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Sample records for repulsive guidance molecule

  1. Levodopa increases oxidative stress and repulsive guidance molecule A levels: a pilot study in patients with Parkinson's disease.

    Science.gov (United States)

    Müller, Thomas; Trommer, Isabel; Muhlack, Siegfried; Mueller, Bernhard K

    2016-04-01

    Exposure to free radicals influences synthesis, degradation and function of proteins, such as repulsive guidance molecule A. Decay of this protein is essential for neuronal maintenance and recovery. Levodopa elevates oxidative stress. Therefore levodopa may impact repulsive guidance molecule A metabolism. Objectives were to investigate plasma concentrations of repulsive guidance molecule A, levodopa, cysteine and cysteinyl-glycine before and 1 h after levodopa application in patients with Parkinson's disease. Cysteine and cysteinyl-glycine as biomarkers for oxidative stress exposure decreased, repulsive guidance molecule A and levodopa rose. Repulsive guidance molecule A remained unchanged in levodopa naïve patients, but particularly went up in patients on a prior chronic levodopa regimen. Decay of cysteine specifically cysteinyl-glycine results from an elevated glutathione generation with rising cysteine consumption respectively from the alternative glutathione transformation to its oxidized form glutathione disulfide after free radical scavenging. Repulsive guidance molecule A rise may inhibit physiologic mechanisms for neuronal survival.

  2. Dissecting Repulsive Guidance Molecule/Neogenin function and signaling during neural development

    NARCIS (Netherlands)

    van den Heuvel, D.M.A.

    2013-01-01

    During neural development a series of precisely ordered cellular processes acts to establish a functional brain comprising millions of neurons and many more neuronal connections. Neogenin and its repulsive guidance molecule (RGM) ligands contribute to neuronal network formation by inducing axon

  3. RGM is a repulsive guidance molecule for retinal axons

    DEFF Research Database (Denmark)

    Monnier, Philippe P; Sierra, Ana; Macchi, Paolo

    2002-01-01

    with known guidance cues, and its messenger RNA is distributed in a gradient with increasing concentration from the anterior to posterior pole of the embryonic tectum. Recombinant RGM at low nanomolar concentration induces collapse of temporal but not of nasal growth cones and guides temporal retinal axons...

  4. Repulsive guidance molecule a blockade exerts the immunoregulatory function in DCs stimulated with ABP and LPS.

    Science.gov (United States)

    Xu, Xuxu; Gao, Yan; Zhai, Zhiyong; Zhang, Shuo; Shan, Fengping; Feng, Juan

    2016-08-02

    Repulsive guidance molecule a (RGMa) is an axonal guidance molecule that has recently found to exert function in immune system. This study evaluated the function of RGMa in modulation of dendritic cells (DCs) function stimulated with Achyranthes bidentata polysaccharide (ABP) and lipopolysaccharide (LPS) using a RGMa-neutralizing antibody. Compared with the Control-IgG/ABP and Control-IgG/LPS groups, DCs in the Anti-RGMa/ABP and Anti-RGMa/LPS groups 1) showed small, round cells with a few cell processes and organelles, and many pinocytotic vesicles; 2) had decreased MHC II, CD86, CD80, and CD40 expression; 3) displayed the decreased IL-12p70, IL-1β and TNF-α levels and increased IL-10 secretion; 4) had a high percentage of FITC-dextran uptake; and 5) displayed a reduced ability to drive T cell proliferation and reinforced T cell polarization toward a Th2 cytokine pattern. We conclude that DCs treated with RGMa-neutralizing antibodies present with tolerogenic and immunoregulatory characteristics, which provides new insights into further understanding of the function of RGMa.

  5. Dragon (repulsive guidance molecule b, RGMb) is a novel gene that promotes colorectal cancer growth.

    Science.gov (United States)

    Shi, Ying; Chen, Guo-Bin; Huang, Xiao-Xiao; Xiao, Chuan-Xing; Wang, Huan-Huan; Li, Ye-Sen; Zhang, Jin-Fang; Li, Shao; Xia, Yin; Ren, Jian-Lin; Guleng, Bayasi

    2015-08-21

    Colorectal cancer (CRC) is one of the most commonly diagnosed cancers and a major cause of cancer death. However, the molecular mechanisms underlying CRC initiation, growth and metastasis are poorly understood. Dragon (RGMb), a member of the repulsive guidance molecule (RGM) family, has been recently identified as a co-receptor for bone morphogenetic protein (BMP) signaling, but the role of Dragon in CRC development is undefined. Here, we show that Dragon expression was increased in colon cancer tissues compared to control tissues in CAC mouse model and in human patients. Dragon promoted proliferation of CT26.WT and CMT93 colon cancer cells and accelerated tumor growth in the xenograft mouse model. Dragon's action on colon cancer development was mediated via the BMP4-Smad1/5/8 and Erk1/2 pathways. Therefore, our results have revealed that Dragon is a novel gene that promotes CRC growth through the BMP pathway. Dragon may be exploited as a potential therapeutic target for CRC treatment.

  6. Dragon (repulsive guidance molecule b) inhibits IL-6 expression in macrophages.

    Science.gov (United States)

    Xia, Yin; Cortez-Retamozo, Virna; Niederkofler, Vera; Salie, Rishard; Chen, Shanzhuo; Samad, Tarek A; Hong, Charles C; Arber, Silvia; Vyas, Jatin M; Weissleder, Ralph; Pittet, Mikael J; Lin, Herbert Y

    2011-02-01

    Repulsive guidance molecule (RGM) family members RGMa, RGMb/Dragon, and RGMc/hemojuvelin were found recently to act as bone morphogenetic protein (BMP) coreceptors that enhance BMP signaling activity. Although our previous studies have shown that hemojuvelin regulates hepcidin expression and iron metabolism through the BMP pathway, the role of the BMP signaling mediated by Dragon remains largely unknown. We have shown previously that Dragon is expressed in neural cells, germ cells, and renal epithelial cells. In this study, we demonstrate that Dragon is highly expressed in macrophages. Studies with RAW264.7 and J774 macrophage cell lines reveal that Dragon negatively regulates IL-6 expression in a BMP ligand-dependent manner via the p38 MAPK and Erk1/2 pathways but not the Smad1/5/8 pathway. We also generated Dragon knockout mice and found that IL-6 is upregulated in macrophages and dendritic cells derived from whole lung tissue of these mice compared with that in respective cells derived from wild-type littermates. These results indicate that Dragon is an important negative regulator of IL-6 expression in immune cells and that Dragon-deficient mice may be a useful model for studying immune and inflammatory disorders.

  7. Spatiotemporal expression of repulsive guidance molecules (RGMs and their receptor neogenin in the mouse brain.

    Directory of Open Access Journals (Sweden)

    Dianne M A van den Heuvel

    Full Text Available Neogenin has been implicated in a variety of developmental processes such as neurogenesis, neuronal differentiation, apoptosis, migration and axon guidance. Binding of repulsive guidance molecules (RGMs to Neogenin inhibits axon outgrowth of different neuronal populations. This effect requires Neogenin to interact with co-receptors of the uncoordinated locomotion-5 (Unc5 family to activate downstream Rho signaling. Although previous studies have reported RGM, Neogenin, and/or Unc5 expression, a systematic comparison of RGM and Neogenin expression in the developing nervous system is lacking, especially at later developmental stages. Furthermore, information on RGM and Neogenin expression at the protein level is limited. To fill this void and to gain further insight into the role of RGM-Neogenin signaling during mouse neural development, we studied the expression of RGMa, RGMb, Neogenin and Unc5A-D using in situ hybridization, immunohistochemistry and RGMa section binding. Expression patterns in the primary olfactory system, cortex, hippocampus, habenula, and cerebellum were studied in more detail. Characteristic cell layer-specific expression patterns were detected for RGMa, RGMb, Neogenin and Unc5A-D. Furthermore, strong expression of RGMa, RGMb and Neogenin protein was found on several major axon tracts such as the primary olfactory projections, anterior commissure and fasciculus retroflexus. These data not only hint at a role for RGM-Neogenin signaling during the development of different neuronal systems, but also suggest that Neogenin partners with different Unc5 family members in different systems. Overall, the results presented here will serve as a framework for further dissection of the role of RGM-Neogenin signaling during neural development.

  8. Dragon (Repulsive Guidance Molecule RGMb) Inhibits E-cadherin Expression and Induces Apoptosis in Renal Tubular Epithelial Cells*

    Science.gov (United States)

    Liu, Wenjing; Li, Xiaoling; Zhao, Yueshui; Meng, Xiao-Ming; Wan, Chao; Yang, Baoxue; Lan, Hui-Yao; Lin, Herbert Y.; Xia, Yin

    2013-01-01

    Dragon is one of the three members of the repulsive guidance molecule (RGM) family, i.e. RGMa, RGMb (Dragon), and RGMc (hemojuvelin). We previously identified the RGM members as bone morphogenetic protein (BMP) co-receptors that enhance BMP signaling. Our previous studies found that Dragon is highly expressed in the tubular epithelial cells of mouse kidneys. However, the roles of Dragon in renal epithelial cells are yet to be defined. We now show that overexpression of Dragon increased cell death induced by hypoxia in association with increased cleaved poly(ADP-ribose) polymerase and cleaved caspase-3 levels in mouse inner medullary collecting duct (IMCD3) cells. Dragon also inhibited E-cadherin expression but did not affect epithelial-to-mesenchymal transition induced by TGF-β in IMCD3 cells. Previous studies suggest that the three RGM members can function as ligands for the receptor neogenin. Interestingly, our present study demonstrates that the Dragon actions on apoptosis and E-cadherin expression in IMCD3 cells were mediated by the neogenin receptor but not through the BMP pathway. Dragon expression in the kidney was up-regulated by unilateral ureteral obstruction in mice. Compared with wild-type mice, heterozygous Dragon knock-out mice exhibited 45–66% reduction in Dragon mRNA expression, decreased epithelial apoptosis, and increased tubular E-cadherin expression and had attenuated tubular injury after unilateral ureteral obstruction. Our results suggest that Dragon may impair tubular epithelial integrity and induce epithelial apoptosis both in vitro and in vivo. PMID:24052264

  9. Dragon (repulsive guidance molecule RGMb) inhibits E-cadherin expression and induces apoptosis in renal tubular epithelial cells.

    Science.gov (United States)

    Liu, Wenjing; Li, Xiaoling; Zhao, Yueshui; Meng, Xiao-Ming; Wan, Chao; Yang, Baoxue; Lan, Hui-Yao; Lin, Herbert Y; Xia, Yin

    2013-11-01

    Dragon is one of the three members of the repulsive guidance molecule (RGM) family, i.e. RGMa, RGMb (Dragon), and RGMc (hemojuvelin). We previously identified the RGM members as bone morphogenetic protein (BMP) co-receptors that enhance BMP signaling. Our previous studies found that Dragon is highly expressed in the tubular epithelial cells of mouse kidneys. However, the roles of Dragon in renal epithelial cells are yet to be defined. We now show that overexpression of Dragon increased cell death induced by hypoxia in association with increased cleaved poly(ADP-ribose) polymerase and cleaved caspase-3 levels in mouse inner medullary collecting duct (IMCD3) cells. Dragon also inhibited E-cadherin expression but did not affect epithelial-to-mesenchymal transition induced by TGF-β in IMCD3 cells. Previous studies suggest that the three RGM members can function as ligands for the receptor neogenin. Interestingly, our present study demonstrates that the Dragon actions on apoptosis and E-cadherin expression in IMCD3 cells were mediated by the neogenin receptor but not through the BMP pathway. Dragon expression in the kidney was up-regulated by unilateral ureteral obstruction in mice. Compared with wild-type mice, heterozygous Dragon knock-out mice exhibited 45-66% reduction in Dragon mRNA expression, decreased epithelial apoptosis, and increased tubular E-cadherin expression and had attenuated tubular injury after unilateral ureteral obstruction. Our results suggest that Dragon may impair tubular epithelial integrity and induce epithelial apoptosis both in vitro and in vivo.

  10. Highly effective photonic cue for repulsive axonal guidance.

    Directory of Open Access Journals (Sweden)

    Bryan J Black

    Full Text Available In vivo nerve repair requires not only the ability to regenerate damaged axons, but most importantly, the ability to guide developing or regenerating axons along paths that will result in functional connections. Furthermore, basic studies in neuroscience and neuro-electronic interface design require the ability to construct in vitro neural circuitry. Both these applications require the development of a noninvasive, highly effective tool for axonal growth-cone guidance. To date, a myriad of technologies have been introduced based on chemical, electrical, mechanical, and hybrid approaches (such as electro-chemical, optofluidic flow and photo-chemical methods. These methods are either lacking in desired spatial and temporal selectivity or require the introduction of invasive external factors. Within the last fifteen years however, several attractive guidance cues have been developed using purely light based cues to achieve axonal guidance. Here, we report a novel, purely optical repulsive guidance technique that uses low power, near infrared light, and demonstrates the guidance of primary goldfish retinal ganglion cell axons through turns of up to 120 degrees and over distances of ∼90 µm.

  11. Axon guidance molecules in vascular patterning.

    Science.gov (United States)

    Adams, Ralf H; Eichmann, Anne

    2010-05-01

    Endothelial cells (ECs) form extensive, highly branched and hierarchically organized tubular networks in vertebrates to ensure the proper distribution of molecular and cellular cargo in the vertebrate body. The growth of this vascular system during development, tissue repair or in disease conditions involves the sprouting, migration and proliferation of endothelial cells in a process termed angiogenesis. Surprisingly, specialized ECs, so-called tip cells, which lead and guide endothelial sprouts, share many feature with another guidance structure, the axonal growth cone. Tip cells are motile, invasive and extend numerous filopodial protrusions sensing growth factors, extracellular matrix and other attractive or repulsive cues in their tissue environment. Axonal growth cones and endothelial tip cells also respond to signals belonging to the same molecular families, such as Slits and Roundabouts, Netrins and UNC5 receptors, Semaphorins, Plexins and Neuropilins, and Eph receptors and ephrin ligands. Here we summarize fundamental principles of angiogenic growth, the selection and function of tip cells and the underlying regulation by guidance cues, the Notch pathway and vascular endothelial growth factor signaling.

  12. Coulomb Repulsion Effect in Two-electron Non-adiabatic Tunneling through a One-level redox Molecule

    DEFF Research Database (Denmark)

    Medvedev, Igor M.; Kuznetsov, Alexander M.; Ulstrup, Jens

    2009-01-01

    We investigated Coulomb repulsion effects in nonadiabatic (diabatic) two-electron tunneling through a redox molecule with a single electronic level in a symmetric electrochemical contact under ambient conditions, i.e., room temperature and condensed matter environment. The electrochemical contact...

  13. New models for intermolecular repulsion and their application to Van Der Waals complexes and crystals of organic molecules

    International Nuclear Information System (INIS)

    Tsui, H.H.Y.

    2001-01-01

    Model intermolecular potentials are required for simulations of molecules in the gas, liquid, or solid phase. The widely used isotropic atom-atom model potentials are empirically fitted and based on the assumptions of transferability, combining rules and that atoms in molecules are spherical. This thesis develops a non-empirical method of modelling repulsion by applying the overlap model, which we show as a general non-empirical method of deriving repulsion potentials for a specific molecule. In this thesis, the repulsion parameters for an exponential atom-atom model potential are obtained from the ab initio charge density of a small organic molecule by making the assumption that the repulsion is proportional to the overlap of a pair of molecules. The proportionality constant is fixed by a limited number of intermolecular perturbation theory (IMPT) calculations. To complete the model potential, the electrostatic interaction is represented by a distributed multipole analysis, and the Slater-Kirkwood formula is used for the dispersion. These non-empirical potentials can reproduce experimental crystal structure when applied to crystal structure prediction of an oxyboryl derivative. A detailed study on further improving the overlap model was carried out for phenol-water, by including other minor intermolecular contributions of charge-transfer and penetration. High quality ab initio calculations on the complex were performed for use in comparison. To compare with experimental data, diffusion Monte Carlo simulations were performed with the potential, so that the effects of anharmonic zero-point motion on structure and energy of the system are included. When the system is too large for an IMPT calculation, the proportionality constant can be determined empirically by fitting the cell volume as shown in our study of crystal structures of chlorothalonil. This is used with an anisotropic repulsion model that has been derived for Cl and N atoms in chlorothalonil. This model

  14. Attractive and repulsive interactions among methanol molecules in supercritical state investigated by Raman spectroscopy and perturbed hard-sphere theory.

    Science.gov (United States)

    Saitow, Ken-ichi; Sasaki, Jungo

    2005-03-08

    The short-range structure of supercritical methanol (CH(3)OH) is investigated by measuring the spontaneous Raman spectra of the C-O stretching mode. The spectra are obtained at a reduced temperature, T(r)=T/T(c)=1.02 (522.9 K), which permits the neat fluid to be studied isothermally as a function of density. As the density increases, the spectral peaks shift toward the lower energy side and the spectra broaden. In the supercritical region, the amount of shifting shows nonlinear density dependence and the width becomes anomalously large. We use the perturbed hard-sphere model to analyze these density dependencies along the vibrational coordinate. The amount of shifting is decomposed into attractive and repulsive components, and the changes in attractive and repulsive energies are evaluated as functions of density and packing fraction, both of which are continuously varied by a factor of 120. Here we show that the shift amount consists principally of the attractive component at all densities, since the attractive energy is about eight times the repulsive energy. The density dependence of the widths is analyzed by calculating homogeneous and inhomogeneous widths as a function of density. The results show that, although vibrational dephasing and density inhomogeneity contribute similarly to the width at low and middle densities, at high density the main contributor turns out to be the vibrational dephasing. We estimate the local density enhancements of supercritical CH(3)OH as function of bulk density by two methods. The results of these analyses show common features, and both the estimated local density enhancements of CH(3)OH are considerably larger than the local density enhancements of simple fluids, i.e., those having nonhydrogen bonding. It is revealed that the local density of supercritical CH(3)OH is 40%-60% greater than the local densities of the simple fluids. We also estimate the local density fluctuation using the obtained values of attractive shift

  15. Abundant expression of guidance and synaptogenic molecules in the injured spinal cord.

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    Anne Jacobi

    Full Text Available BACKGROUND: Spinal interneurons have emerged as crucial targets of supraspinal input during post-injury axonal remodelling. For example, lesioned corticospinal projections use propriospinal neurons as relay stations to form intraspinal detour circuits that circumvent the lesion site and contribute to functional recovery. While a number of the molecules that determine the formation of neuronal circuits in the developing nervous system have been identified, it is much less understood which of these cues are also expressed in the injured spinal cord and can thus guide growing collaterals and initiate synaptogenesis during circuit remodelling. METHODOLOGY/PRINCIPAL FINDINGS: To address this question we characterized the expression profile of a number of guidance and synaptogenic molecules in the cervical spinal cord of healthy and spinal cord-injured mice by in situ hybridization. To assign the expression of these molecules to distinct populations of interneurons we labeled short and long propriospinal neurons by retrograde tracing and glycinergic neurons using a transgenically expressed fluorescent protein. Interestingly, we found that most of the molecules studied including members of slit-, semaphorin-, synCAM-, neuroligin- and ephrin- families as well as their receptors are also present in the adult CNS. While many of these molecules were abundantly expressed in all interneurons examined, some molecules including slits, semaphorin 7a, synCAM4 and neuroligin 1 showed preferential expression in propriospinal interneurons. Overall the expression pattern of guidance and synaptogenic molecules in the cervical spinal cord appeared to be stable over time and was not substantially altered following a midthoracic spinal cord injury. CONCLUSIONS: Taken together, our study indicates that many of the guidance and synaptogenic cues that regulate neuronal circuit formation in development are also present in the adult CNS and therefore likely contribute to the

  16. Ultracold fermions with repulsive interactions

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    Ketterle W.

    2013-08-01

    Full Text Available An ultracold Fermi gas with repulsive interaction has been studied. For weak interactions, the atomic gas is metastable, and the interactions were characterized by obtaining the isothermal compressibility from atomic density profiles. For stronger interactions (kFa ≈ 1, rapid conversion into Feshbach molecules is observed. When the conversion rate becomes comparable to the Fermi energy divided by η, the atomic gas cannot reach equilibrium without forming pairs. This precludes the predicted transition to a ferromagnetic state (Stoner transition. The absence of spin fluctuations proves that the gas stays paramagnetic. In free space, a Fermi gas with strong short-range repulsion does not exist because of the rapid coupling to molecular states.

  17. Charged singularities: repulsive effects

    Energy Technology Data Exchange (ETDEWEB)

    De Felice, F; Nobili, L [Padua Univ. (Italy). Ist. di Fisica; Calvani, M [Padua Univ. (Italy). Ist. di Astronomia

    1980-07-01

    The repulsive phenomena which a particle experiences in the vicinity of a naked singularity are investigated in the Kerr-Newman space-time. The aim is to extend the knowledge of this fact to charged solutions and to have a direct indication of how, in these situations, the gravitational and electrostatic interactions are competing.

  18. ΔM/sub j/ transitions in homonuclear molecule scattering off corrugated surfaces. Square and rectangular lattice symmetry and purely repulsive interaction

    International Nuclear Information System (INIS)

    Proctor, T.R.; Kouri, D.J.; Gerber, R.B.

    1984-01-01

    In this paper, we present the first formal and computational studies of Δm/sub j/ transitions occurring in homonuclear molecule-corrugated surface collisions. The model potential is a pairwise additive one which correctly incorporates the fact that Δm/sub j/ transitions occur only for corrugated surfaces (provided the quantization axis is chosen to be the average surface normal). The principal results are: (a) Δm/sub j/ transitions are extremely sensitive to lattice symmetry; (b) strong selection rules obtain for specular scattering; (c) the magnitude of Δm/sub j/ -transition probabilities are strongly sensitive to surface corrugation; (d) the Δm/sub j/ transitions depend strongly on diffraction peak; (e) the ratio of molecular length to lattice dimension (r/a) has a strong influence on the magnitude of Δm/sub j/ -transition probabilities [with the probabilities increasing as (r/a) increases]; (f) Δm/sub j/ rainbows are predicted to occur as a function of the (r/a) ratio increases; (g) Δm/sub j/ transitions and the Δm/sub j/ rainbow are expected to accompany Δj-rotational rainbows; (h) such magnetic transition rainbows accompanying Δj rainbows are suggested as an explanation of recent experimental observations of quenching of NO polarization for larger Δj transitions in NO/Ag(111) scattering

  19. Discrete repulsive oscillator wavefunctions

    International Nuclear Information System (INIS)

    Munoz, Carlos A; Rueda-Paz, Juvenal; Wolf, Kurt Bernardo

    2009-01-01

    For the study of infinite discrete systems on phase space, the three-dimensional Lorentz algebra and group, so(2,1) and SO(2,1), provide a discrete model of the repulsive oscillator. Its eigenfunctions are found in the principal irreducible representation series, where the compact generator-that we identify with the position operator-has the infinite discrete spectrum of the integers Z, while the spectrum of energies is a double continuum. The right- and left-moving wavefunctions are given by hypergeometric functions that form a Dirac basis for l 2 (Z). Under contraction, the discrete system limits to the well-known quantum repulsive oscillator. Numerical computations of finite approximations raise further questions on the use of Dirac bases for infinite discrete systems.

  20. The transcription factor SOX18 regulates the expression of matrix metalloproteinase 7 and guidance molecules in human endothelial cells.

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    Martina Hoeth

    Full Text Available Mutations in the transcription factor SOX18 are responsible for specific cardiovascular defects in humans and mice. In order to gain insight into the molecular basis of its action, we identified target genes of SOX18 and analyzed one, MMP7, in detail.SOX18 was expressed in HUVEC using a recombinant adenoviral vector and the altered gene expression profile was analyzed using microarrays. Expression of several regulated candidate SOX18 target genes was verified by real-time PCR. Knock-down of SOX18 using RNA interference was then used to confirm the effect of the transcription factor on selected genes that included the guidance molecules ephrin B2 and semaphorin 3G. One gene, MMP7, was chosen for further analysis, including detailed promoter studies using reporter gene assays, electrophoretic mobility shift analysis and chromatin-immunoprecipitation, revealing that it responds directly to SOX18. Immunohistochemical analysis demonstrated the co-expression of SOX18 and MMP7 in blood vessels of human skin.The identification of MMP7 as a direct SOX18 target gene as well as other potential candidates including guidance molecules provides a molecular basis for the proposed function of this transcription factor in the regulation of vessel formation.

  1. Phenotype of V2-derived interneurons and their relationship to the axon guidance molecule EphA4 in the developing mouse spinal cord

    DEFF Research Database (Denmark)

    Lundfald, Line; Restrepo, C. Ernesto; Butt, Simon J B

    2007-01-01

    , we demonstrated that a large proportion of V2 interneurons expressed the axon guidance molecule EphA4, a molecule previously shown to be important for correct organization of locomotor networks. We also showed that V2 interneurons and motor neurons alone did not account for all EphA4-expressing...

  2. Repulsion of polarized particles from two-dimensional materials

    Science.gov (United States)

    Rodríguez-Fortuño, Francisco J.; Picardi, Michela F.; Zayats, Anatoly V.

    2018-05-01

    Repulsion of nanoparticles, molecules, and atoms from surfaces can have important applications in nanomechanical devices, microfluidics, optical manipulation, and atom optics. Here, through the solution of a classical scattering problem, we show that a dipole source oscillating at a frequency ω can experience a robust and strong repulsive force when its near-field interacts with a two-dimensional material. As an example, the case of graphene is considered, showing that a broad bandwidth of repulsion can be obtained at frequencies for which propagation of plasmon modes is allowed 0 chemical potential tunable electrically or by chemical doping.

  3. The axon guidance molecule semaphorin 3F is a negative regulator of tumor progression and proliferation in ileal neuroendocrine tumors

    Science.gov (United States)

    Vercherat, Cécile; Blanc, Martine; Lepinasse, Florian; Gadot, Nicolas; Couderc, Christophe; Poncet, Gilles; Walter, Thomas; Joly, Marie-Odile; Hervieu, Valérie; Scoazec, Jean-Yves; Roche, Colette

    2015-01-01

    Gastro-intestinal neuroendocrine tumors (GI-NETs) are rare neoplasms, frequently metastatic, raising difficult clinical and therapeutic challenges due to a poor knowledge of their biology. As neuroendocrine cells express both epithelial and neural cell markers, we studied the possible involvement in GI-NETs of axon guidance molecules, which have been shown to decrease tumor cell proliferation and metastatic dissemination in several tumor types. We focused on the role of Semaphorin 3F (SEMA3F) in ileal NETs, one of the most frequent subtypes of GI-NETs. SEMA3F expression was detected in normal neuroendocrine cells but was lost in most of human primary tumors and all their metastases. SEMA3F loss of expression was associated with promoter gene methylation. After increasing endogenous SEMA3F levels through stable transfection, enteroendocrine cell lines STC-1 and GluTag showed a reduced proliferation rate in vitro. In two different xenograft mouse models, SEMA3F-overexpressing cells exhibited a reduced ability to form tumors and a hampered liver dissemination potential in vivo. This resulted, at least in part, from the inhibition of mTOR and MAPK signaling pathways. This study demonstrates an anti-tumoral role of SEMA3F in ileal NETs. We thus suggest that SEMA3F and/or its cellular signaling pathway could represent a target for ileal NET therapy. PMID:26447612

  4. BmRobo1a and BmRobo1b control axon repulsion in the silkworm Bombyx mori.

    Science.gov (United States)

    Li, Xiao-Tong; Yu, Qi; Zhou, Qi-Sheng; Zhao, Xiao; Liu, Zhao-Yang; Cui, Wei-Zheng; Liu, Qing-Xin

    2016-02-15

    The development of the nervous system is based on the growth and connection of axons, and axon guidance molecules are the dominant regulators during this course. Robo, as the receptor of axon guidance molecule Slit, plays a key role as a conserved repellent cue for axon guidance during the development of the central nervous system. However, the function of Robo in the silkworm Bombyx mori is unknown. In this study, we cloned two novel robo genes in B. mori (Bmrobo1a and Bmrobo1b). BmRobo1a and BmRobo1b lack an Ig and a FNIII domain in the extracellular region and the CC0 and CC2 motifs in the intracellular region. BmRobo1a and BmRobo1b were colocalized with BmSlit in the neuropil. Knock-down of Bmrobo1a and Bmrobo1b by RNA interference (RNAi) resulted in abnormal development of axons. Our results suggest that BmRobo1a and BmRobo1b have repulsive function in axon guidance, even though their structures are different from Robo1 of other species. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Superconductivity in a Repulsive Model

    DEFF Research Database (Denmark)

    Feldman, Joel; Knoerrer, Horst; Sinclair, Robert

    1997-01-01

    A two-dimensional system of Fermions with classical dispersion relationand a purely repulsive delta function pair potential generates the dominant attractive coupling in the third order Bethe-Salpeter approximation for the Cooper channel. This suggests that the ground state is an l=1 superconductor....

  6. Religion, Repulsion, and Reaction Formation: Transforming Repellent Attractions and Repulsions.

    Science.gov (United States)

    Cohen, Dov; Kim, Emily; Hudson, Nathan W

    2017-06-12

    Protestants were more likely than non-Protestants to demonstrate phenomena consistent with the use of reaction formation. Lab experiments showed that when manipulations were designed to produce taboo attractions (to unconventional sexual practices), Protestants instead showed greater repulsion. When implicitly conditioned to produce taboo repulsions (to African Americans), Protestants instead showed greater attraction. Supportive evidence from other studies came from clinicians' judgments, defense mechanism inventories, and a survey of respondent attitudes. Other work showed that Protestants who diminished and displaced threatening affect were more likely to sublimate this affect into creative activities; the present work showed that Protestants who do not or cannot diminish or displace such threatening affect instead reverse it. Traditional individual difference variables showed little ability to predict reaction formation, suggesting that the observed processes go beyond what we normally study when we talk about self-control. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  7. Mechanical strain stimulates vasculogenesis and expression of angiogenesis guidance molecules of embryonic stem cells through elevation of intracellular calcium, reactive oxygen species and nitric oxide generation.

    Science.gov (United States)

    Sharifpanah, Fatemeh; Behr, Sascha; Wartenberg, Maria; Sauer, Heinrich

    2016-12-01

    Differentiation of embryonic stem (ES) cells may be regulated by mechanical strain. Herein, signaling molecules underlying mechanical stimulation of vasculogenesis and expression of angiogenesis guidance cues were investigated in ES cell-derived embryoid bodies. Treatment of embryoid bodies with 10% static mechanical strain using a Flexercell strain system significantly increased CD31-positive vascular structures and the angiogenesis guidance molecules plexinB1, ephrin B2, neuropilin1 (NRP1), semaphorin 4D (sem4D) and robo4 as well as vascular endothelial growth factor (VEGF), fibroblast growth factor-2 (FGF-2) and platelet-derived growth factor-BB (PDGF-BB) as evaluated by Western blot and real time RT-PCR. In contrast ephrin type 4 receptor B (EphB4) expression was down-regulated upon mechanical strain, indicating an arterial-type differentiation. Robo1 protein expression was modestly increased with no change in mRNA expression. Mechanical strain increased intracellular calcium as well as reactive oxygen species (ROS) and nitric oxide (NO). Mechanical strain-induced vasculogenesis was abolished by the NOS inhibitor L-NAME, the NADPH oxidase inhibitor VAS2870, upon chelation of intracellular calcium by BAPTA as well as upon siRNA inactivation of ephrin B2, NRP1 and robo4. BAPTA blunted the strain-induced expression of angiogenic growth factors, the increase in NO and ROS as well as the expression of NRP1, sem4D and plexinB1, whereas ephrin B2, EphB4 as well as robo1 and robo4 expression were not impaired. Mechanical strain stimulates vasculogenesis of ES cells by the intracellular messengers ROS, NO and calcium as well as by upregulation of angiogenesis guidance molecules and the angiogenic growth factors VEGF, FGF-2 and PDGF-BB. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Entropic Repulsion Between Fluctuating Surfaces

    Science.gov (United States)

    Janke, W.

    The statistical mechanics of fluctuating surfaces plays an important role in a variety of physical systems, ranging from biological membranes to world sheets of strings in theories of fundamental interactions. In many applications it is a good approximation to assume that the surfaces possess no tension. Their statistical properties are then governed by curvature energies only, which allow for gigantic out-of-plane undulations. These fluctuations are the “entropic” origin of long-range repulsive forces in layered surface systems. Theoretical estimates of these forces for simple model surfaces are surveyed and compared with recent Monte Carlo simulations.

  9. Coulomb repulsion in short polypeptides.

    Science.gov (United States)

    Norouzy, Amir; Assaf, Khaleel I; Zhang, Shuai; Jacob, Maik H; Nau, Werner M

    2015-01-08

    Coulomb repulsion between like-charged side chains is presently viewed as a major force that impacts the biological activity of intrinsically disordered polypeptides (IDPs) by determining their spatial dimensions. We investigated short synthetic models of IDPs, purely composed of ionizable amino acid residues and therefore expected to display an extreme structural and dynamic response to pH variation. Two synergistic, custom-made, time-resolved fluorescence methods were applied in tandem to study the structure and dynamics of the acidic and basic hexapeptides Asp6, Glu6, Arg6, Lys6, and His6 between pH 1 and 12. (i) End-to-end distances were obtained from the short-distance Förster resonance energy transfer (sdFRET) from N-terminal 5-fluoro-l-tryptophan (FTrp) to C-terminal Dbo. (ii) End-to-end collision rates were obtained for the same peptides from the collision-induced fluorescence quenching (CIFQ) of Dbo by FTrp. Unexpectedly, the very high increase of charge density at elevated pH had no dynamical or conformational consequence in the anionic chains, neither in the absence nor in the presence of salt, in conflict with the common view and in partial conflict with accompanying molecular dynamics simulations. In contrast, the cationic peptides responded to ionization but with surprising patterns that mirrored the rich individual characteristics of each side chain type. The contrasting results had to be interpreted, by considering salt screening experiments, N-terminal acetylation, and simulations, in terms of an interplay of local dielectric constant and peptide-length dependent side chain charge-charge repulsion, side chain functional group solvation, N-terminal and side chain charge-charge repulsion, and side chain-side chain as well as side chain-backbone interactions. The common picture that emerged is that Coulomb repulsion between water-solvated side chains is efficiently quenched in short peptides as long as side chains are not in direct contact with each

  10. Repulsion between oppositely charged planar macroions.

    Directory of Open Access Journals (Sweden)

    YongSeok Jho

    Full Text Available The repulsive interaction between oppositely charged macroions is investigated using Grand Canonical Monte Carlo simulations of an unrestricted primitive model, including the effect of inhomogeneous surface charge and its density, the depth of surface charge, the cation size, and the dielectric permittivity of solvent and macroions, and their contrast. The origin of the repulsion is a combination of osmotic pressure and ionic screening resulting from excess salt between the macroions. The excess charge over-reduces the electrostatic attraction between macroions and raises the entropic repulsion. The magnitude of the repulsion increases when the dielectric constant of the solvent is lowered (below that of water and/or the surface charge density is increased, in good agreement with experiment. Smaller size of surface charge and the cation, their discreteness and mobility are other factors that enhance the repulsion and charge inversion phenomenons.

  11. Attractive and repulsive magnetic suspension systems overview

    Science.gov (United States)

    Cope, David B.; Fontana, Richard R.

    1992-01-01

    Magnetic suspension systems can be used in a wide variety of applications. The decision of whether to use an attractive or repulsive suspension system for a particular application is a fundamental one which must be made during the design process. As an aid to the designer, we compare and contrast attractive and repulsive magnetic suspension systems and indicate whether and under what conditions one or the other system is preferred.

  12. Casimir Repulsion between Metallic Objects in Vacuum

    International Nuclear Information System (INIS)

    Levin, Michael; McCauley, Alexander P.; Rodriguez, Alejandro W.; Reid, M. T. Homer; Johnson, Steven G.

    2010-01-01

    We give an example of a geometry in which two metallic objects in vacuum experience a repulsive Casimir force. The geometry consists of an elongated metal particle centered above a metal plate with a hole. We prove that this geometry has a repulsive regime using a symmetry argument and confirm it with numerical calculations for both perfect and realistic metals. The system does not support stable levitation, as the particle is unstable to displacements away from the symmetry axis.

  13. Repulsive Casimir and Casimir–Polder forces

    International Nuclear Information System (INIS)

    Milton, Kimball A; Abalo, E K; Parashar, Prachi; Pourtolami, Nima; Brevik, Iver; Ellingsen, Simen Å

    2012-01-01

    Casimir and Casimir–Polder repulsions have been known for more than 50 years. The general ‘Lifshitz’ configuration of parallel semi-infinite dielectric slabs permits repulsion if they are separated by a dielectric fluid that has a value of permittivity that is intermediate between those of the dielectric slabs. This was indirectly confirmed in the 1970s, and more directly by Capasso’s group recently. It has also been known for many years that electrically and magnetically polarizable bodies can experience a repulsive quantum vacuum force. More amenable to practical application are situations where repulsion could be achieved between ordinary conducting and dielectric bodies in vacuum. The status of the field of Casimir repulsion with emphasis on some recent developments will be surveyed. Here, stress will be placed on analytic developments, especially on Casimir–Polder (CP) interactions between anisotropically polarizable atoms, and CP interactions between anisotropic atoms and bodies that also exhibit anisotropy, either because of anisotropic constituents, or because of geometry. Repulsion occurs for wedge-shaped and cylindrical conductors, provided the geometry is sufficiently asymmetric, that is, either the wedge is sufficiently sharp or the atom is sufficiently far from the cylinder. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical in honour of Stuart Dowker’s 75th birthday devoted to ‘Applications of zeta functions and other spectral functions in mathematics and physics’. (review)

  14. Interaction potential and repulsive force between atoms whose internuclear separations are small

    International Nuclear Information System (INIS)

    Barbaro, Jacques

    1971-01-01

    The Thomas-Fermi equation is solved for the homonuclear diatomic molecule. The electronic density and electrostatic potential at each point are used to calculate energies and interaction potentials for very small internuclear separation distances. The repulsive force between atoms is derived by means of the virial theorem. (author) [fr

  15. The Caenorhabditis elegans NF2/Merlin Molecule NFM-1 Nonautonomously Regulates Neuroblast Migration and Interacts Genetically with the Guidance Cue SLT-1/Slit.

    Science.gov (United States)

    Josephson, Matthew P; Aliani, Rana; Norris, Megan L; Ochs, Matthew E; Gujar, Mahekta; Lundquist, Erik A

    2017-02-01

    During nervous system development, neurons and their progenitors migrate to their final destinations. In Caenorhabditis elegans, the bilateral Q neuroblasts and their descendants migrate long distances in opposite directions, despite being born in the same posterior region. QR on the right migrates anteriorly and generates the AQR neuron positioned near the head, and QL on the left migrates posteriorly, giving rise to the PQR neuron positioned near the tail. In a screen for genes required for AQR and PQR migration, we identified an allele of nfm-1, which encodes a molecule similar to vertebrate NF2/Merlin, an important tumor suppressor in humans. Mutations in NF2 lead to neurofibromatosis type II, characterized by benign tumors of glial tissues. Here we demonstrate that in C. elegans, nfm-1 is required for the ability of Q cells and their descendants to extend protrusions and to migrate, but is not required for direction of migration. Using a combination of mosaic analysis and cell-specific expression, we show that NFM-1 is required nonautonomously, possibly in muscles, to promote Q lineage migrations. We also show a genetic interaction between nfm-1 and the C. elegans Slit homolog slt-1, which encodes a conserved secreted guidance cue. Our results suggest that NFM-1 might be involved in the generation of an extracellular cue that promotes Q neuroblast protrusion and migration that acts with or in parallel to SLT-1 In vertebrates, NF2 and Slit2 interact in axon pathfinding, suggesting a conserved interaction of NF2 and Slit2 in regulating migratory events. Copyright © 2017 by the Genetics Society of America.

  16. A soundtrack between allurement and repulsion

    DEFF Research Database (Denmark)

    Have, Iben

    2011-01-01

    By mixing industrial, metallic sounds and organic, throaty sounds, Kitchen Sink creates an acoustic universe which is at once repulsive and alluring. The article takes a phenomenological and deep listening approach to investigate how the soundtrack of Kitchen Sink contributes to the ambiguous...... narrative of the film....

  17. Slit stimulation recruits Dock and Pak to the roundabout receptor and increases Rac activity to regulate axon repulsion at the CNS midline.

    Science.gov (United States)

    Fan, Xueping; Labrador, Juan Pablo; Hing, Huey; Bashaw, Greg J

    2003-09-25

    Drosophila Roundabout (Robo) is the founding member of a conserved family of repulsive axon guidance receptors that respond to secreted Slit proteins. Here we present evidence that the SH3-SH2 adaptor protein Dreadlocks (Dock), the p21-activated serine-threonine kinase (Pak), and the Rac1/Rac2/Mtl small GTPases can function during Robo repulsion. Loss-of-function and genetic interaction experiments suggest that limiting the function of Dock, Pak, or Rac partially disrupts Robo repulsion. In addition, Dock can directly bind to Robo's cytoplasmic domain, and the association of Dock and Robo is enhanced by stimulation with Slit. Furthermore, Slit stimulation can recruit a complex of Dock and Pak to the Robo receptor and trigger an increase in Rac1 activity. These results provide a direct physical link between the Robo receptor and an important cytoskeletal regulatory protein complex and suggest that Rac can function in both attractive and repulsive axon guidance.

  18. S-wave π-nucleus repulsion and dirac phenomenology

    International Nuclear Information System (INIS)

    Chakravarti, S.; Jennings, B.K.

    1993-12-01

    A relativistic π-nucleon potential is extended to m* ≠ m to investigate the possibility of generating s-wave π-nucleus repulsion. We find that relativity does indeed generate significant repulsion, the exact amount depending on the details of the calculation. In contradistinction the tp approximation gives very little repulsion. (author). 18 refs., 3 tabs., 2 figs

  19. Electron attraction mediated by Coulomb repulsion.

    Science.gov (United States)

    Hamo, A; Benyamini, A; Shapir, I; Khivrich, I; Waissman, J; Kaasbjerg, K; Oreg, Y; von Oppen, F; Ilani, S

    2016-07-21

    One of the defining properties of electrons is their mutual Coulomb repulsion. However, in solids this basic property may change; for example, in superconductors, the coupling of electrons to lattice vibrations makes the electrons attract one another, leading to the formation of bound pairs. Fifty years ago it was proposed that electrons can be made attractive even when all of the degrees of freedom in the solid are electronic, by exploiting their repulsion from other electrons. This attraction mechanism, termed 'excitonic', promised to achieve stronger and more exotic superconductivity. Yet, despite an extensive search, experimental evidence for excitonic attraction has yet to be found. Here we demonstrate this attraction by constructing, from the bottom up, the fundamental building block of the excitonic mechanism. Our experiments are based on quantum devices made from pristine carbon nanotubes, combined with cryogenic precision manipulation. Using this platform, we demonstrate that two electrons can be made to attract each other using an independent electronic system as the 'glue' that mediates attraction. Owing to its tunability, our system offers insights into the underlying physics, such as the dependence of the emergent attraction on the underlying repulsion, and the origin of the pairing energy. We also demonstrate transport signatures of excitonic pairing. This experimental demonstration of excitonic pairing paves the way for the design of exotic states of matter.

  20. Guidance of vascular development: lessons from the nervous system.

    Science.gov (United States)

    Larrivée, Bruno; Freitas, Catarina; Suchting, Steven; Brunet, Isabelle; Eichmann, Anne

    2009-02-27

    The vascular system of vertebrates consists of an organized, branched network of arteries, veins, and capillaries that penetrates all the tissues of the body. One of the most striking features of the vascular system is that its branching pattern is highly stereotyped, with major and secondary branches forming at specific sites and developing highly conserved organ-specific vascular patterns. The factors controlling vascular patterning are not yet completely understood. Recent studies have highlighted the anatomic and structural similarities between blood vessels and nerves. The 2 networks are often aligned, with nerve fibers and blood vessels following parallel routes. Furthermore, both systems require precise control over their guidance and growth. Several molecules with attractive and repulsive properties have been found to modulate the proper guidance of both nerves and blood vessels. These include the Semaphorins, the Slits, and the Netrins and their receptors. In this review, we describe the molecular mechanisms by which blood vessels and axons achieve proper path finding and the molecular cues that are involved in their guidance.

  1. Geometric constructions for repulsive gravity and quantization

    International Nuclear Information System (INIS)

    Hohmann, Manuel

    2010-11-01

    In this thesis we present two geometric theories designed to extend general relativity. It can be seen as one of the aims of such theories to model the observed accelerating expansion of the universe as a gravitational phenomenon, or to provide a mathematical structure for the formulation of quantum field theories on curved spacetimes and quantum gravity. This thesis splits into two parts: In the first part we consider multimetric gravity theories containing N>1 standard model copies which interact only gravitationally and repel each other in the Newtonian limit. The dynamics of each of the standard model copies is governed by its own metric tensor. We show that the antisymmetric case, in which the mutual repulsion between the different matter sectors is of equal strength compared to the attractive gravitational force within each sector, is prohibited by a no-go theorem for N=2. We further show that this theorem does not hold for N>2 by explicitly constructing an antisymmetric multimetric repulsive gravity theory. We then examine several properties of this theory. Most notably, we derive a simple cosmological model and show that the accelerating expansion of the late universe can indeed be explained by the mutual repulsion between the different matter sectors. We further present a simple model for structure formation and show that our model leads to the formation of filament-like structures and voids. Finally, we show that multimetric repulsive gravity is compatible with high-precision solar system data using the parametrized post-Newtonian formalism. In the second part of the thesis we propose a mathematical model of quantum spacetime as an infinite-dimensional manifold locally homeomorphic to an appropriate Schwartz space. This extends and unifies both the standard function space construction of quantum mechanics and the differentiable manifold structure of classical spacetime. In this picture we demonstrate that classical spacetime emerges as a finite

  2. Mirror nesting and repulsion-induced superconductivity

    International Nuclear Information System (INIS)

    Belyavsky, Vladimir I.; Kapaev, Vladimir V.; Kopaev, Yurii V.

    2004-01-01

    Mirror nesting condition that is a rise of pair Fermi contour due to matching of some pieces of the Fermi contour and an isoline of the pair-relative-motion kinetic energy may be satisfied, at definite total pair momenta, due to special features of electron dispersion. Perfect mirror nesting results in a rise of the possibility of superconducting ordering up to arbitrary small pairing repulsive interaction strength. Due to kinematical constraints, the order parameter exists only inside some definite domain of the momentum space and changes its sign on a line belonging to this domain

  3. Geometric constructions for repulsive gravity and quantization

    Energy Technology Data Exchange (ETDEWEB)

    Hohmann, Manuel

    2010-11-15

    In this thesis we present two geometric theories designed to extend general relativity. It can be seen as one of the aims of such theories to model the observed accelerating expansion of the universe as a gravitational phenomenon, or to provide a mathematical structure for the formulation of quantum field theories on curved spacetimes and quantum gravity. This thesis splits into two parts: In the first part we consider multimetric gravity theories containing N>1 standard model copies which interact only gravitationally and repel each other in the Newtonian limit. The dynamics of each of the standard model copies is governed by its own metric tensor. We show that the antisymmetric case, in which the mutual repulsion between the different matter sectors is of equal strength compared to the attractive gravitational force within each sector, is prohibited by a no-go theorem for N=2. We further show that this theorem does not hold for N>2 by explicitly constructing an antisymmetric multimetric repulsive gravity theory. We then examine several properties of this theory. Most notably, we derive a simple cosmological model and show that the accelerating expansion of the late universe can indeed be explained by the mutual repulsion between the different matter sectors. We further present a simple model for structure formation and show that our model leads to the formation of filament-like structures and voids. Finally, we show that multimetric repulsive gravity is compatible with high-precision solar system data using the parametrized post-Newtonian formalism. In the second part of the thesis we propose a mathematical model of quantum spacetime as an infinite-dimensional manifold locally homeomorphic to an appropriate Schwartz space. This extends and unifies both the standard function space construction of quantum mechanics and the differentiable manifold structure of classical spacetime. In this picture we demonstrate that classical spacetime emerges as a finite

  4. Horizontal vectorization of electron repulsion integrals.

    Science.gov (United States)

    Pritchard, Benjamin P; Chow, Edmond

    2016-10-30

    We present an efficient implementation of the Obara-Saika algorithm for the computation of electron repulsion integrals that utilizes vector intrinsics to calculate several primitive integrals concurrently in a SIMD vector. Initial benchmarks display a 2-4 times speedup with AVX instructions over comparable scalar code, depending on the basis set. Speedup over scalar code is found to be sensitive to the level of contraction of the basis set, and is best for (lAlB|lClD) quartets when lD  = 0 or lB=lD=0, which makes such a vectorization scheme particularly suitable for density fitting. The basic Obara-Saika algorithm, how it is vectorized, and the performance bottlenecks are analyzed and discussed. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  5. Holographic repulsion and confinement in gauge theory

    Science.gov (United States)

    Husain, Viqar; Kothawala, Dawood

    2013-02-01

    We show that for asymptotically anti-de Sitter (AdS) backgrounds with negative energy, such as the AdS soliton and regulated negative-mass AdS-Schwarzshild metrics, the Wilson loop expectation value in the AdS/CFT conjecture exhibits a Coulomb to confinement transition. We also show that the quark-antiquark (q \\bar{q}) potential can be interpreted as affine time along null geodesics on the minimal string worldsheet and that its intrinsic curvature provides a signature of transition to confinement phase. Our results suggest a generic (holographic) relationship between confinement in gauge theory and repulsive gravity, which in turn is connected with singularity avoidance in quantum gravity. Communicated by P R L V Moniz

  6. Decay modes of two repulsively interacting bosons

    International Nuclear Information System (INIS)

    Kim, Sungyun; Brand, Joachim

    2011-01-01

    We study the decay of two repulsively interacting bosons tunnelling through a delta potential barrier by a direct numerical solution of the time-dependent Schroedinger equation. The solutions are analysed according to the regions of particle presence: both particles inside the trap (in-in), one particle in and one particle out (in-out) and both particles outside (out-out). It is shown that the in-in probability is dominated by the exponential decay, and its decay rate is predicted very well from outgoing boundary conditions. Up to a certain range of interaction strength, the decay of in-out probability is dominated by the single-particle decay mode. The decay mechanisms are adequately described by simple models.

  7. A repulsive magnetic force driven translation micromirror

    International Nuclear Information System (INIS)

    Xue, Yuan; Zuo, Hui; He, Siyuan

    2017-01-01

    This paper presents a repulsive magnetic force driven micromirror with large displacement and high surface quality which well solves the limitation of the previous design, i.e. large variation in translation starting position and low repeatability, caused by the touching points between the moving film and substrate before and in operation. The new design utilizes a driving mechanism, i.e. permanent magnet ring above and electromagnet underneath the moving film, to lift the moving film from touching the substrate and generate a repulsive magnetic force (instead of attractive force in the previous design) to push the moving film up and away from the substrate for translation. Due to the touching, the previous design has to pre-oscillate for 20–30 min at 1 Hz before usage (after resting for a few hours) to reduce the starting position variation from ∼15 µ m to 3–4 µ m. Even after the pre-oscillation, the repeatability is still low, which is 14.2% because of the touching in operation. In the design presented in this paper, the touching between the moving film and the substrate is completely eliminated before and in operation. As a result, the starting position of the translating mirror is constant each time and the repeatability is  <1%. In addition, this design does not need the residual stress gradient to curve up the moving film. The maximum displacement of 144 µ m can be achieved when 140 mA current is applied on the electromagnet. As an application, the micromirror is used as the movable mirror in a Michelson interferometer to measure the wavelength of a laser beam. The result shows a measurement accuracy of 2.19% for a 532 nm laser beam. (paper)

  8. A repulsive magnetic force driven translation micromirror

    Science.gov (United States)

    Xue, Yuan; Zuo, Hui; He, Siyuan

    2017-10-01

    This paper presents a repulsive magnetic force driven micromirror with large displacement and high surface quality which well solves the limitation of the previous design, i.e. large variation in translation starting position and low repeatability, caused by the touching points between the moving film and substrate before and in operation. The new design utilizes a driving mechanism, i.e. permanent magnet ring above and electromagnet underneath the moving film, to lift the moving film from touching the substrate and generate a repulsive magnetic force (instead of attractive force in the previous design) to push the moving film up and away from the substrate for translation. Due to the touching, the previous design has to pre-oscillate for 20-30 min at 1 Hz before usage (after resting for a few hours) to reduce the starting position variation from ~15 µm to 3-4 µm. Even after the pre-oscillation, the repeatability is still low, which is 14.2% because of the touching in operation. In the design presented in this paper, the touching between the moving film and the substrate is completely eliminated before and in operation. As a result, the starting position of the translating mirror is constant each time and the repeatability is  <1%. In addition, this design does not need the residual stress gradient to curve up the moving film. The maximum displacement of 144 µm can be achieved when 140 mA current is applied on the electromagnet. As an application, the micromirror is used as the movable mirror in a Michelson interferometer to measure the wavelength of a laser beam. The result shows a measurement accuracy of 2.19% for a 532 nm laser beam.

  9. Fast Electron Repulsion Integrals for Molecular Coulomb Sturmians

    DEFF Research Database (Denmark)

    Avery, James Emil

    2013-01-01

    A new method is presented for calculating interelectron repulsion integrals for molecular Coulomb Sturmian basis sets. This makes use of an expansion of densities in terms of 2k-Sturmians, and the interelectron repulsion integrals are then calculated by a method based on the theory of hyperspheri......A new method is presented for calculating interelectron repulsion integrals for molecular Coulomb Sturmian basis sets. This makes use of an expansion of densities in terms of 2k-Sturmians, and the interelectron repulsion integrals are then calculated by a method based on the theory...... of hyperspherical harmonics. A rudimentary software library has been implemented and preliminary benchmarks indicate very good performance: On average 40 ns, or approximately 80 clock cycles, per electron repulsion integral. This makes molecular Coulomb Sturmians competitive with Gaussian type orbitals in terms...

  10. Axelrod models of social influence with cultural repulsion

    Science.gov (United States)

    Radillo-Díaz, Alejandro; Pérez, Luis A.; Del Castillo-Mussot, Marcelo

    2009-12-01

    Since both attractive and repulsive effects among agents are important in social systems, we present simulations of two models based on Axelrod’s homogenization mechanism that includes repulsion. These models are the repulsive model, where all individuals can repel, and the partially repulsive model where only a fraction of repelling agents are considered. In these two models, attractive dynamics is implemented for agents with the ability to repel each other only if the number of features shared by them is greater than a threshold parameter. Otherwise, repelling dynamics is used. In the repulsive model, the transition from a monocultural state to a fragmented one often occurs abruptly from one cultural-variability value to the next one and a second transition emerges. For the partially repulsive model, there are also two different transitions present: the initial one being as abrupt as the one found for the repulsive model, whereas the second one follows a less abrupt behavior and resembles that of the original Axelrod model. However, the second transition for this model occurrs from a partially fragmented state and not from a monocultural one.

  11. Role of Coulomb repulsion in multilayer cuprate superconductor

    International Nuclear Information System (INIS)

    Singh Chauhan, Ekta; Singh, Vipul; Masih, Piyush

    2012-01-01

    Although BCS theory completely neglects coulomb repulsion; Anderson and Morel showed very early that it plays a central role in superconductivity. Since all high T c superconductors are based on the structure of closely spaced square planner CuO 2 layers and role of interlayer interaction plays important role in enhancement of T c . Therefore the work has been dealt with 'Role of Coulomb repulsion in Multilayer Cuprate Superconductors'. An expression for transition temperature T c is obtained by using simple integration technique and is numerically solved. It has found that T c decreases with electronic repulsion. (author)

  12. Image Guidance

    Science.gov (United States)

    Guidance that explains the process for getting images approved in One EPA Web microsites and resource directories. includes an appendix that shows examples of what makes some images better than others, how some images convey meaning more than others

  13. Is repulsion good for the health of chimeras?

    Science.gov (United States)

    Jalan, Sarika; Ghosh, Saptarshi; Patra, Bibhabasu

    2017-10-01

    Yes! Very much so. A chimera state refers to the coexistence of a coherent-incoherent dynamical evolution of identically coupled oscillators. We investigate the impact of multiplexing of a layer having repulsively coupled oscillators on the occurrence of chimeras in the layer having attractively coupled identical oscillators. We report that there exists an enhancement in the appearance of the chimera state in one layer of the multiplex network in the presence of repulsive coupling in the other layer. Furthermore, we show that a small amount of inhibition or repulsive coupling in one layer is sufficient to yield the chimera state in another layer by destroying its synchronized behavior. These results can be used to obtain insight into dynamical behaviors of those systems where both attractive and repulsive couplings exist among their constituents.

  14. The Discovery of Gravitational Repulsion by Johannes Droste

    Science.gov (United States)

    McGruder, Charles Hosewell; VanDerMeer, B. Wieb

    2018-01-01

    In 1687 Newton published his universal law of gravitation, which states that the gravitational force is always attractive. This law is based on our terrestrial experience with slowly moving bodies (v Einstein completed his theory of general relativity (also referred to as Einstein’s Theory of Gravitation), which is valid not just for slowly moving bodies but also for those with relativistic velocities. In 1916 Johannes Droste submitted a PhD thesis on general relativity to his advisor, H.A. Lorentz. In it he calculated the motion of a particle in what he called a “single center” and today we call the Schwarzschild field and found that highly relativistic particles experience gravitational repulsion. Thus, his thesis written in Dutch and never before translated contains the discovery of gravitational repulsion. Because of its historical importance we translate the entire section of his thesis containing the discovery of gravitational repulsion. We also translate his thesis in the hope of clearing up a major historical misconception. Namely, that David Hilbert in 1917 discovered gravitational repulsion. In fact, Hilbert rediscovered it, apparently completely independent of Droste’s work. Finally we note that one of the biggest mysteries of astrophysics is the question of how highly energetic particles in relativistic jets and cosmic rays are accelerated. It has been suggested that gravitational repulsion is the mechanism responsible for these phenomena. An historical understanding of gravitational repulsion is therefore pertinent.

