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Sample records for lymphendothelial gap formation

  1. Xanthohumol attenuates tumour cell-mediated breaching of the lymphendothelial barrier and prevents intravasation and metastasis.

    Science.gov (United States)

    Viola, Katharina; Kopf, Sabine; Rarova, Lucie; Jarukamjorn, Kanokwan; Kretschy, Nicole; Teichmann, Mathias; Vonach, Caroline; Atanasov, Atanas G; Giessrigl, Benedikt; Huttary, Nicole; Raab, Ingrid; Krieger, Sigurd; Strnad, Miroslav; de Martin, Rainer; Saiko, Philipp; Szekeres, Thomas; Knasmüller, Siegfried; Dirsch, Verena M; Jäger, Walter; Grusch, Michael; Dolznig, Helmut; Mikulits, Wolfgang; Krupitza, Georg

    2013-07-01

    Health beneficial effects of xanthohumol have been reported, and basic research provided evidence for anti-cancer effects. Furthermore, xanthohumol was shown to inhibit the migration of endothelial cells. Therefore, this study investigated the anti-metastatic potential of xanthohumol. MCF-7 breast cancer spheroids which are placed on lymphendothelial cells (LECs) induce "circular chemorepellent-induced defects" (CCIDs) in the LEC monolayer resembling gates for intravasating tumour bulks at an early step of lymph node colonisation. NF-κB reporter-, EROD-, SELE-, 12(S)-HETE- and adhesion assays were performed to investigate the anti-metastatic properties of xanthohumol. Western blot analyses were used to elucidate the mechanisms inhibiting CCID formation. Xanthohumol inhibited the activity of CYP, SELE and NF-kB and consequently, the formation of CCIDs at low micromolar concentrations. More specifically, xanthohumol affected ICAM-1 expression and adherence of MCF-7 cells to LECs, which is a prerequisite for CCID formation. Furthermore, markers of epithelial-to-mesenchymal transition (EMT) and of cell mobility such as paxillin, MCL2 and S100A4 were suppressed by xanthohumol. Xanthohumol attenuated tumour cell-mediated defects at the lymphendothelial barrier and inhibited EMT-like effects thereby providing a mechanistic explanation for the anti-intravasative/anti-metastatic properties of xanthohumol.

  2. Formation of Degenerate Band Gaps in Layered Systems

    Directory of Open Access Journals (Sweden)

    Alexey P. Vinogradov

    2012-06-01

    Full Text Available In the review, peculiarities of spectra of one-dimensional photonic crystals made of anisotropic and/or magnetooptic materials are considered. The attention is focused on band gaps of a special type—the so called degenerate band gaps which are degenerate with respect to polarization. Mechanisms of formation and properties of these band gaps are analyzed. Peculiarities of spectra of photonic crystals that arise due to the linkage between band gaps are discussed. Particularly, it is shown that formation of a frozen mode is caused by linkage between Brillouin and degenerate band gaps. Also, existence of the optical Borrmann effect at the boundaries of degenerate band gaps and optical Tamm states at the frequencies of degenerate band gaps are analyzed.

  3. Model of Layered Weld Formation Under Narrow Gap Pulse Welding

    Science.gov (United States)

    Krampit, A. G.

    2016-04-01

    The model parameters of narrow gap pulse welding can be divided into input, internal and output ones. The breadth of gap, that is, clearance breadth between upright edges is one of key parameters securing high quality of a weld joint. The paper presents theoretical outcomes for the model of layered weld formation under narrow gap pulse welding. Based on these studies is developed model of processes, which occur in the weld pool under pulse grove welding. It comprises the scheme of liquid metal motion in the weld pool, scheme of fusion with the side edge and in the bottom part, and the scheme of welding current impulse effect on the structure of a weld joint.

  4. Influence of composite insertion technique on gap formation

    Directory of Open Access Journals (Sweden)

    Neha Kapoor

    2016-01-01

    Full Text Available Aim: To compare newer bulk-fill composites with an incrementally filled composite for adaptability and subsequent gap formation at the pulpal floor. Materials and Methods: Class I cavities were prepared in 60 intact molars, with a shallow depression in the center of the pulpal floor. The samples were divided into four groups (n = 15, according to the material used; smart dentine replacement (SDR, SonicFill, Ever X Flow and Z350 XT, restored to a depth of 4 mm. Following thermocycling, samples were sectioned buccolingually and examined under a stereomicroscope. Seven samples from each group were coated with nail varnish except for approximately 1 mm around the tooth restoration junction. These samples were examined under stereomicroscope after staining with 2% buffered methylene blue dye. The remaining samples were examined under a scanning electron microscope for gap formation. The data were statistically analyzed using one-way ANOVA and post-hoc Bonferroni test. Results: SDR showed the significantly best adaptability as compared to both SonicFill and Ever X Flow (comparable. However, significantly least adaptive capacity was seen in the incrementally filled group (Z350 XT. Conclusion: Bulk-fill composites performed better than incremental composites, demonstrating better adaptability and less gap formation at the pulpal floor.

  5. Traction force dynamics predict gap formation in activated endothelium.

    Science.gov (United States)

    Valent, Erik T; van Nieuw Amerongen, Geerten P; van Hinsbergh, Victor W M; Hordijk, Peter L

    2016-09-10

    In many pathological conditions the endothelium becomes activated and dysfunctional, resulting in hyperpermeability and plasma leakage. No specific therapies are available yet to control endothelial barrier function, which is regulated by inter-endothelial junctions and the generation of acto-myosin-based contractile forces in the context of cell-cell and cell-matrix interactions. However, the spatiotemporal distribution and stimulus-induced reorganization of these integral forces remain largely unknown. Traction force microscopy of human endothelial monolayers was used to visualize contractile forces in resting cells and during thrombin-induced hyperpermeability. Simultaneously, information about endothelial monolayer integrity, adherens junctions and cytoskeletal proteins (F-actin) were captured. This revealed a heterogeneous distribution of traction forces, with nuclear areas showing lower and cell-cell junctions higher traction forces than the whole-monolayer average. Moreover, junctional forces were asymmetrically distributed among neighboring cells. Force vector orientation analysis showed a good correlation with the alignment of F-actin and revealed contractile forces in newly formed filopodia and lamellipodia-like protrusions within the monolayer. Finally, unstable areas, showing high force fluctuations within the monolayer were prone to form inter-endothelial gaps upon stimulation with thrombin. To conclude, contractile traction forces are heterogeneously distributed within endothelial monolayers and force instability, rather than force magnitude, predicts the stimulus-induced formation of intercellular gaps. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Gap formation in Danish beech (Fagus sylvatica) forests of low management intensity

    DEFF Research Database (Denmark)

    Ritter, Eva; Vesterdal, Lars

    2006-01-01

    WATBAL for one of the sites. Two forests were non-intervention forests (semi-natural and unmanaged), the third was subject to nature-based management. The study was intended to assess the range of effects of gap formation in forests of low management intensity. In the unmanaged and the nature......, measurements were carried out up to 29 months after gap formation. Average NO3-N concentrations in the gap were 19.3 mg NO3-N l(-1). Gap formation alone did not account for this high level, as concentrations were high also under closed canopy (average 12.4 mg NO3-N l(-1)). However, the gap had significantly....... In the semi-natural forest, advanced regeneration and lateral closure of the gap affected soil moisture levels in the gap in the last year of the study. Author Keywords: gaps; drainage fluxes; Fagus sylvatica L.; nitrate; soil moisture; soil solution; unmanaged forest ecosystems; WATBAL...

  7. Test Format and the Variation of Gender Achievement Gaps within the United States

    Science.gov (United States)

    Reardon, Sean; Fahle, Erin; Kalogrides, Demetra; Podolsky, Anne; Zarate, Rosalia

    2016-01-01

    Prior research demonstrates the existence of gender achievement gaps and the variation in the magnitude of these gaps across states. This paper characterizes the extent to which the variation of gender achievement gaps on standardized tests across the United States can be explained by differing state accountability test formats. A comprehensive…

  8. Dual channel formation in a laser-triggered spark gap

    Science.gov (United States)

    Kushner, M. J.; Kimura, W. D.; Ford, D. H.; Byron, S. R.

    1985-12-01

    During self-break in spark-gap switches, multiple streamers can form in close proximity to one another. The rate of expansion of these streamers is sufficiently fast that they can interact during the current pulse. To help understand how these closely spaced, expanding spark columns interact, a laser-triggered spark gap has been studied in which two parallel columns (separation 1.3 mm) are simultaneously preionized, resulting in a pair of nearly identical, axisymmetric spark columns. The spark gap (electrode separation 1.2 cm) switches a 100 ns, 40-60 kV, 12-20 kA, 1.5 Ω waterline. Interferograms of the expanding arc channels are obtained with a laser interferometer having a time and spatial resolution of 5 ns and 10 μm, respectively. Voltage and current were measured with an internal capacitive-voltage divider and a current viewing resistor. The interferograms show that for initially identical axisymmetric columns, the individual channels do not merge into a single larger axisymmetric spark column. Instead, regions of high gas density remain inside the combined column long into the recovery period. The columns also do not remain axisymmetric as they grow, indicating a long-range interaction between the channels. The voltage drop and resistance of the dual channel spark gaps changes by less than 15% from that of a single spark channel. A scaling model is presented to explain the resistance measurements and to predict the change in resistance for multichannel spark gaps.

  9. Band gap formation and control in coupled periodic ferromagnetic structures

    Science.gov (United States)

    Morozova, M. A.; Sharaevskaya, A. Yu.; Sadovnikov, A. V.; Grishin, S. V.; Romanenko, D. V.; Beginin, E. N.; Sharaevskii, Yu. P.; Nikitov, S. A.

    2016-12-01

    We demonstrate theoretically and experimentally the formation of additional bandgaps in the spectrum of spin waves in coupled magnonic crystals. We present the analytical model, which reveals the mechanism of bandgaps formation in coupled structures. In particular, the formation of one, two, or three bandgaps in the region of the first Bragg resonance is demonstrated and control of its characteristics by the variation of the complex coupling coefficient between magnonic crystals is shown. The spatially-resolved Brillouin light scattering spectroscopy and microwave measurements demonstrate the bandgap splitting in the spin-wave spectrum. The main advantage of proposed coupled structure, as compared to the conventional magnonic crystal, is the tunability of multiple bandgaps in the spin-wave spectrum, which enables potential applications in the frequency selective magnonic devices.

  10. Lobatin B inhibits NPM/ALK and NF-κB attenuating anaplastic-large-cell-lymphomagenesis and lymphendothelial tumour intravasation.

    Science.gov (United States)

    Kiss, Izabella; Unger, Christine; Huu, Chi Nguyen; Atanasov, Atanas Georgiev; Kramer, Nina; Chatruphonprasert, Waranya; Brenner, Stefan; McKinnon, Ruxandra; Peschel, Andrea; Vasas, Andrea; Lajter, Ildiko; Kain, Renate; Saiko, Philipp; Szekeres, Thomas; Kenner, Lukas; Hassler, Melanie R; Diaz, Rene; Frisch, Richard; Dirsch, Verena M; Jäger, Walter; de Martin, Rainer; Bochkov, Valery N; Passreiter, Claus M; Peter-Vörösmarty, Barbara; Mader, Robert M; Grusch, Michael; Dolznig, Helmut; Kopp, Brigitte; Zupko, Istvan; Hohmann, Judit; Krupitza, Georg

    2015-01-28

    An apolar extract of the traditional medicinal plant Neurolaena lobata inhibited the expression of the NPM/ALK chimera, which is causal for the majority of anaplastic large cell lymphomas (ALCLs). Therefore, an active principle of the extract, the furanoheliangolide sesquiterpene lactone lobatin B, was isolated and tested regarding the inhibition of ALCL expansion and tumour cell intravasation through the lymphendothelium. ALCL cell lines, HL-60 cells and PBMCs were treated with plant compounds and the ALK inhibitor TAE-684 to measure mitochondrial activity, proliferation and cell cycle progression and to correlate the results with protein- and mRNA-expression of selected gene products. Several endpoints indicative for cell death were analysed after lobatin B treatment. Tumour cell intravasation through lymphendothelial monolayers was measured and potential causal mechanisms were investigated analysing NF-κB- and cytochrome P450 activity, and 12(S)-HETE production. Lobatin B inhibited the expression of NPM/ALK, JunB and PDGF-Rβ, and attenuated proliferation of ALCL cells by arresting them in late M phase. Mitochondrial activity remained largely unaffected upon lobatin B treatment. Nevertheless, caspase 3 became activated in ALCL cells. Also HL-60 cell proliferation was attenuated whereas PBMCs of healthy donors were not affected by lobatin B. Additionally, tumour cell intravasation, which partly depends on NF-κB, was significantly suppressed by lobatin B most likely due to its NF-κB-inhibitory property. Lobatin B, which was isolated from a plant used in ethnomedicine, targets malignant cells by at least two properties: I) inhibition of NPM/ALK, thereby providing high specificity in combating this most prevalent fusion protein occurring in ALCL; II) inhibition of NF-κB, thereby not affecting normal cells with low constitutive NF-κB activity. This property also inhibits tumour cell intravasation into the lymphatic system and may provide an option to manage this

  11. Influence of elasticity on gap formation in a lining technique with flowable composite.

    Science.gov (United States)

    Cho, Eitetsu; Chikawa, Hirokazu; Kishikawa, Ryuzo; Inai, Norimichi; Otsuki, Masayuki; Foxton, Richard M; Tagami, Junji

    2006-09-01

    The purpose of this study was to investigate the effect of flowable composites as liners for direct composite restorations, with key focus on the elastic moduli of flowable and condensable composites. After treating the composite mold cavity surface with an adhesive system, one of the flowable composites was placed as a 1 mm-thick layer on the cavity floor and irradiated for 20 seconds. The rest of cavity was subsequently filled with a condensable composite and irradiated for 40 seconds. Gap formation at both interfaces--between the cavity floor and flowable composite, and between the flowable and condensable composites--was examined. No gaps were detected at the interface between the cavity floor and flowable composite. Gap percentage at the interface between the flowable and condensable composites was dependent on the difference in elastic modulus. It was concluded that flowable composite with high elastic modulus could inhibit gap formation between flowable and condensable composites.

  12. Nonlinear sub-cyclotron resonance as a formation mechanism for gaps in banded chorus

    CERN Document Server

    Fu, Xiangrong; Dong, Chuanfei; Gary, S Peter

    2015-01-01

    An interesting characteristic of magnetospheric chorus is the presence of a frequency gap at $\\omega \\simeq 0.5\\Omega_e$, where $\\Omega_e$ is the electron cyclotron angular frequency. Recent chorus observations sometimes show additional gaps near $0.3\\Omega_e$ and $0.6\\Omega_e$. Here we present a novel nonlinear mechanism for the formation of these gaps using Hamiltonian theory and test-particle simulations in a homogeneous, magnetized, collisionless plasma. We find that an oblique whistler wave with frequency at a fraction of the electron cyclotron frequency can resonate with electrons, leading to effective energy exchange between the wave and particles.

  13. Bulk-fill resin composites: polymerization contraction, depth of cure, and gap formation.

    Science.gov (United States)

    Benetti, A R; Havndrup-Pedersen, C; Honoré, D; Pedersen, M K; Pallesen, U

    2015-01-01

    The bulk-filling of deep, wide dental cavities is faster and easier than traditional incremental restoration. However, the extent of cure at the bottom of the restoration should be carefully examined in combination with the polymerization contraction and gap formation that occur during the restorative procedure. The aim of this study, therefore, was to compare the depth of cure, polymerization contraction, and gap formation in bulk-fill resin composites with those of a conventional resin composite. To achieve this, the depth of cure was assessed in accordance with the International Organization for Standardization 4049 standard, and the polymerization contraction was determined using the bonded-disc method. The gap formation was measured at the dentin margin of Class II cavities. Five bulk-fill resin composites were investigated: two high-viscosity (Tetric EvoCeram Bulk Fill, SonicFill) and three low-viscosity (x-tra base, Venus Bulk Fill, SDR) materials. Compared with the conventional resin composite, the high-viscosity bulk-fill materials exhibited only a small increase (but significant for Tetric EvoCeram Bulk Fill) in depth of cure and polymerization contraction, whereas the low-viscosity bulk-fill materials produced a significantly larger depth of cure and polymerization contraction. Although most of the bulk-fill materials exhibited a gap formation similar to that of the conventional resin composite, two of the low-viscosity bulk-fill resin composites, x-tra base and Venus Bulk Fill, produced larger gaps.

  14. Formation of interlayer gap and control of interlayer burr in dry drilling of stacked aluminum alloy plates

    Directory of Open Access Journals (Sweden)

    Tian Wei

    2016-02-01

    Full Text Available In aircraft assembly, interlayer burr formation in dry drilling of stacked metal materials is a common problem. Traditional manual deburring operation seriously affects the assembly quality and assembly efficiency, is time-consuming and costly, and is not conducive to aircraft automatic assembly based on industrial robot. In this paper, the formation of drilling exit burr and the influence of interlayer gap on interlayer burr formation were studied, and the mechanism of interlayer gap formation in drilling stacked aluminum alloy plates was investigated, a simplified mathematical model of interlayer gap based on the theory of plates and shells and finite element method was established. The relationship between interlayer gap and interlayer burr, as well as the effect of feed rate and pressing force on interlayer burr height and interlayer gap was discussed. The result shows that theoretical interlayer gap has a positive correlation with interlayer burr height and preloading pressing force is an effective method to control interlayer burr formation.

  15. Effects of flowable resin on bond strength and gap formation in Class I restorations.

    Science.gov (United States)

    Miguez, Patricia A; Pereira, Patricia N R; Foxton, Richard M; Walter, Ricardo; Nunes, Mauro F; Swift, Edward J

    2004-11-01

    This study measured resin/dentin bond strengths and evaluated gap formation at the pulpal floor of occlusal composite restorations using a flowable resin as a liner with either bulk or incremental placement of the restorative composite. Class I occlusal preparations were made in 16 extracted molars, and were randomly divided into two groups for restoration using either One-Step adhesive (OS, BISCO) and Renew composite (RW, BISCO) or OptiBond SOLO adhesive (SOLO, Kerr) and Herculite XRV composite (XRV, Kerr). A flowable resin [AEliteFlo (AE, BISCO) or Revolution (RV, Kerr)] was applied as a liner in half of the specimens of each group. The lined and unlined groups were restored with composite cured in bulk, or cured in 1.5 mm increments. After 24 h in water, the teeth were sectioned into 0.7-mm thick slabs and were examined with an optical microscope (400 x) to determine the presence of internal resin-dentin gaps. The gap-free specimens were trimmed and were subjected to microtensile bond strength testing. Specimens that contained gaps had Knoop hardness of the restorative material measured. All incrementally filled restorations were well adapted to the pulpal floor but nearly all bulk-cured specimens had gaps between the flowable and the hybrid composites. The use of a flowable resin increased the bond strength of OS, but not SOLO. The incremental technique prevented gap formation regardless of the use of a flowable resin. In contrast, the use of a flowable composite did not guarantee gap-free restorations or improved bond strength of resin to dentin in bulk-filled restorations.

  16. Gap formation by inclined massive planets in locally isothermal three-dimensional discs

    Science.gov (United States)

    Chametla, Raúl O.; Sánchez-Salcedo, F. J.; Masset, F. S.; Hidalgo-Gámez, A. M.

    2017-07-01

    We study gap formation in gaseous protoplanetary discs by a Jupiter mass planet. The planet's orbit is circular and inclined relative to the mid-plane of the disc. We use the impulse approximation to estimate the gravitational tidal torque between the planet and the disc, and infer the gap profile. For low-mass discs, we provide a criterion for gap opening when the orbital inclination is ≤30°. Using the fargo3d code, we simulate the disc response to an inclined massive planet. The dependence of the depth and width of the gap obtained in the simulations on the inclination of the planet is broadly consistent with the scaling laws derived in the impulse approximation. Although we mainly focus on planets kept on fixed orbits, the formalism permits to infer the temporal evolution of the gap profile in the cases where the inclination of the planet changes with time. This study may be useful to understand the migration of massive planets on inclined orbit, because the strength of the interaction with the disc depends on whether a gap is opened or not.

  17. Erythrocyte migration and gap formation in rabbit blood clots in vitro.

    Science.gov (United States)

    Ueki, T; Yazama, F; Horiuchi, T; Yamada, M

    2008-04-01

    Thrombolytic agents must be carried by the blood circulation to thrombi to exert their functions. Structural gaps exist between blood vessels and thrombi or in the area surrounding thrombi. Therefore, information about fundamental gap formation at thrombotic areas is critically important for thrombolytic therapy. We previously reported that t-PA accelerates the activities of bovine erythrocytes and hemoglobin (Hb) towards bovine plasminogen activation. Here, we examined gap generation by observing morphological changes during thrombolytic processes in rabbit blood clots deformation of erythrocytes from blood clots and Hb transfer from erythrocytes to serum in vitro. Rabbit venous blood samples (1 ml) were stored under sterile conditions in glass tubes at 37 degrees C for 2, 24, 48 h, 1, and 2 weeks. We examined clot diameter, erythrocyte diameter and number as well as Hb volume in the serum, as well as histological changes in the clots. The diameter of blood clots did not change until 2 weeks after sampling. Erythrocyte diameter decreased within 48 h and at 2 weeks after sampling at the clot surface (p erythrocytes in the serum started to increase starting from 24 h after sampling (p erythrocyte envelope became disrupted and cytoplasm started to flow through pores into the serum at 24 h. The results indicated that blood clots are reduced due to clot retraction, erythrocyte dissociation and cytoplasm leakage without a distinct fibrinolytic reaction. These results indicated that gaps start to form between 2 and 24 h after blood clotting.

  18. Gap formation processes in a high-density plasma opening switch

    Science.gov (United States)

    Grossmann, J. M.; Swanekamp, S. B.; Ottinger, P. F.; Commisso, R. J.; Hinshelwood, D. D.; Weber, B. V.

    1995-01-01

    A gap opening process in plasma opening switches (POS) is examined with the aid of numerical simulations. In these simulations, a high density (ne=1014-5×1015 cm-3) uniform plasma initially bridges a small section of the coaxial transmission line of an inductive energy storage generator. A short section of vacuum transmission line connects the POS to a short circuit load. The results presented here extend previous simulations in the ne=1012-1013 cm-3 density regime. The simulations show that a two-dimensional (2-D) sheath forms in the plasma near a cathode. This sheath is positively charged, and electrostatic sheath potentials that are large compared to the anode-cathode voltage develop. Initially, the 2-D sheath is located at the generator edge of the plasma. As ions are accelerated out of the sheath, it retains its original 2-D structure, but migrates axially toward the load creating a magnetically insulated gap in its wake. When the sheath reaches the load edge of the POS, the POS stops conducting current and the load current increases rapidly. At the end of the conduction phase a gap exists in the POS whose size is determined by the radial dimensions of the 2-D sheath. Simulations at various plasma densities and current levels show that the radial size of the gap scales roughly as B/ne, where B is the magnetic field. The results of this work are discussed in the context of long-conduction-time POS physics, but exhibit the same physical gap formation mechanisms as earlier lower density simulations more relevant to short-conduction-time POS.

  19. Interfering amino terminal peptides and functional implications for heteromeric gap junction formation

    Directory of Open Access Journals (Sweden)

    Richard David Veenstra

    2013-05-01

    Full Text Available Connexin43 (Cx43 is widely expressed in many different tissues of the human body. In cells of some organs, Cx43 is co-expressed with other connexins (Cx, including Cx46 and Cx50 in lens, Cx40 in atrium, Purkinje fibers, and the blood vessel wall, Cx45 in heart, and Cx37 in the ovary. Interactions with the co-expressed connexins may have profound functional implications. The abilities of Cx37, Cx45, Cx46, and Cx50 to function in heteromeric gap junction combinations with Cx43 are well documented. Different studies disagree regarding the ability of Cx43 and Cx40 to produce functional heteromeric gap junctions with each other. We review previous studies regarding the heteromeric interactions of Cx43. The possibility of negative functional interactions between the cytoplasmic pore-forming amino terminal (NT domains of these connexins was assessed using pentameric connexin sequence-specific NT domain (iNT peptides applied to cells expressing homomeric Cx40, Cx37, Cx45, Cx46, and Cx50 gap junctions. A Cx43 iNT peptide corresponding to amino acids 9 to 13 (Ac-KLLDK-NH2 specifically inhibited the electrical coupling of Cx40 gap junctions in a transjunctional (Vj voltage-dependent manner without affecting the function of homologous Cx37, Cx46, Cx50, and Cx45 gap junctions. A Cx40 iNT (Ac-EFLEE-OH peptide counteracted the Vj-dependent block of Cx40 gap junctions, whereas a similarly charged Cx50 iNT (Ac-EEVNE-OH peptide did not, suggesting that these NT domain interactions are not solely based on electrostatics. These data are consistent with functional Cx43 heteromeric gap junction formation with Cx37, Cx45, Cx46, and Cx50 and suggest that Cx40 uniquely experiences functional suppressive interactions with a Cx43 NT domain sequence. These findings present unique functional implications about the heteromeric interactions between Cx43 and Cx40 that may influence cardiac conduction in atrial myocardium and the specialized conduction system.

  20. Gap formation and interfacial heat transfer in alloy 718 investment castings

    Energy Technology Data Exchange (ETDEWEB)

    Sahai, V.; Overfelt, R.A. [Auburn Univ., AL (United States). Space Power Inst.

    1995-12-31

    Investment casting foundries increasingly rely on numerical simulations of their casting processes to enhance quality and reduce costs. An important aspect of numerical simulations is the interfacial heat transfer between the solidifying metal and the mold. The contact conductance varies during solidification as the mold expands and the metal shrinks, leading to the formation of a gap and significantly reduced contact conductance. Very little data are available for the estimation of contact conductance, especially for the superalloys used in the aerospace industry. This work reports on experimental and numerical results for the determination of contact conductance for an axi-symmetric casting of alloy 718. The heat transfer code TOPAZ2D in conjunction with Beck`s method was used for the numerical simulation of this inverse heat transfer problem. The effects of variation of mold properties and thermocouple locations on contact conductance are considered. A relationship between the varying interfacial heat transfer and the formation of gaps is also examined and compared to actual measured values determined by X-ray radiography.

  1. Formation of interlayer gap and control of interlayer burr in dry drilling of stacked aluminum alloy plates

    Institute of Scientific and Technical Information of China (English)

    Tian Wei; Hu Jian; Liao Wenhe; Bu Yin; Zhang Lin

    2016-01-01

    In aircraft assembly, interlayer burr formation in dry drilling of stacked metal materials is a common problem. Traditional manual deburring operation seriously affects the assembly qual-ity and assembly efficiency, is time-consuming and costly, and is not conducive to aircraft automatic assembly based on industrial robot. In this paper, the formation of drilling exit burr and the influ-ence of interlayer gap on interlayer burr formation were studied, and the mechanism of interlayer gap formation in drilling stacked aluminum alloy plates was investigated, a simplified mathematical model of interlayer gap based on the theory of plates and shells and finite element method was established. The relationship between interlayer gap and interlayer burr, as well as the effect of feed rate and pressing force on interlayer burr height and interlayer gap was discussed. The result shows that theoretical interlayer gap has a positive correlation with interlayer burr height and preloading pressing force is an effective method to control interlayer burr formation.

  2. Gaps in the HD169142 protoplanetary disk revealed by polarimetric imaging: Signs of ongoing planet formation?

    CERN Document Server

    Quanz, Sascha P; Buenzli, Esther; Garufi, Antonio; Schmid, Hans Martin; Wolf, Sebastian

    2013-01-01

    We present H-band VLT/NACO polarized light images of the Herbig Ae/Be star HD169142 probing its protoplanetary disk as close as ~0.1" to the star. Our images trace the face-on disk out to ~1.7" (~250 AU) and reveal distinct sub-structures for the first time: 1) the inner disk (<20 AU) appears to be depleted in scattering dust grains; 2) an unresolved disk rim is imaged at ~25 AU; 3) an annular gap extends from ~40 - 70 AU; 4) local brightness asymmetries are found on opposite sides of the annular gap. We discuss different explanations for the observed morphology among which ongoing planet formation is a tempting - but yet to be proven - one. Outside of ~85 AU the surface brightness drops off roughly r^{-3.3}, but describing the disk regions between 85-120 AU / 120-250 AU separately with power-laws r^{-2.6} / r^{-3.9} provides a better fit hinting towards another discontinuity in the disk surface. The flux ratio between the disk integrated polarized light and the central star is ~4.1 * 10^{-3}. Finally, com...

  3. The Role of Short-Range Order and Hyperuniformity in the Formation of Band Gaps in Disordered Photonic Materials

    CERN Document Server

    Froufe-Pérez, Luis S; Damasceno, Pablo F; Muller, Nicolas; Haberko, Jakub; Glotzer, Sharon C; Scheffold, Frank

    2016-01-01

    We study photonic band gap formation in two-dimensional high refractive index disordered ma- terials where the dielectric structure is derived from packing disks in real and reciprocal space. Numerical calculations of the photonic density of states demonstrate the presence of a band gap for all polarizations in both cases. We find that the band gap width is controlled by the increase in positional correlation inducing short-range order and hyperuniformity concurrently. Our findings suggest that the optimization of short-range order, in particular the tailoring of Bragg scattering at the isotropic Brillouin zone, are of key importance for designing disordered PBG materials.

  4. Formation of striations in large-gap coplanar dielectric barrier discharge

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Xiaofei [School of Physics, Beijing Institute of Technology, Beijing 100081 (China); He, Feng, E-mail: hefeng@bit.edu.cn [School of Physics, Beijing Institute of Technology, Beijing 100081 (China); Ouyang, Jiting [School of Physics, Beijing Institute of Technology, Beijing 100081 (China)

    2012-06-04

    Striations in a large-gap coplanar dielectric barrier discharge (DBD) have been investigated by experiment and numerical simulation. The discharge current was measured and the images of infra-red (IR) radiation striation were obtained by an intensified charge-coupled device (ICCD) camera with nanosecond exposure time. The discharge processes are simulated by particle-in-cell/Monte Carlo collision (PIC/MCC) code. The calculated current and the distribution of Xe{sup ⁎} during a single pulse were compared with the experiment. The results show that there are two series of striations corresponding to two stages of discharge. The striations of the second stage are generated as the potential changed remarkably, while the distribution of surface charge almost keeps unchanged. The electric field induced by the space charges plays a key role in the formation of the striations. The stratified wall charge is only a consequence of the stratified spatial field and the striations. -- Highlights: ► IR radiation images of striations were compared with PIC/MCC simulation results. ► Space charge plays a key role in striation formation. ► Stratified wall charge is considered as a consequence of the striations.

  5. Extracellular domains play different roles in gap junction formation and docking compatibility.

    Science.gov (United States)

    Bai, Donglin; Wang, Ao Hong

    2014-02-15

    GJ (gap junction) channels mediate direct intercellular communication and play an important role in many physiological processes. Six connexins oligomerize to form a hemichannel and two hemichannels dock together end-to-end to form a GJ channel. Connexin extracellular domains (E1 and E2) have been shown to be important for the docking, but the molecular mechanisms behind the docking and formation of GJ channels are not clear. Recent developments in atomic GJ structure and functional studies on a series of connexin mutants revealed that E1 and E2 are likely to play different roles in the docking. Non-covalent interactions at the docking interface, including hydrogen bonds, are predicted to form between interdocked extracellular domains. Protein sequence alignment analysis on the docking compatible/incompatible connexins indicate that the E1 domain is important for the formation of the GJ channel and the E2 domain is important in the docking compatibility in heterotypic channels. Interestingly, the hydrogen-bond forming or equivalent residues in both E1 and E2 domains are mutational hot spots for connexin-linked human diseases. Understanding the molecular mechanisms of GJ docking can assist us to develop novel strategies in rescuing the disease-linked connexin mutants.

  6. Effect of pre-heating composite resin on gap formation at three different temperatures

    Directory of Open Access Journals (Sweden)

    Nilabh Choudhary

    2011-01-01

    Full Text Available Aim: The study aims to evaluate and compare total gap surface area formed after restoration of class II cavities with Filtek Z350 and P60 at room temperature, 37°C and 54°C. Materials and Methods: Thirty extracted maxillary and mandibular molars were taken and divided into six groups of five teeth each. Standardized class II cavities were made and were restored with Filtek Z350 and P60, both at room temperature, 37°C and 54°C. Group 1(a was restored with Filtek Z350 at room temperature, Group 1(b with Filtek Z350 at 37°C and Group 1(c with Filtek Z350 at 54°C. Group 2(a was restored with P60 at room temperature, Group 2(b with P60 at 37°C and Group 2(c with P60 at 54°C. After storing the samples in distilled water at room temperature for 48 hours, longitudinal sectioning was done to obtain tooth restoration interface. The interfaces were then examined under compound light microscope with digital output and analyzed using Image J analysis software. Results: The results demonstrated better adaptation and less total gap area formation at 54°C as compared to room temperature and 37°C. Conclusions: Based on the results of this study, it is suggested that use of P60 is better suited for posterior restorations at 54°C as compared to Filtek Z350 universal nanohybrid at room temperature.

  7. Species diversity and regeneration of old-growth seasonally dry Shorea robusta forests following gap formation

    Institute of Scientific and Technical Information of China (English)

    Indra Prasad Sapkota; Mulualem Tigabu; Per Christer Odén

    2009-01-01

    Diversity and regeneration of woody species were investigated in two ecological niches viz. gap and intact vegetation in old-growth seasonally dry Shorea robusta (Gaertn. f.) forests in Nepal. We also related varieties of diversity measures and regeneration attributes to gap characteristics. Stem density of tree and shrub components is higher in the gap than in the intact vegetation. Seedling densities of S. robusta and Terminalia alata (B. Heyne ex Roth.) are higher in the gap than in the intact vegetation, while contrary result is observed for T. bellirica (Gaertn. ex Roxb.) and Syzigium cumini (L. Skeels) in term of seedling density. The complement of Simpson index, Evenness index, and species-individual ratio in the seedling layer are lower in the gap than the intact vegetation. Gap size can explain species richness and species establishment rate. Gaps created by multiple tree falls in different years have higher seedling density of S. robusta than gaps created by single and/or multiple tree falls in the same year. In conclusion, gaps maintain species diversity by increasing seedling density, and favor regeneration of Sal forests. In addition to gap size, other gap attributes also affect species diversity and regeneration.

  8. Gap Junction in the Teleost Fish Lineage: Duplicated Connexins May Contribute to Skin Pattern Formation and Body Shape Determination.

    Science.gov (United States)

    Watanabe, Masakatsu

    2017-01-01

    Gap junctions are intercellular channels that allow passage of ions and small molecules between adjacent cells. Gap junctions in vertebrates are composed of connexons, which are an assembly of six proteins, connexins. Docking of two connexons on the opposite cell surfaces forms a gap junction between the cytoplasm of two neighboring cells. Connexins compose a family of structurally related four-pass transmembrane proteins. In mammals, there are ~20 connexins, each of which contributes to unique permeability of gap junctions, and mutations of some connexin-encoding genes are associated with human diseases. Zebrafish has been predicted to contain 39 connexin-encoding genes; the high number can be attributed to gene duplication during fish evolution, which resulted in diversified functions of gap junctions in teleosts. The determination of body shapes and skin patterns in animal species is an intriguing question. Mathematical models suggest principle mechanisms explaining the diversification of animal morphology. Recent studies have revealed the involvement of gap junctions in fish morphological diversity, including skin pattern formation and body shape determination. This review focuses on connexins in teleosts, which are integrated in the mathematical models explaining morphological diversity of animal skin patterns and body shapes.

  9. Analysis of gap formation at tooth-composite resin interface: effect of C-factor and light-curing protocol

    Directory of Open Access Journals (Sweden)

    Gustavo Oliveira dos Santos

    2007-08-01

    Full Text Available OBJECTIVE: The aim of this study was to evaluate the effect of C-factor and light-curing protocol on gap formation in composite resin restorations. Material and METHODS: Cylindrical cavities with 5.0 mm diameter and three different depths (A=1.0, B=2.0 and C=3.0 mm were prepared on the occlusal surface of 30 human molars and restored in a single increment with P 60. The composite resin was light-cured according to two protocols: standard - 850 mW/cm² / 20 s and gradual - 100 up to 1000 mW/cm² / 10 s + 1000 mW/cm² / 10 s. After storage in distilled water (37°C/7 days, the restorations were cut into three slices in a buccolingual direction and the gap widths were analyzed using a 3D-scanning system. The data were submitted to ANOVA and Student-Newman-Keuls test (alpha=0.05. RESULTS: ANOVA detected a significant influence for the C-factor and light-curing protocol as independent factors, and for the double interaction C-factor vs. light-curing protocol. Cavities with higher C-factor presented the highest gap formation. The gradual light-curing protocol led to smaller gap formation at cavity interfaces. CONCLUSIONS: The findings of this study suggest that the C-factor played an essential role in gap formation. The gradual light-curing protocol may allow relaxation of composite resin restoration during polymerization reaction.

  10. Functional consequences of heterogeneous gap junction channel formation and its influence in health and disease.

    Science.gov (United States)

    Cottrell, G Trevor; Burt, Janis M

    2005-06-10

    The capacity of multiple connexins to hetero-oligomerize into functional heterogeneous gap junction channels has been demonstrated in vivo, in vitro, and in nonmammalian expression systems. These heterogeneous channels display gating activity, channel conductances, selectivity and regulatory behaviors that are sometimes not predicted by the behaviors of the corresponding homogeneous channels. Such observations suggest that heteromerization of gap junction proteins offers an efficient cellular strategy for finely regulating cell-to-cell communication. The available evidence strongly indicates that heterogeneous gap junction assembly is important to normal growth and differentiation, and may influence the appearance of several disease states. Definitive evidence that heterogeneous gap junction channels differentially regulate electrical conduction in excitable cells is absent. This review examines the prevalence, regulation, and implications of gap junction channel hetero-oligomerization.

  11. Anisotropic magnetic properties and superzone gap formation in CeGe single crystal.

    Science.gov (United States)

    Das, Pranab Kumar; Kumar, Neeraj; Kulkarni, R; Dhar, S K; Thamizhavel, A

    2012-04-11

    Single crystals of CeGe and its non-magnetic analog LaGe have been grown by the Czochralski method. The CeGe compound crystallizes in the orthorhombic FeB-type crystal structure with the space group Pnma (#62). The anisotropic magnetic properties have been investigated for well oriented single crystals by measuring the magnetic susceptibility, electrical resistivity and heat capacity. It has been found that CeGe orders antiferromagnetically at 10.5 K. Both transport and magnetic studies have revealed large anisotropy, reflecting the orthorhombic crystal structure. The magnetization data at 1.8 K reveal metamagnetic transitions along the [010] direction at 4.8 and 6.4 T and along the [100] direction at a critical field of 10.7 T, while the magnetization along the [001] direction increases linearly without any anomaly up to a field of 16 T. From the magnetic susceptibility and the magnetization measurements it has been found that the [010] direction is the easy axis of magnetization. The electrical resistivity along the three crystallographic directions exhibits an upturn at T(N), indicating superzone gap formation below T(N) in this compound. We have performed crystal electric field analysis on the magnetic susceptibility and the heat capacity data and found that the ground state is a doublet, and the energies of splitting from the ground state to the first and second excited doublet states were estimated to be 39 and 111 K, respectively.

  12. Coherent Synchrotron-Based Micro-Imaging Employed for Studies of Micro-Gap Formation in Dental Implants

    Science.gov (United States)

    Rack, T.; Zabler, S.; Rack, A.; Stiller, M.; Riesemeier, H.; Cecilia, A.; Nelson, K.

    2011-09-01

    Biocompatible materials such as titanium are regularly applied in oral surgery. Titanium-based implants for the replacement of missing teeth demand a high mechanical precision in order to minimize micro-bacterial leakage, especially when two-piece concepts are used. Synchrotron-based hard x-ray radiography, unlike conventional laboratory radiography, allows high spatial resolution in combination with high contrast even when micro-sized features in such highly attenuating objects are visualized. Therefore, micro-gap formation at interfaces in two-piece dental implants with the sample under different mechanical loads can be studied. We show the existence of micro-gaps in implants with conical connections and study the mechanical behavior of the mating zone of conical implants during loading. The micro-gap is a potential source of implant failure, i.e., bacterial leakage, which can be a stimulus for an inflammatory process.

  13. Vitamin D3 regulates the formation and degradation of gap junctions in androgen-responsive human prostate cancer cells.

    Directory of Open Access Journals (Sweden)

    Linda Kelsey

    Full Text Available 1α-25(OH2 vitamin D3 (1-25D, an active hormonal form of Vitamin D3, is a well-known chemopreventive and pro-differentiating agent. It has been shown to inhibit the growth of several prostate cancer cell lines. Gap junctions, formed of proteins called connexins (Cx, are ensembles of cell-cell channels, which permit the exchange of small growth regulatory molecules between adjoining cells. Cell-cell communication mediated by gap junctional channels is an important homeostatic control mechanism for regulating cell growth and differentiation. We have investigated the effect of 1-25D on the formation and degradation of gap junctions in an androgen-responsive prostate cancer cell line, LNCaP, which expresses retrovirally-introduced Cx32. Connexin32 is expressed by the luminal and well-differentiated cells of normal prostate and prostate tumors. Our results document that 1-25D enhances the expression of Cx32 and its subsequent assembly into gap junctions. Our results further show that 1-25D prevents androgen-regulated degradation of Cx32, post-translationally, independent of androgen receptor (AR-mediated signaling. Finally, our findings document that formation of gap junctions sensitizes Cx32-expressing LNCaP cells to the growth inhibitory effects of 1-25D and alters their morphology. These findings suggest that the growth-inhibitory effects of 1-25D in LNCaP cells may be related to its ability to modulate the assembly of Cx32 into gap junctions.

  14. Geochemical factors promoting die-back gap formation in colonizing patches of Spartina densiflora in an irregularly flooded marsh

    Science.gov (United States)

    Mirlean, Nicolai; Costa, Cesar S. B.

    2017-04-01

    Circular (RP) and ring-shape (RP) patches of vegetation in intertidal flats have been associated with the radial expansion of tussock growth forms and die-back gap in older central stands, respectively. RP formation has not yet been sufficiently explained. We accomplished a comparative geochemical study of CP and RP structures of Spartina densiflora within a single saltmarsh in a microtidal estuary (toxic environment for S. densiflora and die-back central gap formation in RP. CP structure was 5 cm higher in the intertidal than RP but shows frequent presence of a water layer, less severe oxidation of sulfides and limited building-up of toxic condition to plants. Development of S. densiflora RP probably indicates the uplift of sediment by this bioengineer grass and/or periodic lowering of the water surface below a certain critical level.

  15. Qualitative SEM/EDS analysis of microleakage and apical gap formation of adhesive root-filling materials

    Directory of Open Access Journals (Sweden)

    Soraia de Fátima Carvalho Souza

    2012-06-01

    Full Text Available OBJECTIVE: The aim of this study was to compare the correspondence between gap formation and apical microleakage in root canals filled with epoxy resin-based (AH Plus combined or not with resinous primer or with a dimethacrylate-based root canal sealer (Epiphany. MATERIAL AND METHODS: Thirty-nine lower single-rooted human premolars were filled by the lateral condensation technique (LC and immersed in a 50-wt% aqueous silver nitrate solution at 37ºC (24 h. After longitudinal sectioning, epoxy resin replicas were made from the tooth specimens. Both the replicas and the specimens were prepared for scanning electron microscopy (SEM. The gaps were observed in the replicas. Apical microleakage was detected in the specimens by SEM/energy dispersive spectroscopy (SEM/EDS. The data were analyzed statistically using an Ordinal Logistic Regression model and Analysis of Correspondence (α=0.05. RESULTS: Epiphany presented more regions containing gaps between dentin and sealer (p0.05. CONCLUSIONS: The resinous primer did not improve the sealing ability of AH Plus sealer and the presence of gaps had an effect on apical microleakage for all materials.

  16. Integration, gap formation, and sharpening of III-V heterostructure nanowires by selective etching

    DEFF Research Database (Denmark)

    Kallesoe, C.; Mølhave, Kristian; Larsen, K. F.

    2010-01-01

    Epitaxial growth of heterostructure nanowires allows for the definition of narrow sections with specific semiconductor composition. The authors demonstrate how postgrowth engineering of III-V heterostructure nanowires using selective etching can form gaps, sharpening of tips, and thin sections si...

  17. Formation and Decay of Electron-Hole Plasma Clusters in a Direct-Gap Semiconductor CuCl

    Institute of Scientific and Technical Information of China (English)

    JIANG Lei(姜磊); WU Ming-Wei(吴明卫); M. Nagai; M. Kuwata-Gonokami

    2003-01-01

    The master equation for the cluster-size distribution function is solved numerically to investigate the electronhole droplet formation claimed to be discovered in the direct-gap CuCl excited by picosecond laser pulses [Nagai et al. Phys. Rev. Lett. 86 (2001)5795; J. Lumin. 100 (2002)233]. Our result shows that for the excitation in the experiment, the average number of pairs per cluster (ANPC) is only around 5.2, much smaller than that (106 typically for Ge) of the well studied electron-hole droplet in indirect-gap semiconductors such as Ge and Si.These results indicate that what measured in CuCl by Nagai et al. may not come from the EHD formed from exciton gas, instead possibly come from some bubbles of excitons in metallic liquid.

  18. Photonic band-gap formation by optical-phase-mask lithography.

    Science.gov (United States)

    Chan, Timothy Y M; Toader, Ovidiu; John, Sajeev

    2006-04-01

    We demonstrate an approach for fabricating photonic crystals with large three-dimensional photonic band gaps (PBG's) using single-exposure, single-beam, optical interference lithography based on diffraction of light through an optical phase mask. The optical phase mask (OPM) consists of two orthogonally oriented binary gratings joined by a thin, solid layer of homogeneous material. Illuminating the phase mask with a normally incident beam produces a five-beam diffraction pattern which can be used to expose a suitable photoresist and produce a photonic crystal template. Optical-phase-mask Lithography (OPML) is a major simplification from the previously considered multibeam holographic lithography of photonic crystals. The diffracted five-beam intensity pattern exhibits isointensity surfaces corresponding to a diamondlike (face-centered-cubic) structure, with high intensity contrast. When the isointensity surfaces in the interference patterns define a silicon-air boundary in the resulting photonic crystal, with dielectric contrast 11.9 to 1, the optimized PBG is approximately 24% of the gap center frequency. The ideal index contrast for the OPM is in the range of 1.7-2.3. Below this range, the intensity contrast of the diffraction pattern becomes too weak. Above this range, the diffraction pattern may become too sensitive to structural imperfections of the OPM. When combined with recently demonstrated polymer-to-silicon replication methods, OPML provides a highly efficient approach, of unprecedented simplicity, for the mass production of large-scale three-dimensional photonic band-gap materials.

  19. Diameter Growth of Juvenile Trees after Gap Formation in a Bolivian Rain Forest: Responses are Strongly Species-specific and Size-dependent.

    NARCIS (Netherlands)

    Soliz-Gamboa, C.C.; Sandbrink, A.; Zuidema, P.A.

    2012-01-01

    We evaluated growth responses to gap formation for juvenile individuals of three canopy rain forest species: Peltogyne cf. heterophylla, Clarisia racemosa and Cedrelinga catenaeformis. Gaps were formed during selective logging operations 7 yr before sampling in a Bolivian rain forest. We collected w

  20. Formation of Bragg Band Gaps in Anisotropic Phononic Crystals Analyzed With the Empty Lattice Model

    Directory of Open Access Journals (Sweden)

    Yan-Feng Wang

    2016-05-01

    Full Text Available Bragg band gaps of phononic crystals generally, but not always, open at Brillouin zone boundaries. The commonly accepted explanation stems from the empty lattice model: assuming a small material contrast between the constituents of the unit cell, avoided crossings in the phononic band structure appear at frequencies and wavenumbers corresponding to band intersections; for scalar waves the lowest intersections coincide with boundaries of the first Brillouin zone. However, if a phononic crystal contains elastically anisotropic materials, its overall symmetry is not dictated solely by the lattice symmetry. We construct an empty lattice model for phononic crystals made of isotropic and anisotropic materials, based on their slowness curves. We find that, in the anisotropic case, avoided crossings generally do not appear at the boundaries of traditionally defined Brillouin zones. Furthermore, the Bragg “planes” which give rise to phononic band gaps, are generally not flat planes but curved surfaces. The same is found to be the case for avoided crossings between shear (transverse and longitudinal bands in the isotropic case.

  1. Bridging the Gap from Galactic to Extragalactic: Star Formation and Giant Molecular Clouds within the Nearby Spiral Galaxy NGC 300

    Science.gov (United States)

    Faesi, Christopher

    2017-01-01

    The questions surrounding the origins of stars are of key importance in astrophysics across a huge range in physical scales. However, until recently, investigations have been restricted to either detailed studies targeting a few nearby regions in the Milky Way, or kpc- or larger-scale studies of entire galaxies. Between these two scales lies a crucial gap in understanding. In this thesis work, I have taken steps in bridging this gap between Galactic and extragalactic star formation. I will present the results of a campaign of observations and modeling targeting the nearby spiral galaxy NGC 300. Using an extensive suite of multi-wavelength data I have characterized the star formation activity and molecular gas in a large sample of star-forming regions within this galaxy. Additionally, I have assembled an extensive (300 clouds) and high resolution (10 pc) catalog of Giant Molecular Clouds (GMCs) based on ALMA CO observations. This unprecedented look at the population of GMCs in a nearby spiral galaxy reveals an astonishing range of morphologies and properties in the Molecular Gas as well as providing a key testbed for comparison with GMCs in the Milky Way and other nearby galaxies. The GMCs in NGC 300 appear to have similar global properties and show scaling relations consistent with those seen in the Milky Way. Furthermore, the star formation rate appears to correlate with the mass of molecular gas with approximately 250 Gyr depletion time, extending the relation discovered in the Milky Way linearly to larger scales. These results suggest a level of universality in the star formation process within spiral galaxy disks like our own Milky Way.

  2. Mass Gap for Black-Hole Formation in Higher-Derivative and Ghost-Free Gravity

    Science.gov (United States)

    Frolov, Valeri P.

    2015-07-01

    We study a spherical gravitational collapse of a small mass in higher-derivative and ghost-free theories of gravity. By boosting a solution of linearized equations for a static point mass in such theories we obtain in the Penrose limit the gravitational field of an ultrarelativistic particle. Taking a superposition of such solutions we construct a metric of a collapsing null shell in the linearized higher-derivative and ghost-free gravity. The latter allows one to find the gravitational field of a thick null shell. By analyzing these solutions we demonstrate that in a wide class of the higher dimensional theories of gravity as well as for the ghost-free gravity there exists a mass gap for mini-black-hole production. We also found conditions when the curvature invariants remain finite at r =0 for the collapse of the thick null shell.

  3. Mass-gap for black hole formation in higher derivative and ghost free gravity

    CERN Document Server

    Frolov, Valeri P

    2015-01-01

    We study a spherical gravitational collapse of a small mass in higher derivative and ghost free theories of gravity. By boosting a solution of linearized equations for a static point mass in such theories we obtain in the Penrose limit the gravitational field of an ultra-relativistic particle. Taking a superposition of such solutions we construct a metric of a collapsing null shell in the linearized higher derivative and ghost free gravity. The latter allows one to find the gravitational field of a thick null shell. By analysing these solutions we demonstrate that in a wide class of the higher dimensional theories of gravity as well as for the ghost free gravity there exists a mass gap for the mini black hole production. We also found conditions when the curvature invariants remain finite at $r=0$ for the collapse of the thick null shell.

  4. Bridging the gap: disk formation in the Class 0 phase with ambipolar diffusion and Ohmic dissipation

    CERN Document Server

    Dapp, Wolf B; Kunz, Matthew W

    2011-01-01

    Context: Ideal MHD simulations have revealed catastrophic magnetic braking (MB) in the protostellar phase, which prevents the formation of a centrifugal disk around a nascent protostar. Aims: We determine if non-ideal MHD, including the effects of ambipolar diffusion and Ohmic dissipation determined from a detailed chemical network model, allows for disk formation at the earliest stages of star formation (SF). Methods: We employ the axisymmetric thin-disk approximation in order to resolve a dynamic range of 9 orders of magnitude in length and 16 in density, while also calculating partial ionization using up to 19 species in a detailed chemical equilibrium model. MB is applied using a steady-state approximation, and a barotropic relation is used to capture the thermal evolution. Results: We resolve the formation of the first and second cores, with expansion waves at the periphery of each, a magnetic diffusion shock, and prestellar infall profiles at larger radii. Power-law profiles in each region can be unders...

  5. Effect of configuration factor on gap formation in hybrid composite resin, low-shrinkage composite resin and resin-modified glass ionomer.

    Science.gov (United States)

    Boroujeni, Parvin M; Mousavinasab, Sayyed M; Hasanli, Elham

    2015-05-01

    Polymerization shrinkage is one of the important factors in creation of gap between dental structure and composite resin restorations. The aim of this study was to evaluate the effect of configuration factor (C-factor) on gap formation in a hybrid composite resin, a low shrinkage composite resin and a resin modified glass ionomer restorative material. Cylindrical dentin cavities with 5.0 mm diameter and three different depths (1.0, 2.0 and 3.0 mm) were prepared on the occlusal surface of 99 human molars and the cavities assigned into three groups (each of 33). Each group contained three subgroups depend on the different depths and then cavities restored using resin modified glass ionomer (Fuji II LC Improved) and two type composite resins (Filtek P90 and Filtek Z250). Then the restorations were cut into two sections in a mesiodistal direction in the middle of restorations. Gaps were measured on mesial, distal and pulpal floor of the cavities, using a stereomicroscope. Data analyses using Kruskal-Wallist and Mann-Whitney tests. Increasing C-factor from 1.8 to 3.4 had no effect on the gap formation in two type composite resins, but Fuji II LC Improved showed significant effect of increasing C-factor on gap formation. Taken together, when C-factor increased from 1.8 up to 3.4 had no significant effect on gap formation in two tested resin composites. Although, Filtek P90 restorations showed smaller gap formation in cavities walls compared to Filtek Z250 restorations. High C-factor values generated the largest gap formation. Silorane-based composite was more efficient for cavity sealing than methacrylate-based composites and resin modified glass ionomer. © 2014 Wiley Publishing Asia Pty Ltd.

  6. Formation of antiwaves in gap-junction-coupled chains of neurons

    Science.gov (United States)

    Urban, Alexander; Ermentrout, Bard

    2012-07-01

    Using network models consisting of gap-junction-coupled Wang-Buszaki neurons, we demonstrate that it is possible to obtain not only synchronous activity between neurons but also a variety of constant phase shifts between 0 and π. We call these phase shifts intermediate stable phase-locked states. These phase shifts can produce a large variety of wavelike activity patterns in one-dimensional chains and two-dimensional arrays of neurons, which can be studied by reducing the system of equations to a phase model. The 2π periodic coupling functions of these models are characterized by prominent higher order terms in their Fourier expansion, which can be varied by changing model parameters. We study how the relative contribution of the odd and even terms affects what solutions are possible, the basin of attraction of those solutions, and their stability. These models may be applicable to the spinal central pattern generators of the dogfish and also to the developing neocortex of the neonatal rat.

  7. ATP Is Required and Advances Cytokine-Induced Gap Junction Formation in Microglia In Vitro

    Directory of Open Access Journals (Sweden)

    Pablo J. Sáez

    2013-01-01

    Full Text Available Microglia are the immune cells in the central nervous system. After injury microglia release bioactive molecules, including cytokines and ATP, which modify the functional state of hemichannels (HCs and gap junction channels (GJCs, affecting the intercellular communication via extracellular and intracellular compartments, respectively. Here, we studied the role of extracellular ATP and several cytokines as modulators of the functional state of microglial HCs and GJCs using dye uptake and dye coupling techniques, respectively. In microglia and the microglia cell line EOC20, ATP advanced the TNF-α/IFN-γ-induced dye coupling, probably through the induction of IL-1β release. Moreover, TNF-α/IFN-γ, but not TNF-α plus ATP, increased dye uptake in EOC20 cells. Blockade of Cx43 and Panx1 HCs prevented dye coupling induced by TNF-α/IFN-γ, but not TNF-α plus ATP. In addition, IL-6 prevented the induction of dye coupling and HC activity induced by TNF-α/IFN-γ in EOC20 cells. Our data support the notion that extracellular ATP affects the cellular communication between microglia through autocrine and paracrine mechanisms, which might affect the timing of immune response under neuroinflammatory conditions.

  8. The Role of School Performance in Narrowing Gender Gaps in the Formation of STEM Aspirations: A Cross-National Study

    Directory of Open Access Journals (Sweden)

    Allison eMann

    2015-02-01

    Full Text Available Abstract This study uses cross-national evidence to estimate the effect of school peer performance on the size of the gender gap in the formation of STEM career aspirations. We argue that STEM aspirations are influenced not only by gender stereotyping in the national culture but also by the performance of peers in the local school environment. Our analyses are based on the Program for International Student Assessment (PISA. They investigate whether 15-year-old students from 55 different countries expect to have STEM jobs at the age of 30. We find considerable gender differences in the plans to pursue careers in STEM occupations in all countries. Using PISA test scores in math and science aggregated at the school level as a measure of school performance, we find that stronger performance environments have a negative impact on student career aspirations in STEM. Although girls are less likely than boys to aspire to STEM occupations, even when they have comparable abilities, boys respond more than girls to competitive school performance environments. As a consequence, the aspirations gender gap narrows for high-performing students in stronger performance environments. We show that those effects are larger in countries that do not sort students into different educational tracks.

