bluuebunny/crossref_metadata_2025_split huggingface dataset:
Semi‐compliance and illegality in migrant labour markets: an analysis of migrants, employers and the state in the UK
Authors: Ruhs Martin , Anderson Bridget 
Published: October 2009

AbstractThis paper explores the nature and determinants of illegality in migrant labour markets. It conceptualises the various legal ‘spaces of (il)legality’ in the employment of migrants, and explores the perceptions and functions of these spaces from the points of view of migrants, employers, and the state. Our theoretical approach goes beyond the notion that illegality is ‘produced’ by the state, and recognises the agency that some migrants and employers have vis‐à‐vis the state's migration frameworks. Drawing on quantitative and qualitative interviews with East European migrants and employers in the UK, and analysis of the UK government's policies, rhetoric, and enforcement, we find that migrants, employers, and the state all recognise the distinctions between different types of illegality, and their differentiated impacts. In particular, semi‐compliance – which we define as the employment of migrants who are legally resident but working in violation of the employment restrictions attached to their immigration status – is a distinct and contested space of (il)legality that serves important functions. It allows employers and migrants to maximize economic benefits from employment while minimizing the threat of state sanctions for violations of immigration law. Semi‐compliance exists, and is likely to persist, in part because it constitutes an equilibrium, which we show, serves the interests of migrants and employers and in practice is difficult for the state to control. We expect these findings for the UK to be of relevance to many other high‐income countries, which like the UK, consider migrants both as an important source of flexible labour and yet as subjects of immigration control whose employment needs to be closely monitored. Copyright © 2009 John Wiley & Sons, Ltd.
Application of fast‐digitizer card Acqiris DP‐240 in positron lifetime spectroscopy
Authors: Petriska Martin , Zeman Andrej , Slugeň Vladimír , Kršjak Vladimír , Sojak Stanislav , Debarberis Luigi 
Published: October 2009

AbstractBased on the available knowledge base in positron annihilation measurements, new software for digital positron lifetime spectrometry has been designed within the frame of joint activity between STU Bratislava and JRC Petten. The tests of the new positron digital‐life time setup have been carried out. Detectors with BaF2 scintillators and fast‐dynode outputs were chosen for such studies. As the digitiser unit, the card Acqiris DP240 was fully tested. Originally, start and stop timing signals were sampled to digital waveforms separately at a rate of 1 GS/s in 8 bit resolution. However, due to limited quality of collected waveforms which significantly affected post‐processing of data, the joined delayed channel mode with 2 GS/s sampling rate was applied for further studies. The full setup was benchmarked by a series of calibration measurements of two high purity materials, specifically Si and Ni. The inter‐comparison of conventional analogue‐ and digital‐based processing are discussed in detail. Further, the optimisation of main parameters for waveform‐processing are analysed too. Such a new approach in the digital life‐time spectroscopy will help to improve the resolution of existing methodology which might enhance the capabilities of this technique for further applications, especially in materials science. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study of molecular motions in liquid crystal forming compounds using positron lifetime spectroscopy
Authors: Singh K. Chandramani , Yadav R. , Sharma M. , Jain P. C. 
Published: October 2009

AbstractPositron lifetime spectroscopy (PLS) has been used to study molecular motions associated with n ‐p ‐cyano‐p ‐heptylbiphenyl (K21), n ‐p ‐cyano‐p ‐decylbiphenyl (K30), n ‐p ‐cyano‐p ‐hexyloxybiphenyl (M18), and n ‐p ‐ethoxybenzylidene‐p ‐butylaniline (EBBA). In each of these liquid crystal forming compounds, temperature dependent positron lifetime measurements have been performed during the heating cycle of samples prepared by either quenching or slow cooling from the respective liquid crystalline phase of the compounds. Unlike the slow‐cooled sample, the quenched sample shows various characteristic peaks in the ortho‐positronium (o‐Ps) pick‐off lifetime measured over a wide range of temperature, before the system undergoes a glass transition. These peaks have been attributed to various intra‐ and inter‐molecular motions associated with these compounds. A comparative study of the four compounds is presented in this paper. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Positron annihilation studies on D9 steel – Effect of Ti concentration
Authors: Arunkumar J. , Abhaya S. , Rajaraman R. , Amarendra G. , Nair K. G. M. , Sundar C. S. , Raj Baldev 
Published: October 2009