  15. Effect of the repulsive force in the HTSC-permanent magnet hybrid bearing system

    International Nuclear Information System (INIS)

    Ohashi, S.; Kobayashi, S.

    2009-01-01

    Magnetic levitation using the pinning force of the YBaCuO high-T c bulk superconductor (HTSC) materials has an advantage to achieve stable levitation without control. To increase levitation force, the HTSC-permanent magnet hybrid magnetic bearing system is introduced. A circular shaped three phase Nd-Fe-B permanent magnet is installed on the rotor, and HTSC bulk superconductor is set on the stator. The additional permanent magnet is installed under the HTSC. Repulsive force of the permanent magnet is used for levitation, and pinning force between the HTSC and permanent magnet is used for guidance force of the bearing. In this system, relationship between permanent magnet and the HTSC is important. When repulsive force of the permanent magnet is large, pinning force of superconductor is used to keep the rotor position. As a result, stability for the lateral direction is decreased with hybrid system. For levitation force, effect of the hybrid system is not observed with column HTSC. Compared with the ring HTSC results, the following thing is considered. Because there is no space that flux of one permanent magnet acts on the other one with the column HTSC configuration, interaction between two permanent magnets becomes small.

  16. Fixed-Wing UAVs Flock Control through Cohesion and Repulsion Behaviours Combined with a Leadership

    Directory of Open Access Journals (Sweden)

    Cezary Kownacki

    2016-02-01

    Full Text Available The aim of this paper is to present a novel approach to swarm control of small fixed-wing UAVs, which combines only two flocking behaviours with a leadership feature. In the presented approach, two fundamental rules of Reynolds flocking are applied, i.e., cohesion and repulsion, as the base of a decentralized control of self-organization of the flock. These rules are combined with a leadership feature, which is responsible for a global behaviour of guidance, as in the case of animals. Such a bio-inspired combination allows the achievement of a coherent collective flight of a flock of fixed-wing UAVs without applying formal behaviours of migration and alignment. This highly simplifies an implementation of the algorithm. The presented results include both numerical simulations and experimental flights, which validate the hardware implementation of the approach.

  17. Modulation of repulsive forces between neurofilaments by sidearm phosphorylation

    International Nuclear Information System (INIS)

    Kumar, Sanjay; Hoh, Jan H.

    2004-01-01

    Recent studies have advanced the notion that the axonal organization of neurofilaments (NFs) is based on mutual steric repulsion between the unstructured 'sidearm' domains of adjacent NFs. Here, we present experimental evidence that these repulsive forces are modulated by the degree of sidearm phosphorylation. When NFs are sedimented into a gelatinous pellet, pellet volume falls with increasing ionic strength and enzymatic dephosphorylation; sedimentation of phosphorylated NFs in the presence of divalent cations also dramatically reduces pellet volume. Further, atomic force microscopy imaging of isolated mammalian NFs reveals robust exclusion of colloidal particles from the NF backbone that is reduced at high ionic strength and attenuated when the filaments are enzymatically dephosphorylated. Phosphate-phosphate repulsion on the NF sidearm appears to modulate NF excluded volume in a graded fashion, thereby controlling axonal NF organization through interfilament forces

  18. Repulsive gravitational forces: A possible mechanism for clustering

    International Nuclear Information System (INIS)

    Eisenstaedt, J.

    1977-01-01

    It is well known that, in a homogeneous cosmological universe, a positive cosmological constant induces repulsive forces. We show here that in a locally inhomogeneous cosmological model these repulsive forces are related to the sign of q, the deceleration parameter of the associated cosmological space, and to the sign of m, the apparent mass of the central perturbation (which can be negative with a positive energy density everywhere). When q is almost zero--crossing the value zero--small random perturbations of the matter density are the sources of a gravitational instability which can generate a mechanism of fragmentation in an a priori homogeneous universe

  19. Repulsive Casimir-Polder potential by a negative reflecting surface

    Science.gov (United States)

    Yuan, Qi-Zhang

    2015-07-01

    We present a scheme to generate an all-range long repulsive Casimir-Polder potential between a perfect negative reflecting surface and a ground-state atom. The repulsive potential is stable and does not decay with time. The Casimir-Polder potential is proportional to z-2 at short atom-surface distances and to z-4 at long atom-surface distances. Because of these advantages, this potential can help in building quantum reflectors, quantum levitating devices, and waveguides for matter waves.

  20. Repulsive Casimir force in Bose–Einstein Condensate

    Science.gov (United States)

    Mehedi Faruk, Mir; Biswas, Shovon

    2018-04-01

    We study the Casimir effect for a three dimensional system of ideal free massive Bose gas in a slab geometry with Zaremba and anti-periodic boundary conditions. It is found that for these type of boundary conditions the resulting Casimir force is repulsive in nature, in contrast with usual periodic, Dirichlet or Neumann boundary condition where the Casimir force is attractive (Martin and Zagrebnov 2006 Europhys. Lett. 73 15). Casimir forces in these boundary conditions also maintain a power law decay function below condensation temperature and exponential decay function above the condensation temperature albeit with a positive sign, identifying the repulsive nature of the force.

  1. Viscoelastic properties of attractive and repulsive colloidal glasses

    International Nuclear Information System (INIS)

    Puertas, Antonio M; Zaccarelli, Emanuela; Sciortino, Francesco

    2005-01-01

    We report a numerical study of the shear viscosity and the frequency dependent elastic moduli close to dynamical arrest for a model of short range attractive colloids, both for the repulsive and the attractive glass transition. Calculating the stress autocorrelation functions, we find that density fluctuations of wavevectors close to the first peak in the structure factor control the viscosity rise on approaching the repulsive glass, while fluctuations of larger wavevectors control the viscosity close to the attractive glass. On approaching the glass transition, the viscosity diverges with a power law with the same exponent as the density autocorrelation time. (letter to the editor)

  2. Cucker-Smale Flocking with Bounded Cohesive and Repulsive Forces

    Directory of Open Access Journals (Sweden)

    Qiang Song

    2013-01-01

    Full Text Available This paper proposes two Cucker-Smale-type flocking models by introducing both cohesive and repulsive forces to second-order multiagent systems. Under some mild conditions on the initial state of the flocking system, it is shown that the velocity consensus of the agents can be reached independent of the parameter which describes the decay of communication rates. In particular, the collision between any two agents can always be avoided by designing an appropriate bounded repulsive function based on the initial energy of the flock. Numerical examples are given to demonstrate the effectiveness of the theoretical analysis.

  3. Repulsion-based model for contact angle saturation in electrowetting.

    Science.gov (United States)

    Ali, Hassan Abdelmoumen Abdellah; Mohamed, Hany Ahmed; Abdelgawad, Mohamed

    2015-01-01

    We introduce a new model for contact angle saturation phenomenon in electrowetting on dielectric systems. This new model attributes contact angle saturation to repulsion between trapped charges on the cap and base surfaces of the droplet in the vicinity of the three-phase contact line, which prevents these surfaces from converging during contact angle reduction. This repulsion-based saturation is similar to repulsion between charges accumulated on the surfaces of conducting droplets which causes the well known Coulombic fission and Taylor cone formation phenomena. In our model, both the droplet and dielectric coating were treated as lossy dielectric media (i.e., having finite electrical conductivities and permittivities) contrary to the more common assumption of a perfectly conducting droplet and perfectly insulating dielectric. We used theoretical analysis and numerical simulations to find actual charge distribution on droplet surface, calculate repulsion energy, and minimize energy of the total system as a function of droplet contact angle. Resulting saturation curves were in good agreement with previously reported experimental results. We used this proposed model to predict effect of changing liquid properties, such as electrical conductivity, and system parameters, such as thickness of the dielectric layer, on the saturation angle, which also matched experimental results.

  4. An Adaptation-Induced Repulsion Illusion in Tactile Spatial Perception

    Directory of Open Access Journals (Sweden)

    Lux Li

    2017-06-01

    Full Text Available Following focal sensory adaptation, the perceived separation between visual stimuli that straddle the adapted region is often exaggerated. For instance, in the tilt aftereffect illusion, adaptation to tilted lines causes subsequently viewed lines with nearby orientations to be perceptually repelled from the adapted orientation. Repulsion illusions in the nonvisual senses have been less studied. Here, we investigated whether adaptation induces a repulsion illusion in tactile spatial perception. In a two-interval forced-choice task, participants compared the perceived separation between two point-stimuli applied on the forearms successively. Separation distance was constant on one arm (the reference and varied on the other arm (the comparison. In Experiment 1, we took three consecutive baseline measurements, verifying that in the absence of manipulation, participants’ distance perception was unbiased across arms and stable across experimental blocks. In Experiment 2, we vibrated a region of skin on the reference arm, verifying that this focally reduced tactile sensitivity, as indicated by elevated monofilament detection thresholds. In Experiment 3, we applied vibration between the two reference points in our distance perception protocol and discovered that this caused an illusory increase in the separation between the points. We conclude that focal adaptation induces a repulsion aftereffect illusion in tactile spatial perception. The illusion provides clues as to how the tactile system represents spatial information. The analogous repulsion aftereffects caused by adaptation in different stimulus domains and sensory systems may point to fundamentally similar strategies for dynamic sensory coding.

  5. 4-center STO interelectron repulsion integrals with Coulomb Sturmians

    DEFF Research Database (Denmark)

    Avery, James Emil; Avery, John Scales

    2018-01-01

    Abstract We present a method for evaluating 4-center electron repulsion integrals (ERI) for Slater-type orbitals by way of expansions in terms of Coulomb Sturmians. The ERIs can then be evaluated using our previously published methods for rapid evaluation of Coulomb Sturmians through hyperspherical...

  6. Quest for Casimir repulsion between Chern-Simons surfaces

    Science.gov (United States)

    Fialkovsky, Ignat; Khusnutdinov, Nail; Vassilevich, Dmitri

    2018-04-01

    In this paper we critically reconsider the Casimir repulsion between surfaces that carry the Chern-Simons interaction (corresponding to the Hall-type conductivity). We present a derivation of the Lifshitz formula valid for arbitrary planar geometries and discuss its properties. This analysis allows us to resolve some contradictions in the previous literature. We compute the Casimir energy for two surfaces that have constant longitudinal and Hall conductivities. The repulsion is possible only if both surfaces have Hall conductivities of the same sign. However, there is a critical value of the longitudinal conductivity above which the repulsion disappears. We also consider a model where both parity odd and parity even terms in the conductivity are produced by the polarization tensor of surface modes. In contrast to the previous publications [L. Chen and S.-L. Wan, Phys. Rev. B 84, 075149 (2011), 10.1103/PhysRevB.84.075149; Phys. Rev. B 85, 115102 (2012), 10.1103/PhysRevB.85.115102], we include the parity anomaly term. This term ensures that the conductivities vanish for infinitely massive surface modes. We find that at least for a single mode, regardless of the sign and value of its mass, there is no Casimir repulsion.

  7. Melting-curve extrema from a repulsive ''step'' potential

    International Nuclear Information System (INIS)

    Young, D.A.; Alder, B.J.

    1977-01-01

    Molecular dynamics calculations in two dimensions for particles interacting with a repulsive ''step'' potential show melting-curve maxima and minima as well as solid-solid phase transitions. These features are similar to those observed in the phase diagram of cesium and cerium

  8. The Role of Repulsion in Colloidal Crystal Engineering with DNA

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Soyoung E. [Department; Li, Tao [X-ray; Senesi, Andrew J. [X-ray; Mirkin, Chad A. [Department; Lee, Byeongdu [X-ray

    2017-11-07

    Hybridization interactions between DNA-functionalized nanoparticles (DNA-NPs) can be used to program the crystallization behavior of superlattices, yielding access to complex three-dimensional structures with more than 30 different lattice symmetries. The first superlattice structures using DNA-NPs as building blocks were identified almost two decades ago, yet the role of repulsive interactions in guiding structure formation is still largely unexplored. Here, a com-prehensive approach is taken to study the role of repulsion in the assembly behavior of DNA-NPs, enabling the calculation of interparticle interaction potentials based on experimental results. In this work, we used two different means to assemble DNA-NPs—Watson-Crick base pairing interactions and depletion interactions—and systematically varied the salt concen-tration to study the effective interactions in DNA-NP superlattices. A comparison between the two systems allows us to decouple the repulsive forces from the attractive hybridization interactions that are sensitive to the ionic environment. We find that the gap distance between adjacent DNA-NPs follows a simple power law dependence on solution ionic strength regardless of the type of attractive forces present. This result suggests that the observed trend is driven by repulsive inter-actions. To better understand such behavior, we propose a mean-field model that provides a mathematical description for the observed trend. This model shows that the trend is due to the variation in the effective cross-sectional diameter of DNA duplex and the thickness of DNA shell.

  9. Spontaneous symmetry breaking in vortex systems with two repulsive lengthscales.

    Science.gov (United States)

    Curran, P J; Desoky, W M; Milosević, M V; Chaves, A; Laloë, J-B; Moodera, J S; Bending, S J

    2015-10-23

    Scanning Hall probe microscopy (SHPM) has been used to study vortex structures in thin epitaxial films of the superconductor MgB2. Unusual vortex patterns observed in MgB2 single crystals have previously been attributed to a competition between short-range repulsive and long-range attractive vortex-vortex interactions in this two band superconductor; the type 1.5 superconductivity scenario. Our films have much higher levels of disorder than bulk single crystals and therefore both superconducting condensates are expected to be pushed deep into the type 2 regime with purely repulsive vortex interactions. We observe broken symmetry vortex patterns at low fields in all samples after field-cooling from above Tc. These are consistent with those seen in systems with competing repulsions on disparate length scales, and remarkably similar structures are reproduced in dirty two band Ginzburg-Landau calculations, where the simulation parameters have been defined by experimental observations. This suggests that in our dirty MgB2 films, the symmetry of the vortex structures is broken by the presence of vortex repulsions with two different lengthscales, originating from the two distinct superconducting condensates. This represents an entirely new mechanism for spontaneous symmetry breaking in systems of superconducting vortices, with important implications for pinning phenomena and high current density applications.

  10. Mode repulsion of ultrasonic guided waves in rails

    CSIR Research Space (South Africa)

    Loveday, Philip W

    2018-03-01

    Full Text Available . The modes can therefore be numbered in the same way that Lamb waves in plates are numbered, making it easier to communicate results. The derivative of the eigenvectors with respect to wavenumber contains the same repulsion term and shows how the mode shapes...

  11. Repulsive Casimir force from fractional Neumann boundary conditions

    International Nuclear Information System (INIS)

    Lim, S.C.; Teo, L.P.

    2009-01-01

    This Letter studies the finite temperature Casimir force acting on a rectangular piston associated with a massless fractional Klein-Gordon field at finite temperature. Dirichlet boundary conditions are imposed on the walls of a d-dimensional rectangular cavity, and a fractional Neumann condition is imposed on the piston that moves freely inside the cavity. The fractional Neumann condition gives an interpolation between the Dirichlet and Neumann conditions, where the Casimir force is known to be always attractive and always repulsive respectively. For the fractional Neumann boundary condition, the attractive or repulsive nature of the Casimir force is governed by the fractional order which takes values from zero (Dirichlet) to one (Neumann). When the fractional order is larger than 1/2, the Casimir force is always repulsive. For some fractional orders that are less than but close to 1/2, it is shown that the Casimir force can be either attractive or repulsive depending on the aspect ratio of the cavity and the temperature.

  12. The similarity of attractive and repulsive forces on a lattice

    Science.gov (United States)

    Mirahmadi, Marjan-S.; Fatollahi, Amir H.; Khorrami, Mohammad

    2015-07-01

    On a lattice, as the momentum space is compact, the kinetic energy is bounded not only from below but also from above. It is shown that this somehow removes the distinction between repulsive and attractive forces. In particular, it is seen that a region with attractive force would appear forbidden for states with energies higher than a certain value, while repulsive forces could develop bound-states. An explicit transformation is introduced which transforms the spectrum of a system corresponding to a repulsive force, to that of a similar system corresponding to an attractive force. Explicit numerical examples are presented for discrete energies of bound-states of a particle experiencing repulsive force by a piecewise constant potential. Finally, the parameters of a specific one-dimensional (1D) translationally invariant system on continuum are tuned so that the energy of the system resembles the kinetic energy of a system on a 1D lattice. In particular, the parameters are tuned so that while the width of the first energy band and its position are kept finite, the gap between the first energy band and the next energy band goes to infinity, so that effectively only the first energy band is relevant.

  13. One-loop quantum gravity repulsion in the early Universe.

    Science.gov (United States)

    Broda, Bogusław

    2011-03-11

    Perturbative quantum gravity formalism is applied to compute the lowest order corrections to the classical spatially flat cosmological Friedmann-Lemaître-Robertson-Walker solution (for the radiation). The presented approach is analogous to the approach applied to compute quantum corrections to the Coulomb potential in electrodynamics, or rather to the approach applied to compute quantum corrections to the Schwarzschild solution in gravity. In the framework of the standard perturbative quantum gravity, it is shown that the corrections to the classical deceleration, coming from the one-loop graviton vacuum polarization (self-energy), have (UV cutoff free) opposite to the classical repulsive properties which are not negligible in the very early Universe. The repulsive "quantum forces" resemble those known from loop quantum cosmology.

  14. Coulomb repulsion in (TMTSF)2X and (TMTTF)2X

    DEFF Research Database (Denmark)

    Mortensen, Kell; Engler, E. M.

    1985-01-01

    On the basis of studies of transport properties of (TMTSF)2 X, (TMTTF)2X and their binary alloys the authors discuss the role of on-site Coulomb repulsion relative to the transfer integrals. In TMTTF-salts U/ta are believed to be large, resulting in a Hubbard gap, whereas U/ta in TMTSF-salts are ......On the basis of studies of transport properties of (TMTSF)2 X, (TMTTF)2X and their binary alloys the authors discuss the role of on-site Coulomb repulsion relative to the transfer integrals. In TMTTF-salts U/ta are believed to be large, resulting in a Hubbard gap, whereas U/ta in TMTSF...

  15. Pattern formation in annular systems of repulsive particles

    International Nuclear Information System (INIS)

    Marschler, Christian; Starke, Jens; Sørensen, Mads P.; Gaididei, Yuri B.; Christiansen, Peter L.

    2016-01-01

    General particle models with symmetric and asymmetric repulsion are studied and investigated for finite-range and exponential interaction in an annulus. In the symmetric case transitions from one- to multi-lane behavior including multistability are observed for varying particle density and for a varying curvature with fixed density. Hence, the system cannot be approximated by a periodic channel. In the asymmetric case, which is important in pedestrian dynamics, we reveal an inhomogeneous new phase, a traveling wave reminiscent of peristaltic motion. - Highlights: • An asymmetrically interacting repulsive particle model is introduced. • Multi-stability is found in a pedestrian dynamics model. • Transitions from one- to multi-lane behavior are studied numerically.

  16. Understanding valence-shell electron-pair repulsion (VSEPR) theory using origami molecular models

    International Nuclear Information System (INIS)

    Saraswati, Teguh Endah; Saputro, Sulistyo; Ramli, Murni; Praseptiangga, Danar; Khasanah, Nurul; Marwati, Sri

    2017-01-01

    Valence-shell electron-pair repulsion (VSEPR) theory is conventionally used to predict molecular geometry. However, it is difficult to explore the full implications of this theory by simply drawing chemical structures. Here, we introduce origami modelling as a more accessible approach for exploration of the VSEPR theory. Our technique is simple, readily accessible and inexpensive compared with other sophisticated methods such as computer simulation or commercial three-dimensional modelling kits. This method can be implemented in chemistry education at both the high school and university levels. We discuss the example of a simple molecular structure prediction for ammonia (NH 3 ). Using the origami model, both molecular shape and the scientific justification can be visualized easily. This ‘hands-on’ approach to building molecules will help promote understanding of VSEPR theory. (paper)

  17. Understanding valence-shell electron-pair repulsion (VSEPR) theory using origami molecular models

    Science.gov (United States)

    Endah Saraswati, Teguh; Saputro, Sulistyo; Ramli, Murni; Praseptiangga, Danar; Khasanah, Nurul; Marwati, Sri

    2017-01-01

    Valence-shell electron-pair repulsion (VSEPR) theory is conventionally used to predict molecular geometry. However, it is difficult to explore the full implications of this theory by simply drawing chemical structures. Here, we introduce origami modelling as a more accessible approach for exploration of the VSEPR theory. Our technique is simple, readily accessible and inexpensive compared with other sophisticated methods such as computer simulation or commercial three-dimensional modelling kits. This method can be implemented in chemistry education at both the high school and university levels. We discuss the example of a simple molecular structure prediction for ammonia (NH3). Using the origami model, both molecular shape and the scientific justification can be visualized easily. This ‘hands-on’ approach to building molecules will help promote understanding of VSEPR theory.

  18. Swarming and Pattern Formation due to Selective Attraction and Repulsion

    OpenAIRE

    Romanczuk, Pawel; Schimansky-Geier, Lutz

    2012-01-01

    We discuss the collective dynamics of self-propelled particles with selective attraction and repulsion interactions. Each particle, or individual, may respond differently to its neighbours depending on the sign of their relative velocity. Thus, it is able to distinguish approaching (coming closer) and retreating (moving away) individuals. This differentiation of the social response is motivated by the response to looming visual stimuli and may be seen as a generalization of the previously pro...

  19. Vortical null orbits, repulsive barriers, energy confinement in Kerr metric

    Energy Technology Data Exchange (ETDEWEB)

    Calvani, M [Padua Univ. (Italy). Ist. di Astronomia; De Felice, F

    1978-10-01

    The complete analytical description of the null trajectories in the field of a Kerr naked singularity is given. Two peculiar phenomena are described: the existence of repulsive barriers in the r < O world and the existence of null circular bound orbits which surround the singularity in 'shells'. They distribute around the surface at r = m, which is the position of the horizon in the extreme black-hole case; this suggests that a naked singularity 'remembers' the position of the last horizon.

  20. Measured long-range repulsive Casimir–Lifshitz forces

    Science.gov (United States)

    Munday, J. N.; Capasso, Federico; Parsegian, V. Adrian

    2014-01-01

    Quantum fluctuations create intermolecular forces that pervade macroscopic bodies1–3. At molecular separations of a few nanometres or less, these interactions are the familiar van der Waals forces4. However, as recognized in the theories of Casimir, Polder and Lifshitz5–7, at larger distances and between macroscopic condensed media they reveal retardation effects associated with the finite speed of light. Although these long-range forces exist within all matter, only attractive interactions have so far been measured between material bodies8–11. Here we show experimentally that, in accord with theoretical prediction12, the sign of the force can be changed from attractive to repulsive by suitable choice of interacting materials immersed in a fluid. The measured repulsive interaction is found to be weaker than the attractive. However, in both cases the magnitude of the force increases with decreasing surface separation. Repulsive Casimir–Lifshitz forces could allow quantum levitation of objects in a fluid and lead to a new class of switchable nanoscale devices with ultra-low static friction13–15. PMID:19129843

  1. Measured long-range repulsive Casimir-Lifshitz forces.

    Science.gov (United States)

    Munday, J N; Capasso, Federico; Parsegian, V Adrian

    2009-01-08

    Quantum fluctuations create intermolecular forces that pervade macroscopic bodies. At molecular separations of a few nanometres or less, these interactions are the familiar van der Waals forces. However, as recognized in the theories of Casimir, Polder and Lifshitz, at larger distances and between macroscopic condensed media they reveal retardation effects associated with the finite speed of light. Although these long-range forces exist within all matter, only attractive interactions have so far been measured between material bodies. Here we show experimentally that, in accord with theoretical prediction, the sign of the force can be changed from attractive to repulsive by suitable choice of interacting materials immersed in a fluid. The measured repulsive interaction is found to be weaker than the attractive. However, in both cases the magnitude of the force increases with decreasing surface separation. Repulsive Casimir-Lifshitz forces could allow quantum levitation of objects in a fluid and lead to a new class of switchable nanoscale devices with ultra-low static friction.

  2. Positive effects of repulsion on boundedness in a fully parabolic attraction-repulsion chemotaxis system with logistic source

    Science.gov (United States)

    Wang, Wei; Zhuang, Mengdi; Zheng, Sining

    2018-02-01

    In this paper we study the global boundedness of solutions to the fully parabolic attraction-repulsion chemotaxis system with logistic source: ut = Δu - χ∇ ṡ (u∇v) + ξ∇ ṡ (u∇w) + f (u), vt = Δv - βv + αu, wt = Δw - δw + γu, subject to homogeneous Neumann boundary conditions in a bounded and smooth domain Ω ⊂Rn (n ≥ 1), where χ, α, ξ, γ, β and δ are positive constants, and f : R → R is a smooth function generalizing the logistic source f (s) = a - bsθ for all s ≥ 0 with a ≥ 0, b > 0 and θ ≥ 1. It is shown that when the repulsion cancels the attraction (i.e. χα = ξγ), the solution is globally bounded if n ≤ 3, or θ >θn : = min ⁡ {n+2}/4, n/√{n2 + 6 n + 17 }/-n2 - 3 n + 4 4 } with n ≥ 2. Therefore, due to the inhibition of repulsion to the attraction, in any spatial dimension, the exponent θ is allowed to take values less than 2 such that the solution is uniformly bounded in time.

  3. Pattern formation in annular systems of repulsive particles

    DEFF Research Database (Denmark)

    Marschler, Christian; Starke, Jens; Sørensen, Mads Peter

    2016-01-01

    General particle models with symmetric and asymmetric repulsion are studied and investigated for finite-range and exponential interaction in an annulus. In the symmetric case transitions from one- to multi-lane behavior including multistability are observed for varying particle density and for a ...... and for a varying curvature with fixed density. Hence, the system cannot be approximated by a periodic channel. In the asymmetric case, which is important in pedestrian dynamics, we reveal an inhomogeneous new phase, a traveling wave reminiscent of peristaltic motion....

  4. Repulsive polarons and itinerant ferromagnetism in strongly polarized Fermi gases

    DEFF Research Database (Denmark)

    Massignan, Pietro; Bruun, Georg

    2011-01-01

    We analyze the properties of a single impurity immersed in a Fermi sea. At positive energy and scattering lengths, we show that the system possesses a well-defined but metastable excitation, the repulsive polaron, and we calculate its energy, quasiparticle residue and effective mass. From...... polarized (ferromagnetic) domains are then examined for a binary mixture of atoms with a general mass ratio. Our results indicate that mass imbalance lowers the critical interaction strength for phase-separation, but that very short quasiparticle decay times will complicate the experimental observation...

  5. Attractive and repulsive cracks in a heterogeneous material

    International Nuclear Information System (INIS)

    Cortet, Pierre-Philippe; Huillard, Guillaume; Vanel, Loïc; Ciliberto, Sergio

    2008-01-01

    We study experimentally the paths of an assembly of cracks growing in interaction in a heterogeneous two-dimensional elastic brittle material submitted to uniaxial stress. For a given initial crack assembly geometry, we observe two types of crack path. The first one corresponds to a repulsion followed by an attraction on one end of the crack and a tip-to-tip attraction on the other end. The second one corresponds to a pure attraction. Only one of the crack path types is observed in a given sample. Thus, selection between the two types appears as a statistical collective process

  6. Pairing from strong repulsion in triangular lattice Hubbard model

    Science.gov (United States)

    Zhang, Shang-Shun; Zhu, Wei; Batista, Cristian D.

    2018-04-01

    We propose a pairing mechanism between holes in the dilute limit of doped frustrated Mott insulators. Hole pairing arises from a hole-hole-magnon three-body bound state. This pairing mechanism has its roots on single-hole kinetic energy frustration, which favors antiferromagnetic (AFM) correlations around the hole. We demonstrate that the AFM polaron (hole-magnon bound state) produced by a single hole propagating on a field-induced polarized background is strong enough to bind a second hole. The effective interaction between these three-body bound states is repulsive, implying that this pairing mechanism is relevant for superconductivity.

  7. Swarming and pattern formation due to selective attraction and repulsion.

    Science.gov (United States)

    Romanczuk, Pawel; Schimansky-Geier, Lutz

    2012-12-06

    We discuss the collective dynamics of self-propelled particles with selective attraction and repulsion interactions. Each particle, or individual, may respond differently to its neighbours depending on the sign of their relative velocity. Thus, it is able to distinguish approaching (coming closer) and retreating (moving away) individuals. This differentiation of the social response is motivated by the response to looming visual stimuli and may be seen as a generalization of the previously proposed escape and pursuit interactions motivated by empirical evidence for cannibalism as a driving force of collective migration in locusts and Mormon crickets. The model can account for different types of behaviour such as pure attraction, pure repulsion or escape and pursuit, depending on the values (signs) of the different response strengths. It provides, in the light of recent experimental results, an interesting alternative to previously proposed models of collective motion with an explicit velocity-alignment interaction. We discuss the derivation of a coarse-grained description of the system dynamics, which allows us to derive analytically the necessary condition for emergence of collective motion. Furthermore, we analyse systematically the onset of collective motion and clustering in numerical simulations of the model for varying interaction strengths. We show that collective motion arises only in a subregion of the parameter space, which is consistent with the analytical prediction and corresponds to an effective escape and/or pursuit response.

  8. Nuclear many-body problem with repulsive hard core interactions

    Energy Technology Data Exchange (ETDEWEB)

    Haddad, L M

    1965-07-01

    The nuclear many-body problem is considered using the perturbation-theoretic approach of Brueckner and collaborators. This approach is outlined with particular attention paid to the graphical representation of the terms in the perturbation expansion. The problem is transformed to centre-of-mass coordinates in configuration space and difficulties involved in ordinary methods of solution of the resulting equation are discussed. A new technique, the 'reference spectrum method', devised by Bethe, Brandow and Petschek in an attempt to simplify the numerical work in presented. The basic equations are derived in this approximation and considering the repulsive hard core part of the interaction only, the effective mass is calculated at high momentum (using the same energy spectrum for both 'particle' and 'hole' states). The result of 0.87m is in agreement with that of Bethe et al. A more complete treatment using the reference spectrum method in introduced and a self-consistent set of equations is established for the reference spectrum parameters again for the case of hard core repulsions. (author)

  9. Repulsive effects of hydrophobic diamond thin films on biomolecule detection

    Energy Technology Data Exchange (ETDEWEB)

    Ruslinda, A. Rahim, E-mail: ruslindarahim@gmail.com [Institute of Nano Electronic Engineering, Universiti Malaysia Perlis, Jln Kgr-Alor Setar, Seriab, 01000 Kangar, Perlis (Malaysia); Department of Nano Science and Nano Engineering, School of Advance Science and Engineering, Ohkubo 3-4-1, Shinjuku, 169-8555 Tokyo (Japan); Ishiyama, Y. [Department of Nano Science and Nano Engineering, School of Advance Science and Engineering, Ohkubo 3-4-1, Shinjuku, 169-8555 Tokyo (Japan); Penmatsa, V. [Department of Mechanical and Materials Engineering, Florida International University, 10555 West Flagler Street, Miami, FL 33174 (United States); Ibori, S.; Kawarada, H. [Department of Nano Science and Nano Engineering, School of Advance Science and Engineering, Ohkubo 3-4-1, Shinjuku, 169-8555 Tokyo (Japan)

    2015-02-15

    Highlights: • We report the effect of fluorine plasma treatment on diamond thin film to resist the nonspecific adsorption of biomolecules. • The diamond thin film were highly hydrophobic with a surface energy value of ∼25 mN/m. • The repulsive effect shows excellent binding efficiency for both DNA and HIV-1 Tat protein. - Abstract: The repulsive effect of hydrophobic diamond thin film on biomolecule detection, such as single-nucleotide polymorphisms and human immunodeficiency virus type 1 trans-activator of transcription peptide protein detection, was investigated using a mixture of a fluorine-, amine-, and hydrogen-terminated diamond surfaces. These chemical modifications lead to the formation of a surface that effectively resists the nonspecific adsorption of proteins and other biomolecules. The effect of fluorine plasma treatment on elemental composition was also investigated via X-ray photoelectron spectroscopy (XPS). XPS results revealed a fluorocarbon layer on the diamond thin films. The contact angle measurement results indicated that the fluorine-treated diamond thin films were highly hydrophobic with a surface energy value of ∼25 mN/m.

  10. Repulsive effects of hydrophobic diamond thin films on biomolecule detection

    International Nuclear Information System (INIS)

    Ruslinda, A. Rahim; Ishiyama, Y.; Penmatsa, V.; Ibori, S.; Kawarada, H.

    2015-01-01

    Highlights: • We report the effect of fluorine plasma treatment on diamond thin film to resist the nonspecific adsorption of biomolecules. • The diamond thin film were highly hydrophobic with a surface energy value of ∼25 mN/m. • The repulsive effect shows excellent binding efficiency for both DNA and HIV-1 Tat protein. - Abstract: The repulsive effect of hydrophobic diamond thin film on biomolecule detection, such as single-nucleotide polymorphisms and human immunodeficiency virus type 1 trans-activator of transcription peptide protein detection, was investigated using a mixture of a fluorine-, amine-, and hydrogen-terminated diamond surfaces. These chemical modifications lead to the formation of a surface that effectively resists the nonspecific adsorption of proteins and other biomolecules. The effect of fluorine plasma treatment on elemental composition was also investigated via X-ray photoelectron spectroscopy (XPS). XPS results revealed a fluorocarbon layer on the diamond thin films. The contact angle measurement results indicated that the fluorine-treated diamond thin films were highly hydrophobic with a surface energy value of ∼25 mN/m

  11. Repulsive Casimir-Polder forces from cosmic strings

    International Nuclear Information System (INIS)

    Saharian, A.A.; Kotanjyan, A.S.

    2011-01-01

    We investigate the Casimir-Polder force acting on a polarizable microparticle in the geometry of a straight cosmic string. In order to develop this analysis we evaluate the electromagnetic field Green tensor on the imaginary frequency axis. The expression for the Casimir-Polder force is derived in the general case of anisotropic polarizability. In dependence on the eigenvalues for the polarizability tensor and of the orientation of its principal axes, the Casimir-Polder force can be either repulsive or attractive. Moreover, there are situations where the force changes the sign with separation. We show that for an isotropic polarizability tensor the force is always repulsive. At large separations between the microparticle and the string, the force varies inversely with the fifth power of the distance. In the non-retarded regime, corresponding to separations smaller than the relevant transition wavelengths, the force decays with the inverse fourth power of the distance. In the case of anisotropic polarizability, the dependence of the Casimir-Polder potential on the orientation of the polarizability tensor principal axes also leads to a moment of force acting on the particle. (orig.)

  12. Son of sevenless directly links the Robo receptor to rac activation to control axon repulsion at the midline.

    Science.gov (United States)

    Yang, Long; Bashaw, Greg J

    2006-11-22

    Son of sevenless (Sos) is a dual specificity guanine nucleotide exchange factor (GEF) that regulates both Ras and Rho family GTPases and thus is uniquely poised to integrate signals that affect both gene expression and cytoskeletal reorganization. Here, using genetics, biochemistry, and cell biology, we demonstrate that Sos is recruited to the plasma membrane, where it forms a ternary complex with the Roundabout receptor and the SH3-SH2 adaptor protein Dreadlocks (Dock) to regulate Rac-dependent cytoskeletal rearrangement in response to the Slit ligand. Intriguingly, the Ras and Rac-GEF activities of Sos can be uncoupled during Robo-mediated axon repulsion; Sos axon guidance function depends on its Rac-GEF activity, but not its Ras-GEF activity. These results provide in vivo evidence that the Ras and RhoGEF domains of Sos are separable signaling modules and support a model in which Robo recruits Sos to the membrane via Dock to activate Rac during midline repulsion.

  13. Repulsive DNA-DNA interactions accelerate viral DNA packaging in phage phi29

    OpenAIRE

    Keller, Nicholas; delToro, Damian; Grimes, Shelley; Jardine, Paul J.; Smith, Douglas E.

    2014-01-01

    We use optical tweezers to study the effect of attractive versus repulsive DNA-DNA interactions on motor-driven viral packaging. Screening of repulsive interactions accelerates packaging, but induction of attractive interactions by spermidine3+ causes heterogeneous dynamics. Acceleration is observed in a fraction of complexes, but most exhibit slowing and stalling, suggesting that attractive interactions promote nonequilibrium DNA conformations that impede the motor. Thus, repulsive interacti...

  14. Repulsive DNA-DNA interactions accelerate viral DNA packaging in phage Phi29.

    Science.gov (United States)

    Keller, Nicholas; delToro, Damian; Grimes, Shelley; Jardine, Paul J; Smith, Douglas E

    2014-06-20

    We use optical tweezers to study the effect of attractive versus repulsive DNA-DNA interactions on motor-driven viral packaging. Screening of repulsive interactions accelerates packaging, but induction of attractive interactions by spermidine(3+) causes heterogeneous dynamics. Acceleration is observed in a fraction of complexes, but most exhibit slowing and stalling, suggesting that attractive interactions promote nonequilibrium DNA conformations that impede the motor. Thus, repulsive interactions facilitate packaging despite increasing the energy of the theoretical optimum spooled DNA conformation.

  15. Optical absorptions of an exciton in a quantum ring: Effect of the repulsive core

    International Nuclear Information System (INIS)

    Xie, Wenfang

    2013-01-01

    We study the optical absorptions of an exciton in a quantum ring. The quantum ring is described as a circular quantum dot with a repulsive core. The advantage of our methodology is that one can investigate the influence of the repulsive core by varying two parameters in the confinement potential. The linear, third-order nonlinear and total optical absorption coefficients have been examined with the change of the confinement potential. The results show that the optical absorptions are strongly affected by the repulsive core. Moreover, the repulsive core can influence the oscillation in the resonant peak of the absorption coefficients.

  16. Repulsive Gravity in the Oppenheimer-Snyder Collapsar

    Directory of Open Access Journals (Sweden)

    Marshall T. W.

    2016-07-01

    Full Text Available The Oppenheimer-Snyder metric for a collapsing dust ball has a well defined equilib- rium state when the time coordinate goes to plus infinity. The entire ball is contained within the gravitational radius r 0 , but half of its content lies within a thin shell between r 0 and 0 : 94 r 0 . This state has the acausal property that no light ray escapes from it, but if one boundary condition at the surface, which Oppenheimer and Snyder imposed without justification, is removed, then all points in the interior remain in causal contact by null geodesics with the exterior. This modification causes the half shell’s interior radius to increase to 0 : 97 r 0 . Together with the results of a previous article on the den- sity inside a spherosymmetric neutron star, the present results indicate that, in contrast with the universal attraction of Newtonian gravity, General Relativity gives gravitational repulsion at high density.

  17. Phases and amplitudes for a modified repulsive Coulomb field

    International Nuclear Information System (INIS)

    Chidichimo, M.C.; Davison, T.S.

    1990-01-01

    The asymptotic form of the radial wave function for positive-energy states is calculated for the case of a repulsive Coulomb field. The cases of a pure Coulomb potential and a modified Coulomb potential are considered. Second-order analytic solutions for the amplitudes and phases are obtained when the modifications to the pure Coulombic potential take the form αr -2 +βr -3 +γr -4 , using the Jeffreys or WKB method. For the case of a pure Coulomb field, numerical results obtained from this method were compared with ''exact'' numerical results that were obtained using the analytic properties of the Coulomb wave functions. Tables are presented to show the conditions under which the method is accurate

  18. Attractive and Repulsive Forces on Particles in Oscillatory Flow

    Science.gov (United States)

    Agarwal, Siddhansh; Rallabandi, Bhargav; Raju, David; Thameem, Raqeeb; Hilgenfeldt, Sascha

    2016-11-01

    A large class of oscillating flows gives rise to rectified streaming motion of the fluid. It has recently been shown that particle transport in such flows, excited by bubbles oscillating at ultrasound frequencies, leads to differential displacement and efficient sorting of microparticles by size. We derive a general expression for the instantaneous radial force experienced by a small spherical particle in the vicinity of an oscillating interface, and generalize the radial projection of the Maxey-Riley equation to include this effect. Varying relevant system parameters, we show that the net effect on the particle can be either an attraction to or a repulsion from the bubble surface, depending in particular on the particle size and the particle/fluid density contrast. We demonstrate that these predictions are in agreement with a variety of experiments.

  19. Review - On-chip diamagnetic repulsion in continuous flow

    Directory of Open Access Journals (Sweden)

    Mark D Tarn, Noriyuki Hirota, Alexander Iles and Nicole Pamme

    2009-01-01

    Full Text Available We explore the potential of a microfluidic continuous flow particle separation system based on the repulsion of diamagnetic materials from a high magnetic field. Diamagnetic polystyrene particles in paramagnetic manganese (II chloride solution were pumped into a microfluidic chamber and their deflection behaviour in a high magnetic field applied by a superconducting magnet was investigated. Two particle sizes (5 and 10 μm were examined in two concentrations of MnCl2 (6 and 10%. The larger particles were repelled to a greater extent than the smaller ones, and the effect was greatly enhanced when the particles were suspended in a higher concentration of MnCl2. These findings indicate that the system could be viable for the separation of materials of differing size and/or diamagnetic susceptibility, and as such could be suitable for the separation and sorting of small biological species for subsequent studies.

  20. Instant transformation of learned repulsion into motivational "wanting".

    Science.gov (United States)

    Robinson, Mike J F; Berridge, Kent C

    2013-02-18

    Learned cues for pleasant reward often elicit desire, which, in addicts, may become compulsive. According to the dominant view in addiction neuroscience and reinforcement modeling, such desires are the simple products of learning, coming from a past association with reward outcome. We demonstrate that cravings are more than merely the products of accumulated pleasure memories-even a repulsive learned cue for unpleasantness can become suddenly desired via the activation of mesocorticolimbic circuitry. Rats learned repulsion toward a Pavlovian cue (a briefly-inserted metal lever) that always predicted an unpleasant Dead Sea saltiness sensation. Yet, upon first reencounter in a novel sodium-depletion state to promote mesocorticolimbic reactivity (reflected by elevated Fos activation in ventral tegmentum, nucleus accumbens, ventral pallidum, and the orbitofrontal prefrontal cortex), the learned cue was instantly transformed into an attractive and powerful motivational magnet. Rats jumped and gnawed on the suddenly attractive Pavlovian lever cue, despite never having tasted intense saltiness as anything other than disgusting. Instant desire transformation of a learned cue contradicts views that Pavlovian desires are essentially based on previously learned values (e.g., prediction error or temporal difference models). Instead desire is recomputed at reencounter by integrating Pavlovian information with the current brain/physiological state. This powerful brain transformation reverses strong learned revulsion into avid attraction. When applied to addiction, related mesocorticolimbic transformations (e.g., drugs or neural sensitization) of cues for already-pleasant drug experiences could create even more intense cravings. This cue/state transformation helps define what it means to say that addiction hijacks brain limbic circuits of natural reward. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. From repulsive to attractive glass: A rheological investigation.

    Science.gov (United States)

    Zhou, Zhi; Jia, Di; Hollingsworth, Javoris V; Cheng, He; Han, Charles C

    2015-12-21

    Linear rheological properties and yielding behavior of polystyrene core and poly (N-isopropylacrylamide) (PNIPAM) shell microgels were investigated to understand the transition from repulsive glass (RG) to attractive glass (AG) and the A3 singularity. Due to the volume phase transition of PNIPAM in aqueous solution, the microgel-microgel interaction potential gradually changes from repulsive to attractive. In temperature and frequency sweep experiments, the storage modulus (G') and loss modulus (G″) increased discontinuously when crossing the RG-to-AG transition line, while G' at low frequency exhibited a different volume fraction (Φ) dependence. By fitting the data of RG and AG, and then extrapolating to high volume fraction, the difference between RG and AG decreased and the existence of A3 singularity was verified. Dynamic strain sweep experiments were conducted to confirm these findings. RG at 25 °C exhibited one-step yielding, whereas AG at 40 °C showed a typical two-step yielding behavior; the first yielding strain remained constant and the second one gradually decreased as the volume fraction increased. By extrapolating the second yield strain to that of the first one, the predicted A3 singularity was at 0.61 ± 0.02. At 37 °C, when Φeff = 0.59, AG showed one step yielding as the length of the attractive bond increased. The consistency and agreement of the experimental results reaffirmed the existence of A3 singularity, where the yielding behavior of RG and AG became identical.

  2. Graphic Turbulence Guidance

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Forecast turbulence hazards identified by the Graphical Turbulence Guidance algorithm. The Graphical Turbulence Guidance product depicts mid-level and upper-level...

  3. Graphical Turbulence Guidance - Composite

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Forecast turbulence hazards identified by the Graphical Turbulence Guidance algorithm. The Graphical Turbulence Guidance product depicts mid-level and upper-level...

  4. Career guidance in communities

    DEFF Research Database (Denmark)

    Thomsen, Rie

    for the development of a critically reflexive career guidance practice. The considerations are organised around seven elements. 1. Creating opportunity, structure and access 2. Entering a community and increasing visibility 3. Providing guidance in communities 4. Exploring potentials in guidance situations 5...... in career guidance practices as well as in the lives of the people in the communities. This paper falls into two parts: The first part considers the collective as the starting point for the development of meaningful career guidance activities. Based on previous research on career guidance in communities......The aim of this paper is to inspire practitioners and professionals to leave their offices to bring career guidance into communities that might not identify with career guidance in the first instance. By making the effort to engage with communities, practitioners may bring about a critical change...

  5. Guidance Cue Netrin-1 and the Regulation of Inflammation in Acute and Chronic Kidney Disease

    Directory of Open Access Journals (Sweden)

    Punithavathi Ranganathan

    2014-01-01

    Full Text Available Acute kidney injury (AKI is a common problem in the hospital setting and intensive care unit. Despite improved understanding, there are no effective therapies available to treat AKI. A large body of evidence strongly suggests that ischemia reperfusion injury is an inflammatory disease mediated by both adaptive and innate immune systems. Cell migration also plays an important role in embryonic development and inflammation, and this process is highly regulated to ensure tissue homeostasis. One such paradigm exists in the developing nervous system, where neuronal migration is mediated by a balance between chemoattractive and chemorepulsive signals. The ability of the guidance molecule netrin-1 to repulse or abolish attraction of neuronal cells expressing the UNC5B receptor makes it an attractive candidate for the regulation of inflammatory cell migration. Recent identification of netrin-1 as regulators of immune cell migration has led to a large number of studies looking into how netrin-1 controls inflammation and inflammatory cell migration. This review will focus on recent advances in understanding netrin-1 mediated regulation of inflammation during acute and chronic kidney disease and whether netrin-1 and its receptor activation can be used to treat acute and chronic kidney disease.

  6. Quantum mechanics study of repulsive π-π interaction and flexibility of phenyl moiety in the iron azodioxide complex

    Science.gov (United States)

    Liu, Yuemin; Liu, Yucheng; Murru, Siva; Tzeng, Nianfeng; Srivastava, Radhey S.

    2015-10-01

    In this study, repulsive π-π interactions within iron azodioxide complex Fe[Ph(O)NN(O)Ph]3 were quantum mechanically characterized using DFT, MP2 and CCSD(T) methods. Flexibility of six phenyl moieties in this complex structure was also investigated by structural optimization approach using the DFT methods. Our MP2 and CCSD(T) calculations of the closest pair provided interaction energy of 6.62 and 8.29 kcal/mol respectively, which indicate a strongest repulsion among these intra-molecular π-π interactions. Interaction energy of the particular π-π pair calculated from 24 hybrid DFT methods ranges from 4.56 kcal/mol from BHandH method to 15.15 kcal/mol from O3LYP method. Cares should be exercised when interpreting interaction energy and geometry optimization from DFT simulation of systems containing π-π interaction. Comparison between the DFT results and the benchmark CCSD(T) results shows that the DFT calculations of π-π interaction are reasonable but still need to be interpreted with caution. Furthermore, MP2 interaction energy of -44.69 kcal/mol between two substituted π systems/phenyl rings Ph(O)N-moieties suggested that above energetically unfavorable π-π interaction can be compensated by the covalent bond N-N in a single ligand Ph(O)NN(O)Ph, which allows for a reasonable stability across the complex molecules. Optimizations of the entire complex molecule using B3LYP and M06HF methods produced a large variation of π-π distances and orientations, which implied that the complex molecule may perform catalysis at room temperature.

  7. Thermodynamics and elastic moduli of fluids with steeply repulsive potentials

    Science.gov (United States)

    Heyes, D. M.

    1997-08-01

    Analytic expressions for the thermodynamic properties and elastic moduli of molecular fluids interacting with steeply repulsive potentials are derived using Rowlinson's hard-sphere perturbation treatment which employs a softness parameter, λ specifying the deviation from the hard-sphere potential. Generic potentials of this form might be used to represent the interactions between near-hard-sphere stabilized colloids. Analytic expressions for the equivalent hard-sphere diameter of inverse power [ɛ(σ/r)n where ɛ sets the energy scale and σ the distance scale] exponential and logarithmic potential forms are derived using the Barker-Henderson formula. The internal energies in the hard-sphere limit are predicted essentially exactly by the perturbation approach when compared against molecular dynamics simulation data using the same potentials. The elastic moduli are similarly accurately predicted in the hard-sphere limit, as they are trivially related to the internal energy. The compressibility factors from the perturbation expansion do not compare as favorably with simulation data, and in this case the Carnahan-Starling equation of state prediction using the analytic effective hard-sphere diameter would appear to be a preferable route for this thermodynamic property. A more refined state point dependent definition for the effective hard-sphere diameter is probably required for this property.

  8. Pairing from dynamically screened Coulomb repulsion in bismuth

    Science.gov (United States)

    Ruhman, Jonathan; Lee, Patrick A.

    2017-12-01

    Recently, Prakash et al. have discovered bulk superconductivity in single crystals of bismuth, which is a semimetal with extremely low carrier density. At such low density, we argue that conventional electron-phonon coupling is too weak to be responsible for the binding of electrons into Cooper pairs. We study a dynamically screened Coulomb interaction with effective attraction generated on the scale of the collective plasma modes. We model the electronic states in bismuth to include three Dirac pockets with high velocity and one hole pocket with a significantly smaller velocity. We find a weak-coupling instability, which is greatly enhanced by the presence of the hole pocket. Therefore we argue that bismuth is the first material to exhibit superconductivity driven by retardation effects of Coulomb repulsion alone. By using realistic parameters for bismuth we find that the acoustic plasma mode does not play the central role in pairing. We also discuss a matrix element effect, resulting from the Dirac nature of the conduction band, which may affect Tc in the s -wave channel without breaking time-reversal symmetry.

  9. Atomic-batched tensor decomposed two-electron repulsion integrals

    Science.gov (United States)

    Schmitz, Gunnar; Madsen, Niels Kristian; Christiansen, Ove

    2017-04-01

    We present a new integral format for 4-index electron repulsion integrals, in which several strategies like the Resolution-of-the-Identity (RI) approximation and other more general tensor-decomposition techniques are combined with an atomic batching scheme. The 3-index RI integral tensor is divided into sub-tensors defined by atom pairs on which we perform an accelerated decomposition to the canonical product (CP) format. In a first step, the RI integrals are decomposed to a high-rank CP-like format by repeated singular value decompositions followed by a rank reduction, which uses a Tucker decomposition as an intermediate step to lower the prefactor of the algorithm. After decomposing the RI sub-tensors (within the Coulomb metric), they can be reassembled to the full decomposed tensor (RC approach) or the atomic batched format can be maintained (ABC approach). In the first case, the integrals are very similar to the well-known tensor hypercontraction integral format, which gained some attraction in recent years since it allows for quartic scaling implementations of MP2 and some coupled cluster methods. On the MP2 level, the RC and ABC approaches are compared concerning efficiency and storage requirements. Furthermore, the overall accuracy of this approach is assessed. Initial test calculations show a good accuracy and that it is not limited to small systems.

  10. Layers of Cold Dipolar Molecules in the Harmonic Approximation

    DEFF Research Database (Denmark)

    R. Armstrong, J.; Zinner, Nikolaj Thomas; V. Fedorov, D.

    2012-01-01

    We consider the N-body problem in a layered geometry containing cold polar molecules with dipole moments that are polarized perpendicular to the layers. A harmonic approximation is used to simplify the hamiltonian and bound state properties of the two-body inter-layer dipolar potential are used...... to adjust this effective interaction. To model the intra-layer repulsion of the polar molecules, we introduce a repulsive inter-molecule potential that can be parametrically varied. Single chains containing one molecule in each layer, as well as multi-chain structures in many layers are discussed...... and their energies and radii determined. We extract the normal modes of the various systems as measures of their volatility and eventually of instability, and compare our findings to the excitations in crystals. We find modes that can be classified as either chains vibrating in phase or as layers vibrating against...

  11. Molecule nanoweaver

    Science.gov (United States)

    Gerald, II; Rex, E [Brookfield, IL; Klingler, Robert J [Glenview, IL; Rathke, Jerome W [Homer Glen, IL; Diaz, Rocio [Chicago, IL; Vukovic, Lela [Westchester, IL

    2009-03-10

    A method, apparatus, and system for constructing uniform macroscopic films with tailored geometric assemblies of molecules on the nanometer scale. The method, apparatus, and system include providing starting molecules of selected character, applying one or more force fields to the molecules to cause them to order and condense with NMR spectra and images being used to monitor progress in creating the desired geometrical assembly and functionality of molecules that comprise the films.

  12. Meninges-derived cues control axon guidance.

    Science.gov (United States)

    Suter, Tracey A C S; DeLoughery, Zachary J; Jaworski, Alexander

    2017-10-01

    The axons of developing neurons travel long distances along stereotyped pathways under the direction of extracellular cues sensed by the axonal growth cone. Guidance cues are either secreted proteins that diffuse freely or bind the extracellular matrix, or membrane-anchored proteins. Different populations of axons express distinct sets of receptors for guidance cues, which results in differential responses to specific ligands. The full repertoire of axon guidance cues and receptors and the identity of the tissues producing these cues remain to be elucidated. The meninges are connective tissue layers enveloping the vertebrate brain and spinal cord that serve to protect the central nervous system (CNS). The meninges also instruct nervous system development by regulating the generation and migration of neural progenitors, but it has not been determined whether they help guide axons to their targets. Here, we investigate a possible role for the meninges in neuronal wiring. Using mouse neural tissue explants, we show that developing spinal cord meninges produce secreted attractive and repulsive cues that can guide multiple types of axons in vitro. We find that motor and sensory neurons, which project axons across the CNS-peripheral nervous system (PNS) boundary, are attracted by meninges. Conversely, axons of both ipsi- and contralaterally projecting dorsal spinal cord interneurons are repelled by meninges. The responses of these axonal populations to the meninges are consistent with their trajectories relative to meninges in vivo, suggesting that meningeal guidance factors contribute to nervous system wiring and control which axons are able to traverse the CNS-PNS boundary. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Design of a smart haptic system for repulsive force control under irregular manipulation environment

    International Nuclear Information System (INIS)

    Lee, Sang-Rock; Choi, Seung-Hyun; Choi, Seung-Bok; Cho, Myeong-Woo

    2014-01-01

    This paper describes how to make an operator feel the desired repulsive force in a haptic system. When an operator manipulates a haptic system, the repulsive force of the operator varies significantly, depending on many factors such as position, velocity and force. In order to reflect the desired repulsive force to the operator, it is commonly known that a haptic system must compensate for irregularly changing forces. The irregularity of the forces, however, has discouraged many researchers from establishing a clear principle on how to make the operator feel the desired repulsive force. To resolve this problem, we introduce a smart haptic framework that can reflect the desired repulsive force to the operator, regardless of the operator’s movement. A dummy governing equation technique is introduced and used to calculate the proper actuating force in real time. The actuating force is generated by a PID controller. To verify the proposed method, a mathematical proof is offered to show that the repulsive force converges to the desired repulsive force. Additionally, to demonstrate the performance of the proposed method, simulational and experimental tests are implemented. (paper)

  14. Effect of hydration repulsion on nanoparticle agglomeration evaluated via a constant number Monte–Carlo simulation

    International Nuclear Information System (INIS)

    Liu, Haoyang Haven; Lanphere, Jacob; Walker, Sharon; Cohen, Yoram

    2015-01-01

    The effect of hydration repulsion on the agglomeration of nanoparticles in aqueous suspensions was investigated via the description of agglomeration by the Smoluchowski coagulation equation using constant number Monte–Carlo simulation making use of the classical DLVO theory extended to include the hydration repulsion energy. Evaluation of experimental DLS measurements for TiO 2 , CeO 2 , SiO 2 , and α-Fe 2 O 3 (hematite) at high IS (up to 900 mM) or low |ζ-potential| (≥1.35 mV) demonstrated that hydration repulsion energy can be above electrostatic repulsion energy such that the increased overall repulsion energy can significantly lower the agglomerate diameter relative to the classical DLVO prediction. While the classical DLVO theory, which is reasonably applicable for agglomeration of NPs of high |ζ-potential| (∼>35 mV) in suspensions of low IS (∼<1 mM), it can overpredict agglomerate sizes by up to a factor of 5 at high IS or low |ζ-potential|. Given the potential important role of hydration repulsion over a range of relevant conditions, there is merit in quantifying this repulsion energy over a wide range of conditions as part of overall characterization of NP suspensions. Such information would be of relevance to improved understanding of NP agglomeration in aqueous suspensions and its correlation with NP physicochemical and solution properties. (paper)

  15. Glass transition of repulsive charged rods (fd-viruses).

    Science.gov (United States)

    Kang, Kyongok

    2014-05-14

    It has recently been shown that suspensions of long and thin charged fibrous viruses (fd) form a glass at low ionic strengths. The corresponding thick electric double layers give rise to long-ranged repulsive electrostatic interactions, which lead to caging and structural arrest at concentrations far above the isotropic-nematic coexistence region. Structural arrest and freezing of the orientational texture are found to occur at the same concentration. In addition, various types of orientational textures are equilibrated below the glass transition concentration, ranging from a chiral-nematic texture with a large pitch (of about 100 μm), an X-pattern, and a tightly packed domain texture, consisting of helical domains with a relatively small pitch (of about 10 μm) and twisted boundaries. The dynamics of both particles as well as the texture are discussed, below and above the glass transition. Dynamic light scattering correlation functions exhibit two dynamical modes, where the slow mode is attributed to the elasticity of helical domains. On approach of the glass-transition concentration, the slow mode increases in amplitude, while as the amplitudes of the fast and slow mode become equal at the glass transition. Finally, interesting features of the "transient" behaviors of charged fd-rod glass are shown as the initial caging due to structural arrest, the propagation of flow originating from stress release, and the transition to the final metastable glass state. In addition to the intensity correlation function, power spectra are presented as a function of the waiting time, at the zero-frequency limit that may access to the thermal anomalities in a charged system.

