bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of Localized Thinning of Copper Tube Hydroforming in Square Section Die: Effect of Friction Conditions
Authors: Abdelkefi Abir , Boudeau Nathalie , Malecot Pierrick , Guermazi Noamen , Michel Gérard
Published: July 2015

The friction conditions are responsible of the thickness distribution in a part realized by tube hydroforming. Then it is essential to have a good evaluation of the friction coefficient for running predictive finite element simulations. The tube expansion in a square die is one of tests proposed for the friction evaluation. In the literature, several analytical models have been developed for this specific test. The present paper concentrates on one of this model and results obtained from the analytical analysis, FE simulations and experiments are compared. The repartition of the thickness over the shaped tube and its evolution during the process are studied. The tendencies are in agreement but some complementary evaluations are proposed for using the proposed approach for the evaluation of the friction coefficient with the analytical model.
Microstructure and Mechanical Properties of Inconel 718 Produced by SLM and Subsequent Heat Treatment
Authors: Popovich Anatoly A. , Sufiiarov Vadim Sh. , Polozov Igor A. , Borisov Evgenii V.
Published: July 2015

The article presents results of selective laser melting of Inconel 718 superalloy. It was studied phase microstructure of the material obtained by selective laser melting and also the material after heat treatment. The phase composition of the initial powder material, the specimens after selective laser melting before and after heat treatment was studied. The effect of heat treatment on microstructure and mechanical properties of the specimens was shown. It was studied the mechanical behavior of the manufactured specimens before and after heat treatment at room and elevated temperatures as well. The results of impact tests and fractography of the specimens are presented. Mechanical tests showed that the specimens after heat treatment have decent mechanical properties comparable to hot-rolled material. Fractography showed that the obtained material is characterized by ductile failure mode with local elements of brittle fracture.
Tailor-Made Forging Tools by Laser Metal Deposition
Authors: Junker Daniel , Hentschel Oliver , Schmidt Michael , Merklein Marion
Published: July 2015

The desire for individualized products forces the companies to a great diversity of combinable parts. This way, the clients can compile their personalized product. As this trend is not just limited on visual parts but also for functional components, laser additive manufacturing of metals is used more and more often in manufacturing. To bring more additive manufacturing into mass production, Laser Beam Melting and Laser Metal Deposition will be qualified for the use in tool manufacturing within the Bavarian research association “ForNextGen – Next Generation Tools”. The first subproject within this research association investigates the potential of Laser Metal Deposition in the production of hot and cold forging tools. Within initial tests optimized process, parameters for the processing of the hot-work steel 1.2709 are determined by single welding beads. The achieved density and the inner structure are analyzed within cubes that were built with the investigated parameters. As forging tools are usually made of high-carbon tool steel, the processing of materials with a rising percentage of carbon will be part of further investigations.
Parametric Analysis of Micro Electrical Discharge Milling Process of Non-Conductive Silicon Carbide
Authors: Zeller Florian , Ojha Nirdesh , Müller Claas , Reinecke Holger
Published: July 2015

Silicon carbide (SiC) is a high performance ceramic material which is increasingly used in applications which demand for high temperature stable materials. The microstructuring of this material in its sintered state is a challenge for conventional machining methods due to its extraordinary mechanical properties. To overcome these limitations the process of electrical discharge machining (EDM) was modified with a so called assisting electrode (AE) to enable the structuring of non-conductive ceramics such as SiC. This paper presents a parametric analysis of micro electrical discharge milling process of non-conductive SiC for two different tool materials, tungsten carbide (WC) and copper (Cu). A full factorial design with four factors was conducted. The significant factors are shown with main effects plots. Two sets of optimized parameters for maximum material removal rate (MRR) and minimum tool wear rate (TWR) for both tool materials are presented. Hardness and surface roughness are measured and compared to the non-machined material.
A Review of Flow Forming Processes and Mechanisms
Authors: Marini Daniele , Cunningham David , Corney Jonathan
Published: July 2015

After years of pure academic interest and niche applications, today the flow forming process is growing in its importance in the forming industry, due to increasing demand in aerospace, automotive and defense industries. The review surveys academic paper of last fifty years, in order to evaluate the current state of art for academic and practitioner. Theoretical and experimental approaches are collected and compared evaluating their prediction models. Several knowledge gaps can be identified. Stress and strain tensors evolutions are not determined for workpiece, due to high computational cost and missing identification of correct finite elements approach. Final microstructure is often evaluated case by case but its evolution during plastic deformation is not studied. Residual stress and final material proprieties, as corrosion behavior, have been not studied numerically or experimentally. Tool path impact and alternative geometries are not deeply explored. Process experimental optimization and characterization through Design of Experiment is still limited to a few papers and usually not well developed.
Tailor Tempering and Hot-Spotting of Press Hardened Boron Steels
Authors: Galdos Lander , Saenz de Argandoña Eneko , Mendiguren Joseba , Herrero Nuria , Ortubay Rafael , Agirretxe Xabier , Martín José Miguel
Published: July 2015

