninformed one. We conclude that young children who can ask questions may not yet fully understand the process by which they can gain accurate information from someone who has the experience they lack.
Rotordynamic Characteristics of a Five Pad, Rocker-Pivot, Tilting Pad Bearing in a Load-on-Pad Configuration; Comparisons to Predictions and Load-Between-Pad Results
Authors: Childs Dara W. , Carter Clint R.
Published: April 2011

Rotordynamic data are presented for a rocker-pivot tilting pad bearing in load-on-pad (LOP) configuration for (345–3101 kPa) unit loads and speeds from 4000 rpm to 13,000 rpm. The bearing was directly lubricated through a leading edge groove with five pads, 0.282 preload, 60% offset, 57.87 deg pad arc angle, 101.587 mm (3.9995 in.) rotor diameter, 0.1575 mm (0.0062 in.) diametral clearance, and 60.325 mm (2.375 in.) pad length. Measured results were reported for this bearing by Carter and Childs (2008, “Measurements Versus Predictions for the Rotordynamic Characteristics of a 5-Pad, Rocker-Pivot, Tilting-Pad Bearing in Load Between Pad Configuration,” ASME Paper No. GT2008-50069) in the load-between-pad (LBP) configuration. Results for the LOP are compared with predictions from a bulk-flow Navier–Stokes model (as utilized by San Andres (1991, “Effect of Eccentricity on the Force Response of a Hybrid Bearing,” STLE Tribol. Trans., 34, pp. 537–544)) and to the prior LBP results. Frequency effects on the dynamic-stiffness coefficients were investigated by applying dynamic-force excitation over a range of excitation frequencies. Generally, the direct real parts of the dynamic-stiffness coefficients could be modeled as quadratic functions of the excitation frequency, and accounted for by adding a mass matrix to the conventional [K][C] model to produce a frequency-independent [K][C][M] model. Measured added-mass terms in the loaded direction approached 60 kg. The static load direction in the tests was y. The direct stiffness coefficients Kyy and Kxx depend strongly on the applied unit load, more so than speed. They generally increased linearly with load, shifting to a quadratic dependence at higher unit loads. At lower unit loads, Kyy and Kxx increase monotonically with running speed. The experimental results were compared with predictions from a bulk-flow computational fluid dynamics analysis. Stiffness orthotropy was apparent in test results, significantly more than predicted, and it became more pronounced at the heavier unit loads. Measured Kyy values were consistently higher than predicted, and measured Kxx values were lower. Comparing the LOP results to prior measured LBP results for the same bearing, at higher loads, Kyy is significantly larger for the LOP configuration than LBP. Measured values for Kxx are about the same for LOP and LBP. At low unit loads, stiffness orthotropy defined as Kyy/Kxx is the same for LOP and LBP, progressively increasing with increasing unit loads. At the highest unit load, Kyy/Kxx=2.1 for LOP and 1.7 for LBP. Measured direct damping coefficients Cxx and Cyy were insensitive to changes in either load or speed, in contrast to predictions of marked Cyy sensitivity for changes in the load. Only at the highest test speed of 13,000 rpm were the direct damping coefficients adequately predicted. No frequency dependency was observed for the direct damping coefficients.
Dynamic Analysis for Robotic Integration of Tooling Systems
Authors: Li Yuwen , Xi Jeff , Mohamed Richard Phillip , Behdinan Kamran
Published: April 2011

This paper presents a dynamic analysis method for robotic integration of tooling systems. This development is motivated by the fact that many modern robotic automation tasks require large and heavy tooling systems. Yet, the integration of these tooling systems is usually done only considering the geometric constraints and weights without resorting to dynamic analysis. To resolve this problem, the equations of motion of a robot with inclusion of a tooling system are derived using the Lagrangian formulation. Three performance indices are introduced to evaluate the influence of the tooling system on the overall dynamics. The first index measures the energy consumption due to the tooling system’s motion, the second index evaluates the influence of the tooling system on the fundamental frequency, and the third one is the dynamic manipulability ellipsoid to measure the acceleration capability of the tool tip. Simulation studies are carried out to provide guidelines for the design of tooling systems. To demonstrate its effectiveness, the proposed method is applied to facilitate the tooling integration used in the robotic riveting for aerospace assembly.
Fine Tuning of Fuzzy Rule-Base System and Rule Set Reduction Using Statistical Analysis
Authors: Nazir Muhammad Babar , Wang Shaoping
Published: April 2011

