WorldWideScience

Sample records for subgrain boundary migration

  1. Influence of subgrain boundaries on coarsening of grain structures

    Science.gov (United States)

    Zöllner, D.; Skrotzki, W.

    2017-05-01

    In the present work, the influence of subgrain boundaries on the coarsening kinetics of individual grains embedded in an average environment as well as within a grain structure is investigated. It is found that a specific introduction of subgrain boundaries not only influences the speed with which grains shrink or grow, but in contrast to the von Neumann-Mullins-law, a distinct manipulation of the location of the subgrain boundaries allows even grains with few edges to grow, while grains with many edges shrink. During these circumstances one fact stays the same: the area of the individual grains is a linear function of annealing time as long as the environment does not change.

  2. Subgrain boundaries in Antarctic ice quantified by X-ray Laue diffraction

    OpenAIRE

    Weikusat, Ilka; Miyamoto,Atsushi; Faria, Sergio H.; Kipfstuhl, Sepp; Azuma, Nobuhiko; Hondoh,Takeo

    2011-01-01

    Ice in polar ice sheets undergoes deformation during its flow towards the coast. Deformation and recrystallization microstructures such as subgrain boundaries can be observed and recorded using high-resolution light microscopy of sublimation-edged sample surfaces (microstructure mapping). Subgrain boundaries observed by microstructure mapping reveal characteristic shapes and arrangements. As these arrangements are related to the basal plane orientation, full crystallographic or...

  3. EBSD analysis of subgrain boundaries and dislocation slip systems in Antarctic and Greenland ice

    Science.gov (United States)

    Weikusat, Ilka; Kuiper, Ernst-Jan N.; Pennock, Gill M.; Kipfstuhl, Sepp; Drury, Martyn R.

    2017-09-01

    Ice has a very high plastic anisotropy with easy dislocation glide on basal planes, while glide on non-basal planes is much harder. Basal glide involves dislocations with the Burgers vector b = 〈a〉, while glide on non-basal planes can involve dislocations with b = 〈a〉, b = [c], and b = 〈c + a〉. During the natural ductile flow of polar ice sheets, most of the deformation is expected to occur by basal slip accommodated by other processes, including non-basal slip and grain boundary processes. However, the importance of different accommodating processes is controversial. The recent application of micro-diffraction analysis methods to ice, such as X-ray Laue diffraction and electron backscattered diffraction (EBSD), has demonstrated that subgrain boundaries indicative of non-basal slip are present in naturally deformed ice, although so far the available data sets are limited. In this study we present an analysis of a large number of subgrain boundaries in ice core samples from one depth level from two deep ice cores from Antarctica (EPICA-DML deep ice core at 656 m of depth) and Greenland (NEEM deep ice core at 719 m of depth). EBSD provides information for the characterization of subgrain boundary types and on the dislocations that are likely to be present along the boundary. EBSD analyses, in combination with light microscopy measurements, are presented and interpreted in terms of the dislocation slip systems. The most common subgrain boundaries are indicative of basal 〈a〉 slip with an almost equal occurrence of subgrain boundaries indicative of prism [c] or 〈c + a〉 slip on prism and/or pyramidal planes. A few subgrain boundaries are indicative of prism 〈a〉 slip or slip of 〈a〉 screw dislocations on the basal plane. In addition to these classical polygonization processes that involve the recovery of dislocations into boundaries, alternative mechanisms are discussed for the formation of subgrain boundaries that are not related to the

  4. EBSD analysis of subgrain boundaries and dislocation slip systems in Antarctic and Greenland ice

    Directory of Open Access Journals (Sweden)

    I. Weikusat

    2017-09-01

    Full Text Available Ice has a very high plastic anisotropy with easy dislocation glide on basal planes, while glide on non-basal planes is much harder. Basal glide involves dislocations with the Burgers vector b = 〈a〉, while glide on non-basal planes can involve dislocations with b = 〈a〉, b = [c], and b = 〈c + a〉. During the natural ductile flow of polar ice sheets, most of the deformation is expected to occur by basal slip accommodated by other processes, including non-basal slip and grain boundary processes. However, the importance of different accommodating processes is controversial. The recent application of micro-diffraction analysis methods to ice, such as X-ray Laue diffraction and electron backscattered diffraction (EBSD, has demonstrated that subgrain boundaries indicative of non-basal slip are present in naturally deformed ice, although so far the available data sets are limited. In this study we present an analysis of a large number of subgrain boundaries in ice core samples from one depth level from two deep ice cores from Antarctica (EPICA-DML deep ice core at 656 m of depth and Greenland (NEEM deep ice core at 719 m of depth. EBSD provides information for the characterization of subgrain boundary types and on the dislocations that are likely to be present along the boundary. EBSD analyses, in combination with light microscopy measurements, are presented and interpreted in terms of the dislocation slip systems. The most common subgrain boundaries are indicative of basal 〈a〉 slip with an almost equal occurrence of subgrain boundaries indicative of prism [c] or 〈c + a〉 slip on prism and/or pyramidal planes. A few subgrain boundaries are indicative of prism 〈a〉 slip or slip of 〈a〉 screw dislocations on the basal plane. In addition to these classical polygonization processes that involve the recovery of dislocations into boundaries, alternative mechanisms are discussed for the formation of subgrain

  5. Microscopic Distributions of Defect Luminescence From Subgrain Boundaries in Multicrystalline Silicon Wafers

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Hieu T.; Jensen, Mallory A.; Li, Li; Samundsett, Christian; Sio, Hang C.; Lai, Barry; Buonassisi, Tonio; Macdonald, Daniel

    2017-05-01

    We investigate the microscopic distributions of sub-band-gap luminescence emission (the so-called D-lines D1/D2/D3/D4) and the band-to-band luminescence intensity, near recombination-active sub-grain boundaries in multicrystalline silicon wafers for solar cells. We find that the sub-band-gap luminescence from decorating defects/impurities (D1/D2) and from intrinsic dislocations (D3/D4) have distinctly different spatial distributions, and are asymmetric across the sub-grain boundaries. The presence of D1/D2 is correlated with a strong reduction in the band-to-band luminescence, indicating a higher recombination activity. In contrast, D3/D4 emissions are not strongly correlated with the band-to-band intensity. Based on spatially-resolved, synchrotron-based micro-X-ray fluorescence measurements of metal impurities, we confirm that high densities of metal impurities are present at locations with strong D1/D2 emission but low D3/D4 emission. Finally, we show that the observed asymmetry of the sub-band-gap luminescence across the sub-grain boundaries is due to their inclination below the wafer surface. Based on the luminescence asymmetries, the sub-grain boundaries are shown to share a common inclination locally, rather than be orientated randomly.

  6. Segmentation of 3D EBSD data for subgrain boundary identification and feature characterization

    Energy Technology Data Exchange (ETDEWEB)

    Loeb, Andrew, E-mail: ael89@cornell.edu [Department of Engineering, Harvey Mudd College, 301 Platt Blvd, Claremont, CA 91711 (United States); Ferry, Michael [School of Materials Science and Engineering, The University of New South Wales, NSW 2052 (Australia); Bassman, Lori [Department of Engineering, Harvey Mudd College, 301 Platt Blvd, Claremont, CA 91711 (United States)

    2016-02-15

    Subgrain structures formed during plastic deformation of metals can be observed by electron backscatter diffraction (EBSD) but are challenging to identify automatically. We have adapted a 2D image segmentation technique, fast multiscale clustering (FMC), to 3D EBSD data using a novel variance function to accommodate quaternion data. This adaptation, which has been incorporated into the free open source texture analysis software package MTEX, is capable of segmenting based on subtle and gradual variation as well as on sharp boundaries within the data. FMC has been further modified to group the resulting closed 3D segment boundaries into distinct coherent surfaces based on local normals of a triangulated surface. We demonstrate the excellent capabilities of this technique with application to 3D EBSD data sets generated from cold rolled aluminum containing well-defined microbands, cold rolled and partly recrystallized extra low carbon steel microstructure containing three magnitudes of boundary misorientations, and channel-die plane strain compressed Goss-oriented nickel crystal containing microbands with very subtle changes in orientation. - Highlights: • Novel fast multiscale clustering (FMC) implementation segments 3D EBSD data. • FMC segments based on subtle or gradual variation as well as sharp boundaries. • A modification of FMC segments surfaces of microstructural feature volumes. • Method is incorporated in free open source texture analysis software package MTEX. • Several data sets demonstrate FMC and its advantages over Kuwahara filtering.

  7. Subgrain boundary analyses in deformed orthopyroxene by TEM/STEM with EBSD-FIB sample preparation technique

    Science.gov (United States)

    Kogure, Toshihiro; Raimbourg, Hugues; Kumamoto, Akihito; Fujii, Eiko; Ikuhara, Yuichi

    2014-12-01

    High-resolution structure analyses using electron beam techniques have been performed for the investigation of subgrain boundaries (SGBs) in deformed orthopyroxene (Opx) in mylonite from Hidaka Metamorphic Belt, Hokkaido, Japan, to understand ductile deformation mechanism of silicate minerals in shear zones. Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) analysis of Opx porphyroclasts in the mylonitic rock indicated that the crystal orientation inside the Opx crystals gradually changes by rotation about the b-axis by SGBs and crystal folding. In order to observe the SGBs along the b-axis by transmission electron microscopy (TEM) or scanning TEM (STEM), the following sample preparation protocol was adopted. First, petrographic thin sections were slightly etched with hydrofluoric acid to identify SGBs in SEM. The Opx crystals whose b-axes were oriented close to the normal of the surface were identified by EBSD, and the areas containing SGBs were picked and thinned for (S) TEM analysis with a focused ion beam instrument with micro-sampling system. High-resolution TEM imaging of the SGBs in Opx revealed various boundary structures from a periodic array of dissociated (100) [001] edge dislocations to partially or completely incoherent crystals, depending on the misorientation angle. Atomic-resolution STEM imaging clearly confirmed the formation of clinopyroxene (Cpx) structure between the dissociated partial dislocations. Moreover, X-ray microanalysis in STEM revealed that the Cpx contains a considerable amount of calcium replacing iron. Such chemical inhomogeneity may limit glide motion of the dislocation and eventually the plastic deformation of the Opx porphyroclasts at a low temperature. Chemical profiles across the high-angle incoherent SGB also showed an enrichment of the latter in calcium at the boundary, suggesting that SGBs are an efficient diffusion pathway of calcium out of host Opx grain during cooling.

  8. EBSD analysis of heterogeneous microstructures in experimentally deformed calcite: development of core and mantle subgrains, grain boundary bulges and recrystallised grains. Geologica Ultraiectina (289)

    NARCIS (Netherlands)

    Valcke, S.L.A.|info:eu-repo/dai/nl/304833452

    2008-01-01

    Geodynamic processes such as subduction and rifting are mainly controlled by high temperature plastic deformation of rocks. It is known that elements of the microstructure in plastically deformed rocks, such as subgrains and recrystallised grains, are potentially useful as indicators of past

  9. Boundary migration during recrystallization: experimental observations

    DEFF Research Database (Denmark)

    Zhang, Yubin; Juul Jensen, Dorte

    2015-01-01

    materials. This type of analysis has largely been based on the assumption that all or groups of recrystallizing grains grow in the same uniform manner, therefore the results represent average growth behaviors on a macro scale. Recently, significant efforts have been made to quantify the boundary migration......Quantitative analysis of boundary migration during recrystallization is a key task to understand the recrystallization process and to improve recrystallization models. In the last 25-30 years, quantification of boundary migration has mostly been conducted in term of average growth rates in many...... during recrystallization on local grain scales, using different advanced experimental characterization and computer simulation techniques. This paper aims at summarizing these recent achievements with focus on the potentials of the various advanced experimental characterization techniques. Suggestions...

  10. Local boundary migration during recrystallization in pure aluminium

    DEFF Research Database (Denmark)

    Zhang, Yubin; Godfrey, Andrew; Juul Jensen, Dorte

    2011-01-01

    Boundary migration during recrystallization has been followed by an ex situ electron channelling contrast technique, and protrusions/retrusions formed locally on recrystallization boundaries have been quantified. The results show that the motion of recrystallization boundaries is much more comple...

  11. Cavitation at migrating boundaries during high temperature fatigue

    Energy Technology Data Exchange (ETDEWEB)

    Raman, V.

    1987-06-01

    There is growing interest in the role of migrating boundaries during high temperature deformation. One area of current interest is the manner in which grain boundary migration can influence deformation and fracture at elevated temperatures. Much of the detailed treatments of intergranular cracking and cavitation during creep deformation have centered on effects occurring at stationary grain boundaries. The conventional idea represented in numerous publications is that grain boundary sliding plays an important role in intergranular fracture at elevated temperatures. The large stress concentrations developed at irregularities on grain boundaries are frequently cited as the principal reason for the easy generation of cracks and cavities. This article concludes that high temperature fatigue can cause significant migration and sliding in Al-3% Mg and Pb-2% Sn solid solution alloys, and that microcavitation and cracking takes place at the migrating boundaries in specimens tested at large strain amplitudes and low test frequencies. Cavities may be isolated within grains due to boundary migration.

  12. Study on Subgrain Rotation Behavior at Different Interfaces of a Solder Joint During Thermal Shock

    Science.gov (United States)

    Han, Jing; Tan, Shihai; Guo, Fu

    2016-12-01

    In order to investigate subgrain rotation behavior in the recrystallized region of lead-free solder joints, a ball grid array (BGA) specimen with a cross-sectioned edge row was thermally shocked. Electron backscattered diffraction (EBSD) was used to obtain the microstructure and orientations of Sn grains or subgrains in as-reflowed and thermally shocked conditions. Orientation imaging microscopy (OIM) showed that several subgrains were formed at the tilted twin grain boundaries, near the chip side and near the printed circuit board (PCB) side after 200 thermal shocks due to a highly mismatched coefficient of thermal expansion (CTE) of twin grains. Also, subgrains formed at the chip side and PCB side in the solder joint were selected to research the grain rotation behavior in lead-free solder joints. The analysis of subgrain rotation also indicated that the rotation behavior of subgrains was different between the chip side and PCB side. It was closely related with the large different crystal orientations between the chip side and PCB side. Furthermore, electron backscattered patterns (EBSPs) at several parts of the joint were not obtained after 300 thermal shocks due to the serious deformation caused by mismatched CTE during thermal shock. But 4 subgrains were selected and compared with that of the initial state and 200-thermal shock conditions. The results showed that the subgrains at the chip side were also rotated around the Sn [101] and [001] axes and the subgrains at the PCB side were also rotated around the Sn [100] axis, which indicated a continuous process of subgrain rotation.

  13. Simulations of boundary migration during recrystallization using molecular dynamics

    DEFF Research Database (Denmark)

    Godiksen, Rasmus Brauner; Trautt, Z.T.; Upmanyu, M.

    2007-01-01

    process is not uniform as assumed in many recrystallization models, but that the grain boundaries migrate in an irregular fashion and exhibit a strong dependence on the local presence of dislocations, which can distort the local migration process significantly. (c) 2007 Acta Materialia Inc. Published...

  14. In-Situ Investigation of Local Boundary Migration During Recrystallization

    DEFF Research Database (Denmark)

    Zhang, Yubin; Godfrey, Andy; Juul Jensen, Dorte

    2014-01-01

    A combination of electron channeling contrast (ECC) and electron backscatter diffraction pattern (EBSP) techniques has been used to follow in situ the migration during annealing at 323 K (50 A degrees C) of a recrystallizing boundary through the deformed matrix of high-purity aluminum rolled to 8...

  15. The Interaction between Particles and Low Angle Boundaries during Recovering of Aluminium-Alumina Alloys

    DEFF Research Database (Denmark)

    Jones, A.R.; Hansen, Niels

    1981-01-01

    Certain quantitative and qualitative aspects both of subgrain growth and of the interaction between particles and low angle grain boundaries during recovery have been investigated in two aluminium alloys containing low volume fractions of small alumina particles. Quantitative data have been...... boundaries during recovery involves effects in addition to those of simple Zener pinning of migrating boundaries. For the current alloys it is found that a determination of the limits to normal subgrain growth in terms of a modified Zener analysis produces an underestimate of the true extent of particle...

  16. RETRACTED ARTICLE: The Effect of Solute Atoms on Grain Boundary Migration: A Solute Pinning Approach

    Science.gov (United States)

    Hersent, Emmanuel; Marthinsen, Knut; Nes, Erik

    2012-12-01

    The effect of solute atoms on grain boundary migration has been modeled on the basis of the idea that solute atoms will locally perturb the collective rearrangements of solvent atoms associated with boundary migration. The consequence of such perturbations is the cusping of the boundary and corresponding stress concentrations on the solute atoms which will promote thermal activation of these atoms out of the boundary. This thermal activation is considered to be the rate-controlling mechanism in boundary migration. It is demonstrated that the present statistical approach is capable of explaining, in phenomenological terms, the known effects of solute atoms on boundary migration. The experimental results on the effect of copper on boundary migration in aluminum, due to Gordon and Vandermeer, have been well accounted for.

  17. The Role of Stress-Effected Subgrain Size Distribution in Anelastic Recovery: An Experimental Study on Polycrystalline Ice-Ih

    Science.gov (United States)

    Caswell, T. E.; Goldsby, D. L.; Cooper, R. F.; Prior, D. J.

    2013-12-01

    Anelasticity, or time-dependent and recoverable strain, is the source of attenuation at seismic and sub-seismic frequencies, yet the processes governing anelastic recovery are poorly resolved. Numerous experimental studies [e.g., 1-3] have demonstrated that anelasticity occurs via diffusion-effected relaxation along grain boundaries, which leads to a significant grain size sensitivity. Similar studies, however, conducted on deformed single crystals [e.g. 4], coarse-grained metals deforming in dislocation creep [e.g., 5] and polycrystalline ice deforming via a dislocation-accommodated mechanism [6] demonstrate the same frequency dependence, consistent with the grain boundary mechanism, but with no sensitivity to grain size. We postulate that it is the deformation-effected distribution of subgrains, which possesses unique diffusive properties relative to a defect-free lattice, that dominates attenuation in these situations. To test this idea we are conducting creep and stress-drop experiments on polycrystalline ice-Ih with concurrent high-resolution microstructural analysis conducted via Electron Backscatter Diffraction (EBSD) [7] to characterize the relationship between subgrain size distribution and diffusion-effected anelasticity. Our experiments establish the subgrain size distribution in steady-state creep of fine-grained ice-1h at compressional stresses between 0.1-4 MPa, which for the grain sizes and temperatures of our experiments places the rheology squarely within the regime of grain boundary sliding that is accommodated by basal dislocation slip [8]. We then explore the dynamics of the established microstructure, which includes subgrain formation [cf. 9], via stress-drop experiments [e.g. 10]. Experiments of this type allow the characterization of microstructural 'hardness,' i.e., the viscosity of the polycrystalline solid as effected by finite strain, from which we can discern the diffusive kinetics of subgrain boundaries [11, 12]. We are currently

  18. A phase-field simulation study of irregular grain boundary migration during recrystallization

    DEFF Research Database (Denmark)

    Moelans, N.; Zhang, Yubin; Godfrey, A.

    2015-01-01

    We present simulation results based on a phase-field model that describes the migration of recrystallization boundaries into spatially varying deformation energy fields. Energy fields with 2-dimensional variations representing 2 sets of dislocation boundaries lying at equal, but opposite, angles...

  19. Boundary migration in a 3D deformed microstructure inside an opaque sample

    DEFF Research Database (Denmark)

    Zhang, Yubin; Budai, J D; Tischler, Jonathan Z.

    2017-01-01

    How boundaries surrounding recrystallization grains migrate through the 3D network of dislocation boundaries in deformed crystalline materials is unknown and critical for the resulting recrystallized crystalline materials. Using X-ray Laue diffraction microscopy, we show for the first time the mi...

  20. Migrations across International Boundaries and the Nationality and ...

    African Journals Online (AJOL)

    ... its instability in time and the limited means for its policing from colonial times to date and the disregard of the borders by the vivisected but related ethnic groups, have overtime generated and maintained a variable fluidity of migrations across it by citizens of both countries to and fro the other. Currently, Nigerian migrants to ...

  1. The Mechanisms of Grain Boundaries - Slip Transmission, Migration, and Sliding

    Energy Technology Data Exchange (ETDEWEB)

    Briant, Clyde L.

    2005-03-02

    During the last eight years, we have worked on the general problems associated with grain boundaries in metals with DOE support. This final report summarizes the work that has been performed. At the start of this work, we took a much more atomistic approach to grain boundaries. However, as we performed this research it became clear that such approaches had the drawbacks listed above, and that we were not proceeding toward the more general understanding of grain boundaries that we have hoped to achieve. We then moved toward more macroscopic based experiments that we could use to understand the structure and motion of grain boundaries. From these we were able to begin deducing some of the most important results of this work and to provide information that can be used by others to understand the role of grain boundaries in materials. We thus present this report in a topical way and provide the experimental and theoretical underpinning that is needed at each point as we go forward.

  2. A Molecular Dynamics Approach to Grain Boundary Structure and Migration

    DEFF Research Database (Denmark)

    Cotterill, R. M. J.; Leffers, Torben; Lilholt, Hans

    1974-01-01

    It has been demonstrated that grain boundary formation from the melt can be simulated by the molecular dynamics method. The space between two mutually-misoriented crystal slabs was filled with atoms in a random manner and this liquid was then cooled until crystallization occurred. The general...

  3. Phase-field simulation study of the migration of recrystallization boundaries

    DEFF Research Database (Denmark)

    Moelans, Nele; Godfrey, Andy; Zhang, Yubin

    2013-01-01

    amplitudes, however, the velocity scales with the maximum of the deformation energy density along the variation, resulting in a considerably larger velocity than that obtained from standard recrystallization models. The shape of the migrating grain boundary greatly depends on the local characteristics......We present simulation results based on a phase-field model that describes the local migration of recrystallization boundaries into varying deformation energy fields. An important finding from the simulations is that the overall migration rate of the recrystallization front can be considerably...... affected by the variations in the deformed microstructure, resulting in two regimes. For variations with low amplitude, the overall boundary velocity scales with the average stored deformation energy density. This behavior is in agreement with generally accepted theories of recrystallization. For larger...

  4. Interacting effects of strengthening and twin boundary migration in nanotwinned materials

    Science.gov (United States)

    Joshi, Kartikey; Joshi, Shailendra P.

    Twin boundaries play a governing role in the mechanical characteristics of nanotwinned materials. They act as yield strengthening agents by offering resistance to non-coplanar dislocation slip. Twin boundary migration may cause yield softening while also enhancing the strain hardening response. In this work, we investigate the interaction between strengthening and twin boundary migration mechanisms by developing a length-scale dependent crystal plasticity framework for face-centered-cubic nanotwinned materials. The crystal plasticity model incorporates strengthening mechanisms due to dislocation pile-up via slip and slip-rate gradients and twin boundary migration via source-based twin partial nucleation and lattice dislocation-twin boundary interaction. The coupled effect of the load orientation and initial twin size on the speed of twin boundary is discussed and an expression for the same is proposed in terms of relevant material parameters. The efficacy of finite element simulations and the analytical expression in predicting evolution of nanotwinned microstructures comprising size and spatial distributions of twins is demonstrated.

  5. Shear-coupled grain-boundary migration dependence on normal strain/stress

    Science.gov (United States)

    Combe, N.; Mompiou, F.; Legros, M.

    2017-08-01

    In specific conditions, grain-boundary (GB) migration occurs in polycrystalline materials as an alternative vector of plasticity compared to the usual dislocation activity. The shear-coupled GB migration, the expected most efficient GB based mechanism, couples the GB motion to an applied shear stress. Stresses on GB in polycrystalline materials seldom have, however, a unique pure shear component. This work investigates the influence of a normal strain on the shear coupled migration of a Σ 13 (320 )[001 ] GB in a copper bicrystal using atomistic simulations. We show that the yield shear stress inducing the GB migration strongly depends on the applied normal stress. Beyond, the application of a normal stress on this GB qualitatively modifies the GB migration: while the Σ 13 (320 )[001 ] GB shear couples following the 〈110 〉 migration mode without normal stress, we report the observation of the 〈010 〉 mode under a sufficiently high tensile normal stress. Using the nudge elastic band method, we uncover the atomistic mechanism of this 〈010 〉 migration mode and energetically characterize it.

  6. Grain boundary migration induced segregation in V-Cr-Ti alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gelles, D.S. [Pacific Northwest National Lab., Richland, WA (United States); Ohnuki, S.; Takahashi, H. [Univ. of Hokkaido (Japan)

    1996-10-01

    Analytical electron microscopy results are reported for a series of vanadium alloys irradiated in the HFIR JP23 experiment at 500{degrees}C. Alloys were V-5Cr-5Ti and pure vanadium which are expected to have transmuted to V-15Cr-5Ti and V-10Cr following irradiation. Analytical microscopy confirmed the expected transmutation occurred and showed redistribution of Cr and Ti resulting from grain boundary migration in V-5Cr-5Ti, but in pure V, segregation was reduced and no clear trends as a function of position near a boundary were identified.

  7. Onset of Grain Boundary Migration and Drastic Weakening of Quartzite during increasing grade of Metamorphism in the Contact Aureole surrounding the Eureka Valley-Joshua Flat-Beer Creek pluton, California, USA

    Science.gov (United States)

    Morgan, S. S.; Student, J. J.; Jakeway, J.

    2015-12-01

    The Eureka Valley-Joshua Flat-Beer Creek (EJB) pluton in eastern California is surrounded by a ~1.3 km wide intensely deformed concordant aureole of metasedimentary rocks. South of the pluton, the Harkless Quartzite can be mapped from where it is located outside the aureole, with its regional strike through the transition into the aureole and concordancy with the pluton. The transition into concordancy, which is fairly abrupt, occurs over a distance of less than 100 m. Across this transition the bedding rotates close to 90° to become subvertical. Here the metasedimentary formations in the aureole have undergone 65% shortening. A suite of Harkless Quartzite samples was collected starting at 2.3 km south of the pluton, across the transition into concordancy at 1.3 km, and to within 450m from the pluton contact. Microstructurally, the transition is defined by changes in the dominant recrystallization mechanisms. At 2.3 km from the pluton, subgrain rotation recrystallization (SGR) plus grain boundary migration (GBM) operate together and many sedimentary grains (rounded grain boundaries) exist. As the pluton is approached, SGR decreases, GBM increases, and rounded grain boundaries slowly disappear. The abrupt transition into concordancy is marked by the final disappearance of SGR and rounded grain boundaries and extensive GBM. The transition is not completely smooth, and other variables such as pinning and amount of fluid inclusions seem to have a strong local affect on the dominant recrystallization mechanism. We suspect that the onset of extensive GBM allows for the diffusion of water into the crystal lattice which results in the drastic weakening and rotation of metasedimentary formations into concordancy.

  8. The effect of strain path change on subgrain volume fraction determined from in situ X-ray measurements

    DEFF Research Database (Denmark)

    Wejdemann, Christian; Poulsen, Henning Friis; Lienert, U.

    2009-01-01

    dislocation density called subgrains bounded by dislocation rich walls. With the new technique reciprocal space maps, consisting of sharp peaks arising from the subgrains superimposed on a cloud of lower intensity arising from the dislocation walls, are obtained, which allows properties such as subgrain...

  9. Mobile migrants, mobile germs: migration, contagion, and boundary-building in Shenzhen, China after SARS.

    Science.gov (United States)

    Mason, Katherine A

    2012-01-01

    Shenzhen, a city located on the border between Mainland China and Hong Kong, is populated primarily by internal Chinese migrants. After the 2003 SARS epidemic, the pressure in Shenzhen to contain infectious disease has been considerable. By engaging with issues of global biosecurity, migration and citizenship, and intersubjectivity in medicine, I argue that in their attempts to prevent another SARS and protect their own subject positions as modern, urban citizens, Shenzhen's public health professionals worked to maintain precarious boundaries between themselves and their city's majority migrant population. However, by establishing the migrants as dangerous, biological noncitizens, by denying connections between the migrants' experiences and their own experiences of migration, by failing to engage with the migrants as subjects, and by defending structures that institutionalized these exclusions, they undermined both the health of the migrants and the stability of the city they were trying to protect.

  10. Predicting insect migration density and speed in the daytime convective boundary layer.

    Directory of Open Access Journals (Sweden)

    James R Bell

    Full Text Available Insect migration needs to be quantified if spatial and temporal patterns in populations are to be resolved. Yet so little ecology is understood above the flight boundary layer (i.e. >10 m where in north-west Europe an estimated 3 billion insects km(-1 month(-1 comprising pests, beneficial insects and other species that contribute to biodiversity use the atmosphere to migrate. Consequently, we elucidate meteorological mechanisms principally related to wind speed and temperature that drive variation in daytime aerial density and insect displacements speeds with increasing altitude (150-1200 m above ground level. We derived average aerial densities and displacement speeds of 1.7 million insects in the daytime convective atmospheric boundary layer using vertical-looking entomological radars. We first studied patterns of insect aerial densities and displacements speeds over a decade and linked these with average temperatures and wind velocities from a numerical weather prediction model. Generalized linear mixed models showed that average insect densities decline with increasing wind speed and increase with increasing temperatures and that the relationship between displacement speed and density was negative. We then sought to derive how general these patterns were over space using a paired site approach in which the relationship between sites was examined using simple linear regression. Both average speeds and densities were predicted remotely from a site over 100 km away, although insect densities were much noisier due to local 'spiking'. By late morning and afternoon when insects are migrating in a well-developed convective atmosphere at high altitude, they become much more difficult to predict remotely than during the early morning and at lower altitudes. Overall, our findings suggest that predicting migrating insects at altitude at distances of ≈ 100 km is promising, but additional radars are needed to parameterise spatial covariance.

  11. EBSD analysis of subgrain boundaries and dislocation slip systems in Antarctic and Greenland ice

    NARCIS (Netherlands)

    Weikusat, I.; Kuiper, E. N.; Pennock, G. M.; Kipfstuhl, S.; Drury, M. R.

    2017-01-01

    Ice has a very high plastic anisotropy with easy dislocation glide on basal planes, while glide on non-basal planes is much harder. Basal glide involves dislocations with the Burgers vector b = 〈a〉, while glide on non-basal planes can involve dislocations with b = 〈a〉, b = [c], and b = 〈c + a〉.

  12. Effects of subgrain size and static recrystallization on the mechanical performance of polycrystalline material: A microstructure-based crystal plasticity finite element analysis

    Directory of Open Access Journals (Sweden)

    Fengbo Han

    2015-02-01

    Full Text Available In this paper, the effects of subgrain size and static recrystallization on the mechanical performance of polycrystalline material were investigated using a microstructure-based crystal plasticity finite element (CPFE model. Firstly, polycrystalline microstructures with different mean subgrain sizes were prepared using simple assumption based on experimental observations, and intermediate microstructures during static recrystallization (SRX were simulated by a cellular automata model adopting curvature driven grain/subgrain growth mechanism. Then, CPFE method was applied to perform stress analysis of plane strain tension on these virtual microstructures. The results show that the subgrains inside pre-existing grains have an effect on the heterogeneity of the stress distributions. The average stress decreases with increasing the mean subgrain radius. As grain/subgrain grows during SRX, the average stress also decreases. It can be deduced that well-defined and finer subgrain structure may strengthen the polycrystalline material, while grain/subgrain growth during SRX process will degrade the strength.

  13. The Iceland Plate Boundary Zone: Propagating Rifts, Migrating Transforms, and Rift-Parallel Strike-Slip Faults

    Science.gov (United States)

    Karson, J. A.

    2017-11-01

    Unlike most of the Mid-Atlantic Ridge, the North America/Eurasia plate boundary in Iceland lies above sea level where magmatic and tectonic processes can be directly investigated in subaerial exposures. Accordingly, geologic processes in Iceland have long been recognized as possible analogs for seafloor spreading in the submerged parts of the mid-ocean ridge system. Combining existing and new data from across Iceland provides an integrated view of this active, mostly subaerial plate boundary. The broad Iceland plate boundary zone includes segmented rift zones linked by transform fault zones. Rift propagation and transform fault migration away from the Iceland hotspot rearrange the plate boundary configuration resulting in widespread deformation of older crust and reactivation of spreading-related structures. Rift propagation results in block rotations that are accommodated by widespread, rift-parallel, strike-slip faulting. The geometry and kinematics of faulting in Iceland may have implications for spreading processes elsewhere on the mid-ocean ridge system where rift propagation and transform migration occur.

  14. Contribution of precipitate on migrated grain boundaries to ductility-dip cracking in Alloy 625 weld joints

    Science.gov (United States)

    Lee, Dong Jin; Kim, Youn Soo; Shin, Yong Taek; Jeon, Eon Chan; Lee, Sang Hwa; Lee, Hyo-Jong; Lee, Sung Keun; Lee, Jun Hee; Lee, Hae Woo

    2010-10-01

    We investigated the crack properties in Alloy 625 weld metals and their characteristics using experimentally designed filler wires fabricated by varying the niobium and manganese contents in the flux with the shield metal arc welding (SMAW) process. The fast diffusivity of niobium on the migrated grain boundary (MGB) under strong restraint tensile stress, which was induced by the hardened matrix in weld metal containing high niobium and manganese, accelerated the growth of niobium carbide (NbC) in multipass deposits. Coalescence of microvoids along with incoherent NbC and further propagation induced ductility-dip cracking (DDC) on MGB.

  15. Introduction: Understanding Migration Research (Across National and Academic Boundaries in Europe

    Directory of Open Access Journals (Sweden)

    Maren Borkert

    2006-05-01

    Full Text Available In this introduction to the special issue we argue that migration is a phenomenon that shifts space and time. It is an ageless human strategy to improve life and could be defined as a natural behaviour of human beings. What makes migration a subject of investigation are processes like nation-state-building, Europeanisation, globalisation and economic polarisation, which problematise the free movement of people. Academic researchers have responded to the challenges associated with this by drawing upon a range of disciplines, gathering evidence from a variety of countries, and employing an array of methodological tools to examine the emergent and evolving processes and patterns of Europe's new migration. Nonetheless, one is still faced with bewildering diversity in terms of migrant flows and the minority communities that form from these. This complexity, we argue, presents a new challenge for European migration research, particularly to those researchers attempting to understand patterns and processes of migration at a pan-European level and/or entering the field for the first time. The collection is an attempt to explore these challenges from different national and disciplinary perspectives and this introduction is designed to set the scene for this project. URN: urn:nbn:de:0114-fqs060339

  16. A new mechanism for fluid migration in midcrustal shear zones based on viscous grain boundary sliding and creep cavitation

    Science.gov (United States)

    Fusseis, F.; Regenauer-Lieb, K.; Liu, J.

    2009-04-01

    The common perception of fluid migration pathways in midcrustal shear zones relies mostly on hydraulic fractures forming by tensile failure where pore fluid pressure equalizes the combined lithostatic pressure and the tensile strength of the rock. Where the associated pervasive fracturing on multiple scales does not occur but the presence of a fluid phase is indicated, different models are needed to explain fluid transfer. Here we present the ‘granular fluid pump', a model that is capable of explaining fluid migration in fine-grained ultramylonites typical for midcrustal shear zones. We investigated the porosity evolution across the margin of a shear zone in central Australia that formed in granitic gneiss at upper-greenschist facies conditions (Fliervoet et al., 1997). The strain gradient in the sample, which is macroscopically expressed by the reorientation of a preexisting foliation and a substantial grain size reduction, is interpreted as a proxy for time. Our investigation showed that the microstructural evolution of the sample is characterized by two major processes: a) The progressive reduction in abundance and size of potassium feldspar and plagioclase clasts, which decay, with increasing strain, in hydration reactions to form a fine-grained (4% and that the relative frequency of the smallest detectable pores (1.3-3.9 microns) increases from tens of microns) tend to cluster in plagioclase grains, a form of porosity that is associated with feldspar decay and a removal of chemical components. Towards the shear zone center, pores are smaller (micron-sized and below) and generally occur along grain boundaries. Most pores occur in ‘pore sheets' that characterize the multiphase ultramylonitic layers. These grain boundary pores often occur at triple junctions. Lobes extending into neighboring grains and pockmarked surfaces evidence dissolution; little crystallites in grain boundary pores indicate precipitation and mineral growth. Both observations indicate the

  17. Saltmarsh boundary modulates dispersal of mangrove propagules: implications for mangrove migration with sea-level rise.

    Directory of Open Access Journals (Sweden)

    Jennifer M Peterson

    Full Text Available Few studies have empirically examined the suite of mechanisms that underlie the distributional shifts displayed by organisms in response to changing climatic condition. Mangrove forests are expected to move inland as sea-level rises, encroaching on saltmarsh plants inhabiting higher elevations. Mangrove propagules are transported by tidal waters and propagule dispersal is likely modified upon encountering the mangrove-saltmarsh ecotone, the implications of which are poorly known. Here, using an experimental approach, we record landward and seaward dispersal and subsequent establishment of mangrove propagules that encounter biotic boundaries composed of two types of saltmarsh taxa: succulents and grasses. Our findings revealed that propagules emplaced within saltmarsh vegetation immediately landward of the extant mangrove fringe boundary frequently dispersed in the seaward direction. However, propagules moved seaward less frequently and over shorter distances upon encountering boundaries composed of saltmarsh grasses versus succulents. We uniquely confirmed that the small subset of propagules dispersing landward displayed proportionately higher establishment success than those transported seaward. Although impacts of ecotones on plant dispersal have rarely been investigated in situ, our experimental results indicate that the interplay between tidal transport and physical attributes of saltmarsh vegetation influence boundary permeability to propagules, thereby directing the initial phase of shifting mangrove distributions. The incorporation of tidal inundation information and detailed data on landscape features, such as the structure of saltmarsh vegetation at mangrove boundaries, should improve the accuracy of models that are being developed to forecast mangrove distributional shifts in response to sea-level rise.

  18. Subgrain and dislocation structure changes in hot-deformed high-temperature Fe-Ni austenitic alloy

    Energy Technology Data Exchange (ETDEWEB)

    Ducki, K.J.; Rodak, K.; Hetmanczyk, M.; Kuc, D

    2003-08-28

    The influence of plastic deformation on the substructure of a high-temperature austenitic Fe-Ni alloy has been presented. Hot-torsion tests were executed at constant strain rates of 0.1 and 1.0 s{sup -1}, at testing temperatures in the range 900-1150 deg. C. The examination of the microstructure was carried out, using transmission electron microscopy. Direct measurements on the micrographs allowed the calculation of structural parameters: the average subgrain area, and the mean dislocation density. A detailed investigation has shown that the microstructure is inhomogeneous, consisting of dense dislocation walls, subgrains and recrystallized regions.

  19. Gas migration in KBS-3 buffer bentonite. Sensitivity of test parameters to experimental boundary conditions

    Energy Technology Data Exchange (ETDEWEB)

    Harrington, J.F.; Horseman, S.T. [British Geological Survey, Nottingham (United Kingdom)

    2003-01-01

    In the current Swedish repository design concept, hydrogen gas can be generated inside a waste canister by anaerobic corrosion of the ferrous metal liner. If the gas generation rate exceeds the diffusion rate of gas molecules in the buffer porewater, gas will accumulate in the void-space of a canister until its pressure becomes large enough for it to enter the bentonite as a discrete gaseous phase. Three long tenn gas injection tests have been performed on cylinders of pre-compacted MX80 bentonite. Two of these tests were undertaken using a custom-designed constant volume and radial flow (CVRF) apparatus. Gas was injected at a centrally located porous filter installed in the clay before hydration. Arrangements were made for gas to flow to three independently monitored sink-filter arrays mounted around the specimen. Axial and radial total stresses and internal porewater pressures were continuously monitored. Breakthrough and peak gas pressures were substantially larger than the sum of the swelling pressure and the external porewater. The third test was performed. using an apparatus which radially constrains the specimen during gas flow. Observed sensitivity of the breakthrough and peak gas pressures to the test boundary conditions suggests that gas entry must be accompanied by dilation of the bentonite fabric. In other words, there is a tendency for the volume of the specimen to increase during this process. The experimental evidence is consistent with the flow of gas along a relatively small number of crack-like pathways which propagate through the clay as gas pressure increases. Gas entry and breakthrough under constant volume boundary conditions causes a substantial increase in the total stress and the internal porewater pressure. It is possible to determine the point at which gas enters the clay by monitoring changes in these parameters. Localisation of gas flow within multiple pathways results, in nonuniform discharge rates at the sinks. When gas injection

  20. Progressive migration of slab break-off along the southern Tyrrhenian plate boundary: Constraints for the present day kinematics

    Science.gov (United States)

    Chiarabba, Claudio; Palano, Mimmo

    2017-04-01

    The Ionian subduction in the central Mediterranean, just 200 km wide, is one of the narrowest in the world. Its evolution has involved a progressive disruption of the subducting slab, contemporaneous to the retreat and step-wise opening of back-arc basins. In this study, we analyse velocity anomalies of the upper mantle, together with the most comprehensive set of earthquake locations and kinematic indicators available for Italy, to reconstruct the geodynamics and tectonic evolution of the Ionian subduction system. Along the Sicilian boundary, we identify an eastward migration of the slab edge with detachment of the Ionian oceanic lithosphere. We hypothesize that the progressive detachment of the slab took place along lithospheric transform faults of the Neo-Tethys Ocean. Among the main active kinematic elements of the Ionian accretionary wedge, we suggest that a ∼400-km-long and highly segmented shear zone formed by the Aeolian-Tindari-Letojanni fault system and the Ionian fault represents the surface expression of such a lithospheric tearing. The present day convergence between the Eurasian and African plates is accommodated both at the frontal thrust of the flexed Hyblean margin in southern Sicily and offshore along the Tyrrhenian Sea. Lithospheric bending favors the wedging of the mantle underneath northern Sicily, while magmatic fluids are channeled along slab tears.

  1. Ground boundaries

    Science.gov (United States)

    Balluffi, R. W.; Bristowe, P. D.

    The present document is a progress report describing the work accomplished on the study of grain boundaries in Ag, Au, Ni, Si, and Ge. Research was focused on the following four major efforts: study of the atomic structure of grain boundaries by means of x-ray diffraction, transmission electron microscopy and computer modeling; grain boundary migration; short-circuit diffusion along grain boundaries; and development of Thin-Film Deposition/Bonding Apparatus for the manufacture of high purity bicrystals.

  2. Subgrain Rotation Behavior in Sn3.0Ag0.5Cu-Sn37Pb Solder Joints During Thermal Shock

    Science.gov (United States)

    Han, Jing; Tan, Shihai; Guo, Fu

    2018-01-01

    Ball grid array (BGA) samples were soldered on a printed circuit board with Sn37Pb solder paste to investigate the recrystallization induced by subgrain rotation during thermal shock. The composition of the solder balls was Sn3.0Ag0.5Cu-Sn37Pb, which comprised mixed solder joints. The BGA component was cross-sectioned before thermal shock. The microstructure and grain orientations were obtained by a scanning electron microscope equipped with an electron back-scattered diffraction system. Two mixed solder joints at corners of the BGA component were selected as the subjects. The results showed that recrystallization occurred at the corner of the solder joints after 200 thermal shock cycles. The recrystallized subgrains had various new grain orientations. The newly generated grain orientations were closely related to the initial grain orientations, which indicated that different subgrain rotation behaviors could occur in one mixed solder joint with the same initial grain orientation. When the misorientation angles were very small, the rotation axes were about Sn [100], [010] and [001], as shown by analyzing the misorientation angles and subgrain rotation axes, while the subgrain rotation behavior with large misorientation angles in the solder joints was much more complicated. As Pb was contained in the solder joints and the stress was concentrated on the corner of the mixed solder joints, concaves and cracks were formed. When the adjacent recrystallized subgrains were separated, and the process of the continuous recrystallization was limited.

  3. A fourth order accuracy summation-by-parts finite difference scheme for acoustic reverse time migration in boundary-conforming grids

    Science.gov (United States)

    Wang, Ying; Zhou, Hui; Yuan, Sanyi; Ye, Yameng

    2017-01-01

    The fourth order accuracy finite difference scheme is known advantageous in reducing memory and improving efficiency. Summation-by-parts finite difference operator is a natural way for wavefield simulation in complicated domains containing surface topography and irregular interfaces. The application of summation-by-parts method guarantees the stability of numerical approximation for heterogeneous media on curvilinear grids. This paper extends the second order summation-by-parts finite difference method to the fourth order case for the discretization of acoustic wave equation and perfect matched layer in boundary-conforming grids. In particular, the implementation of the fourth order method for wavefield simulation and reverse time migration in complicated domains can significantly improve the efficiency and decrease the storage. The elliptic method is applied for boundary-conforming grid generation in complicated domains. Under such grids, the two-dimensional acoustic wave equation in second order displacement formulation is compactly reformulated for forward modeling and reverse time migration, and the symmetric and compact form of perfectly matched layers expressed in a curvilinear coordinate system are applied to suppress artificial reflections. The discretizations of the acoustic wave equation and perfectly matched layer formula are fourth and second order accuracy in space and time respectively, where the spatial discretization satisfies the principle of summation-by-parts and is stable. Numerical experiments are presented to compare the accuracy of the second with fourth order summation-by-parts finite difference methods and to evaluate the efficiency of reverse time migration by using these two methods. As well, comparisons are performed between the fourth order accuracy summation-by-parts finite difference method and central finite difference method to illustrate the stability superiority of summation-by-parts operators.

  4. Direct observation of grain boundary migration during recrystallization within the bulk of a moderately deformed aluminium single crystal

    DEFF Research Database (Denmark)

    Van Boxel, Steven; Schmidt, Søren; Ludwig, Wolfgang

    2014-01-01

    A single grain growing in the bulk of a mildly deformed (30% thickness reduction through cold rolling) aluminium single crystal with an {001}<100> orientation (Cube orientation), is monitored during recrystallization with synchrotron radiation using topo-tomography. The formation and migration of...... of the analyzed facets is not closely related to any crystallographic {111} plane of neither the growing grain nor the disappearing deformed matrix. © 2013 The Japan Institute of Metals and Materials.......A single grain growing in the bulk of a mildly deformed (30% thickness reduction through cold rolling) aluminium single crystal with an {001} orientation (Cube orientation), is monitored during recrystallization with synchrotron radiation using topo-tomography. The formation and migration...

  5. Ground boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Balluffi, R.W.; Bristowe, P.D.

    1990-01-01

    The present document is a progress report describing the work accomplished on the study of grain boundaries in Ag, Au, Ni, Si, and Ge. Research was focused on the following four major efforts: study of the atomic structure of grain boundaries by means of x-ray diffraction, transmission electron microscopy and computer modeling; grain boundary migration; short-circuit diffusion along grain boundaries; and development of Thin-Film Deposition/Bonding Apparatus for the manufacture of high purity bicrystals. 10 refs., 1 fig.

  6. Direct observation of strain in bulk subgrains and dislocation walls by high angular resolution three-dimensional X-ray diffraction

    DEFF Research Database (Denmark)

    Jakobsen, Bo; Lienert, U.; Almer, J.

    2008-01-01

    associated with the grain, shows a distinct structure consisting of sharp bright peaks superimposed on a cloud of enhanced intensity. The bright peaks (which arise from individual subgrains) are found to be subjected to backward strain (on average) while the fraction of the material giving rise to the cloud...

  7. Space-time model for migration of weak earthquakes along the northern boundary of the Amurian microplate

    Science.gov (United States)

    Trofimenko, S. V.; Bykov, V. G.; Merkulova, T. V.

    2017-03-01

    In this paper, we aimed to investigate the statistical distributions of shallow earthquakes with 2 ≤ M ≤ 4, located in 13 rectangular areas (clusters) bounded by 120°E and 144°E along the northern boundary of the Amurian microplate. As a result of our study, the displacement of seismicity maxima has been determined and three recurrent spatial cycles have been observed. The clusters with similar distribution of earthquakes are suggested to alternate being equally spaced at 7.26° (360-420 km). A comparison of investigation results on the structure of seismicity in various segments of the Amurian microplate reveals the identity between the alternation pattern observed for meridional zones of large earthquakes and a distinguished spatial period. The displacement vector for seismicity in the annual cycles is determined, and the correspondence between its E-W direction and the displacement of the fronts of large earthquakes is established. The elaborated model of seismic and deformation processes is considered, in which subsequent activation of clusters of weak earthquakes (2 ≤ M ≤ 4), tending to extend from the Japanese-Sakhalin island arc to the eastern closure of the Baikal rift zone, is initiated by the displacement of the strain wave front.

  8. X-Ray and Neutron Diffraction Measurements of Dislocation Density and Subgrain Size in a Friction-Stir-Welded Aluminum Alloy

    Science.gov (United States)

    Woo, Wanchuck; Ungár, Tamás; Feng, Zhili; Kenik, Edward; Clausen, Bjørn

    2010-05-01

    The dislocation density and subgrain size were determined in the base material and friction-stir welds of 6061-T6 aluminum alloy. High-resolution X-ray diffraction measurement was performed in the base material. The result of the line profile analysis of the X-ray diffraction peak shows that the dislocation density is about 4.5 × 1014 m-2 and the subgrain size is about 200 nm. Meanwhile, neutron diffraction measurements have been performed to observe the diffraction peaks during friction-stir welding (FSW). The deep penetration capability of the neutron enables us to measure the peaks from the midplane of the Al plate underneath the tool shoulder of the friction-stir welds. The peak broadening analysis result using the Williamson-Hall method shows the dislocation density of about 3.2 × 1015 m-2 and subgrain size of about 160 nm. The significant increase of the dislocation density is likely due to the severe plastic deformation during FSW. This study provides an insight into understanding the transient behavior of the microstructure under severe thermomechanical deformation.