Hot forming processes are becoming a successful solution when complex geometrical components with high mechanical properties are desired. In fact, automotive structural components with tensile strengths higher than 1500MPa are being nowadays industrially produced. The technology is based on the forming and quenching of the sheet inside the forming tool using boron steels. Aiming at boosting the advantages of this technology, car manufacturers have started to demand structural components with different mechanical behavior areas in order to improve the impact response of the auto-motive passenger compartment: the so called tailor tempered components. The basic idea is to obtain final parts with different properties like it has been successfully done using tailored welded blanks. Although different solutions exist, one of the most common strategy is to use partially heated tooling, which influences the cooling of the sheet and consequently the local properties. At the present work, a special tooling with independent heated and cooled areas has been developed in order to evaluate the final properties achievable in the tailored tempering process. High and low conductivity alloys have been used to find the process limits and compare them to classical tool steels. Hardness values, Ultimate Tensile Stresses and microstructures are shown for different steels, tool temperatures and contact pressures. In the last part of the paper, the hot spotting results are presented. Different air gap diameters have been used to evaluate the possibility to create soft spots that will enable an easier cutting of geometrically accurate holes and a more suitable and ductile join between different components by using the spot welding.
Numerical Implementation of a Rheology Model for Fiber-Reinforced Composite and Viscous Layer Approach for Friction Study
Authors: Salazar Betancourt Luis Fernando , Laure Patrice , Silva Luisa , Sager Mustafa
Published: July 2015

A transverse isotropic viscous model accounting for the anisotropy exhibited in fiber-reinforced composite is integrated in the numerical platform of the software Rem3D®. Simulations under various mechanical loading are tested for volume fiber concentrations of 3.5% and 14.7%. Equivalent stresses and equivalent strain rate deformations given by the software were compared to the ones predicted by the model, finding very good agreements. As a second point developed on this paper, we comment on the slip condition between Die/Punch tool with the composite under compression. We noticed that the variation of the viscosity value on a small layer between the Die/Punch tooland the composite affects the nature of the contact. A viscous friction is then formulated as a technique to set slip/no-slip contact condition. We found that the slip condition is recovered at lower values of the viscosity in the interface Die/Punch with the reinforced composite, whereas the no slip condition stated for higher viscosity values.
Improving the Ramp-Up Process of a Body-Construction Line by Numerical Supported Design of Clamping Devices and FEM Based Tolerance Prognosis
Authors: Landgrebe Dirk , Ackert Patrick , Grützner Raik , Weber Johannes , Mauermann Reinhard , Tegtmeier André
Published: July 2015

The use of FEM (finite element method) to assistant in ramp-up processes of car body construction lines is increasing, thanks to developments in recent years [1-3]. Car body manufacturing begins with sheet metal forming, while in subsequent steps the inner structures of the vehicle are assembled and connected to the outer skin by hemming. With reference to the current state of the art, there is no methodology which can reliably predict the dimensional accuracy of body parts through metal forming [4].Additionally, several methods to predict the distortion of joining and the dimensional effect of clamping during the assembly process were presented and validated [4-11]. Dimensional effects of the clamping process are basically the result of a deliberate alignment, other than the given values of construction to compensate dimensional inaccuracy of single parts from the body shop. These deliberate alignments are generally effected through a translation of clamps and pins in the clamping device. Until now, most of the methods of clamping and joining simulation presented have been verified using academic samples.In this report, the quality of forecasting in real problems during a ramp-up process will be verified and expanded. As part of a national project, co-funded by Sächsische Aufbaubank (SAB), the potential of FEM to assist in the ramp-up process were reviewed in a cooperative effort between Porsche Leipzig GmbH and Fraunhofer Institute for Machine Tools and Forming Technology (IWU). Furthermore, it will be shown that developed methods are able to represent the influence of deliberate positioning of clamps in complex samples. For the first time the quality of forecasting through the translation of locating pins is numerically and experimentally qualified.
A Microstructure Based Model for the Mechanical Behavior of Multiphase Steels
Authors: Kok P.J.J. , Spanjer W. , Vegter Henk
Published: July 2015

Multiscale tools are important for the development of multiphase steel grades within Tata Steel R&D. The spatial distribution and morphology of the hard and soft phases in the microstructure as well as their micromechanical properties influences strongly the macroscopic behaviour. To be able to predict the macroscopic response and be of use in an industrial research environment accurate modelling on microscale has to be coupled to efficient homogenization principles. A new algorithm, which extends the capabilities of voronoi tessellations has been developed capturing relevant microstructure parameters. In this paper we show the versatility of the algorithm in simulating many microstructure features in 2 and 3 dimensions and how it is used for micromechanical simulations.
The Uncertainty and Robustness of the Principal Component Analysis as a Tool for the Dimensionality Reduction
Authors: Pietraszek Jacek , Skrzypczak-Pietraszek Ewa
Published: July 2015