Learning and tuning of fuzzy rule-based systems is the core issue for linguistic fuzzy modeling. To achieve an accurate linguistic fuzzy model genetic learning of initial rule base is introduced and evolutionary simultaneous tuning of nonlinear scaling factors and fuzzy membership functions (MFs) are employed. Novel evolutionary algorithm is applied for simultaneous optimization process due to its computational efficiency and reliability. To preserve the interpretability issue, linguistic hedges are utilized, which slightly modify the MFs. Interpretability issue is further improved by introducing the statistical based fuzzy rule reduction technique. In this technique, most appropriate rules are selected by computing the activation tendency of each rule. Further, focusing on granularity of partition, linguistic terms for input and output variables are modified and new reduced rule base system is developed. The proposed techniques are applied to nonlinear electrohydraulic servo system. Extensive simulation and experiment results indicate that proposed schemes not only improve the accuracy but also ensure interpretability preservation. Further, controller developed based on proposed schemes sustains the performance under parametric uncertainties and disturbances.
Coupling Simulation Algorithm of Dynamic Feature of a Plate With Particle Dampers Under Centrifugal Loads
Authors: Xia Zhaowang , Liu Xiandong , Shan Yingchun
Published: April 2011

Particle damper comprises granular particle enclosed in a container within a vibrating structure. The performance of particle damper is strongly nonlinear whose energy dissipation is derived from a combination of mechanisms including plastic collisions and friction between particles or particles and cavity walls. Particle damper containing suitable materials may be effective in a wider temperature range than most other types of passive damping devices. Therefore, it may be applied in extreme temperature environments where most conventional dampers would fail. It may also attenuate vibrations over a broad range of frequencies and cost less. Researches have indicated that particle damper could be a viable option for extreme environment applications. However, to date, no effort has come forward the can prove analytically or numerically that the particle damping is a viable solution for vibration suppression under centrifugal forces. In this paper, a coupling simulation algorithm based on the discrete element method and finite element method and the results of simulative studies aimed at understanding the effects of parameters of particle damper under centrifugal forces are presented. And the results show that the presented coupling simulation algorithm is effective and the analyses of dynamic feature of a plate with particle dampers under centrifugal loads are reasonable.
Vibration Analysis of Homogeneous Transradially Isotropic Generalized Thermoelastic Spheres
Authors: Sharma J. N. , Sharma N.
Published: April 2011

The exact free vibration analysis of stress free or rigidly fixed, thermally insulated/isothermal, transradially (spherically) isotropic thermoelastic solid sphere has been presented in context of nonclassical thermoelasticity. The transradially isotropic is also frequently referred as spherically isotropic in the literature. The basic governing equations of linear generalized thermoelastic, transradially isotropic, sphere have been uncoupled and simplified with the help of Helmholtz decomposition theorem. The formal solution of the coupled system of partial differential equations has been obtained by employing matrix Fröbenius method of extended series. The secular equations for the existence of possible modes of vibrations in the sphere have been derived by employing boundary conditions. The special cases of spheroidal (S-mode) and toroidal (T-mode) vibrations have also been deduced and discussed. It is found that the toroidal motion gets decoupled from the spheroidal one and remains independent of thermal variations and thermal relaxation time. In order to illustrate the analytical development, the numerical solution of secular equations for spheroidal motion (S-mode) is carried out with respect of magnesium and solid helium spheres. The lowest frequency and damping factor of vibrational modes have been computed with the help of MATLAB programming and the results are presented graphically. The study may find applications in aerospace, navigation, geophysics tribology, and other industries where spherical structures are in frequent use.
Microstructural Analysis of Thermite Welds
Authors: Redkin Konstantin V. , Garcia C. Isaac , DeArdo Anthony J.
Published: April 2011

