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Sample records for freely migrating defects

  1. Effect of cascade remnants on freely migrating defects in Cu-1% Au alloys

    Energy Technology Data Exchange (ETDEWEB)

    Iwase, A.; Rehn, L.E.; Baldo, P.M.; Funk, L. [Argonne National Lab., IL (United States). Materials Science Div.

    1997-03-01

    The effects of cascade remnants on Freely Migrating Defects (FMD) were studied by measuring Radiation-Induced Segregation (RIS) in Cu-1%Au at 400degC during simultaneous irradiation with 1.5-MeV He and (400-800)-keV heavy ions (Ne, Ar or Cu). The large RIS observed during 1.5-MeV He-only irradiation was dramatically suppressed under simultaneous heavy ion irradiation. For Cu simultaneous irradiation, the suppression disappeared immediately after the Cu irradiation ceased, while for simultaneous inert gas (Ne or Ar) irradiation, the suppression persisted after the ion beam was turned off. These results demonstrate that the displacement cascades created by heavy ions introduce additional annihilation sites, which reduce the steady-state FMD concentrations. As the cascade remnants produced by Cu ions are thermally unstable at 400degC, the RIS suppression occurs only during simultaneous irradiation. On the other hand, the inert gas atoms which accumulate in the specimen apparently stabilize the cascade remnants, allowing the suppression to persist. (author)

  2. Defect volume for Schottky defect formation and cation vacancy migration in LiH

    Energy Technology Data Exchange (ETDEWEB)

    Symeonides, Chrysoleon I. [Solid State Section, Physics Department, University of Athens, Panepistimiopolis Zografos, 15784 Athens (Greece)], E-mail: jzardas@phys.uoa.gr

    2009-06-10

    The defect volumes in LiH for the formation of a Schottky defect as well as for the cation vacancy migration are estimated for the first time. Their values are found to be larger and smaller, respectively, than the molecular volume. The calculation is based on the equation of state obtained from single-crystal synchrotron X-ray diffraction measurements on solid {sup 7}LiH up to 36 GPa, by relying on an interconnection between defect Gibbs energy and bulk elastic data.

  3. Traffic jam in the primitive streak: the role of defective mesoderm migration in birth defects.

    Science.gov (United States)

    Herion, Nils J; Salbaum, J Michael; Kappen, Claudia

    2014-08-01

    Gastrulation is the process in which the three germ layers are formed that contribute to the formation of all major tissues in the developing embryo. We here review mouse genetic models in which defective gastrulation leads to mesoderm insufficiencies in the embryo. Depending on severity of the abnormalities, the outcomes range from incompatible with embryonic survival to structural birth defects, such as heart defects, spina bifida, or caudal dysgenesis. The combined evidence from the mutant models supports the notion that these congenital anomalies can originate from perturbations of mesoderm specification, epithelial-mesenchymal transition, and mesodermal cell migration. Knowledge about the molecular pathways involved may help to improve strategies for the prevention of major structural birth defects.

  4. Meningeal defects alter the tangential migration of cortical interneurons in Foxc1hith/hith mice

    Directory of Open Access Journals (Sweden)

    Zarbalis Konstantinos

    2012-01-01

    Full Text Available Abstract Background Tangential migration presents the primary mode of migration of cortical interneurons translocating into the cerebral cortex from subpallial domains. This migration takes place in multiple streams with the most superficial one located in the cortical marginal zone. While a number of forebrain-expressed molecules regulating this process have emerged, it remains unclear to what extent structures outside the brain, like the forebrain meninges, are involved. Results We studied a unique Foxc1 hypomorph mouse model (Foxc1hith/hith with meningeal defects and impaired tangential migration of cortical interneurons. We identified a territorial correlation between meningeal defects and disruption of interneuron migration along the adjacent marginal zone in these animals, suggesting that impaired meningeal integrity might be the primary cause for the observed migration defects. Moreover, we postulate that the meningeal factor regulating tangential migration that is affected in homozygote mutants is the chemokine Cxcl12. In addition, by using chromatin immunoprecipitation analysis, we provide evidence that the Cxcl12 gene is a direct transcriptional target of Foxc1 in the meninges. Further, we observe migration defects of a lesser degree in Cajal-Retzius cells migrating within the cortical marginal zone, indicating a less important role for Cxcl12 in their migration. Finally, the developmental migration defects observed in Foxc1hith/hith mutants do not lead to obvious differences in interneuron distribution in the adult if compared to control animals. Conclusions Our results suggest a critical role for the forebrain meninges to promote during development the tangential migration of cortical interneurons along the cortical marginal zone and Cxcl12 as the factor responsible for this property.

  5. Study of treating tibial large bone defect with migration of lengthened bone segment in goats

    Institute of Scientific and Technical Information of China (English)

    YANG liu; LI Qi-hong; ZHOU Zhong-an; TAN Zu-jian; PENG Yi-liang

    2001-01-01

    To study the effects of migration of lengthened bone segment (MLBS) on the blood circulation and repair remodeling process at the ends of large bone defect of a long bone. Methods: A total of 18 adult goats were used and more than 35% of the original length of their left tibia was resected. Upper metaphysiotomy to lengthen upper part of the tibia was done and the lengthened bone segment was migrated to repair the large bone defect. The results were observed with X-ray films, Chinese-ink permeated transparent sections and histological study. Results: After MLBS, the defect ends of the tibia were supplied with abundant blood circulation which resulted in rapid and solid long bone healing. Conclusion: Repair of large bone defect of long bones with MLBS provides a new method for clinical practice.

  6. Intrinsic defect process and O migration in PrBa(Co/Fe)2O5.5

    KAUST Repository

    Salawu, Omotayo Akande

    2017-01-08

    New mixed ion-electron conductors ar desired to lower the operating temperature of solid oxide fuel cells. The O Frenkel energy and migration of O ions in rBa(Co/Fe)2O5.5 are studied for this purpose by density functional theory. We demonstrate that Fe substitution strongly affects the formation of defects and consequently the O migration.

  7. Is long-distance bird flight equivalent to a high-energy fast? Body composition changes in freely migrating and captive fasting great knots

    NARCIS (Netherlands)

    Battley, PF; Dietz, MW; Piersma, T; Dekinga, A; Tang, SX; Hulsman, K; Battley, Phil F.; Tang, Sixian

    2001-01-01

    We studied changes in body composition in great knots, Calidris tenuirostris, before and after a migratory flight of 5,400 km from northwest Australia to eastern China. We also took premigratory birds into captivity and fasted them down to their equivalent arrival mass after migration to compare org

  8. Intrinsic defect processes and O migration in PrBa(Co/Fe)2O5.5

    KAUST Repository

    Salawu, Omotayo Akande

    2016-02-10

    © 2016 The Royal Society of Chemistry. New mixed ion-electron conductors are desired to lower the operating temperature of solid oxide fuel cells. The O Frenkel energy and migration of O ions in PrBa(Co/Fe)2O5.5 are studied for this purpose by density functional theory. The electronic structure and charge redistribution during defect formation are analyzed. We demonstrate that Co → Fe substitution strongly affects the formation of defects and consequently the O migration. The low O Frenkel energy points to a high concentration of O vacancies. The migration of the O ions shows a distinct anisotropy.

  9. Sirt1-deficient mice have hypogonadotropic hypogonadism due to defective GnRH neuronal migration.

    Science.gov (United States)

    Di Sante, Gabriele; Wang, Liping; Wang, Chenguang; Jiao, Xuanmiao; Casimiro, Mathew C; Chen, Ke; Pestell, Timothy G; Yaman, Ismail; Di Rocco, Agnese; Sun, Xin; Horio, Yoshiyuki; Powell, Michael J; He, Xiaohong; McBurney, Michael W; Pestell, Richard G

    2015-02-01

    Hypogonadatropic hypogonadism (HH) can be acquired through energy restriction or may be inherited as congenital hypogonadotropic hypogonadism and its anosmia-associated form, Kallmann's syndrome. Congenital hypogonadotropic hypogonadism is associated with mutations in a group of genes that impact fibroblast growth factor 8 (FGF8) function. The Sirt1 gene encodes a nicotinamide adenine dinucleotide-dependent histone deacetylase that links intracellular metabolic stress to gene expression. Herein Sirt1(-/-) mice are shown to have HH due to failed GnRH neuronal migration. Sirtuin-1 (Sirt1) catalytic function induces GnRH neuronal migration via binding and deacetylating cortactin. Sirt1 colocalized with cortactin in GnRH neurons in vitro. Sirt1 colocalization with cortactin was regulated in an FGF8/fibroblast growth factor receptor-1 dependent manner. The profound effect of Sirt1 on the hormonal status of Sirt1(-/-) mice, mediated via defective GnRH neuronal migration, links energy metabolism directly to the hypogonadal state. Sirt1-cortactin may serve as the distal transducer of neuronal migration mediated by the FGF8 synexpression group of genes that govern HH.

  10. Sirt1-Deficient Mice Have Hypogonadotropic Hypogonadism due to Defective GnRH Neuronal Migration

    Science.gov (United States)

    Di Sante, Gabriele; Wang, Liping; Wang, Chenguang; Jiao, Xuanmiao; Casimiro, Mathew C.; Chen, Ke; Pestell, Timothy G.; Yaman, Ismail; Di Rocco, Agnese; Sun, Xin; Horio, Yoshiyuki; Powell, Michael J.; He, Xiaohong; McBurney, Michael W.

    2015-01-01

    Hypogonadatropic hypogonadism (HH) can be acquired through energy restriction or may be inherited as congenital hypogonadotropic hypogonadism and its anosmia-associated form, Kallmann's syndrome. Congenital hypogonadotropic hypogonadism is associated with mutations in a group of genes that impact fibroblast growth factor 8 (FGF8) function. The Sirt1 gene encodes a nicotinamide adenine dinucleotide-dependent histone deacetylase that links intracellular metabolic stress to gene expression. Herein Sirt1−/− mice are shown to have HH due to failed GnRH neuronal migration. Sirtuin-1 (Sirt1) catalytic function induces GnRH neuronal migration via binding and deacetylating cortactin. Sirt1 colocalized with cortactin in GnRH neurons in vitro. Sirt1 colocalization with cortactin was regulated in an FGF8/fibroblast growth factor receptor-1 dependent manner. The profound effect of Sirt1 on the hormonal status of Sirt1−/− mice, mediated via defective GnRH neuronal migration, links energy metabolism directly to the hypogonadal state. Sirt1-cortactin may serve as the distal transducer of neuronal migration mediated by the FGF8 synexpression group of genes that govern HH. PMID:25545407

  11. Detection of Subsurface Defects Using X-Ray Lateral Migration Radiography - A New Backscatter Imaging Technique

    Energy Technology Data Exchange (ETDEWEB)

    Edward T. Dugan; Alan M. Jacobs

    2003-02-10

    A new Compton X-ray backscatter imaging technique called lateral migration radiography (LMR) is applied to detecting a class of sub-surface defects in materials and structures of industrial importance. These include flaws and defects for which there is either no known method or an effective method for detection. Examples are delamination in layered composite structures, defects in deposited coatings on metal surfaces such as in aircraft jet engine components and geometrical structural/composition changes (e.g. due to corrosion) on the inside of shell-like components with only outside surface area access.Research efforts include: the construction of simulated flawed test objects on which experimental measurements are performed to establish LMR flaw detection capabilities; performance of Monte Carlo simulations of these measurements to assist in predicting optimum source-detector configurations and to help obtain a detailed understanding of the physics of lateral migration in small voids and how this impacts the resulting LMR image contrasts; the procurement of samples of materials of industrial importance with flaws and defects; the application of LMR to the detection of flaws and defects in these samples; the development of a multi-detector scanning system to provide for faster, more effective flaw detection; and a determination, for the types of samples examined, of the limits and capabilities of flaw detection using LMR.LMR imaging measurements on the machined samples showed that the optimum contrast in flaw-to-background signal intensity occurred at an X-ray energy of 75 kVp for the aluminum samples and at 35 kVp for the Delrin sample. Monte Carlo simulations and experimental measurements on the aluminum samples showed that LMR is capable of detecting defects down to the tens of microns range. Measurements on the aluminum samples also showed that LMR is capable of detecting relatively small composition variations; a 30 % difference in image intensity was

  12. Formation and migration of charged native point defects in MgH2 : First-principles calculations

    Science.gov (United States)

    Park, Min Sik; Janotti, Anderson; van de Walle, Chris G.

    2009-08-01

    Using first-principles calculations we have investigated the possible native point defects in bulk MgH2 . Due to the interest in this material for hydrogen storage, we have paid particular attention to hydrogen-related defects that are likely to be involved in the absorption and release kinetics of hydrogen. We have considered neutral and charged defects and calculated formation energies as a function of Fermi-level position and hydrogen chemical potential. In the absence of impurities, we find that under extreme H-poor conditions the lowest-energy defects are positively and negatively charged hydrogen vacancies ( VH+ and VH- ). Under extreme H-rich conditions, the lowest-energy defects are VH+ , negatively charged hydrogen interstitials (Hi-) , and negatively charged Mg vacancies VMg2- . The defects are characterized by unusually large local structural rearrangements. The hydrogen-related defects are also highly mobile, with a lowest migration barrier of less than 0.10 eV for Hi- and H2i , and a highest barrier of 0.63 eV for VH- . By combining the calculated formation energies with migration barriers, we find that the lowest activation energy for self-diffusion is about 1.48 eV under H-poor conditions. The consequences of these results for the hydrogenation and dehydrogenation kinetics are discussed.

  13. The non-Arrhenius migration of interstitial defects in bcc transition metals; Migration de type non-Arrhenius des defauts interstitiels dans les metaux de transition de structure cubique centree

    Energy Technology Data Exchange (ETDEWEB)

    Dudarev, S.L. [EURATOM/UKAEA Fusion Association, Culham Science Centre, Oxfordshire (United Kingdom); Imperial College, Dept. of Physics, London (United Kingdom)

    2008-04-15

    Thermally activated migration of defects drives microstructural evolution of materials under irradiation. In the case of vacancies, the activation energy for migration is many times the absolute temperature, and the dependence of the diffusion coefficient on temperature is well approximated by the Arrhenius law. On the other hand the activation energy for the migration of self-interstitial defects, and particularly self-interstitial atom clusters, is very low. In this case a trajectory of a defect performing Brownian motion at or above room temperature does not follow the Arrhenius-like pattern of migration involving infrequent hops separated by the relatively long intervals of time during which a defect resides at a certain point in the crystal lattice. This article reviews recent atomistic simulations of migration of individual interstitial defects, as well as clusters of interstitial defects, and rationalizes the results of simulations on the basis of solutions of the multi-string Frenkel-Kontorova model. The treatment developed in the paper shows that the origin of the non-Arrhenius migration of interstitial defects and interstitial defect clusters is associated with the interaction between a defect and the classical field of thermal phonons. (author)

  14. Migration

    NARCIS (Netherlands)

    Gienapp, P.; Candolin, Ulrika; Wong, Bob

    2012-01-01

    This chapter examines how human-induced environmental changes affect migration. It explores how such changes affect conditions along the migration route, as well as the cues that are used in the timing of migration such as the celestial bodies and the planet's magnetic field. It emphasizes the effec

  15. ABI2-deficient mice exhibit defective cell migration, aberrant dendritic spine morphogenesis, and deficits in learning and memory.

    Science.gov (United States)

    Grove, Matthew; Demyanenko, Galina; Echarri, Asier; Zipfel, Patricia A; Quiroz, Marisol E; Rodriguiz, Ramona M; Playford, Martin; Martensen, Shelby A; Robinson, Matthew R; Wetsel, William C; Maness, Patricia F; Pendergast, Ann Marie

    2004-12-01

    The Abl-interactor (Abi) family of adaptor proteins has been linked to signaling pathways involving the Abl tyrosine kinases and the Rac GTPase. Abi proteins localize to sites of actin polymerization in protrusive membrane structures and regulate actin dynamics in vitro. Here we demonstrate that Abi2 modulates cell morphogenesis and migration in vivo. Homozygous deletion of murine abi2 produced abnormal phenotypes in the eye and brain, the tissues with the highest Abi2 expression. In the absence of Abi2, secondary lens fiber orientation and migration were defective in the eye, without detectable defects in proliferation, differentiation, or apoptosis. These phenotypes were consistent with the localization of Abi2 at adherens junctions in the developing lens and at nascent epithelial cell adherens junctions in vitro. Downregulation of Abi expression by RNA interference impaired adherens junction formation and correlated with downregulation of the Wave actin-nucleation promoting factor. Loss of Abi2 also resulted in cell migration defects in the neocortex and hippocampus, abnormal dendritic spine morphology and density, and severe deficits in short- and long-term memory. These findings support a role for Abi2 in the regulation of cytoskeletal dynamics at adherens junctions and dendritic spines, which is critical for intercellular connectivity, cell morphogenesis, and cognitive functions.

  16. The effects of cation-anion clustering on defect migration in MgAl2O4.

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    Zamora, Richard J; Voter, Arthur F; Perez, Danny; Perriot, Romain; Uberuaga, Blas P

    2016-07-20

    Magnesium aluminate spinel (MgAl2O4), like many other ceramic materials, offers a range of technological applications, from nuclear reactor materials to military body armor. For many of these applications, it is critical to understand both the formation and evolution of lattice defects throughout the lifetime of the material. We use the Speculatively Parallel Temperature Accelerated Dynamics (SpecTAD) method to investigate the effects of di-vacancy and di-interstitial formation on the mobility of the component defects. From long-time trajectories of the state-to-state dynamics, we characterize the migration pathways of defect clusters, and calculate their self-diffusion constants across a range of temperatures. We find that the clustering of Al and O vacancies drastically reduces the mobility of both defects, while the clustering of Mg and O vacancies completely immobilizes them. For interstitials, we find that the clustering of Mg and O defects greatly reduces O interstitial mobility, but has only a weak effect on Mg. These findings illuminate important new details regarding defect kinetics relevant to the application of MgAl2O4 in extreme environments.

  17. Stoppa approach for intrapelvic damage control and reconstruction of complex acetabular defects with intra-pelvic socket migration: A case report

    Directory of Open Access Journals (Sweden)

    Antonio Murcia-Asensio

    2016-01-01

    Conclusion: The Stoppa approach in hip revision surgery can be a complement to traditional approaches to control the intrapelvic structures, remove migrated implants of previous surgery and reconstruct the pelvic defect.

  18. Freely flowing conversations

    DEFF Research Database (Denmark)

    Aakjær, Marie Kirstejn; Andrade, David; Dexters, Peter

    2012-01-01

    on - and support “positive deviants” (Pascal, Sternin and Sternin) – courageous individuals and groups (inmates as well as staff) who transform conversations into new actions and behavioral traits that become beckons of an improved future. In the following we explore concrete examples of efforts at improving......Some would say this article is an impossibility - the authors being a project manager from the Department of Prisons an (ex) inmate and a Designer doing an industrial PhD in the prisons. We hope that others may see this article as an embodiment of how taking part in new conversations...... and in regards to rehabilitation efforts. In the context of prisons UDI is inspired by the complexity approach (Stacey 2005). We seek to facilitate freely flowing conversations between inmates, staff and managers – pushing the boundaries of existing norms, roles and beliefs. In the end however we rely...

  19. Prickle1 mutation causes planar cell polarity and directional cell migration defects associated with cardiac outflow tract anomalies and other structural birth defects

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    Brian C. Gibbs

    2016-03-01

    Full Text Available Planar cell polarity (PCP is controlled by a conserved pathway that regulates directional cell behavior. Here, we show that mutant mice harboring a newly described mutation termed Beetlejuice (Bj in Prickle1 (Pk1, a PCP component, exhibit developmental phenotypes involving cell polarity defects, including skeletal, cochlear and congenital cardiac anomalies. Bj mutants die neonatally with cardiac outflow tract (OFT malalignment. This is associated with OFT shortening due to loss of polarized cell orientation and failure of second heart field cell intercalation mediating OFT lengthening. OFT myocardialization was disrupted with cardiomyocytes failing to align with the direction of cell invasion into the outflow cushions. The expression of genes mediating Wnt signaling was altered. Also noted were shortened but widened bile ducts and disruption in canonical Wnt signaling. Using an in vitro wound closure assay, we showed Bj mutant fibroblasts cannot establish polarized cell morphology or engage in directional cell migration, and their actin cytoskeleton failed to align with the direction of wound closure. Unexpectedly, Pk1 mutants exhibited primary and motile cilia defects. Given Bj mutant phenotypes are reminiscent of ciliopathies, these findings suggest Pk1 may also regulate ciliogenesis. Together these findings show Pk1 plays an essential role in regulating cell polarity and directional cell migration during development.

  20. Prickle1 mutation causes planar cell polarity and directional cell migration defects associated with cardiac outflow tract anomalies and other structural birth defects.

    Science.gov (United States)

    Gibbs, Brian C; Damerla, Rama Rao; Vladar, Eszter K; Chatterjee, Bishwanath; Wan, Yong; Liu, Xiaoqin; Cui, Cheng; Gabriel, George C; Zahid, Maliha; Yagi, Hisato; Szabo-Rogers, Heather L; Suyama, Kaye L; Axelrod, Jeffrey D; Lo, Cecilia W

    2016-02-16

    Planar cell polarity (PCP) is controlled by a conserved pathway that regulates directional cell behavior. Here, we show that mutant mice harboring a newly described mutation termed Beetlejuice (Bj) in Prickle1 (Pk1), a PCP component, exhibit developmental phenotypes involving cell polarity defects, including skeletal, cochlear and congenital cardiac anomalies. Bj mutants die neonatally with cardiac outflow tract (OFT) malalignment. This is associated with OFT shortening due to loss of polarized cell orientation and failure of second heart field cell intercalation mediating OFT lengthening. OFT myocardialization was disrupted with cardiomyocytes failing to align with the direction of cell invasion into the outflow cushions. The expression of genes mediating Wnt signaling was altered. Also noted were shortened but widened bile ducts and disruption in canonical Wnt signaling. Using an in vitro wound closure assay, we showed Bj mutant fibroblasts cannot establish polarized cell morphology or engage in directional cell migration, and their actin cytoskeleton failed to align with the direction of wound closure. Unexpectedly, Pk1 mutants exhibited primary and motile cilia defects. Given Bj mutant phenotypes are reminiscent of ciliopathies, these findings suggest Pk1 may also regulate ciliogenesis. Together these findings show Pk1 plays an essential role in regulating cell polarity and directional cell migration during development.

  1. Global developmental gene expression and pathway analysis of normal brain development and mouse models of human neuronal migration defects.

    Science.gov (United States)

    Pramparo, Tiziano; Libiger, Ondrej; Jain, Sonia; Li, Hong; Youn, Yong Ha; Hirotsune, Shinji; Schork, Nicholas J; Wynshaw-Boris, Anthony

    2011-03-01

    Heterozygous LIS1 mutations are the most common cause of human lissencephaly, a human neuronal migration defect, and DCX mutations are the most common cause of X-linked lissencephaly. LIS1 is part of a protein complex including NDEL1 and 14-3-3ε that regulates dynein motor function and microtubule dynamics, while DCX stabilizes microtubules and cooperates with LIS1 during neuronal migration and neurogenesis. Targeted gene mutations of Lis1, Dcx, Ywhae (coding for 14-3-3ε), and Ndel1 lead to neuronal migration defects in mouse and provide models of human lissencephaly, as well as aid the study of related neuro-developmental diseases. Here we investigated the developing brain of these four mutants and wild-type mice using expression microarrays, bioinformatic analyses, and in vivo/in vitro experiments to address whether mutations in different members of the LIS1 neuronal migration complex lead to similar and/or distinct global gene expression alterations. Consistent with the overall successful development of the mutant brains, unsupervised clustering and co-expression analysis suggested that cell cycle and synaptogenesis genes are similarly expressed and co-regulated in WT and mutant brains in a time-dependent fashion. By contrast, focused co-expression analysis in the Lis1 and Ndel1 mutants uncovered substantial differences in the correlation among pathways. Differential expression analysis revealed that cell cycle, cell adhesion, and cytoskeleton organization pathways are commonly altered in all mutants, while synaptogenesis, cell morphology, and inflammation/immune response are specifically altered in one or more mutants. We found several commonly dysregulated genes located within pathogenic deletion/duplication regions, which represent novel candidates of human mental retardation and neurocognitive disabilities. Our analysis suggests that gene expression and pathway analysis in mouse models of a similar disorder or within a common pathway can be used to define

  2. Formation, migration, and clustering of point defects in CuInSe2 from first principles

    Science.gov (United States)

    Oikkonen, L. E.; Ganchenkova, M. G.; Seitsonen, A. P.; Nieminen, R. M.

    2014-08-01

    The electronic properties of high-efficiency CuInSe2 (CIS)-based solar cells are affected by the microstructural features of the absorber layer, such as point defect types and their distribution. Recently, there has been controversy over whether some of the typical point defects in CIS—VCu, VSe, InCu, CuIn—can form stable complexes in the material. In this work, we demonstrate that the presence of defect complexes during device operational time can be justified by taking into account the thermodynamic and kinetic driving forces acting behind defect microstructure formation. Our conclusions are backed up by thorough state-of-the-art calculations of defect interaction potentials as well as the activation barriers surrounding the complexes. Defect complexes such as InCu-2VCu, InCu-CuIn, and VSe-VCu are shown to be stable against thermal dissociation at device operating temperatures, but can anneal out within tens of minutes at temperatures higher than 150-200 °C (VCu-related complexes) or 400 °C (antisite pair). Our results suggest that the presence of these complexes can be controlled via growth temperatures, which provides a mechanism for tuning the electronic activity of defects and the device altogether.

  3. Storage and Effective Migration of Li-Ion for Defected β-LiFePO4 Phase Nanocrystals.

    Science.gov (United States)

    Guo, Hua; Song, Xiaohe; Zhuo, Zengqing; Hu, Jiangtao; Liu, Tongchao; Duan, Yandong; Zheng, Jiaxin; Chen, Zonghai; Yang, Wanli; Amine, Khalil; Pan, Feng

    2016-01-13

    Lithium iron phosphate, a widely used cathode material, crystallizes typically in olivine-type phase, α-LiFePO4 (αLFP). However, the new phase β-LiFePO4 (βLFP), which can be transformed from αLFP under high temperature and pressure, is originally almost electrochemically inactive with no capacity for Li-ion battery, because the Li-ions are stored in the tetrahedral [LiO4] with very high activation barrier for migration and the one-dimensional (1D) migration channels for Li-ion diffusion in αLFP disappear, while the Fe ions in the β-phase are oriented similar to the 1D arrangement instead. In this work, using experimental studies combined with density functional theory calculations, we demonstrate that βLFP can be activated with creation of effective paths of Li-ion migration by optimized disordering. Thus, the new phase of βLFP cathode achieved a capacity of 128 mAh g(-1) at a rate of 0.1 C (1C = 170 mA g(-1)) with extraordinary cycling performance that 94.5% of the initial capacity retains after 1000 cycles at 1 C. The activation mechanism can be attributed to that the induced disorder (such as FeLiLiFe antisite defects, crystal distortion, and amorphous domains) creates new lithium migration passages, which free the captive stored lithium atoms and facilitate their intercalation/deintercalation from the cathode. Such materials activated by disorder are promising candidate cathodes for lithium batteries, and the related mechanism of storage and effective migration of Li-ions also provides new clues for future design of disordered-electrode materials with high capacity and high energy density.

  4. Defective neuroepithelial cell cohesion affects tangential branchiomotor neuron migration in the zebrafish neural tube.

    Science.gov (United States)

    Stockinger, Petra; Maître, Jean-Léon; Heisenberg, Carl-Philipp

    2011-11-01

    Facial branchiomotor neurons (FBMNs) in zebrafish and mouse embryonic hindbrain undergo a characteristic tangential migration from rhombomere (r) 4, where they are born, to r6/7. Cohesion among neuroepithelial cells (NCs) has been suggested to function in FBMN migration by inhibiting FBMNs positioned in the basal neuroepithelium such that they move apically between NCs towards the midline of the neuroepithelium instead of tangentially along the basal side of the neuroepithelium towards r6/7. However, direct experimental evaluation of this hypothesis is still lacking. Here, we have used a combination of biophysical cell adhesion measurements and high-resolution time-lapse microscopy to determine the role of NC cohesion in FBMN migration. We show that reducing NC cohesion by interfering with Cadherin 2 (Cdh2) activity results in FBMNs positioned at the basal side of the neuroepithelium moving apically towards the neural tube midline instead of tangentially towards r6/7. In embryos with strongly reduced NC cohesion, ectopic apical FBMN movement frequently results in fusion of the bilateral FBMN clusters over the apical midline of the neural tube. By contrast, reducing cohesion among FBMNs by interfering with Contactin 2 (Cntn2) expression in these cells has little effect on apical FBMN movement, but reduces the fusion of the bilateral FBMN clusters in embryos with strongly diminished NC cohesion. These data provide direct experimental evidence that NC cohesion functions in tangential FBMN migration by restricting their apical movement.

  5. Tumorigenic fragments of APC cause dominant defects in directional cell migration in multiple model systems

    Directory of Open Access Journals (Sweden)

    Scott A. Nelson

    2012-11-01

    Nonsense mutations that result in the expression of truncated, N-terminal, fragments of the adenomatous polyposis coli (APC tumour suppressor protein are found in most sporadic and some hereditary colorectal cancers. These mutations can cause tumorigenesis by eliminating β-catenin-binding sites from APC, which leads to upregulation of β-catenin and thereby results in the induction of oncogenes such as MYC. Here we show that, in three distinct experimental model systems, expression of an N-terminal fragment of APC (N-APC results in loss of directionality, but not speed, of cell motility independently of changes in β-catenin regulation. We developed a system to culture and fluorescently label live pieces of gut tissue to record high-resolution three-dimensional time-lapse movies of cells in situ. This revealed an unexpected complexity of normal gut cell migration, a key process in gut epithelial maintenance, with cells moving with spatial and temporal discontinuity. Quantitative comparison of gut tissue from wild-type mice and APC heterozygotes (APCMin/+; multiple intestinal neoplasia model demonstrated that cells in precancerous epithelia lack directional preference when moving along the crypt-villus axis. This effect was reproduced in diverse experimental systems: in developing chicken embryos, mesoderm cells expressing N-APC failed to migrate normally; in amoeboid Dictyostelium, which lack endogenous APC, expressing an N-APC fragment maintained cell motility, but the cells failed to perform directional chemotaxis; and multicellular Dictyostelium slug aggregates similarly failed to perform phototaxis. We propose that N-terminal fragments of APC represent a gain-of-function mutation that causes cells within tissue to fail to migrate directionally in response to relevant guidance cues. Consistent with this idea, crypts in histologically normal tissues of APCMin/+ intestines are overpopulated with cells, suggesting that a lack of migration might cause cell

  6. First-Principles Study of Hydrogen Impact on the Formation and Migration of Helium Interstitial Defects in hcp Titanium

    Institute of Scientific and Technical Information of China (English)

    LU Yong-Fang; SHI Li-Qun; DING Wei; LONG Xing-Gui

    2012-01-01

    We present a first-principles study of the effects of hydrogen on helium behavior in hcp titanium.The calculation indicates that the dissolved H atoms in hcp Ti change the formation energy of the interstitial He atom,but they do not change the energetically favorable occupying site of the He atom,i.e.,the tetrahedral site is more favorable than the octahedral site.The impacts of H on the formation of interstitial He defects are directly related to the atomic environment around H atoms and their positions relative to interstitial He atoms as well.For He diffusion,a tetrahedral interstitial He atom can more easily migrate along the indirect tetrahedron-octahedron-tetrahedron path than the direct path of tetrahedron-tetrahedron.When a H atom exists in the first neighbor octahedral site from the He,the activation energy for He atom diffusion is 0.46eV,which is higher than that of the He atom diffusion in perfect crystal,0.41 eV.Increasing the number of H atoms to two,He diffusion needs much higher activation energy.This suggests that the H atoms around interstitial He may impede the migration of interstitial He atom in hcp Ti.%We present a first-principles study of the effects of hydrogen on helium behavior in hep titanium. The calculation indicates that the dissolved H atoms in hcp Ti change the formation energy of the interstitial He atom, but they do not change the energetically favorable occupying site of the He atom, I.e., the tetrahedral site is more favorable than the octahedral site. The impacts of H on the formation of interstitial He defects are directly related to the atomic environment around H atoms and their positions relative to interstitial He atoms as well. For He diffusion, a tetrahedral interstitial He atom can more easily migrate along the indirect tetrahedron-octahedron-tetrahedron path than the direct path of tetrahedron-tetrahedron. When a H atom exists in the first neighbor octahedral site from the He, the activation energy for He atom diffusion

  7. Ablation of the 14-3-3gamma Protein Results in Neuronal Migration Delay and Morphological Defects in the Developing Cerebral Cortex.

    Science.gov (United States)

    Wachi, Tomoka; Cornell, Brett; Marshall, Courtney; Zhukarev, Vladimir; Baas, Peter W; Toyo-oka, Kazuhito

    2016-06-01

    14-3-3 proteins are ubiquitously-expressed and multifunctional proteins. There are seven isoforms in mammals with a high level of homology, suggesting potential functional redundancy. We previously found that two of seven isoforms, 14-3-3epsilon and 14-3-3zeta, are important for brain development, in particular, radial migration of pyramidal neurons in the developing cerebral cortex. In this work, we analyzed the function of another isoform, the protein 14-3-3gamma, with respect to neuronal migration in the developing cortex. We found that in utero 14-3-3gamma-deficiency resulted in delays in neuronal migration as well as morphological defects. Migrating neurons deficient in 14-3-3gamma displayed a thicker leading process stem, and the basal ends of neurons were not able to reach the boundary between the cortical plate and the marginal zone. Consistent with the results obtained from in utero electroporation, time-lapse live imaging of brain slices revealed that the ablation of the 14-3-3gamma proteins in pyramidal neurons slowed down their migration. In addition, the 14-3-3gamma deficient neurons showed morphological abnormalities, including increased multipolar neurons with a thicker leading processes stem during migration. These results indicate that the 14-3-3gamma proteins play an important role in radial migration by regulating the morphology of migrating neurons in the cerebral cortex. The findings underscore the pathological phenotypes of brain development associated with the disruption of different 14-3-3 proteins and will advance the preclinical data regarding disorders caused by neuronal migration defects.

  8. Theoretical and experimental investigation of defect formation / migration in Gd2Ti2O7: General rule of oxide-ion migration in A2B2O7 pyrochlore

    Directory of Open Access Journals (Sweden)

    Kaoru Nakamura

    2016-11-01

    Full Text Available We investigated the intrinsic defect formation energy and oxide-ion migration mechanism in Gd2Ti2O7 pyrochlore. It was found that the vacancy formation energy of Gd is lower than that of Ti. For the oxygen vacancy, O(48f was found to show lower vacancy formation energy than O(8b. The formation energy of the vacancy complex showed that the Gd vacancy is accompanied with the O(48f vacancy, which is consistent with our experiment. The migration energy of O(48f along the direction, which is dominant migration path for ionic conduction, was calculated to be 0.43 eV. On the other hand, we found that Gd vacancy increases O(48f migration energy. For example, the migration energy of O(48f along the direction was increased to be 1.36 eV by the local compressive strain around Gd vacancy. This finding could explain our previous experimental result of decreasing conductivity with increasing Gd deficiency. Along with the oxide-ion migration mechanism in Gd2Ti2O7, O(48f migration energies along both and directions for various A2B2O7 pyrochlore structures were investigated. As a general trend of oxide-ion migration in the pyrochlore structure, we propose that O(48f migration along the direction is governed by the strength of B–O bonding. On the other hand, the ratio of ionic radius B/A is proposed to determine O(48f migration along the direction in A2B2O7 pyrochlore.

  9. Defective neuronal migration and inhibition of bipolar to multipolar transition of migrating neural cells by Mesoderm-Specific Transcript, Mest, in the developing mouse neocortex.

    Science.gov (United States)

    Ji, Liting; Bishayee, Kausik; Sadra, Ali; Choi, Seunghyuk; Choi, Wooyul; Moon, Sungho; Jho, Eek-Hoon; Huh, Sung-Oh

    2017-07-04

    Brain developmental disorders such as lissencephaly can result from faulty neuronal migration and differentiation during the formation of the mammalian neocortex. The cerebral cortex is a modular structure, where developmentally, newborn neurons are generated as a neuro-epithelial sheet and subsequently differentiate, migrate and organize into their final positions in the cerebral cortical plate via a process involving both tangential and radial migration. The specific role of Mest, an imprinted gene, in neuronal migration has not been previously studied. In this work, we reduced expression of Mest with in utero electroporation of neuronal progenitors in the developing embryonic mouse neocortex. Reduction of Mest levels by shRNA significantly reduced the number of neurons migrating to the cortical plate. Also, Mest-knockdown disrupted the transition of bipolar neurons into multipolar neurons migrating out of the sub-ventricular zone region. The migrating neurons also adopted a more tangential migration pattern upon knockdown of the Mest message, losing their potential to attach to radial glia cells, required for radial migration. The differentiation and migration properties of neurons via Wnt-Akt signaling were affected by Mest changes. In addition, miR-335, encoded in a Mest gene intron, was identified as being responsible for blocking the default tangential migration of the neurons. Our results suggest that Mest and its intron product, miR-335, play important roles in neuronal migration with Mest regulating the morphological transition of primary neurons required in the formation of the mammalian neocortex. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

  10. Hydrodynamics of freely swimming flagellates

    Science.gov (United States)

    Dolger, Julia; Nielsen, Lasse Tor; Kiorboe, Thomas; Bohr, Tomas; Andersen, Anders

    2016-11-01

    Flagellates are a diverse group of unicellular organisms forming an important part of the marine ecosystem. The arrangement of flagella around the cell serves as a key trait optimizing and compromising essential functions. With micro-particle image velocimetry we observed time-resolved near-cell flows around freely swimming flagellates, and we developed an analytical model based on the Stokes flow around a solid sphere propelled by a variable number of differently placed, temporally varying point forces, each representing one flagellum. The model allows us to reproduce the observed flow patterns and swimming dynamics, and to extract quantities such as swimming velocities and prey clearance rates as well as flow disturbances revealing the organism to flow-sensing predators. Our results point to optimal flagellar arrangements and beat patterns, and essential trade-offs. For biflagellates with two symmetrically arranged flagella we contrasted two species using undulatory and ciliary beat patterns, respectively, and found breast-stroke type beat patterns with equatorial power strokes to be favorable for fast as well as quiet swimming. The Centre for Ocean Life is a VKR Centre of Excellence supported by the Villum Foundation.

  11. In situ study of defect migration kinetics and self-healing of twin boundaries in heavy ion irradiated nanotwinned metals.

    Science.gov (United States)

    Li, J; Yu, K Y; Chen, Y; Song, M; Wang, H; Kirk, M A; Li, M; Zhang, X

    2015-05-13

    High energy particles introduce severe radiation damage in metallic materials, such as Ag. Here we report on the study on twin boundary (TB) affected zone in irradiated nanotwinned Ag wherein time accumulative defect density and defect diffusivity are substantially different from those in twin interior. In situ studies also reveal surprising resilience and self-healing of TBs in response to radiation. This study provides further support for the design of radiation-tolerant nanotwinned metallic materials.

  12. Depletion of Aspergillus nidulans cotA causes a severe polarity defect which is not suppressed by the nuclear migration mutation nudA2.

    Science.gov (United States)

    Johns, Sarah Anne; Leeder, Abigail Claire; Safaie, Mehran; Turner, Geoffrey

    2006-06-01

    The Aspergillus nidulans homologue of Neurospora crassa cot-1, cotA, encoding a member of the NDR protein kinase family, has been cloned and expressed under the control of the conditional alcA promoter. Depletion of CotA by repression of the alcA promoter led to a severe growth defect accompanied by loss of polarity. Germlings show greatly enlarged volume of the spores and hyphae, accompanied by an increase in number of nuclei per compartment, though the nucleus/volume ratio is not significantly altered. The depleted CotA phenotype was not suppressed by a nuclear migration mutation nudA2. Double mutants showed an additive, defective phenotype, unlike the suppression of the cot-1 ts mutation by ropy mutations seen in N. crassa, suggesting a different relationship between nuclear migration and the cot signalling pathway in A. nidulans. A functional CotA-GFP fusion protein was found in punctate regions of fluorescence similar to the distribution reported for human NDR2, and as a cap at the hyphal tip.

  13. Kinetic Monte Carlo studies of the reaction kinetics of crystal defects that diffuse one-dimensionally with occasional transverse migration

    DEFF Research Database (Denmark)

    Heinisch, H.L.; Trinkaus, H.; Singh, Bachu Narain

    2007-01-01

    and confirmed by kinetic Monte Carlo (KMC) simulations. Here we report on KMC simulations investigating a different transition from 1D to 3D diffusion of 1D gliding loops for which their 1D migration is interrupted by occasional 2D migration due to conservative climb by dislocation core diffusion within a plane...... transverse to their 1D glide direction. Their transition from 1D to 3D kinetics is significantly different from that due to direction changes. The KMC results are compared to an analytical description of this diffusion mode in the form of a master curve relating the 1D normalized sink strength...

  14. Brainstem respiratory oscillators develop independently of neuronal migration defects in the Wnt/PCP mouse mutant looptail.

    Directory of Open Access Journals (Sweden)

    Muriel Thoby-Brisson

    Full Text Available The proper development and maturation of neuronal circuits require precise migration of component neurons from their birthplace (germinal zone to their final positions. Little is known about the effects of aberrant neuronal position on the functioning of organized neuronal groups, especially in mammals. Here, we investigated the formation and properties of brainstem respiratory neurons in looptail (Lp mutant mice in which facial motor neurons closely apposed to some respiratory neurons fail to migrate due to loss of function of the Wnt/Planar Cell Polarity (PCP protein Vangl2. Using calcium imaging and immunostaining on embryonic hindbrain preparations, we found that respiratory neurons constituting the embryonic parafacial oscillator (e-pF settled at the ventral surface of the medulla in Vangl2(Lp/+ and Vangl2(Lp/Lp embryos despite the failure of tangential migration of its normally adjacent facial motor nucleus. Anatomically, the e-pF neurons were displaced medially in Lp/+ embryos and rostro-medially Lp/Lp embryos. Pharmacological treatments showed that the e-pF oscillator exhibited characteristic network properties in both Lp/+ and Lp/Lp embryos. Furthermore, using hindbrain slices, we found that the other respiratory oscillator, the preBötzinger complex, was also anatomically and functionally established in Lp mutants. Importantly, the displaced e-pF oscillator established functional connections with the preBötC oscillator in Lp/+ mutants. Our data highlight the robustness of the developmental processes that assemble the neuronal networks mediating an essential physiological function.

  15. Layered hydrogels accelerate iPSC-derived neuronal maturation and reveal migration defects caused by MeCP2 dysfunction

    Science.gov (United States)

    Zhang, Zhen-Ning; Freitas, Beatriz C.; Qian, Hao; Lux, Jacques; Acab, Allan; Trujillo, Cleber A.; Herai, Roberto H.; Nguyen Huu, Viet Anh; Wen, Jessica H.; Joshi-Barr, Shivanjali; Karpiak, Jerome V.; Engler, Adam J.; Fu, Xiang-Dong; Muotri, Alysson R.; Almutairi, Adah

    2016-03-01

    Probing a wide range of cellular phenotypes in neurodevelopmental disorders using patient-derived neural progenitor cells (NPCs) can be facilitated by 3D assays, as 2D systems cannot entirely recapitulate the arrangement of cells in the brain. Here, we developed a previously unidentified 3D migration and differentiation assay in layered hydrogels to examine how these processes are affected in neurodevelopmental disorders, such as Rett syndrome. Our soft 3D system mimics the brain environment and accelerates maturation of neurons from human induced pluripotent stem cell (iPSC)-derived NPCs, yielding electrophysiologically active neurons within just 3 wk. Using this platform, we revealed a genotype-specific effect of methyl-CpG-binding protein-2 (MeCP2) dysfunction on iPSC-derived neuronal migration and maturation (reduced neurite outgrowth and fewer synapses) in 3D layered hydrogels. Thus, this 3D system expands the range of neural phenotypes that can be studied in vitro to include those influenced by physical and mechanical stimuli or requiring specific arrangements of multiple cell types.

  16. Defect production in ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J. [Oak Ridge National Lab., TN (United States); Kinoshita, C. [Kyushu Univ. (Japan)

    1997-08-01

    A review is given of several important defect production and accumulation parameters for irradiated ceramics. Materials covered in this review include alumina, magnesia, spinel silicon carbide, silicon nitride, aluminum nitride and diamond. Whereas threshold displacement energies for many ceramics are known within a reasonable level of uncertainty (with notable exceptions being AIN and Si{sub 3}N{sub 4}), relatively little information exists on the equally important parameters of surviving defect fraction (defect production efficiency) and point defect migration energies for most ceramics. Very little fundamental displacement damage information is available for nitride ceramics. The role of subthreshold irradiation on defect migration and microstructural evolution is also briefly discussed.

  17. A freely-moving monkey treadmill model

    Science.gov (United States)

    Foster, Justin D.; Nuyujukian, Paul; Freifeld, Oren; Gao, Hua; Walker, Ross; Ryu, Stephen I.; Meng, Teresa H.; Murmann, Boris; Black, Michael J.; Shenoy, Krishna V.

    2014-08-01

    Objective. Motor neuroscience and brain-machine interface (BMI) design is based on examining how the brain controls voluntary movement, typically by recording neural activity and behavior from animal models. Recording technologies used with these animal models have traditionally limited the range of behaviors that can be studied, and thus the generality of science and engineering research. We aim to design a freely-moving animal model using neural and behavioral recording technologies that do not constrain movement. Approach. We have established a freely-moving rhesus monkey model employing technology that transmits neural activity from an intracortical array using a head-mounted device and records behavior through computer vision using markerless motion capture. We demonstrate the flexibility and utility of this new monkey model, including the first recordings from motor cortex while rhesus monkeys walk quadrupedally on a treadmill. Main results. Using this monkey model, we show that multi-unit threshold-crossing neural activity encodes the phase of walking and that the average firing rate of the threshold crossings covaries with the speed of individual steps. On a population level, we find that neural state-space trajectories of walking at different speeds have similar rotational dynamics in some dimensions that evolve at the step rate of walking, yet robustly separate by speed in other state-space dimensions. Significance. Freely-moving animal models may allow neuroscientists to examine a wider range of behaviors and can provide a flexible experimental paradigm for examining the neural mechanisms that underlie movement generation across behaviors and environments. For BMIs, freely-moving animal models have the potential to aid prosthetic design by examining how neural encoding changes with posture, environment and other real-world context changes. Understanding this new realm of behavior in more naturalistic settings is essential for overall progress of basic

  18. A freely-moving monkey treadmill model.

    Science.gov (United States)

    Foster, Justin D; Nuyujukian, Paul; Freifeld, Oren; Gao, Hua; Walker, Ross; I Ryu, Stephen; H Meng, Teresa; Murmann, Boris; J Black, Michael; Shenoy, Krishna V

    2014-08-01

    Motor neuroscience and brain-machine interface (BMI) design is based on examining how the brain controls voluntary movement, typically by recording neural activity and behavior from animal models. Recording technologies used with these animal models have traditionally limited the range of behaviors that can be studied, and thus the generality of science and engineering research. We aim to design a freely-moving animal model using neural and behavioral recording technologies that do not constrain movement. We have established a freely-moving rhesus monkey model employing technology that transmits neural activity from an intracortical array using a head-mounted device and records behavior through computer vision using markerless motion capture. We demonstrate the flexibility and utility of this new monkey model, including the first recordings from motor cortex while rhesus monkeys walk quadrupedally on a treadmill. Using this monkey model, we show that multi-unit threshold-crossing neural activity encodes the phase of walking and that the average firing rate of the threshold crossings covaries with the speed of individual steps. On a population level, we find that neural state-space trajectories of walking at different speeds have similar rotational dynamics in some dimensions that evolve at the step rate of walking, yet robustly separate by speed in other state-space dimensions. Freely-moving animal models may allow neuroscientists to examine a wider range of behaviors and can provide a flexible experimental paradigm for examining the neural mechanisms that underlie movement generation across behaviors and environments. For BMIs, freely-moving animal models have the potential to aid prosthetic design by examining how neural encoding changes with posture, environment and other real-world context changes. Understanding this new realm of behavior in more naturalistic settings is essential for overall progress of basic motor neuroscience and for the successful

  19. Virtual reality for freely moving animals.

    Science.gov (United States)

    Stowers, John R; Hofbauer, Maximilian; Bastien, Renaud; Griessner, Johannes; Higgins, Peter; Farooqui, Sarfarazhussain; Fischer, Ruth M; Nowikovsky, Karin; Haubensak, Wulf; Couzin, Iain D; Tessmar-Raible, Kristin; Straw, Andrew D

    2017-08-21

    Standard animal behavior paradigms incompletely mimic nature and thus limit our understanding of behavior and brain function. Virtual reality (VR) can help, but it poses challenges. Typical VR systems require movement restrictions but disrupt sensorimotor experience, causing neuronal and behavioral alterations. We report the development of FreemoVR, a VR system for freely moving animals. We validate immersive VR for mice, flies, and zebrafish. FreemoVR allows instant, disruption-free environmental reconfigurations and interactions between real organisms and computer-controlled agents. Using the FreemoVR platform, we established a height-aversion assay in mice and studied visuomotor effects in Drosophila and zebrafish. Furthermore, by photorealistically mimicking zebrafish we discovered that effective social influence depends on a prospective leader balancing its internally preferred directional choice with social interaction. FreemoVR technology facilitates detailed investigations into neural function and behavior through the precise manipulation of sensorimotor feedback loops in unrestrained animals.

  20. Enhanced Healing of Rat Calvarial Bone Defects with Hypoxic Conditioned Medium from Mesenchymal Stem Cells through Increased Endogenous Stem Cell Migration via Regulation of ICAM-1 Targeted-microRNA-221.

    Science.gov (United States)

    Chang, Woochul; Kim, Ran; Park, Sang In; Jung, Yu Jin; Ham, Onju; Lee, Jihyun; Kim, Ji Hyeong; Oh, Sekyung; Lee, Min Young; Kim, Jongmin; Park, Moon-Seo; Chung, Yong-An; Hwang, Ki-Chul; Maeng, Lee-So

    2015-07-01

    The use of conditioned medium from mesenchymal stem cells may be a feasible approach for regeneration of bone defects through secretion of various components of mesenchymal stem cells such as cytokines, chemokines, and growth factors. Mesenchymal stem cells secrete and accumulate multiple factors in conditioned medium under specific physiological conditions. In this study, we investigated whether the conditioned medium collected under hypoxic condition could effectively influence bone regeneration through enhanced migration and adhesion of endogenous mesenchymal stem cells. Cell migration and adhesion abilities were increased through overexpression of intercellular adhesion molecule-1 in hypoxic conditioned medium treated group. Intercellular adhesion molecule-1 was upregulated by microRNA-221 in mesenchymal stem cells because microRNAs are key regulators of various biological functions via gene expression. To investigate the effects in vivo, evaluation of bone regeneration by computed tomography and histological assays revealed that osteogenesis was enhanced in the hypoxic conditioned medium group relative to the other groups. These results suggest that behavioral changes of endogenous mesenchymal stem cells through microRNA-221 targeted-intercellular adhesion molecule-1 expression under hypoxic conditions may be a potential treatment for patients with bone defects.

  1. Critical Survey of the Freely Available Arabic Corpora

    OpenAIRE

    Zaghouani, Wajdi

    2017-01-01

    The availability of corpora is a major factor in building natural language processing applications. However, the costs of acquiring corpora can prevent some researchers from going further in their endeavours. The ease of access to freely available corpora is urgent needed in the NLP research community especially for language such as Arabic. Currently, there is not easy was to access to a comprehensive and updated list of freely available Arabic corpora. We present in this paper, the results o...

  2. Biometrics and international migration.

    Science.gov (United States)

    Redpath, Jillyanne

    2007-01-01

    This paper will focus on the impact of the rapid expansion in the use of biometric systems in migration management on the rights of individuals; it seeks to highlight legal issues for consideration in implementing such systems, taking as the starting point that the security interests of the state and the rights of the individual are not, and should not be, mutually exclusive. The first part of this paper briefly describes the type of biometric applications available, how biometric systems function, and those used in migration management. The second part examines the potential offered by biometrics for greater security in migration management, and focuses on developments in the use of biometrics as a result of September 11. The third part discusses the impact of the use of biometrics in the management of migration on the individual's right to privacy and ability to move freely and lawfully. The paper highlights the increasing need for domestic and international frameworks to govern the use of biometric applications in the migration/security context, and proposes a number of issues that such frameworks could address.

  3. DFT study of the effect of hydrostatic pressure on formation and migration enthalpies of intrinsic point defects in single crystal Si

    Energy Technology Data Exchange (ETDEWEB)

    Sueoka, Koji; Kamiyama, Eiji; Kariyazaki, Hiroaki [Department of Communication Engineering, Okayama Prefectural University, 111 Kuboki, Soja, Okayama 719-1197 (Japan); Vanhellemont, Jan [Department of Solid State Sciences, Ghent University, Krijgslaan 281-S1, 9000 Gent (Belgium)

    2012-10-15

    The dependence of the formation enthalpy (H{sub f}) of the self-interstitial I and the vacancy V on the hydrostatic pressure P was obtained by calculating the formation energy (E{sub f}) and the relaxation volume (v{sub f}). The dependence of the migration enthalpy (H{sub m}) of I and V on the pressure P was also obtained by calculating the change of H{sub f} during the migration. Density functional theory calculations were used with 216-atom supercells and with special attention for the convergence of the calculations. The neutral I and V are found to have quasi constant formation energies E{sub f}{sup I} and E{sub f}{sup V} for pressures between - 1 GPa to 1 GPa. For the relaxation volume, v{sub f}{sup I} is almost constant while v{sub f}{sup V} decreases with increasing pressure P. The formation and migration enthalpies H{sub f}{sup I} and H{sub m}{sup I}, respectively, at the [110] dumbbell site are given by H{sub f}{sup I} = 3.425 - 0.055 x P (eV) and H{sub m}{sup I} = 0.981 - 0.039 x P (eV) with hydrostatic pressure P given in GPa. The H{sub f}{sup V} and H{sub m}{sup V} dependencies on P are given by H{sub f}{sup V} =3.543 - 0.024 x P{sup 2}- 0.009 x P (eV) and H{sub m}{sup V} = 0.249 + 0.005 x P{sup 2} - 0.030 x P (eV). These results indicate that hydrostatic pressure leads to a slight increase of the equilibrium concentration and diffusion of vacancies but this increase is considerably smaller than that of self-interstitials (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Crank inertial load affects freely chosen pedal rate during cycling.