  16. Isomorphs in the phase diagram of a model liquid without inverse power law repulsion

    DEFF Research Database (Denmark)

    Veldhorst, Arnold Adriaan; Bøhling, Lasse; Dyre, J. C.

    2012-01-01

    scattering function are calculated. The results are shown to reflect a hidden scale invariance; despite its exponential repulsion the Buckingham potential is well approximated by an inverse power-law plus a linear term in the region of the first peak of the radial distribution function. As a consequence...... the dynamics of the viscous Buckingham liquid is mimicked by a corresponding model with purely repulsive inverse-power-law interactions. The results presented here closely resemble earlier results for Lennard-Jones type liquids, demonstrating that the existence of strong correlations and isomorphs does...... not depend critically on the mathematical form of the repulsion being an inverse power law....

  17. Crossover from phonon-mediated to repulsion-induced superconducting pairing with large momentum

    International Nuclear Information System (INIS)

    Belyavsky, V.I.; Kopaev, Yu.V.; Nguyen, N.T.; Togushova, Yu.N.

    2005-01-01

    There are asymmetric and symmetric solutions of the self-consistency equation which takes into account both phonon-mediated and Coulomb pairing interactions. The first of them leads to the order parameter with a nodal line and, in the case of pairing with large momentum, exists at any repulsive and attractive strengths. The second one arises if the attraction exceeds a level depending on the repulsion strength and dominates the pairing in the strong attraction limit. The competition of attraction and repulsion results in unusual isotope-effect exponent observed in the cuprates

  18. On the hydrodynamics of a solvent-saturated lipid bilayer. 1. Model of repulsion

    International Nuclear Information System (INIS)

    Bish, P.M.; Wendel, H.

    1983-01-01

    A semiphenomenological theory of steric repulsion in black lipid films is developed. The model employs the statistical mechanical formulation of the van der Waals theory of simple liquid-vapour interfaces; it is based on the picture that upon diminishing the film thickness the adjacent interfacial layers start overlapping in the film center raising the degree of orientation of the hydrocarbon segments present there. This fact causes a mutual repulsion of the two film surfaces. The general order parameter profile is found to depend on two parameters which are fixed by means of the results of an experiment which recorded the repulsive force as a function of film thickness. (Author) [pt

  19. An electrostatic elliptical mirror for neutral polar molecules.

    Science.gov (United States)

    González Flórez, A Isabel; Meek, Samuel A; Haak, Henrik; Conrad, Horst; Santambrogio, Gabriele; Meijer, Gerard

    2011-11-14

    Focusing optics for neutral molecules finds application in shaping and steering molecular beams. Here we present an electrostatic elliptical mirror for polar molecules consisting of an array of microstructured gold electrodes deposited on a glass substrate. Alternating positive and negative voltages applied to the electrodes create a repulsive potential for molecules in low-field-seeking states. The equipotential lines are parallel to the substrate surface, which is bent in an elliptical shape. The mirror is characterized by focusing a beam of metastable CO molecules and the results are compared to the outcome of trajectory simulations.

  20. Semaphorin 3G Provides a Repulsive Guidance Cue to Lymphatic Endothelial Cells via Neuropilin-2/PlexinD1.

    Science.gov (United States)

    Liu, Xinyi; Uemura, Akiyoshi; Fukushima, Yoko; Yoshida, Yutaka; Hirashima, Masanori

    2016-11-22

    The vertebrate circulatory system is composed of closely related blood and lymphatic vessels. It has been shown that lymphatic vascular patterning is regulated by blood vessels during development, but its molecular mechanisms have not been fully elucidated. Here, we show that the artery-derived ligand semaphorin 3G (Sema3G) and the endothelial cell receptor PlexinD1 play a role in lymphatic vascular patterning. In mouse embryonic back skin, genetic inactivation of Sema3G or PlexinD1 results in abnormal artery-lymph alignment and reduced lymphatic vascular branching. Conditional ablation in mice demonstrates that PlexinD1 is primarily required in lymphatic endothelial cells (LECs). In vitro analyses show that Sema3G binds to neuropilin-2 (Nrp2), which forms a receptor complex with PlexinD1. Sema3G induces cell collapse in an Nrp2/PlexinD1-dependent manner. Our findings shed light on a molecular mechanism by which LECs are distributed away from arteries and form a branching network during lymphatic vascular development. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

  1. A novel method for investigating the repulsive and attractive parts of cubic equations of state and the combining rules used with the vdW-1f theory

    DEFF Research Database (Denmark)

    Kontogeorgis, Georgios; Philippos, Coutsikos; Vassilis, Harismiadis

    1998-01-01

    A novel method for investigating the performance of the repulsive and attractive terms of a cubic equation of state (EoS) along with different combining rules for the cross covolume (b(12)) and cross-energy (a(12)) parameters used with the van der Waals one-fluid theory is presented. The method...... utilizes the EoS-derived liquid-phase activity coefficient which is separated into a combinatorial-free volume part (gamma(c-fv)), obtained from the repulsive term of the EoS, and a residual one (gamma(res)) obtained from the attractive term. Athermal systems (alkane solutions) are used where we can......(c-fv) values with the experimental ones suggest that the van der Waals (vdW) repulsive term is applicable not only to mixtures with spherical molecules, as originally suggested by van der Waals, but also to very asymmetric ones. On the other hand, the attractive term leads to gamma(res) values that can...

  2. Mean transverse momenta correlations in hadron-hadron collisions in MC toy model with repulsing strings

    International Nuclear Information System (INIS)

    Altsybeev, Igor

    2016-01-01

    In the present work, Monte-Carlo toy model with repulsing quark-gluon strings in hadron-hadron collisions is described. String repulsion creates transverse boosts for the string decay products, giving modifications of observables. As an example, long-range correlations between mean transverse momenta of particles in two observation windows are studied in MC toy simulation of the heavy-ion collisions

  3. Molecule Matters

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 14; Issue 4. Molecule Matters – van der Waals Molecules - History and Some Perspectives on Intermolecular Forces. E Arunan. Feature Article Volume 14 Issue 4 April 2009 pp 346-356 ...

  4. Optimal Aerocapture Guidance

    Data.gov (United States)

    National Aeronautics and Space Administration — The main goal of my research is to develop, implement, verify, and validate an optimal numerical predictor-corrector aerocapture guidance algorithm that is...

  5. Coral Reef Guidance

    Science.gov (United States)

    Guidance prepared by EPA and Army Corps of Engineers concerning coral reef protection under the Clean Water Act, Marine Protection, Research, and Sanctuaries Act, Rivers and Harbors Act, and Federal Project Authorities.

  6. Laser Guidance Analysis Facility

    Data.gov (United States)

    Federal Laboratory Consortium — This facility, which provides for real time, closed loop evaluation of semi-active laser guidance hardware, has and continues to be instrumental in the development...

  7. Atkins' molecules

    CERN Document Server

    Atkins, Peters

    2003-01-01

    Originally published in 2003, this is the second edition of a title that was called 'the most beautiful chemistry book ever written'. In it, we see the molecules responsible for the experiences of our everyday life - including fabrics, drugs, plastics, explosives, detergents, fragrances, tastes, and sex. With engaging prose Peter Atkins gives a non-technical account of an incredible range of aspects of the world around us, showing unexpected connections, and giving an insight into how this amazing world can be understood in terms of the atoms and molecules from which it is built. The second edition includes dozens of extra molecules, graphical presentation, and an even more accessible and enthralling account of the molecules themselves.

  8. Interstellar Molecules

    Science.gov (United States)

    Solomon, Philip M.

    1973-01-01

    Radioastronomy reveals that clouds between the stars, once believed to consist of simple atoms, contain molecules as complex as seven atoms and may be the most massive objects in our Galaxy. (Author/DF)

  9. Slow relaxation mode in concentrated oil-in-water microemulsions consisting of repulsive droplets

    Science.gov (United States)

    Hattori, Y.; Ushiki, H.; Courbin, L.; Panizza, P.

    2007-02-01

    The present contribution reports on the observation of two diffusive relaxation modes in a concentrated microemulsion made of repulsive droplets. These two modes can be interpreted in the frame of Weissman’s and Pusey’s theoretical pioneering works. The fast mode is associated to the collective diffusion of droplets whereas the slow one corresponds to the relaxation of droplet concentration fluctuations associated with composition and/or size. We show that (i) repulsive interactions considerably slow down the latter and (ii) a generalized Stokes Einstein relationship between its coefficient of diffusion and the Newtonian viscosity of the solutions, similar to the Walden’s rule for electrolytes, holds for concentrated microemulsion systems made of repulsive droplets.

  10. Mapping between Hamiltonians with attractive and repulsive potentials on a lattice

    International Nuclear Information System (INIS)

    Joglekar, Yogesh N.

    2010-01-01

    Through a simple and exact analytical derivation, we show that for a particle on a lattice there is a one-to-one correspondence between the spectrum in the presence of an attractive potential V and its repulsive counterpart -V. For a Hermitian potential, this result implies that the number of localized states is the same in both attractive and repulsive cases although these states occur above (below) the band continuum for the repulsive (attractive) case. For a PT-symmetric potential that is odd under parity, our result implies that, in the PT-unbroken phase, the energy eigenvalues are symmetric around zero and that the corresponding eigenfunctions are closely related to each other.

  11. Small traveling clusters in attractive and repulsive Hamiltonian mean-field models.

    Science.gov (United States)

    Barré, Julien; Yamaguchi, Yoshiyuki Y

    2009-03-01

    Long-lasting small traveling clusters are studied in the Hamiltonian mean-field model by comparing between attractive and repulsive interactions. Nonlinear Landau damping theory predicts that a Gaussian momentum distribution on a spatially homogeneous background permits the existence of traveling clusters in the repulsive case, as in plasma systems, but not in the attractive case. Nevertheless, extending the analysis to a two-parameter family of momentum distributions of Fermi-Dirac type, we theoretically predict the existence of traveling clusters in the attractive case; these findings are confirmed by direct N -body numerical simulations. The parameter region with the traveling clusters is much reduced in the attractive case with respect to the repulsive case.

  12. Adhesion molecules

    CERN Document Server

    Preedy, Victor R

    2016-01-01

    This book covers the structure and classification of adhesion molecules in relation to signaling pathways and gene expression. It discusses immunohistochemical localization, neutrophil migration, and junctional, functional, and inflammatory adhesion molecules in pathologies such as leukocyte decompression sickness and ischemia reperfusion injury. Highlighting the medical applications of current research, chapters cover diabetes, obesity, and metabolic syndrome; hypoxia; kidney disease; smoking, atrial fibrillation, and heart disease, the brain and dementia; and tumor proliferation. Finally, it looks at molecular imaging and bioinformatics, high-throughput technologies, and chemotherapy.

  13. Analysis on Patterns of Globally Coupled Phase Oscillators with Attractive and Repulsive Interactions

    International Nuclear Information System (INIS)

    Wang Peng-Fei; Xu Zhong-Bin; Ruan Xiao-Dong; Fu Xin

    2015-01-01

    The Hong–Strogatz (HS) model of globally coupled phase oscillators with attractive and repulsive interactions reflects the fact that each individual (oscillator) has its own attitude (attractive or repulsive) to the same environment (mean field). Previous studies on HS model focused mainly on the stable states on Ott–Antonsen (OA) manifold. In this paper, the eigenvalues of the Jacobi matrix of each fixed point in HS model are explicitly derived, with the aim to understand the local dynamics around each fixed point. Phase transitions are described according to relative population and coupling strength. Besides, the dynamics off OA manifold is studied. (paper)

  14. Scaling in soft spheres: fragility invariance on the repulsive potential softness

    International Nuclear Information System (INIS)

    Michele, Cristiano De; Sciortino, Francesco; Coniglio, Antonio

    2004-01-01

    We address the question of the dependence of the fragility of glass forming supercooled liquids on the 'softness' of an interacting potential by performing numerical simulation of a binary mixture of soft spheres with different power n of the interparticle repulsive potential. We show that the temperature dependence of the diffusion coefficients for various n collapses onto a universal curve, supporting the unexpected view that fragility is not related to the hard core repulsion. We also find that the configurational entropy correlates with the slowing down of the dynamics for all studied n. (letter to the editor)

  15. Metastability and coherence of repulsive polarons in a strongly interacting Fermi mixture

    DEFF Research Database (Denmark)

    Kohstall, Cristoph; Zaccanti, Mattheo; Jag, Matthias

    2012-01-01

    show that a well-defined quasiparticle exists for strongly repulsive interactions. We measure the energy and the lifetime of this ‘repulsive polaron’9, 12, 13, and probe its coherence properties by measuring the quasiparticle residue. The results are well described by a theoretical approach that takes...... into account the finite effective range of the interaction in our system. We find that when the effective range is of the order of the interparticle spacing, there is a substantial increase in the lifetime of the quasiparticles. The existence of such a long-lived, metastable many-body state offers intriguing...

  16. Maximum repulsed magnetization of a bulk superconductor with low pulsed field

    International Nuclear Information System (INIS)

    Tsuchimoto, M.; Kamijo, H.; Fujimoto, H.

    2005-01-01

    Pulsed field magnetization of a bulk high-T c superconductor (HTS) is important technique especially for practical applications of a bulk superconducting magnet. Full magnetization is not obtained for low pulsed field and trapped field is decreased by reversed current in the HTS. The trapped field distribution by repulsed magnetization was previously reported in experiments with temperature control. In this study, repulsed magnetization technique with the low pulsed field is numerically analyzed under assumption of variable shielding current by the temperature control. The shielding current densities are discussed to obtain maximum trapped field by two times of low pulsed field magnetizations

  17. Molecule Matters

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 16; Issue 12. Molecule Matters - Dinitrogen. A G Samuelson J Jabadurai. Volume 16 Issue 12 ... Author Affiliations. A G Samuelson1 J Jabadurai1. Department of Inroganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012, India.

  18. Molecule Matters

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 11; Issue 9. Molecule Matters - A Chromium Compound with a Quintuple Bond. K C Kumara Swamy. Feature Article Volume 11 Issue 9 September 2006 pp 72-75. Fulltext. Click here to view fulltext PDF. Permanent link:

  19. Advancing surgical guidance : from (hybrid) molecule to man and beyond

    NARCIS (Netherlands)

    Berg, van den N.S.

    2016-01-01

    The work described in this thesis shows how intraoperative lesion identification can be improved via the introduction of (hybrid) tracers and optimised (hybrid) imaging modalities capable of detecting this tracers. In part one, the reader is introduced to the concept of fluorescence image-guided

  20. Hydrogen detachment driven by a repulsive 1πσ* state - an electron localization function study of 3-amino-1,2,4-triazole.

    Science.gov (United States)

    Bil, Andrzej; Latajka, Zdzisław; Biczysko, Malgorzata

    2018-02-14

    Electron localization function analysis reveals the details of a charge induced hydrogen detachment mechanism of 3-amino-1,2,4-triazole, identified recently to be responsible for phototautomerization of the molecule. In this process vertical excitation to the 1 πσ* state is followed by the barrier-less migration of a H atom along the N-H bond toward the conical intersection with the S0 ground state. The most striking feature revealed for the 1 πσ* state is partial ejection of σ* electrons outside the molecule, even beyond the NH group, at the Franck-Condon point. Further gradual spatial localization of the electron around the proton moving along the N-H stretching coordinate gives a plausible explanation for the repulsive character of the 1 πσ* potential energy surface with the proton wading through the region of space where some negative charge is accumulated ('a virtual acceptor'), dragging some electron density. This mechanism resembles the one postulated for the hydrogen transfer from a donor molecule (D-H) to an acceptor one (A) in a class of vertically excited molecules with a preexisting inter- or intramolecular D-HA motif, even though the acceptor molecule is absent. The present analysis demonstrates also that the bond evolution and changes in the electron density along the excited state reaction path can be effectively studied with the use of an electron localization function.

  1. Threshold guidance update

    International Nuclear Information System (INIS)

    Wickham, L.E.

    1986-01-01

    The Department of Energy (DOE) is developing the concept of threshold quantities for use in determining which waste materials must be handled as radioactive waste and which may be disposed of as nonradioactive waste at its sites. Waste above this concentration level would be managed as radioactive or mixed waste (if hazardous chemicals are present); waste below this level would be handled as sanitary waste. Last years' activities (1984) included the development of a threshold guidance dose, the development of threshold concentrations corresponding to the guidance dose, the development of supporting documentation, review by a technical peer review committee, and review by the DOE community. As a result of the comments, areas have been identified for more extensive analysis, including an alternative basis for selection of the guidance dose and the development of quality assurance guidelines. Development of quality assurance guidelines will provide a reasonable basis for determining that a given waste stream qualifies as a threshold waste stream and can then be the basis for a more extensive cost-benefit analysis. The threshold guidance and supporting documentation will be revised, based on the comments received. The revised documents will be provided to DOE by early November. DOE-HQ has indicated that the revised documents will be available for review by DOE field offices and their contractors

  2. Regulatory guidance document

    International Nuclear Information System (INIS)

    1994-05-01

    The Office of Civilian Radioactive Waste Management (OCRWM) Program Management System Manual requires preparation of the OCRWM Regulatory Guidance Document (RGD) that addresses licensing, environmental compliance, and safety and health compliance. The document provides: regulatory compliance policy; guidance to OCRWM organizational elements to ensure a consistent approach when complying with regulatory requirements; strategies to achieve policy objectives; organizational responsibilities for regulatory compliance; guidance with regard to Program compliance oversight; and guidance on the contents of a project-level Regulatory Compliance Plan. The scope of the RGD includes site suitability evaluation, licensing, environmental compliance, and safety and health compliance, in accordance with the direction provided by Section 4.6.3 of the PMS Manual. Site suitability evaluation and regulatory compliance during site characterization are significant activities, particularly with regard to the YW MSA. OCRWM's evaluation of whether the Yucca Mountain site is suitable for repository development must precede its submittal of a license application to the Nuclear Regulatory Commission (NRC). Accordingly, site suitability evaluation is discussed in Chapter 4, and the general statements of policy regarding site suitability evaluation are discussed in Section 2.1. Although much of the data and analyses may initially be similar, the licensing process is discussed separately in Chapter 5. Environmental compliance is discussed in Chapter 6. Safety and Health compliance is discussed in Chapter 7

  3. PIV Logon Configuration Guidance

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Glen Alan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-03-04

    This document details the configurations and enhancements implemented to support the usage of federal Personal Identity Verification (PIV) Card for logon on unclassified networks. The guidance is a reference implementation of the configurations and enhancements deployed at the Los Alamos National Laboratory (LANL) by Network and Infrastructure Engineering – Core Services (NIE-CS).

  4. Mixed-mode reversed phase/positively charged repulsion chromatography for intact protein separation.

    Science.gov (United States)

    Ding, Ling; Guo, Zhimou; Hu, Zhuo; Liang, Xinmiao

    2017-05-10

    A mixed-mode reversed phase/positively charged repulsion stationary phase C8PN composed of octyl and amino group has been developed for separation of intact protein. Before the separation of proteins, a set of probe compounds were employed to evaluate the chromatographic properties of C8PN, demonstrating typical reversed phase/positively charged repulsion interaction on this stationary phase as estimated. Then the new C8PN stationary phase was used to separate a standard protein mixture on the reversed phase mode. Compared with a commercial C4 stationary phase, it showed different selectivity for some proteins. In order to better understand the properties of C8PN, the effect of acetonitrile content was investigated based on retention equation. Higher values of the equation parameters on C8PN demonstrated that the protein retentions were more sensitive to the change of acetonitrile content. Besides, the influences of buffer salt additives on the protein retentions were also studied. The retention factors of the proteins got larger with the increase of buffer salt concentration, which confirmed the positively charged repulsion interaction on the column. Finally, the C8PN was further applied to separate oxidized- and reduced- forms of Recombinant Human Growth Hormone. Our study indicated the advantages and application potential of mixed-mode reversed phase/positively charged repulsion stationary phase for intact protein separation. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Repulsively interacting fermions in a two-dimensional deformed trap with spin-orbit coupling

    DEFF Research Database (Denmark)

    Marchukov, O. V.; Fedorov, D. V.; Jensen, A. S.

    2015-01-01

    We investigate a two-dimensional system of fermions with two internal (spin) degrees of freedom. It is confined by a deformed harmonic trap and subject to a Zeeman field, Rashba or Dresselhaus one-body spin-orbit couplings and two-body short range repulsion. We obtain self-consistent mean-field $N...

  6. Discontinuous nature of the repulsive-to-attractive colloidal glass transition.

    Science.gov (United States)

    van de Laar, T; Higler, R; Schroën, K; Sprakel, J

    2016-03-04

    In purely repulsive colloidal systems a glass transition can be reached by increasing the particle volume fraction beyond a certain threshold. The resulting glassy state is governed by configurational cages which confine particles and restrict their motion. A colloidal glass may also be formed by inducing attractive interactions between the particles. When attraction is turned on in a repulsive colloidal glass a re-entrant solidification ensues. Initially, the repulsive glass melts as free volume in the system increases. As the attraction strength is increased further, this weakened configurational glass gives way to an attractive glass in which motion is hindered by the formation of physical bonds between neighboring particles. In this paper, we study the transition from repulsive-to-attractive glasses using three-dimensional imaging at the single-particle level. We show how the onset of cage weakening and bond formation is signalled by subtle changes in local structure. We then demonstrate the discontinuous nature of the solid-solid transition, which is marked by a critical onset at a threshold bonding energy. Finally, we highlight how the interplay between bonding and caging leads to complex and heterogeneous dynamics at the microscale.

  7. Spontaneous symmetry breaking due to the trade-off between attractive and repulsive couplings.

    Science.gov (United States)

    Sathiyadevi, K; Karthiga, S; Chandrasekar, V K; Senthilkumar, D V; Lakshmanan, M

    2017-04-01

    Spontaneous symmetry breaking is an important phenomenon observed in various fields including physics and biology. In this connection, we here show that the trade-off between attractive and repulsive couplings can induce spontaneous symmetry breaking in a homogeneous system of coupled oscillators. With a simple model of a system of two coupled Stuart-Landau oscillators, we demonstrate how the tendency of attractive coupling in inducing in-phase synchronized (IPS) oscillations and the tendency of repulsive coupling in inducing out-of-phase synchronized oscillations compete with each other and give rise to symmetry breaking oscillatory states and interesting multistabilities. Further, we provide explicit expressions for synchronized and antisynchronized oscillatory states as well as the so called oscillation death (OD) state and study their stability. If the Hopf bifurcation parameter (λ) is greater than the natural frequency (ω) of the system, the attractive coupling favors the emergence of an antisymmetric OD state via a Hopf bifurcation whereas the repulsive coupling favors the emergence of a similar state through a saddle-node bifurcation. We show that an increase in the repulsive coupling not only destabilizes the IPS state but also facilitates the reentrance of the IPS state.

  8. Regardless-of-Speed Superconducting LSM Controlled-Repulsive MAGLEV Vehicle

    Science.gov (United States)

    Yoshida, Kinjiro; Egashira, Tatsuya; Hirai, Ryuichi

    1996-01-01

    This paper proposes a new repulsive Maglev vehicle which a superconducting linear synchronous motor (LSM) can levitate and propel simultaneously, independently of the vehicle speeds. The combined levitation and propulsion control is carried out by controlling mechanical-load angle and armature-current. Dynamic simulations show successful operations with good ride-quality by using a compact control method proposed here.

  9. Equation satisfied by electron-electron mutual Coulomb repulsion energy density functional

    OpenAIRE

    Joubert, Daniel P.

    2011-01-01

    The electron-electron mutual Coulomb repulsion energy density functional satisfies an equation that links functionals and functional derivatives at N-electron and (N-1)-electron densities for densities determined from the same adiabatic scaled external potential for the N-electron system.

  10. Evidence of central repulsion potential from pionic decay of s-shell Λ-hypernuclei

    International Nuclear Information System (INIS)

    Kumagai-Fuse, I.; Okabe, S.; Akaishi, Y.

    1994-10-01

    Pionic decays of A=4 and 5 hypernuclei are discussed to obtain information about a nucleus-Λ potential. Results for the available decay widths support as a whole that the nucleus-Λ potential has central repulsion not only in A=5 but also in A=4 hypernuclei. (author)

  11. The decay of a false vacuum and the density of states in a random, repulsive potential

    International Nuclear Information System (INIS)

    Neuberger, H.

    1982-01-01

    The replica method is applied to a disordered system built out of randomly distributed, purely repulsive scattering centers. The emerging field theoretical model has a classical solution, a bounce, which gives both the leading form of the level density and the typical ground-state wave function. (orig.)

  12. Role of electrostatic repulsion on colloidal stability of Bacillus halmapalus alpha-amylase

    DEFF Research Database (Denmark)

    Olsen, Søren Nymand; Andersen, Kim Bruno; Randolf, Theodor

    2009-01-01

    Bacillus halmapalus α-amylase (BHA) as a model protein. Repulsive forces between partly unfolded monomers were shown to strongly affect aggregation. Adding salt, increasing valence of counter ions or decreasing pH in the direction of pI resulted in a shift in the rate-limiting step from association...

  13. Bosons system with finite repulsive interaction: self-consistent field method

    International Nuclear Information System (INIS)

    Renatino, M.M.B.

    1983-01-01

    Some static properties of a boson system (T = zero degree Kelvin), under the action of a repulsive potential are studied. For the repulsive potential, a model was adopted consisting of a region where it is constant (r c ), and a decay as 1/r (r > r c ). The self-consistent field approximation used takes into account short range correlations through a local field corrections, which leads to an effective field. The static structure factor S(q-vector) and the effective potential ψ(q-vector) are obtained through a self-consistent calculation. The pair-correlation function g(r-vector) and the energy of the collective excitations E(q-vector) are also obtained, from the structure factor. The density of the system and the parameters of the repulsive potential, that is, its height and the size of the constant region were used as variables for the problem. The results obtained for S(q-vector), g(r-vector) and E(q-vector) for a fixed ratio r o /r c and a variable λ, indicates the raising of a system structure, which is more noticeable when the potential became more repulsive. (author)

  14. Emergence of amplitude death scenario in a network of oscillators under repulsive delay interaction

    International Nuclear Information System (INIS)

    Bera, Bidesh K.; Hens, Chittaranjan; Ghosh, Dibakar

    2016-01-01

    Highlights: • Amplitude death is observed using repulsive mean coupling. • Analytical conditions for amplitude death are derived. • Effect of asymmetry time delay coupling for death is discussed. - Abstract: We report the existence of amplitude death in a network of identical oscillators under repulsive mean coupling. Amplitude death appears in a globally coupled network of identical oscillators with instantaneous repulsive mean coupling only when the number of oscillators is more than two. We further investigate that, amplitude death may emerge even in two coupled oscillators as well as network of oscillators if we introduce delay time in the repulsive mean coupling. We have analytically derived the region of amplitude death island and find out how strength of delay controls the death regime in two coupled or a large network of coupled oscillators. We have verified our results on network of delayed Mackey–Glass systems where parameters are set in hyperchaotic regime. We have also tested our coupling approach in two paradigmatic limit cycle oscillators: Stuart–Landau and Van der Pol oscillators.

  15. The role of local repulsion in superconductivity in the Hubbard-Holstein model

    Science.gov (United States)

    Lin, Chungwei; Wang, Bingnan; Teo, Koon Hoo

    2017-01-01

    We examine the superconducting solution in the Hubbard-Holstein model using Dynamical Mean Field Theory. The Holstein term introduces the site-independent Boson fields coupling to local electron density, and has two competing influences on superconductivity: The Boson field mediates the effective electron-electron attraction, which is essential for the S-wave electron pairing; the same coupling to the Boson fields also induces the polaron effect, which makes the system less metallic and thus suppresses superconductivity. The Hubbard term introduces an energy penalty U when two electrons occupy the same site, which is expected to suppress superconductivity. By solving the Hubbard-Holstein model using Dynamical Mean Field theory, we find that the Hubbard U can be beneficial to superconductivity under some circumstances. In particular, we demonstrate that when the Boson energy Ω is small, a weak local repulsion actually stabilizesthe S-wave superconducting state. This behavior can be understood as an interplay between superconductivity, the polaron effect, and the on-site repulsion: As the polaron effect is strong and suppresses superconductivity in the small Ω regime, the weak on-site repulsion reduces the polaron effect and effectively enhances superconductivity. Our calculation elucidates the role of local repulsion in the conventional S-wave superconductors.

  16. Emergence of amplitude death scenario in a network of oscillators under repulsive delay interaction

    Energy Technology Data Exchange (ETDEWEB)

    Bera, Bidesh K., E-mail: bideshbera18@gmail.com [Physics and Applied Mathematics Unit, Indian Statistical Institute, Kolkata 700108 (India); Hens, Chittaranjan, E-mail: chittaranjanhens@gmail.com [Department of Mathematics, Bar-Ilan University, Ramat Gan 52900 (Israel); Ghosh, Dibakar, E-mail: dibakar@isical.ac.in [Physics and Applied Mathematics Unit, Indian Statistical Institute, Kolkata 700108 (India)

    2016-07-15

    Highlights: • Amplitude death is observed using repulsive mean coupling. • Analytical conditions for amplitude death are derived. • Effect of asymmetry time delay coupling for death is discussed. - Abstract: We report the existence of amplitude death in a network of identical oscillators under repulsive mean coupling. Amplitude death appears in a globally coupled network of identical oscillators with instantaneous repulsive mean coupling only when the number of oscillators is more than two. We further investigate that, amplitude death may emerge even in two coupled oscillators as well as network of oscillators if we introduce delay time in the repulsive mean coupling. We have analytically derived the region of amplitude death island and find out how strength of delay controls the death regime in two coupled or a large network of coupled oscillators. We have verified our results on network of delayed Mackey–Glass systems where parameters are set in hyperchaotic regime. We have also tested our coupling approach in two paradigmatic limit cycle oscillators: Stuart–Landau and Van der Pol oscillators.

  17. Trapping a Knot into Tight Conformations by Intra-Chain Repulsions

    Directory of Open Access Journals (Sweden)

    Liang Dai

    2017-02-01

    Full Text Available Knots can occur in biopolymers such as DNA and peptides. In our previous study, we systematically investigated the effects of intra-chain interactions on knots and found that long-range repulsions can surprisingly tighten knots. Here, we use this knowledge to trap a knot into tight conformations in Langevin dynamics simulations. By trapping, we mean that the free energy landscape with respect to the knot size exhibits a potential well around a small knot size in the presence of long-range repulsions, and this potential can well lead to long-lived tight knots when its depth is comparable to or larger than thermal energy. We tune the strength of intra-chain repulsion such that a knot is weakly trapped. Driven by thermal fluctuations, the knot can escape from the trap and is then re-trapped. We find that the knot switches between tight and loose conformations—referred to as “knot breathing”. We use a Yukawa potential to model screened electrostatic interactions to explore the relevance of knot trapping and breathing in charged biopolymers. We determine the minimal screened length and the minimal strength of repulsion for knot trapping. We find that Coulomb-induced knot trapping is possible to occur in single-stranded DNA and peptides for normal ionic strengths.

  18. Absence of level-repulsion in a two-state Hamiltonian

    International Nuclear Information System (INIS)

    Ahmed, Zafar

    2007-01-01

    But for the inclusion of scattering states, we point out that the two-state method (the so called perturbation method of nearly degenerate levels) for a perturbed two-state Hamiltonian is exact , yet the prediction of the level-repulsion by this method could be contradicted by the exact quantal eigenvalues. (author)

  19. The role of local repulsion in superconductivity in the Hubbard–Holstein model

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chungwei, E-mail: clin@merl.com; Wang, Bingnan; Teo, Koon Hoo

    2017-01-15

    Highlights: • There exists an optimal Boson energy for superconductivity in Hubbard–Holstein model. • The electron-Boson coupling is essential for superconductivity, but the same coupling can lead to polaron insulator, which is against superconductivity. • The local Coulomb repulsion can sometimes enhance superconductivity. - Abstract: We examine the superconducting solution in the Hubbard–Holstein model using Dynamical Mean Field Theory. The Holstein term introduces the site-independent Boson fields coupling to local electron density, and has two competing influences on superconductivity: The Boson field mediates the effective electron-electron attraction, which is essential for the S-wave electron pairing; the same coupling to the Boson fields also induces the polaron effect, which makes the system less metallic and thus suppresses superconductivity. The Hubbard term introduces an energy penalty U when two electrons occupy the same site, which is expected to suppress superconductivity. By solving the Hubbard–Holstein model using Dynamical Mean Field theory, we find that the Hubbard U can be beneficial to superconductivity under some circumstances. In particular, we demonstrate that when the Boson energy Ω is small, a weak local repulsion actually stabilizes the S-wave superconducting state. This behavior can be understood as an interplay between superconductivity, the polaron effect, and the on-site repulsion: As the polaron effect is strong and suppresses superconductivity in the small Ω regime, the weak on-site repulsion reduces the polaron effect and effectively enhances superconductivity. Our calculation elucidates the role of local repulsion in the conventional S-wave superconductors.

  20. Laser-induced breakdown spectra of Zn2 molecule in the violet region

    Indian Academy of Sciences (India)

    The study of excimer and van der Waals molecules such as Hg2, Cd2 and Zn2 are of current interest as they are potential candidates for the possible development of new high power excimer lasers. Group IIB metal dimers (Hg2, Cd2 and Zn2) have essentially repulsive ground states with very shallow van der Walls minima.

  1. Comparative molecular simulation study of low and high density polymer glasses: A competition between attractive and repulsive interactions

    Science.gov (United States)

    Singh, Jalim; Jose, Prasanth

    Results of molecular dynamics simulations of a system of Kremer and Grest linear polymer melts are presented at moderate and high number density. A detailed study of molecular pair distribution function shows that potential of mean force between the molecules has form of Gaussian with an attractive tail at number density ρ = 0.85 (in Lennard-Jones units), which is due to the dominating attractive interactions from temperature T = 0.7. This system shows gelation assisted glass transition, which is interpreted from peaks of molecular structure factor at small wave-numbers. At low temperature, this system phase separate to form dense domains whose local density is high; these domains show many dynamical features of glass transition in monomer and molecular level of relaxation indicating glass transition is assisted by gelation in this system. In the same system, at ρ = 1.0, repulsive interactions dominate, structure does not change even at low temperatures; the system exhibits dynamic heterogeneity and known to undergo glass transition. In this work, we compare and contrast the structure and dynamics of the system near its glass transition. Also, we computed correlation length of systems from the peak value of four-point structural dynamic susceptibility. HPC facility at IIT Mandi.

  2. Environmental guidance regulatory bulletin

    International Nuclear Information System (INIS)

    1997-01-01

    This document describes the background on expanding public participation in the Resource Conservation and Recovery Act and DOE's response. The bulletin also describes the changes made by the final rule to existing regulations, guidance provided by EPA in the preamble and in the revised RCRA Public Participation Manual, the relationship between public participation and environmental justice, and DOE's recent public participation and environmental justice initiatives

  3. Precise Somatotopic Thalamocortical Axon Guidance Depends on LPA-Mediated PRG-2/Radixin Signaling

    DEFF Research Database (Denmark)

    Cheng, Jin; Sahani, Sadhna; Hausrat, Torben Johann

    2016-01-01

    Precise connection of thalamic barreloids with their corresponding cortical barrels is critical for processing of vibrissal sensory information. Here, we show that PRG-2, a phospholipid-interacting molecule, is important for thalamocortical axon guidance. Developing thalamocortical fibers both...

  4. Repulsive wall potentials for He-(Ne,Ar,Kr,Xe) as inferred from differential cross sections

    International Nuclear Information System (INIS)

    Nitz, D.E.; Larson, J.; Swanson, K.; Wildgoose, C.

    1993-01-01

    We have obtained representations of the He-(Ne,Ar,Kr,Xe) ground state repulsive walls using model potentials optimized to fit published absolute differential cross section data for 500 and 1500 eV collisions. The HeNe potential, like the He 2 potentials can be fit using the semi-empirical HFD-B form constrained to cross zero at the proper internuclear separation. For the heavier atoms, this approach is unsuccessful and superior fits are obtained using only the purely repulsive V(r) - A EXP [-αr - βr 2 ] term of the HFD-B potential. Comparison of fitted potentials with previous results will be presented

  5. Analysis on Patterns of Globally Coupled Phase Oscillators with Attractive and Repulsive Interactions

    Science.gov (United States)

    Wang, Peng-Fei; Ruan, Xiao-Dong; Xu, Zhong-Bin; Fu, Xin

    2015-11-01

    The Hong-Strogatz (HS) model of globally coupled phase oscillators with attractive and repulsive interactions reflects the fact that each individual (oscillator) has its own attitude (attractive or repulsive) to the same environment (mean field). Previous studies on HS model focused mainly on the stable states on Ott-Antonsen (OA) manifold. In this paper, the eigenvalues of the Jacobi matrix of each fixed point in HS model are explicitly derived, with the aim to understand the local dynamics around each fixed point. Phase transitions are described according to relative population and coupling strength. Besides, the dynamics off OA manifold is studied. Supported by the National Basic Research Program of China under Grant No. 2015CB057301, the Applied Research Project of Public Welfare Technology of Zhejiang Province under Grant No. 201SC31109 and China Postdoctoral Science Foundation under Grant No. 2014M560483

  6. Stability of a fully magnetized ferromagnetic state in repulsively interacting ultracold Fermi gases

    International Nuclear Information System (INIS)

    Cui Xiaoling; Zhai Hui

    2010-01-01

    We construct a variational wave function to study whether a fully polarized Fermi sea of ultracold atoms is energetically stable against a single spin flip. Our variational wave function contains short-range correlations at least to the same level as Gutzwiller's projected wave function. For the Hubbard lattice model and the continuum model with pure repulsive interaction, we show that a fully polarized Fermi sea is generally unstable even for infinite repulsive strength. By contrast, for a resonance model, the ferromagnetic state is possible if the s-wave scattering length is positive and sufficiently large and the system is prepared to be orthogonal to the molecular bound state. However, we cannot rule out the possibility that more exotic correlations can destabilize the ferromagnetic state.

  7. Even-parity spin-triplet pairing by purely repulsive interactions for orbitally degenerate correlated fermions

    International Nuclear Information System (INIS)

    Zegrodnik, M; Bünemann, J; Spałek, J

    2014-01-01

    We demonstrate the stability of the spin-triplet paired s-wave (with an admixture of extended s-wave) state for the limit of purely repulsive interactions in a degenerate two-band Hubbard model of correlated fermions. The repulsive interactions limit represents an essential extension of our previous analysis (2013 New J. Phys. 15 073050), regarded here as I. We also show that near the half-filling the considered type of superconductivity can coexist with antiferromagnetism. The calculations have been carried out with the use of the so-called statistically consistent Gutzwiller approximation (SGA) for the case of a square lattice. We suggest that the electron correlations in conjunction with the Hund's rule exchange play the crucial role in stabilizing the real-space spin-triplet superconducting state. A sizable hybridization of the bands suppresses the homogeneous paired state. (paper)

  8. Role of repulsive interactions in the interplay with missing strange resonances

    Directory of Open Access Journals (Sweden)

    Alba Paolo

    2018-01-01

    Full Text Available The standard implementation of the HRG model has been shown to be unable to describe all the available data on QCD matter. Here we show the balance of repulsive and attractive hadronic interactions on QCD thermodynamics through observables both calculated by lattice simulations and measured in experiment. Attractive interactions are mediated by resonance formation, which are here implemented through extra states predicted by the Quark Model, while repulsive interactions are modelled by means of Excluded Volume (EV effects. Informations on flavour dependent effective sizes are extracted. It is found that EV effects are present in lattice QCD thermodynamics, and are essential for a comprehensive description of higher order fluctuations of conserved charges.

  9. Molecule Matters van der Waals Molecules

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 14; Issue 12. Molecule Matters van der Waals Molecules - Noble Gas Clusters are London Molecules! E Arunan. Feature Article Volume 14 Issue 12 December 2009 pp 1210-1222 ...

  10. The effects of attractive vs. repulsive instructional cuing on balance performance.

    Science.gov (United States)

    Kinnaird, Catherine; Lee, Jaehong; Carender, Wendy J; Kabeto, Mohammed; Martin, Bernard; Sienko, Kathleen H

    2016-03-16

    Torso-based vibrotactile feedback has been shown to improve postural performance during quiet and perturbed stance in healthy young and older adults and individuals with balance impairments. These systems typically include tactors distributed around the torso that are activated when body motion exceeds a predefined threshold. Users are instructed to "move away from the vibration". However, recent studies have shown that in the absence of instructions, vibrotactile stimulation induces small (~1°) non-volitional responses in the direction of its application location. It was hypothesized that an attractive cuing strategy (i.e., "move toward the vibration") could improve postural performance by leveraging this natural tendency. Eight healthy older adults participated in two non-consecutive days of computerized dynamic posturography testing while wearing a vibrotactile feedback system comprised of an inertial measurement unit and four tactors that were activated in pairs when body motion exceeded 1° anteriorly or posteriorly. A crossover design was used. On each day participants performed 24 repetitions of Sensory Organization Test condition 5 (SOT5), three repetitions each of SOT 1-6, three repetitions of the Motor Control Test, and five repetitions of the Adaptation Test. Performance metrics included A/P RMS, Time-in-zone and 95 % CI Ellipse. Performance improved with both cuing strategies but participants performed better when using repulsive cues. However, the rate of improvement was greater for attractive versus repulsive cuing. The results suggest that when the cutaneous signal is interpreted as an alarm, cognition overrides sensory information. Furthermore, although repulsive cues resulted in better performance, attractive cues may be as good, if not better, than repulsive cues following extended training.

  11. Quantum Statistics: Is there an effective fermion repulsion or boson attraction?

    OpenAIRE

    Mullin, W. J.; Blaylock, G.

    2003-01-01

    Physicists often claim that there is an effective repulsion between fermions, implied by the Pauli principle, and a corresponding effective attraction between bosons. We examine the origins of such exchange force ideas, the validity for them, and the areas where they are highly misleading. We propose that future explanations of quantum statistics should avoid the idea of a effective force completely and replace it with more appropriate physical insights, some of which are suggested here.

  12. Overscreening-underscreening transition in the two-channel Kondo model induced by electron-electron repulsion

    International Nuclear Information System (INIS)

    Zhang Yumei; Chen Hong.

    1995-09-01

    The effects of the repulsion between the electrons on the two-channel Kondo problem are studied by use of the bosonization technique. Following Emery and Kivelson, we define a special case in the spin density wave sector, in which the impurity spin is actually detached from the dynamics of the electrons. The model is thus mapped to a local Sine-Gordon system. For weak repulsion, the basic features of the overscreening picture are maintained. However, at sufficient strong repulsion the system is driven into the weak coupling regime, hence an overscreening-underscreening transition emerges. (author). 22 refs

  13. Stabilization of thin liquid films by repulsive van der waals force

    KAUST Repository

    Li, Erqiang

    2014-05-13

    Using high-speed video recording of bubble rise experiments, we study the stability of thin liquid films trapped between a rising bubble and a surfactant-free liquid-liquid meniscus interface. Using different combinations of nonpolar oils and water that are all immiscible, we investigate the extent to which film stability can be predicted by attractive and repulsive van der Waals (vdW) interactions that are indicated by the relative magnitude of the refractive indices of the liquid combinations, for example, water (refractive index, n = 1.33), perfluorohexane (n = 1.23), and tetradecane (n = 1.43). We show that, when the film-forming phase was oil (perfluorohexane or tetradecane), the stability of the film could always be predicted from the sign of the vdW interaction, with a repulsive vdW force resulting in a stable film and an attractive vdW force resulting in film rupture. However, if aqueous electrolyte is the film-forming bulk phase between the rising air bubble and the upper oil phase, the film always ruptured, even when a repulsive vdW interaction was predicted. We interpret these results as supporting the hypothesis that a short-ranged hydrophobic attraction determines the stability of the thin water film formed between an air phase and a nonpolar oil phase. © 2014 American Chemical Society.

  14. Phaco-efficiency test and re-aspiration analysis of repulsed particle in phacoemulsification.

    Science.gov (United States)

    Kim, Jae-hyung; Ko, Dong-Ah; Kim, Jae Yong; Kim, Myoung Joon; Tchah, Hungwon

    2013-04-01

    To measure the efficiency of phacoemulsification, we have developed a new experimental model for testing phaco-efficiency and analyzed re-aspiration of repulsed particles. Using a Kitaro wetlab system, a piece of blood agar (BA) was placed in an artificial chamber and the phacoemulsifier was placed horizontally. The settings of the phacoemulsifier (Infiniti, Alcon Laboratories) were 26 cc/min for aspiration, 350 cc/min for vacuum, and 95 cm of bottle height. The time to remove BAs was measured using Ozil 100 %, Ozil 40 %, and longitudinal 40 % of phaco power. The angle between the re-aspirated BA particles and the axis of the phacoemulsifier (re-aspiration zone, degree) was analyzed. The average time (seconds) to remove BAs was lower in the Ozil 100 % and the Ozil 40 % mode than in the longitudinal mode (0.37 ± 0.39, 0.85 ± 0.57, and 2.22 ± 1.40 respectively, P value < 0.01). Repulsion exceeding 1 mm occurred more frequently in the longitudinal mode than in the Ozil 100 % mode (100 % vs 40 %, P value = 0.01, Fisher's exact test). The average of re-aspiration zone was 25.9 ± 14.5 in the longitudinal 40 % and 54.0 ± 23.0 in the Ozil 40 % (P value = 0.016). The Ozil mode was more efficient than the longitudinal mode. In addition, the Ozil mode provided less repulsion and wider aspiration zone.

  15. Distinct collective states due to trade-off between attractive and repulsive couplings

    Science.gov (United States)

    Sathiyadevi, K.; Chandrasekar, V. K.; Senthilkumar, D. V.; Lakshmanan, M.

    2018-03-01

    We investigate the effect of repulsive coupling together with an attractive coupling in a network of nonlocally coupled oscillators. To understand the complex interaction between these two couplings we introduce a control parameter in the repulsive coupling which plays a crucial role in inducing distinct complex collective patterns. In particular, we show the emergence of various cluster chimera death states through a dynamically distinct transition route, namely the oscillatory cluster state and coherent oscillation death state as a function of the repulsive coupling in the presence of the attractive coupling. In the oscillatory cluster state, the oscillators in the network are grouped into two distinct dynamical states of homogeneous and inhomogeneous oscillatory states. Further, the network of coupled oscillators follow the same transition route in the entire coupling range. Depending upon distinct coupling ranges, the system displays different number of clusters in the death state and oscillatory state. We also observe that the number of coherent domains in the oscillatory cluster state exponentially decreases with increase in coupling range and obeys a power-law decay. Additionally, we show analytical stability for observed solitary state, synchronized state, and incoherent oscillation death state.

  16. Synchronous bursts on scale-free neuronal networks with attractive and repulsive coupling.

    Directory of Open Access Journals (Sweden)

    Qingyun Wang

    Full Text Available This paper investigates the dependence of synchronization transitions of bursting oscillations on the information transmission delay over scale-free neuronal networks with attractive and repulsive coupling. It is shown that for both types of coupling, the delay always plays a subtle role in either promoting or impairing synchronization. In particular, depending on the inherent oscillation period of individual neurons, regions of irregular and regular propagating excitatory fronts appear intermittently as the delay increases. These delay-induced synchronization transitions are manifested as well-expressed minima in the measure for spatiotemporal synchrony. For attractive coupling, the minima appear at every integer multiple of the average oscillation period, while for the repulsive coupling, they appear at every odd multiple of the half of the average oscillation period. The obtained results are robust to the variations of the dynamics of individual neurons, the system size, and the neuronal firing type. Hence, they can be used to characterize attractively or repulsively coupled scale-free neuronal networks with delays.

  17. PSD Increment Consumption Guidance

    Science.gov (United States)

    This document may be of assistance in applying the New Source Review (NSR) air permitting regulations including the Prevention of Significant Deterioration (PSD) requirements. This document is part of the NSR Policy and Guidance Database. Some documents in the database are a scanned or retyped version of a paper photocopy of the original. Although we have taken considerable effort to quality assure the documents, some may contain typographical errors. Contact the office that issued the document if you need a copy of the original.

  18. Energy distribution in dissociations of polyatomic molecules

    International Nuclear Information System (INIS)

    Koernig, S.A.

    1989-01-01

    In this thesis studies are reported of fragmentation processes in polyatomic molecules. In order to find out which dessocaciation reactions take place, how they are brought about by the internal energy of the reactant, and to investigate the structure of the dissociating 'transition state', the fragment mass and the corresponding kinetic energy release (KER) are determined by differential translational spectroscopy using a position and time sensitive two-particle coincidence detector. The results are interpreted using the statistical theory of unimolecular dissociation. It turns out that the standard assumptions of the theory, especially in calculating KER-distributions, are not realistic in all molecules considered. Dissociation is induced by the neutralization with alkali metal vapour. In ch. 2 the experimental method and the analysis of the data (dissociation pathways, branching ratios and ε-d-distributions) are introduced and exemplified by measurements of cyclohexane, which represents the upper limit in precursor and fragment mass accessible in the apparatus. In ch. 3 a study is reported of the molecules methylchloride (CH 3 Cl) and the acetylradical (CH 3 CO). In spite of their similar geometric structures, completely different dissociation mechanisms have been found. Methylchloride dissociates via a repulsive state; acetyl radicals show energy scrambling. The energy distribution from dissociating acetyl exemplifies dynamical effects in the dissociation. In ch. 4 an investigation of a number of prototype hydrocarbons is presented. The dissociation pathways of several small linear alkanes indicate that neutralization takes place to unknown repulsive potentials, of which the position and steepness are determined from the kinetic energy release. (author). 118 refs.; 40 figs.; 5 tabs

  19. Study on a kind of ϕ-Laplacian Liénard equation with attractive and repulsive singularities.

    Science.gov (United States)

    Xin, Yun; Cheng, Zhibo

    2017-01-01

    In this paper, by application of the Manasevich-Mawhin continuation theorem, we investigate the existence of a positive periodic solution for a kind of ϕ -Laplacian singular Liénard equation with attractive and repulsive singularities.

  20. Non-cable vehicle guidance

    Energy Technology Data Exchange (ETDEWEB)

    Daugela, G.C.; Willott, A.M.; Chopiuk, R.G.; Thornton, S.E.

    1988-06-01

    The purpose is to determine the most promising driverless mine vehicle guidance systems that are not dependent on buried cables, and to plan their development. The project is presented in two phases: a preliminary study and literature review to determine whether suitable technologies exist to justify further work; and an in-depth assessment and selection of technologies for vehicle guidance. A large number of guidance elements are involved in a completely automated vehicle. The technologies that hold the best potential for development of guidance systems for mine vehicles are ultrasonics, radar, lasers, dead reckoning, and guidance algorithms. The best approach to adaptation of these technologies is on a step by step basis. Guidance modules that are complete in themselves and are designed to be integrated with other modules can provide short term benefits. Two modules are selected for development: the dragline operations monitor and automated machine control for optimized mining (AMCOM). 99 refs., 20 figs., 40 tabs.

  1. Measuring the effects of Coulomb repulsion via signal decay in an atmospheric pressure laser ionization ion mobility spectrometer.

    Science.gov (United States)

    Ihlenborg, Marvin; Schuster, Ann-Kathrin; Grotemeyer, Juergen; Gunzer, Frank

    2018-01-01

    Using lasers in ion mobility spectrometry offers a lot of advantages compared to standard ionization sources. Especially, the ion yield can be drastically increased. It can, however, reach levels where the Coulomb repulsion leads to unwanted side effects. Here, we investigate how the Coulomb repulsion can be detected apart from the typical signal broadening by measuring effects created already in the reaction region and comparing them with corresponding finite element method simulations.

  2. Self-accelerated Universe Induced by Repulsive Effects as an Alternative to Dark Energy and Modified Gravities

    Science.gov (United States)

    Luongo, Orlando; Quevedo, Hernando

    2018-01-01

    The existence of current-time universe's acceleration is usually modeled by means of two main strategies. The first makes use of a dark energy barotropic fluid entering by hand the energy-momentum tensor of Einstein's theory. The second lies on extending the Hilbert-Einstein action giving rise to the class of extended theories of gravity. In this work, we propose a third approach, derived as an intrinsic geometrical effect of space-time, which provides repulsive regions under certain circumstances. We demonstrate that the effects of repulsive gravity naturally emerge in the field of a homogeneous and isotropic universe. To this end, we use an invariant definition of repulsive gravity based upon the behavior of the curvature eigenvalues. Moreover, we show that repulsive gravity counterbalances the standard gravitational attraction influencing both late and early times of the universe evolution. This phenomenon leads to the present speed up and to the fast expansion due to the inflationary epoch. In so doing, we are able to unify both dark energy and inflation in a single scheme, showing that the universe changes its dynamics when {\\ddot{H}\\over H}=-2 \\dot{H}, at the repulsion onset time where this condition is satisfied. Further, we argue that the spatial scalar curvature can be taken as vanishing because it does not affect at all the emergence of repulsive gravity. We check the goodness of our approach through two cosmological fits involving the most recent union 2.1 supernova compilation.

  3. Two-component fluid membranes near repulsive walls: Linearized hydrodynamics of equilibrium and nonequilibrium states.

    Science.gov (United States)

    Sankararaman, Sumithra; Menon, Gautam I; Sunil Kumar, P B

    2002-09-01

    We study the linearized hydrodynamics of a two-component fluid membrane near a repulsive wall, using a model that incorporates curvature-concentration coupling as well as hydrodynamic interactions. This model is a simplified version of a recently proposed one [J.-B. Manneville et al., Phys. Rev. E 64, 021908 (2001)] for nonequilibrium force centers embedded in fluid membranes, such as light-activated bacteriorhodopsin pumps incorporated in phospholipid egg phosphatidyl choline (EPC) bilayers. The pump-membrane system is modeled as an impermeable, two-component bilayer fluid membrane in the presence of an ambient solvent, in which one component, representing active pumps, is described in terms of force dipoles displaced with respect to the bilayer midpoint. We first discuss the case in which such pumps are rendered inactive, computing the mode structure in the bulk as well as the modification of hydrodynamic properties by the presence of a nearby wall. These results should apply, more generally, to equilibrium fluid membranes comprised of two components, in which the effects of curvature-concentration coupling are significant, above the threshold for phase separation. We then discuss the fluctuations and mode structure in the steady state of active two-component membranes near a repulsive wall. We find that proximity to the wall smoothens membrane height fluctuations in the stable regime, resulting in a logarithmic scaling of the roughness even for initially tensionless membranes. This explicitly nonequilibrium result is a consequence of the incorporation of curvature-concentration coupling in our hydrodynamic treatment. This result also indicates that earlier scaling arguments which obtained an increase in the roughness of active membranes near repulsive walls upon neglecting the role played by such couplings may need to be reevaluated.

  4. Repulsion analysis of permanent magnets for the Hoop energy storage system

    International Nuclear Information System (INIS)

    O, B. H.; Cho, S. B.; Kim, D. I.

    1996-01-01

    The repulsion force of permanent magnets is studied in order to analyze the instability problem of the rotational motion of a hoop levitated by permanent magnets in the Hoop Energy Storage System (HESS). The hoop of permanent magnets is levitated to remove the mechanical complexities caused by the rotational axis. It is important to maintain stable rotational motion at any speed for the efficiency as well as the safety of the system. To set up the equations of motion, the force of levitation and the source of perturbation are represented in terms of real parameters of the permanent magnets. The instability conditions and various geometric effects of the permanent magnets are analyzed. (author)

  5. Energy-level repulsion by spin-orbit coupling in two-dimensional Rydberg excitons

    Science.gov (United States)

    Stephanovich, V. A.; Sherman, E. Ya.; Zinner, N. T.; Marchukov, O. V.

    2018-05-01

    We study the effects of Rashba spin-orbit coupling on two-dimensional Rydberg exciton systems. Using analytical and numerical arguments we demonstrate that this coupling considerably modifies the wave functions and leads to a level repulsion that results in a deviation from the Poissonian statistics of the adjacent level distance distribution. This signifies the crossover to nonintegrability of the system and hints at the possibility of quantum chaos emerging. Such behavior strongly differs from the classical realization, where spin-orbit coupling produces highly entangled, chaotic electron trajectories in an exciton. We also calculate the oscillator strengths and show that randomization appears in the transitions between states with different total momenta.

  6. Synchronisation Induced by Repulsive Interactions in a System of van der Pol Oscillators

    Science.gov (United States)

    Martins, T. V.; Toral, R.

    2011-09-01

    We consider a system of identical van der Pol oscillators, globally coupled through their velocities, and study how the presence of competitive interactions affects its synchronisation properties. We will address the question from two points of view. Firstly, we will investigate the role of competitive interactions on the synchronisation among identical oscillators. Then, we will show that the presence of a fraction of repulsive links results in the appearance of macroscopic oscillations at that signal's rhythm, in regions where the individual oscillator is unable to synchronise with a weak external signal.