  9. The role of school performance in narrowing gender gaps in the formation of STEM aspirations: a cross-national study.

    Science.gov (United States)

    Mann, Allison; Legewie, Joscha; DiPrete, Thomas A

    2015-01-01

    This study uses cross-national evidence to estimate the effect of school peer performance on the size of the gender gap in the formation of STEM career aspirations. We argue that STEM aspirations are influenced not only by gender stereotyping in the national culture but also by the performance of peers in the local school environment. Our analyses are based on the Program for International Student Assessment (PISA). They investigate whether 15-year-old students from 55 different countries expect to have STEM jobs at the age of 30. We find considerable gender differences in the plans to pursue careers in STEM occupations in all countries. Using PISA test scores in math and science aggregated at the school level as a measure of school performance, we find that stronger performance environments have a negative impact on student career aspirations in STEM. Although girls are less likely than boys to aspire to STEM occupations, even when they have comparable abilities, boys respond more than girls to competitive school performance environments. As a consequence, the aspirations gender gap narrows for high-performing students in stronger performance environments. We show that those effects are larger in countries that do not sort students into different educational tracks.

  10. Ultrasound to stimulate early bone formation in a distraction gap : a double blind randomised clinical pilot trial in the edentulous mandible

    NARCIS (Netherlands)

    Schortinghuis, J; Bronckers, ALLJ; Stegenga, B; Raghoebar, GM; de Bont, LGM

    2005-01-01

    Objective: In a double blind randomised clinical pilot trial, it was investigated whether tow intensity pulsed ultrasound therapy stimulates early bone formation in a distraction gap created in a severely resorbed mandible. Design: Eight patients underwent a mandibular vertical distraction over an a

  11. A Novel 96well-formatted Micro-gap Plate Enabling Drug Response Profiling on Primary Tumour Samples

    Science.gov (United States)

    Ma, Wei-Yuan; Hsiung, Lo-Chang; Wang, Chen-Ho; Chiang, Chi-Ling; Lin, Ching-Hung; Huang, Chiun-Sheng; Wo, Andrew M.

    2015-04-01

    Drug-based treatments are the most widely used interventions for cancer management. Personalized drug response profiling remains inherently challenging with low cell count harvested from tumour sample. We present a 96well-formatted microfluidic plate with built-in micro-gap that preserves up to 99.2% of cells during multiple assay/wash operation and only 9,000 cells needed for a single reagent test (i.e. 1,000 cells per test spot x 3 selected concentration x triplication), enabling drug screening and compatibility with conventional automated workstations. Results with MCF7 and MDA-MB-231 cell lines showed that no statistical significance was found in dose-response between the device and conventional 96-well plate control. Primary tumour samples from breast cancer patients tested in the device also showed good IC50 prediction. With drug screening of primary cancer cells must consider a wide range of scenarios, e.g. suspended/attached cell types and rare/abundant cell availability, the device enables high throughput screening even for suspended cells with low cell count since the signature microfluidic cell-trapping feature ensures cell preservation in a multiple solution exchange protocol.

  12. The role of magnetism in the formation of the two-phase miscibility gap in β Cu–Al–Mn

    Energy Technology Data Exchange (ETDEWEB)

    Lanzini, Fernando, E-mail: flanzini@exa.unicen.edu.ar [Instituto de Física de Materiales Tandil (IFIMAT), Universidad Nacional del Centro de la Provincia de Buenos Aires (UNCPBA), Pinto 399, 7000 Tandil (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina); Alés, Alejandro [Instituto de Física de Materiales Tandil (IFIMAT), Universidad Nacional del Centro de la Provincia de Buenos Aires (UNCPBA), Pinto 399, 7000 Tandil (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina)

    2015-12-01

    A theoretical study of the ground state properties of alloys with compositions along the pseudobinary line Cu{sub 3}Al–Cu{sub 2}AlMn is presented. Cohesive energies, lattice parameters and magnetic moments of the two limiting compounds and three intermediate compositions are calculated by means of density functional theory. In order to evaluate the role of magnetism, both the spin-polarized (SP) and the non spin-polarized (NSP) cases have been considered. It is shown that magnetism plays a central role on the stabilization of the L2{sub 1} crystal structure in Cu{sub 2}AlMn, and in the formation of the miscibility gap in Cu{sub 3}Al–Cu{sub 2}AlMn. The considerable lattice mismatch between the end compounds can be attributed also to magnetic effects. - Highlights: • Alloys with compositions Cu{sub 3−x}AlMn{sub x} were studied by first principles methods. • Both spin-polarized (SP) and non-spin-polarized (NSP) calculations were done. • Cohesive energies, lattice parameters and magnetic moments were determined. • The phase separation Cu{sub 3}Al+Cu{sub 2}AlMn is attributable to magnetic effects. • In the NSP case, L2{sub 1} Cu{sub 2}AlMn is predicted to be unstable against the F43m structure.

  13. sup 7 sup 5 As NQR/NMR study of successive phase transitions and energy gap formation in Kondo semiconductor CeRhAs

    CERN Document Server

    Matsumura, M; Takabatake, T; Tsuji, S; Tou, H; Sera, M

    2003-01-01

    sup 7 sup 5 As NQR/NMR studies were performed to investigate the successive phase transitions found recently, the gap formation and their interplay in a Kondo semiconductor CeRhAs. NQR/NMR spectra in their respective phases change, reflecting lattice modulation modes, q sub 1 = (0, 1/2, 1/2), q sub 2 = (0, 1/3, 1/3) and q sub 3 = (1/3, 0, 0). In particular for well-resolved three NQR lines corresponding to the q sub 3 mode in the lowest temperature phase, the nuclear spin-lattice relaxation rate (T sub 1 T) sup - sup 1 shows an activation type T-dependence, suggesting a gap opening over the entire Fermi surface, in contrast to the V-shaped gap in isostructural CeNiSn and CeRhSn. The evaluated gap of 272 K and the bandwidth of about 4000 K are one order of magnitude larger than those in CeNiSn and CeRhSb. A lattice modulation forms a gap different from the V-shaped gap. (author)

  14. Formation mechanism of the low-frequency locally resonant band gap in the two-dimensional ternary phononic crystals

    Institute of Scientific and Technical Information of China (English)

    Wang Gang; Liu Yao-Zong; Wen Ji-Hong; Yu Dian-Long

    2006-01-01

    The low-frequency band gap and the corresponding vibration modes in two-dimensional ternary locally resonant phononic crystals are restudied successfully with the lumped-mass method. Compared with the work of C. Goffaux and J. Sanchez-Dehesa (Phys. Rev. B 67 14 4301(2003)), it is shown that there exists an error of about 50% in their calculated results of the band structure, and one band is missing in their results. Moreover, the in-plane modes shown in their paper are improper, which results in the wrong conclusion on the mechanism of the ternary locally resonant phononic crystals. Based on the lumped-mass method and better description of the vibration modes according to the band gaps, the locally resonant mechanism in forming the subfrequency gaps is thoroughly analysed. The rule used to judge whether a resonant mode in the phononic crystals can result in a corresponding subfrequency gap is also verified in this ternary case.

  15. The effects of chronic unloading and gap formation on tendon-to-bone healing in a rat model of massive rotator cuff tears.

    Science.gov (United States)

    Killian, Megan L; Cavinatto, Leonardo; Shah, Shivam A; Sato, Eugene J; Ward, Samuel R; Havlioglu, Necat; Galatz, Leesa M; Thomopoulos, Stavros

    2014-03-01

    The objective of this study was to understand the effect of pre-repair rotator cuff chronicity on post-repair healing outcomes using a chronic and acute multi-tendon rat rotator cuff injury model. Full-thickness dual tendon injuries (supra- and infraspinatus) were created unilaterally in adult male Sprague Dawley rats, and left chronically detached for 8 or 16 weeks. After chronic detachment, tears were repaired and acute dual tendon injuries were created and immediately repaired on contralateral shoulders. Tissue level outcomes for bone, tendon, and muscle were assessed 4 or 8 weeks after repair using histology, microcomputed tomography, biomechanical testing, and biochemical assays. Substantial gap formation was seen in 35% of acute repairs and 44% of chronic repairs. Gap formation negatively correlated with mechanical and structural outcomes for both healing time points regardless of injury duration. Bone and histomorphometry, as well as biomechanics, were similar between acute and chronic injury and repair regardless of chronicity and duration of healing. This study was the first to implement a multi-tendon rotator cuff injury with surgical repair following both chronic and acute injuries. Massive tear in a rodent model resulted in gap formation regardless of injury duration which had detrimental effects on repair outcomes. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  16. Closing the gap between behavior and models in route choice: The role of spatiotemporal constraints and latent traits in choice set formation

    DEFF Research Database (Denmark)

    Kaplan, Sigal; Prato, Carlo Giacomo

    2012-01-01

    A considerable gap exists between the behavioral paradigm of choice set formation in route choice and its representation in route choice modeling. While travelers form their viable choice set by retaining routes that satisfy spatiotemporal constraints, existing route generation techniques do...... constraint-based choice set formation followed by compensatory choice. The model is applied to data focusing on habitual commuting route choice behavior in morning peak hours. Results show (i) the possibility of inferring spatiotemporal constraints from considered routes, (ii) the importance of incorporating...... spatiotemporal constraints and latent traits in route choice models, and (iii) the linkage between spatiotemporal constraints and time saving, spatial and mnemonic abilities....

  17. GAP Analysis Program (GAP)

    Data.gov (United States)

    Kansas Data Access and Support Center — The Kansas GAP Analysis Land Cover database depicts 43 land cover classes for the state of Kansas. The database was generated using a two-stage hybrid classification...

  18. End field formation in planar hybrid undulators to ensure gap independence of the first and second field integrals

    Energy Technology Data Exchange (ETDEWEB)

    Papadichev, V.A. [P.N. Lebedev Physical Institute, RAS, 53 Leninsky Prospect, 119991 Moscow (Russian Federation)]. E-mail: papadich@mail1.lebedev.ru; Rybalchenko, G.V. [P.N. Lebedev Physical Institute, RAS, 53 Leninsky Prospect, 119991 Moscow (Russian Federation)

    2004-10-21

    Magnetic field amplitude in pure permanent magnet (PPM) or hybrid undulators is varied by changing the gap. It is necessary to ensure that for all gaps the deviation of the first and second field integrals from ideal be sufficiently small, especially in the XFEL project where dozens of undulator sections, each about 5-m long, are to be used. Since a high field is required, a hybrid undulator should be used. In this paper, field calculations for such an undulator were carried out using the 'Radia' code. Unlike a PPM undulator scheme, hybrid ones require more sophisticated schemes of minimizing field integrals because of complicated redistribution of magnetic flux at the undulator ends with changing gap. Saturation of iron poles makes solution of the problem more difficult. Both effects were studied and several compensating methods were found. Parameters of the permanent magnets and iron poles of the first and last end-field-forming undulator periods were varied in order to change the form and mean value of the first and second integrals versus undulator gap.

  19. Adaptation to diverse nitrogen-limited environments by deletion or extrachromosomal element formation of the GAP1 locus

    DEFF Research Database (Denmark)

    Gresham, D.; Usaite, Renata; Germann, S.M.;

    2010-01-01

    To study adaptive evolution in defined environments, we performed evolution experiments with Saccharomyces cerevisiae (yeast) in nitrogen-limited chemostat cultures. We used DNA microarrays to identify copy-number variation associated with adaptation and observed frequent amplifications and delet...... that the frequency of GAP1circle and gap1 Delta generation may be increased under nitrogen-limiting conditions. We propose that this genomic architecture facilitates evolvability of S. cerevisiae populations exposed to variation in levels and sources of environmental nitrogen.......To study adaptive evolution in defined environments, we performed evolution experiments with Saccharomyces cerevisiae (yeast) in nitrogen-limited chemostat cultures. We used DNA microarrays to identify copy-number variation associated with adaptation and observed frequent amplifications...... chromosomal locus. The GAP1circle is selected following prolonged culturing in L-glutamine-limited chemostats in a manner analogous to the selection of oncogenes present on double minutes in human cancers. Clones carrying only the gap1 Delta allele were selected under various non-amino acid nitrogen...

  20. The School Age Gender Gap in Reading Achievement: Examining the Influences of Item Format and Intrinsic Reading Motivation

    Science.gov (United States)

    Schwabe, Franziska; McElvany, Nele; Trendtel, Matthias

    2015-01-01

    The importance of reading competence for both individuals and society underlines the strong need to understand the gender gap in reading achievement. Beyond mean differences in reading comprehension, research has indicated that girls possess specific advantages on constructed-response items compared with boys of the same reading ability. Moreover,…

  1. Percolation cooling of the Three Mile Island Unit 2 lower head by way of thermal cracking and gap formation

    DEFF Research Database (Denmark)

    Thomsen, K.L.

    2002-01-01

    Two partial models have been developed to elucidate the Three Mile Island Unit 2 lower head coolability by water percolation from above into the thermally cracking debris bed and into a gap between the debris and the wall The bulk permeability of the cracked top crust is estimated based on simple...

  2. Indirect effects of emerald ash borer-induced ash mortality and canopy gap formation on epigaeic beetles.

    Science.gov (United States)

    Gandhi, Kamal J K; Smith, Annemarie; Hartzler, Diane M; Herms, Daniel A

    2014-06-01

    Exotic herbivorous insects have drastically and irreversibly altered forest structure and composition of North American forests. For example, emerald ash borer (Agrilus planipennis Fairmaire) from Asia has caused wide-scale mortality of ash trees (Fraxinus spp.) in eastern United States and Canada. We studied the effects of forest changes resulting from emerald ash borer invasion on epigaeic or ground beetles (Coleoptera: Carabidae) along a gradient of ash dieback and gap sizes in southeastern Michigan. Ground beetles were sampled in hydric, mesic, and xeric habitats in which black (Fraxinus nigra Marshall), green (Fraxinus pennsylvanica Marshall), and white (Fraxinus americana L.) ash were the most common species, respectively. During 2006-2007, we trapped 2,545 adult ground beetles comprising 52 species. There was a negative correlation between percent ash tree mortality in 2006 and catches of all beetles. Catches of Agonum melanarium Dejean (in 2006) and Pterostichus mutus (Say) (in 2006-2007) were negatively correlated with tree mortality and gap size, respectively. However, catches of Pterostichus corvinus Dejean were positively correlated with gap size in 2006. As ash mortality and average gap size increased from 2006 to 2007, catches of all beetles as well as P. mutus and Pterostichus stygicus (Say) increased (1.3-3.9 times), while species diversity decreased, especially in mesic and xeric stands. Cluster analysis revealed that beetle assemblages in hydric and mesic stand diverged (25 and 40%, respectively) in their composition from 2006 to 2007, and that hydric stands had the most unique beetle assemblages. Overall, epigaeic beetle assemblages were altered in ash stands impacted by emerald ash borer; however, these impacts may dissipate as canopy gaps close.

  3. The role of heparan sulfate deficiency in autistic phenotype: potential involvement of Slit/Robo/srGAPs-mediated dendritic spine formation.

    Science.gov (United States)

    Pérez, Christine; Sawmiller, Darrell; Tan, Jun

    2016-04-18

    Autism Spectrum Disorders (ASD) are the second most common developmental cause of disability in the United States. ASDs are accompanied with substantial economic and emotional cost. The brains of ASD patients have marked structural abnormalities, in the form of increased dendritic spines and decreased long distance connections. These structural differences may be due to deficiencies in Heparin Sulfate (HS), a proteoglycan involved in a variety of neurodevelopmental processes. Of particular interest is its role in the Slit/Robo pathway. The Slit/Robo pathway is known to be involved in the regulation of axonal guidance and dendritic spine formation. HS mediates the Slit/Robo interaction; without its presence Slit's repulsive activity is abrogated. Slit/Robo regulates dendritic spine formation through its interaction with srGAPs (slit-robo GTPase Activating Proteins), which leads to downstream signaling, actin cytoskeleton depolymerization and dendritic spine collapse. Through interference with this pathway, HS deficiency can lead to excess spine formation.

  4. In vitro synchrotron-based radiography of micro-gap formation at the implant–abutment interface of two-piece dental implants

    Energy Technology Data Exchange (ETDEWEB)

    Rack, A., E-mail: arack@snafu.de [European Synchrotron Radiation Facility, Grenoble (France); Rack, T. [Charité, Department of Oral and Maxillofacial Surgery, Clinical Navigation and Robotics, Berlin (Germany); Stiller, M. [Charité, Department of Maxillofacial and Facial-Plastic Surgery, Division of Oral Medicine, Radiology and Surgery, Berlin (Germany); Riesemeier, H. [Bundesanstalt für Materialforschung und -prüfung, Division Structure Analysis, Polymer Analysis, Berlin (Germany); Zabler, S. [Technical University of Berlin, Institute for Materials Engineering (Germany); Nelson, K. [Charité, Department of Oral and Maxillofacial Surgery, Clinical Navigation and Robotics, Berlin (Germany)

    2010-03-01

    Micro-radiography using hard X-ray synchrotron radiation is the first potential tool to allow an evaluation of the mechanical behavior of the dental implant–abutment complex during force application, thus enabling the enhancement of the design of dental implants which has been based on theoretical analysis to date. Micro-gap formation at the implant–abutment interface of two-piece dental implants was investigated in vitro using high-resolution radiography in combination with hard X-ray synchrotron radiation. Images were taken with the specimen under different mechanical loads of up to 100 N. The aim of this investigation was to prove the existence of micro-gaps for implants with conical connections as well as to study the mechanical behavior of the mating zone of conical implants during loading. Synchrotron-based radiography in comparison with classical laboratory radiography yields high spatial resolution in combination with high contrast even when exploiting micro-sized features in highly attenuating objects. The first illustration of a micro-gap which was previously indistinguishable by laboratory methods underlines that the complex micro-mechanical behavior of implants requires further in vitro investigations where synchrotron-based micro-imaging is one of the prerequisites.

  5. Unconventional Magnetism and Band Gap Formation in LiFePO4: Consequence of Polyanion Induced Non-planarity.

    Science.gov (United States)

    Jena, Ajit; Nanda, B R K

    2016-01-21

    Oxygen plays a critical role in strongly correlated transition metal oxides as crystal field effect is one of the key factors that determine the degree of localization of the valence d/f states. Based on the localization, a set of conventional mechanisms such as Mott-Hubbard, Charge-transfer and Slater were formulated to explain the antiferromagnetic and insulating (AFI) phenomena in many of these correlated systems. From the case study on LiFePO4, through density-functional calculations, we demonstrate that none of these mechanisms are strictly applicable to explain the AFI behavior when the transition metal oxides have polyanions such as (PO4)(3-). The symmetry-lowering of the metal-oxygen complex, to stabilize the polyanion, creates an asymmetric crystal field for d/f states. In LiFePO4 this field creates completely non-degenerate Fe-d states which, with negligible p-d and d-d covalent interactions, become atomically localized to ensure a gap at the Fermi level. Due to large exchange splitting, high spin state is favored and an antiferromagnetic configuration is stabilized. For the prototype LiFePO4, independent electron approximation is good enough to obtain the AFI ground state. Inclusion of additional correlation measures like Hubbard U simply amplifies the gap and therefore LiFePO4 can be preferably called as weakly coupled Mott insulator.

  6. Unconventional Magnetism and Band Gap Formation in LiFePO4: Consequence of Polyanion Induced Non-planarity

    Science.gov (United States)

    Jena, Ajit; Nanda, B. R. K.

    2016-01-01

    Oxygen plays a critical role in strongly correlated transition metal oxides as crystal field effect is one of the key factors that determine the degree of localization of the valence d/f states. Based on the localization, a set of conventional mechanisms such as Mott-Hubbard, Charge-transfer and Slater were formulated to explain the antiferromagnetic and insulating (AFI) phenomena in many of these correlated systems. From the case study on LiFePO4, through density-functional calculations, we demonstrate that none of these mechanisms are strictly applicable to explain the AFI behavior when the transition metal oxides have polyanions such as (PO4)3-. The symmetry-lowering of the metal-oxygen complex, to stabilize the polyanion, creates an asymmetric crystal field for d/f states. In LiFePO4 this field creates completely non-degenerate Fe-d states which, with negligible p-d and d-d covalent interactions, become atomically localized to ensure a gap at the Fermi level. Due to large exchange splitting, high spin state is favored and an antiferromagnetic configuration is stabilized. For the prototype LiFePO4, independent electron approximation is good enough to obtain the AFI ground state. Inclusion of additional correlation measures like Hubbard U simply amplifies the gap and therefore LiFePO4 can be preferably called as weakly coupled Mott insulator.

  7. Experimental demonstration of a novel bio-sensing platform via plasmonic band gap formation in gold nano-patch arrays

    CERN Document Server

    Grande, Marco; Stomeo, Tiziana; Morea, Giuseppe; Marani, Roberto; Marrocco, Valeria; Petruzzelli, Vincenzo; D'Orazio, Antonella; Cingolani, Roberto; De Vittorio, Massimo; de Ceglia, Domenico; Scalora, Michael

    2011-01-01

    We discuss the possibility of implementing a novel bio-sensing platform based on the observation of the shift of the leaky surface plasmon mode that occurs at the edge of the plasmonic band gap of metal gratings when an analyte is deposited on top of the metallic structure. We provide experimental proof of the sensing capabilities of a two-dimensional array of gold nano-patches by observing color variations in the diffracted field when the air overlayer is replaced with a small quantity of Isopropyl Alcohol (IPA). Effects of rounded corners and surface imperfections are also discussed. Finally, we also report proof of changes in color intensities as a function of the air/filling ratio of the structure and discuss their relation with the diffracted spectra.

  8. Heats of combustion and formation of new energetic thermoplastic elastomers based on GAP, polyNIMMO and polyGLYN

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, Emmanuela [CERSIM, Department of Chemistry, Laval University, Ste-Foy, G1K 7P4 (Canada); Defence Research and Development Canada (DRDC)-Valcartier, 2459 Pie-XI Blvd. North, Val-Belair, G3J 1X5 (Canada); Brousseau, Patrick; Ampleman, Guy [CERSIM, Department of Chemistry, Laval University, Ste-Foy, G1K 7P4 (Canada); Prud' homme, Robert Emery [Defence Research and Development Canada (DRDC)-Valcartier, 2459 Pie-XI Blvd. North, Val-Belair, G3J 1X5 (Canada)

    2003-06-01

    Heats of combustion and formation of various energetic thermoplastic elastomers (ETPE), corresponding to linear copolyurethanes based on an energetic prepolymer and a diisocyanate, were measured by a calorimetric method. These ETPEs were synthesized from three different molecular weights of glycidyl azide polymer, from poly(3-nitratomethyl-3-methyloxetane) and from poly glycidyl nitrate. The prepolymers were also analyzed for comparison with the corresponding ETPEs. A significant difference of the heats of formation was observed between the prepolymers and their ETPEs, while the heats of combustion were similar. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  9. Sb Magnetic Resonance as a Local Probe for the Gap Formation in the Correlated Semimetal FeSb2

    DEFF Research Database (Denmark)

    Gippius, A. A.; Baenitz, M.; Okhotnikov, K. S.;

    2014-01-01

    We report on a comparative study of the narrow-band semimetals FeSb2 and its structural homologue RuSb2 by means of Sb-121,Sb-123 nuclear quadrupole (NQR) and nuclear magnetic resonance (NMR) spectroscopy. From NQR for both compounds two temperature regimes could be identified by use of (123)(1/T...... (1)) measurements. Above 40 K a conventional activated behavior (with Delta/k (B) a parts per thousand... 400 K for FeSb2) dominates in (123)(1/T (1)), whereas below 40 K in both systems an unconventional (123)(1/T (1)) behavior with a smooth maximum at around 10 K is observed. To analyze...... this behavior, we propose the presence of T-dependent in-gap states forming a narrow energy level of localized spins with S = A1/2 near the bottom of the conduction band. These states might have originated from an inherent Sb-deficiency in both compounds. This model enables us to fit the (123)(1/T (1)) data...

  10. Non-isothermal analysis of die corner gap formation for materials deformed by multi-pass ECAP

    Science.gov (United States)

    Medeiros, N.; Moreira, L. P.

    2014-08-01

    In this paper, the upper-bound solutions proposed by Eivani and Karimi Taheri [Comp. Mater. Sci. 42 (2008) 14] to calculate processing force and evaluate die corner angle Ψ formation in terms of tribology and die configurations during cold single pass equal channels angular pressed metals with constant flow stress were extended to work-hardening metals processed by two passes according to route A by using the Swift model combined to von Mises isotropic plasticity criterion. Also, adiabatic heat equation was coupled to solutions to express the final temperature of the workpiece. For that, thermomechanical properties of a hot-dip galvanized interstitial-free (IF) were considered and its behavior under pressing was evaluated to non-hardening and work-hardening conditions in all performed analyses. By including work-hardening in the models and for the critical friction factor of 0.4, theoretical predictions after single pass showed a decreasing of die corner angle and pressing force predictions and increasing of effective plastic strain and end temperature for all friction conditions and tooling geometries evaluated. In addition, after second pass, these responses showed higher values. Finally, with the proposed upper-bound models it was possible to analyze the dependency of angle Ψ, effective plastic strain, pressing load and sample temperature with the instantaneous workpiece height at the entry surface of deformation zone.

  11. Modeling of wind gap formation and development of sedimentary basins during fold growth: application to the Zagros Fold Belt, Iran.

    Science.gov (United States)

    Collignon, Marine; Yamato, Philippe; Castelltort, Sébastien; Kaus, Boris

    2016-04-01

    Mountain building and landscape evolution are controlled by the interactions between river dynamics and tectonic forces. Such interactions have been largely studied but a quantitative evaluation of tectonic/geomorphic feedbacks remains required for understanding sediments routing within orogens and fold-and-thrust belts. Here, we employ numerical simulations to assess the conditions of uplift and river incision necessary to deflect an antecedent drainage network during the growth of one or several folds. We propose that a partitioning of the river network into internal (endorheic) and longitudinal drainage arises as a result of lithological differences within the deforming crustal sedimentary cover. We show with examples from the Zagros Fold Belt (ZFB) that drainage patterns can be linked to the incision ratio R between successive lithological layers, corresponding to the ratio between their relative erodibilities or incision coefficients. Transverse drainage networks develop for uplift rates smaller than 0.8 mm.yr-1 and -10 rates up to 2 mm.yr-1 and incision ratios of 20. Parallel drainage networks and formation of sedimentary basins occur for large values of incision ratio (R >20) and uplift rates between 1 and 2 mm.yr-1. These results have implications for predicting the distribution of sediment depocenters in fold-and-thrust belts, which can be of direct economic interest for hydrocarbon exploration.

  12. The role of gap junctions and mechanical loading on mineral formation in a collagen-I scaffold seeded with osteoprogenitor cells.

    Science.gov (United States)

    Damaraju, Swathi; Matyas, John R; Rancourt, Derrick E; Duncan, Neil A

    2015-05-01

    Fracture nonunions represent one of many large bone defects where current treatment strategies fall short in restoring both form and function of the injured tissue. In this case, the use of a tissue-engineered scaffold for promoting bone healing offers an accessible and easy-to-manipulate environment for studying bone formation processes in vitro. We have previously shown that mechanical prestimulation using confined compression of differentiating osteoblasts results in an increase in mineralization formed in a 3D collagen-I scaffold. This study builds on this knowledge by evaluating the short and long-term effects of blocking gap junction-mediated intercellular communication among osteogenic cells on their effectiveness to mineralize collagen-I scaffolds in vitro, and in the presence and absence of mechanical stimulation. In this study, confined compression was applied in conjunction with octanol (a general communication blocker) or 18-α-glycerrhetinic acid (AGA, a specific gap junction blocker) using a modified FlexCell plate to collagen-I scaffolds seeded with murine embryonic stem cells stimulated toward osteoblast differentiation using beta-glycerol phosphate. The activity, presence, and expression of osteoblast cadherin, connexin-43, as well as various pluripotent and osteogenic markers were examined at 5-30 days of differentiation. Fluorescence recovery after photobleaching, immunofluorescence, viability, histology assessments, and reverse-transcriptase polymerase chain reaction assessments revealed that inhibiting communication in this scaffold altered the lineage and function of differentiating osteoblasts. In particular, treatment with communication inhibitors caused reduced mineralization in the matrix, and dissociation between connexin-43 and integrin α5β1. This dissociation was not restored even after long-term recovery. Thus, in order for this scaffold to be considered as an alternative strategy for the repair of large bone defects, cell

  13. Knowledge Gaps

    DEFF Research Database (Denmark)

    Lyles, Marjorie; Pedersen, Torben; Petersen, Bent

    2003-01-01

    The study explores what factors influence the reduction of managers' perceivedknowledge gaps in the context of the environments of foreign markets. Potentialdeterminants are derived from traditional internationalization theory as well asorganizational learning theory, including the concept......, assimilating, and utilizing knowledge - are crucial determinants ofknowledge gap elimination. In contrast, the two factors deemed essential in traditionalinternationalization process theory - elapsed time of operations and experientiallearning - are found to have no or limited effect.Key words......: Internationalization, knowledge gap, absorptive capacity, learning box....

  14. Density functional theory calculations for the band gap and formation energy of Pr4-xCaxSi12O3+xN18-x; a highly disordered compound with low symmetry and a large cell size.

    Science.gov (United States)

    Hong, Sung Un; Singh, Satendra Pal; Pyo, Myoungho; Park, Woon Bae; Sohn, Kee-Sun

    2017-06-28

    A novel oxynitride compound, Pr4-xCaxSi12O3+xN18-x, synthesized using a solid-state route has been characterized as a monoclinic structure in the C2 space group using Rietveld refinement on synchrotron powder X-ray diffraction data. The crystal structure of this compound was disordered due to the random distribution of Ca/Pr and N/O ions at various Wyckoff sites. A pragmatic approach for an ab initio calculation based on density function theory (DFT) for this disordered compound has been implemented to calculate an acceptable value of the band gap and formation energy. In general, for the DFT calculation of a disordered compound, a sufficiently large super cell and infinite variety of ensemble configurations is adopted to simulate the random distribution of ions; however, such an approach is time consuming and cost ineffective. Even a single unit cell model gave rise to 43 008 independent configurations as an input model for the DFT calculations. Since it was nearly impossible to calculate the formation energy and the band gap energy for all 43 008 configurations, an elitist non-dominated sorting genetic algorithm (NSGA-II) was employed to find the plausible configurations. In the NSGA-II, all 43 008 configurations were mathematically treated as genomes and the calculated band gap and the formation energy as the objective (fitness) function. Generalized gradient approximation (GGA) was first employed in the preliminary screening using NSGA-II, and thereafter a hybrid functional calculation (HSE06) was executed only for the most plausible GGA-relaxed configurations with lower formation and higher band gap energies. The final band gap energy (3.62 eV) obtained after averaging over the selected configurations, resembles closely the experimental band gap value (4.11 eV).

  15. Gap Resolution

    Energy Technology Data Exchange (ETDEWEB)

    2017-04-25

    Gap Resolution is a software package that was developed to improve Newbler genome assemblies by automating the closure of sequence gaps caused by repetitive regions in the DNA. This is done by performing the follow steps:1) Identify and distribute the data for each gap in sub-projects. 2) Assemble the data associated with each sub-project using a secondary assembler, such as Newbler or PGA. 3) Determine if any gaps are closed after reassembly, and either design fakes (consensus of closed gap) for those that closed or lab experiments for those that require additional data. The software requires as input a genome assembly produce by the Newbler assembler provided by Roche and 454 data containing paired-end reads.

  16. The effect of interspecific variation in photosynthetic plasticity on 4-year growth rate and 8-year survival of understorey tree seedlings in response to gap formations in a cool-temperate deciduous forest.

    Science.gov (United States)

    Oguchi, Riichi; Hiura, Tsutom; Hikosaka, Kouki

    2017-04-19

    Gap formation increases the light intensity in the forest understorey. The growth responses of seedlings to the increase in light availability show interspecific variation, which is considered to promote biodiversity in forests. At the leaf level, some species increase their photosynthetic capacity in response to gap formation, whereas others do not. Here we address the question of whether the interspecific difference in the photosynthetic response results in the interspecific variation in the growth response. If so, the interspecific difference in photosynthetic response would also contribute to species coexistence in forests. We also address the further relevant question of why some species do not increase their photosynthetic capacity. We assumed that some cost of photosynthetic plasticity may constrain acquisition of the plasticity in some species, and hypothesized that species with larger photosynthetic plasticity exhibit better growth after gap formation and lower survivorship in the shade understorey of a cool-temperate deciduous forest. We created gaps by felling canopy trees and studied the relationship between the photosynthetic response and the subsequent growth rate of seedlings. Naturally growing seedlings of six deciduous woody species were used and their mortality was examined for 8 years. The light-saturated rate of photosynthesis (Pmax) and the relative growth rate (RGR) of the seedlings of all study species increased at gap plots. The extent of these increases varied among the species. The stimulation of RGR over 4 years after gap formation was strongly correlated with change in photosynthetic capacity of newly expanded leaves. The increase in RGR and Pmax correlated with the 8-year mortality at control plots. These results suggest a trade-off between photosynthetic plasticity and the understorey shade tolerance. Gap-demanding species may acquire photosynthetic plasticity, sacrificing shade tolerances, whereas gap-independent species may acquire

  17. Gap Junctions

    Science.gov (United States)

    Nielsen, Morten Schak; Axelsen, Lene Nygaard; Sorgen, Paul L.; Verma, Vandana; Delmar, Mario; Holstein-Rathlou, Niels-Henrik

    2013-01-01

    Gap junctions are essential to the function of multicellular animals, which require a high degree of coordination between cells. In vertebrates, gap junctions comprise connexins and currently 21 connexins are known in humans. The functions of gap junctions are highly diverse and include exchange of metabolites and electrical signals between cells, as well as functions, which are apparently unrelated to intercellular communication. Given the diversity of gap junction physiology, regulation of gap junction activity is complex. The structure of the various connexins is known to some extent; and structural rearrangements and intramolecular interactions are important for regulation of channel function. Intercellular coupling is further regulated by the number and activity of channels present in gap junctional plaques. The number of connexins in cell-cell channels is regulated by controlling transcription, translation, trafficking, and degradation; and all of these processes are under strict control. Once in the membrane, channel activity is determined by the conductive properties of the connexin involved, which can be regulated by voltage and chemical gating, as well as a large number of posttranslational modifications. The aim of the present article is to review our current knowledge on the structure, regulation, function, and pharmacology of gap junctions. This will be supported by examples of how different connexins and their regulation act in concert to achieve appropriate physiological control, and how disturbances of connexin function can lead to disease. © 2012 American Physiological Society. Compr Physiol 2:1981-2035, 2012. PMID:23723031

  18. Gap junctions.

    Science.gov (United States)

    Nielsen, Morten Schak; Axelsen, Lene Nygaard; Sorgen, Paul L; Verma, Vandana; Delmar, Mario; Holstein-Rathlou, Niels-Henrik

    2012-07-01

    Gap junctions are essential to the function of multicellular animals, which require a high degree of coordination between cells. In vertebrates, gap junctions comprise connexins and currently 21 connexins are known in humans. The functions of gap junctions are highly diverse and include exchange of metabolites and electrical signals between cells, as well as functions, which are apparently unrelated to intercellular communication. Given the diversity of gap junction physiology, regulation of gap junction activity is complex. The structure of the various connexins is known to some extent; and structural rearrangements and intramolecular interactions are important for regulation of channel function. Intercellular coupling is further regulated by the number and activity of channels present in gap junctional plaques. The number of connexins in cell-cell channels is regulated by controlling transcription, translation, trafficking, and degradation; and all of these processes are under strict control. Once in the membrane, channel activity is determined by the conductive properties of the connexin involved, which can be regulated by voltage and chemical gating, as well as a large number of posttranslational modifications. The aim of the present article is to review our current knowledge on the structure, regulation, function, and pharmacology of gap junctions. This will be supported by examples of how different connexins and their regulation act in concert to achieve appropriate physiological control, and how disturbances of connexin function can lead to disease. © 2012 American Physiological Society. Compr Physiol 2:1853-1872, 2012.

  19. Mythic gaps

    Directory of Open Access Journals (Sweden)

    William Hansen

    2014-11-01

    Full Text Available Different kinds of omissions sometimes occur, or are perceived to occur, in traditional narratives and in tradition-inspired literature. A familiar instance is when a narrator realizes that he or she does not fully remember the story that he or she has begun to tell, and so leaves out part of it, which for listeners may possibly result in an unintelligible narrative. But many instances of narrative gap are not so obvious. From straightforward, objective gaps one can distinguish less-obvious subjective gaps: in many cases narrators do not leave out anything crucial or truly relevant from their exposition, and yet readers perceive gaps and take steps to fill them. The present paper considers four examples of subjective gaps drawn from ancient Greek literature (the Pandora myth, ancient Roman literature (the Pygmalion legend, ancient Hebrew literature (the Joseph legend, and early Christian literature (the Jesus legend. I consider the quite varied ways in which interpreters expand the inherited texts of these stories, such as by devising names, manufacturing motives, creating backstories, and in general filling in biographical ellipses. Finally, I suggest an explanation for the phenomenon of subjective gaps, arguing that, despite their variety, they have a single cause.

  20. GAP Analysis Program (GAP) Raster

    Data.gov (United States)

    Kansas Data Access and Support Center — The Kansas GAP Land Cover database depicts 43 land cover classes for the state of Kansas. The database was generated using a two-stage hybrid classification of...

  1. Formats

    Directory of Open Access Journals (Sweden)

    Gehmann, Ulrich

    2012-03-01

    Full Text Available In the following, a new conceptual framework for investigating nowadays’ “technical” phenomena shall be introduced, that of formats. The thesis is that processes of formatting account for our recent conditions of life, and will do so in the very next future. It are processes whose foundations have been laid in modernity and which will further unfold for the time being. These processes are embedded in the format of the value chain, a circumstance making them resilient to change. In addition, they are resilient in themselves since forming interconnected systems of reciprocal causal circuits.Which leads to an overall situation that our entire “Lebenswelt” became formatted to an extent we don’t fully realize, even influencing our very percep-tion of it.

  2. Knowledge Gaps

    DEFF Research Database (Denmark)

    Lyles, Marjorie; Pedersen, Torben; Petersen, Bent

    2003-01-01

    of absorptive capacity. Building onthese literature streams a conceptual model is developed and tested on a set of primarydata of Danish firms and their foreign market operations. The empirical study suggeststhat the factors that pertain to the absorptive capacity concept - capabilities ofrecognizing......, assimilating, and utilizing knowledge - are crucial determinants ofknowledge gap elimination. In contrast, the two factors deemed essential in traditionalinternationalization process theory - elapsed time of operations and experientiallearning - are found to have no or limited effect.Key words......: Internationalization, knowledge gap, absorptive capacity, learning box....

  3. Imaging of a Transitional Disk Gap in Reflected Light : Indications of Planet Formation Around the Young Solar Analog LkCa 15

    NARCIS (Netherlands)

    Thalmann, C.; Grady, C.A.; Goto, M.; Wisniewski, J. P.; Janson, M.; Henning, T.; Honda, M.; Mulders, G. D.; Min, M.; Fukagawa, M.; Moro-Martin, A.; McElwain, M. W.; Hodapp, K. W.; Carson, J.; Abe, L.; Brandner, W.; Egner, S.; Feldt, M.; Fukue, T.; Golota, T.; Guyon, O.; Hashimoto, J.; Hayano, Y.; Hayashi, M.; Hayashi, S.; Ishii, M.; Kandori, R.; Knapp, G. R.; Kudo, T.; Kusakabe, N.; Kuzuhara, M.; Matsuo, T.; Miyama, S.; Morino, J. -I.; Nishimura, T.; Pyo, T. -S.; Serabyn, E.; Shibai, H.; Suto, H.; Suzuki, R.; Takami, M.; Takato, N.; Terada, H.; Tomono, D.; Turner, E. L.; Watanabe, M.; Yamada, T.; Takami, H.; Usuda, T.; Tamura, M.; Fugukawa, M.

    2011-01-01

    We present H- and Ks-band imaging data resolving the gap in the transitional disk around LkCa 15, revealing the surrounding nebulosity. We detect sharp elliptical contours delimiting the nebulosity on the inside as well as the outside, consistent with the shape, size, ellipticity, and orientation of

  4. Significant reduction in NiO band gap upon formation of Lix Ni1-x O alloys: applications to solar energy conversion.

    Science.gov (United States)

    Alidoust, Nima; Toroker, Maytal Caspary; Keith, John A; Carter, Emily A

    2014-01-01

    Long-term sustainable solar energy conversion relies on identifying economical and versatile semiconductor materials with appropriate band structures for photovoltaic and photocatalytic applications (e.g., band gaps of ∼ 1.5-2.0 eV). Nickel oxide (NiO) is an inexpensive yet highly promising candidate. Its charge-transfer character may lead to longer carrier lifetimes needed for higher efficiencies, and its conduction band edge is suitable for driving hydrogen evolution via water-splitting. However, NiO's large band gap (∼ 4 eV) severely limits its use in practical applications. Our first-principles quantum mechanics calculations show band gaps dramatically decrease to ∼ 2.0 eV when NiO is alloyed with Li2O. We show that Lix Ni1-x O alloys (with x=0.125 and 0.25) are p-type semiconductors, contain states with no impurity levels in the gap and maintain NiO's desirable charge-transfer character. Lastly, we show that the alloys have potential for photoelectrochemical applications, with band edges well-placed for photocatalytic hydrogen production and CO2 reduction, as well as in tandem dye-sensitized solar cells as a photocathode. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Imaging of a transitional disk gap in reflected light: indications of planet formation around the young solar analog LkCa 15

    NARCIS (Netherlands)

    Thalmann, C.; Grady, C.A.; Goto, M.; Wisniewski, J.P.; Janson, M.; Henning, T.; Fukagawa, M.; Honda, M.; Mulders, G.D.; Min, M.; Moro-Martín, A.; McElwain, M.W.; Hodapp, K.W.; Carson, J.; Abe, L.; Brandner, W.; Egner, S.; Feldt, M.; Fukue, T.; Golota, T.; Guyon, O.; Hashimoto, J.; Hayano, Y.; Hayashi, M.; Hayashi, S.; Ishii, M.; Kandori, R.; Knapp, G.R.; Kudo, T.; Kusakabe, N.; Kuzuhara, M.; Matsuo, T.; Miyama, S.; Morino, J.-I.; Nishimura, T.; Pyo, T.-S.; Serabyn, E.; Shibai, H.; Suto, H.; Suzuki, R.; Takami, M.; Takato, N.; Terada, H.; Tomono, D.; Turner, E.L.; Watanabe, M.; Yamada, T.; Takami, H.; Usuda, T.; Tamura, M.

    2010-01-01

    We present H- and K-s-band imaging data resolving the gap in the transitional disk around LkCa 15, revealing the surrounding nebulosity. We detect sharp elliptical contours delimiting the nebulosity on the inside as well as the outside, consistent with the shape, size, ellipticity, and orientation o

  6. Imaging of a Transitional Disk Gap in Reflected Light : Indications of Planet Formation Around the Young Solar Analog LkCa 15

    NARCIS (Netherlands)

    Thalmann, C.; Grady, C.A.; Goto, M.; Wisniewski, J. P.; Janson, M.; Henning, T.; Honda, M.; Mulders, G. D.; Min, M.; Fukagawa, M.; Moro-Martin, A.; McElwain, M. W.; Hodapp, K. W.; Carson, J.; Abe, L.; Brandner, W.; Egner, S.; Feldt, M.; Fukue, T.; Golota, T.; Guyon, O.; Hashimoto, J.; Hayano, Y.; Hayashi, M.; Hayashi, S.; Ishii, M.; Kandori, R.; Knapp, G. R.; Kudo, T.; Kusakabe, N.; Kuzuhara, M.; Matsuo, T.; Miyama, S.; Morino, J. -I.; Nishimura, T.; Pyo, T. -S.; Serabyn, E.; Shibai, H.; Suto, H.; Suzuki, R.; Takami, M.; Takato, N.; Terada, H.; Tomono, D.; Turner, E. L.; Watanabe, M.; Yamada, T.; Takami, H.; Usuda, T.; Tamura, M.; Fugukawa, M.

    2011-01-01

    We present H- and Ks-band imaging data resolving the gap in the transitional disk around LkCa 15, revealing the surrounding nebulosity. We detect sharp elliptical contours delimiting the nebulosity on the inside as well as the outside, consistent with the shape, size, ellipticity, and orientation of

  7. Imaging of a transitional disk gap in reflected light: indications of planet formation around the young solar analog LkCa 15

    NARCIS (Netherlands)

    Thalmann, C.; Grady, C.A.; Goto, M.; Wisniewski, J.P.; Janson, M.; Henning, T.; Fukagawa, M.; Honda, M.; Mulders, G.D.; Min, M.; Moro-Martín, A.; McElwain, M.W.; Hodapp, K.W.; Carson, J.; Abe, L.; Brandner, W.; Egner, S.; Feldt, M.; Fukue, T.; Golota, T.; Guyon, O.; Hashimoto, J.; Hayano, Y.; Hayashi, M.; Hayashi, S.; Ishii, M.; Kandori, R.; Knapp, G.R.; Kudo, T.; Kusakabe, N.; Kuzuhara, M.; Matsuo, T.; Miyama, S.; Morino, J.-I.; Nishimura, T.; Pyo, T.-S.; Serabyn, E.; Shibai, H.; Suto, H.; Suzuki, R.; Takami, M.; Takato, N.; Terada, H.; Tomono, D.; Turner, E.L.; Watanabe, M.; Yamada, T.; Takami, H.; Usuda, T.; Tamura, M.

    2010-01-01

    We present H- and K-s-band imaging data resolving the gap in the transitional disk around LkCa 15, revealing the surrounding nebulosity. We detect sharp elliptical contours delimiting the nebulosity on the inside as well as the outside, consistent with the shape, size, ellipticity, and orientation o

  8. Imaging of a transitional disk gap in reflected light: indications of planet formation around the young solar analog LkCa 15

    NARCIS (Netherlands)

    Thalmann, C.; Grady, C.A.; Gotto, M.; Min, M.|info:eu-repo/dai/nl/277318416

    2010-01-01

    We present H- and Ks-band imaging data resolving the gap in the transitional disk around LkCa 15, revealing the surrounding nebulosity. We detect sharp elliptical contours delimiting the nebulosity on the inside as well as the outside, consistent with the shape, size, ellipticity, and orientation of

  9. Imaging of a Transitional Disk Gap in Reflected Light: Indications of Planet Formation Around the Young Solar Analog LkCa 15

    CERN Document Server

    Thalmann, C; Goto, M; Wisniewski, J P; Janson, M; Henning, T; Fukagawa, M; Honda, M; Mulders, G D; Min, M; Moro-Martín, A; McElwain, M W; Hodapp, K W; Carson, J; Abe, L; Brandner, W; Egner, S; Feldt, M; Fukue, T; Golota, T; Guyon, O; Hashimoto, J; Hayano, Y; Hayashi, M; Hayashi, S; Ishii, M; Kandori, R; Knapp, G R; Kudo, T; Kusakabe, N; Kuzuhara, M; Matsuo, T; Miyama, S; Morino, J -I; Nishimura, T; Pyo, T -S; Serabyn, E; Shibai, H; Suto, H; Suzuki, R; Takami, M; Takato, N; Terada, H; Tomono, D; Turner, E L; Watanabe, M; Yamada, T; Takami, H; Usuda, T; Tamura, M

    2010-01-01

    We present H- and Ks-band imaging data resolving the gap in the transitional disk around LkCa 15, revealing the surrounding nebulosity. We detect sharp elliptical contours delimiting the nebulosity on the inside as well as the outside, consistent with the shape, size, ellipticity, and orientation of starlight reflected from the far-side disk wall, whereas the near-side wall is shielded from view by the disk's optically thick bulk. We note that forward-scattering of starlight on the near-side disk surface could provide an alternate interpretation of the nebulosity. In either case, this discovery provides confirmation of the disk geometry that has been proposed to explain the spectral energy distributions (SED) of such systems, comprising an optically thick outer disk with an inner truncation radius of ~46 AU enclosing a largely evacuated gap. Our data show an offset of the nebulosity contours along the major axis, likely corresponding to a physical pericenter offset of the disk gap. This reinforces the leading...

  10. Comparison of two different suture-passing techniques with different suture materials and thicknesses: Biomechanical study of flexor tendons for yield points, gap formation and early post-operative status

    Directory of Open Access Journals (Sweden)

    Volkan Ergan

    2016-12-01

    Conclusion: The yield points with higher forces is expected to be preferred, but their thicknesses can be 3-0 or 4-0. Oblique suture passing should be preferred rather than longitudinal passing. Obviously, suture strengthening methods, like epitendineous running sutures and core sutures, should be used. Without these measures, even passive wrist motion can result in gap formation at the repair site. The results of this study showed that tensile properties of the repaired vary considerably with differences in suture material and design. [Hand Microsurg 2016; 5(3.000: 130-136

  11. Formation of Dirac point and the topological surface states inside the strained gap for mixed 3D Hg1-xCdx Te

    Science.gov (United States)

    Marchewka, Michał

    2016-10-01

    In this paper the results of the numerical calculation obtained for the three-dimensional (3D) strained Hg1-xCdx Te layers for the x-Cd composition from 0.1 to 0.155 and a different mismatch of the lattice constant are presented. For the investigated region of the Cd composition (x value) the negative energy gap (Eg =Γ8 -Γ6) in the Hg1-xCdx Te is smaller than in the case of pure HgTe which, as it turns out, has a significant influence on the topological surface states (TSS) and the position of the Dirac point. The numerical calculation based on the finite difference method applied for the 8×8 kp model with the in-plane tensile strain for (001) growth oriented structure shows that the Dirac cone inside the induced insulating band gap for non zero of the Cd composition and a bigger strain caused by the bigger lattice mismatch (than for the 3D HgTe TI) can be obtained. It was also shown how different x-Cd compounds move the Dirac cone from the valence band into the band gap. The presented results show that 75 nm wide 3D Hg1-xCdx Te structures with x ≈ 0.155 and 1.6% lattice mismatch make the system a true topological insulator with the dispersion of the topological surface states similar to those ones obtained for the strained CdTe/HgTe QW.

  12. Effect of CMT multi-layer narrow gap welding parameters on weld formation%CMT窄间隙多层多道焊接工艺参数对焊缝成形的影响

    Institute of Scientific and Technical Information of China (English)

    周方明; 孙红辉; 宋辉; 周涌明; 张军

    2011-01-01

    In order to reduce spatter, welding heat input, welding residual stress and welding distortion, the influences of welding space of CMT flat overlaying and torch angle on welding formation are studied, and the welding test of CMT multi-layer narrow gap welding is carried out. The results show that good welding formation can be got when the welding space is 2/3 of the single weld width of the first layer and 5/9 of the single weld width of the other layers in the narrow gap welding. In the narrow gap sidewall welding, the good welding formation and sidewall penetration depth can be got when the welding torch at 75°to the horizontal and wire ends 1~2 mm are away from the sidewall. The multi-layer narrow gap welding with low welding heat input can be executed by adopting CMT welding system. A feasible and simple method is provided for reducing welding residual stress and welding distortion.%为了减少焊接热输入和飞溅,降低焊接残余应力和焊接变形,研究了CMT平板堆焊道间距及焊枪倾角对焊缝成形的影响,进行了CMT窄间隙多层多道焊接试验.结果表明,在窄间隙焊接时,第1层焊道间距为单-焊缝熔宽的2/3,以后各层焊道间距为单-焊缝熔宽的5/9,可以获得良好的焊缝成形;在窄间隙侧壁焊接时,焊枪与水平面夹角为75°,焊丝端部距侧壁1~2 mm时,侧壁熔深都在1 mm以上,成形较好,适于侧壁的焊接.采用CMT焊接系统,能够以较低的热输入进行窄间隙多层多道焊,从而为降低焊接残余应力和减少焊接变形提供了一种简单可行的方法.

  13. Effect of different sulphur precursors on morphology and band-gap on the formation of Cu2ZnSnS4 (CZTS) particles with microwave irradiation

    Science.gov (United States)

    Patro, Bharati; Vijaylakshmi, S.; Sharma, Pratibha

    2016-05-01

    Cu2ZnSnS4 (CZTS) is a promising semiconductor material for ecological cost effective thin film Photovoltaic (PV) devices. As it contains earth abundant and non-toxic elements, it has the advantages over commercially available CIGS and CdTe thin film PV devices. In the present work, the pure phase Cu2ZnSnS4 particles were successfully synthesised with microwave irradiation. The morphology and phase study was carried out for the samples prepared with two different sulphur precursors viz. thiourea and thioacetamide (TAA). CZTS particles with thiourea as sulphur precursor are more crystalline than CZTS particles with TAA. The band gap of 1.654eV and 1.713eV were calculated for the samples prepared with thiourea and TAA respectively.

  14. Ultrafast Charge and Triplet State Formation in Diketopyrrolopyrrole Low Band Gap Polymer/Fullerene Blends: Influence of Nanoscale Morphology of Organic Photovoltaic Materials on Charge Recombination to the Triplet State

    Directory of Open Access Journals (Sweden)

    René M. Williams

    2017-01-01

    Full Text Available Femtosecond transient absorption spectroscopy of thin films of two types of morphologies of diketopyrrolopyrrole low band gap polymer/fullerene-adduct blends is presented and indicates triplet state formation by charge recombination, an important loss channel in organic photovoltaic materials. At low laser fluence (approaching solar intensity charge formation characterized by a 1350 nm band (in ~250 fs dominates in the two PDPP-PCBM blends with different nanoscale morphologies and these charges recombine to form a local polymer-based triplet state on the sub-ns timescale (in ~300 and ~900 ps indicated by an 1100 nm absorption band. The rate of triplet state formation is influenced by the morphology. The slower rate of charge recombination to the triplet state (in ~900 ps belongs to a morphology that results in a higher power conversion efficiency in the corresponding device. Nanoscale morphology not only influences interfacial area and conduction of holes and electrons but also influences the mechanism of intersystem crossing (ISC. We present a model that correlates morphology to the exchange integral and fast and slow mechanisms for ISC (SOCT-ISC and H-HFI-ISC. For the pristine polymer, a flat and unstructured singlet-singlet absorption spectrum (between 900 and 1400 nm and a very minor triplet state formation (5% are observed at low laser fluence.

  15. Differential gene expression analysis of tubule forming and non-tubule forming endothelial cells: CDC42GAP as a counter-regulator in tubule formation

    NARCIS (Netherlands)

    Engelse, M.A.; Laurens, N.; Verloop, R.E.; Koolwijk, P.; Hinsbergh, V.W.M. van

    2008-01-01

    The formation of new tubular structures from a quiescent endothelial lining is one of the hallmarks of sprouting angiogenesis. This process can be mimicked in vitro by inducing capillary-like tubular structures in a three-dimensional (3D) fibrin matrix. We aimed to analyze the differential mRNA expr

  16. Interfacial chemical reaction and multiple gap state formation on three layer cathode in organic light-emitting diode: Ca/BaF2/Alq3

    Science.gov (United States)

    Kim, Tae Gun; Lee, Hyunbok; Yi, Yeonjin; Lee, Seung Mi; Kim, Jeong Won

    2015-07-01

    A three layer cathode is a promising stack structure for long lifetime and high efficiency in organic light-emitting diodes. The interfacial chemical reactions and their effects on electronic structures for alkaline-earth metal (Ca, Ba)/Alq3 [tris(8-hydroxyquinolinato)aluminum] and Ca/BaF2/Alq3 are investigated using in-situ X-ray and ultraviolet photoelectron spectroscopy, as well as molecular model calculation. The BaF2 interlayer initially prevents direct contact between Alq3 and the reactive Ca metal, but it is dissociated into Ba and CaF2 by the addition of Ca. As the Ca thickness increases, the Ca penetrates the interlayer to directly participate in the reaction with the underlying Alq3. This series of chemical reactions takes place irrespective of the BaF2 buffer layer thickness as long as the Ca overlayer thickness is sufficient. The interface reaction between the alkaline-earth metal and Alq3 generates two energetically separated gap states in a sequential manner. This phenomenon is explained by step-by-step charge transfer from the alkaline-earth metal to the lowest unoccupied molecular orbital states of Alq3, forming new occupied states below the Fermi level.

  17. Interfacial chemical reaction and multiple gap state formation on three layer cathode in organic light-emitting diode: Ca/BaF{sub 2}/Alq{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae Gun; Kim, Jeong Won, E-mail: jeongwonk@kriss.re.kr [Korea Research Institute of Standards and Science (KRISS), 267 Gajeong-ro, Daejeon 305-340 (Korea, Republic of); Korea University of Science and Technology (UST), 206 Gajeong-ro, Daejeon 305-350 (Korea, Republic of); Lee, Hyunbok [Department of Physics, Kangwon National University, 1 Gangwondaehak-gil, Chuncheon-si, Gangwon-do 200-701 (Korea, Republic of); Yi, Yeonjin [Institute of Physics and Applied Physics, Yonsei University, 50 Yonsei-ro, Seodaemoon-Gu, Seoul 120-749 (Korea, Republic of); Lee, Seung Mi [Korea Research Institute of Standards and Science (KRISS), 267 Gajeong-ro, Daejeon 305-340 (Korea, Republic of)

    2015-07-14

    A three layer cathode is a promising stack structure for long lifetime and high efficiency in organic light-emitting diodes. The interfacial chemical reactions and their effects on electronic structures for alkaline-earth metal (Ca, Ba)/Alq{sub 3} [tris(8-hydroxyquinolinato)aluminum] and Ca/BaF{sub 2}/Alq{sub 3} are investigated using in-situ X-ray and ultraviolet photoelectron spectroscopy, as well as molecular model calculation. The BaF{sub 2} interlayer initially prevents direct contact between Alq{sub 3} and the reactive Ca metal, but it is dissociated into Ba and CaF{sub 2} by the addition of Ca. As the Ca thickness increases, the Ca penetrates the interlayer to directly participate in the reaction with the underlying Alq{sub 3}. This series of chemical reactions takes place irrespective of the BaF{sub 2} buffer layer thickness as long as the Ca overlayer thickness is sufficient. The interface reaction between the alkaline-earth metal and Alq{sub 3} generates two energetically separated gap states in a sequential manner. This phenomenon is explained by step-by-step charge transfer from the alkaline-earth metal to the lowest unoccupied molecular orbital states of Alq{sub 3}, forming new occupied states below the Fermi level.

