bluuebunny/crossref_metadata_2025 huggingface dataset:
Low Oxygen Tension and Relative Defined Culture Medium with 3, 4‐Dihydroxyflavone are Beneficial for Yak–Bovine Interspecies Somatic Cell Nuclear Transfer Embryo
Authors: Xiong X , Li J , Wang L , Zhong J , Zi X , Wang Y
Published: October 2013

Contents

With an aim to improve the efficiency of yak–bovine interspecies somatic cell nuclear transfer (iSCNT), this study investigated the effect of different culture systems on the development, quality and gene expression profile of yak–bovine iSCNT embryo. Reconstructed embryos were cultured in modified synthetic oviductal fluid (mSOF) or relative defined culture medium (RDCM) with 5% or 20% oxygen tension. Relative mRNA abundance of Oct‐4, IFNT, IGF‐2, Bax, GPX‐1, SOD‐1, CAT and GSS was analysed in blastocysts with qRT‐PCR. The blastocyst formation rate in RDCM under 5% oxygen tension was significantly higher than that under 20% oxygen tension (P < 0.05). The total cell number of blastocyst derived from RDCM with 20% oxygen tension was lower than that of other groups, whereas the group of RDCM with 5% oxygen tension showed a beneficial effect on apoptosis index and tolerance to cryopreservation (P < 0.05). However, under the same oxygen tension, the mRNA abundance of IFNT of RDCM groups was higher than that of the mSOF groups. In addition, high oxygen tension during in vitro culture (IVC) with RDCM significantly increases the mRNA expression of oxidative stress‐related genes (GPX‐1, SOD‐1, CAT and GSS) (P < 0.05). 3, 4‐Dihydroxyflavone (DHF) during high oxygen tension was able to improve the cloned blastocyst formation rate in RDCM (P < 0.05). These results for the first time showed that low oxygen tension and RDCM could improve the developmental competence and quality and alleviate the oxidative stress for yak–bovine iSCNT embryo during IVC.
Evaluation of the performance of the microscopic observation drug susceptibility assay for diagnosis of extrapulmonary tuberculosis in China: A preliminary study
Authors: Huang Zikun , Xiong Guoliang , Luo Qing , Jiang Bixia , Li Weitin , Xu Xiaomeng , Li Junming
Published: October 2013

Background and objective

While commercial liquid culture techniques have emerged over 20 years ago, Ziehl–Neelsen (ZN) smear microscopy remains the primary method for diagnosis of tuberculosis (TB) in China because of cost considerations. The microscopic observation drug susceptibility (MODS) assay has been evaluated in different parts of the world to determine whether it can give comparable result to commercial liquid techniques. However, most reports detail evaluation of sputum specimens. This study evaluated the performance of MODS assay for detection of Mycobacterium tuberculosis in extrapulmonary specimens in a Chinese population.

Methods

A total of 173 samples, including pleural fluid (n = 112) and cerebrospinal fluid (CSF, n = 61) samples, were collected from patients suspected to have extrapulmonary TB and tested by ZN smear microscopy, Lowenstein–Jensen (LJ) culture and the MODS assay. Discordant results among MODS assay and the other two methods were resolved by 90‐day follow‐up evaluation for all suspected patients.

Results

The sensitivity of the MODS assay on pleural fluid and CSF samples was 20.5% and 37.5%, respectively, while the specificity of MODS assay on both types of samples approximated 100%. The median time to culture results for the MODS and LJ methods was 14 days, 32 days for pleural fluid, and 9 days and 31 days for CSF samples, respectively.

Conclusions

MODS assay is useful to diagnose extrapulmonary TB and may be an effective and affordable method in resource‐limited countries.
A Framework for Estimating the Adverse Health Effects of Contamination Events in Water Distribution Systems and its Application
Authors: Davis Michael J. , Janke Robert , Magnuson Matthew L.
Published: October 2013

Intentional or accidental releases of contaminants into a water distribution system (WDS) have the potential to cause significant adverse health effects among individuals consuming water from the system. A flexible analysis framework is presented here for estimating the magnitude of such potential effects and is applied using network models for 12 actual WDSs of varying sizes. Upper bounds are developed for the magnitude of adverse effects of contamination events in WDSs and evaluated using results from the 12 systems. These bounds can be applied in cases in which little system‐specific information is available. The combination of a detailed, network‐specific approach and a bounding approach allows consequence assessments to be performed for systems for which varying amounts of information are available and addresses important needs of individual utilities as well as regional or national assessments. The approach used in the analysis framework allows contaminant injections at any or all network nodes and uses models that (1) account for contaminant transport in the systems, including contaminant decay, and (2) provide estimates of ingested contaminant doses for the exposed population. The approach can be easily modified as better transport or exposure models become available. The methods presented here provide the ability to quantify or bound potential adverse effects of contamination events for a wide variety of possible contaminants and WDSs, including systems without a network model.
Perception of Risk and the Attribution of Responsibility for Accidents
Authors: Rickard Laura N.
Published: October 2013