Thermite welding is a simple and cost-effective process widely used in the field for rail repair and joining. Despite the well-accepted use of this technology, there is a major concern regarding the soundness of the weldments which are often found to be very sensitive to wear and cracking. In order to gain a better understanding of the structural factors that contribute to the performance behavior of thermite welds, systematic microstructural analyses of a series of welds was conducted. Of particular interest in this study was to carefully examine and compare the microstructure of the weld metal, heat affected zone (HAZ) and base metal of a series of thermite welded samples with different carbon content. The results of this work revealed the presence of proeutectoid cementite along the prior austenite grain boundaries at the three locations examined. In addition, microhardness evaluation of the welds revealed that substantial softening takes place in the HAZ, independent of the chemical composition of the rails or weld processing conditions. The presence of proeutectoid cementite along the prior austenite grain boundaries and the softening that takes place in the HAZ are two of the structural factors most likely responsible for the lower than expected wear behavior observed in welded or repaired rail steels. This paper will present and discuss the microstructural and processing factors associated with the formation of proeutectoid cementite and the causes leading to the observed softening.
The Cases for and Against Primary Suspension in Truck Design
Authors: Smith Roy E.
Published: April 2011

It has been held as axiomatic, almost since the inception of rail vehicles, that high speed operations demand the implementation of two-stage suspension in truck design. This paper presents factors which refute that idea. Through the analysis of both types of suspension — statically and dynamically — it is shown that the benefits that are thought to be attributable to two-stage suspensions are not confirmed by the facts. Design considerations for both single-stage and two-stage suspensions are also examined, and the non-performance issues are evaluated. It is concluded that there is no reason, from a high speed or safety performance standpoint, to implement a two-stage suspension, but that some practical — especially manufacturing — issues can dictate the use of it in certain applications. For many, if not most, applications, however, a single-stage suspension is the most desirable design choice.
Exploration of Enhanced Heat Dissipation Design for Brake Disc of High Speed Train
Authors: Yu Zhizhuang , Wang Yong
Published: April 2011

The function of the brake disc is to provide the ultimate guarantee of the safety of high speed trains. A braking unit includes two discs and two brake shoes. Braking performance depends on the pressure of the brake shoe and the friction between the disc and the shoe. When a train is braked, the brake disc endures a thermal load, which may affect the mechanical properties of the disc. If the thermal load exceeds the strength limit of the material, it could impact the safe running of the train. Therefore, the thermal load should be reduced as much as possible. Now the frictional surface of disc is plane and heat congregates easily in the surface area. The purpose of this paper is to explore a design for enhanced heat dissipation. A gas channel was used on the frictional surface to achieve the effect of heat dissipation. This design was analyzed by means of tribology and heat transfer theory. The distribution of gas flow was also researched. The temperature and stress field of the disc were simulated and analyzed. By the analysis it can be seen that the gas channel on the frictional surface of disc has a remarkable effect on heat dissipation in the brake disc.
Cognitive Engine Architecture for Railway Communications
Authors: Amanna Ashwin , Price Matthew J. , Bera Soumava , Gadhiok Manik , Reed Jeffrey H.
Published: April 2011

This paper discusses a railway specific cognitive radio that builds upon software defined radio (SDR) platforms to adapt the radio based situational awareness. Cognitive Radio incorporates artificial intelligence based algorithms with reconfigurable software-defined radios that enable automatic adjustments of the radio to improve performance and overcome obstacles the radio may confront in the field (i.e. environmental/man-made interference, occupying the same channel as a user with higher priority, etc.). This paper describes the Railway Cognitive Radio (Rail-CR) architecture and illustrates preliminary results in simulation. The proposed cognitive engine architecture consists of a case-based reasoned (CBR) and a Genetic Algorithm (GA) optimization routine. This paper discusses the overall cognitive architecture, the relationship between the CBR and the GA based on weighted objective functions, and metrics for assessing performance. Methods for case representation, quantifying similarity between cases histories, and techniques for managing case growth rate are presented as well as a proposed test bed SDR platform.
Shattered Rim Failure Modeling in Railroad Wheels
Authors: Sura Venkata S. , Mahadevan Sankaran
Published: April 2011

