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  1. Detection of Majorana Kramers pairs using a quantum point contact

    Science.gov (United States)

    Li, Jian; Pan, Wei; Bernevig, B. Andrei; Lutchyn, Roman

    We propose a setup that integrates a quantum point contact (QPC) and a Josephson junction on a quantum spin Hall sample, experimentally realizable in InAs/GaSb quantum wells. The confinement due to both the QPC and the superconductor results in a Kramers pair of Majorana zero-energy bound states when the superconducting phases in the two arms differ by an odd multiple of π across the Josephson junction. We investigate the detection of these Majorana pairs with the integrated QPC, and find a robust switching from normal to Andreev scattering across the edges due to the presence of Majorana Kramers pairs. This transport signature is expected to be exhibited in measurements of differential conductance and/or current cross-correlation at low bias. This work was supported by ONR-N00014-14-1-0330.

  2. Local scale invariances in the bosonic contact and pair-contact processes

    Energy Technology Data Exchange (ETDEWEB)

    Baumann, Florian [Institut fuer Theoretische Physik I, Universitaet Erlangen-Nuernberg, Staudtstrasse 7B3, D-91058 Erlangen (Germany); Laboratoire de Physique des Materiaux , Universite Henri Poincare Nancy I, BP 239, F-54506 Vandoeuvre les Nancy Cedex (France); Stoimenov, Stoimen [Laboratoire de Physique des Materiaux , Universite Henri Poincare Nancy I, BP 239, F-54506 Vandoeuvre les Nancy Cedex (France); Institute of Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, 1784 Sofia (Bulgaria); Henkel, Malte [Laboratoire de Physique des Materiaux , Universite Henri Poincare Nancy I, BP 239, F-54506 Vandoeuvre les Nancy Cedex (France); Isaac Newton Institute of Mathematical Sciences, 20 Clarkson Road, Cambridge CB3 0EH (United Kingdom)

    2006-04-21

    Local scale invariance for ageing systems without detailed balance is tested through studying the dynamical symmetries of the critical bosonic contact process and the critical bosonic pair-contact process. Their field-theoretical actions can be split into a Schroedinger-invariant term and a pure noise term. It is shown that the two-time response and correlation functions are reducible to certain multipoint response functions which depend only on the Schroedinger-invariant part of the action. For the bosonic contact process, the representation of the Schroedinger group can be derived from the free diffusion equation, whereas for the bosonic pair-contact process, a new representation of the Schroedinger group related to a nonlinear Schroedinger equation with dimensionful couplings is constructed. The resulting predictions of local scale invariance for the two-time responses and correlators are completely consistent with the exactly-known results in both models.

  3. Detection of Majorana Kramers Pairs Using a Quantum Point Contact

    Science.gov (United States)

    Li, Jian; Pan, Wei; Bernevig, B. Andrei; Lutchyn, Roman M.

    2016-07-01

    We propose a setup that integrates a quantum point contact (QPC) and a Josephson junction on a quantum spin Hall sample, experimentally realizable in InAs/GaSb quantum wells. The confinement due to both the QPC and the superconductor results in a Kramers pair of Majorana zero-energy bound states when the superconducting phases in the two arms differ by an odd multiple of π across the Josephson junction. We investigate the detection of these Majorana pairs with the integrated QPC, and find a robust switching from normal to Andreev scattering across the edges due to the presence of Majorana Kramers pairs. Such a switching of the current represents a qualitative signature where multiterminal differential conductances oscillate with alternating signs when the external magnetic field is tuned. We show that this qualitative signature is also present in current cross-correlations. Thus, the change of the backscattering current nature affects both conductance and shot noise, the measurement of which offers a significant advantage over quantitative signatures such as conductance quantization in realistic measurements.

  4. CONSIDERATIONS UPON CONTACT STRESS MODELLING IN DENTAL ARTICULATOR PAIRS

    Directory of Open Access Journals (Sweden)

    Carmen Ciornei

    2012-05-01

    Full Text Available A dental articulator is a mechanism which simulates the temporo-mandibular joint. The articulator is essential as it replicates the basic motions of the upper and lower mandibles, both revolve and translational motions. In the present paper the stresses from an articulator TMJ modelled as a bronze sphere into a cylindrical steel cavity are analyzed by two methods, first applying the Hertzian contact theory and then numerically, by means of finite element analysis using the simulation module in CATIA.

  5. Universal scaling behaviour of directed percolation and the pair contact process in an external field

    CERN Document Server

    Lübeck, S

    2002-01-01

    We consider the scaling behaviour of directed percolation and of the pair contact process with a conjugated field. In particular we determine numerically the equation of state and show that both models are characterized by the same universal scaling function. Furthermore we derive the equation of state for the pair contact process within a mean-field approach which again agrees with the mean-field equation of state of the directed percolation universality class.

  6. Paires de structures de contact sur les vari\\'et\\'es de dimension trois

    OpenAIRE

    Colin, Vincent; Firmo, Sebastiao

    2008-01-01

    We introduce a notion of positive pair of contact structures on a 3-manifold which generalizes a previous definition of Eliashberg-Thurston and Mitsumatsu. Such a pair gives rise to a locally integrable plane field $\\lambda$. We prove that if $\\lambda$ is uniquely integrable and if both structures of the pair are tight, then the integral foliation of $\\lambda$ doesn't contain any Reeb component whose core curve is homologous to zero. Moreover, the ambient manifold carries a Reebless foliation...

  7. Influence of the cylindrical gear pairs parameters to the transverse contact ratio

    Directory of Open Access Journals (Sweden)

    Predrag S. Dobratić

    2014-06-01

    Full Text Available In the field of transmission and power transformation from the power engine to the working machine, gear pairs, are mostly used in mechanical engineering due to their compactness of the structure, high reliability and capacity. One way of improving the performance characteristics of gear pairs, and thus the gear transmitters, is to increase the number of simultaneously meshed pairs of teeth, or increasing the transverse contact ratio. To this end, this paper analyzes in detail the partial and simultaneous influence of the number of teeth and tooth profile shapes, moving through shifting coefficient and pressure angle, to the number of simultaneously meshed pairs of teeth. The obtained results allow us to define the optimum parameters of cylindrical gear pairs, in terms of the size of the transverse contact ratio. Introduction The kinematic indicator of the existence of the transmitting continuity of a rotary movement is the total contact ratio. In order to achieve the transmitting continuity of a rotary movement, the total contact ratio must be higher than one. Based on the total contact ratio, the information on the number of simultaneously meshed pairs of the teeth which rotate during the contact period is obtained. For example, if the  – one and two pairs of teeth alternately take turn, and if the  – two and three pairs of teeth alternately take turn, etc. It should be noted that the  is a necessary but not sufficient condition for achieving multiple meshes. The next condition to meet is the compatibility between the accuracy of teeth production, the teeth rigidity and the intensity of the total load of the teeth pair. The influence of the addendum coefficient on the transverse contact ratio is shown in the paper (Li, 2008. It is shown that changes in the addendum coefficient in conjunction with the corresponding values of the shifting coefficient and gear ratio can achieve the transverse contact ratio value higher than four. The paper

  8. Using a surrogate contact pair to evaluate polyethylene wear in prosthetic knee joints.

    Science.gov (United States)

    Sanders, Anthony P; Lockard, Carly A; Weisenburger, Joel N; Haider, Hani; Raeymaekers, Bart

    2016-01-01

    With recent improvements to the properties of ultra-high molecular weight polyethylene (UHMWPE) used in joint replacements, prosthetic knee and hip longevity may extend beyond two decades. However, it is difficult and costly to replicate such a long in vivo lifetime using clinically relevant in vitro wear testing approaches such as walking gait joint simulators. We advance a wear test intermediate in complexity between pin-on-disk and knee joint simulator tests. The test uses a surrogate contact pair, consisting of a surrogate femoral and tibial specimen that replicate the contact mechanics of any full-scale knee condyle contact pair. The method is implemented in a standard multi-directional pin-on-disk wear test machine, and we demonstrate its application via a two-million-cycle wear test of three different UHMWPE formulations. Further, we demonstrate the use of digital photography and image processing to accurately quantify fatigue damage based on the reduced transmission of light through a damage area in a UHMWPE specimen. The surrogate contact pairs replicate the knee condyle contact areas within -3% to +12%. The gravimetric wear test results reflect the dose of crosslinking radiation applied to the UHMWPE: 35 kGy yielded a wear rate of 7.4 mg/Mcycles, 55 kGy yielded 1.0 mg/Mcycles, and 75 kGy (applied to a 0.1% vitamin E stabilized UHMWPE) yielded 1.5 mg/Mcycles. A precursor to spalling fatigue is observed and precisely measured in the radiation-sterilized (35 kGy) and aged UHMWPE specimen. The presented techniques can be used to evaluate the high-cycle fatigue performance of arbitrary knee condyle contact pairs under design-specific contact stresses, using existing wear test machines. This makes the techniques more economical and well-suited to standardized comparative testing.

  9. Effects of the osmolyte TMAO (Trimethylamine-N-oxide) on aqueous hydrophobic contact-pair interactions.

    Science.gov (United States)

    Macdonald, Ryan D; Khajehpour, Mazdak

    2013-12-31

    Osmolytes are small, soluble organic molecules produced by living organisms for maintaining cell volume. These molecules have also been shown to have significant effects on the stability of proteins. Perhaps one of the most studied osmolytes is Trimethylamine-N-oxide (TMAO). Thermodynamic studies of the effects of TMAO on proteins have shown that this molecule is a strong stabilizer of the protein folded state, thus being able to counteract the effects of protein denaturants such as urea and guanidine hydrochloride. Most studies of TMAO effects on bio-molecular stability have until now been focused on how the osmolyte reduces the solubility of polypeptide backbones, while the effects of TMAO on hydrophobic interactions are still not well understood. In fact, there are few experimental data measuring the effect of TMAO on hydrophobic interactions. This work studies phenyl and alkyl contact pairs as model hydrophobic contact pairs. The formation of these contact pairs is monitored using fluorescence, i.e., through the quenching of phenol fluorescence by carboxylate ions; and a methodology is developed to isolate hydrophobic contributions from other interactions. The data demonstrate that the addition of TMAO to the aqueous solvent destabilizes hydrophobic contact pairs formed between alkyl and phenyl moieties. In other words, TMAO acts as a "denaturant" for hydrophobic interactions.

  10. Effects of the protein denaturant guanidinium chloride on aqueous hydrophobic contact-pair interactions.

    Science.gov (United States)

    Macdonald, Ryan D; Khajehpour, Mazdak

    2015-01-01

    Guanidinium chloride (GdmCl) is one of the most common protein denaturants. Although GdmCl is well known in the field of protein folding, the mechanism by which it denatures proteins is not well understood. In fact, there are few studies looking at its effects on hydrophobic interactions. In this work the effect of GdmCl on hydrophobic interactions has been studied by observing how the denaturant influences model systems of phenyl and alkyl hydrophobic contact pairs. Contact pair formation is monitored through the use of fluorescence spectroscopy, i.e., measuring the intrinsic phenol fluorescence being quenched by carboxylate ions. Hydrophobic interactions are isolated from other interactions through a previously developed methodology. The results show that GdmCl does not significantly affect hydrophobic interactions between small moieties such as methyl groups and phenol; while on the other hand, the interaction of larger hydrophobes such as hexyl and heptyl groups with phenol is significantly destabilized.

  11. The Sentiment Trend Analysis of Twitter Based on Set Pair Contact Degree

    Directory of Open Access Journals (Sweden)

    Chunying Zhang

    2013-01-01

    Full Text Available Sentiment trend of twitter users have a great influence on their friends and the crowd listened. This paper directs at the user sentiment state of twitter, the unique medium, and applies set pair analysis method for trend analysis. First, we begin with set pair contact degree, then based on set pair affective computing model to make comparison with the size relationship of same degree, difference degree, opposition degree of the emotion, to build the user sentiment trend analysis model; Secondly, we analyze the influence for the user's own sentiment trend when the value changed of difference coefficient ; thirdly, after analyze to obtain one user's sentiment orientation threshold as prerequisite for user behavior prediction. Finally, setting an example to calculate the sentiment trend of one twitter, then to get the conclusion is that the analysis of user emotion from a three-dimensional angle is more realistic than the single angle.

  12. Gaz Phase IR and UV Spectroscopy of Neutral Contact Ion Pairs

    Science.gov (United States)

    Habka, Sana; Brenner, Valerie; Mons, Michel; Gloaguen, Eric

    2016-06-01

    Cations and anions, in solution, tend to pair up forming ion pairs. They play a crucial role in many fundamental processes in ion-concentrated solutions and living organisms. Despite their importance and vast applications in physics, chemistry and biochemistry, they remain difficult to characterize namely because of the coexistence of several types of pairing in solution. However, an interesting alternative consists in applying highly selective gas phase spectroscopy which can offer new insights on these neutral ion pairs. Our study consists in characterizing contact ion pairs (CIPs) in isolated model systems (M+, Ph-(CH2)n-COO- with M=Li, Na, K, Rb, Cs, and n=1-3), to determine their spectral signatures and compare them to ion pairs in solution. We have used laser desorption to vaporize a solid tablet containing the desired salt. Structural information for each system was obtained by mass-selective, UV and IR laser spectroscopy combined with high level quantum chemistry calculations1. Evidence of the presence of neutral CIPs was found by scanning the π-π* transition of the phenyl ring using resonant two-photon ionization (R2PI). Then, conformational selective IR/UV double resonance spectra were recorded in the CO2- stretch region for each conformation detected. The good agreement between theoretical data obtained at the BSSE-corrected-fullCCSD(T)/dhf-TZVPP//B97-D3/dhf-TZVPP level and experimental IR spectra led us to assign the 3D structure for each ion pair formed. Spectral signatures of (M+, Ph-CH2-COO-) pairs, were assigned to a bidentate CIPs between the alkali cation and the carboxylate group. In the case of (Li+, Ph-(CH2)3-COO-) pairs, the presence of a flexible side chain promotes a cation-π interaction leading to a tridentate O-O-π structure with its unique IR and UV signatures. IR spectra obtained on isolated CIPs were found very much alike the ones published on lithium and sodium acetate in solution2. However, in the case of sodium acetate, solution

  13. Universality-class crossover by a nonorder field introduced to the pair contact process with diffusion

    Science.gov (United States)

    Park, Su-Chan

    2017-09-01

    The one-dimensional pair contact process with diffusion (PCPD), an interacting particle system with diffusion, pair annihilation, and creation by pairs, has defied consensus about the universality class to which it belongs. An argument by Hinrichsen [Physica A 361, 457 (2006), 10.1016/j.physa.2005.06.101] claims that freely diffusing particles in the PCPD should play the same role as frozen particles when it comes to the critical behavior. Therefore, the PCPD is claimed to have the same critical phenomena as a model with infinitely many absorbing states that belongs to the directed percolation (DP) universality class. To investigate if diffusing particles are really indistinguishable from frozen particles in the sense of the renormalization group, we study numerically a variation of the PCPD by introducing a nonorder field associated with infinitely many absorbing states. We find that a crossover from the PCPD to DP occurs due to the nonorder field. By studying a similar model, we exclude the possibility that the mere introduction of a nonorder field to one model can entail a nontrivial crossover to another model in the same universality class, thus we attribute the observed crossover to the difference of the universality class of the PCPD from the DP class.

  14. Time-dep endent Calculations for Two-proton Decay Width with Schematic Density-dependent Contact Pairing Interaction

    Institute of Scientific and Technical Information of China (English)

    Oishi Tomohiro

    2016-01-01

    We calculate the two-proton decay width of the 6 Be nucleus employing the schematic density-dependent contact potential for the proton-proton pairing interaction. The decay width is calculated with a time-dependent method, in which the two-proton emission is described as a time-evolution of a three-body meta-stable state. Model-dependence of the two-proton decay width has been shown by comparing the results obtained with the two different pairing models, schematic density-dependent contact and Minnesota interactions, which have zero and finite ranges, respectively.

  15. Contact ion pair formation between hard acids and soft bases in aqueous solutions observed with 2DIR spectroscopy.

    Science.gov (United States)

    Sun, Zheng; Zhang, Wenkai; Ji, Minbiao; Hartsock, Robert; Gaffney, Kelly J

    2013-12-12

    The interaction of charged species in aqueous solution has important implications for chemical, biological, and environmental processes. We have used 2DIR spectroscopy to study the equilibrium dynamics of thiocyanate chemical exchange between free ion (NCS(-)) and contact ion pair configurations (MNCS(+)), where M(2+) = Mg(2+) or Ca(2+). Detailed studies of the influence of anion concentration and anion speciation show that the chemical exchange observed with the 2DIR measurements results from NCS(-) exchanging with other anion species in the first solvation shell surrounding Mg(2+) or Ca(2+). The presence of chemical exchange in the 2DIR spectra provides an indirect, but robust, determinant of contact ion pair formation. We observe preferential contact ion pair formation between soft Lewis base anions and hard Lewis acid cations. This observation cannot be easily reconciled with Pearson's acid-base concept or Collins' Law of Matching Water Affinities. The anions that form contact ion pairs also correspond to the ions with an affinity for water and protein surfaces, so similar physical and chemical properties may control these distinct phenomena.

  16. Nature of sodium atoms/(Na(+), e(-)) contact pairs in liquid tetrahydrofuran.

    Science.gov (United States)

    Glover, William J; Larsen, Ross E; Schwartz, Benjamin J

    2010-09-09

    With no internal vibrational or rotational degrees of freedom, atomic solutes serve as the simplest possible probe of a condensed-phase environment's influence on solute electronic structure. Of the various atomic species that can be formed in solution, the quasi-one-electron alkali atoms in ether solvents have been the most widely studied experimentally, primarily due to the convenient location of their absorption spectra at visible wavelengths. The nature of solvated alkali atoms, however, remains controversial: the consensus view is that solvated alkali atoms exist as (Na(+), e(-)) tight-contact pairs (TCPs), species in which the alkali valence electron is significantly displaced from the alkali nucleus and confined primarily by the first solvent shell. Thus, to shed light on the nature of alkali atoms in solution and to further our understanding of condensed-phase effects on solutes' electronic structure, we have performed mixed quantum/classical molecular dynamics simulations of sodium atoms in liquid tetrahydrofuran (Na(0)/THF). Our interest in this particular system stems from recent pump-probe experiments in our group, which found that the rate at which this species is solvated depends on how it was created ( Science 2008 , 321 , 1817 ); in other words, the solvation dynamics of this system do not obey linear response. Our simulations reproduce the experimental spectroscopy of this system and clearly indicate that neutral Na atoms exist as (Na(+), e(-)) TCPs in solution. We find that the driving force for the displacement of sodium's valence electron is the formation of a tight solvation shell around the partially exposed Na(+). On average, four THF oxygens coordinate the cation end of the TCP; however, we also observe fluctuations to other solvent coordination numbers. Furthermore, we find that species with different solvent coordination numbers have unique absorption spectra and that interconversion between species with different solvent coordination

  17. Parallel genetic divergence among coastal-marine ecotype pairs of European anchovy explained by differential introgression after secondary contact.

    Science.gov (United States)

    Le Moan, A; Gagnaire, P-A; Bonhomme, F

    2016-07-01

    Ecophenotypic differentiation among replicate ecotype pairs within a species complex is often attributed to independent outcomes of parallel divergence driven by adaptation to similar environmental contrasts. However, the extent to which parallel phenotypic and genetic divergence patterns have emerged independently is increasingly questioned by population genomic studies. Here, we document the extent of genetic differentiation within and among two geographic replicates of the coastal and marine ecotypes of the European anchovy (Engraulis encrasicolus) gathered from Atlantic and Mediterranean locations. Using a genome-wide data set of RAD-derived SNPs, we show that habitat type (marine vs. coastal) is the most important component of genetic differentiation among populations of anchovy. By analysing the joint allele frequency spectrum of each coastal-marine ecotype pair, we show that genomic divergence patterns between ecotypes can be explained by a postglacial secondary contact following a long period of allopatric isolation (c. 300 kyrs). We found strong support for a model including heterogeneous migration among loci, suggesting that secondary gene flow has eroded past differentiation at different rates across the genome. Markers experiencing reduced introgression exhibited strongly correlated differentiation levels among Atlantic and Mediterranean regions. These results support that partial reproductive isolation and parallel genetic differentiation among replicate pairs of anchovy ecotypes are largely due to a common divergence history prior to secondary contact. They moreover provide comprehensive insights into the origin of a surprisingly strong fine-scale genetic structuring in a high gene flow marine fish, which should improve stock management and conservation actions.

  18. Tunable All Electric Spin Polarizer Using A Quantum Point Contact With Two Pairs of In-Plane Side Gates

    Science.gov (United States)

    Bhandari, Nikhil; Charles, James; Dutta, Maitreya; Das, Partha; Cahay, Marc; Newrock, Richard; Herbert, Steven

    2013-03-01

    We report the first experimental investigation of a device consisting of a quantum point contact (QPC) with four gates - two in-plane side gates in series. The first set of gates (nearest the source contact) is asymmetrically biased to create spin polarization in the channel of the QPC. A symmetric bias is then applied on the second set of side gates (nearest the drain) and varied to tune the location of a conductance anomaly near 0.5 (x2e2/h). The experimental results compare well with simulations of the four-gate QPC devices using a Non-Equilibrium Green's Function formalism. The device is shown to be a tunable all-electric spin polarizer. The range of common-mode bias on the first set of gates over which maximum spin polarization can be achieved is much broader for the four-gate structure compared with the case of a QPC with a single pair of in-plane side gates. This work is supported by NSF under Award 1028483.

  19. The functional significance of density and distribution of outgrowths on co-opted contact pairs in biological arresting systems

    Science.gov (United States)

    Filippov, Alexander E.; Popov, Valentin L.; Gorb, Stanislav N.

    2015-01-01

    Microstructures responsible for temporary arresting of contacting surfaces are widely distributed on surfaces in different organisms. Recent morphological studies show that these structures have different density of outgrowths and not ideal distribution pattern on both complementary parts of the contact. One can suggest that this difference is optimized by natural selection to get stronger mechanical arrest within the system. In this paper, we simulate such a system numerically, both in the frames of continuous contact and discrete dynamical models to prove this hypothesis and elucidate other aspects of optimization of such mechanical adhesive systems. PMID:25533090

  20. Wear mechanism of heavy load friction contact pairs in tracked vehicle by combined ferrography and surface analysis

    Institute of Scientific and Technical Information of China (English)

    LI Li; ZHU You-li; HUANG Yuan-lin; XU Bin-shi; LI Xiao-yan

    2004-01-01

    Ferrography is deemed as one of the most effective methods for wear particle analysis and failure diagnosis. By analyzing the configuration, content and composition of wear particles in the lubricanting grease and the surface state of the worn surface with combined ferrography and surface analysis techniques, the wear mechanism of the ball groove of the master clutch's release device of a heavy load tracked vehicle was determined. Results show that the controlling wear mechanism is combined of abrasion, adhesion, contact fatigue and corrosion wear, which demonstrates the effectiveness of using combined ferrography and worn surface analysis for the study of wear mechanism of contact surface with friction.

  1. Wear performance of self-mating contact pairs of TiN and TiAlN coatings on orthopedic grade Ti-6Al-4V.

    Science.gov (United States)

    Kim, H; Kim, C Y; Kim, D W; Lee, I S; Lee, G H; Park, J C; Lee, S J; Lee, K Y

    2010-08-01

    Both titanium nitride (TiN) and titanium aluminum nitride (TiAlN) have shown great wear resistance potential in metallic medical devices as protective, hard thin film coatings. In the present study, the effects of TiN and TiAlN coating layers on the wear performance of Ti-6Al-4V were compared and analyzed. TiN and TiAlN coatings with a thickness of 3 microm were deposited by a cathodic vacuum arc ion plating technique on the surface of Ti-6Al-4V. Wear tests were conducted by using a pin-on-disk-type tribotester with a point contact self-mating pair in a linear reciprocal motion. A sliding distance of 20 mm per cycle at 1 Hz was used under a load of 15 N under ambient conditions with no lubricant. The wear resistance of TiN and TiAlN coatings is superior to that of uncoated Ti-6Al-4V at the early stage of sliding contact. Until a measurable amount of wear was detected, the number of sliding cycles of the TiAlN coating pair was longer than TiN. After the first detection of wear from the coating layers, the rate of wear of the TiN coating pairs was significantly higher than that of TiAlN (p TiN from the viewpoint of wear resistance under the test conditions used in this study.

  2. Full-length RAG1 promotes contact with coding and intersignal sequences in RAG protein complexes bound to recombination signals paired in cis.

    Science.gov (United States)

    Kumar, Sushil; Swanson, Patrick C

    2009-04-01

    The RAG proteins initiate V(D)J recombination by mediating synapsis and cleavage of two different antigen receptor gene segments through interactions with their flanking recombination signal sequences (RSS). The protein-DNA complexes that support this process have mainly been studied using RAG-RSS complexes assembled using oligonucleotide substrates containing a single RSS that are paired in trans to promote synapsis. How closely these complexes model those formed on longer, more physiologically relevant substrates containing RSSs on the same DNA molecule (in cis) remains unclear. To address this issue, we characterized discrete core and full-length RAG protein complexes bound to RSSs paired in cis. We find these complexes support cleavage activity regulated by V(D)J recombination's '12/23 rule' and exhibit plasticity in RSS usage dependent on partner RSS composition. DNA footprinting studies suggest that the RAG proteins in these complexes mediate more extensive contact with sequences flanking the RSS than previously observed, some of which are enhanced by full-length RAG1, and associated with synapsis and efficient RSS cleavage. Finally, we demonstrate that the RAG1 C-terminus facilitates hairpin formation on long DNA substrates, and full-length RAG1 promotes hairpin retention in the post-cleavage RAG complex. These results provide new insights into the mechanism of physiological V(D)J recombination.

  3. Modelación del contacto entre dos pares de dientes en las coronas de molinos de caña//Modeling of contact between two pairs of teeth in the sugar cane mills gears

    Directory of Open Access Journals (Sweden)

    Abdel Mendoza‐Fernández

    2013-09-01

    Full Text Available En el trabajo se propone un mecanismo equivalente para la modelación del funcionamiento de las coronas de molino de caña de azúcar cuando teóricamente hay dos pares de dientes en contacto. A través del análisis de movilidad del mecanismo se demuestra que no es posible el contacto simultaneo entre dos pares de dientes y que el coeficiente de recubrimiento en estos engranes es igual o menor que la unidad. A partir de los resultados del análisis cinemático del contacto entre un par de dientes, y combinándolo con la modelación del contacto entre dos pares de dientes se demuestra que el coeficiente de recubrimiento real en estos engranajes es menor que la unidad y se producen impactos entre los dientes al inicio del contacto.Palabras claves: molinos de caña, coronas de molinos, coeficiente de recubrimiento, engranajes._________________________________________________________________________________AbstractThe paper proposes an equivalent mechanism for modeling the functioning of the crowns of sugar cane mill when theoretically there are two pairs of teeth in contact. Through mobility analysis of the mechanism is demonstrated that is not possible the simultaneous contact between two pairs of teeth and that the coating coefficient of these gears is equal or less than unity. Combining kinematic analysis results for the contact between a pair of teeth with the modeling the contact between two pairs of teeth, it is demonstrated that gear ratio of these gears is less than unity and impacts occur between the teeth at the start of contact.Key words: sugar cane mills, sugar cane mills gears, contact ratio, gears.

  4. High-resolution Measurement of Contact Ion-pair Structures in Aqueous RbCl Solutions from the Simultaneous Corefinement of their Rb and Cl K-edge XAFS and XRD Spectra

    Energy Technology Data Exchange (ETDEWEB)

    Pham, Van-Thai; Fulton, John L.

    2016-06-21

    In concentrated solutions of aqueous RbCl, all of the Rb+ and Cl- ions exist as contact ion pairs. This full structural assessment is derived from the refinement of three independent experimental measurements: the Rb and Cl K-edge x-ray absorption fine structure (XAFS) and the x-ray diffraction spectra (XRD). This simultaneous refinement of the XAFS and XRD data provides high accuracy since each method probes the structure of different local regions about the ions with high sensitivity. At high RbCl concentration (6 m (mol/kg )) the solution is dominated by Rb+ - Cl- contact ion pairs yielding an average of 1.5 pairs at an Rb-Cl distance of 3.24 Å. Upon formation of these ion pairs, approximately 1.1 waters molecules are displaced from the Rb+ and 1.4 water molecules from Cl-. The hydration shells about both the cation and anion are also determined. These results greatly improve the understanding of monovalent ions and provide a basis for testing the Rb+-Cl- interaction potentials used in molecular dynamics (MD) simulation. This research was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences.

  5. Contact Analysis of Spur Gear Pairs and Calculation of Mesh Stiffness%直齿轮副接触分析及啮合刚度计算

    Institute of Scientific and Technical Information of China (English)

    张国锋

    2014-01-01

    采用有限元法建立直齿轮副接触模型进行仿真分析,计算齿轮副接触应力,并通过赫兹接触理论公式验证了有限元法分析结果的正确性。通过对直齿轮传动进行分析,基于石川公式,采用Matlab软件编程计算直齿轮副时变啮合刚度。%Based on finite element method,contact model of spur gear was built to calculate contact stress by simulation analysis,and which result was verified by means of calculation of Hertz formula of contact theory. Transmission of spur gear system was analysed and time-varing mesh stiffness using Ishikawa formula was calculated by matlab software.

  6. Simultaneous determination of 11 fluorescent whitening agents in food-contact paper and board by ion-pairing high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Jiang, Dingguo; Chen, Lisong; Fu, Wusheng; Qiu, Hanquan

    2015-02-01

    4,4'-Diaminostilbene-2,2'-disulfonic acid based fluorescent whitening agents (DSD-FWAs) are prohibited in food-contact paper and board in many countries. In this work, a reliable high-performance liquid chromatography method was developed for the simultaneous determination of 11 common DSD-FWAs in paper material. Sample preparation and extraction as well as chromatographic separation of multicomponent DSD-FWAs were successfully optimized. DSD-FWAs in prepared samples were ultrasonically extracted with acetonitrile/water/triethylamine (40:60:1, v/v/v), separated on the C(18) column with the mobile phase containing tetrabutylammonium bromide, and then detected by a fluorescence detector. The limits of detection were 0.12-0.24 mg/kg, and the calibration curves showed the linear correlation (R(2) ≥ 0.9994) within the range of 8.0-100 ng/mL, which was equivalent to the range of 0.80-10 mg/kg in the sample. The average recoveries and the RSDs were 81-106% and 2-9% at two fortification levels (1.0 and 5.0 mg/kg) in paper bowls, respectively. The successful determination of 11 DSD-FWAs in food-contact paper and board obtained from local markets indicated that the newly developed method was rapid, accurate, and highly selective.

  7. JAM-A and aPKC: A close pair during cell-cell contact maturation and tight junction formation in epithelial cells.

    Science.gov (United States)

    Ebnet, Klaus

    2013-01-01

    Cell-cell adhesion plays a critical role in the formation of barrier-forming epithelia. The molecules which mediate cell-cell adhesion frequently act as signaling molecules by recruiting and/or assembling cytoplasmic protein complexes. Junctional Adhesion Molecule (JAM)-A interacts with the cell polarity protein PAR-3, a member of the PAR-3-aPKC-PAR-6 complex, which regulates the formation of cell-cell contacts and the development of tight junctions (TJs). In our recent study we found that JAM-A is localized at primordial, spot-like cell-cell junctions (pAJs) in a non-phosphorylated form. After the recruitment of the PAR-aPKC complex and its activation at pAJs, aPKC phosphorylates JAM-A at Ser285 to promote the maturation of immature junctions. In polarized epithelial cells, aPKC phosphorylates JAM-A selectively at the TJs to maintain the barrier function of TJs. Thus, through mutual regulation, JAM-A and aPKC form a functional unit that regulates the establishment of barrier-forming junctions in vertebrate epithelial cells.

  8. A classical description of relaxation of interacting pairs of unlike spins: Extension to T1 ϱ, T2, and T1 ϱoff, including contact interactions

    Science.gov (United States)

    Konig, Seymour H.

    A novel derivation of the equations that describe the spin-lattice magnetic relaxation of nuclear spin moments, in liquids, resulting from magnetic dipolar interactions with neighboring paramagnetic ions, the Solomon-Bloembergen-Morgan equations was previously presented (S. H. Koenig, J. Magn. Reson.31, 1 (1978)). The derivation involves a computation of the dissipative energy flow from the nuclear spins to the lattice rather than a computation of the lattice-produced fluctuations of the local field at the nuclear spins. Two advantages accrue: (1) the spectral densities that enter into the relaxation expressions can be directly related to well-defined absorption transitions and relaxation processes of the paramagnetic ions, clarifying the physical processes that produce relaxation, and (2) the derivation can be readily generalized to paramagnetic ions with arbitrary spin Hamiltonian, and to deviations of their susceptibility from Curie law behavior. The derivation is extended to include relaxation in liquids in the rotating frame: the on resonance T1 ϱ which reduces to T2 for small amplitude radiofrequency fields; and the off resonance T1 ϱoff, which reduces to T1. The results, which are given for contact as well as dipolar interactions, also describe relaxation of 13C and 15N nuclei by protons under conditions of proton-decoupling, a situation becoming increasingly important in the study of biological macromolecules by high-resolution NMR spectroscopy.

  9. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... shop, but 10 hours after she first put in a pair of colored contact lenses, Laura Butler of Parkersburg, W.Va., had "extreme pain in both eyes," she said. "Because I had not ...

  10. Contact dermatitis

    Science.gov (United States)

    Dermatitis - contact; Allergic dermatitis; Dermatitis - allergic; Irritant contact dermatitis; Skin rash - contact dermatitis ... There are 2 types of contact dermatitis. Irritant dermatitis: This ... with acids, alkaline materials such as soaps and detergents , ...

  11. Language Contact.

    Science.gov (United States)

    Nelde, Peter Hans

    1995-01-01

    Examines the phenomenon of language contact and recent trends in linguistic contact research, which focuses on language use, language users, and language spheres. Also discusses the role of linguistic and cultural conflicts in language contact situations. (13 references) (MDM)

  12. Dual contact pogo pin assembly

    Energy Technology Data Exchange (ETDEWEB)

    Hatch, Stephen McGarry

    2016-06-21

    A contact assembly includes a base and a pair of electrical contacts supported by the base. A first end of the first electrical contact corresponds to a first end of the base and is configured to engage a first external conductive circuit element. A first end of the second electrical contact also corresponds to the first end of the base and is configured to engage a second external conductive circuit element. The first contact and the second contact are electrically isolated from one another and configured to compress when engaging an external connector element. The base includes an aperture positioned on a second end of the base outboard of a second end of the first and second electrical contacts. The aperture presents a narrowing shape with a wide mouth distal the electrical contacts and a narrow internal through-hole proximate the electrical contacts.

  13. 金属橡胶非线性干摩擦副的接触作用机理及其仿真结果分析%Contacting mechanism of nonlinear friction pair for metallic rubber and its simulation results

    Institute of Scientific and Technical Information of China (English)

    李宇燕; 黄协清; 宋凯

    2011-01-01

    从金属橡胶材料的干摩擦阻尼产生的机理人手,提出了一种全新的金属橡胶非线性干摩擦结构单元力学模型,该结构单元由一对带有轴向和径向两个方向的弹性元件构成,它们既表示了金属丝之间的摩擦特性,同时也表示了螺线卷线匝在受力变形时的弹性特征.以建立的金属橡胶材料力学模型为基础,采用多个摩擦副单元串联组成的结构,深入研究了线匝的摩擦接触,通过对结构单元组成系统的计算机模拟仿真,对金属橡胶元件在不同载荷作用下的滞迟回线进行了深入地分析和研究,在静态载荷作用下,研究了结构单元的摩擦系数、结构单元的摩擦角对金属橡胶结构摩擦耗能的影响,在动态载荷作用下,研究了载荷的幅值、载荷的频率、载荷的初始相位对摩擦耗能的影响,此项研究工作大大减少了静态和动态试验方面的工作.%From dry-friction damping mechanism of metallic rubber, a new mechanical model for nonlinear friction structure element of metallic rubber was put forward. The structural element was made up of axial and radial elastic elements. The two elements not only denoted friction characteristics among wires, but also elastic properties of spiral turns. Based on the mechanical model constructed, using a series connection structure with multiple friction pairs, friction contacts between turns were studied. Through simulation for the system with the structural elements, hysteresis loops were deeply analyzed and studied under different loading for metallic rubber elements. Under static loading, the effects of friction coefficient and friction angle on energy dissipation of metallic rubber were studied, and under dynamic loading the effects of force's amplitude, frequency and initial phase on energy dissipation were also studied, the studies largely reduced the efforts for static and dynamic experiments.

  14. Pairing Learners in Pair Work Activity

    Science.gov (United States)

    Storch, Neomy; Aldosari, Ali

    2013-01-01

    Although pair work is advocated by major theories of second language (L2) learning and research findings suggest that pair work facilitates L2 learning, what is unclear is how to best pair students in L2 classes of mixed L2 proficiency. This study investigated the nature of pair work in an English as a Foreign Language (EFL) class in a college in…

  15. Direct contact vs. solvent-shared ion pairs in nicl2 electrolytesmonitored by multiplet effects at the ni(ii) l-edge x-ray absorptionDOC_XNOTE=Published by BESSY, Germany in collaboration with LawrenceBerkeley National Laboratory staff.

    Energy Technology Data Exchange (ETDEWEB)

    Aziz, E.F.; Eisebitt, S.; Eberhardt, W.; de Groot, F.; Chiou,J.W.; Dong, C.L.; Guo, J.-H.

    2007-03-29

    We investigate the local electronic structure in aqueous NiCl{sub 2} electrolytes by Ni L edge x-ray absorption spectroscopy. The experimental findings are interpreted in conjunction with multiplet calculations of the electronic structure and the resulting spectral shape. In contrast to the situation in the solid, the electronic structure in the electrolyte reflects the absence of direct contact Ni-Cl ion pairs. We observe a systematic change of the intensity ratio of singlet and triplet-related spectral features as a function of electrolyte concentration. These changes can be described theoretically by a changed weight of transition matrix contributions with different symmetry. We interpret these findings as being due to progressive distortions of the local symmetry induced by solvent-shared ion pairs.

  16. The Nuclear Contact Exists

    CERN Document Server

    Hen, O; Piasetzky, E; Miller, G A; Sargsian, M M

    2014-01-01

    Many-body systems of strongly interacting Fermions are ubiquitous in nature, ranging from High-Tc superconductors and ultra-cold atomic gases to atomic nuclei and neutron stars. Theoretical predictions, recently verified by measurements on ultra-cold atomic gases, show that under certain conditions the universal behavior of systems composed of two kinds of fermions can be described using a single parameter, simply called the contact, which is a measure of the number of different-fermion pairs in close proximity. This paper discusses the relevance of the contact for very different systems: atomic nuclei, made of strongly-interacting neutrons and protons. Here we show that the high-momentum distributions of protons and neutrons in nuclei, dominated by correlated proton-neutron pairs mainly in a spin-triplet state, have the same momentum dependence as those of cold atoms, with a strength described by the contact. We use high-energy electron scattering data to extract a value for the nuclear contact consistent wi...

  17. 偏歪斜滚子摩擦副的接触应力分析及凸度设计%Contact Stress Analysis and Crowning Design of Friction Pair with Rollers Under Misalignment and Skewing Conditions

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    Abstratc:Based on the static elastic-contact theory , a model to describe the mechanical contact between the roller and the race is established under misalignment and skewing conditions , and the fast Fourier transform ( FFT) and the conjugate gradient method are employed to obtain the elastic deformation and the contact stress , respectively . Then, the influences of different parameters on the contact stress distribution are analyzed .The results show that (1) at a constant skewing angle , both the misaligned load effect and the edge effect remarkably improve with the increase of the misalignment angle; (2) at a constant misaligned angle , the skewing phenomenon becomes more obvious with the increase of the skewing angle , and the misalignment angle helps to weaken the edge effect caused by the contact between the roller and the inner race , while the misaligned load effect and the skewing phenomenon both become worse when the roller is contacted with the outer race; and (3) with the increase of the length-to-dia-meter ratio, both the misaligned load effect and the skewing phenomenon become more obvious .In addition, a crowning design method considering both the misalignment and the skewing of the roller is presented to improve the anti-misalignment and anti-skewing ability of roller bearings .%根据静弹性接触理论,建立滚子与滚道同时存在偏斜和歪斜工况下的力学模型,并利用快速傅里叶变换( FFT)求解其弹性变形,用共轭梯度法求解接触应力。通过分析各种工况参数对接触应力分布的影响发现:歪斜角一定时,随着偏斜角的增大,“偏斜效应”和“边缘效应”均变得更加明显;偏斜角一定时,“歪斜效应”随着歪斜角的增大而逐渐明显,且偏斜角能减弱滚子与内滚道接触产生的“边缘效应”,滚子则与外滚道接触产生更加严重的“偏斜效应”和“歪斜效应”;随着滚子长径比的增加,滚子与滚

  18. Powered Tate Pairing Computation

    Science.gov (United States)

    Kang, Bo Gyeong; Park, Je Hong

    In this letter, we provide a simple proof of bilinearity for the eta pairing. Based on it, we show an efficient method to compute the powered Tate pairing as well. Although efficiency of our method is equivalent to that of the Tate pairing on the eta pairing approach, but ours is more general in principle.

  19. Pairings on hyperelliptic curves

    CERN Document Server

    Balakrishnan, Jennifer; Chisholm, Sarah; Eisentraeger, Kirsten; Stange, Katherine; Teske, Edlyn

    2009-01-01

    We assemble and reorganize the recent work in the area of hyperelliptic pairings: We survey the research on constructing hyperelliptic curves suitable for pairing-based cryptography. We also showcase the hyperelliptic pairings proposed to date, and develop a unifying framework. We discuss the techniques used to optimize the pairing computation on hyperelliptic curves, and present many directions for further research.

  20. RACIAL CONTACT, PERSONALITY, AND GROUP PROBLEM SOLVING.

    Science.gov (United States)

    ABNER, EDWARD V.; LEWIT, DAVID W.

    THIS STUDY TESTS THE HYPOTHESIS THAT BIRACIAL GROUPS IN WHICH RACEMATES WERE PAIRED FOR DIRECT CONTACT WOULD PERFORM BETTER THAN THOSE IN WHICH RACEMATES WERE ISOLATED. IT ALSO ASSUMED THAT ETHNOCENTRIC SUBJECTS WOULD PERFORM BETTER WITH CONTACT WITH A RACEMATE, AND THAT AGGRESSIVE SUBJECTS WOULD GET ALONG WELL WITHOUT IT. THE SUBJECTS WERE BOYS…

  1. Screen printed interdigitated back contact solar cell

    Science.gov (United States)

    Baraona, C. R.; Mazaris, G. A.; Chai, A. T.

    1984-10-01

    Interdigitated back contact solar cells are made by screen printing dopant materials onto the back surface of a semiconductor substrate in a pair of interdigitated patterns. These dopant materials are then diffused into the substrate to form junctions having configurations corresponding to these patterns. Contacts having configurations which match the patterns are then applied over the junctions.

  2. Screen printed interdigitated back contact solar cell

    Science.gov (United States)

    Baraona, C. R.; Mazaris, G. A.; Chai, A. T. (Inventor)

    1984-01-01

    Interdigitated back contact solar cells are made by screen printing dopant materials onto the back surface of a semiconductor substrate in a pair of interdigitated patterns. These dopant materials are then diffused into the substrate to form junctions having configurations corresponding to these patterns. Contacts having configurations which match the patterns are then applied over the junctions.

  3. Prioritized Contact Transport Stream

    Science.gov (United States)

    Hunt, Walter Lee, Jr. (Inventor)

    2015-01-01

    A detection process, contact recognition process, classification process, and identification process are applied to raw sensor data to produce an identified contact record set containing one or more identified contact records. A prioritization process is applied to the identified contact record set to assign a contact priority to each contact record in the identified contact record set. Data are removed from the contact records in the identified contact record set based on the contact priorities assigned to those contact records. A first contact stream is produced from the resulting contact records. The first contact stream is streamed in a contact transport stream. The contact transport stream may include and stream additional contact streams. The contact transport stream may be varied dynamically over time based on parameters such as available bandwidth, contact priority, presence/absence of contacts, system state, and configuration parameters.

  4. Casimir light: photon pairs.

    OpenAIRE

    1993-01-01

    Expressions are developed for weak single pair emission probability and strong emission average number of pairs. The water transparency cutoff is closely realized, showing that the fundamental time scale is even shorter.