  9. Subgrain-scale decoupling of Re and 187Os and assessment of laser ablation ICP-MS spot dating in molybdenite

    Science.gov (United States)

    Stein, Holly; Scherstén, Anders; Hannah, Judith; Markey, Richard

    2003-10-01

    Reproducibility of Re-Os molybdenite ages depends on sample size and homogeneity, suggesting that Re and Os are decoupled within individual molybdenite crystals and do not remain spatially linked over time. In order to investigate the Re-Os systematics of molybdenite at the subgrain (micron) scale, we report LA-ICP-MS Re-Os ages for an Archean molybdenite crystal from Aittojärvi, Finland, analyzed in situ in a white aplite matrix. A related Aittojärvi molybdenite (A996D), in the form of a very fine-grained mineral separate, is used as one of our in-house NTIMS standards, and thus its age of 2760 ± 9 Ma is well established. Measurements of ( 187Re + 187Os)/ 185Re on micron scale spots along 200 μm traverses across the crystal yield a wide range of ages demonstrating that, in this case, microsampling of molybdenite does not produce geologically meaningful ages. Experimentation with mineral separations and sample size over a 7-yr period predicted that this would be the outcome. We suggest that 187Os is more likely to be the mobile species, based on its charge and ionic radius, and that 187Os becomes decoupled from parent 187Re with time on the micron and larger scale. Incompatible charge and ionic radius for Os ions formed during reduction of molybdenite-forming fluids may explain the widely observed absence of common (initial) Os in molybdenite. Geologically accurate ages for molybdenite can only be obtained for fully homogenized crystals (or crystal aggregates) so that any post-crystallization 187Re- 187Os decoupling is overcome. A growing number of geologically accurate ID-NTIMS 187Re- 187Os ages for homogenized molybdenite suggest that postcrystallization mobility of radiogenic 187Os must be limited to within the molybdenite mineral phase. We suggest that radiogenic 187Os may be stored in micron scale dislocations, kink bands, and delamination cracks produced by deformation, and that the unusual structure and deformation response of molybdenite results in an

  10. Boundary identification in EBSD data with a generalization of fast multiscale clustering

    Energy Technology Data Exchange (ETDEWEB)

    McMahon, Cullen, E-mail: cullen_mcmahon@hmc.edu [Department of Engineering, Harvey Mudd College, 301 Platt Blvd, Claremont, CA 91711 (United States); Soe, Brian, E-mail: brian_soe@hmc.edu [Department of Engineering, Harvey Mudd College, 301 Platt Blvd, Claremont, CA 91711 (United States); Loeb, Andrew, E-mail: andrew_loeb@hmc.edu [Department of Engineering, Harvey Mudd College, 301 Platt Blvd, Claremont, CA 91711 (United States); Vemulkar, Ayyappa, E-mail: ayyappa_vemulkar@hmc.edu [Department of Engineering, Harvey Mudd College, 301 Platt Blvd, Claremont, CA 91711 (United States); Ferry, Michael, E-mail: m.ferry@unsw.edu.au [School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Bassman, Lori, E-mail: bassman@hmc.edu [Department of Engineering, Harvey Mudd College, 301 Platt Blvd, Claremont, CA 91711 (United States)

    2013-10-15

    Electron backscatter diffraction (EBSD) studies of cellular or subgrain microstructures present problems beyond those in the study of coarse-grained polycrystalline aggregates. In particular, identification of boundaries delineating some subgrain structures, such as microbands, cannot be accomplished simply with pixel-to-pixel misorientation thresholding because many of the boundaries are gradual transitions in crystallographic orientation. Fast multiscale clustering (FMC) is an established data segmentation technique that is combined here with quaternion representation of orientation to segment EBSD data with gradual transitions. This implementation of FMC addresses a common problem with segmentation algorithms, handling data sets with both high and low magnitude boundaries, by using a novel distance function that is a modification of Mahalanobis distance. It accommodates data representations, such as quaternions, whose features are not necessarily linearly correlated but have known distance functions. To maintain the linear run time of FMC with such data, the method requires a novel variance update rule. Although FMC was originally an algorithm for two-dimensional data segmentation, it can be generalized to analyze three-dimensional data sets. As examples, several segmentations of quaternion EBSD data sets are presented. - Highlights: • EBSD data with gradual or subtle boundaries presents problems in segmentation. • Fast multiscale clustering is modified for use with quaternion data. • Further generalizations to any data type with a distance metric are possible. • Polycrystalline and subgrain EBSD data sets are segmented as demonstration.

  11. Structure and properties of grain boundaries

    Science.gov (United States)

    Balluffi, R. W.; Bristowe, P. D.

    1984-03-01

    Results were obtained in the following areas: determination of relative grain boundary energies by the rotating crystallite method; simple structural unit model for core dependent properties of tilt boundaries; twist boundary energies for metals with long ranged pairwise interatomic potentials; structural unit/grain boundary dislocation model for grain boundary structure; detection of expansion of boundaries using diffraction; effect of secondary relaxations on diffraction from high-(SIGMA) 001 twist boundaries; and mechanism of grain boundary migration.

  12. Progress report on grain boundaries

    Science.gov (United States)

    Balluffi, R. W.; Bristowe, P. D.

    1989-06-01

    The research was focused on the following three major areas: (1) study of the atomic structure of grain boundaries by means of X-ray diffraction, transmission electron microscopy and computer modeling; (2) study of grain boundary phase transitions by electron microscopy and computer modeling; (3) investigation of the mechanism of high angle grain boundary migration. Results are briefly discussed.

  13. Progress report on grain boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Balluffi, R.W.; Bristowe, P.D.

    1989-06-01

    The research was focused on the following three major areas: (1) study of the atomic structure of grain boundaries by means of x-ray diffraction, transmission electron microscopy and computer modeling; (2) study of grain boundary phase transitions by electron microscopy and computer modeling; (3) investigation of the mechanism of high angle grain boundary migration. Results are briefly discussed. 20 refs.

  14. On grain boundary facetting under stress during high temperature deformation of Al and Al-Ga alloys

    Energy Technology Data Exchange (ETDEWEB)

    Weygand, D.; Doisneau-Cottignies, B.; Brechet, Y. [Domaine Univ. de Grenoble, St. Martin d`Heres (France). LTPCM; Blandin, J.J. [GPMM, Domaine Universitaire de Grenoble, 38402 St. Martin d`Heres (France)

    1997-08-30

    Aluminuim of high purity and aluminium with 50 ppm gallium were deformed under various strain rates and temperatures in order to investigate the possible influence of liquid like grain boundaries on grain boundary sliding and macroscopic deformation behaviour. Under all conditions, serrated grain boundaries were observed to develop during the tensile test. Those serrated structures were correlated to the development of subgrains observed by optical metallography and transmission electron microscopy. In the absence of an applied stress, further annealing lead to disappearing of the serrated grain boundaries when the annealing temperature was higher than the tensile test temperature under which the serrations were developed. (orig.) 9 refs.

  15. Mechanically induced grain boundary motion in Al-bicrystals

    Energy Technology Data Exchange (ETDEWEB)

    Gorkaya, Tatiana; Molodov, Dmitri A.; Gottstein, Guenter [Institut fuer Metallkunde und Metallphysik der RWTH Aachen (Germany)

    2010-07-01

    The mechanically induced migration of planar grain boundaries in Al-bicrystals was experimentally measured. The novel tensile/compression module for scanning electron microscope was utilized for in-situ measurements of grain boundary motion at elevated temperatures. From the measured temperature dependence of boundary mobility the migration activation parameters for investigated boundaries were determined. Normal boundary motion was observed to be coupled to a shear of the crystal in the region traversed by the grain boundary during its motion. The measured ratios of the normal grain boundary motion to the lateral translation of grains were compared with geometrical models of stress induced boundary migration.

  16. Grain boundaries. Progress report, February 15, 1990--October 15, 1990

    Energy Technology Data Exchange (ETDEWEB)

    Balluffi, R.W.; Bristowe, P.D.

    1990-12-31

    The following are reported: structural studies (dislocation structure of Ni/Ag interphase boundary, structural complexity in grain boundaries with covalent bonding, relation between microscopic properties of two semiconducting grain boundaries and their orientations, diffraction effects due to double positioning in (111) Au bicrystals, sensitivity of diffraction profiles to grain boundary segregation, solute segregation at grain boundaries in Au, 4-body interatomic potential for Si for defect calculations); boundary migration studies (molecular dynamics study of grain boundary migration without participation of grain boundary dislocations); study of short-circuit diffusion along grain boundaries and its dependence on boundary structure; and thin-film deposition/bonding apparatus for manufacturing high-purity bicrystals.

  17. Fluid-controlled grain boundary migration and switch in slip systems in a high strain, high temperature contact aureole, California, USA

    Science.gov (United States)

    Morgan, Sven S.; Nabelek, Peter I.; Student, James; Sadorski, Joseph F.

    2016-04-01

    Within the highly strained aureole surrounding the Eureka Valley-Joshua Flat-Beer Creek (EJB) composite pluton of eastern California, an inversion in microstructures and crystallographic preferred orientations (CPOs) exists with distance from the contact. An inner aureole ( slip in quartz. Within the outer aureole (250 m to 1500 m from the contact), quartzites are interbedded with pelitic schist and are completely recrystallized and microstructures are indicative of extensive GBM. CPOs are indicative of prism [c] slip. Oxygen isotope ratios in the inner aureole are only slightly shifted from their original values. Oxygen isotopes from the outer aureole are shifted more, which is consistent with equilibration with locally derived fluids. We suggest that recrystallization in the outer aureole was aided by pore water, water derived from fluid inclusions, and water generated by prograde reactions in the schists. The pore fluids in the inner aureole were also probably initially water-rich. However, during prograde reactions in the intervening calc-silicate rocks, and perhaps more importantly, between calcite cement and quartz in the quartzites, the pore fluid composition in the inner aureole changed to become dominated by CO2, which acted as a non-wetting phase and decreased the fugacity of water slowing grain boundary mobility. Low water fugacity also suppressed the activity of prism [c] slip. Therefore, we propose that dry conditions or a grain boundary fluid with a significant non-wetting component (CO2) can result in apparent temperatures of deformation that are more than 100 °C lower than the real temperatures of deformation.

  18. Quantitative Characterization of Boundary Roughness in Metals

    DEFF Research Database (Denmark)

    Sun, Jun

    The boundary migration during recrystallization is by nature a heterogeneous process and local structural variations form on recrystallization boundaries, as revealed from modern techniques such as synchrotron X-rays and advanced electron microscopy. The local structural variations, in the form...... of protrusions and retrusions, can provide a dragging/driving force due to the local boundary curvature and affect the further migration of recrystallization boundaries through the deformed matrix. In order to develop new understandings and models for boundary migration that take the heterogeneous local...... structural aspects into account, a detailed characterization is essential of partly recrystallized microstructures focusing on the local shapes of the boundaries, in particular on whether protrusions and retrusions are formed or not. Quantification of the “amount” of boundary roughness in the form...

  19. 'Migration & Integration'

    OpenAIRE

    Lisa Pilgram

    2011-01-01

    Migration, Integration : [kommunalpolitische Herausforderungen]. - Augsburg : Geo-Anwenderzentrum, [ca. 2004]. - XVIII, 281 S. - (Angewandte Sozialgeographie ; 49) (GEO-Taschenbuch). - Zugl.: Augsburg, Univ., Diss., 2003

  20. Properties of grain boundary networks in the NEEM ice core analyzed by combined transmission and reflection optical microscopy

    Science.gov (United States)

    Binder, Tobias; Weikusat, Ilka; Garbe, Christoph; Svensson, Anders; Kipfstuhl, Sepp

    2014-05-01

    Microstructure analysis of ice cores is vital to understand the processes controlling the flow of ice on the microscale. To quantify the microstructural variability (and thus occurring processes) on centimeter, meter and kilometer scale along deep polar ice cores, a large number of sections has to be analyzed. In the last decade, two different methods have been applied: On the one hand, transmission optical microscopy of thin sections between crossed polarizers yields information on the distribution of crystal c-axes. On the other hand, reflection optical microscopy of polished and controlled sublimated section surfaces allows to characterize the high resolution properties of a single grain boundary, e.g. its length, shape or curvature (further developed by [1]). Along the entire NEEM ice core (North-West Greenland, 2537 m length) drilled in 2008-2011 we applied both methods to the same set of vertical sections. The data set comprises series of six consecutive 6 x 9 cm2 sections in steps of 20 m - in total about 800 images. A dedicated method for automatic processing and matching both image types has recently been developed [2]. The high resolution properties of the grain boundary network are analyzed. Furthermore, the automatic assignment of c-axis misorientations to visible sublimation grooves enables us to quantify the degree of similarity between the microstructure revealed by both analysis techniques. The reliability to extract grain boundaries from both image types as well as the appearance of sublimation groove patterns exhibiting low misorientations is investigated. X-ray Laue diffraction measurements (yielding full crystallographic orientation) have validated the sensitivity of the surface sublimation method for sub-grain boundaries [3]. We introduce an approach for automatic extraction of sub-grain structures from sublimation grooves. A systematic analysis of sub-grain boundary densities indicates a possible influence of high impurity contents (amongst

  1. Gendering Migration

    Directory of Open Access Journals (Sweden)

    Mirjana Morokvašić

    2014-12-01

    Full Text Available Migration patterns, migration discourse and underlying representations, migrants’ experiences, obligations and duties as well as the expectations relative to their migration are gendered. Since the pioneering feminist migration scholars’ questioning of men as a universal reference and the invisibility of women or their stereotypical representations as dependents in the mainstream production of knowledge on migration, the scholarship has evolved considerably. It is argued in the paper that the ongoing process of cross-fertilization of developments in two separate epistemologies, each initially questioning monolithic and essentialist visions of a “migrant” on one hand and a “woman” on the other, produced a fecund subfield of research “migration and gender”. The paper provides an insight into this, reviewing work on the issues related to gendering different phases of migration. Bridging migration and gender brought to the top of research agendas issues that used to be on the margins, creating new visibilities but leaving out other gendered dimensions of complex realities of migrant experience.

  2. Cohort migration.

    Science.gov (United States)

    Taeuber, K E

    1966-06-01

    Most migration analyses focus on net migration and are concerned with areal redistributions of population. Migration may also be studied as an event in the life-cycle of an individual, and migration rates may be defined as properties of cohorts. A number of efforts to examine migration as a cohort process has been hampered by the character of available data [or the United States. Rather than await the development of a registration system-either directly or via social security and tax records-the collection of residence histories is suggested as the most feasible approach to obtaining suitable data. A schematic representation of residence histories clarifies their relation to other types of migration data and illustrates the need to design such surveys with specific research purposes in mind. Exploratory work with the 1958 Residence History Supplement to the Current Population Survey (by Beale, Shryock, myself, and various colleagues) demonstrates the utility of this approach.Local studies have made fruitful use of residence histories but typically are unable to delineate birth cohorts or other appropriate base populations exposed to risk. Development of cohort migration techniques analogous to the life table approach to mortality or cohort Jertility analysis requires national data. But migration, unlike Jertility and mortality, involves events that are reversible and repeatable. Hence the demographer's stock of analytic tools requires expansion. To the sociologist-demographer, experimentation with cohort migration models seems to be getting at one of the crucial methodological problems of sociology, the analysis of social mobility. A mutually profitable interchange with students of social mobility is envisaged.

  3. [Internal migration].

    Science.gov (United States)

    Borisovna, L

    1991-06-01

    Very few studies have been conducted that truly permit explanation of internal migration and it repercussions on social and economic structure. It is clear however that a profound knowledge of the determinants and consequences of internal migration will be required as a basis for economic policy decisions that advance the goal of improving the level of living of the population. the basic supposition of most studies of the relationship of population and development is that socioeconomic development conditions demographic dynamics. The process of development in Mexico, which can be characterized by great heterogeneity, consequently produces great regional disparities. At the national level various studies have estimated the volume of internal migration in Mexico, but they have usually been limited to interstate migration because the main source of data, the census, is classified by states. But given the great heterogeneity within states in all the elements related to internal migration, it is clear that studies of internal migration within states are also needed. Such studies are almost nonexistent because of their technical difficulty. National level studies show that interstate migration increased significantly between 1940-80. The proportion of Mexicans living outside their states of birth increased by 558% in those years, compared to the 342% increase in the total Mexican population. Although Puebla has a high rate of increase, migration has kept it below Mexico's national growth rate. Migration between Puebla and other states and within Puebla has led to an increasing unevenness of spatial distribution. Between 1970-80, 57 of Puebla's municipios had growth rates above the state average of 2.8%/year, 6 had growth rates equal to the average, and 129 had growth rates that were below the average but not negative. 25 states with negative growth rates that were considered strongly expulsive. In 1980, 51.7% of the population was concentrated in the 57 municipios

  4. Negotiating boundaries

    DEFF Research Database (Denmark)

    Aarhus, Rikke; Ballegaard, Stinne Aaløkke

    2010-01-01

    to maintain the order of the home when managing disease and adopting new healthcare technology. In our analysis we relate this boundary work to two continuums of visibility-invisibility and integration-segmentation in disease management. We explore five factors that affect the boundary work: objects......To move treatment successfully from the hospital to that of technology assisted self-care at home, it is vital in the design of such technologies to understand the setting in which the health IT should be used. Based on qualitative studies we find that people engage in elaborate boundary work......, activities, places, character of disease, and collaboration. Furthermore, the processes are explored of how boundary objects move between social worlds pushing and shaping boundaries. From this we discuss design implications for future healthcare technologies for the home....

  5. Boundary Spanning

    DEFF Research Database (Denmark)

    Zølner, Mette

    The paper explores how locals span boundaries between corporate and local levels. The aim is to better comprehend potentialities and challenges when MNCs draws on locals’ culture specific knowledge. The study is based on an in-depth, interpretive case study of boundary spanning by local actors...... in the period of post-acquisition when their organization is being integrated into the acquiring MNC. The paper contributes to the literature on boundary spanning in three ways: First, by illustrating that boundary spanning is performed by numerous organizational actors in a variety of positions in MNCs......, inclusively by locals in subsidiaries. Second, by showing that boundary spanning is ‘situated’ in the sense that its result depends on the kind of knowledge to be transmitted and the attitude of the receivers. A third contribution is methodological. The study illustrates that combining bottom-up grounded...

  6. Structure and properties of grain boundaries. Progress report, 15 July 1983-14 July 1984

    Energy Technology Data Exchange (ETDEWEB)

    Balluffi, R.W.; Bristowe, P.D.

    1984-03-01

    Results were obtained in the following areas: determination of relative grain boundary energies by the rotating crystallite method; simple structural unit model for core-dependent properties of tilt boundaries; twist boundary energies for metals with long-ranged pairwise interatomic potentials; structural unit/grain boundary dislocation model for grain boundary structure; detection of expansion of boundaries using diffraction; effect of secondary relaxations on diffraction from high-..sigma.. (001) twist boundaries; and mechanism of grain boundary migration.

  7. Grain boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Balluffi, R.W.; Bristowe, P.D.

    1991-01-01

    The present document is a progress report describing the work accomplished to date during the second year of our four-year grant (February 15, 1990--February 14, 1994) to study grain boundaries. The research was focused on the following three major efforts: Study of the atomic structure of grain boundaries by means of x-ray diffraction, transmission electron microscopy and computer modeling; study of short-circuit diffusion along grain boundaries; and development of a Thin-film Deposition/Bonding Apparatus for the manufacture of high purity bicrystals.

  8. Grain boundaries

    Science.gov (United States)

    Balluffi, R. W.; Bristowe, P. D.

    The present document is a progress report describing the work accomplished to date during the second year of our four-year grant (February 15, 1990 to February 14, 1994) to study grain boundaries. The research was focused on the following three major efforts: study of the atomic structure of grain boundaries by means of x-ray diffraction, transmission electron microscopy and computer modeling; study of short-circuit diffusion along grain boundaries; and development of a Thin-film Deposition/Bonding Apparatus for the manufacture of high purity bicrystals.

  9. Migrating Worker

    DEFF Research Database (Denmark)

    Hansen, Hans

    This is the preliminary report on the results obtained in the Migrating Worker-project. This project was initiated by the Danish Ministry of Finance with the aim of illustrating the effects of the 1408/71 agreement and the bilateral double taxation agreements Denmark has with the countries included...

  10. Dateline Migration.

    Science.gov (United States)

    Tomasi, Lydio E., Ed.

    1995-01-01

    Presents data on international migration and its effects in and between various countries in North America, Europe, and Africa. Discussions include refugee, immigrant, and migrant worker flows; the legal, political, and social problems surrounding immigrants; alien terrorism and law enforcement problems; and migrant effects on education, social…

  11. Cross-community migration: a distinctive human pattern

    OpenAIRE

    Manning, Patrick

    2006-01-01

    ABSTRACT Human migration can be shown to have clear parallels to that of other animal species: the movement of individuals within communities, the colonization of new territories, and the periodic movement of whole communities. But the existence of language among humans allows the creation of distinctive language communities, and therefore of a uniquely human process of migration. Cross-community migration, the migration of humans across the boundaries of language and culture, is a consistent...

  12. Blurring Boundaries

    DEFF Research Database (Denmark)

    Neergaard, Ulla; Nielsen, Ruth

    2010-01-01

    This article builds on the results obtained in the so-called Blurring Boundaries project which was undertaken at the Law Department, Copenhagen Business School, in the period from 2007 to 2009. It looks at the sustainability of the Danish welfare state in an EU law context and on the integration...... of welfare functions into EU law both from an internal market law and a constitutional law perspective. The main problem areas covered by the Blurring Boundaries project were studied in sub-projects on: 1) Internal market law and welfare services; 2) Fundamental rights and non-discrimination law aspects......; and 3) Services of general interest. In the Blurring Boundaries project, three aspects of the European Social Model have been particularly highlighted: the constitutionalisation of the European Social Model, its multi-level legal character, and the clash between market access justice at EU level...

  13. A preference for migration

    OpenAIRE

    Stark, Oded

    2007-01-01

    At least to some extent migration behavior is the outcome of a preference for migration. The pattern of migration as an outcome of a preference for migration depends on two key factors: imitation technology and migration feasibility. We show that these factors jointly determine the outcome of a preference for migration and we provide examples that illustrate how the prevalence and transmission of a migration-forming preference yield distinct migration patterns. In particular, the imitation of...

  14. Towards realistic molecular dynamics simulations of grain boundary mobility

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, J., E-mail: zhou@imm.rwth-aachen.de [Institut fuer Metallkunde und Metallphysik, Rheinisch-Westfaelische Technische Hochschule (RWTH), Aachen (Germany); Mohles, V. [Institut fuer Metallkunde und Metallphysik, Rheinisch-Westfaelische Technische Hochschule (RWTH), Aachen (Germany)

    2011-09-15

    In order to investigate grain boundary migration by molecular dynamics (MD) simulations a new approach involving a crystal orientation-dependent driving force has been developed by imposing an appropriate driving force on grain boundary atoms and enlarging the effective range of driving force. The new approach has been validated by the work of the driving force associated with the motion of grain boundaries. With the new approach the relation between boundary migration velocity and driving force is found to be nonlinear, as was expected from rate theory for large driving forces applied in MD simulations. By evaluating grain boundary mobility nonlinearly for a set of symmetrical <1 1 1> tilt boundaries in aluminum at high temperature, high-angle grain boundaries were shown to move much faster than low-angle grain boundaries. This agrees well with experimental findings for recrystallization and grain growth. In comparison with the available data the simulated mobility of a 38.21{sup o{Sigma}}7 boundary was found to be significantly lower than other MD simulation results and comparable with the experimental values. Furthermore, the average volume involved during atomic jumps for boundary migration is determined in MD simulations for the first time. The large magnitude of the volume indicates that grain boundary migration is accomplished by the correlated motion of atom groups.

  15. Globalization, Migration and Development

    Directory of Open Access Journals (Sweden)

    George, Susan

    2002-01-01

    Full Text Available EnglishMigration may become the most important branch of demography in the earlydecades of the new millennium in a rapidly globalizing world. This paper discusses the causes, costsand benefits of international migration to countries of the South and North, and key issues of commonconcern. International migration is as old as national boundaries, though its nature, volume,direction, causes and consequences have changed. The causes of migration are rooted in the rate ofpopulation growth and the proportion of youth in the population, their education and training,employment opportunities, income differentials in society, communication and transportationfacilities, political freedom and human rights and level of urbanization. Migration benefits the Souththrough remittances of migrants, improves the economic welfare of the population (particularly womenof South countries generally, increases investment, and leads to structural changes in the economy.However, emigration from the South has costs too, be they social or caused by factors such as braindrain. The North also benefits by migration through enhancement of economic growth, development ofnatural resources, improved employment prospects, social development and through exposure toimmigrants' new cultures and lifestyles. Migration also has costs to the North such as of immigrantintegration, a certain amount of destabilization of the economy, illegal immigration, and socialproblems of discrimination and exploitation. Issues common to both North and South include impact onprivate investment, trade, international cooperation, and sustainable development. Both North andSouth face a dilemma in seeking an appropriate balance between importing South's labour or itsproducts and exporting capital and technology from the North.FrenchLa migration est sans doute devenue la partie la plus importante de la démographie des premières décennies du nouveau millénaire dans un monde qui change rapidement. Ce

  16. Albedo Boundary

    Science.gov (United States)

    2003-01-01

    MGS MOC Release No. MOC2-510, 11 October 2003The sharp, nearly straight line that runs diagonally across the center of this April 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image is an albedo boundary. Albedois a term that refers to reflectance of sunlight. A surface with a low albedo is one that appears dark because it reflects less light than a high albedo (bright) surface. On Mars, albedo boundaries occur between two materials of differing texture, particle size, or composition, or some combination of these three factors. The boundary shown here is remarkable because it is so sharp and straight. This is caused by wind. Most likely, the entire surface was once covered with the lower-albedo (darker) material that is now seen in the upper half of the image. At some later time, wind stripped away this darker material from the surfaces in the lower half of the image. The difference in albedo here might be related to composition, and possibly particle size. This picture is located near the southwest rim of Schiaparelli Basin at 5.5oS, 345.9oW. The picture covers an area 3 km (1.9 mi) wide and is illuminated by sunlight from the left.

  17. Boundary issues

    Science.gov (United States)

    Townsend, Alan R.; Porder, Stephen

    2011-03-01

    What is our point of no return? Caesar proclaimed 'the die is cast' while crossing the Rubicon, but rarely does modern society find so visible a threshold in our continued degradation of ecosystems and the services they provide. Humans have always used their surroundings to make a living— sometimes successfully, sometimes not (Diamond 2005)—and we intuitively know that there are boundaries to our exploitation. But defining these boundaries has been a challenge since Malthus first prophesied that nature would limit the human population (Malthus 1798). In 2009, Rockström and colleagues tried to quantify what the 6.8 billion (and counting) of us could continue to get away with, and what we couldn't (Rockström et al 2009). In selecting ten 'planetary boundaries', the authors contend that a sustainable human enterprise requires treating a number of environmental thresholds as points of no return. They suggest we breach these Rubicons at our own peril, and that we've already crossed three: biodiversity loss, atmospheric CO2, and disruption of the global nitrogen (N) cycle. As they clearly hoped, the very act of setting targets has provoked scientific inquiry about their accuracy, and about the value of hard targets in the first place (Schlesinger 2009). Such debate is a good thing. Despite recent emphasis on the science of human-ecosystem interactions, understanding of our planetary boundaries is still in its infancy, and controversy can speed scientific progress (Engelhardt and Caplan 1987). A few weeks ago in this journal, Carpenter and Bennett (2011) took aim at one of the more controversial boundaries in the Rockström analysis: that for human alteration of the global phosphorus (P) cycle. Rockström's group chose riverine P export as the key indicator, suggesting that humans should not exceed a value that could trigger widespread marine anoxic events—and asserting that we have not yet crossed this threshold. There are defensible reasons for a marine

  18. boundary dissipation

    Directory of Open Access Journals (Sweden)

    Mehmet Camurdan

    1998-01-01

    are coupled by appropriate trace operators. This overall model differs from those previously studied in the literature in that the elastic chamber floor is here more realistically modeled by a hyperbolic Kirchoff equation, rather than by a parabolic Euler-Bernoulli equation with Kelvin-Voight structural damping, as in past literature. Thus, the hyperbolic/parabolic coupled system of past literature is replaced here by a hyperbolic/hyperbolic coupled model. The main result of this paper is a uniform stabilization of the coupled PDE system by a (physically appealing boundary dissipation.

  19. [Rural migration in Poland].

    Science.gov (United States)

    Rakowski, W

    1985-01-01

    Migration of the rural population in Poland from 1946 to 1983 is analyzed, with a focus on rural-urban migration. Consideration is given to regional variations in migration patterns, the causes of migration, and the impact of migration on areas of origin.

  20. Characterization of boundary roughness of two cube grains in partly recrystallized copper

    DEFF Research Database (Denmark)

    Sun, Jun; Zhang, Yubin; Dahl, Anders Bjorholm

    2015-01-01

    Protrusions and retrusions typically form on recrystallizing boundaries and thus the boundaries often appear rough. Characterization of the boundary roughness is necessary in order to evaluate the effects of protrusions and retrusions on boundary migration. In the current work, a variable termed ...

  1. Migration of birds

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report covers the migration of birds. Topics covered include why birds migrate, when birds migrate, speed, altitude, courses, distance, major flyways and...

  2. Breaking Boundaries

    DEFF Research Database (Denmark)

    produce desperate attempts to maintain old or create new differences. Political and sociological research into these complex processes has been mainly guided by structural and normative concerns. Faced with growing evidence about the instability of world order and domestic social structures alike, policy....... As a fundamental human experience, liminality transmits cultural practices, codes, rituals, and meanings in-between aggregate structures and uncertain outcomes. As a methodological tool it is well placed to overcome disciplinary boundaries, which often direct attention to specific structures or sectors of society....... Its capacity to provide explanatory accounts of seemingly unstructured situations provides an opportunity to link experience-based and culture-oriented approaches not only to contemporary problems but also to undertake comparisons across historical periods. From a perspective of liminality...

  3. Effects of boundary characteristics on resistance to temper embrittlement and segregation behavior of Ni-Cr-Mo low alloy steel

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sang-Gyu; Lee, Ki-Hyoung [Nuclear Materials Research Division, Korea Atomic Energy Research Institute, Daedeok-daero 989-111, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Kim, Min-Chul, E-mail: mckim@kaeri.re.kr [Nuclear Materials Research Division, Korea Atomic Energy Research Institute, Daedeok-daero 989-111, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Lee, Bong-Sang [Nuclear Materials Research Division, Korea Atomic Energy Research Institute, Daedeok-daero 989-111, Yuseong-gu, Daejeon 305-353 (Korea, Republic of)

    2013-01-20

    SA508 Gr.4N Ni-Cr-Mo low alloy steel has higher strength and fracture toughness than those of commercial SA508 Gr.3 low alloy steel, due to its tempered martensitic microstructure as well as the solid solution effect and its higher contents of Ni and Cr. Hence, several studies have been performed on SA508 Gr.4N for nuclear application. In this study, the effects of microstructure on temper embrittlement and segregation behaviors in Ni-Cr-Mo low alloy steel were evaluated from the viewpoint of grain boundary characteristics. To evaluate the microstructural effect while excluding chemistry effects, the same heat was used but different microstructure samples were prepared by changing the cooling rate after austenitization. The increased volume fraction of martensite reduces the resistance to temper embrittlement, showing an increased transition-temperature shift (TTS) and increased P segregation at prior austenite boundaries. The segregation occurred intensively at prior austenite grain boundaries in tempered martensite, while the segregation occurred simultaneously at both prior austenite boundaries and packet boundaries in tempered bainite. In the EBSD results, most of the packet boundaries in tempered martensite are special boundaries such as N-Ary-Summation 3 coincident site lattice (CSL) boundaries. The differences in P segregation between tempered martensite and tempered bainite are mainly caused by different portions of low energy special boundaries among the sub-grain boundaries. The reduction of temper embrittlement resistance in tempered martensite could be explained by the increased fraction of low energy CSL boundaries, which leads to a concentrated segregation of P at prior austenite grain boundaries.

  4. Technology for Boundaries

    DEFF Research Database (Denmark)

    Bødker, Susanne; Kristensen, Jannie Friis; Nielsen, Christina

    2003-01-01

    This paper presents a study of an organisation, which is undergoing a process transforming organisational and technological boundaries. In particular, we shall look at three kinds of boundaries: the work to maintain and change the boundary between the organisation and its customers; boundaries.......After analysing the history and the current boundary work, the paper will propose new technological support for boundary work. In particular the paper will suggest means of supporting boundaries when these are productive and for changing boundaries when this seems more appropriate. In total, flexible technologies...... seem a core issue when dealing with technology for boundaries....

  5. Internal microstructure observation of enhanced grain-boundary sliding at room temperature in AZ31 magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Ando, D., E-mail: daisuke.ando.c4@tohoku.ac.jp; Sutou, Y.; Koike, J.

    2016-06-01

    The origin of grain boundary sliding (GBS) is known to be slip-induced due to plastic incompatibility near the grain boundary at room temperature. In this study, the relationship between GBS and crystal orientation was investigated in AZ31 Mg alloy rolled sheets at room temperature. The GBS tendency was determined as related to basal dislocation slip where the GBS boundaries were generally located between the grains with respectively high and low or high and high Schmid factors for basal slip. The results indicate that GBS is attributed to the plastic incompatibility caused by anisotropic basal and prismatic slip. Furthermore, GBS was located in regions with localized deformation near grain boundaries. Cross-sectional focused ion beam/transmission electron microscopy (FIB/TEM) observations of these regions revealed seriately arranged subgrains adjacent to a grain boundary. Therefore, we propose that RT-GBS in AZ31 can be caused by localized crystal rotation due to dynamic recover and recrystallization by stress concentration near the grain boundary but not ordinary GBS.

  6. Malaysia and forced migration

    National Research Council Canada - National Science Library

    Arzura Idris

    2012-01-01

    This paper analyzes the phenomenon of "forced migration" in Malaysia. It examines the nature of forced migration, the challenges faced by Malaysia, the policy responses and their impact on the country and upon the forced migrants...

  7. Migration and revolution

    Directory of Open Access Journals (Sweden)

    Nando Sigona

    2012-06-01

    Full Text Available The Arab Spring has not radically transformed migration patterns in the Mediterranean, and the label ‘migration crisis’ does not do justice to the composite and stratified reality.

  8. Essays on temporary migration

    OpenAIRE

    Mestres Domenech, J.

    2012-01-01

    My thesis dissertation focuses on the temporariness of migration, its diverse effects as well as on migration selection. The first paper, A Dynamic Model of Return Migration analyzes the decision process underlying return migration using a dynamic model. We explain how migrants decide whether to stay or to go back to their home country together with their savings and consumption decisions. We simulate our model with return intentions and perform policy simulations. The se...

  9. Irregular Migration of Egyptians

    OpenAIRE

    ROMAN, Howaida

    2008-01-01

    Euro-Mediterranean Consortium for Applied Research on International Migration (CARIM) After defining irregular migration and tackling its different dimensions, the analytical note proposes to analyse the causes and dynamics of irregular migration in Egypt. It highlights furthermore the determinants of EU Policies in the realm of irregular migration, and Egypt’s policy-making approach towards irregular migrants. The conclusion emphasizes the necessity of forging coherent and effective polic...

  10. Impact of consolidation pressure on contaminant migration in clay liner

    Directory of Open Access Journals (Sweden)

    Zhi-hong Zhang

    2013-07-01

    Full Text Available Consolidation deformation occurs in clay liners under the self-weight of wastes at a simple garbage dump or dredged sediment dump, which leads to a decrease in the porosity. However, the migration of contaminants in clay liners is influenced by the porosity. Thus, the impact of consolidation deformation of clay liners on the migration of contaminants cannot be ignored. Based on Biot's consolidation theory, the contaminant migration theory, and consideration of the three kinds of migration mechanisms of convection, diffusion, and adsorption, a one-dimensional migration model of contaminants in deforming porous media was established, and the finite difference method was adopted to obtain the numerical solutions for an established initial-boundary value problem. The impact of consolidation pressure on the migration law of a contaminant was studied. The results show that, regardless of adsorption modes, different consolidation pressures have similar impacts on the migration law of the contaminant. Namely, over a certain migration time, the greater the consolidation pressure is, the smaller the migration depth of the contaminant. The results also show that, while the migration time increases, the impact of a certain increment of consolidation pressure on the variation of contaminant concentration with the depth increases gradually and, while the migration depth increases, the impact of a certain increment of consolidation pressure on the variation of the contaminant concentration with time increases gradually.

  11. More Myths of Migration.

    Science.gov (United States)

    Basch, Linda; Lerner, Gail

    1986-01-01

    Challenges "myths" about women and migration, including (1) the causes of migration are economic, not racism; (2) migrant women receive support from feminist groups and trade unions; (3) transnational corporations are positive forces in developing nations; (4) migration today has little impact on family life; and (5) most migrants cluster in…

  12. Incentives and disincentives: international migration.

    Science.gov (United States)

    Bhagwati, J N

    1984-01-01

    International migration is largely controlled by disincentives, or quotas, on immigration rather than checks on emigrations. Societies generally feel they have a right to exclude others from their boundaries, but they also usually feel that they do not have a right to control emigration. The single-planetary approach holds that people have the right to live wherever they like on the planet, and the cosmopolitan-utilitarian approach believes the same for reasons of world efficiency. The current feeling that societies have the right to exclude others may be explained best by territoriality in human animals. People also believe that their culture will be diluted if too many outsiders enter. In many cases, immigration systems cannot really control immigration, as in the cases of long landlocked borders between the US and Mexico and between Bangladesh and Assam. Immigration systems also contain legal loopholes. For example, in the US it is easier to get a student visa and convert to immigrant status than to gain immigrant status directly. Loopholes lead to plugs, which lead in turn to more loopholes. An upsurge in requests for political asylum followed increased restrictions on immigration in Western Europe. The US has investigated foreign aid and foreign investments to Mexico and Haiti to curb the flow of illegal migrants. The author suggests that foreign investments may lead to more migration because of the creation of a new proletariat used to the ways of developed countries. An estimate of what would happen if all immigration control were removed worldwide concludes that efficiency and income distribution would improve worldwide. Most migration from developing to developed countries currently consists of the migration of skilled professionals, the brain drain. The author proposes a tax on these professionals to be paid to the country of origin to compensate them for the loss in education and training. The author summarizes the differences between the West German

  13. Pushing the pace of tree species migration.

    Directory of Open Access Journals (Sweden)

    Eli D Lazarus

    Full Text Available Plants and animals have responded to past climate changes by migrating with habitable environments, sometimes shifting the boundaries of their geographic ranges by tens of kilometers per year or more. Species migrating in response to present climate conditions, however, must contend with landscapes fragmented by anthropogenic disturbance. We consider this problem in the context of wind-dispersed tree species. Mechanisms of long-distance seed dispersal make these species capable of rapid migration rates. Models of species-front migration suggest that even tree species with the capacity for long-distance dispersal will be unable to keep pace with future spatial changes in temperature gradients, exclusive of habitat fragmentation effects. Here we present a numerical model that captures the salient dynamics of migration by long-distance dispersal for a generic tree species. We then use the model to explore the possible effects of assisted colonization within a fragmented landscape under a simulated tree-planting scheme. Our results suggest that an assisted-colonization program could accelerate species-front migration rates enough to match the speed of climate change, but such a program would involve an environmental-sustainability intervention at a massive scale.

  14. Pushing the pace of tree species migration.

    Science.gov (United States)

    Lazarus, Eli D; McGill, Brian J

    2014-01-01

    Plants and animals have responded to past climate changes by migrating with habitable environments, sometimes shifting the boundaries of their geographic ranges by tens of kilometers per year or more. Species migrating in response to present climate conditions, however, must contend with landscapes fragmented by anthropogenic disturbance. We consider this problem in the context of wind-dispersed tree species. Mechanisms of long-distance seed dispersal make these species capable of rapid migration rates. Models of species-front migration suggest that even tree species with the capacity for long-distance dispersal will be unable to keep pace with future spatial changes in temperature gradients, exclusive of habitat fragmentation effects. Here we present a numerical model that captures the salient dynamics of migration by long-distance dispersal for a generic tree species. We then use the model to explore the possible effects of assisted colonization within a fragmented landscape under a simulated tree-planting scheme. Our results suggest that an assisted-colonization program could accelerate species-front migration rates enough to match the speed of climate change, but such a program would involve an environmental-sustainability intervention at a massive scale.

  15. Predicting bison migration out of Yellowstone National Park using bayesian models.

    Directory of Open Access Journals (Sweden)

    Chris Geremia

    Full Text Available Long distance migrations by ungulate species often surpass the boundaries of preservation areas where conflicts with various publics lead to management actions that can threaten populations. We chose the partially migratory bison (Bison bison population in Yellowstone National Park as an example of integrating science into management policies to better conserve migratory ungulates. Approximately 60% of these bison have been exposed to bovine brucellosis and thousands of migrants exiting the park boundary have been culled during the past two decades to reduce the risk of disease transmission to cattle. Data were assimilated using models representing competing hypotheses of bison migration during 1990-2009 in a hierarchal bayesian framework. Migration differed at the scale of herds, but a single unifying logistic model was useful for predicting migrations by both herds. Migration beyond the northern park boundary was affected by herd size, accumulated snow water equivalent, and aboveground dried biomass. Migration beyond the western park boundary was less influenced by these predictors and process model performance suggested an important control on recent migrations was excluded. Simulations of migrations over the next decade suggest that allowing increased numbers of bison beyond park boundaries during severe climate conditions may be the only means of avoiding episodic, large-scale reductions to the Yellowstone bison population in the foreseeable future. This research is an example of how long distance migration dynamics can be incorporated into improved management policies.

  16. Predicting bison migration out of Yellowstone National Park using bayesian models.

    Science.gov (United States)

    Geremia, Chris; White, P J; Wallen, Rick L; Watson, Fred G R; Treanor, John J; Borkowski, John; Potter, Christopher S; Crabtree, Robert L

    2011-02-14

    Long distance migrations by ungulate species often surpass the boundaries of preservation areas where conflicts with various publics lead to management actions that can threaten populations. We chose the partially migratory bison (Bison bison) population in Yellowstone National Park as an example of integrating science into management policies to better conserve migratory ungulates. Approximately 60% of these bison have been exposed to bovine brucellosis and thousands of migrants exiting the park boundary have been culled during the past two decades to reduce the risk of disease transmission to cattle. Data were assimilated using models representing competing hypotheses of bison migration during 1990-2009 in a hierarchal bayesian framework. Migration differed at the scale of herds, but a single unifying logistic model was useful for predicting migrations by both herds. Migration beyond the northern park boundary was affected by herd size, accumulated snow water equivalent, and aboveground dried biomass. Migration beyond the western park boundary was less influenced by these predictors and process model performance suggested an important control on recent migrations was excluded. Simulations of migrations over the next decade suggest that allowing increased numbers of bison beyond park boundaries during severe climate conditions may be the only means of avoiding episodic, large-scale reductions to the Yellowstone bison population in the foreseeable future. This research is an example of how long distance migration dynamics can be incorporated into improved management policies.

  17. Grain boundaries: Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Balluffi, R.W.; Bristowe, P.D.

    1988-02-01

    Quantitative measurements of grain boundary structure factors using x-ray diffraction have been performed on low angle (001) twist boundaries in gold. Also, a computer atomistic simulation program is being implemented to examine the equilibrium properties of a series of boundaries in gold. Simulation of boundaries at room temperature have been performed. Electron microscopy of grain boundary melting in aluminum was also performed. Results indicated an absence of melting. (CBS)

  18. Tectonics of oblique plate boundary systems

    Science.gov (United States)

    Díaz-Azpiroz, Manuel; Brune, Sascha; Leever, Karen A.; Fernández, Carlos; Czeck, Dyanna M.

    2016-12-01

    The relative displacement between lithospheric plates normally results in obliquely deforming plate boundaries. This is simply caused by the fact that, on plate tectonics basis, irregularly shaped plate boundaries are rarely perpendicular or parallel to small-circle rotation paths, which describe plate motion on a sphere (Fig. 1a). Global current relative plate motions estimated from geological data (DeMets et al., 2010; Argus et al., 2011) and GPS measurements (e.g., Kreemer et al., 2003; Argus et al., 2010) provide insight to the prevalent degrees of obliquity on Earth's surface. Based on these global data sets, Philippon and Corti (2016), statistically show that current orthogonal boundaries (obliquity angle smaller than 10°) represent around 8% of the total boundary length whereas strike-slip boundaries (obliquity angle larger than 80°) are encountered in plate boundaries present oblique relative motions. Furthermore, changes in plate kinematics leading to migration or jumps in the rotation poles necessarily cause obliquity along former pure strike-slip or convergent/divergent boundaries (Fig. 1b).

  19. NASTRAN migration to UNIX

    Science.gov (United States)

    Chan, Gordon C.; Turner, Horace Q.

    1990-01-01

    COSMIC/NASTRAN, as it is supported and maintained by COSMIC, runs on four main-frame computers - CDC, VAX, IBM and UNIVAC. COSMIC/NASTRAN on other computers, such as CRAY, AMDAHL, PRIME, CONVEX, etc., is available commercially from a number of third party organizations. All these computers, with their own one-of-a-kind operating systems, make NASTRAN machine dependent. The job control language (JCL), the file management, and the program execution procedure of these computers are vastly different, although 95 percent of NASTRAN source code was written in standard ANSI FORTRAN 77. The advantage of the UNIX operating system is that it has no machine boundary. UNIX is becoming widely used in many workstations, mini's, super-PC's, and even some main-frame computers. NASTRAN for the UNIX operating system is definitely the way to go in the future, and makes NASTRAN available to a host of computers, big and small. Since 1985, many NASTRAN improvements and enhancements were made to conform to the ANSI FORTRAN 77 standards. A major UNIX migration effort was incorporated into COSMIC NASTRAN 1990 release. As a pioneer work for the UNIX environment, a version of COSMIC 89 NASTRAN was officially released in October 1989 for DEC ULTRIX VAXstation 3100 (with VMS extensions). A COSMIC 90 NASTRAN version for DEC ULTRIX DECstation 3100 (with RISC) is planned for April 1990 release. Both workstations are UNIX based computers. The COSMIC 90 NASTRAN will be made available on a TK50 tape for the DEC ULTRIX workstations. Previously in 1988, an 88 NASTRAN version was tested successfully on a SiliconGraphics workstation.

  20. Comparison of artificial absorbing boundaries for acoustic wave equation modelling

    Science.gov (United States)

    Gao, Yingjie; Song, Hanjie; Zhang, Jinhai; Yao, Zhenxing

    2017-12-01

    Absorbing boundary conditions are necessary in numerical simulation for reducing the artificial reflections from model boundaries. In this paper, we overview the most important and typical absorbing boundary conditions developed throughout history. We first derive the wave equations of similar methods in unified forms; then, we compare their absorbing performance via theoretical analyses and numerical experiments. The Higdon boundary condition is shown to be the best one among the three main absorbing boundary conditions that are based on a one-way wave equation. The Clayton and Engquist boundary is a special case of the Higdon boundary but has difficulty in dealing with the corner points in implementaion. The Reynolds boundary does not have this problem but its absorbing performance is the poorest among these three methods. The sponge boundary has difficulties in determining the optimal parameters in advance and too many layers are required to achieve a good enough absorbing performance. The hybrid absorbing boundary condition (hybrid ABC) has a better absorbing performance than the Higdon boundary does; however, it is still less efficient for absorbing nearly grazing waves since it is based on the one-way wave equation. In contrast, the perfectly matched layer (PML) can perform much better using a few layers. For example, the 10-layer PML would perform well for absorbing most reflected waves except the nearly grazing incident waves. The 20-layer PML is suggested for most practical applications. For nearly grazing incident waves, convolutional PML shows superiority over the PML when the source is close to the boundary for large-scale models. The Higdon boundary and hybrid ABC are preferred when the computational cost is high and high-level absorbing performance is not required, such as migration and migration velocity analyses, since they are not as sensitive to the amplitude errors as the full waveform inversion.

  1. Dialogues on migration policy

    OpenAIRE

    Giugni, Marco; Passy, Florence

    2006-01-01

    Dialogues on Migration Policy brings together leading American and European scholars of immigration politics to address migration policy. Editors Marco Giugni and Florence Passy's aim to present a number of informed "dialogues" addressing three main theoretical concerns in this field: the role of the national state in a globalizing world, the determinants of policy change, and the role of collective interests in migration policy. Adopting an unconventional format, the novelty of Dialogues on ...

  2. Many Faces of Migrations

    OpenAIRE

    Milica Antić Gaber; Marko Krevs

    2013-01-01

    Temporary or permanent, local or international, voluntary or forced, legal or illegal, registered or unregistered migrations of individuals, whole communities or individual groups are an important factor in constructing and modifying (modern) societies. The extent of international migrations is truly immense. At the time of the preparation of this publication more than 200 million people have been involved in migrations in a single year according to the United Nations. Furthermore, three time...