Experimental studies very often lead to datasets with a large number of noted attributes (observed properties) and relatively small number of records (observed objects). The classic analysis cannot explain recorded attributes in the form of regression relationships due to lack of sufficient number of data points. One of method making available a filtering of unimportant attributes is an approach known as ‘dimensionality reduction’. Well-known example of such approach is principal component analysis (PCA) which transforms the data from the high-dimensional space to a space of fewer dimensions and gives heuristics to select least but necessary number of dimensions. Authors used such technique successfully in their previous investigations but a question arose: whether PCA is robust and stable? This paper tries to answer this question by re-sampling experimental data and observing empirical confidence intervals of parameters used to make decision in PCA heuristics.
The Empirical Assessment of the Convergence Rate for the Bootstrap Estimation in Design of Experiment Approach
Authors: Osocha Przemysław , Ulewicz Robert , Szataniak Paweł , Pietraszek Mariusz , Kołomycki Maciej , Radek Norbert , Pasieczyński Łukasz
Published: July 2015

Design of experiment (DoE) is a set of practical recipes and theoretical assumptions leading to the optimization of the technological process and/or the stabilization of its output quality. Practically, all the DoE approaches assume the normality of a random noise and the quasi-linearity of models taken from the general linear model (GLM) class. It allows to use traditional least-square methodology to identification of a model parameters and their confidence intervals. It gives usually sufficient results but completely fails if the model is not from GLM class or a random noise has not a normal distribution. The solution for such problems is the bootstrap approach, a resampling method based on Monte Carlo strategies. This paper tries to answer a question how many repetitions should be made to estimate parameters of the prediction model with sufficient accuracy.
People with Psychogenic non-epileptic seizures: A South African perspective
Authors: Pretorius Chrisma , Cronje Gretha
Published: July 2015

Background: Psychogenic non-epileptic seizures (PNES) is a disabling disorder which has a negative effect on the quality of life of individuals with PNES. A clear understanding of the disorder is necessary, however, to date, research about PNES in South Africa is limited.Objectives: The aims of this study were to explore the demographic variables of individuals with PNES in South Africa, to review the available body of research on PNES, and to compare it with our results.Method: Twenty-two people with PNES, with confirmed video EEG, were recruited by means of convenience sampling from two hospitals. Descriptive statistics were used to describe the demographic variables of the participants.Results: Internationally comparable results revealed misdiagnoses and low treatment delivery amongst a primarily female population.Conclusion: This study provided greater insight into individuals with PNES in South Africa, highlighting the need for more information, support, effective treatment and accurate diagnosis of PNES.
Freirean principles and critical literacy to counter retrograde impulses in the Curriculum and Assessment Policy Statement
Authors: Chetty Rajendra
Published: July 2015

Inherent in the Curriculum and Assessment Policy Statement (CAPS) document are inferences of transmission and reproduction that run counter to the emancipatory imperatives of core educational policy documents enacted after democracy in 1994. Some structural inadequacies in implementation of the first curricular changes to outcomes-based education have opened the way to reactionary and retrograde pedagogy which appears to privilege the teacher and textbook as sole authorities in the classroom. The purpose of this article, therefore, is to warn against teacher-centred pedagogy and restate the significance of Freirean principles in the establishment of a student-centred educational environment, specifically in the field of critical literacy. In defence of Freirean thought, a re-consideration of literacy and critical literacy grant legitimacy to the learner and demonstrate that individual experience is foundational to knowledge construction in a participatory manner which accords with the vision and original principles of education in the new South Africa.
Quantitative assessment of sustainable city logistics
Authors: Grosso-delaVega Rafael , Muñuzuri Jesus
Published: July 2015

The aim of this paper is to seek an answer to an specific question: how to make city logistics sustainable? This question in principle has no specific answer. By contrast, it could be answered in many and varied ways. Behind the search for some of these answers lies the development of a roadmap which this work aims to present. The research lines, the theoretical framework and methodology of the roadmap will be explained. Although the current status of the roadmap, its duration and timing still need to be completed, the main facts, as well as the results obtained to date and the expected results are here presented.
Impacts of aviation fuel sulfur content on climate and human health
Authors: Kapadia Z. Z. , Spracklen D. V. , Arnold S. R. , Borman D. J. , Mann G. W. , Pringle K. J. , Monks S. A. , Reddington C. L. , Benduhn F. , Rap A. , Scott C. E. , Butt E. W. , Yoshioka M.
Published: July 2015