  18. Formation, properties and microstructure of amorphous/crystalline composite Ag{sub 20}Cu{sub 30}Ti{sub 50} alloy using miscibility gap

    Energy Technology Data Exchange (ETDEWEB)

    Ziewiec, Krzysztof, E-mail: kziewiec@gmail.co [Institute of Technology, Pedagogical University of Cracow, ul. Podchorazych 2, 30-084 Krakow (Poland); Kedzierski, Zbigniew; Zielinska-Lipiec, Anna; Stepinski, Janusz; Kac, Slawomir [AGH University of Science and Technology, Faculty of Metal Engineering and Industrial Computer Science, 30 Mickiewicza Ave, 30-059 Krakow (Poland)

    2009-08-12

    The aim of the work was to produce the amorphous/crystalline composite with uniform distribution of fine crystalline soft phase. Silver-copper-titanium Ag{sub 20}Cu{sub 30}Ti{sub 50} alloy was prepared using 99.95 wt% Ag, 99.95 wt% Cu, 99.95 wt% Ti that were arc-melted in argon atmosphere. Then the alloy was melt spun on a copper wheel with linear velocity of 33 m/s. Investigation of the microstructure for both arc-melt massive sample and melt-spun ribbons was performed with use of scanning electron microscope (SEM) with EDS, light microscope (LM) and X-ray diffraction. The thermal stability was evaluated by differential scanning calorimetry (DSC). The properties such as Young modulus and Vickers hardness number before and after crystallization of the amorphous matrix were measured with use of nanoindenter. The microstructure was investigated by transmission electron microscope (TEM). It was found, that the alloy has a tendency for separation within the liquid state due to the miscibility gap which resulted in segregation into Ti-Cu-Ag matrix and Ag-base spherical particles after arc-melting. During rapid cooling through the melt spinning the Ag{sub 20}Cu{sub 30}Ti{sub 50} alloy formed an amorphous/crystalline composite of fcc silver-rich spherical particles within the amorphous Ti-Cu-Ag matrix.

  19. Formative research on the primo vascular system and acceptance by the korean scientific community: the gap between creative basic science and practical convergence technology.

    Science.gov (United States)

    Kim, Hoon Gi

    2013-12-01

    The purpose of this study was to trace the formative process of primo vascular system (PVS) research over the past decade and to describe the characteristics of the Korean scientific community. By publishing approximately 30 papers in journals ranking in the Science Citation Index (Expanded), the PVS research team actively convinced domestic and international scientists of the anatomical existence of the PVS and its possible application to Korean and Western medicine. In addition, by sharing the PVS observation technique, the team promoted the dissemination and further pursuit of the research. In 2012, however, PVS researchers performed smaller scale research without advancing to a higher level as compared to the early days. The main reasons were found to be the Korean Research and Development policy of supporting creative, small-scale basic research and applied research of Western scientific fields that promised potentially greater success on an extensive scale; the indifference concerning, and the disbelief in, the existence of a new circulatory system were shown by the Western medical community. In addition, the Oriental medical community was apathetic about working with the PVS team. Professors Kwang-Sup Soh and Byung-Cheon Lee were the prime movers of PVS research under difficult conditions. Spurred by their belief in the existence and significance of the PVS, they continued with their research despite insufficient experimental data. The Korean scientific community is not ready to promote the Korea-oriented creative field of the PVS team. Copyright © 2013. Published by Elsevier B.V.

  20. PhoneGap 3 beginner's guide

    CERN Document Server

    Natili, Giorgio

    2013-01-01

    Written in a friendly, example-driven Beginner's Guide format, there are plenty of step-by-step instructions to help you get started with PhoneGap.If you are a web developer or mobile application developer interested in an examples-based approach to learning mobile application development basics with PhoneGap, then this book is for you.

  1. Band Gaps of an Amorphous Photonic Materials

    Institute of Scientific and Technical Information of China (English)

    WANG Yi-Quan; FENG Zhi-Fang; HU Xiao-Yong; CHENG Bing-Ying; ZHANG Dao-Zhong

    2004-01-01

    @@ A new kind of amorphous photonic materials is presented. Both the simulated and experimental results show that although the disorder of the whole dielectric structure is strong, the amorphous photonic materials have two photonic gaps. This confirms that the short-range order is an essential factor for the formation of the photonic gaps.

  2. Effect of the gap width around a restoration on the formation of artificial caries lesion%充填物边缘缝隙宽度对人工继发龋形成的影响

    Institute of Scientific and Technical Information of China (English)

    王万山; 赵信义

    2015-01-01

    AIM:To evaluate the effect of the gap width around a restoration on the formation of artificial caries lesion.METHODS:Each of bovine enamel blocks was invested into a metal ring and then was cut longitudinal-ly into 2 equal portions.One portion was inserted into the ring again and the cut surface of the enamel block was ad-hered with a plastic space sheet,with a thickness(μm)of 25,50,100,190 and 270 respectively,followed by inser-tion of a restorative material (Charisma and Fuji Ⅶ respectively)into the residual space of the ring.All restoration specimens were immersed in water for 7 d and then in demineralization solution for 72 h,followed by filling each gap with a light curing sealant resin.Each specimen was cut vertically through the gap to obtain slices of 150 μm thick for the observation under a polarized light microscope and the depths of outer lesion and wall lesion of each specimen were measured using image analysis software.RESULTS:All specimens presented a deeper outer lesion than wall lesion (P<0.05)and Charisma group presented deeper outer lesion than FujiⅦgroup(P<0.05).The depth of wall lesion increased with the increase of the gap width within 100 μm and the Charisma group showed deeper wall lesion than FujiⅦ group(P<0.05 )when the gap width was within 50 ~100 μm.CONCLUSION:The artificial secondary caries model with controlled marginal gap can present obvious out lesion and wall lesion and present the difference of fluoride-releasing materials and non-fluoride-releasing materials in preventing wall lesion.%目的:评价充填物边缘缝隙宽度对人工继发龋形成的影响,确定继发龋模型合适的缝隙宽度。方法:把牛牙釉质块包埋到圆环状模具内,然后对半纵切包埋后的试样,将其中一半重新放入模具内,用充填修复材料(Charisma,FujiⅦ)充填剩余空间,在材料与釉质纵切面间放置缝隙型片(厚度25、50、100、190、270μm),制备釉质与材料间有

  3. Towards smaller gap microbulks

    CERN Document Server

    Attié, D.; Dafni, T; Ferrer-Ribas, E.; Ferrer-Ribas, E; Ferry, S; Giomataris, Y; Herrera, D C; Iguaz, F J; Irastorza, I G; Kebbiri, M; Papaevangelou, T; de Oliveira, R; Seguí, L; Tomás, A

    2014-01-01

    Small gap Micromegas detectors ( < 50 μm) are expected to be optimal for high pressure applications. Combining the microbulk manufacturing technique with a small gap can result in attractive detectors for rare event detection, in particular double beta decay or dark matter searches. We present novel results obtained with small gap microbulks (25 and 12.5 μm) that have been manufactured recently. For the first time for this type of detectors, we show experimentally that for each amplification gap there is an optimal pressure and that smaller gaps are more suitable for higher pressures.

  4. Evaluation of Innovative High Pulse Rate, Purged Spark Gap Concepts

    Science.gov (United States)

    1989-06-01

    gugh the switch and the pressure loss through the gas circulation system. The pressure loss is the sum of the losses in the spark gap , flow ducting...developed to solve the mass, momentum, and energy conservation equations which govern the purging process in a spark gap flow channel following arc...formation. [2,3] In this model, gas properties and spark gap flow channel area varied with distance along the flow axis from the spark gap and with

  5. A first principles analysis of the effect of hydrogen concentration in hydrogenated amorphous silicon on the formation of strained Si-Si bonds and the optical and mobility gaps

    Energy Technology Data Exchange (ETDEWEB)

    Legesse, Merid; Nolan, Michael, E-mail: Michael.nolan@tyndall.ie; Fagas, Giorgos, E-mail: Georgios.fagas@tyndall.ie [Tyndall National Institute, University College Cork, Lee Maltings, Dyke Parade, Cork (Ireland)

    2014-05-28

    In this paper, we use a model of hydrogenated amorphous silicon generated from molecular dynamics with density functional theory calculations to examine how the atomic geometry and the optical and mobility gaps are influenced by mild hydrogen oversaturation. The optical and mobility gaps show a volcano curve as the hydrogen content varies from undersaturation to mild oversaturation, with largest gaps obtained at the saturation hydrogen concentration. At the same time, mid-gap states associated with dangling bonds and strained Si-Si bonds disappear at saturation but reappear at mild oversaturation, which is consistent with the evolution of optical gap. The distribution of Si-Si bond distances provides the key to the change in electronic properties. In the undersaturation regime, the new electronic states in the gap arise from the presence of dangling bonds and strained Si-Si bonds, which are longer than the equilibrium Si-Si distance. Increasing hydrogen concentration up to saturation reduces the strained bonds and removes dangling bonds. In the case of mild oversaturation, the mid-gap states arise exclusively from an increase in the density of strained Si-Si bonds. Analysis of our structure shows that the extra hydrogen atoms form a bridge between neighbouring silicon atoms, thus increasing the Si-Si distance and increasing disorder in the sample.

  6. Bridging the Gap

    OpenAIRE

    Kramer Overgaard, Majken; Broeng, Jes; Jensen, Monika Luniewska; Murdock, Karen; Schmidt, Iben Julie

    2015-01-01

    Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ventures. Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ve...

  7. Bridging the Gap

    DEFF Research Database (Denmark)

    Kramer Overgaard, Majken; Broeng, Jes; Jensen, Monika Luniewska;

    Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ventures.......Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ventures....

  8. Gap and density theorems

    CERN Document Server

    Levinson, N

    1940-01-01

    A typical gap theorem of the type discussed in the book deals with a set of exponential functions { \\{e^{{{i\\lambda}_n} x}\\} } on an interval of the real line and explores the conditions under which this set generates the entire L_2 space on this interval. A typical gap theorem deals with functions f on the real line such that many Fourier coefficients of f vanish. The main goal of this book is to investigate relations between density and gap theorems and to study various cases where these theorems hold. The author also shows that density- and gap-type theorems are related to various propertie

  9. Bridging a Cultural Gap

    Science.gov (United States)

    Leviatan, Talma

    2008-01-01

    There has been a broad wave of change in tertiary calculus courses in the past decade. However, the much-needed change in tertiary pre-calculus programmes--aimed at bridging the gap between high-school mathematics and tertiary mathematics--is happening at a far slower pace. Following a discussion on the nature of the gap and the objectives of a…

  10. Senseless Extravagance, Shocking Gaps

    Science.gov (United States)

    Weissbourd, Richard; Dodge, Trevor

    2012-01-01

    Although most people in the United States believe, at least theoretically, in educational equality, fewer and fewer appear to care about the resource gaps between affluent and poor schools, says Weissbourd. He illustrates these gaps with vivid descriptions of what he calls an "opulence arms race" among affluent independent schools, but…

  11. Bridge the Gap

    DEFF Research Database (Denmark)

    Marselis, Randi Lorenz

    2017-01-01

    This article focuses on photo projects organised for teenage refugees by the Society for Humanistic Photography (Berlin, Germany). These projects, named Bridge the Gap I (2015), and Bridge the Gap II (2016), were carried out in Berlin and brought together teenagers with refugee and German...

  12. Optimized measurement of gaps

    Science.gov (United States)

    Harding, Kevin; Ramamurthy, Rajesh

    2017-05-01

    Gaps are important in a wide range of measurements in manufacturing, from the fitting of critical assemblies too cosmetic features on cars. There are a variety of potential sensors that can measure a gap opening, each with aspects of gap measurements that they do well and other aspects where the technology may lack capability. This paper provides a review of a wide range of optical gages from structured light to passive systems and from line to area measurement. Each technology is considered relative to the ability to accurately measure a gap, including issues of edge effects, edge shape, surface finish, and transparency. Finally, an approach will be presented for creating an optimize measurement off gap openings for critical assembly applications.

  13. GAP-43 in synaptic plasticity: molecular perspectives

    Directory of Open Access Journals (Sweden)

    Holahan MR

    2015-06-01

    Full Text Available Matthew R HolahanDepartment of Neuroscience, Carleton University, Ottawa, ON, CanadaAbstract: The growth-associated protein, GAP-43 (also known as F1, neuromodulin, B-50, participates in the developmental regulation of axonal growth and neural network formation via protein kinase C-mediated regulation of cytoskeletal elements. Transgenic overexpression of GAP-43 can result in the formation of new synapses, neurite outgrowth, and synaptogenesis after injury. In a number of adult mammalian species, GAP-43 has been implicated in the regulation of synaptic transmission and plasticity, such as long-term potentiation, drug sensitization, and changes in memory processes. This review examines the molecular and biochemical attributes of GAP-43, its distribution in the central nervous system, subcellular localization, role in neurite outgrowth and development, and functions related to plasticity, such as those occurring during long-term potentiation, memory formation, and drug sensitization.Keywords: GAP-43, protein kinase C, axons, development, regeneration, long-term potentiation, memory

  14. A photonic thermalization gap in disordered lattices

    CERN Document Server

    Kondakci, H E; Saleh, B E A

    2016-01-01

    The formation of gaps -- forbidden ranges in the values of a physical parameter -- is a ubiquitous feature of a variety of physical systems: from energy bandgaps of electrons in periodic lattices and their analogs in photonic, phononic, and plasmonic systems to pseudo energy gaps in aperiodic quasicrystals. Here, we report on a `thermalization' gap for light propagating in finite disordered structures characterized by disorder-immune chiral symmetry -- the appearance of the eigenvalues and eigenvectors in skew-symmetric pairs. In this class of systems, the span of sub- thermal photon statistics is inaccessible to input coherent light, which -- once the steady state is reached -- always emerges with super-thermal statistics no matter how small the disorder level. We formulate an independent constraint that must be satisfied by the input field for the chiral symmetry to be `activated' and the gap to be observed. This unique feature enables a new form of photon-statistics interferometry: the deterministic tuning...

  15. Modelling Gender Pay Gaps

    OpenAIRE

    2004-01-01

    EXECUTIVE SUMMARYIntroductionThere has been little change in the full-time gender pay gap since the mid 1990s andin the female part-time/male full-time pay gap since the mid 1970s. The gender gapin hourly earnings for those employed full-time in Britain in 2003 was 18 per cent,while that between women working part-time and men working full-time was 40 percent.This research uses statistical methods to identify how much of the gender pay gap isassociated with different factors. The data set ana...

  16. Filling the Income Gap

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ Income distribution has become one of the people's main concerns in China where more than 30years of reform and opening up have also resulted in an ever-expanding wealth gap.But narrowing down the rich-poor disparity will prove to be no easy task.Wei Zhong,a researcher with the Institute of Economics under the Chinese Academy of Social Sciences,elaborated on the origins and trends of China's widening income gap,and discussed solutions to curb the gap,in a recent article.Edited excerpts follow:

  17. Bridging The Inferential Gap

    Science.gov (United States)

    Stewart, Walter F.; Shah, Nirav R.; Selna, Mark J.; Paulus, Ronald A.; Walker, James M.

    2009-01-01

    Most clinical decisions involve bridging the inferential gap: Clinicians are required to “fill in” where they lack knowledge or where no knowledge yet exists. In this context we consider how the inferential gap is a product, in part, of how knowledge is created, the limits to gaining access to such knowledge, and the variable ways in which knowledge is translated into decisions. We consider how electronic health records (EHRs) will help narrow this gap by accelerating the creation of evidence relevant to everyday practice needs and facilitating real-time use of knowledge in practice. PMID:17259202

  18. Small-Gap Flows

    Science.gov (United States)

    1984-04-01

    34’OF CALIFORNIA# BERKELEY, CA 5.1720 ft (45 642-141 SMALL- GAP FLOWS BY E. 0. TUCK REPORT No. NAUE 84-1 CONTRACT N00014-84-K-OU26 APRIL i984...Mechanics, 41 (1970) 769-792. 11 3. Shallow-Water Waves at Discontinuities Shallow-water waves represent perhaps the prototype small- gap flow , the...solving (4.4) we need "initial" conditions at the starting station z = 0, and "exit" conditions at the station z = L where the gap flow merges with the

  19. Filling the Income Gap

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Income distribution has become one of the people’s main concerns in China where more than 30 years of reform and opening up have also resulted in an ever-expanding wealth gap. But narrowing down the

  20. Significant Reduction in NiO Band Gap Upon Formation of LixNi1-xO alloys: Applications To Solar Energy Conversion

    Energy Technology Data Exchange (ETDEWEB)

    Alidoust, Nima; Toroker, Maytal Caspary; Keith, John A.; Carter, Emily A.

    2013-11-21

    Long-term sustainable solar energy conversion relies on identifying economical and versatile semiconductor materials with appropriate band structures for photovoltaic and photocatalytic applications (e.g., band gaps of ~1.5–2.0 eV). Nickel oxide (NiO) is an inexpensive yet highly promising candidate. Its charge-transfer character may lead to longer carrier lifetimes needed for higher efficiencies, and its conduction band edge is suitable for driving hydrogen evolution via water-splitting. However, NiO’s large band gap (~4 eV) severely limits its use in practical applications. Our first-principles quantum mechanics calculations show band gaps dramatically decrease to ~2.0 eV when NiO is alloyed with Li2O. In this paper, we show that LixNi1-xO alloys (with x=0.125 and 0.25) are p-type semiconductors, contain states with no impurity levels in the gap and maintain NiO’s desirable charge-transfer character. Lastly, we show that the alloys have potential for photoelectrochemical applications, with band edges well-placed for photocatalytic hydrogen production and CO2 reduction, as well as in tandem dye-sensitized solar cells as a photocathode.

  1. Molecular doping and band-gap opening of bilayer graphene.

    OpenAIRE

    Samuels, AJ; Carey, JD

    2013-01-01

    The ability to induce an energy band gap in bilayer graphene is an important development in graphene science and opens up potential applications in electronics and photonics. Here we report the emergence of permanent electronic and optical band gaps in bilayer graphene upon adsorption of π electron containing molecules. Adsorption of n- or p-type dopant molecules on one layer results in an asymmetric charge distribution between the top and bottom layers and in the formation of an energy gap. ...

  2. Flows of gas through a protoplanetary gap

    Science.gov (United States)

    Casassus, Simon; van der Plas, Gerrit; M, Sebastian Perez; Dent, William R. F.; Fomalont, Ed; Hagelberg, Janis; Hales, Antonio; Jordán, Andrés; Mawet, Dimitri; Ménard, Francois; Wootten, Al; Wilner, David; Hughes, A. Meredith; Schreiber, Matthias R.; Girard, Julien H.; Ercolano, Barbara; Canovas, Hector; Román, Pablo E.; Salinas, Vachail

    2013-01-01

    The formation of gaseous giant planets is thought to occur in the first few million years after stellar birth. Models predict that the process produces a deep gap in the dust component (shallower in the gas). Infrared observations of the disk around the young star HD 142527 (at a distance of about 140 parsecs from Earth) found an inner disk about 10 astronomical units (AU) in radius (1 AU is the Earth-Sun distance), surrounded by a particularly large gap and a disrupted outer disk beyond 140 AU. This disruption is indicative of a perturbing planetary-mass body at about 90 AU. Radio observations indicate that the bulk mass is molecular and lies in the outer disk, whose continuum emission has a horseshoe morphology. The high stellar accretion rate would deplete the inner disk in less than one year, and to sustain the observed accretion matter must therefore flow from the outer disk and cross the gap. In dynamical models, the putative protoplanets channel outer-disk material into gap-crossing bridges that feed stellar accretion through the inner disk. Here we report observations of diffuse CO gas inside the gap, with denser HCO+ gas along gap-crossing filaments. The estimated flow rate of the gas is in the range of 7 × 10-9 to 2 × 10-7 solar masses per year, which is sufficient to maintain accretion onto the star at the present rate.

  3. Numerical simulation of supersonic gap flow.

    Science.gov (United States)

    Jing, Xu; Haiming, Huang; Guo, Huang; Song, Mo

    2015-01-01

    Various gaps in the surface of the supersonic aircraft have a significant effect on airflows. In order to predict the effects of attack angle, Mach number and width-to-depth ratio of gap on the local aerodynamic heating environment of supersonic flow, two-dimensional compressible Navier-Stokes equations are solved by the finite volume method, where convective flux of space term adopts the Roe format, and discretization of time term is achieved by 5-step Runge-Kutta algorithm. The numerical results reveal that the heat flux ratio is U-shaped distribution on the gap wall and maximum at the windward corner of the gap. The heat flux ratio decreases as the gap depth and Mach number increase, however, it increases as the attack angle increases. In addition, it is important to find that chamfer in the windward corner can effectively reduce gap effect coefficient. The study will be helpful for the design of the thermal protection system in reentry vehicles.

  4. Numerical simulation of supersonic gap flow.

    Directory of Open Access Journals (Sweden)

    Xu Jing

    Full Text Available Various gaps in the surface of the supersonic aircraft have a significant effect on airflows. In order to predict the effects of attack angle, Mach number and width-to-depth ratio of gap on the local aerodynamic heating environment of supersonic flow, two-dimensional compressible Navier-Stokes equations are solved by the finite volume method, where convective flux of space term adopts the Roe format, and discretization of time term is achieved by 5-step Runge-Kutta algorithm. The numerical results reveal that the heat flux ratio is U-shaped distribution on the gap wall and maximum at the windward corner of the gap. The heat flux ratio decreases as the gap depth and Mach number increase, however, it increases as the attack angle increases. In addition, it is important to find that chamfer in the windward corner can effectively reduce gap effect coefficient. The study will be helpful for the design of the thermal protection system in reentry vehicles.

  5. Spin gap in a spiral staircase model

    Energy Technology Data Exchange (ETDEWEB)

    Kiselev, M.N. [Institut fuer Theoretische Physik und Astrophysik, Wuerzburg Universitaet, Am Hubland, D-97074 Wuerzburg (Germany)]. E-mail: kiselev@physik.uni-wuerzburg.de; Aristov, D.N. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, 70569 Stuttgart (Germany); Kikoin, K. [Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel)

    2005-04-30

    We investigate the formation of spin gap in one-dimensional models characterized by the groups with hidden symmetries. We introduce a new class of Hamiltonians for description of spin staircases-the spin systems intermediate between 2-leg ladders and S=1 spin chains. The spin exchange anisotropy along legs is described by the angle of spiral twist. The properties of a special case of spin rotator chain (SRC) corresponding to a flat 1-leg ladder is considered by means of fermionization approach based on Jordan-Wigner transformation. The influence of dynamical hidden symmetries on the scaling properties of the spin gap is discussed.

  6. Semantic Gaps Are Dangerous

    DEFF Research Database (Denmark)

    Ejstrup, Michael; le Fevre Jakobsen, Bjarne

    Semantic gaps are dangerous Language adapts to the environment where it serves as a tool to communication. Language is a social agreement, and we all have to stick to both grammaticalized and non-grammaticalized rules in order to pass information about the world around us. As such language develops...... unpolite language and tend to create dangerous relations where specialy language creates problems and trouble that could be avoided if we had better language tools at hand. But we have not these tools of communication, and we are in a situation today where media and specially digital and social media......, supported by new possibilities of migration, create dangerous situations. How can we avoid these accidental gaps in language and specially the gaps in semantic and metaphoric tools. Do we have to keep silent and stop discusing certain isues, or do we have other ways to get acces to sufficient language tools...

  7. Gap Cycling for SWIFT

    CERN Document Server

    Corum, Curtis A; Snyder, Carl J; Garwood, Michael

    2013-01-01

    Purpose: SWIFT (SWeep Imaging with Fourier Transformation) is a non- Cartesian MRI method with unique features and capabilities. In SWIFT, radiofrequency (RF) excitation and reception are performed nearly simultaneously, by rapidly switching between transmit and receive during a frequency-swept RF pulse. Because both the transmitted pulse and data acquisition are simultaneously amplitude-modulated in SWIFT (in contrast to continuous RF excitation and uninterrupted data acquisition in more familiar MRI sequences), crosstalk between different frequency bands occurs in the data. This crosstalk leads to a "bulls-eye" artifact in SWIFT images. We present a method to cancel this inter-band crosstalk by cycling the pulse and receive gap positions relative to the un-gapped pulse shape. We call this strategy "gap cycling." Methods: We carry out theoretical analysis, simulation and experiments to characterize the signal chain, resulting artifacts, and their elimination for SWIFT. Results: Theoretical analysis reveals t...

  8. Missing the gap

    DEFF Research Database (Denmark)

    Tanggaard, Lene; Glaveanu, Vlad Petre

    creative learning at the borders need not minimize differences, but handle and learn from them? If not, schools and educational institutions risk becoming bad copies of the labour marked instead of enabling students to enter the market with something new, something radically dissimilar from what......Missing the gap This paper is focused on an exploration of creative learning involved in boundary crossing (Tanggaard, 2007). Our aim is to explore the trajectories and pathways realised by students as they move from education to work and vice versa (Tanggaard & Beghetto, 2015), guided...... by the premise that difference and gaps are places where creative learning is intensified (Glaveanu & Gillespie, 2015). The public discourse around education is often concerned with minding or avoiding the gap by making education more relevant for or similar to the labour market, but what if facilitating...

  9. Gap junction communication in myelinating glia.

    Science.gov (United States)

    Nualart-Marti, Anna; Solsona, Carles; Fields, R Douglas

    2013-01-01

    Gap junction communication is crucial for myelination and axonal survival in both the peripheral nervous system (PNS) and central nervous system (CNS). This review examines the different types of gap junctions in myelinating glia of the PNS and CNS (Schwann cells and oligodendrocytes respectively), including their functions and involvement in neurological disorders. Gap junctions mediate intercellular communication among Schwann cells in the PNS, and among oligodendrocytes and between oligodendrocytes and astrocytes in the CNS. Reflexive gap junctions mediating transfer between different regions of the same cell promote communication between cellular compartments of myelinating glia that are separated by layers of compact myelin. Gap junctions in myelinating glia regulate physiological processes such as cell growth, proliferation, calcium signaling, and participate in extracellular signaling via release of neurotransmitters from hemijunctions. In the CNS, gap junctions form a glial network between oligodendrocytes and astrocytes. This transcellular communication is hypothesized to maintain homeostasis by facilitating restoration of membrane potential after axonal activity via electrical coupling and the re-distribution of potassium ions released from axons. The generation of transgenic mice for different subsets of connexins has revealed the contribution of different connexins in gap junction formation and illuminated new subcellular mechanisms underlying demyelination and cognitive defects. Alterations in metabolic coupling have been reported in animal models of X-linked Charcot-Marie-Tooth disease (CMTX) and Pelizaeus-Merzbarcher-like disease (PMLD), which are caused by mutations in the genes encoding for connexin 32 and connexin 47 respectively. Future research identifying the expression and regulation of gap junctions in myelinating glia is likely to provide a better understanding of myelinating glia in nervous system function, plasticity, and disease. This

  10. The longevity gender gap

    DEFF Research Database (Denmark)

    Aviv, Abraham; Shay, Jerry; Christensen, Kaare

    2005-01-01

    In this Perspective, we focus on the greater longevity of women as compared with men. We propose that, like aging itself, the longevity gender gap is exceedingly complex and argue that it may arise from sex-related hormonal differences and from somatic cell selection that favors cells more...... resistant to the ravages of time. We discuss the interplay of these factors with telomere biology and oxidative stress and suggest that an explanation for the longevity gender gap may arise from a better understanding of the differences in telomere dynamics between men and women....

  11. Analysis on Band Gaps of MCM-41 Type of Materials

    Institute of Scientific and Technical Information of China (English)

    HAN Pei-de; LIANG Jian; XU Bing-she; LIU Xu-guang; PENG Lian-mao

    2004-01-01

    The concept and analysis method of photonic crystals and band gaps are introduced into one-dimensional(1D) ordered mesoporous materials. MCM-41 type of materials are treated theoretically as photonic crystals. The formation of band gaps is exhibited and confirmed by a calculation of transfer matrix technique. PBG was found around 9-42 nm in soft X-ray region. The photonic band-gap was predicted to be dependent on incident direction, pore size and lattice constant. The mesoporous materials with different pore sizes and different lattice constants have different band-gap widths.

  12. Formative Assessment in Context

    Science.gov (United States)

    Oxenford-O'Brian, Julie

    2013-01-01

    This dissertation responds to critical gaps in current research on formative assessment practice which could limit successful implementation of this practice within the K-12 classroom context. The study applies a socio cultural perspective of learning to interpret a cross-case analysis of formative assessment practice occurring during one…

  13. Estimating Gender Wage Gaps

    Science.gov (United States)

    McDonald, Judith A.; Thornton, Robert J.

    2011-01-01

    Course research projects that use easy-to-access real-world data and that generate findings with which undergraduate students can readily identify are hard to find. The authors describe a project that requires students to estimate the current female-male earnings gap for new college graduates. The project also enables students to see to what…

  14. Closing the Gap

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    China's recent economic success has brought positive changes to its urban population,but left those in the countryside way behind.The gap in income and living standrs that always existed between urban and rural dwellers has widened alarmingly in the past two decades,causing serious problems.

  15. Structuring the Information Gap.

    Science.gov (United States)

    Edge, Julian

    1984-01-01

    Describes an information gap procedure to teach a new structure which requires students to look for and exchange information in order to complete a task in an English as a second language class. Illustrates the method with a set of materials and suggests ways for teachers to produce similar materials. (SED)

  16. 'Mind the Gap!'

    DEFF Research Database (Denmark)

    Persson, Karl Gunnar

    This paper challenges the widely held view that sharply falling real transport costs closed the transatlantic gap in grain prices in the second half of the 19th century. Several new results emerge from an analysis of a new data set of weekly wheat prices and freight costs from New York to UK mark...

  17. Bridging the Technological Gap.

    Science.gov (United States)

    Lazow, Robert; And Others

    The aim of "Bridging the Technological Gap" (BTG), a federally funded demonstration project, is to use microcomputer technology in the rehabilitation of the psychiatrically disabled. Through the use of a custom designed microcomputer software package, clients receive remediation in areas of specific cognitive and behavioral deficits. The project…

  18. Plasmonic band gap cavities on biharmonic gratings

    Science.gov (United States)

    Kocabas, Askin; Seckin Senlik, S.; Aydinli, Atilla

    2008-05-01

    In this paper, we have experimentally demonstrated the formation of plasmonic band gap cavities in infrared and visible wavelength range. The cavity structure is based on a biharmonic metallic grating with selective high dielectric loading. A uniform metallic grating structure enables strong surface plasmon polariton (SPP) excitation and a superimposed second harmonic component forms a band gap for the propagating SPPs. We show that a high dielectric superstructure can dramatically perturb the optical properties of SPPs and enables the control of the plasmonic band gap structure. Selective patterning of the high index superstructure results in an index contrast in and outside the patterned region that forms a cavity. This allows us to excite the SPPs that localize inside the cavity at specific wavelengths, satisfying the cavity resonance condition. Experimentally, we observe the formation of a localized state in the band gap and measure the dispersion diagram. Quality factors as high as 37 have been observed in the infrared wavelength. The simplicity of the fabrication and the method of testing make this approach attractive for applications requiring localization of propagating SPPs.

  19. The role of gap edge instabilities in setting the depth of planet gaps in protoplanetary discs

    Science.gov (United States)

    Hallam, P. D.; Paardekooper, S.-J.

    2017-08-01

    It is known that an embedded massive planet will open a gap in a protoplanetary disc via angular momentum exchange with the disc material. The resulting surface density profile of the disc is investigated for one-dimensional and two-dimensional disc models and, in agreement with previous work, it is found that one-dimensional gaps are significantly deeper than their two-dimensional counterparts for the same initial conditions. We find, by applying one-dimensional torque density distributions to two-dimensional discs containing no planet, that the excitement of the Rossby wave instability and the formation of Rossby vortices play a critical role in setting the equilibrium depth of the gap. Being a two-dimensional instability, this is absent from one-dimensional simulations and does not limit the equilibrium gap depth there. We find similar gap depths between two-dimensional gaps formed by torque density distributions, in which the Rossby wave instability is present, and two-dimensional planet gaps, in which no Rossby wave instability is present. This can be understood if the planet gap is maintained at marginal stability, even when there is no obvious Rossby wave instability present. Further investigation shows the final equilibrium gap depth is very sensitive to the form of the applied torque density distribution, and using improved one-dimensional approximations from three-dimensional simulations can go even further towards reducing the discrepancy between one- and two-dimensional models, especially for lower mass planets. This behaviour is found to be consistent across discs with varying parameters.

  20. Minding the Gap

    Energy Technology Data Exchange (ETDEWEB)

    Firestone, Millicent Anne [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-02-23

    Neutron & X-ray scattering provides nano- to meso-scale details of complex fluid structure; 1D electronic density maps dervied from SAXS yield molecular level insights; Neutron reflectivity provides substructure details of substrate supported complex fluids; Complex fluids composition can be optimized to support a wide variety of both soluble and membrane proteins; The water gap dimensions can be finely tuned through polymer component.

  1. Small Generation Gap

    Institute of Scientific and Technical Information of China (English)

    JANE SHAW

    1994-01-01

    IT was while I was making milk for my son that I discovered the generation gap between us. A little thing of two years and three months, my son stood on a big chair I brought him and joined me to make milk. Holding a small spoon in his plump little hand, he scooped flour out of a jar and poured it into the feeding bottle and then scooped milk powder and

  2. GapBlaster-A Graphical Gap Filler for Prokaryote Genomes.

    Science.gov (United States)

    de Sá, Pablo H C G; Miranda, Fábio; Veras, Adonney; de Melo, Diego Magalhães; Soares, Siomar; Pinheiro, Kenny; Guimarães, Luis; Azevedo, Vasco; Silva, Artur; Ramos, Rommel T J

    2016-01-01

    The advent of NGS (Next Generation Sequencing) technologies has resulted in an exponential increase in the number of complete genomes available in biological databases. This advance has allowed the development of several computational tools enabling analyses of large amounts of data in each of the various steps, from processing and quality filtering to gap filling and manual curation. The tools developed for gap closure are very useful as they result in more complete genomes, which will influence downstream analyses of genomic plasticity and comparative genomics. However, the gap filling step remains a challenge for genome assembly, often requiring manual intervention. Here, we present GapBlaster, a graphical application to evaluate and close gaps. GapBlaster was developed via Java programming language. The software uses contigs obtained in the assembly of the genome to perform an alignment against a draft of the genome/scaffold, using BLAST or Mummer to close gaps. Then, all identified alignments of contigs that extend through the gaps in the draft sequence are presented to the user for further evaluation via the GapBlaster graphical interface. GapBlaster presents significant results compared to other similar software and has the advantage of offering a graphical interface for manual curation of the gaps. GapBlaster program, the user guide and the test datasets are freely available at https://sourceforge.net/projects/gapblaster2015/. It requires Sun JDK 8 and Blast or Mummer.

  3. GapBlaster-A Graphical Gap Filler for Prokaryote Genomes.

    Directory of Open Access Journals (Sweden)

    Pablo H C G de Sá

    Full Text Available The advent of NGS (Next Generation Sequencing technologies has resulted in an exponential increase in the number of complete genomes available in biological databases. This advance has allowed the development of several computational tools enabling analyses of large amounts of data in each of the various steps, from processing and quality filtering to gap filling and manual curation. The tools developed for gap closure are very useful as they result in more complete genomes, which will influence downstream analyses of genomic plasticity and comparative genomics. However, the gap filling step remains a challenge for genome assembly, often requiring manual intervention. Here, we present GapBlaster, a graphical application to evaluate and close gaps. GapBlaster was developed via Java programming language. The software uses contigs obtained in the assembly of the genome to perform an alignment against a draft of the genome/scaffold, using BLAST or Mummer to close gaps. Then, all identified alignments of contigs that extend through the gaps in the draft sequence are presented to the user for further evaluation via the GapBlaster graphical interface. GapBlaster presents significant results compared to other similar software and has the advantage of offering a graphical interface for manual curation of the gaps. GapBlaster program, the user guide and the test datasets are freely available at https://sourceforge.net/projects/gapblaster2015/. It requires Sun JDK 8 and Blast or Mummer.

  4. What is the Mass of a Gap-opening Planet?

    Science.gov (United States)

    Dong, Ruobing; Fung, Jeffrey

    2017-02-01

    High-contrast imaging instruments such as GPI and SPHERE are discovering gap structures in protoplanetary disks at an ever faster pace. Some of these gaps may be opened by planets forming in the disks. In order to constrain planet formation models using disk observations, it is crucial to find a robust way to quantitatively back out the properties of the gap-opening planets, in particular their masses, from the observed gap properties, such as their depths and widths. Combining 2D and 3D hydrodynamics simulations with 3D radiative transfer simulations, we investigate the morphology of planet-opened gaps in near-infrared scattered-light images. Quantitatively, we obtain correlations that directly link intrinsic gap depths and widths in the gas surface density to observed depths and widths in images of disks at modest inclinations under finite angular resolution. Subsequently, the properties of the surface density gaps enable us to derive the disk scale height at the location of the gap h, and to constrain the quantity Mp2/α, where Mp is the mass of the gap-opening planet and α characterizes the viscosity in the gap. As examples, we examine the gaps recently imaged by VLT/SPHERE, Gemini/GPI, and Subaru/HiCIAO in HD 97048, TW Hya, HD 169142, LkCa 15, and RX J1615.3-3255. Scale heights of the disks and possible masses of the gap-opening planets are derived assuming each gap is opened by a single planet. Assuming α = 10‑3, the derived planet masses in all cases are roughly between 0.1 and 1 MJ.

  5. Gap Opening in 3D: Single Planet Gaps

    CERN Document Server

    Fung, Jeffrey

    2016-01-01

    Giant planets can clear deep gaps when embedded in 2D (razor-thin) viscous circumstellar disks. We show by direct simulation that giant planets are just as capable of carving out gaps in 3D. Surface density maps are similar between 2D and 3D, even in detail. In particular, the scaling $\\Sigma_{\\rm gap} \\propto q^{-2}$ of gap surface density with planet mass, derived from a global "zero-dimensional" balance of Lindblad and viscous torques, applies equally well to results obtained at higher dimensions. Our 3D simulations reveal extensive, near-sonic, meridional flows both inside and outside the gaps; these large-scale circulations might bear on disk compositional gradients, in dust or other chemical species. At high planet mass, gap edges are mildly Rayleigh unstable and intermittently shed streams of material into the gap - less so in 3D than in 2D.

  6. Unveiling the Gap

    DEFF Research Database (Denmark)

    Jensson, Pall; Rokkjær, Ole; Nørgaard, Bente

    discussing their NQF and Sweden has decided not to adjust to the EQF for the moment. Analysis of the subject focus for the individual programmes showed a high degree of variation. In the context of CDIO this means that what seems to be a well-known and commonly accepted definition of a discipline like IE...... needs, how universities decide what to teach, and how to bridge the gap. Do the university programs simply reflect the expertise of the faculty members? Is there need for increasing emphasis on continuing education? Is life-long education the answer, and has this been addressed by the CDIO community?...

  7. Mind the gap

    Energy Technology Data Exchange (ETDEWEB)

    Bhagwat, M.S.; Roberts, C.D. [Argonne National Laboratory, Physics Division, Argonne, IL (United States); Krassnigg, A. [Universitaet Graz, Fachbereich Theoretische Physik, Graz (Austria); Maris, P. [University of Pittsburgh, Department of Physics and Astronomy, PA (United States)

    2007-03-15

    In this summary of the application of Dyson-Schwinger equations to the theory and phenomenology of hadrons, some deductions following from a nonperturbative, symmetry-preserving truncation are highlighted, notable amongst which are results for pseudoscalar mesons. We also describe inferences from the gap equation relating to the radius of convergence of a chiral expansion, applications to heavy-light and heavy-heavy mesons, and quantitative estimates of the contribution of quark orbital angular momentum in pseudoscalar mesons; and recapitulate upon studies of nucleon electromagnetic form factors. (orig.)

  8. Mind the gap.

    Energy Technology Data Exchange (ETDEWEB)

    Bhagwat, M. S.; Krassnigg, A.; Maris, P.; Roberts, C. D.; Physics; Univ. Graz; Univ. of Pittsburgh

    2007-03-01

    In this summary of the application of Dyson-Schwinger equations to the theory and phenomenology of hadrons, some deductions following from a nonperturbative, symmetry-preserving truncation are highlighted, notable amongst which are results for pseudoscalar mesons. We also describe inferences from the gap equation relating to the radius of convergence of a chiral expansion, applications to heavy-light and heavy-heavy mesons, and quantitative estimates of the contribution of quark orbital angular momentum in pseudoscalar mesons; and recapitulate upon studies of nucleon electromagnetic form factors.

  9. Photonic band gap materials

    Science.gov (United States)

    Cassagne, D.

    Photonic band gap materials Photonic band gap materials are periodic dielectric structures that control the propagation of electromagnetic waves. We describe the plane wave method, which allows to calculate the band structures of photonic crystals. By symmetry analysis and a perturbative approach, we predict the appearance of the low energy photonic band gaps of hexagonal structures. We propose new two-dimensional structures called graphite and boron nitride. Using a transfer matrix method, we calculate the transmission of the graphite structure and we show the crucial role of the coupling with external modes. We study the appearance of allowed modes in the photonic band gap by the introduction of localized defects in the periodicity. Finally, we discuss the properties of opals formed by self-organized silica microspheres, which are very promising for the fabrication of three-dimensional photonic crystals. Les matériaux à bandes interdites photoniques sont des structures diélectriques périodiques qui contrôlent la propagation des ondes électromagnétiques. Nous décrivons la méthode des ondes planes qui permet de calculer les structures de bandes des cristaux photoniques. Par une analyse de la symétrie et une approche perturbative, nous précisons les conditions d'existence des bandes interdites de basse énergie. Nous proposons de nouvelles structures bidimensionnelles appelées graphite et nitrure de bore. Grâce à une méthode de matrices de transfert, nous calculons la transmission de la structure graphite et nous mettons en évidence le rôle fondamental du couplage avec les modes extérieurs. Nous étudions l'apparition de modes permis dans la bande interdite grâce à l'introduction de défauts dans la périodicité. Enfin, nous discutons les propriétés des opales constituées de micro-billes de silice auto-organisées, qui sont très prometteuses pour la fabrication de cristaux photoniques tridimensionnels.

  10. Closing the stop gap

    Energy Technology Data Exchange (ETDEWEB)

    Czakon, Michal [RWTH Aachen Univ. (Germany). Inst. fuer Theoretische Teilchnphysik und Kosmologie; Mitov, Alexander [Univ. of Cambridge (United Kingdom). Cavendish Lab.; Papucci, Michele [Lawrence Berkeley National Laboratory, CA (United States). Theoretical Physics Group; California Univ., Berkeley, CA (United States). Dept. of Physics; Ruderman, Joshua T. [Lawrence Berkeley National Laboratory, CA (United States). Theoretical Physics Group; California Univ., Berkeley, CA (United States). Dept. of Physics; New York Univ., NY (United States). Center for Cosmology and Particle Physics; Weiler, Andreas [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); CERN - European Organization for Nuclear Research, Geneva (Switzerland). Theory Div.

    2014-07-15

    Light stops are a hallmark of the most natural realizations of weak-scale supersymmetry. While stops have been extensively searched for, there remain open gaps around and below the top mass, due to similarities of stop and top signals with current statistics. We propose a new fast-track avenue to improve light stop searches for R-parity conserving supersymmetry, by comparing top cross section measurements to the theoretical prediction. Stop masses below ∝180 GeV can now be ruled out for a light neutralino. The possibility of a stop signal contaminating the top mass measurement is also briefly addressed.

  11. Mind the Gap

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    While a growing number of Chinese people are enjoying the benefits brought by economic reform and social development, some are being left behind. The divide between the rich and the poor is widening in China, resulting in an increasingly dissatisfied populace. Some argue that a wealth gap is not a big deal in a market economy and that the problem in China has been exaggerated. But in an article published by China Economic Times, Wu Zhongmin, a sociology professor at the Central Party School of the Commun...

  12. Board affiliation and pay gap

    Institute of Scientific and Technical Information of China (English)

    Shenglan; Chen; Hui; Ma; Danlu; Bu

    2014-01-01

    This paper examines the effects of board affiliation on the corporate pay gap.Using a sample of Chinese listed firms from 2005 to 2011, we find that boards with a greater presence of directors appointed by block shareholders have lower pay gaps. Furthermore, the governance effects of board affiliation with and without pay are distinguished. The empirical results show that board affiliation without pay is negatively related to the pay gap, while board affiliation with pay is positively related to the pay gap. Overall, the results shed light on how block shareholders affect their companies’ pay gaps through board affiliation.

  13. Gap Task Force

    CERN Multimedia

    Lissuaer, D

    One of the more congested areas in the ATLAS detector is the GAP region (the area between the Barrel Calorimeter and the End Cap calorimeter) where Inner Detector services, LAr Services and some Tile services all must co-habitat in a very limited area. It has been clear for some time that the space in the GAP region is not sufficient to accommodate all that is needed. In the last few month additional problems of routing all the services to Z=0 have been encountered due to the very limited space between the Tile Calorimeter and the first layer of Muon chambers. The Technical Management Board (TMB) and the Executive Board (EB) decided in the middle of March to establish a Task Force to look at this problem and come up with a solution within well-specified guidelines. The task force consisted of experts from the ID, Muon, Liquid Argon and Tile systems in addition to experts from the Technical Coordination team and the Physics coordinator. The task force held many meetings and in general there were some very l...

  14. The Politics of Achievement Gaps

    DEFF Research Database (Denmark)

    Valant, J.; Newark, D. A.

    2016-01-01

    on achievement gaps have received little attention from researchers, despite playing an important role in shaping policymakers’ behaviors. Drawing on randomized experiments with a nationally representative sample of adults, we explore the public’s beliefs about test score gaps and its support for gap......-closing initiatives. We find that Americans are more concerned about—and more supportive of proposals to close—wealth-based achievement gaps than Black-White or Hispanic-White gaps. Americans also explain the causes of wealth-based gaps more readily. © 2016 AERA.......For decades, researchers have documented large differences in average test scores between minority and White students and between poor and wealthy students. These gaps are a focal point of reformers’ and policymakers’ efforts to address educational inequities. However, the U.S. public’s views...

  15. Small Multiples with Gaps.

    Science.gov (United States)

    Meulemans, Wouter; Dykes, Jason; Slingsby, Aidan; Turkay, Cagatay; Wood, Jo

    2017-01-01

    Small multiples enable comparison by providing different views of a single data set in a dense and aligned manner. A common frame defines each view, which varies based upon values of a conditioning variable. An increasingly popular use of this technique is to project two-dimensional locations into a gridded space (e.g. grid maps), using the underlying distribution both as the conditioning variable and to determine the grid layout. Using whitespace in this layout has the potential to carry information, especially in a geographic context. Yet, the effects of doing so on the spatial properties of the original units are not understood. We explore the design space offered by such small multiples with gaps. We do so by constructing a comprehensive suite of metrics that capture properties of the layout used to arrange the small multiples for comparison (e.g. compactness and alignment) and the preservation of the original data (e.g. distance, topology and shape). We study these metrics in geographic data sets with varying properties and numbers of gaps. We use simulated annealing to optimize for each metric and measure the effects on the others. To explore these effects systematically, we take a new approach, developing a system to visualize this design space using a set of interactive matrices. We find that adding small amounts of whitespace to small multiple arrays improves some of the characteristics of 2D layouts, such as shape, distance and direction. This comes at the cost of other metrics, such as the retention of topology. Effects vary according to the input maps, with degree of variation in size of input regions found to be a factor. Optima exist for particular metrics in many cases, but at different amounts of whitespace for different maps. We suggest multiple metrics be used in optimized layouts, finding topology to be a primary factor in existing manually-crafted solutions, followed by a trade-off between shape and displacement. But the rich range of possible

  16. Gaps in Political Interest

    DEFF Research Database (Denmark)

    Robison, Joshua

    2015-01-01

    sought to measure respondents’ general interest in politics by asking them how often they follow public affairs. In this article, we uncover novel sources of measurement error concerning this question. We first show that other nationally representative surveys that frequently use this item deliver......Political interest fundamentally influences political behavior, knowledge, and persuasion (Brady, Verba, & Schlozman, 1995; Delli Carpini & Keeter, 1996; Luskin, 1990; Zukin, Andolina, Keeter, Jenkins, & Delli Carpini, 2006). Since the early 1960s, the American National Election Studies (ANES) has...... drastically higher estimates of mass interest. We then use a survey experiment included on a wave of the ANES’ Evaluating Government and Society Surveys (EGSS) to explore the influence of question order in explaining this systemic gap in survey results. We show that placing batteries of political...

  17. Closing the Gap

    DEFF Research Database (Denmark)

    Tamke, Martin; Kobiella, Olaf

    2007-01-01

    The e4d design series is looking for an innovative use of digital technology in architectural education to overcome the gap between design development and the acquisition of digital skills. Digital design approaches include multimedia technology, the crossover of analogue and digital techniques......, rapid-prototyping, visualization, and the presentation in artistic movies. Over the past two years a problem- based design approach was developed, which enabled students to learn digital and architectural skills simultaneously and efficiently. The educational concept consisted generally of four steps......, which, though independent of each other, are determined by questions of the ongoing design process. The first step consists of an abstract or subjective research phase; in the second step the findings are transferred into dynamic spatial structures. Later, the detected qualities are used to develop...

  18. Closing the Gap

    DEFF Research Database (Denmark)

    Tamke, Martin; Kobiella, Olaf

    2007-01-01

    The e4d design series is looking for an innovative use of digital technology in architectural education to overcome the gap between design development and the acquisition of digital skills. Digital design approaches include multimedia technology, the crossover of analogue and digital techniques......, rapid-prototyping, visualization, and the presentation in artistic movies. Over the past two years a problem- based design approach was developed, which enabled students to learn digital and architectural skills simultaneously and efficiently. The educational concept consisted generally of four steps...... architectural projects can be discussed; in addition, a competent monitoring of the process and outcome of innovative and efficient design strategies in architectural and pedagogical aspect is included....

  19. The Gap-Tpc

    Science.gov (United States)

    Rossi, B.; Anastasio, A.; Boiano, A.; Catalanotti, S.; Cocco, A. G.; Covone, G.; Di Meo, P.; Longo, G.; Vanzanella, A.; Walker, S.; Wang, H.; Wang, Y.; Fiorillo, G.

    2016-02-01

    Several experiments have been conducted worldwide, with the goal of observing low-energy nuclear recoils induced by WIMPs scattering off target nuclei in ultra-sensitive, low-background detectors. In the last few decades noble liquid detectors designed to search for dark matter in the form of WIMPs have been extremely successful in improving their sensitivities and setting the best limits. One of the crucial problems to be faced for the development of large size (multi ton-scale) liquid argon experiments is the lack of reliable and low background cryogenic PMTs: their intrinsic radioactivity, cost, and borderline performance at 87 K rule them out as a possible candidate for photosensors. We propose a brand new concept of liquid argon-based detector for direct dark matter search: the Geiger-mode Avalanche Photodiode Time Projection Chamber (GAP-TPC) optimized in terms of residual radioactivity of the photosensors, energy and spatial resolution, light and charge collection efficiency.

  20. The GAP-TPC

    CERN Document Server

    Rossi, B; Boiano, A; Catalanotti, S; Cocco, A G; Covone, G; Di Meo, P; Longo, G; Vanzanella, A; Walker, S; Wang, H; Wang, Y; Fiorillo, G

    2016-01-01

    Several experiments have been conducted worldwide, with the goal of observing low-energy nuclear recoils induced by WIMPs scattering off target nuclei in ultra-sensitive, low-background detectors. In the last few decades noble liquid detectors designed to search for dark matter in the form of WIMPs have been extremely successful in improving their sensitivities and setting the best limits. One of the crucial problems to be faced for the development of large size (multi ton-scale) liquid argon experiments is the lack of reliable and low background cryogenic PMTs: their intrinsic radioactivity, cost, and borderline performance at 87 K rule them out as a possible candidate for photosensors. We propose a brand new concept of liquid argon-based detector for direct dark matter search: the Geiger-mode Avalanche Photodiode Time Projection Chamber (GAP-TPC) optimized in terms of residual radioactivity of the photosensors, energy and spatial resolution, light and charge collection efficiency

  1. Closing the Gap

    DEFF Research Database (Denmark)

    Tamke, Martin; Kobiella, Olaf

    2007-01-01

    The e4d design series is looking for an innovative use of digital technology in architectural education to overcome the gap between design development and the acquisition of digital skills. Digital design approaches include multimedia technology, the crossover of analogue and digital techniques...... architectural projects can be discussed; in addition, a competent monitoring of the process and outcome of innovative and efficient design strategies in architectural and pedagogical aspect is included......., rapid-prototyping, visualization, and the presentation in artistic movies. Over the past two years a problem- based design approach was developed, which enabled students to learn digital and architectural skills simultaneously and efficiently. The educational concept consisted generally of four steps...

  2. Gap bridging enhancement of modified Urca process in nuclear matter

    CERN Document Server

    Alford, Mark G

    2016-01-01

    In nuclear matter at neutron-star densities and temperatures, Cooper pairing leads to the formation of a gap in the nucleon excitation spectra resulting in exponentially strong Boltzmann suppression of many transport coefficients. Previous calculations have shown evidence that density oscillations of sufficiently large amplitude can overcome this suppression for flavor-changing beta processes, via the mechanism of "gap bridging". We address the simplifications made in that initial work, and show that gap bridging can counteract Boltzmann suppression of neutrino emissivity for the realistic case of modified Urca processes in matter with $^3P_2$ neutron pairing.

  3. Hydrogeologic Model for the Gable Gap Area, Hanford Site

    Energy Technology Data Exchange (ETDEWEB)

    Bjornstad, Bruce N.; Thorne, Paul D.; Williams, Bruce A.; Last, George V.; Thomas, Gregory S.; Thompson, Michael D.; Ludwig, Jami L.; Lanigan, David C.

    2010-09-30

    Gable Gap is a structural and topographic depression between Gable Mountain and Gable Butte within the central Hanford Site. It has a long and complex geologic history, which includes tectonic uplift synchronous with erosional downcutting associated with the ancestral Columbia River during both Ringold and Cold Creek periods, and by the later Ice Age (mostly glacial Lake Missoula) floods. The gap was subsequently buried and partially backfilled by mostly coarse-grained, Ice Age flood deposits (Hanford formation). Erosional remnants of both the Ringold Formation and Cold Creek unit locally underlie the high-energy flood deposits. A large window exists in the gap where confined basalt aquifers are in contact with the unconfined suprabasalt aquifer. Several paleochannels, of both Hanford and Ringold Formation age, were eroded into the basalt bedrock across Gable Gap. Groundwater from the Central Plateau presently moves through Gable Gap via one or more of these shallow paleochannels. As groundwater levels continue to decline in the region, groundwater flow may eventually be cut off through Gable Gap.

  4. Seed arrival in tropical forest tree fall gaps.

    Science.gov (United States)

    Puerta-Pińero, Carolina; Muller-Landau, Helene C; Calderón, Osvaldo; Wright, S Joseph

    2013-07-01

    Tree deaths open gaps in closed-canopy forests, which allow light to reach the forest floor and promote seed germination and seedling establishment. Gap dependence of regeneration is an important axis of life history variation among forest plant species, and many studies have evaluated how plant species differ in seedling and sapling performance in gaps. However, relatively little is known about how seed arrival in gaps compares with seed arrival in the understory, even though seed dispersal by wind and animals is expected to be altered in gaps. We documented seed arrival for the first seven years after gap formation in the moist tropical forests of Barro Colorado Island (BCI), Panama, and evaluated how the amount and functional composition of arriving seeds compared with understory sites. On average, in the first three years after gap formation, 72% fewer seeds arrived in gaps than in the understory (207 vs. 740 seeds x m(-2) x yr(-1)). The reduction in number of arriving seeds fell disproportionately on animal-dispersed species, which suffered an 86% reduction in total seed number, while wind-dispersed species experienced only a 47% reduction, and explosively dispersed species showed increased seed numbers arriving. The increase in explosively dispersed seeds consisted entirely of the seeds of several shrub species, a result consistent with greater in situ seed production by explosively dispersed shrubs that survived gap formation or recruited immediately thereafter. Lianas did relatively better in seed arrival into gaps than did trees, suffering less of a reduction in seed arrival compared with understory sites. This result could in large part be explained by the greater predominance of wind dispersal among lianas: there were no significant differences between lianas and trees when controlling for dispersal syndromes. Our results show that seed arrival in gaps is very different from seed arrival in the understory in both total seeds arriving and functional

  5. The inverse F-BAR domain protein srGAP2 acts through srGAP3 to modulate neuronal differentiation and neurite outgrowth of mouse neuroblastoma cells.