AbstractEffect of titanium concentration in the D9 composition on the defect recovery has been investigated using positron lifetime measurements. As‐received and creep‐tested samples of 20% cold‐worked D9 having different weight percent of titanium namely, 0.18, 0.23, 0.25 and 0.36 have been investigated.As‐received Ti variants of D9 have also been isothermally annealed at 973 K and positron lifetime studies have been carried out to confirm the evolution of TiC precipitates during the initial annealing stages. These results are discussed in the light of TiC precipitation with our earlier work on isochronal annealing of cold‐worked D9. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Emission of positronium negative ions from Cs deposited W(100) and polycrystalline Fe surfaces
Authors: Nagashima Yasuyuki , Hakodate Toshihide , Miyamoto Ayaka , Michishio Koji , Terabe Hiroki 
Published: October 2009

AbstractEfficient emission of positronium negative ions from Cs deposited W(100) surface has been observed. The emission efficiency measured over a time interval of 3000 s immediately after the deposition was found to be 1.25% for the target with a 2.2 × 1014 atoms/cm2 Cs layer. The emission from Cs deposited polycrystalline Fe surface has also been observed. The upper limit of the binding energy of the ion has been estimated experimentally. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A comparative study of transformation of micellar structures in CTAB and TTAB binary systems using Positron Lifetime Spectroscopy
Authors: Yadav R. , Singh K. Chandramani , Choudhary S. R. , Jain P. C. 
Published: October 2009

AbstractThe micellar structures of cetyl‐tri‐methyl ammonium bromide (CTAB) and its homologues have been investigated employing several conventional techniques. However, due to lack of sensitivity inherent in these techniques and the perturbation introduced by the probe, the detailed structures of the aggregates in the so‐called single phase regions of these systems are far from being fully understood. Positron has been found to be a useful non‐destructive probe for investigating micellar structures in surfactant systems [1‐3] The present study is an effort to get a better insight into the micellar structures and their transformations in CTAB and TTAB aqueous binary systems Positron lifetime spectroscopy has been employed to study these systems covering a wide range of surfactant concentrations. A comparative study of the results obtained for the two surfactant systems have been discussed in this paper. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Coincident Doppler‐broadening spectroscopy of Si, amorphous SiO2, and α‐quartz using mono‐energetic positrons
Authors: Hugenschmidt C. , Pikart P. , Schreckenbach K. 
Published: October 2009

AbstractExperiments on oxides and on silicon by coincident Doppler broadening spectroscopy (CDBS) using the mono‐ener‐ getic positron beam at the neutron induced positron source NEPOMUC are presented. Doppler‐broadening spectroscopy (DBS) as a function of positron implantation energy is applied in order to compare the crystalline quartz and single crystalline Si with amorphous quartz. More detailed information about the chemical surrounding at the positron annihilation site is gained by CDBS‐experiments. For this reason, the CDBS‐measurements are performed to detect the signature of positrons annihilating with electrons from oxygen. The comparison of the CDB spectra obtained for the quartz samples and ice with that of the Si surface clearly shows that the surface of single‐crystalline Si is terminated with oxygen. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ageing processes in Al‐Cu‐Mg alloys with different Cu/Mg ratios
Authors: Macchi C. , Somoza A. , Ferragut R. , Dupasquier A. , Polmear I. J. 
Published: October 2009