Abstract. Aviation emissions impact both air quality and climate. Using a coupled tropospheric chemistry-aerosol microphysics model we investigate the effects of varying aviation fuel sulfur content (FSC) on premature mortality from long-term exposure to aviation-sourced PM2.5 (particulate matter with a dry diameter of < 2.5 μm) and on the global radiation budget due to changes in aerosol and tropospheric ozone. We estimate that present-day non-CO2 aviation emissions with a typical FSC of 600 ppm result in 3597 (95 % CI: 1307–5888) annual mortalities globally due to increases in cases of cardiopulmonary disease and lung cancer, resulting from increased surface PM2.5 concentrations. We quantify the global annual mean combined radiative effect (REcomb) of non-CO2 aviation emissions as −13.3 mW m−2; from increases in aerosols (direct radiative effect and cloud albedo effect) and tropospheric ozone. Ultra-low sulfur jet fuel (ULSJ; FSC =15 ppm) has been proposed as an option to reduce the adverse health impacts of aviation-induced PM2.5. We calculate that swapping the global aviation fleet to ULSJ fuel would reduce the global aviation-induced mortality rate by 624 (95 % CI: 227–1021) mortalities a−1 and increase REcomb by +7.0 mW m−2. We explore the impact of varying aviation FSC between 0–6000 ppm. Increasing FSC increases annual mortality, while enhancing climate cooling through increasing the aerosol cloud albedo effect (aCAE). We explore the relationship between the injection altitude of aviation emissions and the resulting climate and air quality impacts. Compared to the standard aviation emissions distribution, releasing aviation emissions at the ground increases global aviation-induced mortality and produces a net warming effect, primarily through a reduced aCAE. Aviation emissions injected at the surface are 5 times less effective at forming cloud condensation nuclei, reducing the aviation-induced aCAE by a factor of 10. Applying high FSCs at aviation cruise altitudes combined with ULSJ fuel at lower altitudes result in reduced aviation-induced mortality and increased negative RE compared to the baseline aviation scenario.
Study of the regional CO2 mole fractions filtering approach at a WMO/GAW regional station in China
Authors: Fang S. X. , Tans P. P. , Steinbacher M. , Zhou L. X. , Luan T.
Published: July 2015

Abstract. The identification of atmospheric CO2 observation data which is minimally influenced by very local emissions/removals is essential for the estimation of trend analysis, regional sources and sinks, and for modeling of long-range transport of CO2. In this study, four approaches are used to filter the atmospheric CO2 observation records from 2009 to 2011 at one World Meteorological Organization/Global Atmosphere Watch (WMO/GAW) regional station (Lin'an, LAN) in China. The methods are based on the atmospheric black carbon concentration (BC), on a statistical approach (REBS), on CH4 as auxiliary tracer (AUX) and on meteorological parameters (MET). All approaches do suitably well to capture the seasonal CO2 cycle at LAN. Differences are observed in the average regional mole fractions with annual values in the REBS method at least 1.7 ± 0.2 ppm higher than the other methods. The BC method may underestimate the regional CO2 mole fractions during winter-spring period and should be treated with caution. The REBS method is a purely statistical method and it may also introduce errors on the regional CO2 mole fractions evaluations, as the filtered trend may be deviated by the "noisy" raw data series. Although there are correlations between CH4 and CO2 mole fractions at LAN, the different source/sink regimes may introduce bias on the regional CO2 estimation in the AUX method, typically in summer. Overall, the MET method seems to be the most favorable because it mainly focuses on the influence of potential local sources and sinks and considers diurnal variations, local topography, and meteorological conditions. Using the MET method, the annual growth rate of regional CO2 at LAN is determined to be 3.1 ± 0.01 ppm yr−1 (standard error) from 2009 to 2013.
An analytical system for the measurement of stable hydrogen isotopes in ambient volatile organic compounds
Authors: Meisehen T. , Bühler F. , Koppmann R. , Krebsbach M.
Published: July 2015

Abstract. Stable isotope measurements in atmospheric volatile organic compounds (VOC) are an excellent tool to analyse chemical and dynamical processes in the atmosphere. While up to now isotope studies of VOC in ambient air mainly focus on carbon isotopes, we herein present a new measurement system to investigate hydrogen isotope ratios in atmospheric VOC. This system consisting of a GC-P-IRMS (Gas Chromatography Pyrolysis Isotope Ratio Mass Spectrometer) and a preconcentration system was thoroughly characterised using a working standard. A precision of better than 9 ‰ (in δD) is achieved for n-pentane, 2-methyl-1,3-butadiene (isoprene), n-heptane, 4-methyl-pentane-2-one (4-methyl-2-pentanone), methylbenzene (toluene), n-octane, ethylbenzene, m/p-xylene, and 1,2,4-trimethylbenzene. A comparison with independent measurements via elemental analysis shows an accuracy of better than 9 ‰ for n-pentane, n-heptane, 4-methyl-2-pentanone, toluene, and n-octane. Above a compound specific minimum peak area the obtained δD values are constant within the standard deviations. In addition, a remarkable influence of the pyrolysis process on the isotope ratios is found and discussed. Reliable measurements are only possible if the ceramic tube used for the pyrolysis is sufficiently conditioned, i.e. the inner surface is covered with a carbon layer. It is essential to verify this conditioning regularly and to renew it if required. Furthermore, influences of a necessary H3+ correction and the pyrolysis temperature on the isotope ratios are discussed. Finally, the applicability to measure hydrogen isotope ratios in VOC at ambient levels is demonstrated with measurements of outside air on five different days in February and March 2015. The measured hydrogen isotope ratios range from −136 to −105 ‰ for n-pentane, from −86 to −63 ‰ for toluene, from −39 to −15 ‰ for ethylbenzene, from −99 to −68 ‰ for m/p-xylene, and from −45 to −34 ‰ for o-xylene.
Piezoelectric crystal microbalance measurements of enthalpy of sublimation of C2–C9 dicarboxylic acids
Authors: Dirri F. , Palomba E. , Longobardo A. , Zampetti E.
Published: July 2015