    Science.gov (United States)

    Hansen, Ernst Albin; Jørgensen, Lars Vincents; Jensen, Kurt; Fregly, Benjamin Jon; Sjøgaard, Gisela

    2002-02-01

    Cyclists seek to maximize performance during competition, and gross efficiency is an important factor affecting performance. Gross efficiency is itself affected by pedal rate. Thus, it is important to understand factors that affect freely chosen pedal rate. Crank inertial load varies greatly during road cycling based on the selected gear ratio. Nevertheless, the possible influence of crank inertial load on freely chosen pedal rate and gross efficiency has never been investigated. This study tested the hypotheses that during cycling with sub-maximal work rates, a considerable increase in crank inertial load would cause (1) freely chosen pedal rate to increase, and as a consequence, (2) gross efficiency to decrease. Furthermore, that it would cause (3) peak crank torque to increase if a constant pedal rate was maintained. Subjects cycled on a treadmill at 150 and 250W, with low and high crank inertial load, and with preset and freely chosen pedal rate. Freely chosen pedal rate was higher at high compared with low crank inertial load. Notably, the change in crank inertial load affected the freely chosen pedal rate as much as did the 100W increase in work rate. Along with freely chosen pedal rate being higher, gross efficiency at 250W was lower during cycling with high compared with low crank inertial load. Peak crank torque was higher during cycling at 90rpm with high compared with low crank inertial load. Possibly, the subjects increased the pedal rate to compensate for the higher peak crank torque accompanying cycling with high compared with low crank inertial load.

  5. Absence of both Sos-1 and Sos-2 in peripheral CD4(+) T cells leads to PI3K pathway activation and defects in migration.

    Science.gov (United States)

    Guittard, Geoffrey; Kortum, Robert L; Balagopalan, Lakshmi; Çuburu, Nicolas; Nguyen, Phan; Sommers, Connie L; Samelson, Lawrence E

    2015-08-01

    Sos-1 and Sos-2 are ubiquitously expressed Ras-guanine exchange factors involved in Erk-MAP kinase pathway activation. Using mice lacking genes encoding Sos-1 and Sos-2, we evaluated the role of these proteins in peripheral T-cell signaling and function. Our results confirmed that TCR-mediated Erk activation in peripheral CD4(+) T cells does not depend on Sos-1 and Sos-2, although IL-2-mediated Erk activation does. Unexpectedly, however, we show an increase in AKT phosphorylation in Sos-1/2dKO CD4(+) T cells upon TCR and IL-2 stimulation. Activation of AKT was likely a consequence of increased recruitment of PI3K to Grb2 upon TCR and/or IL-2 stimulation in Sos-1/2dKO CD4(+) T cells. The increased activity of the PI3K/AKT pathway led to downregulation of the surface receptor CD62L in Sos-1/2dKO T cells and a subsequent impairment in T-cell migration.

  6. Return migration.

    Science.gov (United States)

    Gmelch, G

    1980-01-01

    The author reviews the findings of the growing literature on return migration. Topics covered include typologies of return migrants, reasons for return, adaptation and readjustment of returnees, and the impact of return migration on the migrants' home societies. The focus of the study is on international return migration, migration to Northern Europe and northeastern North America, and return migration to the southern and eastern fringes of Europe and the Caribbean

  7. Humidity distribution affected by freely exposed water surfaces

    DEFF Research Database (Denmark)

    Hygum, Morten Arnfeldt; Popok, Vladimir

    2014-01-01

    Accurate models for the water vapor flux at a water-air interface are required in various scientific, reliability and civil engineering aspects. Here, a study of humidity distribution in a container with air and freely exposed water is presented. A model predicting a spatial distribution and time...

  8. Saccadic head and thorax movements in freely walking blowflies

    NARCIS (Netherlands)

    Blaj, G.; Hateren, J.H. van

    2004-01-01

    Visual information processing is adapted to the statistics of natural visual stimuli, and these statistics depend to a large extent on the movements of an animal itself. To investigate such movements in freely walking blowflies, we measured the orientation and position of their head and thorax, with

  9. Saccadic head and thorax movements in freely walking blowflies

    NARCIS (Netherlands)

    Blaj, G.; Hateren, J.H. van

    2004-01-01

    Visual information processing is adapted to the statistics of natural visual stimuli, and these statistics depend to a large extent on the movements of an animal itself. To investigate such movements in freely walking blowflies, we measured the orientation and position of their head and thorax, with

  10. Birth Defects

    Science.gov (United States)

    A birth defect is a problem that happens while a baby is developing in the mother's body. Most birth defects happen during the first 3 months of ... in the United States is born with a birth defect. A birth defect may affect how the ...

  11. Magnetic tracking of eye position in freely behaving chickens

    Directory of Open Access Journals (Sweden)

    Jason S Schwarz

    2013-11-01

    Full Text Available Research on the visual system of non-primates, such as birds and rodents, is increasing. Evidence that neural responses can differ dramatically between head-immobilized and freely behaving animals underlines the importance of studying visual processing in ethologically relevant contexts. In order to systematically study visual responses in freely behaving animals, an unobtrusive system for monitoring eye-in-orbit position in real time is essential. We describe a novel system for monitoring eye position that utilizes a head-mounted magnetic displacement sensor coupled with an eye-implanted magnet. This system is small, lightweight, and offers high temporal and spatial resolution in real time. We use the system to demonstrate the stability of the eye and the stereotypy of eye position during two different behavioral tasks in chickens. This approach offers a viable alternative to search coil and optical eye tracking techniques for high resolution tracking of eye-in-orbit positions in behaving animals.

  12. Magnetic tracking of eye position in freely behaving chickens

    Science.gov (United States)

    Schwarz, Jason S.; Sridharan, Devarajan; Knudsen, Eric I.

    2013-01-01

    Research on the visual system of non-primates, such as birds and rodents, is increasing. Evidence that neural responses can differ dramatically between head-immobilized and freely behaving animals underlines the importance of studying visual processing in ethologically relevant contexts. In order to systematically study visual responses in freely behaving animals, an unobtrusive system for monitoring eye-in-orbit position in real time is essential. We describe a novel system for monitoring eye position that utilizes a head-mounted magnetic displacement sensor coupled with an eye-implanted magnet. This system is small, lightweight, and offers high temporal and spatial resolution in real time. We use the system to demonstrate the stability of the eye and the stereotypy of eye position during two different behavioral tasks in chickens. This approach offers a viable alternative to search coil and optical eye tracking techniques for high resolution tracking of eye-in-orbit position in behaving animals. PMID:24312023

  13. Vibration transmission characteristics of the legs of freely standing honeybees

    DEFF Research Database (Denmark)

    Rohrseitz, Kristin; Kilpinen, Ole

    1997-01-01

    The leg vibrations of honeybees standing on a vibrating substrate were measured with laser Doppler vibrometry, both in freely standing bees and in bees attached to a holder. In both cases, no resonances were found. In the fixed bee preparation, the legs moved with approximately the same amplitude...... as the stimulator. This was also the case in freely standing honeybees, except around 400 Hz, where an average attenuation of approximately 6 dB was observed. In the fixed bee preparation, the vertical movements of the legs were also measured during horizontal stimulation. The vertical vibration amplitude...... of the legs was 15-20 dB lower than the horizontal stimulation amplitude. The electrophysiologically and behaviourally determined thresholds for vibration stimulation increased by approximately 10 dB, when the stimulus direction was changed from vertical to horizontal. These observations support the notion...

  14. Saccadic head and thorax movements in freely walking blowflies

    OpenAIRE

    Blaj, G.; van Hateren, J. H.

    2004-01-01

    Visual information processing is adapted to the statistics of natural visual stimuli, and these statistics depend to a large extent on the movements of an animal itself. To investigate such movements in freely walking blowflies, we measured the orientation and position of their head and thorax, with high spatial and temporal accuracy. Experiments were performed on Calliphora vicina, Lucilia cuprina and L. caesar. We found that thorax and head orientation of walking flies is typically differen...

  15. Soot Formation in Freely-Propagating Laminar Premixed Flames

    Science.gov (United States)

    Lin, K.-C.; Hassan, M. I.; Faeth, G. M.

    1997-01-01

    Soot formation within hydrocarbon-fueled flames is an important unresolved problem of combustion science. Thus, the present study is considering soot formation in freely-propagating laminar premixed flames, exploiting the microgravity environment to simplify measurements at the high-pressure conditions of interest for many practical applications. The findings of the investigation are relevant to reducing emissions of soot and continuum radiation from combustion processes, to improving terrestrial and spacecraft fire safety, and to developing methods of computational combustion, among others. Laminar premixed flames are attractive for studying soot formation because they are simple one-dimensional flows that are computationally tractable for detailed numerical simulations. Nevertheless, studying soot-containing burner-stabilized laminar premixed flames is problematical: spatial resolution and residence times are limited at the pressures of interest for practical applications, flame structure is sensitive to minor burner construction details so that experimental reproducibility is not very good, consistent burner behavior over the lengthy test programs needed to measure soot formation properties is hard to achieve, and burners have poor durability. Fortunately, many of these problems are mitigated for soot-containing, freely-propagating laminar premixed flames. The present investigation seeks to extend work in this laboratory for various soot processes in flames by observing soot formation in freely-propagating laminar premixed flames. Measurements are being made at both Normal Gravity (NG) and MicroGravity (MG), using a short-drop free-fall facility to provide MG conditions.

  16. Freely-tunable broadband polarization rotator for terahertz waves

    Science.gov (United States)

    Peng, Ru-Wen; Fan, Ren-Hao; Zhou, Yu; Jiang, Shang-Chi; Xiong, Xiang; Huang, Xian-Rong; Wang, Mu

    It is known that commercially-available terahertz (THz) emitters usually generate linearly polarized waves only along certain directions, but in practice, a polarization rotator that is capable of rotating the polarization of THz waves to any direction is particularly desirable and it will have various important applications. In this work, we demonstrate a freely tunable polarization rotator for broadband THz waves using a three-rotating-layer metallic grating structure, which can conveniently rotate the polarization of a linearly polarized THz wave to any desired direction with nearly perfect conversion efficiency. The device performance has been experimentally demonstrated by both THz transmission spectra and direct imaging. The polarization rotation originates from multi wave interference in the three-layer grating structure based on the scattering-matrix analysis. We can expect that this active broadband polarization rotator has wide applications in analytical chemistry, biology, communication technology, imaging, etc.. Reference: R. H. Fan, Y. Zhou, X. P. Ren, R. W. Peng, S. C. Jiang, D. H. Xu, X. Xiong, X. R. Huang, and Mu Wang, Advanced Materials 27,1201(2015). Freely-tunable broadband polarization rotator for terahertz waves.

  17. Structure and Dynamics of Freely Suspended Liquid Crystals

    Science.gov (United States)

    Clark, Noel A.

    2004-01-01

    Smectic liquid crystals are phases of rod shaped molecules organized into one dimensionally (1 D) periodic arrays of layers, each layer being between one and two molecular lengths thick. In the least ordered smectic phases, the smectics A and C, each layer is a two dimensional (2D) liquid. Additionally there are a variety of more ordered smectic phases having hexatic short range translational order or 2D crystalline or quasi long range translational order within the layers. The inherent fluid-layer structure and low vapor pressure of smectic liquid crystals enables the long term stabilization of freely suspended, single component, layered fluid films as thin as 30A, a single molecular layer. The layering forces the films to be an integral number of smectic layers thick, quantizing their thickness in layer units and forcing a film of a particular number of layers to be physically homogeneous with respect to its layer structure over its entire area. Optical reflectivity enables the precise determination of the number of layers. These ultrathin freely suspended liquid crystal films are structures of fundamental interest in condensed matter and fluid physics. They are the thinnest known stable fluid structures and have the largest surface-to-volume ratio of any stable fluid preparation, making them ideal for the study of the effects of reduced dimensionality on phase behavior and on fluctuation and interface phenomena. Their low vapor pressure and quantized thickness enable the effective use of microgravity to extend the study of basic capillary phenomena to ultrathin fluid films. Freely suspended films have been a wellspring of new LC physics. They have been used to provide unique experimental conditions for the study of condensed phase transitions in two dimensions. They are the only system in which the hexatic has been unambiguously identified as a phase of matter, and the only physical system in which fluctuations of a 2D XY system and Kosterlitz Thouless phase

  18. Low Mach number theory of freely cooling granular gases

    CERN Document Server

    Meerson, Baruch; Vilenkin, Arkady

    2007-01-01

    We use hydrodynamic equations to investigate the dynamics of a freely cooling dilute granular gas with nearly elastic particle collisions. We assume a narrow channel geometry and focus on the regime where the sound travel time through the system is much shorter than the typical cooling time of the gas. As a result, the pressure rapidly becomes almost homogeneous, while the Mach number is small. Eliminating the sound waves and employing Lagrangian coordinates, we reduce the full hydrodynamics to a single nonlinear/nonlocal equation of a reaction-diffusion type. This equation describes a broad class of flows and, in particular, can follow the development of strongly nonlinear states during clustering instability. Without heat diffusion, the reduced equation is exactly soluble and develops a finite-time density blowup with the same local features as those exhibited by the recently found family of exact solutions of the full set of ideal hydrodynamic equations (Fouxon et al. 2007). The heat diffusion, however, ar...

  19. ``Reverse'' Lock-in Regime on a Freely Oscillating Cylinder

    Science.gov (United States)

    Atsavapranee, P.; Voorhees, A. V.; Benaroya, H.; Wei, T.

    1998-11-01

    DPIV and flow visualizations were used to characterize the flow in the near wake of a freely oscillating cylinder. A rigid cylinder with a low mass ratio was fixed at one end to a leaf spring and free to oscillate, pendulum-like, at the other end in the cross stream plane. It was found that only a subset of the synchronization range follows the behavior of a ``classical'' lock-in, i.e., when the difference between the natural Strouhal frequency and the natural frequency of the cylinder is small enough, vortex shedding frequency deviates from the linear Strouhal dependence and follows instead the cylinder natural frequency. However, over a range of flow speed in which the response amplitude of the cylinder is significant, it was found that the frequency of oscillation and of vortex shedding follow instead the natural Strouhal frequency, instead of the mechanical natural frequency.

  20. Planet-disc interaction on a freely moving mesh

    CERN Document Server

    Munoz, Diego J; Springel, Volker; Hernquist, Lars

    2014-01-01

    General-purpose, moving-mesh schemes for hydrodynamics have opened the possibility of combining the accuracy of grid-based numerical methods with the flexibility and automatic resolution adaptivity of particle-based methods. Due to their supersonic nature, Keplerian accretion discs are in principle a very attractive system for applying such freely moving mesh techniques. However, the high degree of symmetry of simple accretion disc models can be difficult to capture accurately by these methods, due to the generation of geometric grid noise and associated numerical diffusion, which is absent in polar grids. To explore these and other issues, in this work we study the idealized problem of two-dimensional planet-disc interaction with the moving-mesh code AREPO. We explore the hydrodynamic evolution of discs with planets through a series of numerical experiments that vary the planet mass, the disc viscosity and the mesh resolution, and compare the resulting surface density, vortensity field and tidal torque with ...

  1. Structure, Hydrodynamics, and Phase Transition of Freely Suspended Liquid Crystals

    Science.gov (United States)

    Clark, Noel A.

    2000-01-01

    Smectic liquid crystals are phases of rod shaped molecules organized into one dimensionally (1D) periodic arrays of layers, each layer being between one and two molecular lengths thick. In the least ordered smectic phases, the smectics A and C, each layer is a two dimensional (2D) liquid. Additionally there are a variety of more ordered smectic phases having hexatic short range translational order or 2D crystalline quasi long range translational order within the layers. The inherent fluid-layer structure and low vapor pressure of smectic liquid crystals enable the long term stabilization of freely suspended, single component, layered fluid films as thin as 30A, a single molecular layer. The layering forces the films to be an integral number of smectic layers thick, quantizing their thickness in layer units and forcing a film of a particular number of layers to be physically homogeneous with respect to its layer structure over its entire area. Optical reflectivity enables the precise determination of the number of layers. These ultrathin freely suspended liquid crystal films are structures of fundamental interest in condensed matter and fluid physics. They are the thinnest known stable condensed phase fluid structures and have the largest surface-to-volume ratio of any stable fluid preparation, making them ideal for the study of the effects of reduced dimensionality on phase behavior and on fluctuation and interface phenomena. Their low vapor pressure and quantized thickness enable the effective use of microgravity to extend the study of basic capillary phenomena to ultrathin fluid films. Freely suspended films have been a wellspring of new liquid crystal physics. They have been used to provide unique experimental conditions for the study of condensed phase transitions in two dimensions. They are the only system in which the hexatic has been unambiguously identified as a phase of matter, and the only physical system in which fluctuations of a 2D XY system and

  2. The clustering morphology of freely rising deformable bubbles

    CERN Document Server

    Tagawa, Yoshiyuki; Prakash, Vivek N; Annaland, Martin van Sint; Kuipers, Hans; Sun, Chao; Lohse, Detlef

    2012-01-01

    We investigate the clustering morphology of a swarm of freely rising deformable bubbles. A three-dimensional Vorono\\"i analysis enables us to quantitatively distinguish between two typical clustering configurations: preferential clustering and a grid-like structure. The bubble data is obtained from direct numerical simulations (DNS) using the front-tracking method. It is found that the bubble deformation, represented by the aspect ratio \\chi, plays a significant role in determining which type of clustering is realized: Nearly spherical bubbles with \\chi <~ 1.015 form a grid-like structure, while more deformed bubbles show preferential clustering. Remarkably, this criteria for the clustering morphology holds for different diameters of the bubbles, surface tension, and viscosity of the liquid in the studied parameter regime. The mechanism of this clustering behavior is connected to the amount of vorticity generated at the bubble surfaces.

  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. Development of Cloud Based Casting Defects Categorization System (CDCS

    Directory of Open Access Journals (Sweden)

    Sata Amit V.

    2017-03-01

    Full Text Available Defects affect the properties and behavior of the casting during its service life. Since the defects can occur due to different reasons, they must be correctly identified and categorized, to enable applying the appropriate remedial measures. several different approaches for categorizing casting defects have been proposed in technical literature. They mainly rely on physical description, location, and formation of defects. There is a need for a systematic approach for classifying investment casting defects, considering appropriate attributes such as their size, location, identification stage, inspection method, consistency, appearance of defects. A systematic approach for categorization of investment casting defects considering multiple attributes: detection stage, size, shape, appearance, location, consistency and severity of occurrence. Information about the relevant attributes of major defects encountered in investment casting process has been collected from an industrial foundry. This has been implemented in a cloud-based system to make the system freely and widely accessible.

  5. Algebraic approach to multiple defects on the line and application to Casimir force

    CERN Document Server

    Mintchev, M

    2007-01-01

    An algebraic framework for quantization in presence of arbitrary number of point-like defects on the line is developed. We consider a scalar field which interacts with the defects and freely propagates away of them. As an application we compute the Casimir force both at zero and finite temperature. We derive also the charge density in the Gibbs state of a complex scalar field with defects. The example of two delta-defects is treated in detail.

  6. Defect recovery in aluminum irradiated with protons at 20 K

    DEFF Research Database (Denmark)

    Linderoth, S.; Rajainmäki, H.; Nieminen, R. M.

    1987-01-01

    Aluminum single crystals have been irradiated with 7.0-MeV protons at 20 K. The irradiation damage and its recovery are studied with positron-lifetime spectroscopy between 20 and 500 K. Stage-I recovery is observed at 40 K. At 240 K, loss of freely migrating vacancies is observed. Hydrogen...

  7. Dynamics of a freely-falling maple seed

    Science.gov (United States)

    Lee, Injae; Choi, Haecheon

    2016-11-01

    We conduct numerical simulations of a freely-falling maple seed using an immersed boundary method in a non-inertial reference frame. A three-dimensional seed model is obtained by scanning a maple seed. The seed reaches a steady autorotation after a transient period, and a stable leading-edge vortex is attached on the surface of the rotating seed, which increases the drag force during autorotation. In addition, two different approaches are considered to obtain scaling laws describing the relation among the seed weight and geometry, and descending and rotating velocities. The first uses the conservations of mass, linear and angular momentum, and energy. In this approach, a model constant to be determined, called axial induction factor, is obtained from the result of present simulation. The second approach employs a classical steady wing theory in which the vortical strength is scaled with the circulation around a wing and the lift force is modeled by the time derivative of vortical impulse. Available data on various seeds well fall on these scaling laws. Supported by NRF-2014M3C1B1033848.

  8. Freely decaying turbulence in force-free electrodynamics

    CERN Document Server

    Zrake, Jonathan

    2015-01-01

    Freely decaying relativistic force-free turbulence is studied for the first time. We initiate the magnetic field at a short wavelength and simulate its relaxation toward equilibrium on two and three dimensional periodic domains, in both helical and non-helical settings. Force-free turbulent relaxation is found to exhibit an inverse cascade in all settings, and in 3D to have a magnetic energy spectrum consistent with the Kolmogorov $5/3$ power law. 3D relaxations also obey the Taylor hypothesis; they settle promptly into the lowest energy configuration allowed by conservation of the total magnetic helicity. But in 2D, the relaxed state is a force-free equilibrium whose energy greatly exceeds the Taylor minimum, and which contains persistent force-free current layers and isolated flux tubes. We explain this behavior in terms of additional topological invariants that exist only in two dimensions, namely the helicity enclosed within each level surface of the magnetic potential function. The speed and completeness...

  9. FREELY DECAYING TURBULENCE IN FORCE-FREE ELECTRODYNAMICS

    Energy Technology Data Exchange (ETDEWEB)

    Zrake, Jonathan; East, William E. [Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States)

    2016-02-01

    Freely decaying, relativistic force-free turbulence is studied for the first time. We initiate the magnetic field at a short wavelength and simulate its relaxation toward equilibrium on two- and three-dimensional periodic domains in both helical and nonhelical settings. Force-free turbulent relaxation is found to exhibit an inverse cascade in all settings and in three dimensions to have a magnetic energy spectrum consistent with the Kolmogorov 5/3 power law. Three-dimensional relaxations also obey the Taylor hypothesis; they settle promptly into the lowest-energy configuration allowed by conservation of the total magnetic helicity. However, in two dimensions, the relaxed state is a force-free equilibrium whose energy greatly exceeds the Taylor minimum and that contains persistent force-free current layers and isolated flux tubes. We explain this behavior in terms of additional topological invariants that exist only in two dimensions, namely the helicity enclosed within each level surface of the magnetic potential function. The speed and completeness of turbulent magnetic free-energy discharge could help account for rapidly variable gamma-ray emission from the Crab Nebula, gamma-ray bursts, blazars, and radio galaxies.

  10. Near and far wake structures behind freely flying bats

    Science.gov (United States)

    Schunk, Cosima; Swartz, Sharon M.; Breuer, Kenneth S.

    2014-11-01

    While pseudo-volumetric reconstructions of the wakes of flying animals, based on transverse (Trefftz) wake measurements, have become a well-established tool in the study of animal aerodynamics in recent years, there are a number of concerns that persist regarding their use in estimating drag and flight efficiency. Here we report on stereo particle image velocimetry (PIV) measurements behind freely flying bats (Eptesicus fuscus) in both the transverse and streamwise planes. The streamwise plane measurements are taken on the wing as well as in the near and far wake region up to eight chord lengths behind the bat. By organizing the data according to the flight speed, wingbeat phase and the spanwise position of the laser sheet on the wing we are able to connect specific features of the wing and body geometry with observed wake structures and thereby construct a detailed time-space map of the wake. Furthermore, we can quantitatively assess wake distortion and assess the validity of lift and drag estimates based on transverse wake measurements. Supported by AFOSR.

  11. Saccadic head and thorax movements in freely walking blowflies.

    Science.gov (United States)

    Blaj, G; van Hateren, J H

    2004-11-01

    Visual information processing is adapted to the statistics of natural visual stimuli, and these statistics depend to a large extent on the movements of an animal itself. To investigate such movements in freely walking blowflies, we measured the orientation and position of their head and thorax, with high spatial and temporal accuracy. Experiments were performed on Calliphora vicina, Lucilia cuprina and L. caesar. We found that thorax and head orientation of walking flies is typically different from the direction of walking, with differences of 45 degrees common. During walking, the head and the thorax turn abruptly, with a frequency of 5-10 Hz and angular velocities in the order of 1,000 degrees /s. These saccades are stereotyped: head and thorax start simultaneously, with the head turning faster, and finishing its turn before the thorax. The changes in position during walking are saccade-like as well, occurring synchronously, but on average slightly after the orientation saccades. Between orientation saccades the angular velocities are low and the head is held more stable than the thorax. We argue that the strategy of turning by saccades improves the performance of the visual system of blowflies.

  12. Freely Falling Finite Frames Near a Black Hole

    CERN Document Server

    Biswas, Tarun

    2015-01-01

    It is well-known that the Riemann curvature tensor has no discontinuity at the black hole horizon. It is also well-known that a freely falling observer takes finite time to reach the horizon from an outside point. However, the usual assumption is that such an observer resides in a frame of reference (spaceship) of infinitesimal size. This assumption is justified as long as the coordinates are continuous enough to assume that the observer's frame is small compared to the variations of the metric from a local flat metric. Such an assumption may be invalid when the coordinate system has not only a discontinuity but a singularity like the one at the horizon. Hence, here, the characteristics of a finite frame (a spaceship) near a black hole horizon is discussed. It is shown that clocks placed at the front and rear ends have different time scales even in the limit when they reach the horizon at the same time. This renders such a frame physically meaningless. It is also argued that the forces that are expected to ke...

  13. Intersegmental coupling and recovery from perturbations in freely running cockroaches.

    Science.gov (United States)

    Couzin-Fuchs, Einat; Kiemel, Tim; Gal, Omer; Ayali, Amir; Holmes, Philip

    2015-01-15

    Cockroaches are remarkably stable runners, exhibiting rapid recovery from external perturbations. To uncover the mechanisms behind this important behavioral trait, we recorded leg kinematics of freely running animals in both undisturbed and perturbed trials. Functional coupling underlying inter-leg coordination was monitored before and during localized perturbations, which were applied to single legs via magnetic impulses. The resulting transient effects on all legs and the recovery times to normal pre-perturbation kinematics were studied. We estimated coupling architecture and strength by fitting experimental data to a six-leg-unit phase oscillator model. Using maximum-likelihood techniques, we found that a network with nearest-neighbor inter-leg coupling best fitted the data and that, although coupling strengths vary among preparations, the overall inputs entering each leg are approximately balanced and consistent. Simulations of models with different coupling strengths encountering perturbations suggest that the coupling schemes estimated from our experiments allow animals relatively fast and uniform recoveries from perturbations. © 2015. Published by The Company of Biologists Ltd.

  14. CDYL Deficiency Disrupts Neuronal Migration and Increases Susceptibility to Epilepsy.

    Science.gov (United States)

    Qin, Rui; Cao, Shuai; Lyu, Tianjie; Qi, Cai; Zhang, Weiguang; Wang, Yun

    2017-01-10

    During brain development, the correct migration of newborn neurons is one of the determinants of circuit formation, and neuronal migration defects may lead to neurological and psychiatric disorders. The molecular mechanisms underlying neuronal migration and related disorders are poorly understood. Here, we report that Chromodomain Y-like (CDYL) is critical for neuronal migration in mice. Knocking down CDYL caused neuronal migration defects and disrupted both mobility and multipolar-to-bipolar transition of migrating neurons. We find that CDYL regulates neuronal migration by transcriptionally repressing RhoA. In addition, CDYL deficiency increased the excitability of cortical pyramidal neurons and the susceptibility of mice to convulsant-induced seizures. These results demonstrate that CDYL is a regulator of neuronal migration and shed light on the pathogenesis of seizure-related neurodevelopmental disorders. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  15. Paravaginal defect

    DEFF Research Database (Denmark)

    Arenholt, Louise T S; Pedersen, Bodil Ginnerup; Glavind, Karin;

    2016-01-01

    , arcus tendineus fascia pelvis (ATFP), pubocervical fascia, and uterosacral/cardinal ligaments. Studies conclude that physical examination is inconsistent in detecting paravaginal defects. Ultrasound (US) and magnetic resonance imaging (MRI) have been used to describe patterns in the appearance...

  16. Defects and defect processes in nonmetallic solids

    CERN Document Server

    Hayes, W

    2004-01-01

    This extensive survey covers defects in nonmetals, emphasizing point defects and point-defect processes. It encompasses electronic, vibrational, and optical properties of defective solids, plus dislocations and grain boundaries. 1985 edition.

  17. Atomic scale modeling of defect production and microstructure evolution in irradiated metals

    Energy Technology Data Exchange (ETDEWEB)

    Diaz de la Rubia, T.; Soneda, N.; Shimomura, Y. [Lawrence Livermore National Lab., CA (United States)] [and others

    1997-04-01

    Irradiation effects in materials depend in a complex way on the form of the as-produced primary damage state and its spatial and temporal evolution. Thus, while collision cascades produce defects on a time scale of tens of picosecond, diffusion occurs over much longer time scales, of the order of seconds, and microstructure evolution over even longer time scales. In this report the authors present work aimed at describing damage production and evolution in metals across all the relevant time and length scales. They discuss results of molecular dynamics simulations of displacement cascades in Fe and V. They show that interstitial clusters are produced in cascades above 5 keV, but not vacancy clusters. Next, they discuss the development of a kinetic Monte Carlo model that enables calculations of damage evolution over much longer time scales (1000`s of s) than the picosecond lifetime of the cascade. They demonstrate the applicability of the method by presenting predictions on the fraction of freely migrating defects in {alpha}Fe during irradiation at 600 K.

  18. Cortical epileptogenesis of slowly kindled freely moving rats

    Directory of Open Access Journals (Sweden)

    Orbán-Kis K.

    2014-12-01

    Full Text Available Objective. Epilepsy is a neurological disorder that can be caused by many underlying pathologies. The epileptic and interictal manifestations that appear during the progression of chronic epilepsy are still not understood completely. One of the most frequent forms of this disease is temporal lobe epilepsy in which is clear involvement of the hippocampal formation. In order to study the electrografic progression of untreated seizures we used amygdala kindling in freely moving rats. Methods. Seven animals were implanted with bilateral hippocampal and prefrontal electrodes. A bipolar electrode, implanted in the lateral nuclei of the left amygdala was used for stimulation. The kindled group of animals was stimulated daily with the minimum current intensity needed to reach the afterdischarge threshold. Behavioral changes during kindling were scored according to the Racine scale. Results. The average seizure severity on the Racine scale was 2.6±0.4 by day 6 and 4.4±0.6 by day 20. The first spontaneous seizures appeared after 31 days of stimulation. During spontaneous seizures the preictal spike full width at half maximum increased gradually from 51±4msec to 110±5msec (p < 0.05 whereas the amplitude of the negative field potential deflection increased by 62% (p < 0.05. Conclusions. Our study showed that the progression of temporal lobe epilepsy, as seen in humans, can be reproduced in the kindling model with high fidelity. This study confirms in vivo the increase in preictal spike duration as well as the increase of the amplitude of negative field potential deflection during the preictal period.

  19. Navigating freely-available software tools for metabolomics analysis.

    Science.gov (United States)

    Spicer, Rachel; Salek, Reza M; Moreno, Pablo; Cañueto, Daniel; Steinbeck, Christoph

    2017-01-01

    The field of metabolomics has expanded greatly over the past two decades, both as an experimental science with applications in many areas, as well as in regards to data standards and bioinformatics software tools. The diversity of experimental designs and instrumental technologies used for metabolomics has led to the need for distinct data analysis methods and the development of many software tools. To compile a comprehensive list of the most widely used freely available software and tools that are used primarily in metabolomics. The most widely used tools were selected for inclusion in the review by either ≥ 50 citations on Web of Science (as of 08/09/16) or the use of the tool being reported in the recent Metabolomics Society survey. Tools were then categorised by the type of instrumental data (i.e. LC-MS, GC-MS or NMR) and the functionality (i.e. pre- and post-processing, statistical analysis, workflow and other functions) they are designed for. A comprehensive list of the most used tools was compiled. Each tool is discussed within the context of its application domain and in relation to comparable tools of the same domain. An extended list including additional tools is available at https://github.com/RASpicer/MetabolomicsTools which is classified and searchable via a simple controlled vocabulary. This review presents the most widely used tools for metabolomics analysis, categorised based on their main functionality. As future work, we suggest a direct comparison of tools' abilities to perform specific data analysis tasks e.g. peak picking.

  20. Satellite Meteorology Education Resources Freely Available from COMET°

    Science.gov (United States)

    Abshire, W. E.; Dills, P. N.

    2011-12-01

    The COMET° Program (www.comet.ucar.edu) receives funding from NOAA NESDIS, EUMETSAT, and the Meteorological Service of Canada to support education and training efforts in satellite meteorology. These partnerships enable COMET to create educational materials of global interest on the application of products from geostationary and polar-orbiting remote sensing platforms. Recently, COMET's satellite education programs have focused on both current and next generation satellites and their relevance to operational forecasters and other communities. By partnering with experts from the Naval Research Laboratory, NOAA-NESDIS and its Cooperative Institutes, MSC, and other user communities, COMET stimulates greater utilization of satellite data and products. COMET also continues to broaden the scope of its training to include materials on the EUMETSAT Polar-orbiting System (EPS) and Meteosat geostationary satellites. EPS represents an important contribution to the Initial Joint Polar System between NOAA and EUMETSAT, while Meteosat Second Generation imaging capabilities provide an authentic proving ground for the next-generation GOES-R imager. This presentation provides an overview of COMET's recent satellite education efforts including courses and publications that focus on topics like multispectral RGB products, detecting atmospheric dust, and climate monitoring from satellites. Over 50 satellite-focused self-paced online materials are freely available via the Satellite Topic area of the MetEd Web site (www.meted.ucar.edu/topics/modules/satellite) and COMET's Environmental Satellite Resource Center (ESRC)(www.meted.ucar.edu/esrc). The ESRC, another important resource developed for use by the geosciences and education communities, is a searchable, database driven Web site that provides easy access to a wide range of useful information and training materials on Earth-observing satellites. Simple free online registration is required to access all training materials and the

  1. Study on ecological migration in Xinjiang, China

    Institute of Scientific and Technical Information of China (English)

    Abliz Yusup; Osman Niyaz

    2006-01-01

    This paper expounds on the meaning of migration and the status quo of studies at home and abroad on migration and ecological migration. It focuses on the discussion of the necessity of ecological migration in Xinjiang, and the problems faced by the ecological emigrants, such as the lack of water, the serious land salination and basification,sand storms, and the adaptation to the environment. Besides, it probes into the problems existing in the ecological migration, including the unscientific design of the moving project, the defects of the reclamation work, and the irrational treatment of the relation between ecological migration and regional development. Based on this, we put forward some suggestions about and countermeasures against those problems.

  2. Mechanical properties of freely suspended semiconducting graphene-like layers based on MoS2

    NARCIS (Netherlands)

    Castellanos-Gomez, A.; Poot, M.; Steele, G.A.; Van der Zant, H.S.J.; Agrait, N.; Rubio-Bollinger, G.

    2012-01-01

    We fabricate freely suspended nanosheets of molybdenum disulphide (MoS2) which are characterized by quantitative optical microscopy and high-resolution friction force microscopy. We study the elastic deformation of freely suspended nanosheets of MoS2 using an atomic force microscope. The Young’s mod

  3. 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...

  4. 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...

  5. Bosnia: Migrations

    Directory of Open Access Journals (Sweden)

    Stjepan Pavičić

    2000-12-01

    Full Text Available The paper is a reprint of a very informative review of migrations in Bosnia published almost 60 years ago. The author first notes that the [Slavic] population that first settled Bosnia spoke variants of the ikavian-ţakavian dialect spoken also in neighbouring parts of Croatia (although the interrogative ča itself was not common. From the 13th century the jekavian-štokavian dialect expanded from the Southeast, from areas in modern Montenegro. This change was greatly due to immigration of Vlachs, who had adopted jekavian-štokavian. Although earlier Vlach immigrants had adopted the indigenous ikavian idiom, as well as associating themselves with Catholicism or with the Patarene Bosnian Church, later arrivals spoke jekavian-štokavian and adhered to Eastern Orthodoxy. In the 14th century the former group, living on both sides of the Neretva valley and in the Dinaric range, expanded to areas of Croatia, whereas the Eastern Vlachs had already established themselves on the left bank of the Drina river. By 1450 all Vlachs in Bosnia spoke jekavian-štokavian. In the 15–16th centuries the Ottomans favoured the settlement of Vlachs in Bosnia. The Vlachs served in Ottoman military structures, provided transportation services and were useful in the integration of conquered western and northwestern lands. In general, the establishment of Ottoman rule in Bosnia induced major changes in the population and in migration flows. The author divides this history into three periods. The first lasted from the initial Ottoman conquests to the wars of 1683–1699. At its start in the 15th century almost all Patarenes adopted Islam, especially in areas where the Bosnian Church was strong, but also in areas where Catholicism dominated, where some Catholics embraced Islam. Conversions of Catholics to Islam intensified in the 16th century and throughout the 17th, to a different degree in various regions: a in Central Bosnia conversion was almost total, b along the Sava

  6. Electron Paramagnetic Resonance Study of Defects in γ-irradiated Marine Mussel (Mytilus galloprovincialis) and Scallop (Pecten jacobaeus) Shells

    Science.gov (United States)

    Köseoğlu, R.; Köksal, F.; Birey, M.

    2004-11-01

    EPR studies have been performed on some gamma-irradiated marine mussels (Mytilus galloprovincialis) and scallops (Pecten jacobaeus) from the families of Mytilidae and Pectinidae, respectively. Before γ-irradiation, the EPR lines of Mytilus galloprovincialis indicated the existence of Mn2+ ions, which were not observed in the powders of scallop shells. γ -irradiation induced defects in powders of Mytilus galloprovincialis shells, were attributed to orthorhombic CO-3 , axial CO3-3 , orthorhombic CO-2 , freely rotating CO-2 , freely rotating SO-2 , axial SO-3 , isotropic PO2-4 and organic free radicals. γ -irradiation induced defects in powders of Pecten jacobaeus shells were attributed to orthorhombic CO-3 , axial CO3-3 , orthorhombic CO-2 , freely rotating CO-2 , freely rotating SO-2 , and axial SO-3 free radicals. The EPR parameters of the free radicals were compared with literature data on similar defects

  7. On a universal relation for defect data in solids

    Energy Technology Data Exchange (ETDEWEB)

    Skordas, E.S., E-mail: eskordas@phys.uoa.g [Department of Solid State Physics, Faculty of Physics, University of Athens, Panepistimiopolis, 157 84 Zografos (Greece)

    2010-10-15

    We show that the defect data parameters related to various defect processes, e.g., formation, migration, dielectric relaxation parameters, obey a universal law. In particular, the defect entropies scale with the defect enthalpies irrespective of the process considered. A concrete example is given here for SrF{sub 2} by considering the dielectric relaxation parameters (R{sub 1} relaxation mechanism) for crystals doped with trivalent ions of Ce, Eu, and Gd, parameters for the anion-Frenkel formation as well as for the migration of anion vacancy and the anion interstitial motion.

  8. Atomistic stimulation of defective oxides

    CERN Document Server

    Minervini, L

    2000-01-01

    defect processes. The predominant intrinsic disorder reaction and the mechanism by which excess oxygen is accommodated are established. Furthermore, the most favourable migration mechanism and pathway for oxygen ions is predicted. Chapters 7 and 8 investigate pyrochlore oxides. These materials are candidates for solid oxide fuel cell components and as actinide host phases. Such applications require a detailed understanding of the defect processes. The defect energies, displayed as contour maps, are able to account for structure stability and, given an appropriate partial charge potential model, to accurately determine the oxygen positional parameter. In particular, the dependence of the positional parameter on intrinsic disorder is predicted. It is demonstrated, by radiation damage experiments, that these results are able to predict the radiation performance of pyrochlore oxides. Atomistic simulation calculations based on energy minimization techniques and classical pair potentials are used to study several i...

  9. Passive sampling methods for contaminated sediments: Scientific rationale supporting use of freely dissolved concentrations

    DEFF Research Database (Denmark)

    Mayer, Philipp; Parkerton, Thomas F.; Adams, Rachel G.

    2014-01-01

    Passive sampling methods (PSMs) allow the quantification of the freely dissolved concentration (Cfree ) of an organic contaminant even in complex matrices such as sediments. Cfree is directly related to a contaminant's chemical activity, which drives spontaneous processes including diffusive uptake...

  10. Long-term synchronized electrophysiological and behavioral wireless monitoring of freely moving animals

    Science.gov (United States)

    Grand, Laszlo; Ftomov, Sergiu; Timofeev, Igor

    2012-01-01

    Parallel electrophysiological recording and behavioral monitoring of freely moving animals is essential for a better understanding of the neural mechanisms underlying behavior. In this paper we describe a novel wireless recording technique, which is capable of synchronously recording in vivo multichannel electrophysiological (LFP, MUA, EOG, EMG) and activity data (accelerometer, video) from freely moving cats. The method is based on the integration of commercially available components into a simple monitoring system and is complete with accelerometers and the needed signal processing tools. LFP activities of freely moving group-housed cats were recorded from multiple intracortical areas and from the hippocampus. EMG, EOG, accelerometer and video were simultaneously acquired with LFP activities 24-h a day for 3 months. These recordings confirm the possibility of using our wireless method for 24-h long-term monitoring of neurophysiological and behavioral data of freely moving experimental animals such as cats, ferrets, rabbits and other large animals. PMID:23099345

  11. On the symmetrization of rotational spectra for freely rotating linear molecules

    Science.gov (United States)

    Borysow, Aleksandra; Moraldi, Massimo

    It is demonstrated that the symmetrization of a quantum mechanical rotational spectrum of freely rotating linear molecules by means of the Egelstaff transformation produces a symmetric spectrum whose first two even moments coincide with the corresponding classical moments.

  12. EU Migration Policy

    OpenAIRE

    Kleinschmidt, Harald

    2004-01-01

    I shall confine myself in this paper to international migration as migration across international borders.I do so despite the fact that,still today,international migration accounts only for a small share of migration at large.Likewise,I shall deal widh voluntary migration and shall thus exclude,deportation ...

  13. 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...

  14. Research on Protocol Migration

    Institute of Scientific and Technical Information of China (English)

    汪芸; 顾冠群; 等

    1996-01-01

    This paper elaborates the concept and model of protocol migration in network interconnection.Migration strategies and principles are discussed and several cases are studied in detail which show the basic procedure and techniques used in protocol migration.

  15. Internationalization and migration pressure.

    Science.gov (United States)

    Kultalahti, O

    1994-01-01

    The author first develops the concept of migration pressure, which is defined as the growth in the number of people wishing to migrate and the barriers preventing them from so doing. Both macro- and micro-level factors affecting migration pressure are identified. Historical trends in migration pressure in Finland are then discussed. The author then applies this concept to the analysis of current Finnish migration trends. The primary focus is on international migration.

  16. SHARPIN Regulates Uropod Detachment in Migrating Lymphocytes

    Directory of Open Access Journals (Sweden)

    Jeroen Pouwels

    2013-11-01

    Full Text Available SHARPIN-deficient mice display a multiorgan chronic inflammatory phenotype suggestive of altered leukocyte migration. We therefore studied the role of SHARPIN in lymphocyte adhesion, polarization, and migration. We found that SHARPIN localizes to the trailing edges (uropods of both mouse and human chemokine-activated lymphocytes migrating on intercellular adhesion molecule-1 (ICAM-1, which is one of the major endothelial ligands for migrating leukocytes. SHARPIN-deficient cells adhere better to ICAM-1 and show highly elongated tails when migrating. The increased tail lifetime in SHARPIN-deficient lymphocytes decreases the migration velocity. The adhesion, migration, and uropod defects in SHARPIN-deficient lymphocytes were rescued by reintroducing SHARPIN into the cells. Mechanistically, we show that SHARPIN interacts directly with lymphocyte-function-associated antigen-1 (LFA-1, a leukocyte counterreceptor for ICAM-1, and inhibits the expression of intermediate and high-affinity forms of LFA-1. Thus, SHARPIN controls lymphocyte migration by endogenously maintaining LFA-1 inactive to allow adjustable detachment of the uropods in polarized cells.

  17. Point defect engineering strategies to retard phosphorous diffusion in germanium

    KAUST Repository

    Tahini, H. A.

    2013-01-01

    The diffusion of phosphorous in germanium is very fast, requiring point defect engineering strategies to retard it in support of technological application. Density functional theory corroborated with hybrid density functional calculations are used to investigate the influence of the isovalent codopants tin and hafnium in the migration of phosphorous via the vacancy-mediated diffusion process. The migration energy barriers for phosphorous are increased significantly in the presence of oversized isovalent codopants. Therefore, it is proposed that tin and in particular hafnium codoping are efficient point defect engineering strategies to retard phosphorous migration. © the Owner Societies 2013.

  18. Identification of transforming hepatitis B virus S gene nonsense mutations derived from freely replicative viruses in hepatocellular carcinoma.

    Directory of Open Access Journals (Sweden)

    Shiu-Feng Huang

    Full Text Available BACKGROUND & AIMS: The correlation between chronic hepatitis B virus (HBV infection and hepatocellular carcinoma (HCC has been well-established. But the roles of viral factor remain uncertain. Only HBV X gene and nonsense mutations of S gene (C-terminal truncation of HBV surface protein have been demonstrated to have transforming activity. Whether they play a significant role in hepatocarcinogenesis is still uncertain. METHODS: Twenty-five HBV-related HCC patients were positive for hepatitis B core antigen (HBcAg in the cancerous parts of their HCC liver tissues by immunohistochemistry studies, and had available tissue for whole HBV genome sequence analysis. The results were compared with 25 gender and age-matched HBcAg negative HCCs. Plasmids encoding HBV S gene nonsense mutations identified from HBcAg (+ HCC tissue were constructed to investigate their cell proliferation, transformation activity and the oncogenic potentials by xenograft study and in vivo migration assay. RESULTS: HBcAg (+ HCC patients were significantly associated with cirrhosis and small tumor size (≦2 cm when compared with HBcAg (- HCC patients. Southern blot analyses revealed freely replicative forms of HBV in the cancerous parts of HBcAg(+ HCC. Three nonsense mutations of S gene (sL95*, sW182*, and sL216* were identified in the HBcAg(+ HCC tumor tissues. sW182* and sL216* were recurrently found in the 25 HBcAg (- HCC tumor tissue, too. Functional studies of the above 3 non-sense mutations all demonstrated higher cell proliferation activities and transformation abilities than wild type S, especially sW182*. Tumorigenicity analysis by xenograft experiments and in vitro migration assay showed potent oncogenic activity of sW182* mutant. CONCLUSIONS: This study has demonstrated potent oncogenic activity of nonsense mutations of HBV S gene, suggesting they may play an important role in hepatocarcinogenesis.

  19. Governing Global Migration

    OpenAIRE

    2008-01-01

    This study explores the global regulative function of migration politics. Its main aim is to rethink migration politics through an engagement with the Foucauldian governmentality perspective, which focuses on the relation between government and thought. A secondary aim is to use this perspective to explore the global description of migration and migration politics which is emerging with the currently evolving global governance of migration. Doing so, it wishes to contribute both to the study ...

  20. Fertility, Migration, and Altruism

    OpenAIRE

    2000-01-01

    Consider migration to a higher income region as a human capital investment in which parents bear migration costs and children share returns. Migrants from a population with heterogeneous intergenerational discount rates will be self-selected on intergenerational altruism. Thus, immigrants may be self-selected on fertility. Soviet Jews who migrate to Israel despite high migration costs have significantly more children than members of the same birth cohort who migrate later when costs are low. ...

  1. Use of Freely-Available Weebly in Creating Quick and Easy Web Pages: poster presentation

    OpenAIRE

    Hyde, Denise

    2011-01-01

    Weebly is a freely-available software for creating Web pages without having to know HTML. It is easy to use, with its drag and drop editor, and offers the ability to add documents, Web links, videos, slideshows, audio, forms, polls, etc. It is hosted by Weebly and has no limits on storage space. Many templates are available for Web page design. One can publish and update almost immediately. Combined with usage of the freely-available Google Analytics, for example, it is possible to gathe...

  2. The multiple faces of leukocyte interstitial migration

    Science.gov (United States)

    Lämmermann, Tim; Germain, Ronald N.

    2014-01-01

    Spatiotemporal control of leukocyte dynamics within tissues is critical for successful innate and adaptive immune responses. Homeostatic trafficking and coordinated infiltration into and within sites of inflammation and infection rely on signaling in response to extracellular cues that in turn controls a variety of intracellular protein networks regulating leukocyte motility, migration, chemotaxis, positioning, and cell–cell interaction. In contrast to mesenchymal cells, leukocytes migrate in an amoeboid fashion by rapid cycles of actin polymerization and actomyosin contraction, and their migration in tissues is generally referred to as low adhesive and nonproteolytic. The interplay of actin network expansion, contraction, and adhesion shapes the exact mode of amoeboid migration, and in this review, we explore how leukocyte subsets potentially harness the same basic biomechanical mechanisms in a cell-type-specific manner. Most of our detailed understanding of these processes derives from in vitro migration studies in three-dimensional gels and confined spaces that mimic geometrical aspects of physiological tissues. We summarize these in vitro results and then critically compare them to data from intravital imaging of leukocyte interstitial migration in mouse tissues. We outline the technical challenges of obtaining conclusive mechanistic results from intravital studies, discuss leukocyte migration strategies in vivo, and present examples of mode switching during physiological interstitial migration. These findings are also placed in the context of leukocyte migration defects in primary immunodeficiencies. This overview of both in vitro and in vivo studies highlights recent progress in understanding the molecular and biophysical mechanisms that shape robust leukocyte migration responses in physiologically complex and heterogeneous environments. PMID:24573488

  3. Ventricular septal defect (image)

    Science.gov (United States)

    Ventricular septal defect is a congenital defect of the heart, that occurs as an abnormal opening in ... wall that separates the right and left ventricles. Ventricular septal defect may also be associated with other ...

  4. Facts about Birth Defects

    Science.gov (United States)

    ... Button Information For… Media Policy Makers Facts about Birth Defects Language: English (US) Español (Spanish) Recommend ... having a baby born without a birth defect. Birth Defects Are Common Every 4 ½ minutes, a ...

  5. Neural Tube Defects

    Science.gov (United States)

    Neural tube defects are birth defects of the brain, spine, or spinal cord. They happen in the ... that she is pregnant. The two most common neural tube defects are spina bifida and anencephaly. In ...

  6. Theory of hydrogen migration in organic-inorganic halide perovskites.

    Science.gov (United States)

    Egger, David A; Kronik, Leeor; Rappe, Andrew M

    2015-10-12

    Solar cells based on organic-inorganic halide perovskites have recently been proven to be remarkably efficient. However, they exhibit hysteresis in their current-voltage curves, and their stability in the presence of water is problematic. Both issues are possibly related to a diffusion of defects in the perovskite material. By using first-principles calculations based on density functional theory, we study the properties of an important defect in hybrid perovskites-interstitial hydrogen. We show that differently charged defects occupy different crystal sites, which may allow for ionization-enhanced defect migration following the Bourgoin-Corbett mechanism. Our analysis highlights the structural flexibility of organic-inorganic perovskites: successive iodide displacements, combined with hydrogen bonding, enable proton diffusion with low migration barriers. These findings indicate that hydrogen defects can be mobile and thus highly relevant for the performance of perovskite solar cells.

  7. Hippocampal activity during transient respiratory events in the freely behaving cat

    DEFF Research Database (Denmark)

    Poe, G R; Kristensen, Morten Pilgaard; Rector, D M;

    1996-01-01

    We measured dorsal hippocampal activity accompanying sighs and apnea using reflectance imaging and electrophysiologic measures in freely behaving cats. Reflected 660-nm light from a 1-mm2 area of CA1 was captured during sighs and apnea at 25 Hz through a coherent image conduit coupled to a charge...

  8. "Just Google It"--The Scope of Freely Available Information Sources for Doctoral Thesis Writing

    Science.gov (United States)

    Grigas, Vincas; Juzeniene, Simona; Velickaite, Jone

    2017-01-01

    Introduction: Recent developments in the field of scientific information resource provision lead us to the key research question, namely,what is the coverage of freely available information sources when writing doctoral theses, and whether the academic library can assume the leading role as a direct intermediator for information users. Method:…

  9. 34 CFR 300.701 - Outlying areas, freely associated States, and the Secretary of the Interior.

    Science.gov (United States)

    2010-07-01

    ... States—(1) Funds reserved. From the amount appropriated for any fiscal year under section 611(i) of the... State received for fiscal year 2003 under Part B of the Act, but only if the freely associated State— (A... Public Law 95-134, permitting the consolidation of grants by the outlying areas, do not apply to...

  10. A rapid and simple cannulation technique for repeated sampling of cerebrospinal fluid in freely moving rats

    NARCIS (Netherlands)

    Bouman, H.J.; Wimersma Greidanus, T.B. van

    1979-01-01

    A cannulation technique for frequent sampling of cerebrospinal fluid (CSF) in unanaesthetized freely moving rats is described. A permanent stainless steel cannula, constructed in such a way that no loss of CSF occurs, is placed into the rat's cisterna magna and fixed to the skull by anchoring screws

  11. Emotions in freely varying and mono-pitched vowels, acoustic and EGG analyses.

    Science.gov (United States)

    Waaramaa, Teija; Palo, Pertti; Kankare, Elina

    2015-12-01

    Vocal emotions are expressed either by speech or singing. The difference is that in singing the pitch is predetermined while in speech it may vary freely. It was of interest to study whether there were voice quality differences between freely varying and mono-pitched vowels expressed by professional actors. Given their profession, actors have to be able to express emotions both by speech and singing. Electroglottogram and acoustic analyses of emotional utterances embedded in expressions of freely varying vowels [a:], [i:], [u:] (96 samples) and mono-pitched protracted vowels (96 samples) were studied. Contact quotient (CQEGG) was calculated using 35%, 55%, and 80% threshold levels. Three different threshold levels were used in order to evaluate their effects on emotions. Genders were studied separately. The results suggested significant gender differences for CQEGG 80% threshold level. SPL, CQEGG, and F4 were used to convey emotions, but to a lesser degree, when F0 was predetermined. Moreover, females showed fewer significant variations than males. Both genders used more hypofunctional phonation type in mono-pitched utterances than in the expressions with freely varying pitch. The present material warrants further study of the interplay between CQEGG threshold levels and formant frequencies, and listening tests to investigate the perceptual value of the mono-pitched vowels in the communication of emotions.

  12. Concentration of frequencies of trapped waves in problems on freely floating bodies

    Science.gov (United States)

    Nazarov, Sergei A.

    2012-09-01

    It is shown that by choosing the shape of two identical bodies floating freely in a channel with symmetric cross-section it is possible to form any pre-assigned number of linearly independent trapped waves (localized solutions). Bibliography: 27 titles.

  13. Return migration to Italy and labour migration.

    Science.gov (United States)

    Calvaruso, C

    1983-01-01

    The problems caused by large-scale return migration to Italy in recent years are considered. The importance of the additional skills and capital acquired by these migrants while abroad is stressed. Extensive data on the volume of return migration in the 1970s are included.

  14. 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...