AbstractThree age‐hardenable Al‐Cu‐Mg alloys with different Cu/Mg ratios were studied by means of positron annihilation lifetime spectroscopy and Vickers hardness as a function of the artificial ageing time at 175 °C. Complementary information on the decomposition sequence was obtained by means of differential scanning calorimetry. The results are discussed in terms of the different structures that are formed during the precipitation sequence of the supersaturated solid solution. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Defect characterization of heavily As and P doped Si epilayers
Authors: Kilpeläinen Simo , Kuitunen Katja , Slotte Jonatan , Tuomisto Filip , Borot Gaël , Rubaldo Laurent , Clément L. , Pantel Roland , Dutartre Didier 
Published: October 2009

AbstractIn this paper, positron annihilation spectroscopy in Doppler broadening mode is used to show that inactive As and P atoms causing tensile strain in heavily doped Si epilayers are linked to vacancy‐type defects. In the case of As doping, a clear increase in the average number of impurity atoms per monovacancy is observed as As concentration is increased. The effect of high temperature spike annealing on heavily As doped Si epilayers is also investigated and the vacancy‐impurity complexes are shown to be very stable in most samples. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Positron lifetime studies of CaSO4: Dy thermoluminescence phosphors
Authors: Annalakshmi O. , Chirayath Varghese Anto , Babu S. Hari , Jose M. T. , Amarendra G. 
Published: October 2009

AbstractPositron lifetime studies have been carried out on CaSO4:Dy phosphors with and without Teflon binder. The effect of Co‐60 gamma irradiation exposure in these samples has been investigated. Unexposed CaSO4:Dy embedded Teflon discs exhibited four lifetime components viz., 228, 755, 3865 and 77 ps with intensities of 62%, 18%, 14% and 6%, respectively. Since Teflon is used as a binder in these phosphors, the long lived components are understood to arise from this. Upon radiation exposure there is a clear change in these resolved lifetime components. To understand the variation of these lifetime components better, positron lifetime studies was carried out on pure CaSO4:Dy powder (without Teflon) as well as pure Teflon discs exposed to varying radiation doses. The variation of positron lifetime parameters of CaSO4:Dy powder showed systematics, ascribable to SO–4 ion formation due to γ‐ray exposure. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PALS study of point defects in Fe‐Al and Fe‐Al‐Cr alloys
Authors: Kansy Jerzy , Hanc Aneta , Pająk Lucjan , Giebel Dawid 
Published: October 2009

AbstractThe concentrations of quenched‐in vacancies in Fe‐Al and Fe‐Al‐Cr systems after their various thermal treatment were studied by positron lifetime spectroscopy. The experimental data were analyzed with the 2‐state trapping model directly implemented to the code of the computer program (LT‐9 2). The number of quenched‐in vacancies strongly depends on the rate of quenching. For fast quenched samples the atomic concentration is of order of 10–4 and it radically falls after annealing at 500 °C for 0.5 h. A comparison of Fe28Al and Fe28Al5Cr samples, after analogical heat treatment, showed that chromium addition caused a systematical decrease of the resistant vacancy concentrations. In the samples that were slowly cooled after quenching at 1000 °C the positrons are trapped at precipitates of minor alloying elements. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of growth conditions on vacancy defects in MOVPE grown AlN thin layers
Authors: Mäki J.‐M. , Tuomisto F. , Bastek B. , Bertam F. , Christen J. , Dadgar A. , Krost A. 
Published: October 2009

AbstractIn this paper we report preliminary results on the vacancy type defects in thin film aluminum nitride (AlN). We have performed positron beam measurements in 7 thin film AlN layers on silicon grown by metal‐organic vapour phase epitaxy (MOVPE) in varying conditions. The growth temperature, V/III supply ratio of the precursor molecules and the layer thicknesses have been varied. All the samples grown had a high concentration of vacancy type defects, hence it seems that the structural defects and possible strain due to lattice mismatch betweenmaterials has a major role in the vacancy formation. Additionally, the growth conditions were found to have an effect on the vacancy content of the samples. Increasing growth temperatures and decreasing layer thickness seemed to increase the vacancy concentration whereas V/III ratio of the growth gases did not seem to have an effect (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Positron annihilation studies on chalcone chromophore doped PVA
Authors: Bhajantri R. F. , Ravindrachary V. , Harisha A. , Ismayil  , Ranganathaiah C. 
Published: October 2009

