bluuebunny/crossref_metadata_2025 huggingface dataset:
THAM reduces CO2-associated increase in pulmonary vascular resistance – an experimental study in lung-injured piglets
Authors: Höstman Staffan , Borges João Batista , Suarez-Sipmann Fernando , Ahlgren Kerstin M. , Engström Joakim , Hedenstierna Göran , Larsson Anders
Published: September 2015

Introduction

Low tidal volume (VT) ventilation is recommended in patients with acute respiratory distress syndrome (ARDS). This may increase arterial carbon dioxide tension (PaCO2), decrease pH, and augment pulmonary vascular resistance (PVR). We hypothesized that Tris(hydroxymethyl)aminomethane (THAM), a pure proton acceptor, would dampen these effects, preventing the increase in PVR.

Methods

A one-hit injury ARDS model was established by repeated lung lavages in 18 piglets. After ventilation with VT of 6 ml/kg to maintain normocapnia, VT was reduced to 3 ml/kg to induce hypercapnia. Six animals received THAM for 1 h, six for 3 h, and six serving as controls received no THAM. In all, the experiment continued for 6 h. The THAM dosage was calculated to normalize pH and exhibit a lasting effect. Gas exchange, pulmonary, and systemic hemodynamics were tracked. Inflammatory markers were obtained at the end of the experiment.

Results

In the controls, the decrease in VT from 6 to 3 ml/kg increased PaCO2 from 6.0±0.5 to 13.8±1.5 kPa and lowered pH from 7.40±0.01 to 7.12±0.06, whereas base excess (BE) remained stable at 2.7±2.3 mEq/L to 3.4±3.2 mEq/L. In the THAM groups, PaCO2 decreased and pH increased above 7.4 during the infusions. After discontinuing the infusions, PaCO2 increased above the corresponding level of the controls (15.2±1.7 kPa and 22.6±3.3 kPa for 1-h and 3-h THAM infusions, respectively). Despite a marked increase in BE (13.8±3.5 and 31.2±2.2 for 1-h and 3-h THAM infusions, respectively), pH became similar to the corresponding levels of the controls. PVR was lower in the THAM groups (at 6 h, 329±77 dyn∙s/m5 and 255±43 dyn∙s/m5 in the 1-h and 3-h groups, respectively, compared with 450±141 dyn∙s/m5 in the controls), as were pulmonary arterial pressures.

Conclusions

The pH in the THAM groups was similar to pH in the controls at 6 h, despite a marked increase in BE. This was due to an increase in PaCO2 after stopping the THAM infusion, possibly by intracellular release of CO2. Pulmonary arterial pressure and PVR were lower in the THAM-treated animals, indicating that THAM may be an option to reduce PVR in acute hypercapnia.
Inhaled nitric oxide improves transpulmonary blood flow and clinical outcomes after prolonged cardiac arrest: a large animal study
Authors: Derwall Matthias , Ebeling Andreas , Nolte Kay Wilhelm , Weis Joachim , Rossaint Rolf , Ichinose Fumito , Nix Christoph , Fries Michael , Brücken Anne
Published: September 2015

Introduction

The probability to achieve a return of spontaneous circulation (ROSC) after cardiac arrest can be improved by optimizing circulation during cardiopulomonary resuscitation using a percutaneous left ventricular assist device (iCPR). Inhaled nitric oxide may facilitate transpulmonary blood flow during iCPR and may therefore improve organ perfusion and outcome.

Methods

Ventricular fibrillation was electrically induced in 20 anesthetized male pigs. Animals were left untreated for 10 minutes before iCPR was attempted. Subjects received either 20 ppm of inhaled nitric oxide (iNO, n = 10) or 0 ppm iNO (Control, n = 10), simultaneously started with iCPR until 5 hours following ROSC. Animals were weaned from the respirator and followed up for five days using overall performance categories (OPC) and a spatial memory task. On day six, all animals were anesthetized again, and brains were harvested for neurohistopathologic evaluation.

Results

All animals in both groups achieved ROSC. Administration of iNO markedly increased iCPR flow during CPR (iNO: 1.81 ± 0.30 vs Control: 1.64 ± 0.51 L/min, p < 0.001), leading to significantly higher coronary perfusion pressure (CPP) during the 6 minutes of CPR (25 ± 13 vs 16 ± 6 mmHg, p = 0.002). iNO-treated animals showed significantly lower S-100 serum levels thirty minutes post ROSC (0.26 ± 0.09 vs 0.38 ± 0.15 ng/mL, p = 0.048), as well as lower blood glucose levels 120–360 minutes following ROSC. Lower S-100 serum levels were reflected by superior clinical outcome of iNO-treated animals as estimated with OPC (3 ± 2 vs. 5 ± 1, p = 0.036 on days 3 to 5). Three out of ten iNO-treated, but none of the Control animals were able to successfully participate in the spatial memory task. Neurohistopathological examination of vulnerable cerebral structures revealed a trend towards less cerebral lesions in neocortex, archicortex, and striatum in iNO-treated animals compared to Controls.