  5. A stabilized pairing functional

    CERN Document Server

    Erler, J; Reinhard, P --G

    2008-01-01

    We propose a modified pairing functional for nuclear structure calculations which avoids the abrupt phase transition between pairing and non-pairing states. The intended application is the description of nuclear collective motion where the smoothing of the transition is compulsory to remove singularities. The stabilized pairing functional allows a thoroughly variational formulation, unlike the Lipkin-Nogami (LN) scheme which is often used for the purpose of smoothing. First applications to nuclear ground states and collective excitations prove the reliability and efficiency of the proposed stabilized pairing.

  6. Contact Graph Routing

    Science.gov (United States)

    Burleigh, Scott C.

    2011-01-01

    Contact Graph Routing (CGR) is a dynamic routing system that computes routes through a time-varying topology of scheduled communication contacts in a network based on the DTN (Delay-Tolerant Networking) architecture. It is designed to enable dynamic selection of data transmission routes in a space network based on DTN. This dynamic responsiveness in route computation should be significantly more effective and less expensive than static routing, increasing total data return while at the same time reducing mission operations cost and risk. The basic strategy of CGR is to take advantage of the fact that, since flight mission communication operations are planned in detail, the communication routes between any pair of bundle agents in a population of nodes that have all been informed of one another's plans can be inferred from those plans rather than discovered via dialogue (which is impractical over long one-way-light-time space links). Messages that convey this planning information are used to construct contact graphs (time-varying models of network connectivity) from which CGR automatically computes efficient routes for bundles. Automatic route selection increases the flexibility and resilience of the space network, simplifying cross-support and reducing mission management costs. Note that there are no routing tables in Contact Graph Routing. The best route for a bundle destined for a given node may routinely be different from the best route for a different bundle destined for the same node, depending on bundle priority, bundle expiration time, and changes in the current lengths of transmission queues for neighboring nodes; routes must be computed individually for each bundle, from the Bundle Protocol agent's current network connectivity model for the bundle s destination node (the contact graph). Clearly this places a premium on optimizing the implementation of the route computation algorithm. The scalability of CGR to very large networks remains a research topic

  7. Matched-pair classification

    Energy Technology Data Exchange (ETDEWEB)

    Theiler, James P [Los Alamos National Laboratory

    2009-01-01

    Following an analogous distinction in statistical hypothesis testing, we investigate variants of machine learning where the training set comes in matched pairs. We demonstrate that even conventional classifiers can exhibit improved performance when the input data has a matched-pair structure. Online algorithms, in particular, converge quicker when the data is presented in pairs. In some scenarios (such as the weak signal detection problem), matched pairs can be generated from independent samples, with the effect not only doubling the nominal size of the training set, but of providing the structure that leads to better learning. A family of 'dipole' algorithms is introduced that explicitly takes advantage of matched-pair structure in the input data and leads to further performance gains. Finally, we illustrate the application of matched-pair learning to chemical plume detection in hyperspectral imagery.

  8. Lipstick Induced Contact Leucoderma

    OpenAIRE

    Gupta Lalit Kumar; Jain Suresh Kumar; Khare Ashok Kumar

    2001-01-01

    Lipstick is a commonly used cosmetic. Its use may sometimes lead to contact dermatitis. Contact leucoderma to lipsticks however, is not common. We report a patient developing contact leucoderma to lipstick in association with contact dermatitis.

  9. Lipstick Induced Contact Leucoderma

    Directory of Open Access Journals (Sweden)

    Gupta Lalit Kumar

    2001-01-01

    Full Text Available Lipstick is a commonly used cosmetic. Its use may sometimes lead to contact dermatitis. Contact leucoderma to lipsticks however, is not common. We report a patient developing contact leucoderma to lipstick in association with contact dermatitis.

  10. Ion Pairing in Alkali Nitrate Electrolyte Solutions.

    Science.gov (United States)

    Xie, Wen Jun; Zhang, Zhen; Gao, Yi Qin

    2016-03-10

    In this study, we investigate the thermodynamics of alkali nitrate salt solutions, especially the formation of contact ion pairs between alkali cation and nitrate anion. The ion-pairing propensity shows an order of LiNO3 activity coefficients and suggest that the empirical "law of matching water affinity" is followed by these alkali nitrate salt solutions. The spatial patterns of contact ion pairs are different in the three salt solutions studied here: Li(+) forms the contact ion pair with only one oxygen of the nitrate while Na(+) and K(+) can also be shared by two oxygens of the nitrate. In reproducing the salt activity coefficient using Kirkwood-Buff theory, we find that it is essential to include electronic polarization for Li(+) which has a high charge density. The electronic continuum correction for nonpolarizable force field significantly improves the agreement between the calculated activity coefficients and their experimental values. This approach also improves the performance of the force field on salt solubility. From these two aspects, this study suggests that electronic continuum correction can be a promising approach to force-field development for ions with high charge densities.

  11. EDITORIAL: Close contact Close contact

    Science.gov (United States)

    Demming, Anna

    2010-07-01

    The development of scanning probe techniques, such as scanning tunnelling microscopy [1], has often been touted as the catalyst for the surge in activity and progress in nanoscale science and technology. Images of nanoscale structural detail have served as an invaluable investigative resource and continue to fascinate with the fantastical reality of an intricate nether world existing all around us, but hidden from view of the naked eye by a disparity in scale. As is so often the case, the invention of the scanning tunnelling microscope heralded far more than just a useful new apparatus, it demonstrated the scope for exploiting the subtleties of electronic contact. The shrinking of electronic devices has been a driving force for research into molecular electronics, in which an understanding of the nature of electronic contact at junctions is crucial. In response, the number of experimental techniques in molecular electronics has increased rapidly in recent years. Scanning tunnelling microscopes have been used to study electron transfer through molecular films on a conducting substrate, and the need to monitor the contact force of scanning tunnelling electrodes led to the use of atomic force microscopy probes coated in a conducting layer as studied by Cui and colleagues in Arizona [2]. In this issue a collaboration of researchers at Delft University and Leiden University in the Netherlands report a new device architecture for the independent mechanical and electrostatic tuning of nanoscale charge transport, which will enable thorough studies of molecular transport in the future [3]. Scanning probes can also be used to pattern surfaces, such as through spatially-localized Suzuki and Heck reactions in chemical scanning probe lithography. Mechanistic aspects of spatially confined Suzuki and Heck chemistry are also reported in this issue by researchers in Oxford [4]. All these developments in molecular electronics fabrication and characterization provide alternative

  12. Physicochemical Properties of Ion Pairs of Biological Macromolecules.

    Science.gov (United States)

    Iwahara, Junji; Esadze, Alexandre; Zandarashvili, Levani

    2015-09-30

    Ion pairs (also known as salt bridges) of electrostatically interacting cationic and anionic moieties are important for proteins and nucleic acids to perform their function. Although numerous three-dimensional structures show ion pairs at functionally important sites of biological macromolecules and their complexes, the physicochemical properties of the ion pairs are not well understood. Crystal structures typically show a single state for each ion pair. However, recent studies have revealed the dynamic nature of the ion pairs of the biological macromolecules. Biomolecular ion pairs undergo dynamic transitions between distinct states in which the charged moieties are either in direct contact or separated by water. This dynamic behavior is reasonable in light of the fundamental concepts that were established for small ions over the last century. In this review, we introduce the physicochemical concepts relevant to the ion pairs and provide an overview of the recent advancement in biophysical research on the ion pairs of biological macromolecules.

  13. Cooper pairs and bipolarons

    OpenAIRE

    Lakhno, Victor D.

    2016-01-01

    It is shown that Cooper pairs are a solution of the bipolaron problem for model Fr\\"{o}hlich Hamiltonian. The total energy of a pair for the initial Fr\\"{o}hlich Hamiltonian is found. Differences between the solutions for the model and initial two-particle problems are discussed.

  14. Cooper pairs and bipolarons

    Science.gov (United States)

    Lakhno, Victor

    2016-11-01

    It is shown that Cooper pairs are a solution of the bipolaron problem for model Fröhlich Hamiltonian. The total energy of a pair for the initial Fröhlich Hamiltonian is found. Differences between the solutions for the model and initial two-particle problems are discussed.

  15. Critical Schwinger Pair Production.

    Science.gov (United States)

    Gies, Holger; Torgrimsson, Greger

    2016-03-04

    We investigate Schwinger pair production in spatially inhomogeneous electric backgrounds. A critical point for the onset of pair production can be approached by fields that marginally provide sufficient electrostatic energy for an off-shell long-range electron-positron fluctuation to become a real pair. Close to this critical point, we observe features of universality which are analogous to continuous phase transitions in critical phenomena with the pair-production rate serving as an order parameter: electric backgrounds can be subdivided into universality classes and the onset of pair production exhibits characteristic scaling laws. An appropriate design of the electric background field can interpolate between power-law scaling, essential Berezinskii-Kosterlitz-Thouless-type scaling, and a power-law scaling with log corrections. The corresponding critical exponents only depend on the large-scale features of the electric background, whereas the microscopic details of the background play the role of irrelevant perturbations not affecting criticality.

  16. Stereo pairs in Astrophysics

    CERN Document Server

    Vogt, Frédéric

    2011-01-01

    Stereoscopic visualization is seldom used in Astrophysical publications and presentations compared to other scientific fields, e.g., Biochemistry, where it has been recognized as a valuable tool for decades. We put forth the view that stereo pairs can be a useful tool for the Astrophysics community in communicating a truer representation of astrophysical data. Here, we review the main theoretical aspects of stereoscopy, and present a tutorial to easily create stereo pairs using Python. We then describe how stereo pairs provide a way to incorporate 3D data in 2D publications of standard journals. We illustrate the use of stereo pairs with one conceptual and two Astrophysical science examples: an integral field spectroscopy study of a supernova remnant, and numerical simulations of a relativistic AGN jet. We also use these examples to make the case that stereo pairs are not merely an ostentatious way to present data, but an enhancement in the communication of scientific results in publications because they prov...

  17. Critical Schwinger pair production

    CERN Document Server

    Gies, Holger

    2015-01-01

    We investigate Schwinger pair production in spatially inhomogeneous electric backgrounds. A critical point for the onset of pair production can be approached by fields that marginally provide sufficient electrostatic energy for an off-shell long-range electron-positron fluctuation to become a real pair. Close to this critical point, we observe features of universality which are analogous to continuous phase transitions in critical phenomena with the pair-production rate serving as an order parameter: electric backgrounds can be subdivided into universality classes and the onset of pair production exhibits characteristic scaling laws. An appropriate design of the electric background field can interpolate between power-law scaling, essential BKT-type scaling and a power-law scaling with log corrections. The corresponding critical exponents only depend on the large-scale features of the electric background, whereas the microscopic details of the background play the role of irrelevant perturbations not affecting ...

  18. Adaptive Pairing Reversible Watermarking.

    Science.gov (United States)

    Dragoi, Ioan-Catalin; Coltuc, Dinu

    2016-05-01

    This letter revisits the pairwise reversible watermarking scheme of Ou et al., 2013. An adaptive pixel pairing that considers only pixels with similar prediction errors is introduced. This adaptive approach provides an increased number of pixel pairs where both pixels are embedded and decreases the number of shifted pixels. The adaptive pairwise reversible watermarking outperforms the state-of-the-art low embedding bit-rate schemes proposed so far.

  19. Stereo pairs in Astrophysics

    Science.gov (United States)

    Vogt, Frédéric; Wagner, Alexander Y.

    2012-01-01

    Stereoscopic visualization is seldom used in Astrophysical publications and presentations compared to other scientific fields, e.g., Biochemistry, where it has been recognized as a valuable tool for decades. We put forth the view that stereo pairs can be a useful tool for the Astrophysics community in communicating a truer representation of astrophysical data. Here, we review the main theoretical aspects of stereoscopy, and present a tutorial to easily create stereo pairs using Python. We then describe how stereo pairs provide a way to incorporate 3D data in 2D publications of standard journals. We illustrate the use of stereo pairs with one conceptual and two Astrophysical science examples: an integral field spectroscopy study of a supernova remnant, and numerical simulations of a relativistic AGN jet. We also use these examples to make the case that stereo pairs are not merely an ostentatious way to present data, but an enhancement in the communication of scientific results in publications because they provide the reader with a realistic view of multi-dimensional data, be it of observational or theoretical nature. In recognition of the ongoing 3D expansion in the commercial sector, we advocate an increased use of stereo pairs in Astrophysics publications and presentations as a first step towards new interactive and multi-dimensional publication methods.

  20. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... Vision and Daily Eye Drops After One Use Facts About Colored Contacts and Halloween Safety Colored Contact Lens Facts Over-the-Counter Costume Contacts May Contain Chemicals ...

  1. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... One Use Facts About Colored Contacts and Halloween Safety Colored Contact Lens Facts Over-the-Counter Costume ... use of colored contact lenses , from the U.S. Food and Drug Administration (FDA). Are the colored lenses ...

  2. Holographic EPR Pairs, Wormholes and Radiation

    CERN Document Server

    Chernicoff, Mariano; Pedraza, Juan F

    2013-01-01

    As evidence for the ER=EPR conjecture, it has recently been observed that the string that is holographically dual to an entangled quark-antiquark pair separating with (asymptotically) uniform acceleration has a wormhole on its worldsheet. We point out that a two-sided horizon and a wormhole actually appear for much more generic quark-antiquark trajectories, which is consistent with the fact that the members of an EPR pair need not be permanently out of causal contact. The feature that determines whether the causal structure of the string worldsheet is trivial or not turns out to be the emission of gluonic radiation by the dual quark and antiquark. In the strongly-coupled gauge theory, it is only when radiation is emitted that one obtains an unambiguous separation of the pair into entangled subsystems, and this is what is reflected on the gravity side by the existence of the worldsheet horizon.

  3. UNILATERAL CONTACT PROBLEMS USING QUASI-ACTIVE SET STRATEGY

    Institute of Scientific and Technical Information of China (English)

    宣兆成; 李兴斯

    2002-01-01

    The unilateral contact problem can be formulated as a mathematical programming with inequality constraints. To resolve the difficulty in dealing with inequality constraints, a quasi-active set strategy algorithm was presented. At each iteration, it transforms the problem into one without contact in terms of the solution obtained in last iteration and initiates the current iteration using the solution of the transformed problem, and updates a group of contact pairs compared with Lemke algorithm that uqdates only one pair of contact points. The present algorithm greatly enhances the efficiency and numerical examples demonstrate the effectiveness and robustness of the proposed algorithm.

  4. TOOTH CONTACT ANALYSIS OF CONICAL INVOLUTE GEARS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The mathematical model of conical involute gears is developed based on the theory of gearing and the generating mechanism. Tooth contact analysis (TCA) is performed to examine the meshing and bearing contact of the conical involute gear pairs with intersected and crossed axes. In addition, the principal directions and curvatures of the gear surfaces are investigated and the contact ellipses of the mating tooth surfaces are also studied. Finally, the numerical illustrative examples are provided to demonstrate the computational results, test gears are made for tooth-bearing tests, and the conclusion is verified that the theory has the applicability.

  5. Na+ Cl- ion pair association in water-DMSO mixtures: Effect of ion pair model potentials

    Indian Academy of Sciences (India)

    ATANU SARKAR; ANUPAM CHATTERJEE; S C TIWARI; B L TEMBE

    2016-06-01

    Potentials of Mean Force (PMF) for the Na+ Cl- ion pair in water–dimethyl sulfoxide (DMSO)mixtures for three DMSO mole fractions have been computed using constrained Molecular Dynamics (MD)simulations and confirmed by dynamical trajectories and residence times of the ion pair at various inter-ionicseparations. The three ion-ion direct potentials used are 12-6-1, exp-6-1 and exp-8-6-1. The physical picturethat emerges is that there is a strong contact ion pair (CIP) and strong to moderate solvent separated ion pair(SSIP) in these solutions. Analysis of local ion clusters shows that ions are dominantly solvated by watermolecules. The 12-6-1 potential model predicts running coordination numbers closest to experimental data.

  6. Numerical analysis of human dental occlusal contact

    Science.gov (United States)

    Bastos, F. S.; Las Casas, E. B.; Godoy, G. C. D.; Meireles, A. B.

    2010-06-01

    The purpose of this study was to obtain real contact areas, forces, and pressures acting on human dental enamel as a function of the nominal pressure during dental occlusal contact. The described development consisted of three steps: characterization of the surface roughness by 3D contact profilometry test, finite element analysis of micro responses for each pair of main asperities in contact, and homogenization of macro responses using an assumed probability density function. The inelastic deformation of enamel was considered, adjusting the stress-strain relationship of sound enamel to that obtained from instrumented indentation tests conducted with spherical tip. A mechanical part of the static friction coefficient was estimated as the ratio between tangential and normal components of the overall resistive force, resulting in μd = 0.057. Less than 1% of contact pairs reached the yield stress of enamel, indicating that the occlusal contact is essentially elastic. The micro-models indicated an average hardness of 6.25GPa, and the homogenized result for macroscopic interface was around 9GPa. Further refinements of the methodology and verification using experimental data can provide a better understanding of processes related to contact, friction and wear of human tooth enamel.

  7. Junctionless Cooper pair transistor

    Energy Technology Data Exchange (ETDEWEB)

    Arutyunov, K. Yu., E-mail: konstantin.yu.arutyunov@jyu.fi [National Research University Higher School of Economics , Moscow Institute of Electronics and Mathematics, 101000 Moscow (Russian Federation); P.L. Kapitza Institute for Physical Problems RAS , Moscow 119334 (Russian Federation); Lehtinen, J.S. [VTT Technical Research Centre of Finland Ltd., Centre for Metrology MIKES, P.O. Box 1000, FI-02044 VTT (Finland)

    2017-02-15

    Highlights: • Junctionless Cooper pair box. • Quantum phase slips. • Coulomb blockade and gate modulation of the Coulomb gap. - Abstract: Quantum phase slip (QPS) is the topological singularity of the complex order parameter of a quasi-one-dimensional superconductor: momentary zeroing of the modulus and simultaneous 'slip' of the phase by ±2π. The QPS event(s) are the dynamic equivalent of tunneling through a conventional Josephson junction containing static in space and time weak link(s). Here we demonstrate the operation of a superconducting single electron transistor (Cooper pair transistor) without any tunnel junctions. Instead a pair of thin superconducting titanium wires in QPS regime was used. The current–voltage characteristics demonstrate the clear Coulomb blockade with magnitude of the Coulomb gap modulated by the gate potential. The Coulomb blockade disappears above the critical temperature, and at low temperatures can be suppressed by strong magnetic field.

  8. Contact dermatitis caused by dimethylfumarate in Argentina.

    Science.gov (United States)

    Lo Balbo, A; Gotelli, M J; Mac Cormack, W P; Kogan, N; Gotelli, C

    2011-07-01

    For the first time in Argentina, we describe an outbreak of contact dermatitis. New pairs of shoes caused intense pruritus, pain, and eruption, followed by edema, blisters, and a severe negative impact on the epidermal barrier of the feet. We identify dimethylfumarate as the causal agent and suggest an analytical method for its fast identification.

  9. Contact Dermatitis in Pediatrics.

    Science.gov (United States)

    Pelletier, Janice L; Perez, Caroline; Jacob, Sharon E

    2016-08-01

    Contact dermatitis is an umbrella term that describes the skin's reaction to contacted noxious or allergenic substances. The two main categories of contact dermatitis are irritant type and allergic type. This review discusses the signs, symptoms, causes, and complications of contact dermatitis. It addresses the testing, treatment, and prevention of contact dermatitis. Proper management of contact dermatitis includes avoidance measures for susceptible children. Implementation of a nickel directive (regulating the use of nickel in jewelry and other products that come into contact with the skin) could further reduce exposure to the most common allergens in the pediatric population. [Pediatr Ann. 2016;45(8):e287-e292.].

  10. Paired fuzzy sets

    DEFF Research Database (Denmark)

    Rodríguez, J. Tinguaro; Franco de los Ríos, Camilo; Gómez, Daniel

    2015-01-01

    In this paper we want to stress the relevance of paired fuzzy sets, as already proposed in previous works of the authors, as a family of fuzzy sets that offers a unifying view for different models based upon the opposition of two fuzzy sets, simply allowing the existence of different types...

  11. Minimal Pairs: Minimal Importance?

    Science.gov (United States)

    Brown, Adam

    1995-01-01

    This article argues that minimal pairs do not merit as much attention as they receive in pronunciation instruction. There are other aspects of pronunciation that are of greater importance, and there are other ways of teaching vowel and consonant pronunciation. (13 references) (VWL)

  12. Au pair trajectories

    DEFF Research Database (Denmark)

    Dalgas, Karina Märcher

    2015-01-01

    Since 2000, thousands of young Filipino migrants have come to Denmark as au pairs. Officially, they are there to “broaden their cultural horizons” by living temporarily with a Danish host family, but they also conduct domestic labor in exchange for food and money, which allows them to send import...... the Danish au pair scheme therefore speaks to current research on domestic work migration, the transnational family relations of young Filipina migrants and the forms of self-transformation that Filipino migration might engender.......Since 2000, thousands of young Filipino migrants have come to Denmark as au pairs. Officially, they are there to “broaden their cultural horizons” by living temporarily with a Danish host family, but they also conduct domestic labor in exchange for food and money, which allows them to send...... ethnographic component of the dissertation consists of four articles, all emphasizing the au pairs’ agency by viewing their migration as a dynamic personal and social experience. Arguing that Filipina au pairs tend to be understood primarily from the perspective of their precarious situation as domestic...

  13. Anchored paired comparisons

    Science.gov (United States)

    Dalal, E. N.; Handley, J. C.; Wu, W.; Wang, J.

    2008-01-01

    The method of paired comparisons is often used in image quality evaluations. Psychometric scale values for quality judgments are modeled using Thurstone's Law of Comparative Judgment in which distance in a psychometric scale space is a function of the probability of preference. The transformation from psychometric space to probability is a cumulative probability distribution. The major drawback of a complete paired comparison experiment is that every treatment is compared to every other, thus the number of comparisons grows quadratically. We ameliorate this difficulty by performing paired comparisons in two stages, by precisely estimating anchors in the psychometric scale space which are spaced apart to cover the range of scale values and comparing treatments against those anchors. In this model, we employ a generalized linear model where the regression equation has a constant offset vector determined by the anchors. The result of this formulation is a straightforward statistical model easily analyzed using any modern statistics package. This enables model fitting and diagnostics. This method was applied to overall preference evaluations of color pictorial hardcopy images. The results were found to be compatible with complete paired comparison experiments, but with significantly less effort.

  14. Aspectual Pairing in Polish

    NARCIS (Netherlands)

    Młynarczyk, A.K.

    2004-01-01

    The received view on Slavic aspect is that it is intrinsically complex, and that there is little hope of discerning any substantial regularity. We argue that this view is mistaken. We argue that the vast majority of Polish verbs really do come in aspectual pairs and that far from being a mysterious

  15. Excited cooper pairs

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Arrietea, M. G.; Solis, M. A.; De Llano, M. [Universidad Nacional Autonoma de Mexico, Mexico, D.F (Mexico)

    2001-02-01

    Excited cooper pairs formed in a many-fermion system are those with nonzero total center-of mass momentum (CMM). They are normally neglected in the standard Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity for being too few compared with zero CMM pairs. However, a Bose-Einstein condensation picture requires both zero and nonzero CMM pairs. Assuming a BCS model interaction between fermions we determine the populations for all CMM values of Cooper pairs by actually calculating the number of nonzero-CMM pairs relative to that of zero-CMM ones in both 2D and 3D. Although this ratio decreases rapidly with CMM, the number of Cooper pairs for any specific CMM less than the maximum (or breakup of the pair) momentum turns out to be typically larger than about 95% of those with zero-CMM at zero temperature T. Even at T {approx}100 K this fraction en 2D is still as large as about 70% for typical quasi-2D cuprate superconductor parameters. [Spanish] Los pares de cooper excitados formados en un sistema de muchos electrones, son aquellos con momentos de centro de masa (CMM) diferente de cero. Normalmente estos no son tomados en cuenta en la teoria estandar de la superconductividad de Bardeen-Cooper-Schrieffer (BCS) al suponer que su numero es muy pequeno comparados con los pares de centro de masa igual a cero. Sin embargo, un esquema de condensacion Bose-Einstein requiere de ambos pares, con CMM cero y diferente de cero. Asumiendo una interaccion modelo BCS entre los fermiones, determinamos la poblacion de pares cooper con cada uno de todos los posibles valores del CMM calculando el numero de pares con momentos de centro de masa diferente de cero relativo a los pares de CMM igual a cero, en 2D y 3D. Aunque esta razon decrece rapidamente con el CMM, el numero de pares de cooper para cualquier CMM especifico menor que el momento maximo (o rompimiento de par) es tipicamente mas grande que el 95% de aquellos con CMM cero. Aun a T {approx}100 K esta fraccion en 2D es

  16. Multi-pair states in electron-positron pair creation

    Science.gov (United States)

    Wöllert, Anton; Bauke, Heiko; Keitel, Christoph H.

    2016-09-01

    Ultra strong electromagnetic fields can lead to spontaneous creation of single or multiple electron-positron pairs. A quantum field theoretical treatment of the pair creation process combined with numerical methods provides a description of the fermionic quantum field state, from which all observables of the multiple electron-positron pairs can be inferred. This allows to study the complex multi-particle dynamics of electron-positron pair creation in-depth, including multi-pair statistics as well as momentum distributions and spin. To illustrate the potential benefit of this approach, it is applied to the intermediate regime of pair creation between nonperturbative Schwinger pair creation and perturbative multiphoton pair creation where the creation of multi-pair states becomes nonnegligible but cascades do not yet set in. Furthermore, it is demonstrated how spin and helicity of the created electrons and positrons are affected by the polarization of the counterpropagating laser fields, which induce the creation of electron-positron pairs.

  17. Effects of level of social contact on dairy calf behavior and health

    DEFF Research Database (Denmark)

    Jensen, Margit Bak; Larsen, Lars Erik

    2014-01-01

    Housing preweaned dairy calves in pairs rather than individually has been found to positively affect behavioral responses in novel social and environmental situations, but concerns have been raised that close contact among very young animals may impair their health. In previous studies, the level...... of social contact permitted in individual housing has been auditory, visual, or physical contact. It is unclear how these various levels of social contact compare with each other and to pair housing, when their effects on behavior and health are considered, and whether the timing of pair housing has...... an effect. To investigate this, 110 Holstein calves (50 males, 60 females) in 11 blocks were paired according to birth date. Within 60 h of birth, each pair of calves was allocated to 1 of 5 treatments: individual housing with auditory contact (I), individual housing with auditory and visual contact (V...

  18. Junctionless Cooper pair transistor

    Science.gov (United States)

    Arutyunov, K. Yu.; Lehtinen, J. S.

    2017-02-01

    Quantum phase slip (QPS) is the topological singularity of the complex order parameter of a quasi-one-dimensional superconductor: momentary zeroing of the modulus and simultaneous 'slip' of the phase by ±2π. The QPS event(s) are the dynamic equivalent of tunneling through a conventional Josephson junction containing static in space and time weak link(s). Here we demonstrate the operation of a superconducting single electron transistor (Cooper pair transistor) without any tunnel junctions. Instead a pair of thin superconducting titanium wires in QPS regime was used. The current-voltage characteristics demonstrate the clear Coulomb blockade with magnitude of the Coulomb gap modulated by the gate potential. The Coulomb blockade disappears above the critical temperature, and at low temperatures can be suppressed by strong magnetic field.

  19. Protected Flux Pairing Qubit

    Science.gov (United States)

    Bell, Matthew; Zhang, Wenyuan; Ioffe, Lev; Gershenson, Michael

    2014-03-01

    We have studied the coherent flux tunneling in a qubit containing two submicron Josephson junctions shunted by a superinductor (a dissipationless inductor with an impedance much greater than the resistance quantum). The two low energy quantum states of this device, " open="|"> 0 and " open="|"> 1, are represented by even and odd number of fluxes in the loop, respectively. This device is dual to the charge pairing Josephson rhombi qubit. The spectrum of the device, studied by microwave spectroscopy, reflects the interference between coherent quantum phase slips in the two junctions (the Aharonov-Casher effect). The time domain measurements demonstrate the suppression of the qubit's energy relaxation in the protected regime, which illustrates the potential of this flux pairing device as a protected quantum circuit. Templeton Foundation, NSF, and ARO.

  20. Contact Angle Goniometer

    Data.gov (United States)

    Federal Laboratory Consortium — Description:The FTA32 goniometer provides video-based contact angle and surface tension measurement. Contact angles are measured by fitting a mathematical expression...

  1. Corporate Consumer Contact API

    Data.gov (United States)

    General Services Administration — The data in the Corporate Consumer Contact API is based on the content you can find in the Corporate Consumer Contact listing in the Consumer Action Handbook (PDF)....

  2. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... lenses without a prescription in the United States. All contact lenses are medical devices that require a ... no such thing as a "one size fits all" contact lens. Lenses that are not properly fitted ...

  3. Dermatitis, contact (image)

    Science.gov (United States)

    This picture shows a skin inflammation (dermatitis) caused by contact with a material that causes an allergic reaction in this person. Contact dermatitis is a relatively common condition, and can be caused ...

  4. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... sell contacts without a prescription are breaking the law, and may be fined $11,000 per violation. " ... wear any kind of contact lens. In Butler's case, the lenses caused an infection and left her ...

  5. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... Contact Lenses Without a Prescription Sep. 26, 2013 It started as an impulsive buy from a souvenir ... Can Ruin Vision Eye Makeup Safety In fact, it is illegal to sell colored contact lenses without ...

  6. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... not require the same level of care or consideration as a standard contact lens because they can ... sell contacts without a prescription are breaking the law, and may be fined $11,000 per violation. " ...

  7. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... like a suction cup." Halloween is a popular time for people to use colored contact lenses to ... wear costume contact lenses for Halloween or any time of year, follow these guidelines: Get an eye ...

  8. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... glow-in-the-dark lizard lenses, costume contacts can certainly add a spooky, eye-popping touch. But ... consideration as a standard contact lens because they can be purchased over-the-counter or on the ...

  9. Contact Us about Asbestos

    Science.gov (United States)

    How to contact EPA for more information on asbestos, including state and regional contacts, EPA’s Asbestos Abatement/Management Ombudsman and the Toxic Substances Control Act (TSCA) Assistance Information Service (TSCA Hotline).

  10. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... popping touch. But colored contact lenses are popular year-round, not just at Halloween. But few know ... contact lenses for Halloween or any time of year, follow these guidelines: Get an eye exam from ...

  11. Contact lens in keratoconus

    OpenAIRE

    Varsha M Rathi; Preeji S Mandathara; Srikanth Dumpati

    2013-01-01

    Contact lenses are required for the visual improvement in patients with keratoconus. Various contact lens options, such as rigid gas permeable (RGP) lenses, soft and soft toric lenses, piggy back contact lenses (PBCL), hybrid lenses and scleral lenses are availble. This article discusses about selection of a lens depending on the type of keratoconus and the fitting philosophies of various contact lenses including the starting trial lens. A Medline search was carried out for articles in the En...

  12. Coral contact dermatitis

    OpenAIRE

    Jefferson, Julie; Thompson, Curtis; Hinshaw, Molly; Rich, Phoebe

    2015-01-01

    Corals can elicit both toxic and allergic reactions upon contact with the skin. Clinical presentations vary depending on whether the reaction is acute, delayed, or chronic. Literature concerning cutaneous reactions to corals and other Cnidarians is scarce. Herein we report a case of delayed contact hypersensitivity reaction to coral and review the clinical and histopathological features of coral contact dermatitis.

  13. Coral contact dermatitis.

    Science.gov (United States)

    Jefferson, Julie; Thompson, Curtis; Hinshaw, Molly; Rich, Phoebe

    2015-04-16

    Corals can elicit both toxic and allergic reactions upon contact with the skin. Clinical presentations vary depending on whether the reaction is acute, delayed, or chronic. Literature concerning cutaneous reactions to corals and other Cnidarians is scarce. Herein we report a case of delayed contact hypersensitivity reaction to coral and review the clinical and histopathological features of coral contact dermatitis.

  14. Contact urticaria : Present scenario

    Directory of Open Access Journals (Sweden)

    Bhatia Ruchi

    2009-01-01

    Full Text Available Immunological contact urticaria is a hypersensitivity reaction that appears on the skin following contact with an eliciting substance. Recent advances in our understanding of the molecular mechanism and pathogenesis of this reaction have altered its classification, diagnosis, and treatment. We discuss classification, epidemiology, diagnosis, testing, and treatment options that are available to patients with contact urticaria.

  15. Types of Contact Lenses

    Science.gov (United States)

    ... back to top ] Rigid Gas Permeable (RGP) Contact Lenses Rigid gas permeable contact lenses (RGPs) are more durable ... Ortho-K) Orthokeratology, or Ortho-K, is a lens fitting procedure that uses specially designed rigid gas permeable (RGP) contact lenses to change the ...

  16. Mixed lubricated line contacts

    OpenAIRE

    Faraon, Irinel Cosmin

    2005-01-01

    The present work deals with friction in mixed lubricated line contacts. Components in systems are becoming smaller and due to, for instance power transmitted, partial contact may occur. In industrial applications, friction between the moving contacting surfaces cannot be avoided, therefore it is essential that an engineer is able to predict friction.

  17. New Cosmetic Contact Allergens

    Directory of Open Access Journals (Sweden)

    An Goossens

    2015-02-01

    Full Text Available Allergic and photo-allergic contact dermatitis, and immunologic contact urticaria are potential immune-mediated adverse effects from cosmetics. Fragrance components and preservatives are certainly the most frequently observed allergens; however, all ingredients must be considered when investigating for contact allergy.

  18. Au pairs on Facebook

    DEFF Research Database (Denmark)

    Dalgas, Karina Märcher

    2016-01-01

    Ethnographers are increasingly making use of Facebook to acquire access and general acquaintance with their field of study. However, little has been written on how Facebook is used methodologically in research that does not have social media sites as the main focus of interest. This article argues...... that engagement with Facebook as a methodological tool can be useful in research among migrants in highly politicised fields. Pointing to a discursive construction of Filipina au pairs as victims of labour exploitation, the article shows how fieldwork on Facebook enables the exploration of the ways in which...... and on Facebook....

  19. Multispecies pair annihilation reactions.

    Science.gov (United States)

    Deloubrière, Olivier; Hilhorst, Henk J; Täuber, Uwe C

    2002-12-16

    We consider diffusion-limited reactions A(i)+A(j)--> (12 and d> or =2, we argue that the asymptotic density decay for such mutual annihilation processes with equal rates and initial densities is the same as for single-species pair annihilation A+A-->. In d=1, however, particle segregation occurs for all q< infinity. The total density decays according to a q dependent power law, rho(t) approximately t(-alpha(q)). Within a simplified version of the model alpha(q)=(q-1)/2q can be determined exactly. Our findings are supported through Monte Carlo simulations.

  20. Au pairs on Facebook

    DEFF Research Database (Denmark)

    Dalgas, Karina Märcher

    2016-01-01

    Ethnographers are increasingly making use of Facebook to acquire access and general acquaintance with their field of study. However, little has been written on how Facebook is used methodologically in research that does not have social media sites as the main focus of interest. This article argues...... that engagement with Facebook as a methodological tool can be useful in research among migrants in highly politicised fields. Pointing to a discursive construction of Filipina au pairs as victims of labour exploitation, the article shows how fieldwork on Facebook enables the exploration of the ways in which...... and on Facebook....

  1. Contact analysis and load distribution of double-envelop hourglassworm gearing affected by errors and load

    Institute of Scientific and Technical Information of China (English)

    XU Wujiao; QIN Datong; SHI Wankai

    2003-01-01

    An approach for the contact analysis and load distribution of double-envelop hourglass worm gearing is presented,which is based on a 3-D elastic contact finite element method (FEM) model that 3ccommodates the influence of errors and load.As compared with existing tooth contact analysis model that assumes rigidity for the contacting surfaces, the proposed model provides a more realistic analysis on the contact patterns, the distribution of contact load and transmission errors. It is also capable of exploring the influence of different errors on meshing performances, the contact deformation, the shift of the contact zone and load share among the meshing tooth-pairs under different load.

  2. Contact lens in keratoconus

    Directory of Open Access Journals (Sweden)

    Varsha M Rathi

    2013-01-01

    Full Text Available Contact lenses are required for the visual improvement in patients with keratoconus. Various contact lens options, such as rigid gas permeable (RGP lenses, soft and soft toric lenses, piggy back contact lenses (PBCL, hybrid lenses and scleral lenses are availble. This article discusses about selection of a lens depending on the type of keratoconus and the fitting philosophies of various contact lenses including the starting trial lens. A Medline search was carried out for articles in the English language with the keywords keratoconus and various contact lenses such as Rose k lens, RGP lens, hybrid lens, scleral lens and PBCL.

  3. Searching for Pair Halos

    Science.gov (United States)

    Fallon, Lisa; Abramowski, A.; Acero, F.; Aharonian, F.; Akhperjanian, A. G.; Anton, G.; Barres de Almeida, U.; Bazer-Bachi, A. R.; Becherini, Y.; Behera, B.; Bernlühr, K.; Bochow, A.; Boisson, C.; Bolmont, J.; Borrel, V.; Brucker, J.; Brun, F.; Brun, P.; Bühler, R.; Bulik, T.; Büsching, I.; Boutelier, T.; Chadwick, P. M.; Charbonnier, A.; Chaves, R. C. G.; Cheesebrough, A.; Conrad, J.; Chounet, L.-M.; Clapson, A. C.; Coignet, G.; Dalton, M.; Daniel, M. K.; Davids, I. D.; Degrange, B.; Deil, C.; Dickinson, H. J.; Domainko, A. Djannati-Ataü W.; Drury, L. O'c.; Dubois, F.; Dubus, G.; Dyks, J.; Dyrda, M.; Egberts, K.; Eger, P.; Espigat, P.; Fallon, L.; Farnier, C.; Fegan, S.; Feinstein, F.; Fernandes, M. V.; Fiasson, A.; Fürster, A.; Fontaine, G.; Füssling, M.; Gabici, S.; Gallant, Y. A.; Gérard, L.; Gerbig, D.; Giebels, B.; Glicenstein, J. F.; Glück, B.; Goret, P.; Güring, D.; Hampf, D.; Hauser, M.; Heinz, S.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hinton, J. A.; Hoffmann, A.; Hofmann, W.; Hofverberg, P.; Holleran, M.; Hoppe, S.; Horns, D.; Jacholkowska, A.; de Jager, O. C.; Jahn, C.; Jung, I.; Katarzynski, K.; Katz, U.; Kaufmann, S.; Kerschhaggl, M.; Khangulyan, D.; Khálifi, B.; Keogh, D.; Klochkov, D.; Kluzniak, W.; Kneiske, T.; Komin, Nu.; Kosack, K.; Kossakowski, R.; Lamanna, G.; Lenain, J.-P.; Lohse, T.; Lu, C.-C.; Marandon, V.; Marcowith, A.; Masbou, J.; Mau-Rin, D.; McComb, T. J. L.; Medina, M. C.; Méhault, J.; Moderski, R.; Moulin, E.; Naumann-Godo, M.; de Naurois, M.; Nedbal, D.; Nekrassov, D.; Nguyen, N.; Nicholas, B.; Niemiec, J.; Nolan, S. J.; Ohm, S.; Olive, J.-F.; de Ona Wilhelmi, E.; Opitz, B.; Orford, K. J.; Ostrowski, M.; Panter, M.; Paz Arribas, M.; Pedaletti, G.; Pelletier, G.; Petrucci, P.-O.; Pita, S.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raubenheimer, B. C.; Raue, M.; Rayner, S. M.; Reimer, O.; Renaud, M.; de Los Reyes, R.; Rieger, F.; Ripken, J.; Rob, L.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Ruppel, J.; Ryde, F.; Sahakian, V.; Santangelo, A.; Schlickeiser, R.; Schück, F. M.; Schünwald, A.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Shalchi, A.; Sushch, I.; Sikora, M.; Skilton, J. L.; Sol, H.; Stawarz, L.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Szostek, A.; Tam, P. H.; Tavernet, J.-P.; Terrier, R.; Tibolla, O.; Tluczykont, M.; Valerius, K.; van Eldik, C.; Vasileiadis, G.; Venter, C.; Venter, L.; Vialle, J. P.; Viana, A.; Vincent, P.; Vivier, M.; Vülk, H. J.; Volpe, F.; Vorobiov, S.; Wagner, S. J.; Ward, M.; Zdziarski, A. A.; Zech, A.; Zechlin, H.-S.

    We have conducted a search for the giant Pair Halo structures which are inevitably formed around TeV sources due to interactions of very high energy gamma-rays with the Extragalactic Background Light (EBL). The resulting electron/positron pairs are Compton upscattered on photons of the 2.7 K Cosmic Microwave Background Radiation to produce a second generation of gamma-rays which again interact with the EBL; thus an electromagnetic cascade develops. If the magnetic fields on Mpc scales surrounding the central source are sufficiently strong (10-11 G or more), electrons are effectively isotropised before interacting with radiation fields. In this case an extended halo is produced around the source. Using H.E.S.S. observations of Active Galactic Nuclei, including data from PKS 2155-304, 1ES 1101-232 and 1ES 0229+200, we have completed a detailed analysis of these sources. I will present and discuss the astrophysical implications of these results.

  4. Modeling Thermal Contact Resistance

    Science.gov (United States)

    Kittel, Peter; Sperans, Joel (Technical Monitor)

    1994-01-01

    One difficulty in using cryocoolers is making good thermal contact between the cooler and the instrument being cooled. The connection is often made through a bolted joint. The temperature drop associated with this joint has been the subject of many experimental and theoretical studies. The low temperature behavior of dry joints have shown some anomalous dependence on the surface condition of the mating parts. There is also some doubts on how well one can extrapolate from the test samples to predicting the performance of a real system. Both finite element and analytic models of a simple contact system have been developed. The model assumes (a) the contact is dry (contact limited to a small portion of the total available area and the spaces in-between the actual contact patches are perfect insulators), (b) contacts are clean (conductivity of the actual contact is the same as the bulk), (c) small temperature gradients (the bulk conductance may be assumed to be temperature independent), (d) the absolute temperature is low (thermal radiation effects are ignored), and (e) the dimensions of the nominal contact area are small compared to the thickness of the bulk material (the contact effects are localized near the contact). The models show that in the limit of actual contact area much less than the nominal area (a much less than A), that the excess temperature drop due to a single point of contact scales as a(exp -1/2). This disturbance only extends a distance approx. A(exp 1/2) into the bulk material. A group of identical contacts will result in an excess temperature drop that scales as n(exp -1/2), where n is the number of contacts and n dot a is constant. This implies that flat rough surfaces will have a lower excess temperature drop than flat polished surfaces.

  5. Static Coefficient of Rolling Friction at High Contact Temperatures and Various Contact Pressure

    Directory of Open Access Journals (Sweden)

    B. Tadić

    2016-03-01

    Full Text Available The paper theoretically and experimentally analyzes the influence of increased temperature and load contact in the value of the coefficient of rolling friction. Theoretical analyzes show that at temperatures of the order of 200 0C, exist thermal potential necessary to narrow contact zone leads to a redistribution of the contact pressure and an increase in torque performance. Based on the measurement results, established the regression coefficient of friction depending on the temperature, normal load and geometry parameters of contact elements (radius of curvature of the contact elements. Material of examination contact pairs is steel ASTM A-295 hardness 64-66 HRC. The measurement results indicate a very significant impact on the temperature coefficient of friction, normal load and contact geometry (the radius of curvature of the contact elements. According to the authors future research should focus on optimizing the choice of materials that under the given conditions of mechanical and thermal load of contact to ensure a minimum value of the coefficient of rolling friction.

  6. Fission: statistical nucleon pair breaking

    Energy Technology Data Exchange (ETDEWEB)

    Montoya, M. (Instituto Peruano de Energia Nuclear, Lima (Peru))

    1984-06-01

    In order to explain the odd-even effect observed in low energy fission fragment distributions it has been recently required a double mechanism of nucleon pair breaking: before scission (early pair breaking) and at scission (late pair breaking), respectively. In the present work we show that, using the same formulae but considering only the early pair breaking mechanism, one can reproduce fairly well all the available experimental data on the odd-even effects.

  7. Diffractive charged meson pair production

    CERN Document Server

    Lehmann-Dronke, B; Schäfer, S; Stein, E; Schäfer, A

    1999-01-01

    We investigate the possibility to measure the nonforward gluon distribution function by means of diffractively produced charged pion and kaon pairs in polarized lepton nucleon scattering. The resulting cross sections are sizable and are dominated by the gluonic contribution. We find large spin asymmetries, both for pion pairs and for kaon pairs.