  7. Control of charged droplets using electrohydrodynamic repulsion for circular droplet patterning

    International Nuclear Information System (INIS)

    Kim, Bumjoo; Sung, Jungwoo; Lim, Geunbae; Nam, Hyoryung; Kim, Sung Jae; Joo, Sang W

    2011-01-01

    We report a novel method to form a circular pattern of monodisperse microdroplets using an electrohydrodynamic repulsion (EDR) mechanism. EDR is a phenomenon of electrostatical bounced microdroplets from an accumulated droplet on a bottom substrate. In addition to a regular EDR system, by placing a ring electrode between the capillary and ground substrate, two separate regions were created. A parameter study of two regions was carried out for droplet formation and falling velocity to control the radius of the generated droplets and the circular patterns independently. Based on energy conservation theory, our experimental results showed that the free-falling region exerted crucial influences on the sizes of the circular patterns

  8. Observation of attractive and repulsive polarons in a Bose-Einstein condensate

    DEFF Research Database (Denmark)

    Jørgensen, Nils Byg

    2016-01-01

    (BEC) has not yet been realized. Here, we use radio frequency spectroscopy of ultracold bosonic 39K atoms to experimentally demonstrate the existence of a well-defined quasiparticle state of an impurity interacting with a BEC. We measure the energy of the impurity both for attractive and repulsive...... interactions, and find excellent agreement with theories that incorporate three-body correlations. The spectral response consists of a well-defined quasiparticle peak at weak coupling, while for increasing interaction strength, the spectrum is strongly broadened and becomes dominated by the many-body continuum...

  9. Repulsive atomic gas in a harmonic trap on the border of itinerant ferromagnetism.

    Science.gov (United States)

    Conduit, G J; Simons, B D

    2009-11-13

    Alongside superfluidity, itinerant (Stoner) ferromagnetism remains one of the most well-characterized phases of correlated Fermi systems. A recent experiment has reported the first evidence for novel phase behavior on the repulsive side of the Feshbach resonance in a two-component ultracold Fermi gas. By adapting recent theoretical studies to the atomic trap geometry, we show that an adiabatic ferromagnetic transition would take place at a weaker interaction strength than is observed in experiment. This discrepancy motivates a simple nonequilibrium theory that takes account of the dynamics of magnetic defects and three-body losses. The formalism developed displays good quantitative agreement with experiment.

  10. Social dynamics in emergency evacuations: Disentangling crowd's attraction and repulsion effects

    Science.gov (United States)

    Haghani, Milad; Sarvi, Majid

    2017-06-01

    The social dynamics of crowds in emergency escape scenarios have been conventionally modelled as the net effect of virtual forces exerted by the crowd on each individual (as self-driven particles), with the magnitude of the influence formulated as decreasing functions of inter-individual distances and the direction of effect assumed to be transitioning from repulsion to attraction by distance. Here, we revisit this conventional assumption using laboratory experimental data. We show based on robust econometric hypothesis-testing methods that individuals' perception of other escapees differs based on whether those individuals are jamming around exit destinations or are on the move towards the destinations. Also, for moving crowds, it differs based on whether the escape destination chosen by the moving flow is visible or invisible to the individual. The presence of crowd jams around a destination, also the movement of crowd flows towards visible destinations are both perceived on average as repulsion (or disutility) effects (with the former showing significantly larger magnitude than the latter). The movement of crowd flows towards an invisible destination, however, is on average perceived as attraction (or utility) effect. Yet, further hypothesis testing showed that neither of those effects in isolation determines adequately whether an individual would merge with or diverge from the crowd. Rather, the social interaction factors act (at significant levels) in conjunction with the physical factors of the environments (including spatial distances to exit destinations and destinations' visibility). In brief, our finding disentangles the conditions under which individuals are more likely to show mass behaviour from the situations where they are more likely to break from the herd. It identifies two factors that moderate the perception of social interactions, ;crowds' jam/movement status; and ;environmental setup;. Our results particularly challenge the taxonomy of

  11. Development of an innovative reflector drive mechanism using magnetic repulsion force for 4S reactor

    International Nuclear Information System (INIS)

    Tsuji, K.; Watanabe, M.; Inagaki, H.; Nishikawa, A.; Takahashi, H.; Wakamatsu, M.; Matsumiya, H.; Nishiguchi, Y.

    2001-01-01

    A small sized fast reactor 4S: (Super Safe Small and Simple) which has a core of 10 - 30 years life time is controlled by reflectors. The reflector is required to be risen at very low speed to make up for the reactivity swing during operation. This report shows the development of an innovative reflector drive mechanism using magnetic repulsion force that can move at a several micrometer per one step. This drive mechanism has a passive shut down capability, and can eliminate reflector drive line. (author)

  12. International guidance activities

    International Nuclear Information System (INIS)

    Richardson, Allan C.B.

    1989-01-01

    International principles for setting Protective Action Guides (PAGs) are contained in two key documents that contain identical statements. One is Publication Number 40 of the ICRP, which was issued in 1985. The title is 'Protection of the Public in the Event of Major Radiation Accidents, Principles for Planning'. The other is the IAEA's Safety Series Publication Number 72, also issued in 1985, written by many of the same authors and titled, 'Principles for Establishing Intervention Levels'. The principles that were set forth in these documents were identical, were incomplete, and they are, unfortunately, the only principles that are now in effect, while proposed revisions go through one draft after another. There are several such draft revisions that are of significance. The most important is that of the ICRP. The basic guidance that applies to most planned exposure to radiation is ICRP Publication 26. That document has been under revision by the Commission for a number of years, and the new version will, for the first time, include recommendations for emergency response. They are now getting close to closure, and I think it should be a very much improved and useful document. But it isn't finished yet. Such guidance doesn't get developed in a vacuum, and there have been a couple of parallel efforts which have provided significant input to the ICRP, which is essentially a behind-closed-doors effort. These other efforts are more open. One of these is being carried out within the IAEA, which has convened annual meetings of national experts for a number of years in Vienna, to generate a replacement for Safety Series No. 72, mentioned earlier. There is a meeting scheduled this December to complete this effort; and, hopefully, we will reach closure at that meeting on at least the basic principles. The Nuclear Energy Agency (NEA) has also been at work. It has convened a group of experts from member nations that have been developing recommendations. There is an overlap

  13. RH Packaging Program Guidance

    International Nuclear Information System (INIS)

    2006-01-01

    The purpose of this program guidance document is to provide the technical requirements for use, operation, inspection, and maintenance of the RH-TRU 72-B Waste Shipping Package and directly related components. This document complies with the requirements as specified in the RH-TRU 72-B Safety Analysis Report for Packaging (SARP), and Nuclear Regulatory Commission (NRC) Certificate of Compliance (C of C) 9212. If there is a conflict between this document and the SARP and/or C of C, the C of C shall govern. The C of C states: 'each package must be prepared for shipment and operated in accordance with the procedures described in Chapter 7.0, Operating Procedures, of the application.' It further states: 'each package must be tested and maintained in accordance with the procedures described in Chapter 8.0, Acceptance Tests and Maintenance Program of the Application.' Chapter 9.0 of the SARP tasks the Waste Isolation Pilot Plant (WIPP) Management and Operating (M and O) Contractor with assuring the packaging is used in accordance with the requirements of the C of C. Because the packaging is NRC-approved, users need to be familiar with 10 Code of Federal Regulations (CFR) 1.8, 'Deliberate Misconduct.' Any time a user suspects or has indications that the conditions of approval in the C of C were not met, the U.S. Department of Energy (DOE) Carlsbad Field Office (CBFO) shall be notified immediately. CBFO will evaluate the issue and notify the NRC if required. In accordance with 10 CFR Part 71, 'Packaging and Transportation of Radioactive Material,' certificate holders, packaging users, and contractors or subcontractors who use, design, fabricate, test, maintain, or modify the packaging shall post copies of (1) 10 CFR Part 21, 'Reporting of Defects and Noncompliance,' regulations, (2) Section 206 of the Energy Reorganization Act of 1974, and (3) NRC Form 3, Notice to Employees. These documents must be posted in a conspicuous location where the activities subject to these

  14. RH Packaging Program Guidance

    International Nuclear Information System (INIS)

    2008-01-01

    The purpose of this program guidance document is to provide the technical requirements for use, operation, inspection, and maintenance of the RH-TRU 72-B Waste Shipping Package (also known as the 'RH-TRU 72-B cask') and directly related components. This document complies with the requirements as specified in the RH-TRU 72-B Safety Analysis Report for Packaging (SARP), and Nuclear Regulatory Commission (NRC) Certificate of Compliance (C of C) 9212. If there is a conflict between this document and the SARP and/or C of C, the C of C shall govern. The C of C states: 'each package must be prepared for shipment and operated in accordance with the procedures described in Chapter 7.0, Operating Procedures, of the application.' It further states: 'each package must be tested and maintained in accordance with the procedures described in Chapter 8.0, Acceptance Tests and Maintenance Program of the Application.' Chapter 9.0 of the SARP tasks the Waste Isolation Pilot Plant (WIPP) Management and Operating (M and O) Contractor with assuring the packaging is used in accordance with the requirements of the C of C. Because the packaging is NRC-approved, users need to be familiar with Title 10 Code of Federal Regulations (CFR) 71.8, 'Deliberate Misconduct.' Any time a user suspects or has indications that the conditions of approval in the C of C were not met, the U.S. Department of Energy (DOE) Carlsbad Field Office (CBFO) shall be notified immediately. The CBFO will evaluate the issue and notify the NRC if required.In accordance with 10 CFR Part 71, 'Packaging and Transportation of Radioactive Material,' certificate holders, packaging users, and contractors or subcontractors who use, design, fabricate, test, maintain, or modify the packaging shall post copies of (1) 10 CFR Part 21, 'Reporting of Defects and Noncompliance,' regulations, (2) Section 206 of the Energy Reorganization Act of 1974, and (3) NRC Form 3, Notice to Employees. These documents must be posted in a conspicuous

  15. Plowshare radiation protection guidance

    International Nuclear Information System (INIS)

    Parker, H.M.

    1969-01-01

    The recommendations of the ICRP and the NCRP were developed primarily for occupational radiation exposures. They were later modified and applied to non-occupational exposures of populations. These, with appropriate interpretations, can be used to provide Plowshare radiation protection guidance. Exposures from Plowshare operations will tend to be acute, arising from radionuclides of relatively short half-life, but will have some chronic aspects due to small amounts of long-lived radionuclides generated. In addition, the neutron activation process of Plowshare technology will produce radionuclides not commonly encountered in routine nuclear energy programs. How these radionuclides contribute to personnel exposure is known for only a few situations that may not be representative of Plowshare exposure. Further complications arise from differences in radionuclide deposition and physiological sensitivity among individuals of different ages and states of health in the exposed population. All parameters necessary to evaluate such exposures are not available, even for good quantitative approximations, resulting in the need for interpretive experience. (author)

  16. Plowshare radiation protection guidance

    Energy Technology Data Exchange (ETDEWEB)

    Parker, H M [Environmental and Life Sciences Division, Battelle Memorial Institute, Pacific Northwest Laboratory, Richland, WA (United States)

    1969-07-01

    The recommendations of the ICRP and the NCRP were developed primarily for occupational radiation exposures. They were later modified and applied to non-occupational exposures of populations. These, with appropriate interpretations, can be used to provide Plowshare radiation protection guidance. Exposures from Plowshare operations will tend to be acute, arising from radionuclides of relatively short half-life, but will have some chronic aspects due to small amounts of long-lived radionuclides generated. In addition, the neutron activation process of Plowshare technology will produce radionuclides not commonly encountered in routine nuclear energy programs. How these radionuclides contribute to personnel exposure is known for only a few situations that may not be representative of Plowshare exposure. Further complications arise from differences in radionuclide deposition and physiological sensitivity among individuals of different ages and states of health in the exposed population. All parameters necessary to evaluate such exposures are not available, even for good quantitative approximations, resulting in the need for interpretive experience. (author)

  17. NGST fine guidance sensor

    Science.gov (United States)

    Rowlands, Neil; Hutchings, John; Murowinski, Richard G.; Alexander, Russ

    2003-03-01

    Instrumentation for the Next Generation Space Telescope (NGST) is currently in the Phase A definition stage. We have developed a concept for the NGST Fine Guidance Sensor or FGS. The FGS is a detector array based imager which resides in the NGST focal plane. We report here on tradeoff studies aimed at defining an overall configuration of the FGS which will meet the performance and interface requirements. A key performance requirement is a noise equivalent angle of 3 milli-arcseconds to be achieved with 95% probability for any pointing of the observatory in the celestial sphere. A key interface requirement is compatibility with the architecture of the Integrated Science Instrument Module (ISIM). The concept developed consists of two independent and redundant FGS modules, each with a 4' x 2' field of view covered by two 2048 x 2048 infrared detector arrays, providing 60 milli-arcsecond sampling. Performance modeling supporting the choice of this architecture and the trade space considered is presented. Each module has a set of readout electronics which perform star detection, pixel-by-pixel correction, and in fine guiding mode, centroid calculation. These readout electronics communicate with the ISIM Command &Data Handling Units where the FGS control software is based. Rationale for this choice of architecture is also presented.

  18. Molecule Matters van der Waals Molecules

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 15; Issue 7. Molecule Matters van der Waals Molecules - Rg•••HF Complexes are Debye Molecules! E Arunan. Feature Article Volume 15 Issue 7 July 2010 pp 667-674. Fulltext. Click here to view fulltext PDF. Permanent link:

  19. First-passage dynamics of linear stochastic interface models: numerical simulations and entropic repulsion effect

    Science.gov (United States)

    Gross, Markus

    2018-03-01

    A fluctuating interfacial profile in one dimension is studied via Langevin simulations of the Edwards–Wilkinson equation with non-conserved noise and the Mullins–Herring equation with conserved noise. The profile is subject to either periodic or Dirichlet (no-flux) boundary conditions. We determine the noise-driven time-evolution of the profile between an initially flat configuration and the instant at which the profile reaches a given height M for the first time. The shape of the averaged profile agrees well with the prediction of weak-noise theory (WNT), which describes the most-likely trajectory to a fixed first-passage time. Furthermore, in agreement with WNT, on average the profile approaches the height M algebraically in time, with an exponent that is essentially independent of the boundary conditions. However, the actual value of the dynamic exponent turns out to be significantly smaller than predicted by WNT. This ‘renormalization’ of the exponent is explained in terms of the entropic repulsion exerted by the impenetrable boundary on the fluctuations of the profile around its most-likely path. The entropic repulsion mechanism is analyzed in detail for a single (fractional) Brownian walker, which describes the anomalous diffusion of a tagged monomer of the interface as it approaches the absorbing boundary. The present study sheds light on the accuracy and the limitations of the weak-noise approximation for the description of the full first-passage dynamics.

  20. Bridge density functional approximation for non-uniform hard core repulsive Yukawa fluid

    International Nuclear Information System (INIS)

    Zhou Shiqi

    2008-01-01

    In this work, a bridge density functional approximation (BDFA) (J. Chem. Phys. 112, 8079 (2000)) for a non-uniform hard-sphere fluid is extended to a non-uniform hard-core repulsive Yukawa (HCRY) fluid. It is found that the choice of a bulk bridge functional approximation is crucial for both a uniform HCRY fluid and a non-uniform HCRY fluid. A new bridge functional approximation is proposed, which can accurately predict the radial distribution function of the bulk HCRY fluid. With the new bridge functional approximation and its associated bulk second order direct correlation function as input, the BDFA can be used to well calculate the density profile of the HCRY fluid subjected to the influence of varying external fields, and the theoretical predictions are in good agreement with the corresponding simulation data. The calculated results indicate that the present BDFA captures quantitatively the phenomena such as the coexistence of solid-like high density phase and low density gas phase, and the adsorption properties of the HCRY fluid, which qualitatively differ from those of the fluids combining both hard-core repulsion and an attractive tail. (condensed matter: structure, thermal and mechanical properties)

  1. Beth-Uhlenbeck approach for repulsive interactions between baryons in a hadron gas

    Science.gov (United States)

    Vovchenko, Volodymyr; Motornenko, Anton; Gorenstein, Mark I.; Stoecker, Horst

    2018-03-01

    The quantum mechanical Beth-Uhlenbeck (BU) approach for repulsive hard-core interactions between baryons is applied to the thermodynamics of a hadron gas. The second virial coefficient a2—the "excluded volume" parameter—calculated within the BU approach is found to be temperature dependent, and it differs dramatically from the classical excluded volume (EV) model result. At temperatures T =100 -200 MeV, the widely used classical EV model underestimates the EV parameter for nucleons at a given value of the nucleon hard-core radius by large factors of 3-4. Previous studies, which employed the hard-core radii of hadrons as an input into the classical EV model, have to be re-evaluated using the appropriately rescaled EV parameters. The BU approach is used to model the repulsive baryonic interactions in the hadron resonance gas (HRG) model. Lattice data for the second- and fourth-order net baryon susceptibilities are described fairly well when the temperature dependent BU baryonic excluded volume parameter corresponds to nucleon hard-core radii of rc=0.25 -0.3 fm. Role of the attractive baryonic interactions is also considered. It is argued that HRG model with a constant baryon-baryon EV parameter vN N≃1 fm3 provides a simple yet efficient description of baryon-baryon interaction in the crossover temperature region.

  2. Synergy of cell-cell repulsion and vacuolation in a computational model of lumen formation.

    Science.gov (United States)

    Boas, Sonja E M; Merks, Roeland M H

    2014-03-06

    A key step in blood vessel development (angiogenesis) is lumen formation: the hollowing of vessels for blood perfusion. Two alternative lumen formation mechanisms are suggested to function in different types of blood vessels. The vacuolation mechanism is suggested for lumen formation in small vessels by coalescence of intracellular vacuoles, a view that was extended to extracellular lumen formation by exocytosis of vacuoles. The cell-cell repulsion mechanism is suggested to initiate extracellular lumen formation in large vessels by active repulsion of adjacent cells, and active cell shape changes extend the lumen. We used an agent-based computer model, based on the cellular Potts model, to compare and study both mechanisms separately and combined. An extensive sensitivity analysis shows that each of the mechanisms on its own can produce lumens in a narrow region of parameter space. However, combining both mechanisms makes lumen formation much more robust to the values of the parameters, suggesting that the mechanisms may work synergistically and operate in parallel, rather than in different vessel types.

  3. Synergy of cell–cell repulsion and vacuolation in a computational model of lumen formation

    Science.gov (United States)

    Boas, Sonja E. M.; Merks, Roeland M. H.

    2014-01-01

    A key step in blood vessel development (angiogenesis) is lumen formation: the hollowing of vessels for blood perfusion. Two alternative lumen formation mechanisms are suggested to function in different types of blood vessels. The vacuolation mechanism is suggested for lumen formation in small vessels by coalescence of intracellular vacuoles, a view that was extended to extracellular lumen formation by exocytosis of vacuoles. The cell–cell repulsion mechanism is suggested to initiate extracellular lumen formation in large vessels by active repulsion of adjacent cells, and active cell shape changes extend the lumen. We used an agent-based computer model, based on the cellular Potts model, to compare and study both mechanisms separately and combined. An extensive sensitivity analysis shows that each of the mechanisms on its own can produce lumens in a narrow region of parameter space. However, combining both mechanisms makes lumen formation much more robust to the values of the parameters, suggesting that the mechanisms may work synergistically and operate in parallel, rather than in different vessel types. PMID:24430123

  4. Lefschetz thimbles in fermionic effective models with repulsive vector-field

    Science.gov (United States)

    Mori, Yuto; Kashiwa, Kouji; Ohnishi, Akira

    2018-06-01

    We discuss two problems in complexified auxiliary fields in fermionic effective models, the auxiliary sign problem associated with the repulsive vector-field and the choice of the cut for the scalar field appearing from the logarithmic function. In the fermionic effective models with attractive scalar and repulsive vector-type interaction, the auxiliary scalar and vector fields appear in the path integral after the bosonization of fermion bilinears. When we make the path integral well-defined by the Wick rotation of the vector field, the oscillating Boltzmann weight appears in the partition function. This "auxiliary" sign problem can be solved by using the Lefschetz-thimble path-integral method, where the integration path is constructed in the complex plane. Another serious obstacle in the numerical construction of Lefschetz thimbles is caused by singular points and cuts induced by multivalued functions of the complexified scalar field in the momentum integration. We propose a new prescription which fixes gradient flow trajectories on the same Riemann sheet in the flow evolution by performing the momentum integration in the complex domain.

  5. Crossing Over from Attractive to Repulsive Interactions in a Tunneling Bosonic Josephson Junction.

    Science.gov (United States)

    Spagnolli, G; Semeghini, G; Masi, L; Ferioli, G; Trenkwalder, A; Coop, S; Landini, M; Pezzè, L; Modugno, G; Inguscio, M; Smerzi, A; Fattori, M

    2017-06-09

    We explore the interplay between tunneling and interatomic interactions in the dynamics of a bosonic Josephson junction. We tune the scattering length of an atomic ^{39}K Bose-Einstein condensate confined in a double-well trap to investigate regimes inaccessible to other superconducting or superfluid systems. In the limit of small-amplitude oscillations, we study the transition from Rabi to plasma oscillations by crossing over from attractive to repulsive interatomic interactions. We observe a critical slowing down in the oscillation frequency by increasing the strength of an attractive interaction up to the point of a quantum phase transition. With sufficiently large initial oscillation amplitude and repulsive interactions, the system enters the macroscopic quantum self-trapping regime, where we observe coherent undamped oscillations with a self-sustained average imbalance of the relative well population. The exquisite agreement between theory and experiments enables the observation of a broad range of many body coherent dynamical regimes driven by tunable tunneling energy, interactions and external forces, with applications spanning from atomtronics to quantum metrology.

  6. Attractive versus repulsive interactions in the Bose-Einstein condensation dynamics of relativistic field theories

    Science.gov (United States)

    Berges, J.; Boguslavski, K.; Chatrchyan, A.; Jaeckel, J.

    2017-10-01

    We study the impact of attractive self-interactions on the nonequilibrium dynamics of relativistic quantum fields with large occupancies at low momenta. Our primary focus is on Bose-Einstein condensation and nonthermal fixed points in such systems. For a model system, we consider O (N ) -symmetric scalar field theories. We use classical-statistical real-time simulations as well as a systematic 1 /N expansion of the quantum (two-particle-irreducible) effective action to next-to-leading order. When the mean self-interactions are repulsive, condensation occurs as a consequence of a universal inverse particle cascade to the zero-momentum mode with self-similar scaling behavior. For attractive mean self-interactions, the inverse cascade is absent, and the particle annihilation rate is enhanced compared to the repulsive case, which counteracts the formation of coherent field configurations. For N ≥2 , the presence of a nonvanishing conserved charge can suppress number-changing processes and lead to the formation of stable localized charge clumps, i.e., Q balls.

  7. Inquiry into thermodynamic behavior of hard sphere plus repulsive barrier of finite height.

    Science.gov (United States)

    Zhou, Shiqi; Solana, J R

    2009-11-28

    A bridge function approximation is proposed to close the Ornstein-Zernike (OZ) integral equation for fluids with purely repulsive potentials. The performance of the bridge function approximation is then tested by applying the approximation to two kinds of repulsive potentials, namely, the square shoulder potential and the triangle shoulder potential. An extensive comparison between simulation and the OZ approach is performed over a wide density range for the fluid phase and several temperatures. It is found that the agreement between the two routes is excellent for not too low temperatures and satisfactory for extremely low temperatures. Then, this globally trustworthy OZ approach is used to investigate the possible existence or not of a liquid anomaly, i.e., a liquid-liquid phase transition at low temperatures and negative values of the thermal expansion coefficient in certain region of the phase diagram. While the existence of the liquid anomaly in the square shoulder potential has been previously predicted by a traditional first-order thermodynamic perturbation theory (TPT), the present investigation indicates that the liquid-liquid phase transition disappears in the OZ approach, so that its prediction by the first-order TPT is only an artifact originating from the low temperature inadequacy of the first-order TPT. However, the OZ approach indeed predicts negative thermal expansion coefficients. The present bridge function approximation, free of adjustable parameters, is suitable to be used within the context of a recently proposed nonhard sphere perturbation scheme.

  8. Gravitational waves during inflation from a 5D large-scale repulsive gravity model

    International Nuclear Information System (INIS)

    Reyes, Luz M.; Moreno, Claudia; Madriz Aguilar, José Edgar; Bellini, Mauricio

    2012-01-01

    We investigate, in the transverse traceless (TT) gauge, the generation of the relic background of gravitational waves, generated during the early inflationary stage, on the framework of a large-scale repulsive gravity model. We calculate the spectrum of the tensor metric fluctuations of an effective 4D Schwarzschild-de Sitter metric on cosmological scales. This metric is obtained after implementing a planar coordinate transformation on a 5D Ricci-flat metric solution, in the context of a non-compact Kaluza-Klein theory of gravity. We found that the spectrum is nearly scale invariant under certain conditions. One interesting aspect of this model is that it is possible to derive the dynamical field equations for the tensor metric fluctuations, valid not just at cosmological scales, but also at astrophysical scales, from the same theoretical model. The astrophysical and cosmological scales are determined by the gravity-antigravity radius, which is a natural length scale of the model, that indicates when gravity becomes repulsive in nature.

  9. Gravitational waves during inflation from a 5D large-scale repulsive gravity model

    Science.gov (United States)

    Reyes, Luz M.; Moreno, Claudia; Madriz Aguilar, José Edgar; Bellini, Mauricio

    2012-10-01

    We investigate, in the transverse traceless (TT) gauge, the generation of the relic background of gravitational waves, generated during the early inflationary stage, on the framework of a large-scale repulsive gravity model. We calculate the spectrum of the tensor metric fluctuations of an effective 4D Schwarzschild-de Sitter metric on cosmological scales. This metric is obtained after implementing a planar coordinate transformation on a 5D Ricci-flat metric solution, in the context of a non-compact Kaluza-Klein theory of gravity. We found that the spectrum is nearly scale invariant under certain conditions. One interesting aspect of this model is that it is possible to derive the dynamical field equations for the tensor metric fluctuations, valid not just at cosmological scales, but also at astrophysical scales, from the same theoretical model. The astrophysical and cosmological scales are determined by the gravity-antigravity radius, which is a natural length scale of the model, that indicates when gravity becomes repulsive in nature.

  10. Gravitational waves during inflation from a 5D large-scale repulsive gravity model

    Energy Technology Data Exchange (ETDEWEB)

    Reyes, Luz M., E-mail: luzmarinareyes@gmail.com [Departamento de Matematicas, Centro Universitario de Ciencias Exactas e ingenierias (CUCEI), Universidad de Guadalajara (UdG), Av. Revolucion 1500, S.R. 44430, Guadalajara, Jalisco (Mexico); Moreno, Claudia, E-mail: claudia.moreno@cucei.udg.mx [Departamento de Matematicas, Centro Universitario de Ciencias Exactas e ingenierias (CUCEI), Universidad de Guadalajara (UdG), Av. Revolucion 1500, S.R. 44430, Guadalajara, Jalisco (Mexico); Madriz Aguilar, Jose Edgar, E-mail: edgar.madriz@red.cucei.udg.mx [Departamento de Matematicas, Centro Universitario de Ciencias Exactas e ingenierias (CUCEI), Universidad de Guadalajara (UdG), Av. Revolucion 1500, S.R. 44430, Guadalajara, Jalisco (Mexico); Bellini, Mauricio, E-mail: mbellini@mdp.edu.ar [Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata (UNMdP), Funes 3350, C.P. 7600, Mar del Plata (Argentina); Instituto de Investigaciones Fisicas de Mar del Plata (IFIMAR) - Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina)

    2012-10-22

    We investigate, in the transverse traceless (TT) gauge, the generation of the relic background of gravitational waves, generated during the early inflationary stage, on the framework of a large-scale repulsive gravity model. We calculate the spectrum of the tensor metric fluctuations of an effective 4D Schwarzschild-de Sitter metric on cosmological scales. This metric is obtained after implementing a planar coordinate transformation on a 5D Ricci-flat metric solution, in the context of a non-compact Kaluza-Klein theory of gravity. We found that the spectrum is nearly scale invariant under certain conditions. One interesting aspect of this model is that it is possible to derive the dynamical field equations for the tensor metric fluctuations, valid not just at cosmological scales, but also at astrophysical scales, from the same theoretical model. The astrophysical and cosmological scales are determined by the gravity-antigravity radius, which is a natural length scale of the model, that indicates when gravity becomes repulsive in nature.

  11. Repulsion between oppositely charged rod-shaped macromolecules: Role of overcharging and ionic confinement

    Science.gov (United States)

    Antila, Hanne S.; Van Tassel, Paul R.; Sammalkorpi, Maria

    2017-09-01

    The interaction between two oppositely charged rod-shaped macro-ions in a micro-ion solution is investigated via Monte Carlo simulations of the primitive model. The focus is on the asymmetry in rod and/or ion charge, i.e., conditions where oppositely charged objects can repel one another. For equally and oppositely charged rods with asymmetric z:1 micro-ions, repulsion may be induced by overcharging one of the rods with the z valent ions. For asymmetrically charged rods in a symmetric z:z micro-ion solution, a repulsive interaction—at separation of the order of one ion diameter—can arise via an unbalanced osmotic pressure contribution from the ionic atmosphere in the inter-rod space, and an attractive interaction—at a smaller separation—may occur due to a "squeezing out" of the micro-ions from the space between the rods (with a consequent gain in entropy). The thermodynamics of each mechanism is investigated in terms of rod charge and size and micro-ion valence, size, and concentration. Our findings contribute to the understanding of the complex role of charge asymmetry on the interaction of, for example, oppositely charged polyelectrolytes, functionalized nanotubes, and rod-like biomolecules, e.g., viruses.

  12. A microelectrostatic repulsive-torque rotation actuator with two-width fingers

    International Nuclear Information System (INIS)

    Fan, Chao; He, Siyuan

    2015-01-01

    A microelectrostatic repulsive-torque rotation actuator with two-width fingers is presented. The actuator consists of finger-shaped electrodes and is made of two thin film layers, i.e. one movable layer and one fixed layer. There are two types of finger electrodes, namely constant-width and two-width fingers. The two-width finger has a narrow lower segment and a wide top segment. The constant-width finger has only the narrow lower segment. Each rotation finger has its corresponding aligned and unaligned fixed fingers. The electrostatic repulsive torque is generated and acts on the rotation fingers to rotate them up and away from the substrate. As a result, rotation is not limited by the gap between the movable and fixed layers and the ‘pull-in’ instability is avoided. Thus a large out-of-plane rotation and high operational stability can be achieved. The actuator is suitable for two-layer surface micromachining. The model of the actuator is developed. Prototypes are fabricated and tested. The experimental tests show that the actuator achieved a mechanical rotation of 7.65° at a driving voltage of 150 V. The settling time for a mechanical rotation of 5° is 5.7 ms. (paper)

  13. Adsorption of different amphiphilic molecules onto polystyrene latices.

    Science.gov (United States)

    Jódar-Reyes, A B; Ortega-Vinuesa, J L; Martín-Rodríguez, A

    2005-02-15

    In order to know the influence of the surface characteristics and the chain properties on the adsorption of amphiphilic molecules onto polystyrene latex, a set of experiments to study the adsorption of ionic surfactants, nonionic surfactants and an amphiphilic synthetic peptide on different latex dispersions was performed. The adsorbed amount versus the equilibrium surfactant concentration was determined. The main adsorption mechanism was the hydrophobic attraction between the nonpolar tail of the molecule and the hydrophobic regions of the latex surface. This attraction overcame the electrostatic repulsion between chains and latex surface with identical charge sign. However, the electrostatic interactions chain-surface and chain-chain also played a role. General patterns for the adsorption of ionic chains on charged latex surfaces could be established. Regarding the shape, the isotherms presented different plateaus corresponding to electrostatic effects and conformational changes. The surfactant size also affects the adsorption results: the higher the hydrophilic moiety in the surfactant molecule the lower the adsorbed amount.

  14. Deep superconducting magnetic traps for neutral atoms and molecules

    International Nuclear Information System (INIS)

    Harris, J.G.E.; Michniak, R.A.; Nguyen, S.V.; Campbell, W.C.; Egorov, D.; Maxwell, S.E.; Buuren, L.D. van; Doyle, J.M.

    2004-01-01

    We describe the design, construction and performance of three realizations of a high-field superconducting magnetic trap for neutral atoms and molecules. Each of these traps utilizes a pair of coaxial coils in the anti-Helmholtz geometry and achieves depths greater than 4 T, allowing it to capture magnetic atoms and molecules cooled in a cryogenic buffer gas. Achieving this depth requires that the repulsive force between the coils (which can exceed 30 metric tons) be contained. We also describe additional features of the traps, including the elimination of trapped fluxes from the coils and the integration of the coils into a cryogenic vacuum environment suitable for producing cold atoms and molecules

  15. General RMP Guidance - Appendix D: OSHA Guidance on PSM

    Science.gov (United States)

    OSHA's Process Safety Management (PSM) Guidance on providing complete and accurate written information concerning process chemicals, process technology, and process equipment; including process hazard analysis and material safety data sheets.

  16. Vortex molecule in a nanoscopic square superconducting plate

    International Nuclear Information System (INIS)

    Suematsu, Hisataka; Kato, Masaru; Ishida, Takekazu; Koyama, Tomio; Machida, Masahiko

    2010-01-01

    Using the finite element method and solving the Bogoliubov-de Gennes equation, we have investigated magnetic field dependence of the stable vortex structures in a mesoscopic superconducting plate at low temperature (T = 0.1T c ). Because of the compactness of vortex configuration, there is interference between bound states around vortices and such quasi-particle structure affects the vortex configuration. Especially in two-vortices state, vortices form a molecule-like state, where bound states of each vortex form molecular orbital like bonding and anti-bonding states. The vortex configuration is different from that, which is expected from the repulsive interaction between vortices. (author)

  17. CAREER GUIDANCE EXPERIENCE ABROAD

    Directory of Open Access Journals (Sweden)

    Sergey N. Tolstoguzov

    2015-01-01

    Full Text Available The aim of this paper is to describe the experience of careeroriented activities carried out with students of schools in developed and developing countries. Career Guidance in Russia, despite the vast experience of its implementation, is experiencing serious difficulties. In this regard, it is important to take into account the international experience career-oriented activities, such as in the developed countries of North America and the European Union as well as in several Asian countries with rapidly growing economies and a large demographic potential, taking into account the best variants for the Russian education system. Methods. The experience of career-oriented work undertaken with pupils of the USA, Canada, Israel, France, UK, Germany, Denmark, Sweden, Japan, Singapore, China and India is shown on the basis of the comparative analysis of different publications and information sources. The author has made an attempt to generalize the principles of psycho-pedagogical and administrative assistance in professional self-determination of senior pupils abroad. Scientific novelty. The approaches to career-oriented activities in countries with different levels of economic development are compared for the first time. Some principles are revealed. Firstly, the higher the income level per capita in the country, the greater attention is given to vocational guidance. The politics in the developed countries is based on interests of the individual: children’s acquaintance with the world of professions begins already at younger school and the moment of definitive selfdetermination is postponed till the end of their senior stage of education; the possibility of direction change of professional preparation in case of detection of discrepancy of qualities of the pupil to originally selected profile is provided. Career-oriented activity in developing countries, on the contrary, is rigidly coordinated to requirements of economy and a labour market

  18. RH Packaging Program Guidance

    International Nuclear Information System (INIS)

    Washington TRU Solutions, LLC

    2003-01-01

    The purpose of this program guidance document is to provide technical requirements for use, operation, inspection, and maintenance of the RH-TRU 72-B Waste Shipping Package and directly related components. This document complies with the requirements as specified in the RH-TRU 72-B Safety Analysis Report for Packaging (SARP), and Nuclear Regulatory Commission (NRC) Certificate of Compliance (C of C) 9212. If there is a conflict between this document and the SARP and/or C of C, the SARP and/or C of C shall govern. The C of C states: ''...each package must be prepared for shipment and operated in accordance with the procedures described in Chapter 7.0, ''Operating Procedures,'' of the application.'' It further states: ''...each package must be tested and maintained in accordance with the procedures described in Chapter 8.0, ''Acceptance Tests and Maintenance Program of the Application.'' Chapter 9.0 of the SARP tasks the Waste Isolation Pilot Plant (WIPP) Management and Operating (M and O) contractor with assuring the packaging is used in accordance with the requirements of the C of C. Because the packaging is NRC approved, users need to be familiar with 10 CFR (section) 71.11, ''Deliberate Misconduct.'' Any time a user suspects or has indications that the conditions of approval in the C of C were not met, the Carlsbad Field Office (CBFO) shall be notified immediately. CBFO will evaluate the issue and notify the NRC if required. This document details the instructions to be followed to operate, maintain, and test the RH-TRU 72-B packaging. This Program Guidance standardizes instructions for all users. Users shall follow these instructions. Following these instructions assures that operations are safe and meet the requirements of the SARP. This document is available on the Internet at: ttp://www.ws/library/t2omi/t2omi.htm. Users are responsible for ensuring they are using the current revision and change notices. Sites may prepare their own document using the word

  19. Electronic and Structural Properties of ABO3: Role of the B-O Coulomb Repulsions for Ferroelectricity.

    Science.gov (United States)

    Miura, Kaoru; Azuma, Masaki; Funakubo, Hiroshi

    2011-01-17

    We have investigated the role of the Ti-O Coulomb repulsions in the appearance of the ferroelectric state in BaTiO3 as well as the role of the Zn-O Coulomb repulsions in BiZn0.5Ti0.5O3, using a first-principles calculation with optimized structures. In tetragonal BaTiO3, it is found that the Coulomb repulsions between Ti 3s and 3p states and O 2s and 2p states have an important role for the appearance of Ti ion displacement. In BiZn0.5Ti0.5O3, on the other hand, the stronger Zn-O Coulomb repulsions, which are due to the 3s, 3p, and 3d (d10) states of the Zn ion, have more important role than the Ti-O Coulomb repulsions for the appearance of the tetragonal structure. Our suggestion is consistent with the other ferroelectric perovskite oxides ABO3 in the appearance of tetragonal structures as well as rhombohedral structures.

  20. The continuum of behavior guidance.

    Science.gov (United States)

    Nelson, Travis

    2013-01-01

    Behavior guidance is a continuum of techniques, basic and advanced, fundamental to the provision of quality dental care for pediatric patients. This practice must be individualized, pairing the correct method of behavior guidance with each child. To select the appropriate technique, the clinician must have a thorough understanding of each aspect of the continuum and anticipate parental expectations, child temperament, and the technical procedures necessary to complete care. By effectively using techniques within the continuum of behavior guidance, a healing relationship with the family is maintained while addressing dental disease and empowering the child to receive dental treatment throughout their lifetime. Copyright © 2013 Elsevier Inc. All rights reserved.

  1. Regulatory guidance for license renewal

    International Nuclear Information System (INIS)

    Thoma, John A.

    1991-01-01

    The proposed 10 CFR Part 54 rule proceduralizes the process for license renewal by identifying both the administrative and technical requirements for a renewal application. To amplify and support this regulation, written guidance has been provided in the form of a draft Regulatory Guide (DG 1009) and a draft Standard Review Plan for License Renewal (NUREG 1299). This guidance is scheduled to be finalized in 1992. Similar guidance will be provided for the proposed revisions to 10 CFR Part 51 concerning the environmental aspects of license renewal. (author)

  2. SPLC Sustainable Purchasing Guidance Profile

    Science.gov (United States)

    To help you find the resource that is right for your organization, EPA conducted a scan of the landscape and developed summary profiles of some of the leading sources of sustainable purchasing guidance around the globe.

  3. CDM Convective Forecast Planning guidance

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The CDM Convective Forecast Planning (CCFP) guidance product provides a foreast of en-route aviation convective hazards. The forecasts are updated every 2 hours and...

  4. Guidance at the educational marketplace

    DEFF Research Database (Denmark)

    Lystbæk, Christian Tang

    in educational policies and institutions. As educational systems have expanded and, further, have been restructured with the expansion of choice opportunities since the 1980s, guidance has become prioritized as a form of counseling or coaching, which can support students. Thus, guidance has become an important...... `agent´ on the educational "market´, assisting (potential) students into and around the `marketplace´. Consequently, guidance is also an important `agent´ for educational institutions that increasingly use marketing strategies to promote themselves on the market to attract and hold on to their “customers......” in order for the institutions to increase their ´market value´, `sales” and “turnover”. Thus, the expansion of guidance is nurtured by the expansion of the logic of marketization and consumerism. Drawing on Foucauldian perspectives in educational research, which highlight the expansion of powerful...

  5. Density-Dependent Formulation of Dispersion-Repulsion Interactions in Hybrid Multiscale Quantum/Molecular Mechanics (QM/MM) Models

    DEFF Research Database (Denmark)

    Curutchet, Carles; Cupellini, Lorenzo; Kongsted, Jacob

    2018-01-01

    embedding approaches, respectively, nonelectrostatic dispersion and repulsion interactions are instead commonly described through classical potentials despite their quantum mechanical origin. Here we present an extension of the Tkatchenko-Scheffler semiempirical van der Waals (vdWTS) scheme aimed......Mixed multiscale quantum/molecular mechanics (QM/MM) models are widely used to explore the structure, reactivity, and electronic properties of complex chemical systems. Whereas such models typically include electrostatics and potentially polarization in so-called electrostatic and polarizable...... at describing dispersion and repulsion interactions between quantum and classical regions within a QM/MM polarizable embedding framework. Starting from the vdWTSexpression, we define a dispersion and a repulsion term, both of them density-dependent and consistently based on a Lennard-Jones-like potential. We...

  6. [Anterior guidance in complete dentures].

    Science.gov (United States)

    Dubreuil, J; Trevelo, A

    1990-01-01

    Although the anterior guidance in complete dentures is not really a guide, the arrangement of the anterior maxillary and mandibular prosthetic teeth, defines a propulsive line called the virtual anterior guidance, a part from the cinematic criterias. The influence of this guide on cuspal movement is superior, in all mandibular points, to the influence of the condylar pathway. If this line is not respected, the practitioner may have to do excessive grindings during occlusal adjustments.

  7. Amplitude death induced by mixed attractive and repulsive coupling in the relay system

    Science.gov (United States)

    Zhao, Nannan; Sun, Zhongkui; Xu, Wei

    2018-01-01

    The amplitude death (AD) phenomenon is found in the relay system in the presence of the mixed couplings composed of attractive coupling and repulsive coupling. The generation mechanism of AD is revealed and shows that the middle oscillator achieving AD is a prerequisite to further suppress oscillation of the outermost oscillators for the paradigmatic Stuart-Landau and Rössler models. Moreover, regarding the Stuart-Landau relay system as a small motif of star network, we also observe that the mixed couplings can facilitate AD state of the whole network system. Particularly, the threshold of coupling strength is invariable with the change of network size. Our findings may shed a new insight to explore the effects of hybrid coupling on complex systems, also provide a new strategy to control dynamic behaviors in engineering science and neuroscience fields.

  8. Current quantization and fractal hierarchy in a driven repulsive lattice gas.

    Science.gov (United States)

    Rotondo, Pietro; Sellerio, Alessandro Luigi; Glorioso, Pietro; Caracciolo, Sergio; Cosentino Lagomarsino, Marco; Gherardi, Marco

    2017-11-01

    Driven lattice gases are widely regarded as the paradigm of collective phenomena out of equilibrium. While such models are usually studied with nearest-neighbor interactions, many empirical driven systems are dominated by slowly decaying interactions such as dipole-dipole and Van der Waals forces. Motivated by this gap, we study the nonequilibrium stationary state of a driven lattice gas with slow-decayed repulsive interactions at zero temperature. By numerical and analytical calculations of the particle current as a function of the density and of the driving field, we identify (i) an abrupt breakdown transition between insulating and conducting states, (ii) current quantization into discrete phases where a finite current flows with infinite differential resistivity, and (iii) a fractal hierarchy of excitations, related to the Farey sequences of number theory. We argue that the origin of these effects is the competition between scales, which also causes the counterintuitive phenomenon that crystalline states can melt by increasing the density.

  9. Phase diagram of Rydberg atoms with repulsive van der Waals interaction

    International Nuclear Information System (INIS)

    Osychenko, O. N.; Astrakharchik, G. E.; Boronat, J.; Lutsyshyn, Y.; Lozovik, Yu. E.

    2011-01-01

    We report a quantum Monte Carlo calculation of the phase diagram of bosons interacting with a repulsive inverse sixth power pair potential, a model for assemblies of Rydberg atoms in the local van der Waals blockade regime. The model can be parametrized in terms of just two parameters, the reduced density and temperature. Solidification happens to the fcc phase. At zero temperature, the transition density is found with the diffusion Monte Carlo method at density ρ=3.9 ((ℎ/2π) 2 /mC 6 ) 3/4 , where C 6 is the strength of the interaction. The solidification curve at nonzero temperature is studied with the path-integral Monte Carlo approach and is compared with transitions in corresponding harmonic and classical crystals. Relaxation mechanisms are considered in relation to present experiments.

  10. New exact solutions of Einstein's field equations: gravitational force can also be repulsive!

    International Nuclear Information System (INIS)

    Dietz, W.

    1988-01-01

    This article has not been written for specialists of exact solutions of Einstein's field equations but for physicists who are interested in nontrivial information on this topic. We recall the history and some basic properties of exact solutions of Einstein's vacuum equations. We show that the field equations for stationary axisymmetric vacuum gravitational fields can be expressed by only one nonlinear differential equation for a complex function. This compact form of the field equations allows the generation of almost all stationary axisymmetric vacuum gravitational fields. We present a new stationary two-body solution of Einstein's equations as an application of this generation technique. This new solution proves the existence of a macroscopic, repulsive spin-spin interaction in general relativity. Some estimates that are related to this new two-body solution are given

  11. Particle-Hole Asymmetry and Brightening of Solitons in a Strongly Repulsive Bose-Einstein Condensate

    International Nuclear Information System (INIS)

    Balakrishnan, Radha; Satija, Indubala I.; Clark, Charles W.

    2009-01-01

    We study solitary wave propagation in the condensate of a system of hard-core bosons with nearest-neighbor interactions. For this strongly repulsive system, the evolution equation for the condensate order parameter of the system, obtained using spin-coherent state averages, is different from the usual Gross-Pitaevskii equation (GPE). The system is found to support two kinds of solitons when there is a particle-hole imbalance: a dark soliton that dies out as the velocity approaches the sound velocity and a new type of soliton which brightens and persists all the way up to the sound velocity, transforming into a periodic wave train at supersonic speed. Analogous to the GPE soliton, the energy-momentum dispersion for both solitons is characterized by Lieb II modes.

  12. Thermal algebraic-decay charge liquid driven by competing short-range Coulomb repulsion

    Science.gov (United States)

    Kaneko, Ryui; Nonomura, Yoshihiko; Kohno, Masanori

    2018-05-01

    We explore the possibility of a Berezinskii-Kosterlitz-Thouless-like critical phase for the charge degrees of freedom in the intermediate-temperature regime between the charge-ordered and disordered phases in two-dimensional systems with competing short-range Coulomb repulsion. As the simplest example, we investigate the extended Hubbard model with on-site and nearest-neighbor Coulomb interactions on a triangular lattice at half filling in the atomic limit by using a classical Monte Carlo method, and find a critical phase, characterized by algebraic decay of the charge correlation function, belonging to the universality class of the two-dimensional XY model with a Z6 anisotropy. Based on the results, we discuss possible conditions for the critical phase in materials.

  13. Off-shell sensitivity, repulsive correlations and the pion-nucleus optical potential

    Energy Technology Data Exchange (ETDEWEB)

    Keister, B D [Carnegie-Mellon Univ., Pittsburgh, Pa. (USA). Dept. of Physics

    1977-07-01

    Repulsive nucleon-nucleon correlations tend to reduce the dependence of pion-nucleus elastic scattering upon the off-shell pion-nucleon dynamics. However, optical potential calculations can in practice be quite sensitive to the particular choice of off-shell model parameters. It is argued that this sensitivity results from the nature of the optical potential as a one-body operator which introduces extra off-shell dependence not found in physical many-body process itself. Thus, one must be very careful in any attempt to extract correlation or off-shell information, or to predict pion-nucleus phase shifts, by means of an optical potential theory. Results of model calculations are presented for purposes of illustration.

  14. Structure factor of polymers interacting via a short range repulsive potential: Application to hairy wormlike micelles

    International Nuclear Information System (INIS)

    Massiera, Gladys; Ramos, Laurence; Ligoure, Christian; Pitard, Estelle

    2003-01-01

    We use the random phase approximation to compute the structure factor S(q) of a solution of chains interacting through a soft and short range repulsive potential V. Above a threshold polymer concentration, whose magnitude is essentially controlled by the range of the potential, S(q) exhibits a peak whose position depends on the concentration. We take advantage of the close analogy between polymers and wormlike micelles and apply our model, using a Gaussian function for V, to quantitatively analyze experimental small angle neutron scattering profiles of solutions of hairy wormlike micelles. These samples, which consist in surfactant self-assembled flexible cylinders decorated by amphiphilic copolymer, provide indeed an appropriate experimental model system to study the structure of sterically interacting polymer solutions

  15. Disassembly Control of Saccharide-Based Amphiphiles Driven by Electrostatic Repulsion.

    Science.gov (United States)

    Yamada, Taihei; Kokado, Kenta; Sada, Kazuki

    2017-03-14

    According to the design of disassembly using electrostatic repulsion, novel amphiphiles consisting of a lipophilic ion part and a hydrophilic saccharide part were synthesized via the facile copper-catalyzed click reaction, and their molecular assemblies in water and chloroform were studied. The amphiphiles exhibited a molecular orientation opposite to that of the conventional amphiphiles in each case. ζ Potential measurements indicated that the lipophilic ion part is exposed outside in chloroform. The size of a solvophobic part in the amphiphiles dominates the size of an assembling structure; that is, in water, these amphiphiles tethering different lengths of the saccharide part exhibited almost identical assembling size, whereas in chloroform, the size depends on the length of the saccharide part in the amphiphiles.

  16. Inverse Estimation of Surface Radiation Properties Using Repulsive Particle Swarm Optimization Algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyun Ho [Sejong University, Sejong (Korea, Republic of); Kim, Ki Wan [Agency for Defense Development, Daejeon (Korea, Republic of)

    2014-09-15

    The heat transfer mechanism for radiation is directly related to the emission of photons and electromagnetic waves. Depending on the participation of the medium, the radiation can be classified into two forms: surface and gas radiation. In the present study, unknown radiation properties were estimated using an inverse boundary analysis of surface radiation in an axisymmetric cylindrical enclosure. For efficiency, a repulsive particle swarm optimization (RPSO) algorithm, which is a relatively recent heuristic search method, was used as inverse solver. By comparing the convergence rates and accuracies with the results of a genetic algorithm (GA), the performances of the proposed RPSO algorithm as an inverse solver was verified when applied to the inverse analysis of the surface radiation problem.

  17. Inverse Estimation of Surface Radiation Properties Using Repulsive Particle Swarm Optimization Algorithm

    International Nuclear Information System (INIS)

    Lee, Kyun Ho; Kim, Ki Wan

    2014-01-01

    The heat transfer mechanism for radiation is directly related to the emission of photons and electromagnetic waves. Depending on the participation of the medium, the radiation can be classified into two forms: surface and gas radiation. In the present study, unknown radiation properties were estimated using an inverse boundary analysis of surface radiation in an axisymmetric cylindrical enclosure. For efficiency, a repulsive particle swarm optimization (RPSO) algorithm, which is a relatively recent heuristic search method, was used as inverse solver. By comparing the convergence rates and accuracies with the results of a genetic algorithm (GA), the performances of the proposed RPSO algorithm as an inverse solver was verified when applied to the inverse analysis of the surface radiation problem

  18. Non-spherical particle formation induced by repulsive hydration forces during spray drying

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Yong Jae; Lee, Jin-Woo; Chang, Hankwon; Jang, Hee-Dong, E-mail: hdjang@kigam.re.kr; Cho, Kuk, E-mail: kukcho@pusan.ac.kr [Korea Institute of Geoscience and Mineral Resources (Korea, Republic of)

    2013-09-15

    Non-spherical particles were produced during a spray-drying process, but the exact mechanism of their formation was unknown. The non-spherical particles form when the strength of the colloidal droplets is exceeded by external stress stemming from drag in the velocity gradient. Here, we show that repulsive hydration forces reduce the mechanical strength of the droplets; this is critical to the formation of non-spherical particles. Toroidal or ellipsoidal particles were prepared from low-concentration hydrophilic SiO{sub 2}, TiO{sub 2}, and CuO colloidal solutions, but not from hydrophobic ZnO colloidal solutions. The surface properties of the solid particulates are crucial for the morphology of particles formed during spray drying.

  19. Non-spherical particle formation induced by repulsive hydration forces during spray drying

    International Nuclear Information System (INIS)

    Suh, Yong Jae; Lee, Jin-Woo; Chang, Hankwon; Jang, Hee-Dong; Cho, Kuk

    2013-01-01

    Non-spherical particles were produced during a spray-drying process, but the exact mechanism of their formation was unknown. The non-spherical particles form when the strength of the colloidal droplets is exceeded by external stress stemming from drag in the velocity gradient. Here, we show that repulsive hydration forces reduce the mechanical strength of the droplets; this is critical to the formation of non-spherical particles. Toroidal or ellipsoidal particles were prepared from low-concentration hydrophilic SiO 2 , TiO 2 , and CuO colloidal solutions, but not from hydrophobic ZnO colloidal solutions. The surface properties of the solid particulates are crucial for the morphology of particles formed during spray drying

  20. Current quantization and fractal hierarchy in a driven repulsive lattice gas

    Science.gov (United States)

    Rotondo, Pietro; Sellerio, Alessandro Luigi; Glorioso, Pietro; Caracciolo, Sergio; Cosentino Lagomarsino, Marco; Gherardi, Marco

    2017-11-01

    Driven lattice gases are widely regarded as the paradigm of collective phenomena out of equilibrium. While such models are usually studied with nearest-neighbor interactions, many empirical driven systems are dominated by slowly decaying interactions such as dipole-dipole and Van der Waals forces. Motivated by this gap, we study the nonequilibrium stationary state of a driven lattice gas with slow-decayed repulsive interactions at zero temperature. By numerical and analytical calculations of the particle current as a function of the density and of the driving field, we identify (i) an abrupt breakdown transition between insulating and conducting states, (ii) current quantization into discrete phases where a finite current flows with infinite differential resistivity, and (iii) a fractal hierarchy of excitations, related to the Farey sequences of number theory. We argue that the origin of these effects is the competition between scales, which also causes the counterintuitive phenomenon that crystalline states can melt by increasing the density.

  1. Time delay induced different synchronization patterns in repulsively coupled chaotic oscillators

    Science.gov (United States)

    Yao, Chenggui; Yi, Ming; Shuai, Jianwei

    2013-09-01

    Time delayed coupling plays a crucial role in determining the system's dynamics. We here report that the time delay induces transition from the asynchronous state to the complete synchronization (CS) state in the repulsively coupled chaotic oscillators. In particular, by changing the coupling strength or time delay, various types of synchronous patterns, including CS, antiphase CS, antiphase synchronization (ANS), and phase synchronization, can be generated. In the transition regions between different synchronous patterns, bistable synchronous oscillators can be observed. Furthermore, we show that the time-delay-induced phase flip bifurcation is of key importance for the emergence of CS. All these findings may light on our understanding of neuronal synchronization and information processing in the brain.

  2. Effect of long-range repulsive Coulomb interactions on packing structure of adhesive particles.

    Science.gov (United States)

    Chen, Sheng; Li, Shuiqing; Liu, Wenwei; Makse, Hernán A

    2016-02-14

    The packing of charged micron-sized particles is investigated using discrete element simulations based on adhesive contact dynamic model. The formation process and the final obtained structures of ballistic packings are studied to show the effect of interparticle Coulomb force. It is found that increasing the charge on particles causes a remarkable decrease of the packing volume fraction ϕ and the average coordination number 〈Z〉, indicating a looser and chainlike structure. Force-scaling analysis shows that the long-range Coulomb interaction changes packing structures through its influence on particle inertia before they are bonded into the force networks. Once contact networks are formed, the expansion effect caused by repulsive Coulomb forces are dominated by short-range adhesion. Based on abundant results from simulations, a dimensionless adhesion parameter Ad*, which combines the effects of the particle inertia, the short-range adhesion and the long-range Coulomb interaction, is proposed and successfully scales the packing results for micron-sized particles within the latest derived adhesive loose packing (ALP) regime. The structural properties of our packings follow well the recent theoretical prediction which is described by an ensemble approach based on a coarse-grained volume function, indicating some kind of universality in the low packing density regime of the phase diagram regardless of adhesion or particle charge. Based on the comprehensive consideration of the complicated inter-particle interactions, our findings provide insight into the roles of short-range adhesion and repulsive Coulomb force during packing formation and should be useful for further design of packings.

  3. Sugar Antennae for Guidance Signals: Syndecans and Glypicans Integrate Directional Cues for Navigating Neurons

    Directory of Open Access Journals (Sweden)

    Christa Rhiner

    2006-01-01

    Full Text Available Attractive and repulsive signals guide migrating nerve cells in all directions when the nervous system starts to form. The neurons extend thin processes, axons, that connect over wide distances with other brain cells to form a complicated neuronal network. One of the most fascinating questions in neuroscience is how the correct wiring of billions of nerve cells in our brain is controlled. Several protein families are known to serve as guidance cues for navigating neurons and axons. Nevertheless, the combinatorial potential of these proteins seems to be insufficient to sculpt the entire neuronal network and the appropriate formation of connections. Recently, heparan sulfate proteoglycans (HSPGs, which are present on the cell surface of neurons and in the extracellular matrix through which neurons and axons migrate, have been found to play a role in regulating cell migration and axon guidance. Intriguingly, the large number of distinct modifications that can be put onto the sugar side chains of these PGs would in principle allow for an enormous diversity of HSPGs, which could help in regulating the vast number of guidance choices taken by individual neurons. In this review, we will focus on the role of the cell surface HSPGs syndecan and glypican and specific HS modifications in promoting neuronal migration, axon guidance, and synapse formation.