Accidents, one often hears, “happen”; we accept, and even expect, that they will be part of daily life. But in situations in which injury or death result, judgments of responsibility become critical. How might our perceptions of risk influence the ways in which we allocate responsibility for an accident? Drawing from attribution and risk perception theory, this study investigates how perceived controllability and desirability of risk, in addition to perceived danger and recreational risk‐taking, relate to attributions of responsibility for the cause of unintentional injury in a unique setting: U.S. national parks. Three parks, Mount Rainier, Olympic, and Delaware Water Gap, provide the setting for this survey‐based study, which considers how park visitors (N = 447) attribute responsibility for the cause of a hypothetical visitor accident. Results suggest that respondents tended to make more internal (i.e., related to characteristics of the victim), rather than external (i.e., related to characteristics of the park, or park management) attributions. As respondents viewed park‐related risk as controllable, they were more likely to attribute the cause of the accident to the victim. Moreover, among other significant variables, having experienced a similar accident predicted lower internal causal attribution. Opportunities for future research linking risk perception and attribution variables, as well as practical implications for the management of public outdoor settings, are presented.
A multiple cave deposit assessment of suitability of speleothem isotopes for reconstructing palaeo‐vegetation and palaeo‐temperature
Authors: Li Zheng‐Hua , Driese Steven G. , Cheng Hai
Published: October 2013

The suitability of speleothems for interpreting palaeoclimate is typically determined by using either the Hendy Test, overlapping analysis or long‐term cave environment monitoring. However, in many cases, these methods are not applicable, because a speleothem lacks clearly traceable layers for the Hendy Test, it is difficult to obtain an overlapping speleothem nearby, or long‐term cave monitoring is impractical. The authors propose a multiple cave deposit approach to assess the suitability of speleothems for palaeoclimate study. Speleothems collected from two sites within Raccoon Mountain Cave, Tennessee (USA) exhibit remarkable spatial variation (δ13C: −10·3‰ to −2·2‰) over a relatively short distance (ca 260 m). Drip water δ18O values exhibit a seasonal precipitation signal at Site 1 and an annual signal at Site 2. Combining field observations, water isotope analysis and trace‐element data, the authors propose that the speleothem formation at Site 1 and Site 2 tapped distinct sources of CO2: (i) CO2 derived from overlying soils for Site 1; and (ii) limestone dissolved inorganic carbon induced by ground water dissolution for Site 2. Using fresh cave deposits (modern speleothem) δ13C (100% C3 vegetation) as an analogue, a simple model was developed to estimate land surface vegetation for speleothems. The speleothem formation temperature estimated using fresh cave deposit δ18O values generally reflects the mean annual temperature in this region. This study indicates that spatial variations in carbon isotopes could be caused by different carbon sources dominating in different parts of the cave, which should be taken into consideration by researchers when using speleothem δ13C values to reconstruct temporal palaeo‐vegetation changes. This study demonstrates a practical sampling strategy for verifying suitability of speleothems for palaeo‐vegetation and palaeo‐temperature reconstructions by analysing multiple cave deposits, especially for cases in which the Hendy Test, parallel sampling and long‐term monitoring of cave environment are not feasible.
Concurrent and prospective associations among biological maturation, and physical activity at 11 and 13 years of age
Authors: Cumming S. P. , Sherar L. B. , Esliger D. W. , Riddoch C. J. , Malina R. M.
Published: October 2013

This study examined concurrent and prospective associations between objective measures of biological maturation, body composition and physical activity (PA) in adolescent males (n = 671) and females (n = 680). Participants born to women recruited to the Avon Longitudinal Study of Parents and Children birth cohort study were assessed at 11 and 13 years. Percentage of predicted adult stature was used as an estimate of biological maturation. PA and time sedentary was assessed over 7 consecutive days using Actigraph accelerometers. Body composition was assessed using whole‐body DXA scans. At 11 and 13 years, maturity in males was inversely associated with accelerometer counts‐per‐minute (CPM) and time engaged in light PA, and positively associated with time sedentary. In females, maturity was inversely associated with accelerometer (CPM) at 11 but not 13 years. Adjusting for accelerometer wear times and corresponding activity levels at 11 years, maturity and percentage fat mass at 11 years did not predict any indices of PA or sedentary behavior in males or females at 13 years. Whereas advanced maturation in males is associated with less PA and more sedentary behavior at 11 and 13 years, maturity at 11 does not predict PA or sedentary behavior at 13 years in either sex.
Adaptations to changing speed, load, and gradient in human walking: Cost of transport, optimal speed, and pendulum
Authors: Gomeñuka N. A. , Bona R. L. , da Rosa R. G. , Peyré‐Tartaruga L. A.
Published: October 2013

It has been observed that the optimal speed (OPT) of human walking is independent of load on level surfaces because of the unaltered trajectory of the center of mass and consequent conservation of the pendular mechanism. However, the role of the inverted pendulum mechanism that combines speed, load, and gradient during walking remains unknown. In the present study, 10 subjects walked on a treadmill, with and without loading (25% of the body mass), at different speeds and slopes (0%, +7%, and +15%). The three‐dimensional motion and VO2 were simultaneously registered. The mechanical external and internal work and the cost of transport (C) changed with the speed and gradient, but the load only affected C. OPT decreased with increasing gradient, and the pendular mechanics (R) was modified mainly as a result of changes in speed and gradient. OPT and R were independent of the load in these gradients. Remarkably, R increased with increasing speed and decreased (to 30%) with an increasing gradient; moreover, R was independent of load. Therefore, the energy‐saving strategy by the pendular mechanism persists, although at a diminished level, in loaded walking on gradients and partially explains the OPT in this condition.
Race and Ethnic Variations in the Education‐Control‐Distress Model
Authors: Hill Terrence D. , Cook Hilary H. , Whitfield Keith E.
Published: October 2013

Objective

Research shows that education favors mental health, in part, because it helps to develop a greater sense of control. To this point, however, it is unclear whether this process varies according to race and ethnicity.