  8. Application of Acupoints in Pairs

    Institute of Scientific and Technical Information of China (English)

    季扬

    2004-01-01

    @@ Application of acupoints in pairs is a kind of point association in which only a pair of compatible points is used. Based on the principle of compatibility, the author of this article often uses the "pair-point needling" to treat some common diseases, and have obtained very good therapeutic results. Some examples are introduced below.

  9. Cotorsion Pair Extensions

    Institute of Scientific and Technical Information of China (English)

    De Xu ZHOU

    2009-01-01

    Assume that S is an almost excellent extension of R. Using functors Hom R(S,-) and -(×)R S, we establish some connections between classes of modules (L)R and (L)S, cotorsion pairs ((A)R, (A)R)and ((A)S, (B)S). If (L)S is a T-extension or (and) H-extension of (L)R, we show that (L)S is a (resp., monomorphic, epimorphic, special) preenveloping class if and only if so is (L)R. If (S, S) is a TH-extension of ((A)R,(B)R), we obtain that ((A)S,(B)S) is complete (resp., of finite type, of cofinite type, hereditary, perfect, n-tilting) if and only if so is ((A)R,(B)R).

  10. Evaluation of residue-residue contact predictions in CASP9

    KAUST Repository

    Monastyrskyy, Bohdan

    2011-01-01

    This work presents the results of the assessment of the intramolecular residue-residue contact predictions submitted to CASP9. The methodology for the assessment does not differ from that used in previous CASPs, with two basic evaluation measures being the precision in recognizing contacts and the difference between the distribution of distances in the subset of predicted contact pairs versus all pairs of residues in the structure. The emphasis is placed on the prediction of long-range contacts (i.e., contacts between residues separated by at least 24 residues along sequence) in target proteins that cannot be easily modeled by homology. Although there is considerable activity in the field, the current analysis reports no discernable progress since CASP8.

  11. Enhancing imagined contact to reduce prejudice against people with schizophrenia

    Science.gov (United States)

    West, Keon; Holmes, Emily; Hewstone, Miles

    2015-01-01

    Four studies investigated the effect of imagining intergroup contact on prejudice against people with schizophrenia. Experiments 1 and 2 demonstrated that a neutral imagined contact task can have negative effects, compared to a control condition, even when paired with incidental positive information (Experiment 2). Experiments 3 and 4 demonstrated, however, that an integrated positive imagined contact scenario does result in less intergroup anxiety and more positive attitudes, even toward this challenging group. Analyses of participants’ descriptions of the imagined interactions in and across the first three studies confirm that positive and high quality imagined contact is important for reducing prejudice, but failing to ensure that imagined contact is positive may have deleterious consequences. We emphasize the importance of investigating the quality of the imagined contact experience, and discuss the implications for using imagined contact as a prejudice-reducing intervention. PMID:26435686

  12. Contact angle hysteresis explained.

    Science.gov (United States)

    Gao, Lichao; McCarthy, Thomas J

    2006-07-04

    A view of contact angle hysteresis from the perspectives of the three-phase contact line and of the kinetics of contact line motion is given. Arguments are made that advancing and receding are discrete events that have different activation energies. That hysteresis can be quantified as an activation energy by the changes in interfacial area is argued. That this is an appropriate way of viewing hysteresis is demonstrated with examples.

  13. Introduction to contact mechanics

    CERN Document Server

    Fischer-Cripps, Anthony C

    2000-01-01

    Contact mechanics deals with the elastic or plastic contact between two solid objects, and is thus intimately connected with such topics as fracture, hardness, and elasticity.This text, intended for advanced undergraduates, begins with an introduction to the mechanical properties of materials, general fracture mechanics, and fractures in brittle solids.This is followed by a detailed discussion of stresses and the nature of elastic and elastic-plastic contact.

  14. Multi-pair states in electron–positron pair creation

    Directory of Open Access Journals (Sweden)

    Anton Wöllert

    2016-09-01

    Full Text Available Ultra strong electromagnetic fields can lead to spontaneous creation of single or multiple electron–positron pairs. A quantum field theoretical treatment of the pair creation process combined with numerical methods provides a description of the fermionic quantum field state, from which all observables of the multiple electron–positron pairs can be inferred. This allows to study the complex multi-particle dynamics of electron–positron pair creation in-depth, including multi-pair statistics as well as momentum distributions and spin. To illustrate the potential benefit of this approach, it is applied to the intermediate regime of pair creation between nonperturbative Schwinger pair creation and perturbative multiphoton pair creation where the creation of multi-pair states becomes nonnegligible but cascades do not yet set in. Furthermore, it is demonstrated how spin and helicity of the created electrons and positrons are affected by the polarization of the counterpropagating laser fields, which induce the creation of electron–positron pairs.

  15. Experimental many-pairs nonlocality

    Science.gov (United States)

    Poh, Hou Shun; Cerè, Alessandro; Bancal, Jean-Daniel; Cai, Yu; Sangouard, Nicolas; Scarani, Valerio; Kurtsiefer, Christian

    2017-08-01

    Collective measurements on large quantum systems together with a majority voting strategy can lead to a violation of the Clauser-Horne-Shimony-Holt Bell inequality. In the presence of many entangled pairs, this violation decreases quickly with the number of pairs and vanishes for some critical pair number that is a function of the noise present in the system. Here we show that a different binning strategy can lead to a more substantial Bell violation when the noise is sufficiently small. Given the relation between the critical pair number and the source noise, we then present an experiment where the critical pair number is used to quantify the quality of a high visibility photon pair source. Our results demonstrate nonlocal correlations using collective measurements operating on clusters of more than 40 photon pairs.

  16. Allergic Contact Dermatitis

    Directory of Open Access Journals (Sweden)

    Meltem Önder

    2009-03-01

    Full Text Available Allergic contact dermatitis is the delayed type hypersensitivity reaction to exogenous agents. Allergic contact dermatitis may clinically present acutely after allergen exposure and initial sensitization in a previously sensitized individual. Acute phase is characterized by erythematous, scaly plaques. In severe cases vesiculation and bullae in exposed areas are very characteristic. Repeated or continuous exposure of sensitized individual with allergen result in chronic dermatitis. Lichenification, erythematous plaques, hyperkeratosis and fissuring may develop in chronic patients. Allergic contact dermatitis is very common dermatologic problem in dermatology daily practice. A diagnosis of contact dermatitis requires the careful consideration of patient history, physical examination and patch testing. The knowledge of the clinical features of the skin reactions to various contactans is important to make a correct diagnosis of contact dermatitis. It can be seen in every age, in children textile product, accessories and touch products are common allergens, while in adults allergic contact dermatitis may be related with topical medicaments. The contact pattern of contact dermatitis depends on fashion and local traditions as well. The localization of allergic reaction should be evaluated and patients’ occupation and hobbies should be asked. The purpose of this review is to introduce to our collaques up dated allergic contact dermatitis literatures both in Turkey and in the World.

  17. Contact Quality in Participation

    DEFF Research Database (Denmark)

    Simonsen, Jesper; Jensen, Olav Storm

    2016-01-01

    We investigate the concept of participation from the perspective of quality of the contact in the communicative interactions between participants. We argue for the need for an academic-personal competence that qualifies the human contact central in all Participatory Design (PD) activities as a way...... to contribute to “an era of participation.” We describe a contact perspective in PD developed through a collaboration with body-oriented psychotherapeutic research that have specialized experiences in investigating open-minded contact and authentic meetings as body-related experiences....

  18. Colors and contact dermatitis.

    Science.gov (United States)

    Bonamonte, Domenico; Foti, Caterina; Romita, Paolo; Vestita, Michelangelo; Angelini, Gianni

    2014-01-01

    The diagnosis of skin diseases relies on several clinical signs, among which color is of paramount importance. In this review, we consider certain clinical presentations of both eczematous and noneczematous contact dermatitis in which color plays a peculiar role orientating toward the right diagnosis. The conditions that will be discussed include specific clinical-morphologic subtypes of eczematous contact dermatitis, primary melanocytic, and nonmelanocytic contact hyperchromia, black dermographism, contact chemical leukoderma, and others. Based on the physical, chemical, and biologic factors underlying a healthy skin color, the various skin shades drawing a disease picture are thoroughly debated, stressing their etiopathogenic origins and histopathologic aspects.

  19. Sutures and contact homology I

    CERN Document Server

    Colin, Vincent; Honda, Ko; Hutchings, Michael

    2010-01-01

    We define a relative version of contact homology for contact manifolds with convex boundary, and prove basic properties of this relative contact homology. Similar considerations also hold for embedded contact homology.

  20. Pairing the Volcano

    CERN Document Server

    Ionica, Sorina

    2011-01-01

    Isogeny volcanoes are graphs whose vertices are elliptic curves and whose edges are $\\ell$-isogenies. Algorithms allowing to travel on these graphs were developed by Kohel in his thesis (1996) and later on, by Fouquet and Morain (2001). However, up to now, no method was known, to predict, before taking a step on the volcano, the direction of this step. Hence, in Kohel's and Fouquet-Morain algorithms, many steps are taken before choosing the right direction. In particular, ascending or horizontal isogenies are usually found using a trial-and-error approach. In this paper, we propose an alternative method that efficiently finds all points $P$ of order $\\ell$ such that the subgroup generated by $P$ is the kernel of an horizontal or an ascending isogeny. In many cases, our method is faster than previous methods. This is an extended version of a paper published in the proceedings of ANTS 2010. In addition, we treat the case of 2-isogeny volcanoes and we derive from the group structure of the curve and the pairing ...

  1. Frictional Effects on Gear Tooth Contact Analysis

    Directory of Open Access Journals (Sweden)

    Zheng Li

    2013-01-01

    Full Text Available The present paper concentrates on the investigations regarding the situations of frictional shear stress of gear teeth and the relevant frictional effects on bending stresses and transmission error in gear meshing. Sliding friction is one of the major reasons causing gear failure and vibration; the adequate consideration of frictional effects is essential for understanding gear contact behavior accurately. An analysis of tooth frictional effect on gear performance in spur gear is presented using finite element method. Nonlinear finite element model for gear tooth contact with rolling/sliding is then developed. The contact zones for multiple tooth pairs are identified and the associated integration situation is derived. The illustrated bending stress and transmission error results with static and dynamic boundary conditions indicate the significant effects due to the sliding friction between the surfaces of contacted gear teeth, and the friction effect can not be ignored. To understand the particular static and dynamic frictional effects on gear tooth contact analysis, some significant phenomena of gained results will also be discussed. The potentially significant contribution of tooth frictional shear stress is presented, particularly in the case of gear tooth contact analysis with both static and dynamic boundary conditions.

  2. Screw bondgraph contact dynamics

    NARCIS (Netherlands)

    Visser, Martijn; Stramigioli, Stefano; Heemskerk, Cock

    2002-01-01

    This paper presents an elegant contact dynamics model in screw bondgraph form. It can model the contact between any two objects of finite curvature. It does so by defining a Gauss frame on the surfaces of both objects in the points that are closest to each other. Then it describes how the Gauss fram

  3. Contact dermatitis. A review

    DEFF Research Database (Denmark)

    Andersen, Klaus Ejner; Benezra, C; Burrows, D;

    1987-01-01

    In recent years, there has been a dramatic rise in our understanding of contact dermatitis. This paper is a review of our knowledge of the mechanisms involved in contact dermatitis and related phenomena, the investigation of these events and the emergence of significant new allergens during...

  4. Allergic Contact Dermatitis

    OpenAIRE

    Meltem Önder

    2009-01-01

    Allergic contact dermatitis is the delayed type hypersensitivity reaction to exogenous agents. Allergic contact dermatitis may clinically present acutely after allergen exposure and initial sensitization in a previously sensitized individual. Acute phase is characterized by erythematous, scaly plaques. In severe cases vesiculation and bullae in exposed areas are very characteristic. Repeated or continuous exposure of sensitized individual with allergen result in chronic dermatitis. Lichenific...

  5. Critical Points of Contact

    DEFF Research Database (Denmark)

    Jensen, Ole B.; Morelli, Nicola

    2011-01-01

    where the networks meet and establish contact. Thus we argue for the usefulness of the notion of Critical Point of Contact (CPC) to deepen our understanding of the actual life within networks. En route to this notion we draw upon theories within as diverse realms such as interaction design, service...

  6. Contact Hamiltonian mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Bravetti, Alessandro, E-mail: alessandro.bravetti@iimas.unam.mx [Instituto de Investigaciones en Matemáticas Aplicadas y en Sistemas, Universidad Nacional Autónoma de México, A. P. 70543, México, DF 04510 (Mexico); Cruz, Hans, E-mail: hans@ciencias.unam.mx [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, A. P. 70543, México, DF 04510 (Mexico); Tapias, Diego, E-mail: diego.tapias@nucleares.unam.mx [Facultad de Ciencias, Universidad Nacional Autónoma de México, A.P. 70543, México, DF 04510 (Mexico)

    2017-01-15

    In this work we introduce contact Hamiltonian mechanics, an extension of symplectic Hamiltonian mechanics, and show that it is a natural candidate for a geometric description of non-dissipative and dissipative systems. For this purpose we review in detail the major features of standard symplectic Hamiltonian dynamics and show that all of them can be generalized to the contact case.

  7. Contact materials for nanoelectronics

    KAUST Repository

    Alshareef, Husam N.

    2011-02-01

    In this article, we review current research activities in contact material development for electronic and nanoelectronic devices. A fundamental issue in contact materials research is to understand and control interfacial reactions and phenomena that modify the expected device performance. These reactions have become more challenging and more difficult to control as new materials have been introduced and as device sizes have entered the deep nanoscale. To provide an overview of this field of inquiry, this issue of MRS Bulletin includes articles on gate and contact materials for Si-based devices, junction contact materials for Si-based devices, and contact materials for alternate channel substrates (Ge and III-V), nanodevices. © 2011 Materials Research Society.

  8. Refining intra-protein contact prediction by graph analysis

    Directory of Open Access Journals (Sweden)

    Eyal Eran

    2007-05-01

    Full Text Available Abstract Background Accurate prediction of intra-protein residue contacts from sequence information will allow the prediction of protein structures. Basic predictions of such specific contacts can be further refined by jointly analyzing predicted contacts, and by adding information on the relative positions of contacts in the protein primary sequence. Results We introduce a method for graph analysis refinement of intra-protein contacts, termed GARP. Our previously presented intra-contact prediction method by means of pair-to-pair substitution matrix (P2PConPred was used to test the GARP method. In our approach, the top contact predictions obtained by a basic prediction method were used as edges to create a weighted graph. The edges were scored by a mutual clustering coefficient that identifies highly connected graph regions, and by the density of edges between the sequence regions of the edge nodes. A test set of 57 proteins with known structures was used to determine contacts. GARP improves the accuracy of the P2PConPred basic prediction method in whole proteins from 12% to 18%. Conclusion Using a simple approach we increased the contact prediction accuracy of a basic method by 1.5 times. Our graph approach is simple to implement, can be used with various basic prediction methods, and can provide input for further downstream analyses.

  9. Multiple origins of asteroid pairs

    CERN Document Server

    Jacobson, Seth A

    2015-01-01

    Rotationally fissioned asteroids produce unbound daughter asteroids that have very similar heliocentric orbits. Backward integration of their current heliocentric orbits provides an age of closest proximity that can be used to date the rotational fission event. Most asteroid pairs follow a predicted theoretical relationship between the primary spin period and the mass ratio of the two pair members that is a direct consequence of the YORP-induced rotational fission hypothesis. If the progenitor asteroid has strength, asteroid pairs may have high mass ratios with possibly fast rotating primaries. However, secondary fission leaves the originally predicted trend unaltered. We also describe the characteristics of pair members produced by four alternative routes from a rotational fission event to an asteroid pair. Unlike direct formation from the event itself, the age of closest proximity of these pairs cannot generally be used to date the rotational fission event since considerable time may have passed.

  10. Dependence of Two-proton Radioactivity on Nuclear Pairing Models

    CERN Document Server

    Oishi, Tomohiro; Pastore, Alessandro

    2016-01-01

    The sensitivity of two-proton emitting decays to the nuclear pairing correlation is discussed within a time-dependent three-body model. We focus on the $^6$Be nucleus assuming $\\alpha + p + p$ configuration, and its decay process is described as a time-evolution of the three-body resonance state. A noticeable model-dependence of two-proton decay width is found by utilizing schematic density-dependent contact (SDDC) and the finite-range Minnesota pairing models. The model-dependence with the SDDC pairing interaction can be understood from the density distribution of the resonance state, which reflects a synergy of participating interactions. Our result suggests that two-proton decay width may be a suitable reference quantity to sophisticate the nuclear pairing model beyond the nucleon driplines.

  11. Allergic contact dermatitis.

    Science.gov (United States)

    Becker, Detlef

    2013-07-01

    Allergic contact dermatitis is a frequent inflammatory skin disease. The suspected diagnosis is based on clinical symptoms, a plausible contact to allergens and a suitable history of dermatitis. Differential diagnoses should be considered only after careful exclusion of any causal contact sensitization. Hence, careful diagnosis by patch testing is of great importance. Modifications of the standardized test procedure are the strip patch test and the repeated open application test. The interpretation of the SLS (sodium lauryl sulfate) patch test as well as testing with the patients' own products and working materials are potential sources of error. Accurate patch test reading is affected in particular by the experience and individual factors of the examiner. Therefore, a high degree of standardization and continuous quality control is necessary and may be supported by use of an online patch test reading course made available by the German Contact Dermatitis Research Group. A critical relevance assessment of allergic patch test reactions helps to avoid relapses and the consideration of differential diagnoses. Any allergic test reaction should be documented in an allergy ID card including the INCI name, if appropriate. The diagnostics of allergic contact dermatitis is endangered by a seriously reduced financing of patch testing by the German statutory health insurances. Restrictive regulations by the German Drug Law block the approval of new contact allergens for routine patch testing. Beside the consistent avoidance of allergen contact, temporary use of systemic and topical corticosteroids is the therapy of first choice.

  12. Hormonal predictors of women's extra-pair vs. in-pair sexual attraction in natural cycles: Implications for extended sexuality.

    Science.gov (United States)

    Grebe, Nicholas M; Emery Thompson, Melissa; Gangestad, Steven W

    2016-02-01

    In naturally cycling women, Roney and Simmons (2013) examined hormonal correlates of their desire for sexual contact. Estradiol was positively associated, and progesterone negatively associated, with self-reported desire. The current study extended these findings by examining, within a sample of 33 naturally cycling women involved in romantic relationships, hormonal correlates of sexual attraction to or interests in specific targets: women's own primary partner or men other than women's primary partner. Women's sexual interests and hormone (estradiol, progesterone, and testosterone) levels were assessed at two different time points. Whereas estradiol levels were associated with relatively greater extra-pair sexual interests than in-pair sexual interests, progesterone levels were associated with relatively greater in-pair sexual interests. Both hormones specifically predicted in-pair sexual desire, estradiol negatively and progesterone positively. These findings have implications for understanding the function of women's extended sexuality - their sexual proceptivity and receptivity outside the fertile phase, especially during the luteal phase.

  13. Potentially pathogenic free-living amoebae in contact lenses of the asymptomatic contact lens wearers.

    Directory of Open Access Journals (Sweden)

    Maryam Niyyati

    2014-03-01

    Full Text Available Free-living amoebae (FLA including Acanthamoeba spp. and Hartmannella spp. are the causative agents of serious corneal infection especially within contact lens wearers. Thus contact lenses and their storage case could be a suitable niche for potentially pathogenic amoebae. The main objective of the present study was to evaluate the contamination of contact lenses to free living amoebae using morphological and sequencing based methods.Overall, 90 volunteers provided their contact lenses. All volunteers wore soft contact lenses. Both lenses were cultured in the same plate. Forty-eight of the volunteers were medical and dentistry student and 42 were ophthalmology attendees of hospitals in Tehran, Iran. All of the samples were inoculated to non-nutrient medium and monitored daily for the outgrowth of the amoebae. PCR and sequencing were performed using various primer pairs.Of the 90 volunteers, 9 (10% were positive for free-living amoebae outgrowth. Morphological analysis revealed that 3 isolates were belonged to Hartmannella genus according to small round cysts and 6 isolates were belonged to Acanthamoeba genus based on the star shape of endocysts. Sequencing revealed that Acanthamoeba belonged to T4, T3 and T5 genotype. Hartmannella were also belonged to vermiformis species.The presence of potentially pathogenic free living amoebae including Acanthamoeba and Hartmannella could be a high risk for people using soft contact lenses. These results revealed that improved clarification and professional recommendations for contact lens wearers is of utmost importance.

  14. PERIODIC COMPLEMENTARY BINARY SEQUENCE PAIRS

    Institute of Scientific and Technical Information of China (English)

    XuChengqian; ZhaoXiaoqun

    2002-01-01

    A new set of binary sequences-Periodic Complementary Binary Sequence Pair (PCSP)is proposed .A new class of block design-Difference Family Pair (DFP)is also proposed .The relationship between PCSP and DFP,the properties and exising conditions of PCSP and the recursive constructions for PCSP are given.

  15. PERIODIC COMPLEMENTARY BINARY SEQUENCE PAIRS

    Institute of Scientific and Technical Information of China (English)

    Xu Chengqian; Zhao Xiaoqun

    2002-01-01

    A new set of binary sequences-Periodic Complementary Binary Sequence Pair (PCSP) is proposed. A new class of block design-Difference Family Pair (DFP) is also proposed.The relationship between PCSP and DFP, the properties and existing conditions of PCSP and the recursive constructions for PCSP are given.

  16. Assessment Strategies for Pair Programming

    Science.gov (United States)

    Hahn, Jan Hendrik; Mentz, Elsa; Meyer, Lukas

    2009-01-01

    Although pair programming has proved its usefulness in teaching and learning programming skills, it is difficult to assess the individual roles and abilities of students whilst programming in pairs. (Note that within this manuscript, the term assessment refers to evaluating individual student performance.) Assessing only the outcomes of a pair…

  17. Instability of vortex pair leapfrogging

    DEFF Research Database (Denmark)

    Tophøj, Laust; Aref, Hassan

    2013-01-01

    pairs fly off to infinity, and a "walkabout" mode, where the vortices depart from leapfrogging but still remain within a finite distance of one another. We show numerically that this transition is more gradual, a result that we relate to earlier investigations of chaotic scattering of vortex pairs [L...

  18. Kramers Pairs in configuration interaction

    DEFF Research Database (Denmark)

    Avery, John Scales; Avery, James Emil

    2003-01-01

    The theory of symmetry-preserving Kramers pair creation operators is reviewed and formulas for applying these operators to configuration interaction calculations are derived. A new and more general type of symmetry-preserving pair creation operator is proposed and shown to commute with the total...

  19. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... about the members of the eye-care team . Consumer warning about the improper use of colored contact ... About the Academy Jobs at the Academy Financial Relationships with Industry Medical Disclaimer Privacy Policy Terms of ...

  20. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... Patient Stories Español Eye Health / News Halloween Hazard: The Hidden Dangers of Buying Decorative Contact Lenses Without ... been properly fitted by an eye care professional, the lenses stuck to my eye like a suction ...

  1. Tomato contact dermatitis

    DEFF Research Database (Denmark)

    Paulsen, Evy; Christensen, Lars P; Andersen, Klaus Ejner

    2012-01-01

    The tomato plant (Solanum lycopersicum) is an important crop worldwide. Whereas immediate-type reactions to tomato fruits are well known, contact dermatitis caused by tomatoes or tomato plants is rarely reported. The aims of this study were to present new data on contact sensitization to tomato...... plants and review the literature on contact dermatitis caused by both plants and fruits. An ether extract of tomato plants made as the original oleoresin plant extracts, was used in aimed patch testing, and between 2005 and 2011. 8 of 93 patients (9%) tested positive to the oleoresin extracts....... This prevalence is in accordance with the older literature that reports tomato plants as occasional sensitizers. The same applies to tomato fruits, which, in addition, may cause protein contact dermatitis. The allergens of the plant are unknown, but both heat-stable and heat-labile constituents seem...

  2. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... wear any kind of contact lens. In Butler's case, the lenses caused an infection and left her with a corneal abrasion. ... Studies Look at Effects of Marijuana on Vision FEB ...

  3. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... lentes de contacto de color Sep. 26, 2013 It started as an impulsive buy from a souvenir ... Can Ruin Vision Eye Makeup Safety In fact, it is illegal to sell colored contact lenses without ...

  4. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... not require the same level of care or consideration as a standard contact lens because they can ... Us About the Academy Jobs at the Academy Financial Relationships with Industry Medical Disclaimer Privacy Policy Terms ...

  5. Contact Lens Risks

    Science.gov (United States)

    ... Tap and distilled water have been associated with Acanthamoeba keratitis, a corneal infection that is resistant to ... to: Advice for Patients With Soft Contact Lenses: Acanthamoeba Keratitis Infections Related to Complete® MoisturePlus Multi Purpose ...

  6. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... colored contact lenses , from the U.S. Food and Drug Administration (FDA). Are the colored lenses you are ... from dry eye now have a completely new, drug-free alternative to lubricating eye drops and topical ...

  7. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... be purchased over-the-counter or on the Internet," says Thomas Steinemann, MD, professor of ophthalmology at ... ask for a prescription. There is no such thing as a "one size fits all" contact lens. ...

  8. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... also available in Spanish . Follow The Academy Professionals: Education Guidelines News Multimedia Public & Patients: Contact Us About the Academy Jobs at the Academy Financial Relationships with Industry Medical ...

  9. Fragrance allergic contact dermatitis.

    Science.gov (United States)

    Cheng, Judy; Zug, Kathryn A

    2014-01-01

    Fragrances are a common cause of allergic contact dermatitis in Europe and in North America. They can affect individuals at any age and elicit a spectrum of reactions from contact urticaria to systemic contact dermatitis. Growing recognition of the widespread use of fragrances in modern society has fueled attempts to prevent sensitization through improved allergen identification, labeling, and consumer education. This review provides an overview and update on fragrance allergy. Part 1 discusses the epidemiology and evaluation of suspected fragrance allergy. Part 2 reviews screening methods, emerging fragrance allergens, and management of patients with fragrance contact allergy. This review concludes by examining recent legislation on fragrances and suggesting potential additions to screening series to help prevent and detect fragrance allergy.

  10. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... Follow The Academy Professionals: Education Guidelines News Multimedia Public & Patients: Contact Us About the Academy Jobs at the Academy Financial Relationships with Industry Medical Disclaimer Privacy Policy Terms of Service For Advertisers For Media Ophthalmology ...

  11. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... not require the same level of care or consideration as a standard contact lens because they can ... 2016 More Eye Health News Studies Look at Effects of Marijuana on Vision FEB 28, 2017 By ...

  12. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... Contact Lens-Related Eye Infections Mar 01, 2017 New Technology Helps the Legally Blind Be More Independent ... Worse? May 16, 2016 More Eye Health News New Dry Eye Treatment is a Tear-Jerker JUL ...

  13. Colored Contact Lens Dangers

    Science.gov (United States)

    ... Prevention News Ask an Ophthalmologist Patient Stories Español Eye Health / News Halloween Hazard: The Hidden Dangers of Buying Decorative Contact Lenses Without a Prescription Sep. 26, 2013 It started ...

  14. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... Hidden Dangers of Buying Decorative Contact Lenses Without a Prescription Leer en Español: Peligros asociados con los ... contacto de color Sep. 26, 2013 It started as an impulsive buy from a souvenir shop, but ...

  15. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... Healthy Contact Lens Use May 31, 2016 Is El Niño Making Your Allergies Worse? May 16, 2016 ... Number: * Email: * Enter code: * Message: Thank you Your feedback has been sent.

  16. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... Patient Stories Español Eye Health / News Halloween Hazard: The Hidden Dangers of Buying Decorative Contact Lenses Without ... been properly fitted by an eye care professional, the lenses stuck to my eye like a suction ...

  17. Stereo Pair: Patagonia, Argentina

    Science.gov (United States)

    2000-01-01

    This view of northern Patagonia, near El Cain, Argentina shows complexly eroded volcanic terrain, with basalt mesas, sinkholes, landslide debris, playas, and relatively few integrated drainage channels. Surrounding this site (but also extending far to the east) is a broad plateau capped by basalt, the Meseta de Somuncura. Here, near the western edge of the plateau, erosion has broken through the basalt cap in a variety of ways. On the mesas, water-filled sinkholes (lower left) are most likely the result of the collapse of old lava tubes. Along the edges of the mesas (several locations) the basalt seems to be sliding away from the plateau in a series of slices. Water erosion by overland flow is also evident, particularly in canyons where vegetation blankets the drainage channels (green patterns, bottom of image). However, overland water flow does not extend very far at any location. This entire site drains to local playas, some of which are seen here (blue). While the water can reach the playas and then evaporate, what becomes of the eroded rock debris? Wind might excavate some of the finer eroded debris, but the fate of much of the missing bedrock remains mysterious.This cross-eyed stereoscopic image pair was generated using topographic data from the Shuttle Radar Topography Mission, combined with an enhanced Landsat 7 satellite color image. The topography data are used to create two differing perspectives of a single image, one perspective for each eye. In doing so, each point in the image is shifted slightly, depending on its elevation. When stereoscopically merged, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions.Landsat satellites have provided visible light and infrared images of the Earth continuously since 1972. SRTM topographic data match the 30-meter (99-foot) spatial resolution of most Landsat images and provide a valuable complement for studying the historic and growing Landsat data archive. The Landsat 7

  18. Pediatric contact dermatitis

    OpenAIRE

    Sharma Vinod; Asati Dinesh

    2010-01-01

    Allergic contact dermatitis (ACD) in children, until recently, was considered rare. ACD was considered as a disorder of the adult population and children were thought to be spared due to a lack of exposure to potential allergens and an immature immune system. Prevalence of ACD to even the most common allergens in children, like poison ivy and parthenium, is relatively rare as compared to adults. However, there is now growing evidence of contact sensitization of the pediatric population, and i...

  19. Contact air abrasion.

    Science.gov (United States)

    Porth, R

    1999-05-01

    The advantages of contact air abrasion techniques are readily apparent. The first, of course, is the greatly increased ease of use. Working with contact also tends to speed the learning curve by giving the process a more natural dental feel. In addition, as one becomes familiar with working with a dust stream, the potential for misdirecting the air flow is decreased. The future use of air abrasion for deep decay removal will make this the treatment of choice for the next millennium.

  20. Double pendulum contact problem

    Directory of Open Access Journals (Sweden)

    Špička J.

    2014-06-01

    Full Text Available The work concerns contact problems focused on biomechanical systems modelled by a multibody approach. The example is modelling of impact between a body and an infrastructure. The paper firstly presents algorithm for minimum distance calculation. An analytical approach using a tangential plain perpendicular to an initial one is applied. Contact force generated during impact is compared by three different continuous force models, namely the Hertz’s model, the spring-dashpot model and the non-linear damping model. In order to identify contact parameters of these particular models, the method of numerical optimization is used. Purpose of this method is to find the most corresponding results of numerical simulation to the original experiment. Numerical optimization principle is put upon a bouncing ball example for the purpose of evaluation of desirable contact force parameters. The contact modelling is applied to a double pendulum problem. The equation of motion of the double pendulum system is derived using Lagrange equation of the second kind with multipliers, respecting the contact phenomena. Applications in biomechanical research are hinted at arm gravity motion and a double pendulum impact example.

  1. Patients with multiple contact allergies

    DEFF Research Database (Denmark)

    Carlsen, Berit Christina; Andersen, Klaus Ejner; Menné, Torkil;

    2008-01-01

    Patients with multiple contact allergies, also referred to as polysensitized, are more frequent than predicted from prevalence of single sensitivities. The understanding of why some people develop multiple contact allergies, and characterization of patients with multiple contact allergies...... of developing multiple contact allergies. Evidence of allergen clusters among polysensitized individuals is also reviewed. The literature supports the idea that patients with multiple contact allergies constitute a special entity within the field of contact allergy. There is no generally accepted definition...... of patients with multiple contact allergies. We suggest that contact allergy to 3 or more allergens are defined as multiple contact allergies....

  2. Pairing correlations in exotic nuclei

    CERN Document Server

    Sagawa, H

    2012-01-01

    The BCS and HFB theories which can accommodate the pairing correlations in the ground states of atomic nuclei are presented. As an application of the pairing theories, we investigate the spatial extension of weakly bound Ne and C isotopes by taking into account the pairing correlation with the Hartree-Fock-Bogoliubov (HFB) method and a 3-body model, respectively. We show that the odd-even staggering in the reaction cross sections of $^{30,31,32}$Ne and $^{14,15,16}$C are successfully reproduced, and thus the staggering can be attributed to the unique role of pairing correlations in nuclei far from the stability line. A correlation between a one-neutron separation energy and the anti-halo effect is demonstrated for $s$- and p-waves using the HFB wave functions. We also propose effective density-dependent pairing interactions which reproduce both the neutron-neutron ($nn$) scattering length at zero density and the neutron pairing gap in uniform matter. Then, we apply these interactions to study pairing gaps in ...

  3. Pairing Correlations at High Spins

    Science.gov (United States)

    Ma, Hai-Liang; Dong, Bao-Guo; Zhang, Yan; Fan, Ping; Yuan, Da-Qing; Zhu, Shen-Yun; Zhang, Huan-Qiao; Petrache, C. M.; Ragnarsson, I.; Carlsson, B. G.

    The pairing correcting energies at high spins in 161Lu and 138Nd are studied by comparing the results of the cranked-Nilsson-Strutinsky (CNS) and cranked-Nilsson-Strutinsky-Bogoliubov (CNSB) models. It is concluded that the Coriolis effect rather than the rotational alignment effect plays a major role in the reduction of the pairing correlations in the high spin region. Then we proposed an average pairing correction method which not only better reproduces the experimental data comparing with the CNS model but also enables a clean-cut tracing of the configurations thus the full-spin-range discussion on the various rotating bands.

  4. Rough Surface Contact

    Directory of Open Access Journals (Sweden)

    T Nguyen

    2017-06-01

    Full Text Available This paper studies the contact of general rough curved surfaces having nearly identical geometries, assuming the contact at each differential area obeys the model proposed by Greenwood and Williamson. In order to account for the most general gross geometry, principles of differential geometry of surface are applied. This method while requires more rigorous mathematical manipulations, the fact that it preserves the original surface geometries thus makes the modeling procedure much more intuitive. For subsequent use, differential geometry of axis-symmetric surface is considered instead of general surface (although this “general case” can be done as well in Chapter 3.1. The final formulas for contact area, load, and frictional torque are derived in Chapter 3.2.

  5. Acrylate Systemic Contact Dermatitis.

    Science.gov (United States)

    Sauder, Maxwell B; Pratt, Melanie D

    2015-01-01

    Acrylates, the 2012 American Contact Dermatitis Society allergen of the year, are found in a range of products including the absorbent materials within feminine hygiene pads. When fully polymerized, acrylates are nonimmunogenic; however, if not completely cured, the monomers can be potent allergens.A 28-year-old woman is presented, who had her teeth varnished with Isodan (Septodont, Saint-Maur-des-Fossés, France) containing HEMA (2-hydroxyethyl methacrylate) with no initial reaction. Approximately 1 month later, the patient developed a genital dermatitis secondary to her feminine hygiene pads. The initial reaction resolved, but 5 months later, the patient developed a systemic contact dermatitis after receiving a second varnishing.The patient was dramatically patch test positive to many acrylates. This case demonstrates a reaction to likely unpolymerized acrylates within a feminine hygiene pad, as well as broad cross-reactivity or cosensitivity to acrylates, and possibly a systemic contact dermatitis with systemic re-exposure to unpolymerized acrylates.

  6. Shoe allergic contact dermatitis.

    Science.gov (United States)

    Matthys, Erin; Zahir, Amir; Ehrlich, Alison

    2014-01-01

    Foot dermatitis is a widespread condition, affecting men and women of all ages. Because of the location, this condition may present as a debilitating problem to those who have it. Allergic contact dermatitis involving the feet is frequently due to shoes or socks. The allergens that cause shoe dermatitis can be found in any constituent of footwear, including rubber, adhesives, leather, dyes, metals, and medicaments. The goal of treatment is to identify and minimize contact with the offending allergen(s). The lack of product information released from shoe manufacturers and the continually changing trends in footwear present a challenge in treating this condition. The aim of this study is to review the current literature on allergic contact shoe dermatitis; clinical presentation, allergens, patch testing, and management will be discussed. PubMed and MEDLINE databases were used for the search, with a focus on literature updates from the last 15 years.

  7. Exact solution for generalized pairing

    OpenAIRE

    Pan, Feng; J.P. Draayer

    1997-01-01

    An infinite dimensional algebra, which is useful for deriving exact solutions of the generalized pairing problem, is introduced. A formalism for diagonalizing the corresponding Hamiltonian is also proposed. The theory is illustrated with some numerical examples.

  8. Pairing versus quarteting coherence length

    CERN Document Server

    Delion, Doru S

    2015-01-01

    We systematically analyse the coherence length in even-even nuclei. The pairing coherence length in the spin-singlet channel for the effective density dependent delta (DDD) and Gaussian interaction is estimated. We consider in our calculations bound states as well as narrow resonances. It turns out that the pairing gaps given by the DDD interaction are similar to those of the Gaussian potential if one renormalizes the radial width to the nuclear radius. The correlations induced by the pairing interaction have in all considered cases a long range character inside the nucleus and decrease towards the surface. The mean coherence length is larger than the geometrical radius for light nuclei and approaches this value for heavy nuclei. The effect of the temperature and states in continuum is investigated. Strong shell effects are evidenced, especially for protons. We generalize this concept to quartets by considering similar relations, but between proton and neutron pairs. The quartet coherence length has a similar...

  9. Pairing mechanisms for binary stars

    CERN Document Server

    Kouwenhoven, M B N; Goodwin, S P; Zwart, S F Portegies; Kaper, L; 10.1002/asna.200811061

    2008-01-01

    Knowledge of the binary population in stellar groupings provides important information about the outcome of the star forming process in different environments. Binarity is also a key ingredient in stellar population studies and is a prerequisite to calibrate the binary evolution channels. In these proceedings we present an overview of several commonly used methods to pair individual stars into binary systems, which we refer to as the pairing function. Many pairing functions are frequently used by observers and computational astronomers, either for the mathematical convenience, or because they roughly describe the expected outcome of the star forming process. We discuss the consequences of each pairing function for the interpretation of observations and numerical simulations. The binary fraction and mass ratio distribution generally depend strongly on the selection of the range in primary spectral type in a sample. These quantities, when derived from a binary survey with a mass-limited sample of target stars, ...

  10. ALLERGIC CONTACT DERMATITIS

    Directory of Open Access Journals (Sweden)

    Trisna Yuliharti Tersinanda

    2013-07-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE Allergic contact dermatitis is an immunologic reaction that tends to involve the surrounding skin and may even spread beyond affected sites. This skin disease is one of the more frequent, and costly dermatologic problems. Recent data from United Kingdom and United States suggest that the percentage of occupational contact dermatitis due to allergy may be much higher, thus raising the economic impact of occupational allergic contact dermatitis. There is not enough data about the epidemiology of allergic contact dermatitis in Indonesia, however based on research that include beautician in Denpasar, about 27,6 percent had side effect of cosmetics, which is 25,4 percent of it manifested as allergic contact dermatitis. Diagnosis of allergic contact dermatitis is based on anamnesis, physical examination, patch test, and this disease should be distinguished from other eczematous skin disease. The management is prevention of allergen exposure, symptomatic treatment, and physicochemical barrier /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

  11. Allergic contact dermatitis.

    Science.gov (United States)

    Gober, Michael D; Gaspari, Anthony A

    2008-01-01

    Allergic contact dermatitis is a classic example of a cell mediated hypersensitivity reaction in the skin. This occurs as a result of xenobiotic chemicals penetrating into the skin, chemically reacting with self proteins, eventually resulting in a hapten-specific immune response. It is precisely because of this localized immune response that allergic signs and symptoms occur (redness, edema, warmth and pruritus). It has been known for years that conventional T-cells (CD4+ or CD8+ T-cells that express a T-cell receptor alpha/Beta) are critical effectors for this reaction. There is emerging evidence that innate immune lymphocytes such as invariant Natural killer T-cells and even Natural killer cells may play important role. Other T-cell types such as Tregulatory cells and the IL-10 secreting Tregulatory cells type I are likely to be important in the control (resolution) of allergic contact dermatitis. Other cell types that may contribute include B-cells and hapten-specific IgM. Additionally, epidermal Langerhans cells have been ascribed an indispensable role as an antigen presenting cell to educate T-cells of the skin immune system. Studies of mice that lack this cell type suggest that Langerhans cells may be dispensible, and may even play a regulatory role in allergic contact dermatitis. The identity of the antigen presenting cells that complement Langerhans cells has yet to be identified. Lastly, Keratinocytes play a role in all phases of allergic contact dermatitis, from the early initiation phase with the elaboration of inflammatory cytokines, that plays a role in Langerhans cell migration, and T-cell trafficking, through the height of the inflammatory phase with direct interactions with epidermotrophic T-cells, through the resolution phase of allergic contact dermatitis with the production of anti-inflammatory cytokines and tolerogenic antigen presentation to effector T-cells. As the understanding of allergic contact dermatitis continues to improve, this will

  12. Psoriasis and Contact Sensitivitiy

    Directory of Open Access Journals (Sweden)

    Deniz Arlı

    2013-03-01

    Full Text Available Objective: The aim of this study was to investigate the frequency of contact sensitivity in patients with psoriasis, whether there was an association between clinical types and contact sensitivity, whether patch test is a factor that causes Koebner reaction and frequency of contact sensitivity against commonly used topical corticosteroids. Methods: Fifty patients with psoriasis and 50 healthy volunteers were included in this study and ‘European standard series' and test units of active ingredients of some corticosteroids were performed on their upper back. The patches were read on hours 24, 48 and on day 7 in order to detect delayed allergic reactions and also Koebner reaction. The results of both groups were compared by using chi-square test. Results: At the end of the patch test allergic reaction was observed in 7 of 50 (14% patients with psoriasis and 12 of 50 (24% healthy volunteers. There was no statistically significant difference between allergic reaction of study group and healthy volunteers. There was no statistically significant difference between the clinical types of psoriasis and allergic contact sensitivity. The frequency of reaction increased in individuals having a positive sensitivity history to any substance in both patient and control groups. Reaction to topical steroids was not seen in any patients. Koebner phenomenon due to patch test was also not seen in any patients. Conclusion: We did not show any association between psoriasis and contact sensitivity in this study. We believe that contact allergens should be determined by using patch test in psoriatic patients with a positive history to any substance.

  13. Atomic pair-state interferometer

    DEFF Research Database (Denmark)

    Nipper, J.; Balewski, Jonathan B.; Krupp, Alexander T.

    2012-01-01

    to measure the phase shift. Although the coupling between pair states is coherent on the time scale of the experiment, a loss of visibility occurs as a pair-state interferometer involves three simultaneously interfering paths and only one of them is phase shifted by the mutual interaction. Despite additional...... dephasing mechanisms, a pulsed Förster coupling sequence allows for observation of coherent dynamics around the Förster resonance....

  14. Dual pairs in fluid dynamics

    CERN Document Server

    Gay-Balmaz, François

    2010-01-01

    This paper is a rigorous study of the dual pair structure of the ideal fluid and the dual pair structure for the $n$-dimensional Camassa-Holm (EPDiff) equation, including the proofs of the necessary transitivity results. In the case of the ideal fluid, we show that a careful definition of the momentum maps leads naturally to central extensions of diffeomorphism groups such as the group of quantomorphisms and the Ismagilov central extension.

  15. Pair programming: more than just working together in pairs.

    Directory of Open Access Journals (Sweden)

    Elsa Mentz

    2012-03-01

    Full Text Available Pair programming originated in the industry where focus is placed on the development of a programme at the most costand time-effective manner, and within the parameters of quality. In this context, a specific programming code is not developed individually; rather, two people work together in order to ensure a higher quality programming code and to motivate each other to work at a faster pace. The problem with this approach was that novice programmers lacked the social skills to work in pairs as they had not been exposed to this sufficiently at tertiary level. The demand of the industry, especially in terms of programmers needing to be able to programme together, led to the incorporation of pair programming at tertiary level in the late nineties. The pedagogical principles on which any teaching-learning strategy should be built were, however, largely overlooked during this process. This article firstly looks into the semantic and ontological differences between co-operative and collaborative learning and secondly argues that pair programming, within the context of a social constructivist approach to teaching and learning, can be seen as a co-operative teaching-learning strategy. Pair programming is more than just allowing two students to work together on a programming task. The more structured way, in which pair programming needs to be implemented, concur with the principles of co-operative learning. The article concludes that the correct pedagogical application of pair programming as a co-operative teaching-learning strategy in tertiary education will result in improved learning capital.