  15. Population, migration and urbanization.

    Science.gov (United States)

    1982-06-01

    Despite recent estimates that natural increase is becoming a more important component of urban growth than rural urban transfer (excess of inmigrants over outmigrants), the share of migration in the total population growth has been consistently increasing in both developed and developing countries. From a demographic perspective, the migration process involves 3 elements: an area of origin which the mover leaves and where he or she is considered an outmigrant; the destination or place of inmigration; and the period over which migration is measured. The 2 basic types of migration are internal and international. Internal migration consists of rural to urban migration, urban to urban migration, rural to rural migration, and urban to rural migration. Among these 4 types of migration various patterns or processes are followed. Migration may be direct when the migrant moves directly from the village to the city and stays there permanently. It can be circular migration, meaning that the migrant moves to the city when it is not planting season and returns to the village when he is needed on the farm. In stage migration the migrant makes a series of moves, each to a city closer to the largest or fastest growing city. Temporary migration may be 1 time or cyclical. The most dominant pattern of internal migration is rural urban. The contribution of migration to urbanization is evident. For example, the rapid urbanization and increase in urban growth from 1960-70 in the Republic of Korea can be attributed to net migration. In Asia the largest component of the population movement consists of individuals and groups moving from 1 rural location to another. Recently, because urban centers could no longer absorb the growing number of migrants from other places, there has been increased interest in the urban to rural population redistribution. This reverse migration also has come about due to slower rates of employment growth in the urban centers and improved economic opportunities

  16. Migration and Adult Education

    Science.gov (United States)

    Gois, William

    2007-01-01

    The objective of this paper is to highlight the role of adult education as a tool in addressing labour migration issues, specifically those concerning the protection of migrant workers' rights and the transformation of the impact of migration into positive holistic developmental gains. The view of labour migration as a means to forge the economic…

  17. 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…

  18. Migration and Literature

    DEFF Research Database (Denmark)

    Frank, Søren

    We live in an age of migration and more and more authors have migrant backgrounds. Migration and Literature offers a thorough and thought provoking examination of the thematic and formal role of migration in four contemporary and canonized novelists, Günter Grass, Milan Kundera, Salman Rushdie...

  19. An investigation of the challenges in reconstructing PET images of a freely moving animal.

    Science.gov (United States)

    Akhtar, Mahmood; Kyme, Andre; Zhou, Victor; Fulton, Roger; Meikle, Steven

    2013-12-01

    Imaging the brain of a freely moving small animal using positron emission tomography (PET) while simultaneously observing its behaviour is an important goal for neuroscience. While we have successfully demonstrated the use of line-of-response (LOR) rebinning to correct the head motion of confined animals, a large proportion of events may need to be discarded because they either 'miss' the detector array after transformation or fall out of the acceptance range of a sinogram. The proportion of events that would have been measured had motion not occurred, so-called 'lost events', is expected to be even larger for freely moving animals. Moreover, the data acquisition in the case of a freely moving animal is further complicated by a complex attenuation field. The aims of this study were (a) to characterise the severity of the 'lostevents' problem for the freely moving animal scenario, and(b) to investigate the relative impact of attenuation correction errors on quantitative accuracy of reconstructed images. A phantom study was performed to simulate the uncorrelated motion of a target and non-target sourcevolume. A small animal PET scanner was used to acquirelist-mode data for different sets of phantom positions. The list-mode data were processed using the standard LOR rebinning approach, and multiple frame variants of this designed to reduce discarded events. We found that LOR rebinning caused up to 86 % 'lost events', and artifacts that we attribute to incomplete projections, when applied to a freely moving target. This fraction was reduced by up to 18 % using the variant approaches, resulting in slightly reduced image artifacts. The effect of the non-target compartment on attenuation correction of the target volume was surprisingly small. However, for certain poses where the target and non-target volumes are aligned transaxially in the field-of-view, the attenuation problem becomes more complex and sophisticated correction methods will be required. We conclude that

  20. Salmon DNA Accelerates Bone Regeneration by Inducing Osteoblast Migration

    Science.gov (United States)

    Sato, Ayako; Kajiya, Hiroshi; Mori, Nana; Sato, Hironobu; Fukushima, Tadao; Kido, Hirofumi

    2017-01-01

    The initial step of bone regeneration requires the migration of osteogenic cells to defective sites. Our previous studies suggest that a salmon DNA-based scaffold can promote the bone regeneration of calvarial defects in rats. We speculate that the salmon DNA may possess osteoinductive properties, including the homing of migrating osteogenic cells. In the present study, we investigated the influence of the salmon DNA on osteoblastic differentiation and induction of osteoblast migration using MG63 cells (human preosteoblasts) in vitro. Moreover, we analyzed the bone regeneration of a critical-sized in vivo calvarial bone defect (CSD) model in rats. The salmon DNA enhanced both mRNA and protein expression of the osteogenesis-related factors, runt-related transcription factor 2 (Runx2), alkaline phosphatase, and osterix (OSX) in the MG63 cells, compared with the cultivation using osteogenic induction medium alone. From the histochemical and immunohistochemical assays using frozen sections of the bone defects from animals that were implanted with DNA disks, many cells were found to express aldehyde dehydrogenase 1, one of the markers for mesenchymal stem cells. In addition, OSX was observed in the replaced connective tissue of the bone defects. These findings indicate that the DNA induced the migration and accumulation of osteogenic cells to the regenerative tissue. Furthermore, an in vitro transwell migration assay showed that the addition of DNA enhanced an induction of osteoblast migration, compared with the medium alone. The implantation of the DNA disks promoted bone regeneration in the CSD of rats, compared with that of collagen disks. These results indicate that the salmon DNA enhanced osteoblastic differentiation and induction of migration, resulting in the facilitation of bone regeneration. PMID:28060874

  1. Nanoscopic Terraces, Mesas, and Ridges in Freely Standing Thin Films Sculpted by Supramolecular Oscillatory Surface Forces.

    Science.gov (United States)

    Zhang, Yiran; Yilixiati, Subinuer; Pearsall, Collin; Sharma, Vivek

    2016-04-26

    Freely standing thin liquid films containing supramolecular structures including micelles, nanoparticles, polyelectrolyte-surfactant complexes, and smectic liquid crystals undergo drainage via stratification. The layer-by-layer removal of these supramolecular structures manifests as stepwise thinning over time and a coexistence of domains and nanostructures of discretely different thickness. The layering of supramolecular structures in confined thin films contributes additional non-DLVO, supramolecular oscillatory surface forces to disjoining pressure, thus influencing both drainage kinetics and stability of thin films. Understanding and characterizing the spontaneous creation and evolution of nanoscopic topography of stratifying, freely standing thin liquid films have been long-standing challenges due to the absence of experimental techniques with the requisite spatial (thickness thin films and, more generally, of colloidal dispersions like foams.

  2. Between soap bubbles and vesicles: The dynamics of freely floating smectic bubbles

    Science.gov (United States)

    Stannarius, Ralf; May, Kathrin; Harth, Kirsten; Trittel, Torsten

    2013-03-01

    The dynamics of droplets and bubbles, particularly on microscopic scales, are of considerable importance in biological, environmental, and technical contexts. We introduce freely floating bubbles of smectic liquid crystals and report their unique dynamic properties. Smectic bubbles can be used as simple models for dynamic studies of fluid membranes. In equilibrium, they form minimal surfaces like soap films. However, shape transformations of closed smectic membranes that change the surface area involve the formation and motion of molecular layer dislocations. These processes are slow compared to the capillary wave dynamics, therefore the effective surface tension is zero like in vesicles. Freely floating smectic bubbles are prepared from collapsing catenoid films and their dynamics is studied with optical high-speed imaging. Experiments are performed under normal gravity and in microgravity during parabolic flights. Supported by DLR within grant OASIS-Co.

  3. Navier-Stokes hydrodynamics of thermal collapse in a freely cooling granular gas.

    Science.gov (United States)

    Kolvin, Itamar; Livne, Eli; Meerson, Baruch

    2010-08-01

    We show that, in dimension higher than one, heat diffusion and viscosity cannot arrest thermal collapse in a freely evolving dilute granular gas, even in the absence of gravity. Thermal collapse involves a finite-time blowup of the gas density. It was predicted earlier in ideal, Euler hydrodynamics of dilute granular gases in the absence of gravity, and in nonideal, Navier-Stokes granular hydrodynamics in the presence of gravity. We determine, analytically and numerically, the dynamic scaling laws that characterize the gas flow close to collapse. We also investigate bifurcations of a freely evolving dilute granular gas in circular and wedge-shaped containers. Our results imply that, in general, thermal collapse can only be arrested when the gas density becomes comparable with the close-packing density of grains. This provides a natural explanation to the formation of densely packed clusters of particles in a variety of initially dilute granular flows.

  4. Region-Based Fractal Image Coding with Freely-Shaped Partition

    Institute of Scientific and Technical Information of China (English)

    SUNYunda; ZHAOYao; YUANBaozong

    2004-01-01

    In Fractal image coding (FIC), a partitioning of the original image into ranges and domains is required, which greatly affects the coding performance. Usually, the more adaptive to the image content the partition is, the higher performance it can achieve. Nowadays, some alleged Region-based fractal coders (RBFC) using split-and-merge strategy can achieve better adaptivity andperformance compared with traditional rectangular block partitions. However, the regions are still with linear contour. In this paper, we present a Freely-shaped Regionbased fractal coder (FS-RBFC) using a two-step partitioning, i.e. coarse partitioning based on fractal dimension and fine partitioning based on region growth, which brings freely-shaped regions. Our highly image-adaptive scheme can achieve better rate-distortion curve than conventional scheme, even more visually pleasing results at the same performance.

  5. Freely Evolving Process and Statistics in the Two-Dimensional Granular Turbulence

    Science.gov (United States)

    Isobe, Masaharu

    2002-08-01

    We studied the macroscopic statistical properties on the freely evolving quasi-inelastic hard disk (granular) system by performing large-scale (more than a million particles) event-driven molecular dynamics systematically and found that remarkably analogous to an enstrophy cascade process in decaying two-dimensional fluid turbulence. There are four typcial stages in the freely evolving inelastic hard disk system, which are homogeneous, shearing (vortex), clustering and final state. In the shearing stage, the self-organized macroscopic coherent vortices become dominant and the enstrophy decays power-low behavior. In the clustering stage, the energy spectra are close to the expectation of Kraichnan-Batchelor theory and the squared two particle separation strictly obeys Richardson law. These results indicate that the cooperative behavior of quasi-inelastic hard disks system has a same universal class as the macroscopic Navier-Stokes fluid turbulence in the study of dissipative structure.

  6. Membership Problem in groups acting freely on Z^n-trees

    CERN Document Server

    Nikolaev, Andrey

    2011-01-01

    Groups acting freely on Z^n-trees (Z^n-free groups) play a key role in the study of non-archimedean group actions. Following Stallings' ideas, we develop graph-theoretic techniques to investigate subgroup structure of Z^n-free groups. As an immediate application of the presented method, we give an effective solution to the Uniform Membership Problem and the Power Problem in Z^n-free groups.

  7. Freely available online information sources and their impact on libraries and information centres

    OpenAIRE

    Ghosh, T. B.

    2002-01-01

    Since past few years free online information sources like e-journals, e-books, e-data- bases have increased cnsiderably. The traditional library systems are going to transform into digital library systems and different projects like Gutenberg e-book project, Virginia Tech. Digital Library Project, University of California Digital Library project etc. have been undertaken. The author has started to compile the links of such freely available online information sources on the Internet at URL: ht...

  8. Freely generated vertex algebras and non-linear Lie conformal algebras

    OpenAIRE

    De Sole, Alberto; Kac, Victor

    2003-01-01

    We introduce the notion of a non--linear Lie conformal superalgebra and prove a PBW theorem for its universal enveloping vertex algebra. We also show that conversely any graded freely generated vertex algebra is the universal enveloping algebra of a non--linear Lie conformal superalgebra. This correspondence will be applied in the subsequent work to the problem of classification of finitely generated simple graded vertex algebras.

  9. Preoperative diagnosis and radiographic findings of a freely movable mucocele of the vermiform appendix

    Energy Technology Data Exchange (ETDEWEB)

    Shukunami, K.-I.; Kaneshima, M.; Kotsuji, F. [Fukui Medical Univ., Dept. of Obstetrics and Gynecology, Matsuoka-Cho, Yoshida-Gun, Fukui (Japan)

    2000-10-01

    Mucocele of the vermiform appendix is rarely diagnosed before surgery, although radiologic and ultrasonographic (US) findings have been reported. To our knowledge, there have been no previous reports of 2 different radiologic images of the cyst in the same patient during the preoperative period. We present 2 different shapes and locations of a freely movable mucocele of the appendix as it appeared before surgery. (author)

  10. Passive sampling methods for contaminated sediments: Scientific rationale supporting use of freely dissolved concentrations

    DEFF Research Database (Denmark)

    Mayer, Philipp; Parkerton, Thomas F.; Adams, Rachel G.

    2014-01-01

    Passive sampling methods (PSMs) allow the quantification of the freely dissolved concentration (Cfree ) of an organic contaminant even in complex matrices such as sediments. Cfree is directly related to a contaminant's chemical activity, which drives spontaneous processes including diffusive uptake...... point using passive samplers with different surface to volume ratios. Sampling in the kinetic regime is also possible and generally involves the application of performance reference compounds for the calibration. Based on previous research on hydrophobic organic contaminants, it is concluded that Cfree...

  11. A novel synthetic route to freely adjust the crystal structures of Ni-P compounds

    Science.gov (United States)

    Xu, Hanghui; Lu, Shaoxiang; Ren, Lili

    2016-10-01

    Crystal-structure-controllable Ni-P compounds were synthesized using nickel chloride, nontoxic red phosphorus and polyethylene glycol. The hexagonal Ni2P and tetragonal Ni12P5 could be freely transformed via adjusting the amount of polyethylene glycol, and the mechanism of phase transformation was discussed. The catalytic performances of Ni-P compounds were promoted markedly with moderate quantity of PEG. However, excessive PEG will cover the active sites of catalysts and decrease the catalytic activity.

  12. MIGRATION ENTHALPY OF THERMAL VACANCIES BY POSITRON SPECTROSCOPY

    OpenAIRE

    2005-01-01

    The trapping of positrons at vacancy site in some materials provide a new and sensitive method for the equilibrium determination of point defect migration enthalpy. Data are presented for commercial Al–Mg alloys and fitted to a model allowing presentation in the form of Arrhenius plots, hence the migration enthalpy $H_{iv}^m$ can be determined by positron annihilation lifetime technique (PALT). The results show that as the concentration of Mg increases the value of $H_{iv}^m$ increases too.

  13. Migration Enthalpy of Thermal Vacancies by Positron Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    Emad A. Badawi

    2005-01-01

    @@ The trapping of positrons at vacancy site in some materials provide a new and sensitive method for the equilibrium determination of point defect migration enthalpy. Data are presented for commercial Al-Mg alloys and fitted to a model allowing presentation in the form of Arrhenius plots, hence the migration enthalpy H m iv can bedetermined by the positron annihilation lifetime technique. The results show that the value of Hm iv increases as the concentration of Mg increases.

  14. Fusion neutron irradiation induced ordering and defect production in Cu/sub 3/Au at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Huang, J.S.; Guinan, M.W.; Kirk, M.A.; Hahn, P.A.

    1987-08-01

    We irradiate three Cu/sub 3/Au alloys different degrees of initial long-range order at temperatures between 300K and 434K. The resistivity of samples is monitored during irradiation and related to the long-term order parameter by the Muto relation. The results show that the ordering rate, which is proportional to the concentration of freely migrating vacancies, increases at the beginning and then decreases later with fluence. The decrease is a result of the continuous production of sinks in the form of dislocation loops. The effect of sinks on vacancy annihilation in some cases causes a reversed temperature dependence of ordering rate. The free vacancy production rate and the rate of sink production are determined using an ordering kinetics theory. The results of the 14 MeV neutron irradiations are compared to those obtained in other neutron spectra and particle irradiations. The estimated free vacancy production rate is also compared to the primary defect production rate measured at 4.2K in disordered samples.

  15. Single-molecule force spectroscopy of membrane proteins from membranes freely spanning across nanoscopic pores.

    Science.gov (United States)

    Petrosyan, Rafayel; Bippes, Christian A; Walheim, Stefan; Harder, Daniel; Fotiadis, Dimitrios; Schimmel, Thomas; Alsteens, David; Müller, Daniel J

    2015-05-13

    Single-molecule force spectroscopy (SMFS) provides detailed insight into the mechanical (un)folding pathways and structural stability of membrane proteins. So far, SMFS could only be applied to membrane proteins embedded in native or synthetic membranes adsorbed to solid supports. This adsorption causes experimental limitations and raises the question to what extent the support influences the results obtained by SMFS. Therefore, we introduce here SMFS from native purple membrane freely spanning across nanopores. We show that correct analysis of the SMFS data requires extending the worm-like chain model, which describes the mechanical stretching of a polypeptide, by the cubic extension model, which describes the bending of a purple membrane exposed to mechanical stress. This new experimental and theoretical approach allows to characterize the stepwise (un)folding of the membrane protein bacteriorhodopsin and to assign the stability of single and grouped secondary structures. The (un)folding and stability of bacteriorhodopsin shows no significant difference between freely spanning and directly supported purple membranes. Importantly, the novel experimental SMFS setup opens an avenue to characterize any protein from freely spanning cellular or synthetic membranes.

  16. Seismic migration in generalized coordinates

    Science.gov (United States)

    Arias, C.; Duque, L. F.

    2017-06-01

    Reverse time migration (RTM) is a technique widely used nowadays to obtain images of the earth’s sub-surface, using artificially produced seismic waves. This technique has been developed for zones with flat surface and when applied to zones with rugged topography some corrections must be introduced in order to adapt it. This can produce defects in the final image called artifacts. We introduce a simple mathematical map that transforms a scenario with rugged topography into a flat one. The three steps of the RTM can be applied in a way similar to the conventional ones just by changing the Laplacian in the acoustic wave equation for a generalized one. We present a test of this technique using the Canadian foothills SEG velocity model.

  17. Investigation of scum type growing defects on attenuated PSM and its prevention

    Science.gov (United States)

    Choi, Jihwan; Kim, Yongho; Lee, Dongwook; Jung, Hoyong; Kim, Snagpyo; Yim, Donggyu

    2015-10-01

    The abnormal growing defect (we called this defect 'scum haze defect') in the photomask which is generated during the wafer lithography process is very important issue on semiconductor industry. Because wafer yield loss could be caused by the mask CD variation and the transmittance loss due to the growing defects on the photomask, many studies have been done about the mechanism and the solution of the general type growing defects such as haze and Cr migration so far, However we still need to clarify some abnormal types of the growing defects such as scum haze defect. In this paper, we investigated the generation mechanism and prevention techniques of the scum haze defect on the attenuated phase shift mask. This defect composed of CrOx is caused by the increase of the accumulated exposure energy on photomask. This phenomenon is remarkably similar to the Cr migration on binary mask. But, the apparent difference is that this scum type defect is observed on the attenuated phase shift mask which mainly consists of MoSiON film, and it is difficult to control this defect because of its irregular generation characteristic. Additionally, this defect is not generally removed through the conventional wet cleaning process but it only could be removed by a kind of plasma treatment. In this study, the difference of generation mechanism between the scum haze defect and the general haze was discussed, and the optimal process for controlling scum haze defect in the mask manufacturing was described.

  18. Congenital platelet function defects

    Science.gov (United States)

    ... storage pool disorder; Glanzmann's thrombasthenia; Bernard-Soulier syndrome; Platelet function defects - congenital ... Congenital platelet function defects are bleeding disorders that ... function, even though there are normal platelet numbers. Most ...

  19. Birth Defects: Cerebral Palsy

    Science.gov (United States)

    ... defects, premature birth and infant mortality. Solving premature birth Featured articles Accomplishments and lessons learned since the ... and pregnancy Folic acid Medicine safety and pregnancy Birth defects prevention Learn how to help reduce your ...

  20. Formation of vacancy-type defects in titanium nickelide

    Directory of Open Access Journals (Sweden)

    Baturin Anatolii

    2015-01-01

    Full Text Available In this report we briefly review the current state-of-the-art and challenges in determining point defect properties from first-principles calculations as well as from experimental measurements in titanium nickelid. . Based on the vacancy formation energy and their activation energy for vacancy migration in TiNi, vacancy mediated diffusion mechanism was examined. The behavior of vacancy defects in the TiNi structural phase transition has been described.

  1. Atrioventricular Canal Defect

    Science.gov (United States)

    ... doctor See your doctor if you or your child develops signs or symptoms of atrioventricular canal defect. Atrioventricular canal defect occurs before birth when a baby's heart is developing. Some factors, such as Down syndrome, might increase the risk of atrioventricular canal defect. ...

  2. Emergence of oligarchy in collective cell migration

    Science.gov (United States)

    Schumacher, Linus; Maini, Philip; Baker, Ruth

    Identifying the principles of collective cell migration has the potential to help prevent birth defects, improve regenerative therapies and develop model systems for cancer metastasis. In collaboration with experimental biologists, we use computational simulations of a hybrid model, comprising individual-based stochastic cell movement coupled to a reaction-diffusion equation for a chemoattractant, to explore the role of cell specialisation in the guidance of collective cell migration. In the neural crest, an important migratory cell population in vertebrate embryo development, we present evidence that just a few cells are guiding group migration in a cell-induced chemoattractant gradient that determines the switch between ``leader'' and ``follower'' behaviour in individual cells. This leads us to more generally consider under what conditions cell specialisation might become advantageous for collective migration. Alternatively, individual cell responses to locally different microenvironmental conditions could create the (artefactual) appearance of heterogeneity in a population of otherwise identical cellular agents. We explore these questions using a self-propelled particle model as a minimal description for collective cell migration in two and three dimensions.

  3. 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...

  4. Union Dissolution and Migration

    OpenAIRE

    Cooke, Thomas; Mulder, Clara H.; Thomas, Michael

    2016-01-01

    BACKGROUND While there is a limited body of research regarding residential mobility and migration following union dissolution, there is a particular dearth of studies that go into detail about the factors that shape how union dissolution may result in long-distance migration. OBJECTIVE This research isolates and identifies the processes that influence inter-state migration in the period immediately following the dissolution of a marital union. METHODS Multilevel logit models of the probabilit...

  5. Malaysia and forced migration

    OpenAIRE

    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. It considers forced migration as an event hosting multifaceted issues related and relevant to forced migrants and suggests that Malaysia has been preoccupied with the issue of forced migration movements. This is largely seen in various responses invoked from Malaysi...

  6. Socio-demographic aspects of globalization: Canadian perspectives on migration

    Directory of Open Access Journals (Sweden)

    Anthony H. Richmond

    2002-12-01

    Full Text Available Trends in Canadian immigration and emigration in the last decade are examined, distinguishing ‘temporary’ and ‘permanent’ movements, economic migrants and refugees. Comparisons are made with those of other OECD countries. Global migration patterns have changed as a result of post-industrial technologies. Although money, goods and services may move relatively freely, people do not. Processes of inclusion and exclusion occur within and between countries and regions. A typology of migrant incorporation is presented. Questions of human security and border controls are considered. Recommendations are made concerning the protection of migrant human rights.

  7. 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...

  8. 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...

  9. 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...

  10. Decoding of intentional actions from scalp electroencephalography (EEG) in freely-behaving infants.

    Science.gov (United States)

    Hernandez, Zachery R; Cruz-Garza, Jesus; Tse, Teresa; Contreras-Vidal, Jose L

    2014-01-01

    The mirror neuron system (MNS) in humans is thought to enable an individual's understanding of the meaning of actions performed by others and the potential imitation and learning of those actions. In humans, electroencephalographic (EEG) changes in sensorimotor a-band at central electrodes, which desynchronizes both during execution and observation of goal-directed actions (i.e., μ suppression), have been considered an analog to MNS function. However, methodological and developmental issues, as well as the nature of generalized μ suppression to imagined, observed, and performed actions, have yet to provide a mechanistic relationship between EEG μ-rhythm and MNS function, and the extent to which EEG can be used to infer intent during MNS tasks remains unknown. In this study we present a novel methodology using active EEG and inertial sensors to record brain activity and behavioral actions from freely-behaving infants during exploration, imitation, attentive rest, pointing, reaching and grasping, and interaction with an actor. We used 5-band (1-4Hz) EEG as input to a dimensionality reduction algorithm (locality-preserving Fisher's discriminant analysis, LFDA) followed by a neural classifier (Gaussian mixture models, GMMs) to decode the each MNS task performed by freely-behaving 6-24 month old infants during interaction with an adult actor. Here, we present results from a 20-month male infant to illustrate our approach and show the feasibility of EEG-based classification of freely occurring MNS behaviors displayed by an infant. These results, which provide an alternative to the μ-rhythm theory of MNS function, indicate the informative nature of EEG in relation to intentionality (goal) for MNS tasks which may support action-understanding and thus bear implications for advancing the understanding of MNS function.

  11. Comparing the Planform Morphologies of a Freely Meandering Channel and the Bedrock- Controlled South River, VA.

    Science.gov (United States)

    Narinesingh, P.; Pizzuto, J.

    2008-12-01

    The planforms of the lithologically controlled South River, VA, and the freely meandering Teklanika River, AK were investigated using two statistical methods as well as fractal and spectral analyses. The lithologic controls along the South River include riverbanks consisting of pre-Holocene terraces and alluvial fans, and highly resistant bedrock that frequently crops out both in the bed and along the banks. A statistical analysis of bends composed of single arcs shows that the average radius of curvature is six times greater and the average bend length is 25 percent smaller for the South River relative to the meandering river, indicating that lithologically controlled bends are less curved and shorter than freely-formed meander bends. Fractal analysis reveals that the meandering river displays a smaller range in length scales than the South River, which exhibits a wider range in length scales that reflect a wider distribution of bend sizes. The method of Lancaster and Bras, (2002), which identifies bends of different complexity, indicates that the meandering river displays bends composed of single arcs, complex arcs and multiple complex arcs. Unlike the freely meandering Teklanika River, the lithologically controlled South River does not display bends composed of multiple complex arcs, though bends composed of single and complex arcs are common. Spectral analysis reveals that the meandering river's pattern is composed of a relatively narrow range of dominant wavelengths with the most prominent wavelength being the longest, while the lithologically controlled river displays dominant wavelengths over a relatively wide range and the most prominent wavelength is not the longest. This analysis demonstrates that lithological controls increase the range of bend lengths, increase radii of curvature, simplify bend shapes, and increase the distribution of wavelengths of sinuous rivers.

  12. Freely accessible water does not decrease consumption of ethanol liquid diets.

    Science.gov (United States)

    de Fiebre, NancyEllen C; de Fiebre, Christopher M

    2003-02-01

    In experimental studies, liquid ethanol diets are usually given as the sole source of nutrition and fluid. Two series of experiments were conducted to examine the effect of freely accessible water on the consumption of ethanol liquid diets in male Long-Evans rats. The consumption of diets and subsequent learning ability of rats were first examined in animals given twice-daily saline injections. One group received diet with no access to water for 12 weeks and was subsequently given free access to water with diets for an additional 12 weeks. A second group was given diet and water ad libitum for 24 weeks. Control animals received an isocaloric sucrose-containing diet (with or without ad libitum access to water). Subsequently, rats were tested for active avoidance learning. In the first 12 weeks, animals with ad libitum access to water drank more diet than did water-restricted animals, and previously water-restricted animals increased their diet consumption when access to water was freely available. All water-restricted animals, in both ethanol- and sucrose-treated groups, showed deficits in active avoidance learning, whereas only ethanol-treated animals in groups with ad libitum access to water showed learning deficits. In the second series of experiments, the effect of saline injections on diet consumption, both in the presence and absence of water, was examined. Although saline injections were associated with decreased diet consumption, there was no effect of free access to water. No differences in blood ethanol concentration were seen among groups. Findings obtained from both series of studies demonstrate that consumption of a Sustacal-based liquid ethanol diet does not decrease if access to water is freely available.

  13. Flood Inundation Modelling Under Uncertainty Using Globally and Freely Available Remote Sensing Data

    Science.gov (United States)

    Yan, K.; Di Baldassarre, G.; Giustarini, L.; Solomatine, D. P.

    2012-04-01

    The extreme consequences of recent catastrophic events have highlighted that flood risk prevention still needs to be improved to reduce human losses and economic damages, which have considerably increased worldwide in recent years. Flood risk management and long term floodplain planning are vital for living with floods, which is the currently proposed approach to cope with floods. To support the decision making processes, a significant issue is the availability of data to build appropriate and reliable models, from which the needed information could be obtained. The desirable data for model building, calibration and validation are often not sufficient or available. A unique opportunity is offered nowadays by globally available data which can be freely downloaded from internet. This might open new opportunities for filling the gap between available and needed data, in order to build reliable models and potentially lead to the development of global inundation models to produce floodplain maps for the entire globe. However, there remains the question of what is the real potential of those global remote sensing data, characterized by different accuracy, for global inundation monitoring and how to integrate them with inundation models. This research aims at contributing to understand whether the current globally and freely available remote sensing data (e.g. SRTM, SAR) can be actually used to appropriately support inundation modelling. In this study, the SRTM DEM is used for hydraulic model building, while ENVISAT-ASAR satellite imagery is used for model validation. To test the usefulness of these globally and freely available data, a model based on the high resolution LiDAR DEM and ground data (high water marks) is used as benchmark. The work is carried out on a data-rich test site: the River Alzette in the north of Luxembourg City. Uncertainties are estimated for both SRTM and LiDAR based models. Probabilistic flood inundation maps are produced under the framework of

  14. Point defects behavior in beta Cu-based shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Romero, R.; Somoza, A. [Univ. Nacional del Centro de la Provincia de Buenos Aires, Tandil (Argentina). IFIMAT

    1999-12-15

    A summary of positron annihilation spectroscopy data relating to the point defect behavior after quenching and to thermal equilibrium in {beta}-phase Cu-based shape memory alloys Cu-Zn-Al and Cu-Al-Be is presented. Particular attention is given to the initial concentration of quenched-in vacancies as a function of the quenching temperature, migration of the retained point defects with aging temperature and time, and the vacancy formation and migration energies. (orig000.

  15. Improved genetic algorithm freely searching for dangerous slip surface of slope

    Institute of Scientific and Technical Information of China (English)

    WAN Wen; CAO Ping; FENG Tao; YUAN Hai-ping

    2005-01-01

    Based on the slice method of the non-circular slip surface for the calculation of integral stability of slope, an improved genetic algorithm was proposed, which can freely search for the most dangerous slip surface of slope and the corresponding minimum safety factor without supposing the geometric shape of the most dangerous slip surface. This improved genetic algorithm can simulate the genetic evolution process of organisms and avoid the local minimum value compared with the classical methods. The results of engineering cases show that it is a global optimal algorithm and has many advantages, such as higher efficiency and shorter time than the simple genetic algorithm.

  16. PROGRAM DROP: A computer program for prediction of evaporation from freely falling multicomponent drops

    Energy Technology Data Exchange (ETDEWEB)

    Gavin, P.M. [Gavin Consulting, Newark, OH (United States)

    1996-12-01

    PROGRAM DROP consists of a series of FORTRAN routine which together are used to model the evaporation of a freely falling, multicomponent drop composed of an arbitrary number of volatile species and a single nonvolatile, inert component. The physics underlying the model are clearly identified, and the model`s relationship to previous work in the literature is described. Test cases are used to illustrate the viability of the model and to highlight its potential usefulness in the accurate prediction of multicomponent droplet vaporization in a variety of applications.

  17. Electron Scattering from Freely Moveable spin-$\\frac{1}{2}$ fermion in Strong Laser Field

    CERN Document Server

    Liu, Ai-Hua

    2014-01-01

    We study the electron scatter from the freely movable spin-$\\frac{1}{2}$ particle in the presence of a linearly polarized laser field in the first Born approximation. The dressed state of electrons is described by a time-dependent wave function derived from a perturbation treatment (of the laser field). With the aid of numerical results we explore the dependencies of the differential cross section on the laser field properties such as the strength, the frequency, as well as on the electron-impact energy, etc. Due to the targets are movable, the DCS of this process reduced comparing to the Mott scattering, especially in small scattering angles.

  18. Biopython: freely available Python tools for computational molecular biology and bioinformatics.

    Science.gov (United States)

    Cock, Peter J A; Antao, Tiago; Chang, Jeffrey T; Chapman, Brad A; Cox, Cymon J; Dalke, Andrew; Friedberg, Iddo; Hamelryck, Thomas; Kauff, Frank; Wilczynski, Bartek; de Hoon, Michiel J L

    2009-06-01

    The Biopython project is a mature open source international collaboration of volunteer developers, providing Python libraries for a wide range of bioinformatics problems. Biopython includes modules for reading and writing different sequence file formats and multiple sequence alignments, dealing with 3D macro molecular structures, interacting with common tools such as BLAST, ClustalW and EMBOSS, accessing key online databases, as well as providing numerical methods for statistical learning. Biopython is freely available, with documentation and source code at (www.biopython.org) under the Biopython license.

  19. Saccade-related activity in areas 18 and 21a of cats freely viewing complex scenes.

    Science.gov (United States)

    Moeller, Gudrun U; Kayser, Christoph; König, Peter

    2007-03-26

    Although saccadic eye movements can radically change the retinal image, perceptually their impact is surprisingly small. Here, we investigate possible neuronal correlates of saccadic suppression in cats freely viewing natural stimuli. By comparing changes attributable to saccadic events with passive stimulus changes, we find that during saccades: (i) evoked and induced activity is reduced in areas 18 and 21a by equal amounts, (ii) the variability of neuronal activity with stimulus category is abolished in both areas, and (iii) the high-power transient induced by stimulus change is not observed. These results present electrophysiological evidence for saccadic suppression at the level of primary and higher visual cortex under natural conditions.

  20. Model Migration Schedules

    OpenAIRE

    1981-01-01

    This report draws on the fundamental regularity exhibited by age profiles of migration all over the world to develop a system of hypothetical model schedules that can be used in multiregional population analyses carried out in countries that lack adequate migration data.

  1. 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....

  2. Migration, klima og sundhed

    DEFF Research Database (Denmark)

    Tellier, Siri; Carballo, Manuel

    2009-01-01

    Many tentative connections have been postulated between migration and climate. This article points to rural-urban migration, particularly into low elevation urban slums prone to flooding as an issue needing urgent attention by health professionals. It also notes the no-man's land in which...

  3. 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

  4. 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....

  5. 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.

  6. International Migration of Couples

    DEFF Research Database (Denmark)

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

    2017-01-01

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

  7. 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...

  8. 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 a

  9. World Migration Degree Global migration flows in directed networks

    CERN Document Server

    Porat, Idan

    2015-01-01

    In this article we analyze the global flow of migrants from 206 source countries to 145 destination countries (2006-2010) and focus on the differences in the migration network pattern between destination and source counters as represented by its degree and weight distribution. Degree represents the connectivity of a country to the global migration network, and plays an important role in defining migration processes and characteristics. Global analysis of migration degree distribution offers a strong potential contribution to understanding of migration as a global phenomenon. In regard to immigration, we found that it is possible to classify destination countries into three classes: global migration hubs with high connectivity and high migration rate; local migration hubs with low connectivity and high migration rate; and local migration hubs with opposite strategy of high connectivity and low migration rate. The different migration strategies of destination countries are emerging from similar and homogenies p...

  10. Trafficking and cell migration.

    Science.gov (United States)

    Ulrich, Florian; Heisenberg, Carl-Philipp

    2009-07-01

    The migration of single cells and epithelial sheets is of great importance for gastrulation and organ formation in developing embryos and, if misregulated, can have dire consequences e.g. during cancer metastasis. A keystone of cell migration is the regulation of adhesive contacts, which are dynamically assembled and disassembled via endocytosis. Here, we discuss some of the basic concepts about the function of endocytic trafficking during cell migration: transport of integrins from the cell rear to the leading edge in fibroblasts; confinement of signalling to the front of single cells by endocytic transport of growth factors; regulation of movement coherence in multicellular sheets by cadherin turnover; and shaping of extracellular chemokine gradients. Taken together, endocytosis enables migrating cells and tissues to dynamically modulate their adhesion and signalling, allowing them to efficiently migrate through their extracellular environment.

  11. 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.

  12. Malaysia and forced migration

    Directory of Open Access Journals (Sweden)

    Arzura Idris

    2012-06-01

    Full Text Available 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. It considers forced migration as an event hosting multifaceted issues related and relevant to forced migrants and suggests that Malaysia has been preoccupied with the issue of forced migration movements. This is largely seen in various responses invoked from Malaysia due to “south-south forced migration movements.” These responses are, however, inadequate in terms of commitment to the international refugee regime. While Malaysia did respond to economic and migration challenges, the paper asserts that such efforts are futile if she ignores issues critical to forced migrants.

  13. Low temperature diffusivity of self-interstitial defects in tungsten

    Science.gov (United States)

    Swinburne, Thomas D.; Ma, Pui-Wai; Dudarev, Sergei L.

    2017-07-01

    The low temperature diffusivity of nanoscale crystal defects, where quantum mechanical fluctuations are known to play a crucial role, are essential to interpret observations of irradiated microstructures conducted at cryogenic temperatures. Using density functional theory calculations, quantum heat bath molecular dynamics and open quantum systems theory, we evaluate the low temperature diffusivity of self-interstitial atom clusters in tungsten valid down to temperatures of 1 K. Due to an exceptionally low defect migration barrier, our results show that interstitial defects exhibit very high diffusivity of order {10}3 μ {{{m}}}2 {{{s}}}-1 over the entire range of temperatures investigated.

  14. Exercise prior to a freely requested meal modifies pre and postprandial glucose profile, substrate oxidation and sympathovagal balance

    OpenAIRE

    Chapelot Didier; Pichon Aurélien; Charlot Keyne

    2011-01-01

    Abstract Background The effects of exercise on glucose and metabolic events preceding and following a freely initiated meal have never been assessed. Moreover, the relationship between these events and sympathovagal balance is not known. The objective of this study was to determine whether exercise prior to a freely requested meal modifies the pre- and postprandial glucose profile, substrate oxidation and sympathovagal balance. Methods Nine young active male subjects consumed a standard break...

  15. On marriage and migration.

    Science.gov (United States)

    Stark, O

    1988-09-01

    Marriage, migration, and related phenomena such as marital stability, fertility, and investment in human capital may be better explained by studying marriage and migration jointly. This paper examines the role of migration in obtaining joint labor market and marriage market equilibrium. When broadly interpreted, marriage and migration share a number of common features. Both involve search and its resolution (pairing of mates in the former and matching of labor and firms in the latter). In both cases, success in finding a partner is sensitive to the availability of partners and to the distribution of their endowments and traits. Almost always, and along with separation and divorce, marriage mandates spatial relocation which may translate into migration. Both involve a movement that is associated with adjustment costs from 1 state into another. The decisions to enter marriage and undertake employment or the decisions to divorce and quit a job depend on exogenous parameters, some of which are determined by the marriage market and the labor market. Since both marriage and divorce take place in the context of broadly defined markets, they may and often are analyzed applying market concepts, theorems, and solutions. Yet the authors could not pinpoint 1 single, systematic attempt that checks through the interactions between marriage and migration, so this paper attempts to rectify this state of research. Essentially, this paper 1) discusses individual decision making pending possible migration prior to or following marriage, 2) examines whether it is easier for a married couple or a single person to migrate, and 3) considers whether marriage dissolution could cause migration when marriage is the only reason that has kept a spouse from moving. This integrated research agenda for both marriage and migration can delineate interesting new implications to examine.

  16. Simultaneous optogenetic manipulation and calcium imaging in freely moving C. elegans

    Directory of Open Access Journals (Sweden)

    Frederick B Shipley

    2014-03-01

    Full Text Available Understanding how an organism's nervous system transforms sensory input into behavioral outputs requires recording and manipulating its neural activity during unrestrained behavior. Here we present an instrument to simultaneously monitor and manipulate neural activity while observing behavior in a freely moving textit{Caenorhabditis elegans}. Neural activity is recorded optically from cells expressing a calcium indicator, GCaMP3. Neural activity is manipulated optically by illuminating targeted neurons expressing the optogenetic protein Channelrhodopsin. Real-time computer vision software tracks the animal's behavior and identifies the location of targeted neurons in the nematode as it crawls. Patterned illumination from a digital micromirror device is used to selectively illuminate subsets of neurons for either calcium imaging or optogenetic stimulation. Real-time computer vision software constantly updates the illumination pattern in response to the worm's movement and thereby allows for independent optical recording or activation of different neurons in the worm as it moves freely. We use the instrument to directly observe the relationship between sensory neuron activation, interneuron dynamics and locomotion in the worm's mechanosensory circuit. We record and compare calcium transients in the backward locomotion command interneurons AVA, in response to optical activation of the anterior mechanosensory neurons ALM, AVM or both.

  17. Whole-brain calcium imaging with cellular resolution in freely behaving Caenorhabditis elegans.

    Science.gov (United States)

    Nguyen, Jeffrey P; Shipley, Frederick B; Linder, Ashley N; Plummer, George S; Liu, Mochi; Setru, Sagar U; Shaevitz, Joshua W; Leifer, Andrew M

    2016-02-23

    The ability to acquire large-scale recordings of neuronal activity in awake and unrestrained animals is needed to provide new insights into how populations of neurons generate animal behavior. We present an instrument capable of recording intracellular calcium transients from the majority of neurons in the head of a freely behaving Caenorhabditis elegans with cellular resolution while simultaneously recording the animal's position, posture, and locomotion. This instrument provides whole-brain imaging with cellular resolution in an unrestrained and behaving animal. We use spinning-disk confocal microscopy to capture 3D volumetric fluorescent images of neurons expressing the calcium indicator GCaMP6s at 6 head-volumes/s. A suite of three cameras monitor neuronal fluorescence and the animal's position and orientation. Custom software tracks the 3D position of the animal's head in real time and two feedback loops adjust a motorized stage and objective to keep the animal's head within the field of view as the animal roams freely. We observe calcium transients from up to 77 neurons for over 4 min and correlate this activity with the animal's behavior. We characterize noise in the system due to animal motion and show that, across worms, multiple neurons show significant correlations with modes of behavior corresponding to forward, backward, and turning locomotion.

  18. Simultaneous optogenetic manipulation and calcium imaging in freely moving C. elegans.

    Science.gov (United States)

    Shipley, Frederick B; Clark, Christopher M; Alkema, Mark J; Leifer, Andrew M

    2014-01-01

    Understanding how an organism's nervous system transforms sensory input into behavioral outputs requires recording and manipulating its neural activity during unrestrained behavior. Here we present an instrument to simultaneously monitor and manipulate neural activity while observing behavior in a freely moving animal, the nematode Caenorhabditis elegans. Neural activity is recorded optically from cells expressing a calcium indicator, GCaMP3. Neural activity is manipulated optically by illuminating targeted neurons expressing the optogenetic protein Channelrhodopsin. Real-time computer vision software tracks the animal's behavior and identifies the location of targeted neurons in the nematode as it crawls. Patterned illumination from a DMD is used to selectively illuminate subsets of neurons for either calcium imaging or optogenetic stimulation. Real-time computer vision software constantly updates the illumination pattern in response to the worm's movement and thereby allows for independent optical recording or activation of different neurons in the worm as it moves freely. We use the instrument to directly observe the relationship between sensory neuron activation, interneuron dynamics and locomotion in the worm's mechanosensory circuit. We record and compare calcium transients in the backward locomotion command interneurons AVA, in response to optical activation of the anterior mechanosensory neurons ALM, AVM or both.

  19. Two useful methods for evaluating antihypertensive drugs in conscious freely moving rats

    Institute of Scientific and Technical Information of China (English)

    Ding-feng SU; Li-ping XU; Chao-yu MIAO; He-hui XIE; Fu-ming SHEN; Yuan-ying JIANG

    2004-01-01

    AIM: Computerized analysis of blood pressure in conscious freely moving rats is a sound technique for physiological and pharmacological studies. The present work, based on this technique, was designed to introduce two useful methods for the evaluation of antihypertensive drugs in conscious spontaneously hypertensive rat (SHR). They were the directly intragastric administration of drugs and modified probability sum test for evaluating the synergism of the combination of two drugs. METHODS AND RESULTS: (1) Directly intragastric administration was used in conscious rats. A catheter was inserted into stomach immediately after arterial catheter insertion. Three days after operation, blood pressure was recorded and drug might be given intragastically via the gastric catheter. (2) Modified probability sum test was used to evaluate the synergism of two drugs. The formula was: q=PA+B/(PA+PB-PA×PB).With this method, it was obtained: q= 1.32 for the effects of the combination of atenolol and nitrendipine (20 mg/kg+ 10 mg/kg) on systolic blood pressure; q=1.41 for the effects of the combination of atenolol and amlodipine (10 mg/kg+l mg/kg) on systolic blood pressure. CONCLUSION: The two methods introduced by the present work will be important and useful for antihypertensive drug evaluation in conscious freely moving rats.

  20. Calculating Puerto Rico’s Ecological Footprint (1970–2010 Using Freely Available Data

    Directory of Open Access Journals (Sweden)

    Matthew E. Hopton

    2015-07-01

    Full Text Available Ecological Footprint Analysis (EFA is appealing as a metric of sustainability because it is straightforward in theory and easy to conceptualize. However, EFA is difficult to implement because it requires extensive data. A simplified approach to EFA that requires fewer data can serve as a perfunctory analysis allowing researchers to examine a system with relatively little cost and effort. We examined whether a simplified approach using freely available data could be applied to Puerto Rico, a densely populated island with limited land resources. Forty-one years of data were assembled to compute the ecological footprint from 1970 to 2010. According to EFA, individuals in Puerto Rico were moving toward sustainability over time, as the per capita ecological footprint decreased from 3.69 ha per capita (ha/ca in 1970 to 3.05 ha/ca in 2010. However, due to population growth, the population’s footprint rose from 1.00 × 107 ha in 1970 to 1.14 × 107 ha in 2010, indicating Puerto Rico as a whole was moving away from sustainability. Our findings demonstrate the promise for conducting EFA using a simplified approach with freely available data, and we discuss potential limitations on data quality and availability that should be addressed to further improve the science.

  1. A user-configurable headstage for multimodality neuromonitoring in freely moving rats

    Directory of Open Access Journals (Sweden)

    Kanokwan Limnuson

    2016-08-01

    Full Text Available Multimodal monitoring of brain activity, physiology, and neurochemistry is an important approach to gain insight into brain function, modulation, and pathology. With recent progress in micro- and nanotechnology, micro-nano-implants have become important catalysts in advancing brain research. However, to date, only a limited number of brain parameters have been measured simultaneously in awake animals in spite of significant recent progress in sensor technology. Here we have provided a cost and time effective approach to designing a headstage to conduct a multimodality brain monitoring in freely moving animals. To demonstrate this method, we have designed a user-configurable headstage for our micromachined multimodal neural probe. The headstage can reliably record direct-current electrocorticography (DC-ECoG, brain oxygen tension (PbrO2, cortical temperature and regional cerebral blood flow (rCBF simultaneously without significant signal crosstalk or movement artifacts for 72 hours. Even in a noisy environment, it can record low-level neural signals with high quality. Moreover, it can easily interface with signal conditioning circuits that have high power consumption and are difficult to miniaturize. To the best of our knowledge, this is the first time where multiple physiological, biochemical and electrophysiological cerebral variables have been simultaneously recorded from freely moving rats. We anticipate that the developed system will aid in gaining further insight into not only normal cerebral functioning but also pathophysiology of conditions such as epilepsy, stroke and traumatic brain injury.

  2. Single-molecule-sensitive fluorescence resonance energy transfer in freely-diffusing attoliter droplets

    Energy Technology Data Exchange (ETDEWEB)

    Rahmanseresht, Sheema; Ramos, Kieran P.; Gamari, Ben D.; Goldner, Lori S., E-mail: lgoldner@physics.umass.edu [Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003 (United States); Milas, Peker [Department of Neuroscience, University of Wisconsin, Madison, Wisconsin 53705 (United States)

    2015-05-11

    Fluorescence resonance energy transfer (FRET) from individual, dye-labeled RNA molecules confined in freely-diffusing attoliter-volume aqueous droplets is carefully compared to FRET from unconfined RNA in solution. The use of freely-diffusing droplets is a remarkably simple and high-throughput technique that facilitates a substantial increase in signal-to-noise for single-molecular-pair FRET measurements. We show that there can be dramatic differences between FRET in solution and in droplets, which we attribute primarily to an altered pH in the confining environment. We also demonstrate that a sufficient concentration of a non-ionic surfactant mitigates this effect and restores FRET to its neutral-pH solution value. At low surfactant levels, even accounting for pH, we observe differences between the distribution of FRET values in solution and in droplets which remain unexplained. Our results will facilitate the use of nanoemulsion droplets as attoliter volume reactors for use in biophysical and biochemical assays, and also in applications such as protein crystallization or nanoparticle synthesis, where careful attention to the pH of the confined phase is required.

  3. On-line electrochemical measurements of cerebral hypoxanthine of freely moving rats

    Institute of Scientific and Technical Information of China (English)

    ZHANG ZiPin; LIN YuQing; MAO LanQun

    2009-01-01

    This study demonstrates an on-line method for continuous measurements of cerebral hypoxanthine in the freely moving rats with integration of selective electrochemical biosensing with in vivo microdialysis sampling. The selective electrochemical biosensing is achieved by using xanthine oxidase (XOD) as the specific sensing element and Prussian blue (PB) as the electrocatalyst for the reduction of H_2O_2 generated from the oxidase-catalyzed reaction. The method is virtually interference-free from the coexisting electroactive species in the brain and exhibits a good stability and reproducibility. Upon integrated with in vivo microdialysis, the on-line method is well suitable for continuous measurements of cerebral hypoxanthine of freely moving rats, which is illustrated by the measurements of the microdialysates after the hypoxanthine standard was externally infused into the rat brain. This study essen-tially offers a facile on-line electrochemical approach to continuous measurements of cerebral hypoxanthine and could find some interesting applications in physiological and pathological investigations associated with hypoxanthine.

  4. Passive sampling methods for contaminated sediments: scientific rationale supporting use of freely dissolved concentrations.

    Science.gov (United States)

    Mayer, Philipp; Parkerton, Thomas F; Adams, Rachel G; Cargill, John G; Gan, Jay; Gouin, Todd; Gschwend, Philip M; Hawthorne, Steven B; Helm, Paul; Witt, Gesine; You, Jing; Escher, Beate I

    2014-04-01

    Passive sampling methods (PSMs) allow the quantification of the freely dissolved concentration (Cfree ) of an organic contaminant even in complex matrices such as sediments. Cfree is directly related to a contaminant's chemical activity, which drives spontaneous processes including diffusive uptake into benthic organisms and exchange with the overlying water column. Consequently, Cfree provides a more relevant dose metric than total sediment concentration. Recent developments in PSMs have significantly improved our ability to reliably measure even very low levels of Cfree . Application of PSMs in sediments is preferably conducted in the equilibrium regime, where freely dissolved concentrations in the sediment are well-linked to the measured concentration in the sampler via analyte-specific partition ratios. The equilibrium condition can then be assured by measuring a time series or a single time point using passive samplers with different surface to volume ratios. Sampling in the kinetic regime is also possible and generally involves the application of performance reference compounds for the calibration. Based on previous research on hydrophobic organic contaminants, it is concluded that Cfree allows a direct assessment of 1) contaminant exchange and equilibrium status between sediment and overlying water, 2) benthic bioaccumulation, and 3) potential toxicity to benthic organisms. Thus, the use of PSMs to measure Cfree provides an improved basis for the mechanistic understanding of fate and transport processes in sediments and has the potential to significantly improve risk assessment and management of contaminated sediments.

  5. The total and freely dissolved polycyclic aromatic hydrocarbons content in residues from biogas production.

    Science.gov (United States)

    Stefaniuk, Magdalena; Oleszczuk, Patryk

    2016-01-01

    In the situation of increasing agricultural utilization of residues from biogas production (RBP) it is important to determine the concentration of contaminants, which could occur in these materials. The group of contaminants that requires special attention are polycyclic aromatic hydrocarbons (PAH). The objective of the study was to determine the total and freely dissolved (Cfree) of PAHs in RBP from 6 different biogas plants operating under various temperature conditions and without or with the separation into the solid and liquid fractions. The freely dissolved PAHs were determined using polyoxymethylene (POM method). The total content of the Σ16 PAHs in RBP varied from 449 to 6147 μg/kgdw, while that of Cfree PAHs was at the level from 57 to 653 ng/L. No significant differences were noted in the content of the Σ16 PAHs (total) between the solid and the liquid fractions. This indicates that in the course of the separation, the PAHs are distributed proportionally between the fractions. However in the case of Cfree, PAHs content in the solid fraction was over twice as high as in the liquid fraction. This was probably due to the greater affinity of the particles present in the liquid fraction to the analysed PAHs than to the particles of the solid fraction. Higher affinity to liquid fraction was also confirmed by the distribution coefficients KTOC determined on the basis of Cfree.

  6. On-line electrochemical measurements of cerebral hypoxanthine of freely moving rats

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    This study demonstrates an on-line method for continuous measurements of cerebral hypoxanthine in the freely moving rats with integration of selective electrochemical biosensing with in vivo microdialysis sampling. The selective electrochemical biosensing is achieved by using xanthine oxidase (XOD) as the specific sensing element and Prussian blue (PB) as the electrocatalyst for the reduction of H2O2 generated from the oxidase-catalyzed reaction. The method is virtually interference-free from the co-existing electroactive species in the brain and exhibits a good stability and reproducibility. Upon integrated with in vivo microdialysis, the on-line method is well suitable for continuous measurements of cerebral hypoxanthine of freely moving rats, which is illustrated by the measurements of the microdi-alysates after the hypoxanthine standard was externally infused into the rat brain. This study essentially offers a facile on-line electrochemical approach to continuous measurements of cerebral hypoxanthine and could find some interesting applications in physiological and pathological investigations associated with hypoxanthine.

  7. Wireless inertial measurement of head kinematics in freely-moving rats

    Science.gov (United States)

    Pasquet, Matthieu O.; Tihy, Matthieu; Gourgeon, Aurélie; Pompili, Marco N.; Godsil, Bill P.; Léna, Clément; Dugué, Guillaume P.

    2016-01-01

    While miniature inertial sensors offer a promising means for precisely detecting, quantifying and classifying animal behaviors, versatile inertial sensing devices adapted for small, freely-moving laboratory animals are still lacking. We developed a standalone and cost-effective platform for performing high-rate wireless inertial measurements of head movements in rats. Our system is designed to enable real-time bidirectional communication between the headborne inertial sensing device and third party systems, which can be used for precise data timestamping and low-latency motion-triggered applications. We illustrate the usefulness of our system in diverse experimental situations. We show that our system can be used for precisely quantifying motor responses evoked by external stimuli, for characterizing head kinematics during normal behavior and for monitoring head posture under normal and pathological conditions obtained using unilateral vestibular lesions. We also introduce and validate a novel method for automatically quantifying behavioral freezing during Pavlovian fear conditioning experiments, which offers superior performance in terms of precision, temporal resolution and efficiency. Thus, this system precisely acquires movement information in freely-moving animals, and can enable objective and quantitative behavioral scoring methods in a wide variety of experimental situations. PMID:27767085

  8. Changes in Cuba’s Migration Policy and Its Impact on Baseball

    OpenAIRE

    Onesimo Julian Moreira Seijos

    2014-01-01

    Baseball is an essential constituent of the Cuban national identity. For nearly a century, Cuban baseball players had joined high-ranking international leagues, including the Negro Leagues and Major League Baseball (MLB) of the United States. After the triumph of the Revolution in 1959, the professional practice of sport was banned in the country. On the other hand, the revolutionary government instituted migration rules that disallowed Cuban citizens to travel abroad freely. Until the collap...