  3. State Agency Administrative Boundaries

    Data.gov (United States)

    Kansas Data Access and Support Center — This database comprises 28 State agency boundaries and point of contact. The Kansas Geological Survey collected legal descriptions of the boundaries for various...

  4. Allegheny County Municipal Boundaries

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset demarcates the municipal boundaries in Allegheny County. Data was created to portray the boundaries of the 130 Municipalities in Allegheny County the...

  5. HUD GIS Boundary Files

    Data.gov (United States)

    Department of Housing and Urban Development — The HUD GIS Boundary Files are intended to supplement boundary files available from the U.S. Census Bureau. The files are for community planners interested in...

  6. Political State Boundary (National)

    Data.gov (United States)

    Department of Transportation — State boundaries with political limit - boundaries extending into the ocean (NTAD). The TIGER/Line Files are shapefiles and related database files (.dbf) that are an...

  7. Regional Redistribution and Migration

    DEFF Research Database (Denmark)

    Manasse, Paolo; Schultz, Christian

    We study a model with free migration between a rich and a poor region. Since there is congestion, the rich region has an incentive to give the poor region a transfer in order to reduce immigration. Faced with free migration, the rich region voluntarily chooses a transfer, which turns out...... to be equal to that a social planner would choose. Provided migration occurs in equilibrium, this conclusion holds even in the presence of moderate mobility costs. However, large migration costs will lead to suboptimal transfers in the market solution...

  8. Migration and Its Consequences

    OpenAIRE

    Ivan Vasile Ivanoff

    2017-01-01

    ABSTRACT: Migration, as a social phenomenon, has an especially complex character and can be analyzed from the point of view of the state which is the source of the migration as well as from the point of view of the state which is the destination of the migration. Its causes are especially complex but the economic ones are determinant and are fundamentally different of the causes which determine the population to seek refuge in case of armed conflict. The effects of the migration are equally c...

  9. Migration into art

    DEFF Research Database (Denmark)

    Petersen, Anne Ring

    This book addresses a topic of increasing importance to artists, art historians and scholars of cultural studies, migration studies and international relations: migration as a profoundly transforming force that has remodelled artistic and art institutional practices across the world. It explores...... contemporary art's critical engagement with migration and globalisation as a key source for improving our understanding of how these processes transform identities, cultures, institutions and geopolitics. The author explores three interwoven issues of enduring interest: identity and belonging, institutional...... visibility and recognition of migrant artists, and the interrelations between aesthetics and politics, including the balancing of aesthetics, politics and ethics in representations of forced migration....

  10. Atomistic simulation of dislocation emission in nanosized grain boundaries

    Science.gov (United States)

    Derlet, P. M.; van Swygenhoven, H.; Hasnaoui, A.

    2003-11-01

    The present work deals with the atomic mechanism responsible for the emission of partial dislocations from grain boundaries (GB) in nanocrystalline metals. It is shown that, in a 12 nm grain-size sample, GBs containing grain-boundary dislocations (GBDs) can emit a partial dislocation during deformation by local atomic shuffling and stress-assisted free-volume migration. As in previous work, the nucleation occurs at a GBD, which, upon nucleation and propagation, is removed. In the present case, free-volume migration occurs away from the nucleation region both before and after the nucleation event.

  11. Movement ecology of migration in turkey vultures

    Science.gov (United States)

    Mandel, J. T.; Bildstein, K. L.; Bohrer, G.; Winkler, D. W.

    2008-01-01

    We develop individual-based movement ecology models (MEM) to explore turkey vulture (Cathartes aura) migration decisions at both hourly and daily scales. Vulture movements in 10 migration events were recorded with satellite-reporting GPS sensors, and flight behavior was observed visually, aided by on-the-ground VHF radio-tracking. We used the North American Regional Reanalysis dataset to obtain values for wind speed, turbulent kinetic energy (TKE), and cloud height and used a digital elevation model for a measure of terrain ruggedness. A turkey vulture fitted with a heart-rate logger during 124 h of flight during 38 contiguous days showed only a small increase in mean heart rate as distance traveled per day increased, which suggests that, unlike flapping, soaring flight does not lead to greatly increased metabolic costs. Data from 10 migrations for 724 hourly segments and 152 daily segments showed that vultures depended heavily upon high levels of TKE in the atmospheric boundary layer to increase flight distances and maintain preferred bearings at both hourly and daily scales. We suggest how the MEM can be extended to other spatial and temporal scales of avian migration. Our success in relating model-derived atmospheric variables to migration indicates the potential of using regional reanalysis data, as here, and potentially other regional, higher-resolution, atmospheric models in predicting changing movement patterns of soaring birds under various scenarios of climate and land use change. PMID:19060195

  12. Movement ecology of migration in turkey vultures.

    Science.gov (United States)

    Mandel, J T; Bildstein, K L; Bohrer, G; Winkler, D W

    2008-12-09

    We develop individual-based movement ecology models (MEM) to explore turkey vulture (Cathartes aura) migration decisions at both hourly and daily scales. Vulture movements in 10 migration events were recorded with satellite-reporting GPS sensors, and flight behavior was observed visually, aided by on-the-ground VHF radio-tracking. We used the North American Regional Reanalysis dataset to obtain values for wind speed, turbulent kinetic energy (TKE), and cloud height and used a digital elevation model for a measure of terrain ruggedness. A turkey vulture fitted with a heart-rate logger during 124 h of flight during 38 contiguous days showed only a small increase in mean heart rate as distance traveled per day increased, which suggests that, unlike flapping, soaring flight does not lead to greatly increased metabolic costs. Data from 10 migrations for 724 hourly segments and 152 daily segments showed that vultures depended heavily upon high levels of TKE in the atmospheric boundary layer to increase flight distances and maintain preferred bearings at both hourly and daily scales. We suggest how the MEM can be extended to other spatial and temporal scales of avian migration. Our success in relating model-derived atmospheric variables to migration indicates the potential of using regional reanalysis data, as here, and potentially other regional, higher-resolution, atmospheric models in predicting changing movement patterns of soaring birds under various scenarios of climate and land use change.

  13. Evidence for Vacancy Mechanism in Grain Boundary Diffusion in bcc Iron: A Molecular-Dynamics Study

    Science.gov (United States)

    Kwok, Thomas; Ho, P. S.; Yip, Sidney; Balluffi, R. W.; Bristowe, P. D.; Brokman, A.

    1981-10-01

    The dominance of vacancy migration in grain boundary self-diffusion has been established by molecular-dynamics simulation of a bcc iron Σ=5 tilt boundary. The data yielded a reasonable value of the activation energy for migration and showed that the jump processes are highly structure dependent. The use of a temperature-dependent transition-probability matrix to describe the diffusion of the vacancies in the grain boundary is suggested. Formation of one type of boundary interstitial was observed, and the interstitial was found to be immobile during its lifetime.

  14. Migrating Art History

    DEFF Research Database (Denmark)

    Ørum, Tania

    2012-01-01

    Review of Hiroko Ikegami, The Great Migrator. Robert Rauschenberg and the Global Rise of American Art. Cambridge Mass., The MIT Press, 2010. 277 pages. ISBN 978-0-262-01425-0.......Review of Hiroko Ikegami, The Great Migrator. Robert Rauschenberg and the Global Rise of American Art. Cambridge Mass., The MIT Press, 2010. 277 pages. ISBN 978-0-262-01425-0....

  15. Migration in Burkina Faso

    NARCIS (Netherlands)

    Wouterse, F.S.

    2007-01-01

    Migration plays an important role in development and as a strategy for poverty reduction. A recent World Bank investigation finds a significant positive relationship between international migration and poverty reduction at the country level (Adams and Page 2003). Burkina Faso, whose conditions for

  16. Geography of European Migration

    Directory of Open Access Journals (Sweden)

    Zhitin Dmitry V.

    2016-08-01

    Full Text Available In recent decades, the role of international migration has increased dramatically in most European countries. The growth in migration has made some authors proclaim the beginning of a second Migration Period that could transform the social and cultural identity of Europe. The article presents an analysis of international migration geography in Europe in the last twenty-five years. The authors identify the main trends in migration, provide migration profiles of European countries, and propose a classification based on the recent changes in the migrant stock. Changes in the migrant stock (total emigration and immigration reflect the level of involvement in international and global processes. They can serve as an indicator of a country’s attractiveness for both foreigners and the country’s citizens. The study shows that European countries are increasingly split into ‘immigrant’ and ‘emigrant’ states. The authors describe spatial patterns of migration. The volume and localisation of migration flows in Europe are affected not only by cultural and historical circumstance, such as a colonial past or a common language. The scale of immigrant influx often does not depend on a donor country’s demographic potential or the level of its socio-economic development. The links between the place of origin and destination are often more complex than it might initially seem. The authors stress the importance of a differentiated immigration policy taking into account ethnic and cultural features of host societies.

  17. Migration, Narration, Identity

    DEFF Research Database (Denmark)

    Leese, Peter

    (co-editor with Carly McLaughlin and Wladyslaw Witalisz) This book presents articles resulting from joint research on the representations of migration conducted in connection with the Erasmus Intensive Programme entitled «Migration and Narration» taught to groups of international students over...

  18. The Globalisation of migration

    Directory of Open Access Journals (Sweden)

    Milan Mesić

    2002-04-01

    Full Text Available The paper demonstrates that contemporary international migration is a constitutive part of the globalisation process. After defining the concepts of globalisation and the globalisation of migration, the author discusses six key themes, linking globalisation and international migration (“global cities”, the scale of migration; diversification of migration flows; globalisation of science and education; international migration and citizenship; emigrant communities and new identities. First, in accordance with Saskia Sassen’s analysis, the author rejects the wide-spread notion that unqualified migrants have lost an (important role in »global cities«, i.e. in the centres of the new (global economy. Namely, the post-modern service sector cannot function without the support of a wide range of auxiliary unqualified workers. Second, a critical comparison with traditional overseas mass migration to the USA at the turn of the 19th and 20th centuries indicates that present international migration is, perhaps, less extensive – however it is important to take into consideration various limitations that previously did not exist, and thus the present migration potential is in really greater. Third, globalisation is more evident in a diversification of the forms of migration: the source area of migrants to the New World and Europe has expanded to include new regions in the world; new immigration areas have arisen (the Middle East, new industrial countries of the Far East, South Europe; intra-regional migration has intensified. Forth, globalisation is linked to an increased migration of experts and the pessimistic notion of a brain drain has been replaced by the optimistic idea of a brain gain. Fifth, contemporary international migration has been associated with a crisis of the national model of citizenship. Sixth, the interlinking of (migrant cultural communities regardless of distance and the physical proximity of cultural centres (the

  19. Migration and Environmental Hazards

    Science.gov (United States)

    Hunter, Lori M.

    2011-01-01

    Losses due to natural hazards (e.g., earthquakes, hurricanes) and technological hazards (e.g., nuclear waste facilities, chemical spills) are both on the rise. One response to hazard-related losses is migration, with this paper offering a review of research examining the association between migration and environmental hazards. Using examples from both developed and developing regional contexts, the overview demonstrates that the association between migration and environmental hazards varies by setting, hazard types, and household characteristics. In many cases, however, results demonstrate that environmental factors play a role in shaping migration decisions, particularly among those most vulnerable. Research also suggests that risk perception acts as a mediating factor. Classic migration theory is reviewed to offer a foundation for examination of these associations. PMID:21886366

  20. Migration of health workers.

    Science.gov (United States)

    Buchan, James

    2008-01-01

    The discussion and debate stimulated by these papers focused across a range of issues but there were four main areas of questioning: "measuring" and monitoring migration (issues related to comparability, completeness and accuracy of data sets on human resources); the impact of migration of health workers on health systems; the motivations of individual health workers to migrate (the "push" and "pull" factors) and the effect of policies designed either to reduce migration (e.g "self ufficiency") or to stimulate it (e.g active international recruitment). It was recognised that there was a critical need to examine migratory flows within the broader context of all health care labour market dynamics within a country, that increasing migration of health workers was an inevitable consequence of globalisation, and that there was a critical need to improve monitoring so as to better inform policy formulation and policy testing in this area.

  1. European migration: Push and pull

    National Research Council Canada - National Science Library

    Zimmermann, Klaus F

    1994-01-01

      In recent decades, Europe has experienced periods of push and pull migration. Whereas pull migration has been seen as economically beneficial, there is concern that push migration will accelerate the employment crisis...

  2. Diel Migrations of Microorganisms within a Benthic, Hypersaline Mat Community.

    Science.gov (United States)

    Garcia-Pichel, F; Mechling, M; Castenholz, R W

    1994-05-01

    We studied the diel migrations of several species of microorganisms in a hypersaline, layered microbial mat. The migrations were quantified by repeated coring of the mat with glass capillary tubes. The resulting minicores were microscopically analyzed by using bright-field and epifluorescence (visible and infrared) microscopy to determine depths of coherent layers and were later dissected to determine direct microscopic counts of microorganisms. Microelectrode measurements of oxygen concentration, fiber optic microprobe measurements of light penetration within the mat, and incident irradiance measurements accompanied the minicore sampling. In addition, pigment content, photosynthesis and irradiance responses, the capacity for anoxygenic photosynthesis, and gliding speeds were determined for the migrating cyanobacteria. Heavily pigmented Oscillatoria sp. and Spirulina cf. subsalsa migrated downward into the mat during the early morning and remained deep until dusk, when upward migration occurred. The mean depth of the migration (not more than 0.4 to 0.5 mm) was directly correlated with the incident irradiance over the mat surface. We estimated that light intensity at the upper boundary of the migrating cyanobacteria was attenuated to such an extent that photoinhibition was effectively avoided but that intensities which saturated photosynthesis were maintained through most of the daylight hours. Light was a cue of paramount importance in triggering and modulating the migration of the cyanobacteria, even though the migrating phenomenon could not be explained solely in terms of a light response. We failed to detect diel migration patterns for other cyanobacterial species and filamentous anoxyphotobacteria. The sulfide-oxidizing bacterium Beggiatoa sp. migrated as a band that followed low oxygen concentrations within the mat during daylight hours. During the nighttime, part of this population migrated toward the mat surface, but a significant proportion remained deep.

  3. Migration and AIDS.

    Science.gov (United States)

    1998-01-01

    This article presents the perspectives of UNAIDS and the International Organization for Migration (IOM) on migration and HIV/AIDS. It identifies research and action priorities and policy issues, and describes the current situation in major regions of the world. Migration is a process. Movement is enhanced by air transport, rising international trade, deregulation of trade practices, and opening of borders. Movements are restricted by laws and statutes. Denial to freely circulate and obtain asylum is associated with vulnerability to HIV infections. A UNAIDS policy paper in 1997 and IOM policy guidelines in 1988 affirm that refugees and asylum seekers should not be targeted for special measures due to HIV/AIDS. There is an urgent need to provide primary health services for migrants, voluntary counseling and testing, and more favorable conditions. Research is needed on the role of migration in the spread of HIV, the extent of migration, availability of health services, and options for HIV prevention. Research must be action-oriented and focused on vulnerability to HIV and risk taking behavior. There is substantial mobility in West and Central Africa, economic migration in South Africa, and nonvoluntary migration in Angola. Sex workers in southeast Asia contribute to the spread. The breakup of the USSR led to population shifts. Migrants in Central America and Mexico move north to the US where HIV prevalence is higher.

  4. Migration of the population.

    Science.gov (United States)

    Krasinets, E

    1998-03-01

    Two factors influence foreign migration balance of the Russian Federation. The first factor involves the migration process between Russia and former union republics. The influx of population to the Russian Federation from other republics of the former Soviet Union is considered as one of the largest in the world. The average annual migratory growth of Russia during the years 1991-94 as a result of this migration exchange has tripled as compared with 1986-90, with a total of 2.7 million Russians who migrated into Russia. However, from 1996 up to the present time, the number of persons arriving in Russia declined dramatically. Meanwhile, the second factor that determines the country's migration balance is emigration to the far abroad. The most significant trend in determining the development of internal migration in Russia is the outflow of population from northern and eastern regions. The directions of internal and external migratory flows have a large influence on the migration balance in Russia's rural areas. The reduction of migratory flows in rural areas is the direct result of processes in the economic sphere. It confirms the reconstruction of rural-urban migratory exchange.

  5. Characterizations of boundary pluripolar hulls

    NARCIS (Netherlands)

    Djire, I.K.; Wiegerinck, J.

    2016-01-01

    We present some basic properties of the so-called boundary relative extremal function and discuss boundary pluripolar sets and boundary pluripolar hulls. We show that for B-regular domains the boundary pluripolar hull is always trivial on the boundary of the domain and present a “boundary version”

  6. Grain Boundary Complexions

    Science.gov (United States)

    2014-05-01

    deter- mine bulk materials behavior and properties such as superplasticity, creep, fatigue, corrosion , strength and conductivity [2]. Grain boundary...interface (i.e. lattice mismatch accommodated by interface dislocations ), wetting transitions will not occur. A wetting transition is possible in the case...melting only starts around dislocations at low- angle grain boundaries; the grain boundary structure con- sists of isolated liquid pools separated by

  7. Stable Boundary Layer Issues

    OpenAIRE

    Steeneveld, G.J.

    2012-01-01

    Understanding and prediction of the stable atmospheric boundary layer is a challenging task. Many physical processes are relevant in the stable boundary layer, i.e. turbulence, radiation, land surface coupling, orographic turbulent and gravity wave drag, and land surface heterogeneity. The development of robust stable boundary layer parameterizations for use in NWP and climate models is hampered by the multiplicity of processes and their unknown interactions. As a result, these models suffer ...

  8. Oxygen boundary crossing probabilities.

    Science.gov (United States)

    Busch, N A; Silver, I A

    1987-01-01

    The probability that an oxygen particle will reach a time dependent boundary is required in oxygen transport studies involving solution methods based on probability considerations. A Volterra integral equation is presented, the solution of which gives directly the boundary crossing probability density function. The boundary crossing probability is the probability that the oxygen particle will reach a boundary within a specified time interval. When the motion of the oxygen particle may be described as strongly Markovian, then the Volterra integral equation can be rewritten as a generalized Abel equation, the solution of which has been widely studied.

  9. Roughness of grain boundaries in partly recrystallized aluminum

    DEFF Research Database (Denmark)

    Sun, Jun; Zhang, Yubin; Juul Jensen, Dorte

    2017-01-01

    cold rolled aluminum samples. The results show that particle pinning is not the main reason accounting for recrystallization boundary roughness in the present samples. The roughness is however shown to relate to the deformation microstructure and possible effects of migration rate are discussed...

  10. Migration og etnicitet

    DEFF Research Database (Denmark)

    Christiansen, Connie Carøe

    2004-01-01

    Migration og etnicitet er aktuelle og forbundne fænomener, idet migration øger berøringsfladerne mellem befolkningsgrupper. Etniciteter formes i takt med at grænser drages imellem disse grupper. Imod moderniserings-teoriernes forventning forsvandt etnicitet ikke som en traditionel eller oprindelig...... måde at skabe tilhørsforhold på; globalt set fremstår vor tid istedet som en "migrationens tidsalder", der tilsyneladende også er en tidsalder, hvor kulturelle særtræk, i form af etnicitet, udgør vigtige linjer, hvorefter grupper skilller sig ud fra hinanden. Både migration og etnicitet bringer fokus...... den finder sted i modtagerlandet, men nyere perspektiver på migration, som begreber om medborgerskab, transnationalisme og diaspora er eksponenter for, søger udover den nationalstatslige ramme og inddrager konsekvenserne af migrationen for afsenderlande....

  11. Reversal in Migration of Gravel-Sand Transition

    Science.gov (United States)

    Kim, W.

    2011-12-01

    Downstream lithofacies change is an important key to interpret fluviodeltaic depositional environment, which can be recognized by lithologic features, such as grain-size. It has been generally accepted that changes in the downstream position of grain-size transition (e.g., gravel-sand transition) are attributed to variations in basinal forcing (e.g., climate variation, sea-level change and basin subsidence), factors that also cause shoreline migration. However, no quantitative model for predicting evolution of fluviodeltaic strata thoroughly incorporates lithofacies boundaries and allows their free individual migrations. In this presentation, I present a delta evolution model to provide the quantitative understanding of the relationship between the external moving boundary (delta shoreline) and the internal moving boundaries (grain-size transitions). By treating internal coarse to fine grain-size transitions as moving boundaries, the model is capable of accurately predicting the dynamic interactions between the upstream river reaches with different dominant grain-sizes and the downstream shoreline migration in response to base-level changes. For simplicity, the model employs one grain-size transition between the upstream gravel-bed reach and the downstream sand-bed reach and constant rates of water discharge, sediment supply, and relative sea-level rise. Test runs with ranges of sediment supply rates and relative sea-level rise rates show cases for retreat of the gravel-sand transition while the shoreline is still prograding, and thus reveal the condition for reversal in migration of the internal grain-size boundary against the direction of a growing fluviodeltaic system. The model can be used to provide baseline conditions for uniform migration direction of both internal lithofacies transitions and shoreline in fluviodeltaic systems that can be used to accurately assess the trajectory of grain-size transition in sedimentary strata as a proxy for environmental

  12. Stable Boundary Layer Issues

    NARCIS (Netherlands)

    Steeneveld, G.J.

    2012-01-01

    Understanding and prediction of the stable atmospheric boundary layer is a challenging task. Many physical processes are relevant in the stable boundary layer, i.e. turbulence, radiation, land surface coupling, orographic turbulent and gravity wave drag, and land surface heterogeneity. The

  13. A Steering Model of Endothelial Sheet Migration Recapitulates Monolayer Integrity and Directed Collective Migration ▿ †

    Science.gov (United States)

    Vitorino, Philip; Hammer, Mark; Kim, Jongmin; Meyer, Tobias

    2011-01-01

    Cells in endothelial cell monolayers maintain a tight barrier between blood and tissue, but it is not well understood how endothelial cells move within monolayers, pass each other, migrate when stimulated with growth factor, and also retain monolayer integrity. Here, we develop a quantitative steering model based on functional classes of genes identified previously in a small interfering RNA (siRNA) screen to explain how cells locally coordinate their movement to maintain monolayer integrity and collectively migrate in response to growth factor. In the model, cells autonomously migrate within the monolayer and turn in response to mechanical cues resulting from adhesive, drag, repulsive, and directed steering interactions with neighboring cells. We show that lateral-drag steering explains the local coordination of cell movement and the maintenance of monolayer integrity by allowing closure of small lesions. We further demonstrate that directional steering of cells at monolayer boundaries, combined with adhesive steering of cells behind, can explain growth factor-triggered collective migration into open space. Together, this model provides a mechanistic explanation for the observed genetic modularity and a conceptual framework for how cells can dynamically maintain sheet integrity and undergo collective directed migration. PMID:20974808

  14. MODERN MIGRATION POLICY OF RUSSIA

    OpenAIRE

    Kobylinsky S. V.; Usenko A. S.

    2014-01-01

    Several peculiarities of the implementation of migration policy in the Russian Federation were considered in this article. We have shown main provisions on refugees and forced migrants from the Ukraine and labor migration. On the basis of the study we have suggested an improvement of migration legislation, in particular, creation of a single codex and migration police

  15. Migration and health.

    Science.gov (United States)

    Evans, J; Baldwin, W

    1987-01-01

    Investigation of migration and health often forces us to acknowledge that the types of migration (international, internal, and residential) interact with each other as well as other population parameters such as the age/sex structure, sexual activity, fertility, mortality, and family structure. Research on migration is often obscured by these interactions. In fact, the adoption of a health perspective in the design of migration research represents a substantial improvement over traditional approaches that are based on distinctions among the various types of population movement. This is because a health perspective treats population movement as a dynamic process by which individuals are related to specific locations by reason of their participation in human networks. In other words, migration is regarded as a human process rather than a discrete event, and accordingly, it becomes less important to describe the individual's involvement with human networks and the institutions sustaining them. The use of a health perspective in migration research often calls our attention to the ways in which the types of migration are interconnected. For example, a migrant from Mexico might exhibit considerable internal mobility and may circulate between Mexico might exhibit considerable internal mobility and may circulate between Mexico and the US over several years until he develops enough contacts in the US to settle in a particular community in which his personal contact with human networks and place-specific institutions are conducive to settlement. Through him, family members may attach to the community. In the process, they all encounter health risks, make demands on the health care system, change the demographic/health characteristics of both sending and receiving places, sometimes act as transmitting agents of disease to those with whom they interact and, undergo changes in their levels of personal development and well-being. A research perspective that investigates these

  16. Migration = cloning; aliasiing

    DEFF Research Database (Denmark)

    Hüttel, Hans; Kleist, Josva; Nestmann, Uwe

    1999-01-01

    In Obliq, a lexically scoped, distributed, object-oriented programming language, object migration was suggested as the creation of a copy of an object’s state at the target site, followed by turning the object itself into an alias, also called surrogate, for the remote copy. We consider the creat......In Obliq, a lexically scoped, distributed, object-oriented programming language, object migration was suggested as the creation of a copy of an object’s state at the target site, followed by turning the object itself into an alias, also called surrogate, for the remote copy. We consider...... the creation of object surrogates as an abstraction of the abovementioned style of migration. We introduce Øjeblik, a distribution-free subset of Obliq, and provide three different configuration-style semantics, which only differ in the respective aliasing model. We show that two of the semantics, one of which...... matches Obliq’s implementation, render migration unsafe, while our new proposal for a third semantics is provably safe. Our work suggests a straightforward repair of Obliq’s aliasing model such that it allows programs to safely migrate objects....

  17. Molecular dynamics simulation of grain-boundary diffusion of vacancies in bcc iron

    Science.gov (United States)

    Kwok, T.; Ho, P. S.; Yip, S.; Balluffi, R.; Brokman, A. W.; Bristowe, P. D.

    1981-06-01

    The jumping of vacancies in a bcc iron sigma = 5 tilt boundary was simulated by computer molecular dynamics. The data yielded a reasonable value of the activation energy for migration and showed that the jump processes are highly structure dependent. The use of a temperature dependent transition probability matrix to describe the diffusion of the vacancies in the grain boundary is suggested. Formation of one type of boundary interstitial was observed which was found to be immobile.

  18. Molecular dynamics simulation of grain-boundary diffusion of vacancies in bcc iron

    Energy Technology Data Exchange (ETDEWEB)

    Kwok, T.; Ho, P. S.; Yip, S.; Balluffi, R. W.; Bristowe, P. D.; Brokman, A.

    1981-06-01

    The jumping of vacancies in a bcc iron ..sigma.. = 5 tilt boundary was simulated by computer molecular dynamics. The data yielded a reasonable value of the activation energy for migration and showed that the jump processes are highly structure-dependent. The use of a temperature dependent transition probability matrix to describe the diffusion of the vacancies in the grain boundary is suggested. Formation of one type of boundary interstitial was observed which was found to be immobile.

  19. Seeking the boundary of boundary extension.

    Science.gov (United States)

    McDunn, Benjamin A; Siddiqui, Aisha P; Brown, James M

    2014-04-01

    Boundary extension (BE) is a remarkably consistent visual memory error in which participants remember seeing a more wide-angle image of a scene than was actually viewed (Intraub & Richardson, Journal of Experimental Psychology: Learning, Memory, and Cognition 15:179-187, 1989). Multiple stimulus factors are thought to contribute to the occurrence of BE, including object recognition, conceptual knowledge of scenes, and amodal perception at the view boundaries (Intraub, Wiley Interdisciplinary Reviews: Cognitive Science 3:117-127, 2012). In the present study, we used abstract scenes instead of images of the real world, in order to remove expectations based on semantic associations with objects and the schematic context of the view. Close-angle and wide-angle scenes were created using irregular geometric shapes rated by independent observers as lacking any easily recognizable structure. The abstract objects were tested on either a random-dot or a blank background in order to assess the influence of implied continuation of the image beyond its boundaries. The random-dot background conditions had background occlusion cues either present or absent at the image border, in order to test their influence on BE in the absence of high-level information about the scenes. The results indicate that high-level information about objects and schematic context is unnecessary for BE to occur, and that occlusion information at the image boundary also has little influence on BE. Contrary to previous studies, we also found clear BE for all conditions, despite using scenes depicting undetailed objects on a blank white background. The results highlighted the ubiquitous nature of BE and the adaptability of scene perception processes.

  20. Administrative Area Boundaries 2 (State Boundaries), Region 9, 2010, NAVTEQ

    Data.gov (United States)

    U.S. Environmental Protection Agency — NAVTEQ Administrative Area Boundaries 2 (State Boundaries) for Region 9. There are five Administrative Area Boundaries layers (1, 2, 3, 4, 5). These layers contain...

  1. Administrative Area Boundaries 4 (City Boundaries), Region 9, 2010, NAVTEQ

    Data.gov (United States)

    U.S. Environmental Protection Agency — NAVTEQ Administrative Area Boundaries 4 (City Boundaries) for Region 9. There are five Administrative Area Boundaries layers (1, 2, 3, 4, 5). These layers contain...

  2. Inverse boundary spectral problems

    CERN Document Server

    Kachalov, Alexander; Lassas, Matti

    2001-01-01

    Inverse boundary problems are a rapidly developing area of applied mathematics with applications throughout physics and the engineering sciences. However, the mathematical theory of inverse problems remains incomplete and needs further development to aid in the solution of many important practical problems.Inverse Boundary Spectral Problems develop a rigorous theory for solving several types of inverse problems exactly. In it, the authors consider the following: ""Can the unknown coefficients of an elliptic partial differential equation be determined from the eigenvalues and the boundary value

  3. Beyond the Boundary

    DEFF Research Database (Denmark)

    Gorm Hansen, Birgitte

    2011-01-01

    Whether celebratory or critical, STS research on science-industry relations has focused on the blurring of boundaries and hybridization of codes and practices. However, the vocabulary of boundary and hybrid tends to reify science and industry as separate in the attempt to map their relation...... as the negotiation of a preexisting science-industry boundary. Rather, viability is obtained through a strategy of "circumventing" the science-industry food chain and "sequestering" biotech components within the research center. Symbiosis allows academic scientists to do biology while at the same time demonstrating...

  4. Beyond the Boundary

    DEFF Research Database (Denmark)

    Gorm Hansen, Birgitte

    2012-01-01

    Whether celebratory or critical, STS research on science-industry relations has focused on the blurring of boundaries and hybridization of codes and practices. However, the vocabulary of boundary and hybrid tends to reify science and industry as separate in the attempt to map their relation...... as the negotiation of a preexisting science-industry boundary. Rather, viability is obtained through a strategy of circumventing the science-industry food chain and sequestering biotech components within the research center. Symbiosis allows academic scientists to do biology while at the same time demonstrating...

  5. En fornemmelse for migration

    DEFF Research Database (Denmark)

    Schütze, Laura Maria

    Afhandlingen undersøger, hvordan sted, museets rolle som aktør og religion er relevante for produktionen af migration på Immigrantmuseet (2012) og i Københavns Museums udstilling At blive københavner (2010). Afhandlingen er baseret på udstillingsanalyse samt interview med relevant museumsfagligt......, anvendes som virkemidler til at nuancere migration og distancere udstillingen fra den offentlige debat om indvandring. Afhandlingen peger på, at produktionen af den nyere danske historie på museum er præget af et fravær af religion. Det skyldes, at de museumsfaglige praksisser og traditioner afspejler en...... identiteter, som vi tager for givet: nationer, byer, kvinder - såvel som migration og religion. Afhandlingen argumenterer følgelig for, at museernes produktion af (materiel) religion er et særdeles relevant, men kun ringe udforsket, genstandsfelt for religionssociologien....

  6. More myths of migration.

    Science.gov (United States)

    Basch, L; Lerner, G

    1986-01-01

    This paper discusses some of the myths of migration. The 5 myths presented are: 1) racism has little to do with the causes of migration and does not necessarily impede the adjustment or success of migrants; 2) in areas where there is a strong feminist movement and trade unions, migrant women receive their support and can count on the solidarity of these organizations; 3) transnational corporations are positive forces in the developing countries where they operate--not only do they provide these states with new sources of capital, but they also impart new industrial skills to the labor force; 4) migration today is essentially short-term in nature--it therefore does not have a strong impact on family life; and 5) most migrants cluster together in ethnic enclaves which provide a strong source of support and diminish dislocation inherent in the migrant process.

  7. On the interrelations between migration and commuting

    Directory of Open Access Journals (Sweden)

    Lukić Vesna

    2013-01-01

    Full Text Available In this paper, we emphasise the significance of studying the interrelations between commuting and migration. The aim of the paper is to point out the factors which affect these interrelations (demographic and socio-economic characteristics of migrants and commuters, labour market, real estate market, information, life style, etc., with the special emphasis on the role of commuting distance onto the chosen mobility type. Besides theorethical frameworks and results of the selected foreign researches up to date, the overview of research of interrelations between migration and commuting in Serbia has also been presented. While earlier studies conducted by Gawryszenski (1978, Termote (1980 and Reitsma&Vergoossen (1987 pointed to the replacement of migration types between each other within country, in recent literature the interaction between migration and commuting has been studied in a trans-boundary context of the contemporary EU. Modern trend of long distance commuting instead of migration and the concept of substitution/replacement regarding migration and commuting have also been discussed. In Serbia, there is a positive correlation between commuting outflows and immigration in rural settlements of Vojvodina province. Namely, commuting and migration are complement, which is the characteristic of both processes sub-urbanisation and ex-urbanisation (Lukić, 2012. In addition to ownership of real estate and previous migration experience, marital status influenced the chosen mobility type in Serbia as well. Adjustment to changes of Serbian labour market is mostly conducted via migration (Miletić, Lukić, Miljanović, 2011. Interrelations between migration and commuting are very significant due to the tendency of transformation of some commuters into migrants. This process has its consequences, both on demographic as well as the overall socio-economic development of the area of commuters’ origin and destination. However, even though the surveys

  8. Resolving ultrafast exciton migration in organic solids at the nanoscale

    Science.gov (United States)

    Penwell, Samuel B.; Ginsberg, Lucas D. S.; Noriega, Rodrigo; Ginsberg, Naomi S.

    2017-11-01

    Effectiveness of molecular-based light harvesting relies on transport of excitons to charge-transfer sites. Measuring exciton migration, however, has been challenging because of the mismatch between nanoscale migration lengths and the diffraction limit. Instead of using bulk substrate quenching methods, here we define quenching boundaries all-optically with sub-diffraction resolution, thus characterizing spatiotemporal exciton migration on its native nanometre and picosecond scales. By transforming stimulated emission depletion microscopy into a time-resolved ultrafast approach, we measure a 16-nm migration length in poly(2,5-di(hexyloxy)cyanoterephthalylidene) conjugated polymer films. Combined with Monte Carlo exciton hopping simulations, we show that migration in these films is essentially diffusive because intrinsic chromophore energetic disorder is comparable to chromophore inhomogeneous broadening. Our approach will enable previously unattainable correlation of local material structure to exciton migration character, applicable not only to photovoltaic or display-destined organic semiconductors but also to explaining the quintessential exciton migration exhibited in photosynthesis.

  9. Research of Internal Migration by Compartment Models: The Case of Erzurum-Bursa

    Directory of Open Access Journals (Sweden)

    Fatih Çakmak

    2017-04-01

    Full Text Available Migration, which consists of quite complex components, is a concept subjected in many scientific research areas. Internal migration refers a migration occurred in the boundaries of a country. Migration in Turkey usually tends to be directed towards larger and more industrialized provinces. Nevertheless, there exists a density on the direction of certain provinces such as migration from Erzurum to Bursa. Nowadays, the proceeding of the migration flows between Erzurum and Bursa since 1980’s is another point which necessitates to be examined. The purpose of this study is to investigate the migration between Erzurum and Bursa by using compartment models in the 1980-2015 period. The paper performs compartment models to explain the changes of migration flows in terms of gross domestic product, unemployment rate, and time. According to the results, there is a significant increase in migration from Erzurum to Bursa depending on the time of migration and unemployment rate. Nonetheless, there is no significant change related with the gross domestic product. In addition, the study has shown that migration increases as unemployment rate decreases; but there is no significant change in migration depending on time and gross domestic product from Bursa to Erzurum.

  10. Transventricular Migration of Neurocysticercosis.

    Science.gov (United States)

    Shah, Abhidha; Vutha, Ravikiran; Sankhe, Shilpa; Goel, Atul

    2017-09-01

    The movements of a neurocysticercosis cyst within the ventricular cavity have been identified rarely. A 22-year old male patient presented with the main symptom of diplopia for about a week. Findings of the neurologic examination revealed bilateral sixth cranial nerve weakness. Investigations during the period showed an intraventricular tumor that migrated from lateral ventricle to the third ventricle and subsequently to the fourth ventricle. The lesion was resected from the fourth ventricle and was identified to be a neurocysticercosis cyst. Such an intraventricular migration of any kind of tumor has not been recorded in the literature. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Migration, Narration, Identity

    DEFF Research Database (Denmark)

    Leese, Peter

    three consecutive summers from 2010 to 2012. The articles focus on various aspects of the migrant experience and try to answer questions about migrant identity and its representations in literature and the media. The book closes with an original play by Carlos Morton, the Chicano playwright working......(co-editor with Carly McLaughlin and Wladyslaw Witalisz) This book presents articles resulting from joint research on the representations of migration conducted in connection with the Erasmus Intensive Programme entitled «Migration and Narration» taught to groups of international students over...

  12. International Migration of Couples

    DEFF Research Database (Denmark)

    Junge, Martin; Munk, Martin D.; Nikolka, Till

    2018-01-01

    Migrant self-selection is important to labor markets and public finances in both origin and destination countries. We develop a theoretical model regarding the migration of dual-earner couples and test it using population-wide administrative data from Denmark. Our model predicts that the probabil......Migrant self-selection is important to labor markets and public finances in both origin and destination countries. We develop a theoretical model regarding the migration of dual-earner couples and test it using population-wide administrative data from Denmark. Our model predicts...

  13. Samtidskunst og migration

    DEFF Research Database (Denmark)

    Petersen, Anne Ring

    2010-01-01

    "Samtidskunst og migration. En oversigt over faglitteraturen" er en forskningsoversigt der gør status over hvad der hidtil er skrevet inden for det kunsthistoriske område om vor tids billedkunst og migration som politisk, socialt og kulturelt fænomen, primært i forbindelse med immigration til...... Europa og i bredere forstand Vesten. Rapporten er en intern rapport som er lavet i tilknytning til det kollektive forskningsprojekt "Islam i europæisk litteratur" på Afdelingen for Litteraturvidenskab og Moderne Kultur og indleveret til dette projekts leder, Peter Madsen....

  14. Making Migration Meaningful

    DEFF Research Database (Denmark)

    Benwell, Ann Fenger

    2013-01-01

    . The article focuses on changing patterns of mobility in the Mongolian ‘age of the market’ and its effects on population groups. Internal and international migration has continually risen as individuals and families have moved to places of opportunity. Connections are believed to be maintained during periods...... of absence by migrant family members, as both men and women are culturally permitted to be separate from their families. Migration is understood to contribute to prosperity, and separations contribute to generate growth and hishig (good fortune) for the good of the family. However, such mobility is also...

  15. Unix Application Migration Guide

    CERN Document Server

    Microsoft. Redmond

    2003-01-01

    Drawing on the experience of Microsoft consultants working in the field, as well as external organizations that have migrated from UNIX to Microsoft® Windows®, this guide offers practical, prescriptive guidance on the issues you are likely to face when porting existing UNIX applications to the Windows operating system environment. Senior IT decision makers, network managers, and operations managers will get real-world guidance and best practices on planning and implementation issues to understand the different methods through which migration or co-existence can be accomplished. Also detailing

  16. [Migration and diabetes].

    Science.gov (United States)

    Aydinkoc-Tuzcu, Kadriye; Schindler, Karin; Kautzky-Willer, Alexandra; Ludvik, Bernhard; Fasching, Peter

    2016-04-01

    The article deals with the demographic data of migration in Austria and with therapeutic advice concerning drug therapy and diabetes education for patients with migration background. In this context socio-cultural specifics are discussed. These suggestions are seen complementary to the general treatment guidelines of the Austrian Diabetes Association.Especially for the fast months Ramadan there are a lot of informations. The most important point is that the patient care must be highly individualized and the management plan may differ for each patient.

  17. What's driving migration?

    Science.gov (United States)

    Kane, H

    1995-01-01

    During the 1990s investment in prevention of international or internal migration declined, and crisis intervention increased. The budgets of the UN High Commissioner for Refugees and the UN Development Program remained about the same. The operating assumption is that war, persecution, famine, and environmental and social disintegration are inevitable. Future efforts should be directed to stabilizing populations through investment in sanitation, public health, preventive medicine, land tenure, environmental protection, and literacy. Forces pushing migration are likely to increase in the future. Forces include depletion of natural resources, income disparities, population pressure, and political disruption. The causes of migration are not constant. In the past, migration occurred during conquests, settlement, intermarriage, or religious conversion and was a collective movement. Current migration involves mass movement of individuals and the struggle to survive. There is new pressure to leave poor squatter settlements and the scarcities in land, water, and food. The slave trade between the 1500s and the 1800s linked continents, and only 2-3 million voluntarily crossed national borders. Involuntary migration began in the early 1800s when European feudal systems were in a decline, and people sought freedom. Official refugees, who satisfy the strict 1951 UN definition, increased from 15 million in 1980 to 23 million in 1990 but remained a small proportion of international migrants. Much of the mass movement occurs between developing countries. Migration to developed countries is accompanied by growing intolerance, which is misinformed. China practices a form of "population transfer" in Tibet in order to dilute Tibetan nationalism. Colonization of countries is a new less expensive form of control over territory. Eviction of minorities is another popular strategy in Iraq. Public works projects supported by foreign aid displace millions annually. War and civil conflicts

  18. Precipitates and boundaries interaction in ferritic ODS steels

    Energy Technology Data Exchange (ETDEWEB)

    Sallez, Nicolas, E-mail: nicolas.sallez@simap.grenoble-inp.fr [Univ. Grenoble Alpes, SIMAP, F-38000 Grenoble (France); Hatzoglou, Constantinos [Groupe de Physique des Matériaux, Université et INSA de Rouen, UMR CNRS 6634, Normandie Université (France); Delabrouille, Fredéric [EDF–EDF R& D, Les Renardières, 77818 Moret-sur-Loing (France); Sornin, Denis; Chaffron, Laurent [CEA, DEN, Service de Recherches Métallurgiques Appliqué, 91191 Gif-sur-Yvette (France); Blat-Yrieix, Martine [EDF–EDF R& D, Les Renardières, 77818 Moret-sur-Loing (France); Radiguet, Bertrand; Pareige, Philippe [Groupe de Physique des Matériaux, Université et INSA de Rouen, UMR CNRS 6634, Normandie Université (France); Donnadieu, Patricia; Bréchet, Yves [Univ. Grenoble Alpes, SIMAP, F-38000 Grenoble (France)

    2016-04-15

    In the course of a recrystallization study of Oxide Dispersion Strengthened (ODS) ferritic steels during extrusion, particular interest was paid to the (GB) Grain Boundaries interaction with precipitates. Complementary and corresponding characterization experiments using Transmission Electron Microscopy (TEM), Energy Dispersive X-ray spectroscopy (EDX) and Atom Probe Tomography (APT) have been carried out on a voluntarily interrupted extrusion or extruded samples. Microscopic observations of Precipitate Free Zones (PFZ) and precipitates alignments suggest precipitate interaction with migrating GB involving dissolution and Oswald ripening of the precipitates. This is consistent with the local chemical information gathered by EDX and APT. This original mechanism for ODS steels is similar to what had been proposed in the late 80s for similar observation made on Ti alloys reinforced by nanosized yttrium oxides: An interaction mechanism between grain boundaries and precipitates involving a diffusion controlled process of precipitates dissolution at grain boundaries. It is believed that this mechanism can be of primary importance to explain the mechanical behaviour of such steels. - Highlights: • To study the microstructural evolution of a ferritic ODS steel during its extrusion, observations have been carried on samples resulting from a voluntarily interrupted extrusion and extruded materials. • A highly heterogeneous precipitate population have been observed. Nanosized coherent precipitates (2–5 nm) on both sides of the grain boundaries despite grain boundary migration after precipitation due to further thermo-mechanical processing as well as coarse precipitates (10–40 nm) alignments are observed on the grain boundaries and within the grains, parallel to the grain boundaries. • Asymmetrical PFZs can be observed around precipitates alignments and grain boundaries. Using TEM with EDX and APT we have been able to ensure that the PFZs are chemically depleted.

  19. HUC 8 Boundaries

    Data.gov (United States)

    Kansas Data Access and Support Center — This data set is a digital hydrologic unit boundary that is at the 4-digit, 6-digit, 8-digit, and 11-digit level. The data set was developed by delineating the...

  20. FWS Approved Acquisition Boundaries

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This data layer depicts the external boundaries of lands and waters that are approved for acquisition by the U.S. Fish and Wildlife Service (USFWS) in North America,...

  1. National Forest Boundaries

    Data.gov (United States)

    Minnesota Department of Natural Resources — This theme shows the USFS national forest boundaries in the state. This data was acquired from the GIS coordinators at both the Chippewa National Forest and the...

  2. VT Telephone Exchange Boundaries

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The UtilityTelecom_EXCHANGE represents Vermont Telephone Exchange boundaries as defined by the VT Public Service Board. The original data was...

  3. State Park Statutory Boundaries

    Data.gov (United States)

    Minnesota Department of Natural Resources — Legislative statutory boundaries for sixty six state parks, six state recreation areas, and eight state waysides. These data are derived principally from DNR's...

  4. 500 Cities: City Boundaries

    Data.gov (United States)

    U.S. Department of Health & Human Services — This city boundary shapefile was extracted from Esri Data and Maps for ArcGIS 2014 - U.S. Populated Place Areas. This shapefile can be joined to 500 Cities...

  5. Allegheny County Parcel Boundaries

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset contains parcel boundaries attributed with county block and lot number. Use the Property Information Extractor for more control downloading a filtered...

  6. Watershed Boundary Areas

    Data.gov (United States)

    Department of Homeland Security — This map layer contains hydrologic unit boundaries and codes for the United States, Puerto Rico, and the U.S. Virgin Islands. It was revised for inclusion in the...

  7. NM School District Boundaries

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The dataset represents the boundaries of all public school districts in the state of New Mexico. The source for the data layer is the New Mexico Public Education...

  8. Allegheny County Boundary

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset contains the Allegheny County boundary. If viewing this description on the Western Pennsylvania Regional Data Center’s open data portal...

  9. Boundary representation modelling techniques

    CERN Document Server

    2006-01-01

    Provides the most complete presentation of boundary representation solid modelling yet publishedOffers basic reference information for software developers, application developers and users Includes a historical perspective as well as giving a background for modern research.

  10. Site Area Boundaries

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset consists of site boundaries from multiple Superfund sites in U.S. EPA Region 8. These data were acquired from multiple sources at different times and...

  11. Tax Unit Boundaries

    Data.gov (United States)

    Kansas Data Access and Support Center — The Statewide GIS Tax Unit boundary file was created through a collaborative partnership between the State of Kansas Department of Revenue Property Valuation...

  12. VT Federal Aid Urban Boundaries

    Data.gov (United States)

    Vermont Center for Geographic Information — Federal Aid Urban boundaries are defined based on US Census data. The roadways within these boundaries have urban classifications. These FAU boundaries were updated...

  13. Integrity of clay till aquitards to DNAPL migration: Assessment using current and emerging characterization tools

    DEFF Research Database (Denmark)

    Fjordbøge, Annika Sidelmann; Janniche, Gry Sander; Jørgensen, Torben H.

    2017-01-01

    % of the total PCE mass. The data set, and associated data analysis, supported vertical migration of DNAPL through fractures in the upper part of the clay till, horizontal migration along high permeability features around the redox boundary in the clay till, and to some extent vertical migration through...... the fractures in the reduced part of the clay till aquitard to the underlying limestone aquifer. The aquitard integrity to DNAPL migration was found to be compromised at a thickness of reduced clay till of less than 2 m....

  14. Biofilm carrier migration model describes reactor performance.

    Science.gov (United States)

    Boltz, Joshua P; Johnson, Bruce R; Takács, Imre; Daigger, Glen T; Morgenroth, Eberhard; Brockmann, Doris; Kovács, Róbert; Calhoun, Jason M; Choubert, Jean-Marc; Derlon, Nicolas

    2017-06-01

    The accuracy of a biofilm reactor model depends on the extent to which physical system conditions (particularly bulk-liquid hydrodynamics and their influence on biofilm dynamics) deviate from the ideal conditions upon which the model is based. It follows that an improved capacity to model a biofilm reactor does not necessarily rely on an improved biofilm model, but does rely on an improved mathematical description of the biofilm reactor and its components. Existing biofilm reactor models typically include a one-dimensional biofilm model, a process (biokinetic and stoichiometric) model, and a continuous flow stirred tank reactor (CFSTR) mass balance that [when organizing CFSTRs in series] creates a pseudo two-dimensional (2-D) model of bulk-liquid hydrodynamics approaching plug flow. In such a biofilm reactor model, the user-defined biofilm area is specified for each CFSTR; thereby, Xcarrier does not exit the boundaries of the CFSTR to which they are assigned or exchange boundaries with other CFSTRs in the series. The error introduced by this pseudo 2-D biofilm reactor modeling approach may adversely affect model results and limit model-user capacity to accurately calibrate a model. This paper presents a new sub-model that describes the migration of Xcarrier and associated biofilms, and evaluates the impact that Xcarrier migration and axial dispersion has on simulated system performance. Relevance of the new biofilm reactor model to engineering situations is discussed by applying it to known biofilm reactor types and operational conditions.