  16. Critical Points of Contact

    DEFF Research Database (Denmark)

    Jensen, Ole B.; Morelli, Nicola

    2011-01-01

    where the networks meet and establish contact. Thus we argue for the usefulness of the notion of Critical Point of Contact (CPC) to deepen our understanding of the actual life within networks. En route to this notion we draw upon theories within as diverse realms such as interaction design, service...... design, geography, and mobility studies. After the introduction in section we develop and define the notion of CPC based upon a broad set of disciplines and theories. We illustrate the usefulness of the notion within the field of mobility in the network city and within the field of service design...

  17. Counting pairs of faint galaxies

    CERN Document Server

    Woods, D; Richer, H B; Woods, David; Fahlman, Gregory G; Richer, Harvey B

    1995-01-01

    The number of close pairs of galaxies observed to faint magnitude limits, when compared to nearby samples, determines the interaction or merger rate as a function of redshift. The prevalence of mergers at intermediate redshifts is fundamental to understanding how galaxies evolve and the relative population of galaxy types. Mergers have been used to explain the excess of galaxies in faint blue counts above the numbers expected from no-evolution models. Using deep CFHT (I\\leq24) imaging of a ``blank'' field we find a pair fraction which is consistent with the galaxies in our sample being randomly distributed with no significant excess of ``physical'' close pairs. This is contrary to the pair fraction of 34\\%\\pm9\\% found by Burkey {\\it et al.} for similar magnitude limits and using an identical approach to the pair analysis. Various reasons for this discrepancy are discussed. Colors and morphologies of our close pairs are consistent with the bulk of them being random superpositions although, as indicators of int...

  18. Three carbon pairs in Si

    Energy Technology Data Exchange (ETDEWEB)

    Docaj, A. [Physics Department, Texas Tech University, Lubbock, TX 79409-1051 (United States); Estreicher, S.K., E-mail: Stefan.Estreicher@ttu.edu [Physics Department, Texas Tech University, Lubbock, TX 79409-1051 (United States)

    2012-08-01

    Carbon impurities in Si are common in floating-zone and cast-Si materials. The simplest and most discussed carbon complex is the interstitial-substitutional C{sub i}C{sub s} pair, which readily forms when self-interstitials are present in the material. This pair has three possible configurations, each of which is electrically active. The less common C{sub s}C{sub s} pair has been studied in irradiated material but has also recently been seen in as-grown C-rich cast-Si, which is commonly used to fabricate solar cells. The third pair consists of two interstitial C atoms: C{sub i}C{sub i}. Although its formation probability is low for several reasons, the C{sub i}C{sub i} pair is very stable and electrically inactive. In this contribution, we report preliminary results of first-principles calculations of these three C pairs in Si. The structures, binding energies, vibrational spectra, and electrical activity are predicted.

  19. Pressurized bellows flat contact heat exchanger interface

    Science.gov (United States)

    Voss, Fred E. (Inventor); Howell, Harold R. (Inventor); Winkler, Roger V. (Inventor)

    1990-01-01

    Disclosed is an interdigitated plate-type heat exchanger interface. The interface includes a modular interconnect to thermally connect a pair or pairs of plate-type heat exchangers to a second single or multiple plate-type heat exchanger. The modular interconnect comprises a series of parallel, plate-type heat exchangers arranged in pairs to form a slot therebetween. The plate-type heat exchangers of the second heat exchanger insert into the slots of the modular interconnect. Bellows are provided between the pairs of fins of the modular interconnect so that when the bellows are pressurized, they drive the plate-type heat exchangers of the modular interconnect toward one another, thus closing upon the second heat exchanger plates. Each end of the bellows has a part thereof a thin, membrane diaphragm which readily conforms to the contours of the heat exchanger plates of the modular interconnect when the bellows is pressurized. This ensures an even distribution of pressure on the heat exchangers of the modular interconnect thus creating substantially planar contact between the two heat exchangers. The effect of the interface of the present invention is to provide a dry connection between two heat exchangers whereby the rate of heat transfer can be varied by varying the pressure within the bellows.

  20. Close Contact Fluctuations: Time of Contact

    CERN Document Server

    Bush, Daniel R

    2014-01-01

    The letter resolves the long standing debate as to the proper time scale ($$) of the onset of the immunological synapse (IS) bond, the non-covalent chemical bond defining the immune pathways involving T-cells and antigen presenting cells (APC). Results from our model calculations show $$ to be of the order of seconds instead of minutes. Close to the linearly stable regime, we show that in between the two critical spatial thresholds defined by the integrin:ligand pair ($\\Delta_2\\sim$ 40-45 nm) and the T cell receptor (TCR):pMHC bond ($\\Delta_1\\sim$ 14-15 nm), $$ grows monotonically with increasing co-receptor bond length separation $\\delta$ (= $\\Delta_2-\\Delta_1\\sim$ 26-30 nm) while $$ decays with $\\Delta_1$ for fixed $\\Delta_2$. The non-universal $\\delta$-dependent power-law structure of the probability density function (PDF) further explains why only the TCR:pMHC bond is a likely candidate to form a stable synapse.

  1. Opaque Contact Lens For Tracking Motion Of Eye

    Science.gov (United States)

    Zografos, James L., II; Gibson, Charles R.

    1993-01-01

    Opaque contact lens facilitates measurements of movements of eye; particularly, torsional movements. Lens, marked with pair of indices at diameter of 0.5 mm, provides stable, high-contrast reference for measurements of angular position and velocity of eye by use of video-image-analysis techniques. Intended for use in experiments on response of eye to vestibular balance mechanism.

  2. Proxemic communication between HIV-infected mother-child pairs.

    Science.gov (United States)

    Rebouças, Cristiana; Souza Paiva, Simone de; Costa, Enia; Vieira Lima, Ivana Cristina; Freitag Pagliuca, Lorita Marlena; Gimeniz Galvão, Marli Teresinha

    Proxemic communication (behaviours and relations of human interaction) offered by the mother in an HIV-infected mother-child pair during infancy was analysed to determine which proxemic factors promote the exchange of affection. This study, conducted in an experimental laboratory in 2007, included mother-child pairs in which the mother was HIV-positive and the children, under 6 months of age, were born exposed to the virus. Video recordings of the mother-child interaction were analysed according to proxemic factors. Of the 364 interactions recorded for analysis of proxemic communication between the mother-child pair, the most significant proxemic factors were axis, contact behavior, visual code, and tone of voice. The mothers developed communicative strategies such as closer proximity, touch, vocalisation, and smiling to promote the exchange of affection when engaging in maternal care.

  3. Colored Contact Lens Dangers

    Science.gov (United States)

    ... Follow The Academy Professionals: Education Guidelines News Multimedia Public & Patients: Contact Us About the Academy Jobs at the Academy Financial Relationships with Industry Medical Disclaimer Privacy Policy Terms of Service For Advertisers For Media Ophthalmology Job Center © American Academy of ...

  4. Lubrication Of Nonconformal Contacts

    Science.gov (United States)

    Jeng, Yeau-Ren

    1991-01-01

    Report discusses advances in knowledge of lubrication of nonconformal contacts in bearings and other machine elements. Reviews previous developments in theory of lubrication, presents advances in theory of lubrication to determine minimum film thickness, and describes experiments designed to investigate one of regimes of lubrication for ball bearings.

  5. [Contact allergies in musicians].

    Science.gov (United States)

    Gasenzer, E R; Neugebauer, E A M

    2012-12-01

    During the last years, the problem of allergic diseases has increased. Allergies are errant immune responses to a normally harmless substance. In musicians the allergic contact dermatitis to exotic woods is a special problem. Exotic rosewood contains new flavonoids, which trigger an allergic reaction after permanent contact with the instrument. High quality woodwind instruments such as baroque flute or clarinets are made in ebony or palisander because of its great sound. Today instruments for non-professional players are also made in these exotic materials and non-professionals may have the risk to develop contact dermatitis, too. Brass-player has the risk of an allergic reaction to the different metals contained in the metal sheets of modern flutes and brass instruments. Specially nickel and brass alloys are used to product flute tubes or brass instruments. Special problem arises in children: patients who are allergic to plants or foods have a high risk to develop contact dermatitis. Parents don't know the materials of low-priced instruments for beginners. Often unknown cheap woods from exotic areas are used. Low-priced brass instruments contain high amount of brass and other cheap metals. Physicians should advice musician-patients or parents about the risks of the different materials and look for the reason of eczema on mouth, face, or hands.

  6. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... Tips & Prevention News Ask an Ophthalmologist Patient Stories Español Eye Health / News Halloween Hazard: The Hidden Dangers ... Decorative Contact Lenses Without a Prescription Leer en Español: Peligros asociados con los lentes de contacto de ...

  7. Irritant contact dermatitis.

    Science.gov (United States)

    Ale, Iris S; Maibach, Howard I

    2014-01-01

    Irritant contact dermatitis (ICD) is the most common form of contact dermatitis. It represents the cutaneous response to the toxic/physical effects of a wide variety of environmental agents. Nowadays, it is recognized that irritancy does not represent a single monomorphous entity but rather a complex biologic syndrome with diverse pathophysiology and clinical manifestations. The clinical presentation is highly variable depending on several factors, including properties and strength of the irritant, dose, duration and frequency of exposure, environmental factors, and skin susceptibility. The pathophysiological mechanism depends on activation of the innate immune system and involves skin barrier disruption, cellular changes, and release of proinflammatory mediators that directly recruit and activate T lymphocytes. The diagnosis of irritant contact dermatitis is often clinical, and involves a comprehensive history and examination, as well as the exclusion of allergic contact dermatitis with patch testing. Recent advances in understanding the pathogenesis as well as better awareness of the clinical significance of ICD will lead to a improved care for our patients.

  8. Lettuce contact allergy

    DEFF Research Database (Denmark)

    Paulsen, Evy; Andersen, Klaus E

    2016-01-01

    Lettuce (Lactuca sativa L.) and its varieties are important vegetable crops worldwide. They are also well-known, rarely reported, causes of contact allergy. As lettuce allergens and extracts are not commercially available, the allergy may be underdiagnosed. The aims of this article are to present...

  9. [Current contact allergens].

    Science.gov (United States)

    Geier, J; Uter, W; Lessmann, H; Schnuch, A

    2011-10-01

    Ever-changing exposure to contact allergens, partly due to statutory directives (e.g. nickel, chromate, methyldibromo glutaronitrile) or recommendations from industrial associations (e.g. hydroxyisohexyl 3-cyclohexene carboxaldehyde), requires on-going epidemiologic surveillance of contact allergy. In this paper, the current state with special focus in fragrances and preservatives is described on the basis of data of the Information Network of Departments of Dermatology (IVDK) of the year 2010. In 2010, 12,574 patients were patch tested in the dermatology departments belonging to the IVDK. Nickel is still the most frequent contact allergen. However the continuously improved EU nickel directive already has some beneficial effect; sensitization frequency in young women is dropping. In Germany, chromate-reduced cement has been in use now for several years, leading to a decline in chromate sensitization in brick-layers. Two fragrance mixes are part of the German baseline series; they are still relevant. The most important fragrances in these mixes still are oak moss absolute and hydroxyisohexyl 3-cyclohexene carboxaldehyde. However, in relation to these leading allergens, sensitization frequency to other fragrances contained in the mixes seems to be increasing. Among the preservatives, MCI/MI has not lost its importance as contact allergen, in contrast to MDBGN. Sources of MCI/MI sensitization obviously are increasingly found in occupational context. Methylisothiazolinone is a significant allergen in occupational settings, and less frequently in body care products.

  10. Contact: Releasing the news

    Science.gov (United States)

    Pinotti, Roberto

    The problem of mass behavior after man's future contacts with other intelligences in the universe is not only a challenge for social scientists and political leaders all over the world, but also a cultural time bomb as well. In fact, since the impact of CETI (Contact with Extraterrestrial Intelligence) on human civilization, with its different cultures, might cause a serious socio-anthropological shock, a common and predetermined worldwide strategy is necessary in releasing the news after the contact, in order to keep possible manifestations of fear, panic and hysteria under control. An analysis of past studies in this field and of parallel historical situations as analogs suggests a definite "authority crisis" in the public as a direct consequence of an unexpected release of the news, involving a devastating "chain reaction" process (from both the psychological and sociological viewpoints) of anomie and maybe the collapse of today's society. The only way to prevent all this is to prepare the world's public opinion concerning contact before releasing the news, and to develop a long-term strategy through the combined efforts of scientists, political leaders, intelligence agencies and the mass media, in order to create the cultural conditions in which a confrontation with ETI won't affect mankind in a traumatic way. Definite roles and tasks in this multi-level model are suggested.

  11. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... to drive for eight weeks," she said. "I now live with a corneal scar, vision damage and a drooping eyelid." To safely wear costume contact lenses for Halloween or any time of year, follow these guidelines: Get an eye ...

  12. Thermal Contact Conductance

    Science.gov (United States)

    Salerno, Louis J.; Kittel, Peter

    1997-01-01

    The performance of cryogenic instruments is often a function of their operating temperature. Thus, designers of cryogenic instruments often are required to predict the operating temperature of each instrument they design. This requires accurate thermal models of cryogenic components which include the properties of the materials and assembly techniques used. When components are bolted or otherwise pressed together, a knowledge of the thermal performance of such joints are also needed. In some cases, the temperature drop across these joints represents a significant fraction of the total temperature difference between the instrument and its cooler. While extensive databases exist on the thermal properties of bulk materials, similar databases for pressed contacts do not. This has often lead to instrument designs that avoid pressed contacts or to the over-design of such joints at unnecessary expense. Although many people have made measurements of contact conductances at cryogenic temperatures, this data is often very narrow in scope and even more often it has not been published in an easily retrievable fashion, if published at all. This paper presents a summary of the limited pressed contact data available in the literature.

  13. Language Contact and Bilingualism

    NARCIS (Netherlands)

    Appel, René; Muysken, Pieter

    2006-01-01

    What happens - sociologically, linguistically, educationally, politically - when more than one language is in regular use in a community? How do speakers handle these languages simultaneously, and what influence does this language contact have on the languages involved? Although most people in the w

  14. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... person. Get follow up exams with your eye care provider. If you notice redness, swelling, excessive discharge, pain or discomfort from wearing contact lenses, remove the lenses and seek immediate medical attention from an ophthalmologist. Related resources: Learn how ...

  15. Contact allergy to cosmetics

    DEFF Research Database (Denmark)

    Held, E; Johansen, J D; Agner, T

    1999-01-01

    .4%) had doubtfully positive reaction(s) and 31 (5.8%) had irritant reaction(s). Skin-care products were tested most frequently and were also found to cause most positive, doubtfully positive and irritant reactions, 80% of the patients with positive reactions to their own products had no history of contact...

  16. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... EyeSmart videos on your website . Printable posters . Promotional materials for eye health observances. EyeSmart resources are also available in Spanish . Follow The Academy Professionals: Education Guidelines News Multimedia Public & Patients: Contact Us About the Academy Jobs ...

  17. Statistical analysis of Contact Angle Hysteresis

    Science.gov (United States)

    Janardan, Nachiketa; Panchagnula, Mahesh

    2015-11-01

    We present the results of a new statistical approach to determining Contact Angle Hysteresis (CAH) by studying the nature of the triple line. A statistical distribution of local contact angles on a random three-dimensional drop is used as the basis for this approach. Drops with randomly shaped triple lines but of fixed volumes were deposited on a substrate and their triple line shapes were extracted by imaging. Using a solution developed by Prabhala et al. (Langmuir, 2010), the complete three dimensional shape of the sessile drop was generated. A distribution of the local contact angles for several such drops but of the same liquid-substrate pairs is generated. This distribution is a result of several microscopic advancing and receding processes along the triple line. This distribution is used to yield an approximation of the CAH associated with the substrate. This is then compared with measurements of CAH by means of a liquid infusion-withdrawal experiment. Static measurements are shown to be sufficient to measure quasistatic contact angle hysteresis of a substrate. The approach also points towards the relationship between microscopic triple line contortions and CAH.

  18. Divide and Conquer Approach to Contact Map Overlap Problem Using 2D-Pattern Mining of Protein Contact Networks.

    Science.gov (United States)

    Koneru, Suvarna Vani; Bhavani, Durga S

    2015-01-01

    A novel approach to Contact Map Overlap (CMO) problem is proposed using the two dimensional clusters present in the contact maps. Each protein is represented as a set of the non-trivial clusters of contacts extracted from its contact map. The approach involves finding matching regions between the two contact maps using approximate 2D-pattern matching algorithm and dynamic programming technique. These matched pairs of small contact maps are submitted in parallel to a fast heuristic CMO algorithm. The approach facilitates parallelization at this level since all the pairs of contact maps can be submitted to the algorithm in parallel. Then, a merge algorithm is used in order to obtain the overall alignment. As a proof of concept, MSVNS, a heuristic CMO algorithm is used for global as well as local alignment. The divide and conquer approach is evaluated for two benchmark data sets that of Skolnick and Ding et al. It is interesting to note that along with achieving saving of time, better overlap is also obtained for certain protein folds.

  19. Superconductivity: The persistence of pairs

    Energy Technology Data Exchange (ETDEWEB)

    Edelman, Alex; Littlewood, Peter

    2015-05-20

    Superconductivity stems from a weak attraction between electrons that causes them to form bound pairs and behave much like bosons. These so-called Cooper pairs are phase coherent, which leads to the astonishing properties of zero electrical resistance and magnetic flux expulsion typical of superconducting materials. This coherent state may be qualitatively understood within the Bose–Einstein condensate (BEC) model, which predicts that a gas of interacting bosons will become unstable below a critical temperature and condense into a phase of matter with a macroscopic, coherent population in the lowest energy state, as happens in 4He or cold atomic gases. The successful theory proposed by Bardeen, Cooper and Schrieffer (BCS) predicts that at the superconducting transition temperature Tc, electrons simultaneously form pairs and condense, with no sign of pairing above Tc. Theorists have long surmised that the BCS and BEC models are opposite limits of a single theory and that strong interactions or low density can, in principle, drive the system to a paired state at a temperature Tpair higher than Tc, making the transition to the superconducting state BEC-like (Fig. 1). Yet most superconductors to date are reasonably well described by BCS theory or its extensions, and there has been scant evidence in electronic materials for the existence of pairing independent of the full superconducting state (though an active debate rages over the cuprate superconductors). Writing in Nature, Jeremy Levy and colleagues have now used ingenious nanostructured devices to provide evidence for electron pairing1. Perhaps surprisingly, the material they have studied is a venerable, yet enigmatic, low-temperature superconductor, SrTiO3.

  20. Duality based contact shape optimization

    DEFF Research Database (Denmark)

    Vondrák, Vít; Dostal, Zdenek; Rasmussen, John

    2001-01-01

    An implementation of semi-analytic method for the sensitivity analysis in contact shape optimization without friction is described. This method is then applied to the contact shape optimization.......An implementation of semi-analytic method for the sensitivity analysis in contact shape optimization without friction is described. This method is then applied to the contact shape optimization....

  1. Classification of domain movements in proteins using dynamic contact graphs.

    Directory of Open Access Journals (Sweden)

    Daniel Taylor

    Full Text Available A new method for the classification of domain movements in proteins is described and applied to 1822 pairs of structures from the Protein Data Bank that represent a domain movement in two-domain proteins. The method is based on changes in contacts between residues from the two domains in moving from one conformation to the other. We argue that there are five types of elemental contact changes and that these relate to five model domain movements called: "free", "open-closed", "anchored", "sliding-twist", and "see-saw." A directed graph is introduced called the "Dynamic Contact Graph" which represents the contact changes in a domain movement. In many cases a graph, or part of a graph, provides a clear visual metaphor for the movement it represents and is a motif that can be easily recognised. The Dynamic Contact Graphs are often comprised of disconnected subgraphs indicating independent regions which may play different roles in the domain movement. The Dynamic Contact Graph for each domain movement is decomposed into elemental Dynamic Contact Graphs, those that represent elemental contact changes, allowing us to count the number of instances of each type of elemental contact change in the domain movement. This naturally leads to sixteen classes into which the 1822 domain movements are classified.

  2. Evaluation of residue-residue contact prediction in CASP10

    KAUST Repository

    Monastyrskyy, Bohdan

    2013-08-31

    We present the results of the assessment of the intramolecular residue-residue contact predictions from 26 prediction groups participating in the 10th round of the CASP experiment. The most recently developed direct coupling analysis methods did not take part in the experiment likely because they require a very deep sequence alignment not available for any of the 114 CASP10 targets. The performance of contact prediction methods was evaluated with the measures used in previous CASPs (i.e., prediction accuracy and the difference between the distribution of the predicted contacts and that of all pairs of residues in the target protein), as well as new measures, such as the Matthews correlation coefficient, the area under the precision-recall curve and the ranks of the first correctly and incorrectly predicted contact. We also evaluated the ability to detect interdomain contacts and tested whether the difficulty of predicting contacts depends upon the protein length and the depth of the family sequence alignment. The analyses were carried out on the target domains for which structural homologs did not exist or were difficult to identify. The evaluation was performed for all types of contacts (short, medium, and long-range), with emphasis placed on long-range contacts, i.e. those involving residues separated by at least 24 residues along the sequence. The assessment suggests that the best CASP10 contact prediction methods perform at approximately the same level, and comparably to those participating in CASP9.

  3. Electrical contacts principles and applications

    CERN Document Server

    Slade, Paul G

    2013-01-01

    Covering the theory, application, and testing of contact materials, Electrical Contacts: Principles and Applications, Second Edition introduces a thorough discussion on making electric contact and contact interface conduction; presents a general outline of, and measurement techniques for, important corrosion mechanisms; considers the results of contact wear when plug-in connections are made and broken; investigates the effect of thin noble metal plating on electronic connections; and relates crucial considerations for making high- and low-power contact joints. It examines contact use in switch

  4. Allergic contact dermatitis in children.

    Science.gov (United States)

    Fontana, E; Belloni Fortina, A

    2014-12-01

    Allergic contact dermatitis is an inflammatory skin disease (delayed type hypersensitivity reaction) that accounts for up to 20% of all childhood dermatitis. Allergic contact dermatitis represents a clinical manifestation of contact sensitization and usually occurs at skin sites that have come into contact with the allergen. The clinical features of allergic contact dermatitis are itchy eczematous lesions. Prevalence of contact sensitization varies between 27% and 96% of children with suspected contact dermatitis. The relationship between contact sensitization and atopic dermatitis has been widely discussed but only conflicting data have been reported. Epicutaneous patch testing is the gold standard for the diagnosis of allergic contact dermatitis. The most common allergens detected in children are: metals, topical medicaments, fragrances, and preservatives. The first line management of allergic contact dermatitis in children is to avoid the offending allergens identified with the patch test and a topical corticosteroid therapy.

  5. Contact Interactions Probe Effective Dark Matter Models at the LHC

    CERN Document Server

    Dreiner, Herbi; Tattersall, Jamie

    2013-01-01

    Effective field theories provide a simple framework for probing possible dark matter (DM) models by reparametrising full interactions into a reduced number of operators with smaller dimensionality in parameter space. In many cases these models have four particle vertices, e.g. qqXX, leading to the pair production of dark matter particles, X, at a hadron collider from initial state quarks, q. In this analysis we show that for many fundamental DM models with s-channel DM couplings to qq-pairs, these effective vertices must also produce quark contact interactions (CI) of the form qqqq. The respective effective couplings are related by the common underlying theory which allows one to translate the upper limits from one coupling to the other. We show that at the LHC, the experimental limits on quark contact interactions give stronger translated limits on the DM coupling than the experimental searches for dark matter pair production.

  6. [Contact dermatitis from Agave americana].

    Science.gov (United States)

    de la Cueva, Pablo; González-Carrascosa, Mateo; Campos, Minia; Leis, Vicente; Suárez, Ricardo; Lázaro, Pablo

    2005-10-01

    Numerous plant species and their derivatives can cause skin reactions through a variety of mechanisms: irritative contact dermatitis, allergic contact dermatitis, contact urticaria and photodermatitis. We present a case of irritative contact dermatitis after exposure to the sap of Agave americana. The skin symptoms in this case have only been described on rare occasions; although this condition usually presents with a papulovesicular rash, in this patient it appeared as purpuric lesions in the contact area.

  7. Contact of surfaces and contact characteristics of offset surfaces

    Institute of Scientific and Technical Information of China (English)

    Lixin CAO; Hu GONG; Jian LIU

    2008-01-01

    Based on differential geometry, the contact problems of two surfaces are discussed in this paper. The relationship between the contact status of two sur-faces and that of offset surfaces are also analyzed. For a 5-axis NC machining, some research such as optimization of cutter location and calculation of the geometrical cusp height are important. The research results indicate that the relative normal curvature is an important geometrical invariant for describing the contact state of two surfaces. For point contact two surfaces, the calculation equation for the second order remained error is given. For line contact two surfaces, the condition of the second order line contact is that the principal directions and curvatures of the two surfaces are the same along the contact curve. If two surfaces keep the second order line contact, their two offset surfaces will also keep the second order line contact, and their third order remained errors are also uniform with that of the two offset surfaces.

  8. Paired structures in knowledge representation

    DEFF Research Database (Denmark)

    Montero, J.; Bustince, H.; Franco de los Ríos, Camilo;

    2016-01-01

    In this position paper we propose a consistent and unifying view to all those basic knowledge representation models that are based on the existence of two somehow opposite fuzzy concepts. A number of these basic models can be found in fuzzy logic and multi-valued logic literature. Here it is clai......In this position paper we propose a consistent and unifying view to all those basic knowledge representation models that are based on the existence of two somehow opposite fuzzy concepts. A number of these basic models can be found in fuzzy logic and multi-valued logic literature. Here...... of paired structures, generated from two paired concepts together with their associated neutrality, all of them to be modeled as fuzzy sets. In this way, paired structures can be viewed as a standard basic model from which different models arise. This unifying view should therefore allow a deeper analysis...

  9. Organometallic frustrated Lewis pair chemistry.

    Science.gov (United States)

    Erker, Gerhard

    2011-08-07

    Frustrated Lewis pairs are playing an increasingly important role in organometallic chemistry. Examples are presented and discussed where organometallic systems themselves serve as the Lewis base or Lewis acid components in frustrated Lewis pair chemistry, mostly through their attached functional groups. Activation of dihydrogen takes place easily in many of these systems. This may lead to the generation of novel catalyst systems but also in many cases to the occurrence of specific reactions at the periphery of the organometallic frameworks. Increasingly, FLP reactions are used to carry out functional group conversions in organometallic systems under mild reaction conditions. The limits of typical FLP reactivity are explored with selected organometallic examples, a discussion that points toward new developments, such as the discovery of facile new 1,1-carboboration reactions. Learning more and more about the broad spectrum of frustrated Lewis pair chemistry helps us to find novel reactions and applications.

  10. /Au Back Contacts

    Science.gov (United States)

    Paudel, Naba R.; Compaan, Alvin D.; Yan, Yanfa

    2014-08-01

    We report on the fabrication and characterization of CdTe thin-film solar cells with Cu-free MoO3- x /Au back contacts. CdTe solar cells with sputtered CdTe absorbers of thicknesses from 0.5 to 1.75 μm were fabricated on Pilkington SnO2:F/SnO2-coated soda-lime glasses coated with a 60- to 80-nm sputtered CdS layer. The MoO3- x /Au back contact layers were deposited by thermal evaporation. The incorporation of MoO3- x layer was found to improve the open circuit voltage ( V OC) but reduce the fill factor of the ultrathin CdTe cells. The V OC was found to increase as the CdTe thickness increased.

  11. Exlusive charmed meson pair production

    CERN Document Server

    Berezhnoy, A V

    2004-01-01

    The experimental data of BELLE Collaboration on the exclusive charmed meson pair production in the process of monophotonic $e^+e^-$-annihilation ($e^+e^-\\to \\gamma^* \\to D\\bar D$) has been studied. It has been shown that these data is described satisfactorily in the frame work of constituent quark model. Our studies have demonstrated that the central production process $e^+e^-\\to e^+e^-\\gamma\\gamma \\to e^+e^-D\\bar D +X$ and the process of monophotonic $e^+e^-$-annihilation yield comparable numbers of the charmed meson pairs.

  12. Instantons in lepton pair production

    Energy Technology Data Exchange (ETDEWEB)

    Brandenburg, A.; Ringwald, A. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Utermann, A. [Vrije Univ., Amsterdam (Netherlands). Dept. of Physics and Astronomy

    2006-05-15

    We consider QCD instanton-induced contributions to lepton pair production in hadron-hadron collisions. We relate these contributions to those known from deep inelastic scattering and demonstrate that they can be calculated reliably for sufficiently large momentum transfer. We observe that the instanton contribution to the angular distribution of the lepton pairs at finite momentum transfer strongly violates the Lam-Tung relation - a relation between coefficient functions of the angular distribution which is valid within the framework of ordinary perturbation theory. The drastic violation of this relation, as seen in experimental data, might be related to such instanton-induced effects. (Orig.)

  13. Contact stress sensor

    Science.gov (United States)

    Kotovsky, Jack [Oakland, CA

    2012-02-07

    A contact stress sensor includes one or more MEMS fabricated sensor elements, where each sensor element of includes a thin non-recessed portion, a recessed portion and a pressure sensitive element adjacent to the recessed portion. An electric circuit is connected to the pressure sensitive element. The circuit includes a thermal compensator and a pressure signal circuit element configured to provide a signal upon movement of the pressure sensitive element.

  14. Occupational protein contact dermatitis.

    Science.gov (United States)

    Barbaud, Annick; Poreaux, Claire; Penven, Emmanuelle; Waton, Julie

    2015-01-01

    Occupational contact dermatitis is generally caused by haptens but can also be induced by proteins causing mainly immunological contact urticaria (ICU); chronic hand eczema in the context of protein contact dermatitis (PCD). In a monocentric retrospective study, from our database, only 31 (0.41%) of patients with contact dermatitis had positive skin tests with proteins: 22 had occupational PCD, 3 had non-occupational PCD, 5 occupational ICU and 1 cook had a neutrophilic fixed food eruption (NFFE) due to fish. From these results and analysis of literature, the characteristics of PCD can be summarized as follows. It is a chronic eczematous dermatitis, possibly exacerbated by work, suggestive if associated with inflammatory perionyxix and immediate erythema with pruritis, to be investigated when the patient resumes work after a period of interruption. Prick tests with the suspected protein-containing material are essential, as patch tests have negative results. In case of multisensitisation revealed by prick tests, it is advisable to analyse IgE against recombinant allergens. A history of atopy, found in 56 to 68% of the patients, has to be checked for. Most of the cases are observed among food-handlers but PCD can also be due to non-edible plants, latex, hydrolysed proteins or animal proteins. Occupational exposure to proteins can thus lead to the development of ICU. Reflecting hypersensitivity to very low concentrations of allergens, investigating ICU therefore requires caution and prick tests should be performed with a diluted form of the causative protein-containing product. Causes are food, especially fruit peel, non-edible plants, cosmetic products, latex, animals.

  15. Contact stress sensor

    Science.gov (United States)

    Kotovsky, Jack

    2014-02-11

    A method for producing a contact stress sensor that includes one or more MEMS fabricated sensor elements, where each sensor element of includes a thin non-recessed portion, a recessed portion and a pressure sensitive element adjacent to the recessed portion. An electric circuit is connected to the pressure sensitive element. The circuit includes a pressure signal circuit element configured to provide a signal upon movement of the pressure sensitive element.

  16. Pediatric contact dermatitis.

    Science.gov (United States)

    Sharma, Vinod K; Asati, Dinesh P

    2010-01-01

    Allergic contact dermatitis (ACD) in children, until recently, was considered rare. ACD was considered as a disorder of the adult population and children were thought to be spared due to a lack of exposure to potential allergens and an immature immune system. Prevalence of ACD to even the most common allergens in children, like poison ivy and parthenium, is relatively rare as compared to adults. However, there is now growing evidence of contact sensitization of the pediatric population, and it begins right from early childhood, including 1-week-old neonates. Vaccinations, piercing, topical medicaments and cosmetics in younger patients are potential exposures for sensitization. Nickel is the most common sensitizer in almost all studies pertaining to pediatric contact dermatitis. Other common allergens reported are cobalt, fragrance mix, rubber, lanolin, thiomersol, neomycin, gold, mercapto mix, balsum of Peru and colophony. Different factors like age, sex, atopy, social and cultural practices, habit of parents and caregivers and geographic changes affect the patterns of ACD and their variable clinical presentation. Patch testing should be considered not only in children with lesions of a morphology suggestive of ACD, but in any child with dermatitis that is difficult to control.

  17. Pediatric contact dermatitis

    Directory of Open Access Journals (Sweden)

    Sharma Vinod

    2010-01-01

    Full Text Available Allergic contact dermatitis (ACD in children, until recently, was considered rare. ACD was considered as a disorder of the adult population and children were thought to be spared due to a lack of exposure to potential allergens and an immature immune system. Prevalence of ACD to even the most common allergens in children, like poison ivy and parthenium, is relatively rare as compared to adults. However, there is now growing evidence of contact sensitization of the pediatric population, and it begins right from early childhood, including 1-week-old neonates. Vaccinations, piercing, topical medicaments and cosmetics in younger patients are potential exposures for sensitization. Nickel is the most common sensitizer in almost all studies pertaining to pediatric contact dermatitis. Other common allergens reported are cobalt, fragrance mix, rubber, lanolin, thiomersol, neomycin, gold, mercapto mix, balsum of Peru and colophony. Different factors like age, sex, atopy, social and cultural practices, habit of parents and caregivers and geographic changes affect the patterns of ACD and their variable clinical presentation. Patch testing should be considered not only in children with lesions of a morphology suggestive of ACD, but in any child with dermatitis that is difficult to control.

  18. Mechanical Contact Experiments and Simulations

    DEFF Research Database (Denmark)

    Nielsen, Chris Valentin; Martins, P; Zhang, W.

    2011-01-01

    geometries and different materials are analyzed including contact between dissimilar materials. The numerical implementation is performed with a finite element computer program based on the irreducible flow formulation, and contact between deformable objects is modelled by applying the penalty method....... The overall investigation serves for testing and validating the numerical implementation of the mechanical contact, which is one of the main contributions to a system intended for 3D simulation of resistance welding. Correct modelling of contact between parts to be welded, as well as contact with electrodes......, is crucial for satisfactory modelling of the resistance welding process. The resistance heating at the contact interfaces depends on both contact area and pressure, and as the contact areas develop dynamically, the presented tests are relevant for assessing the validity and accuracy of the mechanical contact...

  19. Electron pair creation by photons

    NARCIS (Netherlands)

    Holtwijk, Theodoor

    1960-01-01

    In our experiment on the creation of electron pairs a 5 MeV betatron was used as radiation source and a cloud chamber (with magnetic field) was used as detection instrument. The experimental arrangement is described in section 2.1. The cloud chamber was of the overcompression type so that the recove

  20. Pairs of dual periodic frames

    DEFF Research Database (Denmark)

    Christensen, Ole; Goh, Say Song

    2012-01-01

    is needed. The purpose of the present paper is to provide constructions of dual pairs of frames in the setting of the Hilbert space of periodic functions L2(0,2π). The frames constructed are given explicitly as trigonometric polynomials, which allows for an efficient calculation of the coefficients...

  1. Electron pair creation by photons

    NARCIS (Netherlands)

    Holtwijk, Theodoor

    1960-01-01

    In our experiment on the creation of electron pairs a 5 MeV betatron was used as radiation source and a cloud chamber (with magnetic field) was used as detection instrument. The experimental arrangement is described in section 2.1. The cloud chamber was of the overcompression type so that the recove

  2. Sharp contact corners, fretting and cracks

    Directory of Open Access Journals (Sweden)

    D. A. Hills

    2013-07-01

    Full Text Available Contacts with sharp edges subject to oscillatory loading are likely to nucleate cracks from the corners, if the loading is sufficiently severe. To a first approximation, the corners behave like notches, where the local elastic behaviour is relieved by plasticity, and which in turn causes irreversibilities that give rise to crack nucleation, but also by frictional slip. One question we aim to answer here is; when is the frictional slip enveloped by plastic slip, so that the corner is effectively a notch in a monolithic material? We do this by employing the classical Williams asymptotic solution to model the contact corner, and, in doing so, we render the solution completely general in the sense that it is independent of the overall geometry of the components. We then re-define the independent parameters describing the properties of the Williams solution by using the inherent length scale, a procedure that was described at the first IJFatigue and FFEMS joint workshop [1]. By proceeding in this way, we can provide a self-contained solution that can be ‘pasted in’ to any complete contact problem, and hence the likelihood of crack nucleation, and the circumstances under which it might occur, can be classified. Further, this reformulation of Williams' solution provides a clear means of obtaining the strength (defined by crack nucleation conditions of a material pair with a particular contact angle. This means that the results from a test carried out using a laboratory specimen may easily be carried over to any complicated contact problem found in engineering practice, and a mechanical test of the prototypical geometry, which may often be quite difficult, is avoided.

  3. Tri-residue contact potential: a new knowledge-based energetic method

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A new knowledge-based potential method, the tri-residue contact potential (TRICP), is proposed. This approach resembles the idea of environment-dependent residue contact energy reported by Zhang et al. We statistically study the 3-dimensional structure of proteins and calculate the knowledge-based contact potential of tri-residue clusters. These contact potentials are carefully compared to pairwise contact potentials (PCP). TRICP helps us to systematically examine the impact on the interactions of residue pairs by the third residue. Moreover, TRICP provides us with many clues to identify high frequency characteristic structural units in protein structures.

  4. Sequence of oral bacterial co-adhesion and non-contact brushing

    NARCIS (Netherlands)

    van der Mei, H. C.; Rustema-Abbing, M.; Bruinsma, G. M.; Gottenbos, B.; Busscher, H. J.

    Non-contact plaque removal offers advantages in interproximal spaces, fissures, and pockets. It requires the generation of strong fluid flows and the inclusion of air bubbles to become effective. A pair of co-adhering streptococci and actinomyces has been used previously to demonstrate non-contact

  5. Contextualizing Intergroup Contact: Do Political Party Cues Enhance Contact Effects?

    DEFF Research Database (Denmark)

    Sønderskov, Kim Mannemar; Thomsen, Jens Peter Frølund

    2015-01-01

    political parties on us-them categorizations heightens the awareness of group memberships. This focus in turn enhances the positive intergroup contact effect by stimulating majority members to perceive contacted persons as prototypical outgroup members. A multilevel analysis of 22 countries and almost 37......,000 individuals confirms that the ability of intergroup contact to reduce antiforeigner sentiment increases when political parties focus intensively on immigration issues and cultural differences. Specifically, both workplace contact and interethnic friendship become more effective in reducing antiforeigner...

  6. Quantum Contact Transmission

    Institute of Scientific and Technical Information of China (English)

    崔迪

    2015-01-01

    Abstract:Quantum transmission is based on quantum entanglement, which is a kind of the phenomenon of quantum mechanics. Quantum object refers to two or more between the localized, the classic strong correlation. When two object quantum entanglement in the quantum state is not independent, but related, and the correlation distance, a pair of electronic of entanglement state, no matter how far apart, they spin direction will remain an up and a down. If one of the electronic spin direction is changed, another of the electron spin direction wil follow to change immediately.

  7. Contact dermatitis in Nigeria.

    Science.gov (United States)

    Olumide, Y M

    1985-05-01

    Nickel is the most important sensitizer in Lagos, with an incidence of 12.3% of 453 patients tested. There was no sex difference, as the wearing of necklaces and bracelets was equally fashionable among both sexes. Housewife eczema is not common, probably because of hardening. Dermatitis from additives in the processing of leather and rubber footwear was the next most common. Chromate sensitivity comes usually from leather or cement. Cultural and climatic factors are mainly responsible for differences in the incidence of contact dermatitis found in Lagos from other countries.

  8. Contact Control, Version 1

    Energy Technology Data Exchange (ETDEWEB)

    2016-07-21

    The contact control code is a generalized force control scheme meant to interface with a robotic arm being controlled using the Robot Operating System (ROS). The code allows the user to specify a control scheme for each control dimension in a way that many different control task controllers could be built from the same generalized controller. The input to the code includes maximum velocity, maximum force, maximum displacement, and a control law assigned to each direction and the output is a 6 degree of freedom velocity command that is sent to the robot controller.

  9. Thermal contact conductance

    CERN Document Server

    Madhusudana, Chakravarti V

    2013-01-01

    The work covers both theoretical and practical aspects of thermal contact conductance. The theoretical discussion focuses on heat transfer through spots, joints, and surfaces, as well as the role of interstitial materials (both planned and inadvertent). The practical discussion includes formulae and data that can be used in designing heat-transfer equipment for a variety of joints, including special geometries and configurations. All of the material has been updated to reflect the latest advances in the field.

  10. Contact dermatitis to methylisothiazolinone*

    Science.gov (United States)

    Scherrer, Maria Antonieta Rios; Rocha, Vanessa Barreto; Andrade, Ana Regina Coelho

    2015-01-01

    Methylisothiazolinone (MI) is a preservative found in cosmetic and industrial products. Contact dermatitis caused by either methylchloroisothiazolinone/methylisothiazolinone (MCI/MI or Kathon CG) or MI has shown increasing frequency. The latter is preferably detected through epicutaneous testing with aqueous MI 2000 ppm, which is not included in the Brazilian standard tray. We describe a series of 23 patients tested using it and our standard tray. A case with negative reaction to MCI/MI and positive to MI is emphasized. PMID:26734880

  11. Adhesion in hydrogel contacts

    Science.gov (United States)

    Torres, J. R.; Jay, G. D.; Kim, K.-S.; Bothun, G. D.

    2016-05-01

    A generalized thermomechanical model for adhesion was developed to elucidate the mechanisms of dissipation within the viscoelastic bulk of a hyperelastic hydrogel. Results show that in addition to the expected energy release rate of interface formation, as well as the viscous flow dissipation, the bulk composition exhibits dissipation due to phase inhomogeneity morphological changes. The mixing thermodynamics of the matrix and solvent determines the dynamics of the phase inhomogeneities, which can enhance or disrupt adhesion. The model also accounts for the time-dependent behaviour. A parameter is proposed to discern the dominant dissipation mechanism in hydrogel contact detachment.

  12. Allergic contact dermatitis from octylisothiazolinone

    DEFF Research Database (Denmark)

    Mose, Anja Pahlow; Frost, Simon; Ohlund, Ulf;

    2013-01-01

    Octylisothiazolinone is a biocide that has been reported as a moderate, but rare contact allergen.......Octylisothiazolinone is a biocide that has been reported as a moderate, but rare contact allergen....

  13. Contact Center Manager Administration (CCMA)

    Data.gov (United States)

    Social Security Administration — CCMA is the server that provides a browser-based tool for contact center administrators and supervisors. It is used to manage and configure contact center resources...

  14. Optimal contact definition for reconstruction of Contact Maps

    Directory of Open Access Journals (Sweden)

    Stehr Henning

    2010-05-01

    Full Text Available Abstract Background Contact maps have been extensively used as a simplified representation of protein structures. They capture most important features of a protein's fold, being preferred by a number of researchers for the description and study of protein structures. Inspired by the model's simplicity many groups have dedicated a considerable amount of effort towards contact prediction as a proxy for protein structure prediction. However a contact map's biological interest is subject to the availability of reliable methods for the 3-dimensional reconstruction of the structure. Results We use an implementation of the well-known distance geometry protocol to build realistic protein 3-dimensional models from contact maps, performing an extensive exploration of many of the parameters involved in the reconstruction process. We try to address the questions: a to what accuracy does a contact map represent its corresponding 3D structure, b what is the best contact map representation with regard to reconstructability and c what is the effect of partial or inaccurate contact information on the 3D structure recovery. Our results suggest that contact maps derived from the application of a distance cutoff of 9 to 11Å around the Cβ atoms constitute the most accurate representation of the 3D structure. The reconstruction process does not provide a single solution to the problem but rather an ensemble of conformations that are within 2Å RMSD of the crystal structure and with lower values for the pairwise average ensemble RMSD. Interestingly it is still possible to recover a structure with partial contact information, although wrong contacts can lead to dramatic loss in reconstruction fidelity. Conclusions Thus contact maps represent a valid approximation to the structures with an accuracy comparable to that of experimental methods. The optimal contact definitions constitute key guidelines for methods based on contact maps such as structure prediction through

  15. Computing an upper bound on contact stress with surrogate duality

    Science.gov (United States)

    Xuan, Zhaocheng; Papadopoulos, Panayiotis

    2016-07-01

    We present a method for computing an upper bound on the contact stress of elastic bodies. The continuum model of elastic bodies with contact is first modeled as a constrained optimization problem by using finite elements. An explicit formulation of the total contact force, a fraction function with the numerator as a linear function and the denominator as a quadratic convex function, is derived with only the normalized nodal contact forces as the constrained variables in a standard simplex. Then two bounds are obtained for the sum of the nodal contact forces. The first is an explicit formulation of matrices of the finite element model, derived by maximizing the fraction function under the constraint that the sum of the normalized nodal contact forces is one. The second bound is solved by first maximizing the fraction function subject to the standard simplex and then using Dinkelbach's algorithm for fractional programming to find the maximum—since the fraction function is pseudo concave in a neighborhood of the solution. These two bounds are solved with the problem dimensions being only the number of contact nodes or node pairs, which are much smaller than the dimension for the original problem, namely, the number of degrees of freedom. Next, a scheme for constructing an upper bound on the contact stress is proposed that uses the bounds on the sum of the nodal contact forces obtained on a fine finite element mesh and the nodal contact forces obtained on a coarse finite element mesh, which are problems that can be solved at a lower computational cost. Finally, the proposed method is verified through some examples concerning both frictionless and frictional contact to demonstrate the method's feasibility, efficiency, and robustness.