Methods

Building on previous research, we use data collected from a large probability sample of Texas adults to test the extent to which the education‐control‐distress (E‐C‐D) model varies across three race and ethnic groups, including whites, blacks, and Mexican Americans.

Results

The results of our simple mediation analyses validate the E‐C‐D model for each race/ethnic group. Our moderated mediation analyses suggest that the indirect effect of education on psychological distress through the sense of control is comparable across race/ethnic groups.

Conclusion

The mediating influence of the sense of control does not appear to vary according to the three race/ethnic groups included in the study.
Tolerance and the Politics of Identity in the European Union
Authors: Arwine Alan , Mayer Lawrence
Published: October 2013

Objectives

The basic research problem in this article is whether hostility toward out‐groups is a product of events or whether the degree of hostility toward out‐groups exists independently of such events in the form of a generalized bigotry.

Methods

We examine two countries that experienced threatening violent events from an unassimilated minority in order to determine if their levels of intolerance increased in the period between two runs of the World Values Survey when these violent events occurred. This article also examines six additional EU countries that did not experience such violent events.

Results

In the six countries that did not experience violent events, the level of tolerance increased between the two waves of the World Values Survey while tolerance decreased in the two countries that experienced violent events.

Conclusions

The strongest factor in fostering intolerance toward out‐groups is a perception of a violent, existential threat to one's way of life. Our analyses tentatively suggest the following factor may exacerbate levels of intolerance: the presence and strength of a nativist or populist party of identity mobilizing a rejection of out‐groups.
Earth's spin and volcanic eruptions: evidence for mutual cause‐and‐effect interactions?
Authors: Palladino Danilo M. , Sottili Gianluca
Published: October 2013

The angular velocity of Earth's rotation shows decadal oscillations due to the lunisolar gravitational torque, as well as inter‐ or intra‐annual changes arising from the angular momentum exchange between the atmosphere and the solid Earth. The energies involved in the Length of Day (LOD) variations may affect the crustal deformation rate and seismic energy release on a global scale. We found significant correlation between the occurrences of major volcanic eruptions and theLODpattern since AD 1750. On a multiyear scale, eruption frequency worldwide increases withLODchanges. Moreover, the injection of sulphur gases into the atmosphere during major eruptions is accompanied by significant inter‐annualLODvariations. This provides evidence of complex mutual cause‐and‐effect interactions: stress changes induced by multiyear variations in Earth's spin may affect climactic volcanic activity; also, the atmosphere's dynamic response to volcanic plumes may result in global changes of wind circulation and climate, with consequentLODvariations.
Myocardial infarction and pregnancy
Authors: Wuntakal Rekha , Shetty Nanda , Ioannou Elena , Sharma Sunita , Kurian John
Published: October 2013

Key content

Myocardial infarction is a rare but life‐threatening medical condition during pregnancy.

If unrecognised and not managed appropriately, the associated mortality and morbidity are high.

A high index of suspicion, early diagnosis and treatment are essential.

Multidisciplinary management involving the obstetric physician, cardiologist, anaesthetists and obstetrician is key to improving outcomes.

Learning objectives

To revise the physiological cardiovascular changes in pregnancy.

To recognise the pathophysiology of myocardial infarction during pregnancy.

Identify risks factors for myocardial infarction.

Recognise symptoms and signs of myocardial infarction.

To learn the general management principles of myocardial infarction in pregnancy.

Ethical issues

Should asymptomatic pregnant women with multiple risk factors be screened for coronary heart disease?
Golgi‐mediated Glycosylation Determines Residency of the T2 RNase Rny1p in Saccharomyces cerevisiae
Authors: Shcherbik Natalia
Published: October 2013

The role of glycosylation in the function of the T2 family of RNases is not well understood. In this work, we examined how glycosylation affects the progression of the T2 RNase Rny1p through the secretory pathway in Saccharomyces cerevisiae. We found that Rny1p requires entering into the ER first to become active and uses the adaptor protein Erv29p for packaging into COPII vesicles and transport to the Golgi apparatus. While inside the ER, Rny1p undergoes initial N‐linked core glycosylation at four sites, N37, N70, N103 and N123. Rny1p transport to the Golgi results in the further attachment of high‐glycans. Whereas modifications with glycans are dispensable for the nucleolytic activity of Rny1p, Golgi‐mediated modifications are critical for its extracellular secretion. Failure of Golgi‐specific glycosylation appears to direct Rny1p to the vacuole as an alternative destination and/or site of terminal degradation. These data reveal a previously unknown function of Golgi glycosylation in a T2 RNase as a sorting and secretion signal.
Plotting practices and politics: (im)mutable narratives in OpenStreetMap
Authors: Perkins Chris
Published: October 2013