  9. Optimal migration promotes the outbreak of cooperation in heterogeneous populations

    CERN Document Server

    Schweitzer, Frank

    2012-01-01

    We consider a population of agents that are heterogeneous with respect to (i) their strategy when interacting $n_{g}$ times with other agents in an iterated prisoners dilemma game, (ii) their spatial location on $K$ different islands. After each generation, agents adopt strategies proportional to their average payoff received. Assuming a mix of two cooperating and two defecting strategies, we first investigate for isolated islands the conditions for an exclusive domination of each of these strategies and their possible coexistence. This allows to define a threshold frequency for cooperation that, dependent on $n_{g}$ and the initial mix of strategies, describes the outbreak of cooperation in the absense of migration. We then allow migration of a fixed fraction of the population after each generation. Assuming a worst case scenario where all islands are occupied by defecting strategies, whereas only one island is occupied by cooperators at the threshold frequency, we determine the optimal migration rate that a...

  10. Freely chosen stride frequencies during walking and running are not correlated with freely chosen pedalling frequency and are insensitive to strength training.

    Science.gov (United States)

    Sardroodian, Mahta; Madeleine, Pascal; Voigt, Michael; Hansen, Ernst A

    2015-06-01

    Despite biomechanical differences between walking, running, and cycling, these types of movement are supposedly generated by shared neural networks. According to this hypothesis, we investigated relationships between movement frequencies in these tasks as well as effects of strength training on locomotion behaviour. The movement frequencies during walking, running, and cycling were 58.1±2.6 strides min(-1), 81.3±4.4 strides min(-1), and 77.2±11.5 revolutions min(-1), respectively (n=27). Stride frequencies in walking and running correlated positively (r=0.72, pfrequencies during walking and running, respectively, and pedalling frequency (r=0.16, p=0.219 and r=0.04, p=0.424). Potential changes in the freely chosen stride frequencies and stride phase characteristics were also investigated during walking and running through 4 weeks of (i) hip extension strength training (n=9), (ii) hip flexion strength training (n=9), and (iii) no intervention (n=9). Results showed that stride characteristics were unaffected by strength training. That is in contrast to previous observations of decreased pedalling frequency following strength training. In total, these results are proposed to indicate that walking and running movements are robustly generated due to an evolutionary consolidation of the interaction between the musculoskeletal system and neural networks. Further, based on the present results, and the fact that cycling is a postnatally developed task that likely results in a different pattern of descending and afferent input to rhythm generating neural networks than walking and running, we propose pedalling to be generated by neural networks mainly consolidated for locomotion.

  11. Migration without migraines

    Energy Technology Data Exchange (ETDEWEB)

    Lines, L.; Burton, A.; Lu, H.X. [Memorial Univ. of Newfoundland, St. John`s (Canada)

    1994-12-31

    Accurate velocity models are a necessity for reliable migration results. Velocity analysis generally involves the use of methods such as normal moveout analysis (NMO), seismic traveltime tomography, or iterative prestack migration. These techniques can be effective, and each has its own advantage or disadvantage. Conventional NMO methods are relatively inexpensive but basically require simplifying assumptions about geology. Tomography is a more general method but requires traveltime interpretation of prestack data. Iterative prestack depth migration is very general but is computationally expensive. In some cases, there is the opportunity to estimate vertical velocities by use of well information. The well information can be used to optimize poststack migrations, thereby eliminating some of the time and expense of iterative prestack migration. The optimized poststack migration procedure defined here computes the velocity model which minimizes the depth differences between seismic images and formation depths at the well by using a least squares inversion method. The optimization methods described in this paper will hopefully produce ``migrations without migraines.``

  12. High copy arrays containing a sequence upstream of mec-3 alter cell migration and axonal morphology in C. elegans

    Directory of Open Access Journals (Sweden)

    Patchen Brandi

    2001-01-01

    Full Text Available Abstract Background The Caenorhabditis elegans gene mec-3 encodes a LIM-homeodomain protein that is a master regulator of touch receptor neuron genes. Two of the touch neurons, the ALM neurons, are generated in the anterior of the animal and then migrate to near the middle of the animal. In animals transformed with a sequence upstream of mec-3, the ALM touch receptor neurons failed to migrate to their normal positions and sometimes migrated in the wrong direction, and the PLM touch receptor neurons showed axonal defects. Here we characterize this effect and identify the sequence causing the cell migration and axonal defects. Results The ALM migration defect did not result from RNA interference (RNAi, nonspecific effects of carrying a transgenic array, expression of GFP, or the marker gene used to make the transformants. Instead, the ALM migration defect resulted from transgenic arrays containing many copies of a specific 104 bp DNA sequence. Transgenic arrays containing this sequence did not affect all cell migrations. Conclusions The mec-3 upstream sequence appeared to be sequestering (titrating out a specific DNA-binding factor that is required for the ALMs to migrate correctly. Because titration of this factor could reverse the direction of ALM migrations, it may be part of a program that specifies both the direction and extent of ALM migrations. mec-3 is a master regulator of touch receptor neuron genes, so the factor or factors that bind this sequence may also be involved in specifying the fate of touch receptor neurons.

  13. Defects in semiconductors

    CERN Document Server

    Romano, Lucia; Jagadish, Chennupati

    2015-01-01

    This volume, number 91 in the Semiconductor and Semimetals series, focuses on defects in semiconductors. Defects in semiconductors help to explain several phenomena, from diffusion to getter, and to draw theories on materials' behavior in response to electrical or mechanical fields. The volume includes chapters focusing specifically on electron and proton irradiation of silicon, point defects in zinc oxide and gallium nitride, ion implantation defects and shallow junctions in silicon and germanium, and much more. It will help support students and scientists in their experimental and theoret

  14. Imaging defects and dopants

    Directory of Open Access Journals (Sweden)

    H.Philipp Ebert

    2003-06-01

    With the invention of the transistor, a revolution in the development of semiconductor-based electronic devices began. However, even in the very early stages, the importance of defects and dopant atoms became obvious. In fact, if one incorporates the right defects and dopant atoms into semiconductor materials, one can tune their electrical properties such that optimal device characteristics are achieved. Unfortunately, counteractive defects are often also formed unintentionally during semiconductor processing, leading to unfavorable electronic properties. Considerable research efforts have, therefore, focused on understanding the nanoscale physics that governs the formation of point defects, the incorporation behavior of impurities, and their respective electronic properties.

  15. Point Defects in Semiconductors: Microscopic Identification, Metastable Properties, Defect Migration, and Diffusion

    Science.gov (United States)

    1989-03-31

    ENTHALPY OF RECOMBINATION-ENHANCED ... 9917 mate of the relevant value of AH. by only as much as of the assumption that it is the high-T- kinectic - energy 2...6b. OFFICE SYMBOL 7a. NAME OF MONITORI1NG ORGANIZATION Orerlon State University Iopwba Electrical & Comp uter En r.D C. .&OORESS icily. Staff and ZIP...Professor James A. Van Vechten and Assistant Professor John F. Wager ," fN . Department of Electrical & Computer Engineering Oregon State University

  16. Global Governance of Migration

    OpenAIRE

    2011-01-01

    The aim of this thesis is to analyze the recently formed global governance of migration, which has got an unprecedented trans-boundary nature due to the impacts og globalization in the post Cold War era. 

  17. 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....

  18. Tetraspanins in Cell Migration

    Science.gov (United States)

    Jiang, Xupin; Zhang, Jiaping; Huang, Yuesheng

    2015-01-01

    Tetraspanins are a superfamily of small transmembrane proteins that are expressed in almost all eukaryotic cells. Through interacting with one another and with other membrane and intracellular proteins, tetraspanins regulate a wide range of proteins such as integrins, cell surface receptors, and signaling molecules, and thereby engage in diverse cellular processes ranging from cell adhesion and migration to proliferation and differentiation. In particular, tetraspanins modulate the function of proteins involved in all determining factors of cell migration including cell–cell adhesion, cell–ECM adhesion, cytoskeletal protrusion/contraction, and proteolytic ECM remodeling. We herein provide a brief overview of collective in vitro and in vivo studies of tetraspanins to illustrate their regulatory functions in the migration and trafficking of cancer cells, vascular endothelial cells, skin cells (keratinocytes and fibroblasts), and leukocytes. We also discuss the involvement of tetraspanins in various pathologic and remedial processes that rely on cell migration and their potential value as targets for therapeutic intervention. PMID:26091149

  19. Indonesia's migration transition.

    Science.gov (United States)

    Hugo, G

    1995-01-01

    This article describes population movements in Indonesia in the context of rapid and marked social and economic change. Foreign investment in Indonesia is increasing, and global mass media is available to many households. Agriculture is being commercialized, and structural shifts are occurring in the economy. Educational levels are increasing, and women's role and status are shifting. Population migration has increased over the decades, both short and long distance, permanent and temporary, legal and illegal, and migration to and between urban areas. This article focuses specifically on rural-to-urban migration and international migration. Population settlements are dense in the agriculturally rich inner areas of Java, Bali, and Madura. Although the rate of growth of the gross domestic product was 6.8% annually during 1969-94, the World Bank ranked Indonesia as a low-income economy in 1992 because of the large population size. Income per capita is US $670. Indonesia is becoming a large exporter of labor to the Middle East, particularly women. The predominance of women as overseas contract workers is changing women's role and status in the family and is controversial due to the cases of mistreatment. Malaysia's high economic growth rate of over 8% per year means an additional 1.3 million foreign workers and technicians are needed. During the 1980s urban growth increased at a very rapid rate. Urban growth tended to occur along corridors and major transportation routes around urban areas. It is posited that most of the urban growth is due to rural-to-urban migration. Data limitations prevent an exact determination of the extent of rural-to-urban migration. More women are estimated to be involved in movements to cities during the 1980s compared to the 1970s. Recruiters and middlemen have played an important role in rural-to-urban migration and international migration.

  20. Defects in Human Nature

    Institute of Scientific and Technical Information of China (English)

    黄靓

    2008-01-01

    By tracing the defects of society back to the defects of human nature, humanity's essence is proved to be inherent evil. Man's natural tendency to do evil remain harnessed through the controls and conventions imposed by civilization, however, when rules or civilization are weakened, man' s dark side is unleashed.

  1. Birth Defects (For Parents)

    Science.gov (United States)

    ... this virus during pregnancy, her child may have low birth weight, intellectual disability (mental retardation) or learning disabilities, ... and central nervous system problems. A child with late congenital syphilis may have abnormalities of the ... Diagnosing Birth Defects Many birth defects are diagnosed even before ...

  2. A study of surface semi-geostrophic turbulence: freely decaying dynamics

    CERN Document Server

    Ragone, Francesco

    2015-01-01

    In this study we give a characterization of semi-geostrophic turbulence by performing freely decaying simulations of the semi-geostrophic equations for the case of constant uniform potential vorticity, a set of equations known as surface semi-geostrophic approximation. The equations are formulated as conservation laws for potential temperature and potential vorticity, with a nonlinear Monge-Amp\\'{e}re type inversion equation for the streamfunction, expressed in a transformed coordinate system that follows the geostrophic flow. We perform model studies of turbulent surface semi-geostrophic flows in a doubly-periodic domain in the horizontal limited in the vertical by two rigid lids, allowing for variations of potential temperature at one of the boundaries, and we compare them with the corresponding surface quasi-geostrophic case. Results show that, while surface quasi-geostrophic dynamics is dominated by a symmetric population of cyclones-anticyclones, surface semi-geostrophic dynamics features a prominent rol...

  3. Three dimensional simulations of pattern formation during high-pressure, freely localized microwave breakdown in air

    Energy Technology Data Exchange (ETDEWEB)

    Kourtzanidis, K., E-mail: Konstantinos.Kourtzanidis@onera.fr; Boeuf, J. P. [LAPLACE (Laboratoire Plasma et Conversion d' Energie), Université de Toulouse, UPS, INPT, 118 route de Narbonne, F-31062 Toulouse Cedex 9 (France); Rogier, F. [ONERA - The French Aerospace Lab, 2 Avenue édouard Belin, 31000 Toulouse (France)

    2014-12-15

    Recent experiments have demonstrated that a freely localized 100 GHz microwave discharge can propagate towards the microwave source with high speed, forming a complex pattern of self-organized filaments. We present three-dimensional simulations of the formation and propagation of such patterns that reveal more information on their nature and interaction with the electromagnetic waves. The developed three-dimensional Maxwell-plasma solver permits the study of different forms of incident field polarization. Results for linear and circular polarization of the wave are presented and comparisons with recent experiments show a good overall agreement. The three dimensional simulations provide a quantitative analysis of the parameters controlling the time and length scales of the strongly non-linear plasma dynamics and could be useful for potential microwave plasma applications such as aerodynamic flow and combustion control.

  4. Functionally distinct dopamine signals in nucleus accumbens core and shell in the freely moving rat

    DEFF Research Database (Denmark)

    Dreyer, Jakob K.; Vander Weele, Caitlin M.; Lovic, Vedran

    2016-01-01

    Dynamic signaling of mesolimbic dopamine (DA) neurons has been implicated in reward learning, drug abuse, and motivation. However, this system is complex because firing patterns of these neurons are heterogeneous; subpopulations receive distinct synaptic inputs, and project to anatomically...... and functionally distinct downstream targets, including the nucleus accumbens (NAc) shell and core. The functional roles of these cell populations and their real-time signaling properties in freely moving animals are unknown. Resolving the real-time DA signal requires simultaneous knowledge of the synchronized...... activity of DA cell subpopulations and assessment of the down-stream functional effect ofDArelease. Because this is not yet possible solely by experimentation in vivo,we combine computational modeling and fast-scan cyclic voltammetry data to reconstruct the functionally relevantDAsignal in...

  5. An open access pilot freely sharing cancer genomic data from participants in Texas.

    Science.gov (United States)

    Becnel, Lauren B; Pereira, Stacey; Drummond, Jennifer A; Gingras, Marie-Claude; Covington, Kyle R; Kovar, Christie L; Doddapaneni, Harsha Vardhan; Hu, Jianhong; Muzny, Donna; McGuire, Amy L; Wheeler, David A; Gibbs, Richard A

    2016-02-16

    Genomic data sharing in cancer has been restricted to aggregate or controlled-access initiatives to protect the privacy of research participants. By limiting access to these data, it has been argued that the autonomy of individuals who decide to participate in data sharing efforts has been superseded and the utility of the data as research and educational tools reduced. In a pilot Open Access (OA) project from the CPRIT-funded Texas Cancer Research Biobank, many Texas cancer patients were willing to openly share genomic data from tumor and normal matched pair specimens. For the first time, genetic data from 7 human cancer cases with matched normal are freely available without requirement for data use agreements nor any major restriction except that end users cannot attempt to re-identify the participants (http://txcrb.org/open.html).

  6. Freely designable optical frequency conversion in Raman-resonant four-wave-mixing process

    Science.gov (United States)

    Zheng, Jian; Katsuragawa, Masayuki

    2015-01-01

    Nonlinear optical processes are governed by the relative-phase relationships among the relevant electromagnetic fields in these processes. In this Report, we describe the physics of arbitrary manipulation of Raman-resonant four-wave-mixing process by artificial control of relative phases. As a typical example, we show freely designable optical-frequency conversions to extreme spectral regions, mid-infrared and vacuum-ultraviolet, with near-unity quantum efficiencies. Furthermore, we show that such optical-frequency conversions can be realized by using a surprisingly simple technology where transparent plates are placed in a nonlinear optical medium and their positions and thicknesses are adjusted precisely. In a numerical simulation assuming practically applicable parameters in detail, we demonstrate a single-frequency tunable laser that covers the whole vacuum-ultraviolet spectral range of 120 to 200 nm. PMID:25748023

  7. Partition and Correlation Functions of a Freely Crossed Network Using Ising Model-Type Interactions

    CERN Document Server

    Saito, Akira

    2016-01-01

    We set out to determine the partition and correlation functions of a network under the assumption that its elements are freely connected, with an Ising model-type interaction energy associated with each connection. The partition function is obtained from all combinations of loops on the free network, while the correlation function between two elements is obtained based on all combinations of routes between these points, as well as all loops on the network. These functions allow measurement of the dynamics over the whole of any network, regardless of its form. Furthermore, even as parts are added to the network, the partition and correlation functions can still be obtained. As an example, we obtain the partition and correlation functions in a crystal system under the repeated addition of fixed parts.

  8. A simple optogenetic system for behavioral analysis of freely moving small animals.

    Science.gov (United States)

    Kawazoe, Yuya; Yawo, Hiromu; Kimura, Koutarou D

    2013-01-01

    We present a new and simple optogenetic system for the behavioral analysis of small animals. This system includes a strong LED ring array, a high-resolution CCD camera, and the improved channelrhodopsin ChRGR. We used the system for behavioral analysis with the nematode Caenorhabditis elegans as a model, and we found that it can stimulate ChRGR expressed in the body wall muscles of the animals to modulate the behavior. Our results indicate that this system may be suitable for optogenetic behavioral analysis of freely moving small animals under various conditions to understand the principles underlying brain functions. Copyright © 2012 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

  9. Eavesdropping on the 'ping-pong' quantum communi0ation protocol freely in a noise channel

    Institute of Scientific and Technical Information of China (English)

    Deng Fu-Guo; Li Xi-Han; Li Chun-Yan; Zhou Ping; Zhou Hong-Yu

    2007-01-01

    We introduce an attack scheme for eavesdropping freely the ping-pong quantum communication protocol proposed by Bostr(o)m and Felbinger [Phys. Rev. Lett. 89, 187902 (2002)] in a noise channel. The vicious eavesdropper, Eve,intercepts and measures the travel photon transmitted between the sender and the receiver. Then she replaces the quantum signal with a multi-photon signal in the same state, and measures the returned photons with the measuring basis, with which Eve prepares the fake signal except for one photon. This attack increases neither the quantum channel losses nor the error rate in the sampling instances for eavesdropping check. It works for eavesdropping the secret message transmitted with the ping-pong protocol. Finally, we propose a way for improving the security of the ping-pong protocol.

  10. Noninvasive telemetric gaze tracking in freely-moving socially-housed prosimian primates

    Science.gov (United States)

    Shepherd, Stephen V.; Platt, Michael L.

    2006-01-01

    Behavioral and neurophysiological studies strongly suggest that visual orienting reflects the integration of sensory, motor, and motivational variables with behavioral goals. Relatively little is known, however, regarding the goals that govern visual orienting of animals in their natural environments. Field observations suggest that most nonhuman primates orient to features of their natural environments whose salience is dictated by the visual demands of foraging, locomotion and social interaction. This hypothesis is difficult to test quantitatively, however, in part because accurate gaze-tracking technology has not been employed in field studies. We here report the implementation of a new, telemetric, infrared-video gaze-tracker (ISCAN) to measure visual orienting in freely-moving, socially-housed prosimian primates (Lemur catta). Two male lemurs tolerated the system at approximately ¼ body weight, permitting successful measurements of gaze behavior during spontaneous locomotion through both terrestrial and arboreal landscapes, and in both social and asocial environments. PMID:16431130

  11. Wireless stimulation of antennal muscles in freely flying hawkmoths leads to flight path changes.

    Directory of Open Access Journals (Sweden)

    Armin J Hinterwirth

    Full Text Available Insect antennae are sensory organs involved in a variety of behaviors, sensing many different stimulus modalities. As mechanosensors, they are crucial for flight control in the hawkmoth Manduca sexta. One of their roles is to mediate compensatory reflexes of the abdomen in response to rotations of the body in the pitch axis. Abdominal motions, in turn, are a component of the steering mechanism for flying insects. Using a radio controlled, programmable, miniature stimulator, we show that ultra-low-current electrical stimulation of antennal muscles in freely-flying hawkmoths leads to repeatable, transient changes in the animals' pitch angle, as well as less predictable changes in flight speed and flight altitude. We postulate that by deflecting the antennae we indirectly stimulate mechanoreceptors at the base, which drive compensatory reflexes leading to changes in pitch attitude.

  12. A renormalisation group analysis of 2d freely decaying magnetohydrodynamic turbulence

    CERN Document Server

    Brax, P

    1996-01-01

    We study two dimensional freely decaying magnetohydrodynamic turbulence. We investigate the time evolution of the probability law of the gauge field and the stream function. Assuming that this probability law is initially defined by a statistical field theory in the basin of attraction of a renormalisation group fixed point, we show that its time evolution is generated by renormalisation transformations. In the long time regime, the probability law is described by non-unitary conformal field theories. In that case, we prove that the kinetic and magnetic energy spectra are proportional. We then construct a family of fixed points using the (p,p+2) non-unitary minimal models of conformal field theories.

  13. Characterization of epitopes recognized by monoclonal antibodies: experimental approaches supported by freely accessible bioinformatic tools.

    Science.gov (United States)

    Clementi, Nicola; Mancini, Nicasio; Castelli, Matteo; Clementi, Massimo; Burioni, Roberto

    2013-05-01

    Monoclonal antibodies (mAbs) have been used successfully both in research and for clinical purposes. The possible use of protective mAbs directed against different microbial pathogens is currently being considered. The fine definition of the epitope recognized by a protective mAb is an important aspect to be considered for possible development in epitope-based vaccinology. The most accurate approach to this is the X-ray resolution of mAb/antigen crystal complex. Unfortunately, this approach is not always feasible. Under this perspective, several surrogate epitope mapping strategies based on the use of bioinformatics have been developed. In this article, we review the most common, freely accessible, bioinformatic tools used for epitope characterization and provide some basic examples of molecular visualization, editing and computational analysis.

  14. Exploration of freely available web-interfaces for comparative homology modelling of microbial proteins.

    Science.gov (United States)

    Nema, Vijay; Pal, Sudhir Kumar

    2013-01-01

    This study was conducted to find the best suited freely available software for modelling of proteins by taking a few sample proteins. The proteins used were small to big in size with available crystal structures for the purpose of benchmarking. Key players like Phyre2, Swiss-Model, CPHmodels-3.0, Homer, (PS)2, (PS)(2)-V(2), Modweb were used for the comparison and model generation. Benchmarking process was done for four proteins, Icl, InhA, and KatG of Mycobacterium tuberculosis and RpoB of Thermus Thermophilus to get the most suited software. Parameters compared during analysis gave relatively better values for Phyre2 and Swiss-Model. This comparative study gave the information that Phyre2 and Swiss-Model make good models of small and large proteins as compared to other screened software. Other software was also good but is often not very efficient in providing full-length and properly folded structure.

  15. The olfactory bulb theta rhythm follows all frequencies of diaphragmatic respiration in the freely behaving rat

    Directory of Open Access Journals (Sweden)

    Daniel eRojas-Líbano

    2014-06-01

    Full Text Available Sensory-motor relationships are part of the normal operation of sensory systems. Sensing occurs in the context of active sensor movement, which in turn influences sensory processing. We address such a process in the rat olfactory system. Through recordings of the diaphragm electromyogram (EMG, we monitored the motor output of the respiratory circuit involved in sniffing behavior, simultaneously with the local field potential (LFP of the olfactory bulb (OB in rats moving freely in a familiar environment, where they display a wide range of respiratory frequencies. We show that the OB LFP represents the sniff cycle with high reliability at every sniff frequency and can therefore be used to study the neural representation of motor drive in a sensory cortex.

  16. Simultaneous telemetric monitoring of brain glucose and lactate and motion in freely moving rats.

    Science.gov (United States)

    Rocchitta, Gaia; Secchi, Ottavio; Alvau, Maria Domenica; Farina, Donatella; Bazzu, Gianfranco; Calia, Giammario; Migheli, Rossana; Desole, Maria Speranza; O'Neill, Robert D; Serra, Pier A

    2013-11-05

    A new telemetry system for simultaneous detection of extracellular brain glucose and lactate and motion is presented. The device consists of dual-channel, single-supply miniature potentiostat-I/V converter, a microcontroller unit, a signal transmitter, and a miniaturized microvibration sensor. Although based on simple and inexpensive components, the biotelemetry device has been used for accurate transduction of the anodic oxidation currents generated on the surface of implanted glucose and lactate biosensors and animal microvibrations. The device was characterized and validated in vitro before in vivo experiments. The biosensors were implanted in the striatum of freely moving animals and the biotelemetric device was fixed to the animal's head. Physiological and pharmacological stimulations were given in order to induce striatal neural activation and to modify the motor behavior in awake, untethered animals.

  17. Astrocytes in Migration.

    Science.gov (United States)

    Zhan, Jiang Shan; Gao, Kai; Chai, Rui Chao; Jia, Xi Hua; Luo, Dao Peng; Ge, Guo; Jiang, Yu Wu; Fung, Yin-Wan Wendy; Li, Lina; Yu, Albert Cheung Hoi

    2017-01-01

    Cell migration is a fundamental phenomenon that underlies tissue morphogenesis, wound healing, immune response, and cancer metastasis. Great progresses have been made in research methodologies, with cell migration identified as a highly orchestrated process. Brain is considered the most complex organ in the human body, containing many types of neural cells with astrocytes playing crucial roles in monitoring normal functions of the central nervous system. Astrocytes are mostly quiescent under normal physiological conditions in the adult brain but become migratory after injury. Under most known pathological conditions in the brain, spinal cord and retina, astrocytes are activated and become hypertrophic, hyperplastic, and up-regulating GFAP based on the grades of severity. These three observations are the hallmark in glia scar formation-astrogliosis. The reactivation process is initiated with structural changes involving cell process migration and ended with cell migration. Detailed mechanisms in astrocyte migration have not been studied extensively and remain largely unknown. Here, we therefore attempt to review the mechanisms in migration of astrocytes.

  18. A new rapid kindling variant for induction of cortical epileptogenesis in freely moving rats

    Directory of Open Access Journals (Sweden)

    Juan Carlos Morales

    2014-07-01

    Full Text Available Kindling, one of the most used models of experimental epilepsy is based on daily electrical stimulation in several brain structures. Unlike the classic or slow kindling protocols (SK, the rapid kindling types (RK described until now require continuous stimulation at suprathreshold intensities applied directly to the same brain structure used for subsequent electrophysiological and inmunohistochemical studies, usually the hippocampus. However, the cellular changes observed in these rapid protocols, such as astrogliosis and neuronal loss, could be due to experimental manipulation more than to epileptogenesis-related alterations. Here, we developed a new RK protocol in order to generate an improved model of temporal lobe epilepsy (TLE which allows gradual progression of the epilepsy as well as obtaining an epileptic hippocampus, thus avoiding direct surgical manipulation and electric stimulation over this structure. This new protocol consists of basolateral amygdala (BLA stimulation with 10 trains of biphasic pulses (10s;50Hz per day with 20 minutes-intervals, during 3 consecutive days, using a subconvulsive and subthreshold intensity, which guarantees tissue integrity. The progression of epileptic activity was evaluated in freely moving rats through EEG recordings from cortex and amygdala, accompanied with synchronized video recordings. Moreover, we assessed the effectiveness of RK protocol and the establishment of epilepsy by evaluating cellular alterations of hippocampal slices from kindled rats. RK protocol induced convulsive states similar to SK protocols but in 3 days, with persistently lowered threshold to seizure induction and epileptogenic-dependent cellular changes in amygdala projection areas. We concluded that this novel RK protocol introduces a new variant of the chronic epileptogenesis models in freely moving rats, which is faster, highly reproducible and causes minimum cell damage with respect to that observed in other experimental

  19. A new rapid kindling variant for induction of cortical epileptogenesis in freely moving rats

    Science.gov (United States)

    Morales, Juan Carlos; Álvarez-Ferradas, Carla; Roncagliolo, Manuel; Fuenzalida, Marco; Wellmann, Mario; Nualart, Francisco Javier; Bonansco, Christian

    2014-01-01

    Kindling, one of the most used models of experimental epilepsy is based on daily electrical stimulation in several brain structures. Unlike the classic or slow kindling protocols (SK), the rapid kindling types (RK) described until now require continuous stimulation at suprathreshold intensities applied directly to the same brain structure used for subsequent electrophysiological and immunohistochemical studies, usually the hippocampus. However, the cellular changes observed in these rapid protocols, such as astrogliosis and neuronal loss, could be due to experimental manipulation more than to epileptogenesis-related alterations. Here, we developed a new RK protocol in order to generate an improved model of temporal lobe epilepsy (TLE) which allows gradual progression of the epilepsy as well as obtaining an epileptic hippocampus, thus avoiding direct surgical manipulation and electric stimulation over this structure. This new protocol consists of basolateral amygdala (BLA) stimulation with 10 trains of biphasic pulses (10 s; 50 Hz) per day with 20 min-intervals, during 3 consecutive days, using a subconvulsive and subthreshold intensity, which guarantees tissue integrity. The progression of epileptic activity was evaluated in freely moving rats through electroencephalographic (EEG) recordings from cortex and amygdala, accompanied with synchronized video recordings. Moreover, we assessed the effectiveness of RK protocol and the establishment of epilepsy by evaluating cellular alterations of hippocampal slices from kindled rats. RK protocol induced convulsive states similar to SK protocols but in 3 days, with persistently lowered threshold to seizure induction and epileptogenic-dependent cellular changes in amygdala projection areas. We concluded that this novel RK protocol introduces a new variant of the chronic epileptogenesis models in freely moving rats, which is faster, highly reproducible and causes minimum cell damage with respect to that observed in other

  20. Defects at oxide surfaces

    CERN Document Server

    Thornton, Geoff

    2015-01-01

    This book presents the basics and characterization of defects at oxide surfaces. It provides a state-of-the-art review of the field, containing information to the various types of surface defects, describes analytical methods to study defects, their chemical activity and the catalytic reactivity of oxides. Numerical simulations of defective structures complete the picture developed. Defects on planar surfaces form the focus of much of the book, although the investigation of powder samples also form an important part. The experimental study of planar surfaces opens the possibility of applying the large armoury of techniques that have been developed over the last half-century to study surfaces in ultra-high vacuum. This enables the acquisition of atomic level data under well-controlled conditions, providing a stringent test of theoretical methods. The latter can then be more reliably applied to systems such as nanoparticles for which accurate methods of characterization of structure and electronic properties ha...

  1. Cosmic defects and cosmology

    CERN Document Server

    Magueijo, J; Magueijo, Joao; Brandenberger, Robert

    2000-01-01

    We provide a pedagogical overview of defect models of structure formation. We first introduce the concept of topological defect, and describe how to classify them. We then show how defects might be produced in phase transitions in the Early Universe and approach non-pathological scaling solutions. A very heuristic account of structure formation with defects is then provided, following which we introduce the tool box required for high precision calculations of CMB and LSS power spectra in these theories. The decomposition into scalar vector and tensor modes is reviewed, and then we introduce the concept of unequal-time correlator. We use isotropy and causality to constrain the form of these correlators. We finally show how these correlators may be decomposed into eigenmodes, thereby reducing a defect problem to a series of ``inflation'' problems. We conclude with a short description of results in these theories and how they fare against observations. We finally describe yet another application of topological d...

  2. S1pr2/Gα13 signaling regulates the migration of endocardial precursors by controlling endoderm convergence.

    Science.gov (United States)

    Xie, Huaping; Ye, Ding; Sepich, Diane; Lin, Fang

    2016-06-15

    Formation of the heart tube requires synchronized migration of endocardial and myocardial precursors. Our previous studies indicated that in S1pr2/Gα13-deficient embryos, impaired endoderm convergence disrupted the medial migration of myocardial precursors, resulting in the formation of two myocardial populations. Here we show that endoderm convergence also regulates endocardial migration. In embryos defective for S1pr2/Gα13 signaling, endocardial precursors failed to migrate towards the midline, and the presumptive endocardium surrounded the bilaterally-located myocardial cells rather than being encompassed by them. In vivo imaging of control embryos revealed that, like their myocardial counterparts, endocardial precursors migrated with the converging endoderm, though from a more anterior point, then moved from the dorsal to the ventral side of the endoderm (subduction), and finally migrated posteriorly towards myocardial precursors, ultimately forming the inner layer of the heart tube. In embryos defective for endoderm convergence due to an S1pr2/Gα13 deficiency, both the medial migration and the subduction of endocardial precursors were impaired, and their posterior migration towards the myocardial precursors was premature. This placed them medial to the myocardial populations, physically blocking the medial migration of the myocardial precursors. Furthermore, contact between the endocardial and myocardial precursor populations disrupted the epithelial architecture of the myocardial precursors, and thus their medial migration; in embryos depleted of endocardial cells, the myocardial migration defect was partially rescued. Our data indicate that endoderm convergence regulates the medial migration of endocardial precursors, and that premature association of the endocardial and myocardial populations contributes to myocardial migration defects observed in S1pr2/Gα13-deficient embryos. The demonstration that endoderm convergence regulates the synchronized

  3. A novel detachable head-mounted device for simultaneous EEG and photoacoustic monitoring of epilepsy in freely moving rats.

    Science.gov (United States)

    Wang, Bo; Zhou, Junli; Carney, Paul; Jiang, Huabei

    2015-02-01

    The study of neuro-hemodynamic changes in freely moving animals provides for a better understanding of brain dynamics in normal and disease states. While it has been shown that hemodynamic changes are closely related to seizures, methods for detection in freely moving animals are limited. In this work, we integrate photoacoustic sensor technology and electroencephalography into a small portable device that can be attached on the head of wake freely moving animals. We demonstrate chronic simultaneous monitoring of photoacoustic and electroencephalographic signals in an acute seizure model of epilepsy. Our results demonstrate that both the neural and vascular responses during seizures in freely moving rats have characteristics which are observed to be different and more diverse from that of anesthetized rats. This implies that the neurovascular coupling in seizure in free moving animals are more complicated, which calls for more detailed study in future. To the best of our knowledge, this is the first time for hemodynamic monitoring of seizure in free moving animals. This technology also promises for other hemodynamic related research study in freely moving small animals.

  4. IJEPA: Gray Area for Health Policy and International Nurse Migration.

    Science.gov (United States)

    Efendi, Ferry; Mackey, Timothy Ken; Huang, Mei-Chih; Chen, Ching-Min

    2017-05-01

    Indonesia is recognized as a nurse exporting country, with policies that encourage nursing professionals to emigrate abroad. This includes the country's adoption of international principles attempting to protect Indonesian nurses that emigrate as well as the country's own participation in a bilateral trade and investment agreement, known as the Indonesia-Japan Economic Partnership Agreement that facilitates Indonesian nurse migration to Japan. Despite the potential trade and employment benefits from sending nurses abroad under the Indonesia-Japan Economic Partnership Agreement, Indonesia itself is suffering from a crisis in nursing capacity and ensuring adequate healthcare access for its own populations. This represents a distinct challenge for Indonesia in appropriately balancing domestic health workforce needs, employment, and training opportunities for Indonesian nurses, and the need to acknowledge the rights of nurses to freely migrate abroad. Hence, this article reviews the complex operational and ethical issues associated with Indonesian health worker migration under the Indonesia-Japan Economic Partnership Agreement. It also introduces a policy proposal to improve performance of the Indonesia-Japan Economic Partnership Agreement and better align it with international principles focused on equitable health worker migration.

  5. Electron paramagnetic resonance study of defects in {gamma}-irradiated marine mussel (Mytilus galloprovincialis) and Scallop (Pecten jacobaeus) shells

    Energy Technology Data Exchange (ETDEWEB)

    Koeseoglu, R. [Erciyes Univ., Halil Bayraktar Health Services Vocational Coll., Kayseri (Turkey); Koeksal, F. [Ondokuz Mayis Univ., Physics Dept., Samsun (Turkey); Birey, M. [Ankara Univ., Physics Dept., Ankara (Turkey)

    2004-11-01

    EPR studies have been performed on some gamma-irradiated marine mussels (Mytilus galloprovincialis) and scallops (Pecten jacobaeus) from the families of Mytilidae and Pectinidae, respectively. Before {gamma}-irradiation, the EPR lines of Mytilus galloprovincialis indicated the existence of Mn{sup 2+} ions, which were not observed in the powders of scallop shells. {gamma}-irradiation induced defects in powders of Mytilus galloprovincialis shells, were attributed to orthorhombic CO{sub 3}{sup -}, axial CO{sub 3}{sup 3-}, orthorhombic CO{sub 2}{sup -}, freely rotating CO{sub 2}{sup -}, freely rotating SO{sub 2}{sup -}, axial SO{sub 3}{sup -}, isotropic PO{sub 4}{sup 2-} and organic free radicals. {gamma}-irradiation induced defects in powders of Pecten jacobaeus shells were attributed to orthorhombic CO{sub 3}{sup -}, axial CO{sub 3}{sup 3-}, orthorhombic CO{sub 2}{sup -}, freely rotating CO{sub 2}{sup -}, freely rotating SO{sub 2}{sup -}, and axial SO{sub 3}{sup -} free radicals. The EPR parameters of the free radicals were compared with literature data on similar defects. (orig.)

  6. Diabetes mellitus and birth defects

    Science.gov (United States)

    Correa, Adolfo; Gilboa, Suzanne M.; Besser, Lilah M.; Botto, Lorenzo D.; Moore, Cynthia A.; Hobbs, Charlotte A.; Cleves, Mario A.; Riehle-Colarusso, Tiffany J.; Waller, D. Kim; Reece, E. Albert

    2016-01-01

    OBJECTIVE The purpose of this study was to examine associations between diabetes mellitus and 39 birth defects. STUDY DESIGN This was a multicenter case-control study of mothers of infants who were born with (n = 13,030) and without (n = 4895) birth defects in the National Birth Defects Prevention Study (1997–2003). RESULTS Pregestational diabetes mellitus (PGDM) was associated significantly with noncardiac defects (isolated, 7/23 defects; multiples, 13/23 defects) and cardiac defects (isolated, 11/16 defects; multiples, 8/16 defects). Adjusted odds ratios for PGDM and all isolated and multiple defects were 3.17 (95% CI, 2.20–4.99) and 8.62 (95% CI, 5.27–14.10), respectively. Gestational diabetes mellitus (GDM) was associated with fewer noncardiac defects (isolated, 3/23 defects; multiples, 3/23 defects) and cardiac defects (isolated, 3/16 defects; multiples, 2/16 defects). Odds ratios between GDM and all isolated and multiple defects were 1.42 (95% CI, 1.17–1.73) and 1.50 (95% CI, 1.13–2.00), respectively. These associations were limited generally to offspring of women with prepregnancy body mass index ≥25 kg/m2. CONCLUSION PGDM was associated with a wide range of birth defects; GDM was associated with a limited group of birth defects. PMID:18674752

  7. 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....

  8. Planet Formation with Migration

    CERN Document Server

    Chambers, J E

    2006-01-01

    In the core-accretion model, gas-giant planets form solid cores which then accrete gaseous envelopes. Tidal interactions with disk gas cause a core to undergo inward type-I migration in 10^4 to 10^5 years. Cores must form faster than this to survive. Giant planets clear a gap in the disk and undergo inward type-II migration in <10^6 years if observed disk accretion rates apply to the disk as a whole. Type-II migration times exceed typical disk lifetimes if viscous accretion occurs mainly in the surface layers of disks. Low turbulent viscosities near the midplane may allow planetesimals to form by coagulation of dust grains. The radius r of such planetesimals is unknown. If r<0.5 km, the core formation time is shorter than the type-I migration timescale and cores will survive. Migration is substantial in most cases, leading to a wide range of planetary orbits, consistent with the observed variety of extrasolar systems. When r is of order 100m and midplane alpha is of order 3 times 10^-5, giant planets si...

  9. What Are Neural Tube Defects?

    Science.gov (United States)

    ... NICHD Research Information Clinical Trials Resources and Publications Neural Tube Defects (NTDs): Condition Information Skip sharing on social media links Share this: Page Content What are neural tube defects? Neural (pronounced NOOR-uhl ) tube defects are ...

  10. What Are Congenital Heart Defects?

    Science.gov (United States)

    ... page from the NHLBI on Twitter. What Are Congenital Heart Defects? Congenital (kon-JEN-ih-tal) heart defects are problems ... carry blood to the heart or the body Congenital heart defects change the normal flow of blood through the ...

  11. Gβ1 is required for neutrophil migration in zebrafish.

    Science.gov (United States)

    Ke, Wenfan; Ye, Ding; Mersch, Kacey; Xu, Hui; Chen, Songhai; Lin, Fang

    2017-08-01

    Signaling mediated by G protein-coupled receptors (GPCRs) is essential for the migration of cells toward chemoattractants. The recruitment of neutrophils to injured tissues in zebrafish larvae is a useful model for studying neutrophil migration and trafficking in vivo. Indeed, the study of this process led to the discovery that PI3Kγ is required for the polarity and motility of neutrophils, features that are necessary for the directed migration of these cells to wounds. However, the mechanism by which PI3Kγ is activated remains to be determined. Here we show that signaling by specifically the heterotrimeric G protein subunit Gβ1 is critical for neutrophil migration in response to wounding. In embryos treated with small-molecule inhibitors of Gβγ signaling, neutrophils failed to migrate to wound sites. Although both the Gβ1 and Gβ4 isoforms are expressed in migrating neutrophils, only deficiency for the former (morpholino-based knockdown) interfered with the directed migration of neutrophils towards wounds. The Gβ1 deficiency also impaired the ability of cells to change cell shape and reduced their general motility, defects that are similar to those in neutrophils deficient for PI3Kγ. Transplantation assays showed that the requirement for Gβ1 in neutrophil migration is cell autonomous. Finally, live imaging revealed that Gβ1 is required for polarized activation of PI3K, and for the actin dynamics that enable neutrophil migration. Collectively, our data indicate that Gβ1 signaling controls proper neutrophil migration by activating PI3K and modulating actin dynamics. Moreover, they illustrate a role for a specific Gβ isoform in chemotaxis in vivo. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Primary mesenchyme cell migration requires a chondroitin sulfate/dermatan sulfate proteoglycan.

    Science.gov (United States)

    Lane, M C; Solursh, M

    1991-02-01

    Primary mesenchyme cell migration in the sea urchin embryo is inhibited by sulfate deprivation and exposure to exogenous beta-D-xylosides, two treatments known to disrupt proteoglycan synthesis. We show that in the developing sea urchin, exogenous xyloside affects the synthesis by the primary mesenchyme cells of a very large, cell surface chondroitin sulfate/dermatan sulfate proteoglycan. This proteoglycan is present in a partially purified fraction that restores migratory ability to defective cells in vitro. The integrity of this chondroitin sulfate/dermatan sulfate proteoglycan appears essential for primary mesenchyme cell migration since treatment of actively migrating cells with chondroitinase ABC reversibly inhibited their migration in vitro.

  13. 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....

  14. Neural tube defects

    Directory of Open Access Journals (Sweden)

    M.E. Marshall

    1981-09-01

    Full Text Available Neural tube defects refer to any defect in the morphogenesis of the neural tube, the most common types being spina bifida and anencephaly. Spina bifida has been recognised in skeletons found in north-eastern Morocco and estimated to have an age of almost 12 000 years. It was also known to the ancient Greek and Arabian physicians who thought that the bony defect was due to the tumour. The term spina bifida was first used by Professor Nicolai Tulp of Amsterdam in 1652. Many other terms have been used to describe this defect, but spina bifida remains the most useful general term, as it describes the separation of the vertebral elements in the midline.

  15. Defect Prevention Based on 5 Dimensions of Defect Origin

    Directory of Open Access Journals (Sweden)

    Sakthi Kumaresh

    2012-08-01

    Full Text Available “Discovering the unexpected is more important than confirming the known [7]. In software development,the “unexpected” one relates to defects. These defects when unattended would cause failure to the productand risk to the users. The increasing dependency of society on software and the crucial consequences that afailure can cause requires the need to find out the defects at the origin itself. Based on the lessons learntfrom the earlier set of projects, a defect framework highlighting the 5 Dimensions (Ds of defect origin isproposed in this work. The defect framework is based on analyzing the defects that had emerged fromvarious stages of software development like Requirements, Design, Coding, Testing and Timeline (defectsdue to lack of time during development. This study is not limited to just identifying the origin of defects atvarious phases of software development but also finds out the reasons for such defects, and defectpreventive (DP measures are proposed for each type of defect. This work can help practitioners chooseeffective defect avoidance measures.In addition to arriving at defect framework, this work also proposes a defect injection metric based onseverity of the defect rather than just defect count, which gives the number of adjusted defects produced bya project at various phases. The defect injection metric value, once calculated, serves as a yardstick tomake a comparison in the improvements made in the software process development between similar set ofprojects

  16. Impact of extraneous mispositioned events on motion-corrected brain SPECT images of freely moving animals

    Energy Technology Data Exchange (ETDEWEB)

    Angelis, Georgios I., E-mail: georgios.angelis@sydney.edu.au; Ryder, William J.; Bashar, Rezaul; Meikle, Steven R. [Faculty of Health Sciences and Brain and Mind Research Institute, The University of Sydney, Sydney, NSW 2006 (Australia); Fulton, Roger R. [Faculty of Health Sciences and Brain and Mind Research Institute, The University of Sydney, Sydney, NSW 2006 (Australia); School of Physics, University of Sydney, Sydney, NSW 2006 (Australia); Department of Medical Physics, Westmead Hospital, Sydney, NSW 2145 (Australia)

    2014-09-15

    Purpose: Single photon emission computed tomography (SPECT) brain imaging of freely moving small animals would allow a wide range of important neurological processes and behaviors to be studied, which are normally inhibited by anesthetic drugs or precluded due to the animal being restrained. While rigid body motion of the head can be tracked and accounted for in the reconstruction, activity in the torso may confound brain measurements, especially since motion of the torso is more complex (i.e., nonrigid) and not well correlated with that of the head. The authors investigated the impact of mispositioned events and attenuation due to the torso on the accuracy of motion corrected brain images of freely moving mice. Methods: Monte Carlo simulations of a realistic voxelized mouse phantom and a dual compartment phantom were performed. Each phantom comprised a target and an extraneous compartment which were able to move independently of each other. Motion correction was performed based on the known motion of the target compartment only. Two SPECT camera geometries were investigated: a rotating single head detector and a stationary full ring detector. The effects of motion, detector geometry, and energy of the emitted photons (hence, attenuation) on bias and noise in reconstructed brain regions were evaluated. Results: The authors observed two main sources of bias: (a) motion-related inconsistencies in the projection data and (b) the mismatch between attenuation and emission. Both effects are caused by the assumption that the orientation of the torso is difficult to track and model, and therefore cannot be conveniently corrected for. The motion induced bias in some regions was up to 12% when no attenuation effects were considered, while it reached 40% when also combined with attenuation related inconsistencies. The detector geometry (i.e., rotating vs full ring) has a big impact on the accuracy of the reconstructed images, with the full ring detector being more

  17. FRETBursts: An Open Source Toolkit for Analysis of Freely-Diffusing Single-Molecule FRET.

    Science.gov (United States)

    Ingargiola, Antonino; Lerner, Eitan; Chung, SangYoon; Weiss, Shimon; Michalet, Xavier

    2016-01-01

    Single-molecule Förster Resonance Energy Transfer (smFRET) allows probing intermolecular interactions and conformational changes in biomacromolecules, and represents an invaluable tool for studying cellular processes at the molecular scale. smFRET experiments can detect the distance between two fluorescent labels (donor and acceptor) in the 3-10 nm range. In the commonly employed confocal geometry, molecules are free to diffuse in solution. When a molecule traverses the excitation volume, it emits a burst of photons, which can be detected by single-photon avalanche diode (SPAD) detectors. The intensities of donor and acceptor fluorescence can then be related to the distance between the two fluorophores. While recent years have seen a growing number of contributions proposing improvements or new techniques in smFRET data analysis, rarely have those publications been accompanied by software implementation. In particular, despite the widespread application of smFRET, no complete software package for smFRET burst analysis is freely available to date. In this paper, we introduce FRETBursts, an open source software for analysis of freely-diffusing smFRET data. FRETBursts allows executing all the fundamental steps of smFRET bursts analysis using state-of-the-art as well as novel techniques, while providing an open, robust and well-documented implementation. Therefore, FRETBursts represents an ideal platform for comparison and development of new methods in burst analysis. We employ modern software engineering principles in order to minimize bugs and facilitate long-term maintainability. Furthermore, we place a strong focus on reproducibility by relying on Jupyter notebooks for FRETBursts execution. Notebooks are executable documents capturing all the steps of the analysis (including data files, input parameters, and results) and can be easily shared to replicate complete smFRET analyzes. Notebooks allow beginners to execute complex workflows and advanced users to

  18. Sleeping dendrites: fiber-optic measurements of dendritic calcium activity in freely moving and sleeping animals

    Directory of Open Access Journals (Sweden)

    Julie Seibt

    2014-03-01

    Full Text Available Dendrites are the post-synaptic sites of most excitatory and inhibitory synapses in the brain, making them the main location of cortical information processing and synaptic plasticity. Although current hypotheses suggest a central role for sleep in proper cognitive function and brain plasticity, virtually nothing is known about changes in dendritic activity across the sleep-wake cycle and how waking experience modifies this activity. To start addressing these questions, we developed a method that allows long-term recordings of EEGs/EMG combined with in vivo cortical calcium (Ca2+ activity in freely moving and sleeping rats. We measured Ca2+ activity from populations of dendrites of layer (L 5 pyramidal neurons (n = 13 rats that we compared with Ca2+ activity from populations of neurons in L2/3 (n = 11 rats. L5 and L2/3 neurons were labelled using bolus injection of OGB1-AM or GCaMP6 (1. Ca2+ signals were detected using a fiber-optic system (cannula diameter = 400µm, transmitting the changes in fluorescence to a photodiode. Ca2+ fluctuations could then be correlated with ongoing changes in brain oscillatory activity during 5 major brain states: active wake [AW], quiet wake [QW], NREM, REM and NREM-REM transition (or intermediate state, [IS]. Our Ca2+ recordings show large transients in L5 dendrites and L2/3 neurons that oscillate predominantly at frequencies In summary, we show that this technique is successful in monitoring fluctuations in ongoing dendritic Ca2+ activity during natural brain states and allows, in principle, to combine behavioral measurement with imaging from various brain regions (e.g. deep structures in freely behaving animals. Using this method, we show that Ca2+ transients from populations of L2/3 neurons and L5 dendrites are deferentially regulated across the sleep/wake cycle, with dendritic activity being the highest during the IS sleep. Our correlation analysis suggests that specific sleep EEG activity during NREM and IS

  19. 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

  20. Analysing immune cell migration.

    Science.gov (United States)

    Beltman, Joost B; Marée, Athanasius F M; de Boer, Rob J

    2009-11-01

    The visualization of the dynamic behaviour of and interactions between immune cells using time-lapse video microscopy has an important role in modern immunology. To draw robust conclusions, quantification of such cell migration is required. However, imaging experiments are associated with various artefacts that can affect the estimated positions of the immune cells under analysis, which form the basis of any subsequent analysis. Here, we describe potential artefacts that could affect the interpretation of data sets on immune cell migration. We propose how these errors can be recognized and corrected, and suggest ways to prevent the data analysis itself leading to biased results.

  1. 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...

  2. 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

  3. International Migration of Couples

    DEFF Research Database (Denmark)

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

    2017-01-01

    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...

  4. Migration strategies of insects.

    Science.gov (United States)

    Dingle, H

    1972-03-24

    Physiological and ecological results from a variety of species are consistent with what seem to be valid general statements concerning insect migration. These are as follows: (i)During migration locomotory functions are enhanced and vegetative functions such as feeding and reproduction are suppressed. (ii) Migration usually occurs prereproductively in the life of the adult insect (the oogenesis-flight syndrome). (iii)Since migrant individuals are usually prereproductive, their reproductive values, and hence colonizing abilities, are at or near maximum. (iv) Migrants usually reside in temporary habitats. (v)Migrants have a high potential for population increase, r, which is also advantageous for colonizers. (vi)Both the physiological and ecological parameters of migration are modifiable by environmental factors (that is, phenotypically modifiable)to suit the prevailing conditions. Taken together, these criteria establish a comprehensive theory and adumbrate the basic strategy for migrant insects. This basic strategy is modified to suit the ecological requirements of individual species. Comparative studies of these modifications are of considerable theoretical and practical interest, the more so since most economically important insects are migrants. No satisfactory general statements can as yet be made with respect to the genotype and migration. Certainly we expect colonizing populiations to possess genotypes favoring a high r, but genotypic variation in r depends on the heritabilities of life table statistics, and such measurements are yet to be made (10, 53). The fact that flight duration can be increased by appropriate selection in Oncopeltus fasciatus, and the demonstration of additive genetic variance for this trait in Lygaeus kalmii, suggest that heritability studies of migratory behavior would also be worth pursuing. Most interesting of course, will be possible genetic correlations between migration and life history parameters. Also, migration often

  5. MODEL OF GEOMEDIA CONTAINING DEFECTS: COLLECTIVE EFFECTS OF DEFECTS EVOLUTION DURING FORMATION OF POTENTIAL EARTHQUAKE FOCI

    Directory of Open Access Journals (Sweden)

    I. A. Panteleev

    2015-09-01

    transition is manifested by localized cataclastic deformation (i.e. a set of weak earthquakes, which migrates in space at a velocity several orders of magnitude lower than the speed of sound, as a ‘slow’ deformation wave (Fig. 3. Further reduction of the structural scaling parameter leads to degeneracy of the orientation meta-stability and formation of localized dissipative defect structures in the medium. Once the critical stress is reached, such structures develop in the blow-up regime, i.e. the mode of avalanche-unstable growth of defects in the localized area that is shrinking eventually. At the scale of observation, this process is manifested as brittle fracturing that causes formation of a deformation zone, which size is proportional to the scale of observation, and corresponds to occurrence of a strong earthquake.On the basis of the proposed model showing the behavior of the geomedium containing defects in the field of external stresses, it is possible to describe main ways of stress relaxation in the rock massives – brittle large-scale destruction and cataclastic deformation as consequences of the collective behavior of defects, which is determined by the structural scaling parameter.Results of this study may prove useful for estimation of critical stresses and assessment of the geomedium status in seismically active regions and be viewed as model representations of the physical hypothesis about the uniform nature of deve­lopment of discontinuities/defects in a wide range of spatial scales. 

  6. Mechanisms of Bacterial (Serratia marcescens) Attachment to, Migration along, and Killing of Fungal Hyphae.

    Science.gov (United States)

    Hover, Tal; Maya, Tal; Ron, Sapir; Sandovsky, Hani; Shadkchan, Yana; Kijner, Nitzan; Mitiagin, Yulia; Fichtman, Boris; Harel, Amnon; Shanks, Robert M Q; Bruna, Roberto E; García-Véscovi, Eleonora; Osherov, Nir

    2016-05-01

    We have found a remarkable capacity for the ubiquitous Gram-negative rod bacterium Serratia marcescens to migrate along and kill the mycelia of zygomycete molds. This migration was restricted to zygomycete molds and several basidiomycete species. No migration was seen on any molds of the phylum Ascomycota. S. marcescens migration did not require fungal viability or surrounding growth medium, as bacteria migrated along aerial hyphae as well.S. marcescens did not exhibit growth tropism toward zygomycete mycelium. Bacterial migration along hyphae proceeded only when the hyphae grew into the bacterial colony. S. marcescens cells initially migrated along the hyphae, forming attached microcolonies that grew and coalesced to generate a biofilm that covered and killed the mycelium. Flagellum-defective strains of S. marcescens were able to migrate along zygomycete hyphae, although they were significantly slower than the wild-type strain and were delayed in fungal killing. Bacterial attachment to the mycelium does not necessitate type 1 fimbrial adhesion, since mutants defective in this adhesin migrated equally well as or faster than the wild-type strain. Killing does not depend on the secretion of S. marcescens chitinases, as mutants in which all three chitinase genes were deleted retained wild-type killing abilities. A better understanding of the mechanisms by which S. marcescens binds to, spreads on, and kills fungal hyphae might serve as an excellent model system for such interactions in general; fungal killing could be employed in agricultural fungal biocontrol.