  4. BmRobo2/3 is required for axon guidance in the silkworm Bombyx mori.

    Science.gov (United States)

    Li, Xiao-Tong; Yu, Qi; Zhou, Qi-Sheng; Zhao, Xiao; Liu, Zhao-Yang; Cui, Wei-Zheng; Liu, Qing-Xin

    2016-02-15

    Axon guidance is critical for proper wiring of the nervous system. During the neural development, the axon guidance molecules play a key role and direct axons to choose the correct way to reach the target. Robo, as the receptor of axon guidance molecule Slit, is evolutionarily conserved from planarians to humans. However, the function of Robo in the silkworm, Bombyx mori, remained unknown. In this study, we cloned robo2/3 from B. mori (Bmrobo2/3), a homologue of robo2/3 in Tribolium castaneum. Moreover, BmRobo2/3 was localized in the neuropil, and RNAi-mediated knockdown of Bmrobo2/3 resulted in the longitudinal connectives forming closer to the midline. These data demonstrate that BmRobo2/3 is required for axon guidance in the silkworm. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Repulsive guidance cue semaphorin 3A in urine predicts the progression of acute kidney injury in adult patients from a mixed intensive care unit.

    Science.gov (United States)

    Doi, Kent; Noiri, Eisei; Nangaku, Masaomi; Yahagi, Naoki; Jayakumar, Calpurnia; Ramesh, Ganesan

    2014-01-01

    Predicting the development of acute kidney injury (AKI) in the critical care setting is challenging. Although several biomarkers showed somewhat satisfactory performance for detecting established AKI even in a heterogeneous disease-oriented population, identification of new biomarkers that predict the development of AKI accurately is urgently required. A single-center prospective observational cohort study was undertaken to evaluate for the first time the reliability of the newly identified biomarker semaphorin 3A for AKI diagnosis in heterogeneous intensive care unit populations. In addition to five urinary biomarkers of L-type fatty acid-binding protein (L-FABP), neutrophil gelatinase-associated lipocalin (NGAL), IL-18, albumin and N-acetyl-β-d-glucosaminidase (NAG), urinary semaphorin 3A was measured at intensive care unit (ICU) admission. Three hundred thirty-nine critically ill adult patients were recruited for this study. Among them, 131 patients (39%) were diagnosed with AKI by the RIFLE criteria and 66 patients were diagnosed as AKI at post-ICU admission (later-onset AKI). Eighty-four AKI patients showed worsening severity during 1 week observation (AKI progression). Although L-FABP, NGAL and IL-18 showed significantly higher area under the curve (AUC)-receiver operating characteristic (ROC) values than semaphorin 3A in detecting established AKI, semaphorin 3A was able to detect later-onset AKI and AKI progression with similar AUC-ROC values compared with the other five biomarkers [AUC-ROC (95% CI) for established AKI 0.64 (0.56-0.71), later-onset AKI 0.71 (0.64-0.78), AKI progression 0.71 (0.64-0.77)]. Urinary semaphorin 3A was not increased in non-progressive established AKI, while the other biomarkers were elevated regardless of further progression. Finally, sepsis did not have any impact on semaphorin 3A while the other urinary biomarkers were increased with sepsis. Semaphorin 3A is a new biomarker of AKI which may have a distinct predictive use for AKI progression when compared with other AKI biomarkers.

  6. Quality in career guidance: The Danish case

    DEFF Research Database (Denmark)

    Plant, Peter

    2011-01-01

    Quality assurance systems are introduced in career guidance to monitor, control and develop guidance interventions. The Danish case represents at centrally driven, top-down approach......Quality assurance systems are introduced in career guidance to monitor, control and develop guidance interventions. The Danish case represents at centrally driven, top-down approach...

  7. Density-Dependent Formulation of Dispersion-Repulsion Interactions in Hybrid Multiscale Quantum/Molecular Mechanics (QM/MM) Models.

    Science.gov (United States)

    Curutchet, Carles; Cupellini, Lorenzo; Kongsted, Jacob; Corni, Stefano; Frediani, Luca; Steindal, Arnfinn Hykkerud; Guido, Ciro A; Scalmani, Giovanni; Mennucci, Benedetta

    2018-03-13

    Mixed multiscale quantum/molecular mechanics (QM/MM) models are widely used to explore the structure, reactivity, and electronic properties of complex chemical systems. Whereas such models typically include electrostatics and potentially polarization in so-called electrostatic and polarizable embedding approaches, respectively, nonelectrostatic dispersion and repulsion interactions are instead commonly described through classical potentials despite their quantum mechanical origin. Here we present an extension of the Tkatchenko-Scheffler semiempirical van der Waals (vdW TS ) scheme aimed at describing dispersion and repulsion interactions between quantum and classical regions within a QM/MM polarizable embedding framework. Starting from the vdW TS expression, we define a dispersion and a repulsion term, both of them density-dependent and consistently based on a Lennard-Jones-like potential. We explore transferable atom type-based parametrization strategies for the MM parameters, based on either vdW TS calculations performed on isolated fragments or on a direct estimation of the parameters from atomic polarizabilities taken from a polarizable force field. We investigate the performance of the implementation by computing self-consistent interaction energies for the S22 benchmark set, designed to represent typical noncovalent interactions in biological systems, in both equilibrium and out-of-equilibrium geometries. Overall, our results suggest that the present implementation is a promising strategy to include dispersion and repulsion in multiscale QM/MM models incorporating their explicit dependence on the electronic density.

  8. Nucleus-nucleus potential with repulsive core and elastic scattering. Part 1. Nucleus-nucleus interaction potential

    International Nuclear Information System (INIS)

    Davidovs'ka, O.Yi.; Denisov, V.Yu.; Nesterov, V.O.

    2010-01-01

    Various approaches for nucleus-nucleus interaction potential evaluation are discussed in details. It is shown that the antisymmetrization of nucleons belonging to different nuclei and the Pauli principle give the essential contribution into the nucleus-nucleus potential at distances, when nuclei are strongly overlapping, and lead to appearance of the repulsive core of nucleus nucleus interaction at small distances between nuclei.

  9. Separating the effects of repulsive and attractive forces on the phase diagram, interfacial, and critical properties of simple fluids.

    Science.gov (United States)

    Fuentes-Herrera, M; Moreno-Razo, J A; Guzmán, O; López-Lemus, J; Ibarra-Tandi, B

    2016-06-07

    Molecular simulations in the canonical and isothermal-isobaric ensembles were performed to study the effect of varying the shape of the intermolecular potential on the phase diagram, critical, and interfacial properties of model fluids. The molecular interactions were modeled by the Approximate Non-Conformal (ANC) theory potentials. Unlike the Lennard-Jones or Morse potentials, the ANC interactions incorporate parameters (called softnesses) that modulate the steepness of the potential in their repulsive and attractive parts independently. This feature allowed us to separate unambiguously the role of each region of the potential on setting the thermophysical properties. In particular, we found positive linear correlation between all critical coordinates and the attractive and repulsive softness, except for the critical density and the attractive softness which are negatively correlated. Moreover, we found that the physical properties related to phase coexistence (such as span of the liquid phase between the critical and triple points, variations in the P-T vaporization curve, interface width, and surface tension) are more sensitive to changes in the attractive softness than to the repulsive one. Understanding the different roles of attractive and repulsive forces on phase coexistence may contribute to developing more accurate models of liquids and their mixtures.

  10. Effect of particle-particle attractive and repulsive interactions on the retention in field-flow fractionation

    Czech Academy of Sciences Publication Activity Database

    Janča, J.; Berneron, J.-F.; Stejskal, Jaroslav

    2010-01-01

    Roč. 15, č. 8 (2010), s. 536-543 ISSN 1023-666X R&D Projects: GA AV ČR IAA400500905 Institutional research plan: CEZ:AV0Z40500505 Keywords : attractive and repulsive interactions * colloidal crystals * colloidal particles Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.814, year: 2010

  11. Construction and Self-Assembly of Single-Chain Polymer Nanoparticles via Coordination Association and Electrostatic Repulsion in Water.

    Science.gov (United States)

    Zhu, Zhengguang; Xu, Na; Yu, Qiuping; Guo, Lei; Cao, Hui; Lu, Xinhua; Cai, Yuanli

    2015-08-01

    Simultaneous coordination-association and electrostatic-repulsion interactions play critical roles in the construction and stabilization of enzymatic function metal centers in water media. These interactions are promising for construction and self-assembly of artificial aqueous polymer single-chain nanoparticles (SCNPs). Herein, the construction and self-assembly of dative-bonded aqueous SCNPs are reported via simultaneous coordination-association and electrostatic-repulsion interactions within single chains of histamine-based hydrophilic block copolymer. The electrostatic-repulsion interactions are tunable through adjusting the imidazolium/imidazole ratio in response to pH, and in situ Cu(II)-coordination leads to the intramolecular association and single-chain collapse in acidic water. SCNPs are stabilized by the electrostatic repulsion of dative-bonded block and steric shielding of nonionic water-soluble block, and have a huge specific surface area of function metal centers accessible to substrates in acidic water. Moreover, SCNPs can assemble into micelles, networks, and large particles programmably in response to the solution pH. These unique media-sensitive phase-transformation behaviors provide a general, facile, and versatile platform for the fabrication of enzyme-inspired smart aqueous catalysts. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Non vertical vibronic transitions in atom molecule collisions

    International Nuclear Information System (INIS)

    Klomp, U.C.

    1982-01-01

    This thesis is mainly devoted to an experimental and theoretical study on vibronic transitions which occur in collisions between an alkali atom and several diatomic molecules. An experimental study on electron and ion production in repulsive Cs-CO and Cs-N 2 collisions, and in Cs-NO and Cs-O 2 non-repulsive collisions is presented. The experimental data are discussed in terms of some existing models. It is clear that a new consistent theory on vibronic transitions is needed to explain the experimental data. Such a theory is presented, and it is shown that some existing models are limiting cases of this theory. An experimental study on the relative probabilities for ion and electron production in collisions between a Na, K or Cs atom and an O 2 or NO molecule is also described. These experiments suggest that the incident velocity of the alkali atoms has a predominant influence on the relative probabilities for ion and electron production in these collisions. (Auth.)

  13. Information architecture. Volume 3: Guidance

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-04-01

    The purpose of this document, as presented in Volume 1, The Foundations, is to assist the Department of Energy (DOE) in developing and promulgating information architecture guidance. This guidance is aimed at increasing the development of information architecture as a Departmentwide management best practice. This document describes departmental information architecture principles and minimum design characteristics for systems and infrastructures within the DOE Information Architecture Conceptual Model, and establishes a Departmentwide standards-based architecture program. The publication of this document fulfills the commitment to address guiding principles, promote standard architectural practices, and provide technical guidance. This document guides the transition from the baseline or defacto Departmental architecture through approved information management program plans and budgets to the future vision architecture. This document also represents another major step toward establishing a well-organized, logical foundation for the DOE information architecture.

  14. Small-Angle Neutron Scattering Study of Interplay of Attractive and Repulsive Interactions in Nanoparticle-Polymer System.

    Science.gov (United States)

    Kumar, Sugam; Aswal, Vinod K; Kohlbrecher, Joachim

    2016-02-16

    The phase behavior of nanoparticle (silica)-polymer (polyethylene glycol) system without and with an electrolyte (NaCl) has been studied. It is observed that nanoparticle-polymer system behaves very differently in the presence of electrolyte. In the absence of electrolyte, the nanoparticle-polymer system remains in one-phase even at very high polymer concentrations. On the other hand, a re-entrant phase behavior is found in the presence of electrolyte, where one-phase (individual) system undergoes two-phase (nanoparticle aggregation) and then back to one-phase with increasing polymer concentration. The regime of two-phase system has been tuned by varying the electrolyte concentration. The polymer concentration range over which the two-phase system exists is significantly enhanced with the increase in the electrolyte concentration. These systems have been characterized by small-angle neutron scattering (SANS) experiments of contrast-marching the polymer to the solvent. The data are modeled using a two-Yukawa potential accounting for both attractive and repulsive parts of the interaction between nanoparticles. The phase behavior of nanoparticle-polymer system is explained by interplay of attractive (polymer-induced attractive depletion between nanoparticles) and repulsive (nanoparticle-nanoparticle electrostatic repulsion and polymer-polymer repulsion) interactions present in the system. In the absence of electrolyte, the strong electrostatic repulsion between nanoparticles dominates over the polymer-induced depletion attraction and the nanoparticle system remains in one-phase. With addition of electrolyte, depletion attraction overcomes electrostatic repulsion at some polymer concentration, resulting into nanoparticle aggregation and two-phase system. Further addition of polymer increases the polymer-polymer repulsion which eventually reduces the strength of depletion and hence re-entrant phase behavior. The effects of varying electrolyte concentration on the phase

  15. Spectroscopic calculation of the excited electronic states with spin orbit effect of the molecule NaCs

    International Nuclear Information System (INIS)

    Bleik, S.; Korek, M.; Allouche, A.R.

    2004-01-01

    Full text.The existence of new experimental data on the alkali dimers has stimulated theoretical approaches, necessary to provide predictions accurate enough to be useful for interpretation and evenly for guidance of experiments. With the aim of improving the accuracy of predictions we will perform a theoretical study of the electronic structure of the molecule NaCs using a method mainly in the way by which core-valence effects are taken into account. To investigate the electronic structure of NaCs we will use the package CIPSI (Configuration Interaction by Perturbation of a multiconfiguration wave function Selected Interactively) of the Laboratoire de Physique Quantique (Toulouse, France). The atoms Na and Cs will be treated through non-empirical effective one electron core potentials of Durand and Barthelat type. Molecular orbitals for NaCs will be derived from Self Consistent field Calculations (SCF) and full valence Configuration Interaction (IC) calculations. A core-core interaction more elaborated than the usual approximation 1/R will be taken into account as the sum of an exponential repulsive term plus a long range dispersion term approximated by the well known London formula. Potential energy calculations will be performed for different molecular states, for numerous values of the inter-nuclear distance R in a wide range. Spectroscopic constants have been derived for the bound states with regular shape. A ro vibrational study have been performed for the ground states with a calculation of the rotational and centrifugal distortion constants. A calculation for the transition dipole moment and matrix elements have been done for the bound states

  16. Effects of Coulomb repulsion on conductivity of heterojunction carbon nanotube quantum dots with spin-orbital coupling and interacting leads

    Energy Technology Data Exchange (ETDEWEB)

    Ogloblya, O.V., E-mail: olexandr.ogloblya@gmail.com [Taras Shevchenko National University, 64/13 Volodymyrska St., Kyiv 01601 (Ukraine); Kuznietsova, H.M. [Taras Shevchenko National University, 64/13 Volodymyrska St., Kyiv 01601 (Ukraine); Strzhemechny, Y.M. [Dept. of Physics and Astronomy, Texas Christian University, Fort Worth, TX 76129 (United States)

    2017-01-01

    We performed numerical studies for the conductance of a heterojunction carbon nanotube quantum dot (QD) with an extra spin orbital quantum number and a conventional QD in which the electron state is determined only by the spin quantum number. Our computational approach took into account the spin-orbit interaction and the Coulomb repulsion both between electrons on a QD as well as between the QD electron and the contacts. We utilized an approach based on the Keldysh non-equilibrium Green's function formalism as well as the equation of motion technique. We focused on the case of a finite Coulombic on-site repulsion and considered two possible cases of applied voltage: spin bias and conventional bias. For the system of interest we obtained bias spectroscopy diagrams, i.e. contour charts showing dependence of conductivity on two variables - voltage and the energy level position in a QD - which can be controlled by the plunger gate voltage. The finite Coulombic repulsion splits the density of states into two distinct maxima with the energy separation between them controlled by that parameter. It was also shown that an increase of either the value of the on-site Coulomb repulsion in a QD or the parameter of the Coulomb repulsion between the electrons in the QD and the contacts leads to an overall shift of the density of electronic states dependence toward higher energy values. Presence of the QD-lead interaction yields formation of a new pair of peaks in the differential conductance dependence. We also show that existence of four quantum states in a QD leads to abrupt changes in the density of states. These results could be beneficial for potential applications in nanotube-based amperometric sensors.

  17. Nanopore Device for Reversible Ion and Molecule Sensing or Migration

    Science.gov (United States)

    Pourmand, Nader (Inventor); Vilozny, Boaz (Inventor); Actis, Paolo (Inventor); Seger, R. Adam (Inventor); Singaram, Bakthan (Inventor)

    2015-01-01

    Disclosed are methods and devices for detection of ion migration and binding, utilizing a nanopipette adapted for use in an electrochemical sensing circuit. The nanopipette may be functionalized on its interior bore with metal chelators for binding and sensing metal ions or other specific binding molecules such as boronic acid for binding and sensing glucose. Such a functionalized nanopipette is comprised in an electrical sensor that detects when the nanopipette selectively and reversibly binds ions or small molecules. Also disclosed is a nanoreactor, comprising a nanopipette, for controlling precipitation in aqueous solutions by voltage-directed ion migration, wherein ions may be directed out of the interior bore by a repulsing charge in the bore.

  18. Superconductivity in a Fermi liquid from repulsive interactions: The role of electron–phonon interaction

    International Nuclear Information System (INIS)

    Fan, J.D.; Malozovsky, Y.M.

    2013-01-01

    Highlights: • The sign reversal of pair interaction in momentum space is proved. • It is also shown that electron-phonon interaction in fact leads to the pairing-break effect. • Transition temperature into superconductivity depends on competition between electron-phonon and Coulomb interactions. • Calculated exponent α of the isotope effect shows the possibility equal to, greater or less than 0.5, and even negative. -- Abstract: Based on our previously proven theorem that the interaction between a pair of quasiparticles in the normal Fermi liquid has an opposite sign to the interaction between particles, we consider pair correlation between a pair of quasiparticles when the interaction between particles is repulsive. For the convenience of statements, we have presented in this article once again the proof of the theorem in terms of an exact equation for the thermodynamic potential due to interaction between particles and based on the Green’s function method. Further, we have derived the Landau expansion of the thermodynamic potentials in terms of the variation of the quasiparticle distribution function. We have also derived the expansion of the thermodynamic potential in terms of the variation of an exact single particle (not quasiparticles), these derivations lead to the relationship between the interaction function for two quasiparticles and the interaction energy between two particles as shown. According to the proven theorem the interaction between a pair of quasiparticles is attractive in this case, the pairing – Cooper’s pairing between a pair of quasiparticles is possible. We solve the Bethe–Salpeter type equation for paring of two quasiparticles when both interactions – the Coulomb repulsive and electron–phonon interaction are present. We show that the electron–phonon interaction, in fact, leads to the pair breaking effect, in contrast to the common belief that electron–phonon interaction is the main mechanism for Cooper’s pair

  19. Bipolar outflows as a repulsive gravitational phenomenon - Azimuthally Symmetric Theory of Gravitation (II)

    International Nuclear Information System (INIS)

    Nyambuya, Golden Gadzirayi

    2010-01-01

    This paper is part of a series on the Azimuthally Symmetric Theory of Gravitation (ASTG). This theory is built on Laplace-Poisson's well known equation and it has been shown that the ASTG is capable of explaining, from a purely classical physics standpoint, the precession of the perihelion of solar planets as a consequence of the azimuthal symmetry emerging from the spin of the Sun. This symmetry has and must have an influence on the emergent gravitational field. We show herein that the emergent equations from the ASTG, under some critical conditions determined by the spin, do possess repulsive gravitational fields in the polar regions of the gravitating body in question. This places the ASTG on an interesting pedestal to infer the origins of outflows as a repulsive gravitational phenomenon. Outflows are a ubiquitous phenomenon found in star forming systems and their true origin is a question yet to be settled. Given the current thinking on their origin, the direction that the present paper takes is nothing short of an asymptotic break from conventional wisdom; at the very least, it is a complete paradigm shift because gravitation is not at all associated with this process, but rather it is thought to be an all-attractive force that only tries to squash matter together onto a single point. Additionally, we show that the emergent Azimuthally Symmetric Gravitational Field from the ASTG strongly suggests a solution to the supposed Radiation Problem that is thought to be faced by massive stars in their process of formation. That is, at ∼ 8-10 M sun , radiation from the nascent star is expected to halt the accretion of matter. We show that in-falling material will fall onto the equatorial disk and from there, this material will be channeled onto the forming star via the equatorial plane, thus accretion of mass continues well past the value of ∼ 8-10 M sun , albeit via the disk. Along the equatorial plane, the net force (with the radiation force included) on any

  20. DOE Waste Treatability Group Guidance

    Energy Technology Data Exchange (ETDEWEB)

    Kirkpatrick, T.D.

    1995-01-01

    This guidance presents a method and definitions for aggregating U.S. Department of Energy (DOE) waste into streams and treatability groups based on characteristic parameters that influence waste management technology needs. Adaptable to all DOE waste types (i.e., radioactive waste, hazardous waste, mixed waste, sanitary waste), the guidance establishes categories and definitions that reflect variations within the radiological, matrix (e.g., bulk physical/chemical form), and regulated contaminant characteristics of DOE waste. Beginning at the waste container level, the guidance presents a logical approach to implementing the characteristic parameter categories as part of the basis for defining waste streams and as the sole basis for assigning streams to treatability groups. Implementation of this guidance at each DOE site will facilitate the development of technically defined, site-specific waste stream data sets to support waste management planning and reporting activities. Consistent implementation at all of the sites will enable aggregation of the site-specific waste stream data sets into comparable national data sets to support these activities at a DOE complex-wide level.

  1. Agent Based Individual Traffic Guidance

    DEFF Research Database (Denmark)

    Wanscher, Jørgen

    of the project were not previously considered. We define a special inseparable cost function and develop a solution complex capable of using this cost function. In relation to calibration and estimation of statistical models used for dynamic route guidance we worked with generating random number sequences...

  2. Consensus standard requirements and guidance

    International Nuclear Information System (INIS)

    Putman, V.L.

    1995-01-01

    This report presents information from the ANS Criticality Alarm System Workshop relating to the consensus standard requirements and guidance. Topics presented include: definition; nomenclature; requirements and recommendations; purpose of criticality alarms; design criteria; signal characteristics; reliability, dependability and durability; tests; and emergency preparedness and planning

  3. DOE Waste Treatability Group Guidance

    International Nuclear Information System (INIS)

    Kirkpatrick, T.D.

    1995-01-01

    This guidance presents a method and definitions for aggregating U.S. Department of Energy (DOE) waste into streams and treatability groups based on characteristic parameters that influence waste management technology needs. Adaptable to all DOE waste types (i.e., radioactive waste, hazardous waste, mixed waste, sanitary waste), the guidance establishes categories and definitions that reflect variations within the radiological, matrix (e.g., bulk physical/chemical form), and regulated contaminant characteristics of DOE waste. Beginning at the waste container level, the guidance presents a logical approach to implementing the characteristic parameter categories as part of the basis for defining waste streams and as the sole basis for assigning streams to treatability groups. Implementation of this guidance at each DOE site will facilitate the development of technically defined, site-specific waste stream data sets to support waste management planning and reporting activities. Consistent implementation at all of the sites will enable aggregation of the site-specific waste stream data sets into comparable national data sets to support these activities at a DOE complex-wide level

  4. Negative-mass mitigation of Coulomb repulsion for terahertz undulator radiation of electron bunches

    Energy Technology Data Exchange (ETDEWEB)

    Balal, N.; Magory, E. [Ariel University, Ariel 40700 (Israel); Bandurkin, I. V. [Institute of Applied Physics, Russian Academy of Sciences, 46 Ulyanov St., Nizhny Novgorod 603950 (Russian Federation); Bratman, V. L. [Ariel University, Ariel 40700 (Israel); Institute of Applied Physics, Russian Academy of Sciences, 46 Ulyanov St., Nizhny Novgorod 603950 (Russian Federation); Savilov, A. V. [Institute of Applied Physics, Russian Academy of Sciences, 46 Ulyanov St., Nizhny Novgorod 603950 (Russian Federation); Lobachevsky State University of Nizhny Novgorod, 23 Gagarin Avenue, Nizhny Novgorod 603950 (Russian Federation)

    2015-10-19

    It is proposed to utilize the effect of negative mass for stabilization of the effective axial size of very dense and short electron bunches produced by photo-injector guns by using combined undulator and strong uniform magnetic fields. It has been shown that in the “abnormal” regime, an increase in the electron energy leads to a decrease in the axial velocity of the electron; due to the negative-mass effect, the Coulomb repulsion of electrons leads to their attraction and formation of a fairly stable and compact bunch “nucleus.” An undulator with a strong uniform magnetic field providing the negative-mass effect is designed for an experimental source of terahertz radiation. The use of the negative-mass regime in this experiment should result in a long-pulse coherent spontaneous undulator emission from a short dense moderately relativistic (5.5 MeV) photo-injector electron bunch with a high (up to 20%) efficiency and a narrow frequency spectrum.

  5. Mean-field behavior in coupled oscillators with attractive and repulsive interactions.

    Science.gov (United States)

    Hong, Hyunsuk; Strogatz, Steven H

    2012-05-01

    We consider a variant of the Kuramoto model of coupled oscillators in which both attractive and repulsive pairwise interactions are allowed. The sign of the coupling is assumed to be a characteristic of a given oscillator. Specifically, some oscillators repel all the others, thus favoring an antiphase relationship with them. Other oscillators attract all the others, thus favoring an in-phase relationship. The Ott-Antonsen ansatz is used to derive the exact low-dimensional dynamics governing the system's long-term macroscopic behavior. The resulting analytical predictions agree with simulations of the full system. We explore the effects of changing various parameters, such as the width of the distribution of natural frequencies and the relative strengths and proportions of the positive and negative interactions. For the particular model studied here we find, unexpectedly, that the mixed interactions produce no new effects. The system exhibits conventional mean-field behavior and displays a second-order phase transition like that found in the original Kuramoto model. In contrast to our recent study of a different model with mixed interactions [Phys. Rev. Lett. 106, 054102 (2011)], the π state and traveling-wave state do not appear for the coupling type considered here.

  6. Structure and dynamics of soft repulsive colloidal suspensions in the vicinity of the glass transition.

    Science.gov (United States)

    Crassous, Jérôme J; Casal-Dujat, Lucia; Medebach, Martin; Obiols-Rabasa, Marc; Vincent, Romaric; Reinhold, Frank; Boyko, Volodymyr; Willerich, Immanuel; Menzel, Andreas; Moitzi, Christian; Reck, Bernd; Schurtenberger, Peter

    2013-08-20

    We use a combination of different scattering techniques and rheology to highlight the link between structure and dynamics of dense aqueous suspensions of soft repulsive colloids in the vicinity of a glass transition. Three different latex formulations with an increasing amount of the hydrophilic component resulting in either purely electrostatically or electrosterically stabilized suspensions are investigated. From the analysis of the static structure factor measured by small-angle X-ray scattering, we derive an effective volume fraction that includes contributions from interparticle interactions. We further investigate the dynamics of the suspensions using 3D cross-correlation dynamic light scattering (3DDLS) and rheology. We analyze the data using an effective hard sphere model and in particular compare the linear viscoelasticity and flow behavior to the predictions of mode coupling theory, which accounts for a purely kinetic glass transition determined by the equilibrium structure factor. We demonstrate that seemingly very different colloidal systems exhibit the same generic behavior when the effects from interparticle interactions are incorporated using an effective volume fraction description.

  7. Various oscillation patterns in phase models with locally attractive and globally repulsive couplings.

    Science.gov (United States)

    Sato, Katsuhiko; Shima, Shin-ichiro

    2015-10-01

    We investigate a phase model that includes both locally attractive and globally repulsive coupling in one dimension. This model exhibits nontrivial spatiotemporal patterns that have not been observed in systems that contain only local or global coupling. Depending on the relative strengths of the local and global coupling and on the form of global coupling, the system can show a spatially uniform state (in-phase synchronization), a monotonically increasing state (traveling wave), and three types of oscillations of relative phase difference. One of the oscillations of relative phase difference has the characteristic of being locally unstable but globally attractive. That is, any small perturbation to the periodic orbit in phase space destroys its periodic motion, but after a long time the system returns to the original periodic orbit. This behavior is closely related to the emergence of saddle two-cluster states for global coupling only, which are connected to each other by attractive heteroclinic orbits. The mechanism of occurrence of this type of oscillation is discussed.

  8. Repulsive baryonic interactions and lattice QCD observables at imaginary chemical potential

    Directory of Open Access Journals (Sweden)

    Volodymyr Vovchenko

    2017-12-01

    Full Text Available The first principle lattice QCD methods allow to calculate the thermodynamic observables at finite temperature and imaginary chemical potential. These can be compared to the predictions of various phenomenological models. We argue that Fourier coefficients with respect to imaginary baryochemical potential are sensitive to modeling of baryonic interactions. As a first application of this sensitivity, we consider the hadron resonance gas (HRG model with repulsive baryonic interactions, which are modeled by means of the excluded volume correction. The Fourier coefficients of the imaginary part of the net-baryon density at imaginary baryochemical potential – corresponding to the fugacity or virial expansion at real chemical potential – are calculated within this model, and compared with the Nt=12 lattice data. The lattice QCD behavior of the first four Fourier coefficients up to T≃185 MeV is described fairly well by an interacting HRG with a single baryon–baryon eigenvolume interaction parameter b≃1 fm3, while the available lattice data on the difference χ2B−χ4B of baryon number susceptibilities is reproduced up to T≃175 MeV. Keywords: Hadron resonance gas, Excluded volume, Imaginary chemical potential

  9. Dynamics of unvisited sites in the presence of mutually repulsive random walkers

    International Nuclear Information System (INIS)

    Das, Pratap Kumar; Dasgupta, Subinay; Sen, Parongama

    2007-01-01

    We have considered the persistence of unvisited sites of a lattice, i.e., the probability S(t) that a site remains unvisited till time t in the presence of mutually repulsive random walkers in one dimension. The dynamics of this system has direct correspondence to that of the domain walls in a certain system of Ising spins where the number of domain walls becomes fixed following a zero-temperature quench. Here we get the result that S(t) ∼ exp(-αt β ) where β is close to 0.5 and α a function of the density of the walkers ρ. The fraction of persistent sites in the presence of independent walkers of density ρ' is known to be S'(t) = exp(-2√(2/π ρ't 1/2 ). We show that a mapping of the interacting walkers' problem to the independent walkers' problem is possible with ρ' = ρ/(1 - ρ) provided ρ' and ρ are small. We also discuss some other intricate results obtained in the interacting walkers' case

  10. Gauche effect in 1,2-difluoroethane. Hyperconjugation, bent bonds, steric repulsion.

    Science.gov (United States)

    Goodman, Lionel; Gu, Hongbing; Pophristic, Vojislava

    2005-02-17

    Natural bond orbital deletion calculations show that whereas the gauche preference arises from vicinal hyperconjugative interaction between anti C-H bonds and C-F* antibonds, the cis C-H/C-F* interactions are substantial (approximately 25% of the anti interaction). The established significantly >60 degrees FCCF dihedral angle for the equilibrium conformer can then be rationalized in terms of the hyperconjugation model alone by taking into account both anti interactions that maximize near 60 degrees and the smaller cis interactions that maximize at a much larger dihedral angle. This explanation does not invoke repulsive forces to rationalize the 72 degrees equilibrium conformer angle. The relative minimum energy for the trans conformer is the consequence of a balance between decreasing hyperconjugative stabilization and decreasing steric destabilization as the FCCF torsional angle approaches 180 degrees . The torsional coordinate is predicted to be strongly contaminated by CCF bending, with the result that approximately half of the trans --> gauche stabilization energy stems from mode coupling.

  11. Harmonically trapped attractive and repulsive spin–orbit and Rabi coupled Bose–Einstein condensates

    International Nuclear Information System (INIS)

    Chiquillo, Emerson

    2017-01-01

    Numerically we investigate the ground state of effective one-dimensional spin–orbit (SO) and Rabi coupled two pseudo-spinor Bose–Einstein condensates (BECs) under the effect of harmonic traps. For both signs of the interaction, density profiles of SO and Rabi coupled BECs in harmonic potentials, which simulate a real experimental situation are obtained. The harmonic trap causes a strong reduction of the multi-peak nature of the condensate and it increases its density. For repulsive interactions, the increase of SO coupling results in an uncompressed less dense condensate and with increased multi-peak nature of the density. The increase of Rabi coupling leads to a density increase with an almost constant number of multi-peaks. For both signs of the interaction and negative values of Rabi coupling, the condensate develops a notch in the central point and it seems to a dark-in-bright soliton. In the case of the attractive nonlinearity, an interesting result is the increase of the collapse threshold under the action of the SO and Rabi couplings. (paper)

  12. Unconventional superconductivity in a two-dimensional repulsive gas of fermions with spin-orbit coupling

    Science.gov (United States)

    Wang, Luyang; Vafek, Oskar

    2014-02-01

    We investigate the superconducting instability of a two-dimensional repulsive Fermi gas with Rashba spin-orbit coupling αR. Using renormalization group approach, we find the superconducting transition temperature as a function of the dimensionless ratio Θ=1}/{2}mαR2/EF where EF = 0 when the smaller Fermi surface shrinks to a (Dirac) point. The general trend is that superconductivity is enhanced as Θ increases, but in an intermediate regime Θ ∼ 0.1, a dome-like behavior appears. At a very small value of Θ, the angular momentum channel jz in which superconductivity occurs is quite high. With increasing Θ, jz decreases with a step of 2 down to jz = 6, after which we find the sequence jz = 6, 4, 6, 2, the last value of which continues to Θ → ∞. In an extended range of Θ, the superconducting gap predominantly resides on the large Fermi surface, while Josephson coupling induces a much smaller gap on the small Fermi surface. Below the superconducting transition temperature, we apply mean field theory to derive the self-consistent equations and find the condensation energies. The state with the lowest condensation energy is an unconventional superconducting state which breaks time-reversal symmetry, and in which singlet and triplet pairings are mixed. In general, these states are topologically nontrivial, and the Chern number of the state with total angular momentum jz is C = 2jz.

  13. Long-lived force patterns and deformation waves at repulsive epithelial boundaries

    Science.gov (United States)

    Rodríguez-Franco, Pilar; Brugués, Agustí; Marín-Llauradó, Ariadna; Conte, Vito; Solanas, Guiomar; Batlle, Eduard; Fredberg, Jeffrey J.; Roca-Cusachs, Pere; Sunyer, Raimon; Trepat, Xavier

    2017-10-01

    For an organism to develop and maintain homeostasis, cell types with distinct functions must often be separated by physical boundaries. The formation and maintenance of such boundaries are commonly attributed to mechanisms restricted to the cells lining the boundary. Here we show that, besides these local subcellular mechanisms, the formation and maintenance of tissue boundaries involves long-lived, long-ranged mechanical events. Following contact between two epithelial monolayers expressing, respectively, EphB2 and its ligand ephrinB1, both monolayers exhibit oscillatory patterns of traction forces and intercellular stresses that tend to pull cell-matrix adhesions away from the boundary. With time, monolayers jam, accompanied by the emergence of deformation waves that propagate away from the boundary. This phenomenon is not specific to EphB2/ephrinB1 repulsion but is also present during the formation of boundaries with an inert interface and during fusion of homotypic epithelial layers. Our findings thus unveil a global physical mechanism that sustains tissue separation independently of the biochemical and mechanical features of the local tissue boundary.

  14. The quark model and the nature of the repulsive core of the nucleon-nucleon interaction

    International Nuclear Information System (INIS)

    Faessler, A.; Fernandez, F.; Luebeck, G.; Shimizu, K.

    1982-01-01

    The nature of the repulsive core of the nucleon-nucleon is studied in the quark model. The resonating group equation for nucleon-nucleon scattering is solved with the colour Fermi-Breit interaction including further a linear or quadratic confinement potential. It is shown that the colour magnetic interaction which is adjusted to the Δ-nucleon mass splitting favours the orbital symmetry and disfavours the completely symmetric orbital state. For the important orbital symmetry the relative S wave function between the two nucleons has to have a node. In the framework of the resonating group including the NN, ΔΔ and the hidden colour (CC) channels it is shown that this node produces a 3 S and 1 S phase shift which is identical to a hard core phase shift with a hard core radius γ 0 between 0.3 and 0.6 fm depending on the assumed root mean square radius of the quark part of the nucleon. (orig./HSI)

  15. Riemannian geometry of thermodynamics and systems with repulsive power-law interactions.

    Science.gov (United States)

    Ruppeiner, George

    2005-07-01

    A Riemannian geometric theory of thermodynamics based on the postulate that the curvature scalar R is proportional to the inverse free energy density is used to investigate three-dimensional fluid systems of identical classical point particles interacting with each other via a power-law potential energy gamma r(-alpha) . Such systems are useful in modeling melting transitions. The limit alpha-->infinity corresponds to the hard sphere gas. A thermodynamic limit exists only for short-range (alpha>3) and repulsive (gamma>0) interactions. The geometric theory solutions for given alpha>3 , gamma>0 , and any constant temperature T have the following properties: (1) the thermodynamics follows from a single function b (rho T(-3/alpha) ) , where rho is the density; (2) all solutions are equivalent up to a single scaling constant for rho T(-3/alpha) , related to gamma via the virial theorem; (3) at low density, solutions correspond to the ideal gas; (4) at high density there are solutions with pressure and energy depending on density as expected from solid state physics, though not with a Dulong-Petit heat capacity limit; (5) for 33.7913 a phase transition is required to go between these regimes; (7) for any alpha>3 we may include a first-order phase transition, which is expected from computer simulations; and (8) if alpha-->infinity, the density approaches a finite value as the pressure increases to infinity, with the pressure diverging logarithmically in the density difference.

  16. Two-dimensional assemblies of soft repulsive colloids confined at fluid interfaces

    Science.gov (United States)

    Isa, L.; Buttinoni, I.; Fernandez-Rodriguez, M. A.; Vasudevan, S. A.

    2017-07-01

    Colloidal systems are an excellent example of a materials class for which interrogating fundamental questions leads to answers of direct applied relevance. In our group, we in particular focus on two-dimensional assemblies of micro- and nano-particles confined at the interface between two fluids, e.g., oil-water. Here, we review our work on systems interacting through soft repulsive forces of different origin, i.e., electrostatic and steric. By starting from the paradigmatic case of charged colloids at an interface, we show how they are both offering great opportunities as model systems to investigate the structural and mechanical response of materials and as versatile patterning tools for surface nanostructuring. We then move to the case of deformable particles interacting via steric contacts. We first examine microgel particles, which we also demonstrate as very promising models for structural investigations and robust elements for tunable nanolithography. We conclude by briefly discussing the case of particles comprising a hard inorganic core and a deformable polymer shell, which maintain some of the advantageous features of microgel particles, but also enable the realization of two-dimensional functional materials. This article offers our perspective on a very active field of research, where many interesting developments are expected in the near future. Contribution to the Focus Issue Self-assemblies of Inorganic and Organic Nanomaterials edited by Marie-Paule Pileni.

  17. Preparation and Characterization of Nanofibrillated Cellulose from Bamboo Fiber via Ultrasonication Assisted by Repulsive Effect

    Directory of Open Access Journals (Sweden)

    Zhijun Hu

    2017-01-01

    Full Text Available Nanofibrillated celluloses (NFCs have recently drawn much attention because of their exceptional physicochemical properties. However, the existing preparation procedures either produce low yields or severely degrade the cellulose and, moreover, are not energy efficient. The purpose of this study was to develop a novel process using ultrasonic homogenization to isolate fibrils from bamboo fiber (BF with the assistance of negatively charged entities. The obtained samples were characterized by the degree of substitution (DS of carboxymethyl, Fourier-transform infrared (FT-IR spectroscopy, X-ray diffraction (XRD, thermogravimetric analysis, and transmission electron microscopy (TEM. The results showed that an NFC yield could be obtained above 70% through this route. The enzyme hydrolysis could enhance the surface charge of the fiber, and mechanical activation facilitates an increase in the DS. The disintegrating efficiency of the cellulose fibrils significantly depended on the input power of ultrasonication and the DS. FT-IR spectra confirmed the occurrence of the carboxymethylation reaction based on the appearance of the characteristic signal for the carboxyl group. From XRD analysis, it was observed that the presence of the carboxyl groups makes the isolation more efficient attributed to the ionic repulsion between the carboxylate groups of the cellulose chains.

  18. Magnetism of one-dimensional strongly repulsive spin-1 bosons with antiferromagnetic spin-exchange interaction

    International Nuclear Information System (INIS)

    Lee, J. Y.; Guan, X. W.; Batchelor, M. T.; Lee, C.

    2009-01-01

    We investigate magnetism and quantum phase transitions in a one-dimensional system of integrable spin-1 bosons with strongly repulsive density-density interaction and antiferromagnetic spin-exchange interaction via the thermodynamic Bethe ansatz method. At zero temperature, the system exhibits three quantum phases: (i) a singlet phase of boson pairs when the external magnetic field H is less than the lower critical field H c1 ; (ii) a ferromagnetic phase of atoms in the hyperfine state |F=1, m F =1> when the external magnetic field exceeds the upper critical field H c2 ; and (iii) a mixed phase of singlet pairs and unpaired atoms in the intermediate region H c1 c2 . At finite temperatures, the spin fluctuations affect the thermodynamics of the model through coupling the spin bound states to the dressed energy for the unpaired m F =1 bosons. However, such spin dynamics is suppressed by a sufficiently strong external field at low temperatures. Thus the singlet pairs and unpaired bosons may form a two-component Luttinger liquid in the strong coupling regime.

  19. attitude of secondary school students towards guidance

    African Journals Online (AJOL)

    Elizabeth Egbochuku

    gender and school location significantly influenced students' attitude towards guidance ... students respond and perceive guidance and counselling services will, to ... counsellors will be appointed in post-primary institutions and tertiary levels.

  20. Partial synchronization of relaxation oscillators with repulsive coupling in autocatalytic integrate-and-fire model and electrochemical experiments

    Science.gov (United States)

    Kori, Hiroshi; Kiss, István Z.; Jain, Swati; Hudson, John L.

    2018-04-01

    Experiments and supporting theoretical analysis are presented to describe the synchronization patterns that can be observed with a population of globally coupled electrochemical oscillators close to a homoclinic, saddle-loop bifurcation, where the coupling is repulsive in the electrode potential. While attractive coupling generates phase clusters and desynchronized states, repulsive coupling results in synchronized oscillations. The experiments are interpreted with a phenomenological model that captures the waveform of the oscillations (exponential increase) followed by a refractory period. The globally coupled autocatalytic integrate-and-fire model predicts the development of partially synchronized states that occur through attracting heteroclinic cycles between out-of-phase two-cluster states. Similar behavior can be expected in many other systems where the oscillations occur close to a saddle-loop bifurcation, e.g., with Morris-Lecar neurons.

  1. Formation of Ultracold Molecules

    Energy Technology Data Exchange (ETDEWEB)

    Cote, Robin [Univ. of Connecticut, Storrs, CT (United States)

    2016-01-28

    Advances in our ability to slow down and cool atoms and molecules to ultracold temperatures have paved the way to a revolution in basic research on molecules. Ultracold molecules are sensitive of very weak interactions, even when separated by large distances, which allow studies of the effect of those interactions on the behavior of molecules. In this program, we have explored ways to form ultracold molecules starting from pairs of atoms that have already reached the ultracold regime. We devised methods that enhance the efficiency of ultracold molecule production, for example by tuning external magnetic fields and using appropriate laser excitations. We also investigates the properties of those ultracold molecules, especially their de-excitation into stable molecules. We studied the possibility of creating new classes of ultra-long range molecules, named macrodimers, thousand times more extended than regular molecules. Again, such objects are possible because ultra low temperatures prevent their breakup by collision. Finally, we carried out calculations on how chemical reactions are affected and modified at ultracold temperatures. Normally, reactions become less effective as the temperature decreases, but at ultracold temperatures, they can become very effective. We studied this counter-intuitive behavior for benchmark chemical reactions involving molecular hydrogen.

  2. Review of soil contamination guidance

    International Nuclear Information System (INIS)

    Mueller, M.A.; Kennedy, W.E. Jr.; Soldat, J.K.

    1981-08-01

    A review of existing and proposed radioactive soil contamination standards and guidance was conducted for United Nuclear Corporation (UNC), Office of Surplus Facilities Management. Information was obtained from both government agencies and other sources during a literature survey. The more applicable standards were reviewed, evaluated, and summarized. Information pertaining to soil contamination for both facility operation and facility decommissioning was obtained from a variety of sources. These sources included: the Code of Federal Regulations, regulatory guides, the Federal Register, topical reports written by various government agencies, topical reports written by national laboratories, and publications from the American National Standards Institute (ANSI). It was difficult to directly compare the standards and guidance obtained from these sources since each was intended for a specific situation and different units or bases were used. However, most of the information reviewed was consistent with the philosophy of maintaining exposures at levels as low as reasonably achievable

  3. Guidance on future art commissioning.

    Science.gov (United States)

    2009-05-01

    Delegates at Building Better Healthcare's recent "National Patient Environment and the Arts Conference 2009" in London heard how national public arts think tank ixia has appointed Bristol-based arts and wellbeing development agency Willis Newson to write "concise and convincing guidance" on commissioning art for new healthcare facilities. A key message, during a joint presentation, was that integrating artwork into hospitals and other healthcare premises requires the earliest possible consideration to reap the maximum rewards.

  4. Current materiality guidance for auditors

    OpenAIRE

    McKee, Thomas E.; Eilifsen, Aasmund

    2000-01-01

    Auditors have to make materiality judgments on every audit. This is a difficult process, as both quantitative and qualitative factors have to be evaluated. Additionally, there is no formal guidance for how to implement the materiality concepts discussed in the auditing standards. Although they are sometimes difficult to make, good materiality judgments are crucial for the conduct of a successful audit as poor judgments can result in an audit that is ineffective and/or inefficient. This report...

  5. 2011 Army Strategic Planning Guidance

    Science.gov (United States)

    2011-03-25

    TESI ) of 22,000 Soldiers, the Army’s total force by the end of the mid-term period is programmed to be 520K (AC). We will achieve a more...dwell ratios, extending TESI authority to adequately man deploying units and sustain the All-Volunteer Force, right-sizing the generating force, and... TESI Temporary End-Strength Increase WMD Weapons of Mass Destruction 2011 ARMY STRATEGIC PLANNING GUIDANCE Page 19 2011

  6. Vocational guidance in social volunteering

    Directory of Open Access Journals (Sweden)

    Nikolay S. Pryazhnikov

    2017-03-01

    Full Text Available The paper discusses the possibilities and limitations of vocational guidance in the social volunteering system. The essence of volunteer work is closely related with assistance to desperate people in searching for the meaning of living, often coinciding with labour activity that are deemed in terms of “the main matter of life” and “the leading activity”. For adolescents, it is the choice of career, and for adults, it is the work proper (i.e. an essential condition for personal self-realization. The problem of “forced volunteering” for experts in vocational guidance also means that they often have to work voluntarily and unselfishly outside the official guidelines. To clarify the terms «volunteer» and «a person in desperate need of help» the study used the method of analyzing the documents, e.g. the Regulations on Social Volunteering, the generalization of psychological sources, the initial survey of university students as active supporters of the volunteer movement, On the essence of volunteering and the place of career guidance in selfless social work. Vocational guidance is not excluded from the general system of volunteerism, but has an insufficiently defined status and low popularity among participants in social volunteering. Also, the problem of «forced volunteering» of experts in career counseling, which often requires voluntary and unselfish performance of quality work outside the framework of official instructions, is also indicated. Simultaneously, positive aspects of such disinterested career initiatives are noted, in particular, less control by the official inspectors (or customers and, accordingly, greater freedom of creativity than when someone else does the work.

  7. Visual guidance of mobile platforms

    Science.gov (United States)

    Blissett, Rodney J.

    1993-12-01

    Two systems are described and results presented demonstrating aspects of real-time visual guidance of autonomous mobile platforms. The first approach incorporates prior knowledge in the form of rigid geometrical models linking visual references within the environment. The second approach is based on a continuous synthesis of information extracted from image tokens to generate a coarse-grained world model, from which potential obstacles are inferred. The use of these techniques in workplace applications is discussed.

  8. Individual plant examination: Submittal guidance

    International Nuclear Information System (INIS)

    1989-08-01

    Based on a Policy Statement on Severe Accidents Regarding Future Designs and Existing Plants, the performance of a plant examination is requested from the licensee of each nuclear power plant. The plant examination looks for vulnerabilities to severe accidents and cost-effective safety improvements that reduce or eliminate the important vulnerabilities. This document delineates guidance for reporting the results of that plant examination. 38 refs., 2 tabs

  9. Repulsion forces of superplasticizers on ground granulated blast furnace slag in alkaline media, from AFM measurements to rheological properties

    OpenAIRE

    Palacios, M.; Bowen, P.; Kappl, M.; Butt, H. J.; Stuer, M.; Pecharromán, C.; Aschauer, U.; Puertas, F.

    2012-01-01

    The electrostatic and steric repulsion induced by different superplasticizers on ground granulated blast furnace slag in alkaline media have been studied. The superplasticizers were sulfonated naphthalene, sulfonated melamine, vinyl copolymer, and polycarboxylate- based admixtures. With these superplasticizers the slag suspensions had negative zeta potentials, ranging from -3 to -10 mV. For the first time the adsorbed layer thicknesses for superplasticizers on slag using colloidal probe atomi...

  10. Exact results for the many-body problem in one dimension with repulsive delta-function interaction

    International Nuclear Information System (INIS)

    Yang, C.N.

    1983-01-01

    The repulsive δ interaction problem in one dimension for N particles is reduced, through the use of Bethe's hypothesis, to an eigenvalue problem of matrices of the same sizes as the irreducible representations R of the permutation group S/sub N/. For some R's this eigenvalue problem itself is solved by a second use of Bethe's hypothesis, in a generalized form. In particular, the ground-state problem of spin-1/2 fermions is reduced to a generalized Fredholm equation

  11. Multicritical behavior of the antiferromagnetic Blume-Emery-Griffiths model with the repulsive biquadratic coupling in an external magnetic field

    International Nuclear Information System (INIS)

    Erdinc, Ahmet; Canko, Osman; Keskin, Mustafa

    2006-01-01

    We have studied the antiferromagnetic Blume-Emery-Griffiths model with the repulsive biquadratic coupling in an external magnetic field using the lowest approximation of the cluster variation method which is identical to the mean-field approximation. First, we have investigated the thermal variations of the sublattice magnetizations and obtained four different main topological types. Then, we have calculated the phase diagrams and five main different phase diagram topologies are found. Finally, the discussion and comparison of the phase diagrams are made

  12. Multicritical behavior of the antiferromagnetic Blume-Emery-Griffiths model with the repulsive biquadratic coupling in an external magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Erdinc, Ahmet [Department of Physics, Erciyes University, 38039 Kayseri (Turkey); Canko, Osman [Department of Physics, Erciyes University, 38039 Kayseri (Turkey); Keskin, Mustafa [Department of Physics, Erciyes University, 38039 Kayseri (Turkey)]. E-mail: keskin@erciyes.edu.tr

    2006-06-15

    We have studied the antiferromagnetic Blume-Emery-Griffiths model with the repulsive biquadratic coupling in an external magnetic field using the lowest approximation of the cluster variation method which is identical to the mean-field approximation. First, we have investigated the thermal variations of the sublattice magnetizations and obtained four different main topological types. Then, we have calculated the phase diagrams and five main different phase diagram topologies are found. Finally, the discussion and comparison of the phase diagrams are made.

  13. Quality Assurance in University Guidance Services

    Science.gov (United States)

    Simon, Alexandra

    2014-01-01

    In Europe there is no common quality assurance framework for the delivery of guidance in higher education. Using a case study approach in four university career guidance services in England, France and Spain, this article aims to study how quality is implemented in university career guidance services in terms of strategy, standards and models,…

  14. Providing Career Guidance for Young Women.

    Science.gov (United States)

    Colby, Pamela G.

    This module is directed at personnel working or planning to work in the areas of guidance, counseling, placement and follow-through in junior and senior high school settings, grades 7-12. The module topic is career guidance for young women of junior and senior high school age, aand the focus will be on providing nonbiased career guidance which…

  15. Radionuclide Data Quality Evaluation Guidance

    International Nuclear Information System (INIS)

    Tucker, B.J.; Winters, M.S.; Evans, D.

    2009-01-01

    A considerable amount of radioanalytical data is generated during various phases of the characterization and remediation of radiologically-contaminated sites and properties. It is critical that data generated from the analysis of collected samples be to a level of quality usable by the project and acceptable to stakeholders. In July 2004, the final version of a multi-agency guidance manual entitled Multi-Agency Radiological Analytical Protocols Manual (MARLAP) was issued by the Environmental Protection Agency, Department of Energy, Department of Homeland Security, Nuclear Regulatory Commission, Department of Defense, National Institute of Standards and Technology, U. S. Geological Survey, Food and Drug Administration, and the States of Kentucky and California. The authors' purpose is to introduce readers to some key elements of MARLAP as it relates to radioanalytical lab quality control, and to demonstrate how these guidance elements can be effectively incorporated into mature radioanalytical lab operations and data validation regimes. Based upon the logic and statistical methodologies presented in MARLAP, the authors have revised existing project-specific Radioanalytical Data Evaluation Guidance (RadDEG) used at the FUSRAP Maywood Site in Maywood, NJ. The RadDEG allows users to qualify data in a meaningful way by tying the usability of the data to its activity and uncertainty relative to project action levels and QC results. This exercise may be useful to other projects looking to implement a MARLAP-based approach into their project/site-specific data evaluation methodologies. (authors)

  16. Study of a model Fermi liquid interacting via a hard-core repulsive potential and an attractive tail

    International Nuclear Information System (INIS)

    Ng, Tai Kai; Singwi, K.S.

    1986-02-01

    In this paper we present an extensive microscopic study of the collective and single-particle properties of a model Fermi liquid whose particles interact via a repulsive hard-core potential and an attractive tail. The model system is intended to simulate liquid 3 He. The study is based on an approximate scheme of Singwi, Tosi, Land and Sjoelander (STLS) which was devised to treat correlations in Coulomb Fermi liquids. The primary aim of this study is to learn whether the model system is capable of reproducing some of the salient features observed in normal liquid 3 He, and about the role of the repulsive and attractive parts of the potential. We have calculated the Landau parameters F 0 /sup s/ and F 0 /sup a/ and their variation with pressure, the wave number and pressure dependence of the spin-symmetric and spin-anti-symmetric polarization potentials, pressure dependence of the dispersion of the zero sound, the static structure factors and the quasiparticle mass. Although we make no quantitative claims when comparing our calculations with experiments in real liquid 3 He, we do conclude that our model system within the framework of the STLS scheme can account qualitatively for the latter. Besides, since the theory is microscopic in nature and is parameter free, it has enabled us to understand better the role of the repulsive and the attractive parts of the bare potential in determining the properties of liquid 3 He. 27 figs., 2 tabs

  17. The status of molecules

    International Nuclear Information System (INIS)

    Barnes, T.; Oak Ridge National Lab., TN; Tennessee Univ., Knoxville, TN

    1994-06-01

    This report summarizes the experimental and theoretical status of hadronic molecules, which are weakly-bound states of two or more hadrons. We begin with a brief history of the subject and discuss a few good candidates, and then abstract some signatures for molecules which may be of interest in the classification of possible molecule states. Next we argue that a more general understanding of 2 → 2 hadron-hadron scattering amplitudes will be crucial for molecule searches, and discuss some of our recent work in this area. We conclude with a discussion of a few more recent molecule candidates (notably the f o (1710)) which are not well established as molecules but satisfy some of the expected signatures. (Author)

  18. Optimization and transferability of non-electrostatic repulsion in the polarizable density embedding model

    DEFF Research Database (Denmark)

    Hrsak, Dalibor; Olsen, Jógvan Magnus Haugaard; Kongsted, Jacob

    2017-01-01

    Embedding techniques in combination with response theory represent a successful approach to calculate molecular properties and excited states in large molecular systems such as solutions and proteins. Recently, the polarizable embedding model has been extended by introducing explicit electronic...... densities of the molecules in the nearest environment, resulting in the polarizable density embedding (PDE) model. This improvement provides a better description of the intermolecular interactions at short distances. However, the electronic densities of the environment molecules are calculated in isolation...... interaction energies calculated on the basis of full quantum-mechanical calculations. The obtained optimal factors are used in PDE calculations of various ground- and excited-state properties of molecules embedded in solvents described as polarizable environments. © 2017 Wiley Periodicals, Inc....

  19. Cold Rydberg molecules

    Science.gov (United States)

    Raithel, Georg; Zhao, Jianming

    2017-04-01

    Cold atomic systems have opened new frontiers at the interface of atomic and molecular physics. These include research on novel types of Rydberg molecules. Three types of molecules will be reviewed. Long-range, homonuclear Rydberg molecules, first predicted in [1] and observed in [2], are formed via low-energy electron scattering of the Rydberg electron from a ground-state atom within the Rydberg atom's volume. The binding mostly arises from S- and P-wave triplet scattering. We use a Fermi model that includes S-wave and P-wave singlet and triplet scattering, the fine structure coupling of the Rydberg atom and the hyperfine structure coupling of the 5S1/2 atom (in rubidium [3]). The hyperfine structure gives rise to mixed singlet-triplet potentials for both low-L and high-L Rydberg molecules [3]. A classification into Hund's cases [3, 4, 5] will be discussed. The talk further includes results on adiabatic potentials and adiabatic states of Rydberg-Rydberg molecules in Rb and Cs. These molecules, which have even larger bonding length than Rydberg-ground molecules, are formed via electrostatic multipole interactions. The leading interaction term of neutral Rydberg-Rydberg molecules is between two dipoles, while for ionic Rydberg molecules it is between a dipole and a monopole. NSF (PHY-1506093), NNSF of China (61475123).