It has been argued that crowd‐sourcing offers a radical alternative to conventional ways of mapping, challenging the hegemony of official and commercial cartographies. In this view mapping might begin to offer a forum for different voices, mapping different things, enabling new ways of living. Instead of the Latourian notion of the map as immutable mobile, fixing knowledge and bodies and facilitating governance, the wikification of mapping might facilitate a more mutable politics. This paper focuses on these possibilities by examining OpenStreetMap (OSM), arguably the most significant and emancipatory of neo‐geographic assemblages. While not underplaying the importance of a political economic understanding of the Geoweb, it suggests we need to attend more to the contexts through which emergent knowledge communities enact alternatives, and that notions of practice are central in any evaluation of changing politics of representation. Communities involved in OSM contest the geographies that they call into being, and this process can be narrated through a consideration of local action, in different map spaces and places. A processual view of mapping reveals the extent of mutability of OSM, and highlights many of the tensions evident in collaborative remapping. New ways of mapping reciprocally create and reinforce newly expert knowledge communities that may be emancipatory, but that may also reify power relations. Crowd‐sourced mapping is likely to comprise a hybrid of mutable and immutable elements.
Evaluation of ultrasound‐guided vascular access in dogs
Authors: Chamberlin Scott C. , Sullivan Lauren A. , Morley Paul S. , Boscan Pedro
Published: October 2013

Objective

To describe the technique and determine the feasibility, success rate, perceived difficulty, and time to vascular access using ultrasound guidance for jugular vein catheterization in a cardiac arrest dog model.

Design

Prospective descriptive study.

Setting

University teaching hospital.

Animals

Nine Walker hounds.

Measurements and Main Results

A total of 27 jugular catheterizations were performed postcardiac arrest using ultrasound guidance. Catheterizations were recorded based on the order in which they were performed and presence/absence of a hematoma around the vein. Time (minutes) until successful vascular access and perceived difficulty in achieving vascular access (scale of 1 = easy to 10 = difficult) were recorded for each catheterization. Mean time to vascular access was 1.9 minutes (95% confidence interval, 1.1–3.4 min) for catheterizations without hematoma, versus 4.3 minutes (1.8–10.1 min) for catheterizations with hematoma (P = 0.1). Median perceived difficulty was 2 of 10 (range 1–7) for catheterizations without hematoma, versus 2 of 10 (range 1–8) for catheterizations with hematoma (P = 0.3). A learning curve was evaluated by comparing mean time to vascular access and perceived difficulty in initial versus subsequent catheterizations. Mean time to vascular access was 2.5 minutes (1.0–6.4 min) in the initial 13 catheterizations versus 3.3 minutes (1.5–7.5 min) in the subsequent 14 catheterizations (P = 0.6). Median perceived difficulty in the first 13 catheterizations (3, range 1–8) was significantly greater (P = 0.049) than median perceived difficulty in the subsequent 14 catheterizations (2, range 1–6).

Conclusions

Ultrasound‐guided jugular catheterization is associated with a learning curve but is successful in obtaining rapid vascular access in dogs. Further prospective studies are warranted to confirm the utility of this technique in a clinical setting.
ULTRASONOGRAPHIC CHARACTERISTICS OF LIPIDURIA IN CLINICALLY NORMAL CATS
Authors: Sislak Meg D. , Spaulding Kathy A. , Zoran Debra L. , Bauer John E. , Thompson James A.
Published: October 2013

Echoes are frequently seen in the urinary bladder of cats during abdominal ultrasound. These have been attributed to hematuria, pyuria, crystalluria, and lipid. However, sonographic findings have not been previously correlated with urinalysis. We prospectively evaluated 40 clinically normal cats via ultrasound, serum chemistry, and urinalysis. Thin layer chromatography was performed on the urine to determine the amount (mg) of lipid subfractions including diacylglycerol, triglyceride, phospholipid, free fatty acid, cholesterol, and cholesterol ester. Ninety percent (36/40) of the cats in our population had sonographic echoes suspended in the urinary bladder, with most having a subjective score of mild echoes (n = 20). None of the sonographic echoes were gravity dependent or caused distal acoustic shadowing, reverberation, or twinkle artifact. Of the cats with sonographic echoes in the urine, 66% (24/36) had no significant findings on urinalysis other than the presence of lipid. The total amount of subjective sonographic echoes was not significantly related to the total amount of fat measured on thin layer chromatography or the number of lipid droplets seen on urinalysis. An increased amount of urine diacylglycerol was significantly associated with clumping of echoes (P = 0.02) and the amount of lipid droplets seen on urinalysis (P = 0.04). An association between increased amounts of urine diacylglycerol and the amount of echoes seen on ultrasound approached significance (P = 0.05). Findings from this study support previously published theories that sonographic echoes within the urinary bladder of clinically normal cats may be due to urine lipid.
ACCURACY OF LOW‐FIELD MAGNETIC RESONANCE IMAGING VERSUS RADIOGRAPHY FOR GUIDING INJECTION OF EQUINE DISTAL INTERPHALANGEAL JOINT COLLATERAL LIGAMENTS
Authors: Lamb Megan M. , Barrett Jennifer G. , White Nathaniel A. , Werre Stephen R.
Published: October 2013