Conclusions

In pigs resuscitated with mechanically-assisted CPR from prolonged cardiac arrest, the administration of 20 ppm iNO during and following iCPR improved transpulmonary blood flow, leading to improved clinical neurological outcomes.
Clinical classification of tissue perfusion based on the central venous oxygen saturation and the peripheral perfusion index
Authors: He Huaiwu , Long Yun , Liu Dawei , Wang Xiaoting , Zhou Xiang
Published: September 2015

Introduction

We investigated whether combining the peripheral perfusion index (PI) and central venous oxygen saturation(ScvO2) would identify subsets of patients for assessing the tissue perfusion and predicting outcome during the resuscitation in critically ill patients.

Methods

A total of 202 patients with central venous catheters for resuscitation were enrolled in this prospective observational study. The arterial, central venous blood gas and the PI were measured simultaneously at the enrollment (T0) and 8 h (T8) after early resuscitation. Based on the distribution of the PI in healthy population, a cutoff of PI ≥1.4 was defined as a normal PI. Moreover, the critical value of PI was defined as the best cutoff value related to the mortality in the study population. The PI impairment stratification is defined as follows: a normal PI(≥1.4), mild PI impairment (critical value < PI < 1.4) and critical PI impairment (PI ≤ critical value).

Results

The PI at T8 was with the greatest AUC for prediction the 30-day mortality and PI is an independent risk factor for 30-day mortality. Moreover, a cutoff of PI < 0.6 is related to poor outcomes following resuscitation. So, based on cutoffs of ScvO2 (70 %) and critical PI (0.6) at T8, we assigned the patients to four categories: group 1 (PI ≤ 0.6 on ScvO2 < 70 %), group 2 (PI ≤ 0.6 on ScvO2 ≥ 70 %), group 3 (PI > 0.6 on ScvO2 < 70 %), and group 4 (PI > 0.6 on ScvO2 ≥ 70 %). The combination of low ScvO2(<70 %) and PI(≤0.6) was associated with the lowest survival rates at 30 days [log rank (Mantel–Cox) = 87.518, p < 0.0001]. The sub-group patients who had high ScvO2(>80 %) at T8 were with low mortality and high PI. Moreover, the normal PI (≥1.4) did not show a better outcome than mild impaired PI (0.6-1.4) patients who had a normalized ScvO2(>70 %) after resuscitation. The PI was correlated with the lactate, P(v-a)CO2, and ScvO2 in all the measurements (n = 404). These relationships are strengthened with abnormal PI (PI < 1.4) but not with normal PI (PI ≥ 1.4).

Conclusion

Complementing ScvO2 assessment with PI can better identify endpoints of resuscitation and adverse outcomes. Pursuing a normalized PI (≥1.4) may not result in better outcomes for a mild impaired PI after ScvO2 is normalized.
A close look at protein function prediction evaluation protocols
Authors: Kahanda Indika , Funk Christopher S , Ullah Fahad , Verspoor Karin M , Ben-Hur Asa
Published: September 2015

Background

The recently held Critical Assessment of Function Annotation challenge (CAFA2) required its participants to submit predictions for a large number of target proteins regardless of whether they have previous annotations or not. This is in contrast to the original CAFA challenge in which participants were asked to submit predictions for proteins with no existing annotations. The CAFA2 task is more realistic, in that it more closely mimics the accumulation of annotations over time. In this study we compare these tasks in terms of their difficulty, and determine whether cross-validation provides a good estimate of performance.

Results

The CAFA2 task is a combination of two subtasks: making predictions on annotated proteins and making predictions on previously unannotated proteins. In this study we analyze the performance of several function prediction methods in these two scenarios. Our results show that several methods (structured support vector machine, binary support vector machines and guilt-by-association methods) do not usually achieve the same level of accuracy on these two tasks as that achieved by cross-validation, and that predicting novel annotations for previously annotated proteins is a harder problem than predicting annotations for uncharacterized proteins. We also find that different methods have different performance characteristics in these tasks, and that cross-validation is not adequate at estimating performance and ranking methods.

Conclusions

These results have implications for the design of computational experiments in the area of automated function prediction and can provide useful insight for the understanding and design of future CAFA competitions.
The Impact of Demand Uncertainty on Consumer Subsidies for Green Technology Adoption
Authors: Cohen Maxime C. , Lobel Ruben , Perakis Georgia
Published: September 2015

This paper studies government subsidies for green technology adoption while considering the manufacturing industry’s response. Government subsidies offered directly to consumers impact the supplier’s production and pricing decisions. Our analysis expands the current understanding of the price-setting newsvendor model, incorporating the external influence from the government, who is now an additional player in the system. We quantify how demand uncertainty impacts the various players (government, industry, and consumers) when designing policies. We further show that, for convex demand functions, an increase in demand uncertainty leads to higher production quantities and lower prices, resulting in lower profits for the supplier. With this in mind, one could expect consumer surplus to increase with uncertainty. In fact, we show that this is not always the case and that the uncertainty impact on consumer surplus depends on the trade-off between lower prices and the possibility of underserving customers with high valuations. We also show that when policy makers such as governments ignore demand uncertainty when designing consumer subsidies, they can significantly miss the desired adoption target level. From a coordination perspective, we demonstrate that the decentralized decisions are also optimal for a central planner managing jointly the supplier and the government. As a result, subsidies provide a coordination mechanism.