  20. The Hedgehog Signalling Pathway in Cell Migration and Guidance: What We Have Learned from Drosophila melanogaster

    Directory of Open Access Journals (Sweden)

    Sofia J. Araújo

    2015-10-01

    Full Text Available Cell migration and guidance are complex processes required for morphogenesis, the formation of tumor metastases, and the progression of human cancer. During migration, guidance molecules induce cell directionality and movement through complex intracellular mechanisms. Expression of these molecules has to be tightly regulated and their signals properly interpreted by the receiving cells so as to ensure correct navigation. This molecular control is fundamental for both normal morphogenesis and human disease. The Hedgehog (Hh signaling pathway is evolutionarily conserved and known to be crucial for normal cellular growth and differentiation throughout the animal kingdom. The relevance of Hh signaling for human disease is emphasized by its activation in many cancers. Here, I review the current knowledge regarding the involvement of the Hh pathway in cell migration and guidance during Drosophila development and discuss its implications for human cancer origin and progression.

  1. Ensemble averaged coherent state path integral for disordered bosons with a repulsive interaction (Derivation of mean field equations)

    International Nuclear Information System (INIS)

    Mieck, B.

    2007-01-01

    We consider bosonic atoms with a repulsive contact interaction in a trap potential for a Bose-Einstein condensation (BEC) and additionally include a random potential. The ensemble averages for two models of static (I) and dynamic (II) disorder are performed and investigated in parallel. The bosonic many body systems of the two disorder models are represented by coherent state path integrals on the Keldysh time contour which allow exact ensemble averages for zero and finite temperatures. These ensemble averages of coherent state path integrals therefore present alternatives to replica field theories or super-symmetric averaging techniques. Hubbard-Stratonovich transformations (HST) lead to two corresponding self-energies for the hermitian repulsive interaction and for the non-hermitian disorder-interaction. The self-energy of the repulsive interaction is absorbed by a shift into the disorder-self-energy which comprises as an element of a larger symplectic Lie algebra sp(4M) the self-energy of the repulsive interaction as a subalgebra (which is equivalent to the direct product of M x sp(2); 'M' is the number of discrete time intervals of the disorder-self-energy in the generating function). After removal of the remaining Gaussian integral for the self-energy of the repulsive interaction, the first order variations of the coherent state path integrals result in the exact mean field or saddle point equations, solely depending on the disorder-self-energy matrix. These equations can be solved by continued fractions and are reminiscent to the 'Nambu-Gorkov' Green function formalism in superconductivity because anomalous terms or pair condensates of the bosonic atoms are also included into the selfenergies. The derived mean field equations of the models with static (I) and dynamic (II) disorder are particularly applicable for BEC in d=3 spatial dimensions because of the singularity of the density of states at vanishing wavevector. However, one usually starts out from

  2. Reactive scattering of electronically excited alkali atoms with molecules

    International Nuclear Information System (INIS)

    Mestdagh, J.M.; Balko, B.A.; Covinsky, M.H.; Weiss, P.S.; Vernon, M.F.; Schmidt, H.; Lee, Y.T.

    1987-06-01

    Representative families of excited alkali atom reactions have been studied using a crossed beam apparatus. For those alkali-molecule systems in which reactions are also known for ground state alkali and involve an early electron transfer step, no large differences are observed in the reactivity as Na is excited. More interesting are the reactions with hydrogen halides (HCl): it was found that adding electronic energy into Na changes the reaction mechanism. Early electron transfer is responsible of Na(5S, 4D) reactions, but not of Na(3P) reactions. Moreover, the NaCl product scattering is dominated by the HCl - repulsion in Na(5S, 4D) reactions, and by the NaCl-H repulsion in the case of Na(3P). The reaction of Na with O 2 is of particular interest since it was found to be state specific. Only Na(4D) reacts, and the reaction requires restrictive constraints on the impact parameter and the reactants' relative orientation. The reaction with NO 2 is even more complex since Na(4D) leads to the formation of NaO by two different pathways. It must be mentioned however, that the identification of NaO as product in these reactions has yet to be confirmed

  3. Effects of laminin blended with chitosan on axon guidance on patterned substrates

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, N; Guan, Y J; Chen, X B [Division of Biomedical Engineering, University of Saskatchewan, Saskatoon S7N 5A9 (Canada); Li, M G [Department of Mechanical Engineering, University of Saskatchewan, Saskatoon S7N 5A9 (Canada); Schreyer, D J, E-mail: niz504@mail.usask.c [Department of Anatomy and Cell Biology, Cameco MS Neuroscience Research Center, University of Saskatchewan, Saskatoon, S7K 0M7 (Canada)

    2010-12-15

    Axon guidance is a crucial consideration in the design of tissue scaffolds used to promote nerve regeneration. Here we investigate the combined use of laminin (a putative axon adhesion and guidance molecule) and chitosan (a leading candidate base material for the construction of scaffolds) for promoting axon guidance in cultured adult dorsal root ganglion (DRG) neurons. Using a dispensing-based rapid prototyping (DBRP) technique, two-dimensional grid patterns were created by dispensing chitosan or laminin-blended chitosan substrate strands oriented in orthogonal directions. In vitro experiments illustrated DRG neurites on these patterns preferentially grew upon and followed the laminin-blended chitosan pathways. These results suggest that an orientation of neurite growth can be achieved in an artificially patterned substrate by creating selectively biofunctional pathways. The DBRP technique may provide improved strategies for the use of biofunctional pathways in the design of three-dimensional scaffolds for guidance of nerve repair.

  4. Effects of laminin blended with chitosan on axon guidance on patterned substrates

    International Nuclear Information System (INIS)

    Zhu, N; Guan, Y J; Chen, X B; Li, M G; Schreyer, D J

    2010-01-01

    Axon guidance is a crucial consideration in the design of tissue scaffolds used to promote nerve regeneration. Here we investigate the combined use of laminin (a putative axon adhesion and guidance molecule) and chitosan (a leading candidate base material for the construction of scaffolds) for promoting axon guidance in cultured adult dorsal root ganglion (DRG) neurons. Using a dispensing-based rapid prototyping (DBRP) technique, two-dimensional grid patterns were created by dispensing chitosan or laminin-blended chitosan substrate strands oriented in orthogonal directions. In vitro experiments illustrated DRG neurites on these patterns preferentially grew upon and followed the laminin-blended chitosan pathways. These results suggest that an orientation of neurite growth can be achieved in an artificially patterned substrate by creating selectively biofunctional pathways. The DBRP technique may provide improved strategies for the use of biofunctional pathways in the design of three-dimensional scaffolds for guidance of nerve repair.

  5. 78 FR 4848 - Social Media: Consumer Compliance Risk Management Guidance

    Science.gov (United States)

    2013-01-23

    ...: Consumer Compliance Risk Management Guidance AGENCY: Federal Financial Institutions Examination Council... Media: Consumer Compliance Risk Management Guidance'' (guidance). Upon completion of the guidance, and... management practices adequately address the consumer compliance and legal risks, as well as related risks...

  6. Probing Intranuclear Environments at the Single-Molecule Level

    Science.gov (United States)

    Grünwald, David; Martin, Robert M.; Buschmann, Volker; Bazett-Jones, David P.; Leonhardt, Heinrich; Kubitscheck, Ulrich; Cardoso, M. Cristina

    2008-01-01

    Genome activity and nuclear metabolism clearly depend on accessibility, but it is not known whether and to what extent nuclear structures limit the mobility and access of individual molecules. We used fluorescently labeled streptavidin with a nuclear localization signal as an average-sized, inert protein to probe the nuclear environment. The protein was injected into the cytoplasm of mouse cells, and single molecules were tracked in the nucleus with high-speed fluorescence microscopy. We analyzed and compared the mobility of single streptavidin molecules in structurally and functionally distinct nuclear compartments of living cells. Our results indicated that all nuclear subcompartments were easily and similarly accessible for such an average-sized protein, and even condensed heterochromatin neither excluded single molecules nor impeded their passage. The only significant difference was a higher frequency of transient trappings in heterochromatin, which lasted only tens of milliseconds. The streptavidin molecules, however, did not accumulate in heterochromatin, suggesting comparatively less free volume. Interestingly, the nucleolus seemed to exclude streptavidin, as it did many other nuclear proteins, when visualized by conventional fluorescence microscopy. The tracking of single molecules, nonetheless, showed no evidence for repulsion at the border but relatively unimpeded passage through the nucleolus. These results clearly show that single-molecule tracking can provide novel insights into mobility of proteins in the nucleus that cannot be obtained by conventional fluorescence microscopy. Our results suggest that nuclear processes may not be regulated at the level of physical accessibility but rather by local concentration of reactants and availability of binding sites. PMID:18065482

  7. Comment on ;Acceleration of particles to high energy via gravitational repulsion in the Schwarzschild field; [Astropart. Phys. 86 (2017) 18-20

    Science.gov (United States)

    Spallicci, Alessandro D. A. M.

    2017-09-01

    Comments are due on a recent paper by McGruder III (2017) in which the author deals with the concept of gravitational repulsion in the context of the Schwarzschild-Droste solution. Repulsion (deceleration) for ingoing particles into a black hole is a concept proposed several times starting from Droste himself in 1916. It is a coordinate effect appearing to an observer at a remote distance from the black hole and when coordinate time is employed. Repulsion has no bearing and relation to the local physics of the black hole, and moreover it cannot be held responsible for accelerating outgoing particles. Thereby, the energy boost of cosmic rays cannot be produced by repulsion.

  8. Molecule of the Month

    Indian Academy of Sciences (India)

    Atoms in a molecule generally prefer, particularly among the neighbouring ones, certain optimmn geometrical relationships. These are manifested in specific ranges of bond lengths, bond angles, torsion angles etc. As it always happens, chemists are interested in making molecules where these 'standard relationships' are ...

  9. Molecule of the Month

    Indian Academy of Sciences (India)

    Cyclo bu tadiene (1) has been one of the most popular molecules for experimentalists and theoreticians. This molecule is unstable as . it is antiaromatic ( 4,n electrons in a cyclic array). Even though some highly substituted cyclobutadienes, for example, compound 2 and the Fe(CO)3 complex of cyclobutadiene (3) are ...

  10. Single-Molecule Spectroscopy

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 20; Issue 2. Single-Molecule Spectroscopy: Every Molecule is Different! Kankan Bhattacharyya. General Article Volume 20 Issue 2 February 2015 pp 151-164. Fulltext. Click here to view fulltext PDF. Permanent link:

  11. Single molecule conductance

    NARCIS (Netherlands)

    Willems, R.

    2008-01-01

    This thesis represents an excursion into the world of molecular electronics, i.e. the field of research trying to use individual (organic) molecules as electronic components; in this work various experimental methods have been explored to connect individual molecules to metallic contacts and

  12. Molecules in stars

    International Nuclear Information System (INIS)

    Tsuji, T.

    1986-01-01

    Recently, research related to molecules in stars has rapidly expanded because of progress in related fields. For this reason, it is almost impossible to cover all the topics related to molecules in stars. Thus, here the authors focus their attention on molecules in the atmospheres of cool stars and do not cover in any detail topics related to circumstellar molecules originating from expanding envelopes located far from the stellar surface. However, the authors do discuss molecules in quasi-static circumstellar envelopes (a recently discovered new component of circumstellar envelopes) located near the stellar surface, since molecular lines originating from such envelopes show little velocity shift relative to photospheric lines, and hence they directly affect the interpretation and analysis of stellar spectra

  13. Tuning cell adhesion by direct nanostructuring silicon into cell repulsive/adhesive patterns

    International Nuclear Information System (INIS)

    Premnath, Priyatha; Tavangar, Amirhossein; Tan, Bo; Venkatakrishnan, Krishnan

    2015-01-01

    Developing platforms that allow tuning cell functionality through incorporating physical, chemical, or mechanical cues onto the material surfaces is one of the key challenges in research in the field of biomaterials. In this respect, various approaches have been proposed and numerous structures have been developed on a variety of materials. Most of these approaches, however, demand a multistep process or post-chemical treatment. Therefore, a simple approach would be desirable to develop bio-functionalized platforms for effectively modulating cell adhesion and consequently programming cell functionality without requiring any chemical or biological surface treatment. This study introduces a versatile yet simple laser approach to structure silicon (Si) chips into cytophobic/cytophilic patterns in order to modulate cell adhesion and proliferation. These patterns are fabricated on platforms through direct laser processing of Si substrates, which renders a desired computer-generated configuration into patterns. We investigate the morphology, chemistry, and wettability of the platform surfaces. Subsequently, we study the functionality of the fabricated platforms on modulating cervical cancer cells (HeLa) behaviour. The results from in vitro studies suggest that the nanostructures efficiently repel HeLa cells and drive them to migrate onto untreated sites. The study of the morphology of the cells reveals that cells evade the cytophobic area by bending and changing direction. Additionally, cell patterning, cell directionality, cell channelling, and cell trapping are achieved by developing different platforms with specific patterns. The flexibility and controllability of this approach to effectively structure Si substrates to cell-repulsive and cell-adhesive patterns offer perceptible outlook for developing bio-functionalized platforms for a variety of biomedical devices. Moreover, this approach could pave the way for developing anti-cancer platforms that selectively repel

  14. Tuning cell adhesion by direct nanostructuring silicon into cell repulsive/adhesive patterns

    Energy Technology Data Exchange (ETDEWEB)

    Premnath, Priyatha, E-mail: priyatha.premnath@ryerson.ca [Micro/Nanofabrication Laboratory, Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, ON, Canada M5B 2K3 (Canada); Tavangar, Amirhossein, E-mail: atavanga@ryerson.ca [Micro/Nanofabrication Laboratory, Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, ON, Canada M5B 2K3 (Canada); Tan, Bo, E-mail: tanbo@ryerson.ca [Nanocharacterization Laboratory, Department of Aerospace Engineering, Ryerson University, 350 Victoria Street, Toronto, ON, Canada M5B 2K3 (Canada); Venkatakrishnan, Krishnan, E-mail: venkat@ryerson.ca [Micro/Nanofabrication Laboratory, Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, ON, Canada M5B 2K3 (Canada)

    2015-09-10

    Developing platforms that allow tuning cell functionality through incorporating physical, chemical, or mechanical cues onto the material surfaces is one of the key challenges in research in the field of biomaterials. In this respect, various approaches have been proposed and numerous structures have been developed on a variety of materials. Most of these approaches, however, demand a multistep process or post-chemical treatment. Therefore, a simple approach would be desirable to develop bio-functionalized platforms for effectively modulating cell adhesion and consequently programming cell functionality without requiring any chemical or biological surface treatment. This study introduces a versatile yet simple laser approach to structure silicon (Si) chips into cytophobic/cytophilic patterns in order to modulate cell adhesion and proliferation. These patterns are fabricated on platforms through direct laser processing of Si substrates, which renders a desired computer-generated configuration into patterns. We investigate the morphology, chemistry, and wettability of the platform surfaces. Subsequently, we study the functionality of the fabricated platforms on modulating cervical cancer cells (HeLa) behaviour. The results from in vitro studies suggest that the nanostructures efficiently repel HeLa cells and drive them to migrate onto untreated sites. The study of the morphology of the cells reveals that cells evade the cytophobic area by bending and changing direction. Additionally, cell patterning, cell directionality, cell channelling, and cell trapping are achieved by developing different platforms with specific patterns. The flexibility and controllability of this approach to effectively structure Si substrates to cell-repulsive and cell-adhesive patterns offer perceptible outlook for developing bio-functionalized platforms for a variety of biomedical devices. Moreover, this approach could pave the way for developing anti-cancer platforms that selectively repel

  15. Guidance on accidents involving radioactivity

    International Nuclear Information System (INIS)

    1989-01-01

    This annex contains advice to Health Authorities on their response to accidents involving radioactivity. The guidance is in six parts:-(1) planning the response required to nuclear accidents overseas, (2) planning the response required to UK nuclear accidents a) emergency plans for nuclear installations b) nuclear powered satellites, (3) the handling of casualties contaminated with radioactive substances, (4) background information for dealing with queries from the public in the event of an accident, (5) the national arrangements for incident involving radioactivity (NAIR), (6) administrative arrangements. (author)

  16. Advantages of computed tomographic guidance

    International Nuclear Information System (INIS)

    Casola, G.; Vansonnenberg, E.

    1987-01-01

    Both ultrasound and CT are successfully used to guide interventional procedures throughout the body. There are advantages and disadvantages to each modality and choosing one over the other will vary from case to case. Major factors influencing choice are discussed in this paper. As a general rule CT guidance is usually required for lesions in the thorax, the adrenals, the pancreas, lymph nodes, and for percutaneous abscess drainage. The authors feel that a complimentary use of ultrasound and CT is essential to optimize success and cost-effectiveness; therefore, the interventional radiologist should be familiar with both imaging modalities

  17. Agent Based Individual Traffic guidance

    DEFF Research Database (Denmark)

    Wanscher, Jørgen Bundgaard

    2004-01-01

    When working with traffic planning or guidance it is common practice to view the vehicles as a combined mass. >From this models are employed to specify the vehicle supply and demand for each region. As the models are complex and the calculations are equally demanding the regions and the detail...... of the road network is aggregated. As a result the calculations reveal only what the mass of vehicles are doing and not what a single vehicle is doing. This is the crucial difference to ABIT (Agent Based Individual Trafficguidance). ABIT is based on the fact that information on the destination of each vehicle...

  18. Ecological Restoration: Guidance from Theory

    Directory of Open Access Journals (Sweden)

    Joy Zedler

    2005-09-01

    Full Text Available A review of the science and practice of ecosystem restoration led me to identify key ecological theories and concepts that are relevant to planning, implementing, and sustaining restoration efforts. From experience with actual restoration projects, I provide guidance for improving the restoration process. Despite an abundance of theory and guidance, restoration goals are not always achieved, and pathways toward targets are not highly predictable. This is understandable, since each restoration project has many constraints and unique challenges. To improve restoration progress, I advise that sites be designed as experiments to allow learning while doing. At least the larger projects can be restored in phases, each designed as experimental treatments to test alternative restoration approaches. Subsequent phases can then adopt one or more of the treatments that best achieved goals in earlier phases while applying new tests of other restoration measures. Both science and restoration can progress simultaneously. This phased, experimental approach (called “adaptive restoration” is an effective tool for improving restoration when monitoring, assessment, interpretation and research are integrated into the process.

  19. Laser guidance of mesoscale particles

    Science.gov (United States)

    Underdown, Frank Hartman, Jr.

    Mesoscale particles are guided and trapped in hollow optical fibers using radiation pressure forces. Laser light from a 0.4W, 780nm diode laser is guided in a low- loss fiber mode and used to generate the guidance forces. Laser scattering and absorption forces propels particles along the fiber and polarization gradient forces attract them to the fiber's axial center. Using two counter propagating laser beams, inside the fiber, particles can be trapped in three dimensions. Measuring the spring constant of the trap gives the gradient force. This dissertation describes Rayleigh and Mie scattering models for calculating guidance forces. Calculated forces as a function of particle size and composition (i.e. dielectric, semiconductor, and metals) will be presented. For example, under typical experimental conditions 100nm Au particles are guided by a 2 × 10-14 N propulsive force in a water filled fiber. In comparison, the measured force, obtained from the particle's velocity and Stokes' law, is 7.98 × 10-14 N.

  20. Dynamics of Activated Molecules

    Energy Technology Data Exchange (ETDEWEB)

    Mullin, Amy S. [Univ. of Maryland, College Park, MD (United States)

    2016-11-16

    Experimental studies have been performed to investigate the collisional energy transfer processes of gas-phase molecules that contain large amounts of internal energy. Such molecules are prototypes for molecules under high temperature conditions relevant in combustion and information about their energy transfer mechanisms is needed for a detailed understanding and modeling of the chemistry. We use high resolution transient IR absorption spectroscopy to measure the full, nascent product distributions for collisions of small bath molecules that relax highly vibrationally excited pyrazine molecules with E=38000 cm-1 of vibrational energy. To perform these studies, we developed new instrumentation based on modern IR light sources to expand our experimental capabilities to investigate new molecules as collision partners. This final report describes our research in four areas: the characterization of a new transient absorption spectrometer and the results of state-resolved collision studies of pyrazine(E) with HCl, methane and ammonia. Through this research we have gained fundamental new insights into the microscopic details of relatively large complex molecules at high energy as they undergo quenching collisions and redistribute their energy.

  1. Dissociation in small molecules

    International Nuclear Information System (INIS)

    Dehmer, P.M.

    1982-01-01

    The study of molecular dissociation processes is one of the most interesting areas of modern spectroscopy owing to the challenges presented bt even the simplest of diatomic molecules. This paper reviews the commonly used descriptions of molecular dissociation processes for diatomic molecules, the selection rules for predissociation, and a few of the principles to be remembered when one is forced to speculate about dissociation mechanisms in a new molecule. Some of these points will be illustrated by the example of dissociative ionization in O 2

  2. A study on interaction of DNA molecules and carbon nanotubes for an effective ejection of the molecules

    International Nuclear Information System (INIS)

    Wu, N.; Wang, Q.

    2012-01-01

    The ejection of DNA molecules from carbon nanotubes is reported from interaction energy perspectives by molecular dynamics simulations. The critical ejection energy, which is to be applied to a DNA molecule for a successful ejection from a carbon nanotube, is investigated based on a study on the friction and binding energy between the DNA molecule and the tube. An effective ejection is realized by subjecting a kinetic energy on the DNA molecule that is larger than the solved critical ejection energy. In addition, the relationship between ejection energies and sizes of DNA molecules and carbon nanotubes is investigated. -- Highlights: ► Report the ejection of DNA molecules from CNTs from interaction energy perspectives. ► Develop a methodology for the critical energy of an effective ejection of a DNA molecule from a CNT. ► Present the relationship between critical ejection energies and sizes of DNA molecules and CNTs. ► Provide a general guidance on the ejection of encapsulated molecules from CNTs.

  3. Single molecules and nanotechnology

    CERN Document Server

    Vogel, Horst

    2007-01-01

    This book focuses on recent advances in the rapidly evolving field of single molecule research. These advances are of importance for the investigation of biopolymers and cellular biochemical reactions, and are essential to the development of quantitative biology. Written by leading experts in the field, the articles cover a broad range of topics, including: quantum photonics of organic dyes and inorganic nanoparticles their use in detecting properties of single molecules the monitoring of single molecule (enzymatic) reactions single protein (un)folding in nanometer-sized confined volumes the dynamics of molecular interactions in biological cells The book is written for advanced students and scientists who wish to survey the concepts, techniques and results of single molecule research and assess them for their own scientific activities.

  4. Electron-molecule collisions

    CERN Document Server

    Takayanagi, Kazuo

    1984-01-01

    Scattering phenomena play an important role in modern physics. Many significant discoveries have been made through collision experiments. Amongst diverse kinds of collision systems, this book sheds light on the collision of an electron with a molecule. The electron-molecule collision provides a basic scattering problem. It is scattering by a nonspherical, multicentered composite particle with its centers having degrees of freedom of motion. The molecule can even disintegrate, Le., dissociate or ionize into fragments, some or all of which may also be molecules. Although it is a difficult problem, the recent theoretical, experimental, and computational progress has been so significant as to warrant publication of a book that specializes in this field. The progress owes partly to technical develop­ ments in measurements and computations. No less important has been the great and continuing stimulus from such fields of application as astrophysics, the physics of the earth's upper atmosphere, laser physics, radiat...

  5. Molecules to Materials

    Indian Academy of Sciences (India)

    evolved as a new line of thinking wherein a single molecule or perhaps a collection .... In photonic communication processes, laser light has to be modulated and .... The author wishes to thank G Rajaram for a critical reading of the manuscript.

  6. Single-Molecule Spectroscopy

    Indian Academy of Sciences (India)

    IAS Admin

    overall absorption spectrum of a molecule is a superposition of many such sharp lines .... dilute solution of the enzyme and the substrate over few drops of silicone oil placed ..... Near-field Scanning Optical Microscopy (NSOM): Development.

  7. Quantum dot molecules

    CERN Document Server

    Wu, Jiang

    2014-01-01

    This book reviews recent advances in the exciting and rapidly growing field of quantum dot molecules (QDMs). It offers state-of-the-art coverage of novel techniques and connects fundamental physical properties with device design.

  8. Molecule of the Month

    Indian Academy of Sciences (India)

    Molecule of the Month - Adamantane - A Plastic Piece of Diamond. J Chandrasekhar. Volume 16 Issue 12 ... Keywords. Adamantane; diamondoid systems; plastic crystals. ... Resonance – Journal of Science Education | News. © 2017 Indian ...

  9. Health Service use of ionising radiations: Guidance

    International Nuclear Information System (INIS)

    1995-01-01

    This booklet gives outline guidance on the use of ionising radiations in the Health Service in the United Kingdom. Extensive reference is made to documents where more detailed information may be found. The guidance covers general advice on the medical use of ionising radiations, statutory requirements, and guidance on selected Health Service issues such as patient identification procedures, information management systems, deviations from prescribed radiation dose, imaging and radiotherapy. (57 references) (U.K.)

  10. A renormalization-group analysis of a spin-1 Ising ferromagnet with competing crystal-field and repulsive biquadratic interactions

    International Nuclear Information System (INIS)

    Snowman, Daniel P.

    2009-01-01

    Phase diagrams have been produced and critical exponents calculated for a Blume-Emery-Griffiths system with competing biquadratic and crystal-field interactions with uniform ferromagnetic bilinear interactions. This competition directly effects the clustering and density of nonmagnetic impurities. These results have been produced using renormalization-group methods with a hierarchical lattice. A series of planes of constant, repulsive biquadratic coupling have been probed while varying the temperature and concentration of annealed vacancies in the system. The sinks have been analyzed and interpreted, and critical exponents calculated for the higher order transitions.

  11. Cell adhesion and growth enabled by biomimetic oligopeptide modification of a polydopamine-poly(ethylene oxide) protein repulsive surface

    Czech Academy of Sciences Publication Activity Database

    Musílková, Jana; Kotelnikov, Ilya; Novotná, Katarína; Pop-Georgievski, Ognen; Rypáček, František; Bačáková, Lucie; Proks, Vladimír

    2015-01-01

    Roč. 26, č. 11 (2015), s. 253 ISSN 0957-4530 R&D Projects: GA ČR(CZ) GAP108/11/1857; GA ČR(CZ) GAP108/12/1168; GA MŠk(CZ) EE2.3.30.0029; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:67985823 ; RVO:61389013 Keywords : protein repulsive surface * cell adhesion * RGD * endothelial cells Subject RIV: EI - Biotechnology ; Bionics; CD - Macromolecular Chemistry (UMCH-V) Impact factor: 2.272, year: 2015

  12. ICRP guidance on radioactive waste disposal

    International Nuclear Information System (INIS)

    Cooper, J.R.

    2002-01-01

    The International Commission on Radiological Protection (ICRP) issued recommendations for a system of radiological protection in 1991 as the 1990 Recommendations. Guidance on the application of these recommendations in the general area of waste disposal was issued in 1997 as Publication 77 and guidance specific to disposal of solid long-lived radioactive waste was issued as Publication 81. This paper summarises ICRP guidance in radiological protection requirements for waste disposal concentrating on the ones of relevance to the geological disposal of solid radioactive waste. Suggestions are made for areas where further work is required to apply the ICRP guidance. (author)

  13. Curly arrows meet electron density transfers in chemical reaction mechanisms: from electron localization function (ELF) analysis to valence-shell electron-pair repulsion (VSEPR) inspired interpretation.

    Science.gov (United States)

    Andrés, Juan; Berski, Sławomir; Silvi, Bernard

    2016-07-07

    Probing the electron density transfers during a chemical reaction can provide important insights, making possible to understand and control chemical reactions. This aim has required extensions of the relationships between the traditional chemical concepts and the quantum mechanical ones. The present work examines the detailed chemical insights that have been generated through 100 years of work worldwide on G. N. Lewis's ground breaking paper on The Atom and the Molecule (Lewis, G. N. The Atom and the Molecule, J. Am. Chem. Soc. 1916, 38, 762-785), with a focus on how the determination of reaction mechanisms can be reached applying the bonding evolution theory (BET), emphasizing how curly arrows meet electron density transfers in chemical reaction mechanisms and how the Lewis structure can be recovered. BET that combines the topological analysis of the electron localization function (ELF) and Thom's catastrophe theory (CT) provides a powerful tool providing insight into molecular mechanisms of chemical rearrangements. In agreement with physical laws and quantum theoretical insights, BET can be considered as an appropriate tool to tackle chemical reactivity with a wide range of possible applications. Likewise, the present approach retrieves the classical curly arrows used to describe the rearrangements of chemical bonds for a given reaction mechanism, providing detailed physical grounds for this type of representation. The ideas underlying the valence-shell-electron pair-repulsion (VSEPR) model applied to non-equilibrium geometries provide simple chemical explanations of density transfers. For a given geometry around a central atom, the arrangement of the electronic domain may comply or not with the VSEPR rules according with the valence shell population of the considered atom. A deformation yields arrangements which are either VSEPR defective (at least a domain is missing to match the VSEPR arrangement corresponding to the geometry of the ligands), VSEPR compliant

  14. Manipulating individual dichlorotin phthalocyanine molecules on Cu(100) surface at room temperature by scanning tunneling microscopy

    International Nuclear Information System (INIS)

    Li, Chao; Xiang, Feifei; Wang, Zhongping; Liu, Xiaoqing; Jiang, Danfeng; Wang, Li; Wang, Guang; Zhang, Xueao; Chen, Wei

    2014-01-01

    Single molecule manipulations have been achieved on dichlorotin phthalocyanine(SnCl 2 Pc) molecules adsorbed on Cu (100) at room temperature. Scanning tunneling microscopy observations directly demonstrate that the individual SnCl 2 Pc molecules can be moved along the [100] direction on Cu(100) surface by employing a scanning tunneling microscope tip fixed at the special position of the molecules. The orientation of the molecule can be switched between two angles of ±28° with respect to the [011] surface direction in the same way. Dependences of the probability of molecular motion on the distances between the tip and the molecules reveal that the mechanism for such manipulation of a SnCl 2 Pc molecule is dominated by the repulsive interactions between the tip and the molecules. With the assistance of this manipulation process, a prototype molecular storage array with molecular orientation as information carrier and an artificial hydrogen bonded supramolecular structure have been constructed on the surface. (paper)

  15. Widening opportunities for career guidance

    DEFF Research Database (Denmark)

    Poulsen, Bo Klindt; Skovhus, Randi Boelskifte; Thomsen, Rie

    2017-01-01

    This chapter discusses research circles as a way of organising collaboration between career guidance researchers and practitioners. Such collaboration, it is argued, helps resist neoliberal governance mechanisms and supports social justice perspectives among teachers involved in the provision...... of career education in Danish schools. Based on a research and development project on career education, case analysis is used to explore research circles as a means for collaboration between researchers and practitioners. This analysis shows that research circles provide teachers with a space to reflect...... both in and on action. Career education is the key focus of the case presented in this chapter and it is argued that, in order to increase social mobility through education, there is a need to widen opportunities through experience-based activities among pupils in Danish schools. The chapter contends...

  16. Widening opportunities for career guidance

    DEFF Research Database (Denmark)

    Poulsen, Bo Klindt; Skovhus, Randi Boelskifte; Thomsen, Rie

    2018-01-01

    This chapter discusses research circles as a way of organising collaboration between career guidance researchers and practitioners. Such collaboration, it is argued, helps resist neoliberal governance mechanisms and supports social justice perspectives among teachers involved in the provision...... of career education in Danish schools. Based on a research and development project on career education, case analysis is used to explore research circles as a means for collaboration between researchers and practitioners. This analysis shows that research circles provide teachers with a space to reflect...... both in and on action. Career education is the key focus of the case presented in this chapter and it is argued that, in order to increase social mobility through education, there is a need to widen opportunities through experience-based activities among pupils in Danish schools. The chapter contends...

  17. The inelastic scattering of 2Pi [case (b)] molecules and an understanding of the differing Λ doublet propensities for molecules of π vs π3 orbital occupancy

    International Nuclear Information System (INIS)

    Dagdigian, P.J.; Alexander, M.H.; Liu, K.; Department of Chemistry, University of Maryland, College Park, Maryland 20742; Gas Phase Chemical Dynamics Group, Chemistry Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439)

    1989-01-01

    The quantum formalism for the scattering of a diatomic molecule in a 2 Pi electronic state which is well described by Hund's case (b) limit is investigated here. For a particular JF/sub i/ yields J'F'/sub 1/ transition, quantum interference effects will lead to preferential population of one of the final state Λ doublet levels. The nonstatistical population of final state Λ doublet levels arises from an interference between terms in the expansion of the two electrostatic potential energy surfaces, of A' and A'' reflection symmetry, which describe the interaction between a molecule in a Pi electronic state and a closed-shell partner. The particular Λ doublet level preferred is opposite for molecules of π 1 vs π 3 electron occupancy. The physical origin of this reversal in the Λ doublet propensity is a direct reflection of the fact that for the former the A' potential surface is more repulsive since the sole π electron lies in the triatomic plane in this case, whereas for molecules of π 3 electron occupancy the A' surface is less repulsive than the A'' surface since for the A' surface only one of the three π electrons lies in the triatomic plane. The magnitude of these Λ doublet propensities is illustrated by calculated cross sections for the CH(X 2 Pi)--He system using the ab initio potential energy surfaces calculated by the Argonne theoretical group, and these cross sections are compared to those of the crossed molecular study of Liu and Macdonald [J. Chem. Phys. 61, xxxx (1989)]. A similar analysis is carried out for collisions of a molecule of π 3 electron occupancy and is illustrated by inelastic collisions of OH(X 2 Pi)

  18. Quantum chemical approach for positron annihilation spectra of atoms and molecules beyond plane-wave approximation

    Science.gov (United States)

    Ikabata, Yasuhiro; Aiba, Risa; Iwanade, Toru; Nishizawa, Hiroaki; Wang, Feng; Nakai, Hiromi

    2018-05-01

    We report theoretical calculations of positron-electron annihilation spectra of noble gas atoms and small molecules using the nuclear orbital plus molecular orbital method. Instead of a nuclear wavefunction, the positronic wavefunction is obtained as the solution of the coupled Hartree-Fock or Kohn-Sham equation for a positron and the electrons. The molecular field is included in the positronic Fock operator, which allows an appropriate treatment of the positron-molecule repulsion. The present treatment succeeds in reproducing the Doppler shift, i.e., full width at half maximum (FWHM) of experimentally measured annihilation (γ-ray) spectra for molecules with a mean absolute error less than 10%. The numerical results indicate that the interpretation of the FWHM in terms of a specific molecular orbital is not appropriate.

  19. Differential elastic scattering of He* (21S) by Ar, Kr and Xe: Repulsive rainbows and optical potentials

    International Nuclear Information System (INIS)

    Martin, D.W.; Gregor, R.W.; Jordan, R.M.; Siska, P.E.

    1978-01-01

    Elastic scattering angular distributions of He* (2 1 S) with Ar, Kr, and Xe measured in crossed atomic beams at collision energies from 0.4--2.8 kcal/mole are analyzed using a physically motivated optical potential model. The resulting potentials show some features expected on the basis of the analogous Li--rare gas potentials: monotonically increasing van der Waals well depths epsilon in the sequence Ar, Kr, Xe, and nearly constant well position r/sub m/. However, structure occurs in the repulsive parts of the potentials in the form of a local slope maximum (force minimum) at low positive potential energy, as suggested by other studies. The potential energy at the slope maximum decreases monotonically in the Ar, Kr, Xe sequence, while its position increases monotonically. The slope maximum is manifested in the angular distributions through the appearance of rainbow scattering peaks for Ar and Kr at angles well removed from those at which attractive rainbows are expected, with both repulsive and attractive rainbows evident in the same distribution. The resonance widths are constrained to be simple exponentials. Table I contains all potential parameters derived. Reasonably good agreement is obtained between measured total ionization cross sections and quenching rate constants and those calculated from the optical potentials

  20. Repulsive four-body interactions of α particles and quasistable nuclear α -particle condensates in heavy self-conjugate nuclei

    Science.gov (United States)

    Bai, Dong; Ren, Zhongzhou

    2018-05-01

    We study the effects of repulsive four-body interactions of α particles on nuclear α -particle condensates in heavy self-conjugate nuclei using a semianalytic approach, and find that the repulsive four-body interactions could decrease the critical number of α particles, beyond which quasistable α -particle condensate states can no longer exist, even if these four-body interactions make only tiny contributions to the total energy of the Hoyle-like state of 16O. Explicitly, we study eight benchmark parameter sets, and find that the critical number Ncr decreases by |Δ Ncr|˜1 -4 from Ncr˜11 with vanishing four-body interactions. We also discuss the effects of four-body interactions on energies and radii of α -particle condensates. Our study can be useful for future experiments to study α -particle condensates in heavy self-conjugate nuclei. Also, the experimental determination of Ncr will eventually help establish a better understanding on the α -particle interactions, especially the four-body interactions.

  1. Condensed phase QM/MM simulations utilizing the exchange core functions to describe exchange repulsions at the QM boundary region

    International Nuclear Information System (INIS)

    Umino, Satoru; Takahashi, Hideaki; Morita, Akihiro

    2016-01-01

    In a recent work, we developed a method [H. Takahashi et al., J. Chem. Phys. 143, 084104 (2015)] referred to as exchange-core function (ECF) approach, to compute exchange repulsion E ex between solute and solvent in the framework of the quantum mechanical (QM)/molecular mechanical (MM) method. The ECF, represented with a Slater function, plays an essential role in determining E ex on the basis of the overlap model. In the work of Takahashi et al. [J. Chem. Phys. 143, 084104 (2015)], it was demonstrated that our approach is successful in computing the hydrogen bond energies of minimal QM/MM systems including a cationic QM solute. We provide in this paper the extension of the ECF approach to the free energy calculation in condensed phase QM/MM systems by combining the ECF and the QM/MM-ER approach [H. Takahashi et al., J. Chem. Phys. 121, 3989 (2004)]. By virtue of the theory of solutions in energy representation, the free energy contribution δμ ex from the exchange repulsion was naturally formulated. We found that the ECF approach in combination with QM/MM-ER gives a substantial improvement on the calculation of the hydration free energy of a hydronium ion. This can be attributed to the fact that the ECF reasonably realizes the contraction of the electron density of the cation due to the deficit of an electron.

  2. Condensed phase QM/MM simulations utilizing the exchange core functions to describe exchange repulsions at the QM boundary region

    Energy Technology Data Exchange (ETDEWEB)

    Umino, Satoru; Takahashi, Hideaki, E-mail: hideaki@m.tohoku.ac.jp; Morita, Akihiro [Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578 (Japan)

    2016-08-28

    In a recent work, we developed a method [H. Takahashi et al., J. Chem. Phys. 143, 084104 (2015)] referred to as exchange-core function (ECF) approach, to compute exchange repulsion E{sub ex} between solute and solvent in the framework of the quantum mechanical (QM)/molecular mechanical (MM) method. The ECF, represented with a Slater function, plays an essential role in determining E{sub ex} on the basis of the overlap model. In the work of Takahashi et al. [J. Chem. Phys. 143, 084104 (2015)], it was demonstrated that our approach is successful in computing the hydrogen bond energies of minimal QM/MM systems including a cationic QM solute. We provide in this paper the extension of the ECF approach to the free energy calculation in condensed phase QM/MM systems by combining the ECF and the QM/MM-ER approach [H. Takahashi et al., J. Chem. Phys. 121, 3989 (2004)]. By virtue of the theory of solutions in energy representation, the free energy contribution δμ{sub ex} from the exchange repulsion was naturally formulated. We found that the ECF approach in combination with QM/MM-ER gives a substantial improvement on the calculation of the hydration free energy of a hydronium ion. This can be attributed to the fact that the ECF reasonably realizes the contraction of the electron density of the cation due to the deficit of an electron.

  3. Spin–orbit coupling, minimal model and potential Cooper-pairing from repulsion in BiS2-superconductors

    Science.gov (United States)

    Cobo-Lopez, Sergio; Saeed Bahramy, Mohammad; Arita, Ryotaro; Akbari, Alireza; Eremin, Ilya

    2018-04-01

    We develop the realistic minimal electronic model for recently discovered BiS2 superconductors including the spin–orbit (SO) coupling based on the first-principles band structure calculations. Due to strong SO coupling, characteristic for the Bi-based systems, the tight-binding low-energy model necessarily includes p x , p y , and p z orbitals. We analyze a potential Cooper-pairing instability from purely repulsive interaction for the moderate electronic correlations using the so-called leading angular harmonics approximation. For small and intermediate doping concentrations we find the dominant instabilities to be {d}{x2-{y}2}-wave, and s ±-wave symmetries, respectively. At the same time, in the absence of the sizable spin fluctuations the intra and interband Coulomb repulsions are of the same strength, which yield the strongly anisotropic behavior of the superconducting gaps on the Fermi surface. This agrees with recent angle resolved photoemission spectroscopy findings. In addition, we find that the Fermi surface topology for BiS2 layered systems at large electron doping can resemble the doped iron-based pnictide superconductors with electron and hole Fermi surfaces maintaining sufficient nesting between them. This could provide further boost to increase T c in these systems.

  4. Guidance for evidence-informed policies about health systems: rationale for and challenges of guidance development.

    Directory of Open Access Journals (Sweden)

    Xavier Bosch-Capblanch

    Full Text Available In the first paper in a three-part series on health systems guidance, Xavier Bosch-Capblanch and colleagues examine how guidance is currently formulated in low- and middle-income countries, and the challenges to developing such guidance.

  5. 78 FR 48175 - Retrospective Review of Draft Guidance Documents Issued Before 2010; Withdrawal of Guidances

    Science.gov (United States)

    2013-08-07

    ... guidances (number 19 through 22), contact the Office of Pharmaceutical Science in CDER. 23. ``Qualifying for... to the pharmaceutical industry. In most cases, FDA has developed other guidances and resources to... guidances: 1. ``Manufacturing, Processing, or Holding Active Pharmaceutical Ingredients''--issued April 1998...

  6. Electron-molecule collisions

    International Nuclear Information System (INIS)

    Shimamura, I.; Takayanagi, K.

    1984-01-01

    The study of collision processes plays an important research role in modern physics. Many significant discoveries have been made by means of collision experiments. Based on theoretical, experimental, and computational studies, this volume presents an overview detailing the basic processes of electron-molecule collisions. The editors have collected papers-written by a group of international experts-that consider a diverse range of phenomena occurring in electronmolecule collisions. The volume discusses first the basic formulation for scattering problems and then gives an outline of the physics of electron-molecule collisions. The main topics covered are rotational transitions, vibrational transitions, dissociation of molecules in slow collisions, the electron-molecule collision as a spectroscopic tool for studying molecular electronic structures, and experimental and computational techniques for determining the cross sections. These well-referenced chapters are self-contained and can be read independently or consecutively. Authoritative and up-to-date, Electron-Molecule Collisions is a useful addition to the libraries of students and researchers in the fields of atomic, molecular, and chemical physics, and physical chemistry

  7. Piezoelectric ceramic (PZT) modulates axonal guidance growth of rat cortical neurons via RhoA, Rac1, and Cdc42 pathways.

    Science.gov (United States)

    Wen, Jianqiang; Liu, Meili

    2014-03-01

    Electrical stimulation is critical for axonal connection, which can stimulate axonal migration and deformation to promote axonal growth in the nervous system. Netrin-1, an axonal guidance cue, can also promote axonal guidance growth, but the molecular mechanism of axonal guidance growth under indirect electric stimulation is still unknown. We investigated the molecular mechanism of axonal guidance growth under piezoelectric ceramic lead zirconate titanate (PZT) stimulation in the primary cultured cortical neurons. PZT induced marked axonal elongation. Moreover, PZT activated the excitatory postsynaptic currents (EPSCs) by increasing the frequency and amplitude of EPSCs of the cortical neurons in patch clamp assay. PZT downregulated the expression of Netrin-1 and its receptor Deleted in Colorectal Cancer (DCC). Rho GTPase signaling is involved in interactions of Netrin-1 and DCC. PZT activated RhoA. Dramatic decrease of Cdc42 and Rac1 was also observed after PZT treatment. RhoA inhibitor Clostridium botulinum C3 exoenzyme (C3-Exo) prevented the PZT-induced downregulation of Netrin-1 and DCC. We suggest that PZT can promote axonal guidance growth by downregulation of Netrin-1 and DCC to mediate axonal repulsive responses via the Rho GTPase signaling pathway. Obviously, piezoelectric materials may provide a new approach for axonal recovery and be beneficial for clinical therapy in the future.

  8. 48 CFR 427.104 - General guidance.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 4 2010-10-01 2010-10-01 false General guidance. 427.104... REQUIREMENTS PATENTS, DATA, AND COPYRIGHTS General 427.104 General guidance. As used in FAR part 27, the agency head or agency head designee is the Senior Procurement Executive, except under FAR 27.306(a) and (b...

  9. Driving change : sustainable development action plans Guidance

    OpenAIRE

    Sustainable Development Commission

    2008-01-01

    This guidance builds upon the Sustainable Development Commission’s previous guidance, Getting Started (August 2005), which set out the basic elements that the Sustainable Development Commission would expect to see in a good Sustainable Development Action Plan. Publisher PDF Original published August 2005.

  10. Guidance for performing preliminary assessments under CERCLA

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1991-09-01

    EPA headquarters and a national site assessment workgroup produced this guidance for Regional, State, and contractor staff who manage or perform preliminary assessments (PAs). EPA has focused this guidance on the types of sites and site conditions most commonly encountered. The PA approach described in this guidance is generally applicable to a wide variety of sites. However, because of the variability among sites, the amount of information available, and the level of investigative effort required, it is not possible to provide guidance that is equally applicable to all sites. PA investigators should recognize this and be aware that variation from this guidance may be necessary for some sites, particularly for PAs performed at Federal facilities, PAs conducted under EPA`s Environmental Priorities Initiative (EPI), and PAs at sites that have previously been extensively investigated by EPA or others. The purpose of this guidance is to provide instructions for conducting a PA and reporting results. This guidance discusses the information required to evaluate a site and how to obtain it, how to score a site, and reporting requirements. This document also provides guidelines and instruction on PA evaluation, scoring, and the use of standard PA scoresheets. The overall goal of this guidance is to assist PA investigators in conducting high-quality assessments that result in correct site screening or further action recommendations on a nationally consistent basis.

  11. Career Guidance and Public Mental Health

    Science.gov (United States)

    Robertson, Peter J.

    2013-01-01

    Career guidance may have the potential to promote public health by contributing positively to both the prevention of mental health conditions and to population level well-being. The policy implications of this possibility have received little attention. Career guidance agencies are well placed to reach key target groups. Producing persuasive…

  12. Standards for School Guidance Programs in Maryland.

    Science.gov (United States)

    Maryland State Dept. of Education, Baltimore. Div. of Compensatory, Urban, and Supplementary Programs.

    This brochure is a checklist to rate school compliance with the standards for school guidance programs in Maryland, which were developed by the Maryland State Department of Education. The first set of standards addresses the philosophy and goals of school guidance programs in Maryland and the extent to which program goals and objectives are…

  13. HANDBOOK: HAZARDOUS WASTE INCINERATION MEASUREMENT GUIDANCE

    Science.gov (United States)

    This publication, Volume III of the Hazardous Waste Incineration Guidance Series, contains general guidance to permit writers in reviewing hazardous waste incineration permit applications and trial burn plans. he handbook is a how-to document dealing with how incineration measure...

  14. 33 CFR 385.5 - Guidance memoranda.

    Science.gov (United States)

    2010-07-01

    ... ability of the Corps of Engineers, the South Florida Water Management District, and other non-Federal... § 385.5 Guidance memoranda. (a) General. (1) Technical guidance for internal management of Corps of...) General format and content of Project Implementation Reports (§ 385.26(a)); (ii) Instructions for...

  15. Guidance Counsellor Strategies for Handling Bullying

    Science.gov (United States)

    Power-Elliott, Michleen; Harris, Gregory E.

    2012-01-01

    The purpose of this exploratory-descriptive study was to examine how guidance counsellors in the province of Newfoundland and Labrador would handle a specific verbal-relational bullying incident. Also of interest was guidance counsellor involvement and training in bullying programmes and Positive Behaviour Supports. Data for this study was…

  16. Why Guidance Works Better than Punishment.

    Science.gov (United States)

    Gartrell, Dan

    1995-01-01

    Examines how guidance techniques address the full spectrum of intervention methods, from prevention to conflict resolution to long-term management strategies. Discusses how punishment affects both children and teachers. Suggests that to put guidance into practice teachers should: be realistic, tailor activities to each child, practice positive…

  17. MOLECULES IN η CARINAE

    International Nuclear Information System (INIS)

    Loinard, Laurent; Menten, Karl M.; Güsten, Rolf; Zapata, Luis A.; Rodríguez, Luis F.

    2012-01-01

    We report the detection toward η Carinae of six new molecules, CO, CN, HCO + , HCN, HNC, and N 2 H + , and of two of their less abundant isotopic counterparts, 13 CO and H 13 CN. The line profiles are moderately broad (∼100 km s –1 ), indicating that the emission originates in the dense, possibly clumpy, central arcsecond of the Homunculus Nebula. Contrary to previous claims, CO and HCO + do not appear to be underabundant in η Carinae. On the other hand, molecules containing nitrogen or the 13 C isotope of carbon are overabundant by about one order of magnitude. This demonstrates that, together with the dust responsible for the dimming of η Carinae following the Great Eruption, the molecules detected here must have formed in situ out of CNO-processed stellar material.

  18. Ultrasound Guidance for Botulinum Neurotoxin Chemodenervation Procedures

    Directory of Open Access Journals (Sweden)

    Katharine E. Alter

    2017-12-01

    Full Text Available Injections of botulinum neurotoxins (BoNTs are prescribed by clinicians for a variety of disorders that cause over-activity of muscles; glands; pain and other structures. Accurately targeting the structure for injection is one of the principle goals when performing BoNTs procedures. Traditionally; injections have been guided by anatomic landmarks; palpation; range of motion; electromyography or electrical stimulation. Ultrasound (US based imaging based guidance overcomes some of the limitations of traditional techniques. US and/or US combined with traditional guidance techniques is utilized and or recommended by many expert clinicians; authors and in practice guidelines by professional academies. This article reviews the advantages and disadvantages of available guidance techniques including US as well as technical aspects of US guidance and a focused literature review related to US guidance for chemodenervation procedures including BoNTs injection.

  19. Electron Accumulative Molecules.

    Science.gov (United States)

    Buades, Ana B; Sanchez Arderiu, Víctor; Olid-Britos, David; Viñas, Clara; Sillanpää, Reijo; Haukka, Matti; Fontrodona, Xavier; Paradinas, Markos; Ocal, Carmen; Teixidor, Francesc

    2018-02-28

    With the goal to produce molecules with high electron accepting capacity and low reorganization energy upon gaining one or more electrons, a synthesis procedure leading to the formation of a B-N(aromatic) bond in a cluster has been developed. The research was focused on the development of a molecular structure able to accept and release a specific number of electrons without decomposing or change in its structural arrangement. The synthetic procedure consists of a parallel decomposition reaction to generate a reactive electrophile and a synthesis reaction to generate the B-N(aromatic) bond. This procedure has paved the way to produce the metallacarboranylviologen [M(C 2 B 9 H 11 )(C 2 B 9 H 10 )-NC 5 H 4 -C 5 H 4 N-M'(C 2 B 9 H 11 )(C 2 B 9 H 10 )] (M = M' = Co, Fe and M = Co and M' = Fe) and semi(metallacarboranyl)viologen [3,3'-M(8-(NC 5 H 4 -C 5 H 4 N-1,2-C 2 B 9 H 10 )(1',2'-C 2 B 9 H 11 )] (M = Co, Fe) electron cumulative molecules. These molecules are able to accept up to five electrons and to donate one in single electron steps at accessible potentials and in a reversible way. By targeted synthesis and corresponding electrochemical tests each electron transfer (ET) step has been assigned to specific fragments of the molecules. The molecules have been carefully characterized, and the electronic communication between both metal centers (when this situation applies) has been definitely observed through the coplanarity of both pyridine fragments. The structural characteristics of these molecules imply a low reorganization energy that is a necessary requirement for low energy ET processes. This makes them electronically comparable to fullerenes, but on their side, they have a wide range of possible solvents. The ET from one molecule to another has been clearly demonstrated as well as their self-organizing capacity. We consider that these molecules, thanks to their easy synthesis, ET, self-organizing capacity, wide range of solubility, and easy processability, can

  20. Scattering of atoms by molecules adsorbed at solid surfaces

    International Nuclear Information System (INIS)

    Parra, Zaida.

    1988-01-01

    The formalism of collisional time-correlation functions, appropriate for scattering by many-body targets, is implemented to study energy transfer in the scattering of atoms and ions from molecules adsorbed on metal surfaces. Double differential cross-sections for the energy and angular distributions of atoms and ions scattered by a molecule adsorbed on a metal surface are derived in the limit of impulsive collisions and within a statistical model that accounts for single and double collisions. They are found to be given by the product of an effective cross-section that accounts for the probability of deflection into a solid angle times a probability per unit energy transfer. A cluster model is introduced for the vibrations of an adsorbed molecule which includes the molecular atoms, the surface atoms binding the molecule, and their nearest neighbors. The vibrational modes of CO adsorbed on a Ni(001) metal surface are obtained using two different cluster models to represent the on-top and bridge-bonding situations. A He/OC-Ni(001) potential is constructed from a strongly repulsive potential of He interacting with the oxygen atom in the CO molecule and a van der Waals attraction accounting for the He interaction with the free Ni(001) surface. A potential is presented for the Li + /OC-Ni(001) where a coulombic term is introduced to account for the image force. Trajectory studies are performed and analyzed in three dimensions to obtain effective classical cross-sections for the He/OC-Ni(001) and Li + /OC-Ni(001) systems. Results for the double differential cross-sections are presented as functions of scattering angles, energy transfer and collisional energy. Temperature dependence results are also analyzed. Extensions of the approach and inclusion of effects such as anharmonicity, collisions at lower energies, and applications of the approach to higher coverages are discussed

  1. Optofluidic control of axonal guidance

    Science.gov (United States)

    Gu, Ling; Ordonez, Simon; Black, Bryan; Mohanty, Samarendra K.

    2013-03-01

    Significant efforts are being made for control on axonal guidance due to its importance in nerve regeneration and in the formation of functional neuronal circuitry in-vitro. These include several physical (topographic modification, optical force, and electric field), chemical (surface functionalization cues) and hybrid (electro-chemical, photochemical etc) methods. Here, we report comparison of the effect of linear flow versus microfluidic flow produced by an opticallydriven micromotor in guiding retinal ganglion axons. A circularly polarized laser tweezers was used to hold, position and spin birefringent calcite particle near growth cone, which in turn resulted in microfluidic flow. The flow rate and resulting shear-force on axons could be controlled by a varying the power of the laser tweezers beam. The calcite particles were placed separately in one chamber and single particle was transported through microfluidic channel to another chamber containing the retina explant. In presence of flow, the turning of axons was found to strongly correlate with the direction of flow. Turning angle as high as 90° was achieved. Optofluidic-manipulation can be applied to other types of mammalian neurons and also can be extended to stimulate mechano-sensing neurons.

  2. Effect of dipole polarizability on positron binding by strongly polar molecules

    International Nuclear Information System (INIS)

    Gribakin, G F; Swann, A R

    2015-01-01

    A model for positron binding to polar molecules is considered by combining the dipole potential outside the molecule with a strongly repulsive core of a given radius. Using existing experimental data on binding energies leads to unphysically small core radii for all of the molecules studied. This suggests that electron–positron correlations neglected in the simple model play a large role in determining the binding energy. We account for these by including the polarization potential via perturbation theory and non-perturbatively. The perturbative model makes reliable predictions of binding energies for a range of polar organic molecules and hydrogen cyanide. The model also agrees with the linear dependence of the binding energies on the polarizability inferred from the experimental data (Danielson et al 2009 J. Phys. B: At. Mol. Opt. Phys. 42 235203). The effective core radii, however, remain unphysically small for most molecules. Treating molecular polarization non-perturbatively leads to physically meaningful core radii for all of the molecules studied and enables even more accurate predictions of binding energies to be made for nearly all of the molecules considered. (paper)

  3. Molecule of the Month

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 1; Issue 2. Molecule of the Month Isomers of Benzene - Still Pursuing Dreams. J Chandrasekhar. Feature Article Volume 1 Issue 2 February 1996 pp 80-83. Fulltext. Click here to view fulltext PDF. Permanent link:

  4. Atoms, Molecules, and Compounds

    CERN Document Server

    Manning, Phillip

    2007-01-01

    Explores the atoms that govern chemical processes. This book shows how the interactions between simple substances such as salt and water are crucial to life on Earth and how those interactions are predestined by the atoms that make up the molecules.

  5. Electrons in Molecules

    Indian Academy of Sciences (India)

    structure and properties (includingreactivt'ty) - both static (independent of time) and ... Furthermore, since the energy of H2 + in the ground state must be lower than that of .... (Figure 2b); note also that dp is positive in parts of the antibinding regions behind the two ... But, now both the sizes and shapes of molecules enter into.