  7. Experimental study of forces on freely moving spherical particles during resuspension into turbulent flow

    CERN Document Server

    Traugott, Hadar

    2015-01-01

    Turbulent resuspension is the process of lifting solid particles from the bottom by turbulent flow, ubiquitous in natural and industrial problems. The process is a sequence of events that start with an incipient motion when the particle is dislodged from its place, continue as sliding or rolling along the surface, and ending with the detachment of the particle from the surface and lifting it up into the flow. In this study we measure in details the motion of freely moving solid spherical particles along the bottom smooth wall under an oscillating grid turbulence and track them through the lift-off events. We measure simultaneously the Lagrangian trajectories of the particles and the flow tracers around them. We estimate the local flow parameters and extract the different force terms that act on a particle. For the particles of the diameter comparable with the Kolmogorov length scale, either sliding or rolling along the smooth wall under a zero-mean turbulent flow, we find that: i) the lift force is a dominant...

  8. Marangoni Effect on the Shape of Freely Receding Evaporating Sessile Droplets of Perfectly Wetting Liquids

    Science.gov (United States)

    Tsoumpas, Yannis; Dehaeck, Sam; Rednikov, Alexey; Colinet, Pierre

    2014-11-01

    Freely receding evaporating sessile droplets of perfectly wetting liquids (HFE-7100, 7200 and 7500), with small finite contact angles induced by evaporation, are studied with a Mach-Zehnder interferometer. Surprisingly, the experimentally obtained profiles turn out to deviate from the classical macroscopic static shape of a sessile droplet (as determined by gravity and capillarity), often used when modeling evaporating droplets. These deviations can be seen in two ways. Namely, either the droplet appears to be inflated as compared to the classical static shape assuming the same contact angle and contact radius, or the apparent contact angle appears lower than the classical static one assuming the same volume and contact radius. In reality, the experimental profiles exhibit a local decrease of the slope near the contact line, which we attribute to the Marangoni effect in an evaporating sessile droplet. In this case, the radially inward (along the liquid-air interface) direction of the flow delivers more liquid to the center of the droplet making it appear inflated. When the Marangoni effect is weak, as in the case of the poorly volatile HFE-7500, no significant influence is noticed on the drop shape. The experimental results are compared with the predictions of a lubrication-type theoretical model that incorporates the evaporation-induced Marangoni flow. Financial support of FP7 Marie Curie MULTIFLOW Network (PITN-GA-2008-214919), ESA/BELSPO-PRODEX, BELSPO- μMAST (IAP 7/38) & FRS-FNRS is gratefully acknowledged.

  9. Experimental Study on the Combustion and Microexplosion of Freely Falling Gelled Unsymmetrical Dimethylhydrazine (UDMH Fuel Droplets

    Directory of Open Access Journals (Sweden)

    Jianjun Wu

    2012-08-01

    Full Text Available The increasing demand for high energy density fuels and the concern for their safety have propelled research in the field of gelled propellants, where understanding the combustion of single gelled fuel droplets is the first stage to predict the spray combustion characteristics. The experiments utilized single-isolated freely falling gelled unsymmetrical dimethylhydrazine (UDMH droplets instead of the conventional suspended droplet approach, in order to eliminate the perturbation associated with the suspension mechanism. Morphological transformations of the gelled droplet involved in the combustion processes were monitored by employing a high-speed digital camera, while the effects of ambient pressure and oxygen concentration on burning rate constants were also studied. The experimental results show that four main phenomena (droplet deformation, bubble formation and growth, vapor jetting and luminous jetting flame with “horn” shape and three distinct phases were identified in the droplet combustion process; the high yield stress and polymer chain structure of polymer gellant are responsible for the appearance of bubbles with almost the same order of magnitude as the droplets. Increasing the ambient pressure can increase the burning rate, postpone the appearance of microexplosions, and weaken microexplosion intensity; while increasing the ambient oxygen concentration can promote the appearance of microexplosions, strengthen microexplosion intensity and increase the burning rate.

  10. Flexible Coupling of Respiration and Vocalizations with Locomotion and Head Movements in the Freely Behaving Rat.

    Science.gov (United States)

    Alves, Joseph Andrews; Boerner, Barbara Ciralli; Laplagne, Diego Andrés

    2016-01-01

    Quadrupedal mammals typically synchronize their respiration with body movements during rhythmic locomotion. In the rat, fast respiration is coupled to head movements during sniffing behavior, but whether respiration is entrained by stride dynamics is not known. We recorded intranasal pressure, head acceleration, instantaneous speed, and ultrasonic vocalizations from male and female adult rats while freely behaving in a social environment. We used high-speed video recordings of stride to understand how head acceleration signals relate to locomotion and developed techniques to identify episodes of sniffing, walking, trotting, and galloping from the recorded variables. Quantitative analysis of synchrony between respiration and head acceleration rhythms revealed that respiration and locomotion movements were coordinated but with a weaker coupling than expected from previous work in other mammals. We have recently shown that rats behaving in social settings produce high rates of ultrasonic vocalizations during locomotion bouts. Accordingly, rats emitted vocalizations in over half of the respiratory cycles during fast displacements. We present evidence suggesting that emission of these calls disrupts the entrainment of respiration by stride. The coupling between these two variables is thus flexible, such that it can be overridden by other behavioral demands.

  11. A wireless power transmission system for implantable devices in freely moving rodents.

    Science.gov (United States)

    Eom, Kyungsik; Jeong, Joonsoo; Lee, Tae Hyung; Kim, Jinhyung; Kim, Junghoon; Lee, Sung Eun; Kim, Sung June

    2014-08-01

    Reliable wireless power delivery for implantable devices in animals is highly desired for safe and effective experimental use. Batteries require frequent replacement; wired connections are inconvenient and unsafe, and short-distance inductive coupling requires the attachment of an exterior transmitter to the animal's body. In this article, we propose a solution by which animals with implantable devices can move freely without attachments. Power is transmitted using coils attached to the animal's cage and is received by a receiver coil implanted in the animal. For a three-dimensionally uniform delivery of power, we designed a columnar dual-transmitter coil configuration. A resonator-based inductive link was adopted for efficient long-range power delivery, and we used a novel biocompatible liquid crystal polymer substrate as the implantable receiver device. Using this wireless power delivery system, we obtain an average power transfer efficiency of 15.2% (minimum efficiency of 10% and a standard deviation of 2.6) within a cage of 15×20×15 cm3.

  12. Estimation of unsteady aerodynamics in the wake of a freely flying European starling (Sturnus vulgaris.

    Directory of Open Access Journals (Sweden)

    Hadar Ben-Gida

    Full Text Available Wing flapping is one of the most widespread propulsion methods found in nature; however, the current understanding of the aerodynamics in bird wakes is incomplete. The role of the unsteady motion in the flow and its contribution to the aerodynamics is still an open question. In the current study, the wake of a freely flying European starling has been investigated using long-duration high-speed Particle Image Velocimetry (PIV in the near wake. Kinematic analysis of the wings and body of the bird has been performed using additional high-speed cameras that recorded the bird movement simultaneously with the PIV measurements. The wake evolution of four complete wingbeats has been characterized through reconstruction of the time-resolved data, and the aerodynamics in the wake have been analyzed in terms of the streamwise forces acting on the bird. The profile drag from classical aerodynamics was found to be positive during most of the wingbeat cycle, yet kinematic images show that the bird does not decelerate. It is shown that unsteady aerodynamics are necessary to satisfy the drag/thrust balance by approximating the unsteady drag term. These findings may shed light on the flight efficiency of birds by providing a partial answer to how they minimize drag during flapping flight.

  13. Estimation of unsteady aerodynamics in the wake of a freely flying European starling

    CERN Document Server

    Ben-Gida, Hadar; Taylor, Zachary J; Bezner-Kerr, Wayne; Guglielmo, Christopher G; Kopp, Gregory A; Gurka, Roi

    2013-01-01

    Wing flapping is one of the most widespread propulsion methods found in nature; however, the current understanding of the aerodynamics in bird wakes is incomplete. The role of the unsteady motion in the flow and its contribution to the aerodynamics is still an open question. In the current study, the wake of a freely flying European starling has been investigated using long-duration high-speed Particle Image Velocimetry (PIV) in the near wake. Kinematic analysis of the wings and body of the bird has been performed using additional high-speed cameras that recorded the bird movement simultaneously with the PIV measurements. The wake evolution of four complete wingbeats has been characterized through reconstruction of the time resolved data, and the aerodynamics in the wake have been analyzed in terms of the streamwise forces acting on the bird. The profile drag from classical aerodynamics was found to be positive during most of the wingbeat cycle, yet kinematic images show that the bird does not decelerate. It ...

  14. On freely floating bodies trapping time-harmonic waves in water covered by brash ice

    CERN Document Server

    Kuznetsov, Nikolay

    2015-01-01

    A mechanical system consisting of water covered by brash ice and a body freely floating near equilibrium is considered. The water occupies a half-space into which an infinitely long surface-piercing cylinder is immersed, thus allowing us to study two-dimensional modes of the coupled motion which is assumed to be of small amplitude. The corresponding linear setting for time-harmonic oscillations reduces to a spectral problem whose parameter is the frequency. A constant that characterises the brash ice divides the set of frequencies into two subsets and the results obtained for each of these subsets are essentially different. For frequencies belonging to a finite interval adjacent to zero, the total energy of motion is finite and the equipartition of energy holds for the whole system. For every frequency from this interval, a family of motionless bodies trapping waves is constructed by virtue of the semi-inverse procedure. For sufficiently large frequencies outside of this interval, all solutions of finite ener...

  15. Effect of excitatory amino acids on serum TSH and thyroid hormone levels in freely moving rats.

    Science.gov (United States)

    Alfonso, M; Durán, R; Arufe, M C

    2000-01-01

    The actions of glutamate (L-Glu), and glutamate receptor agonists on serum thyroid hormones (T4 and T3) and TSH levels have been studied in conscious and freely moving adult male rats. The excitatory amino acids (EAA), L-Glu, N-methyl-D-aspartate (NMDA), kainic acid (KA) and domoic acid (Dom) were administered intraperitoneally. Blood samples were collected through a cannula implanted in the rats jugular 0--60 min after injection. Thyroid hormone concentrations were measured by enzyme immunoassay, and thyrotrophin (TSH) concentrations were determined by radioimmunoassay. The results showed that L-Glu (20 and 25 mg/kg) and NMDA (25 mg/kg) increased serum thyroxine (T4), triiodothyronine (T3) and TSH concentrations. Serum thyroid hormone levels increased 30 min after treatment, while serum TSH levels increased 5 min after i.p. administration, in both cases serum levels remained elevated during one hour. Injection of the non-NMDA glutamatergic agonists KA (30 mg/kg) and Dom (1 mg/kg) produced an increase in serum thyroid hormones and TSH levels. These results suggest the importance of EAAs in the regulation of hormone secretion from the pituitary-thyroid axis, as well as the importance of the NMDA and non-NMDA receptors in this stimulatory effect.

  16. Haloperidol-induced changes in neuronal activity in the striatum of the freely moving rat

    Directory of Open Access Journals (Sweden)

    Dorin eYael

    2013-12-01

    Full Text Available The striatum is the main input structure of the basal ganglia, integrating input from the cerebral cortex and the thalamus, which is modulated by midbrain dopaminergic input. Dopamine modulators, including agonists and antagonists, are widely used to relieve motor and psychiatric symptoms in a variety of pathological conditions. Haloperidol, a dopamine D2 antagonist, is commonly used in multiple psychiatric conditions and motor abnormalities. This article reports the effects of haloperidol on the activity of three major striatal subpopulations: medium spiny projection neurons (MSNs, fast spiking interneurons (FSIs and tonically active neurons (TANs. We implanted multi-wire electrode arrays in the rat dorsal striatum and recorded the activity of multiple single units in freely moving animals before and after systemic haloperidol injection. Haloperidol decreased the firing rate of FSIs and MSNs while increasing their tendency to fire in an oscillatory manner in the high voltage spindle (HVS frequency range of 7-9 Hz. Haloperidol led to an increased firing rate of TANs but did not affect their non-oscillatory firing pattern and their typical correlated firing activity. Our results suggest that dopamine plays a key role in tuning both single unit activity and the interactions within and between different subpopulations in the striatum in a differential manner. These findings highlight the heterogeneous striatal effects of tonic dopamine regulation via D2 receptors which potentially enable the treatment of diverse pathological states associated with basal ganglia dysfunction.

  17. Induction and imaging of photothrombotic stroke in conscious and freely moving rats

    Science.gov (United States)

    Lu, Hongyang; Li, Yao; Yuan, Lu; Li, Hangdao; Lu, Xiaodan; Tong, Shanbao

    2014-09-01

    In experimental stroke research, anesthesia is common and serves as a major reason for translational failure. Real-time cerebral blood flow (CBF) monitoring during stroke onset can provide important information for the prediction of brain injury; however, this is difficult to achieve in clinical practice due to various technical problems. We created a photothrombotic focal ischemic stroke model utilizing our self-developed miniature headstage in conscious and freely moving rats. In this model, a high spatiotemporal resolution imager using laser speckle contrast imaging technology was integrated to acquire real-time two-dimensional CBF information during thrombosis. The feasibility, stability, and reliability of the system were tested in terms of CBF, behavior, and T2-weighted magnetic resonance imaging (MRI) findings. After completion of occlusion, the CBF in the targeted cortex of the stroke group was reduced to 16±9% of the baseline value. The mean infarct volume measured by MRI 24 h postmodeling was 77±11 mm3 and correlated well with CBF (R2=0.74). This rodent model of focal cerebral ischemia and real-time blood flow imaging opens the possibility of performing various fundamental and translational studies on stroke without the influence of anesthetics.

  18. 3D-e-Chem-VM: Structural Cheminformatics Research Infrastructure in a Freely Available Virtual Machine.

    Science.gov (United States)

    McGuire, Ross; Verhoeven, Stefan; Vass, Márton; Vriend, Gerrit; de Esch, Iwan J P; Lusher, Scott J; Leurs, Rob; Ridder, Lars; Kooistra, Albert J; Ritschel, Tina; de Graaf, Chris

    2017-02-14

    3D-e-Chem-VM is an open source, freely available Virtual Machine ( http://3d-e-chem.github.io/3D-e-Chem-VM/ ) that integrates cheminformatics and bioinformatics tools for the analysis of protein-ligand interaction data. 3D-e-Chem-VM consists of software libraries, and database and workflow tools that can analyze and combine small molecule and protein structural information in a graphical programming environment. New chemical and biological data analytics tools and workflows have been developed for the efficient exploitation of structural and pharmacological protein-ligand interaction data from proteomewide databases (e.g., ChEMBLdb and PDB), as well as customized information systems focused on, e.g., G protein-coupled receptors (GPCRdb) and protein kinases (KLIFS). The integrated structural cheminformatics research infrastructure compiled in the 3D-e-Chem-VM enables the design of new approaches in virtual ligand screening (Chemdb4VS), ligand-based metabolism prediction (SyGMa), and structure-based protein binding site comparison and bioisosteric replacement for ligand design (KRIPOdb).

  19. Precession of a Freely Rotating Rigid Body Inelastic Relaxation in the Vicinity of Poles

    CERN Document Server

    Efroimsky, M

    1999-01-01

    When a solid body is freely rotating at an angular velocity ${\\bf \\Omega}$, the ellipsoid of constant angular momentum, in the space $\\Omega_1, \\Omega_2, \\Omega_3$, has poles corresponding to spinning about the minimal-inertia and maximal-inertia axes. The first pole may be considered stable if we neglect the inner dissipation, but becomes unstable if the dissipation is taken into account. This happens because the bodies dissipate energy when they rotate about any axis different from that of the maximal inertia. In the case of an oblate symmetrical body, the angular velocity describes a circular cone about the vector of (conserved) angular momentum. In the course of relaxation, the angle of this cone decreases, so that both the angular velocity and the maximal-inertia axis of the body align along the angular momentum. The generic case of an asymmetric body is far more involved. Even the symmetrical prolate body exhibits a sophisticated behaviour, because an infinitesimally small deviation of the body's shape ...

  20. Flexible Coupling of Respiration and Vocalizations with Locomotion and Head Movements in the Freely Behaving Rat

    Directory of Open Access Journals (Sweden)

    Joseph Andrews Alves

    2016-01-01

    Full Text Available Quadrupedal mammals typically synchronize their respiration with body movements during rhythmic locomotion. In the rat, fast respiration is coupled to head movements during sniffing behavior, but whether respiration is entrained by stride dynamics is not known. We recorded intranasal pressure, head acceleration, instantaneous speed, and ultrasonic vocalizations from male and female adult rats while freely behaving in a social environment. We used high-speed video recordings of stride to understand how head acceleration signals relate to locomotion and developed techniques to identify episodes of sniffing, walking, trotting, and galloping from the recorded variables. Quantitative analysis of synchrony between respiration and head acceleration rhythms revealed that respiration and locomotion movements were coordinated but with a weaker coupling than expected from previous work in other mammals. We have recently shown that rats behaving in social settings produce high rates of ultrasonic vocalizations during locomotion bouts. Accordingly, rats emitted vocalizations in over half of the respiratory cycles during fast displacements. We present evidence suggesting that emission of these calls disrupts the entrainment of respiration by stride. The coupling between these two variables is thus flexible, such that it can be overridden by other behavioral demands.

  1. Investigation of the freely available easy-to-use software 'EZR' for medical statistics.

    Science.gov (United States)

    Kanda, Y

    2013-03-01

    Although there are many commercially available statistical software packages, only a few implement a competing risk analysis or a proportional hazards regression model with time-dependent covariates, which are necessary in studies on hematopoietic SCT. In addition, most packages are not clinician friendly, as they require that commands be written based on statistical languages. This report describes the statistical software 'EZR' (Easy R), which is based on R and R commander. EZR enables the application of statistical functions that are frequently used in clinical studies, such as survival analyses, including competing risk analyses and the use of time-dependent covariates, receiver operating characteristics analyses, meta-analyses, sample size calculation and so on, by point-and-click access. EZR is freely available on our website (http://www.jichi.ac.jp/saitama-sct/SaitamaHP.files/statmed.html) and runs on both Windows (Microsoft Corporation, USA) and Mac OS X (Apple, USA). This report provides instructions for the installation and operation of EZR.

  2. Whole-brain calcium imaging with cellular resolution in freely behaving Caenorhabditis elegans

    Science.gov (United States)

    Nguyen, Jeffrey; Shipley, Frederick; Linder, Ashley; Plummer, George; Liu, Mochi; Setru, Sagar; Shaevitz, Joshua; Leifer, Andrew

    The ability to acquire large-scale recordings of neuronal activity in awake and unrestrained animals is needed to provide new insights into how populations of neurons generate animal behavior. Acquiring this data, however, is challenging because it is difficult to track and image individual neurons as an animal deforms its posture and moves many body lengths. Here, we present an instrument capable of recording intracellular calcium transients from the majority of neurons in the head of a freely behaving Caenorhabditis elegans with cellular resolution while simultaneously recording the animal's position, posture, and locomotion. 3D volumetric fluorescent images of neurons expressing the calcium indicator GCaMP6s are recorded at 6 head-volumes/s using spinning disk confocal microscopy. At the same time, we record low magnification images of the animal to measure the animals behavior and track its head as it moves. We develop a time independent neuronal matching algorithm that uses non-rigid point set registration and machine learning to correctly match neurons across time. Using this method, we are able to observe calcium transients from up to 90 neurons for over 4 min and correlate the neural activity with the animal's behavior.

  3. Formation of density singularities in hydrodynamics of freely cooling inelastic gases: a family of exact solutions

    CERN Document Server

    Fouxon, Itzhak; Assaf, Michael; Livne, Eli

    2007-01-01

    We employ granular hydrodynamics to investigate a paradigmatic problem of clustering of particles in a freely cooling dilute granular gas. We consider large-scale hydrodynamic motions where the viscosity and heat conduction can be neglected, and one arrives at the equations of ideal gas dynamics with an additional term describing bulk energy losses due to inelastic collisions. We employ Lagrangian coordinates and derive a broad family of exact non-stationary analytical solutions that depend only on one spatial coordinate. These solutions exhibit a new type of singularity, where the gas density blows up in a finite time when starting from smooth initial conditions. The density blowups signal formation of close-packed clusters of particles. As the density blow-up time $t_c$ is approached, the maximum density exhibits a power law $\\sim (t_c-t)^{-2}$. The velocity gradient blows up as $\\sim - (t_c-t)^{-1}$ while the velocity itself remains continuous and develops a cusp (rather than a shock discontinuity) at the ...

  4. 3D-e-Chem-VM: Structural Cheminformatics Research Infrastructure in a Freely Available Virtual Machine

    Science.gov (United States)

    2017-01-01

    3D-e-Chem-VM is an open source, freely available Virtual Machine (http://3d-e-chem.github.io/3D-e-Chem-VM/) that integrates cheminformatics and bioinformatics tools for the analysis of protein–ligand interaction data. 3D-e-Chem-VM consists of software libraries, and database and workflow tools that can analyze and combine small molecule and protein structural information in a graphical programming environment. New chemical and biological data analytics tools and workflows have been developed for the efficient exploitation of structural and pharmacological protein–ligand interaction data from proteomewide databases (e.g., ChEMBLdb and PDB), as well as customized information systems focused on, e.g., G protein-coupled receptors (GPCRdb) and protein kinases (KLIFS). The integrated structural cheminformatics research infrastructure compiled in the 3D-e-Chem-VM enables the design of new approaches in virtual ligand screening (Chemdb4VS), ligand-based metabolism prediction (SyGMa), and structure-based protein binding site comparison and bioisosteric replacement for ligand design (KRIPOdb). PMID:28125221

  5. Mutation databases for inherited renal disease: are they complete, accurate, clinically relevant, and freely available?

    Science.gov (United States)

    Savige, Judy; Dagher, Hayat; Povey, Sue

    2014-07-01

    This study examined whether gene-specific DNA variant databases for inherited diseases of the kidney fulfilled the Human Variome Project recommendations of being complete, accurate, clinically relevant and freely available. A recent review identified 60 inherited renal diseases caused by mutations in 132 genes. The disease name, MIM number, gene name, together with "mutation" or "database," were used to identify web-based databases. Fifty-nine diseases (98%) due to mutations in 128 genes had a variant database. Altogether there were 349 databases (a median of 3 per gene, range 0-6), but no gene had two databases with the same number of variants, and 165 (50%) databases included fewer than 10 variants. About half the databases (180, 54%) had been updated in the previous year. Few (77, 23%) were curated by "experts" but these included nine of the 11 with the most variants. Even fewer databases (41, 12%) included clinical features apart from the name of the associated disease. Most (223, 67%) could be accessed without charge, including those for 50 genes (40%) with the maximum number of variants. Future efforts should focus on encouraging experts to collaborate on a single database for each gene affected in inherited renal disease, including both unpublished variants, and clinical phenotypes. © 2014 WILEY PERIODICALS, INC.

  6. Effects of 4 multitargeted receptor tyrosine kinase inhibitors on regional hemodynamics in conscious, freely moving rats

    Science.gov (United States)

    Carter, Joanne J.; Fretwell, Laurice V.; Woolard, Jeanette

    2017-01-01

    VEGF inhibitors, including receptor tyrosine kinase inhibitors, are used as adjunct therapies in a number of cancer treatments. An emerging issue with these drugs is that most cause hypertension. To gain insight into the physiological mechanisms involved, we evaluated their regional hemodynamic effects in conscious rats. Male Sprague Dawley rats (350–450 g) were chronically implanted with pulsed Doppler flow probes (renal and mesenteric arteries, and the descending abdominal aorta) and catheters (jugular vein, peritoneal cavity, and distal abdominal aorta). Regional hemodynamics were measured over 4 d, before and after daily administration of cediranib (3 and 6 mg/kg, 3 and 6 mg/kg/h for 1 h, i.v.), sorafenib (10 and 20 mg/kg, 10 and 20 mg kg/h for 1 h, i.v.), pazopanib (30 and100 mg/kg, i.p.), or vandetanib (12.5 and 25 mg/kg, i.p.). All drugs evoked significant increases (P phentolamine and propranolol (each 1 mg/kg/h), suggesting a need for new strategies to overcome them.—Carter, J. J., Fretwell, L. V., Woolard, J. Effects of 4 multitargeted receptor tyrosine kinase inhibitors on regional hemodynamics in conscious, freely moving rats. PMID:27986807

  7. Combined optical sizing and acoustical characterization of single freely-floating microbubbles

    Science.gov (United States)

    Luan, Ying; Renaud, Guillaume; Raymond, Jason L.; Segers, Tim; Lajoinie, Guillaume; Beurskens, Robert; Mastik, Frits; Kokhuis, Tom J. A.; van der Steen, Antonius F. W.; Versluis, Michel; de Jong, Nico

    2016-12-01

    In this study we present a combined optical sizing and acoustical characterization technique for the study of the dynamics of single freely-floating ultrasound contrast agent microbubbles exposed to long burst ultrasound excitations up to the milliseconds range. A co-axial flow device was used to position individual microbubbles on a streamline within the confocal region of three ultrasound transducers and a high-resolution microscope objective. Bright-field images of microbubbles passing through the confocal region were captured using a high-speed camera synchronized to the acoustical data acquisition to assess the microbubble response to a 1-MHz ultrasound burst. Nonlinear bubble vibrations were identified at a driving pressure as low as 50 kPa. The results demonstrate good agreement with numerical simulations based on the shell-buckling model proposed by Marmottant et al. [J. Acoust. Soc. Am. 118, 3499-3505 (2005)]. The system demonstrates the potential for a high-throughput in vitro characterization of individual microbubbles.

  8. From viscous to elastic sheets: Dynamics of smectic freely floating films

    Science.gov (United States)

    Harth, Kirsten; May, Kathrin; Trittel, Torsten; Stannarius, Ralf

    2015-03-01

    Oscillations and rupture of bubbles, composed of an inner fluid separated from an outer fluid by a membrane, represent an old but still immensely active field of research. Membrane properties except surface tension are often neglected for simple fluid films (e.g. soap bubbles), whereas they govern the dynamics in systems with more complex membranes (e.g. vesicles). Due to their layered phase structure, smectic liquid crystals can form stable, uniform and easy-to handle fluid films of immense aspect ratios. Recently, freely floating bubbles detached from a support were prepared. We analyze the relaxation from strongly non-spherical shapes and the rupture dynamics of such bubbles using high-speed video recordings. Peculiar dynamics intermediate between those of simple viscous fluid films and an elastic response emerge: Oscillations, slowed relaxation and even the formation of wrinkles and extrusions. We characterize these phenomena and propose explanations. We acknowledge funding by the German Aerospace Center DLR within Project OASIS-CO and German Science Foundation Project STA 425-28.

  9. Electric sail, photonic sail and deorbiting applications of the freely guided photonic blade

    CERN Document Server

    Janhunen, P

    2013-01-01

    We consider a freely guided photonic blade (FGPB) which is a centrifugally stretched sheet of photonic sail membrane that can be tilted by changing the centre of mass or by other means. The FGPB can be installed at the tip of each main tether of an electric solar wind sail (E-sail) so that one can actively manage the tethers to avoid their mutual collisions and to modify the spin rate of the sail if needed. This enables a more scalable and modular E-sail than the baseline approach where auxiliary tethers are used for collision avoidance. For purely photonic sail applications one can remove the tethers and increase the size of the blades to obtain a novel variant of the heliogyro that can have a significantly higher packing density than the traditional heliogyro. For satellite deorbiting in low Earth orbit (LEO) conditions, analogous designs exist where the E-sail effect is replaced by the negative polarity plasma brake effect and the photonic pressure by atmospheric drag. We conclude that the FGPB appears to ...

  10. Corrosion Behavior of Cast Iron in Freely Aerated Stagnant Arabian Gulf Seawater

    Science.gov (United States)

    Sherif, El-Sayed M.; Abdo, Hany S.; Almajid, Abdulhakim A.

    2015-01-01

    In this work, the results obtained from studying the corrosion of cast iron in freely aerated stagnant Arabian Gulf seawater (AGS) at room temperature were reported. The study was carried out using weight-loss (WL), cyclic potentiodynamic polarization (CPP), open-circuit potential (OCP), and electrochemical impedance spectroscopy (EIS) measurements and complemented by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) investigations. WL experiments between two and 10 days’ immersion in the test electrolyte indicated that the weight-loss the cast iron increases with increasing the time of immersion. CPP measurements after 1 h and 24 h exposure period showed that the increase of time decreases the corrosion via decreasing the anodic and cathodic currents, as well as decreasing the corrosion current and corrosion rate and increasing the polarization resistance of the cast iron. EIS data confirmed the ones obtained by WL and CPP that the increase of immersion time decreases the corrosion of cast iron by increasing its polarization resistance.

  11. Enhanced migration of seismic data

    Energy Technology Data Exchange (ETDEWEB)

    Carrion, P.M. (PPPG/UFBA, Instituto de Geociencias, Rua Gaetano Moura 123, Federacao, 40.210 Salvador, Bahia (BR))

    1990-10-01

    The so-called enhanced migration which uses diffraction tomography as the repair tool for correction of amplitudes (reflection coefficients) of migrated sections is discussed. As with any linearized procedure, diffraction tomography requires knowledge of the initial model. It is suggested that the initial model is taken as the migrated image. It will be demonstrated that diffraction tomography applied to the data residuals improves the amplitudes of the migrated images. Migration is redefined as the reconstruction of the wavefront sets of distributions (reflection interfaces), and the inversion process as tomographic correction of migrated images.

  12. 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.

  13. A new minimal-stress freely-moving rat model for preclinical studies on intranasal administration of CNS drugs

    NARCIS (Netherlands)

    Stevens, Jasper; Suidgeest, Ernst; van der Graaf, Piet Hein; Danhof, Meindert; de Lange, Elizabeth C M

    2009-01-01

    PURPOSE: To develop a new minimal-stress model for intranasal administration in freely moving rats and to evaluate in this model the brain distribution of acetaminophen following intranasal versus intravenous administration. METHODS: Male Wistar rats received one intranasal cannula, an intra-cerebra

  14. Strong activation of vascular prejunctional beta 2-adrenoceptors in freely moving rats by adrenaline released as a co-transmitter

    NARCIS (Netherlands)

    COPPES, RP; SMIT, J; KHALI, NN; Brouwer, F.; ZAAGSMA, J

    1993-01-01

    The effect of adrenaline on the electrically evoked noradrenaline overflow in the portal vein of adrenal demedullated freely moving rats was studied. Adrenaline (100 ng/min) was infused for 2 h into the portal vein. After a 1-h interval when plasma adrenaline had returned to pre-infusion undetectabl

  15. Effects of dissolved organic matter from a eutrophic lake on the freely dissolved concentrations of emerging organic contaminants.

    Science.gov (United States)

    Xiao, Yi-Hua; Huang, Qing-Hui; Vähätalo, Anssi V; Li, Fei-Peng; Chen, Ling

    2014-08-01

    The authors studied the effects of dissolved organic matter (DOM) on the bioavailability of bisphenol A (BPA) and chloramphenicol by measuring the freely dissolved concentrations of the contaminants in solutions containing DOM that had been isolated from a mesocosm in a eutrophic lake. The abundance and aromaticity of the chromophoric DOM increased over the 25-d mesocosm experiment. The BPA freely dissolved concentration was 72.3% lower and the chloramphenicol freely dissolved concentration was 56.2% lower using DOM collected on day 25 than using DOM collected on day 1 of the mesocosm experiment. The freely dissolved concentrations negatively correlated with the ultraviolent absorption coefficient at 254 nm and positively correlated with the spectral slope of chromophoric DOM, suggesting that the bioavailability of these emerging organic contaminants depends on the characteristics of the DOM present. The DOM-water partition coefficients (log KOC ) for the emerging organic contaminants positively correlated with the aromaticity of the DOM, measured as humic acid-like fluorescent components C1 (excitation/emission=250[313]/412 nm) and C2 (excitation/emission=268[379]/456 nm). The authors conclude that the bioavailability of emerging organic contaminants in eutrophic lakes can be affected by changes in the DOM.

  16. Nutritional requirements for methyl orange decolourisation by freely suspended cells and growing cells of Lactobacillus casei TISTR 1500

    Directory of Open Access Journals (Sweden)

    Phisit Seesuriyachan

    2011-01-01

    Full Text Available Lactobacillus casei TISTR 1500 possesses cytoplasmic azoreductase and can breakdown azo bonds under microaerophilic condition. It was found previously that a growing culture is more tolerant to a high initial dye concentration than freely suspended cells supplied only with sucrose. The present study is aimed at investigating the nutritive requirements for decolourisation by the growing cells and the freely suspended cells using Plackett-Burmann experimental design. In this study, the composition of the medium was found to play an important role in methyl orange decolourisation and biomass production. Sucrose, meat extract and peptone increased methyl orange decolourisation by freely suspended cells, whereas sodium acetate exerted a negative effect on decolourisation. In addition, it was observed that the yeast and meat extracts enhanced the degradation of the dye by the growing cells. Sucrose was an important factor in biomass production by freely suspended cells and growing cells. On the other hand, dipotassium hydrogen phosphate and sodium acetate decreased the biomass production. These findings promote the understanding and knowledge about the requirements of azo dye decolourisation by Lactobacillus casei.

  17. Analyzing freely dissolved concentrations of cationic surfactant utilizing ion-exchange capability of polyacrylate coated solid-phase microextraction fibers

    NARCIS (Netherlands)

    Chen, Y.; Droge, S.T.J.; Hermens, J.L.M.

    2012-01-01

    A 7-μm polyacrylate (PA) coated fiber was successfully employed to determine freely dissolved concentrations of cationic surfactants by solid-phase microextraction (SPME) and utilizing the capability of the PA-coating to sorb organic cations via ion-exchange at carboxylic groups. Measured fiber-wate

  18. 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.

  19. 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...

  20. 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...

  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. Migration as Adventure

    DEFF Research Database (Denmark)

    Olwig, Karen Fog

    2017-01-01

    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...

  3. 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...

  4. Migration as Adventure

    DEFF Research Database (Denmark)

    Olwig, Karen Fog

    2017-01-01

    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...

  5. 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

  6. 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...

  7. Describing migration spatial structure

    NARCIS (Netherlands)

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

    2002-01-01

    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 d

  8. 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

  9. World Migration Degree Global migration flows in directed networks

    OpenAIRE

    2015-01-01

    In this article we analyze the global flow of migrants from 206 source countries to 145 destination countries (2006-2010) and focus on the differences in the migration network pattern between destination and source counters as represented by its degree and weight distribution. Degree represents the connectivity of a country to the global migration network, and plays an important role in defining migration processes and characteristics. Global analysis of migration degree distribution offers a...

  10. Defects in germinal center selection in SLE

    Directory of Open Access Journals (Sweden)

    Megan eWoods

    2015-08-01

    Full Text Available Germinal centers (GCs are the primary site at which clonal expansion and affinity maturation of B cells occurs. B cells encounter antigen and receive T cell help in the GC light zone (LZ and then migrate to the dark zone where they proliferate and undergo somatic mutation before cycling back to the LZ for further rounds of selection. Tolerance to autoantigens is frequently lost de novo as GC B cells undergo class switching and somatic mutation. This loss of tolerance is regulated by a variety of mechanisms including cell death, failure to compete for T cell help and failure to differentiate into effector cells. Systemic Lupus Erythematosus (SLE is characterized by loss of tolerance to nucleic acid antigens. While defects in tolerance occur in the naïve repertoire of SLE patients, pathogenic autoantibodies also arise in the GC as a result of failure to exclude autoreactive B cells from the GC and by somatic mutation from non-autoreactive precursors. Several B cell defects contribute to the loss of GC tolerance in SLE, including polymorphisms of genes that regulate BCR signaling, excess TLR7 signaling, defects in FcRIIB expression or defects of B cell apoptosis. Extrinsic soluble factors such as Type1 IFN or an imbalance between the number of TFH cells and regulatory T cells in the GC can also alter B cell negative selection. Finally, defects in macrophage clearance of apoptotic debris within the GC result in BCR mediated internalization of nucleic acid containing material and stimulation of autoantibody production by endosomal TLR driven mechanisms.

  11. The International Organization for Migration in Global Migration Governance

    OpenAIRE

    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.

  12. 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

  13. Quantum-chemical approach to defect formation processes in non-metallic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kotomin, E.A.; Shluger, A.L. (Latvijskij Gosudarstvennyj Univ., Riga (USSR))

    1989-01-01

    Results of the quantum-chemical simulation of the formation of structural and radiation defects are reviewed, using ice, silicon, and silicon dioxide as examples. The relationship between the structural elements of these crystals and the structural defects is analysed. Models of the main defects, their optical characteristics, and the activation energy of their migration are discussed. The relationship between the characteristics obtained by quantum-chemical calculations and the parameters of the macroscopic kinetics of the processes induced by defects in dielectric crystals is considered. (author).

  14. Norwegian Pitched Roof Defects

    Directory of Open Access Journals (Sweden)

    Lars Gullbrekken

    2016-06-01

    Full Text Available The building constructions investigated in this work are pitched wooden roofs with exterior vertical drainpipes and wooden load-bearing system. The aim of this research is to further investigate the building defects of pitched wooden roofs and obtain an overview of typical roof defects. The work involves an analysis of the building defect archive from the research institute SINTEF Building and Infrastructure. The findings from the SINTEF archive show that moisture is a dominant exposure factor, especially in roof constructions. In pitched wooden roofs, more than half of the defects are caused by deficiencies in design, materials, or workmanship, where these deficiencies allow moisture from precipitation or indoor moisture into the structure. Hence, it is important to increase the focus on robust and durable solutions to avoid defects both from exterior and interior moisture sources in pitched wooden roofs. Proper design of interior ventilation and vapour retarders seem to be the main ways to control entry from interior moisture sources into attic and roof spaces.

  15. Silicon, germanium, and their alloys growth, defects, impurities, and nanocrystals

    CERN Document Server

    Kissinger, Gudrun

    2014-01-01

    ""This book gives the state of the art in understanding and tailoring point defects in group IV semiconductors. The reader will find useful and complete information about the mechanisms of formation, migration, and interaction of intrinsic and extrinsic point defects in Si, Ge, and SiGe alloys. This is a unique feature of this work, as it offers the possibility of comparing the peculiar behavior of Si, Ge, and related alloys under one single cover.""-Professor Roberto Fornari, Department of Physics and Earth Sciences, University of Parma, Italy""This book describes the g

  16. Extended point defects in crystalline materials: Ge and Si.

    Science.gov (United States)

    Cowern, N E B; Simdyankin, S; Ahn, C; Bennett, N S; Goss, J P; Hartmann, J-M; Pakfar, A; Hamm, S; Valentin, J; Napolitani, E; De Salvador, D; Bruno, E; Mirabella, S

    2013-04-12

    B diffusion measurements are used to probe the basic nature of self-interstitial point defects in Ge. We find two distinct self-interstitial forms--a simple one with low entropy and a complex one with entropy ∼30  k at the migration saddle point. The latter dominates diffusion at high temperature. We propose that its structure is similar to that of an amorphous pocket--we name it a morph. Computational modeling suggests that morphs exist in both self-interstitial and vacancylike forms, and are crucial for diffusion and defect dynamics in Ge, Si, and probably many other crystalline solids.

  17. An Overview of the Mechanisms of Abnormal GABAergic Interneuronal Cortical Migration Associated with Prenatal Ethanol Exposure.

    Science.gov (United States)

    Shenoda, Botros B

    2017-02-03

    GABAergic Interneuronal migration constitutes an essential process during corticogenesis. Derived from progenitor cells located in the proliferative zones of the ventral telencephalon, newly generated GABAergic Interneuron migrate to their cortical destinations. Cortical dysfunction associated with defects in neuronal migration results in severe developmental consequences. There is growing evidence linking prenatal ethanol exposure to abnormal GABAergic interneuronal migration and subsequent cortical dysfunction. Investigating the pathophysiological mechanisms behind disrupted GABAergic interneuronal migration encountered with prenatal alcohol exposure is crucial for understanding and managing fetal alcohol spectrum disorders. This review explores the molecular pathways regulating GABAergic interneuronal cortical migration that might be altered by prenatal ethanol exposure thus opening new avenues for further research in this topic.

  18. CHARACTERISTICS OF MIGRATION IN ROMANIA

    Directory of Open Access Journals (Sweden)

    Daniela DĂNĂCICĂ

    2010-06-01

    Full Text Available The aim of this research is to study the patterns of migration in Romania. Labor migration in Romania has seen major growth after 1989. Permanent migration rapidly increased in the early years after the revolution, decreasing rapidly thereafter, due to difficulties of obtaining long term residence and work permit in the host countries. However, temporary migration has been found to evolve very dynamically, requiring economic analysis of potential externalities, whether positive or the negative of this phenomenon.

  19. CHARACTERISTICS OF MIGRATION IN ROMANIA

    OpenAIRE

    Daniela DĂNĂCICĂ

    2010-01-01

    The aim of this research is to study the patterns of migration in Romania. Labor migration in Romania has seen major growth after 1989. Permanent migration rapidly increased in the early years after the revolution, decreasing rapidly thereafter, due to difficulties of obtaining long term residence and work permit in the host countries. However, temporary migration has been found to evolve very dynamically, requiring economic analysis of potential externalities, whet...

  20. Evaluation of freely available ancillary data used for detailed soil mapping in Brazil

    Science.gov (United States)

    Samuel-Rosa, Alessandro; Anjos, Lúcia; Vasques, Gustavo; Heuvelink, Gerard

    2014-05-01

    Brazil is one of the world's largest food producers, and is home of both largest rainforest and largest supply of renewable fresh water on Earth. However, it lacks detailed soil information in extensive areas of the country. The best soil map covering the entire country was published at a scale of 1:5,000,000. Termination of governmental support for systematic soil mapping in the 1980's made detailed soil mapping of the whole country a very difficult task to accomplish. Nowadays, due to new user-driven demands (e.g. precision agriculture), most detailed soil maps are produced for small size areas. Many of them rely on as is freely available ancillary data, although their accuracy is usually not reported or unknown. Results from a validation exercise that we performed using ground control points from a small hilly catchment (20 km²) in Southern Brazil (-53.7995ºE, -29.6355ºN) indicate that most freely available ancillary data needs some type of correction before use. Georeferenced and orthorectified RapidEye imagery (recently acquired by the Brazilian government) has a horizontal accuracy (root-mean-square error, RMSE) of 37 m, which is worse than the value published in the metadata (32 m). Like any remote sensing imagery, RapidEye imagery needs to be correctly registered before its use for soil mapping. Topographic maps produced by the Brazilian Army and derived geological maps (scale of 1:25,000) have a horizontal accuracy of 65 m, which is more than four times the maximum value allowed by Brazilian legislation (15 m). Worse results were found for geological maps derived from 1:50,000 topographic maps (RMSE = 147 m), for which the maximum allowed value is 30 m. In most cases positional errors are of systematic origin and can be easily corrected (e.g., affine transformation). ASTER GDEM has many holes and is very noisy, making it of little use in the studied area. TOPODATA, which is SRTM kriged from originally 3 to 1 arc-second by the Brazilian National

  1. Discrete torsion defects

    CERN Document Server

    Brunner, Ilka; Plencner, Daniel

    2014-01-01

    Orbifolding two-dimensional quantum field theories by a symmetry group can involve a choice of discrete torsion. We apply the general formalism of `orbifolding defects' to study and elucidate discrete torsion for topological field theories. In the case of Landau-Ginzburg models only the bulk sector had been studied previously, and we re-derive all known results. We also introduce the notion of `projective matrix factorisations', show how they naturally describe boundary and defect sectors, and we further illustrate the efficiency of the defect-based approach by explicitly computing RR charges. Roughly half of our results are not restricted to Landau-Ginzburg models but hold more generally, for any topological field theory. In particular we prove that for a pivotal bicategory, any two objects of its orbifold completion that have the same base are orbifold equivalent. Equivalently, from any orbifold theory (including those based on nonabelian groups) the original unorbifolded theory can be be obtained by orbifo...

  2. Mask Blank Defect Detection

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, M A; Sommargren, G E

    2000-02-04

    Mask blanks are the substrates that hold the master patterns for integrated circuits. Integrated circuits are semiconductor devices, such as microprocessors (mPs), dynamic random access memory (DRAMs), and application specific integrated circuits (ASICs) that are central to the computer, communication, and electronics industries. These devices are fabricated using a set of master patterns that are sequentially imaged onto light-sensitive coated silicon wafers and processed to form thin layers of insulating and conductive materials on top of the wafer. These materials form electrical paths and transistors that control the flow of electricity through the device. For the past forty years the semiconductor industry has made phenomenal improvements in device functionality, compactness, speed, power, and cost. This progress is principally due to the exponential decrease in the minimum feature size of integrated circuits, which has been reduced by a factor of {radical}2 every three years. Since 1992 the Semiconductor Industry Association (SIA) has coordinated the efforts of producing a technology roadmap for semiconductors. In the latest document, ''The International Technology Roadmap for Semiconductors: 1999'', future technology nodes (minimum feature sizes) and targeted dates were specified and are summarized in Table 1. Lithography is the imaging technology for producing a de-magnified image of the mask on the wafer. A typical de-magnification factor is 4. Mask blank defects as small as one-eighth the equivalent minimum feature size are printable and may cause device failure. Defects might be the result of the surface preparation, such as polishing, or contamination due to handling or the environment. Table 2 shows the maximum tolerable defect sizes on the mask blank for each technology node. This downward trend puts a tremendous burden on mask fabrication, particularly in the area of defect detection and reduction. A new infrastructure for mask

  3. Imaging the Dynamics of Neocortical Population Activity in Behaving and Freely Moving Mammals.

    Science.gov (United States)

    Grinvald, Amiram; Petersen, Carl C H

    2015-01-01

    The development of functional imaging techniques applicable to neuroscience and covering a wide range of spatial and temporal scales has greatly facilitated the exploration of the relationships between cognition, behaviour and electrical brain activity. For mammals, the neocortex plays a particularly profound role in generating sensory perception, controlling voluntary movement, higher cognitive functions and planning goal-directed behaviours. Since these remarkable functions of the neocortex cannot be explored in simple model preparations or in anesthetised animals, the neural basis of behaviour must be explored in awake behaving subjects. Because neocortical function is highly distributed across many rapidly interacting regions, it is essential to measure spatiotemporal dynamics of cortical activity in real-time. Extensive work in anesthetised mammals has shown that in vivo Voltage-Sensitive Dye Imaging (VSDI) reveals the neocortical population membrane potential dynamics at millisecond temporal resolution and subcolumnar spatial resolution. Here, we describe recent advances indicating that VSDI is also already well-developed for exploring cortical function in behaving monkeys and mice. The first animal model, the non-human primate, is well-suited for fundamental exploration of higher-level cognitive function and behavior. The second animal model, the mouse, benefits from a rich arsenal of molecular and genetic technologies. In the monkey, imaging from the same patch of cortex, repeatedly, is feasible for a long period of time, up to a year. In the rodent, VSDI is applicable to freely moving and awake head-restrained mice. Interactions between different cortical areas and different cortical columns can therefore now be dynamically mapped through VSDI and related to the corresponding behaviour. Thus by applying VSDI to mice and monkeys one can begin to explore how behaviour emerges from neuronal activity in neuronal networks residing in different cortical areas.

  4. An implantable device for neuropsychiatric rehabilitation by chronic deep brain stimulation in freely moving rats

    Science.gov (United States)

    Wang, Chenguang; Zhang, Fuqiang; Jia, Hong

    2017-01-01

    Successful practice of clinical deep brain stimulation (DBS) calls for basic research on the mechanisms and explorations of new indications in animals. In the article, a new implantable, single-channel, low-power miniature device is proposed, which may transmit pulses chronically into the brain nucleus of freely moving rats. The DBS system consists of an implantable pulse generator (IPG), a bipolar electrode, and an external programmer. The IPG circuit module is assembled as a 20-mm diameter circular board and fixed on a rat’s skull together with an electrode and battery. The rigid electrode may make its fabrication and implantation more easy. The external programmer is designed for bidirectional communication with the IPG by a telecontrol transceiver and adjusts stimulation parameters. A biological validation was performed in which the effects of electrical stimulation in brain nucleus accumbens were detected. The programmed parameters were accurate, implant steady, and power sufficient to allow stimulation for more than 3 months. The larger area of the electrode tip provided a moderate current or charge density and minimized the damage from electrochemistry and pyroelectricity. The rats implanted with the device showed a reduction in morphine-induced conditioned place preference after high-frequency stimulation. In conclusion, the DBS device is based on the criteria of simple technology, minimal invasion, low cost, small in size, light-weight, and wireless controlled. This shows that our DBS device is appropriate and can be used for preclinical studies, indicating its potential utility in the therapy and rehabilitation of neuropsychiatric disorders. PMID:28121810

  5. Head-mounted LED for optogenetic experiments of freely-behaving animal

    Science.gov (United States)

    Kwon, Ki Yong; Gnade, Andrew G.; Rush, Alexander D.; Patten, Craig D.

    2016-03-01

    Recent developments in optogenetics have demonstrated the ability to target specific types of neurons with sub-millisecond temporal precision via direct optical stimulation of genetically modified neurons in the brain. In most applications, the beam of a laser is coupled to an optical fiber, which guides and delivers the optical power to the region of interest. Light emitting diodes (LEDs) are an alternative light source for optogenetics and they provide many advantages over a laser based system including cost, size, illumination stability, and fast modulation. Their compact size and low power consumption make LEDs suitable light sources for a wireless optogenetic stimulation system. However, the coupling efficiency of an LED's output light into an optical fiber is lower than a laser due to its noncollimated output light. In typical chronic optogenetic experiment, the output of the light source is transmitted to the brain through a patch cable and a fiber stub implant, and this configuration requires two fiber-to-fiber couplings. Attenuation within the patch cable is potential source of optical power loss. In this study, we report and characterize a recently developed light delivery method for freely-behaving animal experiments. We have developed a head-mounted light source that maximizes the coupling efficiency of an LED light source by eliminating the need for a fiber optic cable. This miniaturized LED is designed to couple directly to the fiber stub implant. Depending on the desired optical power output, the head-mounted LED can be controlled by either a tethered (high power) or battery-powered wireless (moderate power) controller. In the tethered system, the LED is controlled through 40 gauge micro coaxial cable which is thinner, more flexible, and more durable than a fiber optic cable. The battery-powered wireless system uses either infrared or radio frequency transmission to achieve real-time control. Optical, electrical, mechanical, and thermal

  6. Effects of a ketogenic diet on hippocampal plasticity in freely moving juvenile rats.

    Science.gov (United States)

    Blaise, J Harry; Ruskin, David N; Koranda, Jessica L; Masino, Susan A

    2015-05-01

    Ketogenic diets are low-carbohydrate, sufficient protein, high-fat diets with anticonvulsant activity used primarily as a treatment for pediatric epilepsy. The anticonvulsant mechanism is thought to involve elevating inhibition and/or otherwise limiting excitability in the brain. Such a mechanism, however, might also significantly affect normal brain activity and limit synaptic plasticity, effects that would be important to consider in the developing brain. To assess ketogenic diet effects on synaptic transmission and plasticity, electrophysiological recordings were performed at the perforant path/dentate gyrus synapse in awake, freely-behaving juvenile male rats. Electrodes were implanted 1 week prior to recording. Animals were fed regular chow or a ketogenic diet ad libitum for 3 weeks before recording. Although the ketogenic diet did not significantly alter baseline excitability (assessed by input-output curves) or short-term plasticity (using the paired-pulse ratio), it did reduce the magnitude of long-term potentiation at all poststimulation timepoints out to the last time measured (48 h). The results suggest an effect of ketogenic diet-feeding on the induction magnitude but not the maintenance of long-term potentiation. The lack of effect of the diet on baseline transmission and the paired-pulse ratio suggests a mechanism that limits excitation preferentially in conditions of strong stimulation, consonant with clinical reports in which the ketogenic diet alleviates seizures without a major impact on normal brain activity. Limiting plasticity in a seizure-susceptible network may limit seizure-induced epileptogenesis which may subserve the ongoing benefit of the ketogenic diet in epilepsy.

  7. A low-cost multichannel wireless neural stimulation system for freely roaming animals

    Science.gov (United States)

    Alam, Monzurul; Chen, Xi; Fernandez, Eduardo

    2013-12-01

    Objectives. Electrical stimulation of nerve tissue and recording of neural activity are the basis of many therapies and neural prostheses. Conventional stimulation systems have a number of practical limitations, especially in experiments involving freely roaming subjects. Our main objective was to develop a modular, versatile and inexpensive multichannel wireless system able to overcome some of these constraints. Approach. We have designed and implemented a new multichannel wireless neural stimulator based on commercial components. The system is small (2 cm × 4 cm × 0.5 cm) and light in weight (9 g) which allows it to be easily carried in a small backpack. To test and validate the performance and reliability of the whole system we conducted several bench tests and in vivo experiments. Main results. The performance and accuracy of the stimulator were comparable to commercial threaded systems. Stimulation sequences can be constructed on-the-fly with 251 selectable current levels (from 0 to 250 µA) with 1 µA step resolution. The pulse widths and intervals can be as long as 65 ms in 2 µs time resolution. The system covers approximately 10 m of transmission range in a regular laboratory environment and 100 m in free space (line of sight). Furthermore it provides great flexibility for experiments since it allows full control of the stimulator and the stimulation parameters in real time. When there is no stimulation, the device automatically goes into low-power sleep mode to preserve battery power. Significance. We introduce the design of a powerful multichannel wireless stimulator assembled from commercial components. Key features of the system are their reliability, robustness and small size. The system has a flexible design that can be modified straightforwardly to tailor it to any specific experimental need. Furthermore it can be effortlessly adapted for use with any kind of multielectrode arrays.