  16. Testing and Modeling of Contact Problems in Resistance Welding

    DEFF Research Database (Denmark)

    Song, Quanfeng

    As a part of the efforts towards a professional and reliable numerical tool for resistance welding engineers, this Ph.D. project is dedicated to refining the numerical models related to the interface behavior. An FE algorithm for the contact problems in resistance welding has been developed...... together two or three cylindrical parts as well as disc-ring pairs of dissimilar metals. The tests have demonstrated the effectiveness of the model. A theoretical and experimental study is performed on the contact resistance aiming at a more reliable model for numerical simulation of resistance welding....... The model currently employed is evaluated. It is found that the model may underestimate the constriction resistance because it is based on the assumption of continual contact area. A new model is proposed on the constriction resistance in resistance welding. A parametric study is performed on the contact...

  17. Constraints on Contact Angles for Multiple Phases in Thermodynamic Equilibrium.

    Science.gov (United States)

    Blunt, Martin J.

    2001-07-01

    For three or more fluid phases in thermodynamic equilibrium and in contact with a solid surface, the Young equation can be used to find relations between the contact angles for different pairs of fluids. For an n-fluid-phase system, n(n-1)/2 contact angles can be defined, but there are (n-1)(n-2)/2 constraints between them, leaving only n-1 independent values of the contact angle. These constraints are very powerful in limiting and determining possible types of wetting behavior. The consequences are discussed for three- and four-phase flow. They have important applications for the understanding of gas injection processes in petroleum reservoirs. Copyright 2001 Academic Press.

  18. Thermal conductance of pressed contacts at liquid helium temperatures

    Science.gov (United States)

    Salerno, L. J.; Kittel, P.; Spivak, A. L.

    1983-01-01

    It is pointed out that the optimum design of cryogenic instruments requires accurate thermal models. The present models are limited by a lack of knowledge of the low temperature thermal conductance of the bolted joints which are typically used in the instrument-to-system interface. In connection with studies of pressed contacts, it has been found that the thermal conductance does not obey the Wiedemann-Franz law. The present investigation is concerned with the characterization of the thermal conductance of pressed contacts at liquid helium-4 temperatures, taking into account the dependence of thermal contact conductance on applied force and temperature. It is shown that for the 0.4 micron OFHC copper pressed contact pair, the thermal conductance varies roughly as the second power of the temperature, and increases with increasing applied force.

  19. Slip in viscous contact-line movement

    Science.gov (United States)

    van Lengerich, Henrik; Steen, Paul; Breuer, Kenneth

    2011-11-01

    The typical continuum fluid dynamics formulation cannot be used to model the spreading of a liquid on a solid because a stress singularity prevents contact-line motion. It is well known that this situation can be remedied by introducing a slip. We perform Stokes-flow simulations with slip and compare these with experiments. In the experiment, liquid (squalane) is forced through two parallel sapphire plates (roughness 0.6nm), and the meniscus shape and its speed are measured. The slip-length for this liquid/solid pair has been measured previously in an independent experiment absent of contact lines (T. Schmatko et. al. PRL 94, 244501). The same geometry is used in a boundary integral method simulation, accurate to within a few molecular diameters in the vicinity of the contact-line. The slip-length in the simulations can be varied such that the meniscus shape matches the experiment. Preliminary results suggest this slip-length is an order of magnitude lower than that reported by Schmatko. Now at the University of Minnesota TC

  20. RATE OF INTRAMOLECULAR CONTACT FORMATION IN PROTEINS

    Institute of Scientific and Technical Information of China (English)

    Lin-xi Zhang; Ting-ting Sun; Xiang-hong Wang

    2007-01-01

    In this paper,we estimate the rate of contact formation between two residues in the interior of the proteins using the Szabo,Schulten,and Schulten formula with the probability distribution P(r)based on 375 proteins from PDB(Protein Data Bank).The probability distribution for residue pair in proteins is different from the Gaussian distribution,especially for short distance between two residues in proteins.The rate of contact formation in the interior of protein is discussed as a function of distance n(=|j-i|)between two residues,and it decreases monotonically with n and follows the scaling relationship of k∝"n-γ with γ=1.43 for the contact radius a=0.40 nm and γ=1.05 for a=0.50 nm.The diffusion coefficient for the relative diffusion of two residues in the interior of proteins is estimated as D=6.4×1 0.-6 cm2/s,which is close to the result that is found for monomer diffusion.

  1. Skew Pairs of Idempotents in Transformation Semigroups

    Institute of Scientific and Technical Information of China (English)

    T. S. BLYTH; M. H. ALMEIDA SANTOS

    2006-01-01

    An ordered pair (e, f) of idempotents of a regular semigroup is called a skew pair if ef is not idempotent whereas fe is idempotent. We have shown previously that there are four distinct types of skew pairs of idempotents. Here we investigate the ubiquity of such skew pairs in full transformation semigroups.

  2. Systemic contact dermatitis

    Directory of Open Access Journals (Sweden)

    Daria Nowak

    2016-02-01

    Full Text Available Systemic contact dermatitis (SCD is a skin inflammation occurring in a patient after systemic administration of a hapten, which previously caused an allergic contact skin reaction in the same person. Most frequently, hypersensitivity reactions typical for SCD occur after absorption of haptens with food or inhalation. Haptens occur mainly in the forms of metals and compounds present in natural resins, preservatives, food thickeners, flavorings and medicines. For many years, several studies have been conducted on understanding the pathogenesis of SCD in which both delayed type hypersensitivity (type IV and immediate type I are observed. Components of the complement system are also suspected to attend there. Helper T cells (Th (Th1 and Th2, cytotoxic T lymphocytes (Tc, and NK cells play a crucial role in the pathogenesis of SCD. They secrete a number of pro-inflammatory cytokines. In addition, regulatory T cells (Tregs have an important role. They control and inhibit activity of the immune system during inflammation. Tregs release suppressor cytokines and interact directly with a target cell through presentation of immunosuppressive particles at the cell surface. Diagnostic methods are generally the patch test, oral provocation test, elimination diet and lymphocyte stimulation test. There are many kinds of inflammatory skin reactions caused by systemic haptens’ distribution. They are manifested in a variety of clinical phenotypes of the disease.

  3. [Systemic contact dermatitis].

    Science.gov (United States)

    Nowak, Daria; Gomułka, Krzysztof; Dziemieszonek, Paulina; Panaszek, Bernard

    2016-02-25

    Systemic contact dermatitis (SCD) is a skin inflammation occurring in a patient after systemic administration of a hapten, which previously caused an allergic contact skin reaction in the same person. Most frequently, hypersensitivity reactions typical for SCD occur after absorption of haptens with food or inhalation. Haptens occur mainly in the forms of metals and compounds present in natural resins, preservatives, food thickeners, flavorings and medicines. For many years, several studies have been conducted on understanding the pathogenesis of SCD in which both delayed type hypersensitivity (type IV) and immediate type I are observed. Components of the complement system are also suspected to attend there. Helper T cells (Th) (Th1 and Th2), cytotoxic T lymphocytes (Tc), and NK cells play a crucial role in the pathogenesis of SCD. They secrete a number of pro-inflammatory cytokines. In addition, regulatory T cells (Tregs) have an important role. They control and inhibit activity of the immune system during inflammation. Tregs release suppressor cytokines and interact directly with a target cell through presentation of immunosuppressive particles at the cell surface. Diagnostic methods are generally the patch test, oral provocation test, elimination diet and lymphocyte stimulation test. There are many kinds of inflammatory skin reactions caused by systemic haptens' distribution. They are manifested in a variety of clinical phenotypes of the disease.

  4. Systemic contact dermatitis

    Directory of Open Access Journals (Sweden)

    Daria Nowak

    2016-02-01

    Full Text Available Systemic contact dermatitis (SCD is a skin inflammation occurring in a patient after systemic administration of a hapten, which previously caused an allergic contact skin reaction in the same person. Most frequently, hypersensitivity reactions typical for SCD occur after absorption of haptens with food or inhalation. Haptens occur mainly in the forms of metals and compounds present in natural resins, preservatives, food thickeners, flavorings and medicines. For many years, several studies have been conducted on understanding the pathogenesis of SCD in which both delayed type hypersensitivity (type IV and immediate type I are observed. Components of the complement system are also suspected to attend there. Helper T cells (Th (Th1 and Th2, cytotoxic T lymphocytes (Tc, and NK cells play a crucial role in the pathogenesis of SCD. They secrete a number of pro-inflammatory cytokines. In addition, regulatory T cells (Tregs have an important role. They control and inhibit activity of the immune system during inflammation. Tregs release suppressor cytokines and interact directly with a target cell through presentation of immunosuppressive particles at the cell surface. Diagnostic methods are generally the patch test, oral provocation test, elimination diet and lymphocyte stimulation test. There are many kinds of inflammatory skin reactions caused by systemic haptens’ distribution. They are manifested in a variety of clinical phenotypes of the disease.

  5. Dynamic contact angle analysis of silicone hydrogel contact lenses.

    Science.gov (United States)

    Read, Michael Leonard; Morgan, Philip Bruce; Kelly, Jeremiah Michael; Maldonado-Codina, Carole

    2011-07-01

    Contact angle measurements are used to infer the clinical wetting characteristics of contact lenses. Such characterization has become more commonplace since the introduction of silicone hydrogel contact lens materials, which have been associated with reduced in vivo wetting due to the inclusion of siloxane-containing components. Using consistent methodology and a single investigator, advancing and receding contact angles were measured for 11 commercially available silicone hydrogel contact lens types with a dynamic captive bubble technique employing customized, fully automated image analysis. Advancing contact angles were found to range between 20° and 72° with the lenses falling into six statistically discrete groupings. Receding contact angles fell within a narrower range, between 17° and 22°, with the lenses segregated into three groups. The relationship between these laboratory measurements and the clinical performance of the lenses requires further investigation.

  6. Pairing theory of striped superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Loder, Florian; Kampf, Arno P.; Kopp, Thilo; Graser, Siegfried [Center for Electronic Correlations and Magnetism, Institute of Physics, Augsburg (Germany)

    2011-07-01

    Striped high-T{sub c} superconductors such as La{sub 7/8}Ba{sub 1/8}CuO{sub 4} show a fascinating competition between spin and charge order on the one hand and superconductivity on the other. A theory for these systems therefore has to capture both the spin correlations in an antiferromagnet and the pair-correlation of a superconductor. For this purpose we have developed an effective Hartree-Fock theory by merging electron pairing with finite center-of-mass momentum and antiferromagnetism. We show that this theory reproduces the key experimental features such as the formation of the antiferromagnetic stripe patterns at 7/8 band filling or the quasi one-dimensional electronic structure observed by photoemission spectroscopy.

  7. Collisions of Vortex Filament Pairs

    Science.gov (United States)

    Banica, Valeria; Faou, Erwan; Miot, Evelyne

    2014-12-01

    We consider the problem of collisions of vortex filaments for a model introduced by Klein et al. (J Fluid Mech 288:201-248, 1995) and Zakharov (Sov Phys Usp 31(7):672-674, 1988, Lect. Notes Phys 536:369-385, 1999) to describe the interaction of almost parallel vortex filaments in three-dimensional fluids. Since the results of Crow (AIAA J 8:2172-2179, 1970) examples of collisions are searched as perturbations of antiparallel translating pairs of filaments, with initial perturbations related to the unstable mode of the linearized problem; most results are numerical calculations. In this article, we first consider a related model for the evolution of pairs of filaments, and we display another type of initial perturbation leading to collision in finite time. Moreover, we give numerical evidence that it also leads to collision through the initial model. We finally study the self-similar solutions of the model.

  8. Septin pairs, a complex choreography.

    Science.gov (United States)

    Ewers, Helge

    2011-06-13

    Septins form a filamentous collar at the mother-bud neck in budding yeast. In cytokinesis, this collar splits into two rings and the septin complexes undergo a dramatic reorientation. Using fluorescence polarization microscopy, DeMay et al. (2011. J. Cell Biol. doi:10.1083/jcb.201012143) now demonstrate that septin complexes assemble as paired filaments in vivo and reveal new insights into septin organization during cytokinesis.

  9. Triplet Pairing in Neutron Matter

    CERN Document Server

    Khodel, V V; Clark, J W

    2001-01-01

    The separation method developed earlier by us [Nucl. Phys. {\\bf A598} 390 (1996)] to calculate and analyze solutions of the BCS gap equation for $^1$S$_0$ pairing is extended and applied to $^3$P$_2$--$^3$F$_2$ pairing in pure neutron matter. The pairing matrix elements are written as a separable part plus a remainder that vanishes when either momentum variable is on the Fermi surface. This decomposition effects a separation of the problem of determining the dependence of the gap components in a spin-angle representation on the magnitude of the momentum (described by a set of functions independent of magnetic quantum number) from the problem of determining the dependence of the gap on angle or magnetic projection. The former problem is solved through a set of nonsingular, quasilinear integral equations, providing inputs for solution of the latter problem through a coupled system of algebraic equations for a set of numerical coefficients. An incisive criterion is given for finding the upper critical density fo...

  10. Morse theory and stable pairs

    CERN Document Server

    Wentworth, Richard A

    2010-01-01

    We study the Morse theory of the Yang-Mills-Higgs functional on the space of pairs $(A,\\Phi)$, where $A$ is a unitary connection on a rank 2 hermitian vector bundle over a compact Riemann surface, and $\\Phi$ is a holomorphic section of $(E, d_A")$. We prove that a certain explicitly defined substratification of the Morse stratification is perfect in the sense of $\\G$-equivariant cohomology, where $\\G$ denotes the unitary gauge group. As a consequence, Kirwan surjectivity holds for pairs. It also follows that the twist embedding into higher degree induces a surjection on equivariant cohomology. This may be interpreted as a rank 2 version of the analogous statement for symmetric products of Riemann surfaces. Finally, we compute the $\\G$-equivariant Poincar\\'e polynomial of the space of $\\tau$-semistable pairs. In particular, we recover an earlier result of Thaddeus. The analysis provides an interpretation of the Thaddeus flips in terms of a variation of Morse functions.

  11. Mediators of homologous DNA pairing.

    Science.gov (United States)

    Zelensky, Alex; Kanaar, Roland; Wyman, Claire

    2014-10-09

    Homologous DNA pairing and strand exchange are at the core of homologous recombination. These reactions are promoted by a DNA-strand-exchange protein assembled into a nucleoprotein filament comprising the DNA-pairing protein, ATP, and single-stranded DNA. The catalytic activity of this molecular machine depends on control of its dynamic instability by accessory factors. Here we discuss proteins known as recombination mediators that facilitate formation and functional activation of the DNA-strand-exchange protein filament. Although the basics of homologous pairing and DNA-strand exchange are highly conserved in evolution, differences in mediator function are required to cope with differences in how single-stranded DNA is packaged by the single-stranded DNA-binding protein in different species, and the biochemical details of how the different DNA-strand-exchange proteins nucleate and extend into a nucleoprotein filament. The set of (potential) mediator proteins has apparently expanded greatly in evolution, raising interesting questions about the need for additional control and coordination of homologous recombination in more complex organisms. Copyright © 2014 Cold Spring Harbor Laboratory Press; all rights reserved.

  12. Contact and hybrid zone hotspots and evolution of birds in the Middle East

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The Middle East is an important contact zone for a considerable number of bird taxa from the western and eastern Palearctic and from the great Saharo-Sindian jesert belt. Using WORLDMAP software, we analyzed the geographical distribution of secondary contact zones for parapatric species pairs of birds in the Middle East. We identified 56 species (29 species pairs) that make contact in the Middle East. The species pairs belong to three orders, i.e. Falconiformes, Piciformes, and Passeriformes. Almost half (46%) of these species pairs hybridize in their contact zones. Although contact zones occur over a large part of northern Middle East, spatially they were not evenly distributed. Contact zone richness was highest in the mountain ranges south of the Caspian Sea and the Caucasus. The hottest hotspots, where up to nine bird species pairs occur sympatrically, are situated in north-eastern Iran and Azerbaijan. We discuss the relevance of these hotspots for improving our understanding of the biogeography and evolution of the avifauna in the Middle East.

  13. The level of social contact affects social behaviour in pre-weaned dairy calves

    DEFF Research Database (Denmark)

    Duve, Linda Rosager; Jensen, Margit Bak

    2011-01-01

    The present study investigated the effects of the level of social contact in the home environment on the social preference, bonding and social behaviour of pre-weaned dairy calves. Twenty-seven pairs of calves were reared from birth until 6 weeks either individually (with limited social contact...... between bars; L-calves), in pairs (with full social contact; F-calves), or individually for 3 weeks and in pairs for the next 3 weeks (LF-calves). At 5 weeks of age the bonding between calves in a pair was evaluated by measuring their response to separation and the subsequent reunion in the home...... environment. The following day the social preference was evaluated in a triangular test arena where the calves could choose between the companion and an unfamiliar calf. Finally, at 6 weeks of age the response of the calves to a novel arena, alone and with the companion, was measured. During separation...

  14. Thermal conductance of augmented pressed metallic contacts at liquid helium temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Salerno, L.J.; Kittel, P.; Spivak, A.L.

    1992-08-01

    The thermal conductance of uncoated oxygen-free high conductivity (OFHC) copper, 6061-T6 aluminum, free-machining brass, and 304 stainless steel sample pairs which were augmented with a gold coated 6061-T6 aluminum washer inserted between the contact surfaces was measured over the temperature range of 1.6 to 6.0 K, with applied forces from 22 to 670 N. The contact surfaces of the sample pairs were prepared with a 0.8 micron lapped finish, while the finish of the aluminum washer was 0.2 micron lapped. The contribution to the overall thermal impedance by the bulk conductance of the aluminum washer was negligible. It was found that addition of the washer offered no significant conductance improvement over an uncoated single contact pair; any benefits from using the gold plated washer were counteracted by the addition of two more contact surfaces. Additionally, the thermal conductance of a 'combination' aluminum sample pair having one gold coated and one uncoated surface was measured and compared to the washer pair. The ratio of the conductance of the washer pair to half the conductance of the 'combination' pair was found to be constant and near unity over the temperature range of the data obtained, within experimental error.

  15. Equilibrium contact angle or the most-stable contact angle?

    Science.gov (United States)

    Montes Ruiz-Cabello, F J; Rodríguez-Valverde, M A; Cabrerizo-Vílchez, M A

    2014-04-01

    It is well-established that the equilibrium contact angle in a thermodynamic framework is an "unattainable" contact angle. Instead, the most-stable contact angle obtained from mechanical stimuli of the system is indeed experimentally accessible. Monitoring the susceptibility of a sessile drop to a mechanical stimulus enables to identify the most stable drop configuration within the practical range of contact angle hysteresis. Two different stimuli may be used with sessile drops: mechanical vibration and tilting. The most stable drop against vibration should reveal the changeless contact angle but against the gravity force, it should reveal the highest resistance to slide down. After the corresponding mechanical stimulus, once the excited drop configuration is examined, the focus will be on the contact angle of the initial drop configuration. This methodology needs to map significantly the static drop configurations with different stable contact angles. The most-stable contact angle, together with the advancing and receding contact angles, completes the description of physically realizable configurations of a solid-liquid system. Since the most-stable contact angle is energetically significant, it may be used in the Wenzel, Cassie or Cassie-Baxter equations accordingly or for the surface energy evaluation.

  16. Contact and Non-contact Measurements of Grinding Pins

    Directory of Open Access Journals (Sweden)

    Magdziak Marek

    2015-01-01

    Full Text Available The paper presents the results of contact and non-contact measurements of external profiles of selected grinding pins. The measurements were conducted in order to choose the appropriate measuring technique in the case of the considered measurement task. In the case of contact measurements the coordinate measuring machine ACCURA II was applied. The used coordinate measuring machine was equipped with the contact scanning probe VAST XT and the Calypso inspection software. Contact coordinate measurements were performed by using of different measurement strategies. The applied strategies included different scanning velocities and distances between measured points. Non-contact measurements were conducted by means of the tool presetter produced by the Mahr company. On the basis of gained results the guidelines concerning measurements of grinding pins were formulated. The measurements of analyzed grinding pins performed by means of the non-contact measuring system are characterized by higher reproducibility than the contact measurements. The low reproducibility of contact measurements may be connected with the inaccuracy of the selected coordinate measuring machine and the measuring probe, the measurement parameters and environmental conditions in the laboratory where the coordinate measuring machine is located. Moreover, the paper presents the possible application of results of conducted investigations. The results of non-contact measurements can be used in the simulation studies of grinding processes. The simulations may reduce the costs of machining processes.

  17. Reducing contact resistance in graphene devices through contact area patterning.

    Science.gov (United States)

    Smith, Joshua T; Franklin, Aaron D; Farmer, Damon B; Dimitrakopoulos, Christos D

    2013-04-23

    Performance of graphene electronics is limited by contact resistance associated with the metal-graphene (M-G) interface, where unique transport challenges arise as carriers are injected from a 3D metal into a 2D-graphene sheet. In this work, enhanced carrier injection is experimentally achieved in graphene devices by forming cuts in the graphene within the contact regions. These cuts are oriented normal to the channel and facilitate bonding between the contact metal and carbon atoms at the graphene cut edges, reproducibly maximizing "edge-contacted" injection. Despite the reduction in M-G contact area caused by these cuts, we find that a 32% reduction in contact resistance results in Cu-contacted, two-terminal devices, while a 22% reduction is achieved for top-gated graphene transistors with Pd contacts as compared to conventionally fabricated devices. The crucial role of contact annealing to facilitate this improvement is also elucidated. This simple approach provides a reliable and reproducible means of lowering contact resistance in graphene devices to bolster performance. Importantly, this enhancement requires no additional processing steps.

  18. Contact angle and local wetting at contact line.

    Science.gov (United States)

    Li, Ri; Shan, Yanguang

    2012-11-06

    This theoretical study was motivated by recent experiments and theoretical work that had suggested the dependence of the static contact angle on the local wetting at the triple-phase contact line. We revisit this topic because the static contact angle as a local wetting parameter is still not widely understood and clearly known. To further clarify the relationship of the static contact angle with wetting, two approaches are applied to derive a general equation for the static contact angle of a droplet on a composite surface composed of heterogeneous components. A global approach based on the free surface energy of a thermodynamic system containing the droplet and solid surface shows the static contact angle as a function of local surface chemistry and local wetting state at the contact line. A local approach, in which only local forces acting on the contact line are considered, results in the same equation. The fact that the local approach agrees with the global approach further demonstrates the static contact angle as a local wetting parameter. Additionally, the study also suggests that the wetting described by the Wenzel and Cassie equations is also the local wetting of the contact line rather than the global wetting of the droplet.

  19. Mechanical Contact Experiments and Simulations

    DEFF Research Database (Denmark)

    Nielsen, Chris Valentin; Martins, P; Zhang, W.

    2011-01-01

    Mechanical contact is studied under dynamic development by means of a combined numerical and experimental investigation. The experiments are designed to allow dynamical development of non-planar contact areas with significant expansion in all three directions as the load is increased. Different...... geometries and different materials are analyzed including contact between dissimilar materials. The numerical implementation is performed with a finite element computer program based on the irreducible flow formulation, and contact between deformable objects is modelled by applying the penalty method....... The overall investigation serves for testing and validating the numerical implementation of the mechanical contact, which is one of the main contributions to a system intended for 3D simulation of resistance welding. Correct modelling of contact between parts to be welded, as well as contact with electrodes...

  20. Point contacts in encapsulated graphene

    Energy Technology Data Exchange (ETDEWEB)

    Handschin, Clevin [Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Swiss Nanoscience Institute, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Fülöp, Bálint; Csonka, Szabolcs [Department of Physics, Budapest University of Technology and Economics and Condensed Matter Research Group of the Hungarian Academy of Sciences, Budafoki ut 8, 1111 Budapest (Hungary); Makk, Péter; Blanter, Sofya; Weiss, Markus; Schönenberger, Christian, E-mail: Christian.Schoenenberger@unibas.ch [Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Watanabe, Kenji; Taniguchi, Takashi [National Institute for Material Science, 1-1 Namiki, Tsukuba 305-0044 (Japan)

    2015-11-02

    We present a method to establish inner point contacts with dimensions as small as 100 nm on hexagonal boron nitride (hBN) encapsulated graphene heterostructures by pre-patterning the top-hBN in a separate step prior to dry-stacking. 2- and 4-terminal field effect measurements between different lead combinations are in qualitative agreement with an electrostatic model assuming point-like contacts. The measured contact resistances are 0.5–1.5 kΩ per contact, which is quite low for such small contacts. By applying a perpendicular magnetic field, an insulating behaviour in the quantum Hall regime was observed, as expected for inner contacts. The fabricated contacts are compatible with high mobility graphene structures and open up the field for the realization of several electron optical proposals.

  1. Hair dye contact allergy

    DEFF Research Database (Denmark)

    Søsted, Heidi; Rastogi, Suresh Chandra; Andersen, Klaus Ejner

    2004-01-01

    Colouring of hair can cause severe allergic contact dermatitis. The most frequently reported hair dye allergens are p-phenylenediamine (PPD) and toluene-2,5-diamine, which are included in, respectively, the patch test standard series and the hairdressers series. The aim of the present study...... was to identify dye precursors and couplers in hair dyeing products causing clinical hair dye dermatitis and to compare the data with the contents of these compounds in a randomly selected set of similar products. The patient material comprised 9 cases of characteristic clinical allergic hair dye reaction, where...... exposure history and patch testing had identified a specific hair dye product as the cause of the reaction. The 9 products used by the patients were subjected to chemical analysis. 8 hair dye products contained toluene-2,5-diamine (0.18 to 0.98%). PPD (0.27%) was found in 1 product, and m-aminophenol (0...

  2. Contact dermatitis to Alstroemeria.

    Science.gov (United States)

    Santucci, B; Picardo, M; Iavarone, C; Trogolo, C

    1985-04-01

    A study was carried out on 50 workers in a floriculture centre to evaluate the incidence of contact dermatitis to Alstroemeria. 3 subjects gave positive reactions to aqueous and ethanolic extracts of cut flowers, stems and leaves. By column chromatography, the allergen was isolated and its chemical structure identified as 6-tuliposide A by proton magnetic resonance and carbon-13 magnetic resonance. Only 6-tuliposide A was isolated from cut flowers, and this gave positive reactions when patch tested at 0.01%; a-methylene-gamma-butyrolactone at 10(-5) (v/v) was positive in the same 3 subjects. Other lactones (gamma-methylene-gamma-butyrolactone, alantolactone, isoalantolactone) were negative at all concentrations used.

  3. Fragrance contact allergy

    DEFF Research Database (Denmark)

    Johansen, Jeanne D

    2003-01-01

    in the same products. This means that it is difficult to avoid exposure, as products labelled as 'fragrance free' have also been shown to contain fragrance ingredients, either because of the use of fragrance ingredients as preservatives or masking perfumes, or the use of botanicals. About 2500 different...... typically have a history of rash to a fine fragrance or scented deodorants. Chemical analysis has revealed that well known allergens from the fragrance mix are present in 15-100% of cosmetic products, including deodorants and fine fragrances, and most often in combinations of three to four allergens...... fragrance ingredients are currently used in the composition of perfumes and at least 100 of these are known contact allergens. Therefore, it is advisable to supplement standard patch testing with the patient's own stay-on cosmetic products, as well as the fragrance chemical hydroxyisohexyl-3-cyclohexane...

  4. Fragrance contact allergy

    DEFF Research Database (Denmark)

    Johansen, Jeanne D

    2003-01-01

    typically have a history of rash to a fine fragrance or scented deodorants. Chemical analysis has revealed that well known allergens from the fragrance mix are present in 15-100% of cosmetic products, including deodorants and fine fragrances, and most often in combinations of three to four allergens...... in the same products. This means that it is difficult to avoid exposure, as products labelled as 'fragrance free' have also been shown to contain fragrance ingredients, either because of the use of fragrance ingredients as preservatives or masking perfumes, or the use of botanicals. About 2500 different...... fragrance ingredients are currently used in the composition of perfumes and at least 100 of these are known contact allergens. Therefore, it is advisable to supplement standard patch testing with the patient's own stay-on cosmetic products, as well as the fragrance chemical hydroxyisohexyl-3-cyclohexane...

  5. Cosmetic Contact Allergens

    Directory of Open Access Journals (Sweden)

    An Goossens

    2016-02-01

    Full Text Available This article presents trends in the frequency of cosmetics as causal factors of allergic contact dermatitis during a 26-year period in 14,911 patients patch-tested between 1990 and 2014, and discusses the cosmetic allergens identified during the last six years (2010–2015 in 603 patients out of 3105 tested. The data were retrieved from, and evaluated with, a patient database developed in-house. The results show the increasing importance of cosmetic allergies, up to 25% of the patients tested during the last five-year period. As expected, fragrance materials, preservatives, and hair dyes were the most frequent culprits, but a great variety of other allergenic ingredients were involved as well. This underlines the need of additional and extensive patch testing with the patient’s products used and their ingredients.

  6. Mechanoluminescent Contact Type Sensor

    Directory of Open Access Journals (Sweden)

    A. K. Yefremov

    2017-01-01

    Full Text Available Mechanoluminescent sensing elements convert mechanical stress into optical radiation. Advantages of such sensors are the ability to generate an optical signal, solid-state, simple structure, and resistance to electromagnetic interference. Mechanoluminescent sensor implementations can possess the concentrated and distributed sensitivity, thereby allowing us to detect the field of mechanical stresses distributed across the area and in volume. Most modern semiconductor photo-detectors can detect mechanoluminescent radiation, so there are no difficulties to provide its detection when designing the mechanoluminescent sensing devices. Mechanoluminescent substances have especial sensitivity to shock loads, and this effect can be used to create a fuse the structure of which includes a target contact type sensor with a photosensitive actuator. The paper briefly describes the theoretical basics of mechanoluminiscence: a light signal emerges from the interaction of crystalline phosphor luminescence centers with electrically charged dislocations, moving due to the deformation of the crystal. A mathematical model of the mechanoluminescent conversion is represented as a functional interaction between parameters of the mechanical shock excitation and the sensor light emission. Examples of computing the optical mechanoluminescent output signal depending on the duration and peak level of impulse load are given. It is shown that the luminous flux, generated by mechanoluminescent sensing element when there is an ammunition-target collision causes the current emerging in photo-detector (photodiode that is sufficient for a typical actuator of the fuse train to operate. The potential possibility to create a contact target type sensor based on the light-sensitive mechanoluminescent sensor was proved by the calculation and simulation results.

  7. Coefficient of friction of a starved lubricated spur gear pair

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Huaiju; Zhu, Caichao; Sun, Zhangdong; Zhang, Yuanyuan; Song, Chaosheng [Chongqing University, Chongqing (China)

    2016-05-15

    The frictional power loss issue of gear pairs becomes an important concern in both industry and academia due to the requirement of the energy saving and the improvement of power density of gear drives. A thermal starved elastohydrodynamic lubrication model is developed to study the tribological performance of a spur gear pair under starved lubrication conditions. The contact pressure, the film thickness, the temperature rise, the frictional power loss, as well as the coefficient of friction are evaluated by considering the variation of the curvature radius, the sliding/rolling motion, and the load distribution of gear tooth within the meshing period. Effects of lubrication starvation condition, load and speed on the coefficient of friction are studied.

  8. Pair tunneling of two atoms out of a trap

    Science.gov (United States)

    Rontani, Massimo

    2013-10-01

    A simple theory for the tunneling of two cold atoms out of a trap in the presence of an attractive contact force is developed. Two competing decay channels, for single-atom and bound-pair tunneling, respectively, contribute independently to the decay law of the mean atom number in the trap. The single-atom tunneling rate is obtained through the quasiparticle wave function formalism. For pair tunneling an effective equation for the center-of-mass motion is derived, so the calculation of the corresponding tunneling rate is again reduced to a simpler one-body problem. The predicted dependence of tunneling rates on the interaction strength qualitatively agrees with a recent measurement of the two-atom decay time [G. Zürn, A. N. Wenz, S. Murmann, T. Lompe, and S. Jochim, arXiv:1307.5153].

  9. Charge Aspects of Composite Pair Superconductivity

    Science.gov (United States)

    Flint, Rebecca

    2014-03-01

    Conventional Cooper pairs form from well-defined electronic quasiparticles, making the internal structure of the pair irrelevant. However, in the 115 family of superconductors, the heavy electrons are forming as they pair and the internal pair structure becomes as important as the pairing mechanism. Conventional spin fluctuation mediated pairing cannot capture the direct transition from incoherent local moments to heavy fermion superconductivity, but the formation of composite pairs favored by the two channel Kondo effect can. These composite pairs are local d-wave pairs formed by two conduction electrons in orthogonal Kondo channels screening the same local moment. Composite pairing shares the same symmetries as magnetically mediated pairing, however, only composite pairing necessarily involves a redistribution of charge within the unit cell originating from the internal pair structure, both as a monopole (valence change) and a quadrupole effect. This redistribution will onset sharply at the superconducting transition temperature. A smoking gun test for composite pairing is therefore a sharp signature at Tc - for example, a cusp in the Mossbauer isomer shift in NpPd5Al2 or in the NQR shift in (Ce,Pu)CoIn5.

  10. Partition function and base pairing probabilities of RNA heterodimers

    Directory of Open Access Journals (Sweden)

    Stadler Peter F

    2006-03-01

    Full Text Available Abstract Background RNA has been recognized as a key player in cellular regulation in recent years. In many cases, non-coding RNAs exert their function by binding to other nucleic acids, as in the case of microRNAs and snoRNAs. The specificity of these interactions derives from the stability of inter-molecular base pairing. The accurate computational treatment of RNA-RNA binding therefore lies at the heart of target prediction algorithms. Methods The standard dynamic programming algorithms for computing secondary structures of linear single-stranded RNA molecules are extended to the co-folding of two interacting RNAs. Results We present a program, RNAcofold, that computes the hybridization energy and base pairing pattern of a pair of interacting RNA molecules. In contrast to earlier approaches, complex internal structures in both RNAs are fully taken into account. RNAcofold supports the calculation of the minimum energy structure and of a complete set of suboptimal structures in an energy band above the ground state. Furthermore, it provides an extension of McCaskill's partition function algorithm to compute base pairing probabilities, realistic interaction energies, and equilibrium concentrations of duplex structures. Availability RNAcofold is distributed as part of the Vienna RNA Package, http://www.tbi.univie.ac.at/RNA/. Contact Stephan H. Bernhart – berni@tbi.univie.ac.at

  11. A CONTACT SEARCHING ALGORITHM FOR CONTACT-IMPACT PROBLEMS

    Institute of Scientific and Technical Information of China (English)

    Wang Fujun; Cheng Jiangang; Yao Zhenhan

    2000-01-01

    A new contact searching algorithm for contact-impact systems is proposed in this paper. In terms of the cell structure and the linked-list, this algorithm solves the problem of sorting and searching contacts in three dimensions by transforming it to a retrieving process from two one-dimensional arrays, and binary searching is no longer required. Using this algorithm, the cost of contact searching is reduced to the order of O(N) instead of O(Nlog2N) for traditional ones, where N is the node number in the system. Moreover, this algorithm can handle contact systems with arbitrary mesh layouts. Due to the simplicity of this algorithm it can be easily implemented in a dynamic explicit finite element Program. Our numerical experimental result shows that this algorithm is reliable and efficient for contact searching of three dimensional systems.

  12. Pair Tunneling through Single Molecules

    Science.gov (United States)

    Raikh, Mikhail

    2007-03-01

    Coupling to molecular vibrations induces a polaronic shift, and can lead to a negative charging energy, U. For negative U, the occupation of the ground state of the molecule is even. In this situation, virtual pair transitions between the molecule and the leads can dominate electron transport. At low temperature, T, these transitions give rise to the charge-Kondo effect [1]. We developed the electron transport theory through the negative-U molecule [2] at relatively high T, when the Kondo correlations are suppressed. Two physical ingredients distinguish our theory from the transport through a superconducting grain coupled to the normal leads [3]: (i) in parallel with sequential pair-tunneling processes, single-particle cotunneling processes take place; (ii) the electron pair on the molecule can be created (or annihilated) by two electrons tunneling in from (or out to) opposite leads. We found that, even within the rate-equation description, the behavior of differential conductance through the negative-U molecule as function of the gate voltage is quite peculiar: the height of the peak near the degeneracy point is independent of temperature, while its width is proportional to T. This is in contrast to the ordinary Coulomb-blockade conductance peak, whose integral strength is T-independent. At finite source-drain bias, V>>T, the width of the conductance peak is ˜V, whereas the conventional Coulomb-blockade peak at finite V splits into two sharp peaks at detunings V/2, and -V/2. Possible applications to the gate-controlled current rectification and switching will be discussed. [1] A. Taraphder and P. Coleman, Phys. Rev. Lett. 66, 2814 (1991). [2] J. Koch, M. E. Raikh, and F. von Oppen, Phys. Rev. Lett. 96, 056803 (2006). [3] F. W. J. Hekking, L. I. Glazman, K. A. Matveev, and R. I. Shekhter, Phys. Rev. Lett. 70, 4138 (1993).

  13. Robust Algorithms for Contact Problems with Constitutive Contact Laws

    OpenAIRE

    2016-01-01

    This thesis is concerned with the solution of contact problems with advanced Coulomb friction in the 3D case using the finite element method. A Lagrange multiplier method modelling the contact traction is employed and the contact conditions are enforced in a weak sense leading to a surface-to-surface discretization. Here more precisely the dual mortar method is used allowing for a static condensation of the additional variables in the system before solving without loosing the optimality of...

  14. Endocrine factors of pair bonding.

    Science.gov (United States)

    Stárka, L

    2007-01-01

    Throughout literature--fiction and poetry, fine arts and music--falling in love and enjoying romantic love plays a central role. While several psychosocial conceptions of pair attachment consider the participation of hormones, human endocrinology has dealt with this theme only marginally. According to some authors in addictology, falling in love shows some signs of hormonal response to stressors with changes in dopamine and serotonin signalling and neurotrophin (transforming growth factor b) concentration. Endorphins, oxytocin and vasopressin may play a role during the later phases of love. However, proof of hormonal events associated with love in humans has, until recently, been lacking.

  15. Top pair production at ATLAS

    Directory of Open Access Journals (Sweden)

    Loginov Andrey

    2013-05-01

    Full Text Available An overview of latest ATLAS measurements of top pair (tt̅ production in proton-proton collisions at the LHC at centre-of-mass energies of 7 and 8 TeV is presented. Measurements of the tt̅ production cross section (σtt̅ in various decay channels, including analyses of differential σtt̅ distributions and a study of jet multiplicity in tt̅ production, as well as searches for tt̅ resonances using boosted top techniques and standard methods, are discussed.

  16. Hysteresis during contact angles measurement.

    Science.gov (United States)

    Diaz, M Elena; Fuentes, Javier; Cerro, Ramon L; Savage, Michael D

    2010-03-15

    A theory, based on the presence of an adsorbed film in the vicinity of the triple contact line, provides a molecular interpretation of intrinsic hysteresis during the measurement of static contact angles. Static contact angles are measured by placing a sessile drop on top of a flat solid surface. If the solid surface has not been previously in contact with a vapor phase saturated with the molecules of the liquid phase, the solid surface is free of adsorbed liquid molecules. In the absence of an adsorbed film, molecular forces configure an advancing contact angle larger than the static contact angle. After some time, due to an evaporation/adsorption process, the interface of the drop coexists with an adsorbed film of liquid molecules as part of the equilibrium configuration, denoted as the static contact angle. This equilibrium configuration is metastable because the droplet has a larger vapor pressure than the surrounding flat film. As the drop evaporates, the vapor/liquid interface contracts and the apparent contact line moves towards the center of the drop. During this process, the film left behind is thicker than the adsorbed film and molecular attraction results in a receding contact angle, smaller than the equilibrium contact angle.

  17. Filipino au pairs on the move

    DEFF Research Database (Denmark)

    Dalgas, Karina Märcher

    2016-01-01

    Most Filipina au pairs in Denmark send remittances back home, and for many, au pairing forms part of longer-term migration trajectories. This article explores how Filipina au pairs try to carve out a future for themselves abroad. It shows that they navigate within tight webs of financial interdep......Most Filipina au pairs in Denmark send remittances back home, and for many, au pairing forms part of longer-term migration trajectories. This article explores how Filipina au pairs try to carve out a future for themselves abroad. It shows that they navigate within tight webs of financial...

  18. Periumbilical allergic contact dermatitis: blue jeans or belt buckles?

    Science.gov (United States)

    Byer, Tara T; Morrell, Dean S

    2004-01-01

    Nickel is the most ubiquitous contact allergen among children and adolescents. Metal blue jeans buttons and belts have been noted to cause nickel dermatitis around the umbilicus. For these children, traditional teaching is strict avoidance of all pants with metal snaps/buttons, particularly blue jeans. In this study we tested 90 pairs of blue jeans and 47 belts for nickel using the dimethylglyoxime spot test. Only 10% of blue jeans tested positive, while 53% of belts tested positive. Furthermore, 10 pairs of nickel-negative blue jeans remained negative after 10 washings. Overall we found no resistance to testing in clothing stores. From these results, we recommend that patients with allergic contact dermatitis secondary to nickel need not strictly avoid blue jeans and metal belt buckles. Rather, families should be encouraged to use the dimethylglyoxime spot test to test these items for nickel prior to purchase.

  19. Contact resistance of ceramic interfaces between materials used for solid oxide fuel cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Koch, S.

    2002-01-01

    The contact resistance can be divided into two main contributions. The small area of contact between ceramic components results in resistance due to current constriction. Resistive phases or potential barriers at the interface result in an interface contribution to the contact resistance, which may be smaller or larger than the constriction resistance. The contact resistance between pairs of three different materials were analysed (strontium doped lanthanum manganite, yttria stabilised zirconia and strontium and nickel doped lanthanum cobaltite), and the effects of temperature, atmosphere, polarisation and mechanical load on the contact resistance were investigated. The investigations revealed that the mechanical load of a ceramic contact has a high influence on the contact resistance, and generally power law dependence between the contact resistance and the mechanical load was found. The influence of the mechanical load on the contact resistance was ascribed to an area effect. The contact resistance of the investigated materials was dominated by current constriction at high temperatures. The measured contact resistance was comparable to the resistance calculated on basis of the contact areas found by optical and electron microscopy. At low temperatures, the interface contribution to the contact resistance was dominating. The cobaltite interface could be described by one potential barrier at the contact interface, whereas the manganite interfaces required several consecutive potential barriers to model the observed behaviour. The current-voltage behaviour of the YSZ contact interfaces was only weakly non-linear, and could be described by 22{+-}1 barriers in series. Contact interfaces with sinterable contact layers were also investigated, and the measured contact resistance for these interfaces were more than 10 times less than for the other interfaces. (au)

  20. Contact sport and osteoarthritis.

    LENUS (Irish Health Repository)

    Molloy, Michael G

    2011-04-01

    Osteoarthritis (OA) is the most common joint disease in the world and the single largest cause of disability for those over 18 years. It affects more than twice as many people as does cardiac disease, and increases in incidence and prevalence with age. Animal and human studies have shown no evidence of increased risk of hip or knee OA with moderate exercise and in the absence of traumatic injury, sporting activity has a protective effect. One age-matched case control study found recreational runners who ran 12-14 miles per week for up to 40 years had no increase in radiological or symptomatic hip or knee OA. However, higher rates of hip OA occur in contact sports than in age-matched controls, with the highest rate in professional players. Soccer players with torn anterior cruciate ligaments (ACL) are more likely to develop knee OA than those with intact ACL. Early ACL repair reduces the risk of knee OA, but does not prevent it. Established injury prevention programmes have been refined to prevent injuries such as ACL rupture.