  6. Molecule of the Month

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 16; Issue 12. Molecule of the Month - A Stable Dibismuthene - A Compound with a Bi-Bi Double Bond. V Chandrasekhar. Volume 16 ... Author Affiliations. V Chandrasekhar1. Department of Chemistry, Indian Institute of Technology, Kanpur 208 016, India.

  7. OMG: Open molecule generator

    NARCIS (Netherlands)

    Peironcely, J.E.; Rojas-Chertó, M.; Fichera, D.; Reijmers, T.; Coulier, L.; Faulon, J.-L.; Hankemeier, T.

    2012-01-01

    Computer Assisted Structure Elucidation has been used for decades to discover the chemical structure of unknown compounds. In this work we introduce the first open source structure generator, Open Molecule Generator (OMG), which for a given elemental composition produces all non-isomorphic chemical

  8. Molecule-based magnets

    Indian Academy of Sciences (India)

    Administrator

    Employing self-assembly methods, it is possible to engineer a bulk molecular material ... synthesis of molecular magnets in 1986, a large variety of them have been synthesized, which can be catego- ... maintained stably per organic molecule, stabilization of a ..... rotating freely under an applied field because it is a magne-.

  9. Molecule of the Month

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 5. Molecule of the Month Molecular–Chameleon: Solvatochromism at its Iridescent Best! Photon Rao. Feature Article Volume 2 Issue 5 May 1997 pp 69-72. Fulltext. Click here to view fulltext PDF. Permanent link:

  10. Exotic helium molecules

    International Nuclear Information System (INIS)

    Portier, M.

    2007-12-01

    We study the photo-association of an ultracold cloud of magnetically trapped helium atoms: pairs of colliding atoms interact with one or two laser fields to produce a purely long range 4 He 2 (2 3 S 1 -2 3 P 0 ) molecule, or a 4 He 2 (2 3 S 1 -2 3 S 1 ) long range molecule. Light shifts in one photon photo-association spectra are measured and studied as a function of the laser polarization and intensity, and the vibrational state of the excited molecule. They result from the light-induced coupling between the excited molecule, and bound and scattering states of the interaction between two metastable atoms. Their analysis leads to the determination of the scattering length a = (7.2 ± 0.6) ruling collisions between spin polarized atoms. The two photon photo-association spectra show evidence of the production of polarized, long-range 4 He 2 (2 3 S 1 -2 3 S 1 ) molecules. They are said to be exotic as they are made of two metastable atoms, each one carrying a enough energy to ionize the other. The corresponding lineshapes are calculated and decomposed in sums and products of Breit-Wigner and Fano profiles associated to one and two photon processes. The experimental spectra are fit, and an intrinsic lifetime τ = (1.4 ± 0.3) μs is deduced. It is checked whether this lifetime could be limited by spin-dipole induced Penning autoionization. This interpretation requires that there is a quasi-bound state close to the dissociation threshold in the singlet interaction potential between metastable helium atoms for the theory to match the experiment. (author)

  11. OMG: Open Molecule Generator.

    Science.gov (United States)

    Peironcely, Julio E; Rojas-Chertó, Miguel; Fichera, Davide; Reijmers, Theo; Coulier, Leon; Faulon, Jean-Loup; Hankemeier, Thomas

    2012-09-17

    Computer Assisted Structure Elucidation has been used for decades to discover the chemical structure of unknown compounds. In this work we introduce the first open source structure generator, Open Molecule Generator (OMG), which for a given elemental composition produces all non-isomorphic chemical structures that match that elemental composition. Furthermore, this structure generator can accept as additional input one or multiple non-overlapping prescribed substructures to drastically reduce the number of possible chemical structures. Being open source allows for customization and future extension of its functionality. OMG relies on a modified version of the Canonical Augmentation Path, which grows intermediate chemical structures by adding bonds and checks that at each step only unique molecules are produced. In order to benchmark the tool, we generated chemical structures for the elemental formulas and substructures of different metabolites and compared the results with a commercially available structure generator. The results obtained, i.e. the number of molecules generated, were identical for elemental compositions having only C, O and H. For elemental compositions containing C, O, H, N, P and S, OMG produces all the chemically valid molecules while the other generator produces more, yet chemically impossible, molecules. The chemical completeness of the OMG results comes at the expense of being slower than the commercial generator. In addition to being open source, OMG clearly showed the added value of constraining the solution space by using multiple prescribed substructures as input. We expect this structure generator to be useful in many fields, but to be especially of great importance for metabolomics, where identifying unknown metabolites is still a major bottleneck.

  12. OMG: Open Molecule Generator

    Directory of Open Access Journals (Sweden)

    Peironcely Julio E

    2012-09-01

    Full Text Available Abstract Computer Assisted Structure Elucidation has been used for decades to discover the chemical structure of unknown compounds. In this work we introduce the first open source structure generator, Open Molecule Generator (OMG, which for a given elemental composition produces all non-isomorphic chemical structures that match that elemental composition. Furthermore, this structure generator can accept as additional input one or multiple non-overlapping prescribed substructures to drastically reduce the number of possible chemical structures. Being open source allows for customization and future extension of its functionality. OMG relies on a modified version of the Canonical Augmentation Path, which grows intermediate chemical structures by adding bonds and checks that at each step only unique molecules are produced. In order to benchmark the tool, we generated chemical structures for the elemental formulas and substructures of different metabolites and compared the results with a commercially available structure generator. The results obtained, i.e. the number of molecules generated, were identical for elemental compositions having only C, O and H. For elemental compositions containing C, O, H, N, P and S, OMG produces all the chemically valid molecules while the other generator produces more, yet chemically impossible, molecules. The chemical completeness of the OMG results comes at the expense of being slower than the commercial generator. In addition to being open source, OMG clearly showed the added value of constraining the solution space by using multiple prescribed substructures as input. We expect this structure generator to be useful in many fields, but to be especially of great importance for metabolomics, where identifying unknown metabolites is still a major bottleneck.

  13. Optimal guidance law in quantum mechanics

    International Nuclear Information System (INIS)

    Yang, Ciann-Dong; Cheng, Lieh-Lieh

    2013-01-01

    Following de Broglie’s idea of a pilot wave, this paper treats quantum mechanics as a problem of stochastic optimal guidance law design. The guidance scenario considered in the quantum world is that an electron is the flight vehicle to be guided and its accompanying pilot wave is the guidance law to be designed so as to guide the electron to a random target driven by the Wiener process, while minimizing a cost-to-go function. After solving the stochastic optimal guidance problem by differential dynamic programming, we point out that the optimal pilot wave guiding the particle’s motion is just the wavefunction Ψ(t,x), a solution to the Schrödinger equation; meanwhile, the closed-loop guidance system forms a complex state–space dynamics for Ψ(t,x), from which quantum operators emerge naturally. Quantum trajectories under the action of the optimal guidance law are solved and their statistical distribution is shown to coincide with the prediction of the probability density function Ψ ∗ Ψ. -- Highlights: •Treating quantum mechanics as a pursuit-evasion game. •Reveal an interesting analogy between guided flight motion and guided quantum motion. •Solve optimal quantum guidance problem by dynamic programming. •Gives a formal proof of de Broglie–Bohm’s idea of a pilot wave. •The optimal pilot wave is shown to be a wavefunction solved from Schrödinger equation

  14. Optimal guidance law in quantum mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ciann-Dong, E-mail: cdyang@mail.ncku.edu.tw; Cheng, Lieh-Lieh, E-mail: leo8101@hotmail.com

    2013-11-15

    Following de Broglie’s idea of a pilot wave, this paper treats quantum mechanics as a problem of stochastic optimal guidance law design. The guidance scenario considered in the quantum world is that an electron is the flight vehicle to be guided and its accompanying pilot wave is the guidance law to be designed so as to guide the electron to a random target driven by the Wiener process, while minimizing a cost-to-go function. After solving the stochastic optimal guidance problem by differential dynamic programming, we point out that the optimal pilot wave guiding the particle’s motion is just the wavefunction Ψ(t,x), a solution to the Schrödinger equation; meanwhile, the closed-loop guidance system forms a complex state–space dynamics for Ψ(t,x), from which quantum operators emerge naturally. Quantum trajectories under the action of the optimal guidance law are solved and their statistical distribution is shown to coincide with the prediction of the probability density function Ψ{sup ∗}Ψ. -- Highlights: •Treating quantum mechanics as a pursuit-evasion game. •Reveal an interesting analogy between guided flight motion and guided quantum motion. •Solve optimal quantum guidance problem by dynamic programming. •Gives a formal proof of de Broglie–Bohm’s idea of a pilot wave. •The optimal pilot wave is shown to be a wavefunction solved from Schrödinger equation.

  15. International guidance, evolution and trends

    International Nuclear Information System (INIS)

    Ruiz Lopez, C.

    2010-01-01

    Carmen Ruiz Lopez, (CSN) addressed the evolution of some of the fundamental concepts related to the objective of protecting future generations, with the intention of encouraging the discussion, and to determine whether the recent international guidance implied any change in philosophy and approach regarding the practical interpretation and implementation of such fundamental concepts. C. Ruiz presented a general overview of the ICRP and IAEA guidance developments as well as the major changes or reorientations introduced by the latest ICRP Recommendations and IAEA Safety Standards that are relevant to long-term issues of geological disposal, namely, ICRP 103 (2009), ICRP 101 (2006), IAEA Safety Fundamentals SF-1(2006) and WS-R-4. As for the ICRP developments, ICRP 103 confirms the validity of ICRP 81(1998) as the main ICRP reference for long-lived waste disposal. C. Ruiz then noted the extension of the scope of ICPR 81 mentioning some of the principles and recommendations related to the objective of protecting future generations and the view of the Commission for demonstrating compliance. ICRP 103 and ICRP 101 reinforce the importance of transparency in the decision-making process and in the demonstration of confidence in situations of increasing uncertainties about time, giving more weight to the process itself and strengthening the need for an open dialogue between regulator and implementer. In both recommendations the Commission recognises the influence of societal values in the final decision on the level of radiological protection, as well as the influence of social concerns and political aspects in the decision-making process. The evolution of internationally agreed safety fundamental objectives and principles can be observed in the changes from the IAEA's Waste Safety Fundamentals of 1995 to the new Safety Fundamentals of 2006. C Ruiz presented a comparison of both documents focussing on the differences in dealing with fundamental concepts related to the

  16. Assessment of the effectiveness of guidance services in senior ...

    African Journals Online (AJOL)

    Guidance Service Assessment Questionnaire for Teacher/Students (GSAQTS) was used to measure the extent of guidance services and their perception of it. ... to counsellor, and a misconception of the counsellors role has made guidance ...

  17. Vacuum mammotomy under ultrasound guidance

    International Nuclear Information System (INIS)

    Luczynska, E.; Kocurek, A.; Pawlik, T.; Aniol, J.; Herman, K.; Skotnicki, P.

    2007-01-01

    Breast ultrasound is a non-invasive method of breast examination. You can use it also for fine needle biopsy, core needle biopsy, vacuum mammotomy and for placing the '' wire '' before open surgical biopsy. 106 patients (105 women and 1 man) aged 20-71 years (mean age 46.9) were treated in Cancer Institute in Cracow by vacuum mammotomy under ultrasound guidance. The lesions found in ultrasonography were divided into three groups: benign lesions (BI RADS II), ambiguous lesions (BI RADS 0, III and IVa), and suspicious lesions (BI RADS IV B, IV C and V). Then lesions were qualified to vacuum mammotomy. According to USG, fibroadenoma or '' fibroadenoma-like '' lesions were found in 75 women, in 6 women complicated cysts, in 6 women cyst with dense fluid (to differentiate with FA), and in 19 patients undefined lesions. Fibroadenoma was confirmed in histopathology in 74% patients among patients with fibroadenoma or '' fibroadenoma-like '' lesions in ultrasound (in others also benign lesions were found). Among lesions undefined after ultrasound examination (total 27 patients) cancer was confirmed in 6 % (DCIS and IDC). In 6 patients with complicated cysts in ultrasound examination, histopathology confirmed fibroadenoma in 4 women, an intraductal lesion in 1 woman and inflamatory process in 1 woman. Also in 6 women with a dense cyst or fibroadenoma seen in ultrasound, histopathology confirmed fibroadenoma in 3 women and fibrosclerosis in 3 women. Any breast lesions undefined or suspicious after ultrasound examination should be verified. The method of verification or kind of operation of the whole lesion (vacuum mammotomy or '' wire '') depends on many factors, for example: lesion localization; lesion size; BI RADS category. (author)

  18. Online thesis guidance management information system

    Science.gov (United States)

    Nasution, T. H.; Pratama, F.; Tanjung, K.; Siregar, I.; Amalia, A.

    2018-03-01

    The development of internet technology in education is still not maximized, especially in the process of thesis guidance between students and lecturers. Difficulties met the lecturers to help students during thesis guidance is the limited communication time and the compatibility of schedule between students and lecturer. To solve this problem, we designed an online thesis guidance management information system that helps students and lecturers to do thesis tutoring process anytime, anywhere. The system consists of a web-based admin app for usage management and an android-based app for students and lecturers.

  19. Size-dependent social attraction and repulsion explains the decision of Atlantic cod Gadus morhua to enter baited pots.

    Science.gov (United States)

    Anders, N; Fernö, A; Humborstad, O-B; Løkkeborg, S; Rieucau, G; Utne-Palm, A C

    2017-12-01

    The present study tested whether the presence of already retained fishes inside baited fish pots acted as a social attraction and affected the entrance probability of Atlantic cod Gadus morhua in a fjord in northern Norway. Video analysis revealed that the probability of an entrance initially increased with the presence of low numbers of fishes inside the pot, but subsequently decreased at a critical number of caught fishes. The critical number was dependent on the size of the G. morhua attempting to enter. This demonstrates that social attraction and repulsion play a role in G. morhua pot fishing and has important implications for the capture efficiency of fisheries executed with pots. © 2017 The Fisheries Society of the British Isles.

  20. Blow-up behavior of ground states for a nonlinear Schrödinger system with attractive and repulsive interactions

    Science.gov (United States)

    Guo, Yujin; Zeng, Xiaoyu; Zhou, Huan-Song

    2018-01-01

    We consider a nonlinear Schrödinger system arising in a two-component Bose-Einstein condensate (BEC) with attractive intraspecies interactions and repulsive interspecies interactions in R2. We get ground states of this system by solving a constrained minimization problem. For some kinds of trapping potentials, we prove that the minimization problem has a minimizer if and only if the attractive interaction strength ai (i = 1 , 2) of each component of the BEC system is strictly less than a threshold a*. Furthermore, as (a1 ,a2) ↗ (a* ,a*), the asymptotical behavior for the minimizers of the minimization problem is discussed. Our results show that each component of the BEC system concentrates at a global minimum of the associated trapping potential.

  1. Defining the contributions of permanent electrostatics, Pauli repulsion, and dispersion in density functional theory calculations of intermolecular interaction energies

    Energy Technology Data Exchange (ETDEWEB)

    Horn, Paul R., E-mail: prhorn@berkeley.edu; Mao, Yuezhi; Head-Gordon, Martin, E-mail: mhg@cchem.berkeley.edu [Kenneth S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California, Berkeley, California 94720, USA and Chemical Sciences Division Lawrence Berkeley National Laboratory Berkeley, California 94720 (United States)

    2016-03-21

    In energy decomposition analysis of Kohn-Sham density functional theory calculations, the so-called frozen (or pre-polarization) interaction energy contains contributions from permanent electrostatics, dispersion, and Pauli repulsion. The standard classical approach to separate them suffers from several well-known limitations. We introduce an alternative scheme that employs valid antisymmetric electronic wavefunctions throughout and is based on the identification of individual fragment contributions to the initial supersystem wavefunction as determined by an energetic optimality criterion. The density deformations identified with individual fragments upon formation of the initial supersystem wavefunction are analyzed along with the distance dependence of the new and classical terms for test cases that include the neon dimer, ammonia borane, water-Na{sup +}, water-Cl{sup −}, and the naphthalene dimer.

  2. Acidic pH retards the fibrillization of human islet amyloid polypeptide due to electrostatic repulsion of histidines

    Science.gov (United States)

    Li, Yang; Xu, Weixin; Mu, Yuguang; Zhang, John Z. H.

    2013-08-01

    The human Islet Amyloid Polypeptide (hIAPP) is the major constituent of amyloid deposits in pancreatic islets of type-II diabetes. IAPP is secreted together with insulin from the acidic secretory granules at a low pH of approximately 5.5 to the extracellular environment at a neutral pH. The increased accumulation of extracellular hIAPP in diabetes indicates that changes in pH may promote amyloid formation. To gain insights and underlying mechanisms of the pH effect on hIAPP fibrillogenesis, all-atom molecular dynamics simulations in explicit solvent model were performed to study the structural properties of five hIAPP protofibrillar oligomers, under acidic and neutral pH, respectively. In consistent with experimental findings, simulation results show that acidic pH is not conducive to the structural stability of these oligomers. This provides a direct evidence for a recent experiment [L. Khemtemourian, E. Domenech, J. P. F. Doux, M. C. Koorengevel, and J. A. Killian, J. Am. Chem. Soc. 133, 15598 (2011)], 10.1021/ja205007j, which suggests that acidic pH inhibits the fibril formation of hIAPP. In addition, a complementary coarse-grained simulation shows the repulsive electrostatic interactions among charged His18 residues slow down the dimerization process of hIAPP by twofold. Besides, our all-atom simulations reveal acidic pH mainly affects the local structure around residue His18 by destroying the surrounding hydrogen-bonding network, due to the repulsive interactions between protonated interchain His18 residues at acidic pH. It is also disclosed that the local interactions nearby His18 operating between adjacent β-strands trigger the structural transition, which gives hints to the experimental findings that the rate of hIAPP fibril formation and the morphologies of the fibrillar structures are strongly pH-dependent.

  3. Single-Molecule Nanomagnets

    Science.gov (United States)

    Friedman, Jonathan R.; Sarachik, Myriam P.

    2010-04-01

    Single-molecule magnets straddle the classical and quantum mechanical worlds, displaying many fascinating phenomena. They may have important technological applications in information storage and quantum computation. We review the physical properties of two prototypical molecular nanomagnets, Mn12-acetate and Fe8: Each behaves as a rigid, spin-10 object and exhibits tunneling between up and down directions. As temperature is lowered, the spin-reversal process evolves from thermal activation to pure quantum tunneling. At low temperatures, magnetic avalanches occur in which the magnetization of an entire sample rapidly reverses. We discuss the important role that symmetry-breaking fields play in driving tunneling and in producing Berry-phase interference. Recent experimental advances indicate that quantum coherence can be maintained on timescales sufficient to allow a meaningful number of quantum computing operations to be performed. Efforts are under way to create monolayers and to address and manipulate individual molecules.

  4. Superexcited states of molecules

    International Nuclear Information System (INIS)

    Nakamura, Hiroki; Takagi, Hidekazu.

    1990-01-01

    The report addresses the nature and major features of molecule's superexcited states, focusing on their involvement in dynamic processes. It also outlines the quantum defect theory which allows various processes involving these states to be treated in a unified way. The Rydberg state has close relation with an ionized state with a positive energy. The quantum defect theory interprets such relation. Specifically, the report first describes the quantum defect theory focusing on its basic principle. The multi-channel quantum defect theory is then outlined centering on how to describe a Rydberg-type superexcited state. Description of a dissociative double-electron excited state is also discussed. The quantum defect theory is based on the fact that the physics of the motion of a Rydberg electron vary with the region in the electron's coordinate space. Finally, various molecular processes that involve a superexcited state are addressed focusing on autoionization, photoionization, dissociative recombination and bonding ionization of diatomic molecules. (N.K.)

  5. Coulomb replica-exchange method: handling electrostatic attractive and repulsive forces for biomolecules.

    Science.gov (United States)

    Itoh, Satoru G; Okumura, Hisashi

    2013-03-30

    We propose a new type of the Hamiltonian replica-exchange method (REM) for molecular dynamics (MD) and Monte Carlo simulations, which we refer to as the Coulomb REM (CREM). In this method, electrostatic charge parameters in the Coulomb interactions are exchanged among replicas while temperatures are exchanged in the usual REM. By varying the atom charges, the CREM overcomes free-energy barriers and realizes more efficient sampling in the conformational space than the REM. Furthermore, this method requires only a smaller number of replicas because only the atom charges of solute molecules are used as exchanged parameters. We performed Coulomb replica-exchange MD simulations of an alanine dipeptide in explicit water solvent and compared the results with those of the conventional canonical, replica exchange, and van der Waals REMs. Two force fields of AMBER parm99 and AMBER parm99SB were used. As a result, the CREM sampled all local-minimum free-energy states more frequently than the other methods for both force fields. Moreover, the Coulomb, van der Waals, and usual REMs were applied to a fragment of an amyloid-β peptide (Aβ) in explicit water solvent to compare the sampling efficiency of these methods for a larger system. The CREM sampled structures of the Aβ fragment more efficiently than the other methods. We obtained β-helix, α-helix, 3(10)-helix, β-hairpin, and β-sheet structures as stable structures and deduced pathways of conformational transitions among these structures from a free-energy landscape. Copyright © 2012 Wiley Periodicals, Inc.

  6. Significant Guidance Issued by the Federal Motor Carrier Safety Administration

    Data.gov (United States)

    Department of Transportation — A list of Significant Guidance documents, which include guidance document disseminated to regulated entities or the general public that may reasonably be anticipated...

  7. Significant Guidance Issued by the Federal Transit Administration

    Data.gov (United States)

    Department of Transportation — A list of Significant Guidance documents, which include guidance document disseminated to regulated entities or the general public that may reasonably be anticipated...

  8. Significant Guidance Issued by the Federal Aviation Administration

    Data.gov (United States)

    Department of Transportation — A list of Significant Guidance documents, which include guidance document disseminated to regulated entities or the general public that may reasonably be anticipated...

  9. Significant Guidance Issued by the Federal Highway Administration

    Data.gov (United States)

    Department of Transportation — A list of Significant Guidance documents, which include guidance document disseminated to regulated entities or the general public that may reasonably be anticipated...

  10. Atoms, molecules & elements

    CERN Document Server

    Graybill, George

    2007-01-01

    Young scientists will be thrilled to explore the invisible world of atoms, molecules and elements. Our resource provides ready-to-use information and activities for remedial students using simplified language and vocabulary. Students will label each part of the atom, learn what compounds are, and explore the patterns in the periodic table of elements to find calcium (Ca), chlorine (Cl), and helium (He) through hands-on activities.

  11. European Union Sustainable Purchasing Guidance Profile

    Science.gov (United States)

    To help you find the resource that is right for your organization, EPA conducted a scan of the landscape and developed summary profiles of some of the leading sources of sustainable purchasing guidance around the globe.

  12. Responsible Purchasing Network - Sustainable Purchasing Guidance Profile

    Science.gov (United States)

    To help you find the resource that is right for your organization, EPA conducted a scan of the landscape and developed summary profiles of some of the leading sources of sustainable purchasing guidance around the globe.

  13. Regulatory systems-based licensing guidance documentation

    International Nuclear Information System (INIS)

    Delligatti, M.S.

    1991-01-01

    The US Nuclear Regulatory Commission (NRC) has developed a series of licensing guidance documents based on the regulatory requirements in Part 60 of Title 10 of the Code of Federal Regulations (10 CFR Part 60). This regulatory systems-based approach to licensing guidance documentation relies on the definition of the high-level waste repository in 10 CFR Part 60. A document which is important for the frame-work it gives to other programmatic licensing guidance is the Draft Regulatory Guide open-quotes Format and Content for the License Application for the High-Level Waste Repositoryclose quotes (FCRG). The FCRG describes a format and content acceptable to NRC for a high-level waste repository license application pursuant to the requirements of 10 CFR Part 60. Other licensing guidance documents will be compatible with the FCRG

  14. Nigerian Journal of Guidance and Counselling

    African Journals Online (AJOL)

    The Nigerian Journal of Guidance and Counselling. ... Journal Homepage Image ... by the Department of Counsellor Education, University of Ilorin, Ilorin, Nigeria. ... Awareness and use of Meseron therapy among clinical psychologists in ...

  15. Drill machine guidance using natural occurring radiation

    International Nuclear Information System (INIS)

    Dahl, H.D.; Schroeder, R.L.; Williams, B.J.

    1980-01-01

    A drilling machine guidance system is described which uses only the naturally occuring radiation within the seam or stratum of interest. The apparatus can be used for guiding horizontal drilling machines through coal seams and the like. (U.K.)

  16. Smartphone Video Guidance Sensor for Small Satellites

    Data.gov (United States)

    National Aeronautics and Space Administration — Smartphone Video Guidance Sensor(SVGS) for Small Satellites will provide a low-cost,integrated rendezvous & proximity operations sensor system to allow an...

  17. Moisture Control Guidance for Commercial and Public ...

    Science.gov (United States)

    This document provides guidance to designers, construction mangers, and building operation/maintenance managers to improve IEQ and reduce risks of encountering IEQ problems due to insufficient moisture control. EPA will be producing a document entitled

  18. RCRA Programmatic Information Policy and Guidance

    Data.gov (United States)

    U.S. Environmental Protection Agency — This asset includes program policy and guidance documents that are used by the EPA regions, states, tribes and private parties to implement the hazardous waste...

  19. Construction machine control guidance implementation strategy.

    Science.gov (United States)

    2010-07-01

    Machine Controlled Guidance (MCG) technology may be used in roadway and bridge construction to improve construction efficiencies, potentially resulting in reduced project costs and accelerated schedules. The technology utilizes a Global Positioning S...

  20. Precision Guidance with Impact Angle Requirements

    National Research Council Canada - National Science Library

    Ford, Jason

    2001-01-01

    This paper examines a weapon system precision guidance problem in which the objective is to guide a weapon onto a non-manoeuvring target so that a particular desired angle of impact is achieved using...

  1. Guidance for the national healthcare disparities report

    National Research Council Canada - National Science Library

    Swift, Elaine K

    2002-01-01

    The Agency for Healthcare Research Quality commissioned the Institute of Medicine establish a committee to provide guidance on the National Healthcare Disparities Report is of access to health care...

  2. Photonic Molecule Lasers Revisited

    Science.gov (United States)

    Gagnon, Denis; Dumont, Joey; Déziel, Jean-Luc; Dubé, Louis J.

    2014-05-01

    Photonic molecules (PMs) formed by coupling two or more optical resonators are ideal candidates for the fabrication of integrated microlasers, photonic molecule lasers. Whereas most calculations on PM lasers have been based on cold-cavity (passive) modes, i.e. quasi-bound states, a recently formulated steady-state ab initio laser theory (SALT) offers the possibility to take into account the spectral properties of the underlying gain transition, its position and linewidth, as well as incorporating an arbitrary pump profile. We will combine two theoretical approaches to characterize the lasing properties of PM lasers: for two-dimensional systems, the generalized Lorenz-Mie theory will obtain the resonant modes of the coupled molecules in an active medium described by SALT. Not only is then the theoretical description more complete, the use of an active medium provides additional parameters to control, engineer and harness the lasing properties of PM lasers for ultra-low threshold and directional single-mode emission. We will extend our recent study and present new results for a number of promising geometries. The authors acknowledge financial support from NSERC (Canada) and the CERC in Photonic Innovations of Y. Messaddeq.

  3. Interstellar molecules and masers

    International Nuclear Information System (INIS)

    Nguyen-Q-Rieu; Guibert, J.

    1978-01-01

    The study of dense and dark clouds, in which hydrogen is mostly in molecular form, became possible since the discovery of interstellar molecules, emitting in the centimeter and millimeter wavelengths. The molecular lines are generally not in local thermal equilibrium (LTE). Their intensity can often be explained by invoking a population inversion mechanism. Maser emission lines due to OH, H 2 O and SiO molecules are among the most intense molecular lines. The H 2 CO molecule, detected in absorption in front of the cold cosmic background radiation of 2.7 K, illustrates the inverse phenomenon, the antimaser absorption. For a radio transition of frequency v, the inversion rate Δn (relative population difference between the upper and lower level) as well as the maser gain can be determined from the radio observations. In the case of the OH lines in the 2 PIsub(3/2), J=3/2 state, the inversion rates approximately 1 to 2% derived from the observations, are comparable with those obtained in the laboratory. The determination of the excitation mechanisms of the masers, through the statistical equilibrium and radiative transfer equations, implies the knowledge of collisional and radiative transition probabilities. A pumping model, which can satisfactorily explain the radio observations of some interstellar OH clouds, will be discussed [fr

  4. UV DISINFECTION GUIDANCE MANUAL FOR THE ...

    Science.gov (United States)

    Provides technical information on selection, design and operation of UV systems; provides regulatory agencies with guidance and the necessary tools to assess UV systems at the design, start-up, and routine operation phase; provides manufacturers with the testing and performance standards for UV components and systems for treating drinking water. Provide guidance to water systems, regulators and manufacturers on UV disinfection of drinking water.

  5. A New Approach to Lane Guidance Systems

    OpenAIRE

    Eidehall, Andreas; Pohl, Jochen; Gustafsson, Fredrik

    2005-01-01

    This paper presents a new automotive safety function called Emergency Lane Assist (ELA). ELA combines conventional lane guidance systems with a threat assessment module that tries to activate and deactivate the lane guidance interventions according to the actual risk level of lane departure. The goal is to only prevent dangerous lane departure manoeuvres. Such a threat assessment algorithm is dependent on detailed information about the vehicle surroundings, i.e., positions and motion of other...

  6. Application of image guidance in pituitary surgery

    Science.gov (United States)

    de Lara, Danielle; Filho, Leo F. S. Ditzel; Prevedello, Daniel M.; Otto, Bradley A.; Carrau, Ricardo L.

    2012-01-01

    Background: Surgical treatment of pituitary pathologies has evolved along the years, adding safety and decreasing morbidity related to the procedure. Advances in the field of radiology, coupled with stereotactic technology and computer modeling, have culminated in the contemporary and widespread use of image guidance systems, as we know them today. Image guidance navigation has become a frequently used technology that provides continuous three-dimensional information for the accurate performance of neurosurgical procedures. We present a discussion about the application of image guidance in pituitary surgeries. Methods: Major indications for image guidance neuronavigation application in pituitary surgery are presented and demonstrated with illustrative cases. Limitations of this technology are also presented. Results: Patients presenting a history of previous transsphenoidal surgeries, anatomical variances of the sphenoid sinus, tumors with a close relation to the internal carotid arteries, and extrasellar tumors are the most important indications for image guidance in pituitary surgeries. The high cost of the equipment, increased time of surgery due to setup time, and registration and the need of specific training for the operating room personnel could be pointed as limitations of this technology. Conclusion: Intraoperative image guidance systems provide real-time images, increasing surgical accuracy and enabling safe, minimally invasive interventions. However, the use of intraoperative navigation is not a replacement for surgical experience and a systematic knowledge of regional anatomy. It must be recognized as a tool by which the neurosurgeon can reduce the risk associated with surgical approach and treatment of pituitary pathologies. PMID:22826819

  7. Determination of lateral interactions between NO molecules on Rh(111)

    International Nuclear Information System (INIS)

    Hagelaar, J H A; Flipse, C F J; Jansen, A P J

    2007-01-01

    In this study, the STM was used to locally study the adsorption of NO on a Rh(111) single crystal. Three new structures were identified. At 200 K, patches of the (4 x 2)-2NO and an unreported (2 x 2)-2NO structure were found at about 0.50ML coverage. Higher exposure gave rise to a (2 x 2)-3NO structure with all molecules adsorbed in the hcp sites. At 5K, a (4 x 4)-1NO structure was observed. The large separation between the molecules can only arise from repulsive interactions over a distance of at least four times the lattice constant (11 A). Here the interaction is estimated to be of the order of ∼10K or ∼0.1 kJ/mol. Dynamic Monte Carlo simulations taking into account adsorption, diffusion and pairwise interactions between adsorbates were used to fit the lateral interaction for the next-next nearest neighbor to the patched STM topograph at 200K for 0.50ML coverage. The value was determined to be 2 kJ/mol. Using pairwise interactions only (2 x 2)-3NO structure could not be explained. It might therefore be necessary to include three-particle interactions. Recent DFT calculations support this idea by showing attractive three-particle interactions

  8. Enhancement of spin polarization induced by Coulomb on-site repulsion between localized pz electrons in graphene embedded with line defects.

    Science.gov (United States)

    Ren, Ji-Chang; Wang, Zhigang; Zhang, Rui-Qin; Ding, Zejun; Van Hove, Michel A

    2015-11-11

    It is well known that the effect of Coulomb on-site repulsion can significantly alter the physical properties of the systems that contain localized d and/or f electrons. However, little attention has been paid to the Coulomb on-site repulsion between localized p electrons. In this study, we demonstrated that Coulomb on-site repulsion between localized pz electrons also plays an important role in graphene embedded with line defects. It is shown that the magnetism of the system largely depends on the choice of the effective Coulomb on-site parameter Ueff. Ueff at the edges of the defect enhances the exchange splitting, which increases the magnetic moment and stabilizes a ferromagnetic state of the system. In contrast, Ueff at the center of the defect weakens the spin polarization of the system. The behavior of the magnetism is explained with the Stoner criterion and the charge accumulation at the edges of the defect. Based on the linear response approach, we estimate reasonable values of Ueff to be 2.55 eV (2.3 eV) at the center (edges) of the defects. More importantly, using a DFT+U+J method, we find that exchange interactions between localized p electrons also play an important role in the spin polarization of the system. These results imply that Coulomb on-site repulsion is necessary to describe the strong interaction between localized pz electrons of carbon related materials.

  9. Influence of Electrostatics on Small Molecule Flux through a Protein Nanoreactor.

    Science.gov (United States)

    Glasgow, Jeff E; Asensio, Michael A; Jakobson, Christopher M; Francis, Matthew B; Tullman-Ercek, Danielle

    2015-09-18

    Nature uses protein compartmentalization to great effect for control over enzymatic pathways, and the strategy has great promise for synthetic biology. In particular, encapsulation in nanometer-sized containers to create nanoreactors has the potential to elicit interesting, unexplored effects resulting from deviations from well-understood bulk processes. Self-assembled protein shells for encapsulation are especially desirable for their uniform structures and ease of perturbation through genetic mutation. Here, we use the MS2 capsid, a well-defined porous 27 nm protein shell, as an enzymatic nanoreactor to explore pore-structure effects on substrate and product flux during the catalyzed reaction. Our results suggest that the shell can influence the enzymatic reaction based on charge repulsion between small molecules and point mutations around the pore structure. These findings also lend support to the hypothesis that protein compartments modulate the transport of small molecules and thus influence metabolic reactions and catalysis in vitro.

  10. Quark chemistry: charmonium molecules

    International Nuclear Information System (INIS)

    De Rujula, A.; Jaffe, R.L.

    1977-01-01

    The theoretical and experimental evidence for two quark-two antiquark hadrons is reviewed. Concentration is placed on predictions for S-wave ''charmonium molecules,'' built of a c anti c charmonium pair and a light quark-antiquark pair. Their spectrum and quantum numbers are predicted and an estimate of their decay couplings and their prediction in monochromatic pion decays from charmonium resonances produced in e + e - -annihilation is given. Some S-wave charmonium resonances should be detectable in these decays, but typical branching ratios are only at the 1% level. 19 references

  11. Ultra-cold molecule production

    International Nuclear Information System (INIS)

    Ramirez-Serrano, Jamie; Chandler, David W.; Strecker, Kevin; Rahn, Larry A.

    2005-01-01

    The production of Ultra-cold molecules is a goal of many laboratories through out the world. Here we are pursuing a unique technique that utilizes the kinematics of atomic and molecular collisions to achieve the goal of producing substantial numbers of sub Kelvin molecules confined in a trap. Here a trap is defined as an apparatus that spatially localizes, in a known location in the laboratory, a sample of molecules whose temperature is below one degree absolute Kelvin. Further, the storage time for the molecules must be sufficient to measure and possibly further cool the molecules. We utilize a technique unique to Sandia to form cold molecules from near mass degenerate collisions between atoms and molecules. This report describes the progress we have made using this novel technique and the further progress towards trapping molecules we have cooled

  12. Constituent Aspects of Workplace Guidance in Secondary VET

    Science.gov (United States)

    Swager, Robert; Klarus, Ruud; van Merriënboer, Jeroen J. G.; Nieuwenhuis, Loek F. M.

    2015-01-01

    Purpose: This paper aims to present an integrated model of workplace guidance to enhance awareness of what constitutes good guidance, to improve workplace guidance practices in vocational education and training. Design/methodology/approach: To identify constituent aspects of workplace guidance, a systematic search of Web of Science was conducted,…

  13. The Development of a Lifelong Guidance System in Hungary

    Science.gov (United States)

    Watts, A. G.; Borbely-Pecze, Bors Tibor

    2011-01-01

    The development of a lifelong guidance system in Hungary Systematic work is currently being undertaken in Hungary to develop a lifelong guidance system, in line with principles outlined by leading international organisations. The origins of career guidance in Hungary, and the nature of the current career guidance system, are outlined. The main…

  14. Non-Participation in Guidance: An Opportunity for Development?

    Science.gov (United States)

    Thomsen, Rie

    2014-01-01

    This article discusses how new opportunities for guidance can emerge from an analysis of the interplay between the participation (or lack of participation) of the individuals in career guidance, and the career guidance practitioner's response. The article suggests critical psychology as a framework for career guidance research and presents…

  15. Constituent aspects of workplace guidance in secondary VET

    NARCIS (Netherlands)

    Swager, Robert; Klarus, Ruud; Van Merriënboer, Jeroen; Nieuwenhuis, Loek

    2018-01-01

    Purpose – This paper aims to present an integrated model of workplace guidance to enhance awareness of what constitutes good guidance, to improve workplace guidance practices in vocational education and training. Design/methodology/approach – To identify constituent aspects of workplace guidance,

  16. 76 FR 61098 - Guidance for 1-Hour SO2

    Science.gov (United States)

    2011-10-03

    ...Notice is hereby given that the EPA has posted its draft non- binding guidance titled, ``Guidance for 1-Hour SO2 NAAQS SIP Submissions'' on its Web site. The EPA invites public comments on this guidance document during the comment period specified below, and plans to issue an updated version of the guidance after reviewing timely submitted comments.

  17. Guidance and Counselling in the Universal Basic Education ...

    African Journals Online (AJOL)

    Quite a number of personnel has significant and diverse roles to play. The guidance counsellor whose role is to provide indispensable guidance services is the primary focus of this paper. The paper justifies the relevance of guidance services to the UBE scheme and also isolates a number of challenges facing the guidance ...

  18. Passing Current through Touching Molecules

    DEFF Research Database (Denmark)

    Schull, G.; Frederiksen, Thomas; Brandbyge, Mads

    2009-01-01

    The charge flow from a single C-60 molecule to another one has been probed. The conformation and electronic states of both molecules on the contacting electrodes have been characterized using a cryogenic scanning tunneling microscope. While the contact conductance of a single molecule between two...

  19. Repulsion forces of superplasticizers on ground granulated blast furnace slag in alkaline media, from AFM measurements to rheological properties

    Directory of Open Access Journals (Sweden)

    Palacios, M.

    2012-12-01

    Full Text Available The electrostatic and steric repulsion induced by different superplasticizers on ground granulated blast furnace slag in alkaline media have been studied. The superplasticizers were sulfonated naphthalene, sulfonated melamine, vinyl copolymer, and polycarboxylate- based admixtures. With these superplasticizers the slag suspensions had negative zeta potentials, ranging from -3 to -10 mV. For the first time the adsorbed layer thicknesses for superplasticizers on slag using colloidal probe atomic force microscopy has been measured. To model the interparticle force interactions an effective Hamaker constant was computed from dielectric properties measured on a dense slag sample produced by spark plasma sintering. The obtained results conclude that the dispersion mechanism for all the superplasticizers studied in the present work is mainly dominated by the steric repulsion. Results were then used in a yield stress model, YODEL, to predict the yield stress with and without the superplasticizers. Predictions of the yield stress agreed well with experimental results.

    En este trabajo se ha estudiado la repulsión electrostática y estérica inducida por diferentes aditivos superplastificantes en sistemas de escoria de horno alto en medios alcalinos. Se han estudiado aditivos superplastificantes basados en naftaleno, melamina, copolímeros vinílicos y basados en policarboxilato. Estos aditivos inducen en la escoria un potencial zeta negativo, entre -3 y -10 mV. Por primera vez, se ha determinado el grosor de la capa de aditivo adsorbido sobre la escoria mediante microscopía de fuerzas atómicas (AFM. Para modelizar las fuerzas de interacción entre partículas, se ha determinado la constante efectiva de Hamaker de la escoria a partir de las propiedades dieléctricas de una muestra de escoria obtenida mediante sinterización spark plasma sintering. Los resultados obtenidos concluyen que el mecanismo de dispersión de los superplastificantes

  20. Investigation of attractive and repulsive interactions associated with ketones in supercritical CO2, based on Raman spectroscopy and theoretical calculations.

    Science.gov (United States)

    Kajiya, Daisuke; Saitow, Ken-ichi

    2013-08-07

    Carbonyl compounds are solutes that are highly soluble in supercritical CO2 (scCO2). Their solubility governs the efficiency of chemical reactions, and is significantly increased by changing a chromophore. To effectively use scCO2 as solvent, it is crucial to understand the high solubility of carbonyl compounds, the solvation structure, and the solute-solvent intermolecular interactions. We report Raman spectroscopic data, for three prototypical ketones dissolved in scCO2, and four theoretical analyses. The vibrational Raman spectra of the C=O stretching modes of ketones (acetone, acetophenone, and benzophenone) were measured in scCO2 along the reduced temperature Tr = T∕Tc = 1.02 isotherm as a function of the reduced density ρr = ρ∕ρc in the range 0.05-1.5. The peak frequencies of the C=O stretching modes shifted toward lower energies as the fluid density increased. The density dependence was analyzed by using perturbed hard-sphere theory, and the shift was decomposed into attractive and repulsive energy components. The attractive energy between the ketones and CO2 was up to nine times higher than the repulsive energy, and its magnitude increased in the following order: acetone attractive energy and optimized the relative configuration between each solute and CO2. According to theoretical calculations for the dispersion energy, the dipole-induced-dipole interaction energy, and the frequency shift due to their interactions, the experimentally determined attractive energy differences in the three solutes were attributed to the dispersion energies that depended on a chromophore attached to the carbonyl groups. It was found that the major intermolecular interaction with the attractive shift varied from dipole-induced dipole to dispersion depending on the chromophore in the ketones in scCO2. As the common conclusion for the Raman spectral measurements and the four theoretical calculations, solute polarizability, modified by the chromophore, was at the core of

  1. The bacterial defensin resistance protein MprF consists of separable domains for lipid lysinylation and antimicrobial peptide repulsion.

    Directory of Open Access Journals (Sweden)

    Christoph M Ernst

    2009-11-01

    Full Text Available Many bacterial pathogens achieve resistance to defensin-like cationic antimicrobial peptides (CAMPs by the multiple peptide resistance factor (MprF protein. MprF plays a crucial role in Staphylococcus aureus virulence and it is involved in resistance to the CAMP-like antibiotic daptomycin. MprF is a large membrane protein that modifies the anionic phospholipid phosphatidylglycerol with l-lysine, thereby diminishing the bacterial affinity for CAMPs. Its widespread occurrence recommends MprF as a target for novel antimicrobials, although the mode of action of MprF has remained incompletely understood. We demonstrate that the hydrophilic C-terminal domain and six of the fourteen proposed trans-membrane segments of MprF are sufficient for full-level lysyl-phosphatidylglycerol (Lys-PG production and that several conserved amino acid positions in MprF are indispensable for Lys-PG production. Notably, Lys-PG production did not lead to efficient CAMP resistance and most of the Lys-PG remained in the inner leaflet of the cytoplasmic membrane when the large N-terminal hydrophobic domain of MprF was absent, indicating a crucial role of this protein part. The N-terminal domain alone did not confer CAMP resistance or repulsion of the cationic test protein cytochrome c. However, when the N-terminal domain was coexpressed with the Lys-PG synthase domain either in one protein or as two separate proteins, full-level CAMP resistance was achieved. Moreover, only coexpression of the two domains led to efficient Lys-PG translocation to the outer leaflet of the membrane and to full-level cytochrome c repulsion, indicating that the N-terminal domain facilitates the flipping of Lys-PG. Thus, MprF represents a new class of lipid-biosynthetic enzymes with two separable functional domains that synthesize Lys-PG and facilitate Lys-PG translocation. Our study unravels crucial details on the molecular basis of an important bacterial immune evasion mechanism and it may help

  2. Raising the Profile of Career Guidance: Educational and Vocational Guidance Practitioner

    Science.gov (United States)

    Hiebert, Bryan

    2009-01-01

    In 2007 the International Association for Educational and Vocational Guidance (IAEVG) launched the Educational and Vocational Guidance Practitioner credential (EVGP) as one means of formally acknowledging the knowledge, skills, and personal attributes that practitioners need in order to provide quality career development services to clients. This…

  3. Safety of magnetic fusion facilities: Guidance

    International Nuclear Information System (INIS)

    1996-05-01

    This document provides guidance for the implementation of the requirements identified in DOE-STD-6002-96, Safety of Magnetic Fusion Facilities: Requirements. This guidance is intended for the managers, designers, operators, and other personnel with safety responsibilities for facilities designated as magnetic fusion facilities. While the requirements in DOE-STD-6002-96 are generally applicable to a wide range of fusion facilities, this Standard, DOE-STD-6003-96, is concerned mainly with the implementation of those requirements in large facilities such as the International Thermonuclear Experimental Reactor (ITER). Using a risk-based prioritization, the concepts presented here may also be applied to other magnetic fusion facilities. This Standard is oriented toward regulation in the Department of Energy (DOE) environment as opposed to regulation by other regulatory agencies. As the need for guidance involving other types of fusion facilities or other regulatory environments emerges, additional guidance volumes should be prepared. The concepts, processes, and recommendations set forth here are for guidance only. They will contribute to safety at magnetic fusion facilities

  4. Guidance levels, achievable doses and expectation levels

    International Nuclear Information System (INIS)

    Li, Lianbo; Meng, Bing

    2002-01-01

    The National Radiological Protection Board (NRPB), the International Atomic Energy Agency (IAEA) and the Commission of the European Communities (CEC) published their guidance levels and reference doses for typical X-ray examination and nuclear medicine in their documents in 1993, 1994 and 1996 respectively. From then on, the concept of guidance levels or reference doses have been applied to different examinations in the field of radiology and proved to be effective for reduction of patient doses. But the guidance levels or reference doses are likely to have some shortcomings and can do little to make further reduction of patient dose in the radiology departments where patient dose are already below them. For this reason, the National Radiological Protection Board (NRPB) proposed a concept named achievable doses which are based on the mean dose observed for a selected sample of radiology departments. This paper will review and discuss the concept of guidance levels and achievable doses, and propose a new concept referred to as Expectation Levels that will encourage the radiology departments where patient dose are already below the guidance levels to keep patient dose as low as reasonably achievable. Some examples of the expectation levels based on the data published by a few countries are also illustrated in this paper

  5. Fine Guidance Sensing for Coronagraphic Observatories

    Science.gov (United States)

    Brugarolas, Paul; Alexander, James W.; Trauger, John T.; Moody, Dwight C.

    2011-01-01

    Three options have been developed for Fine Guidance Sensing (FGS) for coronagraphic observatories using a Fine Guidance Camera within a coronagraphic instrument. Coronagraphic observatories require very fine precision pointing in order to image faint objects at very small distances from a target star. The Fine Guidance Camera measures the direction to the target star. The first option, referred to as Spot, was to collect all of the light reflected from a coronagraph occulter onto a focal plane, producing an Airy-type point spread function (PSF). This would allow almost all of the starlight from the central star to be used for centroiding. The second approach, referred to as Punctured Disk, collects the light that bypasses a central obscuration, producing a PSF with a punctured central disk. The final approach, referred to as Lyot, collects light after passing through the occulter at the Lyot stop. The study includes generation of representative images for each option by the science team, followed by an engineering evaluation of a centroiding or a photometric algorithm for each option. After the alignment of the coronagraph to the fine guidance system, a "nulling" point on the FGS focal point is determined by calibration. This alignment is implemented by a fine alignment mechanism that is part of the fine guidance camera selection mirror. If the star images meet the modeling assumptions, and the star "centroid" can be driven to that nulling point, the contrast for the coronagraph will be maximized.

  6. Interactions of molecules and the properties of crystals

    Science.gov (United States)

    McConnell, Thomas Daniel Leigh

    In this thesis the basic theory of the lattice dynamics of molecular crystals is considered, with particular reference to the specific case of linear molecules. The objective is to carry out a critical investigation of a number of empirical potentials as models for real systems. Suitable coordinates are introduced, in particular vibrational coordinates which are used to describe the translational and rotational modes of the free molecule. The Taylor expansion of the intermolecular potential is introduced and its terms considered, in particular the (first-order) equilibrium conditions for such a system and the (second-order) lattice vibrations. The elastic properties are also considered, in particular with reference to the specific case of rhombohedral crystals. The compressibility and a number of conditions for elastic stability are introduced. The total intermolecular interaction potential is divided into three components using perturbation methods, the electrostatic energy, the repulsion energy and the dispersion energy. A number of models are introduced for these various components. The induction energy is neglected. The electrostatic interaction is represented by atomic multipole and molecular multipole models. The repulsion and dispersion energies are modelled together in a central interaction potential, either the Lennard-Jones atom-atom potential or the anisotropic Berne-Pechukas molecule-molecule potential. In each case, the Taylor expansion coefficients, used to calculate the various molecular properties, are determined. An algorithm is described which provides a relatively simple method for calculating cartesian tensors, which are found in the Taylor expansion coefficients of the multipolar potentials. This proves to be particularly useful from a computational viewpoint, both in terms of programming and calculating efficiency. The model system carbonyl sulphide is introduced and its lattice properties are described. Suitable parameters for potentials used

  7. 75 FR 69089 - Guidance for Industry and Food and Drug Administration Staff; Class II Special Controls Guidance...

    Science.gov (United States)

    2010-11-10

    ... DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration [Docket No. FDA-2010-D-0514] Guidance for Industry and Food and Drug Administration Staff; Class II Special Controls Guidance Document... Administration (FDA) is announcing the availability of the guidance entitled ``Class II Special Controls Guidance...

  8. 76 FR 29251 - Guidance for Industry and Food and Drug Administration Staff; Class II Special Controls; Guidance...

    Science.gov (United States)

    2011-05-20

    ... DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration [Docket No. FDA-2006-D-0094] Guidance for Industry and Food and Drug Administration Staff; Class II Special Controls; Guidance Document... of the guidance entitled ``Guidance for Industry and Food and Drug Administration Staff; Class II...

  9. Measuring Integrated Socioemotional Guidance at School: Factor Structure and Reliability of the Socioemotional Guidance Questionnaire (SEG-Q)

    Science.gov (United States)

    Jacobs, Karen; Struyf, Elke

    2013-01-01

    Socioemotional guidance of students has recently become an integral part of education, however no instrument exists to measure integrated socioemotional guidance. This study therefore examines the factor structure and reliability of the Socioemotional Guidance Questionnaire. Psychometric properties of the Socioemotional Guidance Questionnaire and…

  10. Automated low-thrust guidance for the orbital maneuvering vehicle

    Science.gov (United States)

    Rose, Richard E.; Schmeichel, Harry; Shortwell, Charles P.; Werner, Ronald A.

    1988-01-01

    This paper describes the highly autonomous OMV Guidance Navigation and Control system. Emphasis is placed on a key feature of the design, the low thrust guidance algorithm. The two guidance modes, orbit change guidance and rendezvous guidance, are discussed in detail. It is shown how OMV will automatically transfer from its initial orbit to an arbitrary target orbit and reach a specified rendezvous position relative to the target vehicle.

  11. 76 FR 66925 - Guidance for 1-Hour SO2

    Science.gov (United States)

    2011-10-28

    ...The EPA is announcing an extension of the public comment period for its draft non-binding guidance titled, ``Guidance for 1-Hour SO2 SIP Submissions.'' The draft of the guidance document is currently on the EPA's Web site. The EPA is extending the comment period for an additional 30-day period and invites public comments on this guidance during this period. The EPA plans to issue an updated version of the guidance after reviewing timely submitted comments.

  12. Amending the Characterization of Guidance in Visual Analytics

    OpenAIRE

    Ceneda, Davide; Gschwandtner, Theresia; May, Thorsten; Miksch, Silvia; Schulz, Hans-Jörg; Streit, Marc; Tominski, Christian

    2017-01-01

    At VAST 2016, a characterization of guidance has been presented. It includes a definition of guidance and a model of guidance based on van Wijk's model of visualization. This note amends the original characterization of guidance in two aspects. First, we provide a clarification of what guidance actually is (and is not). Second, we insert into the model a conceptually relevant link that was missing in the original version.

  13. HUMAN FACTORS GUIDANCE FOR CONTROL ROOM EVALUATION

    International Nuclear Information System (INIS)

    OHARA, J.; BROWN, W.; STUBLER, W.; HIGGINS, J.; WACHTEL, J.; PERSENSKY, J.J.

    2000-01-01

    The Human-System Interface Design Review Guideline (NUREG-0700, Revision 1) was developed by the US Nuclear Regulatory Commission (NRC) to provide human factors guidance as a basis for the review of advanced human-system interface technologies. The guidance consists of three components: design review procedures, human factors engineering guidelines, and a software application to provide design review support called the ''Design Review Guideline.'' Since it was published in June 1996, Rev. 1 to NUREG-0700 has been used successfully by NRC staff, contractors and nuclear industry organizations, as well as by interested organizations outside the nuclear industry. The NRC has committed to the periodic update and improvement of the guidance to ensure that it remains a state-of-the-art design evaluation tool in the face of emerging and rapidly changing technology. This paper addresses the current research to update of NUREG-0700 based on the substantial work that has taken place since the publication of Revision 1

  14. The U(3) principle as base of a microscopical U(3) model for the clarification of the phenomenon of nuclear molecules

    International Nuclear Information System (INIS)

    Bader, R.

    1985-01-01

    The tenor of this thesis is the regarding of the U(3) symmetry in the study of nuclear reactions. By the description of the two colliding fragments and their relative motion by means of U(3) quantum numbers U(3) channels and U(3) channel sets are defined. It is shown that in certain collisions the U(3) symmetry of U(3) channels is incompatible with the U(3) symmetry of the compound nucleus. For these U(3) channels the formation of the compound nucleus is forbidden. In this framework a microscopical U(3) model for the phenomenon of the nuclear molecule resonances is developed. U(3) barriers which play an important role in this model are responsible for the repulsion between the two fragments. By microscopical calculations it is confirmed that by the U(3) channels allowed above the U(3) barriers an attraction between the two fragments arises. This interchange of attraction and repulsion leads to the formation of nuclear molecules. Furthermore it is shown that this incompatibility and by this the phenomenon of nuclear molecule resonances can be reduced to an U(3) principle in which the Pauli principle is contained. Basing on this U(3) principle selection rules are formulated which predict candidates for nuclear molecule resonances. This explains why only some binary systems tend to the molecule formation. (orig./HSI) [de

  15. Lanthanide single molecule magnets

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Jinkui; Zhang, Peng [Chinese Academy of Sciences, Changchun (China). Changchun Inst. of Applied Chemistry

    2015-10-01

    This book begins by providing basic information on single-molecule magnets (SMMs), covering the magnetism of lanthanide, the characterization and relaxation dynamics of SMMs and advanced means of studying lanthanide SMMs. It then systematically introduces lanthanide SMMs ranging from mononuclear and dinuclear to polynuclear complexes, classifying them and highlighting those SMMs with high barrier and blocking temperatures - an approach that provides some very valuable indicators for the structural features needed to optimize the contribution of an Ising type spin to a molecular magnet. The final chapter presents some of the newest developments in the lanthanide SMM field, such as the design of multifunctional and stimuli-responsive magnetic materials as well as the anchoring and organization of the SMMs on surfaces. In addition, the crystal structure and magnetic data are clearly presented with a wealth of illustrations in each chapter, helping newcomers and experts alike to better grasp ongoing trends and explore new directions.

  16. Lanthanide single molecule magnets

    CERN Document Server

    Tang, Jinkui

    2015-01-01

    This book begins by providing basic information on single-molecule magnets (SMMs), covering the magnetism of lanthanide, the characterization and relaxation dynamics of SMMs, and advanced means of studying lanthanide SMMs. It then systematically introduces lanthanide SMMs ranging from mononuclear and dinuclear to polynuclear complexes, classifying them and highlighting those SMMs with high barrier and blocking temperatures – an approach that provides some very valuable indicators for the structural features needed to optimize the contribution of an Ising type spin to a molecular magnet. The final chapter presents some of the newest developments in the lanthanide SMM field, such as the design of multifunctional and stimuli-responsive magnetic materials as well as the anchoring and organization of the SMMs on surfaces. In addition, the crystal structure and magnetic data are clearly presented with a wealth of illustrations in each chapter, helping newcomers and experts alike to better grasp ongoing trends and...

  17. Molecules in the Spotlight

    Energy Technology Data Exchange (ETDEWEB)

    Cryan, James

    2010-01-26

    SLAC has just unveiled the world's first X-ray laser, the LCLS. This machine produces pulses of X-rays that are ten billion times brighter than those from conventional sources. One of the goals of this machine is to make movies of chemical reactions, including reactions necessary for life and reactions that might power new energy technologies. This public lecture will show the first results from the LCLS. As a first target, we have chosen nitrogen gas, the main component of the air we breathe. Using the unprecedented power of the LCLS X-rays as a blasting torch, we have created new forms of this molecule and with unique electronic arrangements. Please share with us the first insights from this new technology.