Desmopathy of the distal interphalangeal joint collateral ligament is a common cause of lameness in the horse and carries a variable prognosis for soundness. Intralesional treatment has been proposed for improving outcome; however, limited reports describe methods for injecting this ligament. The purpose of this study was to compare accuracy of low‐field magnetic resonance imaging (MRI) vs. radiography for injecting the collateral ligament of the distal interphalangeal joint. Equine cadaver digit pairs (n = 10) were divided by random assignment to injection of the ligament by either technique. An observer unaware of injection technique determined injection success based on postinjection MRI and/or gross sections acquired from the proximal, middle, and distal portions of the ligament. McNemar's test was performed to determine statistical difference between injection techniques, the number of injection attempts, and injection of the medial or lateral collateral ligament. Magnetic resonance imaging guided injection was successful more frequently than radiographic‐guided injection based on postinjection MRI (24 of 30 vs. 9 of 30; P = 0.0006) and gross sections (26 of 30 vs. 13 of 30; P = 0.0008). At each level of the ligament (proximal, middle, and distal), MRI‐guided injection resulted in more successful injections than radiographic guidance. Statistical significance occurred at the proximal aspect of the collateral ligament based on postinjection MRI (P = 0.0143) and the middle portion of the ligament based on gross sections (P = 0.0253). Findings supported future testing of standing, low‐field MRI as a technique for delivering intralesional regenerative therapy in live horses with desmopathy of these collateral ligaments.
Use of Implementation Theory: A Focus on PARIHS
Authors: Ullrich Philip M. , Sahay Anju , Stetler Cheryl B.
Published: October 2013

Background

Limited understanding and application of theory in implementation research contributes to variable effectiveness of implementation studies. Better understanding of direct experiences with theory could improve implementation research and the potency of interventions.

Aims

This study was a conceptual exercise aimed at characterizing experiences with and applications of the Promoting Action on Research Implementation in Health Services (PARIHS) framework.

Methods

This was a structured, qualitative study involving document reviews and interviews used to answer the following overarching questions about nine implementation research centers: Why and how was PARIHS used? What strengths and weaknesses were identified for PARIHS?

Findings

PARIHS was being used for varied purposes, at varied levels, in varied ways, and to a varying extent within and across centers. Lack of implementation theory use in investigators’ early years was common. Variability in the nature of theory use was attributable to characteristics of the centers, individual investigators, and features of PARIHS. Strengths and weaknesses of the PARIHS framework were identified.

Linking Evidence to Action

The study provides information to researchers and theorists about the use of one well‐known implementation framework. The information suggests areas for improvements in PARIHS as well as theory use in general, and should assist in the development of theory‐based programs of research.
Modulation of stimulus‐specific adaptation by GABAA receptor activation or blockade in the medial geniculate body of the anaesthetized rat
Authors: Duque Daniel , Malmierca Manuel S. , Caspary Donald M.
Published: October 2013

Key points

Neurons in the medial geniculate body (MGB), the auditory thalamus, give stronger responses to rare sounds than to repetitive sounds, a phenomenon referred to as stimulus‐specific adaptation (SSA).

The present study sought to elucidate how the inhibitory thalamic circuitry acting at GABAA receptors affects the generation and/or modulation of SSA from recordings of single unit responses from MGB. Microiontophoretic application of GABAergic agonists selectively increased SSA indices, whereas application of antagonists selectively reduced SSA values.

We found that GABAA‐mediated inhibition did not generate the SSA response but regulated the magnitude of SSA sensitivity in a gain control manner.

These findings advance our understanding of the role of inhibition in coding deviance detection in the MGB.

Stimulus‐specific adaptation (SSA), which describes adaptation to repeated sounds concurrent with the maintenance of responsiveness to uncommon ones, may be an important neuronal mechanism for the detection of and attendance to rare stimuli or for the detection of deviance. It is well known that GABAergic neurotransmission regulates several different response properties in central auditory system neurons and that GABA is the major inhibitory neurotransmitter acting in the medial geniculate body (MGB). The mechanisms underlying SSA are still poorly understood; therefore, the primary aim of the present study was to examine what role, if any, MGB GABAergic circuits play in the generation and/or modulation of SSA. Microiontophoretic activation of GABAA receptors (GABAARs) with GABA or with the selective GABAAR agonist gaboxadol significantly increased SSA (computed with the common SSA index, CSI) by decreasing responses to common stimuli while having a lesser effect on responses to novel stimuli. In contrast, GABAAR blockade using gabazine resulted in a significant decrease in SSA. In all cases, decreases in the CSI during gabazine application were accompanied by an increase in firing rate to the stimulus paradigm. The present findings, in conjunction with those of previous studies, suggest that GABAA‐mediated inhibition does not generate the SSA response, but can regulate the level of SSA sensitivity in a gain control manner. The existence of successive hierarchical levels of processing through the auditory system suggests that the GABAergic circuits act to enhance mechanisms to reduce redundant information.
Approximate End-Effector Tracking Control of Flexible Multibody Systems Using Singular Perturbations
Authors: Gorius Thomas , Seifried Robert , Eberhard Peter
Published: October 2013