Shattered rim cracking, propagation of a sub-surface crack parallel to the tread surface, is one of the dominant railroad wheel failure types observed in North America. This crack initiation and propagation life depends on several factors, such as wheel rim thickness, wheel load, residual stresses in the rim, and the size and location of material defects in the rim. This paper investigates the effect of above mentioned parameters on shattered rim cracking, using finite element analysis and fracture mechanics. This cracking is modeled using a three-dimensional, multi-resolution, elastic-plastic finite element model of a railroad wheel. Material defects are modeled as mathematically sharp cracks. Rolling contact loading is simulated by applying the wheel load on the tread surface over a Hertzian contact area. The equivalent stress intensity factor ranges at the subsurface crack tips are estimated using unimodal stress intensity factors obtained from the finite element analysis and a mixed-mode crack growth model. The residual stress and wheel wear effects are also included in modeling shattered rim cracking.
An Approach to Wind Blow-Over Risk Reduction at Norfolk Southern Rwy
Authors: Rosenberger G. Walter , Dumont Brian J. , Pasta Corey T.
Published: April 2011

A paper written for and presented at the ASME 2010 Joint Rail Conference explored the science and methodology that BNSF Railway has taken to avoid wind-caused derailments.1 This paper further develops this topic with the approach Norfolk Southern Corp (NS) has taken. The foundational fluid flow dynamics and vehicle dynamics modeling and analysis are reviewed. The modeling included doublestack platforms loaded with empty boxes, trailer-on-flatcar (“piggyback”) equipment, high-cube boxcars, hoppers/coal gondolas, and multilevel (“autorack”) flatcars. The implementation of the modeling is outlined as a description of NS’ Speed Restriction System (SRS). The SRS uses real-time weather data and a lookup table of vehicle responses to provide the traffic controller (dispatcher) with recommended train speeds. Thoughts and suggestions on further development of a blowover risk reduction system are presented.
Development of Performance Requirements for a Rail Passenger Workstation Table Safety Standard
Authors: Muhlanger Michelle , Parent Daniel , Severson Kristine , Perlman Benjamin
Published: April 2011

The American Public Transportation Association’s (APTA) Construction and Structural committee, a railroad industry group, with the support of the Federal Railroad Administration (FRA) and the John A. Volpe National Transportation Systems Center (Volpe Center), is creating an industry safety standard for an energy absorbing table. Workstation tables in passenger trains are an increasingly popular seating configuration both in the United States and abroad. Although a well-attached table can provide convenience and compartmentalization for the occupant, there is a risk of abdominal injury during a rail accident. In Fact, there have been several accidents in the United States in which impacts with workstation tables have severely or fatally injured occupants. In 2006, in response to these injuries, an FRA sponsored program developed a prototype table that distributed load over a wider area of the abdomen and absorbed energy during a collision. This table design was tested with specialized anthropomorphic test devices (ATDs) instrumented to measure abdominal impact response and was shown to decrease injury risk compared to a baseline table design. Building on the knowledge gained in the development of the prototype table, the proposed standard requires force to the abdomen be limited while energy is absorbed by the table. Since manufacturers do not have access specialized ATDs, researchers proposed a two part testing requirement. The first part is a quasi-static test which measures the energy absorption capacity of the table with a maximum force level determined from testing with specialized abdominal ATDs. The second part is a sled test with a standard Hybrid III 50th percentile (HIII) ATD to assess compliance with occupant protection standards of compartmentalization and ATD injury assessment reference values (IARVs). This paper discusses the research performed to develop the performance requirement in the draft standard. Current injury measures, originally developed for the automotive industry, were examined to assess their applicability to workstation table impacts. Multiple Mathematical Dynamic Models (MADYMO) model simulations show the estimated injuries during a simulated sled test scenario. Several force-crush parameters were examined, including the initial stiffness of the force-crush curve, the plateau force and the target energy absorbed by the table, to determined the force-crush design characteristics of a table that are likely to reduce injury risk. The results of this study, combined with testing of the current prototype table described in a companion paper [1], led to a draft standard that will greatly improve the safety of workstation tables in passenger rail cars.
Collision Scenarios for Assessing Crashworthiness of Passenger Rail Equipment
Authors: Jacobsen Karina , Llana Patricia , Tyrell David
Published: April 2011