AbstractA novel organic non‐linear optical material 1‐(4‐methylphenyl)‐3‐(4‐ N, N dimethyl amino phenyl)‐2‐propen‐1‐one (MPDMAPP) chalcone chromophore has been synthesized by standard method. Pure and MPDMAPP doped Poly(vinyl alcohol) films are prepared using solution casting method and characterized using UV‐Visible absorption and Positron Annihilation Lifetime Spectroscopy. The optical spectroscopic study shows three absorption bands, 196‐202 nm assigned to localized n →π * transitions, 205‐320 nm to n →π * inter‐band and 385‐428 nm assigned to π →π * transition and arises due to the charge transfer complex. Using observed UV‐Vis spectra, three optical energy gaps, Eg1 (4.96–4.25 eV), Eg2 (3.47–3.32 eV) and Eg3 (2.33–2.24 eV) have been estimated. The observed change in Eg upon doping is understood based on the formation of charge transfer complex arising from the –HC=CH– structure present in the composite and due to the interactions of dopant and OH group of PVA. The PALS results shows that the o‐Ps lifetime decreases continuously as doping concentration increases and I3 initially increases (from 18.82% to 20.95%) from 0 wt% to 0.05 wt% and then decreases gradually up to 16.76% for higher dopant concentrations with decrease in optical band gaps. The variation of positron data with Eg is understood by correlating the probability of Ps formation with the complex. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
o‐Ps lifetime, free volume and Doppler broadening spectroscopy (DBS) studies of 50 MeV Li3+ ion irradiated polystyrene
Authors: Ali S. Asad , Kumar Rajesh , Nambissan P. M. G. , Singh Fouran , Prasad Rajendra 
Published: October 2009

AbstractSwift Heavy Ion(SHI) irradiation of polymeric materials results in the change of their free volume properties. Polystyrene films (1 mm) were irradiated with Li3+ ions of energy 50 MeV to the fluences from 5x1010 to 3.5x1013 ions/cm2.The effect of ion irradiation on free volume has been characterized by PALS and DBS. From o‐Ps pick off annihilation lifetime τ3, mean free volume hole radius, average free volume of micro voids and fractional free volume are computed. Free volume values change slowly with ion fluence with a decrease at the highest fluence of 3.5x1013 ions/cm2. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Defect evolution in steels: Insights from positron studies
Authors: Rajaraman R. , Amarendra G. , Sundar C. S. 
Published: October 2009

AbstractPositron annihilation studies on austentic and ferritic/martensitic and oxide‐dispersion steels are highlighted so as to emphasize the sensitivity of the technique to defect annealing as well as precipitates. The results obtained on austenitic D9 steels are discussed with a view to emphasize the role of small TiC precipitates in the matrix, which play a critical role in void‐swelling behaviour. Further, the role of Ti/C ratio as well as minor alloying elements on swelling behaviour is discussed. The current focus of research is on the use of nanoclusters in ODS alloys towards the suppression of void formation under irradiation. Recent results on the investigation on nano Yttria particles in Fe – model oxide dispersion ferritic steel, are presented with supporting ab‐initio lifetime calculations. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A conservative Fourier‐finite‐element method for solving partial differential equations on the whole sphere
Authors: Dubos T. 
Published: October 2009