In many cases, the design of a tracking controller can be significantly simplified by the use of a 2-degrees of freedom (DOF) control structure, including a feedforward control (i.e., the inversion of the nominal system dynamics). Unfortunately, the computation of this feedforward control is not easy if the system is nonminimum-phase. Important examples of such systems are flexible multibody systems, such as lightweight manipulators. There are several approaches to the numerical computation of the exact inversion of a flexible multibody system. In this paper, the singularly perturbed form of such mechanical systems is used to give a semianalytic solution to the tracking control design. The control makes the end-effector to even though not exactly, but approximately track a certain trajectory. Thereby, the control signal is computed as a series expansion in terms of an overall flexibility of the bodies of the multibody system. Due to the use of symbolic computations, the main calculations are independent of given parameters (e.g., the desired trajectories), such that the feedforward control can be calculated online. The effectiveness of this approach is shown by the simulation of a two-link flexible manipulator.
Why do Fish Have a “Fish-Like Geometry”?
Authors: Kagemoto Hiroshi
Published: October 2013

Most fish share a common geometry, a streamlined anterior body and a deep caudal fin, connected to each other at a tail-base neck, where the body almost shrinks to a point. This work attempts to explain the reason that fish exhibit this type of geometry. Assuming that the fish-like geometry is a result of evolution over millions of years, or, that bodies of modern-day fish have been optimized in some manner as a result of evolution, this work investigates the optimum geometry for a swimming object through existing mathematical optimization techniques to check whether the result obtained is the same as the naturally observed fish-like geometry. In this analysis, the work done by a swimming object is taken as the objective function of the optimization. It is found that a fish-like geometry is in fact obtained mathematically, provided that the appropriate constraints are imposed on the optimization process, which, in turn, provides some clues that explain the reason that fish have a fish-like geometry.
Model for Predicting Drag Torque in Open Multi-Disks Wet Clutches
Authors: Iqbal Shoaib , Al-Bender Farid , Pluymers Bert , Desmet Wim
Published: October 2013

A mathematical model based on continuity and Navier-Stokes equations, considering laminar flow in the gap between the disks, is presented to estimate the drag torque in open multidisks wet clutches. By taking into account the effects of Poiseuille and centrifugal forces, the flow pressure and velocity fields are investigated. The model quantifies the volume fraction of fluids and predicts the evolution of film shape. The drag torque estimated by the model is the sum of drag torque due to shearing of automatic transmission fluid (ATF) and the mist (suspension of ATF in air) film. In order to validate the model, experiments are performed on SAE# 2 test-setup under actual operating conditions of clutches. The model is capable of predicting the drag torque under conditions of variable flow rate and different disks rotational state for higher clutch speed range.
Effective Thermal Conductivity of Ordered Short-Fiber Composites With Single-Fiber Uniform Hexagonal Prism Cell
Authors: Martinez Marcelo B. , Cruz Manuel E. , Matt Carlos F.
Published: October 2013

The bulk behavior of short-fiber composite materials in mechanical, thermal, and electrical applications is of great engineering interest. The reliability of analytical and numerical studies dedicated to these topics depends to a large extent on the postulated, or prescribed, microstructure configurations. Of course, different spatial distributions of fibers lead to different configurations, which in turn influence the effective properties. There are no established (or benchmarked) microstructure configurations (or models) to be used in investigations aimed at calculating the macroscopic behavior of classes of real composite material bodies. In the present numerical study of heat conduction in composites, accurate results for the longitudinal and transverse effective thermal conductivities of short-fiber composites with single-fiber uniform hexagonal prism cell are calculated and validated. The three-dimensional periodic cell microstructure consists of one short circular cylindrical fiber placed at the center, and perpendicular to the two parallel regular hexagons, of the prism. Previous continuous formulation and computational implementation are employed, based on the method of homogenization and finite element discretization. A procedure for generating the domain of the uniform hexagonal prism cell, and the respective tetrahedral finite-element mesh, has been realized using a third-party software. The numerical effective conductivity results obtained in the 3-D calculations are validated against analytical results for the 2-D hexagonal array of circular cylinders.
Effect of Deformation Temperature and Cooling Rate on the Transformation Behavior of the Steel BR1500HS
Authors: Xu Chun
Published: October 2013