    Directory of Open Access Journals (Sweden)

    Yue Ma

    Full Text Available The inverse F-BAR (IF-BAR domain proteins srGAP1, srGAP2 and srGAP3 are implicated in neuronal development and may be linked to mental retardation, schizophrenia and seizure. A partially overlapping expression pattern and highly similar protein structures indicate a functional redundancy of srGAPs in neuronal development. Our previous study suggests that srGAP3 negatively regulates neuronal differentiation in a Rac1-dependent manner in mouse Neuro2a cells. Here we show that exogenously expressed srGAP1 and srGAP2 are sufficient to inhibit valporic acid (VPA-induced neurite initiation and growth in the mouse Neuro2a cells. While ectopic- or over-expression of RhoGAP-defective mutants, srGAP1(R542A and srGAP2(R527A exert a visible inhibitory effect on neuronal differentiation. Unexpectedly, knockdown of endogenous srGAP2 fails to facilitate the neuronal differentiation induced by VPA, but promotes neurite outgrowth of differentiated cells. All three IF-BAR domains from srGAP1-3 can induce filopodia formation in Neuro2a, but the isolated IF-BAR domain from srGAP2, not from srGAP1 and srGAP3, can promote VPA-induced neurite initiation and neuronal differentiation. We identify biochemical and functional interactions of the three srGAPs family members. We propose that srGAP3-Rac1 signaling may be required for the effect of srGAP1 and srGAP2 on attenuating neuronal differentiation. Furthermore, inhibition of Slit-Robo interaction can phenocopy a loss-of-function of srGAP3, indicating that srGAP3 may be dedicated to the Slit-Robo pathway. Our results demonstrate the interplay between srGAP1, srGAP2 and srGAP3 regulates neuronal differentiation and neurite outgrowth. These findings may provide us new insights into the possible roles of srGAPs in neuronal development and a potential mechanism for neurodevelopmental diseases.

  6. Filling the Gondwanan gap

    DEFF Research Database (Denmark)

    Cole, Selina R.; Ausich, William I.; Colmenar Lallena, Jorge

    2017-01-01

    A diverse crinoid fauna is described from the Upper Ordovician (Katian) Fombuena Formation from the eastern Iberian Chains of Spain. New crinoids include the diplobathrid camerates Fombuenacrinus nodulus n. gen. n. Sp., Goyacrinus gutierrezi n. gen. n. Sp., Dalicrinus hammanni n. gen. n. Sp., and...

  7. The Adaptation Finance Gap Report

    DEFF Research Database (Denmark)

    UNEP’s Adaptation Gap Report series focuses on Finance, Technology and Knowledge gaps in climate change adaptation. It compliments the Emissions Gap Report series, and explores the implications of failing to close the emissions gap. The report builds on a 2014 assessment by the United Nations...... Environment Programme (UNEP), which laid out the concept of ‘adaptation gaps’ and outlined three such gaps: technology, finance and knowledge. The 2016 Adaptation Gap Report assesses the difference between the financial costs of adapting to climate change in developing countries and the amount of money...... actually available to meet these costs – a difference known as the “adaptation finance gap”. Like the 2014 report, the 2016 report focuses on developing countries, where adaptation capacity is often the lowest and needs the highest, and concentrates on the period up to 2050. The report identifies trends...

  8. Understanding the Tax Gap1

    OpenAIRE

    Mazur, Mark J.; Plumley, Alan H.

    2007-01-01

    The Tax Gap is defined as the difference between the amount of tax imposed by the Tax Code and the amount that is reported and paid with timely filed returns. For the federal government, the gross tax gap is estimated at $345 billion for Tax Year 2001 (after the collection of late and enforced payments, the net tax gap is estimated at $290 billion for Tax Year 2001). This paper explains the concept of the tax gap, discusses how it is estimated, and points out some limitations with the estimates.

  9. Measuring the Gap

    Directory of Open Access Journals (Sweden)

    Xinshu She MD, MPH

    2016-02-01

    Full Text Available China is a large country where rapid development is accompanied by growing inequalities. How economic inequalities translate to health inequalities is unknown. Baseline health assessment is lacking among rural Chinese children. We aimed at assessing baseline student health of rural Chinese children and comparing them with those of urban children of similar ages. A cross-sectional study was conducted using the 2003 Global School-Based Student Health Survey among 100 students Grade 4 to 6 from rural Guizhou, China. Results were summarized and compared with public data from urban Beijing using multivariate logistic regression models. Rural children are more likely to not wash their hands before a meal (odds ratio [OR] = 5.71, P .05. Rural parents are more likely to not know their children’s whereabouts (OR = 1.81, P < .05. Rural children are more than 4 times likely to have serious injuries (OR = 4.64, P < .01 and to be bullied (OR = 4.01, P < .01. In conclusion, school-age rural Chinese children exhibit more health risk behaviors and fewer protective factors at baseline compared to their urban counterparts. Any intervention aimed at improving child health should take this distributive gap into consideration.

  10. Measuring the Gap

    Science.gov (United States)

    She, Xinshu; Zhao, Deqing; Scholnick, Jenna

    2016-01-01

    China is a large country where rapid development is accompanied by growing inequalities. How economic inequalities translate to health inequalities is unknown. Baseline health assessment is lacking among rural Chinese children. We aimed at assessing baseline student health of rural Chinese children and comparing them with those of urban children of similar ages. A cross-sectional study was conducted using the 2003 Global School-Based Student Health Survey among 100 students Grade 4 to 6 from rural Guizhou, China. Results were summarized and compared with public data from urban Beijing using multivariate logistic regression models. Rural children are more likely to not wash their hands before a meal (odds ratio [OR] = 5.71, P suicidal ideation in the past year (OR = 0.68, P > .05). Rural parents are more likely to not know their children’s whereabouts (OR = 1.81, P bullied (OR = 4.01, P < .01). In conclusion, school-age rural Chinese children exhibit more health risk behaviors and fewer protective factors at baseline compared to their urban counterparts. Any intervention aimed at improving child health should take this distributive gap into consideration. PMID:27335999

  11. GAP Analysis. Bulletin Number 11

    Science.gov (United States)

    2002-01-01

    in 2002 ( ESSB • Creation of a stewardship map is central to GAP’s analysis 6400) that authorizes a comprehensive review to identify the state’s method...governments and their consultants. "Washington State Law ESSB 6400 can be accessed at www.leg.wa.gov/pubfbillinfo/2001-02/Senate, January 10, 2003. Gap

  12. PhoneGap for enterprise

    CERN Document Server

    Shotts, Kerri

    2014-01-01

    This book is intended for developers who wish to use PhoneGap to develop useful, rich, secure mobile applications for their enterprise environment. The book assumes you have working knowledge of PhoneGap, HTML5, CSS3, and JavaScript, and a reasonable understanding of networking and n-tier architectures.

  13. Components of the Belief Gap

    Directory of Open Access Journals (Sweden)

    Cecilie Gaziano

    2014-01-01

    Full Text Available Knowledge gap research focuses on education as an indicator of socioeconomic status (SES. Belief gap research centers on ideology as potentially more powerful than education in comparing sociopolitical groups with scientifically established knowledge and groups with opposing beliefs accepted on faith. This study examined the relationship between education and ideology to understand belief gaps better. The study used 2008 American National Election Study (ANES data to compare conservatives, moderates, and liberals by education on religiosity, child rearing values, opinionation, need for cognition, orientation toward politics, and mass media access and use. Although liberals tended to be more educated than conservatives overall, better-educated conservatives had the highest household incomes and were a much larger group. No known knowledge gap studies have reported results on one group characterized by high education and an opposing group distinguished by a different indicator of SES. Reformulations of the belief gap hypothesis are offered.

  14. GAP Analysis Bulletin Number 15

    Science.gov (United States)

    Maxwell, Jill; Gergely, Kevin; Aycrigg, Jocelyn; Canonico, Gabrielle; Davidson, Anne; Coffey, Nicole

    2008-01-01

    The Mission of the Gap Analysis Program (GAP) is to promote conservation by providing broad geographic information on biological diversity to resource managers, planners, and policy makers who can use the information to make informed decisions. As part of the National Biological Information Infrastructure (NBII) ?a collaborative program to provide increased access to data and information on the nation?s biological resources--GAP data and analytical tools have been used in hundreds of applications: from basic research to comprehensive state wildlife plans; from educational projects in schools to ecoregional assessments of biodiversity. The challenge: keeping common species common means protecting them BEFORE they become threatened. To do this on a state or regional basis requires key information such as land cover descriptions, predicted distribution maps for native animals, and an assessment of the level of protection currently given to those plants and animals. GAP works cooperatively with Federal, state, and local natural resource professionals and academics to provide this kind of information. GAP activities focus on the creation of state and regional databases and maps that depict patterns of land management, land cover, and biodiversity. These data can be used to identify ?gaps? in conservation--instances where an animal or plant community is not adequately represented on the existing network of conservation lands. GAP is administered through the U.S. Geological Survey. Through building partnerships among disparate groups, GAP hopes to foster the kind of collaboration that is needed to address conservation issues on a broad scale. For more information, contact: John Mosesso National GAP Director 703-648-4079 Kevin Gergely National GAP Operations Manager 208-885-3565

  15. Three-dimensional patterns in dielectric barrier discharge with "H" shaped gas gap

    Science.gov (United States)

    Gao, Xing; Dong, Lifang; Wang, Hao; Zhang, Hao; Liu, Ying; Liu, Weibo; Fan, Weili; Pan, Yuyang

    2016-08-01

    Three-dimensional (3D) patterns are obtained for the first time in dielectric barrier discharge by a special designed device with "H" shaped gas gap which consists of a single gas layer gap and two double gas layer gaps. Three dimensional spatiotemporal characteristics of discharge are investigated by photomultiplier and intensified charge-coupled device camera. Results show that the discharge first generates in the single gas layer gap and the coupled filaments in the double gas layer gap present the simultaneity characteristics. The formation of 3D patterns is determined by the distribution of the effective field of the applied field and the wall charge field.

  16. Binary-disk interaction: Gap-Opening criteria

    CERN Document Server

    del Valle, Luciano

    2012-01-01

    We study the interaction of an equal mass binary with an isothermal circumbinary disk motivated by the theoretical and observational evidence of the formation of massive black holes binaries surrounded by gas, after a major merger of gas-rich galaxies. We focus on the torques that the binary produces on the disk and how the exchange of angular momentum can drive the formation of a gap on it. We propose that the angular momentum exchange between the binary and the disk is through the gravitational interaction of the binary and a (tidally formed) global non-axisymmetric perturbation in the disk. Using this gravitational interaction we derive an analytic criterion for the formation of a gap in the disk that can be expressed on the structural parameters h/a and M(< r)/M_{bin}. Using SPH simulations we show that the simulations where the binary opens a gap in the disk and the simulations where the disk does not have a gap are distributed in two well separate regions. Our analytic gap-opening criterion predicts ...

  17. The fluctuating gap model

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Xiaobin

    2011-01-15

    The quasi-one-dimensional systems exhibit some unusual phenomenon, such as the Peierls instability, the pseudogap phenomena and the absence of a Fermi-Dirac distribution function line shape in the photoemission spectroscopy. Ever since the discovery of materials with highly anisotropic properties, it has been recognized that fluctuations play an important role above the three-dimensional phase transition. This regime where the precursor fluctuations are presented can be described by the so called fluctuating gap model (FGM) which was derived from the Froehlich Hamiltonian to study the low energy physics of the one-dimensional electron-phonon system. Not only is the FGM of great interest in the context of quasi-one-dimensional materials, liquid metal and spin waves above T{sub c} in ferromagnets, but also in the semiclassical approximation of superconductivity, it is possible to replace the original three-dimensional problem by a directional average over effectively one-dimensional problem which in the weak coupling limit is described by the FGM. In this work, we investigate the FGM in a wide temperature range with different statistics of the order parameter fluctuations. We derive a formally exact solution to this problem and calculate the density of states, the spectral function and the optical conductivity. In our calculation, we show that a Dyson singularity appears in the low energy density of states for Gaussian fluctuations in the commensurate case. In the incommensurate case, there is no such kind of singularity, and the zero frequency density of states varies differently as a function of the correlation lengths for different statistics of the order parameter fluctuations. Using the density of states we calculated with non-Gaussian order parameter fluctuations, we are able to calculate the static spin susceptibility which agrees with the experimental data very well. In the calculation of the spectral functions, we show that as the correlation increases, the

  18. Coherent Structures near Narrow Gaps in Channel Flows

    Science.gov (United States)

    Guellouz, M. S.; Tavoularis, S.

    1996-11-01

    Flow visualization and hot-wire anemometry were used to investigate the velocity field in axial flow within a rectangular channel containing a single cylindrical rod, parallel to the channel's axis and positioned at different distances from the wall. The formation of a street of three-dimensional, quasi-periodic, counter-rotating vortices in the vicinity of the gap has been observed, even for relatively large gaps. The Strouhal number, convection speed and streamwise spacing of these vortices have been determined as functions of the gap size and the flow parameters. A useful feature of these vortices is the large-scale transport of fluid across the gap, which enhances momentum, heat and mass transfer.

  19. More on gapped Goldstones at finite density: More gapped Goldstones

    CERN Document Server

    Nicolis, Alberto; Piazza, Federico; Rosen, Rachel A

    2013-01-01

    It was recently argued that certain relativistic theories at finite density can exhibit an unconventional spectrum of Goldstone excitations, with gapped Goldstones whose gap is exactly calculable in terms of the symmetry algebra. We confirm this result as well as previous ones concerning gapless Goldstones for non-relativistic systems via a coset construction of the low-energy effective field theory. Moreover, our analysis unveils additional gapped Goldstones, naturally as light as the others, but this time with a model-dependent gap. Their exact number cannot be inferred solely from the symmetry breaking pattern either, but rather depends on the details of the symmetry breaking mechanism--a statement that we explicitly verify with a number of examples. Along the way we provide what we believe to be a particularly transparent interpretation of the so-called inverse-Higgs constraints for spontaneously broken spacetime symmetries.

  20. The Income Gap GROWS Large

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The income gap between regions, urban and rural areas, industries and various social groups is widening in China. The gap, as indicated by the Gini Coefficient, extended beyond an alarming level. A World Bank report said the Gini Coefficient for China surged to 0.47 in 2009, exceeding the "red line" of 0.4. The problems caused by the rising income disparity have been the focus of public attention. Some experts believe that it is high time for China to shrink this income gap. A Xinhua News Agency research team recently analyzed this trend, and published an article in the Economic Information Daily. Edited excerpts follow:

  1. The Income Gap Grows Large

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ The income gap between regions,urban and rural areas,industries and various social groups is widening in China.The gap,as indicated by the Gini Coefficient,extended beyond an alarming level.A World Bank report said the Gini Coefficient for China surged to 0A7 in 2009,exceeding the "red line"of 0.4.The problems caused by the rising income disparity have been the focus of public attention.Some experts believe that it is high time for China to shrink this income gap.

  2. The liquid metastable miscibility gap in Cu-based systems

    DEFF Research Database (Denmark)

    Curiotto, S.; Greco, R.; Pryds, Nini

    2007-01-01

    . In order to predict the phase equilibria and the mechanisms of microstructure formation, a determination of the metastable monotectics in the phase diagrams is essential. This paper focuses on the up-to-date findings on the Cu–Co, Cu–Fe and Cu–Co–Fe metastable miscibility gap in the liquid phase...

  3. Gap Surface Plasmon Waveguide Analysis

    DEFF Research Database (Denmark)

    Nielsen, Michael Grøndahl; Bozhevolnyi, Sergey I.

    2014-01-01

    Plasmonic waveguides supporting gap surface plasmons (GSPs) localized in a dielectric spacer between metal films are investigated numerically and the waveguiding properties at telecommunication wavelengths are presented. Especially, we emphasize that the mode confinement can advantageously...

  4. Talent Management: Bridging the Gap

    Science.gov (United States)

    2015-06-12

    Cooper and Colton, you are the greatest gift I could have ever imagined. Daddy’s done with his homework and now we can go to the park–I promise...45 Gap 4: Up-Or-Out Promotions ..................................................................................... 49

  5. Closing the Cybersecurity Skills Gap

    Directory of Open Access Journals (Sweden)

    Rebecca Vogel

    2016-05-01

    Full Text Available The current consensus is that there is a worldwide gap in skills needed for a competent cybersecurity workforce. This skills gap has implications for the national security sector, both public and private. Although the view is that this will take a concerted effort to rectify, it presents an opportunity for IT professionals, university students, and aspirants to take-up jobs in national security national intelligence as well military and law enforcement intelligence. This paper examines context of the issue, the nature of the cybersecurity skills gap, and some key responses by governments to address the problem. The paper also examines the emerging employment trends, some of the employment challenges, and what these might mean for practice. The paper argues that the imperative is to close the cyber skills gap by taking advantage of the window of opportunity, allowing individuals interested in moving into the cybersecurity field to do so via education and training.

  6. Band gap modulation in polythiophene and polypyrrole-based systems

    Science.gov (United States)

    Kaloni, Thaneshwor P.; Schreckenbach, Georg; Freund, Michael S.

    2016-11-01

    In this paper, the structural and electronic properties of polythiophene and polyprrrole-based systems have been investigated using first-principles calculations both in periodic and oligomer forms. Of particular interest is the band gap modulation through substitutions and bilayer formation. Specifically, S has been substituted by Se and Te in polythiophene, leading to polyseleophene and polytellurophene, respectively, and N has been substituted by P and As in polypyrrole. The values obtained of the binding energy suggest that all the systems studied can be realized experimentally. Stacking (bilayer formation) of pure polythiophene, polypyrrole and their derivatives leads to linear suppression of the band gap or HOMO-LUMO gap as a function of the stacking. Mixed bilayers, including one formed from polythiophene on top of polypyrrole, have also been considered. Overall, a wide range of band gaps can be achieved through substitutions and stacking. Hybrid (B3LYP) calculations also suggest the same trend in the band gap as PBE calculations. Trends in the binding energy are similar for both periodic and molecular calculations. In addition, Γ-point phonon calculations were performed in order to check the stability of selected systems.

  7. Spin gap and antiferromagnetic correlations in the kondo insulator CeNiSn

    DEFF Research Database (Denmark)

    Mason, T.E.; Aeppli, G.; Ramirez, A.P.

    1992-01-01

    Neutron scattering measurements show that the crossover (at T less than or similar to 10 K) from metallic heavy-fermion to semiconducting behavior coincides with the formation of a gap in the magnetic excitation spectrum of CeNiSn. In contrast to the simple band picture of an insulator, the gap...

  8. Band gap effects of hexagonal boron nitride using oxygen plasma

    Energy Technology Data Exchange (ETDEWEB)

    Sevak Singh, Ram; Leong Chow, Wai [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Yingjie Tay, Roland [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Temasek Laboratories-NTU, 50 Nanyang Avenue, Singapore 639798 (Singapore); Hon Tsang, Siu [Temasek Laboratories-NTU, 50 Nanyang Avenue, Singapore 639798 (Singapore); Mallick, Govind [Temasek Laboratories-NTU, 50 Nanyang Avenue, Singapore 639798 (Singapore); Weapons and Materials Research Directorate, U.S. Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005 (United States); Tong Teo, Edwin Hang, E-mail: htteo@ntu.edu.sg [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

    2014-04-21

    Tuning of band gap of hexagonal boron nitride (h-BN) has been a challenging problem due to its inherent chemical stability and inertness. In this work, we report the changes in band gaps in a few layers of chemical vapor deposition processed as-grown h-BN using a simple oxygen plasma treatment. Optical absorption spectra show a trend of band gap narrowing monotonically from 6 eV of pristine h-BN to 4.31 eV when exposed to oxygen plasma for 12 s. The narrowing of band gap causes the reduction in electrical resistance by ∼100 fold. The x-ray photoelectron spectroscopy results of plasma treated hexagonal boron nitride surface show the predominant doping of oxygen for the nitrogen vacancy. Energy sub-band formations inside the band gap of h-BN, due to the incorporation of oxygen dopants, cause a red shift in absorption edge corresponding to the band gap narrowing.

  9. Virtual gap dielectric wall accelerator

    Science.gov (United States)

    Caporaso, George James; Chen, Yu-Jiuan; Nelson, Scott; Sullivan, Jim; Hawkins, Steven A

    2013-11-05

    A virtual, moving accelerating gap is formed along an insulating tube in a dielectric wall accelerator (DWA) by locally controlling the conductivity of the tube. Localized voltage concentration is thus achieved by sequential activation of a variable resistive tube or stalk down the axis of an inductive voltage adder, producing a "virtual" traveling wave along the tube. The tube conductivity can be controlled at a desired location, which can be moved at a desired rate, by light illumination, or by photoconductive switches, or by other means. As a result, an impressed voltage along the tube appears predominantly over a local region, the virtual gap. By making the length of the tube large in comparison to the virtual gap length, the effective gain of the accelerator can be made very large.

  10. Molecular doping and band-gap opening of bilayer graphene.

    Science.gov (United States)

    Samuels, Alexander J; Carey, J David

    2013-03-26

    The ability to induce an energy band gap in bilayer graphene is an important development in graphene science and opens up potential applications in electronics and photonics. Here we report the emergence of permanent electronic and optical band gaps in bilayer graphene upon adsorption of π electron containing molecules. Adsorption of n- or p-type dopant molecules on one layer results in an asymmetric charge distribution between the top and bottom layers and in the formation of an energy gap. The resultant band gap scales linearly with induced carrier density though a slight asymmetry is found between n-type dopants, where the band gap varies as 47 meV/10(13) cm(-2), and p-type dopants where it varies as 40 meV/10(13) cm(-2). Decamethylcobaltocene (DMC, n-type) and 3,6-difluoro-2,5,7,7,8,8-hexacyano-quinodimethane (F2-HCNQ, p-type) are found to be the best molecules at inducing the largest electronic band gaps up to 0.15 eV. Optical adsorption transitions in the 2.8-4 μm region of the spectrum can result between states that are not Pauli blocked. Comparison is made between the band gaps calculated from adsorbate-induced electric fields and from average displacement fields found in dual gate bilayer graphene devices. A key advantage of using molecular adsorption with π electron containing molecules is that the high binding energy can induce a permanent band gap and open up possible uses of bilayer graphene in mid-infrared photonic or electronic device applications.

  11. Folk Belief Theory, the Rigor Gap, and the Achievement Gap

    Science.gov (United States)

    Torff, Bruce

    2014-01-01

    Folk belief theory is suggested as a primary cause for the persistence of the achievement gap. In this research-supported theory, culturally specified folk beliefs about learning and teaching prompt educators to direct more rigorous curriculum to high-advantage students but not to low-advantage students, resulting in impoverished pedagogy in…

  12. Want to Close the Achievement Gap? Close the Teaching Gap

    Science.gov (United States)

    Darling-Hammond, Linda

    2015-01-01

    For years now, educators have looked to international tests as a yardstick to measure how well students from the United States are learning compared with their peers. The answer has been: not so well. The United States has been falling further behind other nations and has struggled with a large achievement gap. Federal policy under No Child Left…

  13. Folk Belief Theory, the Rigor Gap, and the Achievement Gap

    Science.gov (United States)

    Torff, Bruce

    2014-01-01

    Folk belief theory is suggested as a primary cause for the persistence of the achievement gap. In this research-supported theory, culturally specified folk beliefs about learning and teaching prompt educators to direct more rigorous curriculum to high-advantage students but not to low-advantage students, resulting in impoverished pedagogy in…

  14. Gravitational instability of planetary gaps and its effect on orbital migration

    CERN Document Server

    Lin, Min-Kai

    2014-01-01

    Gap formation by giant planets in self-gravitating disks may lead to a gravitational edge instability (GEI). We demonstrate this GEI with global 3D and 2D self-gravitating disk-planet simulations using the ZEUS, PLUTO and FARGO hydrodynamic codes. High resolution 2D simulations show that an unstable outer gap edge can lead to outwards orbital migration. Our results have important implications for theories of giant planet formation in massive disks.

  15. The Emissions Gap Report 2014

    DEFF Research Database (Denmark)

    Farrell, Timothy Clifford

    This fifth Emissions Gap report has a different focus from previous years. While it updates the 2020 emissions gap analysis, it gives particular attention to the implications of the global carbon dioxide emissions budget for staying within the 2 °C limit beyond 2020. It does so because countries...... are giving increasing attention to where they need to be in 2025, 2030 and beyond. Furthermore, this year’s update of the report benefits from the findings on the emissions budget from the latest series of Intergovernmental Panel on Climate Change (IPCC) reports...

  16. Microstrip microwave band gap structures

    Indian Academy of Sciences (India)

    V Subramanian

    2008-04-01

    Microwave band gap structures exhibit certain stop band characteristics based on the periodicity, impedance contrast and effective refractive index contrast. These structures though formed in one-, two- and three-dimensional periodicity, are huge in size. In this paper, microstrip-based microwave band gap structures are formed by removing the substrate material in a periodic manner. This paper also demonstrates that these structures can serve as a non-destructive characterization tool for materials, a duplexor and frequency selective coupler. The paper presents both experimental results and theoretical simulation based on a commercially available finite element methodology for comparison.

  17. Crossover from pseudogap to superconducting gap

    CERN Document Server

    De Cao, Tian

    2010-01-01

    The pseudogap is one of the most pervasive phenomena of high temperature superconductors [1, 2]. There exist two main theoretical scenarios for the explanation of the pseudogap. One is based upon the model of Cooper pairs formation already above the critical temperature of superconducting transition [3, 4], while another assumes that the appearance of the pseudogap state is due to the other orders [5, 6, 7]. Here we find that the particular electronic structure of cuprates confines Cooper pairs to be firstly formed around the antinodal region which is far from the Fermi surface, and these pairs are incoherent and result in the pseudogap state. With the change of doping or temperature, some pairs are transferred toward the nodal region which is on the Fermi surface, thus these pairs are coherent and lead to superconductivity. Thus the coexistence of the pseudogap and the superconducting gap is explained when these two kinds of gaps are not all on the Fermi surface. It is also shown that the symmetry of the pse...

  18. The Adaptation Gap Report - a Preliminary Assessment

    DEFF Research Database (Denmark)

    Alverson, Keith; Olhoff, Anne; Noble, Ian;

    This first Adaptation Gap report provides an equally sobering assessment of the gap between adaptation needs and reality, based on preliminary thinking on how baselines, future goals or targets, and gaps between them might be defined for climate change adaptation. The report focuses on gaps in de...... in developing countries in three important areas: finance, technology and knowledge....

  19. A PHOTONIC BAND GAP FIBRE

    DEFF Research Database (Denmark)

    1999-01-01

    An optical fibre having a periodicidal cladding structure provididing a photonic band gap structure with superior qualities. The periodical structure being one wherein high index areas are defined and wherein these are separated using a number of methods. One such method is the introduction...

  20. Burkholderia pseudomallei Data Gap Analysis

    Science.gov (United States)

    2015-11-01

    conducting this review is to identify the major biodefense relevant data gaps critical to better understanding B. pseudomallei infections and how they are...of patients (Table 2-1). Much of the data has excellent demographic and clinical resolution including age, sex, symptoms, duration of illness, risk...inhalation and enteral. Presentations include pneumonia , genitourinary, cutaneous, general bacteremia, septic arthritis and neurological

  1. Gap Analysis Bulletin No. 13

    Science.gov (United States)

    2005-12-01

    Project Laurence L. Strong of the spatial distribution of the accuracy parameters by applying U.S. Geological Survey, Northern Prairie Wildlife...Wildlife Resources year: at the University of Idaho. Her dissertation focuses on the " GIS Analyst Ree Brannon has returned to school at the population...54 North Dakota Gap Analysis Project Laurence L. Strong

  2. Income Gap Widens in Beijing

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The income gap between the highest-and lowestincome groups in Beijing, China's capital city, grew to 4:1 in 2004, up from 3:1 in 2003, according to a sampling survey of 2,000 urban households conducted by the Beijing Municipal Statistics Bureau.Among the most important factors affecting income levels were education and profession, the survey indicated.

  3. The Widening Income Achievement Gap

    Science.gov (United States)

    Reardon, Sean F.

    2013-01-01

    Has the academic achievement gap between high-income and low-income students changed over the last few decades? If so, why? And what can schools do about it? Researcher Sean F. Reardon conducted a comprehensive analysis of research to answer these questions and came up with some striking findings. In this article, he shows that income-related…

  4. Denmark and the gap year

    DEFF Research Database (Denmark)

    Katznelson, Noemi; Juul, Tilde Mette

    2013-01-01

    This paper describes three different educational offers to young people: “The Folk High School”, “The ‘After-school’” and 10th class. All can be considered optional Gap Years. The following diagram shows how the Danish education system is structured. The Folk High School is a training course of v...

  5. Paired twins and [112] morphology in GaP nanowires.

    Science.gov (United States)

    Algra, Rienk E; Verheijen, Marcel A; Feiner, Lou-Fé; Immink, George G W; Theissmann, Ralf; van Enckevort, Willem J P; Vlieg, Elias; Bakkers, Erik P A M

    2010-07-14

    Formation of random as well as periodic planar defects can occur during vapor-liquid-solid growth of nanowires with the zinc-blende crystal structure. Here we investigate the formation of pairs of twin planes in GaP nanowires. In such pairs, the first twin plane is formed at a random position, rapidly followed by the formation of a second twin plane of which the position is directly related to that of the first one. We show that the triangular [112] morphology of the nanowire is a key element in the formation of these twin pairs. We have extended our previous kinetic nucleation model and show that this describes the development of the nanowire morphology and its relation with the formation of single and paired twin planes.

  6. Tracking the Creation of Tropical Forest Canopy Gaps with UAV Computer Vision Remote Sensing

    Science.gov (United States)

    Dandois, J. P.

    2015-12-01

    The formation of canopy gaps is fundamental for shaping forest structure and is an important component of ecosystem function. Recent time-series of airborne LIDAR have shown great promise for improving understanding of the spatial distribution and size of forest gaps. However, such work typically looks at gap formation across multiple years and important intra-annual variation in gap dynamics remains unknown. Here we present findings on the intra-annual dynamics of canopy gap formation within the 50 ha forest dynamics plot of Barro Colorado Island (BCI), Panama based on unmanned aerial vehicle (UAV) remote sensing. High-resolution imagery (7 cm GSD) over the 50 ha plot was obtained regularly (≈ every 10 days) beginning October 2014 using a UAV equipped with a point and shoot camera. Imagery was processed into three-dimensional (3D) digital surface models (DSMs) using automated computer vision structure from motion / photogrammetric methods. New gaps that formed between each UAV flight were identified by subtracting DSMs between each interval and identifying areas of large deviation. A total of 48 new gaps were detected from 2014-10-02 to 2015-07-23, with sizes ranging from less than 20 m2 to greater than 350 m2. The creation of new gaps was also evaluated across wet and dry seasons with 4.5 new gaps detected per month in the dry season (Jan. - May) and 5.2 per month outside the dry season (Oct. - Jan. & May - July). The incidence of gap formation was positively correlated with ground-surveyed liana stem density (R2 = 0.77, p UAV remote sensing.

  7. Using Unmanned Aerial Vehicles (UAV to Quantify Spatial Gap Patterns in Forests

    Directory of Open Access Journals (Sweden)

    Stephan Getzin

    2014-07-01

    Full Text Available Gap distributions in forests reflect the spatial impact of man-made tree harvesting or naturally-induced patterns of tree death being caused by windthrow, inter-tree competition, disease or senescence. Gap sizes can vary from large (>100 m2 to small (<10 m2, and they may have contrasting spatial patterns, such as being aggregated or regularly distributed. However, very small gaps cannot easily be recorded with conventional aerial or satellite images, which calls for new and cost-effective methodologies of forest monitoring. Here, we used an unmanned aerial vehicle (UAV and very high-resolution images to record the gaps in 10 temperate managed and unmanaged forests in two regions of Germany. All gaps were extracted for 1-ha study plots and subsequently analyzed with spatially-explicit statistics, such as the conventional pair correlation function (PCF, the polygon-based PCF and the mark correlation function. Gap-size frequency was dominated by small gaps of an area <5 m2, which were particularly frequent in unmanaged forests. We found that gap distances showed a variety of patterns. However, the polygon-based PCF was a better descriptor of patterns than the conventional PCF, because it showed randomness or aggregation for cases when the conventional PCF showed small-scale regularity; albeit, the latter was only a mathematical artifact. The mark correlation function revealed that gap areas were in half of the cases negatively correlated and in the other half independent. Negative size correlations may likely be the result of single-tree harvesting or of repeated gap formation, which both lead to nearby small gaps. Here, we emphasize the usefulness of UAV to record forest gaps of a very small size. These small gaps may originate from repeated gap-creating disturbances, and their spatial patterns should be monitored with spatially-explicit statistics at recurring intervals in order to further insights into forest dynamics.

  8. Air Gap Effects in LX-17

    Energy Technology Data Exchange (ETDEWEB)

    Souers, P C; Ault, S; Avara, R; Bahl, K L; Boat, R; Cunningham, B; Gidding, D; Janzen, J; Kuklo, D; Lee, R; Lauderbach, L; Weingart, W C; Wu, B; Winer, K

    2005-09-26

    Three experiments done over twenty years on gaps in LX-17 are reported. For the detonation front moving parallel to the gaps, jets of gas products were seen coming from the gaps at velocities greater than the detonation velocity. A case can be made that the jet velocity increased with gap thickness but the data is scattered. For the detonation front moving transverse to the gap, time delays were seen. The delays roughly increase with gap width, going from 0-70 ns at 'zero gap' to around 300 ns at 0.5-1 mm gap. Larger gaps of up to 6 mm width almost certainly stopped the detonation, but this was not proved. Real-time resolution of the parallel jets and determination of the actual re-detonation or failure in the transverse case needs to be done in future experiments.

  9. A photoevaporative gap in the closest planet-forming disc

    Science.gov (United States)

    Ercolano, Barbara; Rosotti, Giovanni P.; Picogna, Giovanni; Testi, Leonardo

    2017-01-01

    The dispersal of the circum-stellar discs of dust and gas surrounding young low-mass stars has important implications for the formation of planetary systems. Photoevaporation from energetic radiation from the central object is thought to drive the dispersal in the majority of discs, by creating a gap which disconnects the outer from the inner regions of the disc and then disperses the outer disc from the inside-out, while the inner disc keeps draining viscously on to the star. In this Letter, we show that the disc around TW Hya, the closest protoplanetary disc to Earth, may be the first object where a photoevaporative gap has been imaged around the time at which it is being created. Indeed, the detected gap in the Atacama large millimeter/submillimeter array images is consistent with the expectations of X-ray photoevaporation models, thus not requiring the presence of a planet. The photoevaporation model is also consistent with a broad range of properties of the TW Hya system, e.g. accretion rate and the location of the gap at the onset of dispersal. We show that the central, unresolved 870 μm continuum source might be produced by free-free emission from the gas and/or residual dust inside the gap.

  10. submitter Triggering of a pressurized spark gap by a laser beam

    CERN Document Server

    Deutsch, F

    1968-01-01

    A delay line was discharged into a terminating resistor by a spark gap of coaxial design. The spark gap was triggered by a focused laser beam, introduced along the axis; a Q-switched ruby laser giving pulses of 20 ns duration and up to 50 MW power was used. The range of operation of the gap, formative time of the breakdown and jitter were investigated for different gases at pressures above atmospheric, gap widths of 4-10 mm and voltages of up to 120 kv. Mixtures of argon and nitrogen were found to have certain advantages, such as a low threshold for ionization by the laser beam, sufficient dielectric strength, low values of the formative-time jitter and chemical inertness. Formative times of down to about 1 ns and jitters below 1 ns were found. The laser power can be relatively low (0centerdot5-5 MW). An explanation for the breakdown mechanism is proposed.

  11. Satellite formation flying relative dynamics, formation design, fuel optimal maneuvers and formation maintenance

    CERN Document Server

    Wang, Danwei; Poh, Eng Kee

    2017-01-01

    This book systematically describes the concepts and principles for multi-satellite relative motion, passive and near passive formation designs, trajectory planning and control for fuel optimal formation maneuvers, and formation flying maintenance control design. As such, it provides a sound foundation for researchers and engineers in this field to develop further theories and pursue their implementations. Though satellite formation flying is widely considered to be a major advance in space technology, there are few systematic treatments of the topic in the literature. Addressing that gap, the book offers a valuable resource for academics, researchers, postgraduate students and practitioners in the field of satellite science and engineering.

  12. On the accurate estimation of gap fraction during daytime with digital cover photography

    Science.gov (United States)

    Hwang, Y. R.; Ryu, Y.; Kimm, H.; Macfarlane, C.; Lang, M.; Sonnentag, O.

    2015-12-01

    Digital cover photography (DCP) has emerged as an indirect method to obtain gap fraction accurately. Thus far, however, the intervention of subjectivity, such as determining the camera relative exposure value (REV) and threshold in the histogram, hindered computing accurate gap fraction. Here we propose a novel method that enables us to measure gap fraction accurately during daytime under various sky conditions by DCP. The novel method computes gap fraction using a single DCP unsaturated raw image which is corrected for scattering effects by canopies and a reconstructed sky image from the raw format image. To test the sensitivity of the novel method derived gap fraction to diverse REVs, solar zenith angles and canopy structures, we took photos in one hour interval between sunrise to midday under dense and sparse canopies with REV 0 to -5. The novel method showed little variation of gap fraction across different REVs in both dense and spares canopies across diverse range of solar zenith angles. The perforated panel experiment, which was used to test the accuracy of the estimated gap fraction, confirmed that the novel method resulted in the accurate and consistent gap fractions across different hole sizes, gap fractions and solar zenith angles. These findings highlight that the novel method opens new opportunities to estimate gap fraction accurately during daytime from sparse to dense canopies, which will be useful in monitoring LAI precisely and validating satellite remote sensing LAI products efficiently.

  13. Closing the BME attainment gap

    OpenAIRE

    Nortcliffe, Anne; Pink-Keech, Cathy; Evans, Jayne

    2014-01-01

    The national British Minority Ethnic (BME) attainment gap is 16% (Berry and Loke, 2011). BME students frequently report being isolated and lonely (Cotton et al, 2011), and experience derisory support (NUS, 2011). At Sheffield Hallam University (SHU) a pilot Peer Assisted Learning (PAL) programme on an engineering course to aid inclusivity, as at UCL PAL has increased student retention (Angelini, 2011). The initial results at SHU are positive: "They [Mentors] kept me on a course and ...

  14. Introspections on the Semantic Gap

    Science.gov (United States)

    2015-04-14

    essential goal of virtual machine introspection ( VMI ) is security policy enforcement in the presence of an untrustworthy OS. One obstacle to this goal is...ABSTRACT Introspections on the Semantic Gap Report Title An essential goal of virtual machine introspection ( VMI ) is security policy enforcement in the...machine introspection ( VMI ) is security policy enforcement in the presence of an untrustworthy OS. One obstacle to this goal is the difficulty in

  15. Investigations of Pulsed Vacuum Gap.

    Science.gov (United States)

    1981-02-10

    re-az4,irc t:ata -.as taken .0thcut t1he cury-ent vino r’esistor. Initial data, with no current viewing resistor, were taken for a 35 mmn gap using an...Eastman, and J. Kivlin, "The Appearance of Micro- particles in Accelerator Tubes," Proc. of 8th Symp., Paper F6-1, Albuquerque, . . Mexico , (1978). 71391

  16. Filling in biodiversity threat gaps

    DEFF Research Database (Denmark)

    Joppa, L. N.; O'Connor, Brian; Visconti, Piero

    2016-01-01

    increase to 10,000 times the background rate should species threatened with extinction succumb to pressures they face (4). Reversing these trends is a focus of the Convention on Biological Diversity's 2020 Strategic Plan for Biodiversity and its 20 Aichi Targets and is explicitly incorporated...... into the United Nations' 2030 Agenda for Sustainable Development and its 17 Sustainable Development Goals (SDGs). We identify major gaps in data available for assessing global biodiversity threats and suggest mechanisms for closing them....

  17. Rational Solution To Income Gap

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    While enjoying an economic boom, China has seen a widening income gap that has appeared like a chasm between its urban and rural citizens. What are the deep roots of this situation and what is the best way to deal with it? Ding Yuanzhu, researcher at the Macro-Economic Research Institute of the National Development and Reform Commission, shares his views on this issue in an article published in Wen Hui Bao. Excerpts follow:

  18. Prometheus and the Keeler gap

    Science.gov (United States)

    Tajeddine, Radwan; Nicholson, Phillip D.; Hedman, Matthew M.; French, Richard G.; Tiscareno, Matthew S.; Burns, Joseph A.

    2014-11-01

    Linblad resonances with Saturn’s satellites are located at many radii in the rings. While some cause density or bending waves, others hold gap edges from spreading, like the 2:1 resonance with Mimas located at the B-ring edge, the 7:6 resonance with Janus at the A-ring edge, and the 32:31 resonance with Prometheus at the inner edge of the Keeler gap. The latter is the case of study here.Theoretically, the inner edge of the Keeler gap should have 32 regular sinusoidal lobes, where either the maximum or the minimum radius is expected to be aligned with Prometheus and rotating with its mean motion. We show that such is not the case. Fit of occultation data shows the presence of the 32:31 resonance, however, the fit residuals is as high as the amplitude of the resonance amplitude (about 2 km). Analysis of the ISS data, shows irregularities overlapping the lobes (Tiscareno et al. 2005, DPS), that follow Keplerian motion. These irregularities may be due to clumps of particles with different eccentricities than the rest of the edge particles. This phenomenon may be caused by the resonance, as it has not been observed at other circular edges were no resonance is present at their location. The ISS data also shows that the lobe’s minimum/maximum is not perfectly aligned with the longitude of Prometheus, which may be due to libration about the centre of the resonance.

  19. A SEMIOLOGIC APPROACH TO AUDIT EXPECTATIONS GAP

    Directory of Open Access Journals (Sweden)

    Ciolpan Daniela

    2009-05-01

    Full Text Available Audit expectations gap (AEG is one of the most debated phenomena animating the international scientific research scene. The volume of papers focused on defining the AEG concept, examining its determinants, implications, and mechanisms to minimize the gap

  20. Parameters affecting gap detection in the rat.

    Science.gov (United States)

    Leitner, D S; Hammond, G R; Springer, C P; Ingham, K M; Mekilo, A M; Bodison, P R; Aranda, M T; Shawaryn, M A

    1993-09-01

    The present research used a startle amplitude reduction paradigm to investigate the ability of the rat's auditory system to track rapidly changing acoustic transients. Specifically examined was the ability of brief gaps in otherwise continuous noise to reduce the amplitude of a subsequently elicited acoustic startle reflex. The duration of the gap, time between gap offset and startle elicitation (the interstimulus interval or ISI), and rise-fall characteristics of the gap were systematically varied. Consistent with previous research, gaps reliably reduced startle amplitude. Gaps 2 msec long were reliably detected, and a 50-msec ISI resulted in the greatest amplitude reduction. Gaps presented at short ISIs produced amplitude reduction that followed a different time course than did gaps presented at longer ISIs. These results may reflect differences in the length of time available for the processing of the stimulus and may involve two different processes.

  1. "Explaining the Gender Wage Gap in Georgia"

    OpenAIRE

    Khitarishvili, Tamar

    2009-01-01

    This paper evaluates gender wage differentials in Georgia between 2000 and 2004. Using ordinary least squares, we find that the gender wage gap in Georgia is substantially higher than in other transition countries. Correcting for sample selection bias using the Heckman approach further increases the gender wage gap. The Blinder Oaxaca decomposition results suggest that most of the wage gap remains unexplained. The explained portion of the gap is almost entirely attributed to industrial variab...

  2. Gap Year: Time off, with a Plan

    Science.gov (United States)

    Torpey, Elka Maria

    2009-01-01

    A gap year allows people to step off the usual educational or career path and reassess their future. According to people who have taken a gap year, the time away can be well worth it. This article can help a person decide whether to take a gap year and how to make the most of his time off. It describes what a gap year is, including its pros and…

  3. Formative Feedback in a Malaysian Primary School ESL Context

    Science.gov (United States)

    Sardareh, Sedigheh Abbasnasab

    2016-01-01

    The idea of providing students with formative feedback is a crucial part of formative assessment. Teachers need to provide students with feedback that improves their learning. In other words, formative feedback should provide learners with information that help them bridge their learning gap. As formative assessment itself is a newly introduced…

  4. Closing the Achievement Gap: Four States' Efforts

    Science.gov (United States)

    Wixom, Micah Ann

    2015-01-01

    The achievement gap separating economically disadvantaged students from their more advantaged peers disproportionately affects students of color and has been the focus of discussion, research and controversy for more than 40 years. While the gap between black and white students narrowed considerably from the 1950s to the 1980s, that gap has…

  5. Hyper-active gap filling

    Directory of Open Access Journals (Sweden)

    Akira eOmaki

    2015-04-01

    Full Text Available Much work has demonstrated that speakers of verb-final languages are able to construct rich syntactic representations in advance of verb information. This may reflect general architectural properties of the language processor, or it may only reflect a language-specific adaptation to the demands of verb-finality. The present study addresses this issue by examining whether speakers of a verb-medial language (English wait to consult verb transitivity information before constructing filler-gap dependencies, where internal arguments are fronted and hence precede the verb. This configuration makes it possible to investigate whether the parser actively makes representational commitments on the gap position before verb transitivity information becomes available. A key prediction of the view that rich pre-verbal structure-building is a general architectural property is that speakers of verb-medial languages should predictively construct dependencies in advance of verb transitivity information, and therefore that disruption should be observed when the verb has intransitive subcategorization frames that are incompatible with the predicted structure. In three reading experiments (self-paced and eye-tracking that manipulated verb transitivity, we found evidence for reading disruption when the verb was intransitive, although no such reading difficulty was observed when the critical verb was embedded inside a syntactic island structure, which blocks filler-gap dependency completion. These results are consistent with the hypothesis that in English, as in verb-final languages, information from preverbal NPs is sufficient to trigger active dependency completion without having access to verb transitivity information.

  6. Long-gap esophageal atresia.

    Science.gov (United States)

    Shieh, Hester F; Jennings, Russell W

    2017-04-01

    The management of long-gap esophageal atresia remains challenging with limited consensus on the definition, evaluation, and surgical approach to treatment. Efforts to preserve the native esophagus have been successful with delayed primary anastomosis and tension-based esophageal growth induction processes. Esophageal replacement is necessary in a minority of cases, with the conduit of choice and patient outcomes largely dependent on institutional expertise. Given the complexity of this patient population with significant morbidity, treatment and long-term follow-up are best done in multidisciplinary esophageal and airway treatment centers. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Gap junctions - guards of excitability.

    Science.gov (United States)

    Stroemlund, Line Waring; Jensen, Christa Funch; Qvortrup, Klaus; Delmar, Mario; Nielsen, Morten Schak

    2015-06-01

    Cardiomyocytes are connected by mechanical and electrical junctions located at the intercalated discs (IDs). Although these structures have long been known, it is becoming increasingly clear that their components interact. This review describes the involvement of the ID in electrical disturbances of the heart and focuses on the role of the gap junctional protein connexin 43 (Cx43). Current evidence shows that Cx43 plays a crucial role in organizing microtubules at the intercalated disc and thereby regulating the trafficking of the cardiac sodium channel NaV1.5 to the membrane.

  8. The Emissions Gap Report 2015

    DEFF Research Database (Denmark)

    Following the historic signing of the 2030 Agenda for Sustainable Development, this sixth edition of the UNEP Emissions Gap Report comes as world leaders start gathering in Paris to establish a new agreement on climate change. The report offers an independent assessment of the mitigation contribu...... temperature increases on track to stay below 2°C by the end of the century; it provides data for an aspirational target of keeping that increase below 1.5°C; and it evaluates the INDCs in relation to progress on the 2020 pledges made in Cancun....

  9. Band gaps in bubble phononic crystals

    Directory of Open Access Journals (Sweden)

    V. Leroy

    2016-12-01

    Full Text Available We investigate the interaction between Bragg and hybridization effects on the band gap properties of bubble phononic crystals. These latter consist of air cavities periodically arranged in an elastomer matrix and are fabricated using soft-lithography techniques. Their transmission properties are affected by Bragg effects due to the periodicity of the structure as well as hybridization between the propagating mode of the embedding medium and bubble resonance. The hybridization gap survives disorder while the Bragg gap requires a periodic distribution of bubbles. The distance between two bubble layers can be tuned to make the two gaps overlap or to create a transmission peak in the hybridization gap.

  10. Gap Model for Dual Customer Values

    Institute of Scientific and Technical Information of China (English)

    HOU Lun; TANG Xiaowo

    2008-01-01

    The customer value, the key problem in customer relationship management (CRM), was studied to construct a gap model for dual customer values. A basic description of customer values is given, and then the gaps between products and services in different periods for the customers and companies are analyzed based on the product or service life-cycle. The main factors that influence the perceived customer value were analyzed to define the "recognized value gap" and a gap model for the dual customer values was constructed to supply companies with a tool to analyze existing customer value gaps and improve customer relationship management.

  11. Synthetic analyses of the LAVA experimental results on in-vessel corium retention through gap cooling

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Kyoung Ho; Cho, Young Ro; Koo, Kil Mo; Park, Rae Joon; Kim, Jong Hwan; Kim, Jong Tae; Ha, Kwang Sun; Kim, Sang Baik; Kim, Hee Dong

    2001-03-01

    LAVA(Lower-plenum Arrested Vessel Attack) has been performed to gather proof of gap formation between the debris and lower head vessel and to evaluate the effect of the gap formation on in-vessel cooling. Through the total of 12 tests, the analyses on the melt relocation process, gap formation and the thermal and mechanical behaviors of the vessel were performed. The thermal behaviors of the lower head vessel were affected by the formation of the fragmented particles and melt pool during the melt relocation process depending on mass and composition of melt and subcooling and depth of water. During the melt relocation process 10.0 to 20.0 % of the melt mass was fragmented and also 15.5 to 47.5 % of the thermal energy of the melt was transferred to water. The experimental results address the non-adherence of the debris to the lower head vessel and the consequent gap formation between the debris and the lower head vessel in case there was an internal pressure load across the vessel abreast with the thermal load induced by the thermite melt. The thermal behaviors of the lower head vessel during the cooldown period were mainly affected by the heat removal characteristics through this gap, which were determined by the possibilities of the water ingression into the gap depending on the melt composition of the corium simulant. The enhanced cooling capacity through the gap was distinguished in the Al{sub 2}O{sub 3} melt tests. It could be inferred from the analyses on the heat removal capacity through the gap that the lower head vessel could effectively cooldown via heat removal in the gap governed by counter current flow limits(CCFL) even if 2mm thick gap should form in the 30 kg Al{sub 2}O{sub 3} melt tests, which was also confirmed through the variations of the conduction heat flux in the vessel and rapid cool down of the vessel outer surface in the Al{sub 2}O{sub 3} melt tests. In the case of large melt mass of 70 kg Al{sub 2}O{sub 3} melt, however, the infinite

  12. Selective permeability of gap junction channels.

    Science.gov (United States)

    Goldberg, Gary S; Valiunas, Virginijus; Brink, Peter R

    2004-03-23

    Gap junctions mediate the transfer of small cytoplasmic molecules between adjacent cells. A family of gap junction proteins exist that form channels with unique properties, and differ in their ability to mediate the transfer of specific molecules. Mutations in a number of individual gap junction proteins, called connexins, cause specific human diseases. Therefore, it is important to understand how gap junctions selectively move molecules between cells. Rules that dictate the ability of a molecule to travel through gap junction channels are complex. In addition to molecular weight and size, the ability of a solute to transverse these channels depends on its net charge, shape, and interactions with specific connexins that constitute gap junctions in particular cells. This review presents some data and interpretations pertaining to mechanisms that govern the differential transfer of signals through gap junction channels.

  13. [Effects of gaps on distribution of soil aggregates and organic carbon in Pinus massoniana plantation].

    Science.gov (United States)

    Song, Xiao-Yan; Zhang, Dan-Ju; Zhang, Jian; Li, Jian-Ping; Deng, Chang-Chun; Deng, Chao

    2014-11-01

    The effects of forest gap size on the distribution of soil aggregates, organic carbon and labile organic carbon were investigated in a 39-year-old Pinus massoniana plantation in Yibin, Sichuan Province. The results showed that the composition of soil aggregates was dominated by particles > 2 mm, which accounted for 51.7%-78.7% of the whole soil samples under different sized forest gaps and beneath P. massoniana plantation. Soil organic carbon content and labile organic carbon content in > 5 mm aggregates were significantly positively correlated with the soil organic carbon and labile organic carbon contents. Furthermore, the amounts of organic carbon and labile organic carbon storage > 5 mm particles were higher than those in other size particles. Therefore, particles > 5 mm of aggregates dominated the soil carbon pool. Compared with those P. massoniana plantations, the contents of organic carbon in aggregates and total topsoil decreased during the formation of forest gaps, whereas the soil organic carbon storage under 1225 m2 gap was higher. In addition, the soil labile organic carbon content under 225 and 400 m2 gaps and the labile organic carbon storage under 225, 400, 900 and 1225 m2 gaps were higher than those the plantations, but were lower than under the other gaps. It was suggested that an appropriate size of forest gap would increase the accumulation of soil organic carbon and labile organic carbon content. The size of forest gap had significant effects on the distribution of soil aggregates, organic carbon and labile organic carbon. The soil sample under 1225 m2 gap had the highest organic carbon content and storage and a better aggregate proportion, and the higher labile organic carbon storage. Therefore, it was suggested that 1225 m2 gap might be an optimal logging gap size.

  14. Diluted II-VI oxide semiconductors with multiple band gaps.

    Science.gov (United States)

    Yu, K M; Walukiewicz, W; Wu, J; Shan, W; Beeman, J W; Scarpulla, M A; Dubon, O D; Becla, P

    2003-12-12

    We report the realization of a new mult-band-gap semiconductor. Zn(1-y)Mn(y)OxTe1-x alloys have been synthesized using the combination of oxygen ion implantation and pulsed laser melting. Incorporation of small quantities of isovalent oxygen leads to the formation of a narrow, oxygen-derived band of extended states located within the band gap of the Zn(1-y)Mn(y)Te host. When only 1.3% of Te atoms are replaced with oxygen in a Zn0.88Mn0.12Te crystal the resulting band structure consists of two direct band gaps with interband transitions at approximately 1.77 and 2.7 eV. This remarkable modification of the band structure is well described by the band anticrossing model. With multiple band gaps that fall within the solar energy spectrum, Zn(1-y)Mn(y)OxTe1-x is a material perfectly satisfying the conditions for single-junction photovoltaics with the potential for power conversion efficiencies surpassing 50%.

  15. Instabilities at planetary gap edges in 3D self-gravitating disks

    Directory of Open Access Journals (Sweden)

    Lin Min-Kai

    2013-04-01

    Full Text Available Numerical simulations are presented to study the stability of gaps opened by giant planets in 3D self-gravitating disks. In weakly self-gravitating disks, a few vortices develop at the gap edge and merge on orbital time-scales. The result is one large but weak vortex with Rossby number -0.01. In moderately self-gravitating disks, more vortices develop and their merging is resisted on dynamical time-scales. Self-gravity can sustain multi-vortex configurations, with Rossby number -0.2 to -0.1, over a time-scale of order 100 orbits. Self-gravity also enhances the vortex vertical density stratification, even in disks with initial Toomre parameter of order 10. However, vortex formation is suppressed in strongly self-gravitating disks and replaced by a global spiral instability associated with the gap edge which develops during gap formation.

  16. Instabilities at planetary gap edges in 3D self-gravitating disks

    CERN Document Server

    Lin, Min-Kai

    2013-01-01

    Numerical simulations are presented to study the stability of gaps opened by giant planets in 3D self-gravitating disks. In weakly self-gravitating disks, a few vortices develop at the gap edge and merge on orbital time-scales. The result is one large but weak vortex with Rossby number -0.01. In moderately self-gravitating disks, more vortices develop and their merging is resisted on dynamical time-scales. Self-gravity can sustain multi-vortex configurations, with Rossby number -0.2 to -0.1, over a time-scale of order 100 orbits. Self-gravity also enhances the vortex vertical density stratification, even in disks with initial Toomre parameter of order 10. However, vortex formation is suppressed in strongly self-gravitating disks and replaced by a global spiral instability associated with the gap edge which develops during gap formation.

  17. An alternative model for the origin of gaps in circumstellar disks

    CERN Document Server

    Vorobyov, Eduard I; Guedel, Manuel; Lin, D N C

    2016-01-01

    Motivated by recent observational and numerical studies suggesting that collapsing protostellar cores may be replenished from the local environment, we explore the evolution of protostellar cores submerged in the external counter-rotating environment. These models predict the formation of counter-rotating disks with a deep gap in the gas surface density separating the inner disk (corotating with the star) and the outer counter-rotating disk. The properties of these gaps are compared to those of planet-bearing gaps that form in disks hosting giant planets. We employ numerical hydrodynamics simulations of collapsing cores that are replenished from the local counter-rotating environment, as well as numerical hydrodynamic simulations of isolated disks hosting giant planets, to derive the properties of the gaps that form in both cases. Our numerical simulations demonstrate that counter-rotating disks can form for a wide range of mass and angular momentum available in the local environment. The gap that separates b...

  18. Forensics of Subhalo-Stream Encounters: The Three Phases of Gap Growth

    CERN Document Server

    Erkal, Denis

    2014-01-01

    There is hope to discover dark matter subhalos free of stars (predicted by the current theory of structure formation) by observing gaps they produce in tidal streams. In fact, this is the most promising technique for dark substructure detection and characterization as such gaps grow with time and hence become more observable by ongoing and planned Galaxy surveys. To facilitate such future inference, we develop a comprehensive framework for studies of the growth of the stream density perturbations. Starting with simple assumptions, we derive analytic formulae that describe the evolution of all gap properties (size, density contrast etc) at all times. We uncover complex, previously unnoticed behavior, with the stream initially forming a density enhancement near the subhalo impact point. Shortly after, a gap forms due to the relative change in period induced by the subhalo's passage. There is an intermediate regime where the gap grows linearly in time. At late times, the particles in the stream overtake each oth...