  15. Migration scenarii in extrasolar systems

    Directory of Open Access Journals (Sweden)

    Crida A.

    2011-02-01

    Full Text Available In this review talk, I present the theory of type I migration of small mass planets, and its latest developments that open the possibility of outward migration in the inner part of a protoplanetary disk. I also review the type II migration of giant planets, and mention the runaway, type III. Then, we focus on the migration of pairs of planets in resonance. The eccentricity of the planets raise, and possibly their mutual inclination as well. Also, the migration rate can be changed, and directed outward if the outer planet is the lighter. Last, we present a synthetic scenario of migration for the giant planets of our Solar System.

  16. Migration and regional inequality

    DEFF Research Database (Denmark)

    Peng, Lianqing; Swider, Sarah

    2017-01-01

    rising, regional inequality has actually decreased, and most recently, remained stable. Our study suggests that China’s unique migratory regime is crucial to understanding these findings. We conduct a counterfactual simulation to demonstrate how migration and remittances have mitigated income inequality...

  17. Migration as Adventure

    DEFF Research Database (Denmark)

    Olwig, Karen Fog

    2018-01-01

    Narratives of adventure constitute a well-established convention of describing travel experiences, yet the significance of this narrative genre in individuals’ accounts of their migration and life abroad has been little investigated. Drawing on Simmel and Bakhtin, among others, this article...

  18. Digitizing migration heritage

    DEFF Research Database (Denmark)

    Marselis, Randi

    2011-01-01

    Museums are increasingly digitizing their collections and making them available to the public on-line. Creating such digital resources may become means for social inclusion. For museums that acknowledge migration history and cultures of ethnic minority groups as important subjects in multiethnic...

  19. Diel vertical migrat..

    African Journals Online (AJOL)

    2002-01-24

    Jan 24, 2002 ... crustacean zooplankton but also in a Wide array of different marine zooplankton groups. (Russell 1927, McLaren 1963). Thus there is no doubt that ..... cooperation during field work and for their fruitful discussion on the draft manuscript. REFERENCES. Bayly lAE 1986 Aspects of diel vertical migration in ...

  20. Dispersal and migration

    Directory of Open Access Journals (Sweden)

    Schwarz, C.

    2004-06-01

    Full Text Available Ringing of birds unveiled many aspects of avian migration and dispersal movements. However, there is even much more to be explored by the use of ringing and other marks. Dispersal is crucial in understanding the initial phase of migration in migrating birds as it is to understand patterns and processes of distribution and gene flow. So far, the analysis of migration was largely based on analysing spatial and temporal patters of recoveries of ringed birds. However, there are considerable biases and pitfalls in using recoveries due to spatial and temporal variation in reporting probabilities. Novel methods are required for future studies separating the confounding effects of spatial and temporal heterogeneity of recovery data and heterogeneity of the landscape as well. These novel approaches should aim a more intensive and novel use of the existing recovery data by taking advantage of, for instance, dynamic and multistate modeling, should elaborate schemes for future studies, and should also include other marks that allow a more rapid data collection, like telemetry, geolocation and global positioning systems, and chemical and molecular markers. The latter appear to be very useful in the delineating origin of birds and connectivity between breeding and non–breeding grounds. Many studies of migration are purely descriptive. However, King and Brooks (King & Brooks, 2004 examine if movement patterns of dolphins change after the introduction of a gillnet ban. Bayesian methods are an interesting approach to this problem as they provide a meaningful measure of the probability that such a change occurred rather than simple yes/no response that is often the result of classical statistical methods. However, the key difficulty of a general implementation of Bayesian methods is the complexity of the modelling —there is no general userfriendly package that is easily accessible to most scientists. Drake and Alisauskas (Drake & Alisauskas, 2004 examine the

  1. Migration and Africa

    DEFF Research Database (Denmark)

    Zoppi, Marco

    2014-01-01

    European powers imposed the nation-state on Africa through colonialism. But even after African independencies, mainstream discourses and government policies have amplified the idea that sedentariness and the state are the only acceptable mode of modernity. Migration is portrayed as a menace...

  2. Describing migration spatial structure

    NARCIS (Netherlands)

    Rogers, A; Willekens, F; Little, J; Raymer, J

    The age structure of a population is a fundamental concept in demography and is generally depicted in the form of an age pyramid. The spatial structure of an interregional system of origin-destination-specific migration streams is, however, a notion lacking a widely accepted definition. We offer a

  3. Migrating the Light

    DEFF Research Database (Denmark)

    Sørensen, Bent

    The migration of Blaga’s universalist, even centralist poems from Romanian of the first third of the 20th C. into American of the first fifth of the 21st C. illustrates the uses of Pierre Joris’s nomadic methods. My translations of Blaga read well for a teenage audience whose only exposure to lit...

  4. Practical Data Migration

    CERN Document Server

    Morris, Johny

    2012-01-01

    This book is for executives and practitioners tasked with the movement of data from old systems to a new repository. It uses a series of steps guaranteed to get the reader from an empty new system to one that is working and backed by the user population. Using this proven methodology will vastly increase the chances of a successful migration.

  5. From Migration Regime to Regional Citizenry: Migration and Identity ...

    African Journals Online (AJOL)

    I examine the East African common market, taken as a regional migration regime, and draw its implications for intra-regional migration and identity formation. Using desk research, I analyse the common market Protocol's provisions and envisage the implications of its implementation for intraregional migration and identity ...

  6. The International Organization for Migration in Global Migration Governance

    OpenAIRE

    Poulsen, Sofie Havn; Andersen, Lise

    2011-01-01

    This project focuses on the IOM, the notion of global governance of migration and the interaction between these two. The point of departure has been an attempt to grasp the current global approach to migration and comprehend whether, or to what degree, there is governance of migration issues taking place at a global level.

  7. Zimbabwe's Exodus Crisis, Migration, Survival

    International Development Research Centre (IDRC) Digital Library (Canada)

    Remittances, Informalisation and Dispossession in Urban Zimbabwe Sarah Bracking and Lloyd Sachikonye. 324. Chapter Fifteen Transnationalism and Undocumented Migration Between Rural Zimbabwe and South Africa France Maphosa. 346. Chapter Sixteen Metaphors of Migration: Zimbabwean Migrants in the South ...

  8. [Migration processes in small towns].

    Science.gov (United States)

    Makowska, K

    1988-10-01

    Changing migration patterns in Poland and their impact on small towns are analysed with a focus on the period since the 1950s. The analysis shows that although migration previously benefited major urban areas at the expense of small towns, the migration situation of small towns has recently improved.

  9. Adaptive Sentence Boundary Disambiguation

    CERN Document Server

    Palmer, D D; Palmer, David D.; Hearst, Marti A.

    1994-01-01

    Labeling of sentence boundaries is a necessary prerequisite for many natural language processing tasks, including part-of-speech tagging and sentence alignment. End-of-sentence punctuation marks are ambiguous; to disambiguate them most systems use brittle, special-purpose regular expression grammars and exception rules. As an alternative, we have developed an efficient, trainable algorithm that uses a lexicon with part-of-speech probabilities and a feed-forward neural network. After training for less than one minute, the method correctly labels over 98.5\\% of sentence boundaries in a corpus of over 27,000 sentence-boundary marks. We show the method to be efficient and easily adaptable to different text genres, including single-case texts.

  10. The Bottom Boundary Layer.

    Science.gov (United States)

    Trowbridge, John H; Lentz, Steven J

    2018-01-03

    The oceanic bottom boundary layer extracts energy and momentum from the overlying flow, mediates the fate of near-bottom substances, and generates bedforms that retard the flow and affect benthic processes. The bottom boundary layer is forced by winds, waves, tides, and buoyancy and is influenced by surface waves, internal waves, and stratification by heat, salt, and suspended sediments. This review focuses on the coastal ocean. The main points are that (a) classical turbulence concepts and modern turbulence parameterizations provide accurate representations of the structure and turbulent fluxes under conditions in which the underlying assumptions hold, (b) modern sensors and analyses enable high-quality direct or near-direct measurements of the turbulent fluxes and dissipation rates, and (c) the remaining challenges include the interaction of waves and currents with the erodible seabed, the impact of layer-scale two- and three-dimensional instabilities, and the role of the bottom boundary layer in shelf-slope exchange.

  11. Musei del migration heritage / Migration heritage museums

    Directory of Open Access Journals (Sweden)

    Patrizia Dragoni

    2015-01-01

    Since the second half of the 1960s of the 20th century, a profound cultural innovation was accompanied to the radical change in the social, political and economic climate. The anthropological notion of culture as opposed to idealistic vision, the unusual and strong interest in material culture, the enunciation of the concept of cultural property by the Franceschini Commission, the luck of the Public History bring a change of the disciplinary statutes of historical sciences, which begin to attend to social history, focusing on the spontaneous sources of information and initiating experiences of oral history. To all this a remarkable transformation of the themes and of the social function of museums is added. This paper illustrates, in relation to this more general context, the foundation and the dissemination of museums dedicated to the history of migration in Italy and in the world, enunciates their possible social utility for the integration of present migrants in Italy and illustrates, by way of example, the museum recently opened in Recanati.

  12. Observations of the Hawaiian Mesopelagic Boundary Community in Daytime and Nighttime Habitats Using Estimated Backscatter

    Directory of Open Access Journals (Sweden)

    Comfort CM

    2017-07-01

    Full Text Available The Hawaiian mesopelagic boundary community is a slope-associated assemblage of micronekton that undergoes diel migrations along the slopes of the islands, residing at greater depths during the day and moving upslope to forage in shallower water at night. The timing of these migrations may be influenced by environmental factors such as moon phase or ambient light. To investigate the movements of this community, we examined echo intensity data from acoustic Doppler current profilers (ADCPs deployed at shallow and deep sites on the southern slope of Oahu, Hawaii. Diel changes in echo intensity (and therefore in estimated backscatter were observed and determined to be caused, at least in part, by the horizontal migration of the mesopelagic boundary community. Generalized additive modeling (GAM was used to assess the impact of environmental factors on the migration timing. Sunset time and lunar illumination were found to be significant factors. Movement speeds of the mesopelagic boundary community were estimated at 1.25–1.99 km h-1 (35–55 cm s-1. The location at which the migrations were observed is the future site of a seawater air conditioning system, which will cause artificial upwelling at our shallow observation site and may cause animal entrainment at the seawater intake near our deep water observation site. This study is the first to observe the diel migration of the mesopelagic boundary community on southern Oahu in both deep and shallow parts of the habitat, and it is also the first to examine migration trends over long time scales, which allows a better assessment of the effects of seasons and lunar illumination on micronekton migrations. Understanding the driving mechanisms of mesopelagic boundary community behavior will increase our ability to assess and manage coastal ecosystems in the face of increasing anthropogenic impacts.

  13. Cell shape dynamics: from waves to migration.

    Directory of Open Access Journals (Sweden)

    Meghan K Driscoll

    Full Text Available We observe and quantify wave-like characteristics of amoeboid migration. Using the amoeba Dictyostelium discoideum, a model system for the study of chemotaxis, we demonstrate that cell shape changes in a wave-like manner. Cells have regions of high boundary curvature that propagate from the leading edge toward the back, usually along alternating sides of the cell. Curvature waves are easily seen in cells that do not adhere to a surface, such as cells that are electrostatically repelled from surfaces or cells that extend over the edge of micro-fabricated cliffs. Without surface contact, curvature waves travel from the leading edge to the back of a cell at -35 µm/min. Non-adherent myosin II null cells do not exhibit these curvature waves. At the leading edge of adherent cells, curvature waves are associated with protrusive activity. Like regions of high curvature, protrusive activity travels along the boundary in a wave-like manner. Upon contact with a surface, the protrusions stop moving relative to the surface, and the boundary shape thus reflects the history of protrusive motion. The wave-like character of protrusions provides a plausible mechanism for the zig-zagging of pseudopods and for the ability of cells both to swim in viscous fluids and to navigate complex three dimensional topography.

  14. [Medical genetics and migration].

    Science.gov (United States)

    Feingold, J

    1988-01-01

    Any migration results in the transfer of normal and pathological genes from one population to another. The frequency of pathological genes may vary according to the population, sickle cell anaemia, for instance, being frequent in Africa and cystic fibrosis in Europe. It follows that the hereditary pathology of migrants is not the same as that of the host population, at least during the immediate post-migration years; subsequently, all depends on the degree of cross-breeding. In epidemiological genetics the study of the frequency of some diseases in the original population, among migrants and in the host population enables the effects of genes and environment on the aetiology of these diseases to be investigated.

  15. Tracking migrating birds

    DEFF Research Database (Denmark)

    Willemoes, Mikkel

    Migratory movements of birds has always fascinated man and led to many questions concerning the ecological drivers behind, the necessary adaptations and the navigational abilities required. However, especially for the long-distance migrants, basic descriptions of their movements are still lacking...... and many experiments are only becoming possible with the current development of tracking technologies. During this thesis work I have been tracking the poorly known movements of several species of long-distance migrants and document highly complex migration patterns. In three manuscripts these movements...... were related to the yearly progression of an environmental surrogate for food availability along the course of migration. In one species, with multiple, different non-breeding staging sites, environmental conditions explain movements well and also how yearly differences explain differences in timing...

  16. Religion, migration og integration

    DEFF Research Database (Denmark)

    Borup, Jørn

    2010-01-01

    Sammenhængen mellem religion og integration har de sidste år været genstand for debat. Artiklen kommer ind på begreber og sammenhænge relateret til området (migration, diaspora, assimilation, etnicitet, kultur) og ser på religionens mulige rolle som negativ eller positiv ressource i integrationss......Sammenhængen mellem religion og integration har de sidste år været genstand for debat. Artiklen kommer ind på begreber og sammenhænge relateret til området (migration, diaspora, assimilation, etnicitet, kultur) og ser på religionens mulige rolle som negativ eller positiv ressource i...

  17. Forced Migration: Refugee Populations

    Science.gov (United States)

    Boyle, Joyceen S.

    2015-01-01

    Undocumented migration is a global phenomenon that manifests in various contexts. This article describes the impact of the movement of large numbers of people in several African countries, producing a unique type of migrant—the refugee. We describe issues that refugee movements create on fragile health care systems, situations that precipitate refugee movements, certain human rights violations that are of particular concern such as gender based violence (GBV) and child soldiers, and lastly, implications for nursing practice and policy. We use examples from several countries in Sub-Saharan Africa, including the Democratic Republic of the Congo, Rwanda, Liberia, Sierra Leone, and Mozambique. Drawing on key documents from the United Nations High Commissioner for Refugees, current literature, as well as the international experience of the authors, this article presents an overview of forced migration and discusses opportunities for nurses to impact research, practice and policy related to refugee health. PMID:25645484

  18. Gradient zone boundary control in salt gradient solar ponds

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. (Downers Grove, IL)

    1984-01-01

    A method and apparatus for suppressing zone boundary migration in a salt gradient solar pond includes extending perforated membranes across the pond at the boundaries, between the convective and non-convective zones, the perforations being small enough in size to prevent individual turbulence disturbances from penetrating the hole, but being large enough to allow easy molecular diffusion of salt thereby preventing the formation of convective zones in the gradient layer. The total area of the perforations is a sizable fraction of the membrane area to allow sufficient salt diffusion while preventing turbulent entrainment into the gradient zone.

  19. Syrian Crisis and Migration

    OpenAIRE

    Pinar Yazgan; Deniz Eroglu Utku; Ibrahim Sirkeci

    2015-01-01

    With the growing insurrections in Syria in 2011, an exodus in large numbers have emerged. The turmoil and violence have caused mass migration to destinations both within the region and beyond. The current "refugee crisis" has escalated sharply and its impact is widening from neighbouring countries toward Europe. Today, the Syrian crisis is the major cause for an increase in displacement and the resultant dire humanitarian situation in the region. Since the conflict shows no signs of abating i...

  20. Retrograde Gastrojejunostomy Tube Migration

    Directory of Open Access Journals (Sweden)

    Adeleke Adesina

    2014-01-01

    Full Text Available Percutaneous enteral feeding tubes are placed about 250,000 times each year in the United States. Although they are relatively safe, their placement may be complicated by perforation, infection, bleeding, vomiting, dislodgment, and obstruction. There have been numerous reports of antegrade migration of gastrojejunostomy (G-J tubes. We report a case of G-J tube regurgitation following protracted vomiting and discuss the management of this very rare entity.

  1. American Migration Controversies

    OpenAIRE

    Milan Mesić

    1998-01-01

    The USA has been and has remained the world's most important immigration country. The last quarter of the 20th century has been marked by a new mass immigration wave that in absolute size of the immigration flow can be compared to the highest flows in the previous century. This recent migration, however, differs from traditional immigration to America in that it includes a greater ethnic, religious and cultural diversity. The vast majority of today's immigrants, both legal and clandestine, co...

  2. Enforcement and illegal migration

    OpenAIRE

    Pia Orrenius

    2014-01-01

    Border enforcement of immigration laws attempts to raise the costs of illegal immigration, while interior enforcement also lowers the benefits. Border and interior enforcement therefore reduce the net benefits of illegal immigration and should lower the probability that an individual will decide to migrate. While some empirical studies find that border and interior enforcement serve as significant deterrents to illegal immigration, immigration enforcement is costly and carries significant uni...

  3. Conservation physiology of animal migration

    Science.gov (United States)

    Lennox, Robert J.; Chapman, Jacqueline M.; Souliere, Christopher M.; Tudorache, Christian; Wikelski, Martin; Metcalfe, Julian D.; Cooke, Steven J.

    2016-01-01

    Migration is a widespread phenomenon among many taxa. This complex behaviour enables animals to exploit many temporally productive and spatially discrete habitats to accrue various fitness benefits (e.g. growth, reproduction, predator avoidance). Human activities and global environmental change represent potential threats to migrating animals (from individuals to species), and research is underway to understand mechanisms that control migration and how migration responds to modern challenges. Focusing on behavioural and physiological aspects of migration can help to provide better understanding, management and conservation of migratory populations. Here, we highlight different physiological, behavioural and biomechanical aspects of animal migration that will help us to understand how migratory animals interact with current and future anthropogenic threats. We are in the early stages of a changing planet, and our understanding of how physiology is linked to the persistence of migratory animals is still developing; therefore, we regard the following questions as being central to the conservation physiology of animal migrations. Will climate change influence the energetic costs of migration? Will shifting temperatures change the annual clocks of migrating animals? Will anthropogenic influences have an effect on orientation during migration? Will increased anthropogenic alteration of migration stopover sites/migration corridors affect the stress physiology of migrating animals? Can physiological knowledge be used to identify strategies for facilitating the movement of animals? Our synthesis reveals that given the inherent challenges of migration, additional stressors derived from altered environments (e.g. climate change, physical habitat alteration, light pollution) or interaction with human infrastructure (e.g. wind or hydrokinetic turbines, dams) or activities (e.g. fisheries) could lead to long-term changes to migratory phenotypes. However, uncertainty remains

  4. Migration Profile NIGERIA 1. Structural Migration Profile 2. Flash Migration Profile (January - March 2017)

    OpenAIRE

    BRYTON DIAS MARQUES FERNANDO; URSO GIULIANA

    2017-01-01

    The new generation of Migration Profiles aims at collecting knowledge on migration and development at regular, short intervals (3/6 months) and with a sub-national coverage, providing tailored monitoring and ensuring comparability across countries. It links migration, developmental and humanitarian aspects as well as analyses on the EU strategic role vis-à-vis the third country, including its political, financial and humanitarian support. This publication reproduces the Migration Profile of N...

  5. Many Faces of Migrations

    Directory of Open Access Journals (Sweden)

    Milica Antić Gaber

    2013-12-01

    We believe that in the present thematic issue we have succeeded in capturing an important part of the modern European research dynamic in the field of migration. In addition to well-known scholars in this field several young authors at the beginning their research careers have been shortlisted for the publication. We are glad of their success as it bodes a vibrancy of this research area in the future. At the same time, we were pleased to receive responses to the invitation from representatives of so many disciplines, and that the number of papers received significantly exceeded the maximum volume of the journal. Recognising and understanding of the many faces of migration are important steps towards the comprehensive knowledge needed to successfully meet the challenges of migration issues today and even more so in the future. It is therefore of utmost importance that researchers find ways of transferring their academic knowledge into practice – to all levels of education, the media, the wider public and, of course, the decision makers in local, national and international institutions. The call also applies to all authors in this issue of the journal.

  6. Migrations in Slovenian geography textbooks

    Directory of Open Access Journals (Sweden)

    Jurij Senegačnik

    2013-12-01

    Full Text Available In Slovenia, the migrations are treated in almost all geographical textbooks for different levels of education. In the textbooks for the elementary school from the sixth to ninth grade, students acquire knowledge of the migrations by the inductive approach. Difficulty level of treatment and quantity of information are increasing by the age level. In the grammar school program a trail of gaining knowledge on migration is deductive. Most attention is dedicated to migrations in general geography textbooks. The textbooks for vocational and technical school programs deal with migrations to a lesser extent and with different approaches.

  7. Progress report on grain boundaries, February 15, 1990--October 15, 1990

    Energy Technology Data Exchange (ETDEWEB)

    Balluffi, R.W.; Bristowe, P.D.

    1990-01-01

    The present document is a progress report describing the work accomplished to date during the first year of our four-year grant (February 15, 1990--February 14, 1994) to study grain boundaries. The research was focused on the following four major efforts: study of the aromatic structure of grain boundaries by means of x-ray diffraction, transmission electro microscopy and computer modeling; study of grain boundary migration; study of short-circuit diffusion along grain boundaries; and the development of Thin-Film Deposition/Bonding Apparatus for the manufacture of high purity bicrystals.

  8. Physical Guidance of Cell Migration

    Science.gov (United States)

    Losert, Wolfgang

    Cells migrate as individuals or groups, to perform critical functions in life from organ development to wound healing and the immune response. While directed migration of cells is often mediated by chemical or physical gradients, our recent work has demonstrated that the physical properties of the microenvironment can also control and guide migration. I will describe how an underlying wave-like process of the actin scaffolding drives persistent migration, and how such actin waves are nucleated and guided by the texture of the microenvironment. Based on this observation we design textures capable of guiding cells in a single preferred direction using local asymmetries in nano/microtopography on subcellular scales, or altering migration in other ways. This phenomenon is observed both for the pseudopod-dominated migration of Dictyostelium cells and for the lamellipod-driven migration of human neutrophils. The conservation of this mechanism across cell types suggests that actin-wave-based guidance is important in biology and physiology.

  9. Minnesota County Boundaries - lines

    Data.gov (United States)

    Minnesota Department of Natural Resources — Minnesota county boundaries derived from a combination of 1:24,000 scale PLS lines, 1:100,000 scale TIGER, 1:100,000 scale DLG, and 1:24,000 scale hydrography lines....

  10. Knowledge production at boundaries

    NARCIS (Netherlands)

    Stange, Kari

    2017-01-01

    This thesis addresses how knowledge is used and produced in stakeholder-led collaborations to make long-term management plans for European fishery management. Boundary object theory is applied and developed to explain how stakeholders from the fishing industry interact with each other, and with

  11. Environmentalists without Boundaries

    African Journals Online (AJOL)

    GREGORY

    2009-03-16

    Mar 16, 2009 ... African Journal of Environmental Science and Technology Vol. ... The most fruitful scientific endeavors invariably cross boundaries – across ... The White Man's Burden: Why the West's Efforts to Aid the Rest Have Done So Much ... cooperation and capacity (7)stimulating economic development and growth, ...

  12. Environmentalists without Boundaries

    African Journals Online (AJOL)

    GREGORY

    2009-03-16

    Mar 16, 2009 ... Hence, this is a laudable project, but Coca Cola should also be cognizant of the growing African environmental pollution problems associated with plastics disposal as they market bottled water and other juices on the continent. This is an example of a challenge associated with advertent boundary crossing ...

  13. Minnesota County Boundaries

    Data.gov (United States)

    Minnesota Department of Natural Resources — Minnesota county boundaries derived from a combination of 1:24,000 scale PLS lines, 1:100,000 scale TIGER, 1:100,000 scale DLG, and 1:24,000 scale hydrography lines....

  14. Boundaries of the universe

    CERN Document Server

    Glasby, John S

    2013-01-01

    The boundaries of space exploration are being pushed back constantly, but the realm of the partially understood and the totally unknown is as great as ever. Among other things this book deals with astronomical instruments and their application, recent discoveries in the solar system, stellar evolution, the exploding starts, the galaxies, quasars, pulsars, the possibilities of extraterrestrial life and relativity.

  15. Dual boundary spanning

    DEFF Research Database (Denmark)

    Li-Ying, Jason

    2016-01-01

    The extant literature runs short in understanding openness of innovation regarding and the different pathways along which internal and external knowledge resources can be combined. This study proposes a unique typology for outside-in innovations based on two distinct ways of boundary spanning...

  16. Environmentalists without Boundaries

    African Journals Online (AJOL)

    GREGORY

    2009-03-16

    Mar 16, 2009 ... idea that development and environmental sustainability require poverty eradication is not a shocking one, but many scholars remain skeptical about the ... in developing countries has potentially solved this boundary problem by asking for donations through the purchase of bottled water at a price that will ...

  17. Strengthening mechanisms, creep, and fatigue processes in dispersion-hardened niobium alloy. Final scientific report, 1 Feb 89-31 Jan 92

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, A.K.; Gibeling, J.C.

    1992-04-20

    The creep and fatigue properties of pure Nb and Nb-l%Zr alloy were investigated. A model was developed based on the migration of subgrain boundary that can explain the anomalous primary creep transients found in Nb-l%Zr alloy, due to coarsening of subgrain structure. TEM investigations confirmed that such subgrain coarsening occurs during primary creep of Nb-l%Zr. Baseline low cycle fatigue studies of Nb and Nb-l%Zr were completed. Cyclic hardening is observed and there is a microplastic plateau in Nb. The Nb-1%Zr is stronger in cyclic deformation than Nb, with little influence of strain rate. The deformation in the alloy at both high and low strain rates is controlled by the interaction between gliding edge dislocation and solute atoms.

  18. Inferring single-cell behaviour from large-scale epithelial sheet migration patterns.

    Science.gov (United States)

    Lee, Rachel M; Yue, Haicen; Rappel, Wouter-Jan; Losert, Wolfgang

    2017-05-01

    Cell migration plays an important role in a wide variety of biological processes and can incorporate both individual cell motion and collective behaviour. The emergent properties of collective migration are receiving increasing attention as collective motion's role in diseases such as metastatic cancer becomes clear. Yet, how individual cell behaviour influences large-scale, multi-cell collective motion remains unclear. In this study, we provide insight into the mechanisms behind collective migration by studying cell migration in a spreading monolayer of epithelial MCF10A cells. We quantify migration using particle image velocimetry and find that cell groups have features of motion that span multiple length scales. Comparing our experimental results to a model of collective cell migration, we find that cell migration within the monolayer can be affected in qualitatively different ways by cell motion at the boundary, yet it is not necessary to introduce leader cells at the boundary or specify other large-scale features to recapitulate this large-scale phenotype in simulations. Instead, in our model, collective motion can be enhanced by increasing the overall activity of the cells or by giving the cells a stronger coupling between their motion and polarity. This suggests that investigating the activity and polarity persistence of individual cells will add insight into the collective migration phenotypes observed during development and disease. © 2017 The Author(s).

  19. Collective cell migration drives morphogenesis of the kidney nephron.

    Directory of Open Access Journals (Sweden)

    Aleksandr Vasilyev

    2009-01-01

    Full Text Available Tissue organization in epithelial organs is achieved during development by the combined processes of cell differentiation and morphogenetic cell movements. In the kidney, the nephron is the functional organ unit. Each nephron is an epithelial tubule that is subdivided into discrete segments with specific transport functions. Little is known about how nephron segments are defined or how segments acquire their distinctive morphology and cell shape. Using live, in vivo cell imaging of the forming zebrafish pronephric nephron, we found that the migration of fully differentiated epithelial cells accounts for both the final position of nephron segment boundaries and the characteristic convolution of the proximal tubule. Pronephric cells maintain adherens junctions and polarized apical brush border membranes while they migrate collectively. Individual tubule cells exhibit basal membrane protrusions in the direction of movement and appear to establish transient, phosphorylated Focal Adhesion Kinase-positive adhesions to the basement membrane. Cell migration continued in the presence of camptothecin, indicating that cell division does not drive migration. Lengthening of the nephron was, however, accompanied by an increase in tubule cell number, specifically in the most distal, ret1-positive nephron segment. The initiation of cell migration coincided with the onset of fluid flow in the pronephros. Complete blockade of pronephric fluid flow prevented cell migration and proximal nephron convolution. Selective blockade of proximal, filtration-driven fluid flow shifted the position of tubule convolution distally and revealed a role for cilia-driven fluid flow in persistent migration of distal nephron cells. We conclude that nephron morphogenesis is driven by fluid flow-dependent, collective epithelial cell migration within the confines of the tubule basement membrane. Our results establish intimate links between nephron function, fluid flow, and morphogenesis.

  20. Space Based Ornithology: On the Wings of Migration and Biophysics

    Science.gov (United States)

    Smith, James A.

    2005-01-01

    The study of bird migration on a global scale is one of the compelling and challenging problems of modern biology with major implications for human health and conservation biology. Migration and conservation efforts cross national boundaries and are subject to numerous international agreements and treaties. Space based technology offers new opportunities to shed understanding on the distribution and migration of organisms on the planet and their sensitivity to human disturbances and environmental changes. Migration is an incredibly diverse and complex behavior. A broad outline of space based research must address three fundamental questions: (1) where could birds be, i.e. what is their fundamental niche constrained by their biophysical limits? (2) where do we actually find birds, i.e. what is their realizable niche as modified by local or regional abiotic and biotic factors, and (3) how do they get there (and how do we know?), that is what are their migration patterns and associated mechanisms? Our working hypothesis is that individual organism biophysical models of energy and water balance, driven by satellite measurements of spatio-temporal gradients in climate and habitat, will help us to explain the variability in avian species richness and distribution. Dynamic state variable modeling provides one tool for studying bird migration across multiple scales and can be linked to mechanistic models describing the time and energy budget states of migrating birds. Such models yield an understanding of how a migratory flyway and its component habitats function as a whole and link stop-over ecology with biological conservation and management. Further these models provide an ecological forecasting tool for science and application users to address what are the possible consequences of loss of wetlands, flooding, drought or other natural disasters such as hurricanes on avian biodiversity and bird migration.

  1. Cultural Landscape and Migration

    Directory of Open Access Journals (Sweden)

    Gunnar Haaland

    2011-04-01

    Full Text Available This paper focus on the way Nepalese migrants in Myanmar use features of the natural environment in their homeland in metaphoric constructions of a cultural landscape expressing ethnic identity. It is through such "symbolic work" that perceptions of "ethnoscapes" are shaped and indoctrinated. Although the appeal is to symbols that can serve to foster the importance of Nepaliness as a basis for belonging to an imagined community, this does not mean that the caste/ethnicity interaction boundaries are broken down. It does mean however that sectors of activities where such boundaries are made relevant have been changed and so has the cultural content organized through such interaction boundaries. Ethnoscapes do not exist by themselves from a 'primordial' past; they require ongoing expression and confirmation. Features of a natural environment most migrants have never seen is used as sources for spinning compelling webs of significance extolling the values of belonging to a group that shares a common past in that environment. I shall here present material of an ethnoscape very different from what is experienced in Nepal, namely Nepalese multi-caste/ethnic communities among Kachins, Shans, Burmese, Indian and Chinese traders in the Kachin state of Northern Myanmar. Keywords: Nepali migrants; Myanmar; ethnic identity; cultural landscape DOI: 10.3126/dsaj.v4i0.4515 Dhaulagiri Journal of Sociology and Anthropology Vol.4 2010 pp.99-110

  2. The mechanism for primordial germ-cell migration is conserved between Japanese eel and zebrafish.

    Directory of Open Access Journals (Sweden)

    Taiju Saito

    Full Text Available Primordial germ cells (PGCs are segregated and specified from somatic cells during early development. These cells arise elsewhere and have to migrate across the embryo to reach developing gonadal precursors. Several molecules associated with PGC migration (i.e. dead-end, nanos1, and cxcr4 are highly conserved across phylum boundaries. However, since cell migration is a complicated process that is regulated spatially and temporally by multiple adaptors and signal effectors, the process is unlikely to be explained by these known genes only. Indeed, it has been shown that there are variations in PGC migration pattern during development among teleost species. However, it is still unclear whether the actual mechanism of PGC migration is conserved among species. In this study, we studied the migration of PGCs in Japanese eel (Anguilla japonica embryos and tested the migration mechanism between Japanese eel and zebrafish (Danio rerio for conservation, by transplanting eel PGCs into zebrafish embryos. The experiments showed that eel PGCs can migrate toward the gonadal region of zebrafish embryos along with endogenous PGCs, even though the migration patterns, behaviors, and settlements of PGCs are somewhat different between these species. Our results demonstrate that the migration mechanism of PGCs during embryonic development is highly conserved between these two distantly related species (belonging to different teleost orders.

  3. ILO - International Migration Programme.

    Science.gov (United States)

    Boudraa, Miriam

    2011-01-01

    In a wide International Context characterised not only by the economical development but also by the social, cultural, political and individual development, we witness more and more to a exchange between the developed and the developing countries, which can be translated especially in the migration of the work force. In theory, all countries are either countries of origin either countries of transit or destination, and they are all responsible for the rights of migrant workers by promoting the rights, by monitoring and by preventing the abusive conditions. The process of migration of the workforce can be divided into three stages: the first coincides with the period prior to departure, the second is represented by the aftermath of the departure and the period of stay in the country of destination, the third stage corresponds to the return in the country of origin. The workers must be protected throughout this process by the international organizations that perform the catalytic role of communication and exchange between countries, for the only purpose of protecting the rights of immigrant and/or immigrants workers. The responsibility for the protection of workers is divided among the various players in the International Labour Organisation. Every country has to apply measures according to the international standards regarding workers' rights, standards that guide the various countries in the formulation and implementation of their policies and legislation. These standards are suggested by International Conventions, the ILO Conventions and other international instruments such as the human rights instrument. There has been a big step forward once the ILO Fundamental Conventions and Conventions on Migrant Workers where implemented and this implementation represented the use of the Guidelines "ILO Multilateral Framework on Labour Migration".

  4. Grain Boundary Segregation in Metals

    CERN Document Server

    Lejcek, Pavel

    2010-01-01

    Grain boundaries are important structural components of polycrystalline materials used in the vast majority of technical applications. Because grain boundaries form a continuous network throughout such materials, their properties may limit their practical use. One of the serious phenomena which evoke these limitations is the grain boundary segregation of impurities. It results in the loss of grain boundary cohesion and consequently, in brittle fracture of the materials. The current book deals with fundamentals of grain boundary segregation in metallic materials and its relationship to the grain boundary structure, classification and other materials properties.

  5. Changes in the diffusion properties of nonequilibrium grain boundaries upon recrystallization and superplastic deformation of submicrocrystalline metals and alloys

    Science.gov (United States)

    Chuvil'deev, V. N.; Nokhrin, A. V.; Pirozhnikova, O. E.; Gryaznov, M. Yu.; Lopatin, Yu. G.; Myshlyaev, M. M.; Kopylov, V. I.

    2017-08-01

    The effect of an increase in the coefficient of the grain-boundary diffusion upon recrystallization and superplastic deformation of submicrocrystalline (SMC) materials prepared by severe plastic deformation has been studied. It is shown that the coefficient of the grain-boundary diffusion of the SMC materials is dependent on the intensity of the lattice dislocation flow whose value is proportional to the rate of the grain boundary migration upon annealing of SMC metals or the rate of the intragrain deformation under conditions of superplastic deformation of SMC alloys. It is found that, at a high rate of grain boundary migrations and high rates of superplastic deformation, the intensity of the lattice dislocation flow bombarding grain boundaries of SMC materials is higher than the intensity of their diffusion accommodation, which leads to an increase in the coefficient of the grain-boundary diffusion and a decrease in the activation energy. The results of the numerical calculations agree well with the experimental data.

  6. Manipulation of cell mechanotaxis by designing curvature of the elasticity boundary on hydrogel matrix.

    Science.gov (United States)

    Ueki, Ayaka; Kidoaki, Satoru

    2015-02-01

    Directional cell migration induced by the stiffness gradient of cell culture substrates is known as a subset of the mechanical-cue-induced taxis, so-called mechanotaxis, typically durotaxis toward hard region. To establish the general conditions of biomaterials to manipulate the mechanotaxis, the effect of the shape of the elasticity transition boundary between hard and soft regions of a substrate on mechanotaxis should be systematically determined as well as the conditions of elasticity gradient strength. Here, as a simplified factor of expressing variations in the shape of the elasticity boundary in living tissues, we focus on the curvature of the elasticity boundary. Mask-free photolithographic microelasticity patterning of photocurable gelatin gel was employed to systematically prepare elasticity boundaries with various curvatures, and the efficiency of mechanotaxis of fibroblast cells around each curved boundary was examined. Highly efficient usual durotaxis was induced on a convex boundary with 100 μm in radius and on a concave boundary with 750 μm in radius of curvature. Interestingly, biased migration toward soft regions of the gel, i.e., inverse durotaxis, was first observed for concave boundaries with 50 μm or 100 μm in radius of curvature, which was named as "negative mechanotaxis". The curvature of the elasticity boundary was found to markedly affect the efficiency of induction and the direction of mechanotaxis. The mechanism responsible for this phenomenon and the implication for the curvature effect in in vivo systems are discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. International Migration of Couples

    OpenAIRE

    Junge, Martin; Munk, Martin D.; Nikolka, Till; Poutvaara, Panu

    2017-01-01

    We analyze emigration and return decisions of Danish couples. Our main questions are how emigration and return migration decisions depend on education, earnings, and the number and age of children. We use register data on full population from 1982 to 2006, focusing on opposite-gender couples in which the female is aged 23 to 37, and the male 25 to 39. We find that power couples in which both are highly educated are most likely to emigrate, but also most likely to return. Couples in which only...

  8. Globalization, migration and health.

    Science.gov (United States)

    Burnett, Angela

    2002-01-01

    The term 'globalization' describes the integration of economic systems through improved communication, but it also represents increased insecurity for those with few resources--particularly refugees. This article examines why people migrate, their numbers, constraints on their movement and their particular health care needs. Immigrants have much to contribute to their recipient countries, but at some loss to their homelands. Both economically and morally, more liberal immigration policies would be beneficial. Policies towards asylum seekers should not be more restrictive in the aftermath of 11 September 2001 and detention should be the exception rather than the rule. Globalization should be managed so as to improve people's lives throughout the world.

  9. [Obesity, migration and adolescence].

    Science.gov (United States)

    Chamay-Weber, Catherine; Shehu-Brovina, Shqipe; Narring, Françoise

    2012-06-13

    Weight management interventions during adolescence are challenging. Migration adds complexity to this problem, making migrant families more vulnerable. Teenagers confront families to new values transmitted by the host society: opulence, junk food, video games. Obesity should not be seen as a single issue of calories-excess, but must be considered as being part of a larger problem, which takes into account the context of the familial and societal life of the migrants. The caregivers must have an overall view of the situation to provide appropriate approaches to weight management.

  10. Urbanization, Migration, Information

    Directory of Open Access Journals (Sweden)

    Konstantin Lidin

    2016-05-01

    Full Text Available In the contemporary world urbanization becomes a large-scale process. Huge flows of people migrate from poorer districts to the cities with a higher level of consumption. It takes migrants about 15-25 years to give up their traditional ascetic way of life. In this period the ‘new citizens’ try to arrange compact settlements with an archaic way of life, insanitary conditions, high criminogenity and an authoritative local self-government. The processes of formation and decay of the ascetic enclave are viewed through the example of the ‘Shanghai’ trading neighborhood in Irkutsk.

  11. Migration and loving

    OpenAIRE

    Gevrek, Deniz

    2010-01-01

    This paper explores the relationship between anti-miscegenation laws, interracial marriage and black males' geographical distribution in the U.S. during and after the Great Migration. The U.S. Supreme Court decision in the case of Loving v. Virginia in 1967, which forced the last 16 Southern states to strike down their anti-miscegenation laws, creates a unique opportunity to explore the impact of an exogenous change in a state's laws regulating interracial marriages. Analyzing the U.S. Census...

  12. Boundary-layer theory

    CERN Document Server

    Schlichting (Deceased), Hermann

    2017-01-01

    This new edition of the near-legendary textbook by Schlichting and revised by Gersten presents a comprehensive overview of boundary-layer theory and its application to all areas of fluid mechanics, with particular emphasis on the flow past bodies (e.g. aircraft aerodynamics). The new edition features an updated reference list and over 100 additional changes throughout the book, reflecting the latest advances on the subject.

  13. Measuring the Substellar Boundary

    Science.gov (United States)

    Cancino, Adolfo Andrew; Dupuy, Trent

    2018-01-01

    Brown dwarfs are not massive enough to undergo hydrogen fusion and therefore constantly lose heat and change luminosity over their lifetime. Because of this, brown dwarfs do not follow the same pattern that stars on the main sequence follow. Brown dwarfs can have similar luminosities but widely differing masses, or vice versa, while stars follow a tight relationship between mass and luminosity. In principle, mass and luminosity measurements straddling the boundary between stars and brown dwarfs could be used to directly measure this dividing line in mass. We present a method for determining this boundary accurately given a limited sample size. We tested our method with Monte Carlo simulated samples of brown dwarfs and stars with randomly drawn masses and ages, using evolutionary models to infer luminosities. In our simulation designed to mimic the largest current sample of such mass measurements (37 objects; Dupuy & Liu 2017), we find that the uncertainty in the dividing line that can be inferred from the data is ± 4 MJup. This implies that distinguishing between competing evolutionary model predictions for the boundary (~70-80 MJup) will be difficult given the current sample size of mass measurements.

  14. Palaearctic-African Bird Migration

    DEFF Research Database (Denmark)

    Iwajomo, Soladoye Babatola

    Bird migration has attracted a lot of interests over past centuries and the methods used for studying this phenomenon has greatly improved in terms of availability, dimension, scale and precision. In spite of the advancements, relatively more is known about the spring migration of trans......-Saharan migrants than autumn migration. Information about the behavior and interactions of migrants during the nonbreeding season in sub-Saharan Africa is also scarce for many species. Furthermore, very little is known about intra-African migration. This thesis summarizes my research on the autumn migration...... of birds from Europe to Africa and opens up the possibility of studying intra-African migration. I have used long-term, standardized autumn ringing data from southeast Sweden to investigate patterns in biometrics, phenology and population trends as inferred from annual trapping totals. In addition, I...

  15. Network migration for printers

    CERN Multimedia

    2016-01-01

    Further to the recent General Purpose (office) Network reorganisation (as announced in the Bulletin - see here), please note that the majority of print devices will be automatically migrated to the new network IP address range on Tuesday 27 September.   This change should be transparent for these devices and therefore end-users, provided you have installed the printers from the Print Service website. A small number of devices will require manual intervention from the Printer Support team in order to migrate correctly. These devices will not change their IP address until the manual intervention, which will be carried out before Monday 3rd October. However, if you have mistakenly connected directly to the printer’s IP address, then your printing will be affected – please uninstall the printer (for help, see: KB3785), and re-install it from the Print Service website (or follow instructions for visitor machines). Please do this as soon as possible in order to avoid printing issues, t...

  16. Circular Migration and Human Development

    OpenAIRE

    Newland, Kathleen

    2009-01-01

    This paper explores the human development implications of circular migration — both where it occurs naturally and where governments work to create it. The paper discusses various conceptions and definitions of circular migration, and concludes that circular migration is not intrinsically positive or negative in relation to human development; its impact depends upon the circumstances in which it occurs, the constraints that surround it and—above all—the degree of choice that individuals can ex...

  17. The challenges of managing migration

    Energy Technology Data Exchange (ETDEWEB)

    Tacoli, Cecilia

    2005-10-15

    Migration and urbanisation are driven by economic growth and social change, but also by deepening inequalities. Managing migration should not be equated with curbing it, as this inevitably reduces migrants' rights. But managing population movement whilst respecting the rights of migrants and nonmigrants, supporting the contribution of migration to poverty reduction and economic growth in sending and receiving areas and reducing the human and material costs of movement means that fundamental challenges need to be addressed.

  18. Boundary issues and personality disorders.

    Science.gov (United States)

    Gutheil, Thomas G

    2005-03-01

    The author first presents an overview of the basic elements of boundary theory and clarifies the distinction between boundary crossings and boundary violations. The concepts of context dependence, power asymmetry, and fiduciary duty as they relate to boundary problems are also discussed. The intrinsic and extrinsic consequences of boundary problems are reviewed. The extrinsic consequences fall into three major categories: civil lawsuits, complaints to the board of registration, and complaints to professional societies. The author then reviews types of boundary issues that arise in relation to histrionic, dependent, antisocial, and borderline personality disorders. Countertransference issues that arise in working with patients with personality disorders are discussed, as well as cultural differences that may affect the perception of boundary problems. The article ends with a list of risk management principles and recommendations for avoiding boundary problems in the therapeutic relationship.

  19. Allegheny County Zip Code Boundaries

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset demarcates the zip code boundaries that lie within Allegheny County. These are not clipped to the Allgeheny County boundary. If viewing this...

  20. Macrostabilization of the Migration Phenomenon

    Directory of Open Access Journals (Sweden)

    Cristina Burghelea

    2014-03-01

    Full Text Available MacLabour migration is a present phenomenon in the European Union. This phenomenon takes over the entire European continent, but especially in the EU countries. The labor market in Europe is increasingly affected by population aging. Economic differences between European countries make workforce in developing countries to move to developed countries where they find it easier to work and receive higher remuneration than in their home countries. This article tracks labor migration from/to EU, employment in Romania and Romanian migration towards the countries of Western Europe. It also presents statistics on labor migration in the EU and its impact on the labor market

  1. Substrate curvature regulates cell migration.

    Science.gov (United States)

    He, Xiuxiu; Jiang, Yi

    2017-05-23

    Cell migration is essential in many aspects of biology. Many basic migration processes, including adhesion, membrane protrusion and tension, cytoskeletal polymerization, and contraction, have to act in concert to regulate cell migration. At the same time, substrate topography modulates these processes. In this work, we study how substrate curvature at micrometer scale regulates cell motility. We have developed a 3D mechanical model of single cell migration and simulated migration on curved substrates with different curvatures. The simulation results show that cell migration is more persistent on concave surfaces than on convex surfaces. We have further calculated analytically the cell shape and protrusion force for cells on curved substrates. We have shown that while cells spread out more on convex surfaces than on concave ones, the protrusion force magnitude in the direction of migration is larger on concave surfaces than on convex ones. These results offer a novel biomechanical explanation to substrate curvature regulation of cell migration: geometric constrains bias the direction of the protrusion force and facilitates persistent migration on concave surfaces.

  2. Migration and European integration of Serbia

    Directory of Open Access Journals (Sweden)

    Lutovac Zoran

    2016-01-01

    Full Text Available This paper focuses on migration in the context of European integration which implies, on the one hand, internal integration, integration within the EU and, on the other hand, the enlargement process related to the countries that have applied to join the EU. The aim is to determine in which way the migration, especially refugee crisis in 2015, had influence on the EU, as a supranational political community, and what was the impact on Serbia which is in the process of integration into the European Union. Migrant crisis has shown that the EU has to confront many different issues including several issues of great importance for its survival and strengthening: how to influence on global processes to a greater extent instead of dealing with the consequences of the global politics of others; how to preserve and keep the values that the EU itself is founded and the values on which should be built upon further construction of the political community and, finally, weather the EU can be transformed in the direction of the United European States, in both the functional and in terms of values, or the EU will move towards deepening of Europe of concentric circles. Faced with extremely complex migration situation, Serbia does not have the appropriate institutional and regulatory framework, nor a political response to a series of complex issues in the area of migration and migration-related issues, such as asylum system, irregular migration, sustainable return of our citizens asylum seekers in EU member states, implementation of the agreement on readmission, the departure of highly educated - brain drain, migration and development, the fight against human trafficking (protection of victims, prevention, criminal prosecution of traffickers, and smuggling of migrants, issues of border management, demarcation and boundary determination (as well as the agreement that should be concluded. Some of these problems migrant crisis has made visible by encouraging coping

  3. Les questions de migrations internationales (Questions of International Migrations).

    Science.gov (United States)

    Samman, Mouna Liliane

    1993-01-01

    Education about international migration should (1) utilize a framework of historical evolution; (2) stress the growing interdependence of nations; (3) emphasize universal moral values and the role of the individual in human rights; and (4) consider the complementary or competing portraits of international migration presented by the media. (DMM)

  4. Countering inbreeding with migration 1. Migration from unrelated ...

    African Journals Online (AJOL)

    The eff'ect of migration on inbreeding is moclelled fbr small populations with immigrants from a large unrelated population. Different migration rates and numbers fbr the two sexes are assumed, and a general recursion equation for inbreeding progress derived, which can be shown to lead to an equilibrium inbreeding ...