In the present paper, the effects of deformation temperature on phase transformations behavior of the steel BR1500HS during isothermal and non-isothermal deformations are described and discussed. Thermal mechanical simulation tests were carried out on GLEEBLE 1500 thermal simulator, Some specimens are uniaxially extended with strain rate 10/s and their largest deforming degree reaches 15% at 950°C. After deformation, the specimens are cooled to room temperature at different cooling rates, 0.5, 1, 5, 10, 20, 30°C/s, respectively. And the others are nonisothermal uniaxially extended with strain rate 10/s with strain value 15% from the initial deformation temperature of 800°C, and simultaneously cooled to different temperature, 400, 450, 500, 550, 600, 650 and 700°C, respectively. The isothermal deforming microstructures of steel BR1500HS are mainly composed of ferrite and pearlite at a cooling rate range of 0.5 to 1°C/s. When the cooling rate gets to 5°C/s, the microstructures are mainly bainite and some martensite. And the cooling rate is higher than 30°C/s, fully martensitic transformation are accomplished in the experimental steel. The non-isothermal deforming microstructures, however, no martensite phase can be seen. Even the amount of bainite phase is minimal, too.
Experimental and Numerical Investigations of Stacking Sequence Effect on GLARE 5 FML Plates Subjected to Ballistic Impact
Authors: Seyed Yaghoubi A. , Liaw B.
Published: October 2013

In this study, GLARE 5 (3/2) fiber-metal laminated (FML) plates of dimensions: 152.4 mm × 101.6 mm with various stacking sequences, namely: unidirectional [0°4], cross-ply [0°/90°]s, angle-ply [+45°/−45°]s and quasi-isotropic [0°/±45°/90°], were impacted by a 0.22 caliber bullet-shaped projectile using a high-speed gas gun. A high-speed camera was used to measure the projectile velocity along its ballistic trajectory. The post-impact damage in the specimens was evaluated using both nondestructive and destructive techniques. The nondestructive assessment was conducted using an UltraPAC immersion ultrasound system; whereas for the destructive technique the specimens were cut transversely along the impact center using a diamond blade cutting wheel. The results showed that the induced damage in the specimens changed its shape as the prepreg lay-up orientation was altered. The 3D dynamic nonlinear finite element (FE) software, LS-DYNA, was used to validate the experimental results. Good agreement between experimental and FE results was obtained.
Development of Damage Reconstruction Techniques From Impulsive Events Based on Measurements Made Remotely
Authors: Olugboji Oluwafemi A. , Hale Jack M.
Published: October 2013

Damage done to petroleum pipelines can be catastrophic if left undetected with time. Most of these damages results in financial losses, environmental pollution and frequent loss of life as a result of explosion due to prolong exposure of pipeline products. Therefore, damage detection and location techniques will play a key role in the overall integrity management of a pipeline system. This paper addresses the development and testing of mathematical techniques for locating an impulsive event on a pipeline and reconstructing the pressure pulse caused by it from measurements made remotely. When an impulsive event occurs along a pipeline, the pressure pulse propagates in both directions and can be detected and measured by sensors located at different positions along the pipeline. From these measurements the location of the event can be determined and its form reconstructed. Techniques for reconstructing the pulse at it source from the distorted pulses measured were developed using deconvolution theory and inverse methods. This theoretical work was validated by experiments using a simulated pipeline. The experimental work was carried out using a test rig comprising a flexible hose pipe 23 m long and 19 mm diameter with four pressure sensors distributed along the pipe and connected to a data acquisition system. The techniques were tested for static and flowing air in the pipe, and were found to give good results.
Simplified Correlation Equations of Heat Transfer Coefficient During Phase Change Flow Inside Tubes Filled With Porous Media
Authors: Hammad M. , Tarawneh M. , Al-Shqirate A.
Published: October 2013

In this work an easy to use, simple and direct equations were formulated and tested. Heat transfer coefficients of phase change fluid flow were examined in this work. The considered fluid flow encountered convection heat flux inside rigid tubes filled with porous media. During the flow, phase change was assumed. Experimental work was conducted using Carbon dioxide as fluid.

An analytical method using exponential non dimensional analysis was used. The Buckingham π theorem and method of indices was used to obtain simplified formula for the convection heat transfer coefficient and for the Nusselt number.

Two different correlations can be extracted from this formula; one for the evaporation process and the other for the condensation process.
Modelling of Misaligned Rotor Systems in Aero-Engines
Authors: Li Jun , Hong Jie , Ma Yanhong , Zhang Dayi
Published: October 2013

Based on the analysis of structural and dynamic characteristics, a dynamic model of flexible rotor system under misalignment and unbalance excitation in aero-engine was developed through Lagrange equations. The model describes the mechanism and influencing factors of nonlinear properties of misaligned rotors. Then some numerical simulations were performed in order to get the vibration response in time and frequency domain. The results suggest that the rotor system and its coupling may behave in a complex and nonlinear way with the excitation of misalignment and unbalance. The response of the system contains 1× and 2× harmonics, and the spectrum signature closely relate to the misalignment magnitude and the distribution of unbalance mass. A series of experiments were also designed to verify the dynamic model. Their characteristics of response are in good agreement.
The Joint Biomechanics Change by Different Anterior Cruciate Ligament Constitutive Models Under Axial Torque Load
Authors: Wan Chao , Hao Zhixiu , Wen Shizhu
Published: October 2013

According to the previous papers, it was demonstrated that anterior cruciate ligament (ACL) played an important role in resisting the coupled anterior-posterior laxity rather than the rotation laxity under axial torque load of knee joint. In the biomechanics simulation research of knee joint, some different ligament constitutive models were presented to describe the ACL material behavior. However, there is few published paper to study the effect of variable ligament constitutive model on the joint biomechanics under axial torque load.