  1. Noise of sliding rough contact

    Science.gov (United States)

    Le Bot, Alain

    2017-01-01

    This article is a discussion about the origin of friction noise produced when rubbing solids having rough surfaces. We show that noise emerges from numerous impacts into the contact between antagonist asperities of surfaces. Prediction of sound sources reduces to a statistical problem of contact mechanics. On the other hand, contact is also responsible of dissipation of vibration. This leads to the paradoxical result that the noise may not be proportional to the number of sources.

  2. Bound Polaron Pair Formation in Poly (phenylenevinylenes)

    Science.gov (United States)

    Rothberg, Lewis

    The following sections are included: * INTRODUCTION * PHOTOGENERATED YIELD OF SINGLET EXCITONS * AGGREGRATION EFFECTS ON EXCITED STATE PHOTO-GENERATION * ASSIGNMENT TO BOUND POLARON PAIRS AND DISCUSSION * PROBLEMS WITH THE BOUND POLARON PAIR PICTURE AND CONCLUSION * REFERENCES

  3. Ion Implanted Passivated Contacts for Interdigitated Back Contacted Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Young, David L.; Nemeth, William; LaSalvia, Vincenzo; Reedy, Robert; Bateman, Nicholas; Stradins, Pauls

    2015-06-14

    We describe work towards an interdigitated back contacted (IBC) solar cell utilizing ion implanted, passivated contacts. Formation of electron and hole passivated contacts to n-type CZ wafers using tunneling SiO2 and ion implanted amorphous silicon (a-Si) are described. P and B were ion implanted into intrinsic amorphous Si films at several doses and energies. A series of post-implant anneals showed that the passivation quality improved with increasing annealing temperatures up to 900 degrees C. The recombination parameter, Jo, as measured by a Sinton lifetime tester, was Jo ~ 14 fA/cm2 for Si:P, and Jo ~ 56 fA/cm2 for Si:B contacts. The contact resistivity for the passivated contacts, as measured by TLM patterns, was 14 milliohm-cm2 for the n-type contact and 0.6 milliohm-cm2 for the p-type contact. These Jo and pcontact values are encouraging for forming IBC cells using ion implantation to spatially define dopants.

  4. Contextualizing Intergroup Contact: Do Political Party Cues Enhance Contact Effects?

    DEFF Research Database (Denmark)

    Sønderskov, Kim Mannemar; Thomsen, Jens Peter Frølund

    2015-01-01

    This article examines intergroup contact effects in different political contexts. We expand on previous efforts of social psychologists by incorporating the messages of political parties as a contextual trigger of group membership awareness in contact situations. We argue that the focus among...

  5. Fision: Nucleon pair breaking before scission

    OpenAIRE

    Montoya, Modesto

    1984-01-01

    In order to explain the odd-even effect observed in low energy fission fragment distributions it has been recently required a double mechanism of nucleon pair breaking: before scission (early pair breaking) and at scission (late pair breaking), respectively. In the present work we show that, using the same formulae but considering only the early pair breaking mechanism, one can reproduce fairly well all the available experimental data on the odd-even effects.

  6. Computational Contact Mechanics Geometrically Exact Theory for Arbitrary Shaped Bodies

    CERN Document Server

    Konyukhov, Alexander

    2013-01-01

    This book contains a systematical analysis of geometrical situations  leading to  contact pairs -- point-to-surface, surface-to-surface, point-to-curve, curve-to-curve and curve-to-surface.  Each contact pair  is inherited with a special coordinate system based on its geometrical properties such as a Gaussian surface coordinate system or a Serret-Frenet curve coordinate system.  The formulation in a covariant form allows in a straightforward fashion to consider various constitutive relations for a  certain pair such as anisotropy for both frictional and structural parts. Then standard methods well known in computational contact mechanics such as penalty, Lagrange multiplier methods, combination of both and others  are formulated in these coordinate systems. Such formulations require then the powerful apparatus of differential geometry of surfaces and curves as well as of convex analysis. The final goals of such transformations are  then ready-for-implementation numerical algorithms within the finite e...

  7. CISM Course on Rolling Contact Phenomena

    CERN Document Server

    Kalker, Joost

    2000-01-01

    Preface.- Rolling Contact Phenomena - Linear Elasticity.- Finite Element Methods for Rolling Contact.- Plastic Deformation in Rolling Contact.- Non-Steady State Rolling Contact and Corrugations.- Modelling of Tyre Force and Moment Generation.- Rolling Noise.- Lubrication

  8. Contact line and contact angle dynamics in superhydrophobic channels.

    Science.gov (United States)

    Zhang, Junfeng; Kwok, Daniel Y

    2006-05-23

    The dynamics of the wetting and movement of a three-phase contact line confined between two superhydrophobic surfaces were studied using a mean-field free-energy lattice Boltzmann model. Principle features of superhydrophobic surfaces, such as trapped vapor/air between rough microstructures, high contact angles, reduced contact angle hysteresis, and low resistance to fluid flow, were all observed. Movement of the three-phase contact line over a well-patterned superhydrophobic surface displays a periodic stick-jump-slip behavior, while the dynamic contact angle changes accordingly from maximum to minimum. Two regimes were found for the flow velocity as a function of surface roughness and can be related directly to the balance between driving force and flow resistance. This work provides a better understanding of dynamic wetting and fluid flow behaviors over superhydrophobic surfaces and hence could be useful in related applications.

  9. Drift wave in pair-ion plasma

    Indian Academy of Sciences (India)

    Samiran Ghosh; Nikhil Chakrabarti; Manoranjan Khan; M R Gupta

    2013-02-01

    The conditions for the existence of low-frequency electrostatic drift wave in pair-ion plasma are discussed. It is shown that the temperature and/or mass difference of both species could produce drift wave in a pair-ion plasma. The results are discussed in the context of the fullerene pair-ion plasma experiment.

  10. On one-sided torsion pair

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Motivated by the concept of a torsion pair in a pre-triangulated category induced by Beligiannis and Reiten, the notion of a left (right) torsion pair in the left (right) triangulated category is introduced and investigated. We provide new connections between different aspects of torsion pairs in one-sided triangulated categories, pre-triangulated categories, stable categories and derived categories.

  11. Homolog pairing and segregation in Drosophila meiosis.

    Science.gov (United States)

    McKee, B D

    2009-01-01

    Pairing of homologous chromosomes is fundamental to their reliable segregation during meiosis I and thus underlies sexual reproduction. In most eukaryotes homolog pairing is confined to prophase of meiosis I and is accompanied by frequent exchanges, known as crossovers, between homologous chromatids. Crossovers give rise to chiasmata, stable interhomolog connectors that are required for bipolar orientation (orientation to opposite poles) of homologs during meiosis I. Drosophila is unique among model eukaryotes in exhibiting regular homolog pairing in mitotic as well as meiotic cells. I review the results of recent molecular studies of pairing in both mitosis and meiosis in Drosophila. These studies show that homolog pairing is continuous between pre-meiotic mitosis and meiosis but that pairing frequencies and patterns are altered during the mitotic-meiotic transition. They also show that, with the exception of X-Y pairing in male meiosis, which is mediated specifically by the 240-bp rDNA spacer repeats, chromosome pairing is not restricted to specific sites in either mitosis or meiosis. Instead, virtually all chromosome regions, both heterochromatic and euchromatic, exhibit autonomous pairing capacity. Mutations that reduce the frequencies of both mitotic and meiotic pairing have been recently described, but no mutations that abolish pairing completely have been discovered, and the genetic control of pairing in Drosophila remains to be elucidated.

  12. QUANTUM CRYPTOGRAPHY WITH PHOTON PAIRS

    Directory of Open Access Journals (Sweden)

    Anand Sharma,

    2010-07-01

    Full Text Available Quantum cryptographic systems use quantum mechanical concepts that are based on qubit superposition of states, and on the no cloning or no copying theorem to establish unbreakable cipher keys. The basic idea of quantum cryptography is to send the key in the form of photons over a public channel, encoding the zeros and one on quantum states in such a way that any eavesdropping attempt can be detected. Using optical communications the most commonly quantum mechanical property used is the polarization state of photon. However, in most quantum cryptographic algorithms a random polarization state is required. The photons are ideal for low loss transport, either in free space or in optical fibers, i.e. we have the full arsenal of fiber optic technology at our disposal. In this paper we are describing the process of quantum cryptography with photon pairs.

  13. Perturbations of vortex ring pairs

    CERN Document Server

    Gubser, Steven S; Parikh, Sarthak

    2015-01-01

    We study pairs of co-axial vortex rings starting from the action for a classical bosonic string in a three-form background. We complete earlier work on the phase diagram of classical orbits by explicitly considering the case where the circulations of the two vortex rings are equal and opposite. We then go on to study perturbations, focusing on cases where the relevant four-dimensional transfer matrix splits into two-dimensional blocks. When the circulations of the rings have the same sign, instabilities are mostly limited to wavelengths smaller than a dynamically generated length scale at which single-ring instabilities occur. When the circulations have the opposite sign, larger wavelength instabilities can occur.

  14. Paired states on a torus

    Energy Technology Data Exchange (ETDEWEB)

    Cristofano, Gerardo E-mail: gerardo.cristofano@na.infn.it; Maiella, Giuseppe E-mail: giuseppe.maiella@na.infn.it; Marotta, Vincenzo E-mail: vincenzo.marotta@na.infn.it; Niccoli, Giuliano E-mail: giuliano.niccoli@na.infn.it

    2002-10-14

    We analyze the modular properties of the effective CFT description for paired states, proposed in G. Cristofano, G. Maiella, V. Marrota, Mod. Phys. Lett. A 15 (2000) 1679, corresponding to the non-standard filling {nu}=((1)/(p+1)). We construct its characters for the twisted and the untwisted sector and the diagonal partition function. We show that the degrees of freedom entering our partition function naturally go to complete a Z{sub 2}-orbifold construction of the CFT for the Halperin state. Different behaviours for the p even and p odd cases are also studied. Finally it is shown that the tunneling phenomenon selects out a twist invariant CFT which is identified with the Moore-Read model.

  15. Contacts between the factor TUF and RPG sequences.

    Science.gov (United States)

    Vignais, M L; Huet, J; Buhler, J M; Sentenac, A

    1990-08-25

    The yeast TUF factor binds specifically to RPG-like sequences involved in multiple functions at enhancers, silencers, and telomeres. We have characterized the interaction of TUF with its optimal binding sequence, rpg-1 (1-ACACCCATACATTT-14), using a gel DNA-binding assay in combination with methylation protection and mutagenesis experiments. As many as 10 base pairs appear to be engaged in factor binding. Analysis of a collection of 30 different RPG mutants demonstrated the importance of 8 base pairs at position 2, 3, 4, 5, 6, 7, 10, and 12 and the critical role of the central GC pair at position 5. Methylation protection data on four different natural sites confirmed a close contact at positions 4, 5, 6, and 10 and suggested additional contacts at base pairs 8, 12, and 13. The derived consensus sequence was RCAAYCCRYNCAYY. A quantitative band shift analysis was used to determine the equilibrium dissociation constant for the complex of TUF and its optimal binding site rpg-1. The specific dissociation constant (K8) was found to be 1.3 x 10(-11) M. The comparison of the K8 value with the dissociation constant obtained for nonspecific DNA sites (Kn8 = 8.7 x 10(-6) M) shows the high binding selectivity of TUF for its specific RPG target.

  16. Reducing interaction in simultaneous paired stimulation with CI

    Science.gov (United States)

    Vellinga, Dirk; Briaire, Jeroen J.; Kalkman, Randy K.; Frijns, Johan H. M.

    2017-01-01

    In this study simultaneous paired stimulation of electrodes in cochlear implants is investigated by psychophysical experiments in 8 post-lingually deaf subjects (and one extra subject who only participated in part of the experiments). Simultaneous and sequential monopolar stimulation modes are used as references and are compared to channel interaction compensation, partial tripolar stimulation and a novel sequential stimulation strategy named phased array compensation. Psychophysical experiments are performed to investigate both the loudness integration during paired stimulation at the main electrodes as well as the interaction with the electrode contact located halfway between the stimulating pair. The study shows that simultaneous monopolar stimulation has more loudness integration on the main electrodes and more interaction in between the electrodes than sequential stimulation. Channel interaction compensation works to reduce the loudness integration at the main electrodes, but does not reduce the interaction in between the electrodes caused by paired stimulation. Partial tripolar stimulation uses much more current to reach the needed loudness, but shows the same interaction in between the electrodes as sequential monopolar stimulation. In phased array compensation we have used the individual impedance matrix of each subject to calculate the current needed on each electrode to exactly match the stimulation voltage along the array to that of sequential stimulation. The results show that the interaction in between the electrodes is the same as monopolar stimulation. The strategy uses less current than partial tripolar stimulation, but more than monopolar stimulation. In conclusion, the paper shows that paired stimulation is possible if the interaction is compensated. PMID:28182685

  17. Improving contact prediction along three dimensions.

    Directory of Open Access Journals (Sweden)

    Christoph Feinauer

    2014-10-01

    Full Text Available Correlation patterns in multiple sequence alignments of homologous proteins can be exploited to infer information on the three-dimensional structure of their members. The typical pipeline to address this task, which we in this paper refer to as the three dimensions of contact prediction, is to (i filter and align the raw sequence data representing the evolutionarily related proteins; (ii choose a predictive model to describe a sequence alignment; (iii infer the model parameters and interpret them in terms of structural properties, such as an accurate contact map. We show here that all three dimensions are important for overall prediction success. In particular, we show that it is possible to improve significantly along the second dimension by going beyond the pair-wise Potts models from statistical physics, which have hitherto been the focus of the field. These (simple extensions are motivated by multiple sequence alignments often containing long stretches of gaps which, as a data feature, would be rather untypical for independent samples drawn from a Potts model. Using a large test set of proteins we show that the combined improvements along the three dimensions are as large as any reported to date.

  18. Molecular dynamics study of contact mechanics: contact area and interfacial separation from small to full contact

    Science.gov (United States)

    Yang, Chunyan; Persson, Bo

    2008-03-01

    We report a molecular dynamics study of the contact between a rigid solid with a randomly rough surface and an elastic block with a flat surface. We study the contact area and the interfacial separation from small contact (low load) to full contact (high load). For small load the contact area varies linearly with the load and the interfacial separation depends logarithmically on the load [1-4]. For high load the contact area approaches to the nominal contact area (i.e., complete contact), and the interfacial separation approaches to zero. The present results may be very important for soft solids, e.g., rubber, or for very smooth surfaces, where complete contact can be reached at moderate high loads without plastic deformation of the solids. References: [1] C. Yang and B.N.J. Persson, arXiv:0710.0276, (to appear in Phys. Rev. Lett.) [2] B.N.J. Persson, Phys. Rev. Lett. 99, 125502 (2007) [3] L. Pei, S. Hyun, J.F. Molinari and M.O. Robbins, J. Mech. Phys. Sol. 53, 2385 (2005) [4] M. Benz, K.J. Rosenberg, E.J. Kramer and J.N. Israelachvili, J. Phy. Chem. B.110, 11884 (2006)

  19. Analysis of deep learning methods for blind protein contact prediction in CASP12.

    Science.gov (United States)

    Wang, Sheng; Sun, Siqi; Xu, Jinbo

    2017-08-28

    Here we present the results of protein contact prediction achieved in CASP12 by our RaptorX-Contact server, which is an early implementation of our deep learning method for contact prediction. On a set of 38 free-modeling target domains with a median family size of around 58 effective sequences, our server obtained an average top L/5 long- and medium-range contact accuracy of 47% and 44%, respectively (L = length). A complete implementation has an average accuracy of 59% and 57%, respectively. Our deep learning method formulates contact prediction as a pixel-level image labeling problem and simultaneously predicts all residue pairs of a protein using a combination of two deep residual neural networks, taking as input the residue conservation information, predicted secondary structure and solvent accessibility, contact potential, and coevolution information. Our approach differs from existing methods mainly in (1) formulating contact prediction as a pixel-level image labeling problem instead of an image-level classification problem; (2) simultaneously predicting all contacts of an individual protein to make effective use of contact occurrence patterns; and (3) integrating both one-dimensional and two-dimensional deep convolutional neural networks to effectively learn complex sequence-structure relationship including high-order residue correlation. This paper discusses the RaptorX-Contact pipeline, both contact prediction and contact-based folding results, and finally the strength and weakness of our method. © 2017 Wiley Periodicals, Inc.

  20. Pair Housing of Dairy Calves and Age at Pairing: Effects on Weaning Stress, Health, Production and Social Networks

    Science.gov (United States)

    Mlynski, David T.; James, Richard; Croft, Darren P.

    2017-01-01

    The early social environment can influence the health and behaviour of animals, with effects lasting into adulthood. In Europe, around 60% of dairy calves are reared individually during their first eight weeks of life, while others may be housed in pairs or small groups. This study assessed the effects of varying degrees of social contact on weaning stress, health and production during pen rearing, and on the social networks that calves later formed when grouped. Forty female Holstein-Friesian calves were allocated to one of three treatments: individually housed (I, n = 8), pair-housed from day five (P5, n = 8 pairs), and pair-housed from day 28 (P28, n = 8 pairs). From day 48, calves were weaned by gradual reduction of milk over three days, and vocalisations were recorded as a measure of stress for three days before, during and after weaning. Health and production (growth rate and concentrate intakes) were not affected by treatment during the weaning period or over the whole study. Vocalisations were highest post-weaning, and were significantly higher in I calves than pair-reared calves. Furthermore, P28 calves vocalised significantly more than P5 calves. The social network of calves was measured for one month after all calves were grouped in a barn, using association data from spatial proximity loggers. We tested for week-week stability, social differentiation and assortment in the calf network. Additionally, we tested for treatment differences in: coefficient of variation (CV) in association strength, percentage of time spent with ex-penmate (P5 and P28 calves only) and weighted degree centrality (the sum of the strength of an individual’s associations). The network was relatively stable from weeks one to four and was significantly differentiated, with individuals assorting based on prior familiarity. P5 calves had significantly higher CV in association strength than I calves in week one (indicating more heterogeneous social associations) but there were no

  1. Pair Housing of Dairy Calves and Age at Pairing: Effects on Weaning Stress, Health, Production and Social Networks.

    Science.gov (United States)

    Bolt, Sarah L; Boyland, Natasha K; Mlynski, David T; James, Richard; Croft, Darren P

    2017-01-01

    The early social environment can influence the health and behaviour of animals, with effects lasting into adulthood. In Europe, around 60% of dairy calves are reared individually during their first eight weeks of life, while others may be housed in pairs or small groups. This study assessed the effects of varying degrees of social contact on weaning stress, health and production during pen rearing, and on the social networks that calves later formed when grouped. Forty female Holstein-Friesian calves were allocated to one of three treatments: individually housed (I, n = 8), pair-housed from day five (P5, n = 8 pairs), and pair-housed from day 28 (P28, n = 8 pairs). From day 48, calves were weaned by gradual reduction of milk over three days, and vocalisations were recorded as a measure of stress for three days before, during and after weaning. Health and production (growth rate and concentrate intakes) were not affected by treatment during the weaning period or over the whole study. Vocalisations were highest post-weaning, and were significantly higher in I calves than pair-reared calves. Furthermore, P28 calves vocalised significantly more than P5 calves. The social network of calves was measured for one month after all calves were grouped in a barn, using association data from spatial proximity loggers. We tested for week-week stability, social differentiation and assortment in the calf network. Additionally, we tested for treatment differences in: coefficient of variation (CV) in association strength, percentage of time spent with ex-penmate (P5 and P28 calves only) and weighted degree centrality (the sum of the strength of an individual's associations). The network was relatively stable from weeks one to four and was significantly differentiated, with individuals assorting based on prior familiarity. P5 calves had significantly higher CV in association strength than I calves in week one (indicating more heterogeneous social associations) but there were no

  2. Mechanical Contact Experiments and Simulations

    DEFF Research Database (Denmark)

    Nielsen, Chris Valentin; Martins, P; Zhang, W.;

    2011-01-01

    Mechanical contact is studied under dynamic development by means of a combined numerical and experimental investigation. The experiments are designed to allow dynamical development of non-planar contact areas with significant expansion in all three directions as the load is increased. Different...

  3. Contact modeling for robotics applications

    Energy Technology Data Exchange (ETDEWEB)

    Lafarge, R.A.; Lewis, C.

    1998-08-01

    At Sandia National Laboratories (SNL), the authors are developing the ability to accurately predict motions for arbitrary numbers of bodies of arbitrary shapes experiencing multiple applied forces and intermittent contacts. In particular, the authors are concerned with the simulation of systems such as part feeders or mobile robots operating in realistic environments. Preliminary investigation of commercial dynamics software packages led them to the conclusion that they could use commercial software to provide everything they needed except for the contact model. They found that ADAMS best fit their needs for a simulation package. To simulate intermittent contacts, they need collision detection software that can efficiently compute the distances between non-convex objects and return the associated witness features. They also require a computationally efficient contact model for rapid simulation of impact, sustained contact under load, and transition to and from contact conditions. This paper provides a technical review of a custom hierarchical distance computation engine developed at Sandia, called the C-Space Toolkit (CSTk). In addition, they describe an efficient contact model using a non-linear damping term developed by SNL and Ohio State. Both the CSTk and the non-linear damper have been incorporated in a simplified two-body testbed code, which is used to investigate how to correctly model the contact using these two utilities. They have incorporated this model into the ADAMS software using the callable function interface. An example that illustrates the capabilities of the 9.02 release of ADAMS with their extensions is provided.

  4. The importance of contact quality

    DEFF Research Database (Denmark)

    van Bakel, Marian; Gerritsen, Marinel; van Oudenhoven, Jan Pieter

    Establishing contact between expatriates and a local host has been found to reap benefits with regard to Interaction Adjustment, Host National Social Support, Open-mindedness, and Social Initiative. This longitudinal study examines the role of the quality of contact for these four aspects. Expatr...

  5. Drops, contact lines, and electrowetting

    NARCIS (Netherlands)

    Mannetje, 't D.J.C.M.

    2013-01-01

    In this work, we study the behaviour of drops and contact lines under the influence of electric fields, and how these can answer fundamental and industrial questions. Our focus is on studying the varying balance of the electric field, hysteresis forces and inertia as the speed of a contact line chan

  6. Body contact and body language

    DEFF Research Database (Denmark)

    Winther, Helle Dagmar

    2008-01-01

    Body contact and body language are unique and existential and, although culturally dependent and socially embodied, they are also universal communication forms. For small children all over the world, warm, close and nourishing body contact is fundamental to their embodied experi­ence of themselve...

  7. Fabricating customized hydrogel contact lens

    Science.gov (United States)

    Childs, Andre; Li, Hao; Lewittes, Daniella M.; Dong, Biqin; Liu, Wenzhong; Shu, Xiao; Sun, Cheng; Zhang, Hao F.

    2016-10-01

    Contact lenses are increasingly used in laboratories for in vivo animal retinal imaging and pre-clinical studies. The lens shapes often need modification to optimally fit corneas of individual test subjects. However, the choices from commercially available contact lenses are rather limited. Here, we report a flexible method to fabricate customized hydrogel contact lenses. We showed that the fabricated hydrogel is highly transparent, with refractive indices ranging from 1.42 to 1.45 in the spectra range from 400 nm to 800 nm. The Young’s modulus (1.47 MPa) and hydrophobicity (with a sessile drop contact angle of 40.5°) have also been characterized experimentally. Retinal imaging using optical coherence tomography in rats wearing our customized contact lenses has the quality comparable to the control case without the contact lens. Our method could significantly reduce the cost and the lead time for fabricating soft contact lenses with customized shapes, and benefit the laboratorial-used contact lenses in pre-clinical studies.

  8. Emotional Satisfaction of Customer Contacts

    NARCIS (Netherlands)

    Güngör, Hüseyin

    2007-01-01

    For marketing and customer services researchers and professionals who are interested in customer contacts, customer satisfaction and loyalty issues. Contact centers are playing a pivotal role in customer services of the 21st century. Nevertheless, despite their growing importance and presence, conta

  9. Emotional Satisfaction of Customer Contacts

    NARCIS (Netherlands)

    Güngör, Hüseyin

    2007-01-01

    For marketing and customer services researchers and professionals who are interested in customer contacts, customer satisfaction and loyalty issues. Contact centers are playing a pivotal role in customer services of the 21st century. Nevertheless, despite their growing importance and presence,

  10. Emotional Satisfaction of Customer Contacts

    NARCIS (Netherlands)

    Güngör, Hüseyin

    2007-01-01

    For marketing and customer services researchers and professionals who are interested in customer contacts, customer satisfaction and loyalty issues. Contact centers are playing a pivotal role in customer services of the 21st century. Nevertheless, despite their growing importance and presence, conta

  11. Aluminum break-point contacts

    NARCIS (Netherlands)

    Heinemann, Martina; Groot, R.A. de

    1997-01-01

    Ab initio molecular dynamics is used to study the contribution of a single Al atom to an aluminum breakpoint contact during the final stages of breaking and the initial stages of the formation of such a contact. A hysteresis effect is found in excellent agreement with experiment and the form of the

  12. The identification of physical close galaxy pairs

    CERN Document Server

    Soares, D S L

    2007-01-01

    A classification scheme for close pairs of galaxies is proposed. The scheme is motivated by the fact that the majority of apparent close pairs are in fact wide pairs in three-dimensional space. This is demonstrated by means of numerical simulations of random samples of binary galaxies and the scrutiny of the resulting projected and spatial separation distributions. Observational strategies for classifying close pairs according to the scheme are suggested. As a result, physical -- i.e., bound and spatially -- close pairs are identified.

  13. Pairing correlations and transitions in nuclear systems

    CERN Document Server

    Belic, A; Hjorth-Jensen, M

    2004-01-01

    We discuss several pairing-related phenomena in nuclear systems, ranging from superfluidity in neutron stars to the gradual breaking of pairs in finite nuclei. We describe recent experimental evidence that points to a relation between pairing and phase transitions (or transformations) in finite nuclear systems. A simple pairing interaction model is used in order to study and classify an eventual pairing phase transition in finite fermionic systems such as nuclei. We show that systems with as few as 10-16 fermions can exhibit clear features reminiscent of a phase transition.

  14. A Pair Correlation Function Characterizing the Anisotropy of Force Networks

    Institute of Scientific and Technical Information of China (English)

    SUN Qi-Cheng; JI Shun-Ying

    2011-01-01

    Force networks may underlie the constitutive relations among granular solids and granular flows and inter-state transitions. However, it is difficult to effectively describe the anisotropy of force networks. We propose a new pair correlation Function g(r, 0) to describe the characteristic lengths and orientations of force chains that are composed of particles with contact forces greater than the threshold values. A formulation g(r,0) ? A(r)+b(r) cos 2(0 -n/2) is used to fit the g(r, 0) data. The characteristic lengths and orientations of force networks are then elucidated.%@@ Force networks may underlie the constitutive relations among granular solids and granular flows and inter-state transitions.However, it is difficult to effectively describe the anisotropy of force networks.We propose a new pair correlation function g(r,θ) to describe the characteristic lengths and orientations of force chains that are composed of particles with contact forces greater than the threshold values.A formulation g(r,θ)≈a(r) + b( r ) cos 2(θ-π/2) is used to fit the g(r,θ) data.The characteristic lengths and orientations of force networks are then elucidated.

  15. Rotation is the primary motion of paired human epidermal keratinocytes.

    Science.gov (United States)

    Tate, Sota; Imai, Matome; Matsushita, Natsuki; Nishimura, Emi K; Higashiyama, Shigeki; Nanba, Daisuke

    2015-09-01

    Collective motion of keratinocytes is involved in morphogenesis, homeostasis, and wound healing of the epidermis. Yet how the collective motion of keratinocytes emerges from the behavior of individual cells is still largely unknown. The aim of this study was to find the cellular behavior that links single and collective motion of keratinocytes. We investigated the behavior of two-cell colonies of HaCaT keratinocytes by a combination of time-lapse imaging and image processing. The two-cell colonies of HaCaT cells were formed as a contacted pair of keratinocyte clones. Image analysis and cell culture experiments revealed that the rotational speed of two-cell colonies was positively associated with their proliferative capacity. α6 integrin was required for the rotational motion of two-cell keratinocyte colonies. We also confirmed that two-cell colonies of keratinocytes predominantly exhibited the rotational, but not translational, motion, two modes of motion in a contact pair of rotating objects. The rotational motion is the primary motion of two-cell keratinocyte colonies and its speed is positively associated with their proliferative capacity. This study suggests that the assembly of rotating keratinocytes generates the collective motion of proliferative keratinocytes during morphogenesis and wound healing of the epidermis. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  16. Molecular mechanisms of decomposition of hydrated Na+Cl- ion pairs under planar nanopore conditions

    Science.gov (United States)

    Shevkunov, S. V.

    2017-02-01

    The decomposition of Na+Cl- ion pairs under the conditions of a nanoscopic planar pore with structureless walls in a material contact with water vapor at 298 K is simulated by Monte Carlo method. The transition from the state of a contact ion pair (CIP) to the state of solvent-separated ion pair (SSIP) is shown to occur as a result of an increase in the vapor pressure over a pore after exceeding the threshold number of molecules in a hydrate shell. It is found that the planar form of a molecular cluster under the conditions of a narrow pore does not level an abrupt structural transition and the formation of hydrogen bonds in the hydrate shell starts after three molecules are added. The hydrogen bond length under pore conditions is found to be resistant to variations in the hydrate shell size and coincides with that in water under normal conditions.

  17. Contact dermatitis in military personnel.

    Science.gov (United States)

    Dever, Tara T; Walters, Michelle; Jacob, Sharon

    2011-01-01

    Military personnel encounter the same allergens and irritants as their civilian counterparts and are just as likely to develop contact dermatitis from common exposures encountered in everyday life. In addition, they face some unique exposures that can be difficult to avoid owing to their occupational duties. Contact dermatitis can be detrimental to a military member's career if he or she is unable to perform core duties or avoid the inciting substances. An uncontrolled contact dermatitis can result in the member's being placed on limited-duty (ie, nondeployable) status, needing a job or rate change, or separation from military service. We present some common causes of contact dermatitis in military personnel worldwide and some novel sources of contact dermatitis in this population that may not be intuitive.

  18. Factors affecting home range of mallard pairs

    Energy Technology Data Exchange (ETDEWEB)

    Riechmann, J.H.

    1976-06-01

    Certain habitat and social factors were investigated for their effect on home range size of mallard (Anas platyhynchos) pairs breeding in a forested region of north-central Minnesota during the spring of 1971--72. Data from 31 radio-marked hens and drakes were used, but primary emphasis was placed on 8 pairs (5 with both members of the pair marked). Pairs were radio-tracked on river marsh areas, river channels, and large sand lakes to provide comparative data for evaluating home range size differences. Home ranges varied from an average of 53 ha for pairs using primarily river habitat to 871 ha for pairs using only large sand lakes. River and lake shorelines varied considerably in species and density of vegetation. Interaction between pairs as well as density of flocked males appeared to be influenced by these habitat differences with resultant effects on home range sizes.

  19. On Minus Paired-Domination in Graphs

    Institute of Scientific and Technical Information of China (English)

    邢化明; 孙良

    2003-01-01

    The study of minus paired-domination of a graph G=(V,E) is initiated. Let SV be any paired-dominating set of G, a minus paired-dominating function is a function of the form f∶V→{-1,0,1} such that f(v)=1 for v∈S, f(v)≤0 for v∈V-S, and f(N[v])≥1 for all v∈V. The weight of a minus paired-dominating function f is w(f)=∑f(v), over all vertices v∈V. The minus paired-domination number of a graph G is γ-p(G)=min{w(f)|f is a minus paired-dominating function of G}. On the basis of the minus paired-domination number of a graph G defined, some of its properties are discussed.

  20. Contact Stress Analysis for Gears of Different Helix Angle Using Finite Element Method

    Directory of Open Access Journals (Sweden)

    Patil Santosh

    2014-07-01

    Full Text Available The gear contact stress problem has been a great point of interest for many years, but still an extensive research is required to understand the various parameters affecting this stress. Among such parameters, helix angle is one which has played a crucial role in variation of contact stress. Numerous studies have been carried out on spur gear for contact stress variation. Hence, the present work is an attempt to study the contact stresses among the helical gear pairs, under static conditions, by using a 3D finite element method. The helical gear pairs on which the analysis is carried are 0, 5, 15, 25 degree helical gear sets. The Lagrange multiplier algorithm has been used between the contacting pairs to determine the stresses. The helical gear contact stress is evaluated using FE model and results have also been found at different coefficient of friction, varying from 0.0 to 0.3. The FE results have been further compared with the analytical calculations. The analytical calculations are based upon Hertz and AGMA equations, which are modified to include helix angle. The commercial finite element software was used in the study and it was shown that this approach can be applied to gear design efficiently. The contact stress results have shown a decreasing trend, with increase in helix angle.

  1. Cumulative Paired φ-Entropy

    Directory of Open Access Journals (Sweden)

    Ingo Klein

    2016-07-01

    Full Text Available A new kind of entropy will be introduced which generalizes both the differential entropy and the cumulative (residual entropy. The generalization is twofold. First, we simultaneously define the entropy for cumulative distribution functions (cdfs and survivor functions (sfs, instead of defining it separately for densities, cdfs, or sfs. Secondly, we consider a general “entropy generating function” φ, the same way Burbea et al. (IEEE Trans. Inf. Theory 1982, 28, 489–495 and Liese et al. (Convex Statistical Distances; Teubner-Verlag, 1987 did in the context of φ-divergences. Combining the ideas of φ-entropy and cumulative entropy leads to the new “cumulative paired φ-entropy” ( C P E φ . This new entropy has already been discussed in at least four scientific disciplines, be it with certain modifications or simplifications. In the fuzzy set theory, for example, cumulative paired φ-entropies were defined for membership functions, whereas in uncertainty and reliability theories some variations of C P E φ were recently considered as measures of information. With a single exception, the discussions in the scientific disciplines appear to be held independently of each other. We consider C P E φ for continuous cdfs and show that C P E φ is rather a measure of dispersion than a measure of information. In the first place, this will be demonstrated by deriving an upper bound which is determined by the standard deviation and by solving the maximum entropy problem under the restriction of a fixed variance. Next, this paper specifically shows that C P E φ satisfies the axioms of a dispersion measure. The corresponding dispersion functional can easily be estimated by an L-estimator, containing all its known asymptotic properties. C P E φ is the basis for several related concepts like mutual φ-information, φ-correlation, and φ-regression, which generalize Gini correlation and Gini regression. In addition, linear rank tests for scale that

  2. Predicting loop-helix tertiary structural contacts in RNA pseudoknots.

    Science.gov (United States)

    Cao, Song; Giedroc, David P; Chen, Shi-Jie

    2010-03-01

    Tertiary interactions between loops and helical stems play critical roles in the biological function of many RNA pseudoknots. However, quantitative predictions for RNA tertiary interactions remain elusive. Here we report a statistical mechanical model for the prediction of noncanonical loop-stem base-pairing interactions in RNA pseudoknots. Central to the model is the evaluation of the conformational entropy for the pseudoknotted folds with defined loop-stem tertiary structural contacts. We develop an RNA virtual bond-based conformational model (Vfold model), which permits a rigorous computation of the conformational entropy for a given fold that contains loop-stem tertiary contacts. With the entropy parameters predicted from the Vfold model and the energy parameters for the tertiary contacts as inserted parameters, we can then predict the RNA folding thermodynamics, from which we can extract the tertiary contact thermodynamic parameters from theory-experimental comparisons. These comparisons reveal a contact enthalpy (DeltaH) of -14 kcal/mol and a contact entropy (DeltaS) of -38 cal/mol/K for a protonated C(+)*(G-C) base triple at pH 7.0, and (DeltaH = -7 kcal/mol, DeltaS = -19 cal/mol/K) for an unprotonated base triple. Tests of the model for a series of pseudoknots show good theory-experiment agreement. Based on the extracted energy parameters for the tertiary structural contacts, the model enables predictions for the structure, stability, and folding pathways for RNA pseudoknots with known or postulated loop-stem tertiary contacts from the nucleotide sequence alone.

  3. Optically-Induced Cell Fusion on Cell Pairing Microstructures

    Science.gov (United States)

    Yang, Po-Fu; Wang, Chih-Hung; Lee, Gwo-Bin

    2016-02-01

    Cell fusion is a critical operation for numerous biomedical applications including cell reprogramming, hybridoma formation, cancer immunotherapy, and tissue regeneration. However, unstable cell contact and random cell pairings have limited efficiency and yields when utilizing traditional methods. Furthermore, it is challenging to selectively perform cell fusion within a group of cells. This study reports a new approach called optically-induced cell fusion (OICF), which integrates cell-pairing microstructures with an optically-induced, localized electrical field. By projecting light patterns onto a photoconductive film (hydrogen-rich, amorphous silicon) coated on an indium-tin-oxide (ITO) glass while an alternating current electrical field was applied between two such ITO glass slides, “virtual” electrodes could be generated that could selectively fuse pairing cells. At 10 kHz, a 57% cell paring rate and an 87% fusion efficiency were successfully achieved at a driving voltage of 20  Vpp, suggesting that this new technology could be promising for selective cell fusion within a group of cells.

  4. Pulsational-Pair Instability Supernovae

    CERN Document Server

    Woosley, S E

    2016-01-01

    The final evolution of stars in the mass range 60 - 150 solar masses is explored. Depending upon their mass loss and rotation rates, many of these stars will end their lives as pulsational pair-instability supernovae. Even a non-rotating 70 solar mass star is pulsationally unstable during oxygen shell burning and can power a sub-luminous supernova. Rotation decreases the limit further. For more massive stars, the pulsations are less frequent, span a longer time, and are more powerful. Violent pulsations eject not only any residual low density envelope, but also that fraction of the helium core mass outside about 35 - 50 solar masses. The remaining core of helium and heavy elements continues to evolve, ultimately forming an iron core of about 2.5 solar masses that probably collapses to a black hole. A variety of observational transients result with total durations ranging from days to 10,000 years, and luminosities from 10$^{41}$ to 10$^{44}$ erg s$^{-1}$. Many transients resemble ordinary Type IIp supernovae,...

  5. Report on Pairing-based Cryptography.

    Science.gov (United States)

    Moody, Dustin; Peralta, Rene; Perlner, Ray; Regenscheid, Andrew; Roginsky, Allen; Chen, Lily

    2015-01-01

    This report summarizes study results on pairing-based cryptography. The main purpose of the study is to form NIST's position on standardizing and recommending pairing-based cryptography schemes currently published in research literature and standardized in other standard bodies. The report reviews the mathematical background of pairings. This includes topics such as pairing-friendly elliptic curves and how to compute various pairings. It includes a brief introduction to existing identity-based encryption (IBE) schemes and other cryptographic schemes using pairing technology. The report provides a complete study of the current status of standard activities on pairing-based cryptographic schemes. It explores different application scenarios for pairing-based cryptography schemes. As an important aspect of adopting pairing-based schemes, the report also considers the challenges inherent in validation testing of cryptographic algorithms and modules. Based on the study, the report suggests an approach for including pairing-based cryptography schemes in the NIST cryptographic toolkit. The report also outlines several questions that will require further study if this approach is followed.

  6. Multifocal contact lens myopia control.

    Science.gov (United States)

    Walline, Jeffrey J; Greiner, Katie L; McVey, M Elizabeth; Jones-Jordan, Lisa A

    2013-11-01

    Previous studies on soft multifocal contact lens myopia control published in the peer-reviewed literature reported findings of noncommercial contact lenses worn for 1 year or less. This study sought to determine the progression of myopia and axial elongation of children fitted with commercially available distance center soft multifocal contact lenses for 2 years. Eight- to eleven-year-old children with -1.00 D to -6.00 D spherical component and less than 1.00 D astigmatism were fitted with soft multifocal contact lenses with a +2.00 D add (Proclear Multifocal "D"; CooperVision, Fairport, NY). They were age- and gender-matched to participants from a previous study who were fitted with single-vision contact lenses (1 Day Acuvue; Vistakon, Jacksonville, FL). A-scan ultrasound and cycloplegic autorefraction were performed at baseline, after 1 year, and after 2 years. Multilevel modeling was used to compare the rate of change of myopia and axial length between single-vision and soft multifocal contact lens wearers. Forty participants were fitted with soft multifocal contact lenses, and 13 did not contribute complete data (5 contributed 1 year of data). The adjusted mean ± standard error spherical equivalent progression of myopia at 2 years was -1.03 ± 0.06 D for the single-vision contact lens wearers and -0.51 ± 0.06 for the soft multifocal contact lens wearers (p < 0.0001). The adjusted mean axial elongation was 0.41 ± 0.03 and 0.29 ± 0.03 for the single-vision and soft multifocal contact lens wearers, respectively (p < 0.0016). Soft multifocal contact lens wear resulted in a 50% reduction in the progression of myopia and a 29% reduction in axial elongation during the 2-year treatment period compared to a historical control group. Results from this and other investigations indicate a need for a long-term randomized clinical trial to investigate the potential for soft multifocal contact lens myopia control.

  7. Contact allergy to epoxy resin

    DEFF Research Database (Denmark)

    Bangsgaard, Nannie; Thyssen, Jacob Pontoppidan; Menné, Torkil

    2012-01-01

    . Objectives. To evaluate the prevalence of contact allergy to epoxy resin monomer (diglycidyl ether of bisphenol A; MW 340) among patients with suspected contact dermatitis and relate this to occupation and work-related consequences. Patients/methods. The dataset comprised 20 808 consecutive dermatitis...... in an educational programme. Conclusion. The 1% prevalence of epoxy resin contact allergy is equivalent to reports from other countries. The high occurrence of epoxy resin exposure at work, and the limited use of protective measures, indicate that reinforcement of the law is required....

  8. All-graphene edge contacts

    DEFF Research Database (Denmark)

    Jacobsen, Kåre Wedel; Falkenberg, Jesper Toft; Papior, Nick Rübner;

    2016-01-01

    Using ab-initio methods we investigate the possibility of three-terminalgraphene "T-junction" devices and show that these all-graphene edge contactsare energetically feasible when the 1D interface itself is free from foreignatoms. We examine the energetics of various junction structures...... to be in therange of 1-10 kΩμm which is comparable to the best contact resistance reportedfor edge-contacted graphene-metal contacts. We conclude that conductingall-carbon T-junctions should be feasible....

  9. Ensemble treatments of thermal pairing in nuclei

    Science.gov (United States)

    Hung, Nguyen Quang; Dang, Nguyen Dinh

    2009-10-01

    A systematic comparison is conducted for pairing properties of finite systems at nonzero temperature as predicted by the exact solutions of the pairing problem embedded in three principal statistical ensembles, namely the grandcanonical ensemble, canonical ensemble and microcanonical ensemble, as well as the unprojected (FTBCS1+SCQRPA) and Lipkin-Nogami projected (FTLN1+SCQRPA) theories that include the quasiparticle number fluctuation and coupling to pair vibrations within the self-consistent quasiparticle random-phase approximation. The numerical calculations are performed for the pairing gap, total energy, heat capacity, entropy, and microcanonical temperature within the doubly-folded equidistant multilevel pairing model. The FTLN1+SCQRPA predictions are found to agree best with the exact grand-canonical results. In general, all approaches clearly show that the superfluid-normal phase transition is smoothed out in finite systems. A novel formula is suggested for extracting the empirical pairing gap in reasonable agreement with the exact canonical results.

  10. Filipino au pairs on the move

    DEFF Research Database (Denmark)

    Dalgas, Karina Märcher

    2016-01-01

    Most Filipina au pairs in Denmark send remittances back home, and for many, au pairing forms part of longer-term migration trajectories. This article explores how Filipina au pairs try to carve out a future for themselves abroad. It shows that they navigate within tight webs of financial interdep...... by including the migrants’ broader social network within the frame of research.......Most Filipina au pairs in Denmark send remittances back home, and for many, au pairing forms part of longer-term migration trajectories. This article explores how Filipina au pairs try to carve out a future for themselves abroad. It shows that they navigate within tight webs of financial...... interdependence, whilst they continuously form their trajectories in relation to opportunities and restraints posed along the way by their local and transnational social relations. The article argues that examinations of migration trajectories benefit from broadening the research out in both time and space...

  11. Pair programming in education: a literature review

    Science.gov (United States)

    Hanks, Brian; Fitzgerald, Sue; McCauley, Renée; Murphy, Laurie; Zander, Carol

    2011-06-01

    This article provides a review of educational research literature focused on pair programming in the undergraduate computer science curriculum. Research suggests that the benefits of pair programming include increased success rates in introductory courses, increased retention in the major, higher quality software, higher student confidence in solutions, and improvement in learning outcomes. Moreover, there is some evidence that women, in particular, benefit from pair programming. The literature also provides evidence that the transition from paired to solo programming is easy for students. The greatest challenges for paired students appear to concern scheduling and partner compatibility. This review also considers practical issues such as assigning partners, teaching students to work in pairs, and assessing individual contributions, and concludes with a discussion of open research questions.