  19. The role of gap junctions in the brain in health and disease.

    Science.gov (United States)

    Dere, Ekrem; Zlomuzica, Armin

    2012-01-01

    Gap junctions connect the cytosolic compartments of adjacent cells for direct electrotonic and metabolic cell-to-cell communication. Gap junctions between glial cells or neurons are ubiquitously expressed in the brain and play a role in brain development including cell differentiation, cell migration and survival, tissue homeostasis, as well as in human diseases including hearing loss, skin disease, neuropathies, epilepsy, brain trauma, and cardiovascular disease. Furthermore, gap junctions are involved in the synchronization and rhythmic oscillation of hippocampal and neocotical neuronal ensembles which might be important for memory formation and consolidation. In this review the accumulated evidence from mouse mutant and pharmacological studies using gap junction blockers is summarized and the progress made in dissecting the physiological, pathophysiological and behavioral roles of gap junction mediated intercellular communication in the brain is discussed. Copyright © 2011 Elsevier Ltd. All rights reserved.

  20. Geology of the Gypsum Gap quadrangle, Colorado

    Science.gov (United States)

    Cater, Fred W.

    1953-01-01

    The Gypsum Gap quadrangle is one eighteen 7 1/2-minute quadrangles covering the principal carnotite-producing area of southwestern Colorado. The geology of these quadrangles was mapped by the U.S. Geological Survey for the Atomic Energy Commission as part of a comparative study of carnotite deposits. The rocks exposed in the eighteen quadrangles consist of crystalline rocks of pre-Cambrian age and sedimentary rocks that range in age from late Paleozoic to Quaternary. Over much of the area the sedimentary rocks are flat lying, but in places the rocks are disrupted by high-angle faults, and northwest-trending folds. Conspicuous among the folds are large anticlines having cores of intrusive salt and gypsum. Most of the carnotite deposits are confined to the Salt Wash sandstone member of the Jurassic Morrison formation. Within this sandstone, most of the deposits are spottily distributed through a arcuate zone known as the "Uravan Mineral Belt". Individual deposits range in size from irregular masses containing only a few tons of ore to large, tabular masses containing many thousands of tons. The core consists largely of sandstone selectively impregnated and in part replaced by uranium and vanadium minerals. Most of the deposits appear to be related to certain sedimentary structures in sandstones of favorable composition.

  1. Vol en formation sans formation: contrôle et planification pour le vol en formation des avions sans pilote

    OpenAIRE

    2008-01-01

    This thesis presents the study and the implementation of a system that manages autonomously the configuration of a formation of unmanned aerial vehicles, or UAVs. The purposes are to improve the safety and the efficiency of a group of military UAVs, and to fill the gap between mission planning layers and formation control layers. Formation flight is particularly suited for military applications in hostile environments, that require synchronizations on target arrivals or mutual support for jam...

  2. Updated Starshade Technology Gap List

    Science.gov (United States)

    Crill, Brendan P.; Siegler, Nicholas

    2017-01-01

    NASA's Exoplanet Exploration Program (ExEP) guides the development of technology that enables the direct imaging and characterization of exo-Earths in the habitable zone of their stars, for future space observatories. Here we present the Starshade portion of the 2017 ExEP Enabling Technology Gap List, an annual update to ExEP's list of of technology to be advanced in the next 1-5 years. A Starshade is an external occulter on an independent spacecraft, allowing a space telescope to achieve exo-Earth imaging contrast requirements by blocking starlight before it enters the telescope. Building and operating a Starshade requires new technology: the occulter is a structure tens of meters in diameter that must be positioned precisely at a distance of tens of thousands of kilometers from the telescope. We review the current state-of-the-art performance and the performance level that must be achieved for a Starshade.

  3. Holographic Quenches with a Gap

    CERN Document Server

    da Silva, Emilia; Mas, Javier; Serantes, Alexandre

    2016-01-01

    In order to holographically model quenches with a gapped final hamiltonian, we consider a gravity-scalar theory in anti-de Sitter space with an infrared hard wall. We allow a time dependent profile for the scalar field at the wall. This induces an energy exchange between bulk and wall and generates an oscillating scalar pulse. We argue that such backgrounds are the counterpart of quantum revivals in the dual field theory. We perform a qualitative comparison with the quench dynamics of the massive Schwinger model, which has been recently analyzed using tensor network techniques. Agreement is found provided the width of the oscillating scalar pulse is inversely linked to the energy density communicated by the quench. We propose this to be a general feature of holographic quenches.

  4. The "Efficacy-Effectiveness Gap"

    DEFF Research Database (Denmark)

    Nordon, Clementine; Karcher, Helene; Groenwold, Rolf H H

    2016-01-01

    BACKGROUND: The concept of the "efficacy-effectiveness gap" (EEG) has started to challenge confidence in decisions made for drugs when based on randomized controlled trials alone. Launched by the Innovative Medicines Initiative, the GetReal project aims to improve understanding of how to reconcile...... paradigms, in which EEG is related to 1) real-life characteristics of the health care system; 2) the method used to measure the drug's effect; and 3) a complex interaction between the drug's biological effect and contextual factors. CONCLUSIONS: The third paradigm provides an opportunity to look beyond any...... dichotomy between "standardized" versus "real-life" characteristics of the health care system and study designs. Namely, future research will determine whether the identification of these contextual factors can help to best design randomized controlled trials that provide better estimates of drugs...

  5. Denmark and the gap year

    DEFF Research Database (Denmark)

    Katznelson, Noemi; Juul, Tilde Mette

    2013-01-01

    This paper describes three different educational offers to young people: “The Folk High School”, “The ‘After-school’” and 10th class. All can be considered optional Gap Years. The following diagram shows how the Danish education system is structured. The Folk High School is a training course...... of varying duration (approximately between 12 weeks and 1 year) where one lives at the school. It is primarily located after 12 school year. The ‘After-school’ is a special school structure, were the students also live at the school during their 8th, 9th, or 10th years of primary school. 10th Class...... is a voluntary school year extension of primary school. All three types of schools will be described in more detail in this paper....

  6. Holographic quenches with a gap

    Science.gov (United States)

    da Silva, Emilia; Lopez, Esperanza; Mas, Javier; Serantes, Alexandre

    2016-06-01

    In order to holographically model quenches with a gapped final hamiltonian, we consider a gravity-scalar theory in anti-de Sitter space with an infrared hard wall. We allow a time dependent profile for the scalar field at the wall. This induces an energy exchange between bulk and wall and generates an oscillating scalar pulse. We argue that such backgrounds are the counterpart of quantum revivals in the dual field theory. We perform a qualitative comparison with the quench dynamics of the massive Schwinger model, which has been recently analyzed using tensor network techniques. Agreement is found provided the width of the oscillating scalar pulse is inversely linked to the energy density communicated by the quench. We propose this to be a general feature of holographic quenches.

  7. Efros-Shklovskii Coulomb gap in the absence of disorder

    Science.gov (United States)

    Rademaker, Louk; Mahmoudian, Samiyeh; Ralko, Arnaud; Fratini, Simone; Dobrosavljevic, Vladimir

    2015-03-01

    Certain models of frustrated electron systems have been shown to self-generate glassy behavior, in the absence of disorder. Possible candidate materials contain quarter-filled triangular lattices with long-range Coulomb interactions, as found in the θ-family of organic BEDT-TTF crystals. In disordered insulators with localized electronic states, the so-called Coulomb glass, the single particle excitation spectrum displays the well-known Efros-Shklovskii gap. The same excitation spectrum is investigated in a class of models that display self-generated electronic glassiness, showing pseudogap formation related to the Efros-Shklovskii Coulomb gap. Our study suggests universal characteristics of all electron glasses, regardless of disorder.

  8. Gap engineering using Hellmann-Feynmann forces: method and applications

    Science.gov (United States)

    Prasai, Kiran; Biawas, Parthapratim; Drabold, D. A.

    Materials with optimized band gap are needed in many specialized applications. In this talk, we demonstrate that Hellmann-Feynman forces associated with the gap states can be used to find atomic coordinates that yield desired electronic density of states. Using tight-binding models, we show that this approach may be used to arrive at electronically designed models of amorphous silicon and carbon. We provide a simple recipe to include a priori electronic information in the formation of computer models of materials, and prove that this information may have profound structural consequences. We'll briefly discuss implementation of the method in ab-initio molecular dynamics simulations and highlight the latest feats of the method ranging from modeling amorphous semi-conducting materials to understanding the structure and properties of memory materials. K. Prasai, P. Biswas, and D. A. Drabold, Scientific reports, 5 (2015).

  9. Galaxy formation

    CERN Document Server

    Silk, Joseph; Dvorkin, Irina

    2015-01-01

    Galaxy formation is at the forefront of observation and theory in cosmology. An improved understanding is essential for improving our knowledge both of the cosmological parameters, of the contents of the universe, and of our origins. In these lectures intended for graduate students, galaxy formation theory is reviewed and confronted with recent observational issues. In Lecture 1, the following topics are presented: star formation considerations, including IMF, star formation efficiency and star formation rate, the origin of the galaxy luminosity function, and feedback in dwarf galaxies. In Lecture 2, we describe formation of disks and massive spheroids, including the growth of supermassive black holes, negative feedback in spheroids, the AGN-star formation connection, star formation rates at high redshift and the baryon fraction in galaxies.

  10. [Gap edge effect of Castanopsis kawakamii community].

    Science.gov (United States)

    Liu, Jinfu; Hong, Wei; Li, Junqing; Lin, Rongfu

    2003-09-01

    This paper reported the characters of gap edge effect of Castanopsis kawakamii community in Sanming, Fujian Province. The species diversity, ecological dominance, and edge effect strength of 38 forest gaps with different development stages in different stands of Castanopsis kawakamii community were measured, and Shannon-Wiener index, Simpson index, and index of edge effect strength were calculated. The results showed that the index of the gap edge effect of Castanopsis kawakamii community was about 0.7-1.3 (according to the species diversity index) and 0.3-1.8 (according to the ecological dominance index). The gap edge effect had the trend of increasing the species diversity of forest communities. The index of gap effect was affected by the size and development stage of the gap and the related forest type. The study provided a theoretical basis for the maintenance of species diversity and the forest management in Castanopsis kawakamii community.

  11. National GAP Conference 2007-Discussion Groups Report

    Science.gov (United States)

    Ratz, Joan M.; Lamb, Berton Lee

    2010-01-01

    We led two discussion groups during the 2007 National GAP Conference. These discussion groups provided information to help develop a survey of National Gap Analysis Program (GAP) data users. One group discussed technical issues, and the second group discussed the use of GAP data for decisionmaking. Themes emerging from the technical issues group included concerns about data quality, need for information on how to use data, and passive data distribution. The decisionmaking discussion included a wide range of topics including the need to understand presentation of information, the need to connect with and understand users of data, the revision of GAP's mission, and the adaptability of products and data. The decisionmaking group also raised concerns regarding technical issues. One conclusion is that a deep commitment to ongoing information transfer and support is a key component of success for the GAP program.

  12. Soil formation.

    NARCIS (Netherlands)

    Breemen, van N.; Buurman, P.

    1998-01-01

    Soil Formation deals with qualitative and quantitative aspects of soil formation (or pedogenesis) and the underlying chemical, biological, and physical processes. The starting point of the text is the process - and not soil classification. Effects of weathering and new formation of minerals, mobilis

  13. Tree-fall gaps and carbon cycling in the Brazilian Amazon: results from two large forest plots

    Science.gov (United States)

    Espirito-Santo, F.; Keller, M.; Linder, E.; De Oliveira, R., Jr.; Pereira, C.; Oliveira, C. G.

    2013-12-01

    The dynamics of gaps play a role in the regimes of tree mortality and production of coarse woody debris (CWD) in forests. Few studies have attempted to map the distribution of gaps in tropical forest and the production of CWD, a large pool of ecosystem carbon. Here we linked gap formation with carbon cycling through analysis of the CWD inside of gaps. We surveyed two large forest inventory plots of 114 and 53 ha of the Tapajós National Forest (TNF) in the Brazilian Amazon during 2008 and 2009, respectively. We mapped all gaps and collected data on light availability, CWD stocks and tree mortality in the field. Gap location, canopy opening (CO) and leaf area index (LAI) estimated in the field were compared with two IKONOS-2 high-resolution satellite images acquired approximately at the time of the field measurements. We provide the first statistics of CWD production based on gap size in the tropical forest literature. In the two large plots (167 ha total area) we found 96 gaps. The gaps represented 1.42% of the total area and gaps TNF, the production of CWD in recent gaps was 0.76 Mg C ha-1 year-1 and the mean tree mortality was 2.38 stems ha-1 year 1. The area of gaps estimated by using thresholds of light intensity measured by remote sensing optical instruments was twice as large as the gap areas measured on the ground. We found no significant correlation between spectral remote sensing images and CO and LAI, likely because the high faction of shadow in high-resolution satellite images. We conclude that less than 30% of the annual tree mortality and CWD flux was associated with gaps and the detection of gaps with high resolution optical remote sensing remains a challenge because of the high proportion of shadow in the those images. These results highlight the need for permanent plots for long-term carbon studies.

  14. The Immigrant Wage Gap in Germany

    OpenAIRE

    Stephan L. Thomsen; Gernandt, Johannes; Aldashev, Alisher

    2008-01-01

    Immigrants consist of foreigners and citizens with migration background. We analyze the wage gap between natives and these two groups in Germany. The estimates show a substantial gap for both groups with respect to natives. Discarding immigrants who completed education abroad reduces much of the immigrants' wage gap. This implies educational attainment in Germany is an important component of economic integration and degrees obtained abroad are valued less.

  15. PBX 9502 air-gap tests

    Energy Technology Data Exchange (ETDEWEB)

    Dickson, Peter [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Novak, Alan M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Foley, Timothy J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Campbell, Christopher Charles [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-06-29

    A small number of simple air-gap tests were performed on 1-inch diameter PBX 9502 cylinders to determine an approximate threshold for detonation failure. The primary diagnostics were streak imaging and dent measurements in a steel witness plate. Relight was found to occur, with negligible excess transit time, for air gaps up to 1 mm. Relight did not occur with a 3-mm air gap.

  16. Chiral gap effect in curved space

    CERN Document Server

    Flachi, Antonino

    2014-01-01

    We discuss a new type of QCD phenomenon induced in curved space. In the QCD vacuum a mass gap of Dirac fermions is attributed to the spontaneous breaking of chiral symmetry. If the curvature is positive large, the chiral condensate melts but a chiral invariant mass gap can still remain, which we name the chiral gap effect in curved space. This leads to decoupling of quark deconfinement which implies a view of black holes surrounded by a first-order QCD phase transition.

  17. [Remodeling of cardiac gap junctions and arrhythmias].

    Science.gov (United States)

    Yu, Zhi-Bin; Sheng, Juan-Juan

    2011-12-25

    In the heart, gap junctions mediate electrical and chemical coupling between adjacent cardiomyocytes, forming the cell-to-cell pathways for orderly spread of the wave of electrical excitation responsible for a functional syncytium. Three principal connexins are expressed in cardiomyocytes, connexin 43 (CX43), CX40, and CX45. CX43 predominates in ventricular muscle cells. Most of the gap junctions, assembled from CX43, are located at the intercalated discs, often with larger junctional plaques at the disc periphery. The gap junctions are rarely distributed to the sides of the cardiomyocyte. The ischemia-reperfusion, cardiac hypertrophy, heart failure, hypercholesterolemia, and diabetes mellitus induce gap junction remodeling. The gap junction remodeling induced by above-mentioned diseases shows similar characteristics, including down-regulation of CX43, reduction in gap junction plaque size, increased heterogeneity and lateralization of gap junction distribution, and dephosphorylation of CX43. The elevated angiotensin II concentration in local myocardium may play an important role in the gap junction remodeling. The down-regulation of CX43 and lateralization of gap junction distribution alter anisotropic spread of the impulse of ventricular myocardium. The dephosphorylation of CX43 not only reduces electrical conductance, but also decreases permeability of chemicals between cardiomyocytes. The lateralization of gap junctions may increase the number of hemichannels formed by CX43. The opening of hemichannels induces ATP efflux and Na(+) influx, which forms a delayed after-depolarization. The gap junction remodeling in pathological condition produces arrhythmia substrate in the ventricles. In this review, the current knowledge on the relationship between the remodeling of cardiac gap junctions and arrhythmias were summarized.

  18. Wavelet description of the Glottal Gap

    OpenAIRE

    Gómez Vilda, Pedro; Nieto Lluis, Victor; Rodellar Biarge, M. Victoria; Martínez Olalla, Rafael; Muñoz Mulas, Cristina Elena; Álvarez Marquina, Agustin; Mazaira Fernández, Luis Miguel; Scola Yurrita, Bartolomé; Ramírez Calvo, Carlos; Poletti Serafini,Daniel

    2013-01-01

    The Glottal Source correlates reconstructed from the phonated parts of voice may render interesting information with applicability in different fields. One of them is defective closure (gap) detection. Through the paper the background to explain the physical foundations of defective gap are reviewed. A possible method to estimate defective gap is also presented based on a Wavelet Description of the Glottal Source. The method is validated using results from the analysis of a gender-balanced sp...

  19. Gap between active and passive solar heating

    Energy Technology Data Exchange (ETDEWEB)

    Balcomb, J.D.

    1985-01-01

    The gap between active and passive solar could hardly be wider. The reasons for this are discussed and advantages to narrowing the gap are analyzed. Ten years of experience in both active and passive systems are reviewed, including costs, frequent problems, performance prediction, performance modeling, monitoring, and cooling concerns. Trends are analyzed, both for solar space heating and for service water heating. A tendency for the active and passive technologies to be converging is observed. Several recommendations for narrowing the gap are presented.

  20. Forensics of subhalo-stream encounters: the three phases of gap growth

    Science.gov (United States)

    Erkal, Denis; Belokurov, Vasily

    2015-06-01

    There is hope to discover dark matter subhaloes free of stars (predicted by the current theory of structure formation) by observing gaps they produce in tidal streams. In fact, this is the most promising technique for dark substructure detection and characterization as such gaps grow with time, magnifying small perturbations into clear signatures observable by ongoing and planned Galaxy surveys. To facilitate such future inference, we develop a comprehensive framework for studies of the growth of the stream density perturbations. Starting with simple assumptions and restricting to streams on circular orbits, we derive analytic formulae that describe the evolution of all gap properties (size, density contrast, etc.) at all times. We uncover complex, previously unnoticed behaviour, with the stream initially forming a density enhancement near the subhalo impact point. Shortly after, a gap forms due to the relative change in period induced by the subhalo's passage. There is an intermediate regime where the gap grows linearly in time. At late times, the particles in the stream overtake each other, forming caustics, and the gap grows like √{t}. In addition to the secular growth, we find that the gap oscillates as it grows due to epicyclic motion. We compare this analytic model to N-body simulations and find an impressive level of agreement. Importantly, when analysing the observation of a single gap we find a large degeneracy between the subhalo mass, the impact geometry and kinematics, the host potential, and the time since flyby.

  1. Using gaps in N-body tidal streams to probe missing satellites

    Energy Technology Data Exchange (ETDEWEB)

    Ngan, W. H. W.; Carlberg, R. G., E-mail: ngan@astro.utoronto.ca [Department of Astronomy and Astrophysics, University of Toronto, Toronto, ON M5S3H4 (Canada)

    2014-06-20

    We use N-body simulations to model the tidal disruption of a star cluster in a Milky-Way-sized dark matter halo, which results in a narrow stream comparable to (but slightly wider than) Pal-5 or GD-1. The mean Galactic dark matter halo is modeled by a spherical Navarro-Frenk-White potential with subhalos predicted by the ΛCDM cosmological model. The distribution and mass function of the subhalos follow the results from the Aquarius simulation. We use a matched filter approach to look for 'gaps' in tidal streams at 12 length scales from 0.1 kpc to 5 kpc, which appear as characteristic dips in the linear densities along the streams. We find that, in addition to the subhalos' perturbations, the epicyclic overdensities (EOs) due to the coherent epicyclic motions of particles in a stream also produce gap-like signals near the progenitor. We measure the gap spectra—the gap formation rates as functions of gap length—due to both subhalo perturbations and EOs, which have not been accounted for together by previous studies. Finally, we project the simulated streams onto the sky to investigate issues when interpreting gap spectra in observations. In particular, we find that gap spectra from low signal-to-noise observations can be biased by the orbital phase of the stream. This indicates that the study of stream gaps will benefit greatly from high-quality data from future missions.

  2. Structural Dynamics of Tropical Moist Forest Gaps

    Science.gov (United States)

    Hunter, Maria O.; Keller, Michael; Morton, Douglas; Cook, Bruce; Lefsky, Michael; Ducey, Mark; Saleska, Scott; de Oliveira, Raimundo Cosme; Schietti, Juliana

    2015-01-01

    Gap phase dynamics are the dominant mode of forest turnover in tropical forests. However, gap processes are infrequently studied at the landscape scale. Airborne lidar data offer detailed information on three-dimensional forest structure, providing a means to characterize fine-scale (1 m) processes in tropical forests over large areas. Lidar-based estimates of forest structure (top down) differ from traditional field measurements (bottom up), and necessitate clear-cut definitions unencumbered by the wisdom of a field observer. We offer a new definition of a forest gap that is driven by forest dynamics and consistent with precise ranging measurements from airborne lidar data and tall, multi-layered tropical forest structure. We used 1000 ha of multi-temporal lidar data (2008, 2012) at two sites, the Tapajos National Forest and Ducke Reserve, to study gap dynamics in the Brazilian Amazon. Here, we identified dynamic gaps as contiguous areas of significant growth, that correspond to areas > 10 m2, with height <10 m. Applying the dynamic definition at both sites, we found over twice as much area in gap at Tapajos National Forest (4.8 %) as compared to Ducke Reserve (2.0 %). On average, gaps were smaller at Ducke Reserve and closed slightly more rapidly, with estimated height gains of 1.2 m y-1 versus 1.1 m y-1 at Tapajos. At the Tapajos site, height growth in gap centers was greater than the average height gain in gaps (1.3 m y-1 versus 1.1 m y-1). Rates of height growth between lidar acquisitions reflect the interplay between gap edge mortality, horizontal ingrowth and gap size at the two sites. We estimated that approximately 10 % of gap area closed via horizontal ingrowth at Ducke Reserve as opposed to 6 % at Tapajos National Forest. Height loss (interpreted as repeat damage and/or mortality) and horizontal ingrowth accounted for similar proportions of gap area at Ducke Reserve (13 % and 10 %, respectively). At Tapajos, height loss had a much stronger signal (23

  3. Structural Dynamics of Tropical Moist Forest Gaps.

    Directory of Open Access Journals (Sweden)

    Maria O Hunter

    Full Text Available Gap phase dynamics are the dominant mode of forest turnover in tropical forests. However, gap processes are infrequently studied at the landscape scale. Airborne lidar data offer detailed information on three-dimensional forest structure, providing a means to characterize fine-scale (1 m processes in tropical forests over large areas. Lidar-based estimates of forest structure (top down differ from traditional field measurements (bottom up, and necessitate clear-cut definitions unencumbered by the wisdom of a field observer. We offer a new definition of a forest gap that is driven by forest dynamics and consistent with precise ranging measurements from airborne lidar data and tall, multi-layered tropical forest structure. We used 1000 ha of multi-temporal lidar data (2008, 2012 at two sites, the Tapajos National Forest and Ducke Reserve, to study gap dynamics in the Brazilian Amazon. Here, we identified dynamic gaps as contiguous areas of significant growth, that correspond to areas > 10 m2, with height <10 m. Applying the dynamic definition at both sites, we found over twice as much area in gap at Tapajos National Forest (4.8% as compared to Ducke Reserve (2.0%. On average, gaps were smaller at Ducke Reserve and closed slightly more rapidly, with estimated height gains of 1.2 m y-1 versus 1.1 m y-1 at Tapajos. At the Tapajos site, height growth in gap centers was greater than the average height gain in gaps (1.3 m y-1 versus 1.1 m y-1. Rates of height growth between lidar acquisitions reflect the interplay between gap edge mortality, horizontal ingrowth and gap size at the two sites. We estimated that approximately 10% of gap area closed via horizontal ingrowth at Ducke Reserve as opposed to 6% at Tapajos National Forest. Height loss (interpreted as repeat damage and/or mortality and horizontal ingrowth accounted for similar proportions of gap area at Ducke Reserve (13% and 10%, respectively. At Tapajos, height loss had a much stronger signal

  4. Forests and Forest Cover - Green Infrastructure Gaps

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — These data provide restoration value rankings and ecological attributes associated with green infrastructure gaps. The Green Infrastructure Assessment was developed...

  5. Structural Dynamics of Tropical Moist Forest Gaps.

    Science.gov (United States)

    Hunter, Maria O; Keller, Michael; Morton, Douglas; Cook, Bruce; Lefsky, Michael; Ducey, Mark; Saleska, Scott; de Oliveira, Raimundo Cosme; Schietti, Juliana

    2015-01-01

    Gap phase dynamics are the dominant mode of forest turnover in tropical forests. However, gap processes are infrequently studied at the landscape scale. Airborne lidar data offer detailed information on three-dimensional forest structure, providing a means to characterize fine-scale (1 m) processes in tropical forests over large areas. Lidar-based estimates of forest structure (top down) differ from traditional field measurements (bottom up), and necessitate clear-cut definitions unencumbered by the wisdom of a field observer. We offer a new definition of a forest gap that is driven by forest dynamics and consistent with precise ranging measurements from airborne lidar data and tall, multi-layered tropical forest structure. We used 1000 ha of multi-temporal lidar data (2008, 2012) at two sites, the Tapajos National Forest and Ducke Reserve, to study gap dynamics in the Brazilian Amazon. Here, we identified dynamic gaps as contiguous areas of significant growth, that correspond to areas > 10 m2, with height <10 m. Applying the dynamic definition at both sites, we found over twice as much area in gap at Tapajos National Forest (4.8%) as compared to Ducke Reserve (2.0%). On average, gaps were smaller at Ducke Reserve and closed slightly more rapidly, with estimated height gains of 1.2 m y-1 versus 1.1 m y-1 at Tapajos. At the Tapajos site, height growth in gap centers was greater than the average height gain in gaps (1.3 m y-1 versus 1.1 m y-1). Rates of height growth between lidar acquisitions reflect the interplay between gap edge mortality, horizontal ingrowth and gap size at the two sites. We estimated that approximately 10% of gap area closed via horizontal ingrowth at Ducke Reserve as opposed to 6% at Tapajos National Forest. Height loss (interpreted as repeat damage and/or mortality) and horizontal ingrowth accounted for similar proportions of gap area at Ducke Reserve (13% and 10%, respectively). At Tapajos, height loss had a much stronger signal (23% versus 6

  6. Undecidability of the Spectral Gap (short version)

    CERN Document Server

    Cubitt, Toby; Wolf, Michael M

    2015-01-01

    The spectral gap -- the difference in energy between the ground state and the first excited state -- is one of the most important properties of a quantum many-body system. Quantum phase transitions occur when the spectral gap vanishes and the system becomes critical. Much of physics is concerned with understanding the phase diagrams of quantum systems, and some of the most challenging and long-standing open problems in theoretical physics concern the spectral gap, such as the Haldane conjecture that the Heisenberg chain is gapped for integer spin, proving existence of a gapped topological spin liquid phase, or the Yang-Mills gap conjecture (one of the Millennium Prize problems). These problems are all particular cases of the general spectral gap problem: Given a quantum many-body Hamiltonian, is the system it describes gapped or gapless? Here we show that this problem is undecidable, in the same sense as the Halting Problem was proven to be undecidable by Turing. A consequence of this is that the spectral gap...

  7. Formation number for vortex dipoles

    Science.gov (United States)

    Sadri, Vahid; Krueger, Paul S.

    2016-11-01

    This investigation considers the axisymmetric formation of two opposite sign concentric vortex rings from jet ejection between concentric cylinders. This arrangement is similar to planar flow in that the vortex rings will travel together when the gap between the cylinders is small, similar to a vortex dipole, but it has the advantage that the vortex motion is less constrained than the planar case (vortex stretching and vortex line curvature is allowed). The flow was simulated numerically at a jet Reynolds number of 1,000 (based on ΔR and the jet velocity), jet pulse length-to-gap ratio (L / ΔR) in the range 10-20, and gap-to-outer radius ratio (ΔR /Ro) in the range 0.01-0.1. Small gap ratios were chosen for comparison with 2D results. In contrast with 2D results, the closely paired vortices in this study exhibited pinch-off from the generating flow and finite formation numbers. The more complex flow evolution afforded by the axisymmetric model and its influence on the pinch-off process will be discussed. This material is based on work supported by the National Science Foundation under Grant No. 1133876 and SMU. This supports are gratefully acknowledged.

  8. Improving the efficiency of GaP LED's which emit green light

    Science.gov (United States)

    Ladany, I.; Kressel, H.

    1972-01-01

    A study of techniques for preparing n-type material and junctions which yield the most consistent high diode efficiency values high lighted the role that Ga vacancies and/or associated defects play in reducing the green luminescent efficiency of n-type GaP. A useful method for obtaining good quality material was developed. It is shown that junction formation at high temperatures in a process where the n to p transition occurs without removing the substrate from the furnace yields devices superior to those obtained by diffusion or double epitaxy in the conventional manner previously used for GaP junction formation.

  9. Technology--The New Gender Gap.

    Science.gov (United States)

    Weinman, Janice; Cain, Lisa

    1999-01-01

    Focuses on the gender gap in computer science and discusses results from a new report, "Gender Gaps," by the American Association of University Women. Examines technology's impact on gender equity and the importance of teacher education. Notes the increased enrollment of girls in math and science and calls for new programs to increase…

  10. Gap junctions and connexin-interacting proteins

    NARCIS (Netherlands)

    Giepmans, Ben N G

    2004-01-01

    Gap junctions form channels between adjacent cells. The core proteins of these channels are the connexins. Regulation of gap junction communication (GJC) can be modulated by connexin-associating proteins, such as regulatory protein phosphatases and protein kinases, of which c-Src is the best-studied

  11. The Wage Gap and Administrative Salaries Today.

    Science.gov (United States)

    Beyer, Kirk D.

    1992-01-01

    Analysis of national data on college administrator salaries by gender, minority/nonminority status, years of service, and institution type found that wage gaps related to gender and minority status persisted in 1991-92 but that interaction of length of service with other study variables explained a significant amount of this gap. (MSE)

  12. Estimating Gender Wage Gaps: A Data Update

    Science.gov (United States)

    McDonald, Judith A.; Thornton, Robert J.

    2016-01-01

    In the authors' 2011 "JEE" article, "Estimating Gender Wage Gaps," they described an interesting class project that allowed students to estimate the current gender earnings gap for recent college graduates using data from the National Association of Colleges and Employers (NACE). Unfortunately, since 2012, NACE no longer…

  13. Gap junctions and connexin-interacting proteins

    NARCIS (Netherlands)

    Giepmans, Ben N G

    2004-01-01

    Gap junctions form channels between adjacent cells. The core proteins of these channels are the connexins. Regulation of gap junction communication (GJC) can be modulated by connexin-associating proteins, such as regulatory protein phosphatases and protein kinases, of which c-Src is the

  14. String matching with variable length gaps

    DEFF Research Database (Denmark)

    Bille, Philip; Gørtz, Inge Li; Vildhøj, Hjalte Wedel

    2012-01-01

    We consider string matching with variable length gaps. Given a string T and a pattern P consisting of strings separated by variable length gaps (arbitrary strings of length in a specified range), the problem is to find all ending positions of substrings in T that match P. This problem is a basic...

  15. Intersectionopoly: A Simulation of the Wage Gap

    Science.gov (United States)

    Paino, Maria; May, Matthew; Burrington, Lori A.; Becker, Jacob H.

    2017-01-01

    This article describes a simulation activity designed to teach students about the wage gap. The wage gap is an important topic in many sociology classrooms, but it can be difficult to convey the accumulated disadvantage experienced by women and racial/ethnic minorities to students using in-class discussions, lectures, or assigned readings alone.…

  16. Caring Closes the Language-Learning Gap

    Science.gov (United States)

    Borba, Mary

    2009-01-01

    The gap in academic achievement between English speakers and English learners continues to concern educators, parents, and legislators. Rising expectations for literacy and the increasing number of students from diverse backgrounds contribute to this achievement gap. In this article, the author discusses a variety of strategies for reaching out to…

  17. Predicting the optical gap of conjugated systems

    Science.gov (United States)

    Botelho, Andre Leitao

    The adapted Su-Schrieffer-Heeger model is developed in this work as a tool for in silico prediction of the optical gap of pi-conjugated systems for photovoltaic applications. Full transferability of the model ensures reliable predictive power - excellent agreement with 180 independent experimental data points covering virtually all existing conjugated system types with an accuracy exceeding the time-dependent density functional theory, one of the most accurate first-principles methods. Insights on the structure-property relation of conjugated systems obtained from the model lead to guiding rules for optical gap design: 1) fusing aromatic rings parallel to the conjugated path does not significantly lower the optical gap, 2) fusing rings perpendicularly lowers the optical gap of the monomer, but has a reduced benefit from polymerization, and 3) copolymers take advantage of the lower optical gap of perpendicular fused rings and benefit from further optical gap reduction through added parallel fused rings as electronic communicators. A copolymer of parallel and perpendicular benzodithiophenes, differing only in sulfur atom locations, is proposed as a candidate to achieve the optimal 1.2 eV donor optical gap for organic photovoltaics. For small-molecule organic photovoltaics, substituting the end pairs of carbon atoms on pentacene with sulfur atoms is predicted to lower the optical gap from 1.8 eV to 1.1 eV. Furthermore, the model offers an improvement of orders of magnitude in the computational efficiency over commonly used first-principles tools.

  18. Delaying the Academy: A Gap Year Education

    Science.gov (United States)

    O'Shea, Joseph

    2011-01-01

    This investigation serves as one of the first empirical analyses to examine the international volunteering gap year from an educational perspective, concluding an in-depth case study of a prominent gap year organisation in the UK. Contrary to widespread industry promotion of international development, the findings suggest that the experience can…

  19. Gap junctions and connexin-interacting proteins

    NARCIS (Netherlands)

    Giepmans, Ben N G

    2004-01-01

    Gap junctions form channels between adjacent cells. The core proteins of these channels are the connexins. Regulation of gap junction communication (GJC) can be modulated by connexin-associating proteins, such as regulatory protein phosphatases and protein kinases, of which c-Src is the best-studied

  20. Closing the Gender Gap: Act Now

    Science.gov (United States)

    OECD Publishing (NJ3), 2012

    2012-01-01

    Gender gaps are pervasive in all walks of economic life and imply large losses in terms of foregone productivity and living standards to the individuals concerned and the economy. This new OECD report focuses on how best to close these gender gaps under four broad headings: (1) Gender equality, social norms and public policies; and gender equality…

  1. Optical response and excitons in gapped graphene

    DEFF Research Database (Denmark)

    Pedersen, Thomas Garm; Jauho, Antti-Pekka; Pedersen, K.

    2009-01-01

    Graphene can be rendered semiconducting via energy gaps introduced in a variety of ways, e.g., coupling to substrates, electrical biasing, or nanostructuring. To describe and compare different realizations of gapped graphene we propose a simple two-band model in which a "mass" term is responsible...

  2. Low band gap polymers for organic photovoltaics

    DEFF Research Database (Denmark)

    Bundgaard, Eva; Krebs, Frederik C

    2007-01-01

    Low band gap polymer materials and their application in organic photovoltaics (OPV) are reviewed. We detail the synthetic approaches to low band gap polymer materials starting from the early methodologies employing quinoid homopolymer structures to the current state of the art that relies...... in photovoltaic applications and give a tabular overview of rarely applied materials....

  3. The "Developing" Achievement Gap: Colombian Voucher Reform

    Science.gov (United States)

    Stern, Jonathan M. B.

    2014-01-01

    The achievement gap in many developing countries is defined in terms of rich/poor and public/private. The prevailing explanation for the "developing" achievement gap is an underfunded, inefficient, and/or inadequately supplied public school sector. Via an analysis of a Colombian voucher experiment, this article examines the extent to…

  4. School Choice and the Achievement Gap

    Science.gov (United States)

    Jeynes, William H.

    2014-01-01

    The possibility is examined that school choice programs could be a means to reducing the achievement gap. Data based on meta-analytic research and the examination of nationwide data sets suggest that school choice programs that include private schools could reduce the achievement gap by 25%. The propounding of this possibility is based on research…

  5. Spin susceptibility of disordered gapped graphene systems

    Science.gov (United States)

    Grosu, I.; Biter, T. L.

    2017-02-01

    We calculate the spin susceptibility for the case of gapped graphene systems in the presence of disorder. The average single-particle density of states in gapped graphene with disorder was calculated, using the Born and the T-matrix approximations. The temperature dependence of the static spin susceptibility was analyzed. The influence of the chemical potential position and disorder is also discussed.

  6. Delaying the Academy: A Gap Year Education

    Science.gov (United States)

    O'Shea, Joseph

    2011-01-01

    This investigation serves as one of the first empirical analyses to examine the international volunteering gap year from an educational perspective, concluding an in-depth case study of a prominent gap year organisation in the UK. Contrary to widespread industry promotion of international development, the findings suggest that the experience can…

  7. Closing the Prescription Drug Coverage Gap

    Science.gov (United States)

    ... drugs they make are covered during the coverage gap for that calendar year. This includes prescription drugs on the plan’s formulary ( ... you pay for generic drugs during the coverage gap will decrease each year until it reaches 25% in 2020. The coverage ...

  8. THE TECHNOLOGY GAP: ANALYSIS AND APPRAISAL

    Science.gov (United States)

    The paper considers the following five points: First, the technological gap is a meaningful concept, and the phenomenon probably is real. Second, it...is nothing new; something like a technological gap between the United States and Europe has existed for upwards of one hundred years. Third, what is

  9. Superconducting gap structure of FeSe.

    Science.gov (United States)

    Jiao, Lin; Huang, Chien-Lung; Rößler, Sahana; Koz, Cevriye; Rößler, Ulrich K; Schwarz, Ulrich; Wirth, Steffen

    2017-03-07

    The microscopic mechanism governing the zero-resistance flow of current in some iron-based, high-temperature superconducting materials is not well understood up to now. A central issue concerning the investigation of these materials is their superconducting gap symmetry and structure. Here we present a combined study of low-temperature specific heat and scanning tunnelling microscopy measurements on single crystalline FeSe. The results reveal the existence of at least two superconducting gaps which can be represented by a phenomenological two-band model. The analysis of the specific heat suggests significant anisotropy in the gap magnitude with deep gap minima. The tunneling spectra display an overall "U"-shaped gap close to the Fermi level away as well as on top of twin boundaries. These results are compatible with the anisotropic nodeless models describing superconductivity in FeSe.

  10. Antideuteron Sensitivity for the GAPS Experiment

    CERN Document Server

    Aramaki, T; Boggs, S E; von Doetinchem, P; Fuke, H; Mognet, S I; Ong, R A; Perez, K; Zweerink, J

    2015-01-01

    The General Antiparticle Spectrometer (GAPS) is a novel approach for indirect dark matter searches that exploits cosmic antiparticles, especially antideuterons. The GAPS antideuteron measurement utilizes distinctive detection methods using atomic X-rays and charged particles from the decay of exotic atoms as well as the timing and stopping range of the incoming particle, which together provide excellent antideuteron identification. Prior to the future balloon experiment, an accelerator test and a prototype flight were successfully conducted in 2005 and 2012 respectively, in order to verify the GAPS detection concept. This paper describes how the sensitivity of GAPS to antideuterons was estimated using a Monte Carlo simulation along with the atomic cascade model and the Intra-Nuclear Cascade model. The sensitivity for the GAPS antideuteron search obtained using this method is 2.0 $\\times 10^{-6}$ [m$^{-2}$s$^{-1}$sr$^{-1}$(GeV/$n$)$^{-1}$] for the proposed long duration balloon program (LDB, 35 days $\\times$ 3...

  11. Terminology gap in hydrological cycle

    Science.gov (United States)

    Zhuo, Lu; Han, Dawei

    2016-04-01

    Water is central to life on Earth. People have been trying to understand how water moves in the hydrosphere throughout the human history. In the 9th century BC, the famous Greek poet Homer described the hydrological cycle in Iliad as "okeanos whose stream bends back in a circle" with a belief that rivers are ocean-fed from subterranean seas. Later, Aristotle (4th century BC) claimed that most of the water came from underground caverns in which air was transformed into water. It was only until 1674, French scientist Perrault developed the correct concept of the water cycle. In modern times, scientists are interested in understanding the individual processes of the hydrological cycle with a keen focus on runoff which supplies water to rivers, lakes, and oceans. Currently, the prevailing concepts on runoff processes include 'infiltration excess runoff' and 'saturation excess runoff'. However, there is no term to describe another major runoff due to the excess beyond the soil water holding capacity (i.e., the field capacity). We argue that a new term should be introduced to fill this gap, and it could be called 'holding excess runoff' which is compatible with the convention. This new term is significant in correcting a half-century misnomer where 'holding excess runoff' has been incorrectly named as 'saturation excess runoff', which was introduced by the Xinanjiang model in China in 1960s. Similar concept has been adopted in many well-known hydrological models such as PDM and HBV in which the saturation refers to the field capacity. The term 'holding excess runoff' resolves such a common confusion in the hydrological community.

  12. Comparison of two methods of mathematical modeling in hydrodynamic sealing gap

    Directory of Open Access Journals (Sweden)

    Krutil Jaroslav

    2015-01-01

    Full Text Available The aim of work is to compare two possible methods of mathematical modeling of hydrodynamic instabilities. This comparison is performed by monitoring the formation and evolution of Taylor vortices in hydrodynamic sealing gap. Sealing gaps are a part of the hydraulic machines with the impeller, such as turbines and pumps, and they have an effect on the volumetric efficiency of these devices. This work presents two examples of sealing gaps. These examples are closed sealing gap and modified sealing gap with expansion chamber. On these two examples are applied procedures of solution contained in CFD software (ANSYS Fluent 14.5. In ANSYS Fluent is two possible basic approaches of solution this task: the moving wall method and the sliding mesh method. The result of work is monitoring the impact of the expansion chamber on the formation of hydrodynamic instabilities in the sealing gap. Another result is comparison of two used methods of mathematical modeling, which shows that both methods can be used for similar tasks.

  13. The Plateau of Moment of Inertia and the Energy Gap in 161-168Yb

    Institute of Scientific and Technical Information of China (English)

    HUANG Li-Xun; QI Yan-Jun; LI Tao; LIU Shu-Xin

    2011-01-01

    The influence of the gap at Z = 70 on the alignment in 161 168Yb is studied using the particle number conserving method. If there is a gap at the Fermi surface, the occupation probability of the [523)7/2 proton orbital does not change as much as when there is no gap. The formation of the plateau of moment of inertia is sensitive to the relative position of the orbital tt[404]7/2, tt[411]1/2 and tt[523]7/2. A third backbending caused by tt[541]1/2 is predicted.%@@ The influence of the gap at Z=70 on the alignment in 161-168Yb is studied using the particle number conserving method.If there is a gap at the Fermi surface,the occupation probability of the[523]7/2 proton orbital does not change as much as when there is no gap.The formation of the plateau of moment of inertia is sensitive to the relative position of the orbital π[404]7/2,π[411]1/2 and π[523]7/2.A third backbending caused by π[541]1/2 is predicted.

  14. Binary-disk interaction. II. Gap-opening criteria for unequal-mass binaries

    Energy Technology Data Exchange (ETDEWEB)

    Del Valle, Luciano; Escala, Andrés, E-mail: ldelvalleb@gmail.com [Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago (Chile)

    2014-01-01

    We study the interaction of an unequal-mass binary with an isothermal circumbinary disk, motivated by the theoretical and observational evidence that after a major merger of gas-rich galaxies, a massive gaseous disk with a supermassive black hole binary will be formed in the nuclear region. We focus on the gravitational torques that the binary exerts on the disk and how these torques can drive the formation of a gap in the disk. This exchange of angular momentum between the binary and the disk is mainly driven by the gravitational interaction between the binary and a strong nonaxisymmetric density perturbation that is produced in the disk, in response to the presence of the binary. Using smoothed particle hydrodynamics numerical simulations, we test two gap-opening criteria, one that assumes the geometry of the density perturbation is an ellipsoid/thick spiral and another that assumes a flat spiral geometry for the density perturbation. We find that the flat spiral gap-opening criterion successfully predicts which simulations will have a gap in the disk and which will not. We also study the limiting cases predicted by the gap-opening criteria. Since the viscosity in our simulations is considerably smaller than the expected value in the nuclear regions of gas-rich merging galaxies, we conclude that in such environments the formation of a circumbinary gap is unlikely.

  15. SYNGAP1: mind the GAP

    Directory of Open Access Journals (Sweden)

    Nallathambi eJeyabalan

    2016-02-01

    Full Text Available A cardinal feature of early stages of human brain development centres on the sensory, cognitive, and emotional experiences that shape neuronal-circuit formation and refinement. Consequently, alterations in these processes account for many psychiatric and neurodevelopmental disorders. Neurodevelopment disorders affect 3-4% of the world population. The impact of these disorders presents a major challenge to clinicians, geneticists, and neuroscientists. Mutations that cause neurodevelopmental disorders are commonly found in genes encoding proteins that regulate synaptic function. Investigation of the underlying mechanisms using gain or loss of function approaches has revealed alterations in dendritic spine structure, function, and plasticity, consequently modulating the neuronal circuit formation and thereby raising the possibility of neurodevelopmental disorders resulting from synaptopathies. One such gene, SYNGAP1 (Synaptic Ras-GTPase-activating protein has been shown to cause Intellectual Disability with comorbid Autism Spectrum Disorder and epilepsy in children. SYNGAP1 is a negative regulator of Ras, Rap and of AMPA receptor trafficking to the postsynaptic membrane, thereby regulating not only synaptic plasticity, but also neuronal homeostasis. Recent studies on the neurophysiology of SYNGAP1, using Syngap1 mouse models, have provided deeper insights into how downstream signalling proteins and synaptic plasticity are regulated by SYNGAP1. This knowledge has led to a better understanding of the function of SYNGAP1 and suggests a potential target during critical period of development when the brain is more susceptible to therapeutic intervention.

  16. Determining the nature of the gap in semiconducting graphene

    Science.gov (United States)

    Prestigiacomo, J. C.; Nath, A.; Osofsky, M. S.; Hernández, S. C.; Wheeler, V. D.; Walton, S. G.; Gaskill, D. K.

    2017-01-01

    Since its discovery, graphene has held great promise as a two-dimensional (2D) metal with massless carriers and, thus, extremely high-mobility that is due to the character of the band structure that results in the so-called Dirac cone for the ideal, perfectly ordered crystal structure. This promise has led to only limited electronic device applications due to the lack of an energy gap which prevents the formation of conventional device geometries. Thus, several schemes for inducing a semiconductor band gap in graphene have been explored. These methods do result in samples whose resistivity increases with decreasing temperature, similar to the temperature dependence of a semiconductor. However, this temperature dependence can also be caused by highly diffusive transport that, in highly disordered materials, is caused by Anderson-Mott localization and which is not desirable for conventional device applications. In this letter, we demonstrate that in the diffusive case, the conventional description of the insulating state is inadequate and demonstrate a method for determining whether such transport behavior is due to a conventional semiconductor band gap. PMID:28181521

  17. Determining the nature of the gap in semiconducting graphene

    Science.gov (United States)

    Prestigiacomo, J. C.; Nath, A.; Osofsky, M. S.; Hernández, S. C.; Wheeler, V. D.; Walton, S. G.; Gaskill, D. K.

    2017-02-01

    Since its discovery, graphene has held great promise as a two-dimensional (2D) metal with massless carriers and, thus, extremely high-mobility that is due to the character of the band structure that results in the so-called Dirac cone for the ideal, perfectly ordered crystal structure. This promise has led to only limited electronic device applications due to the lack of an energy gap which prevents the formation of conventional device geometries. Thus, several schemes for inducing a semiconductor band gap in graphene have been explored. These methods do result in samples whose resistivity increases with decreasing temperature, similar to the temperature dependence of a semiconductor. However, this temperature dependence can also be caused by highly diffusive transport that, in highly disordered materials, is caused by Anderson-Mott localization and which is not desirable for conventional device applications. In this letter, we demonstrate that in the diffusive case, the conventional description of the insulating state is inadequate and demonstrate a method for determining whether such transport behavior is due to a conventional semiconductor band gap.

  18. Quantifying Audit Expectation Gap: A New approach to Measuring Expectation Gap

    Directory of Open Access Journals (Sweden)

    Salehi Mahdi

    2016-05-01

    Full Text Available The main objective of the study is at first identifying the expectation gap about audit responsibility and the second quantifying the expectation gap in Iran. In order to collecting data, a questionnaire designed and developed between auditors and investors. Collected data analyzed by employing non-parametric statistics test. The results show that there is expectation gap between auditors and investors in Iran. The current study employed a new approach in the world in order to quantifying the expectation gap. It gives the more strength to other researchers in order to measuring audit expectation gap in the world.

  19. Segregation and the gender wage gaps in the private and the public sector

    DEFF Research Database (Denmark)

    Albæk, Karsten; Larsen, Mona; Stage Thomsen, Lars

    2016-01-01

    This paper examines the relation between segregation and the gender wage gap in the public and the private sectors in Denmark from 2002 to 2012. The analysis shows that male–female differences in the share of females in occupations, industries,establishments and job cells (occupations within...... establishments) constitute 46% of the raw gender wage gap in the private sector, while segregation in t he public sector accounts for as much as 63 %. Segregation thus plays a substantially more important role in accounting for the gender wage gap in the public sector than in the private sector. While...... the importance of segregation for wage formation decreased substantially in the public sector over time, it only decreased slightly in the private sector. Although the remaining gender wage gap, after controlling for segregation, is close to zero in the public sector, a substantial within-job cell differential...

  20. Isotropic properties of the photonic band gap in quasicrystals with low-index contrast

    CERN Document Server

    Rose, Priya; Abbate, G; Andreone, A

    2011-01-01

    We report on the formation and development of the photonic band gap in two-dimensional 8-, 10- and 12-fold symmetry quasicrystalline lattices of low index contrast. Finite size structures made of dielectric cylindrical rods were studied and measured in the microwave region, and their properties compared with a conventional hexagonal crystal. Band gap characteristics were investigated by changing the direction of propagation of the incident beam inside the crystal. Various angles of incidence from 0 \\degree to 30\\degree were used in order to investigate the isotropic nature of the band gap. The arbitrarily high rotational symmetry of aperiodically ordered structures could be practically exploited to manufacture isotropic band gap materials, which are perfectly suitable for hosting waveguides or cavities.

  1. Segregation and the gender wage gaps in the private and the public sector

    DEFF Research Database (Denmark)

    Albæk, Karsten; Larsen, Mona; Stage Thomsen, Lars

    2016-01-01

    establishments) constitute 46% of the raw gender wage gap in the private sector, while segregation in t he public sector accounts for as much as 63 %. Segregation thus plays a substantially more important role in accounting for the gender wage gap in the public sector than in the private sector. While...... the importance of segregation for wage formation decreased substantially in the public sector over time, it only decreased slightly in the private sector. Although the remaining gender wage gap, after controlling for segregation, is close to zero in the public sector, a substantial within-job cell differential......This paper examines the relation between segregation and the gender wage gap in the public and the private sectors in Denmark from 2002 to 2012. The analysis shows that male–female differences in the share of females in occupations, industries,establishments and job cells (occupations within...

  2. Band gap engineering of N-alloyed Ga2O3 thin films

    Directory of Open Access Journals (Sweden)

    Dongyu Song

    2016-06-01

    Full Text Available The authors report the tuning of band gap of GaON ternary alloy in a wide range of 2.75 eV. The samples were prepared by a two-step nitridation method. First, the samples were deposited on 2-inch fused silica substrates by megnetron sputtering with NH3 and Ar gas for 60 minutes. Then they were annealed in NH3 ambience at different temperatures. The optical band gap energies are calculated from transmittance measurements. With the increase of nitridation temperature, the band gap gradually decreases from 4.8 eV to 2.05 eV. X-ray diffraction results indicate that as-deposited amorphous samples can crystallize into monoclinic and hexagonal structures after they were annealed in oxygen or ammonia ambience, respectively. The narrowing of the band gap is attributed to the enhanced repulsion of N2p -Ga3d orbits and formation of hexagonal structure.

  3. Confined PBX 9501 gap reinitiation studies

    Energy Technology Data Exchange (ETDEWEB)

    Salyer, Terry R [Los Alamos National Laboratory; Hill, Larry G [Los Alamos National Laboratory; Lam, Kin [Los Alamos National Laboratory

    2009-01-01

    For explosive systems that exhibit gaps or cracks between their internal components (either by design or mechanical failure), measurable time delays exist for detonation waves crossing them. Reinitiation across such gaps is dependent on the type of explosive, gap width, gap morphology, confinement, and temperature effects. To examine this reinitiation effect, a series of tests has been conducted to measure the time delay across a prescribed gap within an 'infinitely' confined PBX 9501 system. Detonation breakout along the explosive surface is measured with a streak camera, and flow features are examined during reinitiation near the gap. Such tests allow for quantitative determination of the time delay corresponding to the time of initiation across a given gap oriented normal to the direction of the detonation wave. Measured time delays can be compared with numerical calculations, making it possible to validate initiation models as well as estimate detonation run-up distances. Understanding this reinitiation behavior is beneficial for the design and evaluation of explosive systems that require precision timing and performance.

  4. Abort Gap Cleaning for LHC Run 2

    Energy Technology Data Exchange (ETDEWEB)

    Uythoven, Jan [CERN; Boccardi, Andrea [CERN; Bravin, Enrico [CERN; Goddard, Brennan [CERN; Hemelsoet, Georges-Henry [CERN; Höfle, Wolfgang [CERN; Jacquet, Delphine [CERN; Kain, Verena [CERN; Mazzoni, Stefano [CERN; Meddahi, Malika [CERN; Valuch, Daniel [CERN; Gianfelice-Wendt, Eliana [Fermilab

    2014-07-01

    To minimize the beam losses at the moment of an LHC beam dump the 3 μs long abort gap should contain as few particles as possible. Its population can be minimised by abort gap cleaning using the LHC transverse damper system. The LHC Run 1 experience is briefly recalled; changes foreseen for the LHC Run 2 are presented. They include improvements in the observation of the abort gap population and the mechanism to decide if cleaning is required, changes to the hardware of the transverse dampers to reduce the detrimental effect on the luminosity lifetime and proposed changes to the applied cleaning algorithms.

  5. One-Dimensional Anisotropic Band Gap Structure

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The band gap structure of one-dimensional anisotropic photonic crystal has been studied by means of the transfer matrix formalism. From the analytic expressions and numeric calculations we see some general characteristics of the band gap structure of anisotropic photonic crystals, each band separates into two branches and the two branches react to polarization sensitively. In the practical case of oblique incidence, gaps move towards high frequency when the angle of incidence increases. Under some special conditions, the two branches become degenerate again.

  6. Method for Bubbledeck Concrete Slab with Gaps

    Directory of Open Access Journals (Sweden)

    Sergiu Călin

    2009-01-01

    Full Text Available The composite slabs are made of BubbleDeck type slab elements with spherical gaps, poured in place on transversal and longitudinal directions. By introducing the gaps leads to a 30...50\\% lighter slab which reduces the loads on the columns, walls and foundations, and of course of the entire building. BubbleDeck slab elements are plates with ribs on two directions made of reinforced concrete or precast concrete with spherical shaped bubbles. These slab elements have a bottom and an upper concrete part connected with vertical ribs that go around the gaps.

  7. Refractive Indices of Semiconductors from Energy gaps

    CERN Document Server

    Tripathy, S K

    2015-01-01

    An empirical relation based on energy gap and refractive index data has been proposed in the present study to calculate the refractive index of semiconductors. The proposed model is then applied to binary as well as ternary semiconductors for a wide range of energy gap. Using the relation, dielectric constants of some III-V group semiconductors are calculated. The calculated values for different group of binary semiconductors, alkali halides and ternary semiconductors fairly agree with other calculations and known values over a wide range of energy gap. The temperature variation of refractive index for some binary semiconductors have been calculated.

  8. LHC Abort Gap Monitoring and Cleaning

    CERN Document Server

    Meddahi, M; Boccardi, A; Butterworth, A; Fisher, A S; Gianfelice-Wendt, E; Goddard, B; Hemelsoet, G H; Höfle, W; Jacquet, D; Jaussi, M; Kain, V; Lefevre, T; Shaposhnikova, E; Uythoven, J; Valuch, D

    2010-01-01

    Unbunched beam is a potentially serious issue in the LHC as it may quench the superconducting magnets during a beam abort. Unbunched particles, either not captured by the RF system at injection or leaking out of the RF bucket, will be removed by using the existing damper kickers to excite resonantly the particles in the abort gap. Following beam simulations, a strategy for cleaning the abort gap at different energies was proposed. The plans for the commissioning of the beam abort gap cleaning are described and first results from the beam commissioning are presented.

  9. A gap clearing kicker for Main Injector

    CERN Document Server

    Kourbanis, I; Biggs, J; Brown, B; Capista, D; Jensen, C C; Krafczyk, G E; Morris, D K; Scott, D; Seiya, K; Ward, S R; Wu, G; Yang, M -J

    2012-01-01

    Fermilab Main Injector has been operating at high Beam Power levels since 2008 when multi-batch slip stacking became operational. In order to maintain and increase the beam power levels the localized beam loss due to beam left over in the injection kicker gap during slip stacking needs to be addressed. A set of gap clearing kickers that kick any beam left in the injection gap to the beam abort have been built. The kickers were installed in the summer of 2009 and became operational in November of 2010. The kicker performance and its effect on the beam losses will be described.

  10. Abort Gap Cleaning for LHC Run 2

    CERN Document Server

    Uythoven, J; Bravin, E; Goddard, B; Hemelsoet, GH; Höfle, W; Jacquet, D; Kain, V; Mazzoni, S; Meddahi, M; Valuch, D

    2015-01-01

    To minimise the beam losses at the moment of an LHC beam dump the 3 μs long abort gap should contain as few particles as possible. Its population can be minimised by abort gap cleaning using the LHC transverse damper system. The LHC Run 1 experience is briefly recalled; changes foreseen for the LHC Run 2 are presented. They include improvements in the observation of the abort gap population and the mechanism to decide if cleaning is required, changes to the hardware of the transverse dampers to reduce the detrimental effect on the luminosity lifetime and proposed changes to the applied cleaning algorithms.