In this paper, a 3-dimension finite element model of an intact tibiofemoral joint including all the main anatomical structures was reconstructed and two ACL constitutive models were compared under 10 Nm femur external torque load. The two ACL constitutive models corresponded to an isotropic hyperelastic model and a transversely isotropic hyperelastic model considering fiber effect, respectively. All the ACL material properties of the two constitutive models were defined by fitting the same stress-strain data. Another model with ACL resected was also analyzed under the same load to estimate the function ACL played under joint axial torque load.

It was found that the resection of ACL changed the knee joint deformations significantly in all directions except the distal-proximal translation. In the ACL resected joint model, the internal-external rotation, anterior-posterior and medial-lateral translations increased by about 20%, 500% and 600%, respectively. Comparing to the ACL intact joint model, the Mises stress values of medial collateral ligament decreased while that on lateral collateral ligament increased greatly (from 35 MPa to 61 MPa). In the comparison of the two different ACL constitutive models, the internal-external rotation, as the highest deformation of the knee joint, changed by about 11% and the maximal deformation alteration was obtained in the anterior-posterior translation (about 80%). Both the highest stress value and distribution on ACL have altered mostly while the Mises stress distributions of other ligaments and menisci have changed slightly.

The alteration of joint kinematics and ligament biomechanics by different ACL constitutive models would be due to the different descriptions of the material transverse behavior and the real complex ACL stress distribution under an axial torque load, although the longitudinal material behaviors described by different ACL constitutive models were almost the same based on the same experiment data.
Design Optimization of Magnetic Fluid Cooling System
Authors: Lee J. , Nomura T. , Dede E. M.
Published: October 2013

This paper introduces topology design optimization for a magnetically controlled convective heat transfer cooling system. It is well known that a stationary magnetic field subjected to a temperature gradient generates fluid motion in a magnetic fluid (e.g. ferrofluid). This physical phenomenon may be exploited to drive convective motion in the cooling system to maximize the heat transfer performance. Here, the magnetic field source layout of the system is designed to enhance the heat transfer performance. More specifically, the distribution and magnetization direction of the permanent magnet (PM) field source is optimized to minimize the maximum temperature of a closed loop heat transfer system. The design optimization is performed using a gradient-based topology optimization method with a fully coupled non-linear analysis for magnetic-thermal-fluid systems. Interestingly, magnet designs similar to Halbach arrays are obtained as the optimal PM layout. The magnetic field distribution generated by the designed layout affects the body force that the fluid is subjected to and results in unique fluid flow patterns for maximum cooling performance of the system. Thus, this paper will provide an explanation of the design optimization procedure and provide the design result.
Intelligent Combination of Batch Fabrication With Rapid Prototyping Techniques for a Drop-on-Demand Microdrop Generator
Authors: Kagerer Markus , Eiler Kenji L. , Irlinger Franz , Lueth Tim C.
Published: October 2013

A fluidic experimentation platform, consisting of a piezoelectrically driven microdrop generator which is mounted on a quick-action clamping device, is introduced. Microdrop generators are playing an increasingly important role in many industries. Even though their beginnings were in the printing and coating sector, their strengths are more and more used in other sectors. The wide variety of properties of the fluids like molten polymers, dispersions, or monomers usually require a redesign of the microdrop generator for each application to achieve drops of the size, with the speed, and uniformity that are needed. Therefore, the use of rapid prototyping (RP) techniques for the adaption of microdrop generators to new boundary conditions is indispensable.

The presented microdrop generator is based on the diaphragm design. A silicon base plate includes the fluidic components. The number of nozzles is three. Even if one nozzle is clogged two other nozzles are working. The diaphragm is made of borosilicate glass. On top of the diaphragm a piezoelectric transducer is glued. The piezoelectric transducer and the diaphragm form a bimorph actuator. Since only the borosilicate glass and the silicon are in contact with the fluid the assembly is highly chemical resistant to aggressive media. Thus, a very broad range of fluids is ejectable.

Besides the laser as main tool a dicing saw is involved in the process flow. Investigations for the optimum machining parameters are presented. In this project four equal microdrop generators respectively 12 nozzles and one further silicon base plate for further quality inspection of the whole batch are manufactured simultaneously. They serve as a good basis for fluidic experiments. Only six process steps are necessary to fabricate one microdrop generator within 25 min. Up to 16 microdrop generators can be batch fabricated in a 4″ process chain with rapid prototyping techniques.

The realized quick-action clamping device supports a rapid exchange of the microdrop generators and enables future technologies. Here, the electrical and the fluidic connection of the microdrop generator are realized. The microdrop generator is inserted into a groove and is at the same time fluidically and electrically connected via four spring contacts. Special feature is that no gluing or soldering processes are necessary. The device is constructed in a modular way to add further components like a heating cartridge or a fluid reservoir. Overall, the exchange of one microdrop generator can be realized within one minute.

The use of the batch fabricated microdrop generator in combination with the presented quick-action clamping device guarantees an efficient execution of fluidic experiments.