  8. Identification of behaviour in freely moving dogs (Canis familiaris using inertial sensors.

    Directory of Open Access Journals (Sweden)

    Linda Gerencsér

    Full Text Available Monitoring and describing the physical movements and body postures of animals is one of the most fundamental tasks of ethology. The more precise the observations are the more sophisticated the interpretations can be about the biology of a certain individual or species. Animal-borne data loggers have recently contributed much to the collection of motion-data from individuals, however, the problem of translating these measurements to distinct behavioural categories to create an ethogram is not overcome yet. The objective of the present study was to develop a "behaviour tracker": a system composed of a multiple sensor data-logger device (with a tri-axial accelerometer and a tri-axial gyroscope and a supervised learning algorithm as means of automated identification of the behaviour of freely moving dogs. We collected parallel sensor measurements and video recordings of each of our subjects (Belgian Malinois, N=12; Labrador Retrievers, N=12 that were guided through a predetermined series of standard activities. Seven behavioural categories (lay, sit, stand, walk, trot, gallop, canter were pre-defined and each video recording was tagged accordingly. Evaluation of the measurements was performed by support vector machine (SVM classification. During the analysis we used different combinations of independent measurements for training and validation (belonging to the same or different individuals or using different training data size to determine the robustness of the application. We reached an overall accuracy of above 90% perfect identification of all the defined seven categories of behaviour when both training and validation data belonged to the same individual, and over 80% perfect recognition rate using a generalized training data set of multiple subjects. Our results indicate that the present method provides a good model for an easily applicable, fast, automatic behaviour classification system that can be trained with arbitrary motion patterns and

  9. Identification of behaviour in freely moving dogs (Canis familiaris) using inertial sensors.

    Science.gov (United States)

    Gerencsér, Linda; Vásárhelyi, Gábor; Nagy, Máté; Vicsek, Tamas; Miklósi, Adam

    2013-01-01

    Monitoring and describing the physical movements and body postures of animals is one of the most fundamental tasks of ethology. The more precise the observations are the more sophisticated the interpretations can be about the biology of a certain individual or species. Animal-borne data loggers have recently contributed much to the collection of motion-data from individuals, however, the problem of translating these measurements to distinct behavioural categories to create an ethogram is not overcome yet. The objective of the present study was to develop a "behaviour tracker": a system composed of a multiple sensor data-logger device (with a tri-axial accelerometer and a tri-axial gyroscope) and a supervised learning algorithm as means of automated identification of the behaviour of freely moving dogs. We collected parallel sensor measurements and video recordings of each of our subjects (Belgian Malinois, N=12; Labrador Retrievers, N=12) that were guided through a predetermined series of standard activities. Seven behavioural categories (lay, sit, stand, walk, trot, gallop, canter) were pre-defined and each video recording was tagged accordingly. Evaluation of the measurements was performed by support vector machine (SVM) classification. During the analysis we used different combinations of independent measurements for training and validation (belonging to the same or different individuals or using different training data size) to determine the robustness of the application. We reached an overall accuracy of above 90% perfect identification of all the defined seven categories of behaviour when both training and validation data belonged to the same individual, and over 80% perfect recognition rate using a generalized training data set of multiple subjects. Our results indicate that the present method provides a good model for an easily applicable, fast, automatic behaviour classification system that can be trained with arbitrary motion patterns and potentially be

  10. Long-term potentiation at temporoammonic path-CA1 synapses in freely moving rats

    Directory of Open Access Journals (Sweden)

    Jossina eGonzalez

    2016-02-01

    Full Text Available Hippocampal area CA1 receives direct entorhinal layer III input via the temporoammonic path (TAP and recent studies implicate TAP-CA1 synapses are important for some aspects of hippocampal memory function. Nonetheless, as few studies have examined TAP-CA1 synaptic plasticity in vivo, the induction and longevity of TAP-CA1 long-term potentiation (LTP has not been fully characterized. We analyzed CA1 responses following stimulation of the medial aspect of the angular bundle and investigated LTP at medial temporoammonic path (mTAP-CA1 synapses in freely moving rats. We demonstrate monosynaptic mTAP-CA1 responses can be isolated in vivo as evidenced by observations of independent current sinks in the stratum lacunosum moleculare of both areas CA1 and CA3 following angular bundle stimulation. Contrasting prior indications that TAP input rarely elicits CA1 discharge, we observed mTAP-CA1 responses that appeared to contain putative population spikes in 40% of our behaving animals. Theta burst high frequency stimulation of mTAP afferents resulted in an input specific and NMDA receptor-dependent LTP of mTAP-CA1 responses in behaving animals. LTP of mTAP-CA1 responses decayed as a function of two exponential decay curves with time constants (τ of 2.7 and 148 days to decay 63.2% of maximal LTP. In contrast, mTAP-CA1 population spike potentiation longevity demonstrated a τ of 9.6 days. To our knowledge, these studies provide the first description of mTAP-CA1 LTP longevity in vivo. These data indicate TAP input to area CA1 is a physiologically relevant afferent system that displays robust synaptic plasticity.

  11. Dynamic and temperature dependent response of physical vapor deposited Se in freely standing nanometric thin films

    Science.gov (United States)

    Yoon, Heedong; McKenna, Gregory B.

    2016-05-01

    Here, we report results from an investigation of nano-scale size or confinement effects on the glass transition and viscoelastic properties of physical vapor deposited selenium films. The viscoelastic response of freely standing Se films was determined using a biaxial membrane inflation or bubble inflation method [P. A. O'Connell and G. B. McKenna, Science 307, 1760-1763 (2005)] on films having thicknesses from 60 to 267 nm and over temperatures ranging from Tg, macroscopic - 15 °C to Tg, macroscopic + 21 °C. Time-temperature superposition and time-thickness superposition were found to hold for the films in the segmental dispersion. The responses are compared with macroscopic creep and recoverable creep compliance data for selenium [K. M. Bernatz et al., J. Non-Cryst. Solids 307, 790-801 (2002)]. The time-temperature shift factors for the thin films show weaker temperature dependence than seen in the macroscopic behavior, being near to Arrhenius-like in their temperature dependence. Furthermore, the Se films exhibit a "rubbery-like" stiffening that increases as film thickness decreases similar to prior observations [P. A. O'Connell et al., Macromolecules 45(5), 2453-2459 (2012)] for organic polymers. In spite of the differences from the macroscopic behavior in the temperature dependence of the viscoelastic response, virtually no change in Tg as determined from the thickness dependence of the retardation time defining Tg was observed in the bubble inflation creep experiments to thicknesses as small as 60 nm. We also find that the observed rubbery stiffening is consistent with the postulate of K. L. Ngai et al. [J. Polym. Sci., Part B: Polym. Phys. 51(3), 214-224 (2013)] that it should correlate with the change of the macroscopic segmental relaxation.

  12. An Arbitrary Waveform Wearable Neuro-stimulator System for Neurophysiology Research on Freely Behaving Animals.

    Science.gov (United States)

    Samani, Mohsen Mosayebi; Mahnam, Amin; Hosseini, Nasrin

    2014-04-01

    Portable wireless neuro-stimulators have been developed to facilitate long-term cognitive and behavioral studies on the central nervous system in freely moving animals. These stimulators can provide precisely controllable input(s) to the nervous system, without distracting the animal attention with cables connected to its body. In this study, a low power backpack neuro-stimulator was developed for animal brain researches that can provides arbitrary stimulus waveforms for the stimulation, while it is small and light weight to be used for small animals including rats. The system consists of a controller that uses an RF link to program and activate a small and light microprocessor-based stimulator. A Howland current source was implemented to produce precise current controlled arbitrary waveform stimulations. The system was optimized for ultra-low power consumption and small size. The stimulator was first tested for its electrical specifications. Then its performance was evaluated in a rat experiment when electrical stimulation of medial longitudinal fasciculus induced circling behavior. The stimulator is capable of delivering programmed stimulations up to ± 2 mA with adjusting steps of 1 μA, accuracy of 0.7% and compliance of 6 V. The stimulator is 15 mm × 20 mm × 40 mm in size, weights 13.5 g without battery and consumes a total power of only 5.l mW. In the experiment, the rat could easily carry the stimulator and demonstrated the circling behavior for 0.1 ms current pulses of above 400 μA. The developed system has a competitive size and weight, whereas providing a wide range of operation and the flexibility of generating arbitrary stimulation patterns ideal for long-term experiments in the field of cognitive and neuroscience research.

  13. The concentration and changes in freely dissolved polycyclic aromatic hydrocarbons in biochar-amended soil.

    Science.gov (United States)

    Oleszczuk, Patryk; Kuśmierz, Marcin; Godlewska, Paulina; Kraska, Piotr; Pałys, Edward

    2016-07-01

    The presence of polycyclic aromatic hydrocarbons (PAHs) in biochars hinders their environmental use. The aim of this study was to determine the freely dissolved (Cfree) PAH content in soil amended with biochar in a long-term (851 days) field experiment. Biochar was added to the soil at a rate of 30 and 45 t/ha. The addition of biochar to the soil resulted in a decrease in Σ13 Cfree PAHs by 25 and 22%, in the soil with the addition of biochar at the rate of 30 and 45 t/ha, respectively. As far as individual PAHs are concerned, in most cases a reduction in Cfree was also observed (from 3.6 to 66%, depending on the biochar rate). During the first 105 days of the experiment, the content of Σ13 Cfree in the biochar-amended soil significantly decreased by 26% (30 t/ha) and 36% (45 t/ha). After this period of time until the end of the experiment, no significant changes in Cfree were observed, regardless of the biochar rate. However, the behavior of individual PAH groups differed depending on the number of rings and experimental treatment. Ultimately, after 851 days of the experiment the content of Σ13 Cfree PAHs was lower by 29% (30 t/ha) and 35% (45 t/ha) compared to the beginning of the study as well as lower by 40% (30 t/ha) and 42% (45 t/ha) than in the control soil. The log KTOC coefficients calculated for the biochar-amended soils were higher immediately after adding biochar and subsequently they gradually decreased, indicating the reduced strength of the interaction between biochar and the studied PAHs. The obtained results show that the addition of biochar to soil does not create a risk in terms of the content of Cfree PAHs.

  14. Freely distributed bed-net use among Chano Mille residents, south Ethiopia: a longitudinal study

    Directory of Open Access Journals (Sweden)

    Loha Eskindir

    2013-01-01

    Full Text Available Abstract Background A huge discrepancy was reported between ownership versus utilization of insecticide-treated bed nets (ITNs. To acquire the benefits of ITNs, households need to use and not merely own them. The objective of this study was to characterize the pattern of, and assess factors related to ITN use in one village in south Ethiopia. Methods A prospective cohort study involving 8,121 residents (in 1,388 households was carried out from April 2009 to April 2011 (101 weeks. Every week, individuals were asked whether they slept under an ITN the night before the interview. Descriptive statistics was used to report the availability and use of ITN. A negative, binomial, probability, distribution model was fitted to find out significant predictors of ITN use. Reasons for not using ITN were summarized. Results The total number of ITNs available at the beginning of the study was 1,631 (1.68 ITNs per household. On week 48, 3,099 new ITNs (PermaNet2.0 were distributed freely (2.3 ITNs per household. The number of households who received at least one new ITN was 1,309 (98.4%. The percentage of children Conclusions The ITN use fraction reached to a maximum of 69% despite near universal coverage (98.4% was achieved. Gender, age differences and distance from vector breeding site were associated with ITN use. Strategies may need to be designed addressing disproportions in ITN use, lack of convenient space to hang more than one ITN (for those receiving more than one, and measures to prolong usable life of ITNs.

  15. Environmentally Driven Migration in a Social Network Game

    Science.gov (United States)

    Takano, Masanori; Wada, Kazuya; Fukuda, Ichiro

    2015-07-01

    Cooperative behaviors are common in humans, and they are the fundamental basis of our society. Theoretical and experimental studies have modeled environments where the behaviors of humans, or agents, have been restricted to analyze their social behavior. However, it is important that such studies can be generalized to a less restrictive environment in order to understand human society. Social network games (SNGs) provide a powerful tool for the quantitative study of human behavior using a less restrictive environment than in previous studies. We focused on multilevel selection, one of the theoretical frameworks used to study the evolution of cooperation. The evolution of cooperation by multilevel selection requires that the continual assortment between cooperators and noncooperators is generated; thus, humans may have acquired mechanisms that ensure assortment (e.g., migration between groups). This study aims to investigate this mechanism in a less restrictive environment. For this purpose, we researched the effect of migration based on data analysis in an SNG where the players could behave more freely than was possible in the environments used in the previous studies. We showed that players maintained assortment between cooperators and defectors in this SNG, where it appears that environmentally driven migration generated the assortment.

  16. Assessing EUV mask defectivity

    Science.gov (United States)

    Okoroanyanwu, Uzodinma; Tchikoulaeva, Anna; Ackmann, Paul; Wood, Obert; La Fontaine, Bruno; Bubke, Karsten; Holfeld, Christian; Peters, Jan Hendrik; Kini, Sumanth; Watson, Sterling; Lee, Isaac; Mu, Bo; Lim, Phillip; Raghunathan, Sudhar; Boye, Carol

    2010-04-01

    This paper assesses the readiness of EUV masks for pilot line production. The printability of well characterized reticle defects, with particular emphasis on those reticle defects that cause electrical errors on wafer test chips, is investigated. The reticles are equipped with test marks that are inspected in a die-to-die mode (using DUV inspection tool) and reviewed (using a SEM tool), and which also comprise electrically testable patterns. The reticles have three modules comprising features with 32 nm ground rules in 104 nm pitch, 22 nm ground rules with 80 nm pitch, and 16 nm ground rules with 56 nm pitch (on the wafer scale). In order to determine whether specific defects originate from the substrate, the multilayer film, the absorber stack, or from the patterning process, the reticles were inspected after each fabrication step. Following fabrication, the reticles were used to print wafers on a 0.25 NA full-field ASML EUV exposure tool. The printed wafers were inspected with state of the art bright-field and Deep UV inspection tools. It is observed that the printability of EUV mask defects down to a pitch of 56 nm shows a trend of increased printability as the pitch of the printed pattern gets smaller - a well established trend at larger pitches of 80 nm and 104 nm, respectively. The sensitivity of state-of-the-art reticle inspection tools is greatly improved over that of the previous generation of tools. There appears to be no apparent decline in the sensitivity of these state-of-the-art reticle inspection tools for higher density (smaller) patterns on the mask, even down to 56nm pitch (1x). Preliminary results indicate that a blank defect density of the order of 0.25 defects/cm2 can support very early learning on EUV pilot line production at the 16nm node.

  17. How Tissue Mechanical Properties Affect Enteric Neural Crest Cell Migration.

    Science.gov (United States)

    Chevalier, N R; Gazguez, E; Bidault, L; Guilbert, T; Vias, C; Vian, E; Watanabe, Y; Muller, L; Germain, S; Bondurand, N; Dufour, S; Fleury, V

    2016-02-18

    Neural crest cells (NCCs) are a population of multipotent cells that migrate extensively during vertebrate development. Alterations to neural crest ontogenesis cause several diseases, including cancers and congenital defects, such as Hirschprung disease, which results from incomplete colonization of the colon by enteric NCCs (ENCCs). We investigated the influence of the stiffness and structure of the environment on ENCC migration in vitro and during colonization of the gastrointestinal tract in chicken and mouse embryos. We showed using tensile stretching and atomic force microscopy (AFM) that the mesenchyme of the gut was initially soft but gradually stiffened during the period of ENCC colonization. Second-harmonic generation (SHG) microscopy revealed that this stiffening was associated with a gradual organization and enrichment of collagen fibers in the developing gut. Ex-vivo 2D cell migration assays showed that ENCCs migrated on substrates with very low levels of stiffness. In 3D collagen gels, the speed of the ENCC migratory front decreased with increasing gel stiffness, whereas no correlation was found between porosity and ENCC migration behavior. Metalloprotease inhibition experiments showed that ENCCs actively degraded collagen in order to progress. These results shed light on the role of the mechanical properties of tissues in ENCC migration during development.

  18. The histone demethylase UTX regulates stem cell migration and hematopoiesis.

    Science.gov (United States)

    Thieme, Sebastian; Gyárfás, Tobias; Richter, Cornelia; Özhan, Günes; Fu, Jun; Alexopoulou, Dimitra; Muders, Michael H; Michalk, Irene; Jakob, Christiane; Dahl, Andreas; Klink, Barbara; Bandola, Joanna; Bachmann, Michael; Schröck, Evelin; Buchholz, Frank; Stewart, A Francis; Weidinger, Gilbert; Anastassiadis, Konstantinos; Brenner, Sebastian

    2013-03-28

    Regulated migration of hematopoietic stem cells is fundamental for hematopoiesis. The molecular mechanisms underlying stem cell trafficking are poorly defined. Based on a short hairpin RNA library and stromal cell-derived factor-1 (SDF-1) migration screening assay, we identified the histone 3 lysine 27 demethylase UTX (Kdm6a) as a novel regulator for hematopoietic cell migration. Using hematopoietic stem and progenitor cells from our conditional UTX knockout (KO) mice, we were able to confirm the regulatory function of UTX on cell migration. Moreover, adult female conditional UTX KO mice displayed myelodysplasia and splenic erythropoiesis, whereas UTX KO males showed no phenotype. During development, all UTX KO female and a portion of UTX KO male embryos developed a cardiac defect, cranioschisis, and died in utero. Therefore, UTY, the male homolog of UTX, can compensate for UTX in adults and partially during development. Additionally, we found that UTX knockdown in zebrafish significantly impairs SDF-1/CXCR4-dependent migration of primordial germ cells. Our data suggest that UTX is a critical regulator for stem cell migration and hematopoiesis.

  19. International migration under the microscope

    NARCIS (Netherlands)

    Willekens, F.J.; Massey, D.; Raymer, J.; Beauchemin, C.

    2016-01-01

    Although humanitarian crises, such as the ongoing mass exodus from Syria toward Europe, tend to focus global attention on migration, each year millions of people migrate to and from affected countries throughout the world. Progress has been made in understanding drivers of migration, and we have

  20. Congenital Abdominal Wall Defects

    DEFF Research Database (Denmark)

    Risby, Kirsten; Jakobsen, Marianne Skytte; Qvist, Niels

    2016-01-01

    complications were seen in five (15%) children: four had detachment of the mesh and one patient developed abdominal compartment syndrome. Mesh related clinical infection was observed in five children. In hospital mortality occurred in four cases (2 gastroschisis and 2 omphalocele) and was not procedure......OBJECTIVE: To evaluate the clinical utility of GORE® DUALMESH (GDM) in the staged closure of large congenital abdominal wall defects. MATERIALS AND METHODS: Data of patients with congenital abdominal wall defects managed with GDM was analyzed for outcome regarding complete fascial closure; mesh...

  1. Supersymmetric k-defects

    CERN Document Server

    Koehn, Michael

    2015-01-01

    In supersymmetric theories, topological defects can have nontrivial behaviors determined purely by whether or not supersymmetry is restored in the defect core. A well-known example of this is that some supersymmetric cosmic strings are automatically superconducting, leading to important cosmological effects and constraints. We investigate the impact of nontrivial kinetic interactions, present in a number of particle physics models of interest in cosmology, on the relationship between supersymmetry and supercurrents on strings. We find that in some cases it is possible for superconductivity to be disrupted by the extra interactions.

  2. Migrating for a Profession

    DEFF Research Database (Denmark)

    Olwig, Karen Fog

    2015-01-01

    a strong sense of agency and self-empowerment. In the post-WWII period, numerous Caribbean women trained in nursing at British hospitals that have been described as marred by race and gender related inequality and associated forms of exploitation. Yet, the nurses interviewed about this training emphasised......Youths from the Global South migrating for further education often face various forms of discrimination. This Caribbean case study discusses how conditions in the home country can provide a foundation for educational migration that helps the migrants overcome such obstacles and even develop...... its high quality and downplayed the problems encountered. This positive attitude, it is argued, must be understood in the light of the key ideological role of education, particularly for a profession, as an avenue of social and personal mobility in the late-colonial Caribbean societies and the ways...

  3. 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

  4. 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...

  5. Tracking migrating birds

    DEFF Research Database (Denmark)

    Willemoes, Mikkel

    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......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...... habitats with those in rural habitats. Some species have decreased the frequency of migrants and migration distance in urban environments, and others have not. The other manuscript describes the small scale movements of three different Palaearctic migrants during winter in Africa in a farmland habitat...

  6. Managing the Mass Migration

    Institute of Scientific and Technical Information of China (English)

    Lan Xinzhen

    2012-01-01

    Big crowds and foul air on the train,frighteningly long queues and fierce clashes at the station...these are common scenes during China's Spring Festival travel rush.The annual travel peak is known as the world's biggest human migration.This year's stampede is still ongoing.Lasting over 40 days,people began retuming to their hometowns on January 8 and the final stragglers will make their way back to the cities by February 16.

  7. Migration with fiscal externalities.

    Science.gov (United States)

    Hercowitz, Z; Pines, D

    1991-11-01

    "This paper analyses the distribution of a country's population among regions when migration involves fiscal externalities. The main question addressed is whether a decentralized decision making [by] regional governments can produce an optimal population distribution...or a centralized intervention is indispensable, as argued before in the literature.... It turns out that, while with costless mobility the fiscal externality is fully internalized by voluntary interregional transfers, with costly mobility, centrally coordinated transfers still remain indispensable for achieving the socially optimal allocation."

  8. Making Migration Meaningful

    DEFF Research Database (Denmark)

    Benwell, Ann Fenger

    2013-01-01

    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...... inadvertently contributed to the breakdown of the institutions of marriage and family – institutions that were supported by separations in the pastoral economy...

  9. Enforcement and illegal migration

    OpenAIRE

    Orrenius, Pia

    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...

  10. Functorial Data Migration

    CERN Document Server

    Spivak, David I

    2010-01-01

    In this paper we present a simple database definition language: that of categories and functors. A database schema is a category and a state is a set-valued functor. We show that morphisms of schemas induce three "data migration functors" that translate states from one schema to the other in canonical ways. Database states form a boolean topos of which the classical "relational algebra" is a fragment. These ideas thus create a new denotational semantics for database theory.

  11. Gender and migration from Albania.

    Science.gov (United States)

    Stecklov, Guy; Carletto, Calogero; Azzarri, Carlo; Davis, Benjamin

    2010-11-01

    This article examines the dynamics and causes of the shift in the gender composition of migration, and more particularly, in women's access to migration opportunities and decision-making. Our analysis focuses on Albania, a natural laboratory for studying international migration where out-migration was essentially nonexistent from the end of World War II to the end of the 1980s. Interest in the Albanian case is heightened because of the complex layers of inequality existing at the time when migration began: relatively low levels of inequality within the labor market and educational system-a product of the Communist era-while household relations remained heavily steeped in tradition and patriarchy. We use micro-level data from the Albania 2005 Living Standards Measurement Study, including migration histories for family members since migration began. Based on discrete-time hazard models, the analysis shows a dramatic increase in male migration and a gradual and uneven expansion of the female proportion of this international migration. Female migration, which is shown to be strongly associated with education, wealth, and social capital, appears responsive to economic incentives and constraints. Using information on the dependency of female migration to the household demographic structure as well as the sensitivity of female migration to household-level shocks, we show how household-level constraints and incentives affect male and female migration differently. Throughout this period, however, women's migration behavior appears more directly aligned with household-level factors, and there is little evidence to suggest that increased female migration signals rising behavioral independence among Albanian women.

  12. 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

  13. Defect and Innovation of Water Rights System

    Institute of Scientific and Technical Information of China (English)

    Zhou Bin

    2008-01-01

    The rare deposition of water resources conflicts with its limitless demand. This determined the existence of the water rights transaction system. The implementation of the water rights transaction system requires clarifying the definition of water re-source fight above all distinctly. At present, it is a kind of common right system arrangement which needs the Chinese government to dispose of water resources. Though a series of management sys-tems guaranteed the government's supply of water resource, it hindered the development of the water market seriously and caused the utilization of water resources to stay in the inefficient or low efficient state for a long time. Thus, we should change the government's leading role in the resource distribution and really rely on the market to carry on the water rights trade and transac-tion. In this way, the water rights could become a kind of private property right relatively, and circulate freely in the market. As a result of this, we should overcome the defects of common right, make its external performance internalized maximally and achieve the optimized water resource disposition and use it more effec-tively.

  14. Hydrodynamics of pronuclear migration

    Science.gov (United States)

    Nazockdast, Ehssan; Needleman, Daniel; Shelley, Michael

    2014-11-01

    Microtubule (MT) filaments play a key role in many processes involved in cell devision including spindle formation, chromosome segregation, and pronuclear positioning. We present a direct numerical technique to simulate MT dynamics in such processes. Our method includes hydrodynamically mediated interactions between MTs and other cytoskeletal objects, using singularity methods for Stokes flow. Long-ranged many-body hydrodynamic interactions are computed using a highly efficient and scalable fast multipole method, enabling the simulation of thousands of MTs. Our simulation method also takes into account the flexibility of MTs using Euler-Bernoulli beam theory as well as their dynamic instability. Using this technique, we simulate pronuclear migration in single-celled Caenorhabditis elegans embryos. Two different positioning mechanisms, based on the interactions of MTs with the motor proteins and the cell cortex, are explored: cytoplasmic pulling and cortical pushing. We find that although the pronuclear complex migrates towards the center of the cell in both models, the generated cytoplasmic flows are fundamentally different. This suggest that cytoplasmic flow visualization during pronuclear migration can be utilized to differentiate between the two mechanisms.

  15. Glycine Receptor α2 Subunit Activation Promotes Cortical Interneuron Migration

    Directory of Open Access Journals (Sweden)

    Ariel Avila

    2013-08-01

    Full Text Available Glycine receptors (GlyRs are detected in the developing CNS before synaptogenesis, but their function remains elusive. This study demonstrates that functional GlyRs are expressed by embryonic cortical interneurons in vivo. Furthermore, genetic disruption of these receptors leads to interneuron migration defects. We discovered that extrasynaptic activation of GlyRs containing the α2 subunit in cortical interneurons by endogenous glycine activates voltage-gated calcium channels and promotes calcium influx, which further modulates actomyosin contractility to fine-tune nuclear translocation during migration. Taken together, our data highlight the molecular events triggered by GlyR α2 activation that control cortical tangential migration during embryogenesis.

  16. 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.

  17. Quantum computing with defects.

    Science.gov (United States)

    Weber, J R; Koehl, W F; Varley, J B; Janotti, A; Buckley, B B; Van de Walle, C G; Awschalom, D D

    2010-05-11

    Identifying and designing physical systems for use as qubits, the basic units of quantum information, are critical steps in the development of a quantum computer. Among the possibilities in the solid state, a defect in diamond known as the nitrogen-vacancy (NV(-1)) center stands out for its robustness--its quantum state can be initialized, manipulated, and measured with high fidelity at room temperature. Here we describe how to systematically identify other deep center defects with similar quantum-mechanical properties. We present a list of physical criteria that these centers and their hosts should meet and explain how these requirements can be used in conjunction with electronic structure theory to intelligently sort through candidate defect systems. To illustrate these points in detail, we compare electronic structure calculations of the NV(-1) center in diamond with those of several deep centers in 4H silicon carbide (SiC). We then discuss the proposed criteria for similar defects in other tetrahedrally coordinated semiconductors.

  18. Nonlinear theory of nonstationary low Mach number channel flows of freely cooling nearly elastic granular gases.

    Science.gov (United States)

    Meerson, Baruch; Fouxon, Itzhak; Vilenkin, Arkady

    2008-02-01

    We employ hydrodynamic equations to investigate nonstationary channel flows of freely cooling dilute gases of hard and smooth spheres with nearly elastic particle collisions. This work focuses on the regime where the sound travel time through the channel is much shorter than the characteristic cooling time of the gas. As a result, the gas pressure rapidly becomes almost homogeneous, while the typical Mach number of the flow drops well below unity. Eliminating the acoustic modes and employing Lagrangian coordinates, we reduce the hydrodynamic equations to a single nonlinear and nonlocal equation of a reaction-diffusion type. This equation describes a broad class of channel flows and, in particular, can follow the development of the clustering instability from a weakly perturbed homogeneous cooling state to strongly nonlinear states. If the heat diffusion is neglected, the reduced equation becomes exactly soluble, and the solution develops a finite-time density blowup. The blowup has the same local features at singularity as those exhibited by the recently found family of exact solutions of the full set of ideal hydrodynamic equations [I. Fouxon, Phys. Rev. E 75, 050301(R) (2007); I. Fouxon,Phys. Fluids 19, 093303 (2007)]. The heat diffusion, however, always becomes important near the attempted singularity. It arrests the density blowup and brings about previously unknown inhomogeneous cooling states (ICSs) of the gas, where the pressure continues to decay with time, while the density profile becomes time-independent. The ICSs represent exact solutions of the full set of granular hydrodynamic equations. Both the density profile of an ICS and the characteristic relaxation time toward it are determined by a single dimensionless parameter L that describes the relative role of the inelastic energy loss and heat diffusion. At L>1 the intermediate cooling dynamics proceeds as a competition between "holes": low-density regions of the gas. This competition resembles Ostwald

  19. Dynamics of freely suspended lyotropic films. I. An inelastic light scattering study of thermal surface fluctuations

    Science.gov (United States)

    Young, Charles Y.; Clark, Noel A.

    1981-04-01

    We have studied the spectrum and intensity of light scattered by thermal surface displacement fluctuations on freely suspended lyotropic films. Films consisted of a liquid core and surface soap layers and were drawn from solution containing water, glycerol, NaCl, and the ionic surfactant hexadecyltrimethyl ammonium bromide (HTAB). Two modes were observed: a propagating undulation mode in which the film surfaces move together and a damped peristaltic mode having oppositely moving surface soap layers. Dispersion relations for these modes, obtained from the dependence of the scattered light intensity correlation function on film thickness h and wave vector k, confirm the macroscopic hydrodynamic description of film motion. In particular, the overdamped peristaltic mode is shown to involve Poiseuille flow of the fluid core with the flow velocity zero within 2 Å of the surfactant-solution interface, indicating no significant slip or rigid interfacial water layer. No evidence of dispersion in the effective viscosity of the fluid core h(k,w) over the range 0

  20. Soil Monitor: an advanced and freely accesible platform to challenge soil sealing in Italy

    Science.gov (United States)

    Langella, Giuliano; Basile, Angelo; Giannecchini, Simone; Domenico Moccia, Francesco; Munafò, Michele; Terribile, Fabio

    2017-04-01

    Soil sealing is known to be one of the most serious soil degradation processes since it greatly disturbs or removes essential ecosystem services. Although important policy documents (Roadmap to a Resource Efficient in Europe, SDG'S) promise to mitigate this problem, there are still no signs of change and today soil sealing continues to increase globally. We believe an immediate action is required to reduce the distance between the grand policy declarations and the poor availability of operational - and scientifically robust - tools to challenge soil sealing. These tools must be able to support the decisions made by people who manage and control the soil sealing, namely urban and landscape planning professionals and authorities. In this contribution, we demonstrate that soil sealing can be effectively challenged by the implementation of a dedicated Geospatial Cyberinfrastructure. The platform we are developing - named Soil Monitor - is at now a well-functioning prototype freely available at http://www.soilmonitor.it/. It has been developed by research scientists coming from different disciplines. The national authority for environmental protection (ISPRA) provided the dataset while INU (Italian association of urban planners) tested the soil sealing and the urban planning indicators. More generally, Soil Monitor has been designed to support the Italian policy documents connected to soil sealing: AS 1181, AS 2383, L. 22 May 2015, n. 68; L. 28 December, n. 221). Thus, it connects many different soil sealing aspects including science, community, policy and economy. Soil Monitor performs geospatial computation in real-time to support the decision making in the landscape planning. This aims at measuring soil sealing in order to mitigate it and in particular at recognizing actions to achieve the land degradation neutrality. The web platform covers the entire Italy, even though it is "Country-agnostic". Data are processed at a very high spatial resolution (10-20 m), which

  1. Extended Molecular Dynamics Simulation of the Carbon Monoxide Migration in Sperm Whale Myoglobin

    OpenAIRE

    Bossa, Cecilia; Anselmi, Massimiliano; Roccatano, Danilo; Amadei, Andrea; Vallone, Beatrice; Brunori, Maurizio; Di Nola, Alfredo

    2004-01-01

    We report the results of an extended molecular dynamics simulation on the migration of photodissociated carbon monoxide in wild-type sperm whale myoglobin. Our results allow following one possible ligand migration dynamics from the distal pocket to the Xe1 cavity via a path involving the other xenon binding cavities and momentarily two additional packing defects along the pathway. Comparison with recent time resolved structural data obtained by Laue crystallography with subnanosecond to milli...

  2. Leaning-type polar smectic-C phase in a freely suspended bent-core liquid crystal film.

    Science.gov (United States)

    Chattham, Nattaporn; Tamba, Maria-Gabriela; Stannarius, Ralf; Westphal, Eduard; Gallardo, Hugo; Prehm, Marko; Tschierske, Carsten; Takezoe, Hideo; Eremin, Alexey

    2015-03-01

    A rich variety of responsive behavior occurs in complex structured fluids due to their lower symmetries. On the other hand, fluid disorder tends to increase the symmetry of liquid crystal mesophases. Here, we report direct evidence for the existence of a mesophase with CS symmetry. The observations are based on optical studies of director inversion walls in freely suspended films in electric fields under obliquely incident light. This phase is distinguished by the polarization lying in the molecular tilt plane in freely suspended films. Such a low-symmetry polar fluid phase has been long predicted to occur in bent-core liquid crystals. The stability of this phase is attributed to the bent shape of the mesogens and dominating dispersion interactions.

  3. Incoherent twin boundary migration induced by ion irradiation in Cu

    Energy Technology Data Exchange (ETDEWEB)

    Li, N.; Misra, A. [Center for Integrated Nanotechnologies, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Wang, J.; Wang, Y. Q. [Materials Science and Technology Division, MST-8, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Serruys, Y. [CEA, DEN, Service de Recherches de Metallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France); Nastasi, M. [Nebraska Center for Energy Sciences Research, University of Nebraska, Lincoln, Nebraska 68588 (United States)

    2013-01-14

    Grain boundaries can act as sinks for radiation-induced point defects. The sink capability is dependent on the atomic structures and varies with the type of point defects. Using high-resolution transmission electron microscopy, we observed that {Sigma}3{l_brace}112{r_brace} incoherent twin boundary (ITB) in Cu films migrates under Cu{sup 3+} ion irradiation. Using atomistic modeling, we found that {Sigma}3{l_brace}112{r_brace} ITB has the preferred sites for adsorbing interstitials and the preferential diffusion channels along the Shockley partial dislocations. Coupling with the high mobility of grain boundary Shockley dislocations within {Sigma}3{l_brace}112{r_brace} ITB, we infer that {Sigma}3{l_brace}112{r_brace} ITB migrates through the collective glide of grain boundary Shockley dislocations, driven by a concurrent reduction in the density of radiation-induced defects, which is demonstrated by the distribution of nearby radiation-induced defects.

  4. Hydrogen impurity in SrTiO{sub 3}: structure, electronic properties and migration

    Energy Technology Data Exchange (ETDEWEB)

    Villamagua, Luis [Grupo de Fisica de Cristales, Escuela de Electronica y Telecomunicaciones, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador); Barreto, Rafael [Facultad de IngenierIa Civil, Escuela Politecnica Nacional, Apartado 14-01-2759, Quito (Ecuador); Procel, Luis Miguel [Departamento de Quimica, Colegio Politecnico, Universidad San Francisco de Quito, Apartado 17-12-841, Quito (Ecuador); Stashans, Arvids [Grupo de Fisica de Cristales, Escuela de Electronica y Telecomunicaciones, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador)

    2007-03-15

    The present paper reports a computational investigation of the geometry and electronic structure as well as the migration of a hydrogen impurity in the cubic SrTiO{sub 3} crystal. The study is done using an approach based on the Hartree-Fock theory and developed for periodic systems. It is found that the H impurity forms the so-called OH group at the equilibrium. Analysis of electron density within the defective region implies the enhancement in covalent chemical bonding. A possible defect migration has been also investigated.

  5. Reynolds and Mass-Damping Effect on Prediction of the Peak Amplitude of A Freely Vibrating Cylinder

    Institute of Scientific and Technical Information of China (English)

    HUANG Zhi-yong; CUI Wei-cheng; LIU Ying-zhong; HUANG Xiao-ping

    2008-01-01

    The Reynolds effect and mass-damping effect on the peak amplitude of a freely vibrating cylinder is studied by using forced oscillating data from Gopalkrishnan's research in 1993, in which all experimental cases were carried out at a fixed Reynolds and the tested cylinder was recognized as a body that had no mass and damping. However, the Reynolds and mass-damping are the very important parameters for the peak amplitude of a freely vibrating cylinder.In the present study, a function F is introduced to connect the forced oscillation and free vibration. Firstly the peak amplitude A*G can be obtained from the function F using forced oscillation data of Gopalkrishnan's experimental at Re=104, and then the Reynolds effect is taken into account in the function f(Re), while the mass-damping effect is considered in the function K(α), where α is the mass-damping ratio. So the peak amplitude of a freely vibrating cylinder can be predicted by the expression:A*=K(α)f(Re)A*G. It is found that the peak transverse amplitudes predicted by the above equation agree very well with many recent experimental data under both high and low Reynolds conditions while mass-damping varies. Furthermore, it is seen that the Reynolds number does have a great effect on the peak amplitude of a freely vibrating cylinder. The present idea in this paper can be applied as an update in the empirical models that also use forced oscillation data to predict the vortex induced vibration (VIV) response of a long riser in the frequency domain.

  6. Exercise prior to a freely requested meal modifies pre and postprandial glucose profile, substrate oxidation and sympathovagal balance

    Directory of Open Access Journals (Sweden)

    Chapelot Didier

    2011-09-01

    Full Text Available Abstract Background The effects of exercise on glucose and metabolic events preceding and following a freely initiated meal have never been assessed. Moreover, the relationship between these events and sympathovagal balance is not known. The objective of this study was to determine whether exercise prior to a freely requested meal modifies the pre- and postprandial glucose profile, substrate oxidation and sympathovagal balance. Methods Nine young active male subjects consumed a standard breakfast (2298 ± 357 kJ. After 120 min, they either performed 75 min of exercise on a cycle ergometer (EX - 70% VO2max or rested (RT. Lunch was freely requested but eaten ad libitum only during the 1st session, and then energy intake was fixed across conditions. Glucose and sympathovagal balance were assessed continuously using a subcutaneous glucose monitoring system and analysis of heart rate variability, respectively. Every 5 min, a mean value was calculated for both glucose and sympathovagal balance. Substrate oxidation was determined by calculating the gas exchange ratio when lunch was requested and 180 min after the onset of eating. Results Preprandial glucose profiles were found in 72% of the sessions and with a similar frequency under both conditions. Meals were requested after a similar delay (40 ± 12 and 54 ± 10 min in EX and RT respectively; ns. At meal request, sympathovagal balance was not different between conditions but CHO oxidation was lower and fat oxidation higher in EX than in RT (-46% and +63%, respectively; both p Conclusions These results show that exercise does not impair preprandial glucose declines at the following meal freely requested, but leads to an increased postprandial glucose response and an elevated fat oxidation, an effect that vagal withdrawal may contribute to explain.

  7. Morphine decreases extracellular levels of glutamate in the anterior cingulate cortex: an in vivo microdialysis study in freely moving rats

    Institute of Scientific and Technical Information of China (English)

    YueHAO; Jing-yuYANG; MingGUO; Chun-fuWU; Ming-fanWU

    2004-01-01

    AIM: The anterior cingulate cortex (ACC), an important region of prefrontal cortex for cognitive functions, has been implicated in drug abuse and addiction. In the present study, we intended to investigate the effect of morphine on the extracellular levels of glutamate in the ACC in freely moving rats. METHODS: In vivo microdialysis coupled to high performance liquid chromatography and electrochemical detection had been used for the

  8. Freely dissolved concentrations and sediment-water activity ratios of PCDD/Fs and PCBs in the open Baltic Sea.

    Science.gov (United States)

    Cornelissen, Gerard; Wiberg, Karin; Broman, Dag; Arp, Hans Peter H; Persson, Ylva; Sundqvist, Kristina; Jonsson, Per

    2008-12-01

    Aqueous concentrations of polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs) as well as polychlorinated biphenyls (PCBs) in the open sea have heretofore been measured by filtering and extracting large amounts of water. Measurement of freely dissolved concentrations with this technique is difficult because of corrections for sorption to dissolved organic matter. In this study we use a novel, more economic technique using equilibrium passive samplers consisting of 17-microm thin polyoxymethylene (POM-17), capable of measuring freely dissolved aqueous concentrations (Cw) in pristine (i.e., background) locations. POM-17 was employed in an extensive field campaign at five stations in the open Baltic sea to obtain Cw at two depths (1 m above the seafloor and 25 m below the surface). Median Cw in the overlying water was 2.3 pg toxic equivalents (TEQ)/m3 PCDD/Fs and 15 pg/L sum 7-PCB, with generally less than a factor two variation among sites and depths. Also freely dissolved concentrations of native compounds in the surface sediment porewater (C(PW)) were determined in laboratory batch experiments. The data were used to derive sediment-water activity ratios, which indicate the diffusive flux direction. It was found that the PCDD/Fs and PCBs were in close equilibrium between the sediment porewater and the overlying water. Comparison of C(PW) with total sediment concentrations indicated that more than 90% of the compounds were sorbed to sedimentary black carbon.

  9. Multi-scale model for point defects behaviour in uranium mononitride

    Science.gov (United States)

    Starikov, S.; Kuksin, A.; Smirnova, D.

    2017-01-01

    A multiscale approach was used to study the properties of point defects in uranium mononitride (UN). In this work we used combination of several methods: ab initio calculations; molecular dynamics simulations with a new interatomic potential; thermodynamic model. Density functional theory (DFT) calculations are used for fitting of the parameters of the angular-dependent interatomic potential, as well as for evaluation of the defects formation and migration energies. Molecular dynamics (MD) simulations are applied to analyze what migration/formation mechanisms are activated at finite temperatures and to calculate diffusion coefficients of point defects. The thermodynamic model for description of concentrations and diffusivities for point defects in non-stoichiometric UN1+x is proposed.

  10. 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".

  11. Population, desertification, and migration.

    Science.gov (United States)

    Westing, A H

    1994-01-01

    When an imbalance develops between population numbers and the carrying capacity of the land, the persons thereby displaced are referred to as environmental refugees. The utilization of the land beyond sustainability leads to land degradation and ultimately, desertification. The social and political impacts of long-term environmental migration can be distinguished: a) at the site of origin of the displaced persons by the residual population; b) at rural sites of destination within the nation between the new arrivals and preestablished populations; c) in the cities within the nation; d) in the nonindustrialized foreign countries; and e) in the industrialized foreign countries. In the event that an area which had previously been devoted to pastoralism is converted to agriculture, the displaced pastoralists might respond through armed rebellion. In some instances, the disenchanted urban squatters become a politically restive and even a destabilizing force, as occurred in Sudan in the 1980s, especially in Khartoum and Port Sudan. The foreign countries to which many of the displaced persons are migrating are subjected to increasing levels of migrant-induced economic, cultural, and political strains. The growing problems associated with south-to-north migration across the Mediterranean Sea have recently led France, Italy, Portugal, and Spain to enter into a consultative arrangement with Algeria, Libya, Mauritania, Morocco, and Tunisia. All foreign aid to the nonindustrialized countries that attempts to ameliorate the problem of desertification must adopt integrated approaches that: a) address population issues; b) support environmental education; c) provide for the protection of biodiversity; d) encourage participatory forms of local and national government; e) provide opportunities for income generation outside the livestock sector; and f) foster political security and facilitate ecogeographical (subregional) cooperation.

  12. Many Faces of Migrations

    Directory of Open Access Journals (Sweden)

    Milica Antić Gaber

    2013-12-01

    The title “Many faces of migration”, connecting contributions in this special issue, is borrowed from the already mentioned Gallup Institute’s report on global migration (Esipova, 2011. The guiding principle in the selection of the contributions has been their diversity, reflected also in the list of disciplines represented by the authors: sociology, geography, ethnology and cultural anthropology, history, art history, modern Mediterranean studies, gender studies and media studies. Such an approach necessarily leads not only to a diverse, but at least seemingly also incompatib

  13. [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.

  14. Adsorption, intercalation and diffusion of Na on defective bilayer graphene: a computational study

    Science.gov (United States)

    Yang, Shaobin; Li, Sinan; Tang, Shuwei; Shen, Ding; Dong, Wei; Sun, Wen

    2017-04-01

    The interaction between inserted/adsorbed Na and the structures of pristine and defective bilayer graphene (BLG) with Stone-Wales (SW), mono-vacancy (MV) and divacancy (DV) defects have been investigated by the first-principles calculations. The computational results show that the intercalation of Na in the interlayer of BLG with DV defects is more energetically favorable than Na adsorption on the surface. The lower formation energies of Na adsorption/intercalation on/in the BLG with DV defect reflect a stronger attraction between Na and DV defects compared with MV and SW defects. A significant charge transfer occurs from Na to near graphene layer(s) of BLG. The adsorption and intercalation of Na not only induce more significant structural distortion into the upper layer graphene with SW defect but also spin polarization for MV and DV defects. The results of migration energy barriers show that Na prefers to diffuse toward the DV site, and the diffusion outward the DV site is more difficult in comparison with the SW and MV defects. As a consequence, more Na atoms would be trapped in the region of the DV defect, leading to larger capacity than SW and MV defects.

  15. Types of Congenital Heart Defects

    Science.gov (United States)

    ... heart develops. Examples of Simple Congenital Heart Defects Holes in the Heart (Septal Defects) The septum is ... Google+ SITE INDEX ACCESSIBILITY PRIVACY STATEMENT FOIA NO FEAR ACT OIG CONTACT US National Institutes of Health ...

  16. Adults with Congenital Heart Defects

    Science.gov (United States)

    ... Disease Venous Thromboembolism Aortic Aneurysm More Web Booklet: Adults With Congenital Heart Defects Updated:Aug 29,2017 ... the list below to learn more. Web Booklet: Adults With Congenital Heart Defects Introduction Introduction: Adults with ...

  17. Signaling through the G-protein-coupled receptor Rickets is important for polarity, detachment, and migration of the border cells in Drosophila.

    Science.gov (United States)

    Anllo, Lauren; Schüpbach, Trudi

    2016-06-15

    Cell migration plays crucial roles during development. An excellent model to study coordinated cell movements is provided by the migration of border cell clusters within a developing Drosophila egg chamber. In a mutagenesis screen, we isolated two alleles of the gene rickets (rk) encoding a G-protein-coupled receptor. The rk alleles result in border cell migration defects in a significant fraction of egg chambers. In rk mutants, border cells are properly specified and express the marker Slbo. Yet, analysis of both fixed as well as live samples revealed that some single border cells lag behind the main border cell cluster during migration, or, in other cases, the entire border cell cluster can remain tethered to the anterior epithelium as it migrates. These defects are observed significantly more often in mosaic border cell clusters, than in full mutant clusters. Reduction of the Rk ligand, Bursicon, in the border cell cluster also resulted in migration defects, strongly suggesting that Rk signaling is utilized for communication within the border cell cluster itself. The mutant border cell clusters show defects in localization of the adhesion protein E-cadherin, and apical polarity proteins during migration. E-cadherin mislocalization occurs in mosaic clusters, but not in full mutant clusters, correlating well with the rk border cell migration phenotype. Our work has identified a receptor with a previously unknown role in border cell migration that appears to regulate detachment and polarity of the border cell cluster coordinating processes within the cells of the cluster themselves.

  18. Tantalum cones and bone defects in revision total knee arthroplasty.

    Science.gov (United States)

    Boureau, F; Putman, S; Arnould, A; Dereudre, G; Migaud, H; Pasquier, G

    2015-04-01

    Management of bone loss is a major challenge in revision total knee arthroplasty (TKA). The development of preformed porous tantalum cones offers new possibilities, because they seem to have biological and mechanical qualities that facilitate osseointegration. Compared to the original procedure, when metaphyseal bone defects are too severe, a single tantalum cone may not be enough and we have developed a technique that could extend the indications for this cone in these cases. We used 2 cones to fill femoral bone defects in 7 patients. There were no complications due to wear of the tantalum cones. Radiological follow-up did show any migration or loosening. The short-term results confirm the interest of porous tantalum cones and suggest that they can be an alternative to allografts or megaprostheses in case of massive bone defects.

  19. Reconstructions of eyelid defects

    Directory of Open Access Journals (Sweden)

    Nirmala Subramanian

    2011-01-01

    Full Text Available Eyelids are the protective mechanism of the eyes. The upper and lower eyelids have been formed for their specific functions by Nature. The eyelid defects are encountered in congenital anomalies, trauma, and postexcision for neoplasm. The reconstructions should be based on both functional and cosmetic aspects. The knowledge of the basic anatomy of the lids is a must. There are different techniques for reconstructing the upper eyelid, lower eyelid, and medial and lateral canthal areas. Many a times, the defects involve more than one area. For the reconstruction of the lid, the lining should be similar to the conjunctiva, a cover by skin and the middle layer to give firmness and support. It is important to understand the availability of various tissues for reconstruction. One layer should have the vascularity to support the other layer which can be a graft. A proper plan and execution of it is very important.

  20. Wetting on smooth micropatterned defects

    OpenAIRE

    Debuisson, Damien; Dufour, Renaud; Senez, Vincent; Arscott, Steve

    2011-01-01

    We develop a model which predicts the contact angle hysteresis introduced by smooth micropatterned defects. The defects are modeled by a smooth function and the contact angle hysteresis is explained using a tangent line solution. When the liquid micro-meniscus touches both sides of the defect simultaneously, depinning of the contact line occurs. The defects are fabricated using a photoresist and experimental results confirm the model. An important point is that the model is scale-independent,...

  1. Congenital Heart Defects (For Parents)

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old Congenital Heart Defects KidsHealth > For Parents > Congenital Heart Defects A A A What's in this article? How ... a Problem en español Anomalías cardíacas congénitas A congenital heart defect is a problem in the heart's structure that ...

  2. First-principles study of defect behavior in irradiated uranium monocarbide

    Science.gov (United States)

    Ducher, R.; Dubourg, R.; Barrachin, M.; Pasturel, A.

    2011-03-01

    Ab initio electron theory based on the projector-augmented-wave method in the generalized gradient approximation of the density functional theory is used for calculating formation and migration energies of point defects in uranium monocarbide (UC). The use of the Hubbard term to describe the 5f electrons of uranium is discussed on the basis of the density of states and cohesive energies. A formalism allowing the “raw” calculated energies to be normalized is proposed to take into account the compositional dependence of defective crystals. Such formation energies are then used to determine the population of predominant defects as a function of nonstoichiometry. We identify the most stable defects as uranium antisites and carbon vacancies for UC1-x, and dimers C2 for UC1+x. The most stable thermal defects are obtained, in turn, by formation of complex defects associating dimer C2 and carbon vacancies whereas carbon Frenkel pairs and Schottky defects require larger formation energies. The migration energies are also calculated for different mechanisms, using as diffusion vectors both thermal vacancy sources and preexisting constitutional defects in the case of off-stoichiometric alloys. We compare the calculated diffusion paths with available experimental data proposed by Matzke [J. Less-Common Met.JCOMAH0022-508810.1016/0022-5088(86)90573-4 121, 537 (1986)].

  3. 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...

  4. 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...

  5. Electrochemically induced nanocluster migration

    Energy Technology Data Exchange (ETDEWEB)

    Hartl, Katrin [Lehrstuhl Physikalische Chemie, Technische Universitaet Muenchen, Lichtenbergstr. 4, D-85748 Garching (Germany); Department of Chemistry, CS06, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen O (Denmark); Nesselberger, Markus [Department of Chemistry, CS06, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen O (Denmark); Mayrhofer, Karl J.J. [MPI fuer Eisenforschung, Abt. Grenzflaechenchemie und Oberflaechentechnik, Max-Planck-Strasse 1, D-40237 Duesseldorf (Germany); Kunz, Sebastian; Schweinberger, Florian F.; Kwon, GiHan [Lehrstuhl Physikalische Chemie, Technische Universitaet Muenchen, Lichtenbergstr. 4, D-85748 Garching (Germany); Hanzlik, Marianne [Institut fuer Elektronenmikroskopie, Technische Universitaet Muenchen, Lichtenbergstr. 4, D-85748 Garching (Germany); Heiz, Ueli [Lehrstuhl Physikalische Chemie, Technische Universitaet Muenchen, Lichtenbergstr. 4, D-85748 Garching (Germany); Arenz, Matthias, E-mail: m.arenz@kemi.ku.d [Department of Chemistry, CS06, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen O (Denmark)

    2010-12-30

    In the presented study the influence of electrochemical treatments on size-selected Pt nanoclusters (NCs) supported on amorphous carbon is investigated by means of transmission electron microscopy (TEM). Well-defined Pt NCs are prepared by an ultra-high vacuum (UHV) laser vaporization source and deposited with low kinetic energy ({<=}10 eV/cluster) onto TEM gold grids covered by a thin (2 nm) carbon film. After transfer out of UHV Pt NCs are verified to be uniform in size and randomly distributed on the support. Subsequently, the TEM grids are employed as working electrodes in a standard electrochemical three electrode setup and the Pt nanoclusters are subjected to different electrochemical treatments. It is found that the NC arrangement is not influenced by potential hold conditions (at 0.40 V vs. RHE) or by potential cycling in a limited potential window (V{sub max} = 0.55 V vs. RHE). Upon potential cycling to 1.05 V vs. RHE, however, the NCs migrate on the carbon support. Interestingly, migration in oxygen or argon saturated electrolyte leads to NC coalescence, a mechanism discussed for being responsible for performance degradation of low temperature fuel cells, whereas in carbon monoxide saturated electrolyte the Pt NC agglomerate, but remain separated from each other and thus form distinctive structures.

  6. Developmental Defects in Trisomy 21 and Mouse Models

    Directory of Open Access Journals (Sweden)

    Jean Maurice Delabar

    2006-01-01

    Full Text Available Aneuploidies have diverse phenotypic consequences, ranging from mental retardation and developmental abnormalities to susceptibility to common phenotypes and various neoplasms. This review focuses on the developmental defects of murine models of a prototype human aneuploidy: trisomy 21 (Down syndrome, DS, T21. Murine models are clearly the best tool for dissecting the phenotypic consequences of imbalances that affect single genes or chromosome segments. Embryos can be studied freely in mice, making murine models particularly useful for the characterization of developmental abnormalities. This review describes the main phenotypic alterations occurring during the development of patients with T21 and the developmental abnormalities observed in mouse models, and investigates phenotypes common to both species.

  7. Gender and Migration from Albania

    OpenAIRE

    2010-01-01

    This article examines the dynamics and causes of the shift in the gender composition of migration, and more particularly, in women's access to migration opportunities and decision-making. Our analysis focuses on Albania, a natural laboratory for studying international migration where outmigration was essentially nonexistent from the end of World War II to the end of the 1980s. Interest in the Albanian case is heightened because of the complex layers of inequality existing at the time when mig...

  8. Internal migration transition in Romania?

    OpenAIRE

    Horváth, István

    2016-01-01

    This paper is an overview of the shifts in the internal migration patterns in Romania for the last six decades. In the first part a literature-based brief overview of the trends and patterns of internal migration during communism will be presented. In the second (more extensive) part, a statistical-data based analysis of the internal migration trends and patterns over the last 25 years will be provided.

  9. 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.

  10. Gender and Migration: Overview Report

    OpenAIRE

    Jolly, Susie; Reeves, Hazel; Piper, Nicola

    2005-01-01

    Abstract. Over the past four decades total numbers of international migrants have more than doubled but the percentage of the world population migrating has remained fairly constant. There are now 175 million international migrants worldwide or approximately 3.5 per cent of the global population – about half of whom are women, despite the common misconception that men are the migrants. This Overview Report on Gender and Migration takes a broad approach to migration – it looks at the gender dy...

  11. Gender and Migration from Albania

    OpenAIRE

    2010-01-01

    This article examines the dynamics and causes of the shift in the gender composition of migration, and more particularly, in women’s access to migration opportunities and decision-making. Our analysis focuses on Albania, a natural laboratory for studying international migration where out-migration was essentially nonexistent from the end of World War II to the end of the 1980s. Interest in the Albanian case is heightened because of the complex layers of inequality existing at the time when mi...

  12. Substrate curvature regulates cell migration

    Science.gov (United States)

    He, Xiuxiu; Jiang, Yi

    2017-06-01

    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.