  11. NIRI Imaging of Transitional Protoplanetary Disks with Submm-Resolved Inner Holes/Gaps

    Science.gov (United States)

    Currie, Thayne; Condell, Hannah Jang; Robitaille, Thomas; Dahm, Scott; Wilner, David; Andrews, Sean; Kuchner, Marc

    2011-08-01

    Disks around young stars with inner holes/gaps (transitional disks) provide a crucial probe of active planet formation and/or the last phases of planet formation. We propose high-contrast Gemini/NIRI imaging of disks around four stars with inner holes/gaps: LkCa 15, MWC 758, LkHa 330, and UX Tau A. In all cases, the disks have been spatially resolved in the submm, have inner holes/gaps large enough to be resolved by NIRI, and show structural features indicative of sculpting by unseen planets. Our study will provide sensitive constraints on the presence of planet-mass objects and provide a detailed probe of the structure of disks in the process of spawning planetary systems.

  12. CZTS stoichiometry effects on the band gap energy

    Energy Technology Data Exchange (ETDEWEB)

    Malerba, Claudia, E-mail: claudia.malerba-1@ing.unitn.it [University of Trento, Department of Civil, Environmental and Mechanical Engineering, via Mesiano 77, 38123 Trento (Italy); ENEA, Casaccia Research Center, via Anguillarese 301, 00123 Roma (Italy); Biccari, Francesco [ENEA, Casaccia Research Center, via Anguillarese 301, 00123 Roma (Italy); Azanza Ricardo, Cristy Leonor [University of Trento, Department of Civil, Environmental and Mechanical Engineering, via Mesiano 77, 38123 Trento (Italy); Valentini, Matteo [Sapienza – University of Rome, Department of Physics, p.le A. Moro 5, 00185 Roma (Italy); ENEA, Casaccia Research Center, via Anguillarese 301, 00123 Roma (Italy); Chierchia, Rosa [ENEA, Casaccia Research Center, via Anguillarese 301, 00123 Roma (Italy); Müller, Melanie [University of Trento, Department of Civil, Environmental and Mechanical Engineering, via Mesiano 77, 38123 Trento (Italy); Max Planck Institute for Solid State Research, Heisenberg str. 1, 70569 Stuttgart (Germany); Santoni, Antonino [ENEA, Frascati Research Center, via E. Fermi 45, 00044 Frascati (Italy); Esposito, Emilia [ENEA, Portici Research Center, Piazzale E. Fermi, 80055 Portici (Napoli) (Italy); Mangiapane, Pietro [ENEA, Casaccia Research Center, via Anguillarese 301, 00123 Roma (Italy); Scardi, Paolo [University of Trento, Department of Civil, Environmental and Mechanical Engineering, via Mesiano 77, 38123 Trento (Italy); Mittiga, Alberto [ENEA, Casaccia Research Center, via Anguillarese 301, 00123 Roma (Italy)

    2014-01-05

    Highlights: • CZTS films with different compositions were grown from stacked-layer precursors. • The band-gap energy varies from 1.48 to 1.63 eV as the [Sn]/[Cu] ratio increases. • The Zn content seems not to be a critical parameter for the optical properties. • PDS data show an increase of the sub-gap absorption as the Sn content is reduced. • Formation of defects at low Sn content was proposed to explain the Eg variation. -- Abstract: The considerable spread of Cu{sub 2}ZnSnS{sub 4} (CZTS) optical properties reported in the literature is discussed in terms of material stoichiometry. To this purpose, kesterite thin films were prepared by sulfurization of multilayered precursors of ZnS, Cu and Sn, changing the relative amounts to obtain CZTS layers with different compositions. X-Ray Diffraction (XRD), Energy Dispersive X-Ray (EDX) spectroscopy, X-Ray Photoelectron Spectroscopy (XPS) and Raman spectroscopy were used for structural and compositional analysis. XRD quantitative phase analysis provides the amount of spurious phases and information on Sn-site occupancy. The optical properties were investigated by spectrophotometric and Photothermal Deflection Spectroscopy (PDS) measurements to assess the absorption coefficient of samples with different compositions. The PDS data show an increase of the sub-band absorption as the Sn content decreases. The results are interpreted assuming the formation of additional defects as the tin content is reduced. Those defects can also be responsible for the decrease of the band gap energy value as the Sn/Cu ratio is decreased.

  13. Gap locations influence the release of carbon, nitrogen and phosphorus in two shrub foliar litter in an alpine fir forest.

    Science.gov (United States)

    He, Wei; Wu, Fuzhong; Yang, Wanqin; Zhang, Danju; Xu, Zhenfeng; Tan, Bo; Zhao, Yeyi; Justine, Meta Francis

    2016-02-24

    Gap formation favors the growth of understory plants and affects the decomposition process of plant debris inside and outside of gaps. Little information is available regarding how bioelement release from shrub litter is affected by gap formation during critical periods. The release of carbon (C), nitrogen (N), and phosphorus (P) in the foliar litter of Fargesia nitida and Salix paraplesia in response to gap locations was determined in an alpine forest of the eastern Qinghai-Tibet Plateau via a 2-year litter decomposition experiment. The daily release rates of C, N, and P increased from the closed canopy to the gap centers during the two winters, the two later growing seasons and the entire 2 years, whereas this trend was reversed during the two early growing seasons. The pairwise ratios among C, N, and P converged as the litter decomposition proceeded. Compared with the closed canopy, the gap centers displayed higher C:P and N:P ratio but a lower C:N ratio as the decomposition proceeded. Alpine forest gaps accelerate the release of C, N, and P in decomposing shrub litter, implying that reduced snow cover resulting from vanishing gaps may inhibit the release of these elements in alpine forests.

  14. Ultrafast Charge Separation in Low Band-Gap Polymer Blend for Photovoltaics

    Directory of Open Access Journals (Sweden)

    Egelhaaf Hans-J.

    2013-03-01

    Full Text Available We track ultrafast charge dissociation in a particularly promising low-band-gap- polymer:fullerene blend for organic photovoltaics. Impulsive photoexcitation with excess energy leads to a 30-fs formation of an hot charge transfer state, precursor of free carriers.

  15. Globalization and the Gender Wage Gap

    National Research Council Canada - National Science Library

    Remco H. Oostendorp

    There are several theoretical reasons why globalization will have a narrowing as well as a widening effect on the gender wage gap, but little is known about the actual impact, except for some country studies...

  16. Device Physics of Narrow Gap Semiconductors

    CERN Document Server

    Chu, Junhao

    2010-01-01

    Narrow gap semiconductors obey the general rules of semiconductor science, but often exhibit extreme features of these rules because of the same properties that produce their narrow gaps. Consequently these materials provide sensitive tests of theory, and the opportunity for the design of innovative devices. Narrow gap semiconductors are the most important materials for the preparation of advanced modern infrared systems. Device Physics of Narrow Gap Semiconductors offers descriptions of the materials science and device physics of these unique materials. Topics covered include impurities and defects, recombination mechanisms, surface and interface properties, and the properties of low dimensional systems for infrared applications. This book will help readers to understand not only the semiconductor physics and materials science, but also how they relate to advanced opto-electronic devices. The last chapter applies the understanding of device physics to photoconductive detectors, photovoltaic infrared detector...

  17. Sustainability Tools Inventory - Initial Gaps Analysis

    Science.gov (United States)

    This report identifies a suite of tools that address a comprehensive set of community sustainability concerns. The objective is to discover whether "gaps" exist in the tool suite’s analytic capabilities. These tools address activities that significantly influenc...

  18. Multi Band Gap High Efficiency Converter (RAINBOW)

    Science.gov (United States)

    Bekey, I.; Lewis, C.; Phillips, W.; Shields, V.; Stella, P.

    1997-01-01

    The RAINBOW multi band gap system represents a unique combination of solar cells, concentrators and beam splitters. RAINBOW is a flexible system which can readily expand as new high efficiency components are developed.

  19. School Segregation and Racial Academic Achievement Gaps

    Directory of Open Access Journals (Sweden)

    Sean F. Reardon

    2016-09-01

    Full Text Available Although it is clear that racial segregation is linked to academic achievement gaps, the mechanisms underlying this link have been debated since James Coleman published his eponymous 1966 report. In this paper, I examine sixteen distinct measures of segregation to determine which is most strongly associated with academic achievement gaps. I find clear evidence that one aspect of segregation in particular—the disparity in average school poverty rates between white and black students’ schools—is consistently the single most powerful correlate of achievement gaps, a pattern that holds in both bivariate and multivariate analyses. This implies that high-poverty schools are, on average, much less effective than lower-poverty schools and suggests that strategies that reduce the differential exposure of black, Hispanic, and white students to poor schoolmates may lead to meaningful reductions in academic achievement gaps.

  20. Structural Dynamics of Tropical Moist Forest Gaps

    OpenAIRE

    Hunter, Maria O.; Michael Keller; Douglas Morton; Bruce Cook; Michael Lefsky; Mark Ducey; Scott Saleska; Raimundo Cosme de Oliveira; Juliana Schietti

    2015-01-01

    Gap phase dynamics are the dominant mode of forest turnover in tropical forests. However, gap processes are infrequently studied at the landscape scale. Airborne lidar data offer detailed information on three-dimensional forest structure, providing a means to characterize fine-scale (1 m) processes in tropical forests over large areas. Lidar-based estimates of forest structure (top down) differ from traditional field measurements (bottom up), and necessitate clear-cut definitions unencumbered...

  1. Columbia River Component Data Gap Analysis

    Energy Technology Data Exchange (ETDEWEB)

    L. C. Hulstrom

    2007-10-23

    This Data Gap Analysis report documents the results of a study conducted by Washington Closure Hanford (WCH) to compile and reivew the currently available surface water and sediment data for the Columbia River near and downstream of the Hanford Site. This Data Gap Analysis study was conducted to review the adequacy of the existing surface water and sediment data set from the Columbia River, with specific reference to the use of the data in future site characterization and screening level risk assessments.

  2. Gap Waves in Piezoelectric layered Medium

    Directory of Open Access Journals (Sweden)

    Danoyan Z.N.

    2007-03-01

    Full Text Available In the present paper the conditions of existence of shear electroelastic gap waves in piezoelectric-vacuum-dielectric layered system are found. It is shown that in the discontact layered system the gap electroelastic waves can be propagated. It is considered the limiting case when the thickness of vacuuming layer tends to zero. It is proved that the statement of the problem is true when there is no acoustic contact between piezoelectric and dielectric grounded media.

  3. Modification in band gap of zirconium complexes

    Science.gov (United States)

    Sharma, Mayank; Singh, J.; Chouhan, S.; Mishra, A.; Shrivastava, B. D.

    2016-05-01

    The optical properties of zirconium complexes with amino acid based Schiff bases are reported here. The zirconium complexes show interesting stereo chemical features, which are applicable in organometallic and organic synthesis as well as in catalysis. The band gaps of both Schiff bases and zirconium complexes were obtained by UV-Visible spectroscopy. It was found that the band gap of zirconium complexes has been modified after adding zirconium compound to the Schiff bases.

  4. Explaining personality pay gaps in the UK

    OpenAIRE

    Nandi, Alita; Nicoletti, Cheti

    2009-01-01

    Using the British Household Panel Survey we examine how the Big Five personality traits - openness to experience, conscientiousness, extroversion, agreeableness, and neuroticism - affect wages. We estimate mean and quantile pay gaps between people with low and high levels of each of the Big Five, and decompose these pay gaps in the part explained by differences in workers’ characteristics and in the residual unexplained part. We find that openness to experience is the most relevant personal...

  5. Light transmission through a triangular air gap

    CERN Document Server

    Carvalho, Silvania A

    2013-01-01

    Due to the recent interest in studying propagation of light through triangular air gaps, we calculate, by using the analogy between optics and quantum mechanics and the multiple step technique, the transmissivity through a triangular air gap surrounded by an homogeneous dielectric medium. The new formula is then compared with the formula used in literature. Starting from the qualitative and quantitative differences between these formulas, we propose optical experiments to test our theoretical results.

  6. Modification in band gap of zirconium complexes

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Mayank, E-mail: mayank30134@gmail.com; Singh, J.; Chouhan, S. [Department of Physics, ISLE, IPS Academy, Indore (M.P.) (India); Mishra, A. [School of Physics, Devi Ahilya Vishwavidyalaya, Indore (M.P.) (India); Shrivastava, B. D. [Govt. P. G. College, Biora (M.P.) (India)

    2016-05-06

    The optical properties of zirconium complexes with amino acid based Schiff bases are reported here. The zirconium complexes show interesting stereo chemical features, which are applicable in organometallic and organic synthesis as well as in catalysis. The band gaps of both Schiff bases and zirconium complexes were obtained by UV-Visible spectroscopy. It was found that the band gap of zirconium complexes has been modified after adding zirconium compound to the Schiff bases.

  7. Galaxy Formation

    DEFF Research Database (Denmark)

    Sparre, Martin

    Galaxy formation is an enormously complex discipline due to the many physical processes that play a role in shaping galaxies. The objective of this thesis is to study galaxy formation with two different approaches: First, numerical simulations are used to study the structure of dark matter and how...... galaxies form stars throughout the history of the Universe, and secondly it is shown that observations of gamma-ray bursts (GRBs) can be used to probe galaxies with active star formation in the early Universe. A conclusion from the hydrodynamical simulations is that the galaxies from the stateof......-the-art cosmological simulation, Illustris, follow a tight relation between star formation rate and stellar mass. This relation agrees well with the observed relation at a redshift of z = 0 and z = 4, but at intermediate redshifts of z ' 2 the normalisation is lower than in real observations. This is highlighted...

  8. Superconducting gap anomaly in heavy fermion systems

    Indian Academy of Sciences (India)

    G C Rout; M S Ojha; S N Behera

    2008-04-01

    The heavy fermion system (HFS) is described by the periodic Anderson model (PAM), treating the Coulomb correlation between the -electrons in the mean-field Hartree-Fock approximation. Superconductivity is introduced by a BCS-type pairing term among the conduction electrons. Within this approximation the equation for the superconducting gap is derived, which depends on the effective position of the energy level of the -electrons relative to the Fermi level. The latter in turn depends on the occupation probability f of the -electrons. The gap equation is solved self-consistently with the equation for f; and their temperature dependences are studied for different positions of the bare -electron energy level, with respect to the Fermi level. The dependence of the superconducting gap on the hybridization leads to a re-entrant behaviour with increasing strength. The induced pairing between the -electrons and the pairing of mixed conduction and -electrons due to hybridization are also determined. The temperature dependence of the hybridization parameter, which characterizes the number of electrons with mixed character and represents the number of heavy electrons is studied. This number is shown to be small. The quasi-particle density of states (DOS) shows the existence of a pseudo-gap due to superconductivity and the signature of a hybridization gap at the Fermi level. For the choice of the model parameters, the DOS shows that the HFS is a metal and undergoes a transition to the gap-less superconducting state.

  9. Undecidability of the Spectral Gap (full version)

    CERN Document Server

    Cubitt, Toby; Wolf, Michael M

    2015-01-01

    We show that the spectral gap problem is undecidable. Specifically, we construct families of translationally-invariant, nearest-neighbour Hamiltonians on a 2D square lattice of $d$-level quantum systems ($d$ constant), for which determining whether the system is gapped or gapless is an undecidable problem. This is true even with the promise that each Hamiltonian is either gapped or gapless in the strongest sense: it is promised to either have continuous spectrum above the ground state in the thermodynamic limit, or its spectral gap is lower-bounded by a constant in the thermodynamic limit. Moreover, this constant can be taken equal to the local interaction strength of the Hamiltonian. This implies that it is logically impossible to say in general whether a quantum many-body system is gapped or gapless. Our results imply that there exist specific Hamiltonians for which the presence or absence of a spectral gap is independent of all consistent axiomatisations of mathematics. These results have a number of impor...

  10. Plasmon transmission through excitonic subwavelength gaps

    CERN Document Server

    Sukharev, Maxim

    2016-01-01

    We study the transfer of electromagnetic energy across a subwavelength gap separating two co-axial metal nanorodes. The absence of spacer in the gap separating the rods the system exhibits the strong coupling between longitudinal plasmons in the two rods. The nature and magnitude of this coupling is studied by varying various geometrical parameters. When the length of one rod is varied this mode spectrum exhibits the familiar anti-crossing behavior that depends on the coupling strength determined by the gap width. As a function of frequency the transmission is dominated by a splitted longitudinal plasmon peak. The two hybrid modes are the dipole-like "bonding" mode characterized by a peak intensity in the gap, and a quadrupole-like "antibonding" mode whose amplitude vanishes at the gap center. When off-resonant $2-$level emitters are placed in the gap, almost no effect on the frequency dependent transmission is observed. In contrast, when the molecular system is resonant with the plasmonic lineshape, the tran...

  11. Plasmon resonances in atomic-scale gaps

    CERN Document Server

    Kern, Johannes; Tarakina, Nadezda V; Häckel, Tim; Emmerling, Monika; Kamp, Martin; Huang, Jer-Shing; Biagioni, Paolo; Prangsma, Jord C; Hecht, Bert

    2011-01-01

    Gap modes in resonant plasmonic nanostructures exhibit optical fields whose spatial confinement and near-field enhancement strongly increases for smaller gaps[1]. In the context of augmented light-matter interaction, gap modes are of high interest for various applications such as single-emitter spectroscopy[2-4], quantum optics[5,6], extreme nonlinear optics[7,8], efficient optical switching[9], optical trapping10, and molecular opto-electronics[11]. By means of reproducible self-assembly we have obtained side-by-side aligned gold nanorod dimers with robust gaps reaching well below 0.5 nm. For such atomic-scale gaps extreme splitting of the symmetric and anti-symmetric dimer eigenmodes of more than 800 meV is observed in white-light scattering experiments. Besides providing evidence for atomic-scale gap modes at visible wavelengths with correspondingly small mode volumes and strong field enhancement, our experimental results can serve as a benchmark for electromagnetic modeling beyond local Maxwell theory[12,...

  12. Gap junction intercellular communication and benzene toxicity.

    Science.gov (United States)

    Rivedal, Edgar; Witz, Gisela; Leithe, Edward

    2010-03-19

    Aberrant regulation of gap junction intercellular communication (GJIC) has been linked to several human diseases, including cancer and abnormal hematopoietic development. Benzene exposure has been shown to cause hematotoxicity and leukemia, but the underlying mechanisms involved remain unclear. We have observed that several metabolites of benzene have the ability to block gap junction intercellular communication. The ring-opened trans,trans-muconaldehyde (MUC) was found to be the most potent inhibitor of gap junction channels. MUC was found to induce cross-linking of the gap junction protein connexin43, which seemed to be responsible for the induced inhibition of GJIC. Glutaraldehyde, which has a similar molecular structure as MUC, was found to possess similar effects on gap junctions as MUC, while the mono-aldehyde formaldehyde shows lower potency, both as a connexin cross-linker, and as an inhibitor of GJIC. Both glutaraldehyde and formaldehyde have previously been associated with induction of leukemia and disturbance of hematopoiesis. Taken together, the data support a possible link between the effect of MUC on gap junctions, and the toxic effects of benzene. Copyright (c) 2009 Elsevier Ireland Ltd. All rights reserved.

  13. Water limits to closing yield gaps

    Science.gov (United States)

    Davis, Kyle Frankel; Rulli, Maria Cristina; Garrassino, Francesco; Chiarelli, Davide; Seveso, Antonio; D'Odorico, Paolo

    2017-01-01

    Agricultural intensification is often seen as a suitable approach to meet the growing demand for agricultural products and improve food security. It typically entails the use of fertilizers, new cultivars, irrigation, and other modern technology. In regions of the world affected by seasonal or chronic water scarcity, yield gap closure is strongly dependent on irrigation (blue water). Global yield gap assessments have often ignored whether the water required to close the yield gap is locally available. Here we perform a gridded global analysis (10 km resolution) of the blue water consumption that is needed annually to close the yield gap worldwide and evaluate the associated pressure on renewable freshwater resources. We find that, to close the yield gap, human appropriation of freshwater resources for irrigation would have to increase at least by 146%. Most study countries would experience at least a doubling in blue water requirement, with 71% of the additional blue water being required by only four crops - maize, rice, soybeans, and wheat. Further, in some countries (e.g., Algeria, Morocco, Syria, Tunisia, and Yemen) the total volume of blue water required for yield gap closure would exceed sustainable levels of freshwater consumption (i.e., 40% of total renewable surface and groundwater resources).

  14. U.S. Geological Survey Gap Analysis Program

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Gap Analysis Program (GAP) is an element of the U.S. Geological Survey (USGS). GAP helps to implement the Department of Interior?s goals of inventory,...

  15. Increasing gap junctional coupling: a tool for dissecting the role of gap junctions.

    Science.gov (United States)

    Axelsen, Lene Nygaard; Haugan, Ketil; Stahlhut, Martin; Kjølbye, Anne-Louise; Hennan, James K; Holstein-Rathlou, Niels-Henrik; Petersen, Jørgen Søberg; Nielsen, Morten Schak

    2007-03-01

    Much of our current knowledge about the physiological and pathophysiological role of gap junctions is based on experiments where coupling has been reduced by either chemical agents or genetic modification. This has brought evidence that gap junctions are important in many physiological processes. In a number of cases, gap junctions have been implicated in the initiation and progress of disease, and experimental uncoupling has been used to investigate the exact role of coupling. The inverse approach, i.e., to increase coupling, has become possible in recent years and represents a new way of testing the role of gap junctions. The aim of this review is to summarize the current knowledge obtained with agents that selectively increase gap junctional intercellular coupling. Two approaches will be reviewed: increasing coupling by the use of antiarrhythmic peptide and its synthetic analogs and by interfering with the gating of gap junctional channels.

  16. Ocean Mixed Layer Response to Gap Wind Scenarios

    Science.gov (United States)

    2006-12-01

    LAYER ........5 B. GAP WINDS AND GAP FLOW .............................7 III MODELS AND DATA SOURCES ................................13 A. COUPLED...atmospheric and the oceanic boundary layer during gap flow conditions were made by a research aircraft with dropsonde and AXBTs. This dataset gave us the...Polar Regions (http://oceanworld.tamu.edu/resources/ocng textbook , last visited 26 October 2006). B. GAP WINDS AND GAP FLOW Gap winds are low

  17. Horizontal roof gap of backfill hydraulic support

    Institute of Scientific and Technical Information of China (English)

    张强; 张吉雄; 邰阳; 方坤; 殷伟

    2015-01-01

    For the backfill hydraulic support as the key equipment for achieving integration of backfilling and coal mining simultaneously in the practical process, its characteristics will directly influence the backfill body’s compression ratio. Horizontal roof gap, as a key parameter of backfilling characteristics, may impact the backfilling effect from the aspects of control of roof subsidence in advance, support stress, backfilling process and the support design. Firstly, the reason why horizontal roof gap exists was analyzed and its definition, causes and connotation were introduced, then adopting the Pro/E 3D simulation software, three typical 3D entity models of backfill hydraulic supports were built, based on the influence of horizontal roof gap on backfilling effect, and influence rules of four factors, i.e. support height, suspension height, suspension angle and tamping angle, were emphatically analyzed on horizontal roof gap. The results indicate that, the four factors all have significant impacts on horizontal roof gap, but show differences in influence trend and degree, showing negative linear correlation, positive linear correlation, positive semi-parabolic correlation and negative semi-parabolic correlation, respectively. Four legs type is the most adaptive to the four factors, while six legs (II) type has the poorest adaptability, and the horizontal roof gap is small under large support height, small suspension height, small suspension angle and large tamping angle situation. By means of optimizing structure components and their positional relation and suspension height of backfill scrape conveyor in the process of support design and through controlling working face deployment, roof subsidence in advance, mining height and backfilling during engineering application, the horizontal roof gap is optimized. The research results can be served as theoretical basis for support design and guidance for backfill support to have better performance in backfilling.

  18. Galaxy Formation

    DEFF Research Database (Denmark)

    Sparre, Martin

    galaxies form stars throughout the history of the Universe, and secondly it is shown that observations of gamma-ray bursts (GRBs) can be used to probe galaxies with active star formation in the early Universe. A conclusion from the hydrodynamical simulations is that the galaxies from the stateof......-the-art cosmological simulation, Illustris, follow a tight relation between star formation rate and stellar mass. This relation agrees well with the observed relation at a redshift of z = 0 and z = 4, but at intermediate redshifts of z ' 2 the normalisation is lower than in real observations. This is highlighted...... of GRB host galaxies is affected by the fact that GRBs appear mainly to happen in low-metallicity galaxies. Solving this problem will make it possible to derive the total cosmic star formation rate more reliably from number counts of GRBs....

  19. Band gap opening of monolayer and bilayer graphene doped with aluminium, silicon, phosphorus, and sulfur

    Science.gov (United States)

    Denis, Pablo A.

    2010-06-01

    The chemical doping of monolayer and bilayer graphene with aluminium, silicon, phosphorus and sulfur was investigated. Si-doped graphene has the lowest formation energy although it is semimetallic. P-doped graphene has a magnetic moment of 1 μ B and for 3 at.% of doping the band gap is 0.67 eV. Al-doped graphene is very unstable but it is an attractive material because it is metallic. To reduce the formation energies of the substitutional defects we investigated the formation of interlayer bonds in bilayer graphene. Phosphorus forms the strongest bonds between layers giving particular stability to this material. P-doped bilayer graphene has a gap of 0.43 eV but it is has no magnetic moment.

  20. STELLAR MASS-GAP AS A PROBE OF HALO ASSEMBLY HISTORY AND CONCENTRATION: YOUTH HIDDEN AMONG OLD FOSSILS

    Energy Technology Data Exchange (ETDEWEB)

    Deason, A. J.; Conroy, C. [Department of Astronomy and Astrophysics, University of California Santa Cruz, Santa Cruz, CA 95064 (United States); Wetzel, A. R. [Department of Astronomy, Yale University, New Haven, CT 06520 (United States); Tinker, J. L., E-mail: alis@ucolick.org [Center for Cosmology and Particle Physics, Department of Physics, New York University, New York, NY 10013 (United States)

    2013-11-10

    We investigate the use of the halo mass-gap statistic—defined as the logarithmic difference in mass between the host halo and its most massive satellite subhalo—as a probe of halo age and concentration. A cosmological N-body simulation is used to study N ∼ 25, 000 group/cluster-sized halos in the mass range 10{sup 12.5} < M{sub halo}/M{sub ☉} < 10{sup 14.5}. In agreement with previous work, we find that halo mass-gap is related to halo formation time and concentration. On average, older and more highly concentrated halos have larger halo mass-gaps, and this trend is stronger than the mass-concentration relation over a similar dynamic range. However, there is a large amount of scatter owing to the transitory nature of the satellite subhalo population, which limits the use of the halo mass-gap statistic on an object-by-object basis. For example, we find that 20% of very large halo mass-gap systems (akin to {sup f}ossil groups{sup )} are young and have likely experienced a recent merger between a massive satellite subhalo and the central subhalo. We relate halo mass-gap to the observable stellar mass-gap via abundance matching. Using a galaxy group catalog constructed from the Sloan Digital Sky Survey Data Release 7, we find that the star formation and structural properties of galaxies at fixed mass show no trend with stellar mass-gap. This is despite a variation in halo age of ≈2.5 Gyr over ≈1.2 dex in stellar mass-gap. Thus, we find no evidence to suggest that the halo formation history significantly affects galaxy properties.

  1. The origin of multiple superconducting gaps in MgB2.

    Science.gov (United States)

    Souma, S; Machida, Y; Sato, T; Takahashi, T; Matsui, H; Wang, S-C; Ding, H; Kaminski, A; Campuzano, J C; Sasaki, S; Kadowaki, K

    2003-05-01

    Magnesium diboride, MgB2, has the highest transition temperature (T(c) = 39 K) of the known metallic superconductors. Whether the anomalously high T(c) can be described within the conventional BCS (Bardeen-Cooper-Schrieffer) framework has been debated. The key to understanding superconductivity lies with the 'superconducting energy gap' associated with the formation of the superconducting pairs. Recently, the existence of two kinds of superconducting gaps in MgB2 has been suggested by several experiments; this is in contrast to both conventional and high-T(c) superconductors. A clear demonstration of two gaps has not yet been made because the previous experiments lacked the ability to resolve the momentum of the superconducting electrons. Here we report direct experimental evidence for the two-band superconductivity in MgB2, by separately observing the superconducting gaps of the sigma and pi bands (as well as a surface band). The gaps have distinctly different sizes, which unambiguously establishes MgB2 as a two-gap superconductor.

  2. Gap winds and their effects on regional oceanography Part I: Cross Sound, Alaska

    Science.gov (United States)

    Ladd, Carol; Cheng, Wei

    2016-10-01

    Gap-wind events flowing from Cross Sound in the eastern Gulf of Alaska (GOA) were examined using QuikSCAT wind data. The average duration of an event is 3.6 days with the longest event recorded in the QuikSCAT dataset being 12 days. Daily offshore directed winds with speeds >10 m s-1 are more common during the winter months (October-March), averaging 20.0 days per year, and less common during the summer (April - September), averaging 2.8 days per year. Interannual variability in the frequency of gap-wind events is correlated with El Niño. During gap-wind events, the spatial scales of high off-shore directed winds (>10 m s-1) reach almost 200 km off-shore and 225 km along the shelf break, suggesting that the winds directly influence both the shelf (20-65 km wide) and the off-shore waters. A model experiment suggests that a gap-wind event can result in eddy formation and changes in circulation and water properties. Increased entrainment of water from below the mixed layer due to the gap-wind event implies that mixed-layer nitrate concentrations could increase on the order of 5-10 μmole/l, potentially enhancing primary production in the region. An accompanying paper discusses part II of our study (Ladd et al., 2016) focusing on gap-wind events in the western GOA around Kodiak Island.

  3. Effect of interfacial lattice mismatch on bulk carrier concentration and band gap of InN

    Energy Technology Data Exchange (ETDEWEB)

    Kuyyalil, Jithesh [FOTON, UMR 6082, INSA, F-35708 Rennes (France); Tangi, Malleswararao; Shivaprasad, S. M. [Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore-560064 (India)

    2012-10-15

    The issue of ambiguous values of the band gap (0.6 to 2 eV) of InN thin film in literature has been addressed by a careful experiment. We have grown wurtzite InN films by PA-MBE simultaneously on differently modified c-plane sapphire substrates and characterized by complementary structural and chemical probes. Our studies discount Mie resonances caused by metallic In segregation at grain boundaries as the reason for low band gap values ( Almost-Equal-To 0.6 eV) and also the formation of Indium oxides and oxynitrides as the cause for high band gap value ( Almost-Equal-To 2.0 eV). It is observed that polycrystallinity arising from azimuthal miss-orientation of c-oriented wurtzite InN crystals increases the carrier concentration and the band gap values. We have reviewed the band gap, carrier concentration, and effective mass of InN in literature and our own measurements, which show that the Moss-Burstein relation with a non-parabolic conduction band accounts for the observed variation of band gap with carrier concentration.

  4. Origins of electronic band gap reduction in Cr/N codoped TiO2.

    Science.gov (United States)

    Parks Cheney, C; Vilmercati, P; Martin, E W; Chiodi, M; Gavioli, L; Regmi, M; Eres, G; Callcott, T A; Weitering, H H; Mannella, N

    2014-01-24

    Recent studies indicated that noncompensated cation-anion codoping of wide-band-gap oxide semiconductors such as anatase TiO2 significantly reduces the optical band gap and thus strongly enhances the absorption of visible light [W. Zhu et al., Phys. Rev. Lett. 103, 226401 (2009)]. We used soft x-ray spectroscopy to fully determine the location and nature of the impurity levels responsible for the extraordinarily large (∼1 eV) band gap reduction of noncompensated codoped rutile TiO2. It is shown that Cr/N codoping strongly enhances the substitutional N content, compared to single element doping. The band gap reduction is due to the formation of Cr 3d3 levels in the lower half of the gap while the conduction band minimum is comprised of localized Cr 3d and delocalized N 2p states. Band gap reduction and carrier delocalization are critical elements for efficient light-to-current conversion in oxide semiconductors. These findings thus raise the prospect of using codoped oxide semiconductors with specifically engineered electronic properties in a variety of photovoltaic and photocatalytic applications.

  5. Novel Approach for Modeling of Nonuniform Slag Layers and Air Gap in Continuous Casting Mold

    Science.gov (United States)

    Wang, Xudong; Kong, Lingwei; Yao, Man; Zhang, Xiaobing

    2017-02-01

    Various kinds of surface defects on the continuous casting slab usually originate from nonuniform heat transfer and mechanical behavior, especially during the initial solidification inside the mold. In this article, a model-coupled inverse heat transfer problem incorporating the effect of slag layers and air gap is developed to study the nonuniform distribution of liquid slag, solid slag, and air gap layers. The model considers not only the formation and evolution of slag layers and air gap but also the temperatures in the mold copper as measured by thermocouples. The simulation results from the model and the measured temperatures from experiments are shown to be in good agreement with each other. At the casting speed of 0.65 m/min, the liquid slag film disappears and transforms into solid slag entirely at about 400 mm away from meniscus, and an air gap begins to form. Until the mold exit, the maximum thickness of the solid slag layer and air gap gradually increases to 1.34 and 0.056 mm, respectively. The results illustrate that the magnitude and nonuniform distribution of the slag layers and air gap along the cross direction, correlating with heat flux between the shell and mold, eventually determine the temperature profiles of the mold hot face and slab surface. The proposed model may provide a convenient approach for analyzing nonuniform heat transfer and mechanical behaviors between the mold and slab in the real casting process.

  6. Robust band gap and half-metallicity in graphene with triangular perforations

    Science.gov (United States)

    Gregersen, Søren Schou; Power, Stephen R.; Jauho, Antti-Pekka

    2016-06-01

    Ideal graphene antidot lattices are predicted to show promising band gap behavior (i.e., EG≃500 meV) under carefully specified conditions. However, for the structures studied so far this behavior is critically dependent on superlattice geometry and is not robust against experimentally realistic disorders. Here we study a rectangular array of triangular antidots with zigzag edge geometries and show that their band gap behavior qualitatively differs from the standard behavior which is exhibited, e.g., by rectangular arrays of armchair-edged triangles. In the spin unpolarized case, zigzag-edged antidots give rise to large band gaps compared to armchair-edged antidots, irrespective of the rules which govern the existence of gaps in armchair-edged antidot lattices. In addition the zigzag-edged antidots appear more robust than armchair-edged antidots in the presence of geometrical disorder. The inclusion of spin polarization within a mean-field Hubbard approach gives rise to a large overall magnetic moment at each antidot due to the sublattice imbalance imposed by the triangular geometry. Half-metallic behavior arises from the formation of spin-split dispersive states near the Fermi energy, reducing the band gaps compared to the unpolarized case. This behavior is also found to be robust in the presence of disorder. Our results highlight the possibilities of using triangular perforations in graphene to open electronic band gaps in systems with experimentally realistic levels of disorder, and furthermore, of exploiting the strong spin dependence of the system for spintronic applications.

  7. The effect of repeated preheating of dimethacrylate and silorane-based composite resins on marginal gap of class V restorations

    Directory of Open Access Journals (Sweden)

    Parnian Alizadeh Oskoee

    2017-03-01

    Full Text Available Background. One of the problems with composite resin restorations is gap formation at resin‒tooth interface. The present study evaluated the effect of preheating cycles of silorane- and dimethacrylate-based composite resins on gap formation at the gingival margins of Class V restorations. Methods. In this in vitro study, standard Class V cavities were prepared on the buccal surfaces of 48 bovine incisors. For restorative procedure, the samples were randomly divided into 2 groups based on the type of composite resin (group 1: di-methacrylate composite [Filtek Z250]; group 2: silorane composite [Filtek P90] and each group was randomly divided into 2 subgroups based on the composite temperature (A: room temperature; B: after 40 preheating cycles up to 55°C. Marginal gaps were measured using a stereomicroscope at ×40 and analyzed with two-way ANOVA. Inter- and intra-group comparisons were analyzed with post-hoc Tukey tests. Significance level was defined at P < 0.05. Results. The maximum and minimum gaps were detected in groups 1-A and 2-B, respectively. The effects of composite resin type, preheating and interactive effect of these variables on gap formation were significant (P<0.001. Post-hoc Tukey tests showed greater gap in dimethacrylate compared to silorane composite resins (P< 0.001. In each group, gap values were greater in composite resins at room temperature compared to composite resins after 40 preheating cycles (P<0.001. Conclusion. Gap formation at the gingival margins of Class V cavities decreased due to preheating of both composite re-sins. Preheating of silorane-based composites can result in the best marginal adaptation.

  8. Tire Crumb Research Study Literature Review / Gap ...

    Science.gov (United States)

    In order to more fully understand data gaps in human exposure and toxicity to tire crumb materials, ATSDR, CPSC and EPA undertook a collaborative effort in the form of a scientific literature review and subsequent gaps analysis. The first objective of the Literature Review and Gap Analysis (LRGA) collaboration was to identify the existing body of literature related specifically to human exposure to tire crumb materials through the use of synthetic turf athletic fields and playgrounds. The second objective was to characterize and summarize the relevant data from the scientific literature. The final objective was to review the summary information and identify data gaps to build on the current understanding of the state-of-the-science and inform the development of specific research efforts that would be most impactful in the near-term. Because of the need for additional information, the U.S. Environmental Protection Agency (EPA), the Centers for Disease Control and Prevention/Agency for Toxic Substances and Disease Registry (ATSDR), and the U.S. Consumer Product Safety Commission (CPSC) launched a multi-agency action plan to study key environmental human health questions. The Federal Research Action Plan includes numerous activities, including research studies (U.S. EPA, 2016). A key objective of the Action Plan is to identify key knowledge gaps.

  9. Comparative study of INPIStron and spark gap

    Science.gov (United States)

    Han, Kwang S.; Lee, Ja H.

    1993-01-01

    An inverse pinch plasma switch, INPIStron, was studied in comparison to a conventional spark gap. The INPIStron is under development for high power switching applications. The INPIStron has an inverse pinch dynamics, opposed to Z-pinch dynamics in the spark gap. The electrical, plasma dynamics and radiative properties of the closing plasmas have been studied. Recently the high-voltage pulse transfer capabilities or both the INPIStron and the spark gap were also compared. The INPIStron with a low impedance Z = 9 ohms transfers 87 percent of an input pulse with a halfwidth of 2 mu s. For the same input pulse the spark gap of Z = 100 ohms transfers 68 percent. Fast framing and streak photography, taken with an TRW image converter camera, was used to observe the discharge uniformity and closing plasma speed in both switches. In order to assess the effects of closing plasmas on erosion of electrode material, emission spectra of two switches were studied with a spectrometer-optical multi channel analyzer (OMA) system. The typical emission spectra of the closing plasmas in the INPIStron and the spark gap showed that there were comparatively weak carbon line emission in 658.7 nm and copper (electrode material) line emissions in the INPIStron, indicating low erosion of materials in the INPIStron.

  10. Gap junctions: structure and function (Review).

    Science.gov (United States)

    Evans, W Howard; Martin, Patricia E M

    2002-01-01

    Gap junctions are plasma membrane spatial microdomains constructed of assemblies of channel proteins called connexins in vertebrates and innexins in invertebrates. The channels provide direct intercellular communication pathways allowing rapid exchange of ions and metabolites up to approximately 1 kD in size. Approximately 20 connexins are identified in the human or mouse genome, and orthologues are increasingly characterized in other vertebrates. Most cell types express multiple connexin isoforms, making likely the construction of a spectrum of heteromeric hemichannels and heterotypic gap junctions that could provide a structural basis for the charge and size selectivity of these intercellular channels. The precise nature of the potential signalling information traversing junctions in physiologically defined situations remains elusive, but extensive progress has been made in elucidating how connexins are assembled into gap junctions. Also, participation of gap junction hemichannels in the propagation of calcium waves via an extracellular purinergic pathway is emerging. Connexin mutations have been identified in a number of genetically inherited channel communication-opathies. These are detected in connexin 32 in Charcot Marie Tooth-X linked disease, in connexins 26 and 30 in deafness and skin diseases, and in connexins 46 and 50 in hereditary cataracts. Biochemical approaches indicate that many of the mutated connexins are mistargeted to gap junctions and/or fail to oligomerize correctly into hemichannels. Genetic ablation approaches are helping to map out a connexin code and point to specific connexins being required for cell growth and differentiation as well as underwriting basic intercellular communication.

  11. Two Modes of Partially Screened Gap

    CERN Document Server

    Szary, Andrzej; Gil, Janusz

    2014-01-01

    The analysis of X-ray observations suggest an ultrastrong ($B\\gtrsim 10^{14} \\,{\\rm G}$) surface magnetic field at the polar cap of pulsars (Szary, 2013). On the other hand, the temperature of the polar caps is about a few millions Kelvin. Based on these two facts we use the Partially Screened Gap (PSG) model to describe the Inner Acceleration Region (IAR). The PSG model assumes that the temperature of the actual polar cap is equal to the so-called critical value, i.e. the temperature at which the outflow of thermal ions from the surface screens the gap completely. We have found that, depending on the conditions above the polar cap, the generation of high energetic photons in IAR can be caused either by Curvature Radiation (CR) or by Inverse Compton Scattering (ICS). Completely different properties of both processes result in two different scenarios of breaking the acceleration gap: the so-called PSG-off mode for the gap dominated by CR and the PSG-on mode for the gap dominated by ICS. The existence of two di...

  12. Nonspecific effects of gap paradigm on swallowing.

    Science.gov (United States)

    Yoneda, Masaki; Saitoh, Kazuya

    2017-02-01

    Analogous to the gap paradigm in experiments for saccadic eye movements with very short reaction times, we hypothesized that the initiation of oropharyngeal swallowing movements guided by visual cues are encouraged under experimental conditions using a similar gap paradigm. A red visual cue indicating to hold a bolus in the mouth and a blue one indicating to swallow the bolus were sequentially provided on a computer display to 11 healthy participants. The gap period between these cues varied from 0 to 800ms. Swallowing kinetics and kinematics were recorded using surface electromyography and a laser displacement sensor, respectively. In comparison with the no-gap paradigm, the delay from the onset of muscle activities to initiation of movement significantly decreased with a 100- (pparadigm of 100-200ms. Wrist flexion was boosted in a similar manner. Thus, the gap effect may be a generalized warning effect. Our findings might provide insights into the contribution of the basal ganglia to volitional swallowing. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Localized electronic states and the superconducting gap in Bi 2Sr 2CaCu 2O 8+y

    Science.gov (United States)

    Quitmann, C.; Ma, Jian; Kelley, R. J.; Margaritondo, G.; Onellion, M.

    1994-12-01

    Angle-resolved photoemission data taken on some Bi 2Sr 2CaCu 2O 8+y single crystals exhibit the formation of a superconducting gap in the absence of a quasiparticle normal state band. We observe the opening of the superconducting gap in the same regions of the Brillouin zone for which it is observed for samples that do exhibit a quasiparticle normal state. The absence of a dispersing quasiparticle normal state indicates that the normal state electronic states in these samples are almost localized in real space. Our data suggest that two types of carriers can coexist, and contribute to forming a superconducting gap, in these materials.

  14. The effect of the shape of gaps on microenvironmental conditions and seedling recruitment in Molinietum caeruleae meadows

    Directory of Open Access Journals (Sweden)

    Kinga Kostrakiewicz-Gierałt

    2015-07-01

    Full Text Available Cessation of the management of semi-natural habitats such as grasslands and meadows contributes to secondary succession and encroachment of native and alien tall-growing perennials, large tussock grasses, shrubs, and trees. Thus, the formation of gaps in the plant canopy and litter, enabling seedling recruitment, appears to be a very effective method for the restoration of several plant communities. The main objective of the research was to assess the effect of the shape of openings on microenvironmental conditions and seedling recruitment in Molinietum caeruleae patches in various habitat conditions. In all study patches, circular and linear openings, comparable in area, were randomly created through the removal of plant canopy and litter layer. The circular gaps presented greater light availability and lower soil humidity than linear openings, while soil temperature within differently shaped openings was similar. Regardless of differences in microenvironmental conditions, the total number of seedlings in differently shaped gaps did not vary considerably. Three plant categories were found: (i those recruited mostly in circular openings, (ii those recruited mostly in linear gaps, (iii those colonizing circular and linear gaps similarly. The colonizers of circular gaps represented various synecological groups (ruderal, grasslands and meadows, young tree communities and diverse life forms (therophytes, hemicryptophytes, chamaephytes, phanerophytes, while the colonizers of linear gaps were meadow and grassland hemicryptophytes. The formation of linear openings contributes to increases in the abundance of meadow taxa, while the creation of circular openings may have a negative effect, contributing to the promotion of the secondary succession process.

  15. Hippocampal formation

    NARCIS (Netherlands)

    Cappaert, N.L.M.; van Strien, N.M.; Witter, M.P.; Paxinos, G.

    2015-01-01

    The hippocampal formation and parahippocampal region are prominent components of the rat nervous system and play a crucial role in learning, memory, and spatial navigation. Many new details regarding the entorhinal cortex have been discovered since the previous edition, and the growing interest in t

  16. Canopy gap edge determination and the importance of gap edges for plant diversity

    Directory of Open Access Journals (Sweden)

    D. Salvador-Van Eysenrode

    2002-01-01

    Full Text Available Canopy gaps, i.e. openings in the forest cover caused by the fall of structural elements, are considered to be important for the maintenance of diversity and for the forest cycle. A gap can be considered as a young forest patch in the forest matrix, composed of interior surrounded by an edge, both enclosed by a perimeter. Much of the attention has been focused on the gap interior. However, at gap edges the spectrum of regeneration opportunities for plants may be larger than in the interior. Although definitions of gap are still discussed, any definition can describe it in an acceptable way, if justified, but defining edges is complicated and appropriate descriptors should be used. A method to determine gap interior and edge, using light as a descriptor, is presented with an example of gaps from a beech forest (Fagus sylvatica in Belgium. Also, the relevance and implications of gap edges for plant diversity and calculation of forest turnover is discussed.

  17. Closing the Gap: An Overview. The Achievement Gap: An Overview. Info Brief. Number 44

    Science.gov (United States)

    Poliakoff, Anne Rogers

    2006-01-01

    Persistent gaps between the academic achievements of different groups of children are thoroughly documented by the U.S. National Assessment of Educational Progress and other statistical analyses of state assessments, grades, course selection, and dropout rates. Despite improvements in some years, the gap endures as a consistent and disturbing…

  18. Widening the Gap: Pre-University Gap Years and the "Economy of Experience"

    Science.gov (United States)

    Heath, Sue

    2007-01-01

    Embarking upon a pre-university gap year is an increasingly popular option among British students. Drawing on Brown et al.'s work on positional conflict theory and the increased importance of the "economy of experience", this paper seeks to explore this growing popularity and argues that the gap year's enhanced profile raises important…

  19. Close the Gap : a study on the regulation of Connexin43 gap junctional communication

    NARCIS (Netherlands)

    Zeijl, Leonie van

    2009-01-01

    Gap junctions are groups of transmembrane channels that connect the cytoplasms of adjacent cells to mediate the diffusion of small molecules, such as ions, metabolites, second messengers and small peptides. The building blocks of gap junctions are connexin proteins. The most ubiquitous and best stu

  20. Focusing on the Participation and Engagement Gap: A Case Study on Closing the Achievement Gap

    Science.gov (United States)

    Fisher, Douglas; Frey, Nancy; Lapp, Diane

    2011-01-01

    In this case study, we focus on 2 variables often neglected in conversations about closing the achievement gap. Most recommendations for closing the achievement gap center on extending learning time, including afterschool programs, extended year programs, and supplemental instruction. Our school focused on attendance and student engagement in our…

  1. Widening the Gap: Pre-University Gap Years and the "Economy of Experience"

    Science.gov (United States)

    Heath, Sue

    2007-01-01

    Embarking upon a pre-university gap year is an increasingly popular option among British students. Drawing on Brown et al.'s work on positional conflict theory and the increased importance of the "economy of experience", this paper seeks to explore this growing popularity and argues that the gap year's enhanced profile raises important…

  2. Mean field magnetization of gapped anisotropic multiplet

    Science.gov (United States)

    Paixão, L. S.; Reis, M. S.

    2014-06-01

    Some materials have a large gap between the ground and first excited states. At temperatures smaller than the gap value, the thermodynamic properties of such materials are mainly ruled by the ground state. It is also common to find materials with magnetocrystalline anisotropy, which arises due to interatomic interactions. The present paper uses a classical approach to deal large angular momenta in such materials. Based on analytical expressions for the thermodynamics of paramagnetic gapped anisotropic multiplets, we use mean field theory to study the influence of the anisotropy upon the properties of interacting systems. We also use Landau theory to determine the influence of the anisotropy in first and second order phase transitions. It is found that the anisotropy increases the critical temperature, and enlarges the hysteresis of first order transitions. We present analytical expressions for the quantities analyzed.

  3. Gap junction diseases of the skin.

    Science.gov (United States)

    van Steensel, M A M

    2004-11-15

    Gap junctions are intercellular channels that allow the passage of water, ions, and small molecules. They are involved in quick, short-range messaging between cells and are found in skin, nervous tissue, heart, and muscle. An increasing number of hereditary skin disorders appear to be caused by mutations in one of the genes coding for the constituent proteins of gap junctions, known as connexins. In this review, the currently known connexin disorders that feature skin abnormalities are described: keratitis-ichthyosis deafness syndrome, erythrokeratoderma variabilis, Vohwinkel's syndrome, and a novel disorder called hypotrichosis-deafness syndrome. What is known about the pathogenesis of these disorders is discussed and related to gap junction physiology. (c) 2004 Wiley-Liss, Inc.

  4. Sizable band gap in organometallic topological insulator

    Science.gov (United States)

    Derakhshan, V.; Ketabi, S. A.

    2017-01-01

    Based on first principle calculation when Ceperley-Alder and Perdew-Burke-Ernzerh type exchange-correlation energy functional were adopted to LSDA and GGA calculation, electronic properties of organometallic honeycomb lattice as a two-dimensional topological insulator was calculated. In the presence of spin-orbit interaction bulk band gap of organometallic lattice with heavy metals such as Au, Hg, Pt and Tl atoms were investigated. Our results show that the organometallic topological insulator which is made of Mercury atom shows the wide bulk band gap of about ∼120 meV. Moreover, by fitting the conduction and valence bands to the band-structure which are produced by Density Functional Theory, spin-orbit interaction parameters were extracted. Based on calculated parameters, gapless edge states within bulk insulating gap are indeed found for finite width strip of two-dimensional organometallic topological insulators.

  5. Closing the technological gap in Latin America

    Energy Technology Data Exchange (ETDEWEB)

    Street, J.H.; James, D.D.

    1978-06-01

    The 19 oil-importing countries of Latin America were severely affected by the 1973 oil embargo and price increases, which revealed a widening technological gap that has made stability and economic growth difficult for these countries. Unstable price levels and massive inflation have produced unprecedented balance-of-payments deficits. The area's technological gap leaves it unprepared to produce adequate food supplies or to make major resource substitutions. Internal weaknesses are evident in the educational and research biases of South America that have limited the progress of universities and research institutes. New policies are needed to promote viable science and technology by setting priorities and expanding indigenous research programs. Several case studies of indigenous innovation and adaptation are noted to illustrate the potential for closing the technological gap in a peaceful, constructive way. 44 references.

  6. Computational fluid dynamics of gap flow in a biocentrifugal blood pump.

    Science.gov (United States)

    Chua, Leok Poh; Song, Guoliang; Yu, Simon Ching Man; Lim, Tau Meng

    2005-08-01

    The centrifugal blood pump with a magnetically suspended impeller has shown its superiority as compared to other artificial heart pumps. However, there is still insufficient understanding of fluid mechanics related issues in the clearance gap. The design nature of the pump requires sufficient washout in the clearance between the impeller and the stationary pump housing inner surface. In this study, numerical simulations were carried out to investigate the flow fields in the gap of the Kyoto-NTN centrifugal blood pump. The flow patterns in the gap region of the blood pump were presented and regions of high and low velocity were identified. It was found that the radial velocity of the blood in the gap was closely related to the pressure distribution at the exit of the impeller, both the highest pressure gradient and the highest radial velocity in the gap occurred at an angular position of 170 degrees . The mass flow rate in the gap was estimated to be 25.2% of the pump outflow, which is close to the measurement results of a five times enlarged test pump. The wall shear stresses on the gap surface were found to be over 21 Pa and below 300 Pa, which is correspondingly higher than the threshold of thrombi formation and is lower than the shearing threshold of red blood cells. Comparison of the 1 : 1 simulation model with the measurement results on a five times enlarged test pump indicates that there are some differences in the resulting radial velocity distributions in the gap and thus the washout mechanism. Two symmetrical high washout regions at both the cutwater and splitter plate were observed in the simulation instead of a single washout region at the splitter plate found in the experimental study. This may be due to the scaling effect of the enlarged test pump; also the medium used in the experiment is different from the simulation.

  7. Review and bibliometric analysis of published literature citing data produced by the Gap Analysis Program (GAP)

    Science.gov (United States)

    Ratz, Joan M.; Conk, Shannon J.

    2014-01-01

    The Gap Analysis Program (GAP) of the U.S. Geological Survey (USGS) produces geospatial datasets providing information on land cover, predicted species distributions, stewardship (ownership and conservation status), and an analysis dataset which synthesizes the other three datasets. The intent in providing these datasets is to support the conservation of biodiversity. The datasets are made available at no cost. The initial datasets were created at the state level. More recent datasets have been assembled at regional and national levels. GAP entered an agreement with the Policy Analysis and Science Assistance branch of the USGS to conduct an evaluation to describe the effect that using GAP data has on those who utilize the datasets (GAP users). The evaluation project included multiple components: a discussion regarding use of GAP data conducted with participants at a GAP conference, a literature review of publications that cited use of GAP data, and a survey of GAP users. The findings of the published literature search were used to identify topics to include on the survey. This report summarizes the literature search, the characteristics of the resulting set of publications, the emergent themes from statements made regarding GAP data, and a bibliometric analysis of the publications. We cannot claim that this list includes all publications that have used GAP data. Given the time lapse that is common in the publishing process, more recent datasets may be cited less frequently in this list of publications. Reports or products that used GAP data may be produced but never published in print or released online. In that case, our search strategies would not have located those reports. Authors may have used GAP data but failed to cite it in such a way that the search strategies we used would have located those publications. These are common issues when using a literature search as part of an evaluation project. Although the final list of publications we identified is not

  8. GASP: Gapped Ancestral Sequence Prediction for proteins

    Directory of Open Access Journals (Sweden)

    Shields Denis C

    2004-09-01

    Full Text Available Abstract Background The prediction of ancestral protein sequences from multiple sequence alignments is useful for many bioinformatics analyses. Predicting ancestral sequences is not a simple procedure and relies on accurate alignments and phylogenies. Several algorithms exist based on Maximum Parsimony or Maximum Likelihood methods but many current implementations are unable to process residues with gaps, which may represent insertion/deletion (indel events or sequence fragments. Results Here we present a new algorithm, GASP (Gapped Ancestral Sequence Prediction, for predicting ancestral sequences from phylogenetic trees and the corresponding multiple sequence alignments. Alignments may be of any size and contain gaps. GASP first assigns the positions of gaps in the phylogeny before using a likelihood-based approach centred on amino acid substitution matrices to assign ancestral amino acids. Important outgroup information is used by first working down from the tips of the tree to the root, using descendant data only to assign probabilities, and then working back up from the root to the tips using descendant and outgroup data to make predictions. GASP was tested on a number of simulated datasets based on real phylogenies. Prediction accuracy for ungapped data was similar to three alternative algorithms tested, with GASP performing better in some cases and worse in others. Adding simple insertions and deletions to the simulated data did not have a detrimental effect on GASP accuracy. Conclusions GASP (Gapped Ancestral Sequence Prediction will predict ancestral sequences from multiple protein alignments of any size. Although not as accurate in all cases as some of the more sophisticated maximum likelihood approaches, it can process a wide range of input phylogenies and will predict ancestral sequences for gapped and ungapped residues alike.

  9. GASP: Gapped Ancestral Sequence Prediction for proteins.

    Science.gov (United States)

    Edwards, Richard J; Shields, Denis C

    2004-09-06

    The prediction of ancestral protein sequences from multiple sequence alignments is useful for many bioinformatics analyses. Predicting ancestral sequences is not a simple procedure and relies on accurate alignments and phylogenies. Several algorithms exist based on Maximum Parsimony or Maximum Likelihood methods but many current implementations are unable to process residues with gaps, which may represent insertion/deletion (indel) events or sequence fragments. Here we present a new algorithm, GASP (Gapped Ancestral Sequence Prediction), for predicting ancestral sequences from phylogenetic trees and the corresponding multiple sequence alignments. Alignments may be of any size and contain gaps. GASP first assigns the positions of gaps in the phylogeny before using a likelihood-based approach centred on amino acid substitution matrices to assign ancestral amino acids. Important outgroup information is used by first working down from the tips of the tree to the root, using descendant data only to assign probabilities, and then working back up from the root to the tips using descendant and outgroup data to make predictions. GASP was tested on a number of simulated datasets based on real phylogenies. Prediction accuracy for ungapped data was similar to three alternative algorithms tested, with GASP performing better in some cases and worse in others. Adding simple insertions and deletions to the simulated data did not have a detrimental effect on GASP accuracy. GASP (Gapped Ancestral Sequence Prediction) will predict ancestral sequences from multiple protein alignments of any size. Although not as accurate in all cases as some of the more sophisticated maximum likelihood approaches, it can process a wide range of input phylogenies and will predict ancestral sequences for gapped and ungapped residues alike.