This paper was accepted by Yossi Aviv, operations management.
Managing silage making to reduce losses
Authors: Wilkinson J M
Published: September 2015

Losses of dry matter and metabolisable energy (ME) occur in silage making due to delayed harvest and also between field and feed trough due to fermentation and aerobic spoilage. Farmers should aim to exert greater control of silage making operations to improve timeliness of harvest and to minimise losses of nutrients. Concentrate input per unit of milk production is often higher than optimal which is more often a reflection of low silage quality than of wasteful overfeeding. A week's delayed harvest of grass is estimated to incur a net cost of 13 pence per cow per day of winter feeding. Mowing a dry crop and spreading it out to maximise rate of water loss during the wilting period can reduce losses in the field. Consolidation of crop in the silo to achieve a minimum fresh weight density of 700 kg/m3 and dry matter (DM) density of 210 kg/m3 will help to minimise losses during the storage period, paying particular attention to the outermost layer which should be covered with an oxygen barrier film. A feed-out progression rate of at least 1 metre per week in winter and 1.5 to 2 metres per week in summer, coupled with harvesting a clean crop with low yeast and mould counts will help to reduce losses during feed-out. Many bunker silos are too old, too small, have no safety rail and are over-filled. Safety issues should be considered at all stages of silage making. Appropriate steps should be taken wherever possible to minimise risk of injury.
Looking after your staff
Authors: Moore Jenny
Published: September 2015

Jenny Moore suggests seven ways to address the teacher workload challenge and improve staff wellbeing this year
Getting those grants
Authors: Ellery John
Published: September 2015

Fundraising expert John Ellery discusses some key things that schools must consider when applying for funds or grants
Psychosis, Pain, and Time: A Personal Reflection
Authors: Saks Elyn R.
Published: September 2015

In this essay, I explore psychosis, pain, and time from a personal standpoint. I do not do a study, nor even review the literature. Rather, I reflect on my own experiences. As someone who has experienced psychosis, pain, and the passage of time, I can indeed speak from personal experience. Of course, I am an “n” of only one and others may have different experiences. So this is an opening of dialogue, and not an endpoint.
Tandem Mass Spectrometry Has a Larger Analytical Range than Fluorescence Assays of Lysosomal Enzymes: Application to Newborn Screening and Diagnosis of Mucopolysaccharidoses Types II, IVA, and VI
Authors: Kumar Arun Babu , Masi Sophia , Ghomashchi Farideh , Chennamaneni Naveen Kumar , Ito Makoto , Scott C Ronald , Turecek Frantisek , Gelb Michael H , Spacil Zdenek
Published: September 2015

BACKGROUND

There is interest in newborn screening and diagnosis of lysosomal storage diseases because of the development of treatment options that improve clinical outcome. Assays of lysosomal enzymes with high analytical range (ratio of assay response from the enzymatic reaction divided by the assay response due to nonenzymatic processes) are desirable because they are predicted to lead to a lower rate of false positives in population screening and to more accurate diagnoses.

METHODS

We designed new tandem mass spectrometry (MS/MS) assays that give the largest analytical ranges reported to date for the use of dried blood spots (DBS) for detection of mucopolysaccharidoses type II (MPS-II), MPS-IVA, and MPS-VI. For comparison, we carried out fluorometric assays of 6 lysosomal enzymes using 4-methylumbelliferyl (4MU)-substrate conjugates.

RESULTS

The MS/MS assays for MPS-II, -IVA, and -VI displayed analytical ranges that are 1–2 orders of magnitude higher than those for the corresponding fluorometric assays. The relatively small analytical ranges of the 4MU assays are due to the intrinsic fluorescence of the 4MU substrates, which cause high background in the assay response.

CONCLUSIONS

These highly reproducible MS/MS assays for MPS-II, -IVA, and -VI can support multiplex newborn screening of these lysosomal storage diseases. MS/MS assays of lysosomal enzymes outperform 4MU fluorometric assays in terms of analytical range. Ongoing pilot studies will allow us to gauge the impact of the increased analytical range on newborn screening performance.
Targets, threats and (dis)trust: The managerial troika for public school principals in Chile
Authors: Montecinos Carmen , Ahumada Luis , Galdames Sergio , Campos Fabián , Leiva María Verónica
Published: September 2015

Public education in Chile has been steadily losing students as a result of the implementation, for the last 35 years, of a market model. In this paper we exemplify how a structural problem (public schools’ declining enrollment) created by neoliberal educational policies is transformed into an individual problem to be managed by the public school principal. Principals must sign a performance-based contract that specifies sanctions and incentives for meeting enrollment targets. The current paper examines, through data produced by in-depth interviews and shadowing, how 19 principals worked toward that target. Findings show that to manage enrollment principals spent, on average, 24% of their time performing marketing tasks. Principals, thus, have developed an entrepreneurial self, which is promoted by quasi-market school governance models. Through this entrepreneurship they manage various threats that represent barriers to the possibilities for meeting enrollment targets.
M-convolutions of products and ratios, statistical distributions and fractional calculus
Authors: Mathai Arakaparampil M.
Published: September 2015