In June 2009, at the request of the Federal Railroad Administration (FRA), the Railroad Safety Advisory Committee established the Engineering Task Force (ETF). The ETF is comprised of government, railroads, suppliers, and labor organizations and their consultants. The ETF was tasked with recommending a process for assessing alternative Tier I passenger rail equipment, i.e., passenger equipment that is operated at speeds up to 125 mph on the general railroad system. The final product of the ETF is a document outlining criteria and procedures for demonstrating crashworthiness performance of passenger rail equipment built to alternative design standards and proposed for operation in the US. The results provide a means of assessing whether an alternative design compares to designs compliant with the FRA’s Tier I crashworthiness requirements. This paper focuses on the criteria and procedures developed for scenario-based requirements. The principle collision scenario describes the minimum train-level crashworthiness performance required in a train-to-train collision of an alternatively designed passenger train with a conventional locomotive-led passenger train. For cab car-led and MU locomotive-led operations, the impact speed is prescribed at 20 mph. For locomotive led operations, the impact speed is prescribed at 25 mph. Criteria for evaluating this scenario include intrusion limits for the passengers and engineer, and occupant protection measures. Other scenario-based requirements discussed in this paper include colliding equipment override, connected equipment override, and truck attachment.
Rotational Energy Harvesting Systems for Unpowered Freight Rail Cars
Authors: Nagode C. , Ahmadian M. , Taheri S.
Published: April 2011

Commonly, freight cars have no available source of electric power, thus preventing the use of any electronic devices that could improve convenience, performance, and efficiency of railroad operations. The devices introduced in this paper are motion-based electromagnetic energy harvesting systems. Similar in size and shape to a conventional damper or shock absorber, the systems are to be placed in the coil spring of the suspension to convert part of the energy usually wasted as heat into useful electric energy. This paper will present the design, development and testing of such devices. Tests of prototype devices on a shock dynamometer show that more than 20 Watts RMS of power can be produced with motions that can be encountered in train suspensions. The devices presented, although primarily developed for railroad applications, are not limited to use in freight cars and could be similarly applied in various vehicles with suspension like tractor-trailers, buses or automobiles.
Alzheimer’s Disease: The Challenge of the Second Century
Authors: Holtzman David M. , Morris John C. , Goate Alison M.
Published: April 2011

In the first of our State of the Art Review series, David M. Holtzman, John C. Morris, and Alison M. Goate explore the rapid pace of Alzheimer’s disease research and the challenges to translating research breakthroughs into clinical treatments.
Communicating Wirelessly with Our Bodies
Authors: Wang Wei
Published: April 2011

Wireless communication for biomedical devices is enabled by using the human body for signal transmission.
Science Translational Medicine
Podcast: 6 April 2011
Authors: Holtzman David M. , Smith Orla
Published: April 2011

A conversation with David M. Holtzman about the challenges of developing new treatments for Alzheimer's disease.
Relief from Zmp1-Mediated Arrest of Phagosome Maturation Is Associated with Facilitated Presentation and Enhanced Immunogenicity of Mycobacterial Antigens
Authors: Johansen Pål , Fettelschoss Antonia , Amstutz Beat , Selchow Petra , Waeckerle-Men Ying , Keller Peter , Deretic Vojo , Held Leonhard , Kündig Thomas M. , Böttger Erik C. , Sander Peter
Published: April 2011