  12. Ordered pairing in liquid metallic hydrogen

    Science.gov (United States)

    Carlsson, A. E.; Ashcroft, N. W.

    1983-01-01

    We study two possible types of pairing involving the protons of a proposed low-temperature liquid phase metallic hydrogen. Electron-proton pairing, which can result in an insulating phase, is investigated by using an approximate solution of an Eliashberg-type equation for the anomalous self-energy. A very low estimate of the transition temperature is obtained by including proton correlations in the effective interaction. For proton-proton pairing, we derive a new proton pair potential based on the Abrikosov wave function. This potential includes the electron-proton interaction to all orders and has a much larger well depth than is obtained with linear screening methods. This suggests the possibility of either a superfluid paired phase analogous to that in He-3, or alternatively a phase with true molecular pairing.

  13. Galaxy pairs align with galactic filaments

    CERN Document Server

    Tempel, Elmo

    2015-01-01

    Context. Gravitational collapse theory and numerical simulations suggest that the velocity field within large-scale galaxy filaments is dominated by motions along the filaments. Aims. Our aim is to check whether observational data reveal any preferred orientation of galaxy pairs with respect to the underlying filaments as a result of the expectedly anisotropic velocity field. Methods. We use galaxy pairs and galaxy filaments identified from the Sloan Digital Sky Survey data. For filament extraction, we use the Bisous model that is based the marked point process technique. During the filament detection, we use the centre point of each pair instead of the positions of galaxies to avoid a built-in influence of pair orientation on the filament construction. For pairs lying within filaments (3012 cases), we calculate the angle between the line connecting galaxies of each pair and their host filament. To avoid redshift-space distortions, the angle is measured in the plain of the sky. Results. The alignment analysis...

  14. Multipair approach to pairing in nuclei

    CERN Document Server

    Sambataro, M

    2012-01-01

    The ground state of a general pairing Hamiltonian for a finite nuclear system is constructed as a product of collective, real, distinct pairs. These are determined sequentially via an iterative variational procedure that resorts to diagonalizations of the Hamiltonian in restricted model spaces. Different applications of the method are provided that include comparisons with exact and projected BCS results. The quantities that are examined are correlation energies, occupation numbers and pair transfer matrix elements. In a first application within the picket-fence model, the method is seen to generate the exact ground state for pairing strengths confined in a given range. Further applications of the method concern pairing in spherically symmetric mean fields and include simple exactly solvable models as well as some realistic calculations for middle-shell Sn isotopes. In the latter applications, two different ways of defining the pairs are examined: either with J=0 or with no well-defined angular momentum. The ...

  15. Mathematical models of grinding manufacture and tooth contact analysis of spherical gears

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The spherical gear is a gear-driven mechanism with two degrees of freedom (DOF), which can transfer spatial motion and power. Grinding machining of the spherical gear is performed with a plate grinding wheel by using generating method, and based on mathematical model of the plate grinding wheel, the mathematical model of the spherical gear is set up. And then, the meshing model of a spherical gear pair is developed and the tooth contact analysis (TCA) of the spherical gear pairs is performed. After that, the position of a contact point on teeth surfaces of the spherical gear pair can be solved by using a nonlinear solver. Finally, the paths of contact points on teeth surfaces of the spherical gear are studied: Since every tooth of the spherical gear is diverse, the contact paths of the meshing of the spherical gear pair are complex and multiform. These are very useful to further investigations on transmission theory and practical applications of spherical gear pairs.

  16. Medical management of contact dermatitis.

    Science.gov (United States)

    Alexandroff, A B; Johnston, G A

    2009-10-01

    Allergic and irritant contact dermatitis are important dermatological problems. Although the frequencies of positive reactions to a number of allergens have decreased during last 30 years because of better avoidance (and at least in part due to improved legislation), contact allergy to other agents is rising. The medical treatment starts from a correct identification of triggers of contact dermatitis which could allow patients to reduce or avoid exposure to these agents in future. A good clinical history, examination and immunological tests including patch testing are of crucial importance at this stage. Further management includes emollients, topical and oral corticosteroids, topical calcineurin inhibitors, azathioprine and ciclosporin. Methotrexate and alitretinoin are recent additions to the armamentarium of dermatologists who manage contact dermatitis.

  17. Scalable algorithms for contact problems

    CERN Document Server

    Dostál, Zdeněk; Sadowská, Marie; Vondrák, Vít

    2016-01-01

    This book presents a comprehensive and self-contained treatment of the authors’ newly developed scalable algorithms for the solutions of multibody contact problems of linear elasticity. The brand new feature of these algorithms is theoretically supported numerical scalability and parallel scalability demonstrated on problems discretized by billions of degrees of freedom. The theory supports solving multibody frictionless contact problems, contact problems with possibly orthotropic Tresca’s friction, and transient contact problems. It covers BEM discretization, jumping coefficients, floating bodies, mortar non-penetration conditions, etc. The exposition is divided into four parts, the first of which reviews appropriate facets of linear algebra, optimization, and analysis. The most important algorithms and optimality results are presented in the third part of the volume. The presentation is complete, including continuous formulation, discretization, decomposition, optimality results, and numerical experimen...

  18. Occupational contact dermatitis in hairdressers

    DEFF Research Database (Denmark)

    Schwensen, Jakob F; Johansen, Jeanne Duus; Veien, Niels K

    2013-01-01

    BACKGROUND: Occupational contact dermatitis among hairdressers is frequent, owing to daily exposure to irritants and allergens. OBJECTIVES: To identify sensitization to the most common allergens associated with the occupation of hairdressing. METHODS: Patch test results of 399 hairdressers and 19...

  19. Dendritic cells and contact dermatitis.

    Science.gov (United States)

    Sasaki, Yoshinori; Aiba, Setsuya

    2007-10-01

    Contact dermatitis is a biological response to simple chemicals in the skin. Although it is well known that allergic contact dermatitis is mediated by the immune system, it is still uncertain whether it is a kind of protective response or it is simply an unnecessary response. We have demonstrated the following: (1) haptens activate Langerhans cells in the initiation phase of murine allergic contact dermatitis in vivo, (2) haptens activate human monocyte-derived dendritic cells in vitro, (3) the activation of dendritic cells by haptens is primarily mediated by the activation of p38 mitogen-activated protein kinase (MAPK), and (4) the activation of p38 MAPK is mediated by stimulation related to an imbalance of intracellular redox. Based on these observations, we will discuss the biological significance of contact dermatitis. In addition, we will review some up-to-date findings on Langerhans cell biology.

  20. Contact vitiligo: etiology and treatment

    Directory of Open Access Journals (Sweden)

    Singh P

    2003-01-01

    Full Text Available Fifty patients of contact vitiligo were studied. EtiologicaI agents of contact vitiligo were identified by clinical history, distribution of lesions and patch testing with suspected material. All patients were advised to avoid the suspected agent and treated with PUVASOL and topical steroid. Out of 50 patients (Male 8%, Female 92% age 14-60 years., etiological agent of contact vitiligo was found to be sticking bindi alone in 24 (48%, while bindi along with other etiological agents were found to be purse, foot wear, plastic watch strap, lipstick and tooth paste in 14 ( 28% cases. 14 (28% patients also had disseminated lesions of vitiligo along with contact vitiligo. Positive reaction with patch testing was observed in 18 (36% while depigmentation was seen in 4 ( 8% cases. We observed that response of treatment was better in patients with shorter duration of disease while poor response was seen in patients with longer duration of disease.

  1. The geometry of surfaces contact

    Directory of Open Access Journals (Sweden)

    Siegl J.

    2007-11-01

    Full Text Available This contribution deals with a geometrical exact description of contact between two given surfaces which are defined by the vector functions. These surfaces are substituted at a contact point by approximate surfaces of the second order in accordance with the Taylor series and consequently there is derived a differential surface of these second order surfaces. Knowledge of principal normal curvatures, their directions and the tensor (Dupin indicatrix of this differential surface are necessary for description of contact of these surfaces. For description of surface geometry the first and the second surface fundamental tensor and a further methods of the differential geometry are used. A geometrical visualisation of obtained results of this analysis is made. Method and results of this study will be applied to contact analysis of tooth screw surfaces of screw machines.

  2. Nordic project food contact materials

    DEFF Research Database (Denmark)

    Li, Ågot; Tesdal Håland, Julie; Petersen, Jens Højslev

    countries have had a limited focus on the FCM area with the exception of Denmark and Finland. The aim of the project was therefore to control establishments producing, importing or using plastic food contact materials as well as to increase the knowledge of the inspectors performing these controls......Denmark, Finland, Faroe Islands, Iceland, Norway and Sweden have in 2013––2015 conducted a Nordic project on food contact materials. Food contact materials are used in all stages of food production and can be a general source of contamination. The food safety authorities in most of the Nordic....... The focus of the inspections was to control the declaration of compliance (DoC) for plastic food contact materials. The requirement for a Doc is mandatory in order to ensure that the FCM complies with the legislation. In addition some products were analyzed for phthalates....

  3. Transition metal contacts to graphene

    Energy Technology Data Exchange (ETDEWEB)

    Politou, Maria, E-mail: Maria.Politou@imec.be; De Gendt, Stefan; Heyns, Marc [KU Leuven, 3001 Leuven (Belgium); imec, Kapeldreef 75, 3001 Leuven (Belgium); Asselberghs, Inge; Radu, Iuliana; Conard, Thierry; Richard, Olivier; Martens, Koen; Huyghebaert, Cedric; Tokei, Zsolt [imec, Kapeldreef 75, 3001 Leuven (Belgium); Lee, Chang Seung [SAIT, Samsung Electronics Co., Suwon 443-803 (Korea, Republic of); Sayan, Safak [imec, Kapeldreef 75, 3001 Leuven (Belgium); Intel Corporation, 2200 Mission College Blvd, Santa Clara, California 95054 (United States)

    2015-10-12

    Achieving low resistance contacts to graphene is a common concern for graphene device performance and hybrid graphene/metal interconnects. In this work, we have used the circular Transfer Length Method (cTLM) to electrically characterize Ag, Au, Ni, Ti, and Pd as contact metals to graphene. The consistency of the obtained results was verified with the characterization of up to 72 cTLM structures per metal. Within our study, the noble metals Au, Ag and Pd, which form a weaker bond with graphene, are shown to result in lower contact resistance (Rc) values compared to the more reactive Ni and Ti. X-ray Photo Electron Spectroscopy and Transmission Electron Microscopy characterization for the latter have shown the formation of Ti and Ni carbides. Graphene/Pd contacts show a distinct intermediate behavior. The weak carbide formation signature and the low Rc values measured agree with theoretical predictions of an intermediate state of weak chemisorption of Pd on graphene.

  4. An Entropic Approach for Pair Trading

    Directory of Open Access Journals (Sweden)

    Daisuke Yoshikawa

    2017-06-01

    Full Text Available In this paper, we derive the optimal boundary for pair trading. This boundary defines the points of entry into or exit from the market for a given stock pair. However, if the assumed model contains uncertainty, the resulting boundary could result in large losses. To avoid this, we develop a more robust strategy by accounting for the model uncertainty. To incorporate the model uncertainty, we use the relative entropy as a penalty function in the expected profit from pair trading.

  5. Top pair production distributions at the Tevatron

    Directory of Open Access Journals (Sweden)

    Takeuchi Yuji

    2013-05-01

    Full Text Available At the Tevatron, the top quark is mainly produced in pairs through the strong interaction and decays before forming hadrons. Thus the kinematical distributions at top pair production possess rich information on the tt¯$tar t$ production vertex including polarizations of top and anti-top quarks. In this article, recent measurements on top quark pair production distributions at Tevatron (CDF and DO are presented.

  6. An Entropic Approach for Pair Trading

    OpenAIRE

    Daisuke Yoshikawa

    2017-01-01

    In this paper, we derive the optimal boundary for pair trading. This boundary defines the points of entry into or exit from the market for a given stock pair. However, if the assumed model contains uncertainty, the resulting boundary could result in large losses. To avoid this, we develop a more robust strategy by accounting for the model uncertainty. To incorporate the model uncertainty, we use the relative entropy as a penalty function in the expected profit from pair trading.

  7. Embodied Archives as Contact Zones

    Directory of Open Access Journals (Sweden)

    Judit Vidiella

    2015-02-01

    Full Text Available This article proposes a reflection about affective politics from locating some theoretical and conceptual genealogies like «emotion», «affection», «zones of contact»…, that understand them as action and force fields. These contributions allow us to rethink the relation of affects with politics and strategies of archive linked to performance, and understood as zones of friction, collision, circulation and contact: performative writing, repertoire, memes…

  8. Metal semiconductor contacts and devices

    CERN Document Server

    Cohen, Simon S; Einspruch, Norman G

    1986-01-01

    VLSI Electronics Microstructure Science, Volume 13: Metal-Semiconductor Contacts and Devices presents the physics, technology, and applications of metal-semiconductor barriers in digital integrated circuits. The emphasis is placed on the interplay among the theory, processing, and characterization techniques in the development of practical metal-semiconductor contacts and devices.This volume contains chapters that are devoted to the discussion of the physics of metal-semiconductor interfaces and its basic phenomena; fabrication procedures; and interface characterization techniques, particularl

  9. Contact process in a wedge

    CERN Document Server

    Cox, J Theodore; Schinazi, Rinaldo B

    2009-01-01

    We prove that the supercritical one-dimensional contact process survives in certain wedge-like space-time regions, and that when it survives it couples with the unrestricted contact process started from its upper invariant measure. As an application we show that a type of weak coexistence is possible in the nearest-neighbor ``grass-bushes-trees'' successional model introduced in Durrett and Swindle (1991).

  10. Contact dermatitis to botanical extracts.

    Science.gov (United States)

    Kiken, David A; Cohen, David E

    2002-09-01

    A review of the literature of reported cases of contact dermatitis to a variety of natural herbal extracts is Presented. Natural extracts are commonly used ingredients in many cosmetic preparations and homeopathic remedies. Although the term natural botanical extracts inherently purports to have beneficial and benign properties, these extracts can cause adverse reactions in individuals. As such, dermatologists should be cognizant of these agents as possible sources of allergenicity in patients presenting with contact dermatitis.

  11. Pairing preferences of the model mono-valence mono-atomic ions investigated by molecular simulation.

    Science.gov (United States)

    Zhang, Qiang; Zhang, Ruiting; Zhao, Ying; Li, HuanHuan; Gao, Yi Qin; Zhuang, Wei

    2014-05-14

    We carried out a series of potential of mean force calculations to study the pairing preferences of a series of model mono-atomic 1:1 ions with evenly varied sizes. The probabilities of forming the contact ion pair (CIP) and the single water separate ion pair (SIP) were presented in the two-dimensional plots with respect to the ion sizes. The pairing preferences reflected in these plots largely agree with the empirical rule of matching ion sizes in the small and big size regions. In the region that the ion sizes are close to the size of the water molecule; however, a significant deviation from this conventional rule is observed. Our further analysis indicated that this deviation originates from the competition between CIP and the water bridging SIP state. The competition is mainly an enthalpy modulated phenomenon in which the existing of the water bridging plays a significant role.

  12. Dual origin of pairing in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Idini, A. [University of Jyvaskyla, Department of Physics (Finland); Potel, G. [Michigan State University, National Superconducting Cyclotron Laboratory (United States); Barranco, F. [Escuela Superior de Ingenieros, Universidad de Sevilla, Departamento de Fìsica Aplicada III (Spain); Vigezzi, E., E-mail: enrico.vigezzi@mi.infn.it [INFN Sezione di Milano (Italy); Broglia, R. A. [Università di Milano, Dipartimento di Fisica (Italy)

    2016-11-15

    The pairing correlations of the nucleus {sup 120}Sn are calculated by solving the Nambu–Gor’kov equations, including medium polarization effects resulting from the interweaving of quasiparticles, spin and density vibrations, taking into account, within the framework of nuclear field theory (NFT), processes leading to self-energy and vertex corrections and to the induced pairing interaction. From these results one can not only demonstrate the inevitability of the dual origin of pairing in nuclei, but also extract information which can be used at profit to quantitatively disentangle the contributions to the pairing gap Δ arising from the bare and from the induced pairing interaction. The first is the strong {sup 1}S{sub 0} short-range NN potential resulting from meson exchange between nucleons moving in time reversal states within an energy range of hundreds of MeV from the Fermi energy. The second results from the exchange of vibrational modes between nucleons moving within few MeV from the Fermi energy. Short- (v{sub p}{sup bare}) and long-range (v{sub p}{sup ind}) pairing interactions contribute essentially equally to nuclear Cooper pair stability. That is to the breaking of gauge invariance in open-shell superfluid nuclei and thus to the order parameter, namely to the ground state expectation value of the pair creation operator. In other words, to the emergent property of generalized rigidity in gauge space, and associated rotational bands and Cooper pair tunneling between members of these bands.

  13. Lax pairs for deformed Minkowski spacetimes

    CERN Document Server

    Kyono, Hideki; Yoshida, Kentaroh

    2015-01-01

    We proceed to study Yang-Baxter deformations of 4D Minkowski spacetime based on a conformal embedding. We first revisit a Melvin background and argue a Lax pair by adopting a simple replacement law invented in 1509.00173. This argument enables us to deduce a general expression of Lax pair. Then the anticipated Lax pair is shown to work for arbitrary classical $r$-matrices with Poinca\\'e generators. As other examples, we present Lax pairs for pp-wave backgrounds, the Hashimoto-Sethi background, the Spradlin-Takayanagi-Volovich background.

  14. Lax pairs for deformed Minkowski spacetimes

    Energy Technology Data Exchange (ETDEWEB)

    Kyono, Hideki; Sakamoto, Jun-ichi; Yoshida, Kentaroh [Department of Physics, Kyoto University,Kitashirakawa Oiwake-cho, Kyoto 606-8502 (Japan)

    2016-01-25

    We proceed to study Yang-Baxter deformations of 4D Minkowski spacetime based on a conformal embedding. We first revisit a Melvin background and argue a Lax pair by adopting a simple replacement law invented in 1509.00173. This argument enables us to deduce a general expression of Lax pair. Then the anticipated Lax pair is shown to work for arbitrary classical r-matrices with Poincaré generators. As other examples, we present Lax pairs for pp-wave backgrounds, the Hashimoto-Sethi background, the Spradlin-Takayanagi-Volovich background.

  15. Transrelativistic pair plasmas in AGN jets

    DEFF Research Database (Denmark)

    Bottcher, M.; Pohl, M.; Schlickeiser, R.

    1999-01-01

    Models of relativistic jets filled with ultrarelativistic pair plasma are very successful in explaining the broadband radiation of gamma-ray blazars. Assuming that the initial injection and cooling of ultrarelativistic pair plasma in an AGN jet has occurred, producing the observed high-energy gamma......-ray radiation, we investigate the further evolution of the pair plasma as it continues to move out from the central engine. The effects of thermalization and reacceleration, the emission of pair bremsstrahlung and annihilation radiation and the bulk Compton process, and the possible application to MeV blazars...

  16. COTORSION PAIRS OVER FINITE GROUP GRADED RINGS

    Institute of Scientific and Technical Information of China (English)

    MENG Fan-yun; SUN Ju-xiang

    2015-01-01

    In this paper, we study the relation of cotorsion pairs between the graded and ungraded cases. By using the graded theory and the relative homological algebra, we first consider the relationship of cotorsion pairs in R-mod and S = R∗G-mod when R is any ring and G is a finite group. Then we study rigid cotorsion pairs in R-gr and consider the relationship of cotorsion pairs between R-gr and R-mod when R is a ring graded by a finite group G with|G|−1 ∈R.

  17. Measuring the rate of intramolecular contact formation in polypeptides

    Science.gov (United States)

    Lapidus, Lisa; Eaton, William; Hofrichter, James

    2001-03-01

    Formation of a specific contact between two residues of a polypeptide chain is an important elementary process in protein folding. Here we describe a method for studying contact formation between tryptophan and cysteine based on measurements of the lifetime of the tryptophan triplet state. With tryptophan at one end of a flexible peptide and cysteine at the other, the triplet decay rate is identical to the rate of quenching by cysteine and is also close to the diffusion-limited rate of contact formation. The length dependence of this end-to-end contact rate was studied in a series of Cys-(Ala-Gly-Gln)_k-Trp peptides, with k varying from 1 to 6. The rate decreases from -1/(40 ns) for k = 1 to -1/(140 ns) for k = 6, approaching the length-dependence expected for a random coil (n-3/2) for the longest peptides. Comparing the intramolecular and bimolecular quenching rates for cysteine with two disulfide molecules (cystine and lipoate) determines the ratio of the equilibrium constants for forming the intramolecular and bimolecular contact pairs. This ratio depends on the persistence length of the chain and is therefore a measure of the flexibility of the polypeptide.

  18. Video Conference System that Keeps Mutual Eye Contact Among Participants

    Directory of Open Access Journals (Sweden)

    Masahiko Yahagi

    2011-10-01

    Full Text Available A novel video conference system is developed. Suppose that three people A, B, and C attend the video conference, the proposed system enables eye contact among every pair. Furthermore, when B and C chat, A feels as if B and C were facing each other (eye contact seems to be kept among B and C. In the case of a triangle video conference, the respective video system is composed of a half mirror, two video cameras, and two monitors. Each participant watches other participants' images that are reflected by the half mirror. Cameras are set behind the half mirror. Since participants' image (face and the camera position are adjusted to be the same direction, eye contact is kept and conversation becomes very natural compared with conventional video conference systems where participants' eyes do not point to the other participant. When 3 participants sit at the vertex of an equilateral triangle, eyes can be kept even for the situation mentioned above (eye contact between B and C from the aspect of A. Eye contact can be kept not only for 2 or 3 participants but also any number of participants as far as they sit at the vertex of a regular polygon.

  19. INVESTIGATION OF HIGH-CURRENT INTERRUPTING CONTACTS WORKING SURFACES MECHANICAL INTERACTION NATURE

    Directory of Open Access Journals (Sweden)

    O.G. Volkova

    2016-03-01

    Full Text Available Introduction. The nature of the interaction of high-working surfaces of the electrical contact uniquely affects their performance. By the failure of the contacts in the main drive processes resulting from complex destructive factors affecting their performance. However, not all processes are studied in detail and give in modeling. The purpose of the paper is to show the possibility of using the method of holographic interferometry to estimate the plastic deformation in the zone of contact interaction. One of the significant factors affecting the work of the contact pair is the compressive force of the contact surfaces. Compression discontinuous contact is directly connected with the processes of elastic and plastic deformation of the contact material, which is particularly evident in the contact details of the powder or composite materials. The paper focuses on the plastic deformation of the surface layers of discontinuous contact in circuit, it is believed that it is directly related to the mechanism of conductivity of contacts. As shown, a significant effect on the deformation of the contact surfaces and renders the working environment, in particular transformer oil. Methodology. Assessing the impact of compression forces on the deformation of the contact surface was conducted experimentally using the method of holographic interferometry. Results. Experimental studies, which indicated that the compact and powder materials plastic deformation in and around the area microcontacts simplistically stated that requires experimental verification. A method for evaluating the state of stress, which affects the formation and destruction of the local contact spots. Practical value. Using the experimental method of determining the movement of the contact region allows you to optimize discontinuous contacts from composite and powder materials.

  20. Measuring The Contact Resistances Of Photovoltaic Cells

    Science.gov (United States)

    Burger, D. R.

    1985-01-01

    Simple method devised to measure contact resistances of photovoltaic solar cells. Method uses readily available equipment and applicable at any time during life of cell. Enables evaluation of cell contact resistance, contact-end resistance, contact resistivity, sheet resistivity, and sheet resistivity under contact.

  1. RF Sputtering of Gold Contacts On Niobium

    Science.gov (United States)

    Barr, D. W.

    1983-01-01

    Reliable gold contacts are deposited on niobium by combination of RF sputtering and photolithography. Process results in structures having gold only where desired for electrical contact. Contacts are stable under repeated cycling from room temperature to 4.2 K and show room-temperature contact resistance as much as 40 percent below indium contacts made by thermalcompression bonding.

  2. Solar cell with back side contacts

    Energy Technology Data Exchange (ETDEWEB)

    Nielson, Gregory N; Okandan, Murat; Cruz-Campa, Jose Luis; Resnick, Paul J; Wanlass, Mark Woodbury; Clews, Peggy J

    2013-12-24

    A III-V solar cell is described herein that includes all back side contacts. Additionally, the positive and negative electrical contacts contact compoud semiconductor layers of the solar cell other than the absorbing layer of the solar cell. That is, the positive and negative electrical contacts contact passivating layers of the solar cell.

  3. Solar cell with back side contacts

    Science.gov (United States)

    Nielson, Gregory N; Okandan, Murat; Cruz-Campa, Jose Luis; Resnick, Paul J; Wanlass, Mark Woodbury; Clews, Peggy J

    2013-12-24

    A III-V solar cell is described herein that includes all back side contacts. Additionally, the positive and negative electrical contacts contact compoud semiconductor layers of the solar cell other than the absorbing layer of the solar cell. That is, the positive and negative electrical contacts contact passivating layers of the solar cell.

  4. Social behavior of young dairy calves housed with limited or full social contact with a peer

    DEFF Research Database (Denmark)

    Duve, Linda Rosager; Jensen, Margit Bak

    2012-01-01

    This study compared the effect of individual and pair housing and age at pair housing on the social behavior of young dairy calves. Twenty-seven pairs of calves were reared from birth until 6 wk either individually (limited social contact between bars; L calves), in pairs (full social contact; F......, and 34 (age of the youngest calf in a pair) and from the group pens on d 44 and 49 (age of the youngest calf in the group). Behavioral recordings were performed using instantaneous recording at 5-min intervals on d 2, 22, and 34 over 16h to investigate overall activity and social activity of the pairs...... sniffing and licking another calf more than were the L calves. No difference was found in duration of lying down in body contact with another calf between F and LF calves on d 22; however, on d 34, LF calves performed more of this behavior than did F calves. Continuous recordings of social behavior were...

  5. Ferromagnetic tunnel contacts to graphene: Contact resistance and spin signal

    Energy Technology Data Exchange (ETDEWEB)

    Cubukcu, M.; Laczkowski, P.; Vergnaud, C.; Marty, A.; Attané, J.-P.; Notin, L.; Vila, L., E-mail: laurent.vila@cea.fr; Jamet, M. [University Grenoble Alpes, CEA, INAC-SP2M, F-38054 Grenoble (France); Martin, M.-B.; Seneor, P.; Anane, A.; Deranlot, C.; Fert, A. [Unité Mixte de Physique CNRS-Thales, F-91767 Palaiseau (France); Auffret, S. [University Grenoble Alpes, CNRS, CEA, INAC-SPINTEC, Grenoble F-38054 (France); Ducruet, C. [Crocus Technology, 4 place Robert Schuman, 38000 Grenoble (France)

    2015-02-28

    We report spin transport in CVD graphene-based lateral spin valves using different magnetic contacts. We compared the spin signal amplitude measured on devices where the cobalt layer is directly in contact with the graphene to the one obtained using tunnel contacts. Although a sizeable spin signal (up to ∼2 Ω) is obtained with direct contacts, the signal is strongly enhanced (∼400 Ω) by inserting a tunnel barrier. In addition, we studied the resistance-area product (R.A) of a variety of contacts on CVD graphene. In particular, we compared the R.A products of alumina and magnesium oxide tunnel barriers grown by sputtering deposition of aluminum or magnesium and subsequent natural oxidation under pure oxygen atmosphere or by plasma. When using an alumina tunnel barrier on CVD graphene, the R.A product is high and exhibits a large dispersion. This dispersion can be highly reduced by using a magnesium oxide tunnel barrier, as for the R.A value. This study gives insight in the material quest for reproducible and efficient spin injection in CVD graphene.

  6. Rigid supersymmetry on 5-dimensional Riemannian manifolds and contact geometry

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Yiwen [C.N. Yang Institute for Theoretical Physics,Stony Brook, NY, 11790 (United States)

    2014-05-12

    In this note we generalize the methods of http://dx.doi.org/10.1007/JHEP08(2012)141, http://dx.doi.org/10.1007/JHEP01(2013)072 and http://dx.doi.org/10.1007/JHEP05(2013)017 to 5-dimensional Riemannian manifolds M. We study the relations between the geometry of M and the number of solutions to a generalized Killing spinor equation obtained from a 5-dimensional supergravity. The existence of 1 pair of solutions is related to almost contact metric structures. We also discuss special cases related to M=S{sup 1}×M{sub 4}, which leads to M being foliated by submanifolds with special properties, such as Quaternion-Kähler. When there are 2 pairs of solutions, the closure of the isometry sub-algebra generated by the solutions requires M to be S{sup 3} or T{sup 3}-fibration over a Riemann surface. 4 pairs of solutions pin down the geometry of M to very few possibilities. Finally, we propose a new supersymmetric theory for N=1 vector multiplet on K-contact manifold admitting solutions to the Killing spinor equation.

  7. Fatigue resistant carbon coatings for rolling/sliding contacts

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Harpal; Ramirez, Giovanni; Eryilmaz, Osman; Greco, Aaron; Doll, Gary; Erdemir, Ali

    2016-06-01

    The growing demands for renewable energy production have recently resulted in a significant increase in wind plant installation. Field data from these plants show that wind turbines suffer from costly repair, maintenance and high failure rates. Often times the reliability issues are linked with tribological components used in wind turbine drivetrains. The primary failure modes in bearings and gears are associated with micropitting, wear, brinelling, scuffing, smearing and macropitting all of which occur at or near the surface. Accordingly, a variety of surface engineering approaches are currently being considered to alter the near surface properties of such bearings and gears to prevent these tribological failures. In the present work, we have evaluated the tribological performance of compliant highly hydrogenated diamond like carbon coating developed at Argonne National Laboratory, under mixed rolling/sliding contact conditions for wind turbine drivetrain components. The coating was deposited on AISI 52100 steel specimens using a magnetron sputter deposition system. The experiments were performed on a PCS Micro-Pitting-Rig (MPR) with four material pairs at 1.79 GPa contact stress, 40% slide to roll ratio and in polyalphaolefin (PAO4) basestock oil (to ensure extreme boundary conditions). The post-test analysis was performed using optical microscopy, surface profilometry, and Raman spectroscopy. The results obtained show a potential for these coatings in sliding/rolling contact applications as no failures were observed with coated specimens even after 100 million cycles compared to uncoated pair in which they failed after 32 million cycles, under the given test conditions.

  8. Tunnel conductance of Watson-Crick nucleoside-base pairs from telegraph noise

    Energy Technology Data Exchange (ETDEWEB)

    Chang Shuai; He Jin; Lin Lisha; Zhang Peiming; Liang Feng; Huang Shuo; Lindsay, Stuart [Biodesign Institute, Arizona State University, Tempe, AZ 85287 (United States); Young, Michael [Department of Physics, Arizona State University, Tempe, AZ 85287 (United States)], E-mail: Stuart.Lindsay@asu.edu

    2009-05-06

    The use of tunneling signals to sequence DNA is presently hampered by the small tunnel conductance of a junction spanning an entire DNA molecule. The design of a readout system that uses a shorter tunneling path requires knowledge of the absolute conductance across base pairs. We have exploited the stochastic switching of hydrogen-bonded DNA base-nucleoside pairs trapped in a tunnel junction to determine the conductance of individual molecular pairs. This conductance is found to be sensitive to the geometry of the junction, but a subset of the data appears to come from unstrained molecular pairs. The conductances determined from these pairs are within a factor of two of the predictions of density functional calculations. The experimental data reproduces the counterintuitive theoretical prediction that guanine-deoxycytidine pairs (3 H-bonds) have a smaller conductance than adenine-thymine pairs (2 H-bonds). A bimodal distribution of switching lifetimes shows that both H-bonds and molecule-metal contacts break.

  9. Open string pair creation from worldsheet instantons

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, Christian [Max-Planck-Institut fuer Gravitationsphysik, Albert-Einstein-Institut, Muehlenberg 1, D-14476 Potsdam (Germany); Torrielli, Alessandro [Institute for Theoretical Physics and Spinoza Institute, Utrecht University, Leuvenlaan 4, 3584 CE Utrecht (Netherlands)

    2010-10-08

    Worldline instantons provide a particularly elegant way to derive Schwinger's well-known formula for the pair creation rate due to a constant electric field in quantum electrodynamics. In this communication, we show how to extend this method to the corresponding problem of open string pair creation. (fast track communication)

  10. Exploring Pair Programming Benefits for MIS Majors

    Science.gov (United States)

    Dongo, Tendai; Reed, April H.; O'Hara, Margaret

    2016-01-01

    Pair programming is a collaborative programming practice that places participants in dyads, working in tandem at one computer to complete programming assignments. Pair programming studies with Computer Science (CS) and Software Engineering (SE) majors have identified benefits such as technical productivity, program/design quality, academic…

  11. Prime pairs and the zeta function

    NARCIS (Netherlands)

    Korevaar, J.

    2009-01-01

    Are there infinitely many prime pairs with given even difference? Most mathematicians think so. Using a strong arithmetic hypothesis, Goldston, Pintz and Yildirim have recently shown that there are infinitely many pairs of primes differing by at most sixteen. There is extensive numerical support for

  12. Bidirectional Synonym Ratings of 464 Noun Pairs.

    Science.gov (United States)

    Whitten, William B.; And Others

    1979-01-01

    Each of 464 noun pairs was rated for synonymy on a seven-point scale by college students to provide an extensive set of synonym pairs for use as stimuli in experiments, and to evaluate the effects of word encoding order on perceived synonymy. (SW)

  13. Kinetic energy driven pairing in cuprate superconductors

    NARCIS (Netherlands)

    Maier, TA; Jarrell, M; Macridin, A; Slezak, C

    2004-01-01

    Pairing occurs in conventional superconductors through a reduction of the electronic potential energy accompanied by an increase in kinetic energy. In the underdoped cuprates, optical experiments show that pairing is driven by a reduction of the electronic kinetic energy. Using the dynamical cluster

  14. Exploring Pair Programming Benefits for MIS Majors

    Science.gov (United States)

    Dongo, Tendai; Reed, April H.; O'Hara, Margaret

    2016-01-01

    Pair programming is a collaborative programming practice that places participants in dyads, working in tandem at one computer to complete programming assignments. Pair programming studies with Computer Science (CS) and Software Engineering (SE) majors have identified benefits such as technical productivity, program/design quality, academic…

  15. Prime pairs and the zeta function

    NARCIS (Netherlands)

    Korevaar, J.

    2009-01-01

    Are there infinitely many prime pairs with given even difference? Most mathematicians think so. Using a strong arithmetic hypothesis, Goldston, Pintz and Yildirim have recently shown that there are infinitely many pairs of primes differing by at most sixteen. There is extensive numerical support for

  16. Optimal scaling of paired comparison data

    NARCIS (Netherlands)

    van de Velden, M.

    2004-01-01

    In this paper we consider the analysis of paired comparisons using optimal scaling techniques. In particular, we will, inspired by Guttman's approach for quantifying paired comparisons, formulate a new method to obtain optimal scaling values for the subjects. We will compare our results with those o

  17. THE INVESTIGATION OF CONTACT RESISTANCE CHARACTERISTICS ON ELECTRICAL CONTACTS USED IN COAL MINES

    Institute of Scientific and Technical Information of China (English)

    郭凤仪; 王其平; 孙鹤旭; 乔和; 张静

    1997-01-01

    Based on the electrical contact and arc theory, the experiments on contact resistance characteristics of electrical contacts are carried out, by analyzing the experimental results, some conclusions of contact resistance characteristics have been obtained in this paper.

  18. Muon pair production in relativistic nuclear collisions

    CERN Document Server

    Hencken, K; Serbo, V G

    2006-01-01

    The exclusive production of one $\\mu^+\\mu^-$ pair in collisions of two ultra-relativistic nuclei is considered. We present the simple method for calculation of the Born cross section for this process. Then we found that the Coulomb corrections to this cross section (which correspond to multi-photon exchange of the produced $\\mu^{\\pm}$ with nuclei) are small while the unitarity corrections are large. This is in sharp contrast to the exclusive $e^+e^-$ pair production where the Coulomb corrections to the Born cross section are large while the unitarity corrections are small. We calculated also the cross section for the production of one $\\mu^+\\mu^-$ pair and several $e^+e^-$ pairs in the leading logarithmic approximation. Using this cross section we found that the inclusive production of $\\mu^+\\mu^-$ pair coincides in this approximation with its Born value.

  19. Pairing in a dry Fermi sea.

    Science.gov (United States)

    Maier, T A; Staar, P; Mishra, V; Chatterjee, U; Campuzano, J C; Scalapino, D J

    2016-06-17

    In the traditional Bardeen-Cooper-Schrieffer theory of superconductivity, the amplitude for the propagation of a pair of electrons with momentum k and -k has a log singularity as the temperature decreases. This so-called Cooper instability arises from the presence of an electron Fermi sea. It means that an attractive interaction, no matter how weak, will eventually lead to a pairing instability. However, in the pseudogap regime of the cuprate superconductors, where parts of the Fermi surface are destroyed, this log singularity is suppressed, raising the question of how pairing occurs in the absence of a Fermi sea. Here we report Hubbard model numerical results and the analysis of angular-resolved photoemission experiments on a cuprate superconductor. In contrast to the traditional theory, we find that in the pseudogap regime the pairing instability arises from an increase in the strength of the spin-fluctuation pairing interaction as the temperature decreases rather than the Cooper log instability.

  20. Antibacterial surface design - Contact kill

    Science.gov (United States)

    Kaur, Rajbir; Liu, Song

    2016-08-01

    Designing antibacterial surfaces has become extremely important to minimize Healthcare Associated Infections which are a major cause of mortality worldwide. A previous biocide-releasing approach is based on leaching of encapsulated biocides such as silver and triclosan which exerts negative impacts on the environment and potentially contributes to the development of bacterial resistance. This drawback of leachable compounds led to the shift of interest towards a more sustainable and environmentally friendly approach: contact-killing surfaces. Biocides that can be bound onto surfaces to give the substrates contact-active antibacterial activity include quaternary ammonium compounds (QACs), quaternary phosphoniums (QPs), carbon nanotubes, antibacterial peptides, and N-chloramines. Among the above, QACs and N-chloramines are the most researched contact-active biocides. We review the engineering of contact-active surfaces using QACs or N-chloramines, the modes of actions as well as the test methods. The charge-density threshold of cationic surfaces for desired antibacterial efficacy and attempts to combine various biocides for the generation of new contact-active surfaces are discussed in detail. Surface positive charge density is identified as a key parameter to define antibacterial efficacy. We expect that this research field will continue to attract more research interest in view of the potential impact of self-disinfective surfaces on healthcare-associated infections, food safety and corrosion/fouling resistance required on industrial surfaces such as oil pipes and ship hulls.

  1. Improving electric contacts by ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Xu Shiru; Zhang Ying; Zheng Tiampi

    1989-01-01

    This article studies the improvement of electric contacts by ion implantation. 1 x 10/sup 17/ cm/sup -2/ of N/sup +/ and N/sub 2//sup +/ was implanted into two kinds of electric contacts, then a make-and-break test was made with the low voltage electrical apparatus. The weight loss of the contacts, temperature rise, contact resistance and transfer of material between the two contacts were measured. The contacts implanted by ions have improved electrical erosion properties.

  2. Solubilization and fractionation of paired helical filaments.

    Science.gov (United States)

    González, P J; Correas, I; Avila, J

    1992-09-01

    Paired helical filaments isolated from brains of two different patients with Alzheimer's disease were extensively treated with the ionic detergent, sodium dodecyl sulphate. Filaments were solubilized at different extents, depending on the brain examined, thus suggesting the existence of two types of paired helical filaments: sodium dodecyl sulphate-soluble and insoluble filaments. In the first case, the number of structures resembling paired helical filaments greatly decreased after the detergent treatment, as observed by electron microscopy. Simultaneously, a decrease in the amount of sedimentable protein was also observed upon centrifugation of the sodium dodecyl sulfate-treated paired helical filaments. A sodium dodecyl sulphate-soluble fraction was isolated as a supernatant after low-speed centrifugation of the sodium dodecyl sulphate-treated paired helical filaments. The addition of the non-ionic detergent Nonidet-P40 to this fraction resulted in the formation of paired helical filament-like structures. When the sodium dodecyl sulphate-soluble fraction was further fractionated by high-speed centrifugation, three subfractions were observed: a supernatant, a pellet and a thin layer between these two subfractions. No paired helical filaments were observed in any of these subfractions, even after addition of Nonidet P-40. However, when they were mixed back together, the treatment with Nonidet P-40 resulted in the visualization of paired helical filament-like structures. These results suggest that at least two different components are needed for the reconstitution of paired helical filaments as determined by electron microscopy. The method described here may allow the study of the components involved in the formation of paired helical filaments and the identification of possible factors capable of blocking this process.

  3. Ion pairs of indobenzimidazolo cyanines: a structural study based on conductivity, absorption, fluorescence and 1H-NMR

    Science.gov (United States)

    Tatikolov, Aleksandr S.; Ishchenko, Aleksandr A.; Ghelli, Stefano; Ponterini, Glauco

    1998-11-01

    Asymmetric benzimidazolo carbo, di- and tricarbocyanines form ion pairs of the solvent-separated and contact types with different counterions in tetrahydrofuran, toluene and toluene-nitrile mixtures. The dissociation constants of the ion pairs in tetrahydrofuran, evaluated from conductivity data, do not depend on the length of the polymethine chain and show only a small decrease with decreasing counterion size. The absorption and fluorescence excitation spectra of the contact ion pairs exhibit a pronounced hypsochromic shift with respect to the solvated ions and the solvent-separated ion pairs. 1H-NMR experiments have provided information about the electronic structures of the ions of both the asymmetric dyes and the corresponding symmetric carbocyanines. They have also revealed different preferred anion locations in the contact ion pairs of the symmetric indocarbocyanine on one hand, and of the benzimidazolo carbocyanine and the asymmetric dyes on the other. This structural difference is suggested to be a cause of the observed opposite effects of ion pairing on the isomerization kinetics of the two groups of dyes.

  4. Contact dermatitis in a woodworker.

    Science.gov (United States)

    Correale, Christine E; Marks, James G

    2002-03-01

    Woods are capable of causing allergic or irritant contact dermatitis which typically occurs on the exposed areas of the arms, face, and neck. The allergens found in woods include quinones, stilbenes, phenols, and terpenes. We report an 84-year-old woodworker who developed allergic contact dermatitis from Bolivian rosewood and Cocobolo wood. The patient was patch-tested using the North American Contact Dermatitis Group Standard Tray; 2,6 dimethoxyl 1,4 benzoquinone; and wood that he had been exposed to on a regular basis. Positive patch test reactions occurred to methyldibromo glutaronitrile phenoxyethanol, sodium gold thiosulfate, Bolivian rosewood, and Cocobolo wood. Allergens found in Bolivian rosewood and Cocobolo wood caused this patient's chronic dermatitis, which cleared when he avoided these woods. Copyright 2002, Elsevier Science (USA). All rights reserved.

  5. [Occupational contact dermatitis in hairdressers].

    Science.gov (United States)

    Kieć-Swierczyńska, Marta; Krycisz, Beata; Chomiczewska, Dorota

    2009-01-01

    Numerous data from the medical literature show that working as a hairdresser is associated with the highest risk of occupational contact dermatitis. In Europe, hairdressers rank first of all occupation groups with the highest prevalence of occupational dermatitis. It is estimated that 10-20% and even 50% of hairdressers are affected with skin disorders. Skin problems occur soon after commencing hairdressing, in the first 2 years of work, sometimes during vocational training. The most common factors contributing to skin damage include water, shampoos, detergents, conditioners, hair dyes, bleaches, permanent wave solutions and components of gloves. Water and wet work are prime skin irritants - causal factors of irritant contact dermatitis while p-phenylenediamine, glyceryl monothioglycolate, ammonium persulfate and also fragrances, preservatives, disinfectants and metals are the most important allergens, which induce allergic contact dermatitis.