Abstract. We present here a novel experimental setup able to measure the enthalpy of sublimation of a given compound by means of Piezoelectric Crystal Microbalances (PCM). This experiment was performed in the TG-Lab facility in IAPS-INAF, dedicated to the development of TGA sensors for space measurements, such as detection of organic and non-organic volatile species and refractory materials in planetary environments. In order to study physical-chemical processes concerning the Volatile Organic Compounds (VOC) present in atmospheric environments, the setup has been tested on Dicarboxylic acids. Acids with low molecular weight are among the components of organic fraction of particulate matter in the atmosphere, coming from different sources (biogenic and anthropogenic). Considering their relative abundance, it is useful to consider Dicarboxylic acid as "markers" to define the biogenic or anthropogenic origin of the aerosol, thus obtaining some information of the emission sources. In this work, a temperature controlled effusion cell was used to sublimate VOC, creating a molecular flux that was collimated onto a cold PCM. The VOC re-condensed onto the PCM quartz crystal allowing the determination of the deposition rate. From the measurements of deposition rates, it was possible to infer the enthalpy of sublimation of Adipic acid, i.e. Δ Hsub: 141.6 ± 0.8 kJ mol−1, Succinic acid, i.e. 113.3 ± 1.3 kJ mol−1, Oxalic acid, i.e. 62.5 ± 3.1 kJ mol−1 and Azelaic acid, i.e. 124.2 ± 1.2 kJ mol−1 (weight average values). The results obtained are in very good agreement with literature within 10 % for the Adipic, Succinic and Oxalic acid.
Climate and carbon cycle dynamics in a CESM simulation from 850 to 2100 CE
Authors: Lehner F. , Joos F. , Raible C. C. , Mignot J. , Born A. , Keller K. M. , Stocker T. F.
Published: July 2015

Abstract. Under the protocols of phase 3 of the Paleoclimate Modelling Intercomparison Project, a number of simulations were produced that provide a range of potential climate evolutions from the last millennium to the end of the current century. Here, we present the first simulation with the Community Earth System Model (CESM), which includes an interactive carbon cycle, that covers the last millennium. The simulation is continued to the end of the twenty-first century. Besides state-of-the-art forcing reconstructions, we apply a modified reconstruction of total solar irradiance to shed light on the issue of forcing uncertainty in the context of the last millennium. Nevertheless, we find that structural uncertainties between different models can still dominate over forcing uncertainty for quantities such as hemispheric temperatures or the land and ocean carbon cycle response. Compared to other model simulations, we find forced decadal-scale variability to occur mainly after volcanic eruptions, while during other periods internal variability masks potentially forced signals and calls for larger ensembles in paleoclimate modeling studies. At the same time, we were not able to attribute millennial temperature trends to orbital forcing, as has been suggested recently. The climate–carbon-cycle sensitivity in CESM during the last millennium is estimated to be between 1.0 and 2.1 ppm °C−1. However, the dependence of this sensitivity on the exact time period and scale illustrates the prevailing challenge of deriving robust constraints on this quantity from paleoclimate proxies. In particular, the response of the land carbon cycle to volcanic forcing shows fundamental differences between different models. In CESM the tropical land dictates the response to volcanoes, with a distinct behavior for large and moderate eruptions. Under anthropogenic emissions, global land and ocean carbon uptake rates emerge from the envelope of interannual natural variability by about year 1947 and 1877, respectively, as simulated for the last millennium.
A 2600-year history of floods in the Bernese Alps, Switzerland: frequencies, mechanisms and climate forcing
Authors: Schulte L. , Peña J. C. , Carvalho F. , Schmidt T. , Julià R. , Llorca J. , Veit H.
Published: July 2015

Abstract. A 2600-year long composite palaeoflood record is reconstructed from high-resolution delta plain sediments of the Hasli–Aare floodplain on the northern slope of the Swiss Alps. Natural proxies compiled from sedimentary, geochemical and geomorphological data were calibrated by textual and factual sources and instrumental data. No fewer than 12 of the 14 historically recorded extreme events between 1480 and the termination of the Hasli–Aare river channel correction in 1875 were also identified by coarse-grained flood layers, log(Zr / Ti) peaks and factor 1 anomalies. Geomorphological, historical and instrumental data provide evidence for flood damage intensities and discharge estimations of severe and catastrophic historical floods. Spectral analysis of the geochemical and documentary flood series and several climate proxies (TSI, δ18O, tree-rings, NAO, SNAO) identify similar periodicities of around 60, 80, 100, 120 and 200 years during the last millennia, indicating the influence of the North Atlantic circulation and solar forcing on alpine flood dynamics. The composite floodplain record illustrates that periods of organic soil formation and deposition of phyllosilicates (from the medium high catchment area) match those of total solar irradiance maxima, suggesting reduced flood activity during warmer climate pulses. Aggradation with multiple sets of flood layers with increased contribution of siliciclasts from the highest catchment area (plutonic bedrock) (e.g. 1300–1350, 1420–1480, 1550–1620, 1650–1720 and 1811–1851 cal yr AD) occurred predominantly during periods with reduced solar irradiance, lower δ18O anomalies, cooler summer temperatures and phases of drier spring climate in the Alps. Increased water storage by glaciers, snow cover and snow patches susceptible to melting processes associated with rainfall episodes and abrupt rises in temperature substantially increased surface runoff on slopes and discharges of alpine rivers. This interpretation is in agreement with the findings that the severe and catastrophic historical floods in the Aare since 1670 occurred mostly during positive SNAO (Summer North Atlantic Oscillation) pulses after years or even decades dominated by negative SNAO and cooler annual temperatures.
Analytical model of temperature distribution in metal cutting based on Potential Theory
Authors: Klocke F. , Brockmann M. , Gierlings S. , Veselovac D.
Published: July 2015