  5. Cryogenic EBSD on ice: preserving a stable surface in a low pressure SEM

    NARCIS (Netherlands)

    Weikusat, I.; Winter, D.A.M. de; Pennock, G.M.; Hayles, M.; Schneijdenberg, C.T.W.M.; Drury, M.R.

    2011-01-01

    Naturally deformed ice contains subgrains with characteristic geometries that have recently been identified in etched surfaces using high-resolution light microscopy (LM). The probable slip systems responsible for these subgrain boundary types can be determined using electron backscattered

  6. Patterns of East to West migration in the context of European migration systems possibilities and limits of migration control

    OpenAIRE

    Irina Molodikova

    2008-01-01

    This paper gives an overview of the main migration trends of the CIS (Commonwealth of Independent States) migration system in the context of the development of EU migration and migration control and seeks to explain the peculiarities of the CIS migration system’s development.

  7. Quantitative and qualitative approaches to identifying migration chronology in a continental migrant

    Science.gov (United States)

    Beatty, William S.; Kesler, Dylan C.; Webb, Elisabeth B.; Raedeke, Andrew H.; Naylor, Luke W.; Humburg, Dale D.

    2013-01-01

    The degree to which extrinsic factors influence migration chronology in North American waterfowl has not been quantified, particularly for dabbling ducks. Previous studies have examined waterfowl migration using various methods, however, quantitative approaches to define avian migration chronology over broad spatio-temporal scales are limited, and the implications for using different approaches have not been assessed. We used movement data from 19 female adult mallards (Anas platyrhynchos) equipped with solar-powered global positioning system satellite transmitters to evaluate two individual level approaches for quantifying migration chronology. The first approach defined migration based on individual movements among geopolitical boundaries (state, provincial, international), whereas the second method modeled net displacement as a function of time using nonlinear models. Differences in migration chronologies identified by each of the approaches were examined with analysis of variance. The geopolitical method identified mean autumn migration midpoints at 15 November 2010 and 13 November 2011, whereas the net displacement method identified midpoints at 15 November 2010 and 14 November 2011. The mean midpoints for spring migration were 3 April 2011 and 20 March 2012 using the geopolitical method and 31 March 2011 and 22 March 2012 using the net displacement method. The duration, initiation date, midpoint, and termination date for both autumn and spring migration did not differ between the two individual level approaches. Although we did not detect differences in migration parameters between the different approaches, the net displacement metric offers broad potential to address questions in movement ecology for migrating species. Ultimately, an objective definition of migration chronology will allow researchers to obtain a comprehensive understanding of the extrinsic factors that drive migration at the individual and population levels. As a result, targeted

  8. Boundaries and Boundary Marks - Substantive Cultural Heritage of Extensive Importance

    Science.gov (United States)

    Waldhaeusl, P.; Koenig, H.; Mansberger, R.

    2015-08-01

    The Austrian Society for surveying and Geoinformation (ASG) has proposed to submit "Boundaries and Boundary Marks" for the UNESCO World Heritage title. It was time that boundaries, borders and limits of all types as well as ownership rights would find the proper attention in the global public. Landmarks symbolize the real property and the associated rights and obligations, in a figurative sense, the property generally and all legal limits. A democratic state of law is impossible at today's population density without a functioning land administration system with surveying and jurisdiction. As monumental World Heritage representatives of the geodetic artwork "Boundaries and Boundary Marks" are specifically proposed: remaining monuments of the original cadastral geodetic network, the first pan-Austrian surveying headquarters in Vienna, and a specific selection of outstanding boundary monuments. Landmarks are monuments to the boundaries which separate rights and obligations, but also connect the neighbors peacefully after written agreement. "And cursed be he who does not respect the boundaries" you wrote already 3000 years ago. Boundaries and Boundary Marks are a real thing; they all belong to the tangible or material heritage of human history. In this context also the intangible heritage is discussed. This refers to oral tradition and expressions, performing arts; social practices, rituals and festive events; as well as to knowledge and practices handling nature and the universe. "Boundaries and Boundary Marks" do not belong to it, but clearly to the material cultural world heritage. "Boundary and Boundary Marks" is proposed to be listed according to the criteria (ii),(iv),(vi).

  9. Boundary Fractal Analysis of Two Cube-oriented Grains in Partly Recrystallized Copper

    DEFF Research Database (Denmark)

    Sun, Jun; Zhang, Yubin; Dahl, Anders Bjorholm

    2015-01-01

    The protrusions and retrusions observed on the recrystallizing boundaries affect the migration kinetics during recrystallization. Characterization of the boundary roughness is necessary in order to evaluate their effects. This roughness has a structure that can be characterized by fractal analysi......, and in this study the so-called “Minkowski sausage” method is adopted. Hereby, two cube-oriented grains in partly recrystallized microstructures are analyzed and quantitative information regarding the dimensions of protrusions/retrusions is obtained....

  10. Migration - utopia or myopia?

    Directory of Open Access Journals (Sweden)

    Peter Osborne

    1998-03-01

    Full Text Available Peter Osborne spent a sabbatical in northern America and was surprised that so many scientists and students stated that caribou migration was largely the result of mosquito pressure. He failed however to find any documented evidence of this claim although he was constantly confronted by the well known «facts» that mosquitoes had been observed to drive caribou crazy and even kill juveniles. The issue Osborne wishes to focus is that an experimentally unsubstantiated anthropomorphism appears to have become critical evidence in support of a theory. A recent article in Nature (393, 511-513, 1998 devoted to the uses of 'science in fiction' to stimulate thought and discussion about aspects of academia encouraged him to write the following comment in the form of a parody of ancient Greek dialogues.

  11. Nightly Test system migration

    CERN Document Server

    Win-Lime, Kevin

    2013-01-01

    The summer student program allows students to participate to the Cern adventure. They can follow several interesting lectures about particle science and participate to the experiment work. As a summer student, I had worked for LHCb experiment. LHCb uses a lot of software to analyze its data. All this software is organized in packages and projects. They are built and tested during the night using an automated system and the results are displayed on a web interface. Actually, LHCb is changing this system. It is looking for a replacement candidate. So I was charged to unify some internal interfaces to permit a swift migration. In this document, I will describe shortly the system used by LHCb, then I will explain what I have done in detail.

  12. Migration issues important -- Mongolia.

    Science.gov (United States)

    1999-01-01

    Migration and urbanization are issues that require increasing attention in Mongolia. Mr. Sodov Sonin, Minister of Health and Social Welfare, stated at the Forum that fertility has declined, but mortality, in particular the mortality of children and mothers, is still too high. In addition, there is a significant gap between the knowledge of and behaviors concerning reproductive health, which is one of the causes of the country's high abortion rates. However, on the positive side, literacy is high among women--70% of the students in Mongolia's higher educational institutions are female and the State recognizes equal rights for women. Moreover, programs that promote health and education, including the National Program on Reproductive Health, are being implemented; but despite all these, Mongolia still lacks the human and financial resources to implement the ICPD Program of Action satisfactorily. The country also needs dramatic changes in mind-set and in terms of capacity building, given its ongoing socioeconomic transition.

  13. Migration: the trends converge.

    Science.gov (United States)

    1985-09-01

    Formerly, Australia, New Zealand, Canada, and the US have served as permanent destinations for immigrants, while Europe's migrants have moved to more northerly countries to work for a time and then returned home. From 1973-1975 Europe's recruitment of foreign workers virtually ended, although family reunion for those immigrants allowed in was encouraged. Problems resulting from this new settlement migration include low paying jobs for immigrant women, high unemployment, and inadequate education for immigrant children. Illegal migrants from Latin America and the Caribbean enter the US and Canada each year while illegal North African immigrants enter Italy, Spain, and Greece. North America, Australia, and Europe have all received political refugees from Asia and Latin America. Increasingly, these foreigners compete in the labor market rather than simply fill jobs the native workers do not want. All the receiving countries have similar policy priorities: 1) more effective ways for controlling and monitoring inflows and checking illegal immigration; 2) encouraging normal living patterns and accepting refugees; and 3) integrating permanent migrants into the host country. Europe's public immigration encouragement prior to the first oil shock, has left some countries with a labor force that is reluctant to return home. It is unlikely that Europe will welcome foreign labor again in this decade, since unemployment among young people and women is high and family reunion programs may still bring in many immigrants. Less immigration pattern change will probably occur in North America, Australia, and New Zealand since these countries' populations are still growing and wages are more flexible. Immigration, regulated by policy, and emigration, determined by market forces, now are working in the same direction and will likely reduce future migration flows.

  14. A classification of ecological boundaries

    Science.gov (United States)

    Strayer, D.L.; Power, M.E.; Fagan, W.F.; Pickett, S.T.A.; Belnap, J.

    2003-01-01

    Ecologists use the term boundary to refer to a wide range of real and conceptual structures. Because imprecise terminology may impede the search for general patterns and theories about ecological boundaries, we present a classification of the attributes of ecological boundaries to aid in communication and theory development. Ecological boundaries may differ in their origin and maintenance, their spatial structure, their function, and their temporal dynamics. A classification system based on these attributes should help ecologists determine whether boundaries are truly comparable. This system can be applied when comparing empirical studies, comparing theories, and testing theoretical predictions against empirical results.

  15. Migration of rigid particles in two-phase viscoelastic shear flow

    Science.gov (United States)

    Anderson, Patrick; Jaensson, Nick; Hulsen, Martien

    2017-11-01

    We present simulations of particle migration in two-phase flows, where one of the fluids is viscoelastic, whereas the other is Newtonian. The fluid-fluid interface is assumed to be diffuse, and is described using Cahn-Hilliard theory. The equations are solved using the finite element method on moving meshes that are aligned with the particle boundary. The meshes used are highly refined in the interfacial region between the fluids and near the particle boundary, which allows us to perform simulations with a small interfacial thickness. Four regimes of particle migration are observed. The first regime, migration away from the interface, occurs if normal stresses in the viscoelastic fluid are absent, i.e. a Newtonian fluid. Due to the deformation of the interface, as Laplace pressure is build up, effectively pushing the particle away from the interface. The second regime, halted migration, occurs if the particle migrates toward the interface, but the migration is halted due to the Laplace pressure. In the third regime, interface penetration, the interfacial tension is not large enough to halt the migration, and the particle moves into the Newtonian fluid, encapsulated by a film of viscoelastic fluid. In the final fourth regime the particles are adsorbed at the interface.

  16. Transcending Organizational Boundaries

    DEFF Research Database (Denmark)

    Kringelum, Louise Tina Brøns

    This thesis explores how processes of business model innovation can unfold in a port authority by transcending organizational boundaries through inter-organizational collaboration. The findings contribute to two fields of academic inquiry: the study of business model innovation and the study of how...... by applying the engaged scholarship approach, thereby providing a methodological contribution to both port and business model research. Emphasizing the interplay of intra- and inter-organizational business model innovation, the thesis adds insight into the roles of port authorities, business model trends...

  17. Grain Boundary Energies in Copper.

    Science.gov (United States)

    Omar, Ramli

    Available from UMI in association with The British Library. Requires signed TDF. The dependence of grain boundary energy on boundary orientation was studied in copper annealed at 1000 ^circC. Grain boundary orientations and the disorientations across the boundaries were measured. A rotation matrix notation is used to interpret selected area electron channelling patterns observed in a scanning electron microscope. The Herring and Shewmon torque terms were investigated using wire specimens having a "bamboo" structure. The Herring torque terms were determined using the Hess relation. The (110) section of the Sigma 11 gamma-plot (i.e. the variation of grain boundary energy with boundary orientation) was evaluated. In this plot, minima in energies were found at the (311) and (332) mirror planes. Sigma 3 and Sigma9 boundaries were investigated in sheet specimens. The (110) and (111) sections of the Sigma3 gamma -plot were evaluated. In addition to the sharp cusps occurring at the Sigma3 {111} planes, the further shallower cusps occur at the incoherent Sigma 3 boundaries with the interfacial planes approximately parallel to {322} in one crystal and {11.44} in the other crystal. Flat and curved Sigma9 boundaries were investigated. The break up of Sigma9 boundaries into two Sigma3 boundaries and the relation between the Sigma3 and Sigma 9 gamma-plots was also examined. The (110) section of the Sigma9 gamma-plot was constructed.

  18. Family migration and migrant integration

    NARCIS (Netherlands)

    Bonjour, S.; Kraler, A.; Triandafyllidou, A.

    2016-01-01

    Family migration and integration are intimately related concepts in contemporary policy discourses in major migrant receiving countries. In these discourses, both family related migration as such and the migrant family as an institution are problematised with regard to their relation to integration.

  19. Migration Decisions of Skilled Migrants

    National Research Council Canada - National Science Library

    Eskelä, Elina

    2013-01-01

    ...-speaking destination countries such as the United States. This paper enhances the understanding of student mobility in exploring the migration motives of international students in the case of a less common destination. Keywords International students skilled migration immigration Helsinki Finland Elina Eskel* University of Helsinki, Finland Received 24 Oc...

  20. Challenged by migration: Europe's options

    NARCIS (Netherlands)

    Constant, Amelie F.; Zimmermann, Klaus F.

    2017-01-01

    This paper examines the migration and labour mobility in the European Union and elaborates on their importance for the existence of the EU. Against all measures of success, the current public debate seems to suggest that the political consensus that migration is beneficial is broken. This comes with

  1. 178 GLOBALIZATION, MIGRATION AND UNDERDEVELOPMENT ...

    African Journals Online (AJOL)

    179 imbues them with less international profile. More recently, the refuges problem could in some sense be seen as a form of forced migration, but these are also largely within the continent. The Migration that engages our attention in this paper specifically relates to the voluntary movement of people from one continent to ...

  2. Africa: Setting for Human Migration

    Science.gov (United States)

    Buuba, Babacar Diop

    2007-01-01

    Analysis of African migrations can help to understand prehistoric, historical, ancient modern and contemporaneous migrations. Movements of populations were and continue to be so intense that, for some analysts, they constitute one of the dominant trends of the history and destiny of the very old continent. African and non-African states, whether…

  3. International migration and its regulation

    NARCIS (Netherlands)

    Baganha, M.I.; Doomernik, J.M.J.; Gsir, S.; Hofmann, M.; Kraler, A.; Penninx, R; Kraal, K.; Berger, M.

    2006-01-01

    A fundamental issue in society today, migration has been undergoing a new dynamic transformation, calling for new policy approaches. This new dynamic is not yet understood clearly, let alone that adequate policy answers for ‘the managing’ of these new migration processes and the consequences for

  4. Measuring International Migration in Azerbaijan

    Directory of Open Access Journals (Sweden)

    Serhat Yüksel

    2018-01-01

    Full Text Available International migration significantly affects economic, social, cultural, and political factors of the country. Owing to this situation, it can be said that the reasons of international migration should be analyzed in order to control this problem. The purpose of this study is to determine the influencing factors of international migration in Azerbaijan. In this scope, annual data of 11 explanatory variables for the period of 1995–2015 was analyzed via Multivariate Adaptive Regression Splines (MARS method. According to the results of this analysis, it was identified that people prefer to move other countries in case of high unemployment rates. In addition, the results of the study show that population growth and high mortality rate increases the migration level. While considering these results, it was recommended that Azerbaijan should focus on these aspects to control international migration problem.

  5. Reweighting twisted boundary conditions

    CERN Document Server

    Bussone, Andrea; Hansen, Martin; Pica, Claudio

    2015-01-01

    Imposing twisted boundary conditions on the fermionic fields is a procedure extensively used when evaluating, for example, form factors on the lattice. Twisting is usually performed for one flavour and only in the valence, and this causes a breaking of unitarity. In this work we explore the possibility of restoring unitarity through the reweighting method. We first study some properties of the approach at tree level and then we stochastically evaluate ratios of fermionic determinants for different boundary conditions in order to include them in the gauge averages, avoiding in this way the expensive generation of new configurations for each choice of the twisting angle, $\\theta$. As expected the effect of reweighting is negligible in the case of large volumes but it is important when the volumes are small and the twisting angles are large. In particular we find a measurable effect for the plaquette and the pion correlation function in the case of $\\theta=\\pi/2$ in a volume $16\\times 8^3$, and we observe a syst...

  6. Migration and development in Pakistan: some selected issues.

    Science.gov (United States)

    Irfan, M

    1986-01-01

    Various sources of cross-sectional data were used as a basis for considering some of the interrelationships between migration and development in Pakistan, particularly the effects on the labor-exporting rural areas. The available data yield a range of estimates as to the level of mobility. During the 1970s, around 7-10% of Pakistan's population changed residence. The incidence of migration was higher among females than males. Women's greater propensity to migrate can be attributed primarily to patrilocal marriage customs wherein a significant proportion of females migrate, particularly in the rural areas. According to the 1979 Population, Labor Force and Migration Survey, the share of migrants in the total female population fell from 11.8% to 4.8% when migration for marriage is excluded. In Pakistan, mobility is predominantly local or involves short distances only. Only 19% of the internal migrants crossed provincial boundaries. 29.8% of the flow was from rural to urban areas. The remainder of the volume of internal migration was shared equally by inter-city and urban-to-rural migrants. The coincidence of the timing of marriage and entry into the labor market in individuals' life cycles generated a peak for the 15-24 age group in the age-mobility curve. A positive association exists between education and the propensity to migrate. In terms of origin, the propensity to move exhibited by the higher educational group was higher (33%) in rural areas than in urban areas (10%). 83% of this group from rural areas moved to urban centers; 80% of the same educational background chose another urban center as destination. The data on remittances may suffer both from reporting areas and being unrepresentative. The remittances estimated due to internal migration, on the basis of the PLM survey, amounted to 3 billion rupees in 1978. On average, remittances accounted for 35% of the earnings of the migrants. Average remittances were substantially less than the earnings of

  7. Current Migration Movements in Europe

    Directory of Open Access Journals (Sweden)

    Jelena Zlatković Winter

    2004-09-01

    Full Text Available After a brief historical review of migrations in Europe, the paper focuses on current migration trends and their consequences. At the end of the 1950s, Western Europe began to recruit labour from several Mediterranean countries – Italy, Spain, Portugal and former Yugoslavia, and later from Morocco, Algeria, Tunisia and Turkey. Some countries, such as France, Great Britain and the Netherlands, recruited also workers from their former colonies. In 1970 Germany had the highest absolute number of foreigners, followed by France, and then Switzerland and Belgium. The total number of immigrants in Western Europe was twelve million. During the 1970s mass recruitment of foreign workers was abandoned, and only the arrival of their family members was permitted, which led to family reunification in the countries of employment. Europe closed its borders, with the result that clandestine migration increased. The year 1989 was a turning point in the history of international migrations. The political changes in Central and Eastern Europe brought about mass migration to the West, which culminated in the so-called “mass movement of 1989–1990”. The arrival of ethnic Germans in Germany, migration inside and outside of the territory of the former Soviet Union, an increase in the number of asylum seekers and displaced persons, due to armed conflicts, are – according to the author – the main traits of current migration. The main part of the paper discusses the causes and effects of this mass wave, as well as trends in labour migration, which is still present. The second part of the paper, after presenting a typology of migrations, deals with the complex processes that brought about the formation of new communities and led to the phenomenon of new ethnic minorities and to corresponding migration policies in Western European countries that had to address these issues.

  8. The challenge of migration and health.

    Science.gov (United States)

    Carballo, Manuel

    2006-01-01

    Dr Manuel Carballo of the International Centre for Migration and Health provides the background to migration and its impact on the health of migrating peoples and the health care systems that treat them.

  9. Microfluidics to define leukocyte migration patterns

    NARCIS (Netherlands)

    Boneschansker, Johan

    2017-01-01

    Leukocyte migration into tissues is characteristic of inflammation. In this thesis, we design and validate microfluidic devices that allow for precise quantification of leukocyte migration patterns. Our microfluidic platform can quantify migration patterns using single-cell quantitative metrics that

  10. Migration process control in the modern society

    OpenAIRE

    A R Dimaev

    2009-01-01

    The sociological way of the migration phenomenon can be considered only in complex. As a social science of migration we should understand the social science control, which is based on direct and indirect control of migration process.

  11. Internal and international migration in Nepal.

    Science.gov (United States)

    Kc, B K

    1987-01-01

    Internal and international migration trends in Nepal are reviewed using data from the 1971 and 1981 censuses. The causes and consequences of migration are considered. The need for policies to control migration of all kinds is stressed.

  12. MIGRATION IMPACT ON ECONOMICAL SITUATION

    Directory of Open Access Journals (Sweden)

    Virginia COJOCARU

    2016-01-01

    Full Text Available This paper presents recent trends and flows of labor migration and its impact on economic and social life. Main aim of this research sets up the influence of the migration on the European economics and its competitiveness. Methods of research are: method of comparison, analysis method, method of deduction, method of statistics, modeling method. The economic impact of migration has been intensively studied but is still often driven by ill-informed perceptions, which, in turn, can lead to public antagonism towards migration. These negative views risk jeopardising efforts to adapt migration policies to the new economic and demographic challenges facing many countries. Migration Policy looks at the evidence for how immigrants affect the economy in three main areas: The labour market, public purse and economic growth. In Europe, the scope of labour mobility greatly increased within the EU/EFTA zones following the EU enlargements of 2004, 2007 and 2014-2015. This added to labour markets’ adjustment capacity. Recent estimates suggest that as much as a quarter of the asymmetric labour market shock – that is occurring at different times and with different intensities across countries – may have been absorbed by migration within a year.

  13. On the concept of migration policy

    OpenAIRE

    DZHANSARAYEVA RIMA YERENATOVNA; MALIKOVA SHOLPAN BALTABEKOVNA

    2015-01-01

    The article analyzes existing in the different sources of non-fiction variety of interpretations of the term “migration policy”. The variety of approaches to the concept of “politics” and “the migration process” gives rise to different points of view on the vision of migration policy. Contradictions are clearly seen in the difference in definitions of migration policy. Migration policy a purposeful activity of political institutions, aimed at streamlining and regulation of migration processes...

  14. Migration in two directions.

    Science.gov (United States)

    Slim, Rita; Koussa, Salam; Awada, Hassan; Yaghi, Cesar; Honein, Khalil; Sayegh, Raymond

    2009-01-01

    Percutaneous endoscopic gastrostomy (PEG), the modality of choice for long-term enteral access, is generally a safe procedure but can be associated with many potential complications. Report two different and late complications of PEG in two patients fed at home, leading them to the emergency department. A 75-year-old man and a 14-year-old young man with PEG presented to the emergency department with two different complications related to the gastrostomy tube. The first patient developed fever and deterioration in mental status due to parietal abscess which developed secondary to the migration of the internal button of the gastrostomy tube in the abdominal wall. He was treated with antibiotics and the gastrostomy tube was extracted. The second one presented upper gastrointestinal bleeding due to intestinal perforation at the level of the internal button of the gastrostomy tube. Bleeding and perforation were treated conservatively and he had a good evolution. Persons taking care of patients with PEG tube must be aware of potential complications. The position and the permeability of the tube must be systematically checked before feeding and medical advice should immediately be asked for in case of doubt or in the presence of any alarming sign.

  15. Psychosocial Aspects of Migration

    Directory of Open Access Journals (Sweden)

    Ayla Tuzcu

    2014-02-01

    Full Text Available The incident of migration that occurs as a result of the mobility of individuals between various regions and is considered a social change process brings along various factors. Among these factors, the most important one is the culture of the new society where the immigrant begins to live and the process of adaptation with this culture. Individuals from different cultures are required to live together, cope with differences and overcome the difficulties. The process of adaptation to the new lifestyle might cause the individual to have some feelings such as loneliness, socially isolation, being alienated, being regretful and self-depreciation, and consequently experience a greater stress. Being unable to cope with stress efficiently creates risks in individuals in terms of health problems such as anxiety and depression. Healthcare professionals are required to evaluate life styles, difficulties and coping levels of immigrants in order to protect and develop their mental health. [Psikiyatride Guncel Yaklasimlar - Current Approaches in Psychiatry 2014; 6(1.000: 56-66

  16. Negotiating Cluster Boundaries

    DEFF Research Database (Denmark)

    Giacomin, Valeria

    2017-01-01

    Palm oil was introduced to Malay(si)a as an alternative to natural rubber, inheriting its cluster organizational structure. In the late 1960s, Malaysia became the world’s largest palm oil exporter. Based on archival material from British colonial institutions and agency houses, this paper focuses...... on the governance dynamics that drove institutional change within this cluster during decolonization. The analysis presents three main findings: (i) cluster boundaries are defined by continuous tug-of-war style negotiations between public and private actors; (ii) this interaction produces institutional change...... within the cluster, in the form of cumulative ‘institutional rounds’ – the correction or disruption of existing institutions or the creation of new ones; and (iii) this process leads to a broader inclusion of local actors in the original cluster configuration. The paper challenges the prevalent argument...

  17. Repeated judgment sampling: Boundaries

    Directory of Open Access Journals (Sweden)

    Johannes Muller-Trede

    2011-06-01

    Full Text Available This paper investigates the boundaries of the recent result that eliciting more than one estimate from the same person and averaging these can lead to accuracy gains in judgment tasks. It first examines its generality, analysing whether the kind of question being asked has an effect on the size of potential gains. Experimental results show that the question type matters. Previous results reporting potential accuracy gains are reproduced for year-estimation questions, and extended to questions about percentage shares. On the other hand, no gains are found for general numerical questions. The second part of the paper tests repeated judgment sampling's practical applicability by asking judges to provide a third and final answer on the basis of their first two estimates. In an experiment, the majority of judges do not consistently average their first two answers. As a result, they do not realise the potential accuracy gains from averaging.

  18. Superfluid Boundary Layer.

    Science.gov (United States)

    Stagg, G W; Parker, N G; Barenghi, C F

    2017-03-31

    We model the superfluid flow of liquid helium over the rough surface of a wire (used to experimentally generate turbulence) profiled by atomic force microscopy. Numerical simulations of the Gross-Pitaevskii equation reveal that the sharpest features in the surface induce vortex nucleation both intrinsically (due to the raised local fluid velocity) and extrinsically (providing pinning sites to vortex lines aligned with the flow). Vortex interactions and reconnections contribute to form a dense turbulent layer of vortices with a nonclassical average velocity profile which continually sheds small vortex rings into the bulk. We characterize this layer for various imposed flows. As boundary layers conventionally arise from viscous forces, this result opens up new insight into the nature of superflows.

  19. Public Computation & Boundary Play

    CERN Document Server

    Sengupta, Pratim

    2016-01-01

    In this paper, we introduce 'public computation' as a genre of learning environments that can be used to radically broaden public participation in authentic, computation-enabled STEM disciplinary practices. Our paradigmatic approach utilizes open source software designed for professional scientists, engineers and digital artists, and situates them in an undiluted form, alongside live and archived expert support, in a public space. We present a case study of DigiPlay, a prototypical public computation space we designed at the University of Calgary, where users can interact directly with scientific simulations as well as the underlying open source code using an array of massive multi- touch screens. We argue that in such a space, public interactions with the code can be thought of as boundary work and play, through which public participation becomes legitimate scientific act, as the public engages in scientific creation through truly open-ended explorations with the code.

  20. Challenging the Boundaries

    DEFF Research Database (Denmark)

    Nørgaard, Nina

    2004-01-01

    to explore in the study and teaching of foreign languages. Not only may linguistics and literature be employed to shed light on each other, the insights gained may furthermore prove useful in a broader context in our foreign language studies. The article begins with a brief introduction to literary...... linguistics in general and to Hallidayan linguistics in particular. The theoretical framework thus laid out, it is exemplified how Halliday's theory of language may be employed in the analysis of literature. The article concludes by considering the possible status of literary linguistics in a broader......To many people, challenging the boundaries between the traditional disciplines in foreign language studies means doing cultural studies. The aim of this article is to pull in a different direction by suggesting how the interface between linguistics and literature may be another fertile field...

  1. The Plasmasphere Boundary Layer

    Directory of Open Access Journals (Sweden)

    D. L. Carpenter

    2004-12-01

    Full Text Available As an inner magnetospheric phenomenon the plasmapause region is of interest for a number of reasons, one being the occurrence there of geophysically important interactions between the plasmas of the hot plasma sheet and of the cool plasmasphere. There is a need for a conceptual framework within which to examine and discuss these interactions and their consequences, and we therefore suggest that the plasmapause region be called the Plasmasphere Boundary Layer, or PBL. Such a term has been slow to emerge because of the complexity and variability of the plasma populations that can exist near the plasmapause and because of the variety of criteria used to identify the plasmapause in experimental data. Furthermore, and quite importantly in our view, a substantial obstacle to the consideration of the plasmapause region as a boundary layer has been the longstanding tendency of textbooks on space physics to limit introductory material on the plasmapause phenomenon to zeroth order descriptions in terms of ideal MHD theory, thus implying that the plasmasphere is relatively well understood. A textbook may introduce the concept of shielding of the inner magnetosphere from perturbing convection electric fields, but attention is not usually paid to the variety of physical processes reported to occur in the PBL, such as heating, instabilities, and fast longitudinal flows, processes which must play roles in plasmasphere dynamics in concert with the flow regimes associated with the major dynamo sources of electric fields. We believe that through the use of the PBL concept in future textbook discussions of the plasmasphere and in scientific communications, much progress can be made on longstanding questions about the physics involved in the formation of the plasmapause and in the cycles of erosion and recovery of the plasmasphere. Key words. Magnetospheric physics (plasmasphere; plasma convection; MHD waves and instabilities

  2. The Plasmasphere Boundary Layer

    Directory of Open Access Journals (Sweden)

    D. L. Carpenter

    2004-12-01

    Full Text Available As an inner magnetospheric phenomenon the plasmapause region is of interest for a number of reasons, one being the occurrence there of geophysically important interactions between the plasmas of the hot plasma sheet and of the cool plasmasphere. There is a need for a conceptual framework within which to examine and discuss these interactions and their consequences, and we therefore suggest that the plasmapause region be called the Plasmasphere Boundary Layer, or PBL. Such a term has been slow to emerge because of the complexity and variability of the plasma populations that can exist near the plasmapause and because of the variety of criteria used to identify the plasmapause in experimental data. Furthermore, and quite importantly in our view, a substantial obstacle to the consideration of the plasmapause region as a boundary layer has been the longstanding tendency of textbooks on space physics to limit introductory material on the plasmapause phenomenon to zeroth order descriptions in terms of ideal MHD theory, thus implying that the plasmasphere is relatively well understood. A textbook may introduce the concept of shielding of the inner magnetosphere from perturbing convection electric fields, but attention is not usually paid to the variety of physical processes reported to occur in the PBL, such as heating, instabilities, and fast longitudinal flows, processes which must play roles in plasmasphere dynamics in concert with the flow regimes associated with the major dynamo sources of electric fields. We believe that through the use of the PBL concept in future textbook discussions of the plasmasphere and in scientific communications, much progress can be made on longstanding questions about the physics involved in the formation of the plasmapause and in the cycles of erosion and recovery of the plasmasphere.

    Key words. Magnetospheric physics (plasmasphere; plasma convection; MHD waves and instabilities

  3. Population commission discusses international migration.

    Science.gov (United States)

    1997-01-01

    At the 30th session of the Commission on Population and Development during February 24-28, 1997, international migration was the main topic, with special linkages between migration and development and on gender issues and the family. New and emerging issues were also considered. Members stressed the need for more reliable data on migration, the direction of migrants flows, and the characteristics of migrants. The Commission requested a task force on basic social services to hold a technical symposium of experts on international migration in 1998. Its chair, Dr. Nafis Sadik, said that migration issues should based on the reality of choice not on coercive measures or quotas. Almost half of the migrants globally are women. The Commission was given a new impetus by the International Conference on Population and Development held at Cairo in 1994. Migration pressures intensified in the second half of the 1980s and in the early 1990s, creating areas of concern: the negative impact of short-term migration on working conditions in host countries; migration pressures emanating from climatic change; the protection of migrant women and their children; the right of receiving countries to regulate access to their territory; the adverse consequences of forced migration; the situation of persons whose asylum claims have been rejected; the trafficking in women and children, prostitution and coercive adoption; and the sudden and massive arrival of refugees in need of international protection. The 1998 session of the Commission will feature the theme of health and mortality, with special emphasis on the linkages between health and development and on gender and age.

  4. In Situ Studies on the Irradiation-Induced Twin Boundary-Defect Interactions in Cu

    Science.gov (United States)

    Fan, C.; Li, Jin; Fan, Zhe; Wang, H.; Zhang, X.

    2017-11-01

    Polycrystalline Cu films with nanoscale annealing twins are subjected to in situ Kr++ ion irradiation at room temperature inside a transmission electron microscope up to a dose of 1 displacement-per-atom. Radiation induces prominent migration of incoherent twin boundaries. Depending on twin thickness, three types of twin boundary evolutions are observed, including rapid detwinning, gradual detwinning, and self-healing. The mechanism of twin thickness-dependent evolution of microstructures is discussed. This study provides further evidence on twin boundary-defect interactions and may assist the design of radiation-tolerant twinned metallic materials.

  5. Migration and the Wage Curve:

    DEFF Research Database (Denmark)

    Brücker, Herbert; Jahn, Elke J.

      Based on a wage curve approach we examine the labor market effects of migration in Germany. The wage curve relies on the assumption that wages respond to a change in the unemployment rate, albeit imperfectly. This allows one to derive the wage and employment effects of migration simultaneously...... with a vocational degree. The wage and employment effects of migration are moderate: a 1 percent increase in the German labor force through immigration increases the aggregate unemployment rate by less than 0.1 percentage points and reduces average wages by less 0.1 percent. While native workers benefit from...

  6. Rural migration and health care

    DEFF Research Database (Denmark)

    Svendsen, Gunnar Lind Haase; Jensen, Marit Vatn

    This literature study focuses on possible links between access to health services and migration in rural areas. Why do people move to or from rural areas or why do they stay? What determines where people settle? And, in this context, do local health care services play an important or minor role......, or no role at all? First, the paper reports on key findings from rural migration studies, in order to shed light on two migration trends: urbanization and counter-urbanization. Then we take a closer look on settlement preferences in rural areas, including the impact of health care facilities. Finally, we end...

  7. Countering inbreeding with migration 1. Migration from unrelated ...

    African Journals Online (AJOL)

    l2-(1 -rn)(t -m)l|,. (1.14) with all terms as defined fbr (1.5). Equation (1.14) does not appear to be directly amenable to the development of general rules for the limitation ... effects of migration and restricted population size with equal numbers of the two sexes and with only male migration. N'lale rnigrant number. Herd size l1 .'l.

  8. Grain boundary melting in ice

    OpenAIRE

    Thomson, E. S.; Hansen-Goos, Hendrik; Wilen, L. A.; Wettlaufer, J. S.

    2012-01-01

    We describe an optical scattering study of grain boundary premelting in water ice. Ubiquitous long ranged attractive polarization forces act to suppress grain boundary melting whereas repulsive forces originating in screened Coulomb interactions and classical colligative effects enhance it. The liquid enhancing effects can be manipulated by adding dopant ions to the system. For all measured grain boundaries this leads to increasing premelted film thickness with increasing electrolyte concentr...

  9. Conformal boundaries of warped products

    DEFF Research Database (Denmark)

    Kokkendorff, Simon Lyngby

    2006-01-01

    In this note we prove a result on how to determine the conformal boundary of a type of warped product of two length spaces in terms of the individual conformal boundaries. In the situation, that we treat, the warping and conformal distortion functions are functions of distance to a base point....... The result is applied to produce examples of CAT(0)-spaces, where the conformal and ideal boundaries differ in interesting ways....

  10. The Boundary Function Method. Fundamentals

    Science.gov (United States)

    Kot, V. A.

    2017-03-01

    The boundary function method is proposed for solving applied problems of mathematical physics in the region defined by a partial differential equation of the general form involving constant or variable coefficients with a Dirichlet, Neumann, or Robin boundary condition. In this method, the desired function is defined by a power polynomial, and a boundary function represented in the form of the desired function or its derivative at one of the boundary points is introduced. Different sequences of boundary equations have been set up with the use of differential operators. Systems of linear algebraic equations constructed on the basis of these sequences allow one to determine the coefficients of a power polynomial. Constitutive equations have been derived for initial boundary-value problems of all the main types. With these equations, an initial boundary-value problem is transformed into the Cauchy problem for the boundary function. The determination of the boundary function by its derivative with respect to the time coordinate completes the solution of the problem.

  11. Analysis of turbulent boundary layers

    CERN Document Server

    Cebeci, Tuncer

    1974-01-01

    Analysis of Turbulent Boundary Layers focuses on turbulent flows meeting the requirements for the boundary-layer or thin-shear-layer approximations. Its approach is devising relatively fundamental, and often subtle, empirical engineering correlations, which are then introduced into various forms of describing equations for final solution. After introducing the topic on turbulence, the book examines the conservation equations for compressible turbulent flows, boundary-layer equations, and general behavior of turbulent boundary layers. The latter chapters describe the CS method for calculati

  12. What turns migrants into ethnic minorities at work? : Factors Erecting Ethnic Boundaries among Dutch Police Officers

    NARCIS (Netherlands)

    Siebers, Hans

    Transnational migration flows have revitalised the interest in ethnicity in social sciences. The ethnic boundary approach (Barth, Wimmer) argues for a non-essentialist understanding of ethnicity and calls for detecting the factors that turn migrants into ethnic minorities. Based on ethnographic

  13. Migration at the micro-scale: intra-parochial movements in rural Normandy, 1946-54.

    Science.gov (United States)

    White, P E

    1981-01-01

    "Most working definitions of migration accept that only movements across local authority boundaries can normally be dealt with: by the use of questionnaire surveys certain urban studies have examined intra-unit moves but few non-urban migration studies have been able to penetrate below the level of local authority boundaries. In this paper use is made of various unpublished documents available in connection with population censuses in France from which it is possible to examine migration within rural communes for the intercensal period from 1946 to 1954. Twelve communes were investigated and the emerging picture of intra-parochial migrants have been compared with that of inter-parochial movers." The author notes "differences in age-structure between the two groups. Net movement takes place up the settlement hierarchy within each 'commune', whilst the reasons for movement show that between village-centres and outlying settlements there are certain social cleavages." excerpt

  14. Symbolic Boundary Work in Schools: Demarcating and Denying Ethnic Boundaries

    Science.gov (United States)

    Tabib-Calif, Yosepha; Lomsky-Feder, Edna

    2014-01-01

    This article examines the symbolic boundary work that is carried out at a school whose student population is heterogeneous in terms of ethnicity and class. Based on ethnography, the article demonstrates how the school's staff seeks to neutralize ethnic boundaries and their accompanying discourse, while the pupils try to bring ethnic…

  15. [International migration: 1979].

    Science.gov (United States)

    1981-01-01

    Statistics on international migration in Panama in 1979 are provided for the 3 airports, 6 seaports, and 2 border crossings used by international travelers. The categories of visitors, temporary visitors, immigrants, and residents among those entering and leaving the country are defined and the data collection procedures are briefly specified. Between 1975-79, the number of persons entering the country through all points increased from 392,449 to 520,454, while the number departing increased from 397,759 to a figure provisionally estimated at 514,250. In 1979, 317,303 men and 203,151 women entered the country, 427,527 by air, 89,764 by land, and 3,163 by sea. 473 men and 355 women immigrated, all arriving by air. 391,502 of those entering were visitors, 2,407 were temporary visitors, and 98,589 were residents, of whom 81,462 were Panamanian and 17,127 foreign. Another table indicates the number of persons by category entering at each point by month; December had the highest number of arrivals, 56,070, followed by July, with 47,889. Other tables indicate the number of arrivals by category according to country of nationality and country of permanent residence; the number of arrivals by sex and category in 5-year age groups; the number of visitors entering for motives related to travel according to nationality and country of residence; the number entering by duration of stay, according to reasons for travel and country of residence; the number entering through the airport at Tocumen or the border crossing at Paso de Canoa, by motives for travel, according to country of residence, and by sex and age; and the number of returning Panamanian residents by port of entry and nationality, according to point of origin. Data are also provided on the number leaving by category for each point of departure and month of departure.

  16. Mechanisms of ripple migration on a natural sand bed under waves

    Science.gov (United States)

    Carlson, E.; Foster, D. L.

    2016-02-01

    In nearshore environments, the wave bottom boundary layer is of particular importance to bedform migration and evolution as it is the location of energy transfer from the water column to the bed. This effort examines the mechanisms responsible for bedform evolution and migration. In a field scale laboratory study, sand ripple dynamics were measured using particle image velocimetry. Both monotonic (T = 4 s, 8 s), bimodal (wave pair T = 3.7, 4.3 s), and solitary wave cases were examined. Bedform states included orbital and anorbital rippled beds with wavelengths ranging from 5 to 15 cm. During cases of moderately high energy, time series of instantaneous ripple migration rates oscillated with the same frequency as the surface waves. The oscillatory ripple migration signature was asymmetric, with higher amplitudes during onshore directed movement. This asymmetry leads to a net onshore migration, ranging from 0.1 to 0.6 cm/min in the wave conditions mentioned. The cyclic motion of the ripple field was compared to concomitant transfer mechanisms affecting the boundary layer dynamics including: bed shear stress, coherent structure generation, and free stream velocity. Coherent structures were identified using the swirling strength criterion, and were present during each half wave developing in the ripple troughs. Two estimates of bed shear stress were made: 1) Meyer-Peter Muller method using the bed migration to determine the necessary stress and 2) double averaging of the velocity field and partitioning into components of stress, following the methods of Rodriguez-Abudo and Foster (2014). Peak ripple migration rates occurred during strengthening onshore flow, which coincides with peak bed shear stresses and the onset of coherent structure formation. Higher energy bimodal wave groups caused periods of high suspension which were coincident with peak onshore migrations, during the low velocity periods of the bimodal forcing the bed did not migrate.

  17. The migration challenge for PAYG

    Czech Academy of Sciences Publication Activity Database

    Aslanyan, Gurgen

    2014-01-01

    Roč. 27, č. 4 (2014), s. 1023-1038 ISSN 0933-1433 Institutional support: PRVOUK-P23 Keywords : public pension s * PAYG * unskilled migration Subject RIV: AH - Economics Impact factor: 1.109, year: 2014

  18. The migration challenge for PAYG

    Czech Academy of Sciences Publication Activity Database

    Aslanyan, Gurgen

    2014-01-01

    Roč. 27, č. 4 (2014), s. 1023-1038 ISSN 0933-1433 Institutional support: RVO:67985998 Keywords : public pension s * PAYG * unskilled migration Subject RIV: AH - Economics Impact factor: 1.109, year: 2014

  19. Migration, distress and cultural identity

    National Research Council Canada - National Science Library

    Bhugra, Dinesh

    2004-01-01

    ...; they also attempt to settle down by either assimilation or biculturalism. In this paper, various hypotheses explaining the act of migration and its relationship with mental distress are described...

  20. Collaboration in Healthcare Through Boundary Work and Boundary Objects

    DEFF Research Database (Denmark)

    Meier, Ninna

    2015-01-01

    This article contributes to our understanding of how boundary work is practiced in healthcare settings. Previous studies have shown how boundaries are constantly changing, multiple, and co-existing, and can also be relatively stable cognitive and social distinctions between individuals and groups....... In highly specialized, knowledge-intensive organizations such as healthcare organizations, organizational, professional, and disciplinary boundaries mark the formal structure and division of work. Collaboration and coordination across these boundaries are essential to minimizing gaps in patient care......, but also may be challenging to achieve in practice. By drawing on data from an ethnographic study of two hospital wards, this article investigates practices of cross-disciplinary and professional collaboration and adds to our knowledge of how this kind of boundary work is produced in context. Moreover...

  1. Lateral migration of a capsule in a parabolic flow.

    Science.gov (United States)

    Nix, S; Imai, Y; Ishikawa, T

    2016-07-26

    Red blood cells migrate to the center of the blood vessel in a process called axial migration, while other blood cells, such as white blood cells and platelets, are disproportionately found near the blood vessel wall. However, much is still unknown concerning the lateral migration of cells in the blood; the specific effect of hydrodynamic factors such as a wall or a shear gradient is still unclear. In this study, we investigate the lateral migration of a capsule using the boundary integral method, in order to compute exactly an infinite computational domain for an unbounded parabolic flow and a semi-infinite computational domain for a near-wall parabolic flow in the limit of Stokes flow. We show that the capsule lift velocity in an unbounded parabolic flow is linear with respect to the shear gradient, while the lift velocity in a near-wall parabolic flow is dependent on the distance to the wall. Then, using these relations, we give an estimation of the relative effect of the shear gradient as a function of channel width and distance between the capsule and the wall. This estimation can be used to determine cases in which the effect of the shear gradient or wall can be neglected; for example, the formation of the cell-free layer in blood vessels is determined to be unaffected by the magnitude of the shear gradient. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Imaging of Subsurface Faults using Refraction Migration with Fault Flooding

    KAUST Repository

    Metwally, Ahmed Mohsen Hassan

    2017-05-31

    We propose a novel method for imaging shallow faults by migration of transmitted refraction arrivals. The assumption is that there is a significant velocity contrast across the fault boundary that is underlain by a refracting interface. This procedure, denoted as refraction migration with fault flooding, largely overcomes the difficulty in imaging shallow faults with seismic surveys. Numerical results successfully validate this method on three synthetic examples and two field-data sets. The first field-data set is next to the Gulf of Aqaba and the second example is from a seismic profile recorded in Arizona. The faults detected by refraction migration in the Gulf of Aqaba data were in agreement with those indicated in a P-velocity tomogram. However, a new fault is detected at the end of the migration image that is not clearly seen in the traveltime tomogram. This result is similar to that for the Arizona data where the refraction image showed faults consistent with those seen in the P-velocity tomogram, except it also detected an antithetic fault at the end of the line. This fault cannot be clearly seen in the traveltime tomogram due to the limited ray coverage.

  3. Migration of the Nellix endoprosthesis.

    Science.gov (United States)

    England, Andrew; Torella, Francesco; Fisher, Robert K; McWilliams, Richard G

    2016-08-01

    This study reports the incidence and sequelae of migration of the Nellix (Endologix Inc, Irvine, Calif) endoprosthesis after endovascular aneurysm sealing. A review was performed of the follow-up imaging of all endovascular aneurysm sealing patients in a university hospital endovascular program who had a minimum follow-up of 1 year. The first postoperative and latest follow-up computed tomography scans were used to measure the distances between the proximal and distal borders of the stent grafts relative to reference vessels using a previously validated technique. Device migration was based on previously established criteria and defined as any stent graft movement of ≥4 mm related to a predefined reference vessel. Device movement in a caudal direction was given a positive value, and movement in a cranial direction was denoted by a negative value. Eighteen patients (35 stent grafts) were eligible for inclusion in this retrospective review. The mean preoperative abdominal aortic aneurysm diameter was 57 mm (standard deviation [SD], 5; range, 50-67 mm) and aortic neck length was 30 mm (SD, 16; range, 6-62 mm). Proximal migration, according to study definitions, was identified in six stent grafts (17%), all in a caudal direction. At 1 year the mean proximal migration distance was +6.6 mm (SD, 1.6; range, +4.7-+9.2 mm). Migration occurred in a single stent graft in four patients and bilaterally in one. No distal migration occurred. Proximal migration of the Nellix endoprosthesis does occur and was without any sequelae in our series. Further investigations into the long-term positional stability of the Nellix device, together with a more thorough understanding of the etiology and consequences of migration, are required. Copyright © 2016 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

  4. Metallicity, planetary formation and migration

    OpenAIRE

    Livio, M.; Pringle, J. E.

    2003-01-01

    Recent observations show a clear correlation between the probability of hosting a planet and the metallicity of the parent star. Since radial velocity surveys are biased, however, towards detecting planets with short orbital periods, the probability-metallicity correlation could merely reflect a dependence of migration rates on metallicity. We investigated the possibility, but find no basis to suggest that the migration process is sensitive to the metallicity. The indication is, therefore, th...

  5. Computational Economic Modeling of Migration

    OpenAIRE

    Klabunde, Anna

    2014-01-01

    In this paper an agent-based model of endogenously evolving migrant networks is developed to identify the determinants of migration and return decisions. Individuals are connected by links, the strength of which declines over time and distance. Methodologically, this paper combines parameterization using data from the Mexican Migration Project with calibration. It is shown that expected earnings, an idiosyncratic home bias, network ties to other migrants, strength of links to the home country...

  6. Boundary-Layer & health

    Science.gov (United States)

    Costigliola, V.