  10. EVA Systems Technology Gaps and Priorities 2017

    Science.gov (United States)

    Johnson, Brian J.; Buffington, Jesse A.

    2017-01-01

    Performance of Extra-Vehicular Activities (EVA) has been and will continue to be a critical capability for human space flight. Human exploration missions beyond LEO will require EVA capability for either contingency or nominal activities to support mission objectives and reduce mission risk. EVA systems encompass a wide array of products across pressure suits, life support systems, EVA tools and unique spacecraft interface hardware (i.e. EVA Translation Paths and EVA Worksites). In a fiscally limited environment with evolving transportation and habitation options, it is paramount that the EVA community's strategic planning and architecture integration products be reviewed and vetted for traceability between the mission needs far into the future to the known technology and knowledge gaps to the current investments across EVA systems. To ascertain EVA technology and knowledge gaps many things need to be brought together, assessed and analyzed. This includes an understanding of the destination environments, various mission concept of operations, current state of the art of EVA systems, EVA operational lessons learned, and reference advanced capabilities. A combined assessment of these inputs should result in well-defined list of gaps. This list can then be prioritized depending on the mission need dates and time scale of the technology or knowledge gap closure plan. This paper will summarize the current state of EVA related technology and knowledge gaps derived from NASA's Exploration EVA Reference Architecture and Operations Concept products. By linking these products and articulating NASA's approach to strategic development for EVA across all credible destinations an EVA could be done in, the identification of these gaps is then used to illustrate the tactical and strategic planning for the EVA technology development portfolio. Finally, this paper illustrates the various "touch points" with other human exploration risk identification areas including human health and

  11. Increasing gap junctional coupling: a tool for dissecting the role of gap junctions

    DEFF Research Database (Denmark)

    Axelsen, Lene Nygaard; Haugan, Ketil; Stahlhut, Martin;

    2007-01-01

    . In a number of cases, gap junctions have been implicated in the initiation and progress of disease, and experimental uncoupling has been used to investigate the exact role of coupling. The inverse approach, i.e., to increase coupling, has become possible in recent years and represents a new way of testing......Much of our current knowledge about the physiological and pathophysiological role of gap junctions is based on experiments where coupling has been reduced by either chemical agents or genetic modification. This has brought evidence that gap junctions are important in many physiological processes...... the role of gap junctions. The aim of this review is to summarize the current knowledge obtained with agents that selectively increase gap junctional intercellular coupling. Two approaches will be reviewed: increasing coupling by the use of antiarrhythmic peptide and its synthetic analogs...

  12. The Gender Wage Gap and Domestic Violence

    Science.gov (United States)

    Aizer, Anna

    2014-01-01

    Three quarters of all violence against women is perpetrated by domestic partners. This study exploits exogenous changes in the demand for labor in female-dominated industries to estimate the impact of the male-female wage gap on domestic violence. Decreases in the wage gap reduce violence against women, consistent with a household bargaining model. These findings shed new light on the health production process as well as observed income gradients in health and suggest that in addition to addressing concerns of equity and efficiency, pay parity can also improve the health of American women via reductions in violence. PMID:25110354

  13. The Gender Wage Gap and Domestic Violence.

    Science.gov (United States)

    Aizer, Anna

    2010-09-01

    Three quarters of all violence against women is perpetrated by domestic partners. This study exploits exogenous changes in the demand for labor in female-dominated industries to estimate the impact of the male-female wage gap on domestic violence. Decreases in the wage gap reduce violence against women, consistent with a household bargaining model. These findings shed new light on the health production process as well as observed income gradients in health and suggest that in addition to addressing concerns of equity and efficiency, pay parity can also improve the health of American women via reductions in violence.

  14. Maximizing band gaps in plate structures

    DEFF Research Database (Denmark)

    Halkjær, Søren; Sigmund, Ole; Jensen, Jakob Søndergaard

    2006-01-01

    Band gaps, i.e., frequency ranges in which waves cannot propagate, can be found in elastic structures for which there is a certain periodic modulation of the material properties or structure. In this paper, we maximize the band gap size for bending waves in a Mindlin plate. We analyze an infinite...... periodic plate using Bloch theory, which conveniently reduces the maximization problem to that of a single base cell. Secondly, we construct a finite periodic plate using a number of the optimized base cells in a postprocessed version. The dynamic properties of the finite plate are investigated...

  15. Gendered Justice Gaps in Bosnia-Herzegovina

    DEFF Research Database (Denmark)

    Björkdahl, Annika; Mannergren Selimovic, Johanna

    2014-01-01

    , and reparations gaps-this article examines structural constraints for women to engage in shaping and implementing transitional justice, and unmasks transitional justice as a site for the long-term construction of the gendered post-conflict order. Thus, the gendered dynamics of peacebuilding and transitional...... justice have produced a post-conflict order characterized by gendered peace and justice gaps. Yet, we conclude that women are doing justice within the Bosnian-Herzegovina transitional justice project, and that their presence and participation is complex, multilayered, and constrained yet critical. © 2013...

  16. Natural Gas Engine Development Gaps (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Zigler, B.T.

    2014-03-01

    A review of current natural gas vehicle offerings is presented for both light-duty and medium- and heavy-duty applications. Recent gaps in the marketplace are discussed, along with how they have been or may be addressed. The stakeholder input process for guiding research and development needs via the Natural Gas Vehicle Technology Forum (NGVTF) to the U.S. Department of Energy and the California Energy Commission is reviewed. Current high-level natural gas engine development gap areas are highlighted, including efficiency, emissions, and the certification process.

  17. Gribov gap equation at finite temperature

    Energy Technology Data Exchange (ETDEWEB)

    Canfora, Fabrizio; Pais, Pablo [Centro de Estudios Cientificos (CECS), Valdivia (Chile); Universidad Andres Bello, Santiago (Chile); Salgado-Rebolledo, Patricio [Centro de Estudios Cientificos (CECS), Valdivia (Chile); Universidad de Concepcion, Departamento de Fisica, Concepcion (Chile); Universite Libre de Bruxelles and International Solvay Insitutes, Physique Theorique et Mathematique, Bruxelles (Belgium)

    2014-05-15

    In this paper the Gribov gap equation at finite temperature is analyzed. The solutions of the gap equation (which depend explicitly on the temperature) determine the structure of the gluon propagator within the semi-classical Gribov approach. The present analysis is consistent with the standard confinement scenario for low temperatures, while for high enough temperatures, deconfinement takes place and a free gluon propagator is obtained. An intermediate regime in between the confined and free phases can be read off from the resulting gluon propagator, which appears to be closely related to partial deconfinement. (orig.)

  18. Closing the R&D Gap

    OpenAIRE

    Thomas Karier

    1999-01-01

    This study identifies a clear need for government policy to address the widening R&D gap between the United States, Japan and Germany. In 1991, the United States spent only 1.9 percent of its GDP on nondefense R&D compared to 3 percent for Japan and 2.7 percent for Germany. The possibility that his gap can be closed through tax incentives, such as the Research and Experimentation tax credit, appears highly unlikely. A detailed review of this credit shows that it had a relatively minor impact ...

  19. Security Gaps In Authentication Factor Credentials

    Directory of Open Access Journals (Sweden)

    Neeraj A. Sharma

    2015-08-01

    Full Text Available Authentication factors refer to user login credentials that a user supplies to an authentication process for it to decide whether to grant or deny access. While two-factor and three-factor authentication generally provides better security than one-factor authentication the aim of this paper is to review security in individual authentication factor credentials that are in use nowadays. These credentials will be discussed in factor categories knowledge factor possession factor and inherence factor. The paper details current security gaps and some novel approaches to diminish the gaps in these authentication factors. We believe that our recommendations will inspire development of better authentication credentials and systems.

  20. The Gender Gap in European Business Schools

    DEFF Research Database (Denmark)

    Roseberry, Lynn; Remke, Robyn; Klæsson, Johan

    "The Gender Gap in European Business Schools: A Leadership Perspective" is a research project initiated and funded by EFMD, EQUAL, and the business schools represented on the project’s Steering Committee with following motivations for the study: Numerous studies by policy makers and academics have...... documented the existence of a faculty gender gap in Higher Education Institutions (HEIs), which starts at the bottom of the academic hierarchy at the Ph.D. level and grows wider at each succeeding stage in the academic career path. As of 2013, women still represented less than 30% of grade A academic staff...

  1. Flexowriters, Punch Paper Poetry and Ontological Gaps

    DEFF Research Database (Denmark)

    Søndergaard, Morten

    2013-01-01

    this position as being as close to the current state of affairs at this point in time as may be achieved (and I think it is), then we still need to ask ourselves: what happened to the archive-material that did not ‘fit’ the technologies and politics of the archive? If and when the transformation of the archive...... able to close the gap between the different paradigmatic ‘regimes’ defining the archival practice in the process of transformation. The ‘unheard’ not only witnesses this on an empirical level; it points, I would claim, towards an ontological gap between archival practices and the theoretical scope...

  2. SAR backscatter from coniferous forest gaps

    Science.gov (United States)

    Day, John L.; Davis, Frank W.

    1992-01-01

    A study is in progress comparing Airborne Synthetic Aperture Radar (AIRSAR) backscatter from coniferous forest plots containing gaps to backscatter from adjacent gap-free plots. Issues discussed are how do gaps in the range of 400 to 1600 sq m (approximately 4-14 pixels at intermediate incidence angles) affect forest backscatter statistics and what incidence angles, wavelengths, and polarizations are most sensitive to forest gaps. In order to visualize the slant-range imaging of forest and gaps, a simple conceptual model is used. This strictly qualitative model has led us to hypothesize that forest radar returns at short wavelengths (eg., C-band) and large incidence angles (e.g., 50 deg) should be most affected by the presence of gaps, whereas returns at long wavelengths and small angles should be least affected. Preliminary analysis of 1989 AIRSAR data from forest near Mt. Shasta supports the hypothesis. Current forest backscatter models such as MIMICS and Santa Barbara Discontinuous Canopy Backscatter Model have in several cases correctly predicted backscatter from forest stands based on inputs of measured or estimated forest parameters. These models do not, however, predict within-stand SAR scene texture, or 'intrinsic scene variability' as Ulaby et al. has referred to it. For instance, the Santa Barbara model, which may be the most spatially coupled of the existing models, is not truly spatial. Tree locations within a simulated pixel are distributed according to a Poisson process, as they are in many natural forests, but tree size is unrelated to location, which is not the case in nature. Furthermore, since pixels of a simulated stand are generated independently in the Santa Barbara model, spatial processes larger than one pixel are not modeled. Using a different approach, Oliver modeled scene texture based on an hypothetical forest geometry. His simulated scenes do not agree well with SAR data, perhaps due to the simple geometric model used. Insofar as texture

  3. Closing the gap between formalism and application

    DEFF Research Database (Denmark)

    Christensen, Ole Ravn

    2008-01-01

    -based learning (PBL), in the special model used at Aalborg University, Denmark, may give us some idea of how to bridge this gap. Through an investigation of a series of examples of student projects concerning the application of mathematical subjects-such as matrices, differential equations, cluster analysis......A common problem in learning mathematics concerns the gap between, on the one hand, doing the formalisms and calculations of abstract mathematics and, on the other hand, applying these in a specific contextualized setting for example the engineering world. The skills acquired through problem...

  4. En introduksjon til Gap-modellen

    OpenAIRE

    Ranglund, Ole Jørgen

    2014-01-01

    GAP-modellen, som er forankret i det dominerende persepsjonspsykologiske perspektivet innen tjenesteforskningen, kan ofte være et velegnet redskap til bruk i organisasjoners kvalitetsrettede arbeid. Modellen, som har blitt forandret flere ganger, ble utviklet på midten av 1980-tallet (Parasuraman, Zeithaml og Berry 1985). Etter at forskning på tjenester for alvor skjøt fart litt ut på 1980-tallet har Gap-modellen vært sentral, og etter hvert har modellen fått hegemoni (Lindquist og Persson 19...

  5. Mechanics of Fluid-Filled Interstitial Gaps. II. Gap Characteristics in Xenopus Embryonic Ectoderm.

    Science.gov (United States)

    Barua, Debanjan; Parent, Serge E; Winklbauer, Rudolf

    2017-08-22

    The ectoderm of the Xenopus embryo is permeated by a network of channels that appear in histological sections as interstitial gaps. We characterized this interstitial space by measuring gap sizes, angles formed between adjacent cells, and curvatures of cell surfaces at gaps. From these parameters, and from surface-tension values measured previously, we estimated the values of critical mechanical variables that determine gap sizes and shapes in the ectoderm, using a general model of interstitial gap mechanics. We concluded that gaps of 1-4 μm side length can be formed by the insertion of extracellular matrix fluid at three-cell junctions such that cell adhesion is locally disrupted and a tension difference between cell-cell contacts and the free cell surface at gaps of 0.003 mJ/m(2) is generated. Furthermore, a cell hydrostatic pressure of 16.8 ± 1.7 Pa and an interstitial pressure of 3.9 ± 3.6 Pa, relative to the central blastocoel cavity of the embryo, was found to be consistent with the observed gap size and shape distribution. Reduction of cell adhesion by the knockdown of C-cadherin increased gap volume while leaving intracellular and interstitial pressures essentially unchanged. In both normal and adhesion-reduced ectoderm, cortical tension of the free cell surfaces at gaps does not return to the high values characteristic of the free surface of the whole tissue. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  6. Establishment of epithelial polarity--GEF who's minding the GAP?

    Science.gov (United States)

    Ngok, Siu P; Lin, Wan-Hsin; Anastasiadis, Panos Z

    2014-08-01

    Cell polarization is a fundamental process that underlies epithelial morphogenesis, cell motility, cell division and organogenesis. Loss of polarity predisposes tissues to developmental disorders and contributes to cancer progression. The formation and establishment of epithelial cell polarity is mediated by the cooperation of polarity protein complexes, namely the Crumbs, partitioning defective (Par) and Scribble complexes, with Rho family GTPases, including RhoA, Rac1 and Cdc42. The activation of different GTPases triggers distinct downstream signaling pathways to modulate protein-protein interactions and cytoskeletal remodeling. The spatio-temporal activation and inactivation of these small GTPases is tightly controlled by a complex interconnected network of different regulatory proteins, including guanine-nucleotide-exchange factors (GEFs), GTPase-activating proteins (GAPs), and guanine-nucleotide-dissociation inhibitors (GDIs). In this Commentary, we focus on current understanding on how polarity complexes interact with GEFs and GAPs to control the precise location and activation of Rho GTPases (Crumbs for RhoA, Par for Rac1, and Scribble for Cdc42) to promote apical-basal polarization in mammalian epithelial cells. The mutual exclusion of GTPase activities, especially that of RhoA and Rac1, which is well established, provides a mechanism through which polarity complexes that act through distinct Rho GTPases function as cellular rheostats to fine-tune specific downstream pathways to differentiate and preserve the apical and basolateral domains. This article is part of a Minifocus on Establishing polarity.

  7. Dynamic Model of Gap Loop for HCW Mill

    Institute of Scientific and Technical Information of China (English)

    YANG Jing-ming; YANG Qiu-xia; CHE Hai-jun; CHANG Ling-fang

    2004-01-01

    The hydraulic automatic gauge control system using gap loop for cold mill was designed. The stiffness of HCW cold mill was defined for gap loop, and the dynamic model of gauge control system for gap loop was built with mechanism analysis. The stiffness for gap loop and the cylinder displacement loop were measured.

  8. "Minding the gap": imagination, creativity and human cognition.

    Science.gov (United States)

    Pelaprat, Etienne; Cole, Michael

    2011-12-01

    Inquiry into the nature of mental images is a major topic in psychology where research is focused on the psychological faculties of imagination and creativity. In this paper, we draw on the work of L.S. Vygotsky to develop a cultural-historical approach to the study of imagination as central to human cognitive processes. We characterize imagination as a process of image making that resolves "gaps" arising from biological and cultural-historical constraints, and that enables ongoing time-space coordination necessary for thought and action. After presenting some basic theoretical considerations, we offer a series of examples to illustrate for the reader the diversity of processes of imagination as image making. Applying our arguments to contemporary digital media, we argue that a cultural-historical approach to image formation is important for understanding how imagination and creativity are distinct, yet inter-penetrating processes.

  9. Galaxy formation.

    Science.gov (United States)

    Peebles, P J

    1998-01-01

    It is argued that within the standard Big Bang cosmological model the bulk of the mass of the luminous parts of the large galaxies likely had been assembled by redshift z approximately 10. Galaxy assembly this early would be difficult to fit in the widely discussed adiabatic cold dark matter model for structure formation, but it could agree with an isocurvature version in which the cold dark matter is the remnant of a massive scalar field frozen (or squeezed) from quantum fluctuations during inflation. The squeezed field fluctuations would be Gaussian with zero mean, and the distribution of the field mass therefore would be the square of a random Gaussian process. This offers a possibly interesting new direction for the numerical exploration of models for cosmic structure formation.

  10. Cloud Formation

    Science.gov (United States)

    Graham, Mark Talmage

    2004-05-01

    Cloud formation is crucial to the heritage of modern physics, and there is a rich literature on this important topic. In 1927, Charles T.R. Wilson was awarded the Nobel Prize in physics for applications of the cloud chamber.2 Wilson was inspired to study cloud formation after working at a meteorological observatory on top of the highest mountain in Scotland, Ben Nevis, and testified near the end of his life, "The whole of my scientific work undoubtedly developed from the experiments I was led to make by what I saw during my fortnight on Ben Nevis in September 1894."3 To form clouds, Wilson used the sudden expansion of humid air.4 Any structure the cloud may have is spoiled by turbulence in the sudden expansion, but in 1912 Wilson got ion tracks to show up by using strobe photography of the chamber immediately upon expansion.5 In the interim, Millikan's study in 1909 of the formation of cloud droplets around individual ions was the first in which the electron charge was isolated. This study led to his famous oil drop experiment.6 To Millikan, as to Wilson, meteorology and physics were professionally indistinct. With his meteorological physics expertise, in WWI Millikan commanded perhaps the first meteorological observation and forecasting team essential to military operation in history.7 But even during peacetime meteorology is so much of a concern to everyone that a regular news segment is dedicated to it. Weather is the universal conversation topic, and life on land could not exist as we know it without clouds. One wonders then, why cloud formation is never covered in physics texts.

  11. Closing the Achievement Gap on ACT & SAT

    Science.gov (United States)

    Anderson, David

    2010-01-01

    Research has focused on four groups of factors and the achievement gap: (1) student characteristics (high school GPA, attendance patterns, courses taken in high school, participation in extra-curricular activities, etc.); (2) family characteristics (family structure, in home, parents' level of education, mobility, etc.); (3) school-based…

  12. The Wage Gap: Briefing Paper #1.

    Science.gov (United States)

    National Committee on Pay Equity, Washington, DC.

    Women have made slow, steady progress in the labor market since 1979, but the wage gap has not narrowed significantly. This briefing paper updates a September 1987 paper based on "Male-Female Differences in Work Experience, Occupations, and Earnings: 1984" (Current Population Reports, Household Economic Studies, Series P-70, No. 10, issued in…

  13. A Theory of Gender Wage Gap

    OpenAIRE

    Jellal, Mohamed; Nordman, Christophe

    2009-01-01

    In this paper, we introduce uncertainty of the labour productivity of women in a competitive model of wage determination. We demonstrate that more qualified women are then offered much lower wages than men at the equilibrium. This result is consistent with the glass ceiling hypothesis according to which there exist larger gender wage gaps at the upper tail of the wage distribution.

  14. Producing gapped-ferrite transformer cores

    Science.gov (United States)

    Mclyman, W. T.

    1980-01-01

    Improved manufacturing techniques make reproducible gaps and minimize cracking. Molded, unfired transformer cores are cut with thin saw and then fired. Hardened semicircular core sections are bonded together, placed in aluminum core box, and fluidized-coated. After winding is run over box, core is potted. Economical method significantly reduces number of rejects.

  15. FINAL REPORT ON GDE GAP CELL

    Energy Technology Data Exchange (ETDEWEB)

    Herman, D.; Summers, W.; Danko, E.

    2009-09-28

    A project has been undertaken to develop an electrochemical cell and support equipment for evaluation of a gas diffusion electrode-based, narrow-electrolyte-gap anode for SO{sub 2} oxidation in the hydrogen production cycle of the hybrid sulfur (HyS) process. The project supported the HyS development program at the Savannah River National Lab (SRNL). The benefits of using a gas diffusion electrode in conjunction with the narrow anolyte gap are being determined through electrochemical polarization testing under a variety conditions, and by comparison to results produced by SRNL and others using anode technologies that have no anolyte gap. These test results indicate that the NGA cell has low resistance suitable for use in the HyS electrolyzer, exhibits good efficiency at high current densities compared to the direct feed HyS electrolyzer, and indicates robust performance in extended testing over 65 hours. Seepage episodes were mostly caused by port clogging, which can be mitigated in future designs through minor modifications to the hardware. Significant reductions in sulfur crossover have not yet been demonstrated in the NGA configuration compared to in-house direct feed testing, but corroborative sulfur layer analysis is as yet incomplete. Further testing in a single-pass anolyte configuration is recommended for complete evaluation of steady-state electrochemical efficiency and SO{sub 2} crossover in the narrow gap configuration.

  16. Gap junction diseases of the skin.

    NARCIS (Netherlands)

    Steensel, M.A.M. van

    2004-01-01

    Gap junctions are intercellular channels that allow the passage of water, ions, and small molecules. They are involved in quick, short-range messaging between cells and are found in skin, nervous tissue, heart, and muscle. An increasing number of hereditary skin disorders appear to be caused by muta

  17. The deposit financing gap: another Dutch disease

    NARCIS (Netherlands)

    Meijers, H.H.M.; Muysken, J.; Sleijpen, O.C.H.M.

    2015-01-01

    In the last 2 decades, the Netherlands has experienced an increase in real-estate prices, accompanied by an increase in mortgages and a marked decline in household savings. As a consequence, banks are faced with a large retail funding gap: outstanding mortgage debt is insufficiently matched by

  18. The deposit financing gap: Another Dutch disease

    NARCIS (Netherlands)

    Meijers, H.H.M.; Muysken, J.; Sleijpen, O.C.H.M.

    2014-01-01

    In the last two decades the Netherlands have experienced an increase in real-estate prices, accompanied by an increase in mortgages and a marked decline in household savings. As a consequence banks are faced with a large retail funding gap: outstanding mortgage debt is insufficiently matched by

  19. The deposit financing gap: Another Dutch disease

    NARCIS (Netherlands)

    Meijers, H.H.M.; Muysken, J.; Sleijpen, O.C.H.M.

    2014-01-01

    In the last two decades the Netherlands have experienced an increase in real-estate prices, accompanied by an increase in mortgages and a marked decline in household savings. As a consequence banks are faced with a large retail funding gap: outstanding mortgage debt is insufficiently matched by reta

  20. The deposit financing gap: another Dutch disease

    NARCIS (Netherlands)

    Meijers, H.H.M.; Muysken, J.; Sleijpen, O.C.H.M.

    2015-01-01

    In the last 2 decades, the Netherlands has experienced an increase in real-estate prices, accompanied by an increase in mortgages and a marked decline in household savings. As a consequence, banks are faced with a large retail funding gap: outstanding mortgage debt is insufficiently matched by retai

  1. EurepGAP certification for small producers

    NARCIS (Netherlands)

    Valk, van der O.M.C.

    2006-01-01

    The majority of agriculture practitioners worldwide are smallholders. Compliance with market related standards, such as set by EurepGAP, is crucial for obtaining and maintaining international market access, particularly to the European Union. Private standards must allow for innovative and cost effi

  2. Auditory gap detection in the early blind.

    Science.gov (United States)

    Weaver, Kurt E; Stevens, Alexander A

    2006-01-01

    For blind individuals, audition provides critical information for interacting with the environment. Individuals blinded early in life (EB) typically show enhanced auditory abilities relative to sighted controls as measured by tasks requiring complex discrimination, attention and memory. In contrast, few deficits have been reported on tasks involving auditory sensory thresholds (e.g., Yates, J.T., Johnson, R.M., Starz, W.J., 1972. Loudness perception of the blind. Audiology 11(5), 368-376; Starlinger, I., Niemeyer, W., 1981. Do the blind hear better? Investigations on auditory processing in congenital or early acquired blindness. I. Peripheral functions. Audiology 20(6), 503-509). A study of gap detection stands at odds with this distinction [Muchnik, C., Efrati, M., Nemeth, E., Malin, M., Hildesheimer, M., 1991. Central auditory skills in blind and sighted subjects. Scand. Audiol. 20(1), 19-23]. In the current investigation we re-examined gap detection abilities in the EB using a single-interval, yes/no method. A group of younger sighted control individuals (SCy) was included in the analysis in addition to EB and sighted age matched control individuals (SCm) in order to examine the effect of age on gap detection performance. Estimates of gap detection thresholds for EB subjects were nearly identical to SCm subjects and slightly poorer relative to the SCy subjects. These results suggest some limits on the extent of auditory temporal advantages in the EB.

  3. The Gaps of Which Communication Is Made.

    Science.gov (United States)

    Peters, John Durham

    1994-01-01

    Argues that the gap between transmission and reception is fundamental to most communication. Summarizes theorizing on communication and mass communication in Plato, about U.S. broadcasting, and in hermeneutics. Concludes that a conceptual contrast between open dissemination (mass) and individualized interaction (interpersonal) is inevitable…

  4. Topological scaling and gap filling at crisis

    Energy Technology Data Exchange (ETDEWEB)

    Szabo, K. Gabor [Department of Mathematics, University of Kansas, Lawrence, Kansas 66045 (United States); Institute for Theoretical Physics, Eoetvoes University, P.O. Box 32, Budapest, H-1518, (Hungary); Lai, Ying-Cheng [Department of Mathematics and Department of Electrical Engineering, Arizona State University, Tempe, Arizona 85287 (United States); Tel, Tamas [Institute for Theoretical Physics, Eoetvoes University, P.O. Box 32, Budapest, H-1518, (Hungary); Grebogi, Celso [Institute for Plasma Research, Department of Mathematics, and Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States)

    2000-05-01

    Scaling laws associated with an interior crisis of chaotic dynamical systems are studied. We argue that open gaps of the chaotic set become densely filled at the crisis due to the sudden appearance of unstable periodic orbits with extremely long periods. We formulate a scaling theory for the associated growth of the topological entropy. (c) 2000 The American Physical Society.

  5. Band Gap Narrowing in Heavily Doped Silicon.

    Science.gov (United States)

    Gupta, Tapan Kumar

    Two analytic models for transport and band gap narrowing in heavily doped (N_{rm D} > 10^{20} cm^ {-3}) silicon have been set up and verified through measurements on n^{+} -p junction devices. The first model is based on calculation of the ratio of the charge present in the emitter of the n^{+} region of the junction to that of the charge present in the absence of band gap shrinkage. Fermi-Dirac statistics are employed and are found to have a significant effect at this doping level. The second model is based on current transport of minority carriers in the n^{+} region. In this model only two parameters need to be known, the diffusion coefficient and the diffusion length for minority carriers, to calculate the band gap narrowing. An empirical relation between band gap narrowing and donor concentration has also been established based on experimental values of diffusion coefficient and mobility. These models have been verified by several different experimental techniques including surface photovoltage, open circuit voltage decay, photoconductivity decay and modulation reflection spectroscopy. The results indicate that, in the impurity range above about 10^{20} cm^{-3}, Fermi-Dirac statistics must be invoked in order to achieve a satisfactory fit with experimental data.

  6. Energy Gaps in a Spacetime Crystal

    CERN Document Server

    Horwitz, L P

    2009-01-01

    This paper presents an analysis of the band structure of a spacetime potential lattice created by a standing electromagnetic wave. We show that there are energy band gaps. We estimate the effect, and propose a measurement that could confirm the existence of such phenomena.

  7. Quantifying the Gender Gap in Science Interests

    Science.gov (United States)

    Baram-Tsabari, Ayelet; Yarden, Anat

    2011-01-01

    Nearly 5,000 self-generated science-related K-12 students' questions, classified into seven science subjects, were used to quantitatively measure the gender gap in science interests and its change with age. In this data set, a difference between boys' and girls' science interests did not exist during early childhood, but increased over 20-fold by…

  8. Subgroup Achievement and Gap Trends: Hawaii

    Science.gov (United States)

    Center on Education Policy, 2010

    2010-01-01

    Hawaii showed improvement in reading and math in grade 8 at the basic, proficient, and advanced levels for Asian and white students, low income students, and boys and girls. Gains in math tended to be larger than in reading. Trends in closing achievement gaps were mixed. Comparable data were available from 2007 through 2009. (Contains 9 tables.)…

  9. The Reed Elsevier stock price gap

    NARCIS (Netherlands)

    Kamp, B.

    1995-01-01

    This is the report of a limited study on the structural stock price differences between Reed and Elsevier. The purpose of this study is to provide an overview of the problem area and to formulate and discuss several hypotheses regarding the causes of this gap. The research was performed by

  10. Gap junction diseases of the skin.

    NARCIS (Netherlands)

    Steensel, M.A.M. van

    2004-01-01

    Gap junctions are intercellular channels that allow the passage of water, ions, and small molecules. They are involved in quick, short-range messaging between cells and are found in skin, nervous tissue, heart, and muscle. An increasing number of hereditary skin disorders appear to be caused by muta

  11. Ethnicity and Gender Gaps in Early Childhood

    Science.gov (United States)

    Hansen, Kirstine; Jones, Elizabeth M.

    2011-01-01

    Gender differences in academic performance and achievement have been of policy concern for decades--both interest in lower performance by girls in the areas of mathematics and science and, more recently, in boys' underperformance in most other academic areas. Much previous research has focused on gender gaps, while overlooking other factors that…

  12. The Gender Gap in European Business Schools

    DEFF Research Database (Denmark)

    Roseberry, Lynn; Remke, Robyn; Klæsson, Johan

    "The Gender Gap in European Business Schools: A Leadership Perspective" is a research project initiated and funded by EFMD, EQUAL, and the business schools represented on the project’s Steering Committee with following motivations for the study: Numerous studies by policy makers and academics have...

  13. Decomposing Achievement Gaps among OECD Countries

    Science.gov (United States)

    Zhang, Liang; Lee, Kristen A.

    2011-01-01

    In this study, we use decomposition methods on PISA 2006 data to compare student academic performance across OECD countries. We first establish an empirical model to explain the variation in academic performance across individuals, and then use the Oaxaca-Blinder decomposition method to decompose the achievement gap between each of the OECD…

  14. Gaps in agricultural climate adaptation research

    Science.gov (United States)

    Davidson, Debra

    2016-05-01

    The value of the social sciences to climate change research is well recognized, but notable gaps remain in the literature on adaptation in agriculture. Contributions focus on farmer behaviour, with important research regarding gender, social networks and institutions remaining under-represented.

  15. Colored neon flanks and line gap enhancement.

    Science.gov (United States)

    Redies, C; Spillmann, L; Kunz, K

    1984-01-01

    When a colored line connects two black (or differently colored) lines across a gap, colored neon flanks are seen on either side of it. These flanks extend over gap sizes of 50 min arc foveally and are not explained by Bezold-type assimilation. They may be elicited by black lines as short as 6 min arc adjoining the colored line at each end. To maximize these flanks, the black and colored lines must appear linearly continuous. Nonaligned junctions weaken the effect and an angular tilt of more than 40 dog destroys it. In this and other respects, (local) neon flanks are similar to van Tuijl's (global) neon color spreading (1975). Both phenomena have analogs in brightness perception. We propose that neon spreading is a lateral extension of neon flanks across the empty space between them, and discuss similarities of these effects with other brightness illusions (Schumann, Prandtl, Ehrenstein). For this group of illusions the term "line gap enhancement" is introduced to imply perceptual enhancement of changes in brightness and/or color along lines. Correspondences between the psychophysical properties and structural prerequisites for line gap enhancement on one hand and neuronal response properties of end-zone inhibited (hypercomplex) cortical cells on the other are discussed.

  16. Radial-Gap Motor for Ship Propulsion

    Science.gov (United States)

    Yanamoto, Toshiyuki; Yokoyama, Minoru

    The KHI team has developed radial gap high-temperature superconducting (HTS) motors of three sizes, 1 MW-class, 3 MW, and 20 MW, to be used for electric propulsion systems for ships. The volumetric torque density of the assembled 3 MW HTS motor was recorded at 40 kNm/m3 in the load test; the world's highest in the class.

  17. EurepGAP certification for small producers

    NARCIS (Netherlands)

    Valk, van der O.M.C.

    2006-01-01

    The majority of agriculture practitioners worldwide are smallholders. Compliance with market related standards, such as set by EurepGAP, is crucial for obtaining and maintaining international market access, particularly to the European Union. Private standards must allow for innovative and cost effi

  18. FINAL REPORT ON GDE GAP CELL

    Energy Technology Data Exchange (ETDEWEB)

    Herman, D.; Summers, W.; Danko, E.

    2009-09-28

    A project has been undertaken to develop an electrochemical cell and support equipment for evaluation of a gas diffusion electrode-based, narrow-electrolyte-gap anode for SO{sub 2} oxidation in the hydrogen production cycle of the hybrid sulfur (HyS) process. The project supported the HyS development program at the Savannah River National Lab (SRNL). The benefits of using a gas diffusion electrode in conjunction with the narrow anolyte gap are being determined through electrochemical polarization testing under a variety conditions, and by comparison to results produced by SRNL and others using anode technologies that have no anolyte gap. These test results indicate that the NGA cell has low resistance suitable for use in the HyS electrolyzer, exhibits good efficiency at high current densities compared to the direct feed HyS electrolyzer, and indicates robust performance in extended testing over 65 hours. Seepage episodes were mostly caused by port clogging, which can be mitigated in future designs through minor modifications to the hardware. Significant reductions in sulfur crossover have not yet been demonstrated in the NGA configuration compared to in-house direct feed testing, but corroborative sulfur layer analysis is as yet incomplete. Further testing in a single-pass anolyte configuration is recommended for complete evaluation of steady-state electrochemical efficiency and SO{sub 2} crossover in the narrow gap configuration.

  19. Health disparities and gaps in school readiness.

    Science.gov (United States)

    Currie, Janet

    2005-01-01

    The author documents pervasive racial disparities in the health of American children and analyzes how and how much those disparities contribute to racial gaps in school readiness. She explores a broad sample of health problems common to U.S. children, such as attention deficit hyperactivity disorder, asthma, and lead poisoning, as well as maternal health problems and health-related behaviors that affect children's behavioral and cognitive readiness for school. If a health problem is to affect the readiness gap, it must affect many children, it must be linked to academic performance or behavior problems, and it must show a racial disparity either in its prevalence or in its effects. The author focuses not only on the black-white gap in health status but also on the poor-nonpoor gap because black children tend to be poorer than white children. The health conditions Currie considers seriously impair cognitive skills and behavior in individual children. But most explain little of the overall racial gap in school readiness. Still, the cumulative effect of health differentials summed over all conditions is significant. Currie's rough calculation is that racial differences in health conditions and in maternal health and behaviors together may account for as much as a quarter of the racial gap in school readiness. Currie scrutinizes several policy steps to lessen racial and socioeconomic disparities in children's health and to begin to close the readiness gap. Increasing poor children's eligibility for Medicaid and state child health insurance is unlikely to be effective because most poor children are already eligible for public insurance. The problem is that many are not enrolled. Even increasing enrollment may not work: socioeconomic disparities in health persist in Canada and the United Kingdom despite universal public health insurance. The author finds more promise in strengthening early childhood programs with a built-in health component, like Head Start; family

  20. Robust room temperature ferromagnetism and band gap tuning in nonmagnetic Mg doped ZnO films

    Science.gov (United States)

    Quan, Zhiyong; Liu, Xia; Qi, Yan; Song, Zhilin; Qi, Shifei; Zhou, Guowei; Xu, Xiaohong

    2017-03-01

    Mg doped ZnO films with hexagonal wurtzite structure were deposited on c-cut sapphire Al2O3 substrates by pulsed laser deposition. Both room temperature ferromagnetism and band gap of the films simultaneously tuned by the concentration of oxygen vacancies were performed. Our results further reveal that the singly occupied oxygen vacancies should be responsible for the room temperature ferromagnetism and band gap narrowing. Singly occupied oxygen vacancies having the localized magnetic moments form bound magnetic polarons, which results in a long-range ferromagnetic ordering due to Mg doping. Moreover, band gap narrowing of the films is probably due to the formation of impurity band in the vicinity of valence band, originating from singly occupied oxygen vacancies. These results may build a bridge to understand the relationship between the magnetic and optical properties in oxide semiconductor, and are promising to integrate multiple functions in one system.

  1. Band-gap and sub-band-gap photoelectrochemical processes at nanocrystalline CdS grown on ZnO by successive ionic layer adsorption and reaction method

    Energy Technology Data Exchange (ETDEWEB)

    Malashchonak, M.V., E-mail: che.malasche@gmail.com [Belarusian State University, Nezalezhnastsi Av. 4, Minsk 220030 (Belarus); Streltsov, E.A., E-mail: streltea@bsu.by [Belarusian State University, Nezalezhnastsi Av. 4, Minsk 220030 (Belarus); Mazanik, A.V. [Belarusian State University, Nezalezhnastsi Av. 4, Minsk 220030 (Belarus); Kulak, A.I., E-mail: kulak@igic.bas-net.by [Institute of General and Inorganic Chemistry, National Academy of Sciences of Belarus, Surganova str., 9/1, Minsk 220072 (Belarus); Poznyak, S.K. [Belarusian State University, Nezalezhnastsi Av. 4, Minsk 220030 (Belarus); Stroyuk, O.L., E-mail: stroyuk@inphyschem-nas.kiev.ua [L.V. Pysarzhevsky Institute of Physical Chemistry of National Academy of Sciences of Ukraine, 31 prosp. Nauky, 03028 Kyiv (Ukraine); Kuchmiy, S.Ya. [L.V. Pysarzhevsky Institute of Physical Chemistry of National Academy of Sciences of Ukraine, 31 prosp. Nauky, 03028 Kyiv (Ukraine); Gaiduk, P.I. [Belarusian State University, Nezalezhnastsi Av. 4, Minsk 220030 (Belarus)

    2015-08-31

    Cadmium sulfide nanoparticle (NP) deposition by the successive ionic layer adsorption and reaction (SILAR) method on the surface of mesoporous ZnO micro-platelets with a large specific surface area (110 ± 10 m{sup 2}g{sup −1}) results in the formation of ZnO/CdS heterostructures exhibiting a high incident photon-to-current conversion efficiency (Y) not only within the region of CdS fundamental absorption (Y{sub max} = 90%; 0.1 M Na{sub 2}S + 0.1 M Na{sub 2}SO{sub 3}), but also in the sub-band-gap (SBG) range (Y{sub max} = 25%). The onset potentials of SBG photoelectrochemical processes are more positive than the band-gap (BG) onset potential by up to 100 mV. A maximum incident photon-to-current conversion efficiency value for SBG processes is observed at larger amount of deposited CdS in comparison with the case of BG ones. The Urbach energy (E{sub U}) of CdS NPs determined from the photocurrent spectra reaches a maximal value on an early deposition stage (E{sub U} = 93 mV at SILAR cycle number N = 5), then lowers somewhat (E{sub U} = 73 mV at N = 10) and remains steady in the range of N from 20 to 300 (E{sub U} = 67 ± 1 mV). High efficiency of the photoelectrochemical SBG processes are interpreted in terms of light scattering in the ZnO/CdS heterostructures. - Highlights: • ZnO/CdS films demonstrate high quantum efficiency (25%) for sub-band-gap transitions. • Onset photocurrent potentials for sub-band-gap processes differ than those for band-gap ones. • Sub-band-gap transitions are caused by band-tail states in CdS nanoparticles.

  2. Cement Formation

    DEFF Research Database (Denmark)

    Telschow, Samira; Jappe Frandsen, Flemming; Theisen, Kirsten

    2012-01-01

    Cement production has been subject to several technological changes, each of which requires detailed knowledge about the high multiplicity of processes, especially the high temperature process involved in the rotary kiln. This article gives an introduction to the topic of cement, including...... an overview of cement production, selected cement properties, and clinker phase relations. An extended summary of laboratory-scale investigations on clinkerization reactions, the most important reactions in cement production, is provided. Clinker formations by solid state reactions, solid−liquid and liquid...

  3. Molecule Formation on Interstellar Grains

    Science.gov (United States)

    Vidali, G.

    2011-05-01

    The first experiments that were expressively designed to be applicable to hydrogen formation reactions in the ISM measured the efficiency of formation of molecular hydrogen on a polycrystalline olivine (Pirronello et al. (1997a)). It soon turned out that more was needed, and research began on the mechanism of reaction, on the in uence of the surface morphology, and on the excitation of the just- ormed molecule. In this review, I summarize what we learned from these and other experiments, and where more work is needed: in the elementary steps of reaction, in the bridging of the laboratory-ISM gap (large ux/large surface - small ux/small grain) using simulations, and in using realistic samples of dust grains. Understanding what experiments can and cannot deliver will help in designing and targeting observations, and vice-versa.

  4. In situ observational research of the gap wind "Hijikawa-Arashi" in Japan

    Science.gov (United States)

    Ohashi, Yukitaka; Terao, Toru; Shigeta, Yoshinori; Ohsawa, Teruo

    2015-02-01

    The Hijikawa-arashi, a gap wind occurring in Ozu City, Ehime Prefecture, Japan, was investigated through in situ observations of horizontal and vertical directions. Analysis of surface air temperature data revealed that the inland Ozu Basin was radiatively cooled on the days on which the Hijikawa-arashi events occurred. This induced a greater difference in air temperature between the basin and the estuary of the Hijikawa River in comparison to days that no basin cooling occurred. In addition, the wind speeds of the Hijikawa-arashi observed at the estuary of the Hijikawa River were strongly proportional to the sea-level pressure difference between the inland Ozu Basin and the estuary. Theoretical calculations indicated that this pressure gradient force was sufficient for driving the strong wind of the Hijikawa-arashi. Moreover, calculation of the Froude number using vertical meteorological data revealed that the Hijikawa-arashi developed as a supercritical flow. That is, the flow was intensified at the exit of the gap, in accordance with the hydraulic theory. The vertical observations detected the inversion layer over the Hijikawa-arashi and suggested an application of the shallow water theory to this gap wind. The Hijikawa-arashi is an interesting gap flow with a strong wind, despite its small-scale geography relative to other gap winds worldwide. There is an important trigger getting higher basin pressure upstream due to the radiative cooling of the atmosphere and formation of a cold pool at the basin.

  5. Mind the Gap : A study of the student-audit expectation gap and factors affecting it

    OpenAIRE

    2015-01-01

    This study explore the expectation gap between students and audit practitioners, and if certain factors have any significant impact on the students conformity to the practitioners expectations. The study is limited to business students and audit practitioners. We used an Independent Sam-ples T-Test and Pearson Correlation Analysis to conduct the analysis of 286 student responses and 98 practitioner responses. The results confirm previous research; the expectation gap exists. The findings conc...

  6. Coupled-mode theory for photonic band-gap inhibition of spatial instabilities.

    Science.gov (United States)

    Gomila, Damià; Oppo, Gian-Luca

    2005-07-01

    We study the inhibition of pattern formation in nonlinear optical systems using intracavity photonic crystals. We consider mean-field models for singly and doubly degenerate optical parametric oscillators. Analytical expressions for the new (higher) modulational thresholds and the size of the "band gap" as a function of the system and photonic crystal parameters are obtained via a coupled-mode theory. Then, by means of a nonlinear analysis, we derive amplitude equations for the unstable modes and find the stationary solutions above threshold. The form of the unstable mode is different in the lower and upper parts of the band gap. In each part there is bistability between two spatially shifted patterns. In large systems stable wall defects between the two solutions are formed and we provide analytical expressions for their shape. The analytical results are favorably compared with results obtained from the full system equations. Inhibition of pattern formation can be used to spatially control signal generation in the transverse plane.

  7. Thermo-Structural Response Caused by Structure Gap and Gap Design for Solid Rocket Motor Nozzles

    Directory of Open Access Journals (Sweden)

    Lin Sun

    2016-06-01

    Full Text Available The thermo-structural response of solid rocket motor nozzles is widely investigated in the design of modern rockets, and many factors related to the material properties have been considered. However, little work has been done to evaluate the effects of structure gaps on the generation of flame leaks. In this paper, a numerical simulation was performed by the finite element method to study the thermo-structural response of a typical nozzle with consideration of the structure gap. Initial boundary conditions for thermo-structural simulation were defined by a quasi-1D model, and then coupled simulations of different gap size matching modes were conducted. It was found that frictional interface treatment could efficiently reduce the stress level. Based on the defined flame leak criteria, gap size optimization was carried out, and the best gap matching mode was determined for designing the nozzle. Testing experiment indicated that the simulation results from the proposed method agreed well with the experimental results. It is believed that the simulation method is effective for investigating thermo-structural responses, as well as designing proper gaps for solid rocket motor nozzles.

  8. Smaller Real Regional Income Gap than Nominal Income Gap: A Price-adjusted Study

    Institute of Scientific and Technical Information of China (English)

    Xiaojuan Jiang; Hui Li

    2006-01-01

    Two factors determining the level of living in different areas are income level and price level.Current studies on regional gaps concentrate on the gap in income levels. The present paper studies the impact of the two variables on the real living standards in different regions, with the real gap in the living standards calculated with price adjustment by taking into consideration only the deviations brought about by cash income. The basic conclusion is that, despite China's economy having witnessed rapid growth, the statistics at the macro level cannot disguise the obvious gaps among regions; therefore, as a result of the impact of income and price, the real gap in the living standards among different regions is smaller than the gap indicated by the nominal income level. As people are sensitive to cash income level, they have a low sensitivity to changes in real purchasing power. In other words, in areas that have the same real income levels, people tend to think that people live better when the nominal income and price are both high. The differences in price indices among different regions show that the same cash income can get different goods and services in different regions. This explains the rationale of the existence of floating workers among different regions. On this basis, we predict that people working in high-income areas who enjoy higher levels of social security might prefer to live in low-priceareas after retirement if the social security payment method becomes more flexible.

  9. Cybersecurity and Privacy - bridging the gap

    DEFF Research Database (Denmark)

    he huge potential in future connected services has as a precondition that privacy and security needs are dealt with in order for new services to be accepted. This issue is increasingly on the agenda both at the company and at individual level. Cybersecurity and Privacy – bridging the gap addresses...... two very complex fields of the digital world, i.e., Cybersecurity and Privacy. These multifaceted, multidisciplinary and complex issues are usually understood and valued differently by different individuals, data holders and legal bodies. But a change in one field immediately affects the others....... Policies, frameworks, strategies, laws, tools, techniques, and technologies – all of these are tightly interwoven when it comes to security and privacy. This book is another attempt to bridge the gap between the industry and academia. The book addresses the views from academia and industry on the subject...

  10. INVESTIGATING MACROECONOMIC STABILITY USING THE OUTPUT GAP

    Directory of Open Access Journals (Sweden)

    Emilia TITAN

    2013-03-01

    Full Text Available The purpose of the article is to illustrate the importance of the output gap in analysing macroeconomic stability in general and business cycle dynamics in particular. Ten EU countries are considered, with five old members and five new members. For all ten countries the data for the period 1999-2014 is used, but for four countries, namely France, the United Kingdom, Italy and Spain additional data is available that goes back to 1965, such that the whole period 1965-2014 is covered, which allows for a particular analysis. An empirical analysis is performed with regard to the behaviour of the output gap for different countries over time. The results obtained allow for relevant comparisons and highlight the usefulness of this indicator as a tool in the study of business cycles.

  11. Gap Assessment in the Emergency Response Community

    Energy Technology Data Exchange (ETDEWEB)

    Barr, Jonathan L.; Burtner, Edwin R.; Pike, William A.; Peddicord, Annie M Boe; Minsk, Brian S.

    2010-09-27

    This report describes a gap analysis of the emergency response and management (EM) community, performed during the fall of 2009. Pacific Northwest National Laboratory (PNNL) undertook this effort to identify potential improvements to the functional domains in EM that could be provided by the application of current or future technology. To perform this domain-based gap analysis, PNNL personnel interviewed subject matter experts (SMEs) across the EM domain; to make certain that the analyses reflected a representative view of the community, the SMEs were from a variety of geographic areas and from various sized communities (urban, suburban, and rural). PNNL personnel also examined recent and relevant after-action reports and U.S. Government Accountability Office reports.

  12. The fiscal gap: An estimate for Russia

    Directory of Open Access Journals (Sweden)

    Evgeny Goryunov

    2015-09-01

    Full Text Available The fiscal gap is an indicator of the long-term balance of public finance and is calculated based on the intertemporal government budget constraint, which links government tax revenues and expenditures over long intervals. The estimate of the fiscal gap for the Russian general government has been determined according to three scenarios with varying assumptions regarding demographic trends, productivity growth rates, oil and gas prices and the quantity of extractable reserves. The calculations show that the current fiscal policy cannot provide for the stability of public finance in the long run. The main factors of budget imbalances are the growth of pension and health care expenditures caused by demographic trends and the gradual decline in tax receipts from the oil and gas sector.

  13. Inception report and gap analysis. Boiler inspection

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-06-01

    This inception and gap analysis report on boilers in Latvia, has been prepared in the framework of the 'Implementation of the EU directive on energy performance of buildings: development of the Latvian Scheme for energy auditing of building and inspection of boilers'. The report is the basis for the establishment of training of boiler inspectors; it develops a gap analysis for better understanding and estimating the number of installations in Latvia and develops suggestions for the institutional set up. In particular includes information on existing standard and regulation on boiler, suggestion for the content of the training material of experts for boiler inspections and a syllabus of the training course. A specific section is dedicated to the suggestion for certification system of trained boiler inspectors. (au)

  14. Diluted magnetic semiconductors with narrow band gaps

    Science.gov (United States)

    Gu, Bo; Maekawa, Sadamichi

    2016-10-01

    We propose a method to realize diluted magnetic semiconductors (DMSs) with p - and n -type carriers by choosing host semiconductors with a narrow band gap. By employing a combination of the density function theory and quantum Monte Carlo simulation, we demonstrate such semiconductors using Mn-doped BaZn2As2 , which has a band gap of 0.2 eV. In addition, we found a nontoxic DMS Mn-doped BaZn2Sb2 , of which the Curie temperature Tc is predicted to be higher than that of Mn-doped BaZn2As2 , the Tc of which was up to 230 K in a recent experiment.

  15. Photonic band gap in thin wire metamaterials.

    Science.gov (United States)

    Hock, Kai Meng

    2008-03-01

    We investigate the band structure of a class of photonic crystals made from only thin wires. Using a different method, we demonstrate that a complete photonic band gap is possible for such materials. Band gap materials normally consist of space filling dielectric or metal, whereas thin wires occupy a very small fraction of the volume. We show that this is related to the large increase in scattering at the Brillouin zone boundary. The method we developed brings together the calculation techniques in three different fields. The first is the calculation of scattering from periodic, tilted antennas, which we improve upon. The second is the standard technique for frequency selective surface design. The third is obtained directly from low energy electron diffraction theory. Good agreements with experiments for left handed materials, negative materials, and frequency selective surfaces are demonstrated.

  16. Neuroanatomical Correlates of the Income Achievement Gap

    Science.gov (United States)

    Mackey, Allyson P.; Finn, Amy S.; Leonard, Julia A.; Jacoby Senghor, Drew S.; West, Martin R.; Gabrieli, Christopher F.O.; Gabrieli, John D. E.

    2015-01-01

    In the United States, the difference in academic achievement between higher- and lower-income students (i.e., the income achievement gap) is substantial and growing. Here, we investigated neuroanatomical correlates of this gap in adolescents (n = 58) in whom academic achievement was measured by statewide standardized testing. Cortical gray matter volume was significantly greater in students from higher-income backgrounds (n = 35) compared to students from lower-income backgrounds (n = 23), but cortical white matter volume and total cortical surface area did not differ between groups. Cortical thickness in all lobes of the brain was greater in students from higher-income than lower-income backgrounds. Thicker cortex, particularly in temporal and occipital lobes, was associated with better test performance. These results represent the first evidence that cortical thickness differs across broad swaths of the brain between higher- and lower-income students, and that cortical thickness is related to academic achievement test scores. PMID:25896418

  17. Closing the Knowledge Gap in Foreign Markets

    DEFF Research Database (Denmark)

    Lyles, Marjorie A.; Pedersen, Torben; Petersen, Bent

    The study explores how firms close their knowledge gaps in relation to business environments of foreign markets. Potential determinants are derived from traditional internationalization process theory as well as more recent literature on organizational learning processes, including the concept...... of absorptive capacity. Building on these two literature streams a conceptual model is developed and tested on a set of primary data of Danish firms and their foreign market operations. The empirical study suggests that factors considered essential in traditional internationalization process theory......, such as experiential learning, explains only a very limited part of perceived knowledge gaps. When factors pertaining to the concepts of absorptive capacity and superstitious learning are added, the explanatory power improves significantly. Apparently, our understanding of firms' internationalization processes can...

  18. Flow Mode Magnetorheological Dampers with an Eccentric Gap

    OpenAIRE

    Choi, Young-Tai; Norman M. Wereley

    2014-01-01

    This paper analyzes flow mode magnetorheological (MR) dampers with an eccentric annular gap (i.e., a nonuniform annular gap). To this end, an MR damper analysis for an eccentric annular gap is constructed based on approximating the eccentric annular gap using a rectangular duct with a variable gap, as well as a Bingham-plastic constitutive model of the MR fluid. Performance of flow mode MR dampers with an eccentric gap was assessed analytically using both field-dependent damping force and dam...

  19. Local dynamics of gap-junction-coupled interneuron networks

    Science.gov (United States)

    Lau, Troy; Gage, Gregory J.; Berke, Joshua D.; Zochowski, Michal

    2010-03-01

    Interneurons coupled by both electrical gap-junctions (GJs) and chemical GABAergic synapses are major components of forebrain networks. However, their contributions to the generation of specific activity patterns, and their overall contributions to network function, remain poorly understood. Here we demonstrate, using computational methods, that the topological properties of interneuron networks can elicit a wide range of activity dynamics, and either prevent or permit local pattern formation. We systematically varied the topology of GJ and inhibitory chemical synapses within simulated networks, by changing connection types from local to random, and changing the total number of connections. As previously observed we found that randomly coupled GJs lead to globally synchronous activity. In contrast, we found that local GJ connectivity may govern the formation of highly spatially heterogeneous activity states. These states are inherently temporally unstable when the input is uniformly random, but can rapidly stabilize when the network detects correlations or asymmetries in the inputs. We show a correspondence between this feature of network activity and experimental observations of transient stabilization of striatal fast-spiking interneurons (FSIs), in electrophysiological recordings from rats performing a simple decision-making task. We suggest that local GJ coupling enables an active search-and-select function of striatal FSIs, which contributes to the overall role of cortical-basal ganglia circuits in decision-making.

  20. Information gap decision support for contaminant remediation

    Science.gov (United States)

    Vesselinov, V. V.; O'Malley, D.

    2013-12-01

    Uncertainty quantifications and decision analyses under severe lack of information are ubiquitous in every applied field of engineering, policy, and science. A severe lack of information precludes our ability to determine unbiased probabilistic distributions for model parameters and model predictions; therefore, model and decision uncertainties due to a severe lack of information cannot be characterized probabilistically. To circumvent this problem, information gap (info-gap) theory has been developed to explicitly recognize and quantify the implications of information gaps in decision making. Here we present a decision analysis based on info-gap theory developed for a source identification problem where the locations and mass fluxes of contaminants impacting groundwater resources are unknown. The problem is characterized with a lack of information related to (1) model parameters representing contaminant migration in the aquifer, and (2) observed contamination concentration in the existing monitoring wells. These two sources of uncertainty are coupled through an inverse model where the observed concentrations are applied to estimate model parameters. The decision goal is based on contaminant predictions at points of compliance. The decision analysis is demonstrated for synthetic and real-world test cases. The applied uncertainty-quantification, decision-support techniques and computational algorithms are implemented in code MADS (Model Analyses for Decision Support; http://mads.lanl.gov). MADS is C/C++ code that provides a framework for model-based decision support. MADS performs various types of model analyses including sensitivity analysis, parameter estimation, uncertainty quantification, model calibration, selection and averaging. To perform the analyses, MADS can be coupled with any external simulators. Our efforts target development of an interactive computer-based Decision Support System (DSS) that will help domain scientist, managers, regulators, and

  1. Evaluating the gender wage gap in Sweden

    OpenAIRE

    Malmberg, Åsa

    2007-01-01

    Using mainly quantile regressions, this paper evaluates the gender wage gap throughout the conditional wage distribution in Sweden. The gender wage is found to increase at the upper tail of the wage distribution, indicating an enforcement of the glass ceiling effect recorded in earlier studies. The results also indicate that the earlier noted trend of diminishing wage differences at the bottom of the wage distribution now is turning. The increase of overall wage inequalities coincides with a ...

  2. Bridging the Gap: Linking Simulation and Testing

    Energy Technology Data Exchange (ETDEWEB)

    Krajewski, Paul E.; Carsley, John; Stoudt, Mark R.; Hovanski, Yuri

    2012-09-01

    The Materials Genome Initiative (MGI) which is a key enabler for the Advanced Manufacturing Partnership, announced in 2011 by U.S. President Barack Obama, was established to accelerate the development and deployment of advanced materials. The MGI is driven by the need to "bridge the gap" between (I) experimental results and computational analysis to enable the rapid development and validation of new mateirals, and (II) the processes required to convert these materials into useable goods.