AbstractSolving transport equations on the whole sphere using an explicit time stepping and an Eulerian formulation on a latitude–longitude grid is relatively straightforward but suffers from the pole problem: due to the increased zonal resolution near the pole, numerical stability requires unacceptably small time steps. Commonly used workarounds such as near‐pole zonal filters affect the qualitative properties of the numerical method. Rigorous solutions based on spherical harmonics have a high computational cost.The numerical method we propose to avoid this problem is based on a Galerkin formulation in a subspace of a Fourier‐finite‐element spatial discretization. The functional space we construct provides quasi‐uniform resolution and high‐order accuracy, while the Galerkin formalism guarantees the conservation of linear and quadratic invariants. For N2 degrees of freedom, the computational cost is 𝒪(N2logN), dominated by the zonal Fourier transforms. This is more than with a finite‐difference or finite‐volume method, which costs 𝒪(N2), and less than with a spherical harmonics method, which costs 𝒪(N3). Differential operators with latitude‐dependent coefficients are inverted at a cost of 𝒪(N2).We present experimental results and standard benchmarks demonstrating the accuracy, stability and efficiency of the method applied to the advection of a scalar field by a prescribed velocity field and to the incompressible rotating Navier–Stokes equations. The steps required to extend the method towards compressible flows and the Saint‐Venant equations are described. Copyright © 2009 Royal Meteorological Society
Assimilation of SEVIRI infrared radiances with HIRLAM 4D‐Var
Authors: Stengel M. , Undén P. , Lindskog M. , Dahlgren P. , Gustafsson N. , Bennartz R. 
Published: October 2009

AbstractFour‐dimensional variational data assimilation (4D‐Var) systems are ideally suited to obtain the best possible initial model state by utilizing information about the dynamical evolution of the atmospheric state from observations, such as satellite measurements, distributed over a certain period of time. In recent years, 4D‐Var systems have been developed for several global and limited‐area models. At the same time, spatially and temporally highly resolved satellite observations, as for example performed by the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) on board the Meteosat Second Generation satellites, have become available.Here we demonstrate the benefit of a regional NWP model's analyses and forecasts gained by the assimilation of those radiances. The 4D‐Var system of the HIgh Resolution Limited Area Model (HIRLAM) has been adjusted to utilize three of SEVIRI's infrared channels (located around 6.2 µm, 7.3 µm, and 13.4 µm, respectively) under clear‐sky and low‐level cloud conditions. Extended assimilation and forecast experiments show that the main direct impact of assimilated SEVIRI radiances on the atmospheric analysis were additional tropospheric humidity and wind increments. Forecast verification reveals a positive impact for almost all upper‐air variables throughout the troposphere. Largest improvements are found for humidity and geopotential height in the middle troposphere. The observations in regions of low‐level clouds provide especially beneficial information to the NWP system, which highlights the importance of satellite observations in cloudy areas for further improvements in the accuracy of weather forecasts. Copyright © 2009 Royal Meteorological Society
Isotope pattern vector based tandem mass spectral data calibration for improved peptide and protein identification
Authors: Zhang Jingfen , Xu Dong , Gao Wen , Lin Guohui , He Simin 
Published: October 2009

AbstractTandem mass spectra contain noisy peaks which make peak picking for peptide identification difficult. Moreover, all spectral peaks can be shifted due to systematic measurement errors. In this paper, a novel use of anisotope pattern vector(IPV) is proposed for denoising and systematic measurement error prediction. By matching the experimental IPVs with the theoretical IPVs of candidate fragment ions, true ionic peaks can be identified. Furthermore, these identified experimental IPVs and their corresponding theoretical IPVs are used in an optimization process to predict the systematic measurement error associated with the target spectrum. In return, the subsequent spectral data calibration based on the predicted systematic measurement error enhances the data quality. We show that such an integrated denoising and calibration process leads to significantly improved peptide and protein identification. Different from the commonly employed chemical calibration methods, our IPV‐based method is a purely computational method for individual spectra analysis and globally optimizes the use of spectral data. Copyright © 2009 John Wiley & Sons, Ltd.