Pathogenic mycobacteria escape host innate immune responses by blocking phagosome-lysosome fusion. Avoiding lysosomal delivery may also be involved in the capacity of mycobacteria to evade major histocompatibility complex (MHC) class I- or II-dependent T-cell responses. In this study, we used a genetic mutant ofMycobacterium bovisBCG that is unable to escape lysosomal transfer and show that presentation of mycobacterial antigens is affected by the site of intracellular residence. Compared to infection with wild-type BCG, infection of murine bone marrow-derived dendritic cells with a mycobacterial mutant deficient in zinc metalloprotease 1 (Zmp1) resulted in increased presentation of MHC class II-restricted antigens, as assessed by activation of mycobacterial Ag85A-specific T-cell hybridomas. Thezmp1deletion mutant was more immunogenicin vivo, as measured by delayed-type hypersensitivity (DTH), antigen-specific lymphocyte proliferation, and the frequency of antigen-specific gamma interferon (IFN-γ)-producing lymphocytes of both CD4 and CD8 subsets. In conclusion, our results suggest that phagosome maturation and lysosomal delivery of BCG facilitate mycobacterial antigen presentation and enhance immunogenicity.
Genetic Diversity of Cryptosporidium spp. from Bangladeshi Children
Authors: Hira Kirthi G. , Mackay Melanie R. , Hempstead Andrew D. , Ahmed Sabeena , Karim Mohammad M. , O'Connor Roberta M. , Hibberd Patricia L. , Calderwood Stephen B. , Ryan Edward T. , Khan Wasif A. , Ward Honorine D.
Published: April 2011

The genetic diversity of
Cryptosporidium
spp. from infected children was characterized for the first time in Bangladesh. Seven
C. hominis
and
C. parvum
subtype families (including a new family, IIm) and 15 subtypes (including 2 new subtypes) were identified. The dominance of specific families and subtypes was different from that in other countries.
Multilocus Sequence Typing of Bartonella henselae in the United Kingdom Indicates that Only a Few, Uncommon Sequence Types Are Associated with Zoonotic Disease
Authors: Chaloner Gemma L. , Harrison Timothy G. , Coyne Karen P. , Aanensen David M. , Birtles Richard J.
Published: April 2011

Bartonella henselae
is one of the most common zoonotic agents acquired from companion animals (cats) in industrialized countries. Nonetheless, although the prevalence of infections in cats is high, the number of human cases reported is relatively low. One hypothesis for this discrepancy is that
B. henselae
strains vary in their zoonotic potential. To test this hypothesis, we employed structured sampling to explore the population structure of
B. henselae
in the United Kingdom and to determine the distribution of strains associated with zoonotic disease within this structure. A total of 118
B. henselae
strains were delineated into 12 sequence types (STs) using multilocus sequence typing. We observed that most (85%) of the zoonosis-associated strains belonged to only three genotypes, i.e., ST2, ST5, and ST8. Conversely, most (74%) of the feline isolates belonged to ST4, ST6, and ST7. The difference in host association of ST2, ST5, and ST8 (zoonosis associated) and ST6 (feline) was statistically significant (
P
< 0.05), indicating that a few, uncommon STs were responsible for the majority of symptomatic human infections.
Multiplex PCR Allows Rapid and Accurate Diagnosis of Bloodstream Infections in Newborns and Children with Suspected Sepsis
Authors: Lucignano Barbara , Ranno Stefania , Liesenfeld Oliver , Pizzorno Beatrice , Putignani Lorenza , Bernaschi Paola , Menichella Donato
Published: April 2011