  18. Magnetic field modification of ultracold molecule-molecule collisions

    International Nuclear Information System (INIS)

    Tscherbul, T V; Suleimanov, Yu V; Aquilanti, V; Krems, R V

    2009-01-01

    We present an accurate quantum mechanical study of molecule-molecule collisions in the presence of a magnetic field. The work focuses on the analysis of elastic scattering and spin relaxation in collisions of O 2 ( 3 Σ g - ) molecules at cold (∼0.1 K) and ultracold (∼10 -6 K) temperatures. Our calculations show that magnetic spin relaxation in molecule-molecule collisions is extremely efficient except at magnetic fields below 1 mT. The rate constant for spin relaxation at T=0.1 K and a magnetic field of 0.1 T is found to be as large as 6.1x10 -11 cm -3 s -1 . The magnetic field dependence of elastic and inelastic scattering cross sections at ultracold temperatures is dominated by a manifold of Feshbach resonances with the density of ∼100 resonances per Tesla for collisions of molecules in the absolute ground state. This suggests that the scattering length of ultracold molecules in the absolute ground state can be effectively tuned in a very wide range of magnetic fields. Our calculations demonstrate that the number and properties of the magnetic Feshbach resonances are dramatically different for molecules in the absolute ground and excited spin states. The density of Feshbach resonances for molecule-molecule scattering in the low-field-seeking Zeeman state is reduced by a factor of 10.

  19. Equation of state and Helmholtz free energy for the atomic system of the repulsive Lennard-Jones particles.

    Science.gov (United States)

    Mirzaeinia, Ali; Feyzi, Farzaneh; Hashemianzadeh, Seyed Majid

    2017-12-07

    Simple and accurate expressions are presented for the equation of state (EOS) and absolute Helmholtz free energy of a system composed of simple atomic particles interacting through the repulsive Lennard-Jones potential model in the fluid and solid phases. The introduced EOS has 17 and 22 coefficients for fluid and solid phases, respectively, which are regressed to the Monte Carlo (MC) simulation data over the reduced temperature range of 0.6≤T * ≤6.0 and the packing fraction range of 0.1 ≤ η ≤ 0.72. The average absolute relative percent deviation in fitting the EOS parameters to the MC data is 0.06 and 0.14 for the fluid and solid phases, respectively. The thermodynamic integration method is used to calculate the free energy using the MC simulation results. The Helmholtz free energy of the ideal gas is employed as the reference state for the fluid phase. For the solid phase, the values of the free energy at the reduced density equivalent to the close-packed of a hard sphere are used as the reference state. To check the validity of the predicted values of the Helmholtz free energy, the Widom particle insertion method and the Einstein crystal technique of Frenkel and Ladd are employed. The results obtained from the MC simulation approaches are well agreed to the EOS results, which show that the proposed model can reliably be utilized in the framework of thermodynamic theories.

  20. Travelling plateaus for a hyperbolic Keller–Segel system with attraction and repulsion: existence and branching instabilities

    International Nuclear Information System (INIS)

    Perthame, Benoît; Tang, Min; Vauchelet, Nicolas; Schmeiser, Christian

    2011-01-01

    How can repulsive and attractive forces, acting on a conservative system, create stable travelling patterns or branching instabilities? We have proposed to study this question in the framework of the hyperbolic Keller–Segel system with logistic sensitivity. This is a model system motivated by experiments on cell communities auto-organization, a field which is also called socio-biology. We continue earlier modelling work, where we have shown numerically that branching patterns arise for this system and we have analysed this instability by formal asymptotics for small diffusivity of the chemo-repellent. Here we are interested in the more general situation, where the diffusivities of both the chemo-attractant and the chemo-repellent are positive. To do so, we develop an appropriate functional analysis framework. We apply our method to two cases. Firstly we analyse steady states. Secondly we analyse travelling waves when neglecting the degradation coefficient of the chemo-repellent; the unique wave speed appears through a singularity cancellation which is the main theoretical difficulty. This shows that in different situations the cell density takes the shape of a plateau. The existence of steady states and travelling plateaus are a symptom of how rich the system is and why branching instabilities can occur. Numerical tests show that large plateaus may split into smaller ones, which remain stable

  1. Stability of the Superconducting d-Wave Pairing Toward the Intersite Coulomb Repulsion in CuO_2 Plane

    Science.gov (United States)

    Val'kov, V. V.; Dzebisashvili, D. M.; Korovushkin, M. M.; Barabanov, A. F.

    2018-06-01

    Taking into account the real crystalline structure of the CuO_2 plane and the strong spin-fermion coupling, we study the influence of the intersite Coulomb repulsion between holes on the Cooper instability of the spin-polaron quasiparticles in cuprate superconductors. The analysis shows that only the superconducting d-wave pairing is implemented in the whole region of doping, whereas the solutions of the self-consistent equations for the s-wave pairing are absent. It is shown that intersite Coulomb interaction V_1 between the holes located at the nearest oxygen ions does not affect the d-wave pairing, because its Fourier transform V_q vanishes in the kernel of the corresponding integral equation. The intersite Coulomb interaction V_2 of quasiparticles located at the next-nearest oxygen ions does not vanish in the integral equations, however, but it is also shown that the d-wave pairing is robust toward this interaction for physically reasonable values of V_2.

  2. A 2 Tesla Full Scale High Performance Periodic Permanent Magnet Model for Attractive (228 KN) and repulsive Maglev

    Science.gov (United States)

    Stekly, Z. J. J.; Gardner, C.; Domigan, P.; Baker, J.; Hass, M.; McDonald, C.; Wu, C.; Farrell, R. A.

    1996-01-01

    Two 214.5 cm. long high performance periodic (26 cm period) permanent magnet half-assemblies were designed and constructed for use as a wiggler using Nd-B-Fe and vanadium permendur as hard and soft magnetic materials by Field Effects, a division of Intermagnetics General Corporation. Placing these assemblies in a supporting structure with a 2.1 cm pole to pole separation resulted in a periodic field with a maximum value of 2.04 T. This is believed to be the highest field ever achieved by this type of device. The attractive force between the two 602 kg magnet assemblies is 228 kN, providing enough force for suspension of a 45,500 kg vehicle. If used in an attractive maglev system with an appropriate flat iron rail, one assembly will generate the same force with a gap of 1.05 cm leading to a lift to weight ratio of 38.6, not including the vehicle attachment structure. This permanent magnet compares well with superconducting systems which have lift to weight ratios in the range of 5 to 10. This paper describes the magnet assemblies and their measured magnetic performance. The measured magnetic field and resulting attractive magnetic force have a negative spring characteristic. Appropriate control coils are necessary to provide stable operation. The estimated performance of the assemblies in a stable repulsive mode, with eddy currents in a conducting guideway, is also discussed.

  3. Multicritical dynamical phase diagrams of the kinetic Blume-Emery-Griffiths model with repulsive biquadratic coupling in an oscillating field

    Energy Technology Data Exchange (ETDEWEB)

    Temizer, Umuet [Department of Physics, Bozok University, 66100 Yozgat (Turkey); Kantar, Ersin [Institute of Science, Erciyes University, 38039 Kayseri (Turkey); Keskin, Mustafa [Department of Physics, Erciyes University, 38039 Kayseri (Turkey)], E-mail: keskin@erciyes.edu.tr; Canko, Osman [Department of Physics, Erciyes University, 38039 Kayseri (Turkey)

    2008-06-15

    We study, within a mean-field approach, the stationary states of the kinetic Blume-Emery-Griffiths model with repulsive biquadratic coupling under the presence of a time-varying (sinusoidal) magnetic field. We employ the Glauber-type stochastic dynamics to construct set of dynamic equations of motion. The behavior of the time dependence of the order parameters and the behavior of the average order parameters in a period, which is also called the dynamic order parameters, as functions of the reduced temperature are investigated. The dynamic phase transition points are calculated and phase diagrams are presented in the reduced magnetic field amplitude and reduced temperature plane. The dynamical transition from one regime to the other can be of first- or second order depending on the region in the phase diagram. According to the values of the crystal field interaction or single-ion anisotropy constant and biquadratic exchange constant, we find 20 fundamental types of phase diagrams which exhibit many dynamic critical points, such as tricritical points, zero-temperature critical points, double critical end points, critical end point, triple point and multicritical point. Moreover, besides a disordered and ordered phases, seven coexistence phase regions exist in the system.

  4. Supramolecular "Big Bang" in a Single-Ionic Surfactant/Water System Driven by Electrostatic Repulsion: From Vesicles to Micelles.

    Science.gov (United States)

    Leclercq, Loïc; Bauduin, Pierre; Nardello-Rataj, Véronique

    2017-04-11

    In aqueous solution, dimethyldi-n-octylammonium chloride, [DiC 8 ][Cl], spontaneously forms dimers at low concentrations (1-10 mM) to decrease the strength of the hydrophobic-water contact. Dimers represent ideal building blocks for the abrupt edification of vesicles at 10 mM. These vesicles are fully characterized by dynamic and static light scattering, self-diffusion nuclear magnetic resonance, and freeze-fracture transmission electron microscopy. An increase in concentration leads to electrostatic repulsion between vesicles that explode into small micelles at 30 mM. These transitions are detected by means of surface tension, conductivity, and solubility of hydrophobic solutes as well as by isothermal titration microcalorimetry. These unusual supramolecular transitions emerge from the surfactant chemical structure that combines two contradictory features: (i) the double-chain structure tending to form low planar aggregates with low water solubility and (ii) the relatively short chains giving high hydrophilicity. The well-balanced hydrophilic-hydrophobic character of [DiC 8 ][Cl] is then believed to be at the origin of the unusual supramolecular sequence offering new opportunities for drug delivery systems.

  5. Development of an inverse distance weighted active infrared stealth scheme using the repulsive particle swarm optimization algorithm.

    Science.gov (United States)

    Han, Kuk-Il; Kim, Do-Hwi; Choi, Jun-Hyuk; Kim, Tae-Kuk

    2018-04-20

    Treatments for detection by infrared (IR) signals are higher than for other signals such as radar or sonar because an object detected by the IR sensor cannot easily recognize its detection status. Recently, research for actively reducing IR signal has been conducted to control the IR signal by adjusting the surface temperature of the object. In this paper, we propose an active IR stealth algorithm to synchronize IR signals from the object and the background around the object. The proposed method includes the repulsive particle swarm optimization statistical optimization algorithm to estimate the IR stealth surface temperature, which will result in a synchronization between the IR signals from the object and the surrounding background by setting the inverse distance weighted contrast radiant intensity (CRI) equal to zero. We tested the IR stealth performance in mid wavelength infrared (MWIR) and long wavelength infrared (LWIR) bands for a test plate located at three different positions on a forest scene to verify the proposed method. Our results show that the inverse distance weighted active IR stealth technique proposed in this study is proved to be an effective method for reducing the contrast radiant intensity between the object and background up to 32% as compared to the previous method using the CRI determined as the simple signal difference between the object and the background.

  6. Superconductor to spin-density-wave transition in quasi-one-dimensional metals with repulsive anisotropic interaction

    International Nuclear Information System (INIS)

    Rozhkov, A.V.

    2007-01-01

    A mechanism for superconductivity in a quasi-one-dimensional system with repulsive Ising-anisotropic interaction is studied. The Ising anisotropy opens the gap Δ s in the spin sector of the model. This gap allows the triplet superconductivity and the spin-density wave as the only broken symmetry phases. These phases are separated by the first order transition. The transport properties of the system are investigated in different parts of the phase diagram. The calculation of DC conductivity σ(T) in the high-temperature phase shows that the function σ(T) cannot be used as an indicator of a superconducting ground state: even if σ(T) is a decreasing function at high temperature, yet, the ground state may be insulating spin-density wave; the opposite is also true. The calculation of the spin dynamical structure factor S zz (q, ω) demonstrates that it is affected by the superconducting phase transition in a qualitative fashion: below T c the structure factor develops a gap with a coherent excitation inside this gap

  7. p -wave superconductivity in weakly repulsive 2D Hubbard model with Zeeman splitting and weak Rashba spin-orbit coupling

    Science.gov (United States)

    Hugdal, Henning G.; Sudbø, Asle

    2018-01-01

    We study the superconducting order in a two-dimensional square lattice Hubbard model with weak repulsive interactions, subject to a Zeeman field and weak Rashba spin-orbit interactions. Diagonalizing the noninteracting Hamiltonian leads to two separate bands, and by deriving an effective low-energy interaction we find the mean field gap equations for the superconducting order parameter on the bands. Solving the gap equations just below the critical temperature, we find that superconductivity is caused by Kohn-Luttinger-type interaction, while the pairing symmetry of the bands is indirectly affected by the spin-orbit coupling. The dominating attractive momentum channel of the Kohn-Luttinger term depends on the filling fraction n of the system, and it is therefore possible to change the momentum dependence of the order parameter by tuning n . Moreover, n also determines which band has the highest critical temperature. Rotating the magnetic field changes the momentum dependence from states that for small momenta reduce to a chiral px±i py type state for out-of-plane fields, to a nodal p -wave-type state for purely in-plane fields.

  8. Inversion of particle size distribution by spectral extinction technique using the attractive and repulsive particle swarm optimization algorithm

    Directory of Open Access Journals (Sweden)

    Qi Hong

    2015-01-01

    Full Text Available The particle size distribution (PSD plays an important role in environmental pollution detection and human health protection, such as fog, haze and soot. In this study, the Attractive and Repulsive Particle Swarm Optimization (ARPSO algorithm and the basic PSO were applied to retrieve the PSD. The spectral extinction technique coupled with the Anomalous Diffraction Approximation (ADA and the Lambert-Beer Law were employed to investigate the retrieval of the PSD. Three commonly used monomodal PSDs, i.e. the Rosin-Rammer (R-R distribution, the normal (N-N distribution, the logarithmic normal (L-N distribution were studied in the dependent model. Then, an optimal wavelengths selection algorithm was proposed. To study the accuracy and robustness of the inverse results, some characteristic parameters were employed. The research revealed that the ARPSO showed more accurate and faster convergence rate than the basic PSO, even with random measurement error. Moreover, the investigation also demonstrated that the inverse results of four incident laser wavelengths showed more accurate and robust than those of two wavelengths. The research also found that if increasing the interval of the selected incident laser wavelengths, inverse results would show more accurate, even in the presence of random error.

  9. Rheo-SAXS investigation of shear-thinning behaviour of very anisometric repulsive disc-like clay suspensions.

    Science.gov (United States)

    Philippe, A M; Baravian, C; Imperor-Clerc, M; De Silva, J; Paineau, E; Bihannic, I; Davidson, P; Meneau, F; Levitz, P; Michot, L J

    2011-05-18

    Aqueous suspensions of swelling clay minerals exhibit a rich and complex rheological behaviour. In particular, these repulsive systems display strong shear-thinning at very low volume fractions in both the isotropic and gel states. In this paper, we investigate the evolution with shear of the orientational distribution of aqueous clay suspensions by synchrotron-based rheo-SAXS experiments using a Couette device. Measurements in radial and tangential configurations were carried out for two swelling clay minerals of similar morphology and size, Wyoming montmorillonite and Idaho beidellite. The shear evolution of the small angle x-ray scattering (SAXS) patterns displays significantly different features for these two minerals. The detailed analysis of the angular dependence of the SAXS patterns in both directions provides the average Euler angles of the statistical effective particle in the shear plane. We show that for both samples, the average orientation is fully controlled by the local shear stress around the particle. We then apply an effective approach to take into account multiple hydrodynamic interactions in the system. Using such an approach, it is possible to calculate the evolution of viscosity as a function of shear rate from the knowledge of the average orientation of the particles. The viscosity thus recalculated almost perfectly matches the measured values as long as collective effects are not too important in the system.

  10. Rheo-SAXS investigation of shear-thinning behaviour of very anisometric repulsive disc-like clay suspensions

    International Nuclear Information System (INIS)

    Philippe, A M; Baravian, C; Imperor-Clerc, M; De Silva, J; Davidson, P; Paineau, E; Bihannic, I; Michot, L J; Meneau, F; Levitz, P

    2011-01-01

    Aqueous suspensions of swelling clay minerals exhibit a rich and complex rheological behaviour. In particular, these repulsive systems display strong shear-thinning at very low volume fractions in both the isotropic and gel states. In this paper, we investigate the evolution with shear of the orientational distribution of aqueous clay suspensions by synchrotron-based rheo-SAXS experiments using a Couette device. Measurements in radial and tangential configurations were carried out for two swelling clay minerals of similar morphology and size, Wyoming montmorillonite and Idaho beidellite. The shear evolution of the small angle x-ray scattering (SAXS) patterns displays significantly different features for these two minerals. The detailed analysis of the angular dependence of the SAXS patterns in both directions provides the average Euler angles of the statistical effective particle in the shear plane. We show that for both samples, the average orientation is fully controlled by the local shear stress around the particle. We then apply an effective approach to take into account multiple hydrodynamic interactions in the system. Using such an approach, it is possible to calculate the evolution of viscosity as a function of shear rate from the knowledge of the average orientation of the particles. The viscosity thus recalculated almost perfectly matches the measured values as long as collective effects are not too important in the system.

  11. Virtual Ultrasound Guidance for Inexperienced Operators

    Science.gov (United States)

    Caine, Timothy; Martin, David

    2012-01-01

    Medical ultrasound or echocardiographic studies are highly operator-dependent and generally require lengthy training and internship to perfect. To obtain quality echocardiographic images in remote environments, such as on-orbit, remote guidance of studies has been employed. This technique involves minimal training for the user, coupled with remote guidance from an expert. When real-time communication or expert guidance is not available, a more autonomous system of guiding an inexperienced operator through an ultrasound study is needed. One example would be missions beyond low Earth orbit in which the time delay inherent with communication will make remote guidance impractical. The Virtual Ultrasound Guidance system is a combination of hardware and software. The hardware portion includes, but is not limited to, video glasses that allow hands-free, full-screen viewing. The glasses also allow the operator a substantial field of view below the glasses to view and operate the ultrasound system. The software is a comprehensive video program designed to guide an inexperienced operator through a detailed ultrasound or echocardiographic study without extensive training or guidance from the ground. The program contains a detailed description using video and audio to demonstrate equipment controls, ergonomics of scanning, study protocol, and scanning guidance, including recovery from sub-optimal images. The components used in the initial validation of the system include an Apple iPod Classic third-generation as the video source, and Myvue video glasses. Initially, the program prompts the operator to power-up the ultrasound and position the patient. The operator would put on the video glasses and attach them to the video source. After turning on both devices and the ultrasound system, the audio-video guidance would then instruct on patient positioning and scanning techniques. A detailed scanning protocol follows with descriptions and reference video of each view along with

  12. Overcoming consumer inertia to dietary guidance.

    Science.gov (United States)

    Webb, Densie; Byrd-Bredbenner, Carol

    2015-07-01

    Despite 35 y of dietary guidance, there has been no substantial shift in consumer compliance. Consumers report that they seek information on nutrition and healthy eating, but most are not paying attention to dietary recommendations. For guidance to be effective, it must be realistic. Even with increasingly detailed nutrition information and evidence that diet affects health outcomes, convenience and taste remain the strongest determinants of food choices. It is up to health educators to clear up confusion and give consumers control with nutrition messages that are realistic, positive, easy to understand, and actionable without an expectation that consumers will surrender foods they love. © 2015 American Society for Nutrition.

  13. Overcoming Consumer Inertia to Dietary Guidance12

    Science.gov (United States)

    Webb, Densie; Byrd-Bredbenner, Carol

    2015-01-01

    Despite 35 y of dietary guidance, there has been no substantial shift in consumer compliance. Consumers report that they seek information on nutrition and healthy eating, but most are not paying attention to dietary recommendations. For guidance to be effective, it must be realistic. Even with increasingly detailed nutrition information and evidence that diet affects health outcomes, convenience and taste remain the strongest determinants of food choices. It is up to health educators to clear up confusion and give consumers control with nutrition messages that are realistic, positive, easy to understand, and actionable without an expectation that consumers will surrender foods they love. PMID:26178023

  14. Electron-excited molecule interactions

    International Nuclear Information System (INIS)

    Christophorou, L.G.; Tennessee Univ., Knoxville, TN

    1991-01-01

    In this paper the limited but significant knowledge to date on electron scattering from vibrationally/rotationally excited molecules and electron scattering from and electron impact ionization of electronically excited molecules is briefly summarized and discussed. The profound effects of the internal energy content of a molecule on its electron attachment properties are highlighted focusing in particular on electron attachment to vibrationally/rotationally and to electronically excited molecules. The limited knowledge to date on electron-excited molecule interactions clearly shows that the cross sections for certain electron-molecule collision processes can be very different from those involving ground state molecules. For example, optically enhanced electron attachment studies have shown that electron attachment to electronically excited molecules can occur with cross sections 10 6 to 10 7 times larger compared to ground state molecules. The study of electron-excited molecule interactions offers many experimental and theoretical challenges and opportunities and is both of fundamental and technological significance. 54 refs., 15 figs

  15. Single Molecule Screening of Disease DNA Without Amplification

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ji-Young [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    was probed with fluorescently-labeled probe molecules and imaged. When only the probes were stained and hybridized in a vial, it had 6 orders of magnitude dynamic range with a detection limit of ~0.7 copy/cell. A second dye was added to lower the false positive levels. Although there was a sacrifice of two orders of magnitude in detection limit, the number of false positives was reduced to zero. HPV-16 DNA was also hybridized and detected on surface-tethered probes. When the entire human genomic DNA and HPV was labeled and hybridized, the detection limit was similar to that of one-color assay detected in capillary. However, non-specific adsorption was high, and the dynamic range was narrow because of saturation of the surface and electrostatic repulsion between hybridized targets on the surface. The second probe was introduced to lower non-specific adsorption, and the strategy succeeded in 4 orders of magnitude linear dynamic range in a log-log plot, along with 2.4 copies/cell detection limit. DNA extracts of cell lines that contained a known copy number of HPV-16 DNA were tested with the four strategies described above. The calculated numbers from observed molecule counts matched the known values. Results from the Pap test sample with added HPV DNA were similar to those of purified DNA, suggesting our method is compatible with the conventional Pap test sample collection method. Further optimization will be needed before this single molecule level detection and identification can actually be used in a real clinical lab, but it has good potential and applicability. Improvement such as automated imaging and scanning, more accurate data processing software as well as sensitive camera, should help increase the efficiency and throughput.

  16. Organic Molecules in Meteorites

    Science.gov (United States)

    Martins, Zita

    2015-08-01

    Carbonaceous meteorites are primitive samples from the asteroid belt, containing 3-5wt% organic carbon. The exogenous delivery of organic matter by carbonaceous meteorites may have contributed to the organic inventory of the early Earth. The majority (>70%) of the meteoritic organic material consist of insoluble organic matter (IOM) [1]. The remaining meteoritic organic material (meteorites contain soluble organic molecules with different abundances and distributions, which may reflect the extension of aqueous alteration or thermal metamorphism on the meteorite parent bodies. Extensive aqueous alteration on the meteorite parent body may result on 1) the decomposition of α-amino acids [5, 6]; 2) synthesis of β- and γ-amino acids [2, 6-9]; 3) higher relative abundances of alkylated polycyclic aromatic hydrocarbons (PAHs) [6, 10]; and 4) higher L-enantiomer excess (Lee) value of isovaline [6, 11, 12].The soluble organic content of carbonaceous meteorites may also have a contribution from Fischer-Tropsch/Haber-Bosch type gas-grain reactions after the meteorite parent body cooled to lower temperatures [13, 14].The analysis of the abundances and distribution of the organic molecules present in meteorites helps to determine the physical and chemical conditions of the early solar system, and the prebiotic organic compounds available on the early Earth.[1] Cody and Alexander (2005) GCA 69, 1085. [2] Cronin and Chang (1993) in: The Chemistry of Life’s Origin. pp. 209-258. [3] Martins and Sephton (2009) in: Amino acids, peptides and proteins in organic chemistry. pp. 1-42. [4] Martins (2011) Elements 7, 35. [5] Botta et al. (2007) MAPS 42, 81. [6] Martins et al. (2015) MAPS, in press. [7] Cooper and Cronin (1995) GCA 59, 1003. [8] Glavin et al. (2006) MAPS. 41, 889. [9] Glavin et al. (2011) MAPS 45, 1948. [10] Elsila et al. (2005) GCA 5, 1349. [11] Glavin and Dworkin (2009) PNAS 106, 5487. [12] Pizzarello et al. (2003) GCA 67, 1589. [13] Chan et al. (2012) MAPS. 47, 1502

  17. 28 CFR 91.53 - Other guidance.

    Science.gov (United States)

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Other guidance. 91.53 Section 91.53 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) GRANTS FOR CORRECTIONAL FACILITIES Environmental... Justice has also published NEPA procedures that incorporate the CEQ regulations at 28 CFR part 61...

  18. 21 CFR 601.29 - Guidance documents.

    Science.gov (United States)

    2010-04-01

    ... Manufacturers Assistance (HFM-40), Center for Biologics Evaluation and Research, Food and Drug Administration... 21 Food and Drugs 7 2010-04-01 2010-04-01 false Guidance documents. 601.29 Section 601.29 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) BIOLOGICS...

  19. 21 CFR 312.145 - Guidance documents.

    Science.gov (United States)

    2010-04-01

    ... of Drug Information, Center for Drug Evaluation and Research, Food and Drug Administration, 10903 New... Evaluation and Research, Food and Drug Administration, 1401 Rockville Pike, Rockville, MD 20852-1448. [65 FR... 21 Food and Drugs 5 2010-04-01 2010-04-01 false Guidance documents. 312.145 Section 312.145 Food...

  20. Chinese Human Rights Guidance on Minerals Sourcing

    DEFF Research Database (Denmark)

    Buhmann, Karin

    2017-01-01

    in the minerals sector and due diligence to ensure socially responsible sourcing of minerals with a particular focus on human rights, the guidelines refer to international human rights standards and are designed to be consistent with guidance issued by the OECD. The article discusses the Chinese guidelines...

  1. Guidance for performing site inspections under CERCLA

    Energy Technology Data Exchange (ETDEWEB)

    1992-09-01

    This guidance presents EPA`s site inspection (SI) strategy. The strategy discusses procedural guidelines to investigate potential Superfund (CERCLA) sites for evaluation pursuant to the Hazard Ranking System (HRS), revised in accordance with the Superfund Amendments and Reauthorization Act of 1986. The HRS is the primary means by which EPA evaluates sites for superfund`s National Priorities List (NPL).

  2. Bridge over troubled water: Guidance crosses | Amundson ...

    African Journals Online (AJOL)

    This article is based on a keynote presentation at an international conference where the focus was cross-over career guidance. Simon and Garfunkel's popular song, "Bridge ... and the future, and building connections. There also was the suggestion that other metaphors could be used as a way to broaden the exploration.

  3. Guidance on Port Biological Baseline Surveys (PBBS)

    Digital Repository Service at National Institute of Oceanography (India)

    Awad, A.; Haag, F.; Anil, A.C.; Abdulla, A.

    This publication has been prepared by GBP, IOI, CSIR-NIO and IUCN in order to serve as guidance to those who are planning to carry out a port biological baseline survey, in particular in the context of Ballast Water Management. It has been drafted...

  4. The Guidance Counselor and the Reading Curriculum.

    Science.gov (United States)

    Ediger, Marlow

    There are many ways guidance counselors can help teachers achieve more optimal reading instruction. Counselors first may have to ascertain the kinds of problems faced by a student in learning to read. Assessing a student's ability to use picture clues to decipher words may be necessary with primary grade students. Knowledge about phonics, using…

  5. Guidance of eruption for general practitioners.

    Science.gov (United States)

    Ngan, Peter W; Kao, Elizabeth C; Wei, Stephen H

    2003-04-01

    The principle of early treatment through well-planned extraction of primary teeth followed by removal of permanent teeth has stood the test of time. The objective of this article is to develop some simple guidelines for general dental practitioners to perform 'guidance of eruption' in malocclusion with severe crowding.

  6. ROUTE PLAN DESIGNER FOR TRACTOR GUIDANCE SYSTEMS

    DEFF Research Database (Denmark)

    Sveistrup, Daniel; Jørgensen, Rasmus Nyholm; Green, Ole

    2010-01-01

    Earlier works have shown field trial designs to be very labor extensive, even when combining autoguidancesystems with conventional machinery.Designing routes for semi-automated systems in a controlled manner is both resource demandingand complicated. Different types of auto-guidance systems vary ...

  7. Tunnelling of a molecule

    International Nuclear Information System (INIS)

    Jarvis, P.D.; Bulte, D.P.

    1998-01-01

    A quantum-mechanical description of tunnelling is presented for a one-dimensional system with internal oscillator degrees of freedom. The 'charged diatomic molecule' is frustrated on encountering a barrier potential by its centre of charge not being coincident with its centre of mass, resulting in transitions amongst internal states. In an adiabatic limit, the tunnelling of semiclassical coherent-like oscillator states is shown to exhibit the Hartman and Bueuttiker-Landauer times t H and t BL , with the time dependence of the coherent state parameter for the tunnelled state given by α(t) = α e -iω(t+Δt) , Δt = t H - it BL . A perturbation formalism is developed, whereby the exact transfer matrix can be expanded to any desired accuracy in a suitable limit. An 'intrinsic' time, based on the oscillator transition rate during tunnelling, transmission or reflection, is introduced. In simple situations the resulting intrinsic tunnelling time is shown to vanish to lowest order. In the general case a particular (nonzero) parametrisation is inferred, and its properties discussed in comparison with the literature on tunnelling times for both wavepackets and internal clocks. Copyright (1998) CSIRO Australia

  8. Single molecule tracking

    Science.gov (United States)

    Shera, E. Brooks

    1988-01-01

    A detection system is provided for identifying individual particles or molecules having characteristic emission in a flow train of the particles in a flow cell. A position sensitive sensor is located adjacent the flow cell in a position effective to detect the emissions from the particles within the flow cell and to assign spatial and temporal coordinates for the detected emissions. A computer is then enabled to predict spatial and temporal coordinates for the particle in the flow train as a function of a first detected emission. Comparison hardware or software then compares subsequent detected spatial and temporal coordinates with the predicted spatial and temporal coordinates to determine whether subsequently detected emissions originate from a particle in the train of particles. In one embodiment, the particles include fluorescent dyes which are excited to fluoresce a spectrum characteristic of the particular particle. Photones are emitted adjacent at least one microchannel plate sensor to enable spatial and temporal coordinates to be assigned. The effect of comparing detected coordinates with predicted coordinates is to define a moving sample volume which effectively precludes the effects of background emissions.

  9. Wnt5a regulates midbrain dopaminergic axon growth and guidance.

    Directory of Open Access Journals (Sweden)

    Brette D Blakely

    2011-03-01

    Full Text Available During development, precise temporal and spatial gradients are responsible for guiding axons to their appropriate targets. Within the developing ventral midbrain (VM the cues that guide dopaminergic (DA axons to their forebrain targets remain to be fully elucidated. Wnts are morphogens that have been identified as axon guidance molecules. Several Wnts are expressed in the VM where they regulate the birth of DA neurons. Here, we describe that a precise temporo-spatial expression of Wnt5a accompanies the development of nigrostriatal projections by VM DA neurons. In mice at E11.5, Wnt5a is expressed in the VM where it was found to promote DA neurite and axonal growth in VM primary cultures. By E14.5, when DA axons are approaching their striatal target, Wnt5a causes DA neurite retraction in primary cultures. Co-culture of VM explants with Wnt5a-overexpressing cell aggregates revealed that Wnt5a is capable of repelling DA neurites. Antagonism experiments revealed that the effects of Wnt5a are mediated by the Frizzled receptors and by the small GTPase, Rac1 (a component of the non-canonical Wnt planar cell polarity pathway. Moreover, the effects were specific as they could be blocked by Wnt5a antibody, sFRPs and RYK-Fc. The importance of Wnt5a in DA axon morphogenesis was further verified in Wnt5a-/- mice, where fasciculation of the medial forebrain bundle (MFB as well as the density of DA neurites in the MFB and striatal terminals were disrupted. Thus, our results identify a novel role of Wnt5a in DA axon growth and guidance.

  10. Raman non-coincidence effect of boroxol ring: The interplay between repulsion and attraction forces in the glassy, supercooled and liquid state

    Science.gov (United States)

    Kalampounias, Angelos G.; Papatheodorou, George N.

    2018-06-01

    Temperature dependent Raman spectra of boric oxide have been measured in a temperature range covering the glassy, supercooled and liquid state. The shift of the isotropic band assigned to boroxol rings relative to the anisotropic component upon heating the glass is measured and attributed to the Raman non-coincidence effect. The measured shift is associated with the competition between attraction and repulsion forces with increasing temperature. The relation of dephasing and orientational relaxation times to the non-coincidence effect of the condensed phases has been examined. We discuss our results in the framework of the current phenomenological status of the field in an attempt to separate the attraction and repulsion contributions corresponding to the observed non-coincidence effect.

  11. Theoretical Investigations Regarding Single Molecules

    DEFF Research Database (Denmark)

    Pedersen, Kim Georg Lind

    Neoclassical Valence Bond Theory, Quantum Transport, Quantum Interference, Kondo Effect, and Electron Pumping. Trap a single organic molecule between two electrodes and apply a bias voltage across this "molecular junction". When electrons pass through the molecule, the different electron paths can...... interfere destructively or constructively. Destructive interference effects in electron transport could potentially improve thermo-electrics, organic logic circuits and energy harvesting. We have investigated destructive interference in off-resonant transport through organic molecules, and have found a set...

  12. Biofuels: from microbes to molecules

    National Research Council Canada - National Science Library

    Lu, Xuefeng

    2014-01-01

    .... The production of different biofuel molecules including hydrogen, methane, ethanol, butanol, higher chain alcohols, isoprenoids and fatty acid derivatives, from genetically engineered microbes...

  13. Labelled molecules, modern research implements

    International Nuclear Information System (INIS)

    Pichat, L.; Langourieux, Y.

    1974-01-01

    Details of the synthesis of carbon 14- and tritium-labelled molecules are examined. Although the methods used are those of classical organic chemistry the preparation of carbon 14-labelled molecules differs in some respects, most noticeably in the use of 14 CO 2 which requires very special handling techniques. For the tritium labelling of organic molecules the methods are somewhat different, very often involving exchange reactions. The following are described in turn: the so-called Wilzbach exchange method; exchange by catalysis in solution; catalytic hydrogenation with tritium; reductions with borotritides. Some applications of labelled molecules in organic chemistry, biochemistry and pharmacology are listed [fr

  14. Effects of repulsive three-body force in 12C + 12C scattering at 100A MeV

    Directory of Open Access Journals (Sweden)

    W.W. Qu

    2015-12-01

    Full Text Available The angular distribution of 12C + 12C scattering at an incident energy of 100A MeV has been measured. The elastic and inelastic scatterings in 12C to the excitation energies of up to ∼45 MeV were measured simultaneously for the first time with the high-resolution Grand Raiden spectrometer at the Research Center for Nuclear Physics (RCNP. The angular distributions of the elastic scattering to the ground state (01+ and inelastic scattering to the 4.44 MeV (21+ excited state were precisely obtained in the angular range of 1.0°–7.5° with a step of 0.1°. Additionally, the angular distribution was obtained for the sum of the cross sections for excitation energies above the 4.44 MeV state up to 11 MeV, which includes the 7.65 MeV (02+, 9.64 MeV (31−, and 10.30 MeV (22+ states, in addition to probably the simultaneous excitation of the 4.44 MeV state in the projectile and the target nuclei. Those combined data provide a means to study the effects of channel coupling on the elastic cross section. The observed angular distributions are compared with theoretical calculations based on three double-folding models with complex G-matrix interactions, the CEG07b, MPa, and ESC models. The importance of three-body repulsive forces included in the CEG07b and MPa models will be discussed.

  15. Floating Chip Mounting System Driven by Repulsive Force of Permanent Magnets for Multiple On-Site SPR Immunoassay Measurements

    Science.gov (United States)

    Horiuchi, Tsutomu; Tobita, Tatsuya; Miura, Toru; Iwasaki, Yuzuru; Seyama, Michiko; Inoue, Suzuyo; Takahashi, Jun-ichi; Haga, Tsuneyuki; Tamechika, Emi

    2012-01-01

    We have developed a measurement chip installation/removal mechanism for a surface plasmon resonance (SPR) immunoassay analysis instrument designed for frequent testing, which requires a rapid and easy technique for changing chips. The key components of the mechanism are refractive index matching gel coated on the rear of the SPR chip and a float that presses the chip down. The refractive index matching gel made it possible to optically couple the chip and the prism of the SPR instrument easily via elastic deformation with no air bubbles. The float has an autonomous attitude control function that keeps the chip parallel in relation to the SPR instrument by employing the repulsive force of permanent magnets between the float and a float guide located in the SPR instrument. This function is realized by balancing the upward elastic force of the gel and the downward force of the float, which experiences a leveling force from the float guide. This system makes it possible to start an SPR measurement immediately after chip installation and to remove the chip immediately after the measurement with a simple and easy method that does not require any fine adjustment. Our sensor chip, which we installed using this mounting system, successfully performed an immunoassay measurement on a model antigen (spiked human-IgG) in a model real sample (non-homogenized milk) that included many kinds of interfering foreign substances without any sample pre-treatment. The ease of the chip installation/removal operation and simple measurement procedure are suitable for frequent on-site agricultural, environmental and medical testing. PMID:23202030

  16. Structural behavior and dynamics of an anomalous fluid between attractive and repulsive walls: templating, molding, and superdiffusion.

    Science.gov (United States)

    Leoni, Fabio; Franzese, Giancarlo

    2014-11-07

    Confinement can modify the dynamics, the thermodynamics, and the structural properties of liquid water, the prototypical anomalous liquid. By considering a generic model for anomalous liquids, suitable for describing solutions of globular proteins, colloids, or liquid metals, we study by molecular dynamics simulations the effect that an attractive wall with structure and a repulsive wall without structure have on the phases, the crystal nucleation, and the dynamics of the fluid. We find that at low temperatures the large density of the attractive wall induces a high-density, high-energy structure in the first layer ("templating" effect). In turn, the first layer induces a "molding" effect on the second layer determining a structure with reduced energy and density, closer to the average density of the system. This low-density, low-energy structure propagates further through the layers by templating effect and can involve all the existing layers at the lowest temperatures investigated. Therefore, although the high-density, high-energy structure does not self-reproduce further than the first layer, the structured wall can have a long-range influence thanks to a sequence of templating, molding, and templating effects through the layers. We find that the walls also have an influence on the dynamics of the liquid, with a stronger effect near the attractive wall. In particular, we observe that the dynamics is largely heterogeneous (i) among the layers, as a consequence of the sequence of structures caused by the walls presence, and (ii) within the same layer, due to superdiffusive liquid veins within a frozen matrix of particles near the walls at low temperature and high density. Hence, the partial freezing of the first layer does not correspond necessarily to an effective reduction of the channel's section in terms of transport properties, as suggested by other authors.

  17. Why LiFePO4 is a safe battery electrode: Coulomb repulsion induced electron-state reshuffling upon lithiation.

    Science.gov (United States)

    Liu, Xiaosong; Wang, Yung Jui; Barbiellini, Bernardo; Hafiz, Hasnain; Basak, Susmita; Liu, Jun; Richardson, Thomas; Shu, Guojiun; Chou, Fangcheng; Weng, Tsu-Chien; Nordlund, Dennis; Sokaras, Dimosthenis; Moritz, Brian; Devereaux, Thomas P; Qiao, Ruimin; Chuang, Yi-De; Bansil, Arun; Hussain, Zahid; Yang, Wanli

    2015-10-21

    LiFePO4 is a battery cathode material with high safety standards due to its unique electronic structure. We performed systematic experimental and theoretical studies based on soft X-ray emission, absorption, and hard X-ray Raman spectroscopy of LixFePO4 nanoparticles and single crystals. The results clearly show a non-rigid electron-state reconfiguration of both the occupied and unoccupied Fe-3d and O-2p states during the (de)lithiation process. We focus on the energy configurations of the occupied states of LiFePO4 and the unoccupied states of FePO4, which are the critical states where electrons are removed and injected during the charge and discharge process, respectively. In LiFePO4, the soft X-ray emission spectroscopy shows that, due to the Coulomb repulsion effect, the occupied Fe-3d states with the minority spin sit close to the Fermi level. In FePO4, the soft X-ray absorption and hard X-ray Raman spectroscopy show that the unoccupied Fe-3d states again sit close to the Fermi level. These critical 3d electron state configurations are consistent with the calculations based on modified Becke and Johnson potentials GGA+U (MBJGGA+U) framework, which improves the overall lineshape prediction compared with the conventionally used GGA+U method. The combined experimental and theoretical studies show that the non-rigid electron state reshuffling guarantees the stability of oxygen during the redox reaction throughout the charge and discharge process of LiFePO4 electrodes, leading to the intrinsic safe performance of the electrodes.

  18. Elementary process theory: a formal axiomatic system with a potential application as a foundational framework for physics supporting gravitational repulsion of matter and antimatter

    International Nuclear Information System (INIS)

    Cabbolet, M.J.T.F.

    2010-01-01

    Theories of modern physics predict that antimatter having rest mass will be attracted by the earth's gravitational field, but the actual coupling of antimatter with gravitation has not been established experimentally. The purpose of the present research was to identify laws of physics that would govern the universe if antimatter having rest mass would be repulsed by the earth's gravitational field. As a result, a formalized axiomatic system was developed together with interpretation rules for the terms of the language: the intention is that every theorem of the system yields a true statement about physical reality. Seven non-logical axioms of this axiomatic system form the elementary process theory (EPT): this is then a scheme of elementary principles describing the dynamics of individual processes taking place at supersmall scale. It is demonstrated how gravitational repulsion functions in the universe of the EPT, and some observed particles and processes have been formalized in the framework of the EPT. Incompatibility of quantum mechanics (QM) and General Relativity (GR) with the EPT is proven mathematically; to demonstrate applicability to real world problems to which neither QM nor GR applies, the EPT has been applied to a theory of the Planck era of the universe. The main conclusions are that a completely formalized framework for physics has been developed supporting the existence of gravitational repulsion and that the present results give rise to a potentially progressive research program. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  19. RMP Guidance for Chemical Distributors - Appendix D: OSHA Guidance on PSM

    Science.gov (United States)

    Guidance on the Process Safety Management standard says information (including MSDS) about chemicals, including process intermediates, must enable accurate assessment of fire/explosion characteristics, reactivity hazards, and corrosing/erosion effects.

  20. A Formal Investigation of the Organization of Guidance Behavior: Implications for Humans and Autonomous Guidance

    Science.gov (United States)

    Kong, Zhaodan

    Guidance behavior generated either by artificial agents or humans has been actively studied in the fields of both robotics and cognitive science. The goals of these two fields are different. The former is the automatic generation of appropriate or even optimal behavior, while the latter is the understanding of the underlying mechanism. Their challenges, though, are closely related, the most important one being the lack of a unified, formal and grounded framework where the guidance behavior can be modeled and studied. This dissertation presents such a framework. In this framework, guidance behavior is analyzed as the closed-loop dynamics of the whole agent-environment system. The resulting dynamics give rise to interaction patterns. The central points of this dissertation are that: first of all, these patterns, which can be explained in terms of symmetries that are inherent to the guidance behavior, provide building blocks for the organization of behavior; second, the existence of these patterns and humans' organization of their guidance behavior based on these patterns are the reasons that humans can generate successful behavior in spite of all the complexities involved in the planning and control. This dissertation first gives an overview of the challenges existing in both scientific endeavors, such as human and animal spatial behavior study, and engineering endeavors, such as autonomous guidance system design. It then lays out the foundation for our formal framework, which states that guidance behavior should be interpreted as the collection of the closed-loop dynamics resulting from the agent's interaction with the environment. The following, illustrated by examples of three different UAVs, shows that the study of the closed-loop dynamics should not be done without the consideration of vehicle dynamics, as is the common practice in some of the studies in both autonomous guidance and human behavior analysis. The framework, the core concepts of which are

  1. Growing interstellar molecules with ion-molecule reactions

    International Nuclear Information System (INIS)

    Bohme, D.K.

    1989-01-01

    Laboratory measurements of gas-phase ion-molecule reactions continue to provide important insights into the chemistry of molecular growth in interstellar environments. It is also true that the measurements are becoming more demanding as larger molecules capture our interest. While some of these measurements are motivated by current developments in chemical models of interstellar environments or by new molecular observations by astronomers, others explore novel chemistry which can lead to predictions of new interstellar molecules. Here the author views the results of some recent measurements, taken in the Ion Chemistry Laboratory at York University with the SIFT technique, which address some of the current needs of modellers and observers and which also provide some new fundamental insight into molecular growth, particularly when it occurs in the presence of large molecules such as PAH molecules which are now thought to have a major influence on the chemistry of interstellar environments in which they are present

  2. Non-chiral, auxetic system of noncentrosymmetric molecules in two dimensions

    International Nuclear Information System (INIS)

    Wojciechowski, K.W.

    2002-12-01

    A two-dimensional model of tri-atomic molecules (which 'atoms' are distributed on vertices of equilateral triangles, and which are further referred to as cyclic trimers) is solved exactly in the static (zero-temperature) limit for the nearest-neighbor site-site interactions. It is shown that the cyclic trimers (noncentrosymmetric by the definition) can form a mechanically stable and elastically isotropic non-chiral phase of negative Poisson ratio. The properties of the system are illustrated by three examples of the atom-atom interaction potentials: (i) the purely repulsive (n-inverse-power) potential, (ii) the purely attractive (n-power) potential and (iii) the Lennard-Jones-like potential which shows both the repulsive and the attractive part. The analytic form of the dependence of the Poisson ratio on the interatomic potential is obtained. It is shown that the Poisson ratio depends, in a universal way, only on the trimer anisotropy parameter both (1) in the limit of n → ∞ for the cases (i) and (ii), as well as (2) at the zero external pressure for any potential with a doubly differentiable minimum, the case (iii) is an example. (author)

  3. Rovibrational states of Wigner molecules in spherically symmetric confining potentials

    Energy Technology Data Exchange (ETDEWEB)

    Cioslowski, Jerzy [Institute of Physics, University of Szczecin, Wielkopolska 15, 70-451 Szczecin, Poland and Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Str. 38, D-01187 Dresden (Germany)

    2016-08-07

    The strong-localization limit of three-dimensional Wigner molecules, in which repulsively interacting particles are confined by a weak spherically symmetric potential, is investigated. An explicit prescription for computation of rovibrational wavefunctions and energies that are asymptotically exact at this limit is presented. The prescription is valid for systems with arbitrary angularly-independent interparticle and confining potentials, including those involving Coulombic and screened (i.e., Yukawa/Debye) interactions. The necessary derivations are greatly simplified by explicit constructions of the Eckart frame and the parity-adapted primitive wavefunctions. The performance of the new formalism is illustrated with the three- and four-electron harmonium atoms at their strong-correlation limits. In particular, the involvement of vibrational modes with the E symmetry is readily pinpointed as the origin of the “anomalous” weak-confinement behavior of the {sup 1}S{sub +} state of the four-electron species that is absent in its {sup 1}D{sub +} companion of the strong-confinement regime.

  4. How Confinement-Induced Structures Alter the Contribution of Hydrodynamic and Short-Ranged Repulsion Forces to the Viscosity of Colloidal Suspensions

    Directory of Open Access Journals (Sweden)

    Meera Ramaswamy

    2017-10-01

    Full Text Available Confined systems ranging from the atomic to the granular are ubiquitous in nature. Experiments and simulations of such atomic and granular systems have shown a complex relationship between the microstructural arrangements under confinement, the short-ranged particle stresses, and flow fields. Understanding the same correlation between structure and rheology in the colloidal regime is important due to the significance of such suspensions in industrial applications. Moreover, colloidal suspensions exhibit a wide range of structures under confinement that could considerably modify such force balances and the resulting viscosity. Here, we use a combination of experiments and simulations to elucidate how confinement-induced structures alter the relative contributions of hydrodynamic and short-range repulsive forces to produce up to a tenfold change in the viscosity. In the experiments we use a custom-built confocal rheoscope to image the particle configurations of a colloidal suspension while simultaneously measuring its stress response. We find that as the gap decreases below 15 particle diameters, the viscosity first decreases from its bulk value, shows fluctuations with the gap, and then sharply increases for gaps below 3 particle diameters. These trends in the viscosity are shown to strongly correlate with the suspension microstructure. Further, we compare our experimental results to those from two different simulations techniques, which enables us to determine the relative contributions of hydrodynamic and short-range repulsive stresses to the suspension rheology. The first method uses the lubrication approximation to find the hydrodynamic stress and includes a short-range repulsive force between the particles while the second is a Stokesian dynamics simulation that calculates the full hydrodynamic stress in the suspension. We find that the decrease in the viscosity at moderate confinements has a significant contribution from both the

  5. Design Guidance for New Windows | Efficient Windows Collaborative

    Science.gov (United States)

    Foundry Foundry New Construction Windows Window Selection Tool Selection Process Design Guidance Installation Replacement Windows Window Selection Tool Assessing Options Selection Process Design Guidance Installation Understanding Windows Benefits Design Considerations Measuring Performance Performance Standards

  6. Design Guidance for Replacement Windows | Efficient Windows Collaborative

    Science.gov (United States)

    Foundry Foundry New Construction Windows Window Selection Tool Selection Process Design Guidance Installation Replacement Windows Window Selection Tool Assessing Options Selection Process Design Guidance Installation Understanding Windows Benefits Design Considerations Measuring Performance Performance Standards

  7. 78 FR 25454 - Issuance of Final Guidance Publication

    Science.gov (United States)

    2013-05-01

    ... NIOSH-161-A] Issuance of Final Guidance Publication AGENCY: National Institute for Occupational Safety... Human Services (HHS). ACTION: Notice of issuance of final guidance publication. SUMMARY: The National...), announces the availability of the following publication: ``NIOSH Current Intelligence Bulletin 65...

  8. 77 FR 74194 - Issuance of Final Guidance Publication

    Science.gov (United States)

    2012-12-13

    ... NIOSH-238] Issuance of Final Guidance Publication AGENCY: National Institute for Occupational Safety and... Services (HHS). ACTION: Notice of issuance of final guidance publication. SUMMARY: The National Institute...), announces the availability of the following publication: NIOSH Alert entitled ``Preventing Occupational...

  9. 78 FR 13097 - Electric Power Research Institute; Seismic Evaluation Guidance

    Science.gov (United States)

    2013-02-26

    ... NUCLEAR REGULATORY COMMISSION [NRC-2013-0038] Electric Power Research Institute; Seismic... Electric Power Research Institute (EPRI)-1025287, ``Seismic Evaluation Guidance: Screening, Prioritization... guidance and clarification of an acceptable approach to assist nuclear power reactor licensees when...

  10. Enzyme Molecules in Solitary Confinement

    Directory of Open Access Journals (Sweden)

    Raphaela B. Liebherr

    2014-09-01

    Full Text Available Large arrays of homogeneous microwells each defining a femtoliter volume are a versatile platform for monitoring the substrate turnover of many individual enzyme molecules in parallel. The high degree of parallelization enables the analysis of a statistically representative enzyme population. Enclosing individual enzyme molecules in microwells does not require any surface immobilization step and enables the kinetic investigation of enzymes free in solution. This review describes various microwell array formats and explores their applications for the detection and investigation of single enzyme molecules. The development of new fabrication techniques and sensitive detection methods drives the field of single molecule enzymology. Here, we introduce recent progress in single enzyme molecule analysis in microwell arrays and discuss the challenges and opportunities.

  11. Organizing and addressing magnetic molecules.

    Science.gov (United States)

    Gatteschi, Dante; Cornia, Andrea; Mannini, Matteo; Sessoli, Roberta

    2009-04-20

    Magnetic molecules ranging from simple organic radicals to single-molecule magnets (SMMs) are intensively investigated for their potential applications in molecule-based information storage and processing. The goal of this Article is to review recent achievements in the organization of magnetic molecules on surfaces and in their individual probing and manipulation. We stress that the inherent fragility and redox sensitivity of most SMM complexes, combined with the noninnocent role played by the substrate, ask for a careful evaluation of the structural and electronic properties of deposited molecules going beyond routine methods for surface analysis. Detailed magnetic information can be directly obtained using X-ray magnetic circular dichroism or newly emerging scanning probe techniques with magnetic detection capabilities.

  12. Ion-Molecule Reaction Dynamics.

    Science.gov (United States)

    Meyer, Jennifer; Wester, Roland

    2017-05-05

    We review the recent advances in the investigation of the dynamics of ion-molecule reactions. During the past decade, the combination of single-collision experiments in crossed ion and neutral beams with the velocity map ion imaging detection technique has enabled a wealth of studies on ion-molecule reactions. These methods, in combination with chemical dynamics simulations, have uncovered new and unexpected reaction mechanisms, such as the roundabout mechanism and the subtle influence of the leaving group in anion-molecule nucleophilic substitution reactions. For this important class of reactions, as well as for many fundamental cation-molecule reactions, the information obtained with crossed-beam imaging is discussed. The first steps toward understanding micro-solvation of ion-molecule reaction dynamics are presented. We conclude with the presentation of several interesting directions for future research.

  13. Strategies for Structural Youth Unemployment: a Capability Approach for Guidance

    OpenAIRE

    Massimiliano Costa; Daniele Morselli; John Polesel; Suzanne Rice

    2015-01-01

    The aim of this article is to present an innovative approach for guidance. The article starts by introducing the structural reason of unemployment in Italy. It presents the Australian model of guidance and the new reforms on guidance which are being introduced in Italy. It then describes a Change Laboratory intervention carried in a vocational setting in Australia in 2012, which is proposed as model of guidance based on the capability approach.The different stakeholders actively participate i...

  14. Computed tomography guidance for skeletal biopsy

    International Nuclear Information System (INIS)

    Frager, D.H.; Goldman, M.J.; Elkin, C.M.; Cynamon, J.; Leeds, N.E.; Seimon, L.P.; Habermann, E.T.; Schreiber, K.; Freeman, L.M.

    1987-01-01

    Computed tomographic (CT) guided biopsy and abscess drainage of multiple organ systems have been well described. Reports of spinal and skeletal applications have been less common. This study describes the use of CT guidance in the biopsy of various skeletal lesions in 46 patients. Forty-one patients had skinny needle aspirations (18 or 22 gauge) and 23 patients had trephine core biopsies. Sites of the lesions included: thoracic spine - 15 patients, lumbosacral spine - 17 patients, bony pelvis - 6 patients, rib - 2 patients, and long bones - 6 patients. Fast scanners capable of rapid image reconstruction have overcome many constraints. With CT guidance, the physician who performs the procedure receives virtually no ionizing radiation. The exact location of the needle tip is accurately visualized in relation to the lesion being biopsied and to the vital organs. (orig.)

  15. Taxonometric Guidance for Developing Quality Assurance

    International Nuclear Information System (INIS)

    Thomadsen, Bruce; Lin, She-Woei

    2008-01-01

    A taxonomy is an ordered classification system. In error reduction analysis, an examination of the human failures that lead to an event often uses a taxonomy to classify the failures according to some aspect of their characteristics. These classifications provide insights into the forces that kept the persons involved from achieving their intended actions. They also can provide guidance for changing the situation to prevent failure in the future. For example, the corrective action would be different if a therapist pressed the wrong button because several buttons looked alike or they forgot which button to press. Different types of failures lead to particular types of remediation. Taxonomies can provide guidance in selecting between possible corrective actions

  16. Guidance and justification in particularistic ethics.

    Science.gov (United States)

    Kihlbom, U

    2000-10-01

    This paper argues that, contrary to a common line of criticism followed by scholars such as Helga Kuhse, a particularistic version of virtue ethics properly elaborated, can provide sound moral guidance and a satisfactory account for moral justification of our opinions regarding, for instance, health care practice. In the first part of the paper, three criteria for comparing normative theories with respect to action-guiding power are outlined, and it is argued that the presented particularistic version of virtue ethics actually can provide more guidance than the universalistic theories followed by Kuhse and others. In the second part of the paper it is claimed that universalist normative theories have serious problems accounting for the role that moral principles are supposed to play in the justification, of moral opinions, whereas the present version of virtue ethics accommodates a plausible alternative idea of justification without invoking moral principles or eschewing objectivity.

  17. River City High School Guidance Services: A Conceptual Model.

    Science.gov (United States)

    American Coll. Testing Program, Iowa City, IA.

    This model describes how the guidance staff at a hypothetical high school communicated the effectiveness of the guidance program to students, parents, teachers, and administrators. A description of the high school is presented, and guidance services and personnel are described. A conceptual model responding to student needs is outlined along with…

  18. 76 FR 411 - Regulatory Guidance Concerning Electronic Signatures and Documents

    Science.gov (United States)

    2011-01-04

    ... guidance, including memoranda and letters, may no longer be relied upon to the extent they are inconsistent... Concerning Electronic Signatures and Documents AGENCY: Federal Motor Carrier Safety Administration (FMCSA), DOT. ACTION: Notice of regulatory guidance. SUMMARY: FMCSA issues regulatory guidance concerning the...

  19. Adapting haptic guidance authority based on user grip

    NARCIS (Netherlands)

    Smisek, J.; Mugge, W.; Smeets, J.B.J.; Van Paassen, M.M.; Schiele, A

    2014-01-01

    Haptic guidance systems support the operator in task execution using additional forces on the input device. Scaling of the guidance forces determines the control authority of the support system. As task complexity may vary, one level of the guidance scaling may be insufficient, and adaptation of the

  20. Assessment of Adaptive Guidance for Responsive Launch Vehicles and Spacecraft

    Science.gov (United States)

    2009-04-29

    Figures 1 Earth centered inertial and launch plumbline coordinate systems . . . . . . . 7 2 Geodetic and geocentric latitude...Dramatically reduced reoccurring costs related to guidance. The same features of the closed-loop ascent guidance that provide operational flexibility...also result in greatly reduced need for human intervention. Thus the operational costs related to ascent guidance could be reduced to minimum