    2010-09-01

    It has long been known that specific atmospheric processes, such as weather and longer-term climatic fluctuations, affect human health. The biometeorological literature refers to this relationship as meteorotropism, defined as a change in an organism that is correlated with a change in atmospheric conditions. Plenty of (patho)physiological functions are affected by those conditions - like the respiratory diseases - and currently it is difficult to put any limits for pathologies developed in reply. Nowadays the importance of atmospheric boundary layer and health is increasingly recognised. A number of epidemiologic studies have reported associations between ambient concentrations of air pollution, specifically particulate pollution, and adverse health effects, even at the relatively low concentrations of pollution found. Since 1995 there have been over twenty-one studies from four continents that have explicitly examined the association between ambient air pollutant mixes and daily mortality. Statistically significant and positive associations have been reported in data from various locations around the world, all with varying air pollutant concentrations, weather conditions, population characteristics and public health policies. Particular role has been given to atmospheric boundary layer processes, the impact of which for specific patient-cohort is, however, not well understood till now. Assessing and monitoring air quality are thus fundamental to improve Europe's welfare. One of current projects run by the "European Medical Association" - PASODOBLE will develop and demonstrate user-driven downstream information services for the regional and local air quality sectors by combining space-based and in-situ data with models in 4 thematic service lines: - Health community support for hospitals, pharmacies, doctors and people at risk - Public information for regions, cities, tourist industry and sporting event organizers - Compliance monitoring support on particulate

  7. European Integration and Labour Migration

    Directory of Open Access Journals (Sweden)

    Julda Kielyte

    2010-11-01

    Full Text Available The present paper studies how European integration might affect the migration of workers in the enlarged EU. Unlike the reduced-form migration models, we base our empirical analysis on the theory of economic geography à la Krugman (1991, which provides an alternative modelling of migration pull and push factors. Parameters of the theoretical model are estimated econometrically using historical migration data. Our empirical findings suggest that European integration would trigger selective migration between the countries in the enlarged EU. In the Baltics, Lithuania would gain about 7.25% of the total work force. In the Visegrád Four, the share of the mobile labour force would increase the most in Hungary, 8.35%, compared to the pre-integration state. Our predictions for the East-West migration are moderate and lower than those of reduced-form models: between 5.44% (from the Baltics and 3.61% (from the Visegrád Four would emigrate to the EU North. Because migrants not only follow market potential, but also shape the region’s market potential, the long-run agglomeration forces are sufficiently weak to make a swift emergence of a core-periphery pattern in the enlarged EU very unlikely.

  8. The dynamics of mass migration

    Science.gov (United States)

    Massey, Douglas S.; Zenteno, Rene M.

    1999-01-01

    We specify a set of equations defining a dynamic model of international migration and estimate its parameters by using data specially collected in Mexico. We then used it to project the a hypothetical Mexican community population forward in time. Beginning with a stable population of 10,000 people, we project ahead 50 years under three different assumptions: no international migration; constant probabilities of in- and out-migration, and dynamic schedules of out- and in-migration that change as migratory experience accumulates. This exercise represents an attempt to model the self-feeding character of international migration noted by prior observers and theorists. Our model quantifies the mechanisms of cumulative causation predicted by social capital theory and illustrates the shortcomings of standard projection methodologies. The failure to model dynamically changing migration schedules yields a 5% overstatement of the projected size of the Mexican population after 50 years, an 11% understatement of the total number of U.S. migrants, a 15% understatement of the prevalence of U.S. migratory experience in the Mexican population, and an 85% understatement of the size of the Mexican population living in the United States. PMID:10220465

  9. Microstructure and crystallographic preferred orientation of polycrystalline microgarnet aggregates developed during progressive creep, recovery, and grain boundary sliding

    Science.gov (United States)

    Massey, M.A.; Prior, D.J.; Moecher, D.P.

    2011-01-01

    Optical microscopy, electron probe microanalysis, and electron backscatter diffraction methods have been used to examine a broad range of garnet microstructures within a high strain zone that marks the western margin of a major transpression zone in the southern New England Appalachians. Garnet accommodated variable states of finite strain, expressed as low strain porphyroclasts (Type 1), high strain polycrystalline aggregates (Type 2), and transitional morphologies (Type 3) that range between these end members. Type 1 behaved as rigid porphyroclasts and is characterized by four concentric Ca growth zones. Type 2 help define foliation and lineation, are characterized by three Ca zones, and possess a consistent bulk crystallographic preferred orientation of (100) symmetrical to the tectonic fabric. Type 3 show variable degrees of porphyroclast associated with aggregate, where porphyroclasts display complex compositional zoning that corresponds to lattice distortion, low-angle boundaries, and subgrains, and aggregate CPO mimics porphyroclast orientation. All aggregates accommodated a significant proportion of greenschist facies deformation through grain boundary sliding, grain rotation and impingement, and pressure solution, which lead to a cohesive behavior and overall strain hardening of the aggregates. The characteristic CPO could not have been developed in this manner, and was the result of an older phase of partitioned amphibolite facies dislocation creep, recovery including chemical segregation, and recrystallization of porphyroclasts. This study demonstrates the significance of strain accommodation within garnet and its affect on composition under a range of PT conditions, and emphasizes the importance of utilizing EBSD methods with studies that rely upon a sound understanding of garnet. ?? 2010 Elsevier Ltd.

  10. Seismic link at plate boundary

    Indian Academy of Sciences (India)

    transfer between two major faults, and parallel to the geothermal area extension. 1. Introduction. Plate boundaries are the zones where most earth dynamics are focussed. The complexity of tectonic boundaries draws attention to them as the largest earthquakes are felt in these areas and they elicit the natural hazard of ...

  11. Exclusion Process with Slow Boundary

    Science.gov (United States)

    Baldasso, Rangel; Menezes, Otávio; Neumann, Adriana; Souza, Rafael R.

    2017-06-01

    We study the hydrodynamic and the hydrostatic behavior of the simple symmetric exclusion process with slow boundary. The term slow boundary means that particles can be born or die at the boundary sites, at a rate proportional to N^{-θ }, where θ > 0 and N is the scaling parameter. In the bulk, the particles exchange rate is equal to 1. In the hydrostatic scenario, we obtain three different linear profiles, depending on the value of the parameter θ ; in the hydrodynamic scenario, we obtain that the time evolution of the spatial density of particles, in the diffusive scaling, is given by the weak solution of the heat equation, with boundary conditions that depend on θ . If θ \\in (0,1), we get Dirichlet boundary conditions, (which is the same behavior if θ =0, see Farfán in Hydrostatics, statical and dynamical large deviations of boundary driven gradient symmetric exclusion processes, 2008); if θ =1, we get Robin boundary conditions; and, if θ \\in (1,∞), we get Neumann boundary conditions.

  12. Fuzzy Boundary and Fuzzy Semiboundary

    OpenAIRE

    Athar, M.; Ahmad, B.

    2008-01-01

    We present several properties of fuzzy boundary and fuzzy semiboundary which have been supported by examples. Properties of fuzzy semi-interior, fuzzy semiclosure, fuzzy boundary, and fuzzy semiboundary have been obtained in product-related spaces. We give necessary conditions for fuzzy continuous (resp., fuzzy semicontinuous, fuzzy irresolute) functions. Moreover, fuzzy continuous (resp., fuzzy semicontinuous, fuzzy irresolute) functions have been characterized via fuzzy...

  13. Nucleation of small angle boundaries

    CSIR Research Space (South Africa)

    Nabarro, FRN

    1996-12-01

    Full Text Available The internal stresses induced by the strain gradients in an array of lattice cells delineated by low-angle dislocation boundaries are partially relieved by the creation of new low-angle boundaries. This is shown to be a first-order transition...

  14. How Firms Make Boundary Decisions

    DEFF Research Database (Denmark)

    Dobrajska, Magdalena; Billinger, Stephan; Becker, Markus

    2014-01-01

    We report findings from an analysis of 234 firm boundary decisions that a manufacturing firm has made during a 10 year period. Extensive interviews with all major decision makers located both at the headquarters and subsidiaries allow us to examine (a) who was involved in each boundary decision...

  15. Seismicity patterns in the Himalayan plate boundary and identification of the areas of high seismic potential

    Science.gov (United States)

    Khattri, K. M.; Tyagi, A. K.

    1983-07-01

    Space-time distribution of earthquakes along the Himalayan plate boundary has been investigated with a view to discerning fluctuations in seismicity rates associated with great earthquakes, the possibilities of epicentre migration and gaps in seismic activity. Data from 1800 to 1976 were considered. This study shows that all great earthquakes ( M ⩾ 8.0) were preceded by seismically quiescent periods of at least 19 years. Furthermore, earthquake quiescence has also been recognised to follow the great earthquakes. Three possible trends of migration of epicentres of great earthquakes have been recognised: (1) The first trend starts from the 1905 Kangra earthquake, the epicentres of subsequent earthquakes migrating eastwards along the plate boundary. (2) The second trend of migration starts from the great Nepal earthquake of 1833 associated with eastward migration. (3) The third trend commences from the great Assam earthquake of 1897 and shows a westward migration of earthquake epicentres. The middle section of the Himalayan convergent plate boundary (80°E to 90°E), in general, displays a relatively low level of seismicity as compared to the adjacent sections. A remarkable decrease in seismicity following the year 1970 has been observed along a section of the Himalaya which lies to the east of the rupture zone of the great 1905 Kangra earthquake. Since 1970 the seismicity rate has also dropped in the region lying in between the rupture zones of the great Assam earthquakes of 1897 and 1950, as has earlier been reported by Khattri and Wyss (1978). Such decreases in the level of seismicity along active plate boundaries have been demonstrated to be indicative of building up of stresses leading to future great earthquakes (Mogi, 1969; McCann et al., 1979).

  16. Prediction of dislocation boundary characteristics

    DEFF Research Database (Denmark)

    Winther, Grethe

    Plastic deformation of both fcc and bcc metals of medium to high stacking fault energy is known to result in dislocation patterning in the form of cells and extended planar dislocation boundaries. The latter align with specific crystallographic planes, which depend on the crystallographic....... Crystal plasticity calculations combined with the hypothesis that these boundaries separate domains with local differences in the slip system activity are introduced to address precise prediction of the experimentally observed boundaries. The presentation will focus on two cases from fcc metals...... orientation of the grain [1]. For selected boundaries it has been experimentally verified that the boundaries consist of fairly regular networks of dislocations, which come from the active slip systems [2]. The networks have been analyzed within the framework of Low-Energy-Dislocation-Structures (LEDS...

  17. Boundary Drawing in Clinical Work

    DEFF Research Database (Denmark)

    Meier, Ninna

    The aim of this paper is to show how health care professionals temporarily dissolve and redraw boundaries in their everyday work, in order to coordinate clinical work and facilitate collaboration in patient pathways. Boundaries are social constructions that help us make sense of our complex, social...... world. In health care, formal boundaries are important distinctions that separate health care practitioners into medical specialties, professions and organizational departments. But clinical work also relies on the ability of health care practitioners to collaborate around patients in formal...... arrangements or emergent, temporary teams. Focusing on the cognitive and social boundaries we draw to establish identity and connection (to a profession, team or person) the paper shows how health care professionals can use inter-personal relationships to temporarily dismiss formal boundaries. By redrawing...

  18. Distributed Tuning of Boundary Resources

    DEFF Research Database (Denmark)

    Eaton, Ben; Elaluf-Calderwood, Silvia; Sørensen, Carsten

    2015-01-01

    in the context of a paradoxical tension between the logic of generative and democratic innovations and the logic of infrastructural control. Boundary resources play a critical role in managing the tension as a firm that owns the infrastructure can secure its control over the service system while independent...... firms can participate in the service system. In this study, we explore the evolution of boundary resources. Drawing on Pickering’s (1993) and Barrett et al.’s (2012) conceptualizations of tuning, the paper seeks to forward our understanding of how heterogeneous actors engage in the tuning of boundary...... resources within Apple’s iOS service system. We conduct an embedded case study of Apple’s iOS service system with an in-depth analysis of 4,664 blog articles concerned with 30 boundary resources covering 6 distinct themes. Our analysis reveals that boundary resources of service systems enabled by digital...

  19. Brain response to prosodic boundary cues depends on boundary position

    Directory of Open Access Journals (Sweden)

    Julia eHolzgrefe

    2013-07-01

    Full Text Available Prosodic information is crucial for spoken language comprehension and especially for syntactic parsing, because prosodic cues guide the hearer’s syntactic analysis. The time course and mechanisms of this interplay of prosody and syntax are not yet well understood. In particular, there is an ongoing debate whether local prosodic cues are taken into account automatically or whether they are processed in relation to the global prosodic context in which they appear. The present study explores whether the perception of a prosodic boundary is affected by its position within an utterance. In an event-related potential (ERP study we tested if the brain response evoked by the prosodic boundary differs when the boundary occurs early in a list of three names connected by conjunctions (i.e., after the first name as compared to later in the utterance (i.e., after the second name. A closure positive shift (CPS — marking the processing of a prosodic phrase boundary — was elicited only for stimuli with a late boundary, but not for stimuli with an early boundary. This result is further evidence for an immediate integration of prosodic information into the parsing of an utterance. In addition, it shows that the processing of prosodic boundary cues depends on the previously processed information from the preceding prosodic context.

  20. Linking Poverty, Irregular Migration and Human Trafficking ...

    African Journals Online (AJOL)

    Migration literature suggests that poverty, irregular migration and human trafficking are causally linked. However, empirical studies linking these aspects of migration are scarce. This is because, as clandestine activities, data collection on these aspects of migration presents serious challenges. As a result of these ...

  1. Rural-Urban Migration in Colombia.

    Science.gov (United States)

    Schultz, T. Paul

    The rural-urban migration pattern in Colombia during the last 25 years has resulted in a population increase in urban areas from 30 to 52 percent of the total population. This study explores the causes of internal migration. Migration rates are estimated for various groups in the population to clarify who migrates and to where. A model of…

  2. Towards a new understanding of migration timing

    NARCIS (Netherlands)

    Kölzsch, Andrea; Muskens, Gerard; Kruckenberg, Helmut; Glazov, Peter; Weinzierl, Rolf; Nolet, Bart A.; Wikelski, Martin

    2016-01-01

    According to migration theory and several empirical studies, long-distance migrants are more time-limited during spring migration and should therefore migrate faster in spring than in autumn. Competition for the best breeding sites is supposed to be the main driver, but timing of migration is

  3. Distance and Intrastate College Student Migration

    Science.gov (United States)

    Alm, James; Winters, John V.

    2009-01-01

    Most studies of student migration focus on "interstate" migration of college students, largely because the aggregate data typically used are limited in geographic specificity to states. However, interstate migration is only a small part of the total student migration. Public institutions generally get most of their students from within…

  4. Bubble dynamics in a compressible liquid in contact with a rigid boundary.

    Science.gov (United States)

    Wang, Qianxi; Liu, Wenke; Zhang, A M; Sui, Yi

    2015-10-06

    A bubble initiated near a rigid boundary may be almost in contact with the boundary because of its expansion and migration to the boundary, where a thin layer of water forms between the bubble and the boundary thereafter. This phenomenon is modelled using the weakly compressible theory coupled with the boundary integral method. The wall effects are modelled using the imaging method. The numerical instabilities caused by the near contact of the bubble surface with the boundary are handled by removing a thin layer of water between them and joining the bubble surface with its image to the boundary. Our computations correlate well with experiments for both the first and second cycles of oscillation. The time history of the energy of a bubble system follows a step function, reducing rapidly and significantly because of emission of shock waves at inception of a bubble and at the end of collapse but remaining approximately constant for the rest of the time. The bubble starts being in near contact with the boundary during the first cycle of oscillation when the dimensionless stand-off distance γ = s/R m bubble centre from the boundary and R m is the maximum bubble radius. This leads to (i) the direct impact of a high-speed liquid jet on the boundary once it penetrates through the bubble, (ii) the direct contact of the bubble at high temperature and high pressure with the boundary, and (iii) the direct impingement of shock waves on the boundary once emitted. These phenomena have clear potential to damage the boundary, which are believed to be part of the mechanisms of cavitation damage.

  5. The European Refugee Crisis from the Perspective of International Migration Governance

    Directory of Open Access Journals (Sweden)

    Xie Tingting

    2015-11-01

    Full Text Available The influx of refugees in Europe in 2015 has greatly increased, which not only affects the stability and unity of European society, but also exerts certain pressure on its economic development. In the face of the refugee crisis, it is a dilemma for the European countries to choose either humanitarian or national interests. Starting from the impact and challenge that international migration has had on effective governance within national boundaries, this paper uses the theories of international migration to analyze the three basic choices. Further, the authors provide a new way of thinking about the European refugee crisis from the perspective of international migration governance mechanisms. Of course, China should seize the opportunity to become an advocate of the international migration governance mechanism and rule maker of the global governance.

  6. Space-based Remote Sensing: A Tool for Studying Bird Migration Across Multiple Scales

    Science.gov (United States)

    Smith, James A.

    2005-01-01

    The study of bird migration on a global scale is one of the compelling and challenging problems of modern biology with major implications for human health and conservation biology. Migration and conservation efforts cross national boundaries and are subject to numerous international agreements and treaties. Space based technology offers new opportunities to shed understanding on the distribution and migration of organisms on the planet and their sensitivity to human disturbances and environmental changes. Our working hypothesis is that individual organism biophysical models of energy and water balance, driven by satellite measurements of spatio-temporal gradients in climate and habitat, will help us to explain the variability in avian species richness and distribution. Further, these models provide an ecological forecasting tool for science and application users to visualize the possible consequences of loss of wetlands, flooding, or other natural disasters such as hurricanes on avian biodiversity and bird migration.

  7. Migration and sustainability - compatible or contradictory?

    DEFF Research Database (Denmark)

    Røpke, Inge

    2006-01-01

    When the migration issue is discussed in a sustainability perspective, two questions are vital: 1) What is the relationship between migration and the global population growth? 2) What is the relationship between migration and consumption growth, and how does migration influence the distribution o...... of consumption possibilities both between and within industrialized and developing countries? Based on responses to these questions, it is argued that reasonably managed migration will be compatible with sustainable development....

  8. Seasonal survival probabilities suggest low migration mortality in migrating bats.

    Directory of Open Access Journals (Sweden)

    Simone Giavi

    Full Text Available Migration is adaptive if survival benefits are larger than costs of residency. Many aspects of bat migration ecology such as migratory costs, stopover site use and fidelity are largely unknown. Since many migrating bats are endangered, such information is urgently needed to promote conservation. We selected the migrating Leisler's bat (Nyctalus leisleri as model species and collected capture-recapture data in southern Switzerland year round during 6 years. We estimated seasonal survival and site fidelity with Cormack-Jolly-Seber models that accounted for the presence of transients fitted with Bayesian methods and assessed differences between sexes and seasons. Activity peaked in autumn and spring, whereas very few individuals were caught during summer. We hypothesize that the study site is a migratory stopover site used during fall and spring migration for most individuals, but there is also evidence for wintering. Additionally, we found strong clues for mating during fall. Summer survival that included two major migratory journeys was identical to winter survival in males and slightly higher in females, suggesting that the migratory journeys did not bear significant costs in terms of survival. Transience probability was in both seasons higher in males than in females. Our results suggest that, similarly to birds, Leisler's bat also use stopover sites during migration with high site fidelity. In contrast to most birds, the stopover site was also used for mating and migratory costs in terms of survival seemed to be low. Transients' analyses highlighted strong individual variation in site use which makes particularly challenging the study and modelling of their populations as well as their conservation.

  9. Seasonal survival probabilities suggest low migration mortality in migrating bats.

    Science.gov (United States)

    Giavi, Simone; Moretti, Marco; Bontadina, Fabio; Zambelli, Nicola; Schaub, Michael

    2014-01-01

    Migration is adaptive if survival benefits are larger than costs of residency. Many aspects of bat migration ecology such as migratory costs, stopover site use and fidelity are largely unknown. Since many migrating bats are endangered, such information is urgently needed to promote conservation. We selected the migrating Leisler's bat (Nyctalus leisleri) as model species and collected capture-recapture data in southern Switzerland year round during 6 years. We estimated seasonal survival and site fidelity with Cormack-Jolly-Seber models that accounted for the presence of transients fitted with Bayesian methods and assessed differences between sexes and seasons. Activity peaked in autumn and spring, whereas very few individuals were caught during summer. We hypothesize that the study site is a migratory stopover site used during fall and spring migration for most individuals, but there is also evidence for wintering. Additionally, we found strong clues for mating during fall. Summer survival that included two major migratory journeys was identical to winter survival in males and slightly higher in females, suggesting that the migratory journeys did not bear significant costs in terms of survival. Transience probability was in both seasons higher in males than in females. Our results suggest that, similarly to birds, Leisler's bat also use stopover sites during migration with high site fidelity. In contrast to most birds, the stopover site was also used for mating and migratory costs in terms of survival seemed to be low. Transients' analyses highlighted strong individual variation in site use which makes particularly challenging the study and modelling of their populations as well as their conservation.

  10. Boundaries of dreams, boundaries of dreamers: thin and thick boundaries as a new personality measure.

    Science.gov (United States)

    Hartmann, E

    1989-11-01

    Previous work by the author and his collaborators on frequent nightmare sufferers demonstrated that these people had striking personality characteristics which could be called "thin boundaries" in a number of different senses. In order to measure thin and thick boundaries, a 145-item questionnaire, the Boundary Questionnaire, has been developed which has now been taken by over 1,000 persons. Preliminary results are presented indicating that, as predicted a priori, several new groups of nightmare sufferers and groups of art students scored usually "thin," whereas a group of naval officers had usually "thick" boundaries. Overall, thinness on the Boundary Questionnaire correlated highly positively (r = .40) with frequency of dream recall and also significantly (r = .16) with length of sleep.

  11. Environmental Change and Human Migration

    Directory of Open Access Journals (Sweden)

    Milan Mesić

    2014-12-01

    Full Text Available The 30th anniversary of the journal Migration and Ethnic Themes (MET is an occasion to announce a new key issue in the modern world’s future, which, in the authors’ opinion, is becoming the central theme within multidisciplinary and interdisciplinary field of migration studies. This concerns the displacement of people in the local and national context as well as migration across national borders, at the regional and global level, which are directly or indirectly caused by environmental change. The recent genetic studies on the origins and development of the human race further confirm that the human ecological migrations are the first and the oldest type of migrations at all. In addition, as archaeological and other findings suggest, just this type of migration sometimes played a key role in the emergence, decay and changing of ancient civilizations. It seems that the early researchers of migration studies had a lot in mind considering changes in natural environment as an important determinant of human spatial movements. The interest for this topic in the social sciences had trailed off until the re-emergence in the second half of the 1980s. The authors accept the classification on the causal categories of “environmental migration” as: a “natural” disasters; b “urban-industrial” disasters, and c exploitation and degradation of resources. Further, they deal with the definition of basic concepts, first of all with disputes about the definition of “environmental refugees” as opposed to “environmental migrants”. Finally, the authors systematize two major competing approaches to migration and migrants caused by environmental change. The first one is “the alarmist” and the second one “the sceptic” approach. Luckily, the Sceptics are able (for now to prove that deterrent worse-case scenarios on increasingly powerful and unstoppable “waves” of environmental migrants (refugees have not been achieved. This serves them as

  12. ESCAP migration study gathers momentum.

    Science.gov (United States)

    1980-01-01

    A comparative study is being conducted in the ESCAP (Economic and Social Commission for Asia and the Pacific) region on the relationships of migration and urbanization to development. The 1st stage of the study will entail the preparation of country reports on the census analysis of migration, urbanization and development. The 2nd stage will involve preparation of a series of national migration surveys. The 3rd phase will involve assisting member governments to formulate a comprehensive population redistribution policy as part of their national development planning. 1st-phase country reports have been completed in Sri Lanka, South Korea, the Philippines, and Indonesia. Migration in Sri Lanka has largely been rural-to-rural with little urbanization so far. The picture in South Korea has been the opposite, with rapid urbanization in the 1960s and 1970s; the government is hoping to divert some population to smaller cities away from Seoul. The pattern in the Philippines is 1 of urban primacy with the metropolis of Manila accounting for over 1/3 of the country's total population. Indonesia is characterized by a dense heartland in the Java-Bali regions. However, the rate of urbanization here has been slower. Migrants in all the countries studied are preponderantly young. The sex differential varies from country to country. The influence of migration on subsequent fertility is unknown.

  13. Optimal boundary control and boundary stabilization of hyperbolic systems

    CERN Document Server

    Gugat, Martin

    2015-01-01

    This brief considers recent results on optimal control and stabilization of systems governed by hyperbolic partial differential equations, specifically those in which the control action takes place at the boundary.  The wave equation is used as a typical example of a linear system, through which the author explores initial boundary value problems, concepts of exact controllability, optimal exact control, and boundary stabilization.  Nonlinear systems are also covered, with the Korteweg-de Vries and Burgers Equations serving as standard examples.  To keep the presentation as accessible as possible, the author uses the case of a system with a state that is defined on a finite space interval, so that there are only two boundary points where the system can be controlled.  Graduate and post-graduate students as well as researchers in the field will find this to be an accessible introduction to problems of optimal control and stabilization.

  14. The International-Migration Network

    CERN Document Server

    Fagiolo, Giorgio

    2012-01-01

    This paper studies international migration from a complex-network perspective. We define the international-migration network (IMN) as the weighted-directed graph where nodes are world countries and links account for the stock of migrants originated in a given country and living in another country at a given point in time. We characterize the binary and weighted architecture of the network and its evolution over time in the period 1960-2000. We find that the IMN is organized around a modular structure characterized by a small-world pattern displaying disassortativity and high clustering, with power-law distributed weighted-network statistics. We also show that a parsimonious gravity model of migration can account for most of observed IMN topological structure. Overall, our results suggest that socio-economic, geographical and political factors are more important than local-network properties in shaping the structure of the IMN.

  15. Illuminating dynamic neutrophil trans-epithelial migration with micro-optical coherence tomography

    Science.gov (United States)

    Chu, Kengyeh K.; Kusek, Mark E.; Liu, Linbo; Som, Avira; Yonker, Lael M.; Leung, Huimin; Cui, Dongyao; Ryu, Jinhyeob; Eaton, Alexander D.; Tearney, Guillermo J.; Hurley, Bryan P.

    2017-04-01

    A model of neutrophil migration across epithelia is desirable to interrogate the underlying mechanisms of neutrophilic breach of mucosal barriers. A co-culture system consisting of a polarized mucosal epithelium and human neutrophils can provide a versatile model of trans-epithelial migration in vitro, but observations are typically limited to quantification of migrated neutrophils by myeloperoxidase correlation, a destructive assay that precludes direct longitudinal study. Our laboratory has recently developed a new isotropic 1-μm resolution optical imaging technique termed micro-optical coherence tomography (μOCT) that enables 4D (x,y,z,t) visualization of neutrophils in the co-culture environment. By applying μOCT to the trans-epithelial migration model, we can robustly monitor the spatial distribution as well as the quantity of neutrophils chemotactically crossing the epithelial boundary over time. Here, we demonstrate the imaging and quantitative migration results of our system as applied to neutrophils migrating across intestinal epithelia in response to a chemoattractant. We also demonstrate that perturbation of a key molecular event known to be critical for effective neutrophil trans-epithelial migration (CD18 engagement) substantially impacts this process both qualitatively and quantitatively.

  16. Determination of grain boundary mobility during recrystallization by statistical evaluation of electron backscatter diffraction measurements

    Energy Technology Data Exchange (ETDEWEB)

    Basu, I., E-mail: basu@imm.rwth-aachen.de; Chen, M.; Loeck, M.; Al-Samman, T.; Molodov, D.A.

    2016-07-15

    One of the key aspects influencing microstructural design pathways in metallic systems is grain boundary motion. The present work introduces a method by means of which direct measurement of grain boundary mobility vs. misorientation dependence is made possible. The technique utilizes datasets acquired by means of serial electron backscatter diffraction (EBSD) measurements. The experimental EBSD measurements are collectively analyzed, whereby datasets were used to obtain grain boundary mobility and grain aspect ratio with respect to grain boundary misorientation. The proposed method is further validated using cellular automata (CA) simulations. Single crystal aluminium was cold rolled and scratched in order to nucleate random orientations. Subsequent annealing at 300 °C resulted in grains growing, in the direction normal to the scratch, into a single deformed orientation. Growth selection was observed, wherein the boundaries with misorientations close to Σ7 CSL orientation relationship (38° 〈111〉) migrated considerably faster. The obtained boundary mobility distribution exhibited a non-monotonic behavior with a maximum corresponding to misorientation of 38° ± 2° about 〈111〉 axes ± 4°, which was 10–100 times higher than the mobility values of random high angle boundaries. Correlation with the grain aspect ratio values indicated a strong growth anisotropy displayed by the fast growing grains. The observations have been discussed in terms of the influence of grain boundary character on grain boundary motion during recrystallization. - Highlights: • Statistical microstructure method to measure grain boundary mobility during recrystallization • Method implementation independent of material or crystal structure • Mobility of the Σ7 boundaries in 5N Al was calculated as 4.7 × 10{sup –8} m{sup 4}/J ⋅ s. • Pronounced growth selection in the recrystallizing nuclei in Al • Boundary mobility values during recrystallization 2–3 orders of

  17. Climate Migration and Moral Responsibility.

    Science.gov (United States)

    Nawrotzki, Raphael

    Even though anthropogenic climate change is largely caused by industrialized nations, its burden is distributed unevenly with poor developing countries suffering the most. A common response to livelihood insecurities and destruction is migration. Using Peter Singer's "historical principle" this paper argues that a morally just evaluation requires taking causality between climate change and migration under consideration. The historical principle is employed to emphasize shortcomings in commonly made philosophical arguments to oppose immigration. The article concludes that none of these arguments is able to override the moral responsibility of industrialized countries to compensate for harms that their actions have caused.

  18. Women’s football migration

    DEFF Research Database (Denmark)

    Agergaard, Sine

    What is intriguing about women’s football as a cultural phenomenon is that unlike men’s football the finances and media interest for the game are sparse. Nevertheless we have found that migration of female football players is growing steadily and women’s football is becoming global in nature....... The question is then what drives this globalization process? According to our study of women’s football migration into Scandinavia, one of the centers of women’s football, transnational networks play a crucial role in mobilizing global migratory moves. Using the concept of friends-of-friends networks from Bale...

  19. Genre et migration au Maroc

    OpenAIRE

    KHACHANI, Mohamed

    2011-01-01

    Euro-Mediterranean Consortium for Applied Research on International Migration (CARIM) Une des principales caractéristiques récentes de la migration marocaine est sa tendance à une féminisation soutenue. Le projet migratoire - qui était un projet d’hommes - intéresse de plus en plus les femmes marocaines au point de constituer actuellement près de la moitié de l’effectif migratoire marocain. Cette reconnaissance de l'importance des femmes dans la construction de l'espace migratoire a placé ...

  20. Automation of Flexible Migration Workflows

    Directory of Open Access Journals (Sweden)

    Dirk von Suchodoletz

    2011-03-01

    Full Text Available Many digital preservation scenarios are based on the migration strategy, which itself is heavily tool-dependent. For popular, well-defined and often open file formats – e.g., digital images, such as PNG, GIF, JPEG – a wide range of tools exist. Migration workflows become more difficult with proprietary formats, as used by the several text processing applications becoming available in the last two decades. If a certain file format can not be rendered with actual software, emulation of the original environment remains a valid option. For instance, with the original Lotus AmiPro or Word Perfect, it is not a problem to save an object of this type in ASCII text or Rich Text Format. In specific environments, it is even possible to send the file to a virtual printer, thereby producing a PDF as a migration output. Such manual migration tasks typically involve human interaction, which may be feasible for a small number of objects, but not for larger batches of files.We propose a novel approach using a software-operated VNC abstraction layer in order to replace humans with machine interaction. Emulators or virtualization tools equipped with a VNC interface are very well suited for this approach. But screen, keyboard and mouse interaction is just part of the setup. Furthermore, digital objects need to be transferred into the original environment in order to be extracted after processing. Nevertheless, the complexity of the new generation of migration services is quickly rising; a preservation workflow is now comprised not only of the migration tool itself, but of a complete software and virtual hardware stack with recorded workflows linked to every supported migration scenario. Thus the requirements of OAIS management must include proper software archiving, emulator selection, system image and recording handling. The concept of view-paths could help either to automatically determine the proper pre-configured virtual environment or to set up system

  1. Networks, linkages, and migration systems.

    Science.gov (United States)

    Fawcett, J T

    1989-01-01

    Recent theoretical interest in migration systems calls attention to the functions of diverse linkages between countries in stimulating, directing,and maintaining international flows of people. This article proposes a conceptual framework for the non-people linkages in international migration systems and discusses the implications for population movement of the 4 categories and 3 types of linkages that define the network. The 4 categories include 1) state to state relations, 2) mass culture connections, 3) family and personal networks, and 4) migrant agency activities. The 3 types of linkages are 1) tangible linkages, 2) regulatory linkages, and 3) relational linkages.

  2. Rural migration in southern Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Mosser, D.; Soden, D.L.

    1993-08-01

    This study reviews the history of migration in two rural counties in Southern Nevada. It is part of a larger study about the impact of a proposed high-level nuclear waste repository on in- and out-migration patterns in the state. The historical record suggests a boom and bust economic cycle has predominated in the region for the past century creating conditions that should be taken into account by decision makers when ascertaining the long-term impacts of the proposed repository.

  3. Full wavefield migration : Utilization of multiples in seismic migration

    NARCIS (Netherlands)

    Berkhout, A.J.; Verschuur, D.J.

    2012-01-01

    The next generation migration technology considers multiple scattering as vital information, allowing the industry to generate significantly better images of the subsurface. The proposed full wavefield algorithm (FWM) makes use of two-way wave theory that is formulated in terms of one-way

  4. Countering inbreeding with migration 2. Migration from related ...

    African Journals Online (AJOL)

    In conservation and breeding, large populations are important for evolutionary viability and selection progress. On the other hand, practical and economic rcasons may exist for population subdivision. These populations (islands) may be tied together to form effectively a single population (archipelago) by migration rates of ...

  5. Grain boundary melting in ice

    Science.gov (United States)

    Thomson, E. S.; Hansen-Goos, Hendrik; Wettlaufer, J. S.; Wilen, L. A.

    2013-03-01

    We describe an optical scattering study of grain boundary premelting in water ice. Ubiquitous long ranged attractive polarization forces act to suppress grain boundary melting whereas repulsive forces originating in screened Coulomb interactions and classical colligative effects enhance it. The liquid enhancing effects can be manipulated by adding dopant ions to the system. For all measured grain boundaries this leads to increasing premelted film thickness with increasing electrolyte concentration. Although we understand that the interfacial surface charge densities qs and solute concentrations can potentially dominate the film thickness, we cannot directly measure them within a given grain boundary. Therefore, as a framework for interpreting the data we consider two appropriate qs dependent limits; one is dominated by the colligative effect and other is dominated by electrostatic interactions.

  6. Allegheny County School District Boundaries

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset demarcates the school district boundaries within Allegheny County If viewing this description on the Western Pennsylvania Regional Data Center’s open...

  7. Boundary Layer Control on Airfoils.

    Science.gov (United States)

    Gerhab, George; Eastlake, Charles

    1991-01-01

    A phenomena, boundary layer control (BLC), produced when visualizing the fluidlike flow of air is described. The use of BLC in modifying aerodynamic characteristics of airfoils, race cars, and boats is discussed. (KR)

  8. County Boundaries with Shorelines (National)

    Data.gov (United States)

    Department of Transportation — County boundaries with shorelines cut in (NTAD). The TIGER/Line Files are shapefiles and related database files (.dbf) that are an extract of selected geographic and...

  9. HUC 8-11 Boundaries

    Data.gov (United States)

    Kansas Data Access and Support Center — This data set is a digital hydrologic unit boundary that is at the 4-digit, 6-digit, 8-digit, and 11-digit level. The data set was developed by delineating the...

  10. The laminar boundary layer equations

    CERN Document Server

    Curle, N

    2017-01-01

    Thorough introduction to boundary layer problems offers an ordered, logical presentation accessible to undergraduates. The text's careful expositions of the limitations and accuracy of various methods will also benefit professionals. 1962 edition.

  11. State Highway District Boundaries - 2004

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — This data represents the NM Department of Transportation District boundaries as legislatively defined (i.e. these are not maintenance defined districts).

  12. Boundary Spanners in Global Partnerships

    DEFF Research Database (Denmark)

    Søderberg, Anne-Marie; Romani, Laurence

    2017-01-01

    client relationships and coordinating highly complex projects. We analyze vendor managers’ narratives of their collaboration with a European client in a long-term project, which is presented as a strategic partnership in an outsourcing 3.0 mode. The study offers a rich and conceptualized account of those...... technology (IT) development projects from the rare perspective of Indian vendor managers in one of the world’s largest IT service companies. It draws on a qualitative study of a collaborative partnership and focuses on the key boundary spanners who are responsible for developing trustful and sustainable...... managers’ boundary-spanning activities and a context-sensitive understanding of their boundary work. The study applies Bourdieu’s concept of capital (economic, cultural, social, and symbolic) not only in its analysis of the two powerful partners but also in its discussion of the boundary...

  13. Recognition of boundary feedback systems

    DEFF Research Database (Denmark)

    Pedersen, Michael

    1989-01-01

    A system that has been the object of intense research is outlined. In view of that and recent progress of the theory of pseudodifferential boundary operator calculus, the author describes some features that could prove to be interesting in connection with the problems of boundary feedback...... stabilizability. It is shown that it is possible to use the calculus to consider more general feedback systems in a variational setup....

  14. UO2 Grain Growth: Developing Phase Field Models for Pore Dragging, Solute Dragging and Anisotropic Grain Boundary Energies

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, K. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Tonks, M. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Zhang, Y. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Biner, B. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-09-28

    A detailed phase field model for the effect of pore drag on grain growth kinetics was implemented in MARMOT. The model takes into consideration both the curvature-driven grain boundary motion and pore migration by surface diffusion. As such, the model accounts for the interaction between pore and grain boundary kinetics, which tends to retard the grain growth process. Our 2D and 3D simulations demonstrate that the model capture all possible pore-grain boundary interactions proposed in theoretical models. For high enough surface mobility, the pores move along with the migrating boundary as a quasi-rigid-body, albeit hindering its migration rate compared to the pore-free case. For less mobile pores, the migrating boundary can separate from the pores. For the pore-controlled grain growth kinetics, the model predicts a strong dependence of the growth rate on the number of pores, pore size, and surface diffusivity in agreement with theroretical models. An evolution equation for the grain size that includes these parameters was derived and showed to agree well with numerical solution. It shows a smooth transition from boundary-controlled kinetics to pore-controlled kinetics as the surface diffusivity decreases or the number of pores or their size increases. This equation can be utilized in BISON to give accurate estimate for the grain size evolution. This will be accomplished in the near future. The effect of solute drag and anisotropy of grain boundary on grain growth will be investigated in future studies.

  15. Internal wave-mediated shading causes frequent vertical migrations in fishes

    KAUST Repository

    Kaartvedt, Stein

    2012-04-25

    We provide evidence that internal waves cause frequent vertical migrations (FVM) in fishes. Acoustic data from the Benguela Current revealed that pelagic scattering layers of fish below ~140 m moved in opposite phases to internal waves, ascending ~20 m towards the wave trough and descending from the wave crest. At the trough, the downward displacement of upper waters and the upward migration of fish created an overlapping zone. Near-bottom fish correspondingly left the benthic boundary zone at the wave trough, ascending into an acoustic scattering layer likely consisting of zooplankton and then descending to the benthic boundary zone at the wave crest. We suggest that this vertical fish migration is a response to fluctuations in light intensity of 3 to 4 orders of magnitude caused by shading from a turbid surface layer that had chlorophyll a values of 3 to 4 mg m−3 and varied in thickness from ~15 to 50 m at a temporal scale corresponding to the internal wave period (30 min). This migration frequency thus is much higher than that of the common and widespread light-associated diel vertical migration. Vertical movements affect prey encounters, growth, and survival. We hypothesize that FVM increase the likelihood of prey encounters and the time for safe visual foraging among planktivorous fish, thereby contributing to efficient trophic transfer in major upwelling areas.

  16. Trade and migration: the case of NAFTA.

    Science.gov (United States)

    Martin, P L

    1993-01-01

    "This article provides background information on NAFTA [the North American Free Trade Agreement], reviews data on its economic effects, and summarizes studies and projections of NAFTA's likely effects on Mexico-to-U.S. migration. Migration factors (demand-pull, supply-push, and networks) are examined to determine whether NAFTA's effect on economic development particularly in the border areas will accelerate or retard migration. The conclusion is that NAFTA is likely to produce a temporary migration hump, slightly raising already high migration levels in the 1990s, but reducing the volume of Mexico-to-U.S. migration that would otherwise occur over subsequent decades." excerpt

  17. Creating and refining boundaries--church splitting among Pentecostal Vietnamese migrants in Berlin.

    Science.gov (United States)

    Hüwelmeier, Gertrud

    2013-06-01

    In many parts of the world, Pentecostalism is becoming the fastest growing religious movement. As a result of migration, people from Asia, Africa and Latin America carry religious ideas and practices across borders, in other cases, migrants establish religious networks in the diaspora. However, while embracing newcomers from various backgrounds, Pentecostal believers constantly cross cultural boundaries by incorporating people from different ethnic, national and language backgrounds. While Pentecostal charismatic practitioners blurr boundaries in many situations, simultaneously, they create 'bright boundaries' by rejecting 'traditional' religious practices, imagined as the Other of Pentecostalism and thus to be eliminated. By referring to the concept of boundaries (Barth 1969; Alba (Ethnic and Racial Studies 1:20-69, 2005)) this article argues that charismatic Pentecostal Christianity, alongside its embracing practices with regard to social, ethnic and political boundaries, generates religious boundaries: First, church members reject "traditional" religious practices such as ancestor veneration and spirit possession, practices migrants carry across borders. Second, Pentecostal believers create boundaries towards those who split from the church. By exploring the ambiguities of migrant converts, I will investigate, how some of them subvert and reject control and authority exerted by religious leaders. Therefore, this article, based on ethnographic fieldwork among Vietnamese Pentecostalists, contributes to widely underresearched practices of boundary making and church splitting in the diaspora.

  18. Dimension of Fractal Basin Boundaries.

    Science.gov (United States)

    Park, Bae-Sig

    In many dynamical systems, multiple attractors coexist for certain parameter ranges. The set of initial conditions that asymptotically approach each attractor is its basin of attraction. These basins can be intertwined on arbitrary small scales. Basin boundary can be either smooth or fractal. Dynamical systems that have fractal basin boundary show "final state sensitivity" of the initial conditions. A measure of this sensitivity (uncertainty exponent alpha) is related to the dimension of the basin boundary d = D - alpha , where D is the dimension of the phase space and d is the dimension of the basin boundary. At metamorphosis values of the parameter, there might happen a conversion from smooth to fractal basin boundary (smooth-fractal metamorphosis) or a conversion from fractal to another fractal basin boundary characteristically different from the previous fractal one (fractal-fractal metamorphosis). The dimension changes continuously with the parameter except at the metamorphosis values where the dimension of the basin boundary jumps discontinuously. We chose the Henon map and the forced damped pendulum to investigate this. Scaling of the basin volumes near the metamorphosis values of the parameter is also being studied for the Henon map. Observations are explained analytically by using low dimensional model map. We look for universal scalings of the dimension of fractal basin boundaries near type I and type III intermittency transitions to chaos. Type I intermittency can occur as the system experiences a saddle-node (tangent) bifurcation and type III intermittency can occur as the system experiences an inverted period doubling bifurcation. At these bifurcations, multiple attractors with fractal basin boundaries can be created. It is found the dimension scales, with the parameter, according to the power law d = d_{o } - k| p - p_{c}| ^{beta} with beta = 1/2, where p is the system parameter, p _{c} is the bifurcation value, k is a scaling constant, and d_{o} is

  19. Globalisation and Migration in Africa

    African Journals Online (AJOL)

    forced and people who migrate on this reason without formal documents often risk harassment from immigration and law enforcement authorities of the host country. ..... crime. The ubiquity of cellular phones and proliferation of cyber communica- tion systems means that instant linkages can be made across countries without.

  20. [The questions of international migration].

    Science.gov (United States)

    Samman, M L

    1993-03-01

    International migrations have growing implications for both countries of destination. In the latter, the presence of foreigners and of members of their families today creates problems of integration, causes argument, and brings mounting xenophobia. Paralleling political, economic, and social measures taken by public authorities to respond to these difficulties, education needs to assist in diffusing the resulting social tensions by preparing the minds of learners and helping to develop new attitudes. In particular, when educational programs address questions of international migration, these should be treated in the framework of historical evolution in order that their real significance and their true temporal and spatial dimensions become apparent. It is also important that the growing interdependence between countries should be made plain, that national history should be placed in its international context, and that the true consequences of these developments should be made clear. In this context, learners need to be acquainted with Human Rights, thereby stressing universal moral values and the role of the individual. Lastly, questions relating to international migration are usually presented in the media in a selective and partial manner, and the young people who take in this information often accept the hasty judgments which are made of situations as proven facts. This is why all teaching about international migration needs to be considered or reconsidered in light of the complementary or competing actions of the media. (author's modified)

  1. Migration monitoring with automated technology

    Science.gov (United States)

    Rhonda L. Millikin

    2005-01-01

    Automated technology can supplement ground-based methods of migration monitoring by providing: (1) unbiased and automated sampling; (2) independent validation of current methods; (3) a larger sample area for landscape-level analysis of habitat selection for stopover, and (4) an opportunity to study flight behavior. In particular, radar-acoustic sensor fusion can...

  2. The concept of crisis migration

    Directory of Open Access Journals (Sweden)

    Jane McAdam

    2014-02-01

    Full Text Available "Crisis migration needs to be understood in terms of ‘tipping points’, which are triggered not just by events but also by underlying structural processes. It is important for policymakers for there to be an adequate theory behind the concept of ‘crisis migration’ so that responses are appropriate, timely and thoughtful. "

  3. Job Migration: A Collaborative Effort

    Science.gov (United States)

    Wagoner, Cynthia L.

    2012-01-01

    Music teachers often change jobs several times during their careers. Reasons for job changes vary, but regardless, these changes bring a different set of challenges. Sharing knowledge and learning are part and parcel of collaboration. So what if, as education professionals, music teachers decided to collaborate during job migrations? For all music…

  4. Marriage migration in the Netherlands

    NARCIS (Netherlands)

    Leen Sterckx; Jaco Dagevos; Willem Huijnk; Jantine van Lisdonk

    2014-01-01

    Original title: Huwelijksmigratie in Nederland When a man or woman living in the Netherlands embarks on a relationship with a partner from another country and the couple decide to build a married life together in the Netherlands, we call this marriage migration. The foreign partner who moves to

  5. Measuring attitudes towards unauthorized migration

    NARCIS (Netherlands)

    van der Veer, C.G.; Ommundsen, R.; Krumov, K.; Van Le, H.; Larsen, K.S.

    2008-01-01

    This study reports on the development and cross-national utility of a Likert type scale measuring attitudes toward unauthorized migration into a foreign country in two samples from "migrant-sending" nations. In the first phase a pool of 86 attitude statements were administered to a sample of 505

  6. Bird Migration Across the Himalayas

    NARCIS (Netherlands)

    Prins, Herbert H.T.; Namgail, Tsewang

    2017-01-01

    Birds migrating across the Himalayan region fly over the highest peaks in the world, facing immense physiological and climatic challenges. The authors show the different strategies used by birds to cope with these challenges. Many wetland avian species are seen in the high-altitude lakes of the

  7. Migrations of sandy beach meiofauna

    African Journals Online (AJOL)

    animals leaving the surface area when the wave surges crossed their habitat. His samples, however, only covered the ..... I ,,10 animals. •• 50 animals. FIGURE 4. Vertical distribution of meiofau na per 57 em1 in the top 24 em of sand during the l4-hour vertical migration experimenL. ~. N o o t"' o o -("). > > "f1. ~. -("). > :z: >. <.

  8. Directed cell migration in co-cultures by topographic curvature for heterogeneous tissue engineering.

    Science.gov (United States)

    Okutani, Chihiro; Wagatsuma, Akira; Mabuchi, Kunihiko; Hoshino, Takayuki

    2017-07-01

    Placing cells in the proper position is important for tissue engineering. Previous works addressed this subject in the way of controlling cell migration by micro- or nano-patterning the substrates. However, the problem of changing spatial cell density freely under co-culture conditions is remaining. To solve this problem, in this work, we report that C2C12 spatial cell density changes by the patterning geometric boundary of the topographical structures. In 48 h after seeding cells, at the linear boundary (ridge-groove) structures, C2C12 Groove/Ridge ratio was under 0.70 both under monoculture conditions and under co-culture conditions. In contrast, at the combining the linear boundary and the round boundary (ridge-groove + hole) structures, the ratio was over 0.89 under both culture conditions. This our finding will provide a new device which enables to manipulate spatial cell density under co-culture conditions for heterogeneous tissue engineering.

  9. Migration Theories and Mental Health in Toni Morrison's Jazz

    OpenAIRE

    Leila Tafreshi Motalgh; Wan Roselezam Wan Yahya

    2015-01-01

    This article aims to elaborate the relationship between migration and mental health problems that are evident in migrant women in Toni Morrison's Jazz (1992). To this end, pre-migration, migration and post-migration stress factors are identified in the novel based on Danish Bhugra's theory of migration. It seems that pre-migration stress factors and traumas are associated with the push theory of migration, while post-migration stresses are associated with the pull theory of migration. Despite...