  3. Geology and health:closing the gap

    Institute of Scientific and Technical Information of China (English)

    A.B.Kampunzu

    2004-01-01

    It was discovered several decades ago that the natural geo-environment could substantially impact on the health of animals and humans. However, despite the growth of evidence supporting this discovery, there has not been a close interaction between geoscientists and health scientists in assessing the need to study the various facets of the relationships between human and animal health and air, water, soils and rocks. This book is timely in closing that gap as stated in its title.

  4. Closing the Knowledge Gap in Foreign Markets

    DEFF Research Database (Denmark)

    Lyles, Marjorie A.; Pedersen, Torben; Petersen, Bent

    The study explores how firms close their knowledge gaps in relation to business environments of foreign markets. Potential determinants are derived from traditional internationalization process theory as well as more recent literature on organizational learning processes, including the concept...... of absorptive capacity. Building on these two literature streams a conceptual model is developed and tested on a set of primary data of Danish firms and their foreign market operations. The empirical study suggests that factors considered essential in traditional internationalization process theory...

  5. Characterizing the gender gap in introductory physics

    Science.gov (United States)

    Kost, Lauren E.; Pollock, Steven J.; Finkelstein, Noah D.

    2009-06-01

    Previous research [S. J. Pollock , Phys. Rev. ST Phys. Educ. Res. 3, 1 (2007)] showed that despite the use of interactive engagement techniques, the gap in performance between males and females on a conceptual learning survey persisted from pretest to post-test at the University of Colorado at Boulder. Such findings were counter to previously published work [M. Lorenzo , Am. J. Phys. 74, 118 (2006)]. This study begins by identifying a variety of other gender differences. There is a small but significant difference in the course grades of males and females. Males and females have significantly different prior understandings of physics and mathematics. Females are less likely to take high school physics than males, although they are equally likely to take high school calculus. Males and females also differ in their incoming attitudes and beliefs about physics. This collection of background factors is analyzed to determine the extent to which each factor correlates with performance on a conceptual post-test and with gender. Binned by quintiles, we observe that males and females with similar pretest scores do not have significantly different post-test scores (p>0.2) . The post-test data are then modeled using two regression models (multiple regression and logistic regression) to estimate the gender gap in post-test scores after controlling for these important prior factors. These prior factors account for about 70% of the observed gender gap. The results indicate that the gender gap exists in interactive physics classes at our institution but is largely associated with differences in previous physics and math knowledge and incoming attitudes and beliefs.

  6. Supersize me: Cronobacter sakazakii phage GAP32

    Energy Technology Data Exchange (ETDEWEB)

    Abbasifar, Reza; Griffiths, Mansel W. [Canadian Research Institute for Food Safety, University of Guelph, Guelph, ON, Canada N1G 2W1 (Canada); Sabour, Parviz M. [Agriculture and Agri-Food Canada, Guelph Food Research Centre, Guelph, ON, Canada N1G 5C9 (Canada); Ackermann, Hans-Wolfgang [Department of Microbiology-Infectiology and Immunology, Faculty of Medicine, Université Laval, Quebec, QC (Canada); Vandersteegen, Katrien; Lavigne, Rob [Laboratory of Gene Technology, Katholieke Universiteit Leuven, Leuven (Belgium); Noben, Jean-Paul [Biomedical Research Institute and Transnational University Limburg, School of Life Sciences, Hasselt University, Diepenbeek (Belgium); Alanis Villa, Argentina; Abbasifar, Arash [Canadian Research Institute for Food Safety, University of Guelph, Guelph, ON, Canada N1G 2W1 (Canada); Nash, John H.E. [Public Health Agency of Canada, Laboratory for Foodborne Zoonoses, Guelph, ON, Canada N1G 3W4 (Canada); Kropinski, Andrew M., E-mail: akropins@uoguelph.ca [Public Health Agency of Canada, Laboratory for Foodborne Zoonoses, Guelph, ON, Canada N1G 3W4 (Canada); Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada N1G 2W1 (Canada)

    2014-07-15

    Cronobacter sakazakii is a Gram-negative pathogen found in milk-based formulae that causes infant meningitis. Bacteriophages have been proposed to control bacterial pathogens; however, comprehensive knowledge about a phage is required to ensure its safety before clinical application. We have characterized C. sakazakii phage vB{sub C}saM{sub G}AP32 (GAP32), which possesses the second largest sequenced phage genome (358,663 bp). A total of 571 genes including 545 protein coding sequences and 26 tRNAs were identified, thus more genes than in the smallest bacterium, Mycoplasma genitalium G37. BLASTP and HHpred searches, together with proteomic analyses reveal that only 23.9% of the putative proteins have defined functions. Some of the unique features of this phage include: a chromosome condensation protein, two copies of the large subunit terminase, a predicted signal-arrest-release lysin; and an RpoD-like protein, which is possibly involved in the switch from immediate early to delayed early transcription. Its closest relatives are all extremely large myoviruses, namely coliphage PBECO4 and Klebsiella phage vB{sub K}leM-RaK2, with whom it shares approximately 44% homologous proteins. Since the homologs are not evenly distributed, we propose that these three phages belong to a new subfamily. - Highlights: • Cronobacter sakazakii phage vB{sub C}saM{sub G}AP32 has a genome of 358,663 bp. • It encodes 545 proteins which is more than Mycoplasma genitalium G37. • It is a member of the Myoviridae. • It is peripherally related to coliphage PBECO4 and Klebsiella phage vB{sub K}leM-RaK2. • GAP32 encodes a chromosome condensation protein.

  7. Spirit of place: Bridging the 'epistemological gap'

    Science.gov (United States)

    Dudley, Nickola B. N.

    My work explores the psychological gap between humans and nature. Also how humanity is a parcel of nature and that the philosophy of spirit of place can create oneness through imagery, describing the landscape while also encompassing the 'larger frame' within the aesthetic. These transcendental moments connect with not only the landscape but to earth as a spiritual entity. My work is a response to the landscape and these moments.

  8. Characterizing the gender gap in introductory physics

    Directory of Open Access Journals (Sweden)

    Steven J. Pollock

    2009-01-01

    Full Text Available Previous research [S. J. Pollock et al., Phys. Rev. ST Phys. Educ. Res. 3, 1 (2007] showed that despite the use of interactive engagement techniques, the gap in performance between males and females on a conceptual learning survey persisted from pretest to post-test at the University of Colorado at Boulder. Such findings were counter to previously published work [M. Lorenzo et al., Am. J. Phys. 74, 118 (2006]. This study begins by identifying a variety of other gender differences. There is a small but significant difference in the course grades of males and females. Males and females have significantly different prior understandings of physics and mathematics. Females are less likely to take high school physics than males, although they are equally likely to take high school calculus. Males and females also differ in their incoming attitudes and beliefs about physics. This collection of background factors is analyzed to determine the extent to which each factor correlates with performance on a conceptual post-test and with gender. Binned by quintiles, we observe that males and females with similar pretest scores do not have significantly different post-test scores (p>0.2 . The post-test data are then modeled using two regression models (multiple regression and logistic regression to estimate the gender gap in post-test scores after controlling for these important prior factors. These prior factors account for about 70% of the observed gender gap. The results indicate that the gender gap exists in interactive physics classes at our institution but is largely associated with differences in previous physics and math knowledge and incoming attitudes and beliefs.

  9. Full-waveform inversion: Filling the gaps

    KAUST Repository

    Beydoun, Wafik B.

    2015-09-01

    After receiving an outstanding response to its inaugural workshop in 2013, SEG once again achieved great success with its 2015 SEG Middle East Workshop, “Full-waveform inversion: Filling the gaps,” which took place 30 March–1 April 2015 in Abu Dhabi, UAE. The workshop was organized by SEG, and its partner sponsors were Saudi Aramco (gold sponsor), ExxonMobil, and CGG. Read More: http://library.seg.org/doi/10.1190/tle34091106.1

  10. Level of evidence gap in orthopedic research.

    Science.gov (United States)

    Baldwin, Keith D; Bernstein, Joseph; Ahn, Jaimo; McKay, Scott D; Sankar, Wudbhav N

    2012-09-01

    Level of evidence is the most widely used metric for the quality of a publication, but instances exist in which a Level I study is neither feasible nor desirable. The goal of this study was to evaluate the level of evidence gap in current orthopedic research, which the authors defined as the disparity between the level of evidence that would be required to optimally answer the primary research question and the level of evidence that was actually used. Five orthopedic surgeons (K.D.B., J.B., J.A., S.D.M., W.N.S.) evaluated blinded articles from the first 6 months of 2010 in the Journal of Bone and Joint Surgery (American Volume) (JBJS-Am), classifying the study type and design and extracting a primary research question from each article. Each evaluator then defined the study type and method, along with the level of evidence that would ideally be used to address the primary research question. The level of evidence gap was then calculated by subtracting the actual level of evidence of the manuscript from the level of evidence of the idealized study. Of the 64 JBJS-Am manuscripts eligible for analysis, the average level of evidence was between Level II and III (mean, 2.73). The average level of evidence gap was 1.06 compared with the JBJS-Am-designated level of evidence and 1.28 compared with the evaluators' assessment. Because not all questions require Level I studies, level of evidence alone may not be the best metric for the quality of orthopedic surgery literature. Instead, the authors' concept of a level of evidence gap may be a better tool for assessing the state of orthopedic research publications.

  11. Synthesis and optical properties of dendrite-like GaP nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Haihui [School of Chemical Engineering, Shandong Institute of light Industry, Jinan 250353 (China); Gai Ligang, E-mail: liganggai@yahoo.com [School of Chemical Engineering, Shandong Institute of light Industry, Jinan 250353 (China); Liu Yugao [School of Mechanical and Electrical Engineering, Qingdao Agricultural University, Qingdao 266109 (China)

    2010-06-15

    Dendrite-like GaP nanostructures have been prepared at low temperature via a solvothermal route using mesoporous silica SBA-15 microparticles (SMP) with surface channels as the structure-directing agent. The samples were characterized with X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), diffuse reflection ultraviolet-visible (UV-vis) spectroscopy, and room-temperature photoluminescence. The formation mechanism and optical properties of the dendrites are discussed.

  12. The dynamics of latifundia formation.

    Science.gov (United States)

    Chaves, Luis Fernando

    2013-01-01

    Land tenure inequity is a major social problem in developing nations worldwide. In societies, where land is a commodity, inequities in land tenure are associated with gaps in income distribution, poverty and biodiversity loss. A common pattern of land tenure inequities through the history of civilization has been the formation of latifundia [Zhuāngyuán in chinese], i.e., a pattern where land ownership is concentrated by a small fraction of the whole population. Here, we use simple Markov chain models to study the dynamics of latifundia formation in a heterogeneous landscape where land can transition between forest, agriculture and recovering land. We systematically study the likelihood of latifundia formation under the assumption of pre-capitalist trade, where trade is based on the average utility of land parcels belonging to each individual landowner during a discrete time step. By restricting land trade to that under recovery, we found the likelihood of latifundia formation to increase with the size of the system, i.e., the amount of land and individuals in the society. We found that an increase of the transition rate for land use changes, i.e., how quickly land use changes, promotes more equitable patterns of land ownership. Disease introduction in the system, which reduced land profitability for infected individual landowners, promoted the formation of latifundia, with an increased likelihood for latifundia formation when there were heterogeneities in the susceptibility to infection. Finally, our model suggests that land ownership reforms need to guarantee an equitative distribution of land among individuals in a society to avoid the formation of latifundia.

  13. The dynamics of latifundia formation.

    Directory of Open Access Journals (Sweden)

    Luis Fernando Chaves

    Full Text Available Land tenure inequity is a major social problem in developing nations worldwide. In societies, where land is a commodity, inequities in land tenure are associated with gaps in income distribution, poverty and biodiversity loss. A common pattern of land tenure inequities through the history of civilization has been the formation of latifundia [Zhuāngyuán in chinese], i.e., a pattern where land ownership is concentrated by a small fraction of the whole population. Here, we use simple Markov chain models to study the dynamics of latifundia formation in a heterogeneous landscape where land can transition between forest, agriculture and recovering land. We systematically study the likelihood of latifundia formation under the assumption of pre-capitalist trade, where trade is based on the average utility of land parcels belonging to each individual landowner during a discrete time step. By restricting land trade to that under recovery, we found the likelihood of latifundia formation to increase with the size of the system, i.e., the amount of land and individuals in the society. We found that an increase of the transition rate for land use changes, i.e., how quickly land use changes, promotes more equitable patterns of land ownership. Disease introduction in the system, which reduced land profitability for infected individual landowners, promoted the formation of latifundia, with an increased likelihood for latifundia formation when there were heterogeneities in the susceptibility to infection. Finally, our model suggests that land ownership reforms need to guarantee an equitative distribution of land among individuals in a society to avoid the formation of latifundia.

  14. Galaxy Formation

    CERN Document Server

    Longair, Malcolm S

    2008-01-01

    This second edition of Galaxy Formation is an up-to-date text on astrophysical cosmology, expounding the structure of the classical cosmological models from a contemporary viewpoint. This forms the background to a detailed study of the origin of structure and galaxies in the Universe. The derivations of many of the most important results are derived by simple physical arguments which illuminate the results of more advanced treatments. A very wide range of observational data is brought to bear upon these problems, including the most recent results from WMAP, the Hubble Space Telescope, galaxy surveys like the Sloan Digital Sky Survey and the 2dF Galaxy Redshift Survey, studies of Type 1a supernovae, and many other observations.

  15. [The gender gap in Italian medicine].

    Science.gov (United States)

    De Simone, Silvia; Podda, Daiana; Lampis, Jessica

    2015-01-28

    This study is collocated in the debate about the gender gap in Medicine giving voice to female physicians who have damaged the "glass ceiling". Our research offers a contribute to the exploration about the motivations of persistence of gender gap in Medicine despite current changes. This study is based on 21 biographical interviews to female physicians who are managers in Italian hospitals. The themes emerged by data analysis concerned the participants 'discrimination experiences in their hierarchical advancement, the evidences of a persistence of horizontal segregation in some medical specializations, the difficult to find a work-life balance and the effects of this difficult on the female physicians' health. Our research confirmed a persistence of gender gap in the medical world, which disadvantages women in their career choices and in their hierarchical advancement and which appears in the form of invisible barriers impregnated of stereotypes and prejudices that are taken for granted by many men and women, especially those who have the power; these barriers make the female doctors 'health more vulnerable to the event of work-related stress. By the dates emerged the necessity of cultural and institutional interventions, actions for deconstruction of gender stereotypes, and the necessity of intervention for a more flexible and functioning work organization that satisfies the female physicians' needs.

  16. Invited review: Small GTPases and their GAPs.

    Science.gov (United States)

    Mishra, Ashwini K; Lambright, David G

    2016-08-01

    Widespread utilization of small GTPases as major regulatory hubs in many different biological systems derives from a conserved conformational switch mechanism that facilitates cycling between GTP-bound active and GDP-bound inactive states under control of guanine nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs), which accelerate slow intrinsic rates of activation by nucleotide exchange and deactivation by GTP hydrolysis, respectively. Here we review developments leading to current understanding of intrinsic and GAP catalyzed GTP hydrolytic reactions in small GTPases from structural, molecular and chemical mechanistic perspectives. Despite the apparent simplicity of the GTPase cycle, the structural bases underlying the hallmark hydrolytic reaction and catalytic acceleration by GAPs are considerably more diverse than originally anticipated. Even the most fundamental aspects of the reaction mechanism have been challenging to decipher. Through a combination of experimental and in silico approaches, the outlines of a consensus view have begun to emerge for the best studied paradigms. Nevertheless, recent observations indicate that there is still much to be learned. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 431-448, 2016.

  17. Gap junction channels and cardiac impulse propagation.

    Science.gov (United States)

    Desplantez, Thomas; Dupont, Emmanuel; Severs, Nicholas J; Weingart, Robert

    2007-08-01

    The role of gap junction channels on cardiac impulse propagation is complex. This review focuses on the differential expression of connexins in the heart and the biophysical properties of gap junction channels under normal and disease conditions. Structural determinants of impulse propagation have been gained from biochemical and immunocytochemical studies performed on tissue extracts and intact cardiac tissue. These have defined the distinctive connexin coexpression patterns and relative levels in different cardiac tissues. Functional determinants of impulse propagation have emerged from electrophysiological experiments carried out on cell pairs. The static properties (channel number and conductance) limit the current flow between adjacent cardiomyocytes and thus set the basic conduction velocity. The dynamic properties (voltage-sensitive gating and kinetics of channels) are responsible for a modulation of the conduction velocity during propagated action potentials. The effect is moderate and depends on the type of Cx and channel. For homomeric-homotypic channels, the influence is small to medium; for homomeric-heterotypic channels, it is medium to strong. Since no data are currently available on heteromeric channels, their influence on impulse propagation is speculative. The modulation by gap junction channels is most prominent in tissues at the boundaries between cardiac tissues such as sinoatrial node-atrial muscle, atrioventricular node-His bundle, His bundle-bundle branch and Purkinje fibers-ventricular muscle. The data predict facilitation of orthodromic propagation.

  18. Ion-gap sensing for engine control

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-09-01

    This article reports that in addition to detecting misfire to conform with California onboard diagnostic (OBD II) regulations, Delco Electronics and Mecel AB engineers are looking at ion-gap sensing to control knock, A/F ratio, and other possible engine control parameters. The combustion of fuel in an engine cylinder produces ions. Detection of those ions by the spark plug (ion-gap sensing), and use of the resulting ion currents, has been employed in engine management systems since 1988. Saab introduced the first application, for cam-phase sensing. The main driving force for ion-gap sensing is OBD II requirements for 100% misfire detection at all speeds and loads. The technique has been expanded in subsequent applications to include misfire, knock, and pre-ignition detection and control, and more recently in combustion-ion detection using a capacitance-type, ion-current measurement method. Use of the ion current`s wave shape to control knock allows elimination of the separate piezoelectric type (PZT) sensor. Future applications could provide additional engine-control features including air/fuel ratio measurement and control.

  19. Gap Junctions: The Claymore for Cancerous Cells

    Directory of Open Access Journals (Sweden)

    Ailar Nakhlband

    2011-07-01

    Full Text Available Introduction: Gap junctions play an important role in the cell proliferation in mammalian cells as well as carcinogenesis. However, there are controversial issues about their role in cancer pathogenesis. This study was designed to evaluate genotoxicity and cytotoxicity of Carbenoxolone (CBX as a prototype of inter-cellular gap junction blocker in MCF7 and BT20 human breast cancer cells. Methods: The MCF7and BT20 human breast cancer cell lines were cultivated, and treated at designated confluency with different doses of CBX. Cellular cytotoxicity was examined using standard colorimetric assay associated with cell viability tests. Gene expression evaluation was carried out using real time polymerase chain reaction (PCR. Results: MCF7 and BT20 cells were significantly affected by CBX in a dose dependent manner in cell viability assays. Despite varying expression of genes, down regulation of pro- and anti-apoptotic genes was observed in these cells. Conclusion: Based upon this investigation, it can be concluded that CBX could affect both low and high proliferative types of breast cancer cell lines and disproportionate down regulation of both pre- and anti-apoptotic genes may be related to interacting biomolecules, perhaps via gap junctions.

  20. Effects of coverage gap reform on adherence to diabetes medications.

    Science.gov (United States)

    Zeng, Feng; Patel, Bimal V; Brunetti, Louis

    2013-04-01

    To investigate the impact of Part D coverage gap reform on diabetes medication adherence. Retrospective data analysis based on pharmacy claims data from a national pharmacy benefit manager. We used a difference-in-difference-indifference method to evaluate the impact of coverage gap reform on adherence to diabetes medications. Two cohorts (2010 and 2011) were constructed to represent the last year before Affordable Care Act (ACA) reform and the first year after reform, respectively. Each patient had 2 observations: 1 before and 1 after entering the coverage gap. Patients in each cohort were divided into groups based on type of gap coverage: no coverage, partial coverage (generics only), and full coverage. Following ACA reform, patients with no gap coverage and patients with partial gap coverage experienced substantial drops in copayments in the coverage gap in 2011. Their adherence to diabetes medications in the gap, measured by percentage of days covered, improved correspondingly (2.99 percentage points, 95% confidence interval [CI] 0.49-5.48, P = .019 for patients with no coverage; 6.46 percentage points, 95% CI 3.34-9.58, P gap in 2011. However, their adherence did not increase (-0.13 percentage point, P = .8011). In the first year of ACA coverage gap reform, copayments in the gap decreased substantially for all patients. Patients with no coverage and patients with partial coverage in the gap had better adherence in the gap in 2011.

  1. Planet Formation with Migration

    CERN Document Server

    Chambers, J E

    2006-01-01

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

  2. Gap Dynamics and the Maintenance of Biodiversity%林窗与生物多样性维持

    Institute of Scientific and Technical Information of China (English)

    梁晓东; 叶万辉; 蚁伟民

    2001-01-01

    This paper reviewed the concept,formation and function of gap and developed a new concept,canopy rift.It refers to the small 1-25m2 rift in the canopy caused by the different distribution pattern of the canopy species or breakage,standing death and treefall.Canopy gap,mainly caused by small-scale disturbances including natural disturbance regime and human disturbance regime,is an important phase in the forest regeneration cycle.It plays a leading role in the formation and maintenance of the patches mosaic structure in a forest community.Corresponding to the three phases of the forest regeneration cycle,patches can be classified into three types:gap phase,building phase and mature forest.Many factors may contribute to the maintenance of biodiversity.Here we divided them into ① intrinsic factors,mainly including the biological and ecological characteristics of the species and ② external factors,the heterogeneity of habitat.The formation of gaps leads to the diversification of micro-environment,and changes the type and magnitude of understory.Gap impacts the forest micro-environment,community structure and dynamic process.Gap causes different status of renewal between pioneer species and climax species,and generates the patch which is the different in the constitute of woods,population dynamic and growing speed.It leads to the diversity of community difference and species component,which is the difference of species between community patches.Gap is of great significance in enhancing and maintaining species diversity for it may enhance habitat heterogeneity.

  3. Outcome of rail fixator system in reconstructing bone gap

    Directory of Open Access Journals (Sweden)

    Amit Lakhani

    2014-01-01

    Conclusion: All patients well tolerated rail fixator with good functional results and gap reconstruction. Easy application of rail fixator and comfortable distraction procedure suggest rail fixator a good alternative for gap reconstruction of limbs.

  4. Charge Distribution Dependency on Gap Thickness of CMS Endcap RPC

    CERN Document Server

    Park, Sung K; Lee, Kyongsei

    2016-01-01

    We report a systematic study of charge distribution dependency of CMS Resistive Plate Chamber (RPC) on gap thickness. Prototypes of double-gap RPCs with six different gap thickness ranging from from 1.0 to 2.0 mm in 0.2-mm steps have been built with 2-mm-thick phenolic high-pressure-laminated plates. The efficiencies of the six gaps are measured as a function of the effective high voltages. We report that the strength of the electric fields of the gap is decreased as the gap thickness is increased. The distributions of charges in six gaps are measured. The space charge effect is seen in the charge distribution at the higher voltages. The logistic function is used to fit the charge distribution data. Smaller charges can be produced within smaller gas gap. But the digitization threshold should be also lowered to utilize these smaller charges.

  5. ROSS Skills, Knowledge, and Abilities Training Evaluation. Gaps and Recommendations

    Energy Technology Data Exchange (ETDEWEB)

    Ala, Maureen [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Gruidl, Jeremiah [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Buddemeier, Brooke [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-09-30

    This document describes the development of the ROSS SKAs, the cross-mapping of the SKAs to the available training, identifies gaps in the SKA and training, and provides recommendations to address those gaps.

  6. Vehicle Codes and Standards: Overview and Gap Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Blake, C.; Buttner, W.; Rivkin, C.

    2010-02-01

    This report identifies gaps in vehicle codes and standards and recommends ways to fill the gaps, focusing on six alternative fuels: biodiesel, natural gas, electricity, ethanol, hydrogen, and propane.

  7. Effects of topography, soil type and forest age on the frequency and size distribution of canopy gap disturbances in a tropical forest

    Directory of Open Access Journals (Sweden)

    E. Lobo

    2013-04-01

    Full Text Available Treefall gaps are the major source of disturbance in most tropical forests. The frequency and size of these gaps have important implications for forest ecosystem processes as they can influence the functional trait distribution of tree communities, stand-level above-ground biomass and productivity. However, we still know little about the relative importance of environmental drivers of gap disturbance regimes because existing studies vary greatly in criteria used for defining gaps, in the spatial extent of the study area, and the spatial resolution of canopy height measurements. Here we use LiDAR (light detecting and ranging to explore how forest age, topography and soil type affect canopy disturbance patterns across a 1500 ha tropical forest landscape in central Panama. We characterize disturbance based on the frequency distribution of gap sizes (the "gap size distribution", and the area of the forest affected by gaps (the "gap area fraction". We found that slope and forest age had significant effects on the gap size distribution, with a higher frequency of large gaps associated with old-growth forests and more gentle slopes. Slope and forest age had similar effects on the gap area fraction, however gap area fraction was also affected by soil type and by aspect. We conclude that variation in disturbance patterns across the landscape can be linked to factors that act at the fine scale (such as aspect or slope, and factors that show heterogeneity at coarser scales (such as forest age or soil type. Awareness of the role of different environmental factors influencing gap formation can help scale-up the impacts of canopy disturbance on forest communities measured at the plot scale to landscape and regional scales.

  8. Wage gap between men and women in Tunisia

    OpenAIRE

    Jeddi, Hela; Malouche, Dhafer

    2015-01-01

    This paper focuses on estimating wage differences between males and females in Tunisia by using the Oaxaca-Blinder decomposition, a technical that isolates wage gap due to characteristics, from wage gap due to discrimination against women. The data used in the analysis is obtained from the Tunisian Population and Employment Survey 2005. It is estimated that, the gender wage gap is about 19% and the results ascertain that the gender wage gap is mostly attributed to discrimination, especially t...

  9. Development of narrow gap welding technology for extremely thick steel

    Science.gov (United States)

    Imai, K.; Saito, T.; Okumura, M.

    In the field of extremely thick steel, various narrow gap welding methods were developed on the basis of former welding methods and are used in practice. It is important to develop and improve automatic narrow gap welding, J edge preparation by gas cutting, the prevention of welding defects, wires for narrow gap welding and so on in order to expand the scope of application of the method. Narrow gap welding technologies are described, based on new concepts developed by Nippon Steel Corporation.

  10. The gap year for geographers:effects and paradoxes

    OpenAIRE

    Blackburn, Alan; Clark, Gordon; Pilgrim, David

    2005-01-01

    This paper examines why the growing gap-year phenomenon is important for university geography departments in the context of education and employment. The research examines the scale and types of gap years, and their effects on students. The study uses a multi-actor approach comprising information from national statistical sources, university departments, students who have taken gap years and commercial gap-year providers. The paper draws some lessons for geography departments such as the need...

  11. Information Interaction as a Mechanism of Semantic Gap Elimination

    Directory of Open Access Journals (Sweden)

    Victor Y. Tsvetkov

    2013-01-01

    Full Text Available The article studies semantic gap as an objective phenomenon, shows that semantic gap occurs both in parallel computing and in other areas. Semantic description of the content is revealed as a set of different descriptions. Causes of semantic gap are described. The content of information exchange is explained in the article. Information interaction in the semantic field is interpreted as a mechanism to lessen the gap

  12. Fundamental Gaps in Numerical Semigroups with Respect to Their Multiplicity

    Institute of Scientific and Technical Information of China (English)

    J.C.ROSALES; P.A.GARC(I)A-S(A)NCHEZ; J.I.GARC(I)A-GARC(I)A; J.A.JIM(E)NEZ MADRID

    2004-01-01

    For a numerical semigroup, we introduce the concept of a fundamental gap with respect to the multiplicity of the semigroup. The semigroup is fully determined by its multiplicity and these gaps. We study the case when a set of non-negative integers is the set of fundamental gaps with respect to the multiplicity of a numerical semigroup. Numerical semigroups with maximum and minimum number of this kind of gaps are described.

  13. {ital In Situ} Band Gap Engineering of Carbon Nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Crespi, V.H.; Cohen, M.L. [Department of Physics, University of California at Berkeley, Berkeley, California 94720, and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Rubio, A. [Departamento de Fisica Teorica, Universidad de Valladolid, E-47011 Valladolid (Spain)

    1997-09-01

    Bond rotation defects close the gap in large-gap nanotubes, open the gap in small-gap nanotubes, and increase the density of states in metallic nanotubes. Not only are these defects likely to be present in as-grown nanotubes, but they could be introduced locally into intact nanotubes, thereby opening a new road towards device applications. {copyright} {ital 1997} {ital The American Physical Society}

  14. Pattern Formation

    Science.gov (United States)

    Hoyle, Rebecca

    2006-03-01

    From the stripes of a zebra and the spots on a leopard's back to the ripples on a sandy beach or desert dune, regular patterns arise everywhere in nature. The appearance and evolution of these phenomena has been a focus of recent research activity across several disciplines. This book provides an introduction to the range of mathematical theory and methods used to analyse and explain these often intricate and beautiful patterns. Bringing together several different approaches, from group theoretic methods to envelope equations and theory of patterns in large-aspect ratio-systems, the book also provides insight behind the selection of one pattern over another. Suitable as an upper-undergraduate textbook for mathematics students or as a fascinating, engaging, and fully illustrated resource for readers in physics and biology, Rebecca Hoyle's book, using a non-partisan approach, unifies a range of techniques used by active researchers in this growing field. Accessible description of the mathematical theory behind fascinating pattern formation in areas such as biology, physics and materials science Collects recent research for the first time in an upper level textbook Features a number of exercises - with solutions online - and worked examples

  15. Gamma-ray Emission from the Vela Pulsar Modeled with the Annular Gap and Core Gap

    CERN Document Server

    Du, Y J; Qiao, G J; Chou, C K

    2011-01-01

    The Vela pulsar represents a distinct group of {\\gamma}-ray pulsars. Fermi {\\gamma}-ray observations reveal that it has two sharp peaks (P1 and P2) in the light curve with a phase separation of 0.42 and a third peak (P3) in the bridge. The location and intensity of P3 are energy-dependent. We use the 3D magnetospheric model for the annular gap and core gap to simulate the {\\gamma}-ray light curves, phase-averaged and phase-resolved spectra. We found that the acceleration electric field along a field line in the annular gap region decreases with heights. The emission at high energy GeV band is originated from the curvature radiation of accelerated primary particles, while the synchrotron radiation from secondary particles have some contributions to low energy {\\gamma}-ray band (0.1 - 0.3 GeV). The {\\gamma}-ray light curve peaks P1 and P2 are generated in the annular gap region near the altitude of null charge surface, whereas P3 and the bridge emission is generated in the core gap region. The intensity and loc...

  16. Seasonal bird use of canopy gaps in a bottomland forest.

    Energy Technology Data Exchange (ETDEWEB)

    Bowen, Liessa, T,; Moorman, Christopher, E.; Kilgo, John, C.

    2007-04-01

    ABSTRACT.—Bird use of small canopy gaps within mature forests has not been well studied, particularly across multiple seasons. We investigated seasonal differences in bird use of gap and forest habitat within a bottomland hardwood forest in the Upper Coastal Plain of South Carolina. Gaps were 0.13- to 0.5-ha, 7- to 8-year-old group-selection timber harvest openings. Our study occurred during four bird-use periods (spring migration, breeding, postbreeding, and fall migration) in 2001 and 2002. We used plot counts and mist netting to estimate bird abundance in canopy gaps and surrounding mature forest habitats. Using both survey methods, we observed more birds, including forest-interior species, forest-edge species, field-edge species, and several individual species in canopy gap and gap-edge habitats than in surrounding mature forest during all periods. Interactions between period and habitat type often were significant in models, suggesting a seasonal shift in habitat use. Bird activity generally shifted between the interior of canopy gaps and the immediate gap edge, but many species increased their use of forested habitat during the breeding period. This suggests that many species of birds selectively choose gap and gap-edge habitat over surrounding mature forest during the non-breeding period. Creation of small canopy gaps within a mature forest may increase local bird species richness. The reasons for increased bird activity in gaps remain unclear.

  17. Jumping across the gap - a series of atrial extrastimuli.

    Science.gov (United States)

    Swamy, Mahadeva; Katyal, Deepak; Raja J, Kaushal

    2015-01-01

    The "gap phenomenon" is an interesting phenomenon in electrophysiology arising from the differences in refractory periods at two or more levels of the atrioventricular (AV) conduction system. We present a patient with dual AV nodal physiology in whom the AH jump mediates the gap phenomenon. We also briefly discuss the other mechanisms of gap phenomenon that have been described in this setting.

  18. Amodal completion with background determines depth from monocular gap stereopsis.

    Science.gov (United States)

    Grove, Philip M; Ben Sachtler, W L; Gillam, Barbara J

    2006-10-01

    Grove, Gillam, and Ono [Grove, P. M., Gillam, B. J., & Ono, H. (2002). Content and context of monocular regions determine perceived depth in random dot, unpaired background and phantom stereograms. Vision Research, 42, 1859-1870] reported that perceived depth in monocular gap stereograms [Gillam, B. J., Blackburn, S., & Nakayama, K. (1999). Stereopsis based on monocular gaps: Metrical encoding of depth and slant without matching contours. Vision Research, 39, 493-502] was attenuated when the color/texture in the monocular gap did not match the background. It appears that continuation of the gap with the background constitutes an important component of the stimulus conditions that allow a monocular gap in an otherwise binocular surface to be responded to as a depth step. In this report we tested this view using the conventional monocular gap stimulus of two identical grey rectangles separated by a gap in one eye but abutting to form a solid grey rectangle in the other. We compared depth seen at the gap for this stimulus with stimuli that were identical except for two additional small black squares placed at the ends of the gap. If the squares were placed stereoscopically behind the rectangle/gap configuration (appearing on the background) they interfered with the perceived depth at the gap. However when they were placed in front of the configuration this attenuation disappeared. The gap and the background were able under these conditions to complete amodally.

  19. Better Gas-Gap Thermal Switches For Sorption Compressors

    Science.gov (United States)

    Bhandari, Pradeep; Rodriguez, Jose

    1995-01-01

    Gas-gap thermal switches associated with sorption compressors of some heat pumps and cryogenic systems designed for higher performance, according to proposal, by introducing controlled turbulent flows into gas gaps. Utilizes convection in turbulent flow to transfer heat at greater rate. Design takes advantage of flow of working fluid. Working fluid also serve as heat transfer medium in gas gap.

  20. Causes of and Solutions to the Achievement Gap: Teachers' Perceptions

    Science.gov (United States)

    Ratcliff, Nancy J.; Costner, Richard H.; Carroll, Kimberly L.; Jones, Cathy R.; Sheehan, Heather Chase; Hunt, Gilbert H.

    2016-01-01

    Survey results from 874 educators regarding the achievement gap are shared. The importance of the achievement gap, causes of and solutions to the achievement gap, and performance expectations for students in their schools are explored. Implications for teacher educators are discussed as related to both pre-service and in-service training programs.

  1. Narrowing the Achievement Gap: Perspectives and Strategies for Challenging Times

    Science.gov (United States)

    Timar, Thomas B., Ed.; Maxwell-Jolly, Julie, Ed.

    2012-01-01

    This timely and thoughtful book provides multiple perspectives on closing achievement gaps. Closing persistent gaps in educational outcomes between different groups of students has been a central goal of educational policy for the past forty years. The commitment to close existing achievement gaps poses an unprecedented challenge to policy makers,…

  2. Plasmon-enhanced water splitting on TiO2-passivated GaP photocatalysts.

    Science.gov (United States)

    Qiu, Jing; Zeng, Guangtong; Pavaskar, Prathamesh; Li, Zhen; Cronin, Stephen B

    2014-02-21

    Integrating plasmon resonant nanostructures with photocatalytic semiconductors shows great promise for high efficiency photocatalytic water splitting. However, the electrochemical instability of most III-V semiconductors severely limits their applicability in photocatalysis. In this work, we passivate p-type GaP with a thin layer of n-type TiO2 using atomic layer deposition. The TiO2 passivation layer prevents corrosion of the GaP, as evidenced by atomic force microscopy and photoelectrochemical measurements. In addition, the TiO2 passivation layer provides an enhancement in photoconversion efficiency through the formation of a charge separating pn-region. Plasmonic Au nanoparticles deposited on top of the TiO2-passivated GaP further increases the photoconversion efficiency through local field enhancement. These two enhancement mechanisms are separated by systematically varying the thickness of the TiO2 layer. Because of the tradeoff between the quickly decaying plasmonic fields and the formation of the pn-charge separation region, an optimum performance is achieved for a TiO2 thickness of 0.5 nm. Finite difference time domain (FDTD) simulations of the electric field profiles in this photocatalytic heterostructure corroborate these results. The effects of plasmonic enhancement are distinguished from the natural catalytic properties of Au by evaluating similar photocatalytic TiO2/GaP structures with catalytic, non-plasmonic metals (i.e., Pt) instead of Au. This general approach of passivating narrower band gap semiconductors enables a wider range of materials to be considered for plasmon-enhanced photocatalysis for high efficiency water splitting.

  3. The gender earnings gap among pharmacists.

    Science.gov (United States)

    Carvajal, Manuel J; Armayor, Graciela M; Deziel, Lisa

    2012-01-01

    A gender earnings gap exists across professions. Compared with men, women earn consistently lower income levels. The determinants of wages and salaries should be explored to assess whether a gender earnings gap exists in the pharmacy profession. The objectives of this study were to (1) compare the responses of male and female pharmacists' earnings with human-capital stock, workers' preferences, and opinion variables and (2) assess whether the earnings determination models for male and female pharmacists yielded similar results in estimating the wage-and-salary gap through earnings projections, the influence of each explanatory variable, and gender differences in statistical significance. Data were collected through the use of a 37-question survey mailed to registered pharmacists in South Florida, United States. Earnings functions were formulated and tested separately for male and female pharmacists using unlogged and semilog equation forms. Number of hours worked, human-capital stock, job preferences, and opinion variables were hypothesized to explain wage-and-salary differentials. The empirical evidence led to 3 major conclusions: (1) men's and women's earnings sometimes were influenced by different stimuli, and when they responded to the same variables, the effect often was different; (2) although the influence of some explanatory variables on earnings differed in the unlogged and semilog equations, the earnings projections derived from both equation forms for male and female pharmacists were remarkably similar and yielded nearly identical male-female earnings ratios; and (3) controlling for number of hours worked, human-capital stock, job preferences, and opinion variables reduced the initial unadjusted male-female earnings ratios only slightly, which pointed toward the presence of gender bias. After controlling for human-capital stock, job-related characteristics, and opinion variables, male pharmacists continued to earn higher income levels than female

  4. Mango: multiple alignment with N gapped oligos.

    Science.gov (United States)

    Zhang, Zefeng; Lin, Hao; Li, Ming

    2008-06-01

    Multiple sequence alignment is a classical and challenging task. The problem is NP-hard. The full dynamic programming takes too much time. The progressive alignment heuristics adopted by most state-of-the-art works suffer from the "once a gap, always a gap" phenomenon. Is there a radically new way to do multiple sequence alignment? In this paper, we introduce a novel and orthogonal multiple sequence alignment method, using both multiple optimized spaced seeds and new algorithms to handle these seeds efficiently. Our new algorithm processes information of all sequences as a whole and tries to build the alignment vertically, avoiding problems caused by the popular progressive approaches. Because the optimized spaced seeds have proved significantly more sensitive than the consecutive k-mers, the new approach promises to be more accurate and reliable. To validate our new approach, we have implemented MANGO: Multiple Alignment with N Gapped Oligos. Experiments were carried out on large 16S RNA benchmarks, showing that MANGO compares favorably, in both accuracy and speed, against state-of-the-art multiple sequence alignment methods, including ClustalW 1.83, MUSCLE 3.6, MAFFT 5.861, ProbConsRNA 1.11, Dialign 2.2.1, DIALIGN-T 0.2.1, T-Coffee 4.85, POA 2.0, and Kalign 2.0. We have further demonstrated the scalability of MANGO on very large datasets of repeat elements. MANGO can be downloaded at http://www.bioinfo.org.cn/mango/ and is free for academic usage.

  5. Microwave resonant activation in hybrid single-gap/two-gap Josephson tunnel junctions

    Science.gov (United States)

    Carabello, Steven; Lambert, Joseph G.; Mlack, Jerome; Dai, Wenqing; Li, Qi; Chen, Ke; Cunnane, Daniel; Xi, X. X.; Ramos, Roberto C.

    2016-09-01

    Microwave resonant activation is a powerful, straightforward technique to study classical and quantum systems, experimentally realized in Josephson junction devices cooled to very low temperatures. These devices typically consist of two single-gap superconductors separated by a weak link. We report the results of the first resonant activation experiments on hybrid thin film Josephson junctions consisting of a multi-gap superconductor (MgB2) and a single-gap superconductor (Pb or Sn). We can interpret the plasma frequency in terms of theories both for conventional and hybrid junctions. Using these models, we determine the junction parameters including critical current, resistance, and capacitance and find moderately high quality factors of Q0˜ 100 for these junctions.

  6. Electron Elevator: Excitations across the Band Gap via a Dynamical Gap State.

    Science.gov (United States)

    Lim, A; Foulkes, W M C; Horsfield, A P; Mason, D R; Schleife, A; Draeger, E W; Correa, A A

    2016-01-29

    We use time-dependent density functional theory to study self-irradiated Si. We calculate the electronic stopping power of Si in Si by evaluating the energy transferred to the electrons per unit path length by an ion of kinetic energy from 1 eV to 100 keV moving through the host. Electronic stopping is found to be significant below the threshold velocity normally identified with transitions across the band gap. A structured crossover at low velocity exists in place of a hard threshold. An analysis of the time dependence of the transition rates using coupled linear rate equations enables one of the excitation mechanisms to be clearly identified: a defect state induced in the gap by the moving ion acts like an elevator and carries electrons across the band gap.

  7. The mass gap and its applications

    CERN Document Server

    Gogokhia, Vakhtang; Barnafoldi, Gergely Gabor

    2013-01-01

    Quantum Chromodynamics (QCD) is the most up-to-date theory of the strong interaction. Its predictions have been verified experimentally, and it is a cornerstone of the Standard Model of particle physics. However, standard perturbative procedures fail if applied to low-energy QCD. Even the discovery of the Higgs Boson will not solve the problem of masses originating from the non-perturbative behavior of QCD.This book presents a new method, the introduction of the 'mass gap', first suggested by Arthur Jaffe and Edward Witten at the turn of the millennium. It attempts to show that, to explain the

  8. The band-gap enhanced photovoltaic structure

    Science.gov (United States)

    Tessler, Nir

    2016-05-01

    We critically examine the recently suggested structure that was postulated to potentially add 50% to the photo-conversion efficiency of organic solar cells. We find that the structure could be realized using stepwise increase in the gap as long as the steps are not above 0.1 eV. We also show that the charge extraction is not compromised due to an interplay between the contact's space charge and the energy level modification, which result in a flat energy band at the extracting contact.

  9. Dispersion of coupled mode-gap cavities

    CERN Document Server

    Lian, Jin; Yüce, Emre; De Rossi, Sylvain Combrié Alfredo; Mosk, Allard P

    2015-01-01

    The dispersion of a CROW made of photonic crystal mode-gap cavities is pronouncedly asymmetric. This asymmetry cannot be explained by the standard tight binding model. We show that the fundamental cause of the asymmetric dispersion is the fact that the cavity mode profile itself is dispersive, i.e., the mode wave function depends on the driving frequency, not the eigenfrequency. This occurs because the photonic crystal cavity resonances do not form a complete set. By taking into account the dispersive mode profile, we formulate a mode coupling model that accurately describes the asymmetric dispersion without introducing any new free parameters.

  10. Energy gap in concentrated spin glasses

    Energy Technology Data Exchange (ETDEWEB)

    Liao, S.B.; Bhagat, S.M.; Manheimer, M.A.; Moorjani, K.

    1988-04-15

    Using magnetic resonance data at several frequencies, we have obtained the temperature dependence of the field-induced magnetization (M) in three concentrated spin glasses. At every frequency, M is independent of T for Tapprox. gap energy with values close to the corresponding Curie--Weiss temperatures theta/sub p/ but much larger than the respective spin-glass transition temperatures T/sub SG/.

  11. Gas gap studies about streamer operated RPCs

    Science.gov (United States)

    Paoloni, A.; Mengucci, A.; Spinetti, M.; Ventura, M.; Votano, L.

    2017-05-01

    The requirement of high rate capability for operation at LHC, led 20 years ago to the achievement of Resistive Plate Chambers operated in avalanche mode, thanks to the introduction of new gas mixtures and to the development of the Front-End electronics. The need for a further increase of the rate capability, in view of the upgrades of LHC, is imposing new detector geometries with thinner gas gaps and electrodes. Streamer operation of RPCs may still be suitable for low rate experiments, and therefore in this paper a comparison between two different detector geometries, the old standard and the newly proposed one, is performed in streamer mode.

  12. Unstructured Randomness, Small Gaps and Localization

    CERN Document Server

    Farhi, Edward; Gosset, David; Gutmann, Sam; Shor, Peter

    2010-01-01

    We study the Hamiltonian associated with the quantum adiabatic algorithm with a random cost function. Because the cost function lacks structure we can prove results about the ground state. We find the ground state energy as the number of bits goes to infinity, show that the minimum gap goes to zero exponentially quickly, and we see a localization transition. We prove that there are no levels approaching the ground state near the end of the evolution. We do not know which features of this model are shared by a quantum adiabatic algorithm applied to random instances of satisfiability since despite being random they do have bit structure.

  13. Overcoming Knowledge Gaps in Postmerger Integration

    DEFF Research Database (Denmark)

    Alaranta, Maria Eliisa; Martela, Eero

    2012-01-01

    Over 50% of mergers and acquisitions (M&As) fail, mainly because of integration problems. In such integrations, much of the experiential (learning-by-doing) knowledge critical for running the business becomes redundant or is lost. However, we know virtually nothing about what type of mechanisms...... best facilitate overcoming the gaps in experiential knowledge in these dynamic hybrid organizational situations. We study a case of integration of software-maintenance processes after a megamerger. In the first phase of the integration, the company combined best features of existing knowledge systems...

  14. Dynamically coupled plasmon-phonon modes in GaP: An indirect-gap polar semiconductor

    Science.gov (United States)

    Ishioka, Kunie; Brixius, Kristina; Höfer, Ulrich; Rustagi, Avinash; Thatcher, Evan M.; Stanton, Christopher J.; Petek, Hrvoje

    2015-11-01

    The ultrafast coupling dynamics of coherent optical phonons and the photoexcited electron-hole plasma in the indirect gap semiconductor GaP are investigated by experiment and theory. For below-gap excitation and probing by 800-nm light, only the bare longitudinal optical (LO) phonons are observed. For above-gap excitation with 400-nm light, the photoexcitation creates a high density, nonequilibrium e -h plasma, which introduces an additional, faster decaying oscillation due to an LO phonon-plasmon coupled (LOPC) mode. The LOPC mode frequency exhibits very similar behavior for both n - and p -doped GaP, downshifting from the LO to the transverse optical (TO) phonon frequency limits with increasing photoexcited carrier density. We assign the LOPC mode to the LO phonons coupled with the photoexcited multicomponent plasma. For the 400-nm excitation, the majority of the photoexcited electrons are scattered from the Γ valley into the satellite X valley, while the light and spin-split holes are scattered into the heavy hole band, within 30 fs. The resulting mixed plasma is strongly damped, leading to the LOPC frequency appearing in the reststrahlen gap. Due to the large effective masses of the X electrons and heavy holes, the coupled mode appears most distinctly at carrier densities ≳5 ×1018cm-3 . We perform theoretical calculations of the nuclear motions and the electronic polarizations following an excitation with an ultrashort optical pulse to obtain the transient reflectivity responses of the coupled modes. We find that, while the longitudinal diffusion of photoexcited carriers is insignificant, the lateral inhomogeneity of the photoexcited carriers due to the laser intensity profile should be taken into account to reproduce the major features of the observed coupled mode dynamics.

  15. Communication: Fragment-based Hamiltonian model of electronic charge-excitation gaps and gap closure.

    Science.gov (United States)

    Valone, S M; Pilania, G; Liu, X Y; Allen, J R; Wu, T-C; Atlas, S R; Dunlap, D H

    2015-11-14

    Capturing key electronic properties such as charge excitation gaps within models at or above the atomic scale presents an ongoing challenge to understanding molecular, nanoscale, and condensed phase systems. One strategy is to describe the system in terms of properties of interacting material fragments, but it is unclear how to accomplish this for charge-excitation and charge-transfer phenomena. Hamiltonian models such as the Hubbard model provide formal frameworks for analyzing gap properties but are couched purely in terms of states of electrons, rather than the states of the fragments at the scale of interest. The recently introduced Fragment Hamiltonian (FH) model uses fragments in different charge states as its building blocks, enabling a uniform, quantum-mechanical treatment that captures the charge-excitation gap. These gaps are preserved in terms of inter-fragment charge-transfer hopping integrals T and on-fragment parameters U((FH)). The FH model generalizes the standard Hubbard model (a single intra-band hopping integral t and on-site repulsion U) from quantum states for electrons to quantum states for fragments. We demonstrate that even for simple two-fragment and multi-fragment systems, gap closure is enabled once T exceeds the threshold set by U((FH)), thus providing new insight into the nature of metal-insulator transitions. This result is in contrast to the standard Hubbard model for 1d rings, for which Lieb and Wu proved that gap closure was impossible, regardless of the choices for t and U.

  16. Communication: Fragment-based Hamiltonian model of electronic charge-excitation gaps and gap closure

    Energy Technology Data Exchange (ETDEWEB)

    Valone, S. M.; Pilania, G.; Liu, X. Y. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Allen, J. R.; Wu, T.-C.; Atlas, S. R.; Dunlap, D. H. [Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

    2015-11-14

    Capturing key electronic properties such as charge excitation gaps within models at or above the atomic scale presents an ongoing challenge to understanding molecular, nanoscale, and condensed phase systems. One strategy is to describe the system in terms of properties of interacting material fragments, but it is unclear how to accomplish this for charge-excitation and charge-transfer phenomena. Hamiltonian models such as the Hubbard model provide formal frameworks for analyzing gap properties but are couched purely in terms of states of electrons, rather than the states of the fragments at the scale of interest. The recently introduced Fragment Hamiltonian (FH) model uses fragments in different charge states as its building blocks, enabling a uniform, quantum-mechanical treatment that captures the charge-excitation gap. These gaps are preserved in terms of inter-fragment charge-transfer hopping integrals T and on-fragment parameters U{sup (FH)}. The FH model generalizes the standard Hubbard model (a single intra-band hopping integral t and on-site repulsion U) from quantum states for electrons to quantum states for fragments. We demonstrate that even for simple two-fragment and multi-fragment systems, gap closure is enabled once T exceeds the threshold set by U{sup (FH)}, thus providing new insight into the nature of metal-insulator transitions. This result is in contrast to the standard Hubbard model for 1d rings, for which Lieb and Wu proved that gap closure was impossible, regardless of the choices for t and U.

  17. Surface band-gap narrowing in quantized electron accumulation layers.

    Science.gov (United States)

    King, P D C; Veal, T D; McConville, C F; Zúñiga-Pérez, J; Muñoz-Sanjosé, V; Hopkinson, M; Rienks, E D L; Jensen, M Fuglsang; Hofmann, Ph

    2010-06-25

    An energy gap between the valence and the conduction band is the defining property of a semiconductor, and the gap size plays a crucial role in the design of semiconductor devices. We show that the presence of a two-dimensional electron gas near to the surface of a semiconductor can significantly alter the size of its band gap through many-body effects caused by its high electron density, resulting in a surface band gap that is much smaller than that in the bulk. Apart from reconciling a number of disparate previous experimental findings, the results suggest an entirely new route to spatially inhomogeneous band-gap engineering.

  18. First study of rapidity gaps in e+e- annihilation

    CERN Document Server

    Abe, K; Ahn, C J; Akagi, T; Allen, N J; Ash, William W; Aston, D; Baird, K G; Baltay, C; Band, H R; Barakat, M B; Baranko, G J; Bardon, O; Barklow, Timothy L; Bazarko, A O; Ben-David, R; Benvenuti, Alberto C; Bienz, T; Bilei, G M; Bisello, D; Blaylock, G; Bogart, J R; Bolton, T; Bower, G R; Brau, J E; Breidenbach, M; Bugg, W M; Burke, D; Burnett, T H; Burrows, P N; Busza, W; Calcaterra, A; Caldwell, D O; Calloway, D H; Camanzi, B; Carpinelli, M; Cassell, R; Castaldi, R; Castro, A; Cavalli-Sforza, M; Church, E; Cohn, H O; Coller, J A; Cook, V; Cotton, R; Cowan, R F; Coyne, D G; de Oliveira, A; Damerell, C J S; Daoudi, M; De Sangro, R; De Simone, P; Dell'Orso, R; Dima, M; Du, P Y C; Dubois, R; Eisenstein, B I; Elia, R; Falciai, D; Fero, M J; Frey, R; Furuno, K; Gillman, T; Gladding, G E; González, S; Hallewell, G D; Hart, E L; Hasegawa, Y; Hedges, S J; Hertzbach, S S; Hildreth, M D; Huber, J; Huffer, M E; Hughes, E W; Hwang, H; Iwasaki, Y; Jackson, D J; Jacques, P; Jaros, J A; Johnson, A S; Johnson, J R; Johnson, R A; Junk, T R; Kajikawa, R; Kalelkar, M S; Kang, H J; Karliner, I; Kawahara, H; Kendall, H W; Kim, Y; King, M E; King, R; Kofler, R R; Krishna, N M; Kroeger, R S; Labs, J F; Langston, M; Lath, A; Lauber, J A; Leith, D W G S; Liu, M X; Liu, X; Loreti, M; Lu, A; Lynch, H L; Ma, J; Mancinelli, G; Manly, S L; Mantovani, G C; Markiewicz, T W; Maruyama, T; Massetti, R; Masuda, H; Mattison, T S; Mazzucato, E; McKemey, A K; Meadows, B T; Messner, R; Mockett, P M; Moffeit, K C; Mours, B; Müller, G; Müller, D; Nagamine, T; Narita, S; Nauenberg, U; Neal, H A; Nussbaum, M; Ohnishi, Y; Osborne, L S; Panvini, R S; Park, H; Pavel, T J; Peruzzi, I; Piccolo, M; Piemontese, L; Pieroni, E; Pitts, K T; Plano, R J; Prepost, R; Prescott, C Y; Punkar, G D; Quigley, J; Ratcliff, B N; Reeves, T W; Reidy, J; Rensing, P E; Rochester, L S; Rothberg, J E; Rowson, P C; Russell, J J; Saxton, O H; Schalk, T L; Schindler, R H; Schumm, B A; Seiden, A; Sen, S; Serbo, V V; Saevitz, M H; Shank, J T; Shapiro, G; Shapiro, S L; Sherden, D J; Shmakov, K D; Simopoulos, C; Sinev, N B; Smith, S R; Snyder, J A; Stamer, P E; Steiner, H; Steiner, R; Strauss, M G; Su, D; Suekane, F; Sugiyama, A; Suzuki, S; Swartz, M; Szumilo, A; Takahashi, T; Taylor, F E; Torrence, E; Turk, J; Usher, T; Vavra, J; Vannini, C; Vella, E N; Venuti, J P; Verdier, R; Verdini, P G; Wagner, S R; Waite, A P; Watts, S J; Weidemann, A W; Weiss, E R; Whitaker, J S; White, S L; Wickens, F J; Williams, D A; Williams, D C; Williams, S H; Willocq, S; Wilson, R J; Wisniewski, W J; Woods, M; Word, G B; Wyss, J; Yamamoto, R K; Yamartino, J M; Yang, X; Yellin, S J; Young, C C; Yuta, H; Zapalac, G H; Zdarko, R W; Zeitlin, C; Zhou, J

    1996-01-01

    We present the first study of rapidity gaps in e+e- annihilations using Z0 decays collected by the SLD experiment at SLAC. Our measured rapidity gap spectra all exponentially with increasing gap size over five decades, and we observe no anomalous class of events containing large gaps. This supports the interpretation of the large-gap events measured in pp and ep collisions in terms of exchange of color-singlet objects. The presence of heavy flavors or additional jets does not affect these conclusions.

  19. Single phase 3D phononic band gap material.

    Science.gov (United States)

    Warmuth, Franziska; Wormser, Maximilian; Körner, Carolin

    2017-06-19

    Phononic band gap materials are capable of prohibiting the propagation of mechanical waves in certain frequency ranges. Band gaps are produced by combining different phases with different properties within one material. In this paper, we present a novel cellular material consisting of only one phase with a phononic band gap. Different phases are modelled by lattice structure design based on eigenmode analysis. Test samples are built from a titanium alloy using selective electron beam melting. For the first time, the predicted phononic band gaps via FEM simulation are experimentally verified. In addition, it is shown how the position and extension of the band gaps can be tuned by utilizing knowledge-based design.

  20. Breakdown localization in the fixed gap system

    CERN Document Server

    Rajamaki, Robin; Wuensch, Walter

    2014-01-01

    Accurate localization of breakdowns in vacuum could help shed light on breakdown related processes that are not yet fully understood. At the DC spark lab at CERN, an instrument called the Fixed Gap System (FGS) has been developed partially for this purpose. Among other things, the FGS has four built-in antennas, which are intended for breakdown localization. The capability of this aspect of the FGS was explored in this report. Specifically, the feasibility of using a method similar to that which is used in cavity Beam Position Monitors (BPMs) was investigated. The usable frequency range of the current experimental setup was also studied. Firstly, a modal analysis of the inner geometry of the FGS was done in HFSS. This showed that the two first modes to be expected in the spark gap quite differ from those of the ideal pillbox – both in field pattern and in frequency ( 4 and 6 GHz vs. 0.2 and 3 GHz). Secondly, S-parameters of the system were measured. These showed that the coupling between antennas is weak...