It is shown that Mellin convolutions of products and ratios in the real scalar variable case can be considered as densities of products and ratios of two independently distributed real scalar positive random variables. It is also shown that these are also connected to Krätzel integrals and to the Krätzel transform in applied analysis, to reaction-rate probability integrals in astrophysics and to other related aspects when the random variables have gamma or generalized gamma densities, and to fractional calculus when one of the variables has a type-1 beta density and the other variable has an arbitrary density. Matrix-variate analogues are also discussed. In the matrix-variate case, the M-convolutions introduced by the author are shown to be directly connected to densities of products and ratios of statistically independently distributed positive definite matrix random variables in the real case and to Hermitian positive definite matrices in the complex domain. These M-convolutions reduce to Mellin convolutions in the scalar variable case.
Closed-loop transcranial alternating current stimulation of slow oscillations
Authors: Wilde Christian , Bruder Ralf , Binder Sonja , Marshall Lisa , Schweikard Achim
Published: September 2015

Transcranial alternating current stimulation (tACS) is an emerging non-invasive tool for modulating brain oscillations. There is evidence that weak oscillatory electrical stimulation during sleep can entrain cortical slow oscillations to improve the memory consolidation in rodents and humans. Using a novel method and a custom built stimulation device, automatic stimulation of slow oscillations in-phase with the endogenous activity in a real-time closed-loop setup is possible. Preliminary data from neuroplasticity experiments show a high detection performance of the proposed method, electrical measurements demonstrate the outstanding quality of the presented stimulation device.
Introducing a frequency-tunable magnetic particle spectrometer
Authors: Behrends André , Graeser Matthias , Buzug Thorsten M.
Published: September 2015

Image quality in the new imaging modality magnetic particle imaging (MPI) heavily relies on the quality of the magnetic nanoparticles in use. Therefore, it is crucial to understand the behaviour of such particles. A common technique to analyze the behaviour of the particles is magnetic particle spectrometry (MPS). However, most spectrometers are limited to measurements at a single or multiple discrete excitation frequencies. This paper introduces a frequency-tunable spectrometer, able to perform measurements in the range of 100 Hz - 24kHz.
Creating 3D gelatin phantoms for experimental evaluation in biomedicine
Authors: Stein Nils , Saathoff Thore , Antoni Sven-Thomas , Schlaefer Alexander
Published: September 2015

We describe and evaluate a setup to create gelatin phantoms by robotic 3D printing. Key aspects are the large workspace, reproducibility and resolution of the created phantoms. Given its soft tissue nature, the gelatin is kept fluid during inside the system and we present parameters for additive printing of homogeneous, solid objects. The results indicate that 3D printing of gelatin can be an alternative for quickly creating larger soft tissue phantoms without the need for casting a mold.
Numerical simulation of low-pulsation gerotor pumps for use in the pharmaceutical industry and in biomedicine
Authors: Klopsch Vincent , Germann Tomas , Seitz Hermann
Published: September 2015

The reduction of the pulsation of flow and pressure as well as the increase of the mean flow of a displacement pump will be a benefit to many technical processes, especially in the pharmaceutical industry and in biomedicine. By reducing the flow pulsation, microreactors could work more efficiently and thin-film coatings or fluids in biomedical applications could be applied with more precision. This article presents a new toolbox to analyse and compare different types of gerotor pump gear profiles. The main objective was the development of a toolbox to analyse the mean flow and the flow ripple of theoretical and reverse engineered gerotor gear sets. For that reason, the presented toolbox does not work with analytic functions, but with numerical methods based on point cloud data. A comparison of four different profile types shows that these profiles perform very differently if they are limited by a given maximal outer root diameter and by the numbers of the teeth of both rotors.
Simulation based investigation of source-detector configurations for non-invasive fetal pulse oximetry
Authors: Böttrich Marcel , Ley Sebastian , Husar Peter
Published: September 2015

Transabdominal fetal pulse oximetry is a method to monitor the oxygen supply of the unborn child non-invasively. Due to the measurement setup, the received signal of the detector is composed of photons coding purely maternal and photons coding mixed fetal-maternal information. To analyze the wellbeing of the fetus, the fetal signal is extracted from the mixed component. In this paper we assess source-detector configurations, such that the mixed fetal-maternal components of the acquired signals are maximized. Monte-Carlo method is used to simulate light propagation and photon distribution in tissue. We use a plane layer and a spherical layer geometry to model the abdomen of a pregnant woman. From the simulations we extracted the fluence at the detector side for several source-detector distances and analyzed the ratio of the mixed fluence component to total fluence. Our simulations showed that the power of the mixed component depends on the source-detector distance as expected. Further we were able to visualize hot spot areas in the spherical layer model where the mixed fluence ratio reaches the highest level. The results are of high importance for sensor design considering signal composition and quality for non-invasive fetal pulse oximetry.
Impact of electrode geometry on force generation during functional electrical stimulation
Authors: Loitz Jan C. , Reinert Aljoscha , Schroeder Dietmar , Krautschneider Wolfgang H.
Published: September 2015