  13. A modeling approach to study the effect of cell polarization on keratinocyte migration.

    Directory of Open Access Journals (Sweden)

    Matthias Jörg Fuhr

    Full Text Available The skin forms an efficient barrier against the environment, and rapid cutaneous wound healing after injury is therefore essential. Healing of the uppermost layer of the skin, the epidermis, involves collective migration of keratinocytes, which requires coordinated polarization of the cells. To study this process, we developed a model that allows analysis of live-cell images of migrating keratinocytes in culture based on a small number of parameters, including the radius of the cells, their mass and their polarization. This computational approach allowed the analysis of cell migration at the front of the wound and a reliable identification and quantification of the impaired polarization and migration of keratinocytes from mice lacking fibroblast growth factors 1 and 2--an established model of impaired healing. Therefore, our modeling approach is suitable for large-scale analysis of migration phenotypes of cells with specific genetic defects or upon treatment with different pharmacological agents.

  14. Wetting on smooth micropatterned defects

    CERN Document Server

    Debuisson, Damien; Senez, Vincent; Arscott, Steve

    2011-01-01

    We develop a model which predicts the contact angle hysteresis introduced by smooth micropatterned defects. The defects are modeled by a smooth function and the contact angle hysteresis is explained using a tangent line solution. When the liquid micro-meniscus touches both sides of the defect simultaneously, depinning of the contact line occurs. The defects are fabricated using a photoresist and experimental results confirm the model. An important point is that the model is scale-independent, i.e. the contact angle hysteresis is dependent on the aspect ratio of the function, not on its absolute size; this could have implications for natural surface defects.

  15. 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)

  16. Study of clustering point defects under irradiation in dilute iron alloys; Etude de la formation sous irradiation des amas de defauts ponctuels dans les alliages ferritiques faiblement allies

    Energy Technology Data Exchange (ETDEWEB)

    Duong-Hardouin Duparc, T.H.A

    1998-12-31

    In low copper steels for nuclear reactor pressure vessel, point defect clustering plays an important role in hardening. These clusters are very small and invisible by transmission electron microscopy. In order to study the hardening component which results from the clustering of freely migrating point defects, we irradiated in a high voltage electron microscope Fe, the FeCu{sub 0.13%}, FeP{sub 0.015%} and FeN{sub 33ppm} alloys and the complex FeMn{sub 1.5%}Ni{sub 0.8%}Cu{sub 0.13%}P{sub 0.01%} alloy the composition of which is close to the matrix of pressure vessel steel. We studied the nucleation of dislocation loops and their growth velocity. The observations and the analyses have shown that in the complex model alloy, the interstitial dislocation loops are smaller and their density is more important than for the others alloys. The diffusion coefficients of interstitials and vacancies are obtained with the help of a simplified model. The densities of dislocation loops and their growth velocities obtained experimentally are reproduced by means of a cluster dynamics model we have developed. This is achieved self-consistently by using as a first trial the approximated coefficients obtained with the simplified model. The results of calculations have shown that the binding energy of di-interstitials must be very important in the binary iron alloys and only 0.95 eV in iron. Copper, nitrogen and phosphorus stabilize di-interstitials in iron. Finally the distribution of interstitial loops at 290 deg C and at 2.10{sup -9} dpa/s is calculated with the diffusion coefficient of point defects adjusted in FeCu. A distribution of small loops appears which gives an increase of hardening estimated to 10 Hv instead of 33 Hv experimentally observed. This low value can be improved by assuming in agreement with molecular dynamics simulations that a little fraction of di-interstitials is created at 2.5 MeV. (author) 111 refs.

  17. 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.

  18. Defect Recognition in Thermosonic Imaging

    Institute of Scientific and Technical Information of China (English)

    CHEN Dapeng; WU Naiming; ZHANG Zheng

    2012-01-01

    This work is aimed at developing an effective method for defect recognition in thermosonic imaging.The heat mechanism of thermosonic imaging is introduced,and the problem for defect recognition is discussed.For this purpose,defect existing in the inner wall of a metal pipeline specimen and defects embedded in a carbon fiber reinforced plastic (CFRP) laminate are tested.The experimental data are processed by pulse phase thermography (PPT) method to show the phase images at different frequencies,and the characteristic of phase angle vs frequency curve of thermal anomalies and sound area is analyzed.A binary image,which is based on the characteristic value of defects,is obtained by a new recognition algorithm to show the defects.Results demonstrate good defect recognition performance for thermosonic imaging,and the reliability of this technique can be improved by the method.

  19. HANDICRAFTS, INVASIONS AND MIGRATIONS

    Directory of Open Access Journals (Sweden)

    Perla Shiomara del Carpio Ovando

    2014-01-01

    Full Text Available This research is focused on the migratory movements that have characterized Simojovel de Allende, Chiapas. Both indigenous Tsotsil communities as well as mestizos from different municipalities live in Simojovel, which is a town that has had multiple migratory movements due to different reasons. For example, economical struggle that has led to poverty, the lack of opportunities; the political situation, religious and ethnic persecutions, insecurity and the communitarian division between zapatistas and non-zapatistas. There are also cultural factors that have caused migration in Simojovel such as tradition, generational gaps, young people’s interests for new types of work and ways of living. Simojovel has been characterized by its coffee, tobacco and amber, but also by its migratory activity.

  20. 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.

  1. Kirchhoff migration without phases

    Science.gov (United States)

    Bardsley, Patrick; Guevara Vasquez, Fernando

    2016-10-01

    We present a simple, frequency domain, preprocessing step to Kirchhoff migration that allows the method to image scatterers when the wave field phase information is lost at the receivers, and only intensities are measured. The resulting imaging method does not require knowing the phases of the probing field or manipulating the phase of the wave field at the receivers. In a regime where the scattered field is small compared to the probing field, the problem of recovering the full-waveform scattered field from intensity data can be formulated as an embarrassingly simple least-squares problem. Although this only recovers the projection (on a known subspace) of the full-waveform scattered field, we show that, for high frequencies, this projection gives Kirchhoff images asymptotically identical to the images obtained with full waveform data. Our method can also be used when the source is modulated by a Gaussian process and autocorrelations are measured at an array of receivers.

  2. Kirchhoff migration without phases

    CERN Document Server

    Bardsley, Patrick

    2016-01-01

    We present a simple, frequency domain, preprocessing step to Kirchhoff migration that allows the method to image scatterers when the wave field phase information is lost at the receivers, and only intensities are measured. The resulting imaging method does not require knowing the phases of the probing field or manipulating the phase of the wave field at the receivers. In a regime where the scattered field is small compared to the probing field, the problem of recovering the full-waveform scattered field from intensity data can be formulated as an embarrassingly simple least-squares problem. Although this only recovers the projection (on a known subspace) of the full-waveform scattered field, we show that, for high frequencies, this projection gives Kirchhoff images asymptotically identical to the images obtained with full waveform data. Our method can also be used when the source is modulated by a Gaussian process and autocorrelations are measured at an array of receivers.

  3. Topological defect lasers

    CERN Document Server

    Knitter, Sebastian; Xiong, Wen; Guy, Mikhael I; Solomon, Glenn S; Cao, Hui

    2014-01-01

    We demonstrate topological defect lasers in a GaAs membrane with embedded InAs quantum dots. By introducing a disclination to a square-lattice of elliptical air holes, we obtain spatially confined optical resonances with high quality factor. Such resonances support powerflow vortices, and lase upon optical excitation of quantum dots, embedded in the structure. The spatially inhomogeneous variation of the unit cell orientation adds another dimension to the control of a lasing mode, enabling the manipulation of its field pattern and energy flow landscape.

  4. Addition of biochar to sewage sludge decreases freely dissolved PAHs content and toxicity of sewage sludge-amended soil.

    Science.gov (United States)

    Stefaniuk, Magdalena; Oleszczuk, Patryk

    2016-11-01

    Due to an increased content of polycyclic aromatic hydrocarbons (PAHs) frequently found in sewage sludges, it is necessary to find solutions that will reduce the environmental hazard associated with their presence. The aim of this study was to determine changes of total and freely dissolved concentration of PAHs in sewage sludge-biochar-amended soil. Two different sewage sludges and biochars with varying properties were tested. Biochars (BC) were produced from biogas residues at 400 °C or 600 °C and from willow at 600 °C. The freely dissolved PAH concentration was determined by means of passive sampling using polyoxymethylene (POM). Total and freely dissolved PAH concentration was monitored at the beginning of the experiment and after 90 days of aging of the sewage sludge with the biochar and soil. Apart from chemical evaluation, the effect of biochar addition on the toxicity of the tested materials on bacteria - Vibrio fischeri (Microtox(®)), plants - Lepidium sativum (Phytotestkit F, Phytotoxkit F), and Collembola - Folsomia candida (Collembolan test) was evaluated. The addition of biochar to the sewage sludges decreased the content of Cfree PAHs. A reduction from 11 to 43% of sewage sludge toxicity or positive effects on plants expressed by root growth stimulation from 6 to 25% to the control was also found. The range of reduction of Cfree PAHs and toxicity was dependent on the type of biochar. After 90 days of incubation of the biochars with the sewage sludge in the soil, Cfree PAHs and toxicity were found to further decrease compared to the soil with sewage sludge alone. The obtained results show that the addition of biochar to sewage sludges may significantly reduce the risk associated with their environmental use both in terms of PAH content and toxicity of the materials tested. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Changes in Cuba’s Migration Policy and Its Impact on Baseball

    Directory of Open Access Journals (Sweden)

    Onesimo Julian Moreira Seijos

    2014-11-01

    Full Text Available Baseball is an essential constituent of the Cuban national identity. For nearly a century, Cuban baseball players had joined high-ranking international leagues, including the Negro Leagues and Major League Baseball (MLB of the United States. After the triumph of the Revolution in 1959, the professional practice of sport was banned in the country. On the other hand, the revolutionary government instituted migration rules that disallowed Cuban citizens to travel abroad freely. Until the collapse of the Soviet Union, the Cuban national baseball team reigned in amateur competitions worldwide. Sporting successes in general and those of baseball in particular, were managed by the government as a political tool; the government used to display the loyalty of the athletes as a triumph of the Cuban system. However, since the nineties there has been a growing departure of Cuban top baseball players who have had the target of entering in MLB franchises, disregarding that the Cuban migration policy had remained unwavering. On the other hand, after the enactment of changes in the Cuban migration policy in 2013, the unconventional departure of high performance baseball players has increased sharply. The relationship between the migration reform and the increased leakage of baseball players has not been studied by scholars. The relevance of this paper is that it is the first academic approach to that relationship. This paper discusses the migration reform in Cuba and focuses mainly on its impact on baseball.

  6. 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…

  7. The migration of university graduates

    DEFF Research Database (Denmark)

    Drejer, Ina; Holm, Jacob Rubæk; Nielsen, Kristian

    of university graduates is an important issue for regional policy makers. The present paper analyzes the migration patterns of university graduates from two very different regions in Denmark: the Greater Capital region around Copenhagen and the peripheral region of North Denmark. Studies of the migration...

  8. New dimensions in cell migration

    NARCIS (Netherlands)

    Friedl, P.; Sahai, E.; Weiss, S.; Yamada, K.M.

    2012-01-01

    Studies of cell migration in three-dimensional (3D) cell culture systems and in vivo have revealed several differences when compared with cell migration in two dimensions, including their morphology and mechanical and signalling control. Here, researchers assess the contribution of 3D models to our

  9. 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...

  10. Interrogating the Mediterranean 'Migration Crisis'

    NARCIS (Netherlands)

    Pallister-Wilkins, P.

    2016-01-01

    This Forum aims to uncover the socio-politics of the ‘migration crisis’ in the Mediterranean. The contributions explore the idea of the ‘migration crisis’ or ‘refugee crisis’ in the Mediterranean from the starting point that as scholars of the Mediterranean we can do two things: one, we can look at

  11. Turbulent boundary layer on a large freely moving particle suspended in high-Reynolds number isotropic turbulence

    Science.gov (United States)

    Byron, Margaret; Meyer, Colin; Bellani, Gabriele; Variano, Evan

    2011-11-01

    We experimentally measure the flow surrounding neutrally buoyant particles freely moving in homogeneous, isotropic turbulence. Particle size is within the inertial subrange of the ambient turbulence. We measure the flow using stereoscopic particle image velocimetry which resolves 3 velocity components in a nearly 2-dimensional planar volume. We calculate ensemble average velocity statistics, conditional on the particle kinematics. Two-point statistics indicate the effect of the moving particle on the surrounding turbulent flow. We use these results to consider the impact of ambient turbulence on aquatic microorganisms, specifically those which are larger than the Kolmogorov timescale and small enough that swimming does not dominate transport.

  12. An automated food delivery system for behavioral and neurophysiological studies of learning and memory in freely moving monkeys.

    Science.gov (United States)

    Wilson, Fraser A W; Kim, Byoung-Hoon; Ryou, Jae-Wook; Ma, Yuan-Ye

    2005-05-01

    We describe a custom-built feeder based on stepping motor technology controlled by a laboratory computer. The feeder dispenses a wide range of foods: any fruit, vegetable, or nut. The feeder allows the investigator to reward monkeys with different foods within a single experimental day. The monkey's motivation to perform tasks is high and does not rely upon food regulation. The avoidance of regulation, as well as the palatability and variety of the rewards dispensed by our device, distinguishes it from commercially available products. We also describe the use of the feeder in the context of novel behavioral and neurophysiological studies in freely moving monkeys.

  13. Data Migration for Ontology Evolution

    Institute of Scientific and Technical Information of China (English)

    赵彦; 张雷; 林晨曦; 张卓; 俞勇

    2004-01-01

    Ontology is the conceptual backbone that provides meaning to data on the semantic web. However, ontology is not a static resource and may evolve over time, which often leaves the meaning of data in an undefined or inconsistent state. It is thus very important to have a method to preserve the data and its meaning when ontology changes. This paper proposed a general method that solves the problem using data migration. It analyzed some of the issues in the method including separation of ontology and data, migration specification, migration result and migration algorithm. The paper also instantiates the general mothod in RDF(S) as an example. The RDF(S) example itself is a simple but complete method for migrating RDF data when RDFS ontology changes.

  14. Dipole defects in beryl

    Energy Technology Data Exchange (ETDEWEB)

    Holanda, B A; Cordeiro, R C; Blak, A R, E-mail: bruna.holanda@usp.br, E-mail: renan.cordeiro@usp.br, E-mail: anablak@if.usp.br

    2010-11-15

    Dipole defects in gamma irradiated and thermally treated beryl (Be{sub 3}Al{sub 2}Si{sub 6}O{sub 18}) samples have been studied using the Thermally Stimulated Depolarization Currents (TSDC) technique. TSDC experiments were performed in pink (morganite), green (emerald), blue (aquamarine) and colourless (goshenite) natural beryl. TSDC spectra present dipole peaks at 190K, 220K, 280K and 310K that change after gamma irradiation and thermal treatments. In morganite samples, for thermal treatments between 700K and 1100K, the 280K peak increase in intensity and the band at 220K disappears. An increase of the 280K peak and a decrease of the 190K peak were observed in the TSDC spectra of morganite after a gamma irradiation of 25kGy performed after the thermal treatments. In the case of emerald samples, thermal treatments enhanced the 280K peak and gamma irradiation partially destroyed this band. The goshenite TSDC spectra present only one band at 280K that is not affected either by thermal treatments or by gamma irradiation. All the observed peaks are of dipolar origin because the intensity of the bands is linearly dependent on the polarization field, behaviour of dipole defects. The systematic study, by means of TSDC measurements, of ionizing irradiation effects and thermal treatments in these crystals makes possible a better understanding of the role played by the impurities in beryl crystals.

  15. 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.

  16. Dependence of sea urchin primary mesenchyme cell migration on xyloside- and sulfate-sensitive cell surface-associated components.

    Science.gov (United States)

    Lane, M C; Solursh, M

    1988-05-01

    The migration of sea urchin primary mesenchyme cells (PMC) is inhibited in embryos cultured in sulfate-free seawater and in seawater containing exogenous xylosides. In the present study, primary mesenchyme cells and extra-cellular matrix have been isolated from normal and treated Lytechinus pictus and Strongylocentrotus purpuratus embryos and recombined in an in vitro migration assay to determine whether the cells or the matrix are migration defective. Normal cells were found to migrate on either normal or treated matrix, whereas sulfate-deprived and xyloside-treated PMC failed to migrate in vitro on normal and treated substrata. Migratory ability can be restored to defective cells by returning the PMC to normal seawater, or by exposing the defective cells to materials removed from the surface of normal cells with 1 M urea. The similarity of the results obtained with sulfate-deprived and xyloside-treated PMC suggested that a common molecule may be affected by the two treatments. As a first test of this possibility, xyloside-treated S. purpuratus PMC were given the urea extract prepared from sulfate-deprived S. purpuratus PMC, and this extract did not restore migratory ability. These findings indicate that PMC normally synthesize a surface-associated molecule that is involved in cell migration, and the sensitivity to exogenous xylosides and sulfate deprivation suggests that a sulfated proteoglycan may be involved in primary mesenchyme cell migration.

  17. The atypical cadherin Celsr1 functions non-cell autonomously to block rostral migration of facial branchiomotor neurons in mice.

    Science.gov (United States)

    Glasco, Derrick M; Pike, Whitney; Qu, Yibo; Reustle, Lindsay; Misra, Kamana; Di Bonito, Maria; Studer, Michele; Fritzsch, Bernd; Goffinet, André M; Tissir, Fadel; Chandrasekhar, Anand

    2016-09-01

    The caudal migration of facial branchiomotor (FBM) neurons from rhombomere (r) 4 to r6 in the hindbrain is an excellent model to study neuronal migration mechanisms. Although several Wnt/Planar Cell Polarity (PCP) components are required for FBM neuron migration, only Celsr1, an atypical cadherin, regulates the direction of migration in mice. In Celsr1 mutants, a subset of FBM neurons migrates rostrally instead of caudally. Interestingly, Celsr1 is not expressed in the migrating FBM neurons, but rather in the adjacent floor plate and adjoining ventricular zone. To evaluate the contribution of different expression domains to neuronal migration, we conditionally inactivated Celsr1 in specific cell types. Intriguingly, inactivation of Celsr1 in the ventricular zone of r3-r5, but not in the floor plate, leads to rostral migration of FBM neurons, greatly resembling the migration defect of Celsr1 mutants. Dye fill experiments indicate that the rostrally-migrated FBM neurons in Celsr1 mutants originate from the anterior margin of r4. These data suggest strongly that Celsr1 ensures that FBM neurons migrate caudally by suppressing molecular cues in the rostral hindbrain that can attract FBM neurons.

  18. Patterns of cell thickness oscillations during directional migration of Physarum polycephalum.

    Science.gov (United States)

    Rodiek, Beatrice; Takagi, Seiji; Ueda, Tetsuo; Hauser, Marcus J B

    2015-07-01

    The functional relationship between the velocity of cell locomotion and intracellular spatial patterns of thickness oscillations in the acellular slime mould Physarum polycephalum was studied. The freely migrating plasmodial cells of 300-800 µm length were tadpole-shaped and displayed thickness oscillations along their longitudinal (body) axis. Two distinct patterns of intracellular thickness oscillations were observed in dependence on the locomotive velocity. The first mode consisted of a single travelling wave that propagated from the rear to the front of the cell. This pattern occurred when the plasmodium migrated slowly. The second mode was a multinodal standing wave that was found during events of fast propagation. Transitions between these two types of cell thickness oscillation patterns took place in narrow propagation velocity intervals. We discuss the possible mechanism leading to these patterns, which are conjectured to modulate both the intracellular pressure and the velocity of free locomotion of the cell.

  19. Particle-area dependence of mineral dust in the immersion mode: investigations with freely suspended drops in an acoustic levitator

    Directory of Open Access Journals (Sweden)

    K. Diehl

    2014-05-01

    Full Text Available The heterogeneous freezing temperatures of supercooled drops were measured by using an acoustic levitator. This technique allows to freely suspending single drops in air without electrical charges thereby avoiding any electrical influences which may affect the freezing process. Heterogeneous nucleation caused by several mineral dust particles (montmorillonite, two types of illite was investigated in the immersion mode. Drops of 1 \\unit{mm} in radius were monitored by a~video camera during cooling down to −28 °C to simulate the tropospheric temperature range. The surface temperature of the drops was remotely determined with an infra-red thermometer so that the onset of freezing was indicated. For comparisons, measurements with one particle type were additionally performed in the Mainz vertical wind tunnel with drops of 340 \\unit{{\\mu}m} radius freely suspended. The data were interpreted regarding the particle surfaces immersed in the drops. Immersion freezing was observed in a~temperature range between −13 and −26 °C in dependence of particle type and surface area per drop. The results were evaluated by applying two descriptions of heterogeneous freezing, the stochastic and the singular model.

  20. Web-MCQ: a set of methods and freely available open source code for administering online multiple choice question assessments.

    Science.gov (United States)

    Hewson, Claire

    2007-08-01

    E-learning approaches have received increasing attention in recent years. Accordingly, a number of tools have become available to assist the nonexpert computer user in constructing and managing virtual learning environments, and implementing computer-based and/or online procedures to support pedagogy. Both commercial and free packages are now available, with new developments emerging periodically. Commercial products have the advantage of being comprehensive and reliable, but tend to require substantial financial investment and are not always transparent to use. They may also restrict pedagogical choices due to their predetermined ranges of functionality. With these issues in mind, several authors have argued for the pedagogical benefits of developing freely available, open source e-learning resources, which can be shared and further developed within a community of educational practitioners. The present paper supports this objective by presenting a set of methods, along with supporting freely available, downloadable, open source programming code, to allow administration of online multiple choice question assessments to students.

  1. Chronic monitoring of cortical hemodynamics in behaving, freely-moving rats using a miniaturized head-mounted optical microscope

    Science.gov (United States)

    Sigal, Iliya; Gad, Raanan; Koletar, Margaret; Ringuette, Dene; Stefanovic, Bojana; Levi, Ofer

    2016-03-01

    Growing interest within the neurophysiology community in assessing healthy and pathological brain activity in animals that are awake and freely-behaving has triggered the need for optical systems that are suitable for such longitudinal studies. In this work we report label-free multi-modal imaging of cortical hemodynamics in the somatosensory cortex of awake, freely-behaving rats, using a novel head-mounted miniature optical microscope. The microscope employs vertical cavity surface emitting lasers (VCSELs) at three distinct wavelengths (680 nm, 795 nm, and 850 nm) to provide measurements of four hemodynamic markers: blood flow speeds, HbO, HbR, and total Hb concentration, across a > 2 mm field of view. Blood flow speeds are extracted using Laser Speckle Contrast Imaging (LSCI), while oxygenation measurements are performed using Intrinsic Optical Signal Imaging (IOSI). Longitudinal measurements on the same animal are made possible over the course of > 6 weeks using a chronic window that is surgically implanted into the skull. We use the device to examine changes in blood flow and blood oxygenation in superficial cortical blood vessels and tissue in response to drug-induced absence-like seizures, correlating motor behavior with changes in blood flow and blood oxygenation in the brain.

  2. Commentary: How ethanol short-circuits the cerebellum-actions on Golgi cells in freely-moving animals.

    Science.gov (United States)

    Freund, Ronald K

    2012-11-01

    This commentary discusses the important contributions of the article published in this journal by Huang and colleagues, titled, "Acute ethanol exposure increases firing and induces oscillations in cerebellar Golgi cells of freely moving rats." In this manuscript, Huang and colleagues present a number of interesting and important findings. While it has been shown previously that ethanol (EtOH) causes an increase in the firing of cerebellar Golgi cells in brain slice preparations and anesthetized animals, here the authors provide the first evidence that this action of EtOH occurs in vivo in freely moving, unanesthetized animals. These results also enhance our understanding of cerebellar functioning by describing the mechanism by which EtOH essentially de-afferentates (blocks specific inputs to) the cerebellum from the normal processing of sensory signals due to EtOH-induced Golgi neuron excitation, resulting in inhibition of granule cells. Furthermore, the authors characterize the novel observation of EtOH-induced neuronal oscillations, which was not previously observed in other preparations.

  3. Mass and Moment of Inertia Govern the Transition in the Dynamics and Wakes of Freely Rising and Falling Cylinders

    Science.gov (United States)

    Mathai, Varghese; Zhu, Xiaojue; Sun, Chao; Lohse, Detlef

    2017-08-01

    In this Letter, we study the motion and wake patterns of freely rising and falling cylinders in quiescent fluid. We show that the amplitude of oscillation and the overall system dynamics are intricately linked to two parameters: the particle's mass density relative to the fluid m*≡ρp/ρf and its relative moment of inertia I*≡Ip/If. This supersedes the current understanding that a critical mass density (m*≈0.54 ) alone triggers the sudden onset of vigorous vibrations. Using over 144 combinations of m* and I*, we comprehensively map out the parameter space covering very heavy (m*>10 ) to very buoyant (m*data collapse into two scaling regimes demarcated by a transitional Strouhal number Stt≈0.17 . Stt separates a mass-dominated regime from a regime dominated by the particle's moment of inertia. A shift from one regime to the other also marks a gradual transition in the wake-shedding pattern: from the classical two-single (2 S ) vortex mode to a two-pair (2 P ) vortex mode. Thus, autorotation can have a significant influence on the trajectories and wakes of freely rising isotropic bodies.

  4. A DFT-based toxicity QSAR study of aromatic hydrocarbons to Vibrio fischeri: Consideration of aqueous freely dissolved concentration.

    Science.gov (United States)

    Wang, Ying; Yang, Xianhai; Wang, Juying; Cong, Yi; Mu, Jingli; Jin, Fei

    2016-05-05

    In the present study, quantitative structure-activity relationship (QSAR) techniques based on toxicity mechanism and density functional theory (DFT) descriptors were adopted to develop predictive models for the toxicity of alkylated and parent aromatic hydrocarbons to Vibrio fischeri. The acute toxicity data of 17 aromatic hydrocarbons from both literature and our experimental results were used to construct QSAR models by partial least squares (PLS) analysis. With consideration of the toxicity process, the partition of aromatic hydrocarbons between water phase and lipid phase and their interaction with the target biomolecule, the optimal QSAR model was obtained by introducing aqueous freely dissolved concentration. The high statistical values of R(2) (0.956) and Q(CUM)(2) (0.942) indicated that the model has good goodness-of-fit, robustness and internal predictive power. The average molecular polarizability (α) and several selected thermodynamic parameters reflecting the intermolecular interactions played important roles in the partition of aromatic hydrocarbons between the water phase and biomembrane. Energy of the highest occupied molecular orbital (E(HOMO)) was the most influential descriptor which dominated the toxicity of aromatic hydrocarbons through the electron-transfer reaction with biomolecules. The results demonstrated that the adoption of freely dissolved concentration instead of nominal concentration was a beneficial attempt for toxicity QSAR modeling of hydrophobic organic chemicals.

  5. Computer code for the atomistic simulation of lattice defects and dynamics. [COMENT code

    Energy Technology Data Exchange (ETDEWEB)

    Schiffgens, J.O.; Graves, N.J.; Oster, C.A.

    1980-04-01

    This document has been prepared to satisfy the need for a detailed, up-to-date description of a computer code that can be used to simulate phenomena on an atomistic level. COMENT was written in FORTRAN IV and COMPASS (CDC assembly language) to solve the classical equations of motion for a large number of atoms interacting according to a given force law, and to perform the desired ancillary analysis of the resulting data. COMENT is a dual-purpose intended to describe static defect configurations as well as the detailed motion of atoms in a crystal lattice. It can be used to simulate the effect of temperature, impurities, and pre-existing defects on radiation-induced defect production mechanisms, defect migration, and defect stability.

  6. Defects in new protective aprons

    Energy Technology Data Exchange (ETDEWEB)

    Glaze, S.; LeBlanc, A.D.; Bushong, S.C.

    1984-07-01

    Upon careful examination, several defects have been detected in new protective aprons. The nature of the defects is identified and described. Although the occurrence of such defects has not exceeded 5%, they are significant enough to warrant return of the lead apron to the supplier. It is recommended that the integrity of all new protective aprons be verified upon receipt as well as at yearly intervals.

  7. 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.

  8. Simple rules guide dragonfly migration

    Science.gov (United States)

    Wikelski, Martin; Moskowitz, David; Adelman, James S; Cochran, Jim; Wilcove, David S; May, Michael L

    2006-01-01

    Every year billions of butterflies, dragonflies, moths and other insects migrate across continents, and considerable progress has been made in understanding population-level migratory phenomena. However, little is known about destinations and strategies of individual insects. We attached miniaturized radio transmitters (ca 300 mg) to the thoraxes of 14 individual dragonflies (common green darners, Anax junius) and followed them during their autumn migration for up to 12 days, using receiver-equipped Cessna airplanes and ground teams. Green darners exhibited distinct stopover and migration days. On average, they migrated every 2.9±0.3 days, and their average net advance was 58±11 km in 6.1±0.9 days (11.9±2.8 km d−1) in a generally southward direction (186±52°). They migrated exclusively during the daytime, when wind speeds were less than 25 km h−1, regardless of wind direction, but only after two nights of successively lower temperatures (decrease of 2.1±0.6 °C in minimum temperature). The migratory patterns and apparent decision rules of green darners are strikingly similar to those proposed for songbirds, and may represent a general migration strategy for long-distance migration of organisms with high self-propelled flight speeds. PMID:17148394

  9. Musei del migration heritage

    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.

  10. 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.

  11. Studies of defects and defect agglomerates by positron annihilation spectroscopy

    DEFF Research Database (Denmark)

    Eldrup, Morten Mostgaard; Singh, B.N.

    1997-01-01

    and with other experimental methods (in particular transmission electron microscopy) forms the basis for the use of PAS to quantitatively characterize defects and defect complexes, both visible and invisible is transmission electron microscopes: this is illustrated by some examples. Finally, the advantages...

  12. Nonmuscle myosin heavy chain IIA mediates integrin LFA-1 de-adhesion during T lymphocyte migration.

    Science.gov (United States)

    Morin, Nicole A; Oakes, Patrick W; Hyun, Young-Min; Lee, Dooyoung; Chin, Y Eugene; Chin, Eugene Y; King, Michael R; Springer, Timothy A; Shimaoka, Motomu; Tang, Jay X; Reichner, Jonathan S; Kim, Minsoo

    2008-01-21

    Precise spatial and temporal regulation of cell adhesion and de-adhesion is critical for dynamic lymphocyte migration. Although a great deal of information has been learned about integrin lymphocyte function-associated antigen (LFA)-1 adhesion, the mechanism that regulates efficient LFA-1 de-adhesion from intercellular adhesion molecule (ICAM)-1 during T lymphocyte migration is unknown. Here, we show that nonmuscle myosin heavy chain IIA (MyH9) is recruited to LFA-1 at the uropod of migrating T lymphocytes, and inhibition of the association of MyH9 with LFA-1 results in extreme uropod elongation, defective tail detachment, and decreased lymphocyte migration on ICAM-1, without affecting LFA-1 activation by chemokine CXCL-12. This defect was reversed by a small molecule antagonist that inhibits both LFA-1 affinity and avidity regulation, but not by an antagonist that inhibits only affinity regulation. Total internal reflection fluorescence microscopy of the contact zone between migrating T lymphocytes and ICAM-1 substrate revealed that inactive LFA-1 is selectively localized to the posterior of polarized T lymphocytes, whereas active LFA-1 is localized to their anterior. Thus, during T lymphocyte migration, uropodal adhesion depends on LFA-1 avidity, where MyH9 serves as a key mechanical link between LFA-1 and the cytoskeleton that is critical for LFA-1 de-adhesion.

  13. C3G regulates cortical neuron migration, preplate splitting and radial glial cell attachment.

    Science.gov (United States)

    Voss, Anne K; Britto, Joanne M; Dixon, Mathew P; Sheikh, Bilal N; Collin, Caitlin; Tan, Seong-Seng; Thomas, Tim

    2008-06-01

    Neuronal migration is integral to the development of the cerebral cortex and higher brain function. Cortical neuron migration defects lead to mental disorders such as lissencephaly and epilepsy. Interaction of neurons with their extracellular environment regulates cortical neuron migration through cell surface receptors. However, it is unclear how the signals from extracellular matrix proteins are transduced intracellularly. We report here that mouse embryos lacking the Ras family guanine nucleotide exchange factor, C3G (Rapgef1, Grf2), exhibit a cortical neuron migration defect resulting in a failure to split the preplate into marginal zone and subplate and a failure to form a cortical plate. C3G-deficient cortical neurons fail to migrate. Instead, they arrest in a multipolar state and accumulate below the preplate. The basement membrane is disrupted and radial glial processes are disorganised and lack attachment in C3G-deficient brains. C3G is activated in response to reelin in cortical neurons, which, in turn, leads to activation of the small GTPase Rap1. In C3G-deficient cells, Rap1 GTP loading in response to reelin stimulation is reduced. In conclusion, the Ras family regulator C3G is essential for two aspects of cortex development, namely radial glial attachment and neuronal migration.

  14. UK Migration Policy and Migration from Eastern Partnership Countries

    OpenAIRE

    2013-01-01

    This paper examines UK migration policy and recent migration flows from Eastern Partnership (EaP) countries to the UK. Although inflows of migrant workers were relatively large in the mid-2000s, especially amongst Ukrainians, these have fallen following changes to UK immigration policy, especially the Seasonal Agricultural Workers Scheme and the introduction of the Points Based System. As a result, the stock of migrants from EaP countries resident in the UK is small, especially in comparison ...

  15. Background Defect Density Reduction Using Automated Defect Inspection And Analysis

    Science.gov (United States)

    Weirauch, Steven C.

    1988-01-01

    Yield maintenance and improvement is a major area of concern in any integrated circuit manufacturing operation. A major aspect of this concern is controlling and reducing defect density. Obviously, large defect excursions must be immediately addressed in order to maintain yield levels. However, to enhance yields, the subtle defect mechanisms must be reduced or eliminated as well. In-line process control inspections are effective for detecting large variations in the defect density on a real time basis. Examples of in-line inspection strategies include after develop or after etch inspections. They are usually effective for detecting when a particular process segment has gone out of control. However, when a process is running normally, there exists a background defect density that is generally not resolved by in-line process control inspections. The inspection strategies that are frequently used to monitor the background defect density are offline inspections. Offline inspections are used to identify the magnitude and characteristics of the background defect density. These inspections sample larger areas of product wafers than the in-line inspections to allow identification of the defect generating mechanisms that normally occur in the process. They are used to construct a database over a period of time so that trends may be studied. This information enables engineering efforts to be focused on the mechanisms that have the greatest impact on device yield. Once trouble spots in the process are identified, the data base supplies the information needed to isolate and solve them. The key aspect to the entire program is to utilize a reliable data gathering mechanism coupled with a flexible information processing system. This paper describes one method of reducing the background defect density using automated wafer inspection and analysis. The tools used in this evaluation were the KLA 2020 Wafer Inspector, KLA Utility Terminal (KLAUT), and a new software package developed

  16. Defects in rutile and anatase polymorphs of TiO2: kinetics and thermodynamics near grain boundaries.

    Science.gov (United States)

    Uberuaga, Blas P; Bai, Xian-Ming

    2011-11-02

    The direct consequence of irradiation on a material is the creation of point defects-typically interstitials and vacancies, and their aggregates-but it is the ultimate fate of these defects that determines the material's radiation tolerance. Thus, understanding how defects migrate and interact with sinks, such as grain boundaries, is crucial for predicting the evolution of the material. We examine defect properties in two polymorphs of TiO(2)-rutile and anatase-to determine how these materials might respond differently to irradiation. Using molecular statics and temperature accelerated dynamics, we focus on two issues: how point defects interact with a representative grain boundary and how they migrate in the bulk phase. We find that grain boundaries in both polymorphs are strong sinks for all point defects, though somewhat stronger in rutile than anatase. Further, the defect kinetics are very different in the two polymorphs, with interstitial species diffusing quickly in rutile while oxygen defects-both interstitials and vacancies-are fast diffusers in anatase. These results allow us to speculate on how grain boundaries will modify the radiation tolerance of these materials. In particular, grain boundaries in rutile will lead to a space charge layer at the boundary and a vacancy-rich damage structure, while in anatase the damage structure would likely be more stoichiometric, but with larger defects consisting primarily of Ti ions.

  17. Beryllium nitrate inhibits fibroblast migration to disrupt epimorphic regeneration.

    Science.gov (United States)

    Cook, Adam B; Seifert, Ashley W

    2016-10-01

    Epimorphic regeneration proceeds with or without formation of a blastema, as observed for the limb and skin, respectively. Inhibition of epimorphic regeneration provides a means to interrogate the cellular and molecular mechanisms that regulate it. In this study, we show that exposing amputated limbs to beryllium nitrate disrupts blastema formation and causes severe patterning defects in limb regeneration. In contrast, exposing full-thickness skin wounds to beryllium only causes a delay in skin regeneration. By transplanting full-thickness skin from ubiquitous GFP-expressing axolotls to wild-type hosts, we demonstrate that beryllium inhibits fibroblast migration during limb and skin regeneration in vivo Moreover, we show that beryllium also inhibits cell migration in vitro using axolotl and human fibroblasts. Interestingly, beryllium did not act as an immunostimulatory agent as it does in Anurans and mammals, nor did it affect keratinocyte migration, proliferation or re-epithelialization, suggesting that the effect of beryllium is cell type-specific. While we did not detect an increase in cell death during regeneration in response to beryllium, it did disrupt cell proliferation in mesenchymal cells. Taken together, our data show that normal blastema organogenesis cannot occur without timely infiltration of local fibroblasts and highlights the importance of positional information to instruct pattern formation during regeneration. In contrast, non-blastemal-based skin regeneration can occur despite early inhibition of fibroblast migration and cell proliferation.

  18. Neuronal migration and its disorders affecting the CA3 region

    Directory of Open Access Journals (Sweden)

    Richard eBelvindrah

    2014-03-01

    Full Text Available In this review, we focus on CA3 neuronal migration disorders in the rodent. We begin by introducing the main steps of hippocampal development, and we summarize characteristic hippocampal malformations in human. We then describe various mouse mutants showing structural hippocampal defects. Notably, genes identified in human cortical neuronal migration disorders consistently give rise to a CA3 phenotype when mutated in the mouse. We successively describe their molecular, physiological and behavioral phenotypes that together contribute to a better understanding of CA3-dependent functions. We finally discuss potential factors underlying the CA3 vulnerability revealed by these mouse mutants and that may also contribute to other human neurological and psychiatric disorders.

  19. Vacancy Migration and Void Formation in gamma-irradiated Ice

    DEFF Research Database (Denmark)

    Eldrup, Morten Mostgaard

    1976-01-01

    are ascribed to Ps inhibition and conversion by radiation created OH radicals. Heating above −165°C makes both effects disappear in agreement with radiation chemistry results on OH. Heating also increases the longest lifetime up to 11 nsec at −130°C. This is explained as vacancy migration leading to void......Positron annihilation techniques (PAT) have been used to study the effects in ice of γ irradiation at −196°C and of subsequent heating, both in poly‐ and monocrystalline samples. The main effects of irradiation are (1) the appearance in positron lifetime spectra of two long‐lived components (1...... formation. A vacancy migration energy is obtained, Em=0.34±0.07 eV, around three times higher than the previously assumed value. The advantage in this kind of study of using PAT, which are specifically sensitive to vacancy type defects, is pointed out....

  20. Dock-family exchange factors in cell migration and disease.

    Science.gov (United States)

    Gadea, Gilles; Blangy, Anne

    2014-10-01

    Dock family proteins are evolutionary conserved exchange factors for the Rho GTPases Rac and Cdc42. There are 11 Dock proteins in mammals, named Dock1 (or Dock180) to Dock11 that play different cellular functions. In particular, Dock proteins regulate actin cytoskeleton, cell adhesion and migration. Not surprisingly, members of the Dock family have been involved in various pathologies, including cancer and defects in the central nervous and immune systems. This review proposes an update of the recent findings regarding the function of Dock proteins, focusing on their role in the control of cell migration and invasion and the consequences in human diseases. Copyright © 2014 Elsevier GmbH. All rights reserved.

  1. Transport-reaction model for defect and carrier behavior within displacement cascades in gallium arsenide

    Energy Technology Data Exchange (ETDEWEB)

    Wampler, William R.; Myers, Samuel Maxwell,

    2014-02-01

    A model is presented for recombination of charge carriers at displacement damage in gallium arsenide, which includes clustering of the defects in atomic displacement cascades produced by neutron or ion irradiation. The carrier recombination model is based on an atomistic description of capture and emission of carriers by the defects with time evolution resulting from the migration and reaction of the defects. The physics and equations on which the model is based are presented, along with details of the numerical methods used for their solution. The model uses a continuum description of diffusion, field-drift and reaction of carriers and defects within a representative spherically symmetric cluster. The initial radial defect profiles within the cluster were chosen through pair-correlation-function analysis of the spatial distribution of defects obtained from the binary-collision code MARLOWE, using recoil energies for fission neutrons. Charging of the defects can produce high electric fields within the cluster which may influence transport and reaction of carriers and defects, and which may enhance carrier recombination through band-to-trap tunneling. Properties of the defects are discussed and values for their parameters are given, many of which were obtained from density functional theory. The model provides a basis for predicting the transient response of III-V heterojunction bipolar transistors to pulsed neutron irradiation.

  2. Subsurface defects structural evolution in nano-cutting of single crystal copper

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Quanlong [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Center for Precision Engineering, Harbin Institute of Technology, Harbin 150001 (China); Bai, Qingshun [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Chen, Jiaxuan, E-mail: wangquanlong0@hit.edu.cn [Center for Precision Engineering, Harbin Institute of Technology, Harbin 150001 (China); Sun, Yazhou [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Guo, Yongbo [Center for Precision Engineering, Harbin Institute of Technology, Harbin 150001 (China); Liang, Yingchun [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2015-07-30

    Highlights: • An innovative analysis method is adopted to analyze nano-cutting process accurately. • A characteristic SFT and stair-rod dislocation are found in subsurface defect layer. • The formation mechanism of stair-rod dislocation is investigated. • The local atomic structure of subsurface defects is introduced. - Abstract: In this work, molecular dynamics simulation is performed to study the subsurface defects structural distribution and its evolution during nano-cutting process of single crystal copper. The formation mechanism of chip and machined surface is interviewed by analyzing the dislocation evolution and atomic migration. The centro-symmetry parameter and spherical harmonics method are adopted to characterize the distribution and evolution of the subsurface defect structures and local atomic structures. The results show that stacking faults, dislocation loops, “V-shaped” dislocation loops, and plenty of point defects are formed during the machined surface being formed in shear-slip zone. In subsurface damage layers, stair-rod dislocation, stacking fault tetrahedra, atomic cluster defect, and vacancy defect are formed. And the formation mechanism of stair-rod dislocation is investigated by atomic-scale structure evolution. The local atomic structures of subsurface defects are icosahedrons, hexagonal close packed, body-centered cubic, and defect face center cubic, and the variations of local atomic structures are investigated.

  3. Defect studies in low-temperature-grown GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Bliss, D.E.

    1992-11-01

    High content of excess As is incorporated in GaAs grown by low-temperature molecular-beam-epitaxy (LTMBE). The excess As exists primarily as As antisite defects AsGa and a lesser extent of gallium vacancies V[sub Ga]. The neutral AsGa-related defects were measured by infrared absorption at 1[mu]m. Gallium vacancies, V[sub Ga], was investigated by slow positron annihilation. Dependence of defect contents on doping was studied by Si and Be dopants. No free carriers are generated by n-type or p-type doping up to 10[sup 19] cm[sup [minus]3] Si or Be. Raman data indicate Be occupies Ga substitutional sites but Si atom is not substitutional. Si induces more As[sub Ga] in the layer. As As[sub Ga] increases, photoquenchable As[sub Ga] decreases. Fraction of photoquenchable defects correlates to defects within 3 nearest neighbor separations disrupting the metastability. Annealing reduces neutral As[sub Ga] content around 500C, similar to irradiation damaged and plastically deformed Ga[sub As], as opposed to bulk grown GaAs in which As[sub Ga]-related defects are stable up to 1100C. The lower temperature defect removal is due to V[sub Ga] enhanced diffusion of As[sub Ga] to As precipitates. The supersaturated V[sub GA] and also decreases during annealing. Annealing kinetics for As[sub Ga]-related defects gives 2.0 [plus minus] 0.3 eV and 1.5 [plus minus] 0.3 eV migration enthalpies for the As[sub Ga] and V[sub Ga]. This represents the difference between Ga and As atoms hopping into the vacancy. The non-photoquenchable As[sub Ga]-related defects anneal with an activation energy of 1.1 [plus minus] 0.3eV. Be acceptors can be activated by 800C annealing. Temperature difference between defect annealing and Be activation formation of As[sub Ga]-Be[sub Ga] pairs. Si donors can only be partially activated.

  4. Defect studies in low-temperature-grown GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Bliss, David Emory [Univ. of California, Berkeley, CA (United States)

    1992-11-01

    High content of excess As is incorporated in GaAs grown by low-temperature molecular-beam-epitaxy (LTMBE). The excess As exists primarily as As antisite defects AsGa and a lesser extent of gallium vacancies VGa. The neutral AsGa-related defects were measured by infrared absorption at 1μm. Gallium vacancies, VGa, was investigated by slow positron annihilation. Dependence of defect contents on doping was studied by Si and Be dopants. No free carriers are generated by n-type or p-type doping up to 1019 cm-3 Si or Be. Raman data indicate Be occupies Ga substitutional sites but Si atom is not substitutional. Si induces more AsGa in the layer. As AsGa increases, photoquenchable AsGa decreases. Fraction of photoquenchable defects correlates to defects within 3 nearest neighbor separations disrupting the metastability. Annealing reduces neutral AsGa content around 500C, similar to irradiation damaged and plastically deformed GaAs, as opposed to bulk grown GaAs in which AsGa-related defects are stable up to 1100C. The lower temperature defect removal is due to VGa enhanced diffusion of AsGa to As precipitates. The supersaturated VGa and also decreases during annealing. Annealing kinetics for AsGa-related defects gives 2.0 ± 0.3 eV and 1.5 ± 0.3 eV migration enthalpies for the AsGa and VGa. This represents the difference between Ga and As atoms hopping into the vacancy. The non-photoquenchable AsGa-related defects anneal with an activation energy of 1.1 ± 0.3eV. Be acceptors can be activated by 800C annealing. Temperature difference between defect annealing and Be activation formation of AsGa-BeGa pairs. Si donors can only be partially activated.

  5. Atomistic simulation of the point defects in TaW ordered alloy

    Indian Academy of Sciences (India)

    Zhong-Liang Lin; Jian-Min Zhang; Yan Zhang; Vincent Ji

    2011-01-01

    Combining molecular dynamics (MD) simulation with modified analytic embeddedatom method (MAEAM), the formation, migration and activation energies of the point defects for six-kind migration mechanisms in B2-type TaW alloy have been investigated. The results showed that the anti-site defects TaW and WTa were easier to form than Ta and W vacancies owing to their lower formation energies. Comparing the migration and activation energies needed for six-kind migration mechanisms of a Ta (or W) vacancy, we found that one nearest-neighbour jump (1NNJ) was the most favourable because of its lowest migration and activation energies, but it would lead to a disorder in the alloy. One next-nearest-neighbour jump (1NNNJ) and one third-nearest-neighbour jump (1TNNJ) could maintain the ordered property of the alloy but required higher migration and activation energies. So the 1NNNJ and 1TNNJ should be replaced by straight [100] six nearestneighbor cyclic jumps (S[100]6NNCJ) (especially) or bent [100] six nearest-neighbour cyclic jumps (B[100]6NNCJ) and [110] six nearest-neighbor cyclic jumps ([110]6NNCJ), respectively.

  6. Interregional migration flows in Indonesia

    NARCIS (Netherlands)

    Wajdi, N.; van Wissen, L.J.G.; Mulder, C.H.

    2015-01-01

    Population Census and Intercensal Population Survey data permit description of the origin–destination patterns that characterize interregional migration flows in Indonesia. Application of the framework of population redistribution proposed by Long (1985) results in indications of over-urbanization,

  7. Quantifying global international migration flows.

    Science.gov (United States)

    Abel, Guy J; Sander, Nikola

    2014-03-28

    Widely available data on the number of people living outside of their country of birth do not adequately capture contemporary intensities and patterns of global migration flows. We present data on bilateral flows between 196 countries from 1990 through 2010 that provide a comprehensive view of international migration flows. Our data suggest a stable intensity of global 5-year migration flows at ~0.6% of world population since 1995. In addition, the results aid the interpretation of trends and patterns of migration flows to and from individual countries by placing them in a regional or global context. We estimate the largest movements to occur between South and West Asia, from Latin to North America, and within Africa.

  8. Minimum wages, earnings, and migration

    National Research Council Canada - National Science Library

    Boffy-Ramirez, Ernest

    2013-01-01

    Does increasing a state’s minimum wage induce migration into the state? Previous literature has shown mobility in response to welfare benefit differentials across states, yet few have examined the minimum wage as a cause of mobility...

  9. A low-cost, multiplexed μECoG system for high-density recordings in freely moving rodents

    Science.gov (United States)

    Insanally, Michele; Trumpis, Michael; Wang, Charles; Chiang, Chia-Han; Woods, Virginia; Palopoli-Trojani, Kay; Bossi, Silvia; Froemke, Robert C.; Viventi, Jonathan

    2016-04-01

    Objective. Micro-electrocorticography (μECoG) offers a minimally invasive neural interface with high spatial resolution over large areas of cortex. However, electrode arrays with many contacts that are individually wired to external recording systems are cumbersome and make recordings in freely behaving rodents challenging. We report a novel high-density 60-electrode system for μECoG recording in freely moving rats. Approach. Multiplexed headstages overcome the problem of wiring complexity by combining signals from many electrodes to a smaller number of connections. We have developed a low-cost, multiplexed recording system with 60 contacts at 406 μm spacing. We characterized the quality of the electrode signals using multiple metrics that tracked spatial variation, evoked-response detectability, and decoding value. Performance of the system was validated both in anesthetized animals and freely moving awake animals. Main results. We recorded μECoG signals over the primary auditory cortex, measuring responses to acoustic stimuli across all channels. Single-trial responses had high signal-to-noise ratios (SNR) (up to 25 dB under anesthesia), and were used to rapidly measure network topography within ∼10 s by constructing all single-channel receptive fields in parallel. We characterized evoked potential amplitudes and spatial correlations across the array in the anesthetized and awake animals. Recording quality in awake animals was stable for at least 30 days. Finally, we used these responses to accurately decode auditory stimuli on single trials. Significance. This study introduces (1) a μECoG recording system based on practical hardware design and (2) a rigorous analytical method for characterizing the signal characteristics of μECoG electrode arrays. This methodology can be applied to evaluate the fidelity and lifetime of any μECoG electrode array. Our μECoG-based recording system is accessible and will be useful for studies of perception and decision

  10. Birth Defects Research and Tracking

    Science.gov (United States)

    ... used data from the National Birth Defects Prevention Study (NBDPS) to examine maternal asthma medication use during pregnancy and the risk of certain birth defects. (Published October 22, 2014) World Down Syndrome Day Read one mother’s reflection on the birth ...

  11. Calculating charged defects using CRYSTAL

    Science.gov (United States)

    Bailey, Christine L.; Liborio, Leandro; Mallia, Giuseppe; Tomić, Stanko; Harrison, Nicholas M.

    2010-07-01

    The methodology for the calculation of charged defects using the CRYSTAL program is discussed. Two example calculations are used to illustrate the methodology: He+ ions in a vacuum and two intrinsic charged defects, Cu vacancies and Ga substitution for Cu, in the chalcopyrite CuGaS2.

  12. Facts about Atrial Septal Defect

    Science.gov (United States)

    ... Living With Heart Defects Data & Statistics Tracking & Research Articles & Key Findings Free Materials Multimedia and Tools Links to Other Websites Information For... Media Policy Makers Facts about Atrial Septal Defect Language: English Español (Spanish) Recommend on Facebook Tweet Share Compartir ...

  13. Facts about Ventricular Septal Defect

    Science.gov (United States)

    ... Living With Heart Defects Data & Statistics Tracking & Research Articles & Key Findings Free Materials Multimedia and Tools Links to Other Websites Information For... Media Policy Makers Facts about Ventricular Septal Defect Language: English Español (Spanish) Recommend on Facebook Tweet Share Compartir ...

  14. Irradiation Defects in Silicon Crystal

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The application of irradiation in silicon crystal is introduced.The defects caused by irradiation are reviewed and some major ways of studying defects in irradiated silicon are summarized.Furthermore the problems in the investigation of irradiated silicon are discussed as well as its properties.

  15. Homeward bound: Yemeni return migration.

    Science.gov (United States)

    Colton, N A

    1993-01-01

    The author discusses the return migration of Yemenis from Saudi Arabia during the period 1970-1989. "Through the use of original, empirical data collected in Yemen, this article sheds light on who these returning migrants are, where they have come from, and what sort of future awaits them.... The survey conducted on return migration was administered in the winter and spring of 1989 in a region of North Yemen called al-Hujariyya."

  16. Migration and Deforestation in Indonesia

    OpenAIRE

    Darmawan, Rivayani; Klasen, Stephan; Nuryartono, Nunung

    2015-01-01

    Indonesia now has the highest deforestation rate in the world, with an average increase of about 47,600 ha per year. As a result, the nation is one of the largest emitters of greenhouse gases in the world and putting its rich biodiversity at risk. Although the literature discussing the political economy of Indonesia commercial's logging is growing, only a small amount focuses on the relationship between migration and deforestation. Migration may contribute to the forest cover change, as migra...

  17. Zero Overhead Java Thread Migration

    OpenAIRE

    Bouchenak, Sara; Hagimont, Daniel

    2002-01-01

    The wide diffusion of Java is partly due to its mechanisms for mobile computing. Java provides most of the functions required to implement mobile applications, essentially code mobility (i.e., dynamic class loading) and data mobility (i.e., object serialization). However, Java does not provide any mechanism for the mobility of the computation (i.e., threads migration). Several projects have addressed the issue of Java thread migration- , e.g.,Sumatra, Wasp, JavaGo, Brakes, CIA. Most of these ...

  18. Simple rules guide dragonfly migration

    OpenAIRE

    Wikelski, Martin; Moskowitz, David; Adelman, James S; Cochran, Jim; Wilcove, David S; May, Michael L

    2006-01-01

    Every year billions of butterflies, dragonflies, moths and other insects migrate across continents, and considerable progress has been made in understanding population-level migratory phenomena. However, little is known about destinations and strategies of individual insects. We attached miniaturized radio transmitters (ca 300 mg) to the thoraxes of 14 individual dragonflies (common green darners, Anax junius) and followed them during their autumn migration for up to 12 days, using receiver-e...

  19. articles: Describing migration spatial structure

    OpenAIRE

    Andrei Rogers; Frans Willekens; James Raymer; Jani Little

    2002-01-01

    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 definition in this article, one that draws on the log-linear specification of the geographer's spatial interaction model. We illustrate our definition with observed migration data, we discuss extens...

  20. Integrated modeling of European migration

    OpenAIRE

    Raymer, James; Wiśniowski, Arkadiusz; Forster, Jonathan J.; Peter W. F. Smith; Bijak, Jakub

    2013-01-01

    International migration data in Europe are collected by individual countries with separate collection systems and designs. As a result, reported data are inconsistent in availability, definition and quality. In this paper, we propose a Bayesian model to overcome the limitations of the various data sources. The focus is on estimating recent international migration flows amongst 31 countries in the European Union and European Free Trade Association from 2002 to 2008, using data collated by Euro...