  10. Mediterranean Migrations: Regionalisms Versus Globalisation

    Directory of Open Access Journals (Sweden)

    Martin Baldwin-Eduards

    2004-06-01

    Full Text Available This paper challenges the claim of globalisation as a cause ofimmigration into Southern Europe and, on an empirical basis, identifies regionalisation as being the primary issue, along with networked migratory patterns. However, the changing patterns of immigration do present challenges to both state and society. It is argued here that recent policy responses in Portugal, Italy and Spain have been inconsistent and irrational – reflecting more the ‘securitisation’ of migration than European reality. Earlier policy innovations are identified, by country and date: most of these have now been abandoned. It is suggested that all of Southern Europe has converged onto a statist, restrictionist model of immigration control that was formerly held only by Greece. The principal characteristics of this model are outlined, along with a migration flowchart and indicative data for migrant flows and sub-flows in Italy and Spain. In the final section, I try to show that the needs of the economy cannot be predicted, immigration cannot becontrolled in the manner currently being enforced across Southern Europe, and attempts to do so will damage rather than improve economic productivity and growth. The concept of an accomodating immigration policy is advanced, whereby the state tries to manage the needs of both employers and potential migrants. Six guidelines for policy development are suggested – most of which have alreadybeen successfully carried out in the European Union. These are the following: migration in order to find a job; circular cross-border migration; EU level negotiation of readmission agreements; the need for a variety of migration-for-employment schemes; legal residence should not depend upon continuity of employment; and discreet legalisation will still be needed in Southern Europe.

  11. The Role of Ethnicity in Qualitative Migration Research

    Directory of Open Access Journals (Sweden)

    Sanja Cukut Krilić

    2011-08-01

    Full Text Available In contemporary social science research, researchers largely perceive ethnic groups as a result of a process of boundary making rather than a taken for granted part of our world. However, in methodological terms, researchers often still see ethnicity as imposed on the research process rather than as constructed throughout it. Using personal experience from several research projects, the author first presents the role of ethnic belonging in her research. She then identifies other factors as crucial in negotiating her insider/outsider status in the “field”. The author shows that the researcher’s insider/outsider status is not a fixed category, but is rather negotiated in the research process, depending on the researcher’s multiple and shifting positionalities. Drawing on the critique of methodological nationalism and on the theories of transnationalism in the social sciences and the humanities, she discusses the recent transformations of research designs in qualitative migration research and argues for more de-ethnicised research on migration. On this basis, she calls for migration research beyond locally bounded research sites.

  12. Migrations from the Gora region at the end of the 20th and the beginning of the 21st century

    Directory of Open Access Journals (Sweden)

    Đorđević-Crnobrnja Jadranka

    2014-01-01

    Full Text Available In this paper I will analyze economic and political migration in the Gora region at the end of the 20th and in the first decade of the 21st century. It is my intent to consider and explain their cause and their intensity and scope. In short, I view the socioeconomic and political dimension of these migrations from an ethnological and anthropological point of view. The economic and political migrations from the Gora region at the end of the 20th and the beginning of the 21st century represent the continuation of earlier migrations, albeit more intensive and larger in scope (whole families are migrating. There migrations can be viewed as the effects of political changes in Kosovo, as well as the socioeconomic crisis of the 1990’s. There are no fixed boundaries between these types of migrations, and the only truly stand out examples are the cases in which people migrated for safety reasons. A certain type of migration can be identified based on the terminology used by the interlocutors. I have encountered the terms “banishment” and “displacement” in the narrative discourse of my interlocutors. These terms are used to describe the migrations from Gora during the 1999 war, as well as immediately after. The differences between economic and political migrants can be gouged from other factors such as going to Gora during vacations and holidays as well as investing money into real-estate in the region. Individuals who emigrated from Gora because they feared for their and the loves of their families go to Gora rarely (to attend funerals for example and are not currently thinking of investing unlike those who had left Gora as economic migrants. There are no differences when it comes to where people migrate to for different reasons. Places of migration can, however, be indicative of the form of migration in the sense of whether people migrated to a foreign country or not. One can turn into the other due to the changing of state borders. Thus

  13. Boundary slip from the immersed boundary lattice Boltzmann models.

    Science.gov (United States)

    Le, Guigao; Zhang, Junfeng

    2009-02-01

    We report an interesting and important observation of the velocity fields from immersed boundary lattice Boltzmann methods (IB-LBM). The computed velocity profiles can deviate from theoretical predictions greatly even for very simple flow situations, both in the immersed boundary layer and the bulk region. A rigorous analysis of the IB-LBM simulated velocity for a symmetric shear flow is carried out, and the analytical solutions indicate a strong dependence of velocity on the relaxation parameter (kinetic viscosity). Also our simulations demonstrate that simply increasing the immersed boundary layer thickness is not an efficient approach to reduce such velocity discrepancy. We hope this work will bring the awareness of this essential issue to people using IB-LBM for various flow situations.

  14. Depth migration and de-migration for 3-D migration velocity analysis; Migration profondeur et demigration pour l'analyse de vitesse de migration 3D

    Energy Technology Data Exchange (ETDEWEB)

    Assouline, F.

    2001-07-01

    3-D seismic imaging of complex geologic structures requires the use of pre-stack imaging techniques, the post-stack ones being unsuitable in that case. Indeed, pre-stack depth migration is a technique which allows to image accurately complex structures provided that we have at our disposal a subsurface velocity model accurate enough. The determination of this velocity model is thus a key element for seismic imaging, and to this end, migration velocity analysis methods have met considerable interest. The SMART method is a specific migration velocity analysis method: the singularity of this method is that it does not rely on any restrictive assumptions on the complexity of the velocity model to determine. The SMART method uses a detour through the pre-stack depth migrated domain for extracting multi-offset kinematic information hardly accessible in the time domain. Once achieved the interpretation of the pre-stack depth migrated seismic data, a kinematic de-migration technique of the interpreted events enables to obtain a consistent kinematic database (i.e. reflection travel-times). Then, the inversion of these travel-times, by means of reflection tomography, allows the determination of an accurate velocity model. To be able to really image geologic structures for which the 3-D feature is predominant, we have studied the implementation of migration velocity analysis in 3-D in the context of the SMART method, and more generally, we have developed techniques allowing to overcome the intrinsic difficulties in the 3-D aspects of seismic imaging. Indeed, although formally the SMART method can be directly applied to the case of 3-D complex structures, the feasibility of its implementation requires to choose well the imaging domain. Once this choice done, it is also necessary to conceive a method allowing, via the associated de-migration, to obtain the reflection travel-times. We first consider the offset domain which constitutes, still today, the strategy most usually used

  15. Elastically mediated interactions between grain boundaries and precipitates in two-phase coherent solids

    Science.gov (United States)

    Xu, Ye-Chuan; Geslin, Pierre-Antoine; Karma, Alain

    2016-10-01

    We investigate analytically and numerically the interaction between grain boundaries and second phase precipitates in two-phase coherent solids in the presence of misfit strain. Our numerical study uses amplitude equations that describe the interaction of composition and stress [R. Spatschek and A. Karma, Phys. Rev. B 81, 214201 (2010), 10.1103/PhysRevB.81.214201] and free-energies corresponding to two-dimensional hexagonal and three-dimensional BCC crystal structures that exhibit isotropic and anisotropic elastic properties, respectively. We consider two experimentally motivated geometries where (i) a lamellar precipitate nucleates along a planar grain boundary that is centered inside the precipitate, and (ii) a circular precipitate nucleates inside a grain at a finite distance to an initially planar grain boundary. For the first geometry, we find that the grain boundary becomes morphologically unstable due to the combination of long-range elastic interaction between the grain boundary and compositional domain boundaries, and shear-coupled grain boundary motion. We characterize this instability analytically by extending the linear stability analysis carried out recently [P.-A. Geslin, Y.-C. Xu, and A. Karma, Phys. Rev. Lett. 114, 105501 (2015), 10.1103/PhysRevLett.114.105501] to the more general case of elastic anisotropy. The analysis predicts that elastic anisotropy hinders but does not suppress the instability. Simulations also reveal that, in a well-developed nonlinear regime, this instability can lead to the break-up of low-angle grain boundaries when the misfit strain exceeds a threshold that depends on the grain boundary misorientation. For the second geometry, simulations show that the elastic interaction between an initially planar grain boundary and an adjacent circular precipitate causes the precipitate to migrate to and anchor at the grain boundary.

  16. Migration, Poverty, and the Rural South

    Science.gov (United States)

    Bacon, Lloyd

    1973-01-01

    Employs the 1967 Survey of Economic Opportunity'' data to test hypotheses about differences in migration selectivity depending on the structural distance traversed in the migration process. (Author/JM)

  17. Individual decisions to migrate during civil conflict.

    Science.gov (United States)

    Bohra-Mishra, Pratikshya; Massey, Douglas S

    2011-05-01

    The existing literature on forced migration limits our understanding of how violence affects migration to competing destinations. This article adds to the literature on forced migration by studying how armed violence during a period of civil conflict in south-central Nepal influenced the likelihood of local, internal, and international migration. We find that violence has a nonlinear effect on migration, such that low to moderate levels of violence reduce the odds of movement, but when violence reaches high levels, the odds of movement increase. We also find that the effect of violence on mobility increases as the distance of the move increases. When we consider the influence of violence on microlevel decision-making, we find that the effects of individual and household-level determinants were mostly consistent with hypotheses derived from contemporary theories of voluntary migration and that no predictor of migration influenced the decision to migrate differently in the presence of violence.

  18. The boundary-scan handbook

    CERN Document Server

    Parker, Kenneth P

    2016-01-01

    Aimed at electronics industry professionals, this 4th edition of the Boundary Scan Handbook describes recent changes to the IEEE1149.1 Standard Test Access Port and Boundary-Scan Architecture. This updated edition features new chapters on the possible effects of the changes on the work of the practicing test engineers and the new 1149.8.1 standard. Anyone needing to understand the basics of boundary scan and its practical industrial implementation will need this book. Provides an overview of the recent changes to the 1149.1 standard and the effect of the changes on the work of test engineers;   Explains the new IEEE 1149.8.1 subsidiary standard and applications;   Describes the latest updates on the supplementary IEEE testing standards. In particular, addresses: IEEE Std 1149.1                      Digital Boundary-Scan IEEE Std 1149.4                      Analog Boundary-Scan IEEE Std 1149.6                      Advanced I/O Testing IEEE Std 1149.8.1           �...

  19. Undulatory microswimming near solid boundaries

    Science.gov (United States)

    Schulman, R. D.; Backholm, M.; Ryu, W. S.; Dalnoki-Veress, K.

    2014-10-01

    The hydrodynamic forces involved in the undulatory microswimming of the model organism C. elegans are studied in proximity to solid boundaries. Using a micropipette deflection technique, we attain direct and time-resolved force measurements of the viscous forces acting on the worm near a single planar boundary as well as confined between two planar boundaries. We observe a monotonic increase in the lateral and propulsive forces with increasing proximity to the solid interface. We determine normal and tangential drag coefficients for the worm, and find these to increase with confinement. The measured drag coefficients are compared to existing theoretical models. The ratio of normal to tangential drag coefficients is found to assume a constant value of 1.5 ± 0.1(5) at all distances from a single boundary, but increases significantly as the worm is confined between two boundaries. In response to the increased drag due to confinement, we observe a gait modulation of the nematode, which is primarily characterized by a decrease in the swimming amplitude.

  20. Patient migration among the Italian regions in 2003

    Directory of Open Access Journals (Sweden)

    Gabriele Messina

    2008-03-01

    Full Text Available

    Background: In the Italian National Health Service hospital planning was influenced by two aspects: the patients’ freedom to choose their health care provider and the equal distribution of centers spread throughout Italy. While every Italian Region should be able to meet the health needs of its own inhabitants, consistent migration among regions exists. Retrospective studies of cross boundaries patient flows can be useful for health planning purposes, providing precious information about citizens’ preferences, and helping health managers to think about inequality and adjust the offer of care. The aim of this study is to describe cross boundary flows which occurred across all the Italian Regions in 2003.

    Methods: The hospital discharges for 2003 were obtained from the General Directorate for Health Planning of the Italian Ministry of Health. We analyzed regional cross boundary flows using the Gandy Nomogram. This tool, which assesses patient mobility, can be used to describe regions’ ability to satisfy their internal health demand and their own capability in attracting foreign patients.

    Results: All of the regions, for the most part, were able to satisfy internal health care demands, and are placed in the upper right corner of the Gandy Nomogram. Umbria, Emilia Romagna, P. A. di Bolzano, Tuscany, Lombardy, Friuli V. Giulia, Lazio, Abruzzo were the regions that appeared to perform best. The Lombardy region attracts the most patients.

    Conclusions: This study briefly provides an evaluation of hospital supply of services giving indications about patients’ perception of the quality and organization of services. A deeper analysis of patient migration may be undertaken by looking at specific diseases. This kind of research could be useful for planning and maximising supplies when making decisions about healthcare.

  1. DEFINING MIGRATION POLICIES FROM ORIGIN COUNTRY PERSPECTIVE

    OpenAIRE

    Monica SERBAN

    2014-01-01

    The role state plays in international migration gathers more and more attention in migration studies, across different disciplines. Policies implemented in order to manage migration are a point of high interest in the space of destination countries. Yet, even though our knowledge from destination perspective has constantly increased, origin state is still under the shadow of a biased research agenda. We have little insights on the way migration policies at origin are built, enforced or on the...

  2. Migration in Asia-Europe Relations

    OpenAIRE

    Juego, Bonn

    2010-01-01

    There is a remarkable difference between viewing migration as a 'social integration' issue, on the one hand, and migration as a 'social relation'. The idea of ‘social integration’ has unrealistic assumptions that see migration as a one-way process, that societies and human relations are static, and that migrants are mechanical. Policies that are founded on unrealistic assumptions are most likely to generate tensions, conflicts, and contradictions. For a migration process to succeed in forging...

  3. Evolution with Stochastic Fitness and Stochastic Migration

    Science.gov (United States)

    Rice, Sean H.; Papadopoulos, Anthony

    2009-01-01

    Background Migration between local populations plays an important role in evolution - influencing local adaptation, speciation, extinction, and the maintenance of genetic variation. Like other evolutionary mechanisms, migration is a stochastic process, involving both random and deterministic elements. Many models of evolution have incorporated migration, but these have all been based on simplifying assumptions, such as low migration rate, weak selection, or large population size. We thus have no truly general and exact mathematical description of evolution that incorporates migration. Methodology/Principal Findings We derive an exact equation for directional evolution, essentially a stochastic Price equation with migration, that encompasses all processes, both deterministic and stochastic, contributing to directional change in an open population. Using this result, we show that increasing the variance in migration rates reduces the impact of migration relative to selection. This means that models that treat migration as a single parameter tend to be biassed - overestimating the relative impact of immigration. We further show that selection and migration interact in complex ways, one result being that a strategy for which fitness is negatively correlated with migration rates (high fitness when migration is low) will tend to increase in frequency, even if it has lower mean fitness than do other strategies. Finally, we derive an equation for the effective migration rate, which allows some of the complex stochastic processes that we identify to be incorporated into models with a single migration parameter. Conclusions/Significance As has previously been shown with selection, the role of migration in evolution is determined by the entire distributions of immigration and emigration rates, not just by the mean values. The interactions of stochastic migration with stochastic selection produce evolutionary processes that are invisible to deterministic evolutionary theory

  4. Migration, Youth, and Agricultural Productivity in Ethiopia

    OpenAIRE

    Brauw, Alan de

    2015-01-01

    This paper explores the relationship between migration and agricultural productivity in Ethiopia. Given that there are fairly significant returns to either rural-urban or international migration for labor in Ethiopia, it could be that credit constraints hindering migration start-up are an unexplored constraint against migration. The paper primarily uses the Ethiopia Rural Household Survey panel and a migrant listing exercise completed after the 2009 survey round to explore whether past agricu...

  5. Biological aspects of human migration and mobility.

    Science.gov (United States)

    Mascie-Taylor, C G N; Krzyżanowska, M

    2017-08-01

    This paper reviews how migration, both geographical and social, impacts on variation in some human biological traits. Migration and mobility are considered in relation to anthropometric traits and indices, psychometric traits, health, disease and nutrition, temperature regulation and metabolism, mental health and gene flow. It is well known that migration is important in disease transmission but, as this paper demonstrates, migration can have both positive and negative impacts on both donor and recipient populations for a wide range of human traits.

  6. Migration and rural opportunities in Nigeria.

    Science.gov (United States)

    Adepoju, A

    1984-01-01

    This study is concerned with migration to rural areas in Nigeria. The author examines the rural economic structures, social systems, and demographic features affecting such migration. These features are compared for migrants and nonmigrants in the cash cropping and subsistence cropping areas of southwestern Nigeria. The results suggest that rural migration in southwestern Nigeria is mainly urban-rural migration of a colonizing type. Data for the study are from a survey of 1,782 households in 12 villages.

  7. Capitalist development and internal migration in Nigeria.

    Science.gov (United States)

    Akor, R I; Mou, D

    1986-12-01

    The authors analyze internal migration trends in Nigeria by examining individual household strategies and how they have adapted to structural changes brought about by colonial rule and capitalist development. The first section of this article describes the structural changes that started the process of labor migration. The second section deals with post-independence industrialization and the consequent rural-urban migration. The final section analyzes the consequences of these migration patterns for urban growth and rural productivity.

  8. Juridical structures: refugees and migration.

    Science.gov (United States)

    Veiter, T

    1988-01-01

    The juridical problems in regard to the concepts of refugee, expulsion, and migration are complicated. If one speaks about migration in Europe, one must 1st distinguish between Eastern and Western Europe. In the communist states of Eastern Europe the refugee problem does not exist officially, with the only existing refugee problem in Yugoslavia, which has signed and ratified the Geneva Refugee Convention of 1951. In the other East European states the right to asylum exists, but refugees are granted asylum only if they are persecuted in their country of origin for their communist ideas and activities. In speaking of migration, one must distinguish between migration, forced migration, mass migration, emigration, immigration, the shift of populations, and refugees. In the communist countries of Eastern Europe the right to emigration is not respected, although certain exceptions, as in Poland or Yugoslavia do exist. Generally, in the communist states emigration is not allowed and illegal emigration is punished as "Flight from the Republic." With a few exceptions, political and other persecutions are no longer so typical within Europe. In the last decades, the refugee problem has changed to other continents: Afghanistan/Pakistan, Iran, Sri Lanka, East Timor, Lebanon, Palestine, Sudan, Tchad, Ethiopia, Eritrea, and Angola. The refugee problem in Europe consists mainly in the large afflux of refugees coming from places with other cultural (and religious) attributes. The Islamic immigrants declare themselves regularly as political refugees and hope to be acknowledged as such by the receiving state. The fear of the governments and populations of the receiving countries is that it would not be possible to assimilate such aliens who do not belong to the Christian culture of Europe. Formerly, refugees came mostly from the Christian countries of Eastern Europe with the same race identity and the same religion. For years now, more and more foreign workers are a kind of migrant

  9. Step-Wise Migration : Evidence from Indonesia

    NARCIS (Netherlands)

    Pardede, Elda; McCann, Philip; Venhorst, Viktor

    2016-01-01

    The objective of this paper is to study multiple internal migration trajectories in Indonesia, with special attention to step-wise migration. Step-wise migration involves moves with smaller steps from village to nearby small town, to larger town, and then to big cities rather than a direct move from

  10. Migration Flows: Measurement, Analysis and Modeling

    NARCIS (Netherlands)

    Willekens, F.J.; White, Michael J.

    2016-01-01

    This chapter is an introduction to the study of migration flows. It starts with a review of major definition and measurement issues. Comparative studies of migration are particularly difficult because different countries define migration differently and measurement methods are not harmonized.

  11. KIN NETWORKS AND MIGRATION IN SAGBAMA LOCAL ...

    African Journals Online (AJOL)

    CIU

    borders, legally or illegally (IOM, 2003: 14). Personal relations which connect migrants, former migrants and non-migrants with each other in the places of origin and destination increase the probability of international labour migration in connection with circular migration and chain migration processes. As social networks ...

  12. Zimbabwe's Exodus: Crisis, Migration, Survival | IDRC - International ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2010-07-01

    Zimbabwe's Exodus: Crisis, Migration, Survival. Book cover Zimbabwe's Exodus: Crisis, Migration, Survival. Editor(s):. Jonathan Crush and Daniel Tevera. Publisher(s):. Southern African Migration Programme, IDRC. July 1, 2010. ISBN: 9781920409227. 420 pages. e-ISBN: 9781552504994. Download PDF · Read the e- ...

  13. Migration, Remittances, and Forest Dependence in Ethiopia ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Migration, Remittances, and Forest Dependence in Ethiopia: Implications for Food Security, Gender, and Forest Conservation. This project will provide evidence that offers important insight into the connection between migration, gender, and forest dependence in rural Ethiopia. Need for labour migration, forest resources ...

  14. [Urban employment and internal migration in Peru].

    Science.gov (United States)

    Cotlear, D

    1984-06-01

    The relationship between internal migration and employment problems in Peru is examined. The author argues that regional differences in income distribution are the primary causes of migration, particularly to urban areas. A model of the migration process is developed and tested using data from official sources, surveys, and the published literature.

  15. Asymptotic analysis and boundary layers

    CERN Document Server

    Cousteix, Jean

    2007-01-01

    This book presents a new method of asymptotic analysis of boundary-layer problems, the Successive Complementary Expansion Method (SCEM). The first part is devoted to a general comprehensive presentation of the tools of asymptotic analysis. It gives the keys to understand a boundary-layer problem and explains the methods to construct an approximation. The second part is devoted to SCEM and its applications in fluid mechanics, including external and internal flows. The advantages of SCEM are discussed in comparison with the standard Method of Matched Asymptotic Expansions. In particular, for the first time, the theory of Interactive Boundary Layer is fully justified. With its chapter summaries, detailed derivations of results, discussed examples and fully worked out problems and solutions, the book is self-contained. It is written on a mathematical level accessible to graduate and post-graduate students of engineering and physics with a good knowledge in fluid mechanics. Researchers and practitioners will estee...

  16. Free boundary ballooning mode representation

    Science.gov (United States)

    Zheng, Linjin

    2012-03-01

    Considerable efforts have been made in this field to develop a free boundary ballooning mode representation, which can incorporate the peeling mode stability criterion. Those efforts have not succeeded, simply because the so-called ballooning mode invariance is broken toward plasma edge. This makes 1D description of high n modes at plasma edge become impossible, where n is toroidal mode number. Nevertheless, we prove that the existence of ``half" ballooning mode invariance toward plasma core enables an 1.δ-dimentional representation of the modes, where δ˜O(1/n). This considerably reduces the complicity in investigating high n modes at plasma edge and can be used to study peeling-ballooning modes. This technique can also be useful to extend the 1D calculation of fixed boundary ballooning modes for free boundary ballooning modes. Numerical example will also be presented together with the topological symmetry analysis.

  17. Boundary Value Problems and Approximate Solutions ...

    African Journals Online (AJOL)

    In this paper, we discuss about some basic things of boundary value problems. Secondly, we study boundary conditions involving derivatives and obtain finite difference approximations of partial derivatives of boundary value problems. The last section is devoted to determine an approximate solution for boundary value ...

  18. Boundary Spanners as supports of social capital

    DEFF Research Database (Denmark)

    Vincenti, Gordon

    2016-01-01

    Boundary Spanners are important agenets of supporting the capacity building of local neighbourhoods and of sustainable social captial the article focuses on the skills and competnces adn role of Boundary Spanners.......Boundary Spanners are important agenets of supporting the capacity building of local neighbourhoods and of sustainable social captial the article focuses on the skills and competnces adn role of Boundary Spanners....

  19. Boundary Transgressions: An Issue In Psychotherapeutic Encounter ...

    African Journals Online (AJOL)

    Boundary transgressions tend to be conceptualized on a continuum ranging from boundary crossings to boundary violations. Boundary crossings (e.g. accepting an inexpensive holiday gift from a client, unintentionally encountering a client in public, or attending a client's special event) are described in the literature as ...

  20. Dynamic characteristics of large scale spark bubbles close to different boundaries

    Science.gov (United States)

    Zhang, S.; Zhang, A. M.; Wang, S. P.; Cui, J.

    2017-09-01

    Experiments on the pulsation of the high-voltage electrical-spark bubbles near different boundaries are conducted by means of high-speed photography. Some intriguing details are observed clearly, such as the formation of the jet (especially the contact jet formed when a bubble is quite close to the rigid boundary) and bubble splitting. The variation of the maximum radius of the bubble, bubble period, jet tip velocity, and bubble center migration is investigated with the presence of different boundaries. In the study of the bubble period, two fitting curves are obtained from the data by the author and previous references; one is for the bubble generated beneath the free surface and the other is for the bubble generated above the rigid boundary. In the study of the maximum jet tip velocity, a possible trend line is proposed to describe the variation of the jet tip velocity with γb (the non-dimensional standoff distance from the bubble center to the rigid boundary). Finally, the critical value of γb is studied, at which the migration of the bubble center is inverted.

  1. The cost of migration: spoonbills suffer higher mortality during trans-Saharan spring migrations only

    NARCIS (Netherlands)

    Lok, T.; Overdijk, O.; Piersma, T.

    2015-01-01

    Explanations for the wide variety of seasonal migration patterns of animals all carry the assumption that migration is costly and that this cost increases with migration distance. Although in some studies, the relationships between migration distance and breeding success or annual survival are

  2. The cost of migration : Spoonbills suffer higher mortality during trans-Saharan spring migrations only

    NARCIS (Netherlands)

    Lok, Tamar; Overdijk, Otto; Piersma, Theunis

    2015-01-01

    Explanations for the wide variety of seasonal migration patterns of animals all carry the assumption that migration is costly and that this cost increases with migration distance. Although in some studies, the relationships between migration distance and breeding success or annual survival are

  3. Japanese Migration and the Americas: An Introduction to the Study of Migration.

    Science.gov (United States)

    Mukai, Gary; Brunette, Rachel

    This curriculum module introduces students to the study of migration, including a brief overview of some categories of migration and reasons why people migrate. As a case study, the module uses the Japanese migration experience in the United States, Peru, Brazil, Canada, Mexico, Argentina, Bolivia, and Paraguay. The module introduces students to…

  4. Self-Selection Patterns in Mexico-U.S. Migration: The Role of Migration Networks

    OpenAIRE

    David McKenzie; Hillel Rapoport

    2010-01-01

    The authors examine the role of migration networks in determining self-selection patterns of Mexico-U.S. migration. They first present a simple theoretical framework showing how such networks impact on migration incentives at different education levels and, consequently, how they are likely to affect the expected skill composition of migration. Using survey data from Mexico, the authors th...

  5. Drawing boundaries : boundary arrangements of the IPCC working groups

    NARCIS (Netherlands)

    Christel van Eck

    2016-01-01

    The present research investigates how the IPCC’s Working Groups safeguard their scientific character while communicating with policymakers. Due to the different nature of Working Groups’ assessments, all Working Groups make different boundary arrangements of how science is defined; what is

  6. Boundary works of Grindr research

    DEFF Research Database (Denmark)

    Jørgensen, Kristian Møller

    . It can be understood as arising from boundary works (Jamieson 2005, [Auhor of this paper] forthcoming) and thus be ontologically entangled with the meeting of the prospect of boundary transgression that marks the end of intimacy. Lauren Berlant on the other hand sees intimacy as: …the processes by which....... Communications, 36(1), 91–111. Lundby, K. (ed.) (2014). Mediatization of Communication: Handbooks of Communication Science, vol. 21. Berlin: De Gruyter Mouton. Marwick, A., & Boyd, D. (2014). Networked privacy: How teenagers negotiate context in social media. New Media & Society. Markham, A., & Buchanan, E...

  7. Boundary effect in electrorheological fluids.

    Science.gov (United States)

    Gong, X L; Yang, F; Xuan, S H; Zong, L H; Zhu, W; Jiang, W Q

    2011-12-01

    The effect of the boundary friction coefficient on the rheological properties of the electrorheological (ER) fluids in quasistatic and dynamic states is investigated by computer simulation. The relation between the shear stress and the boundary friction coefficient in quasistatic and dynamic states is discussed qualitatively and quantitatively, and the trend matches the previously reported experimental results well. The flow curves of ER fluids, under different friction coefficients, are calculated, and it is found that the friction coefficient affects the flow curves. In two dimensions, the transitions in structure corresponding to the shear stress variations are presented to understand the mechanism of ER fluids.

  8. Information dynamics of boundary perception

    DEFF Research Database (Denmark)

    Kragness, Haley; Hansen, Niels Christian; Vuust, Peter

    It has long been noted that expert musicians lengthen notes at phrase boundaries in expressive performance. Recently, we have extended research on this phenomenon by showing that undergraduates with no formal musical training and children as young as 3 years lengthen phrase boundaries during self......-paced listening to chord sequences in a lab setting (the musical dwell-time effect). However, the origin of the musical dwell-time effect is still unknown. Recent work has demonstrated that musicians and non-musicians are sensitive to entropy in musical sequences, experiencing high-entropy contexts as more...

  9. Tropical cyclone boundary layer shocks

    OpenAIRE

    Slocum, Christopher J.; Williams, Gabriel J.; Taft, Richard K.; Wayne H. Schubert

    2014-01-01

    This paper presents numerical solutions and idealized analytical solutions of axisymmetric, $f$-plane models of the tropical cyclone boundary layer. In the numerical model, the boundary layer radial and tangential flow is forced by a specified pressure field, which can also be interpreted as a specified gradient balanced tangential wind field $v_{\\rm gr}(r)$ or vorticity field $\\zeta_{\\rm gr}(r)$. When the specified $\\zeta_{\\rm gr}(r)$ field is changed from one that is radially concentrated i...

  10. MIGRATION OF ORACLE HR DATABASE

    CERN Multimedia

    ais.support@cern.ch

    2001-01-01

    Restricted services from 3 to 7 November 2001 Due to the migration of the Oracle HR application to the Web, some services which rely on the application's availability may be disturbed from Friday 2 November at 17:30 until Thursday 8 November at 08:30. Amongst those services: HR Division: records office, recruitment, claims and benefits. FI Division: personnel accounting, advances and claims. ST Division: registration office (access cards). SPL Division: external firm staff records. EP Division: users' office. Experiments' secretariats: PIE, Greybook. Divisional secretariats: externals, internal addresses. All information concerning this migration is available at: http://ais.cern.ch We apologize for any inconvenience and thank you in advance for your understanding.

  11. Physicists' Forced Migrations under Hitler

    Science.gov (United States)

    Beyerchen, Alan

    2011-03-01

    When the Nazis came to power in early 1933 they initiated formal and informal measures that forced Jews and political opponents from public institutions such as universities. Some physicists retired and others went into industry, but most emigrated. International communication and contact made emigration a viable option despite the desperate economic times in the Great Depression. Another wave of emigrations followed the annexation of Austria in 1938. Individual cases as well as general patterns of migration and adaptation to new environments will be examined in this presentation. One important result of the forced migrations was that many of the physicists expelled under Hitler played important roles in strengthening physics elsewhere, often on the Allied side in World War II.

  12. Elastic Reverse Time Migration (RTM) From Surface Topography

    Science.gov (United States)

    Akram, Naveed; Chen, Xiaofei

    2017-04-01

    Seismic Migration is a promising data processing technique to construct subsurface images by projecting the recorded seismic data at surface back to their origins. There are numerous Migration methods. Among them, Reverse Time Migration (RTM) is considered a robust and standard imaging technology in present day exploration industry as well as in academic research field because of its superior performance compared to traditional migration methods. Although RTM is extensive computing and time consuming but it can efficiently handle the complex geology, highly dipping reflectors and strong lateral velocity variation all together. RTM takes data recorded at the surface as a boundary condition and propagates the data backwards in time until the imaging condition is met. It can use the same modeling algorithm that we use for forward modeling. The classical seismic exploration theory assumes flat surface which is almost impossible in practice for land data. So irregular surface topography has to be considered in simulation of seismic wave propagation, which is not always a straightforward undertaking. In this study, Curved grid finite difference method (CG-FDM) is adapted to model elastic seismic wave propagation to investigate the effect of surface topography on RTM results and explore its advantages and limitations with synthetic data experiments by using Foothill model with topography as the true model. We focus on elastic wave propagation rather than acoustic wave because earth actually behaves as an elastic body. Our results strongly emphasize on the fact that irregular surface topography must be considered for modeling of seismic wave propagation to get better subsurface images specially in mountainous scenario and suggest practitioners to properly handled the geometry of data acquired on irregular topographic surface in their imaging algorithms.

  13. Labour Migration and Shadow Prices

    OpenAIRE

    Henry J. Bruton

    1980-01-01

    The effect of migration and home remittances .on the shadow prices of labour and foreign exchange is analysed here, taking into consideration changes in their social marginal productivities.It is argued tha r appreciation of currency, due to large capital inflows and not to increased productivity, results in a misallocation of resources, and, therefore, there is an urgent need for a proper analysis to determine the optimal level of emigrants.

  14. Asia Strategy on International Migration

    OpenAIRE

    Yasushi Iguchi

    2014-01-01

    Japan needs to develop a strategy for planning and realizing economic integration suitable for Asia. Such a strategy should cover not only liberalization of trade in goods and services and investment but also management of international migration. When developing the strategy, it is important to recognize that since the turn of the century, the leadership of globalization is shifting from developed countries to emerging countries.

  15. Heterogeneous Workers, Trade, and Migration

    OpenAIRE

    Heiland, Inga; Kohler, Wilhelm

    2013-01-01

    We argue that the narrative of variety-induced gains from trade in differentiated goods needs revision. If producing differentiated varieties of a good requires differentiated skills and if the work force is heterogeneous in these skills, then firms are likely to have monopsony power. We show that trade then has adverse labor market effects: It increases the monopsony power of firms and worsens the average quality of matches between firms and workers. We also show that international migration...

  16. Influences of environmental cues, migration history and habitat familiarity on partial migration

    DEFF Research Database (Denmark)

    Skov, Christian; Aarestrup, Kim; Baktoft, Henrik

    2010-01-01

    The factors that drive partial migration in organisms are not fully understood. Roach (Rutilus rutilus), a freshwater fish, engage in partial migration where parts of populations switch between summer habitats in lakes and winter habitats in connected streams. To test if the partial migration trait...... is phenotypically plastic or has genetic components, we translocated roach from 2 populations with different opportunities for migration to a lake with migration opportunity, containing a local roach population. This enabled monitoring of partial migration of fish in 3 different situations: 1) previous opportunity...... in the lake with migration opportunity where from group 2 fish were translocated. Directional migration in and out of the lakes was monitored using Passive Integrated Transponder technology. Translocated fish with previous migration opportunity showed migration patterns more similar to local fish than...

  17. Using a Convection Model to Predict Altitudes of White Stork Migration Over Central Israel

    Science.gov (United States)

    Shamoun-Baranes, Judy; Liechti, Olivier; Yom-Tov, Yoram; Leshem, Yossi

    Soaring migrants such as storks, pelicans and large birds of prey rely on thermal convection during migration. The convection model ALPTHERM was designed to predict the onset, strength, duration and depth of thermal convection for varying topographies for glider pilots, based on atmospheric conditions at midnight. We tested ALPTHERM predictions as configured for two topographies of central Israel, the Coastal Plains and the Judean and Samarian Mountains in order to predict altitudes of migrating white storks (Ciconia ciconia). Migrating flocks of white storks were tracked with a motorized glider, to measure maximum altitudes of migration during spring 2000. A significant positive correlation was found between the maximum daily altitudes of migration measured and the predicted upper boundary of thermal convection for the Coastal Plains and Samarian Mountains. Thirty-minute predictions for the Coastal Plains and Samarian Mountains correlated positively with measured maximum migration altitudes per thermal. ALPTHERM forecasts can be used to alter flight altitudes in both civil and especially military aviation and reduce the hazard of serious aircraft collisions with soaring migrants.

  18. Postnatal Migration of Cerebellar Interneurons

    Directory of Open Access Journals (Sweden)

    Ludovic Galas

    2017-06-01

    Full Text Available Due to its continuing development after birth, the cerebellum represents a unique model for studying the postnatal orchestration of interneuron migration. The combination of fluorescent labeling and ex/in vivo imaging revealed a cellular highway network within cerebellar cortical layers (the external granular layer, the molecular layer, the Purkinje cell layer, and the internal granular layer. During the first two postnatal weeks, saltatory movements, transient stop phases, cell-cell interaction/contact, and degradation of the extracellular matrix mark out the route of cerebellar interneurons, notably granule cells and basket/stellate cells, to their final location. In addition, cortical-layer specific regulatory factors such as neuropeptides (pituitary adenylate cyclase-activating polypeptide (PACAP, somatostatin or proteins (tissue-type plasminogen activator (tPA, insulin growth factor-1 (IGF-1 have been shown to inhibit or stimulate the migratory process of interneurons. These factors show further complexity because somatostatin, PACAP, or tPA have opposite or no effect on interneuron migration depending on which layer or cell type they act upon. External factors originating from environmental conditions (light stimuli, pollutants, nutrients or drug of abuse (alcohol also alter normal cell migration, leading to cerebellar disorders.

  19. ILLEGAL MIGRATION-CONCEPTUAL DELIMITATIONS

    Directory of Open Access Journals (Sweden)

    CRISTINA FLORINA POPESCU (PANAIT

    2013-05-01

    Full Text Available Illegal migration is a mobile phenomenon, which ignores national borders, a threat that originates outside the community and extends to Western societies. This phenomenon is becoming larger and irregular migrants are often in a precarious situation and exposed to the criminals involved in various manifestations of organized crime. The future risk factors of the illegal migration are the demographic bomb, because the population is decreasing in European countries and increasing rapidly in poorer countries, droughts, floods, deforestation, that cause conflicts between climate refugees , extreme poverty, totalitarian regimes, epidemics, can trigger millions of people, the elderly and the working population imbalance which leads to the permanent import of immigrants To combat this phenomenon, states must engage and cooperate with each other. Measures taken by states must balance their integration policy for immigrants, legally residents and asylum policy to comply with international conventions. Also, states must adopt anti-immigrant policies, consisting of subordination visa policy to the interests of international security and exchange of information and, not least, to continue the Schengen process, as a value of humanitarian law applied in the field. The aim of the research is to characterize this dangerous phenomenon for the society and the goal is to identify strategies to combat illegal migration.

  20. SUPER-ECCENTRIC MIGRATING JUPITERS

    Energy Technology Data Exchange (ETDEWEB)

    Socrates, Aristotle; Katz, Boaz; Dong Subo; Tremaine, Scott [Institute for Advanced Study, Princeton, NJ 08540 (United States)

    2012-05-10

    An important class of formation theories for hot Jupiters involves the excitation of extreme orbital eccentricity (e = 0.99 or even larger) followed by tidal dissipation at periastron passage that eventually circularizes the planetary orbit at a period less than 10 days. In a steady state, this mechanism requires the existence of a significant population of super-eccentric (e > 0.9) migrating Jupiters with long orbital periods and periastron distances of only a few stellar radii. For these super-eccentric planets, the periastron is fixed due to conservation of orbital angular momentum and the energy dissipated per orbit is constant, implying that the rate of change in semi-major axis a is a-dot {proportional_to}a{sup 1/2} and consequently the number distribution satisfies dN/d log a{proportional_to}a{sup 1/2}. If this formation process produces most hot Jupiters, Kepler should detect several super-eccentric migrating progenitors of hot Jupiters, allowing for a test of high-eccentricity migration scenarios.

  1. Material deposition and migration processes with resonant magnetic perturbation fields at TEXTOR

    Science.gov (United States)

    Laengner, Ruth; Schmitz, O.; Brezinsek, S.; Coenen, J. W.; Eich, T.; Freisinger, M.; Kirschner, A.; Kreter, A.; Möller, S.; Laengner, M.; Philipps, V.; Pospieszczyk, A.; Reimer, H.; Samm, U.; Wienhold, P.; Textor Team

    2013-07-01

    Resonant Magnetic Perturbations (RMPs) are applied with the Dynamic Ergodic Divertor (DED) at TEXTOR to control the plasma edge transport and the plasma surface interaction. This leads to the formation of a three-dimensional (3D) topology of the scrape-off layer (SOL). To quantify the erosion/deposition balance and the material migration in this 3D boundary, spherical test limiters were exposed to plasmas with and without RMP fields applied. Methane doped with 13C as tracer element was injected through a gas inlet in the test limiter. The local gas source was monitored by spatially resolving spectroscopy and the resulting deposition patterns on the limiters were analysed with colourimetry and nuclear reaction analysis. These measurements were compared to simulations of the magnetic field topology simulations. The data provide evidence of a particle migration dominated by an ExB drift within stochastic zones of the 3D plasma boundary.

  2. Why Migrate: For Study or for Work?

    Directory of Open Access Journals (Sweden)

    Elise S. Brezis

    2016-08-01

    Full Text Available Over the past decades, globalization has led to a huge increase in the migration of workers, as well as students. This paper develops a simple two-step model that describes the decisions of an individual vis-à-vis education and migration, and presents a unified model, wherein the two migration decisions are combined into a single, unique model. This paper shows that under the plausible assumption that costs of migration differ over the human life cycle, the usual brain drain strategy is sub-optimal. With an increase in globalization, the brain drain strategy will be replaced by the strategy of migration of students.

  3. Family migration and relative earnings potentials

    DEFF Research Database (Denmark)

    Foged, Mette

    2016-01-01

    A unitarian model of family migration in which families may discount wives’ private gains is used to derive testable predictions regarding the type of couples that select into migrating. The empirical tests show that gender neutral family migration cannot be rejected against the alternative...... of husband centered migration. Couples are more likely to migrate if household earnings potential is disproportionally due to one partner, and families react equally strongly to a male and a female relative advantage in educational earnings potential. These results are driven by households with a strong...

  4. Denuded Zones, Diffusional Creep, and Grain Boundary Sliding

    Energy Technology Data Exchange (ETDEWEB)

    Wadsworth, J; Ruano, O A; Sherby, O D

    2001-06-27

    The appearance of denuded zones following low stress creep in particle-containing crystalline materials is both a microstructural prediction and observation often cited as irrefutable evidence for the Nabarro-Herring mechanism of diffusional creep. The denuded zones are predicted to be at grain boundaries that are orthogonal to the direction of the applied stress. Furthermore, their dimensions should account for the accumulated plastic flow. In the present paper, the evidence for such denuded zones is critically examined. These zones have been observed during creep of magnesium, aluminum, and nickel-base alloys. The investigation casts serious doubts on the apparently compelling evidence for the link between denuded zones and diffusional creep. Specifically, denuded zones are clearly observed under conditions that are explicitly not diffusional creep. Additionally, the denuded zones are often found in directions that are not orthogonal to the applied stress. Other mechanisms that can account for the observations of denuded zones are discussed. It is proposed that grain boundary sliding accommodated by slip is the rate-controlling process in the stress range where denuded zones have been observed. It is likely that the denuded zones are created by dissolution of precipitates at grain boundaries that are simultaneously sliding and migrating during creep.

  5. Influences of environmental cues, migration history, and habitat familiarity on partial migration

    OpenAIRE

    Christian Skov; Kim Aarestrup; Henrik Baktoft; Jakob Brodersen; Christer Brönmark; Lars-Anders Hansson; Nielsen, Einar E.; Tine Nielsen; P Anders Nilsson

    2010-01-01

    The factors that drive partial migration in organisms are not fully understood. Roach (Rutilus rutilus), a freshwater fish, engage in partial migration where parts of populations switch between summer habitats in lakes and winter habitats in connected streams. To test if the partial migration trait is phenotypically plastic or has genetic components, we translocated roach from 2 populations with different opportunities for migration to a lake with migration opportunity, containing a local roa...

  6. Thermal impact of migrating birds' wing color on their flight performance: Possibility of new generation of biologically inspired drones.

    Science.gov (United States)

    Hassanalian, M; Abdelmoula, H; Ben Ayed, S; Abdelkefi, A

    2017-05-01

    The thermal impact of the birds' color on their flight performance are investigated. In most of the large migrating birds, the top of their wings is black. Considering this natural phenomenon in the migrating birds, such as albatross, a thermal analysis of the boundary layer of their wings is performed during the year depending on the solar insulation. It is shown that the temperature difference between the bright and dark colored top wing surface is around 10°C. The dark color on the top of the wing increases the temperature of the boundary layer over the wing which consequently reduces the skin drag force over the wing. This reduction in the drag force can be considered as one of the effective factors for long endurance of these migrating birds. This research should lead to improved designs of the drones by applying the inspired colors which can help drones increase their endurance. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Emerging Transnational migration from Romanian villages

    Directory of Open Access Journals (Sweden)

    Dumitru Sandu

    2014-11-01

    Full Text Available This article presents the first results of a community census (December 2001 on temporary external migration at the level of all Romanian villages. Local key informants filled in the questionnaire on international temporary migration and its sociodemographic profile. As function of the key destinations, the Romanian villages cluster into six major migration fields: Germany, Hungary, Italy, Turkey, Yugoslavia and Spain. At a more detailed level, considering multiple destinations, those fields break into 15 regions of migration.Village-level analysis of the phenomenon indicates a strong selectivity of migration depending on village characteristics. About 4 percent of the total villages of the country account for more than 60 percent of the total return migration from abroad. These are villages of a high probability of transnationalism. Circular or transnational migration is shown to be connected with the basic characteristics of the migration system of the country: the villages where village to city commuting declined sharply after 1990 and where return migration from cities was high recorded a higher propensity for circular migration abroad. A set of about 2700 villages of high migration prevalence is described as «probable transnational communities».

  8. Seismic link at plate boundary

    Indian Academy of Sciences (India)

    ... tested using the coherence of time series to determine the causality and related orientation. The resulting link orientations at the plate boundary conditions indicate that causal triggering seems to be localized along a major fault, as a stress transfer between two major faults, and parallel to the geothermal area extension.

  9. Current Sinkhole Boundaries in Iowa

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — This dataset is a polygon coverage of the sinkhole boundaries as determined by using LiDAR data. The polygons relate to the point coverage using the KPolyID field in...

  10. Humor styles and symbolic boundaries

    NARCIS (Netherlands)

    Kuipers, G.

    2009-01-01

    Humor is strongly related to group boundaries. Jokes and other humorous utterances often draw on implicit references and inside knowledge; they tend to refer to sensitive topics which may offend people; and they ideally incite laughter, one of the strongest markers of social solidarity and emotional

  11. On Boundaries in Linguistic Continua.

    Science.gov (United States)

    Jorgensen, J. Normann; Kristensen, Kjeld

    1995-01-01

    Discusses the notion of regional standards of a language with regard to modern Danish. Regional and national standards of a language as well as local dialect are defined. The article shows that, for a geographical entity, a statistically determined boundary can be established in the range between the extremes of a regional dialect and national…

  12. Boundaries of flat compact surfaces

    DEFF Research Database (Denmark)

    Røgen, Peter

    1999-01-01

    type. The number of $3$-singular points (points of zero curvature or if not then of zero torsion) on the boundary of a flat immersed compact surface is greater than or equal to twice the absolute value of the Euler characteristic of the surface. A set of necessary and, in a weakened sense, sufficient...

  13. 'Regime shopping' across (blurring) boundaries

    NARCIS (Netherlands)

    Houwerzijl, M.S.; Evju, Stein

    2014-01-01

    This book chapter identifies and explores the (blurring) boundaries between the legal regimes for labour mobility across the EU. In the context of - what is sometimes called - 'regime shopping' a close look is taken into the law on freedom of movement within the EU. Several categories of

  14. the Martian atmospheric boundary layer

    DEFF Research Database (Denmark)

    Petrosyan, A.; Galperin, B.; Larsen, Søren Ejling

    2011-01-01

    The planetary boundary layer (PBL) represents the part of the atmosphere that is strongly influenced by the presence of the underlying surface and mediates the key interactions between the atmosphere and the surface. On Mars, this represents the lowest 10 km of the atmosphere during the daytime...

  15. BRIDGES ACROSS AFRICA'S INTERNATIONAL BOUNDARIES ...

    African Journals Online (AJOL)

    The empirical data for this paper is drawn from the ethnic minorities divided along and astride the Cross River borderlands with southern Cameroon. Scholars who have studied the Nigeria Cameroon Boundary tend to lay more emphasis on the state centric perspective that continues to operate largely within the framework ...

  16. Editorial: Environmentalists without Boundaries | Ogunseitan ...

    African Journals Online (AJOL)

    African Journal of Environmental Science and Technology. Journal Home · ABOUT · Advanced Search · Current Issue · Archives · Journal Home > Vol 3, No 3 (2009) >. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register. Editorial: Environmentalists without Boundaries.

  17. An economic analysis of migration in Mexico.

    Science.gov (United States)

    Greenwood, M J; Ladman, J R

    1978-07-01

    This paper analyzes internal migration in Mexico over the 1960-70 period. A model of the determinants of migration is specified and estimated for aggregated interstate migration flows. Results show that distance serves as a significant deterrent to migration, that higher destination earning levels are attractive to migrants, and that regions with high unemployment rates experience lower rates of inmigration. An unanticipated finding is that regions with higher earning levels have greater rates of outmigration. The data are disaggregated to examine separate migration relationships for each state. The results are that distance is a lesser deterrent for those migrants with more accessible alternatives, that higher earning levels reduce the deterring effects of distance, and that regions with higher earning levels have lower associated elasticities of migration. It is concluded that economic factors have played a crucial role in internal migration and thus in the changing occupational and geographic structure of the Mexican labor force.

  18. Partial migration in fishes: causes and consequences

    DEFF Research Database (Denmark)

    Chapman, B.B.; Hulthén, K.; Brodersen, J.

    2012-01-01

    Partial migration, where only some individuals from a population migrate, has been widely reported in a diverse range of animals. In this paper, what is known about the causes and consequences of partial migration in fishes is reviewed. Firstly, the ultimate and proximate drivers of partial...... migration are reflected upon: what ecological factors can shape the evolution of migratory dimorphism? How is partial migration maintained over evolutionary timescales? What proximate mechanisms determine whether an individual is migratory or remains resident? Following this, the consequences of partial...... migration are considered, in an ecological and evolutionary context, and also in an applied sense. Here it is argued that understanding the concept of partial migration is crucial for fisheries and ecosystem managers, and can provide information for conservation strategies. The review concludes...