The goal of functional electrical stimulation is to restore lost movements by excitation of motor axons inner-vating the target muscle. For optimal electrode placement and geometry the distribution and spatial orientation of the desired motor axons has to be known. In this study, the response of motor axons with different orientations to electrical stimulation was simulated. Three electrode geometries with the same area were used. The simulated axon activation was compared to experimental force measurements and showed good agreements. It is now assumed that optimal electrode geometry does strongly depend on motor axon orientation, which can vary from one subject to the other. Lack of knowledge about the dominant motor axon orientation makes the use of square, round or multi-pad electrodes favorable.
3D-based visual physical activity assessment of children
Authors: Maile S. , Kobel S. , Munz M. , Engleder T. , Steinacker J. M. , Capanni F.
Published: September 2015

In the last decades, an alarming rise in prevalence of childhood overweight and obesity has been observed which is partly attributed to a lack in physical activity and has started to become a public health concern. Therefore, the necessity for accurate physical activity assessment has become more and more apparent. Physical activity can be assessed objectively using accelerometers or combined devices. The application of such devices is sometimes complex and wearing the device may influence the behaviour of the test person. Therefore, assessment without any worn device would be an advantage.

A RGB-D camera device captures motion of the test person in a specific measurement area. After reducing the data and subtraction of the voxel distance, an activity level can be calculated.

The calculated activity level is similar to acceleration data of common monitoring devices. The calculated activity level is the sum of the person’s activity. Little activity with small movement can be differentiated from intense activity with large movement and high acceleration as well as no activity. The data can be structured in body-activity and limb-activity. Classifying those categories increases the benefit of this assessment compared to common accelerometers.

With the RGB-D based assessment objective, contextual information of different physical activity levels can be provided. Physical activity assessment without a worn device offers advantages such as the lack of manipulation of the device and its positioning, also the person’s compliance is no issue influencing the assessment. The RGB-D based assessment is similar to acceleration data and can be converted into comparable data and units after calibration. For more specific assessments a validation with accelerometers and the calibration of the derived data is necessary.
Brief aus Brasilien
Authors: Klotz Christian
Published: September 2015

This letter from Brazil gives a brief introduction to the history of philosophy in Brazil and an overview of the present situation of philosophy at Brazilian universities. It puts the development of Brazilian academic philosophy into the context of the political changes Brazil has undergone since the foundation of its first universities. Finally, the letter points out some difficulties which Brazilian academic philosophers face today.
Impact Investing: A Primer and Review of the Literature
Authors: Clarkin John E. , L. Cangioni Carole
Published: September 2015

Once viewed at opposite ends of a spectrum, financial investment and philanthropy are becoming partners in social enterprise development. Impact investing (II) is one of the most innovative ways to bring the resources of the world’s financial markets to the world’s seemingly intractable problems. Since its emergence from the socially responsible investment field, interest in II has grown substantially among a wide variety of practitioners and service providers throughout the world, although scholarly work in the field is scarce. To stimulate interest in this topic, this paper provides a primer and review of the current knowledge base in II. Our wide search of resources on the topic revealed potential contributions from the legal, financial, social entrepreneurship, and project management literature. We found several themes in our synthesis of the reports, articles and surveys included in our study, and several areas where gaps were evident. In general, practitioners focused on the opportunities of II and its potential, while few studies addressed the challenges associated with its implementation. Because II is not a panacea and is inappropriate for many social enterprises, opportunities exist for studies that rigorously examine the applicability and efficacy of II initiatives. This review of the literature provides scholars with an overview of II and a large number of potential resources to aid in their efforts to advance the knowledge base in the field.
Completing the Cycle in Entrepreneurial Research: Action Research to Link Entrepreneurs and Researchers and Reform the University
Authors: Greenwood Davydd James
Published: September 2015

Chandra and Zachary’s recent major book,
Performance Analysis and Optimization of a Dual Warhead System
Authors: Guo Xiao-Jun , Wen He-Ming
Published: September 2015

In modern warfare earth penetrating weapons are often used to defeat enemy’s hardened and deeply buried targets such as aircraft shelters and bunkers. A dual warhead system (DWS) is one of such weapons composed of a forward shaped charge (FSC) and a following through warhead (FTW). In this paper, an analytical model is first proposed to analyze the penetration of an FTW into concrete targets with pre-drilled holes and a DWS is then optimized in order to achieve its best penetration performance. The effects of various parameters on the performance of a dual warhead system penetrating a concrete target are delineated. It transpires that the present model predictions are in good agreement with available experimental data and that the results obtained may be useful for designing such weapon systems.
Analysis of Thermoviscoplastic Effects on Dynamic Necking of Pure Copper Bars during Impact Tension
Authors: Ma Dongfang , Chen Danian , Shanxing Wu , Wang Huanran , Hou Yanjun , Cai Canyuan , Deng Gaotao
Published: September 2015