Abstract. Temperature fields evolving during metal cutting processes have also been of major interest. Temperatures in the tool influence the wear behaviour and hence costs, temperatures in the work-piece are directly responsible for later product quality. Due to the high significance of temperatures, many modelling attempts for temperature fields have been conducted, however failed to deliver satisfying results. The present paper describes a novel analytical model using complex functions based on potential theory. Relevant heat sources in metal cutting as well as changing material constants are considered. The model was validated by an orthogonal cutting process and different real machining processes.
Asielzoekers in Europa: de geopolitieke context
Authors: Jennissen R.P.W.
Published: July 2015

Asylum seekers in Europe: the geopolitical context

In recent years, the number of asylum seekers in Europe has increased again. According to the figures of Eurostat, more than 600.000 applications for asylum were submitted in the countries of the EU in 2014. This is more than double compared to 2010. This article seeks to provide explanations for this sudden increase. Furthermore, this article contains a detailed description of the long route which refugees who lodge an asylum application in a Northern or Western European country have to accomplish. Many considerations have to be made during this route. Other people than the refugees themselves (i.e. traffickers) make these considerations as well and they are often restricted by the circumstances.
Op zoek naar bescherming in een vrije wereld
Authors: Entzinger H.B.
Published: July 2015

In search for protection in a free world. Asylum migration to Europe analyzed

The arrival of asylum seekers has become a major political and social issue in Europe recently, although not for the first time in history. This article describes and analyses the reasons why growing numbers of undocumented migrants come to Europe, many of them as asylum seekers. One important reason is growing political instability in a ring of countries that surround the EU. The article also describes the different routes undocumented migrants take to the EU, the rapid changes that occur in the choice of routes, and the backgrounds of these changes. Although most attention goes to the risky transit in the Central Mediterranean area, and the number of migrants taking this route is growing, a majority of asylum seekers has reached the EU via other routes. Finally, this article also indicates roads towards finding solutions to the issue; this can only be achieved in the context of the EU.
Een verblijfsvergunning, maar dan?
Authors: Klaver J.F.I.
Published: July 2015

A residence permit, but what then? The socio-economic integration of refugees in the Netherlands

Integration is an essential element of refugee protection. This article presents data on the socio-economic integration of refugees in the Netherlands who have received a residence status between 2000 and 2010. Many refugees are unable to integrate successfully into the Dutch labor market, which results in high levels of welfare dependency and poverty. The article furthermore discusses developments in Dutch integration policies, with a specific focus on civic integration, family reunification and citizenship. These policies are increasingly characterized by imposing more stringent requirements on migrants as a precondition for obtaining permanent residency and citizenship. As such, these policy developments prove to be counterproductive to refugee integration in the Netherlands. A brief comparison between the Netherlands on the one hand and Denmark, the United Kingdom and Belgium/Flanders on the other, shows that the Netherlands pursue a particularly severe course with regard to imposing integration requirements on refugees.
Comparison of Different Cytokine Conditions Reveals Resveratrol as a New Molecule for Ex Vivo Cultivation of Cord Blood-Derived Hematopoietic Stem Cells
Authors: Heinz Niels , Ehrnström Birgitta , Schambach Axel , Schwarzer Adrian , Modlich Ute , Schiedlmeier Bernhard
Published: July 2015

Human cord blood (CB)-derived hematopoietic stem cells (HSCs) are an interesting source for HSC transplantation. However, the number of collected CB-HSCs is often too low for one transplantation; therefore, ex vivo expansion of CB-HSCs is desirable. Current expansion protocols are based on the use of cytokine combinations, including insulin-like growth factor-binding protein 2 (IGFBP2) and angiopoietin-like proteins, or combinations with “small molecules” such as stemregenin-1. The aim of our project was to compare the potential of different CB-HSC expansion strategies side-by-side by phenotypical analysis in vitro and serial engraftment properties in NOD/SCID/IL2rg−/− (NSG) immunodeficient mice. We further identified resveratrol, a naturally occurring polyphenol, as a new, alternative small molecule combined with cytokines to facilitate serum-free ex vivo expansion of human CB-HSCs. The cultivation in resveratrol preserved the CB-HSC phenotype in vitro most efficiently and was ∼2 times more potent than commonly used cytokine conditions (including stem cell factor, thrombopoietin, Fms-related tyrosine kinase 3 ligand, interleukin-6) and the recently established serum-free culture, including IGFBP2 and angiopoietin-like 5. Serial transplantation studies further confirmed resveratrol to support robust multilineage engraftment in primary and secondary NSG recipients. Therefore, our work proposes resveratrol as a new small molecule for improved ex vivo culture and modification of human HSCs based on an efficient ex vivo propagation of the HSC fate.