Sepsis is a major health problem in newborns and children. Early detection of pathogens allows initiation of appropriate antimicrobial therapy that strongly correlates with positive outcomes. Multiplex PCR has the potential to rapidly identify bloodstream infections, compensating for the loss of blood culture sensitivity. In an Italian pediatric hospital, multiplex PCR (the LightCycler SeptiFast test) was compared to routine blood culture with 1,673 samples obtained from 803 children with suspected sepsis; clinical and laboratory information was used to determine the patient infection status. Excluding results attributable to contaminants, SeptiFast showed a sensitivity of 85.0% (95% confidence interval [CI] = 78.7 to 89.7%) and a specificity of 93.5% (95% CI = 92.1 to 94.7%) compared to blood culture. The rate of positive results was significantly higher with SeptiFast (14.6%) than blood culture (10.3%) (
P
< 0.0001), and the overall positivity rate was 16.1% when the results of both tests were combined.
Staphylococcus aureus
(11.6%), coagulase-negative staphylococci (CoNS) (29.6%),
Pseudomonas aeruginosa
(16.5%), and
Klebsiella
spp. (10.1%) were the most frequently detected. SeptiFast identified 97 additional isolates that blood culture failed to detect (24.7%
P. aeruginosa
, 23.7% CoNS, 14.4%
Klebsiella
spp., 14.4%
Candida
spp.). Among specimens taken from patients receiving antibiotic therapy, we also observed a significantly higher rate of positivity of SeptiFast than blood culture (14.1% versus 6.5%, respectively;
P
< 0.0001). On the contrary, contaminants were significantly more frequent among blood cultures than SeptiFast (
n
= 97 [5.8%] versus
n
= 26 [1.6%]), respectively;
P
< 0.0001). SeptiFast served as a highly valuable adjunct to conventional blood culture in children, adding diagnostic value and shortening the time to result (TTR) to 6 h.
Development and Evaluation of a Loop-Mediated Isothermal Amplification Method for Rapid Detection of Anaplasma ovis
Authors: Ma Miling , Liu Zhijie , Sun Ming , Yang Jifei , Guan Guiquan , Li Youquan , Luo Jianxun , Yin Hong
Published: April 2011

Anaplasma ovis
is an intraerythrocytic rickettsial pathogen of small ruminants. Loop-mediated isothermal amplification (LAMP) is a nucleic acid detection method in which the target DNA can be efficiently amplified with high specificity and sensitivity under isothermal conditions. In this study, a LAMP method was developed for the specific detection of
A. ovis
, using LAMP primers designed on the basis of the major surface protein 4 gene. LAMP was performed at 65°C for 30 min. Its specificity was confirmed by successful amplification of several
A. ovis
isolates and through EcoRI restriction analysis of LAMP products. No cross-reactivity with the
A. marginale
Lushi isolate,
Mycoplasma mycoides
subsp.
capri
,
Chlamydophila psittaci
,
Theileria ovis
,
T. luwenshuni
,
T. uilenbergi
, or the
Babesia
sp. Xinjiang isolate was observed. Detection using the LAMP method was compared with that using conventional PCR in 227 field samples; LAMP demonstrated a sensitivity of 95.45%. In summary, LAMP is a specific, sensitive, and rapid test for the diagnosis of
A. ovis
infection, with the potential to be standardized as a detection method for
A. ovis
in areas of endemicity.
Rapid Differentiation of Mixed Influenza A/H1N1 Virus Infections with Seasonal and Pandemic Variants by Multitemperature Single-Stranded Conformational Polymorphism Analysis
Authors: Pajak Beata , Stefanska Ilona , Lepek Krzysztof , Donevski Stefan , Romanowska Magdalena , Szeliga Magdalena , Brydak Lidia B. , Szewczyk Boguslaw , Kucharczyk Krzysztof
Published: April 2011

Mixed infections of a single host with different variants of influenza A virus are the main source of reassortants which may have unpredictable properties when they establish themselves in the human population. In this report we describe a method for rapid detection of mixed influenza virus infections with the seasonal A/H1N1 human strain and the pandemic A/H1N1/v strain which emerged in 2009 in Mexico and the United States. The influenza virus A/H1N1 variants were characterized by the multitemperature single-stranded conformational polymorphism (MSSCP) method. The MSSCP gel patterns of hemagglutinin gene fragments of pandemic A/H1N1/v and different seasonal A/H1N1 strains were easily distinguishable 2 h after completion of reverse transcription-PCR (RT-PCR). Using the MSSCP-based genotyping approach, coinfections with seasonal and pandemic variants of the A/H1N1 subtype were identified in 4 out of 23 primary samples obtained from patients that presented with influenza-like symptoms to hospitals across Poland during the 2009-2010 epidemic season. Pandemic influenza virus strain presence was confirmed in all these primary samples by real-time RT-PCR. The sensitivity level of the MSSCP-based minor genetic variant detection was 0.1%, as determined on a mixture of DNA fragments obtained from amplification of the hemagglutinin gene of seasonal and pandemic strains. The high sensitivity of the method suggests its applicability for characterization of new viral variants long before they become dominant.