In order to make effective measure for the stress, strain and strain rate in the specimen, a tensile split Hopkinson bar (TSHB) was optimized in the first loading duration and the thermoviscoplastic models for a pure copper were determined. The deformation of the pure copper bar during the multi-tensile loading including the necking process in the optimized TSHB testing was recorded by a high speed camera and was used in providing an extensional check of the determined thermoviscoplastic models of the pure copper. The thermoviscoplastic models determined in a certain range of strain were employed in numerically simulating the large deformation of the pure copper bar to adjust the thermoviscoplastic model to describing large strain range. The instability strain of thermoviscoplastic materials in simple tension given by Batra et al was compared with the experimental strain at diffuse necking of the pure copper bar and the computed instability strain based on the load-average strain of the pure copper bar. The local necking of the pure copper bar in the optimized TSHB testing was numerically simulated using the micro-mechanical data given by Ragab and was compared with the recorded necking.
Experimental and Numerical Study on the Dynamic Buckling of Ping-pong Balls under Impact Loading
Authors: Zhang X. W. , Yu T. X.
Published: September 2015

By means of ping-pong balls, the dynamic buckling behaviours of thin-walled spherical shells under impact loading are studied both experimentally and numerically. First, the quasi-static tests were conducted on an MTS tester, in which the ball was compressed onto a PMMA plate. Apart from the force-displacement relationship, the evolution of the contact zone between the ball and the plate was obtained by a digital camera. In the impact tests, ping-pong balls were accelerated by an air-gun and then impinged onto a rigid plate with the velocity ranging 10–45 m/s. The local dynamic buckling processes of the ball were recorded by a high-speed digital camera, from which the impact duration, the maximum contact diameter, as well as the contact diameter at snap-through buckling under different impact velocities were obtained. It is found that with the same size of contact zone, the dynamic energy absorption of the ball is much larger than that in the quasi-static tests. To understand the dynamic effects in the impact process, numerical simulations were performed by using different material properties and different impact velocities. The comparison between the experimental and numerical results show that the kinetic energy absorption of the ball is induced by the strain-rate effect, local vibration of the ball and viscous-elastic effect, respectively.
Strain Rate Effects on the Interaction between an Eccentric Matrix Crack and a Circular Inclusion in Composites under Dynamic Loadings
Authors: Liu Lu-Guang , Ou Zhuo-Cheng , Pi Ai-Guo , Duan Zhuo-Ping , Huang Feng-Lei
Published: September 2015

The interaction between an eccentric matrix crack and a circular inclusion in composites was investigated numerically to explore the strain rate effects on the crack deflection/penetration behavior at the matrix-inclusion interface. It is found, with the increase of strain rate, that there will occur in turn the crack deflection, the double-crack fracture and the crack penetration processes for a certain material. Moreover, both higher relative interfacial strength and smaller eccentric angles can redound to the crack penetration. Additionally, it is demonstrated that the strain rate effect on the composite strength is a local structural response characteristic rather than an intrinsic material property, which sounds in agreement with that proposed by previous authors.
A Microscopic Approach to Strain-rate Effect on the Compressive Strength of Concrete-like Materials
Authors: Lu Yubin
Published: September 2015

The micromechanical damage model proposed in Huang et al. (2002) [Huang C, Subhash G, Stanley JV. A dynamic damage growth model for uniaxial compressive response of rock aggregates. Mech Mater 2002;34:267–277] is modified to predict the dynamic damage evolution of concrete subjected to dynamic axial compression loads under different lateral confinement conditions. It shows that the stress–strain response, the compressive strength and the damage growth rate are strongly influenced by the confining pressure. It is also found that when the strain-rate exceeds 10
4
s
-1
, the compressive strength tends to be greatly depended on strain-rates.
Experiments and Modeling of Failure and Fragmentation of Alumina Cylinders under Uniaxial Compression
Authors: Wang Yong-Gang , Hu Jian-Dong , Zhou Feng-Hua
Published: September 2015

Quasistatic compressive strength of alumina cylinders was measured using specimen of two sizes. The strength of the material was dependent on the specimen size. High speed video photography showed that the failure of the cylindrical specimen started from axial splitting, and after failure the specimen fragmentized into small pieces. A fragmentation model was proposed for estimating the average sizes of the fragments. The calculated fragment sizes agreed reasonably well with the experimental data. By using Ls-Dyna software, the failure of cylindrical specimen containing pre-existing crack-like flaws had been simulated.
Numerical Analysis of Shockwave Propagation in Urban Underpass
Authors: Li Xin , Wang Zhihua , Wu Guiying
Published: September 2015

As an indispensable part of transportation system, urban underpass can alleviate traffic congestion and reduce traffic accidents effectively. In order to acquaint the hydrodynamics of shockwave in underpass and assess the potential damage and risk of bombing accidents, a numerical simulation was established to calculate the blast effects originating from the 13Kg TNT. Based on the location of detonation point, the shape of corridor section and the exit’s cover, peak pressure distributions were predicted. The results indicate that the propagation of shockwave in horizontal direction switches to the inclined top of ground in a near-field due to the ground reflection and the set of exit’s cover increases the risk of explosion to the structure and the users.
Radiation Characteristics of a Reflector Antenna Under Shock Wave Loading
Authors: Liu Yan , Yuan Junming , Dong Lu , Huang Fenglei
Published: September 2015