  1. Holographic Chern-Simons Defects

    CERN Document Server

    Fujita, Mitsutoshi; Meyer, Rene; Sugimoto, Shigeki

    2016-01-01

    We study SU(N) Yang-Mills-Chern-Simons theory in the presence of defects that shift the Chern-Simons level from a holographic point of view by embedding the system in string theory. The model is a D3-D7 system in Type IIB string theory, whose gravity dual is given by the AdS soliton background with probe D7-branes attaching to the AdS boundary along the defects. We holographically renormalize the free energy of the defect system with sources, from which we obtain the correlation functions for certain operators naturally associated to these defects. We find interesting phase transitions when the separation of the defects as well as the temperature are varied. We also discuss some implications for the Fractional Quantum Hall Effect and for two-dimensional QCD.

  2. 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.

  3. 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 m......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...... 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...... in the population of the species. The papers show that adult and juvenile birds can use different migration strategies depending on time of season and prevailing conditions. Also, the fuel loads of some individuals were theoretically sufficient for a direct flight to important goal area, but whether they do so...

  4. Inhibition of HMG CoA reductase reveals an unexpected role for cholesterol during PGC migration in the mouse

    Directory of Open Access Journals (Sweden)

    Ewing Andrew G

    2008-12-01

    Full Text Available Abstract Background Primordial germ cells (PGCs are the embryonic precursors of the sperm and eggs. Environmental or genetic defects that alter PGC development can impair fertility or cause formation of germ cell tumors. Results We demonstrate a novel role for cholesterol during germ cell migration in mice. Cholesterol was measured in living tissue dissected from mouse embryos and was found to accumulate within the developing gonads as germ cells migrate to colonize these structures. Cholesterol synthesis was blocked in culture by inhibiting the activity of HMG CoA reductase (HMGCR resulting in germ cell survival and migration defects. These defects were rescued by co-addition of isoprenoids and cholesterol, but neither compound alone was sufficient. In contrast, loss of the last or penultimate enzyme in cholesterol biosynthesis did not alter PGC numbers or position in vivo. However embryos that lack these enzymes do not exhibit cholesterol defects at the stage at which PGCs are migrating. This demonstrates that during gestation, the cholesterol required for PGC migration can be supplied maternally. Conclusion In the mouse, cholesterol is required for PGC survival and motility. It may act cell-autonomously by regulating clustering of growth factor receptors within PGCs or non cell-autonomously by controlling release of growth factors required for PGC guidance and survival.

  5. Radiation-induced defects in clay minerals: A review

    Energy Technology Data Exchange (ETDEWEB)

    Allard, Th., E-mail: thierry.allard@impmc.upmc.fr [IMPMC, UMR CNRS 7590, Universite Pierre et Marie Curie, Universite Denis Diderot, IRD, IPGP, Case 115, 4 Place Jussieu, 75005 Paris (France); Balan, E.; Calas, G.; Fourdrin, C.; Morichon, E.; Sorieul, S. [IMPMC, UMR CNRS 7590, Universite Pierre et Marie Curie, Universite Denis Diderot, IRD, IPGP, Case 115, 4 Place Jussieu, 75005 Paris (France)

    2012-04-15

    Extensive information has been collected on radiation effects on clay minerals over the last 35 years, providing a wealth of information on environmental and geological processes. The fields of applications include the reconstruction of past radioelement migrations, the dating of clay minerals or the evolution of the physico-chemical properties under irradiation. The investigation of several clay minerals, namely kaolinite, dickite, montmorillonite, illite and sudoite, by Electron Paramagnetic Resonance Spectroscopy has shown the presence of defects produced by natural or artificial radiations. These defects consist mostly of electron holes located on oxygen atoms of the structure. The various radiation-induced defects are differentiated through their nature and their thermal stability. Most of them are associated with a {pi} orbital on a Si-O bond. The most abundant defect in clay minerals is oriented perpendicular to the silicate layer. Thermal annealing indicates this defect in kaolinite (A-center) to be stable over geological periods at ambient temperature. Besides, electron or heavy ion irradiation easily leads to an amorphization in smectites, depending on the type of interlayer cation. The amorphization dose exhibits a bell-shaped variation as a function of temperature, with a decreasing part that indicates the influence of thermal dehydroxylation. Two main applications of the knowledge of radiation-induced defects in clay minerals are derived: (i) The use of defects as tracers of past radioactivity. In geological systems where the age of the clay can be constrained, ancient migrations of radioelements can be reconstructed in natural analogues of high level nuclear waste repositories. When the dose rate may be assumed constant over time, the paleodose is used to date clay populations, an approach applied to fault gouges or laterites of the Amazon basin. (ii) The influence of irradiation over physico-chemical properties of clay minerals. An environmental

  6. Direct observation of hydration of TiO 2 on Ti using electrochemical AFM: freely corroding versus potentiostatically held

    Science.gov (United States)

    Bearinger, Jane P.; Orme, Christine A.; Gilbert, Jeremy L.

    2001-10-01

    Hydration of titanium/titanium oxide surfaces under freely corroding and potentiostatically held conditions has been characterized using electrochemical atomic force microscopy (EC AFM). In contrast to conventional high vacuum techniques, AFM enables measurement of morphological surface structure in the in situ hydrated state. Electrochemical probes in the imaging environment further enable acquisition of electrical characteristics during AFM imaging. Experiments were performed on etched, electropolished commercially pure titanium. As noted by direct observation and corroborated by power spectral density (Fourier analysis) measurements, oxide domes cover the titanium surface and grow laterally during hydration. Applied potential altered the growth rate. Under open circuit potential conditions, growth proceeded approximately six times faster than under a -1 V applied voltage ( 1098±52 nm2/ min ± versus 184.84±19 nm2/min). Film growth increased electrical resistance and lowered interfacial capacitance based on step polarization impedance spectroscopy tests.

  7. Effect of pyrolysis temperatures on freely dissolved polycyclic aromatic hydrocarbon (PAH) concentrations in sewage sludge-derived biochars.

    Science.gov (United States)

    Zielińska, Anna; Oleszczuk, Patryk

    2016-06-01

    The aim of this study was to evaluate the effect of sewage sludge pyrolysis on freely dissolved (Cfree) polycyclic aromatic hydrocarbon (PAH) contents in biochars. Four sewage sludges with varying properties and PAH contents were pyrolysed at temperatures of 500 °C, 600 °C or 700 °C. Cfree PAH contents were determined using polyoxymethylene (POM). The contents of Cfree PAHs in the sludges ranged from 262 to 294 ng L(-1). Sewage sludge-derived biochars have from 2.3- to 3.4-times lower Cfree PAH contents comparing to corresponding sewage sludges. The Cfree PAH contents in the biochars ranged between 81 ng L(-1) and 126 ng L(-1). As regards agricultural use of biochar, the lower contents of Cfree PAHs in the biochars compared to the sewage sludges makes biochar a safer material than sewage sludge in terms of PAH contents.

  8. Using disposable solid-phase microextraction (SPME) to determine the freely dissolved concentration of polybrominated diphenyl ethers (PBDEs) in sediments.

    Science.gov (United States)

    Jia, Fang; Cui, Xinyi; Wang, Wei; Delgado-Moreno, Laura; Gan, Jay

    2012-08-01

    Polybrominated diphenyl ethers (PBDEs) are brominated flame retardants (BFRs). The ubiquity and persistence of PBDEs in sediment have raised concerns over their environmental fate and ecological risks. Due to strong affinity for sediment organic matter, environmental fate and bioavailability of PBDEs closely depend on their phase distribution. In this study, disposable polydimethylsiloxane (PDMS) fiber was used to derive the freely dissolved concentration (C(free)) of PBDEs in sediment porewater as a measurement of bioavailability. The PDMS-to-water partition coefficient (log K(PDMS)) was 5.46-5.83 for BDE 47, 99, and 153. In sediments, PBDEs were predominantly sorbed to the sediment phase, with C(free) accounting for PBDEs decreased as their bromination or sediment organic carbon content increased. The strong association with dissolved organic matter (DOM) implies a potential for facilitated offsite transport and dispersion in the environment that depends closely on the stability of sediment aggregates.

  9. Imaging brain activity during seizures in freely behaving rats using a miniature multi-modal imaging system.

    Science.gov (United States)

    Sigal, Iliya; Koletar, Margaret M; Ringuette, Dene; Gad, Raanan; Jeffrey, Melanie; Carlen, Peter L; Stefanovic, Bojana; Levi, Ofer

    2016-09-01

    We report on a miniature label-free imaging system for monitoring brain blood flow and blood oxygenation changes in awake, freely behaving rats. The device, weighing 15 grams, enables imaging in a ∼ 2 × 2 mm field of view with 4.4 μm lateral resolution and 1 - 8 Hz temporal sampling rate. The imaging is performed through a chronically-implanted cranial window that remains optically clear between 2 to > 6 weeks after the craniotomy. This imaging method is well suited for longitudinal studies of chronic models of brain diseases and disorders. In this work, it is applied to monitoring neurovascular coupling during drug-induced absence-like seizures 6 weeks following the craniotomy.

  10. Instrumentation for fast-scan cyclic voltammetry combined with electrophysiology for behavioral experiments in freely moving animals

    Science.gov (United States)

    Takmakov, Pavel; McKinney, Collin J.; Carelli, Regina M.; Wightman, R. Mark

    2011-07-01

    Fast-scan cyclic voltammetry is a unique technique for sampling dopamine concentration in the brain of rodents in vivo in real time. The combination of in vivo voltammetry with single-unit electrophysiological recording from the same microelectrode has proved to be useful in studying the relationship between animal behavior, dopamine release and unit activity. The instrumentation for these experiments described here has two unique features. First, a 2-electrode arrangement implemented for voltammetric measurements with the grounded reference electrode allows compatibility with electrophysiological measurements, iontophoresis, and multielectrode measurements. Second, we use miniaturized electronic components in the design of a small headstage that can be fixed on the rat's head and used in freely moving animals.

  11. SAGES: a suite of freely-available software tools for electronic disease surveillance in resource-limited settings.

    Directory of Open Access Journals (Sweden)

    Sheri L Lewis

    Full Text Available Public health surveillance is undergoing a revolution driven by advances in the field of information technology. Many countries have experienced vast improvements in the collection, ingestion, analysis, visualization, and dissemination of public health data. Resource-limited countries have lagged behind due to challenges in information technology infrastructure, public health resources, and the costs of proprietary software. The Suite for Automated Global Electronic bioSurveillance (SAGES is a collection of modular, flexible, freely-available software tools for electronic disease surveillance in resource-limited settings. One or more SAGES tools may be used in concert with existing surveillance applications or the SAGES tools may be used en masse for an end-to-end biosurveillance capability. This flexibility allows for the development of an inexpensive, customized, and sustainable disease surveillance system. The ability to rapidly assess anomalous disease activity may lead to more efficient use of limited resources and better compliance with World Health Organization International Health Regulations.

  12. Real-time, continuous, fluorescence sensing in a freely-moving subject with an implanted hybrid VCSEL/CMOS biosensor

    Science.gov (United States)

    O’Sullivan, Thomas D.; Heitz, Roxana T.; Parashurama, Natesh; Barkin, David B.; Wooley, Bruce A.; Gambhir, Sanjiv S.; Harris, James S.; Levi, Ofer

    2013-01-01

    Performance improvements in instrumentation for optical imaging have contributed greatly to molecular imaging in living subjects. In order to advance molecular imaging in freely moving, untethered subjects, we designed a miniature vertical-cavity surface-emitting laser (VCSEL)-based biosensor measuring 1cm3 and weighing 0.7g that accurately detects both fluorophore and tumor-targeted molecular probes in small animals. We integrated a critical enabling component, a complementary metal-oxide semiconductor (CMOS) read-out integrated circuit, which digitized the fluorescence signal to achieve autofluorescence-limited sensitivity. After surgical implantation of the lightweight sensor for two weeks, we obtained continuous and dynamic fluorophore measurements while the subject was un-anesthetized and mobile. The technology demonstrated here represents a critical step in the path toward untethered optical sensing using an integrated optoelectronic implant. PMID:24009996

  13. Dual-channel telemetry system for recording vocalization-correlated neuronal activity in freely moving squirrel monkeys.

    Science.gov (United States)

    Grohrock, P; Häusler, U; Jürgens, U

    1997-09-05

    A miniature telemetric system is described which allows simultaneous measurements of neural activity and vocalization in freely moving monkeys within their social group. Single and multi-unit activities were detected with medium impedance electrodes that were fixed to self-made microdrives allowing accurate vertical positioning over a range of 8 mm. Vocalizations were registered by means of a piezo-ceramic device sensing the vocalization-induced skull vibrations. This allowed identification of the vocalizing animal in a larger group and eliminated environmental noise. Neuronal activity and vocalization were transmitted via separate channels of a FM transmitter using different carrier frequencies. The signals were decoded in two conventional FM receivers equipped with an automatic frequency control. The signals were stored for off-line analysis on a HiFi videotape recorder.

  14. A Comparison of Urge Intensity and the Probability of Tic Completion During Tic Freely and Tic Suppression Conditions.

    Science.gov (United States)

    Specht, Matt W; Nicotra, Cassandra M; Kelly, Laura M; Woods, Douglas W; Ricketts, Emily J; Perry-Parrish, Carisa; Reynolds, Elizabeth; Hankinson, Jessica; Grados, Marco A; Ostrander, Rick S; Walkup, John T

    2014-03-01

    Tic-suppression-based treatments (TSBTs) represent a safe and effective treatment option for Chronic Tic Disorders (CTDs). Prior research has demonstrated that treatment naive youths with CTDs have the capacity to safely and effectively suppress tics for prolonged periods. It remains unclear how tic suppression is achieved. The current study principally examines how effective suppression is achieved and preliminary correlates of the ability to suppress tics. Twelve youths, ages 10 to 17 years, with moderate-to-marked CTDs participated in an alternating sequence of tic freely and reinforced tic suppression conditions during which urge intensity and tic frequency were frequently assessed. Probability of tics occurring was half as likely following high-intensity urges during tic suppression (31%) in contrast to low-intensity urges during tic freely conditions (60%). Age was not associated with ability to suppress. Intelligence indices were associated with or trended toward greater ability to suppress tics. Attention difficulties were not associated with ability to suppress but were associated with tic severity. In contrast to our "selective suppression" hypothesis, we found participants equally capable of suppressing their tics regardless of urge intensity during reinforced tic suppression. Tic suppression was achieved with an "across-the-board" effort to resist urges. Preliminary data suggest that ability to suppress may be associated with general cognitive variables rather than age, tic severity, urge severity, and attention. Treatment naive youths appear to possess a capacity for robust tic suppression. TSBTs may bolster these capacities and/or enable their broader implementation, resulting in symptom improvement.

  15. The Wageningen Lowland Runoff Simulator (WALRUS): implementation and application to the freely draining Hupsel Brook catchment and controlled Cabauw polder

    Science.gov (United States)

    Brauer, Claudia; Torfs, Paul; Teuling, Ryan; Uijlenhoet, Remko

    2014-05-01

    Recently, we developed the Wageningen Lowland Runoff Simulator (WALRUS) to fill the gap between complex, spatially distributed models which are often used in lowland catchments and simple, parametric models which have mostly been developed for mountainous catchments. This parametric rainfall-runoff model can be used all over the world in both freely draining lowland catchments and polders with controlled water levels. Here, we present the model implementation, opportunities for practical application and experience from validation studies with data from two field sites. The open source model code is implemented in R and is set-up such that it can be used by both practitioners and researchers. For direct use by practitioners, defaults are implemented for relations between model variables and to compute initial conditions, leaving only four parameters which require calibration. For research purposes, the defaults can easily be changed. WALRUS is computationally efficient, which allows operational forecasting and uncertainty estimation by creating ensembles. An approach for flexible time steps increases numerical stability and makes model parameter values independent of time step size, which facilitates use of the model with the same parameter set for multi-year water balance studies as well as detailed analyses of individual flood peaks. We applied WALRUS to two contrasting Dutch catchments: the slightly sloping, freely draining Hupsel Brook catchment and the flat Cabauw polder with controlled water levels. In both catchments, WALRUS performs well during the years used for calibration and validation. The model also performs well during extremely wet periods (flash flood in the Hupsel Brook catchment in August 2010) and extremely dry periods (summer 1976) and can forecast the effect of control operations (changing weir elevations and surface water supply).

  16. 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 their…

  17. 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…

  18. Kinematic artifacts in prestack depth migration.

    NARCIS (Netherlands)

    Stolk, C.C.; Symes, W.W.

    2004-01-01

    Strong refraction of waves in the migration velocity model introduces kinematic artifacts¿coherent events not corresponding to actual reflectors¿into the image volumes produced by prestack depth migration applied to individual data bins. Because individual bins are migrated independently, the migrat

  19. Influence of radiation induced defect clusters on silicon particle detectors

    Energy Technology Data Exchange (ETDEWEB)

    Junkes, Alexandra

    2011-10-15

    exhibits a bistability, as does the leakage current. In oxygen rich material the defect transforms (V{sub 3} activation energy for migration E{sub a} = 1.77 {+-} 0.08 eV) to the L defect, which can be assigned to the V{sub 3}O defect. In the second part of this work, it is demonstrated that the radiation induced effective doping concentration can be attributed to the generation of three deep acceptors (H(116K), H(140K), H(151K)), two donors (BD defect and E(30K)) and the vacancyphosphorus defect VP. The reverse annealing of the effective doping concentration is presented for samples irradiated with neutrons for fluences up to {phi}=10{sup 15} cm{sup -2}. From defect concentrations it is possible to reproduce the effective doping concentration as extracted from capacitance-voltage characteristics. The last part of this work deals with the characterisation of Float Zone pad sensors in the frame of the CMS tracker upgrade programme. Due to a new production process, several material defects were introduced in the sensors. They explain unexpected electrical properties in thin sensors. (orig.)

  20. Interplay between intrinsic point defects and low-angle grain boundary in bcc tungsten: effects of local stress field.

    Science.gov (United States)

    Niu, Liang-Liang; Zhang, Ying; Shu, Xiaolin; Jin, Shuo; Zhou, Hong-Bo; Gao, Fei; Lu, Guang-Hong

    2015-07-01

    We have used molecular statics in conjunction with an embedded atom method to explore the interplay between native point defects (vacancies and self-interstitials (SIAs)) and a low-angle grain boundary (GB) in bcc tungsten. The low-angle GB has biased absorption of SIAs over vacancies. We emphasize the significance of phenomena such as vacancy delocalization and SIA instant absorption around the GB dislocation cores in stabilizing the defect structures. Interstitial loading into the GB can dramatically enhance the interaction strength between the point defects and the GB due to SIA clustering (SIA cloud formation) or SIA vacancy recombination. We propose that the 'maximum atom displacement' can complement the 'vacancy formation energy' in evaluating unstable vacancy sites. Calculations of point defect migration barriers in the vicinity of GB dislocation cores show that vacancies and SIAs preferentially migrate along the pathways in the planes immediately above and below the core, respectively.

  1. Interplay between intrinsic point defects and low-angle grain boundary in bcc tungsten: effects of local stress field

    Science.gov (United States)

    Niu, Liang-Liang; Zhang, Ying; Shu, Xiaolin; Jin, Shuo; Zhou, Hong-Bo; Gao, Fei; Lu, Guang-Hong

    2015-06-01

    We have used molecular statics in conjunction with an embedded atom method to explore the interplay between native point defects (vacancies and self-interstitials (SIAs)) and a low-angle grain boundary (GB) in bcc tungsten. The low-angle GB has biased absorption of SIAs over vacancies. We emphasize the significance of phenomena such as vacancy delocalization and SIA instant absorption around the GB dislocation cores in stabilizing the defect structures. Interstitial loading into the GB can dramatically enhance the interaction strength between the point defects and the GB due to SIA clustering (SIA cloud formation) or SIA vacancy recombination. We propose that the ‘maximum atom displacement’ can complement the ‘vacancy formation energy’ in evaluating unstable vacancy sites. Calculations of point defect migration barriers in the vicinity of GB dislocation cores show that vacancies and SIAs preferentially migrate along the pathways in the planes immediately above and below the core, respectively.

  2. The role of point defects in PbS, PbSe and PbTe: a first principles study.

    Science.gov (United States)

    Li, Wun-Fan; Fang, Chang-Ming; Dijkstra, Marjolein; van Huis, Marijn A

    2015-09-09

    Intrinsic defects are of central importance to many physical and chemical processes taking place in compound nanomaterials, such as photoluminescence, accommodation of off-stoichiometry and cation exchange. Here, the role of intrinsic defects in the above mentioned processes inside rock salt (RS) lead chalcogenide systems PbS, PbSe and PbTe (PbX) was studied systematically using first principles density functional theory. Vacancy, interstitial, Schottky and Frenkel defects were considered. Rock salt PbO was included for comparison. The studied physical properties include defect formation energy, local geometry relaxation, Bader charge analysis, and electronic structure. The defect formation energies show that monovacancy defects and Schottky defects are favoured over interstitial and Frenkel defects. Schottky dimers, where the cation vacancy and anion vacancy are adjacent to each other, have the lowest defect formation energies at 1.27 eV, 1.29 eV and 1.21 eV for PbS, PbSe and PbTe, respectively. Our results predict that a Pb monovacancy gives rise to a shallow acceptor state, while an X vacancy generates a deep donor state, and Schottky defects create donor-acceptor pairs inside the band gap. The surprisingly low formation energy of Schottky dimers suggests that they may play an important role in cation exchange processes, in contrast to the current notion that only single point defects migrate during cation exchange.

  3. Evolution of secondary defects in arsenic implanted Si

    Science.gov (United States)

    Zhu, He; Wang, Miao; Zhang, Bingpo; Wu, Huizhen; Sun, Yan; Hu, Gujin; Dai, Ning

    2016-04-01

    Behavior of defects in ion-implanted semiconductors is an everlasting topic and becomes even more critical as semiconductor devices continuously shrink and ion implantation technique has been increasingly employed. High resolution transmission electron microscope (HRTEM) and energy dispersive X-ray (EDX) were employed to investigate the structural evolution of arsenic (As) implanted silicon (Si). Project range (PR) defects and end of range (EOR) dislocations are observed via HRTEM. EDX characterization proves the two types of defects are related to dopant atoms precipitations. The sizes of both PR defects and EOR dislocations enlarge at the expense of small ones with the elevation of annealing temperature. The characterizations of electrochemical capacitance-voltage and EDX conclude that the SiO2/Si interface is playing an indispensable role in the deactivation of dopant atoms during the annealing process. As atoms are detected in the As-implanted Si region near the SiO2/Si interface but not in the silica layer. Nanoparticles composed of Si atoms in the silica layer are observed in the 1150 °C-annealed samples, which proves the migration of oxygen atoms at the SiO2/Si interface.

  4. Orthodontic intrusive movement to reduce infrabony defects in periodontal pacients

    Directory of Open Access Journals (Sweden)

    Aldrieli Regina Ambrósio

    2008-01-01

    Full Text Available The adult tends to be an excellent orthodontic patient, because he/she is motivated and cooperative. Nevertheless, many adult patientspresent periodontal problems. Intrusive movement is usually necessary against an area with infrabony defects, and in order for treatmentto be successful, it is necessary for all related aspects to be well understood. The aim of this study was to discuss the feasibility and efficacy of orthodontic intrusion as a means of reducing infrabony defects caused by periodontal disease. The methodology used was reviewed in the literature, from which articles were selected using the MEDLINE, LILACS and BBO databases. After periodontal treatment and maintenance with suitable bacterial plaque control has been performed, orthodontic treatment with intrusive tooth movement can be performed in case of pathological tooth migration and extrusion. The segmented arch technique is the most indicated for intruding teeth with infrabony defects because it is capable of developing light and continuous forces. Furthermore, although studies did not confirm, they suggested that orthodontic intrusion could lead to the formation of new periodontal support tissue. With a multidisciplinary approach, it is possible to successfully perform intrusion movements in teeth that present infrabony defects, provided that periodontal inflammation has been treated and the patient presents an excellent level of plaque control. Among the benefits of this approach are: better appearance, better access to dental hygiene, restitution of incisal occlusion and reduction in non axial load.

  5. International migration: a global challenge.

    Science.gov (United States)

    Martin, P; Widgren, J

    1996-04-01

    Trends in international migration are presented in this multiregional analysis. Seven of the world's wealthiest countries have about 33% of the world's migrant population, but under 16% of the total world population. Population growth in these countries is substantially affected by the migrant population. The migration challenge is external and internal. The external challenge is to balance the need for foreign labor and the commitment to human rights for those migrants seeking economic opportunity and political freedom. The internal challenge is to assure the social adjustment of immigrants and their children and to integrate them into society as citizens and future leaders. Why people cross national borders and how migration flows are likely to evolve over the next decades are explained. This report also presents some ways that countries can manage migration or reduce the pressures which force people to migrate. It is recommended that receiving nations control immigration by accelerating global economic growth and reducing wars and human rights violations. This report examines the impact of immigration on international trade, aid, and direct intervention policies. Although migration is one of the most important international economic issues, it is not coordinated by an international group. The European experience indicates that it is not easy to secure international cooperation on issues that affect national sovereignty. It is suggested that countries desiring control of their borders should remember that most people never cross national borders to live or work in another country, that 50% of the world's migrants move among developing countries, and that countries can shift from being emigration to immigration countries. The author suggests that sustained reductions in migration pressure are a better alternative than the "quick fixes" that may invite the very much feared mass and unpredictable movements.

  6. Forecasting of Interregional Migration Flows

    Directory of Open Access Journals (Sweden)

    Yuriy Davydovich Shmidt

    2017-03-01

    Full Text Available The article explores the problem of interregional migration flows modelling. As a rule, the existing models of interregional migration flows use the aggregated data and do not take into consideration the fact that a decision to relocate is formed and taken at the micro-level, at the level of households. The purpose of the present research is to develop the forecasting method for interregional migration flows of the region taking into consideration the behaviour of households at the micro-level. The research tests the hypothesis that the modelling of household behaviours at the local level as regards taking a decision to relocate to other regions, which takes into account the existing interactions with relatives and other communities, allows to obtain adequate forecasts of interregional migration flows. To forecast the interregional migration flows of the region, we develop a methodological approach and software solution, based on cellular automaton model modification proposed in the current work and on econometric models of birth and death processes, which have been tested on the Primorsky Krai data. The authors’ model of the cellular automaton is a kind of the combined probabilistic cellular automaton in which the condition of each cell changes depending on a condition of four closest neighbours (von Neumann vicinity and four cells chosen in a random way. The article builds a mid-term forecast of Primorsky Krai interregional migration flows. The research demonstrates the possibility and reasonability of modelling the interregional migration flows by cellular automatons. The highly perspective direction of the research is the modelling of other macroeconomic processes based on modelling by cellular automatons of a behaviour of households, companies and other economic entities at the local level.

  7. 2010 Defects in Semiconductors GRC

    Energy Technology Data Exchange (ETDEWEB)

    Shengbai Zhang

    2011-01-06

    Continuing its tradition of excellence, this Gordon Conference will focus on research at the forefront of the field of defects in semiconductors. The conference will have a strong emphasis on the control of defects during growth and processing, as well as an emphasis on the development of novel defect detection methods and first-principles defect theories. Electronic, magnetic, and optical properties of bulk, thin film, and nanoscale semiconductors will be discussed in detail. In contrast to many conferences, which tend to focus on specific semiconductors, this conference will deal with point and extended defects in a broad range of electronic materials. This approach has proved to be extremely fruitful for advancing fundamental understanding in emerging materials such as wide-band-gap semiconductors, oxides, sp{sup 2} carbon based-materials, and photovoltaic/solar cell materials, and in understanding important defect phenomena such as doping bottleneck in nanostructures and the diffusion of defects and impurities. The program consists of about twenty invited talks and a number of contributed poster sessions. The emphasis should be on work which has yet to be published. The large amount of discussion time provides an ideal forum for dealing with topics that are new and/or controversial.

  8. Software Defect Detection with Rocus

    Institute of Scientific and Technical Information of China (English)

    Yuan Jiang; Ming Li; Zhi-Hua Zhou

    2011-01-01

    Software defect detection aims to automatically identify defective software modules for efficient software test in order to improve the quality of a software system. Although many machine learning methods have been successfully applied to the task, most of them fail to consider two practical yet important issues in software defect detection. First, it is rather difficult to collect a large amount of labeled training data for learning a well-performing model; second, in a software system there are usually much fewer defective modules than defect-free modules, so learning would have to be conducted over an imbalanced data set. In this paper, we address these two practical issues simultaneously by proposing a novel semi-supervised learning approach named Rocus. This method exploits the abundant unlabeled examples to improve the detection accuracy, as well as employs under-sampling to tackle the class-imbalance problem in the learning process. Experimental results of real-world software defect detection tasks show that Rocgs is effective for software defect detection. Its performance is better than a semi-supervised learning method that ignores the class-imbalance nature of the task and a class-imbalance learning method that does not make effective use of unlabeled data.

  9. 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...... for migration, migrating in a familiar environment (the local population); 2) previous opportunity for migration, migrating in an unfamiliar environment; and 3) no previous opportunity for seasonal migration, migrating in an unfamiliar environment. In addition, we evaluated the migration patterns of roach...

  10. DEFECTS SIMULATION OF ROLLING STRIP

    Directory of Open Access Journals (Sweden)

    Rudolf Mišičko

    2009-06-01

    Full Text Available The defects in the continuous casting slabs can be developed or kept down in principle by rolling technology, especially depend to sort, size and distribution of primary defects, as well as used of rolling parameters. Scope of the article is on observation behavior artificial surface and undersurface defects (scores without filler (surface defects and filling by oxides and casting powder (subsurface defects. First phase of hot rolling process have been done by software simulation DEFORM 3D setting to the limited condition for samples with surface defects. Samples of material with low-carbon steel of sizes h x b x l have been chosen and the surface defects shape „U” and „V” of scores have been injected artificially by software. The process of rolling have been simulated on the deformation temperatures 1200°C and 900°C, whereas on the both of this deformation temperatures have been applied amount of deformation 10 and 50 %. With respect to the process of computer simulation, it is not possible to truthful real oxidation condition (physical – chemical process during heat of metal, in the second phase of our investigation have been observed influence of oxides and casting powders inside the scores for a defect behavior in plastic deformation process (hot and cold rolling process in laboratory condition. The basic material was STN steel class 11 375, cladding material was steel on the bases C-Mn-Nb-V. Scores have been filled by scales to get from the heating temperatures (1100°C a 1250°C, varied types of casting powders, if you like mixture of scale and casting powders in the rate 1:4. The joint of the basic and cladding material have been done by peripheral welded joint. Experiment results from both phases are pointed on the evolution of original typology defects in rolling process.

  11. 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....

  12. International migration in Serbia: Facts and policies

    OpenAIRE

    Bobić Mirjana; Babović Marija

    2013-01-01

    In the absence of comprehensive, systematic and precize data on international migration in Serbia, and consequently the analysis of migration trends, their drivers and outcomes, the objective of this paper is to offer the review of contemporary migration flows in Serbia. International migration flows are observed in the context of semi-peripheral position of Serbia in the global system, and hindered transformation and development. Migrations are analyzed at the macro level, according to...

  13. Five Facts about Congenital Heart Defects

    Science.gov (United States)

    ... Button Past Emails CDC Features Five Facts about Congenital Heart Defects Language: English Español (Spanish) Recommend on Facebook Tweet Share Compartir Congenital heart defects are the most common types of birth defects. ...

  14. 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

  15. Cell migration in confined environments.

    Science.gov (United States)

    Irimia, Daniel

    2014-01-01

    We describe a protocol for measuring the speed of human neutrophils migrating through small channels, in conditions of mechanical confinement comparable to those experienced by neutrophils migrating through tissues. In such conditions, we find that neutrophils move persistently, at constant speed for tens of minutes, enabling precise measurements at single cells resolution, for large number of cells. The protocol relies on microfluidic devices with small channels in which a solution of chemoattractant and a suspension of isolated neutrophils are loaded in sequence. The migration of neutrophils can be observed for several hours, starting within minutes after loading the neutrophils in the devices. The protocol is divided into four main steps: the fabrication of the microfluidic devices, the separation of neutrophils from whole blood, the preparation of the assay and cell loading, and the analysis of data. We discuss the practical steps for the implementation of the migration assays in biology labs, the adaptation of the protocols to various cell types, including cancer cells, and the supplementary device features required for precise measurements of directionality and persistence during migration.

  16. [Mexican migration policies after IRCA].

    Science.gov (United States)

    Alba, F

    1999-01-01

    The evolution since 1964 of Mexican government policy regarding migrant workers in the US is discussed. For a decade after the "bracero" program was terminated by the US, the Mexican government attempted to encourage creation of another legal framework for migration, regarded as inevitable whether legal or clandestine. Around 1974-75, a more distant attitude, termed the "policy of no policy," acquired considerable support in Mexican government and academic circles. The no-policy strategy allowed Mexico to achieve certain objectives regarding migration without prompting US intervention in its internal affairs, as for example by a linkage of US migration policy to specific Mexican government actions. The 1986 passage of the US Immigration Reform and Control Act effectively ended the no-policy strategy that had allowed the Mexican government to count on the continued emigration of Mexican workers without compromising its position of promoting respect for migrant rights. The unilateral change in the status quo by the US led to substitution of the "policy of dialogue," a clear signal of the Mexican government's search for a new migration agreement. The policy of dialogue has entailed greater discussion of the two traditional Mexican objectives regarding migration. Some progress has apparently been made concerning migrant rights, but the second and less explicit objective, that of preventing abrupt changes in US immigration policy and in migratory flows, is harder to judge. The atmosphere of freer public debate in Mexico is politicizing migratory policy.

  17. A novel role for Lh3 dependent ECM modifications during neural crest cell migration in zebrafish.

    Directory of Open Access Journals (Sweden)

    Santanu Banerjee

    Full Text Available During vertebrate development, trunk neural crest cells delaminate along the entire length of the dorsal neural tube and initially migrate as a non-segmented sheet. As they enter the somites, neural crest cells rearrange into spatially restricted segmental streams. Extracellular matrix components are likely to play critical roles in this transition from a sheet-like to a stream-like mode of migration, yet the extracellular matrix components and their modifying enzymes critical for this transition are largely unknown. Here, we identified the glycosyltransferase Lh3, known to modify extracellular matrix components, and its presumptive substrate Collagen18A1, to provide extrinsic signals critical for neural crest cells to transition from a sheet-like migration behavior to migrating as a segmental stream. Using live cell imaging we show that in lh3 null mutants, neural crest cells fail to transition from a sheet to a stream, and that they consequently enter the somites as multiple streams, or stall shortly after entering the somites. Moreover, we demonstrate that transgenic expression of lh3 in a small subset of somitic cells adjacent to where neural crest cells switch from sheet to stream migration restores segmental neural crest cell migration. Finally, we show that knockdown of the presumptive Lh3 substrate Collagen18A1 recapitulates the neural crest cell migration defects observed in lh3 mutants, consistent with the notion that Lh3 exerts its effect on neural crest cell migration by regulating post-translational modifications of Collagen18A1. Together these data suggest that Lh3-Collagen18A1 dependent ECM modifications regulate the transition of trunk neural crest cells from a non-segmental sheet like migration mode to a segmental stream migration mode.

  18. A novel role for Lh3 dependent ECM modifications during neural crest cell migration in zebrafish.

    Science.gov (United States)

    Banerjee, Santanu; Isaacman-Beck, Jesse; Schneider, Valerie A; Granato, Michael

    2013-01-01

    During vertebrate development, trunk neural crest cells delaminate along the entire length of the dorsal neural tube and initially migrate as a non-segmented sheet. As they enter the somites, neural crest cells rearrange into spatially restricted segmental streams. Extracellular matrix components are likely to play critical roles in this transition from a sheet-like to a stream-like mode of migration, yet the extracellular matrix components and their modifying enzymes critical for this transition are largely unknown. Here, we identified the glycosyltransferase Lh3, known to modify extracellular matrix components, and its presumptive substrate Collagen18A1, to provide extrinsic signals critical for neural crest cells to transition from a sheet-like migration behavior to migrating as a segmental stream. Using live cell imaging we show that in lh3 null mutants, neural crest cells fail to transition from a sheet to a stream, and that they consequently enter the somites as multiple streams, or stall shortly after entering the somites. Moreover, we demonstrate that transgenic expression of lh3 in a small subset of somitic cells adjacent to where neural crest cells switch from sheet to stream migration restores segmental neural crest cell migration. Finally, we show that knockdown of the presumptive Lh3 substrate Collagen18A1 recapitulates the neural crest cell migration defects observed in lh3 mutants, consistent with the notion that Lh3 exerts its effect on neural crest cell migration by regulating post-translational modifications of Collagen18A1. Together these data suggest that Lh3-Collagen18A1 dependent ECM modifications regulate the transition of trunk neural crest cells from a non-segmental sheet like migration mode to a segmental stream migration mode.

  19. Molecular dissection of the migrating posterior lateral line primordium during early development in zebrafish

    Directory of Open Access Journals (Sweden)

    Villablanca Eduardo J

    2010-12-01

    Full Text Available Abstract Background Development of the posterior lateral line (PLL system in zebrafish involves cell migration, proliferation and differentiation of mechanosensory cells. The PLL forms when cranial placodal cells delaminate and become a coherent, migratory primordium that traverses the length of the fish to form this sensory system. As it migrates, the primordium deposits groups of cells called neuromasts, the specialized organs that contain the mechanosensory hair cells. Therefore the primordium provides both a model for studying collective directional cell migration and the differentiation of sensory cells from multipotent progenitor cells. Results Through the combined use of transgenic fish, Fluorescence Activated Cell Sorting and microarray analysis we identified a repertoire of key genes expressed in the migrating primordium and in differentiated neuromasts. We validated the specific expression in the primordium of a subset of the identified sequences by quantitative RT-PCR, and by in situ hybridization. We also show that interfering with the function of two genes, f11r and cd9b, defects in primordium migration are induced. Finally, pathway construction revealed functional relationships among the genes enriched in the migrating cell population. Conclusions Our results demonstrate that this is a robust approach to globally analyze tissue-specific expression and we predict that many of the genes identified in this study will show critical functions in developmental events involving collective cell migration and possibly in pathological situations such as tumor metastasis.

  20. Modeling of point defects and rare gas incorporation in uranium mono-carbide

    Science.gov (United States)

    Chartier, A.; Van Brutzel, L.

    2007-02-01

    An embedded atom method (EAM) potential has been established for uranium mono-carbide. This EAM potential was fitted on structural properties of metallic uranium and uranium mono-carbide. The formation energies of point defects, as well as activation energies for self migration, have been evaluated in order to cross-check the suitability of the potential. Assuming that the carbon vacancies are the main defects in uranium mono-carbide compounds, the migration paths and energies are consistent with experimental data selected by Catlow[C.R.A. Catlow, J. Nucl. Mater. 60 (1976) 151]. The insertion and migration energies for He, Kr and Xe have also been evaluated with available inter-atomic potentials [H.H. Andersen, P. Sigmund, Nucl. Instr. and Meth. B 38 (1965) 238]. Results show that the most stable defect configuration for rare gases is within uranium vacancies. The migration energy of an interstitial Xe is 0.5 eV, in agreement with the experimental value of 0.5 eV [Hj. Matzke, Science of advanced LMFBR fuels, Solid State Physics, Chemistry and Technology of Carbides, Nitrides and Carbonitrides of Uranium and Plutonium, North-Holland, 1986].

  1. Ventricular Septal Defect (For Parents)

    Science.gov (United States)

    ... Child What Kids Say About: Handling Stress Anxiety, Fears, and Phobias Community Service: A Family's Guide to ... septal defect (VSD) — sometimes referred to as a hole in the heart — is a type of congenital ...

  2. Defective Autophagy Initiates Malignant Transformation.

    Science.gov (United States)

    Galluzzi, Lorenzo; Bravo-San Pedro, José Manuel; Kroemer, Guido

    2016-05-19

    In this issue of Molecular Cell, Park et al. (2016) elegantly demonstrate that a partial defect in autophagy supports malignant transformation as it favors the production of genotoxic reactive oxygen species by mitochondria.

  3. Screening Tests for Birth Defects

    Science.gov (United States)

    ... 21 (Down syndrome) . Other trisomies include trisomy 13 (Patau syndrome) and trisomy 18 (Edwards syndrome) . A monosomy is ... which there is an extra chromosome. Trisomy 13 (Patau Syndrome): A genetic disorder that causes serious heart defects ...

  4. Atrial Septal Defect (For Teens)

    Science.gov (United States)

    ... septal defect (pronounced: AY-tree-ul SEP-tul DEE-fekt), or ASD for short, is sometimes referred ... can be treated with cardiac catheterization (pronounced: CAR-dee-ack cath-uh-turr-ih-ZAY-shun), in ...

  5. Low quantum defect laser performance

    Science.gov (United States)

    Bowman, Steven R.

    2017-01-01

    Low quantum defect lasers are possible using near-resonant optical pumping. This paper examines the laser material performance as the quantum defect of the laser is reduced. A steady-state model is developed, which incorporates the relevant physical processes in these materials and predicts extraction efficiency and waste heat generation. As the laser quantum defect is reduced below a few percent, the impact of fluorescence cooling must be included in the analysis. The special case of a net zero quantum defect laser is examined in detail. This condition, referred to as the radiation balance laser (RBL), is shown to provide two orders of magnitude lower heat generation at the cost of roughly 10% loss in extraction efficiency. Numerical examples are presented with the host materials Yb:YAG and Yb:Silica. The general conditions, which yield optimal laser efficiency, are derived and explored.

  6. Congenital heart defect - corrective surgery

    Science.gov (United States)

    ... Hypoplastic left heart repair; Tetralogy of Fallot repair; Coarctation of the aorta repair; Atrial septal defect repair; ... done in the neonatal intensive care unit (NICU). Coarctation of the aorta repair: Coarctation of the aorta ...

  7. Painless causality in defect calculations

    CERN Document Server

    Cheung, C; Cheung, Charlotte; Magueijo, Joao

    1997-01-01

    Topological defects must respect causality, a statement leading to restrictive constraints on the power spectrum of the total cosmological perturbations they induce. Causality constraints have for long been known to require the presence of an under-density in the surrounding matter compensating the defect network on large scales. This so-called compensation can never be neglected and significantly complicates calculations in defect scenarios, eg. computing cosmic microwave background fluctuations. A quick and dirty way to implement the compensation are the so-called compensation fudge factors. Here we derive the complete photon-baryon-CDM backreaction effects in defect scenarios. The fudge factor comes out as an algebraic identity and so we drop the negative qualifier ``fudge''. The compensation scale is computed and physically interpreted. Secondary backreaction effects exist, and neglecting them constitutes the well-defined approximation scheme within which one should consider compensation factor calculatio...

  8. A PTK7/Ror2 Co-Receptor Complex Affects Xenopus Neural Crest Migration.

    Directory of Open Access Journals (Sweden)

    Martina Podleschny

    Full Text Available Neural crest cells are a highly migratory pluripotent cell population that generates a wide array of different cell types and failure in their migration can result in severe birth defects and malformation syndromes. Neural crest migration is controlled by various means including chemotaxis, repellent guidance cues and cell-cell interaction. Non-canonical Wnt PCP (planar cell polarity signaling has previously been shown to control cell-contact mediated neural crest cell guidance. PTK7 (protein tyrosine kinase 7 is a transmembrane pseudokinase and a known regulator of Wnt/PCP signaling, which is expressed in Xenopus neural crest cells and required for their migration. PTK7 functions as a Wnt co-receptor; however, it remains unclear by which means PTK7 affects neural crest migration. Expressing fluorescently labeled proteins in Xenopus neural crest cells we find that PTK7 co-localizes with the Ror2 Wnt-receptor. Further, co-immunoprecipitation experiments demonstrate that PTK7 interacts with Ror2. The PTK7/Ror2 interaction is likely relevant for neural crest migration, because Ror2 expression can rescue the PTK7 loss of function migration defect. Live cell imaging of explanted neural crest cells shows that PTK7 loss of function affects the formation of cell protrusions as well as cell motility. Co-expression of Ror2 can rescue these defects. In vivo analysis demonstrates that a kinase dead Ror2 mutant cannot rescue PTK7 loss of function. Thus, our data suggest that Ror2 can substitute for PTK7 and that the signaling function of its kinase domain is required for this effect.

  9. 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...... up with a more deepgoing review of the relatively small number of studies, which explicitly deal with settlement preferences related to access to health care....

  10. Brownian Motion in Planetary Migration

    CERN Document Server

    Murray-Clay, R A; Murray-Clay, Ruth A.; Chiang, Eugene I.

    2006-01-01

    A residual planetesimal disk of mass 10-100 Earth masses remained in the outer solar system following the birth of the giant planets, as implied by the existence of the Oort cloud, coagulation requirements for Pluto, and inefficiencies in planet formation. Upon gravitationally scattering planetesimal debris, planets migrate. Orbital migration can lead to resonance capture, as evidenced here in the Kuiper and asteroid belts, and abroad in extra-solar systems. Finite sizes of planetesimals render migration stochastic ("noisy"). At fixed disk mass, larger (fewer) planetesimals generate more noise. Extreme noise defeats resonance capture. We employ order-of-magnitude physics to construct an analytic theory for how a planet's orbital semi-major axis fluctuates in response to random planetesimal scatterings. To retain a body in resonance, the planet's semi-major axis must not random walk a distance greater than the resonant libration width. We translate this criterion into an analytic formula for the retention effi...

  11. Planet migration and magnetic torques

    Science.gov (United States)

    Strugarek, A.; Brun, A. S.; Matt, S. P.; Reville, V.

    2016-10-01

    The possibility that magnetic torques may participate in close-in planet migration has recently been postulated. We develop three dimensional global models of magnetic star-planet interaction under the ideal magnetohydrodynamic (MHD) approximation to explore the impact of magnetic topology on the development of magnetic torques. We conduct twin numerical experiments in which only the magnetic topology of the interaction is altered. We find that magnetic torques can vary by roughly an order of magnitude when varying the magnetic topology from an aligned case to an anti-aligned case. Provided that the stellar magnetic field is strong enough, we find that magnetic migration time scales can be as fast as ~100 Myr. Hence, our model supports the idea that magnetic torques may participate in planet migration for some close-in star-planet systems.

  12. 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.

  13. 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...... up with a more deepgoing review of the relatively small number of studies, which explicitly deal with settlement preferences related to access to health care....

  14. Neurobiology of Monarch Butterfly Migration.

    Science.gov (United States)

    Reppert, Steven M; Guerra, Patrick A; Merlin, Christine

    2016-01-01

    Studies of the migration of the eastern North American monarch butterfly (Danaus plexippus) have revealed mechanisms behind its navigation. The main orientation mechanism uses a time-compensated sun compass during both the migration south and the remigration north. Daylight cues, such as the sun itself and polarized light, are processed through both eyes and integrated through intricate circuitry in the brain's central complex, the presumed site of the sun compass. Monarch circadian clocks have a distinct molecular mechanism, and those that reside in the antennae provide time compensation. Recent evidence shows that migrants can also use a light-dependent inclination magnetic compass for orientation in the absence of directional daylight cues. The monarch genome has been sequenced, and genetic strategies using nuclease-based technologies have been developed to edit specific genes. The monarch butterfly has emerged as a model system to study the neural, molecular, and genetic basis of long-distance animal migration.

  15. Stable line defects in silicene

    Science.gov (United States)

    Ghosh, Dibyajyoti; Parida, Prakash; Pati, Swapan K.

    2015-11-01

    Line defects in two-dimensional (2D) materials greatly modulate various properties of their pristine form. Using ab initio molecular dynamics (AIMD) simulations, we investigate the structural reconstructions of different kinds of grain boundaries in the silicene sheets. It is evident that depending upon the presence of silicon adatoms and edge shape of grain boundaries (i.e., armchair or zigzag), stable extended line defects (ELDs) can be introduced in a controlled way. Further studies show the stability of these line-defects in silicene, grown on Ag(111) surface at room-temperature. Importantly, unlike most of the 2D sheet materials such as graphene and hexagonal boron nitride, 5-5-8 line defects modify the nonmagnetic semimetallic pristine silicene sheet to spin-polarized metal. As ferromagnetically ordered magnetic moments remain strongly localized at the line defect, a one-dimensional spin channel gets created in silicene. Interestingly, these spin channels are quite stable because, unlike the edge of nanoribbons, structural reconstruction or contamination cannot destroy the ordering of magnetic moments here. Zigzag silicene nanoribbons with a 5-5-8 line defect also exhibit various interesting electronic and magnetic properties depending upon their width as well as the nature of the magnetic coupling between edge and defect spin states. Upon incorporation of other ELDs, such as 4-4-4 and 4-8 defects, 2D sheets and nanoribbons of silicene show a nonmagnetic metallic or semiconducting ground state. Highlighting the controlled formation of ELDs and consequent emergence of technologically important properties in silicene, we propose new routes to realize silicene-based nanoelectronic and spintronic devices.

  16. Topological defects from the multiverse

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jun [Institute of Cosmology, Department of Physics and Astronomy, Tufts University, Medford, MA 02155 (United States); Blanco-Pillado, Jose J. [Department of Theoretical Physics, University of the Basque Country UPV/EHU, 48080 Bilbao (Spain); IKERBASQUE, Basque Foundation for Science, 48013, Bilbao (Spain); Garriga, Jaume [Departament de Fisica Fonamental i Institut de Ciencies del Cosmos, Universitat de Barcelona, Marti i Franques, 1, 08028, Barcelona (Spain); Vilenkin, Alexander [Institute of Cosmology, Department of Physics and Astronomy, Tufts University, Medford, MA 02155 (United States)

    2015-05-28

    Many theories of the early universe predict the existence of a multiverse where bubbles continuously nucleate giving rise to observers in their interior. In this paper, we point out that topological defects of several dimensionalities will also be produced in de Sitter like regions of the multiverse. In particular, defects could be spontaneously nucleated in our parent vacuum. We study the evolution of these defects as they collide with and propagate inside of our bubble. We estimate the present distribution of defects in the observable part of the universe. The expected number of such nearby defects turns out to be quite small, even for the highest nucleation rate. We also study collisions of strings and domain walls with our bubble in our past light cone. We obtain simulated full-sky maps of the loci of such collisions, and find their angular size distribution. Similarly to what happens in the case of bubble collisions, the prospect of detecting any collisions of our bubble with ambient defects is greatly enhanced in the case where the cosmological constant of our parent vacuum is much higher than the vacuum energy density during inflation in our bubble.

  17. Topological defects from the multiverse

    Science.gov (United States)

    Zhang, Jun; Blanco-Pillado, Jose J.; Garriga, Jaume; Vilenkin, Alexander

    2015-05-01

    Many theories of the early universe predict the existence of a multiverse where bubbles continuously nucleate giving rise to observers in their interior. In this paper, we point out that topological defects of several dimensionalities will also be produced in de Sitter like regions of the multiverse. In particular, defects could be spontaneously nucleated in our parent vacuum. We study the evolution of these defects as they collide with and propagate inside of our bubble. We estimate the present distribution of defects in the observable part of the universe. The expected number of such nearby defects turns out to be quite small, even for the highest nucleation rate. We also study collisions of strings and domain walls with our bubble in our past light cone. We obtain simulated full-sky maps of the loci of such collisions, and find their angular size distribution. Similarly to what happens in the case of bubble collisions, the prospect of detecting any collisions of our bubble with ambient defects is greatly enhanced in the case where the cosmological constant of our parent vacuum is much higher than the vacuum energy density during inflation in our bubble.

  18. Topological Defects from the Multiverse

    CERN Document Server

    Zhang, Jun; Garriga, Jaume; Vilenkin, Alexander

    2015-01-01

    Many theories of the early universe predict the existence of a multiverse where bubbles continuously nucleate giving rise to observers in their interior. In this paper, we point out that topological defects of several dimensionalities will also be produced in de Sitter like regions of the multiverse. In particular, defects could be spontaneously nucleated in our parent vacuum. We study the evolution of these defects as they collide with and propagate inside of our bubble. We estimate the present distribution of defects in the observable part of the universe. The expected number of such nearby defects turns out to be quite small, even for the highest nucleation rate. We also study collisions of strings and domain walls with our bubble in our past light cone. We obtain simulated full-sky maps of the loci of such collisions, and find their angular size distribution. Similarly to what happens in the case of bubble collisions, the prospect of detecting any collisions of our bubble with ambient defects is greatly e...

  19. Intrauterine Infections and Birth Defects

    Institute of Scientific and Technical Information of China (English)

    XIAO-YING ZHENG; XIN-MING SONG; LI-HUA PANG; YING JI; HONG-MEI SUN; LEI ZHANG; JU-FEN LIU; YAN-LING GUO; YAN ZHANG; TING ZHANG; YI-FEI WANG; CHEN XU; GONG CHEN; RUOLEI XIN; JIA-PENG CHEN; XU-MEI HU; QING YANG

    2004-01-01

    Intrauterine infection is an important cause of some birth defects worldwide. The most common pathogens include rubella virus, cytomegaloviurs, ureaplasma urealyticum, toxoplasma, etc. General information about these pathogens in epidemiology, consequence of birth defects, and the possible mechanisms in the progress of birth defects, and the interventions to prevent or treat these pathogens' infections are described. The infections caused by rubella virus, cytomegaloviurs, ureaplasma urealyticum, toxoplasma, etc. are common, yet they are proved to be fatal during the pregnant period, especially during the first trimester. These infections may cause sterility, abortion, stillbirth, low birth weight, and affect multiple organs that may induce loss of hearing and vision, even fetal deformity and the long-term effects. These pathogens' infections may influence the microenvironment of placenta, including levels of enzymes and cytokines, and affect chondriosome that may induce the progress of birth defect. Early diagnosis of infections during pregnancy should be strengthened. There are still many things to be settled, such as the molecular mechanisms of birth defects, the effective vaccines to certain pathogens. Birth defect researches in terms of etiology and the development of applicable and sensitive pathogen detection technology and methods are imperative.

  20. Electrical fingerprint of pipeline defects

    Energy Technology Data Exchange (ETDEWEB)

    Mica, Isabella [STMicroelectronics Srl, via C.Olivetti 2, 20041 Agrate Brianza (Italy)]. E-mail: isabella.mica@st.com; Polignano, Maria Luisa [STMicroelectronics Srl, via C.Olivetti 2, 20041 Agrate Brianza (Italy); Marco, Cinzia De [STMicroelectronics Srl, via C.Olivetti 2, 20041 Agrate Brianza (Italy)

    2004-12-15

    Pipeline defects are dislocations that connect the source region of the transistor with the drain region. They were widely reported to occur in CMOS, BiCMOS devices and recently in SOI technologies. They can reduce device yield either by affecting the devices functionality or by increasing the current consumption under stand-by conditions. In this work the electrical fingerprint of these dislocations is studied, its purpose is to enable us to identify these defects as the ones responsible for device failure. It is shown that the pipeline defects are responsible for a leakage current from source to drain in the transistors. This leakage has a resistive characteristic and it is lightly modulated by the body bias. It is not sensitive to temperature; vice versa the off-current of a good transistor exhibits the well-known exponential dependence on 1/T. The emission spectrum of these defects was studied and compared with the spectrum of a good transistor. The paper aims to show that the spectrum of a defective transistor is quite peculiar; it shows well defined peaks, whereas the spectrum of a good transistor under saturation conditions is characterized by a broad spectral light emission distribution. Finally the deep-level transient spectroscopy (DLTS) is tried on defective diodes.