Significance

Human cord blood (CB)-derived hematopoietic stem cells (HSCs) are an important source for HSC transplantations but restricted in their usage because of their low numbers. In gene therapy, modifications of HSCs relies on their ex vivo modification without losing their stemness properties. Therefore, ex vivo cultivation and expansion of CB-HSCs is important for their effective application in HSC transplantation and gene therapy. Several promising protocols for serum-free cultivation of HSCs using different combinations of cytokines or so-called small molecules are described. A direct comparison was performed of three described serum-free cytokine conditions, demonstrating that the natural occurring polyphenol resveratrol is able to support ex vivo cultivation of CB-HSCs. The results show that resveratrol is an additional candidate for improving ex vivo cultures of HSCs for transplantation and gene therapeutic applications in the future.
Mortality and loss to follow‐up among HIV‐infected persons on long‐term antiretroviral therapy in Latin America and the Caribbean
Authors: Carriquiry Gabriela , Fink Valeria , Koethe John Robert , Giganti Mark Joseph , Jayathilake Karu , Blevins Meridith , Cahn Pedro , Grinsztejn Beatriz , Wolff Marcelo , Pape Jean William , Padgett Denis , Madero Juan Sierra , Gotuzzo Eduardo , McGowan Catherine Carey , Shepherd Bryan Earl
Published: July 2015

Introduction

Long‐term survival of HIV patients after initiating highly active antiretroviral therapy (ART) has not been sufficiently described in Latin America and the Caribbean, as compared to other regions. The aim of this study was to describe the incidence of mortality, loss to follow‐up (LTFU) and associated risk factors for patients enrolled in the Caribbean, Central and South America Network (CCASAnet).

Methods

We assessed time from ART initiation (baseline) to death or LTFU between 2000 and 2014 among ART‐naïve adults (≥18 years) from sites in seven countries included in CCASAnet: Argentina, Brazil, Chile, Haiti, Honduras, Mexico and Peru. Kaplan‐Meier techniques were used to estimate the probability of mortality over time. Risk factors for death were assessed using Cox regression models stratified by site and adjusted for sex, baseline age, nadir pre‐ART CD4 count, calendar year of ART initiation, clinical AIDS at baseline and type of ART regimen.

Results

A total of 16,996 ART initiators were followed for a median of 3.5 years (interquartile range (IQR): 1.6–6.2). The median age at ART initiation was 36 years (IQR: 30–44), subjects were predominantly male (63%), median CD4 count was 156 cells/µL (IQR: 60–251) and 26% of subjects had clinical AIDS prior to starting ART. Initial ART regimens were predominantly non‐nucleoside reverse transcriptase inhibitor based (86%). The cumulative incidence of LTFU five years after ART initiation was 18.2% (95% confidence interval (CI) 17.5–18.8%). A total of 1582 (9.3%) subjects died; the estimated probability of death one, three and five years after ART initiation was 5.4, 8.3 and 10.3%, respectively. The estimated five‐year mortality probability varied substantially across sites, from 3.5 to 14.0%. Risk factors for death were clinical AIDS at baseline (adjusted hazard ratio (HR)=1.65 (95% CI 1.47–1.87); p<0.001), lower baseline CD4 (HR=1.95 (95% CI 1.63–2.32) for 50 vs. 350 cells/µL; p<0.001) and older age (HR=1.47 (95% CI 1.29–1.69) for 50 vs. 30 years at ART initiation; p<0.001).

Conclusions

In this large, long‐term study of mortality among HIV‐positive adults initiating ART in Latin America and the Caribbean, overall estimates of mortality were heterogeneous, generally falling between those reported in high‐income countries and sub‐Saharan Africa.
Paracrine Met signaling triggers epithelial–mesenchymal transition in mammary luminal progenitors, affecting their fate
Authors: Di-Cicco Amandine , Petit Valérie , Chiche Aurélie , Bresson Laura , Romagnoli Mathilde , Orian-Rousseau Véronique , Vivanco Maria dM , Medina Daniel , Faraldo Marisa M , Glukhova Marina A , Deugnier Marie-Ange
Published: July 2015