  19. Migration from New EU Member Countries

    DEFF Research Database (Denmark)

    Pytlikova, Mariola

    2007-01-01

    The main purpose of the paper is to give predictions of the migration potential from the 7 new EU member countries to the EEA/EU-13 countries. Being able to analyze 'real' migration behavior from these particular countries over the period 1990-2000 helps me to avoid problems related to (double) out......-of sample forecasts and to the assumption of invariance of migration behavior across a space that previous studies had to hold. Results of the econometric analyses reveal the importance of controlling for pairs of countries unobserved heterogeneity. Preliminary results regarding the predictions of future...... gross and net migration flows show that the magnitude of the estimated gross and net migration flows is relatively high and lower, respectively, compared to forecasts from previous studies. Such a development in gross and net migration flows indicates that migration from the new EU member countries...

  20. Korean nursing students' intention to migrate abroad.

    Science.gov (United States)

    Lee, Eunjoo; Moon, Mikyung

    2013-12-01

    Migration of Korean nurses has continued with changing patterns and reasons. However, detailed studies of migration among Korean nursing students are limited. This study examined the intention, reasons, and preferences of migration among Korean nursing students. This study also identified priorities and barriers to the decision of nursing students to migrate and work abroad. A descriptive study using a questionnaire was used for this study. A total of 717 nursing students from four BSN programs and three diploma programs at nursing schools in D city and K province of South Korea were included in the analysis. According to the results, 69.8% of respondents intended to migrate abroad, if possible, or absolutely in the future. The score for females who answered "yes, if possible" regarding the intention to migrate was significantly higher, compared to males. More than 64% of respondents eventually want to return to Korea after migration. The two most common reasons for migration were economic reason (salary) (29.7%) and "professional development (28.2%)". Half of all respondents preferred the US as the destination country of migration (50.5%). "Working condition" was the most prevalent reason for the decision regarding the destination and the place to work. More than 71% of respondents selected "the lack of language proficiency" as a barrier to migration. Economic reason was not as strong as in the past to explain migration of Korean nursing students. Most Korean nursing students want to return back with professional development and higher degree. Even permanent migration and return migration of nurses are an inevitable part of globalization, positive and negative aspects of migration between donor as well as destination countries should be investigated. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Grain Boundary Engineering of Electrodeposited Thin Films

    DEFF Research Database (Denmark)

    Alimadadi, Hossein

    of the favorable boundaries that break the network of general grain boundaries. Successful dedicated synthesis of a textured nickel film fulfilling the requirements of grain boundary engineered materials, suggests improved boundary specific properties. However, the textured nickel film shows fairly low......Grain boundary engineering aims for a deliberate manipulation of the grain boundary characteristics to improve the properties of polycrystalline materials. Despite the emergence of some successful industrial applications, the mechanism(s) by which the boundary specific properties can be improved...... to engineer new materials. In this study, one of the most widely used electrolytes for electrodeposition is chosen for the synthesis of nickel films and based on thorough characterization of the boundaries the potentials in grain boundary engineering are outlined. The internal structure of the nickel films...

  2. Measurements of the Curvature of Protrusions/Retrusions on Migrating Recrystallization Boundaries

    DEFF Research Database (Denmark)

    Zhang, Yubin; Godfrey, A.; Juul Jensen, Dorte

    2009-01-01

    in thickness. The results reveal that the values calculated by both these methods are reasonable when compared with the stored energy measured by differential scanning calorimetry. The relationship between protrusions and the average stored energy density in the deformed matrix is also investigated...

  3. "Within Its Jurisdiction": Moving Boundaries, People, and the Law of Migration a

    National Research Council Canada - National Science Library

    Judith Resnik

    2016-01-01

    ... to this country's law of the border. For the title, she have borrowed the phrase "within its jurisdiction" from the Constitution's Fourteenth Amendment to invite reflection not only on the meaning of its promise that no state shall "deny to any person within its jurisdiction the equal protection of the laws" but also on the role that territory plays in thinking through this country's assertions of power over and its responsibilities toward migrants.

  4. Lateral migration of an elastic capsule by optical force in a uniform flow.

    Science.gov (United States)

    Chang, Cheong Bong; Huang, Wei-Xi; Sung, Hyung Jin

    2012-12-01

    The lateral migration of an elastic capsule under an optical force in a uniform flow was studied to show the separation characteristics according to the elastic properties in the cross-type optical separator. The initially spherical capsule was moved through the fluid flow using a laser beam with a Gaussian distribution focused along the direction normal to the flow device surface. To simulate such a system, a penalty immersed boundary method was adopted to enable fluid-membrane coupling, and a dynamic ray tracing method was applied to the optical force calculation. The effects of the elastic properties of the capsule membrane (the surface Young's modulus and the bending modulus) on the lateral migration were studied. By increasing the surface Young's modulus, the capsule deformed less and the migration distance increased; however, buckling occurred in the capsule with a high surface Young's modulus. Buckling could be suppressed by increasing the bending rigidity. The effects of the flow velocity and the laser beam power were also examined. In the simulation, the S number, i.e., the ratio of the optical force to the viscous force, was adjusted by decreasing the flow velocity or increasing the laser beam power. The migration distance increased as the S number increased, and a constant lateral migration distance was obtained for a rigid particle for a given S number. An elastic capsule under conditions intermediate between a fixed flow velocity and a fixed laser beam power, however, did not yield a constant lateral migration distance due to the extent of the deformation in the different situations. To predict the lateral migration distance of an elastic capsule, a nondimensional parameter, S_{e}, was defined to include the effects of the optical force, the elastic force, and the fluid viscous force. A unified tendency of the lateral migration distance with S_{e} was obtained for capsules with intermediate elasticity, by varying either the flow velocity or the laser

  5. Return migration as failure or success? : The determinants of return migration intentions among Moroccan migrants in Europe

    NARCIS (Netherlands)

    de Haas, H.; Fokkema, T.; Fihri, M.F.

    2015-01-01

    Different migration theories generate competing hypotheses with regard to determinants of return migration. While neoclassical migration theory associates migration to the failure to integrate at the destination, the new economics of labour migration sees return migration as the logical stage after

  6. Migration, Acculturation and Political Values

    Directory of Open Access Journals (Sweden)

    Cristian Bocancea

    2011-12-01

    Full Text Available Contemporary migration flows create deep processes of acculturation whose consistency, stability and finality are based on a symbolical and subjective arsenal, represented by the democratic values promoted by the Western world. Besides the demographic and economic changes brought by the current population movements (real or virtual there is also a noticeable cultural change which affects the depths of societies (regardless of whether these movements are emigrations or immigrations and which refer to the birth or the consolidation of a lifestyle based on the aspiration to prosperity, personal freedom and democracy, beyond racial, ethnic, religious, etc. differences.

  7. Migrating Applications to IPv6

    CERN Document Server

    York, Dan

    2011-01-01

    If IPv6 is to be adopted on a large scale, the applications running on desktop systems, laptops, and even mobile devices need to work just as well with this protocol as they do with IPv4. This concise book takes you beyond the network layer and helps you explore the issues you need to address if you are to successfully migrate your apps to IPv6. It's ideal for application developers, system/network architects, product managers, and others involved in moving your network to IPv6. Explore changes you need to make in your application's user interfaceMake sure your application is retrieving corre

  8. Genre et migration au Liban

    OpenAIRE

    JOUNI, Hassan

    2011-01-01

    Euro-Mediterranean Consortium for Applied Research on International Migration (CARIM) La femme possède un statut bien avancé au sein de la société libanaise : la Constitution libanaise proclame l’égalité entre les citoyens. Quelques lois et pratiques restent, toutefois, discriminatoires à l’égard de la femme, notamment la loi sur la nationalité et la loi sur le statut personnel. Une discrimination sociale très grave existe en ce qui concerne les femmes travaillant à domicile; elles subi...

  9. Giant Planet Formation and Migration

    Science.gov (United States)

    Paardekooper, Sijme-Jan; Johansen, Anders

    2018-02-01

    Planets form in circumstellar discs around young stars. Starting with sub-micron sized dust particles, giant planet formation is all about growing 14 orders of magnitude in size. It has become increasingly clear over the past decades that during all stages of giant planet formation, the building blocks are extremely mobile and can change their semimajor axis by substantial amounts. In this chapter, we aim to give a basic overview of the physical processes thought to govern giant planet formation and migration, and to highlight possible links to water delivery.

  10. Asian student migration to Australia.

    Science.gov (United States)

    Shu, J; Hawthorne, L

    1996-01-01

    "This paper presents an overview of Asian student migration to Australia, together with an analysis of political and educational aspects of the overseas student programme. It focuses on some significant consequences of this flow for Australia. The characteristics of key student groups are contrasted to provide some perspective of the diversity of historical and cultural backgrounds, with the source countries of Malaysia, Indonesia and PRC [China] selected as case studies. Since the issue of PRC students in Australia has attracted considerable public attention and policy consideration, particular focus is placed on their experience." (SUMMARY IN FRE AND SPA) excerpt

  11. Clandestine labor migration to Taiwan.

    Science.gov (United States)

    Tsay, C

    1992-01-01

    "Illegal migration to Taiwan is a recent phenomenon but with a rapid rate of increase. Most illegal foreign workers enter on visitor's visas and overstay. This paper's detailed analysis of official data reveals that Malaysia, Philippines, Indonesia and Thailand are the major sources, providing a stock of mostly male workers numbering around 40,000. Sociodemographic and attitudinal changes among Taiwanese workers coupled with labor shortages in low-skilled jobs are pressuring the Taiwanese government to formulate plans for a systematic importation of foreign labor." excerpt

  12. Free boundary ballooning mode representation

    Science.gov (United States)

    Zheng, L. J.

    2012-10-01

    A new type of ballooning mode invariance is found in this paper. Application of this invariance is shown to be able to reduce the two-dimensional problem of free boundary high n modes, such as the peeling-ballooning modes, to a one-dimensional problem. Here, n is toroidal mode number. In contrast to the conventional ballooning representation, which requires the translational invariance of the Fourier components of the perturbations, the new invariance reflects that the independent solutions of the high n mode equations are translationally invariant from one radial interval surrounding a single singular surface to the other intervals. The conventional ballooning mode invariance breaks down at the vicinity of plasma edge, since the Fourier components with rational surfaces in vacuum region are completely different from those with rational surfaces in plasma region. But, the new type of invariance remains valid. This overcomes the limitation of the conventional ballooning mode representation for studying free boundary modes.

  13. Social Entrepreneurship: Definition and Boundaries

    Directory of Open Access Journals (Sweden)

    Samer Abu-Saifan

    2012-02-01

    Full Text Available While individuals may be publicly recognized as social entrepreneurs for their contributions to improve the welfare of communities, the field of social entrepreneurship continues to struggle to gain academic legitimacy. Social entrepreneurship is a term in search of a good definition. The current use of the term seems vague and limitless; it needs boundaries to demarcate its function. The lack of a common definition hinders research and raises questions about which social or profit-making activities fall within the spectrum of social entrepreneurship. To become an important stream in the entrepreneurship literature, social entrepreneurship needs to be properly defined and it requires a theoretical framework that links it to the theory of entrepreneurship. This article builds on the literature to define social entrepreneurship, discusses the boundaries of socially-oriented entrepreneurial activities, and positions the social entrepreneur in the spectrum of entrepreneurship.

  14. Helmholtz bright and boundary solitons

    Energy Technology Data Exchange (ETDEWEB)

    Christian, J M [Joule Physics Laboratory, School of Computing, Science and Engineering, Institute for Materials Research, University of Salford, Salford M5 4WT (United Kingdom); McDonald, G S [Joule Physics Laboratory, School of Computing, Science and Engineering, Institute for Materials Research, University of Salford, Salford M5 4WT (United Kingdom); Chamorro-Posada, P [Departmento de TeorIa de la Senal y Comunicaciones e IngenierIa Telematica, Universidad de Valladolid, ETSI Telecomunicacion, Campus Miguel Delibes s/n, 47011 Valladolid (Spain)

    2007-02-16

    We report, for the first time, exact analytical boundary solitons of a generalized cubic-quintic nonlinear Helmholtz (NLH) equation. These solutions have a linked-plateau topology that is distinct from conventional dark soliton solutions; their amplitude and intensity distributions are spatially delocalized and connect regions of finite and zero wave-field disturbances (suggesting also the classification as 'edge solitons'). Extensive numerical simulations compare the stability properties of recently derived Helmholtz bright solitons, for this type of polynomial nonlinearity, to those of the new boundary solitons. The latter are found to possess a remarkable stability characteristic, exhibiting robustness against perturbations that would otherwise lead to the destabilizing of their bright-soliton counterparts.

  15. Defining Our National Cyberspace Boundaries

    Science.gov (United States)

    2010-02-17

    took place within our national cyberspace boundaries. 14. ABSTRACT Cyber Borders, Cyberspace National Policy, Convention On The Law Of Cyberspace... The Law Of Cyberspace, Cyberspace Law, Cyberspace Theory CLASSIFICATION: Unclassified In February 2009, the Obama Administration...Justinian” to the more recent United Nations “Convention on the Law of the Sea” approved in 1982 by 150 12 countries.22 Risk is an area that is not as

  16. Equilibrium composition of interphase boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Wynblatt, P.

    1990-01-01

    Two modeling approaches have been used to investigate segregation effects at interphase boundaries. The first approach is based on the nearest neighbor bond model, used in conjunction with the regular solution approximation, and is an extension of an earlier framework developed to address segregation phenomena at free surfaces. In order to model a semicoherent interphase boundary, we have employed a second modeling approach, based on Monte Carol simulation, in conjunction with the embedded atom method (EAM). The EAM is a powerful new method for describing interatomic interactions in metallic systems. It includes certain many-body interactions that depend on the local environment of an atom. The Monte Carol approach has been applied to semicoherent interphase boundaries in Cu-Ag-Au alloys dilute in Au. These alloys consist of coexisting Cu-rich and Ag-rich phases, which differ in lattice constant by about 12%, such that good matching across in interface occurs when nine structural units of the Cu-rich phase are opposed to eight structural units of the Ag-rich phase. Thus far, interfaces with two different orientations have been studied: {l brace}001{r brace}-Cu//{l brace}001{r brace}-Ag, {l angle}110{r angle}-Cu//{l angle}110{r angle}-Ag; and {l brace}111{r brace}-Cu//{l brace}111{r brace}-Ag, {l angle}110{r angle}-Cu//{l angle}110{r angle}-Ag. These two interfaces will be referred to as the (001) and (111) interphase boundaries, for short. 18 refs.

  17. Bridging boundaries: CORBA in perspective.

    OpenAIRE

    Cahill, Vinny; Baker, Sean; Nixon, Paddy

    1997-01-01

    peer-reviewed peer-reviewed applications that cross the boundaries of different computing machines, operating systems, and programming languages are increasingly the norm. As a result, the need for what might be called ???bridging technologies??? to develop software that works across heterogeneous environments has become more compelling. The Common Object Request Broker Architecture is one such technology that is both robust and commercially available. CORBA essentially describes...

  18. Bridging boundaries: CORBA in perspective.

    OpenAIRE

    Cahill, Vinny

    1997-01-01

    PUBLISHED pplications that cross the boundaries of different computing machines, operating systems, and programming languages are increasingly the norm. As a result, the need for what might be called ?bridging technologies? to develop software that works across heterogeneous environments has become more compelling. The Common Object Request Broker Architecture is one such technology that is both robust and commercially available. CORBA essentially describes how client app...

  19. Working across Boundaries in Design

    DEFF Research Database (Denmark)

    Clausen, Christian; Yoshinaka, Yutaka

    The paper addresses how insights from the social shaping tradition and political process theory may contribute to an understanding of design as staging of sociotechnical relations and processes cutting across boundaries of diverse organisational, political and knowledge domains. This idea is purs...... organisational practices. One implication of this approach includes an attention towards what (and how) ar-eas may be rendered open to negotiation and transformation in technological design, implementation, and change processes....

  20. Teacher professional boundaries: online & offline

    OpenAIRE

    Morris, Zoe Anna

    2017-01-01

    The 21st century has emerged as an era of accountability and standardisation for the teaching profession (Mikulec & Miller, 2012). The current research is comprised of 4 interrelated empirical studies which measure and explore individual differences in perceptions of teacher-student boundaries in the secondary school context from an ethical perspective. This research is timely given it has been 8 years since the Teacher Code of Conduct was introduced in Victoria (The Institute, 2008). While t...

  1. Borders, boundaries and desirable wishes

    Directory of Open Access Journals (Sweden)

    Luca Pinciaroli

    2015-05-01

    Full Text Available “Borders, boundaries and desirable wishes” is the title of the residential workshop offered to a group of young adults (aged 18-25 of the Centro di Salute Mentale (Mental Health Center of the DSM Basaglia of ASL TO2 in Turin. The idea of the workshop, the definition of the objectives and the topics, which are clearly expressed in the title, come from the work of the team dedicated to group psychotherapies, which has been offering group psychodrama sessions to young adults of this age since 2008. In the delicate move to the adult age, these young adults are lost and stuck in static realities where it is not possible to open up to the dimension of desire nor to the transforming encounter with the Other, since they didn’t have the experience of boundaries and lack. These two elements are necessary to acquire the ability to make projects for oneself. During the workshop the following instruments were used: group, psychodrama and art therapy. The group, as a paternal function, ensured the presence of safe boundaries enabling individuals to experiment; psychodrama and art therapy enabled the bodies to experience encounters and transformations, using doing as a metaphor for the movement against the inhibition of doing and as a way to show oneself to the Other and be able to see the Other. 

  2. Boundary detection via dynamic programming

    Science.gov (United States)

    Udupa, Jayaram K.; Samarasekera, Supun; Barrett, William A.

    1992-09-01

    This paper reports a new method for detecting optimal boundaries in multidimensional scene data via dynamic programming (DP). In its current form the algorithm detects 2-D contours on slices and differs from other reported DP-based algorithms in an essential way in that it allows freedom in 2-D for finding optimal contour paths (as opposed to a single degree of freedom in the published methods). The method is being successfully used in segmenting object boundaries in a variety of medical applications including orbital volume from CT images (for craniofacial surgical planning), segmenting bone in MR images for kinematic analysis of the joints of the foot, segmenting the surface of the brain from the inner surface of the cranial vault, segmenting pituitary gland tumor for following the effect of a drug on the tumor, segmenting the boundaries of the heart in MR images, and segmenting the olfactory bulb for verifying hypotheses related to the size of this bulb in certain disease states.

  3. Morality and boundaries in Paul

    Directory of Open Access Journals (Sweden)

    Bert Jan Lietaert Peerbolte

    2012-01-01

    Full Text Available In the Pauline communities, ethics, ethos and identity were closely intertwined. This essay analyses the way in which Paul emphasised the mental boundaries of the Christ communities to turn them into moral boundaries. In this process, the fencing off of these communities over against their past and their present was a fundamental feature of Paul’s reasoning. The communities thus became fenced off from their past, because the Christ event was seen as causing a major change in history. This change affected both Gentile and Jewish believers. At the same time, Paul stressed the boundaries with the outside world: he characterised the inside world as the loyal remnant of Israel, consisting of Jews and Gentiles alike, and pointed out that this group is the group of the elect ‘saints’. The perspective with which Paul looked at ethics and morality inside this group was strongly coloured by the assumed identity of this group as ‘Israel’. Even though the Mosaic Law was no longer the focal point for the identity of this eschatological Israel, the ethical demands Paul mentioned over against the members of this new Israel were highly influenced by the morality of the law. For Paul, sanctification was a fundamental ideal, and this ideal reflected the spirituality of the Holiness Code of Leviticus. This particular ethical model was framed by the awareness that Paul (and Christ before him was ‘sent’ by God, much in the same way the prophets of Israel themselves had been sent.

  4. Political motivations for intra-European migration.

    Science.gov (United States)

    Bygnes, Susanne; Flipo, Aurore

    2017-08-01

    Motivations for migrating within the European Union have mainly been attributed to economic, career and lifestyle choices. This article suggests that political dissatisfaction is also an important motivator of recent intra-European migration. In our analysis of in-depth interviews with Romanian migrants in Spain and with Spanish migrants in Norway, we found a common emphasis on the political dimensions of their decision to migrate. In the interviews, the economic component of migration was often related to bad governance and negative perceptions of the state. The similarities of Spanish and Romanian migration narratives are especially striking because Spain and Romania represent substantially different migratory, political and economic contexts. However, migration is more obviously intertwined with conventional acts of political protest in the Spanish case. We suggest that differences in democratic contexts are pivotal in people's reactions to and framing of their deep dissatisfaction with domestic politics, as found in many European countries today.

  5. Migration in Asia-Europe Relations

    DEFF Research Database (Denmark)

    Juego, Bonn

    2010-01-01

    There is a remarkable difference between viewing migration as a 'social integration' issue, on the one hand, and migration as a 'social relation'. The idea of ‘social integration’ has unrealistic assumptions that see migration as a one-way process, that societies and human relations are static......, and that migrants are mechanical. Policies that are founded on unrealistic assumptions are most likely to generate tensions, conflicts, and contradictions. For a migration process to succeed in forging social harmony and development, it is therefore of decisive and crucial importance to regard migration...... as a ‘social relation’. This is simply because successful migration has to be a harmonious synergy between the migrants (and also the sending countries where they come from) and the receiving society (and its people). As indicated, migrants enter into the receiving society not merely as a passive commodity...

  6. Globalisation and international migration in Asia.

    Science.gov (United States)

    Hugo, G

    1998-03-01

    "The present paper attempts to summarise the major contemporary trends in international migration in Asia and how this is related to the rapid demographic transition occurring across most of the region. The diversity of types of mobility is one of the striking features of Asian international migration and developments in each major type [are] discussed in the paper. It is then argued that there are elements within the Asian migration system that give it a momentum which to some extent operates outside of the influence of economic and political trends. Finally some emerging issues in Asian international migration are briefly addressed. These include the scale and effects of remittances, the feminisation of migration, undocumented migration, increasing government involvement and brain drain issues." (EXCERPT)

  7. Sage-grouse Conservation Assessment Boundary

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Boundary of the conservation assessment of Greater Sage-grouse and sagebrush habitat conducted by the Western Association of Fish and Wildlife Agencies. The boundary...

  8. Boundary of the State of Iowa

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — This coverage contains polygons representing the Iowa Boundary, it was derived from a coverage of county boundaries, called COUNTIES, of the state of Iowa. COUNTIES...

  9. Cal State Park Boundaries 2011/2012

    Data.gov (United States)

    California Department of Resources — This is a GIS version of California State Park (CSP) operational boundaries and does not represent official property boundary determinations. This GIS version is...

  10. Practical boundary surveying legal and technical principles

    CERN Document Server

    Gay, Paul

    2015-01-01

    This guide to boundary surveying provides landowners, land surveyors, students and others with the necessary foundation to understand boundary surveying techniques and the common legal issues that govern boundary establishment.  Boundary surveying is sometimes mistakenly considered a strictly technical discipline with simple and straightforward technical solutions.  In reality, boundary establishment is often a difficult and complex matter, requiring years of experience and a thorough understanding of boundary law.  This book helps readers to understand the challenges often encountered by boundary surveyors and some of the available solutions. Using only simple and logically explained mathematics, the principles and practice of boundary surveying are demystified for those without prior experience, and the focused coverage of pivotal issues such as easements and setting lot corners will aid even licensed practitioners in untangling thorny cases. Practical advice on using both basic and advanced instruments ...

  11. On filter boundary conditions in topology optimization

    DEFF Research Database (Denmark)

    Clausen, Anders; Andreassen, Erik

    2017-01-01

    Most research papers on topology optimization involve filters for regularization. Typically, boundary effects from the filters are ignored. Despite significant drawbacks the inappropriate homogeneous Neumann boundary conditions are used, probably because they are trivial to implement. In this paper...

  12. The trade, migration, and development nexus

    OpenAIRE

    Philip L. Martin

    2006-01-01

    This paper deals with migrants' role in stimulating development in their countries of origin, outlining the three major channels through which migration can affect development: recruitment, remittances, and returns. It next turns to the North American Free Trade Agreement (NAFTA), assessing the relevance of the Mexico-United States migration hump for migration, trade, and development elsewhere. The paper concludes that migrants can accelerate development in their countries of origin but finds...

  13. Essays of Economic Development and Migration

    OpenAIRE

    Kleemans, Maria Adriaantje

    2015-01-01

    This dissertation is composed of three chapters and studies issues related to economic development and migration. The first chapter looks at migration choice in an environment where people face risk and liquidity constraints. The second chapter, which is co-authored with Jeremy Magruder, studies the labor market impact of immigration in Indonesia. The third chapter is written together with Joan Hamory Hick and Edward Miguel and examines selection into migration in Kenya.The first paper dev...

  14. Navigational Strategies of Migrating Monarch Butterflies

    Science.gov (United States)

    2014-11-10

    AFRL-OSR-VA-TR-2014-0339 NAVIGATIONAL STRATEGIES OF MIGRATING MONARCH BUTTERFLIES Steven Reppert UNIVERSITY OF MASSACHUSETTS Final Report 11/10/2014...Final Progress Statement to (Dr. Patrick Bradshaw) Contract/Grant Title: Navigational Strategies of Migrating Monarch Butterflies Contract...Grant #: FA9550-10-1-0480 Reporting Period: 01-Sept-10 to 31-Aug-14 Overview of accomplishments: Migrating monarch butterflies (Danaus

  15. [Big-city migration in historical perspective].

    Science.gov (United States)

    Croes, M M; Van Huis, L T

    1997-01-01

    "The migration flows to and from the four largest Dutch municipalities (Amsterdam, Rotterdam, The Hague and Utrecht) show a number of similarities. During the past few decades internal migration has been characterized by a move away from the large cities, while the much smaller international migration flow had an opposite direction. This has resulted in a net decrease of the total population in the largest cities." (SUMMARY IN ENG) excerpt

  16. Inter-Religious Marriage and Migration

    OpenAIRE

    Bohm, Maggie Y

    2008-01-01

    This study analyzes the influence of 1) inter-religious marriage and 2) differing levels of church attendance within a married couple on migration behavior. The study draws from previous research on inter-racial marriage for a framework to examine whether there is reason to expect a relationship between migration and inter-religious marriage. We hypothesize that the propensity for migration is higher for inter-religious couples than for couples constituted by individuals of the same religion ...

  17. Elastic least-squares reverse time migration

    KAUST Repository

    Feng, Zongcai

    2016-09-06

    Elastic least-squares reverse time migration (LSRTM) is used to invert synthetic particle-velocity data and crosswell pressure field data. The migration images consist of both the P- and Svelocity perturbation images. Numerical tests on synthetic and field data illustrate the advantages of elastic LSRTM over elastic reverse time migration (RTM). In addition, elastic LSRTM images are better focused and have better reflector continuity than do the acoustic LSRTM images.

  18. Observations of dislocation interactions with recrystallized grain boundaries

    Science.gov (United States)

    Price, C. W.

    1988-08-01

    Possible evidence of the interaction of individual dislocations with recrystallized grain boundaries (GBs) was found in aluminum specimens that had been statically recrystallized after hot deformation. Matrix dislocations from the deformed material appeared to terminate on the recrystallized GB; however, GB dislocations (GBDs) that should have formed from the absorption of the matrix dislocations were not present. In addition, subboundary structure immediately in front of the moving GB appeared to have undergone accelerated dissociation. These observations suggest that rapid GB motion is not associated with lateral movement of GBDs, and short-range dislocation-GB interaction forces, probably image forces, could cause climb-induced vacancy supersaturations to form in front of the GB. This supersaturated vacancy atmosphere could constitute an important contribution to rapid GB migration.

  19. Nuss bar migrations: occurrence and classification

    Energy Technology Data Exchange (ETDEWEB)

    Binkovitz, Lauren E.; Binkovitz, Larry A. [Mayo Clinic, Department of Radiology, Rochester, MN (United States); Zendejas, Benjamin; Moir, Christopher R. [Mayo Clinic, Department of Surgery, Rochester, MN (United States)

    2016-12-15

    Pectus excavatum results from dorsal deviation of the sternum causing narrowing of the anterior-posterior diameter of the chest. It can result in significant cosmetic deformities and cardiopulmonary compromise if severe. The Nuss procedure is a minimally invasive technique that involves placing a thin horizontally oriented metal bar below the dorsal sternal apex for correction of the pectus deformity. To identify the frequency and types of Nuss bar migrations, to present a new categorization of bar migrations, and to present examples of true migrations and pseudomigrations. We retrospectively reviewed the electronic medical records and all pertinent radiologic studies of 311 pediatric patients who underwent a Nuss procedure. We evaluated the frequency and type of bar migrations. Bar migration was demonstrated in 23 of 311 patients (7%) and occurred within a mean period of 26 days after surgery. Bar migrations were subjectively defined as deviation of the bar from the position demonstrated on the immediate postoperative radiographs and categorized as superior, inferior, rotation, lateral or flipped using a new classification system. Sixteen of the 23 migrations required re-operation. Nuss bar migration can be diagnosed with careful evaluation of serial radiographs. Nuss bar migration has a wide variety of appearances and requires exclusion of pseudomigration resulting from changes in patient positioning between radiologic examinations. (orig.)

  20. The role of language in international migration

    DEFF Research Database (Denmark)

    Adsera, Alicia; Pytlikova, Mariola

    in shaping international migration. Specifically, we investigate how both linguistic distance and linguistic diversity, as a proxy for the “potential” ease to learn a new language and to adapt to a new context, affect migration. We find that migration rates increase with linguistic proximity and the result...... a foreign language might be an important factor in the migration decision. We use a novel dataset on immigration flows and stocks of foreigners in 30 OECD destination countries from 223 source countries for the years 1980–2009 and a wide range of linguistic indicators to study the role of language...

  1. Dust Migration in Gravitationally Active Protoplanetary Disks

    Science.gov (United States)

    Backus, I.; Quinn, T.

    2017-05-01

    Solid growth and planet formation may require dense regions of dust. I investigate dust migration concentration, in gravitationally active protoplanetary disks using high resolution, 3D SPH simulations.

  2. Investigation of acetyl migrations in furanosides

    National Research Council Canada - National Science Library

    Chevallier, O P; Migaud, M E

    2006-01-01

    ...) derivatives facilitate acyl migration. Conditions which favour intramolecular and intermolecular mechanisms have been identified with intermolecular transesterifications taking place under mild basic conditions when intramolecular...

  3. Migration processes in SCO member states

    Directory of Open Access Journals (Sweden)

    Valentina Sergeevna Antonyuk

    2012-12-01

    Full Text Available The article concerns modern state and development of migration processes in SCO member states. As a main method of research statistical analysis was applied. The article shows that migration streams between SCO member states are rather intensive, and the problem of labor migration becomes more and more urgent. The countries of consuming and supplying of labour force are clearly differentiated in the region. For some countries, labor export is the key sector of economy. At the same time, interstate relations between SCO member states sometimes are rather disputed. The most urgent factors causing the development of migration processes in the region were determined. Among them, thefactor of growing outflows from China isespecially noted. It is noted that migration processes are discussed by SCO member states nowadays in terms of illegal migration and international criminality connected with it. It means that the question of labor migration is a real problem. It is indicated that the creation of a specific joint commission on migration policy affiliated with the Council of Foreign Ministers of SCO member states is the necessary condition of effective interaction in migration questions within the framework of Shanghai Cooperation Organization.

  4. International migration: The state-sovereignty-migration nexus

    Directory of Open Access Journals (Sweden)

    D. Chigudu

    2015-12-01

    Full Text Available Commonly, international human migration is blamed for corroding states sovereignty, especially stemming from policy circles, academic literature and citizens of the host countries. This has attracted the attention of the media highlighting hazards of being a migrant, with some countries viewing migrants as enemies; and, Cuba provides a vivid case. Yet in other countries, migrants are viewed as important contributors to social and economic development, with Mexico, the Dominican Republic and India serving as examples. This article locates migrants in the framework of human rights as guided by international law without prejudice to the demands of state sovereignty, but linking the two in the context of developing international standards. Migration is seen as a feature of human history dating back to primordial time. Nothing appears surprising in the movement of people across borders, defining a migrant through emigration and immigration while giving due respect to the sovereignty of states, both sending and receiving. The article discusses the nexus between migrants and state sovereignty in order to highlight the mutual benefit grounded in international law. It attempts to portray a more positive image of the migrant person in light of the global world, socio-economic development and human rights fundamentals. The main challenge remains that of implementing human rights, which appear to be at the crossroads of individual rights and state sovereignty. The paper reveals how the challenge can be overcome while maintaining the structure of rights and freedoms without infringement on states’ sovereignty. It concludes that migrants remain on the periphery of effective protection from the vagaries of the citizens, partly because the state has a tendency to confine certain rights to its citizenry. States possess discretionary authority to control the ingress of foreign nationals into their territories though sometimes they fail to do that as evidenced

  5. Grain Boundary Structures and Collective Dynamics of Inversion Domains in Binary Two-Dimensional Materials

    Science.gov (United States)

    Taha, Doaa; Mkhonta, S. K.; Elder, K. R.; Huang, Zhi-Feng

    2017-06-01

    Understanding and controlling the properties and dynamics of topological defects is a lasting challenge in the study of two-dimensional materials, and is crucial to achieve high-quality films required for technological applications. Here grain boundary structures, energies, and dynamics of binary two-dimensional materials are investigated through the development of a phase field crystal model that is parametrized to match the ordering, symmetry, energy, and length scales of hexagonal boron nitride. Our studies reveal some new dislocation core structures for various symmetrically and asymmetrically tilted grain boundaries, in addition to those obtained in previous experiments and first-principles calculations. We also identify a defect-mediated growth dynamics for inversion domains governed by the collective atomic migration and defect core transformation at grain boundaries and junctions, a process that is related to inversion symmetry breaking in binary lattice.

  6. Discourive boundaries of the "Alien" within the space of literature and narration communication

    Directory of Open Access Journals (Sweden)

    Detinko Yulia Ivanovna

    2016-03-01

    Full Text Available The article considers the opposition «own/alien» in the framework of cross-cultural communication. The material of the study is a German- language novel «Die undankbare Fremde», created by writer Brezhnev, who survived the experience of migration to a foreign country and adapting to a new culture. The narrator in the novel describes his and other people’s space by means of mental and speech behaviour lines - discursive boundaries. The role of boundaries between the two cultures is the language level, the attitude to time and space. The difference in cultural and linguistic features, described in the novel, is confirmed by the theory of cultural parameters by E.T. Holl. This intersection can be carried out both at the level of the external social behavior, and on a deeper level - inner emotional «I» narrator describes the discursive boundaries using antonymous vocabulary, metaphors, pronoun deixis.

  7. Boundary induced nonlinearities at small Reynolds numbers

    NARCIS (Netherlands)

    Sbragaglia, M.; Sugiyama, K.

    2007-01-01

    We investigate the importance of boundary slip at finite Reynolds numbers for mixed boundary conditions. Nonlinear effects are induced by the non-homogeneity of the boundary condition and change the symmetry properties of the flow with an overall mean flow reduction. To explain the observed drag

  8. Boundary controllability of integrodifferential systems in Banach ...

    Indian Academy of Sciences (India)

    the regularity of optimal boundary controls for parabolic equations with quadratic cost criterion. Recently Han and Park [7] derived a set of sufficient conditions for the boundary controllability of a semilinear system with a nonlocal condition. The purpose of this paper is to study the boundary controllability of nonlinear ...

  9. Boundary crossings and violations in clinical settings.

    Science.gov (United States)

    Aravind, V K; Krishnaram, V D; Thasneem, Z

    2012-01-01

    Principles of beneficence, autonomy, and nonmaleficence, compassion along with fiduciary partnership are the core concepts in the doctor-patient relationship in therapeutic settings. There are varieties of reasons for boundary problems. Physicians ignorance, exploitative character, emotional vulnerability moral weakness and similar factors may pave the way for boundary issues resulting in nonsexual or sexual boundary crossings and violations.

  10. Determination of grain boundary geometry using TEM

    NARCIS (Netherlands)

    Jang, H.; Farkas, D.; Hosson, J.T.M. De

    An experimental method to obtain the grain boundary geometry using the transmission electron microscope is presented. The method allows Σ determination including grain boundary plane orientation. In order to determine the specialness of the grain boundary, three different criteria for maximum

  11. Free-Boundary Resistive Modes in Tokamaks

    NARCIS (Netherlands)

    Huysmans, G. T. A.; Goedbloed, J. P.; Kerner, W.

    1993-01-01

    There exist a number of observations of magnetohydrodynamic (MHD) activity that can be related to resistive MHD modes localized near the plasma boundary. To study the stability of these modes, a free boundary description of the plasma is essential. The resistive plasma-vacuum boundary conditions

  12. Working with boundaries in systems psychodynamic consulting

    Directory of Open Access Journals (Sweden)

    Henk Struwig

    2012-01-01

    Full Text Available Orientation: The researcher described the systems psychodynamics of boundary management in organisations. The data showed how effective boundary management leads to good holding environments that, in turn, lead to containing difficult emotions.Research purpose: The purpose of the research was to produce a set of theoretical assumptions about organisational boundaries and boundary management in organisations and, from these, to develop a set of hypotheses as a thinking framework for practising consulting psychologists when they work with boundaries from a systems psychodynamic stance.Motivation for the study: The researcher used the belief that organisational boundaries reflect the essence of organisations. Consulting to boundary managers could facilitate a deep understanding of organisational dynamics.Research design, approach and method: The researcher followed a case study design. He used systems psychodynamic discourse analysis. It led to six working hypotheses.Main findings: The primary task of boundary management is to hold the polarities of integration and differentiation and not allow the system to become fragmented or overly integrated. Boundary management is a primary task and an ongoing activity of entire organisations.Practical/managerial implications: Organisations should work actively at effective boundary management and at balancing integration and differentiation. Leaders should become aware of how effective boundary management leads to good holding environments that, in turn, lead to containing difficult emotions in organisations.Contribution/value-add: The researcher provided a boundary-consulting framework in order to assist consultants to balance the conceptual with the practical when they consult.

  13. From migration to settlement: the pathways, migration modes and dynamics of neurons in the developing brain

    Science.gov (United States)

    HATANAKA, Yumiko; ZHU, Yan; TORIGOE, Makio; KITA, Yoshiaki; MURAKAMI, Fujio

    2016-01-01

    Neuronal migration is crucial for the construction of the nervous system. To reach their correct destination, migrating neurons choose pathways using physical substrates and chemical cues of either diffusible or non-diffusible nature. Migrating neurons extend a leading and a trailing process. The leading process, which extends in the direction of migration, determines navigation, in particular when a neuron changes its direction of migration. While most neurons simply migrate radially, certain neurons switch their mode of migration between radial and tangential, with the latter allowing migration to destinations far from the neurons’ site of generation. Consequently, neurons with distinct origins are intermingled, which results in intricate neuronal architectures and connectivities and provides an important basis for higher brain function. The trailing process, in contrast, contributes to the late stage of development by turning into the axon, thus contributing to the formation of neuronal circuits. PMID:26755396

  14. Elderly Migration and State Fiscal Policy: Evidence from the 1990 Census Migration Flows

    National Research Council Canada - National Science Library

    Karen Smith Conway; Andrew J. Houtenville

    2001-01-01

    .... This research investigates whether elderly migration is affected by state fiscal policies, paying close attention to how the public sector is represented and using net as well as gross state-to-state migration flows...

  15. Migration of Asteroidal Dust Particles

    Science.gov (United States)

    Ipatov, S. I.; Mather, J. C.; Taylor, P. A.

    2003-08-01

    We numerically investigated the migration of dust particles with initial velocities and positions same as those of the numbered asteroids using the Bulirsh-Stoer method of integration and took into account the gravitational influence of 8 planets, radiation pressure, Poynting-Robertson drag and solar wind drag, for values of the ratio between the radiation pressure force and the gravitational force β equal to 0.01, 0.05, 0.1, 0.25, and 0.4. For silicate particles such values of β correspond to diameters of 40, 9, 4, 1.6, and 1 microns, respectively. For each β >= 0.05 we considered N=500 particles (N=250 for β =0.01). In our runs, planets were considered as material points, but, based on orbital elements obtained with a step of probability of a collision of a particle with a terrestrial planet during the lifetime of the particle. For smaller particles, the ratio of the number of particles that collided with the Sun to the total number of simulated particles and the probability of collisions of particles with the terrestrial planets are smaller. The probability of a collision of a migrating dust particle with the Earth for β =0.01 is greater by a factor of 220 than for β =0.4. The mean time ta during which an asteroidal dust particle had a semi-major axis 'a' in intervals with a fixed width is greater for smaller β (for the same initial number of particles) at a3.5 AU than at 'a' between 1 and 3 AU, and are usually maximum at 'a' about 2.3 AU. For β =0.01 the local maxima of ta corresponding to the 5:6, 6:7, 3:4, and 2:3 resonances with the Earth are greater than the maximum at 2.4 AU. The peaks in distribution of migrating asteroidal dust particles with semi-major axis corresponding to the n/(n+1) resonances with Earth and Venus and the gaps associated with the 1:1 resonances with these planets are more pronounced for larger particles. The spatial density of a simulated dust cloud and its luminosity (as seen from outside) were greater for smaller distance

  16. Stereotactic core needle breast biopsy marker migration: An analysis of factors contributing to immediate marker migration.

    Science.gov (United States)

    Jain, Ashali; Khalid, Maria; Qureshi, Muhammad M; Georgian-Smith, Dianne; Kaplan, Jonah A; Buch, Karen; Grinstaff, Mark W; Hirsch, Ariel E; Hines, Neely L; Anderson, Stephan W; Gallagher, Katherine M; Bates, David D B; Bloch, B Nicolas

    2017-11-01

    To evaluate breast biopsy marker migration in stereotactic core needle biopsy procedures and identify contributing factors. This retrospective study analyzed 268 stereotactic biopsy markers placed in 263 consecutive patients undergoing stereotactic biopsies using 9G vacuum-assisted devices from August 2010-July 2013. Mammograms were reviewed and factors contributing to marker migration were evaluated. Basic descriptive statistics were calculated and comparisons were performed based on radiographically-confirmed marker migration. Of the 268 placed stereotactic biopsy markers, 35 (13.1%) migrated ≥1 cm from their biopsy cavity. Range: 1-6 cm; mean (± SD): 2.35 ± 1.22 cm. Of the 35 migrated biopsy markers, 9 (25.7%) migrated ≥3.5 cm. Patient age, biopsy pathology, number of cores, and left versus right breast were not associated with migration status (P> 0.10). Global fatty breast density (P= 0.025) and biopsy in the inner region of breast (P = 0.031) were associated with marker migration. Superior biopsy approach (P= 0.025), locally heterogeneous breast density, and t-shaped biopsy markers (P= 0.035) were significant for no marker migration. Multiple factors were found to influence marker migration. An overall migration rate of 13% supports endeavors of research groups actively developing new biopsy marker designs for improved resistance to migration. • Breast biopsy marker migration is documented in 13% of 268 procedures. • Marker migration is affected by physical, biological, and pathological factors. • Breast density, marker shape, needle approach etc. affect migration. • Study demonstrates marker migration prevalence; marker design improvements are needed.

  17. Migration delays caused by anthropogenic barriers: modeling dams, temperature, and success on migrating salmon smolts

    Science.gov (United States)

    Marschall, Elizabeth A.; Mather, Martha E.; Parrish, Donna; Allison, Gary W.; McMenemy, James R.

    2011-01-01

    Disruption to migration is a growing problem for conservation and restoration of animal populations. Anthropogenic barriers along migration paths can delay or prolong migrations, which may result in a mismatch with migration-timing adaptations. To understand the interaction of dams (as barriers along a migration path), seasonally changing environmental conditions, timing of Atlantic salmon (Salmo salar) downstream migration, and ultimate migration success, we used 10 years of river temperature and discharge data as a template upon which we simulated downstream movement of salmon. Atlantic salmon is a cool-water species whose downstream migrating smolts must complete migration before river temperatures become too warm. We found that dams had a local effect on survival as well as a survival effect that was spatially and temporally removed from the encounter with the dam. While smolts are delayed by dams, temperatures downstream can reach lethal or near-lethal temperatures; as a result, the match between completion of migration and the window of appropriate migration conditions can be disrupted. The strength of this spatially and temporally removed effect is at least comparable to the local effects of dams in determining smolt migration success in the presence of dams. We also considered smolts from different tributaries, varying in distance from the river mouth, to assess the potential importance of locally adapted migration timing on the effect of barriers. Migration-initiation temperature affected modeled smolt survival differentially across tributaries, with the success of smolts from upstream tributaries being much more variable across years than that of smolts with a shorter distance to travel. As a whole, these results point to the importance of broadening our spatial and temporal view when managing migrating populations. We must consider not only how many individuals never make it across migration barriers, but also the spatially and temporally removed

  18. Migration delays caused by anthropogenic barriers: Modeling dams, temperature, and success of migrating salmon smolts

    Science.gov (United States)

    Marschall, E.A.; Mather, M. E.; Parrish, D.L.; Allison, G.W.; McMenemy, J.R.

    2011-01-01

    Disruption to migration is a growing problem for conservation and restoration of animal populations. Anthropogenic barriers along migration paths can delay or prolong migrations, which may result in a mismatch with migration-timing adaptations. To understand the interaction of dams (as barriers along a migration path), seasonally changing environmental conditions, timing of Atlantic salmon (Salmo salar) downstream migration, and ultimate migration success, we used 10 years of river temperature and discharge data as a template upon which we simulated downstream movement of salmon. Atlantic salmon is a cool-water species whose downstream migrating smolts must complete migration before river temperatures become too warm. We found that dams had a local effect on survival as well as a survival effect that was spatially and temporally removed from the encounter with the dam. While smolts are delayed by dams, temperatures downstream can reach lethal or near-lethal temperatures;as a result, the match between completion of migration and the window of appropriate migration conditions can be disrupted. The strength of this spatially and temporally removed effect is at least comparable to the local effects of dams in determining smolt migration success in the presence of dams. We also considered smolts from different tributaries, varying in distance from the river mouth, to assess the potential importance of locally adapted migration timing on the effect of barriers. Migration-initiation temperature affected modeled smolt survival differentially across tributaries, with the success of smolts from upstream tributaries being much more variable across years than that of smolts with a shorter distance to travel. As a whole, these results point to the importance of broadening our spatial and temporal view when managing migrating populations. We must consider not only how many individuals never make it across migration barriers, but also the spatially and temporally removed

  19. Morphological constraints on changing avian migration phenology.

    Science.gov (United States)

    Møller, A P; Rubolini, D; Saino, N

    2017-06-01

    Many organisms at northern latitudes have responded to climate warming by advancing their spring phenology. Birds are known to show earlier timing of spring migration and reproduction in response to warmer springs. However, species show heterogeneous phenological responses to climate warming, with those that have not advanced or have delayed migration phenology experiencing population declines. Although some traits (such as migration distance) partly explain heterogeneity in phenological responses, the factors affecting interspecies differences in the responsiveness to climate warming have yet to be fully explored. In this comparative study, we investigate whether variation in wing aspect ratio (reflecting relative wing narrowness), an ecomorphological trait that is strongly associated with flight efficiency and migratory behaviour, affects the ability to advance timing of spring migration during 1960-2006 in a set of 80 European migratory bird species. Species with larger aspect ratio (longer and narrower wings) showed smaller advancement of timing of spring migration compared to species with smaller aspect ratio (shorter and wider wings) while controlling for phylogeny, migration distance and other life-history traits. In turn, migration distance positively predicted aspect ratio across species. Hence, species that are better adapted to migration appear to be more constrained in responding phenologically to rapid climate warming by advancing timing of spring migration. Our findings corroborate the idea that aspect ratio is a major evolutionary correlate of migration, and suggest that selection for energetically efficient flights, as reflected by high aspect ratio, may hinder phenotypically plastic/microevolutionary adjustments of migration phenology to ongoing climatic changes. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

  20. Pseudo-voluntary migration: the case of internal migration system in former Yugoslavia

    Directory of Open Access Journals (Sweden)

    Damir Josipovič

    2013-12-01

    Full Text Available Migration theory has been dichotomised from several different analytical perspectives. The aim of this article is to view migration movements in a holistic scheme taking into account the geographical factors shaping migration patterns at both the point of origin and destination, rather than on the conceptualizations involving the built-in dualisms. The former Yugoslavia with its myriad of cases shows that migration has to be viewed without biased international or internal lenses. Furthermore, the author argues that the migration movements were instead part of a more or less organized system which tended to create circumstances, possibilities and/or impossibilities to migrate. In this way, instead of classifying migrations as either forced or voluntary, the concept of pseudo-voluntary migration movements was proposed. In changing the perspective in which migrations are view in this, the article draws extensively on the moorings theory developed by Bruce Moon. The author gives an updated framework for individual or small group migration analysis. The latter is supplemented by a set of variables and factors in order to make a further use possible at the level of international or internal migration. The author argues that the internal Yugoslav migration system between 1945 and 1991 should be viewed within a framework of potentially coerced, semi-coerced or ‘pseudo-voluntary migration’.