In this paper, the radiation characteristics of a reflector antenna with surface deformation were numerically simulated. The deformation of the reflector antenna under shock wave loading was simulated by LSDYNA software and the far-field patterns of these deformed reflector antennas were calculated by FEKO software. The structure-deformed reflector antennas obtained by LSDYNA software were used as the initial structure of the reflector antennas for calculating the radiation characteristics. The equations were derived to calculate the far field of the reflector antenna according to the physical optics method. As a consequence, according to the encounter modes of the shock wave and the antenna, the far-field patterns were investigated under three conditions of the shock wave frontal action, rear action and oblique action on the antenna.
A Spherical Cavity Expansion Penetration Model for Concrete Based on Hoek–Brown Strength Criterion
Authors: Xu H. , Wen H. M.
Published: September 2015

A spherical cavity expansion model for concrete is first proposed by using an elastic-brittle-plastic material law with Hoek–Brown strength criterion. The constitutive model can capture the basic features of the mechanical response of concrete materials including the effects of strain-softening and pressure hardening (pressure-dependent shear strength) and all the parameters used in the model can be determined from material tests. The forcing function obtained from the spherical cavity expansion analysis is then employed to construct a penetration model for concrete targets struck by ogival-nosed projectiles. It transpires that the present model predictions are in good agreement with experimental observations in terms of penetration depth and ballistic limits/residual velocities in the case of perforation.
Mechanism of High-velocity Projectile Penetration into Concrete
Authors: Wu Hai-Jun , Wang Yinan , Shan Yu , Huang Feng-Lei , Li Qing-Ming
Published: September 2015

The penetration depth of rigid projectiles is investigated using the modified spherical cavity expansion theory and the Holmquist–Johnson–Cook (HJC) model for the concrete targets, in which the model parameters used in the Mohr–Coulomb Tresca-limit yield criterion are obtained by the triaxial compression tests. By comparing the cavity expansion pressures of the concrete samples with two different types of aggregate, the influence of the aggregate hardness on the penetration processes is discussed. With the analysis of the tractions acted on the projectile nose, the influences of the projectile and target material properties as well as the projectile structure on the transition impact velocity are also discussed. By comparing the theoretical results with the experimental data, two penetration mechanisms are demonstrated for the ogive-nose projectile penetration into concrete with the striking velocities up to 2.0 km/s.
Effects of HMX Particle Size on the Shock Initiation of PBXC03 Explosive
Authors: Wen Li-Jing , Duan Zhuo-Ping , Zhang Lian-Sheng , Zhang Zhen-Yu , Ou Zhuo-Cheng , Huang Feng-Lei
Published: September 2015

A series of shock initiation experiments are performed on the PBXC03 explosives in different formulations to understand the influence of the explosive particle size on the shock initiation, and the in-situ pressure gauge data are obtained which show that shock sensitivity decreases with the explosive particle size under the test condition used in this paper. Moreover, a mesoscopic reaction rate model which is calibrated by the experimental data on a medium formulation PBXC03 explosive is adopted and then applied to predict numerically the shock initiation of other PBXC03 explosives in different formulations. The numerical results are in good agreement with the experimental data.
CFD Predictions of Sufficient Suspension Conditions in Solid-Liquid Agitated Tanks
Authors: Tamburini A. , Brucato A. , Cipollina A. , Micale G. , Ciofalo M.
Published: September 2015

Most research efforts on mechanically agitated solid-liquid contactors have been devoted to the assessment of the minimum impeller speed for complete off-bottom suspension, N

js
. Actually, many industrial vessels are operated at impeller speeds slightly lower than N

js
(Oldshue, 1983; Rieger et al., 1988). This suggests that the sufficient suspension condition, which is quantitatively specified in this paper by introducing a suitably defined quantity N

ss
, may represent a valid alternative to that of complete suspension.

In the present work time-dependent RANS simulations were carried out with the aim of predicting the achievement of sufficient suspension conditions. The Eulerian-Eulerian Multi Fluid Model along with the Sliding Grid algorithm were employed. The Unsuspended Solids Criterion (USC) (Tamburini et al., 2011a) was adopted to distinguish the suspended particles from the unsuspended ones.

The experimental suspension curves (mass fraction of suspended particles versus impeller speed, i.e. x

susp
vs N) collected by Tamburini et al. (2011a) and the relevant N

ss
values were predicted by the present CFD simulations and a very good agreement was found, with maximum discrepancies of about 4%.

Moreover, CFD results were used to test the ability of some N

js
assessment methods proposed in the literature to predict sufficient suspension conditions.
Highly Non-linear Microfluidic Resistor Elements for Flow Rate-dependent Addressing of Microchannels
Authors: Rajah Luke , White Duncan A. , Knowles Tuomas P. J.
Published: September 2015

We have developed a microfluidic resistor element exhibiting a hydrodynamic resistance that is strongly dependent on the pressure at the inlet of the device. Such an element can be used to construct microfluidic circuits that possess a highly non-linear dependence between the pressure and the flow rate, in contrast to conventional microfluidic resistors. We show that this effect can be exploited to create valves which do not require an external control line, but are actuated directly through the pressure difference between the single inlet and outlet of the device. Furthermore, we show that the flux to each branch of the circuit controlled by the valve can be fixed for high or low flow rates by modifying the fixed resistances internal to the device.
Equiatomic cerium intermetallics CeXX′ with twopelements
Authors: Pöttgen Rainer , Chevalier Bernard
Published: September 2015