HGF/Met signaling has recently been associated with basal-type breast cancers, which are thought to originate from progenitor cells residing in the luminal compartment of the mammary epithelium. We found that ICAM-1 efficiently marks mammary luminal progenitors comprising hormone receptor-positive and receptor-negative cells, presumably ductal and alveolar progenitors. Both cell populations strongly express Met, while HGF is produced by stromal and basal myoepithelial cells. We show that persistent HGF treatment stimulates the clonogenic activity of ICAM1-positive luminal progenitors, controlling their survival and proliferation, and leads to the expression of basal cell characteristics, including stem cell potential. This is accompanied by the induction of Snai1 and Snai2, two major transcription factors triggering epithelial–mesenchymal transition, the repression of the luminal-regulatory genes Elf5 and Hey1, and claudin down-regulation. Our data strongly indicate that paracrine Met signaling can control the function of luminal progenitors and modulate their fate during mammary development and tumorigenesis.
Arcuate hypothalamic AgRP and putative POMC neurons show opposite changes in spiking across multiple timescales
Authors: Mandelblat-Cerf Yael , Ramesh Rohan N , Burgess Christian R , Patella Paola , Yang Zongfang , Lowell Bradford B , Andermann Mark L
Published: July 2015

Agouti-related-peptide (AgRP) neurons—interoceptive neurons in the arcuate nucleus of the hypothalamus (ARC)—are both necessary and sufficient for driving feeding behavior. To better understand the functional roles of AgRP neurons, we performed optetrode electrophysiological recordings from AgRP neurons in awake, behaving AgRP-IRES-Cre mice. In free-feeding mice, we observed a fivefold increase in AgRP neuron firing with mounting caloric deficit in afternoon vs morning recordings. In food-restricted mice, as food became available, AgRP neuron firing dropped, yet remained elevated as compared to firing in sated mice. The rapid drop in spiking activity of AgRP neurons at meal onset may reflect a termination of the drive to find food, while residual, persistent spiking may reflect a sustained drive to consume food. Moreover, nearby neurons inhibited by AgRP neuron photostimulation, likely including satiety-promoting pro-opiomelanocortin (POMC) neurons, demonstrated opposite changes in spiking. Finally, firing of ARC neurons was also rapidly modulated within seconds of individual licks for liquid food. These findings suggest novel roles for antagonistic AgRP and POMC neurons in the regulation of feeding behaviors across multiple timescales.
Slit2 as a β-catenin/Ctnnb1-dependent retrograde signal for presynaptic differentiation
Authors: Wu Haitao , Barik Arnab , Lu Yisheng , Shen Chengyong , Bowman Andrew , Li Lei , Sathyamurthy Anupama , Lin Thiri W , Xiong Wen-Cheng , Mei Lin
Published: July 2015

Neuromuscular junction formation requires proper interaction between motoneurons and muscle cells. β-Catenin (Ctnnb1) in muscle is critical for motoneuron differentiation; however, little is known about the relevant retrograde signal. In this paper, we dissected which functions of muscle Ctnnb1 are critical by an in vivo transgenic approach. We show that Ctnnb1 mutant without the transactivation domain was unable to rescue presynaptic deficits of Ctnnb1 mutation, indicating the involvement of transcription regulation. On the other hand, the cell-adhesion function of Ctnnb1 is dispensable. We screened for proteins that may serve as a Ctnnb1-directed retrograde factor and identified Slit2. Transgenic expression of Slit2 specifically in the muscle was able to diminish presynaptic deficits by Ctnnb1 mutation in mice. Slit2 immobilized on beads was able to induce synaptophysin puncta in axons of spinal cord explants. Together, these observations suggest that Slit2 serves as a factor utilized by muscle Ctnnb1 to direct presynaptic differentiation.
Increase in Utilization of Afterhours Medical Imaging: A Study of Three Canadian Academic Centers
Authors: Chaudhry Shivani , Dhalla Irfan , Lebovic Gerald , Rogalla Patrik , Dowdell Timothy
Published: July 2015

Objectives

The objectives of our study were to assess trends in afterhours medical imaging utilization for emergency department (ED) and inpatient (IP) patient populations from 2006-2013, including analysis by modality and specialty and with adjustment for patient volume.

Methods

For this retrospective study, we reviewed the number of CT, MRI, and ultrasound studies performed for the ED and IP patients during the afterhours time period (5pm - 8am on weekdays and 24 hours on weekends and statutory holidays) from 2006-2013 at three different Canadian academic hospitals. We used the Jonckheere-Terpstra (JT) test to determine statistical significance of imaging and patient volume trends. A regression model was used to examine whether there was an increasing trend over time in the volume of imaging tests per 1000 patients.

Results

For all three sites from 2006-2013 during the afterhours time period: There was a statistically significant increasing trend in total medical imaging volume, which also held true when the volumes were assessed by modality and by specialty. There was a statistically significant increasing trend in ED and IP patient volume. When medical imaging volumes were adjusted for patient volumes, there was a statistically significant increasing trend in imaging being performed per patient.

Conclusion

Afterhours medical imaging volumes demonstrated a statistically significant increasing trend at all three sites from 2006-2013 when assessed by total volume, modality, and specialty. During the same time period and at all three sites, the ED and IP patient volumes also demonstrated a statistically significant increasing trend with more medical imaging, however, being performed per patient.