The equiatomic CeXX′ phases (XandX′ = elements of the 3rd, 4th, or 5thmain group) extend the large series of CeTXintermetallics (T= electron-rich transition metal). These phases crystallize with simple structure types, i.e. ZrNiAl, TiNiSi, CeScSi, α-ThSi2, AlB2, and GdSi2. In contrast to the CeTXintermetallics one observes pronounced solid solutions for the CeXX′ phases. The main influence on the magnetic ground states results from the absence ofdelectrons. All known CeXX′ phases show exclusively trivalent cerium and antiferro- or ferromagnetic ordering at low temperatures. The crystal chemical details and some structure-property relationships are reviewed.
The Muhammadiyah’s 47th Congress and “Islam Berkemajuan”
Authors: Ali Muhamad
Published: September 2015

The Muhammadiyah’s 47th congress or muktamar in Makassar, South Sulawesi, 18-22 Syawwal 1436 H or 3-7 August 2015, had its theme “Enlightenment Movement toward A Progressive Indonesia”. In the opening ceremony, the chairman of the central board, Din Syamsuddin, took the occasion to propose that three of the Muhammadiyah’s leaders, namely Kahar Mudzakir, Ki Bagus Hadikusumo, and Kasman Singodimejo, be recognized as national heroes. President Ir. Joko Widodo has yet to respond to the proposal, but expressed his high appreciation for the Muhammadiyah’s contributions as the enlightenment and progressive movement to the Muslim community and the nation through its schools and universities, hospitals, and others. Joko Widodo pointed to the challenge of the nation’s plurality, and invited participants to continue to give their enlightening contributions to the nation and to the world.DOI: 10.15408/sdi.v22i2.1978
Range extension of Oxymycterus wayku (Mammalia: Rodentia: Cricetidae), an endemic species from austral Yungas, and first record for Catamarca province, northwestern Argentina
Authors: D'Hiriart Sofia , Ortiz Pablo E. , Russo Candela , Jayat J. Pablo
Published: September 2015

Oxymycterus wayku Jayat, D’Elía, Pardinãs, Miotti & Ortiz, 2008, a rodent species recently described, is known in only four localities within the Subtropical Mountain Forests of the Yungas eco-region in Tucumán, northwestern Argentina. Specimens were recorded in an owl pellet sample during a recent survey. This record represents the first for Oxymycterus in Catamarca Province, extending approximately 60 km south its southern distribution in the region. Sixteen other small non-volant mammal species were recorded there, turning this area into one of the most diverse for this understudied group in Argentina.
Resgates da memória e da história
Authors: Oliveira Juliana Prestes de , Oliveira Amanda Laís Jacobsen de , Alós Anselmo Peres
Published: September 2015

Este trabalho visa apresentar um breve estudo sobre o romance Austerlitz (2008), do escritor W. B. Sebald. Para isso, busca-se fazer aproximações entre a memória do protagonista Austerlitz, o modo como esse teve sua vida modificada e sua família destruída pelo regime nazista de Hitler durante a Segunda Guerra Mundial, e a História de uma época marcada por essa guerra. O autor nos conduz à dimensão dos pensamentos e da memória de alguém que luta para fugir de qualquer coisa que possa levá-lo ao seu passado e a rememoração de fatos que marcaram negativamente a sua vida. Por meio disso, podemos construir uma nova versão da História da época, através da voz de alguém que vivenciou esse período conturbado. Além disso, esse romance traz à tona a questão da importância de se relatar as histórias e experiências daqueles que não estão diretamente ligados aos discursos oficiais, para que esses fatos sejam vistos sob novas perspectivas e não caiam no esquecimento.
Entrevista com Roberto Schwarz
Authors: Paula Felipe Oliveira de
Published: September 2015

Em Entrevistas temos sete repostas de Roberto Schwarz sobre sua formação, literatura, política, estética, entre outras questões
Fotografias
Authors: Polidori Robert
Published: September 2015

Seis imagens do artista Robert Polidori
Effectiveness of heuristic evaluation in usability evaluation of elearning applications in higher educ
Authors: Ssemugabi Samuel , De Villiers Ruth
Published: September 2015

The Internet, World Wide Web (WWW) and e-learning are contributing to new forms of teaching and learning. Such environments should be designed and evaluated in effective ways, considering both usability- and pedagogical issues. The selection of usability evaluation methods (UEMs) is influenced by the cost of a methods and its effectiveness in addressing users’ issues. The issue of usability is vital in e-learning, where students cannot begin to learn unless they can first use the application. Heuristic evaluation (HE) remains the most widely-used usability evaluation method. This paper describes meta-evaluation research that investigated an HE of a web-based learning (WBL) application. The evaluations were based on a synthesised framework of criteria, related to usability and learning within WBL environments. HE was found to be effective in terms of the number and nature of problems identified in the target application by a complementary team of experienced experts. The findings correspond closely with those of a survey among learners.