  6. Methylisothiazolinone contact allergy - A review

    DEFF Research Database (Denmark)

    Lundov, M D; Krongaard, Teddy; L Menné, T

    2011-01-01

    In the early 2000s the preservative methylisothiazolinone (MI) was released as an individual preservative for industrial products and in 2005 permitted for use in cosmetic products. Up till then MI had only been used in combination with methylcholoroisthiazolinone (MCI). MCI/MI is one of the most...... frequent causes of preservative contact allergy and early studies showed that both MI and MCI are sensitizers. The prevalence of MI contact allergy is already around 1·5% and sources of exposure are associated with occupation, cosmetic products or household products. Use of MI in industrial products...... is not restricted and cases of occupational contact allergy to MI e.g. in painters are reported. The frequency of use of MI in cosmetics is low, around 1%, while up to 16·5% of household products were preserved with MI. We found 19 (1·5%) out of 1272 cosmetic products labelled with MI, primarily rinse-off products...

  7. Methylisothiazolinone contact allergy: a review

    DEFF Research Database (Denmark)

    Lundov, M D; Krongaard, T; Menné, T L

    2011-01-01

    In the early 2000s the preservative methylisothiazolinone (MI) was released as an individual preservative for industrial products and in 2005 permitted for use in cosmetic products. Up till then MI had only been used in combination with methylcholoroisthiazolinone (MCI). MCI/MI is one of the most...... frequent causes of preservative contact allergy and early studies showed that both MI and MCI are sensitizers. The prevalence of MI contact allergy is already around 1·5% and sources of exposure are associated with occupation, cosmetic products or household products. Use of MI in industrial products...... is not restricted and cases of occupational contact allergy to MI e.g. in painters are reported. The frequency of use of MI in cosmetics is low, around 1%, while up to 16·5% of household products were preserved with MI. We found 19 (1·5%) out of 1272 cosmetic products labelled with MI, primarily rinse-off products...

  8. Soft lithography contacts to organics

    Directory of Open Access Journals (Sweden)

    Julia W.P. Hsu

    2005-07-01

    Full Text Available Organic materials play an increasingly important role in (optoelectronics, particularly in low-cost or flexible devices. A major challenge is the contact between the electrodes and the organic material. Processes developed for inorganic semiconductors are inapplicable because of the sensitivity of organic materials to heat, radiation, and chemicals. Deposition of metal(s through shadow masks onto organic materials is commonly used, despite problems with ill-controlled interfaces and material damage. In addition, conventional approaches restrict device size to >1 μm. Clearly, a better technique is needed. In this article, two soft lithography methods for making contacts to organic materials are reviewed: nanotransfer printing (nTP and soft-contact lamination (ScL. These new approaches produce devices that outperform those made by conventional methods. The link between better device performance and better interfacial control is explained, and nanoscale devices are described.

  9. Effect of extended tooth contact on the modeling of spur gear transmissions

    Science.gov (United States)

    Oswald, Fred B.; Coy, John J.; Lin, Hsiang Hsi; Wang, Jifeng

    1993-01-01

    In some gear dynamic models, the effect of tooth flexibility is ignored when the model determines which pairs of teeth are in contact. Deflection of loaded teeth is not introduced until the equations of motion are solved. This means the zone of tooth contact and average tooth meshing stiffness are underestimated and the individual tooth load is overstated, especially for heavily-loaded gears. The static transmission error and dynamic load of heavily-loaded, low-contact-ratio spur gears is compared with this effect both neglected and included. Neglecting the effect yields an underestimate of resonance speeds and an overestimate of the dynamic load.

  10. Effect of extended tooth contact on the modeling of spur gear transmissions

    Science.gov (United States)

    Lin, Hsiang H.; Wang, Jifeng; Oswald, Fred B.; Coy, John J.

    1993-06-01

    In some gear dynamic models, the effect of tooth flexibility is ignored when the model determines which pairs of teeth are in contact. Deflection of loaded teeth is not introduced until the equations of motion are solved. This means the zone of tooth contact and average tooth meshing stiffness are underestimated and the individual tooth load is overstated, especially for heavily-loaded gears. The static transmission error and dynamic load of heavily-loaded, low-contact-ratio spur gears is compared with this effect both neglected and included. Neglecting the effect yields an underestimate of resonance speeds and an overestimate of the dynamic load.

  11. Quasiparticles in a diffusive conductor: interaction and pairing

    Energy Technology Data Exchange (ETDEWEB)

    Gueron, S

    1997-10-17

    The interaction between quasi particles is studied both theoretically and experimentally. The first part of this thesis is to provide direct evidence for this interaction by measuring the energy exchange rate between quasi particles in the case of thin metallic diffusive films. The experimental results agree qualitatively with the existing theories but are not explained quantitatively. The second part of this thesis deals with the propagation of correlation of pairs of electrons with opposite spin in a normal metal when it is placed in contact with a superconductor. This proximity effect is studied by measuring the density of states. The aim of the experiments is to specify in what sense a normal metal in proximity with a superconductor develops a superconducting character. (A.C.) 102 refs.

  12. The Chromosomal Courtship Dance-homolog pairing in early meiosis.

    Science.gov (United States)

    Klutstein, Michael; Cooper, Julia Promisel

    2014-02-01

    The intermingling of genomes that characterizes sexual reproduction requires haploid gametes in which parental homologs have recombined. For this, homologs must pair during meiosis. In a crowded nucleus where sequence homology is obscured by the enormous scale and packaging of the genome, partner alignment is no small task. Here we review the early stages of this process. Chromosomes first establish an initial docking site, usually at telomeres or centromeres. The acquisition of chromosome-specific patterns of binding factors facilitates homolog recognition. Chromosomes are then tethered to the nuclear envelope (NE) and subjected to nuclear movements that 'shake off' inappropriate contacts while consolidating homolog associations. Thereafter, homolog connections are stabilized by building the synaptonemal complex or its equivalent and creating genetic crossovers. Recent perspectives on the roles of these stages will be discussed.

  13. Pairing of a few Fermi atoms in one dimension

    Science.gov (United States)

    D'Amico, Pino; Rontani, Massimo

    2015-04-01

    We study a few Fermi atoms interacting through attractive contact forces in a one-dimensional trap by means of numerical exact diagonalization. From the combined analysis of energies and wave functions of correlated ground and excited states we find evidence of BCS-like pairing even for very few atoms. For moderate interaction strength, we reproduce the even-odd oscillation of the separation energy observed in Zürn, Wenz, Murmann, Bergschneider, Lompe, and Jochim, Phys. Rev. Lett. 111, 175302 (2013), 10.1103/PhysRevLett.111.175302. For strong interatomic attraction the arrangement of dimers in the trap differs from the homogeneous case as a consequence of Pauli blockade in real space.

  14. Final Report on project Photoinduced Dipoles and Charge Pairs in Condensed Media

    Energy Technology Data Exchange (ETDEWEB)

    Braun, Charles L.

    2006-09-27

    Most of our work involves photogenerated donor (D+) and acceptor (A-) radical ion pairs and their escape and recombination. The geminate radical ions are produced by inter or intramolecular electron transfer quenching of photoexcited acceptors. We made great progress in understanding the effect of charge separation distance and other factors on free ion formation. For geminate radical ion pairs formed by intermolecular electron transfer quenching, we found that, at least in a medium polarity solvent lilce dichloromethane, free radical ions are mainly formed from solvent separated radical ion pairs (SSRIPs). Contact radical ion pairs (CRIPs) make a very small contribution to free radical ion formation. It is observed that CRIPs and SSRIPs are kinetically distinguishable species. There is a potential barrier between CRIPs and SSRIPs that prevents a fast equilibrium between the two during the recombination of radical ion pairs and free radical ion formation. We confirmed for the first time that, for the recombination of both CRIPs and SSRIPs that are in the Marcus inverted region, rate constants of SSRIPs are larger than those of CRIPs. Our study indicates that initial charge separation distance and the potential barrier between CRIPs and SSRIPs play a more important role than recombination rate on free ion formation. Temperature dependence experiments reveal that through-tunneling back electron transfer is the dominant approach for the SSRIP recombination process. We believe that our discovery of the roles played by the initial charge separation distance and the potential barrier between radical ion pairs of different separation have very important implications for the development of new concepts for the design of organic photovoltaic (OPV) cells. Photoinduced transient dipole experiments are used to probe the effective charge separation distance of flexible electron donor/acceptor systems, D-(CH2)n-A, where D is 4-N-N-dimethylaniline, A is 9-anthryl and n=3, 4. We

  15. Multibody dynamics with unilateral contacts

    CERN Document Server

    Pfeiffer, Friedrich

    2008-01-01

    As mechanical systems become more complex so do the mathematical models and simulations used to describe the interactions of their parts. One area of multibody theory that has received a great deal of attention in recent years is the dynamics of multiple contact situations occurring in continuous joints and couplings. Despite the rapid gains in our understanding of what occurs when continuous joints and couplings interact, until now there were no books devoted exclusively to this intriguing phenomenon. Focusing on the concerns of practicing engineers, Multibody Dynamics with Unilateral Contact

  16. Contact allergy to oak moss

    DEFF Research Database (Denmark)

    Bernard, Guillaume; Giménez-Arnau, Elena; Rastogi, Suresh Chandra

    2003-01-01

    a method developed for the identification of contact allergens present in natural complex mixtures to oak moss absolute. The method is based on the combination of bioassay-guided chemical fractionation, gas chromatography-mass spectrometry analysis and structure-activity relationship studies. Our first......In addition to pure synthetic fragrance materials several natural extracts are still in use in the perfume industry. Among them oak moss absolute, prepared from the lichen Evernia prunastri (L.) Arch., is considered a major contact sensitizer and is therefore included in the fragrance mix used...

  17. CONTACT DERMATITIS AMONG CONSTRUCTION WORKERS

    Directory of Open Access Journals (Sweden)

    Ida Ayu Diah Purnama Sari

    2013-02-01

    Full Text Available Contact dermatitis is a form of skin inflammation with spongiosis or intercellular edema of the epidermis due to the interaction of irritants and allergens. While occupational contact dermatitis is an inflammation of the skin due to exposure to irritants or allergens in the workplace. One of the jobs that have a high risk of the disease are construction workers. Although the disease is rarely-threatening but can cause high morbidity and suffering for workers, so it can affect the economy and quality of life of patients.

  18. Allergic contact dermatitis and cosmetics.

    Science.gov (United States)

    Watkins, Shannon; Zippin, Jonathan

    2012-10-01

    Contact dermatitis is a common dermatologic condition that can result from exposure to allergens at home or at work. Cosmetics represent a large diverse group of products that Americans apply to their skin to treat disease or enhance beauty. With increased use of cosmetics, the rate of sensitization to many allergenic components has increased. We review the more common allergens present in cosmetics as well as the types of cosmetics that are known to contain them. With proper education and patch testing, dermatologists will be able to identify contact allergies to cosmetic ingredients and help patients avoid the offending products.

  19. Contact urticaria, allergic contact dermatitis, and photoallergic contact dermatitis from oxybenzone.

    Science.gov (United States)

    Landers, Maeran; Law, Sandra; Storrs, Frances J

    2003-03-01

    There is little literature regarding conventional patch tests and photopatch tests to oxybenzone resulting in both immediate- and delayed-type hypersensitivity reactions. A patient was patch-tested and photopatch-tested to various sunscreen chemicals. Both immediate- and delayed-type hypersensitivity reactions were observed with oxybenzone. The positive patch tests were also photoaccentuated. Oxybenzone, a common sunscreen allergen, can result in both contact urticaria and delayed-type hypersensitivity on both conventional patch testing and photopatch testing. Allergic contact dermatitis to sunscreen chemicals has traditionally included contact urticaria, allergic contact dermatitis, and photoallergic contact dermatitis. Due to the recognition of p-aminobenzoic acid (PABA) and its esters as sensitizers, the presence of benzophenones in "PABA-free" sunscreens has become more prevalent, especially in sunscreens with a sun protection factor (SPF) greater than 8. In our patient, immediate- and delayed-type hypersensitivity reactions were seen to oxybenzone (2-hydroxy-4-methoxybenzophenone, 2-benzoyl-5-methoxyphenol, benzophenone-3, Eusolex 4360, Escalol 567, EUSORB 228, Spectra-Sorb UV-9, Uvinul M-40) upon conventional patch testing and photopatch testing.

  20. Contact Characteristics of Conical Involute Gears with Crossed Axes%交错轴渐开线锥形齿轮的接触特性

    Institute of Scientific and Technical Information of China (English)

    李建刚; 王淑媛; 贺敬良; 李雪松

    2005-01-01

    Based on the theory of gearing and the gear generating mechanism, this study investigates the contact characteristics of conical involute gear pairs with crossed axes. The meshing model with a reference rack as intermedium is established and tooth contact analysis (TCA) is performed to examine the meshing and bearing contact of the conical involute gear pairs composed of a pinion and a gear. Using the contact line of reference rack tooth surface, the path of contact is confirmed, and the calculation formula of principal direction, relative curvature, path of contact and ellipse of contact are derived. Finally, numerical examples are provided to demonstrate computational results and test gears are made for tooth-bearing tests. The conclusion verifies that the theory is applicable.

  1. Patient-specific finite element analysis of chronic contact stress exposure after intraarticular fracture of the tibial plafond.

    Science.gov (United States)

    Li, Wendy; Anderson, Donald D; Goldsworthy, Jane K; Marsh, J Lawrence; Brown, Thomas D

    2008-08-01

    The role of altered contact mechanics in the pathogenesis of posttraumatic osteoarthritis (PTOA) following intraarticular fracture remains poorly understood. One proposed etiology is that residual incongruities lead to altered joint contact stresses that, over time, predispose to PTOA. Prevailing joint contact stresses following surgical fracture reduction were quantified in this study using patient-specific contact finite element (FE) analysis. FE models were created for 11 ankle pairs from tibial plafond fracture patients. Both (reduced) fractured ankles and their intact contralaterals were modeled. A sequence of 13 loading instances was used to simulate the stance phase of gait. Contact stresses were summed across loadings in the simulation, weighted by resident time in the gait cycle. This chronic exposure measure, a metric of degeneration propensity, was then compared between intact and fractured ankle pairs. Intact ankles had lower peak contact stress exposures that were more uniform and centrally located. The series-average peak contact stress elevation for fractured ankles was 38% (p = 0.0015; peak elevation was 82%). Fractured ankles had less area with low contact stress exposure than intact ankles and a greater area with high exposure. Chronic contact stress overexposures (stresses exceeding a damage threshold) ranged from near zero to a high of 18 times the matched intact value. The patient-specific FE models represent substantial progress toward elucidating the relationship between altered contact stresses and the outcome of patients treated for intraarticular fractures.

  2. P-wave Cooper pair splitting

    Directory of Open Access Journals (Sweden)

    Henning Soller

    2012-07-01

    Full Text Available Background: Splitting of Cooper pairs has recently been realized experimentally for s-wave Cooper pairs. A split Cooper pair represents an entangled two-electron pair state, which has possible application in on-chip quantum computation. Likewise the spin-activity of interfaces in nanoscale tunnel junctions has been investigated theoretically and experimentally in recent years. However, the possible implications of spin-active interfaces in Cooper pair splitters so far have not been investigated.Results: We analyze the current and the cross correlation of currents in a superconductor–ferromagnet beam splitter, including spin-active scattering. Using the Hamiltonian formalism, we calculate the cumulant-generating function of charge transfer. As a first step, we discuss characteristics of the conductance for crossed Andreev reflection in superconductor–ferromagnet beam splitters with s-wave and p-wave superconductors and no spin-active scattering. In a second step, we consider spin-active scattering and show how to realize p-wave splitting using only an s-wave superconductor, through the process of spin-flipped crossed Andreev reflection. We present results for the conductance and cross correlations.Conclusion: Spin-activity of interfaces in Cooper pair splitters allows for new features in ordinary s-wave Cooper pair splitters, that can otherwise only be realized by using p-wave superconductors. In particular, it provides access to Bell states that are different from the typical spin singlet state.

  3. Pure Pairing Modes in Trapped Fermion Systems

    Science.gov (United States)

    Capuzzi, P.; Hernández, E. S.; Szybisz, L.

    2013-05-01

    We present numerical predictions for the shape of the pairing fluctuations in harmonically trapped atomic 6Li with two spin projections, based on the fluiddynamical description of cold fermions with pairing interactions. In previous works it has been shown that when the equilibrium of a symmetric mixture is perturbed, the linearized fluiddynamic equations decouple into two sets, one containing the sound mode of fermion superfluids and the other the pairing mode. The latter corresponds to oscillations of the modulus of the complex gap and is driven by the kinetic energy densities of the particles and of the pairs. Assuming proportionality between the heat flux and the energy gradient, the particle kinetic energy undergoes a diffusive behavior and the diffusion parameter is the key parameter for the relaxation time scale. We examine a possible range of values for this parameter and find that the shape of the pairing oscillation is rather insensitive to the precise value of the transport coefficient. Moreover, the pairing fluctuation is largely confined to the center of the trap, and the energy of the pairing mode is consistent with the magnitude of the equilibrium gap.

  4. String pair production in non homogeneous backgrounds

    Energy Technology Data Exchange (ETDEWEB)

    Bolognesi, S. [Department of Physics “E. Fermi” University of Pisa, and INFN - Sezione di Pisa,Largo Pontecorvo, 3, Ed. C, 56127 Pisa (Italy); Rabinovici, E. [Racah Institute of Physics, The Hebrew University of Jerusalem,91904 Jerusalem (Israel); Tallarita, G. [Departamento de Ciencias, Facultad de Artes Liberales,Universidad Adolfo Ibáñez, Santiago 7941169 (Chile)

    2016-04-28

    We consider string pair production in non homogeneous electric backgrounds. We study several particular configurations which can be addressed with the Euclidean world-sheet instanton technique, the analogue of the world-line instanton for particles. In the first case the string is suspended between two D-branes in flat space-time, in the second case the string lives in AdS and terminates on one D-brane (this realizes the holographic Schwinger effect). In some regions of parameter space the result is well approximated by the known analytical formulas, either the particle pair production in non-homogeneous background or the string pair production in homogeneous background. In other cases we see effects which are intrinsically stringy and related to the non-homogeneity of the background. The pair production is enhanced already for particles in time dependent electric field backgrounds. The string nature enhances this even further. For spacial varying electrical background fields the string pair production is less suppressed than the rate of particle pair production. We discuss in some detail how the critical field is affected by the non-homogeneity, for both time and space dependent electric field backgrouds. We also comment on what could be an interesting new prediction for the small field limit. The third case we consider is pair production in holographic confining backgrounds with homogeneous and non-homogeneous fields.

  5. Exploring Pair Programming Benefits for MIS Majors

    Directory of Open Access Journals (Sweden)

    April H. Reed

    2016-12-01

    Full Text Available Pair programming is a collaborative programming practice that places participants in dyads, working in tandem at one computer to complete programming assignments. Pair programming studies with Computer Science (CS and Software Engineering (SE majors have identified benefits such as technical productivity, program/design quality, academic performance, and increased satisfaction for their participants. In this paper, pair programming is studied with Management Information Systems (MIS majors, who (unlike CS and SE majors taking several programming courses typically take only one programming course and often struggle to develop advanced programming skills within that single course. The researchers conducted two pair programming experiments in an introductory software development course for MIS majors over three semesters to determine if pair programming could enhance learning for MIS students. The program results, researchers’ direct observations, and participants’ responses to a survey questionnaire were analyzed after each experiment. The results indicate that pair programming appears to be beneficial to MIS students’ technical productivity and program design quality, specifically the ability to create programs using high-level concepts. Additionally, results confirmed increased student satisfaction and reduced frustration, as the pairs worked collaboratively to produce a program while actively communicating and enjoying the process.

  6. An Easy-To-Use Combination Four-Terminal-Pair/Two-Terminal-Pair AC Transformer Bridge.

    Science.gov (United States)

    Jeffery, A; Shields, J Q; Lee, L H

    1998-01-01

    A new four-terminal-pair bridge, capable of achieving a relative standard uncertainty of 1×10(-9), was constructed at the National Institute of Standards and Technology by converting a two-terminal-pair bridge. The conversion requires only the addition of components which are easily removed if two-terminal-pair measurements are to be made. The design and testing of this bridge is described. The new four-terminal-pair bridge requires fewer auxiliary balances than the present four-terminal-pair bridge employed at NIST, which makes it much easier to use. This new design can be used to compare capacitance, resistance, and inductance standards.

  7. English for au pairs the au pair's guide to learning English

    CERN Document Server

    Curtis, Lucy

    2014-01-01

    English for Au Pairs has interlinked stories about a group of au pairs new to England. Marta, an 18-year-old from Poland arrives in the UK to work as an au pair. Throughout her year-long stay she has many different experiences - some bad, some good - but with the support of her host family she finds new friends and improves her English. English for Au Pairs offers insight into the joys and difficulties of being an au pair while at the same time reinforcing English language learning through grammar explanations and exercises.

  8. Pair supersolid with atom-pair hopping on the state-dependent triangular lattice

    Science.gov (United States)

    Zhang, Wanzhou; Yin, Ruoxi; Wang, Yancheng

    2013-11-01

    We systematically study an extended Bose-Hubbard model with atom hopping and atom-pair hopping in the presence of a three-body constraint on the triangular lattice. By means of large-scale quantum Monte Carlo simulations, the ground-state phase diagram is studied. We find a first-order transition between the atomic superfluid phase and the pair superfluid phase when the ratio of the atomic hopping and the atom-pair hopping is adapted. The first-order transition remains unchanged under various conditions. We then focus on the interplay among the atom-pair hopping, the on-site repulsion, and the nearest-neighbor repulsion. With on-site repulsion present, we observe first-order transitions between the Mott insulators and pair superfluid driven by the pair hopping. With the nearest-neighbor repulsion turning on, three typical solid phases with 2/3, 1, and 4/3 filling emerge at small atom-pair hopping region. A stable pair supersolid phase is found at small on-site repulsion. This is due to the three-body constraint and the pair hopping, which essentially make the model a quasihardcore boson system. Thus the pair supersolid state emerges basing on the order-by-disorder mechanism, by which hardcore bosons avoid classical frustration on the triangular lattice. Without on-site repulsion, the transitions between the pair supersolid and the atom superfluid or pair superfluid are first order, except for the particle-hole symmetric point. With weak on-site repulsion and atom hopping turning on, the transition between the pair supersolid and pair superfluid phase becomes continuous. The transition between solid and pair supersolid is three-dimensional XY university, with dynamical exponent z=1 and correlation exponent ν=0.67155. The thermal melting of pair supersolid belongs to the two-dimensional Ising university. We check both energetic and mechanical balance of pair supersolid phase. Lowering the three-body constraint, no pair supersolid is found due to the absence of

  9. Fast Grasp Contact Computation for a Serial Robot

    Science.gov (United States)

    Shi, Jianying (Inventor); Hargrave, Brian (Inventor); Diftler, Myron A. (Inventor)

    2015-01-01

    A system includes a controller and a serial robot having links that are interconnected by a joint, wherein the robot can grasp a three-dimensional (3D) object in response to a commanded grasp pose. The controller receives input information, including the commanded grasp pose, a first set of information describing the kinematics of the robot, and a second set of information describing the position of the object to be grasped. The controller also calculates, in a two-dimensional (2D) plane, a set of contact points between the serial robot and a surface of the 3D object needed for the serial robot to achieve the commanded grasp pose. A required joint angle is then calculated in the 2D plane between the pair of links using the set of contact points. A control action is then executed with respect to the motion of the serial robot using the required joint angle.

  10. Evaporation Erosion During the Relay Contact Breaking Process Based on a Simplified Arc Model

    Institute of Scientific and Technical Information of China (English)

    CUI Xinglei; ZHOU Xue; ZHAI Guofu; PENG Xiyuan

    2016-01-01

    Evaporation erosion of the contacts is one of the fundamental failure mechanisms for relays.In this paper,the evaporation erosion characteristics are investigated for the copper contact pair breaking a resistive direct current (dc) 30 V/10 A circuit in the air.Molten pool simulation of thc contacts is coupled with the gas dynamics to cMculate the evaporation rate.A simplified arc model is constructed to obtain the contact voltage and current variations with time for the prediction of the current density and the heat flux distributions flowing from the arc into the contacts.The evaporation rate and mass variations with time during the breaking process are presented.Experiments are carried out to verify the simulation results.

  11. Pair Creation at Large Inherent Angles

    Energy Technology Data Exchange (ETDEWEB)

    Chen, P.; Tauchi, T.; Schroeder, D.V.; /SLAC

    2007-04-25

    In the next-generation linear colliders, the low-energy e{sup +}e{sup -} pairs created during the collision of high-energy e{sup +}e{sup -} beams would cause potential deleterious background problems to the detectors. At low collider energies, the pairs are made essentially by the incoherent process, where the pair is created by the interaction of beamstrahlung photons on the individual particles in the oncoming beam. This problem was first identified by Zolotarev, et al[1]. At energies where the beamstrahlung parameter {Upsilon} lies approximately in the range 0.6 {approx}< {Upsilon} {approx}< 100, pair creation from the beamstrahlung photons is dominated by a coherent process, first noted by Chen[2]. The seriousness of this pair creation problem lies in the transverse momenta that the pair particles carry when leaving the interaction point (IP) with large angles. One source of transverse momentum is from the kick by the field of the oncoming beam which results in an outcoming angle {theta} {proportional_to} 1/{radical}x, where x is the fractional energy of the particle relative to the initial beam particle energy[2,3]. As was shown in Ref. 131, there in fact exists an energy threshold for the coherent pairs, where x{sub th} {approx}> 1/2{Upsilon}. Thus within a tolerable exiting angle, there exists an upper limit for {Upsilon} where all coherent pairs would leave the detector through the exhaust port[4]. A somewhat different analysis has been done by Schroeder[5]. In the next generation of linear colliders, as it occurs, the coherent pairs can be exponentially suppressed[2] by properly choosing the {Upsilon}({approx}< 0.6). When this is achieved, the incoherent pairs becomes dominant. Since the central issue is the transverse momentum for particles with large angles, we notice that there is another source for it. Namely, when the pair particles are created at low energies, the intrinsic angles of these pairs when produced may already be large. This issue was

  12. Pair creation in heavy ion channeling

    Directory of Open Access Journals (Sweden)

    N.A. Belov

    2016-04-01

    Full Text Available Heavy ions channeled through crystals with multi-GeV kinetic energies can create electron–positron pairs. In the framework of the ion, the energy of virtual photons arising from the periodic crystal potential may exceed the threshold 2mec2. The repeated periodic collisions with the crystal ions yield high pair production rates. When the virtual photon frequency matches a nuclear transition in the ion, the production rate can be resonantly increased. In this two-step excitation-pair conversion scheme, the excitation rates are coherently enhanced, and scale approximately quadratically with the number of crystal sites along the channel.

  13. Implementation of Cryptosystems Based on Tate Pairing

    Institute of Scientific and Technical Information of China (English)

    Lei Hu; Jun-Wu Dong; Ding-Yi Pei

    2005-01-01

    Tate pairings over elliptic curves are important in cryptography since they can be used to construct efficient identity-based cryptosystems, and their implementation dominantly determines the efficiencies of the cryptosystems. In this paper, the implementation of a cryptosystem is provided based on the Tate pairing over a supersingular elliptic curve of MOV degree 3. The implementation is primarily designed to re-use low-level codes developed in implementation of usual elliptic curve cryptosystems. The paper studies how to construct the underlying ground field and its extension to accelerate the finite field arithmetic, and presents a technique to speedup the time-consuming powering in the Tate pairing algorithm.

  14. Becoming independent through au pair migration

    DEFF Research Database (Denmark)

    Dalgas, Karina Märcher

    2015-01-01

    . This article argues that, despite this critique, au pairing does play an important formative role for young Filipinas because it opens up for experiences abroad that enable them to be recognised as independent adults in Philippine society. Rather than autonomy, however, au pairs define their independence...... in terms of their capacity to assume responsibility for others, thereby achieving a position of social respect. Based on ethnographic fieldwork in Denmark and the Philippines, this article explores how young Filipinas use the social, economic, and cultural resources they gain from their au pair stay abroad...

  15. The Effects of Prospective Naturalistic Contact on the Stigma of Mental Illness

    Science.gov (United States)

    Couture, Shannon M.; Penn, David L.

    2006-01-01

    The primary aim of this study was to determine whether naturalistic, interpersonal contact with persons with a severe mental illness (SMI) could reduce stigma. Participants from the agency Compeer (which pairs volunteers with people with SMI) were compared to volunteers from a control agency and to nonvolunteer participants from the community on…

  16. Genotyping Oral Commensal Bacteria to Predict Social Contact and Structure

    Science.gov (United States)

    Wallace, Amelia D.; Riley, Lee W.

    2016-01-01

    Social network structure is a fundamental determinant of human health, from infectious to chronic diseases. However, quantitative and unbiased approaches to measuring social network structure are lacking. We hypothesized that genetic relatedness of oral commensal bacteria could be used to infer social contact between humans, just as genetic relatedness of pathogens can be used to determine transmission chains of pathogens. We used a traditional, questionnaire survey-based method to characterize the contact network of the School of Public Health at a large research university. We then collected saliva from a subset of individuals to analyze their oral microflora using a modified deep sequencing multilocus sequence typing (MLST) procedure. We examined micro-evolutionary changes in the S. viridans group to uncover transmission patterns reflecting social network structure. We amplified seven housekeeping gene loci from the Streptococcus viridans group, a group of ubiquitous commensal bacteria, and sequenced the PCR products using next-generation sequencing. By comparing the generated S. viridans reads between pairs of individuals, we reconstructed the social network of the sampled individuals and compared it to the network derived from the questionnaire survey-based method. The genetic relatedness significantly (p-value < 0.001) correlated with social distance in the questionnaire-based network, and the reconstructed network closely matched the network derived from the questionnaire survey-based method. Oral commensal bacterial are thus likely transmitted through routine physical contact or shared environment. Their genetic relatedness can be used to represent a combination of social contact and shared physical space, therefore reconstructing networks of contact. This study provides the first step in developing a method to measure direct social contact based on commensal organism genotyping, potentially capable of unmasking hidden social networks that contribute to

  17. Contact Lenses for Vision Correction

    Science.gov (United States)

    ... Follow The Academy Professionals: Education Guidelines News Multimedia Public & Patients: Contact Us About the Academy Jobs at the Academy Financial Relationships with Industry Medical Disclaimer Privacy Policy Terms of Service For Advertisers For Media Ophthalmology Job Center © American Academy of ...

  18. Almost contact metric 3-submersions

    Directory of Open Access Journals (Sweden)

    Bill Watson

    1984-01-01

    Full Text Available An almost contact metric 3-submersion is a Riemannian submersion, π from an almost contact metric manifold (M4m+3,(φi,ξi,ηii=13,g onto an almost quaternionic manifold (N4n,(Jii=13,h which commutes with the structure tensors of type (1,1;i.e., π*φi=Jiπ*, for i=1,2,3. For various restrictions on ∇φi, (e.g., M is 3-Sasakian, we show corresponding limitations on the second fundamental form of the fibres and on the complete integrability of the horizontal distribution. Concommitantly, relations are derived between the Betti numbers of a compact total space and the base space. For instance, if M is 3-quasi-Saskian (dΦ=0, then b1(N≤b1(M. The respective φi-holomorphic sectional and bisectional curvature tensors are studied and several unexpected results are obtained. As an example, if X and Y are orthogonal horizontal vector fields on the 3-contact (a relatively weak structure total space of such a submersion, then the respective holomorphic bisectional curvatures satisfy: Bφi(X,Y=B′J′i(X*,Y*−2. Applications to the real differential geometry of Yarg-Milis field equations are indicated based on the fact that a principal SU(2-bundle over a compactified realized space-time can be given the structure of an almost contact metric 3-submersion.

  19. Forces in Liquid Metal Contacts

    DEFF Research Database (Denmark)

    Duggen, Lars; Mátéfi-Tempfli, Stefan

    2014-01-01

    Using rather well known theory about capillary bridges between two electrodes we calculate the tensile force that can be applied to liquid metal contacts in the micrometer regime. Assuming circular symmetry, full wetting of the electrodes, and neglecting gravity, we present a brief review...

  20. Allergic and irritant contact dermatitis.

    Science.gov (United States)

    Nosbaum, Audrey; Vocanson, Marc; Rozieres, Aurore; Hennino, Anca; Nicolas, Jean-François

    2009-01-01

    Irritant and allergic contact dermatitis are common inflammatory skin diseases induced by repeated skin contact with low molecular weight chemicals, called xenobiotics or haptens. Although both diseases may have similar clinical presentations, they can be differentiated on pathophysiological grounds. Irritant contact dermatitis (ICD) is a non-specific inflammatory dermatitis brought about by activation of the innate immune system by the pro-inflammatory properties of chemicals. Allergic contact dermatitis (ACD) corresponds to a delayed-type hypersensitivity response with a skin inflammation mediated by hapten-specific T cells. Recent progress in the pathophysiology of chemical-induced skin inflammation has shown that ICD and ACD are closely associated and that the best way to prevent ACD is to develop strategies to avoid ICD. The immunological diagnosis of ICD or ACD requires investigation of the presence (ACD) or absence (ICD) of antigen-specific T cells. The detection of T cells can be performed in the skin (collected from ACD lesions or positive patch tests) and/or in the blood, particularly by using the enzyme-linked immunospot assay (ELISPOT). This method, recently developed in ACD to metals, offers a new biological tool enabling the immunobiological diagnosis of ACD.

  1. Frictional heating of tribological contacts

    NARCIS (Netherlands)

    Bos, Johannes

    1995-01-01

    Wherever friction occurs, mechanical energy is transformed into heat. The tem­ perature rise associated with this heating can have an important influence on the tribological behaviour of the contacting components. Apart from determining per­ formance, thermal phenomena affect reliability and may cau

  2. Clinical update on contact allergy.

    Science.gov (United States)

    Uter, Wolfgang; Johansen, Jeanne Duus; Orton, David I; Frosch, Peter J; Schnuch, Axel

    2005-10-01

    The aim of this article is to review recent findings in contact allergy, regarding clinical research. The biocide methyldibromo glutaronitrile was identified to be an important sensitizer. Subsequently, it was banned from leave-on cosmetics in the European Union. Another group of important allergens that have been studied extensively included the fragrances oak moss absolute, isoeugenol, hydroxyisohexyl 3-cyclohexene carboxaldehyde and farnesol. A new fragrance mix II has been developed for standard testing, which includes the two latter compounds. Dose response studies have demonstrated broad individual variation of elicitation thresholds, dependent on the allergen concentration during induction, and other factors. Some unsuspected routes of exposure to allergens include oral, inhalational, connubial or airborne contact. Experimental studies provide a classification of newly introduced chemicals; increasingly, the local lymph node assay is supplementing and potentially replacing the guinea pig maximization test. Recent advances in occupational contact allergy include, for example, some attempts to improve diagnostics for epoxy resin and other plastic, glue, and cutting fluid components. Constant awareness for new allergens, confirmed by critical evaluation, standardization of patch test materials, and the identification of temporal patterns and subgroups at risk will improve both the diagnosis and prevention of allergic contact dermatitis.

  3. Doping graphene with metal contacts

    NARCIS (Netherlands)

    Giovannetti, G.; Khomyakov, Petr; Brocks, G.; Karpan, Volodymyr; van den Brink, J.; Kelly, Paul J.

    2008-01-01

    Making devices with graphene necessarily involves making contacts with metals. We use density functional theory to study how graphene is doped by adsorption on metal substrates and find that weak bonding on Al, Ag, Cu, Au, and Pt, while preserving its unique electronic structure, can still shift the

  4. Uncontrolled Selling of Contact Lenses

    Directory of Open Access Journals (Sweden)

    Cem Sundu

    2015-05-01

    Full Text Available Objectives: To evaluate the opticians’ perspective about selling and applying contact lenses (CL in the provincial centre of Mersin. Materials and Methods: Twenty opticians who work in the 4 main districts in the provincial centre of Mersin were included in the study. A questionnaire form which was prepared before was filled out by the participants. Results: Seventy-eight percent of the opticians were selling CL without prescription, whereas 25% also carried out its fitting. Seventyfive percent of the participants did not get any education about contact lenses, while 65% of them were feeling themselves disqualified about CLs. Furthermore, half of the participants did not have enough knowledge about the complications associated with CL usage and 75% of them wanted to receive information about CLs. Conclusion: As a result of the questionnaire, we found out that a significant part of the participants were both selling and fitting contact lenses without prescription. We believe that auditing the opticians is as important as educating the contact lens users. (Turk J Ophthalmol 2015; 45: 102-104

  5. Ohmic contacts to semiconducting diamond

    Science.gov (United States)

    Zeidler, James R.; Taylor, M. J.; Zeisse, Carl R.; Hewett, C. A.; Delahoussaye, Paul R.

    1990-10-01

    Work was carried out to improve the electron beam evaporation system in order to achieve better deposited films. The basic system is an ion pumped vacuum chamber, with a three-hearth, single-gun e-beam evaporator. Four improvements were made to the system. The system was thoroughly cleaned and new ion pump elements, an e-gun beam adjust unit, and a more accurate crystal monitor were installed. The system now has a base pressure of 3 X 10(exp -9) Torr, and can easily deposit high-melting-temperature metals such as Ta with an accurately controlled thickness. Improved shadow masks were also fabricated for better alignment and control of corner contacts for electrical transport measurements. Appendices include: A Thermally Activated Solid State Reaction Process for Fabricating Ohmic Contacts to Semiconducting Diamond; Tantalum Ohmic Contacts to Diamond by a Solid State Reaction Process; Metallization of Semiconducting Diamond: Mo, Mo/Au, and Mo/Ni/Au; Specific Contact Resistance Measurements of Ohmic Contracts to Diamond; and Electrical Activation of Boron Implanted into Diamond.

  6. Barrier/Cu contact resistivity

    Energy Technology Data Exchange (ETDEWEB)

    Reid, J.S.; Nicolet, M.A. [California Inst. of Tech., Pasadena, CA (United States); Angyal, M.S.; Lilienfeld, D.; Shacham-Diamand, Y. [Cornell Univ., Ithaca, NY (United States); Smith, P.M. [Sandia National Labs., Albuquerque, NM (United States)

    1995-10-17

    The specific contact resistivity of Cu with ({alpha} + {beta})-Ta, TiN, {alpha}-W, and amorphous-Ta{sub 36}Si{sub 14}N{sub 50} barrier films is measured using a novel four-point-probe approach. Geometrically, the test structures consist of colinear sets of W-plugs to act as current and voltage probes that contact the bottom of a planar Cu/barrier/Cu stack. Underlying Al interconnects link the plugs to the current source and voltmeter. The center-to-center distance of the probes ranges from 3 to 200 {micro}m. Using a relation developed by Vu et al., a contact resistivity of roughly 7 {times} 10{sup {minus}9} {Omega} cm{sup 2} is obtained for all tested barrier/Cu combinations. By reflective-mode small-angle X-ray scattering, the similarity in contact resistivity among the barrier films may be related to interfacial impurities absorbed from the deposition process.

  7. Non-contact ECG monitoring

    Science.gov (United States)

    Smirnov, Alexey S.; Erlikh, Vadim V.; Kodkin, Vladimir L.; Keller, Andrei V.; Epishev, Vitaly V.

    2016-03-01

    The research is dedicated to non-contact methods of electrocardiography. The authors describe the routine of experimental procedure and suggest the approach to solving the problems which arise at indirect signal recording. The paper presents the results of experiments conducted by the authors, covers the flow charts of ECG recorders and reviews the drawbacks of filtering methods used in foreign equivalents.

  8. Interfacial closure of contacting surfaces

    Science.gov (United States)

    Rieutord, F.; Rauer, C.; Moriceau, H.

    2014-08-01

    Understanding the contact between solid surfaces is a long-standing problem which has a strong impact on the physics of many processes such as adhesion, friction, lubrication and wear. Experimentally, the investigation of solid/solid interfaces remains challenging today, due to the lack of experimental techniques able to provide sub-nanometer scale information on interfaces buried between millimeters of materials. Yet, a strong interest exists improving the modeling of contact mechanics of materials in order to adjust their interface properties (e.g., thermal transport, friction). We show here that the essential features of the residual gap between contacting surfaces can be measured using high energy X-ray synchrotron reflectivity. The presence of this nano-gap is general to the contact of solids. In some special case however, it can be removed when attractive forces take over repulsive contributions, depending on both height and wavelength of asperity distributions (roughness). A criterion for this instability is established in the standard case of van der Waals attractive forces and elastic asperity compression repulsive forces (Hertz model). This collapse instability is confirmed experimentally in the case of silicon direct bonding, using high-energy X-ray synchrotron reflectivity and adhesion energy measurements. The possibility to achieve fully closed interfaces at room temperature opens interesting perspectives to build stronger assemblies with smaller thermal budgets.

  9. Amplification of Cooper pair splitting current in a graphene-based Cooper pair beam splitter geometry

    Science.gov (United States)

    Islam, SK Firoz; Saha, Arijit

    2017-09-01

    Motivated by the recent experiments [Scientific Reports 6, 23051 (2016), 10.1038/srep23051; Phys. Rev. Lett. 114, 096602 (2015), 10.1103/PhysRevLett.114.096602], we theoretically investigate Cooper pair splitting current in a graphene-based Cooper pair beam splitter geometry. By considering the graphene-based superconductor as an entangler device, instead of normal [two-dimensional (2D)] BCS superconductor, we show that the Cooper pair splitting current mediated by the crossed Andreev process is amplified compared to its normal superconductor counterpart. This amplification is attributed to the strong suppression of the local normal Andreev reflection process (arising from the Cooper pair splitting) from the graphene-based superconductor to lead via the same quantum dot, in comparison to the usual 2D superconductor. Due to the vanishing density of states at the Dirac point of undoped graphene, a doped graphene-based superconductor is considered here and it is observed that Cooper pair splitting current is very insensitive to the doping level in comparison to the usual 2D superconductor. The transport process of nonlocal spin-entangled electrons also depends on the type of pairing, i.e., whether the electron-hole pairing is onsite, intersublattice or the combination of both. The intersublattice pairing of graphene causes the maximum nonlocal Cooper pair splitting current, whereas the presence of both pairings reduces the Cooper pair splitting current.

  10. Implementation of New Pairing Technique for Studying the Effectiveness of Pairs on Persona and Programming

    Directory of Open Access Journals (Sweden)

    HARSIMARJEET KHURANA

    2011-01-01

    Full Text Available This paper reports on a study in which persona for the category of paired and solo students were compared on the parameter like program clarity, presentation, satisfaction level and confidence level, also the effectiveness of pairs in a JAVA programming language and the impact of pairs on each other. In this study same programs were given to all the category of paired and solo students. Finding reported in this paper are that pairing students were more likely to turn in working programs, and these programs were correctly implemented with more required features as compared to solo students. It has been observed that pairing of intelligent, average and poor with themselves has not shown significant differences but we have seen significant differences with combination of pairs.

  11. Quench Property of Twisted-Pair MgB$_2$ Superconducting Cables in Helium Gas

    CERN Document Server

    Spurrell, J; Falorio, I; Pelegrin, J; Ballarino, A; Yang, Y

    2015-01-01

    CERN's twisted-pair superconducting cable is a novel design which offers filament transposition, low cable inductance and is particularly suited for tape conductors such as 2G YBCO coated conductors, Ag-sheathed Bi2223 tapes and Ni/Monel-sheathed MgB2 tapes. A typical design of such twistedpair cables consists of multiple superconducting tapes intercalated with thin copper tapes as additional stabilizers. The copper tapes are typically not soldered to the superconducting tapes so that sufficient flexibility is retained for the twisting of the tape assembly. The electrical and thermal contacts between the copper and superconducting tapes are an important parameter for current sharing, cryogenic stability and quench propagation. Using an MgB2 twisted-pair cable assembly manufactured at CERN, we have carried out minimum quench energy (MQE) and propagation velocity (vp) measurements with point-like heat deposition localized within a tape. Furthermore, different contacts between the copper and superconductor aroun...

  12. Insight into the Evaporation Dynamics of a Pair of Sessile Droplets on a Hydrophobic Substrate.

    Science.gov (United States)

    Shaikeea, Angkur Jyoti Dipanka; Basu, Saptarshi

    2016-02-09

    In this work, we have demonstrated three unique regimes in the evaporation lifecycle of a pair of sessile droplets placed in variable proximity on a hydrophobic substrate. For small separation distance, the droplets undergo asymmetric spatiotemporal evaporation leading to contact angle hysteresis and suppressed vaporization. The reduced evaporation has been attributed quantitatively to the existence of a constrained vapor-rich dome between the two droplets. However, a dynamic decrease in the droplet radius due to solvent removal marks a return to symmetry in terms of evaporation and contact angle. We have described the variation in evaporation flux using a universal correction factor. We have also demonstrated the existence of a critical separation distance beyond which the droplets in the droplet pair do not affect each other. The results are crucial to a plethora of applications ranging from surface patterning to lab-on-a-chip devices.

  13. A new unnatural base pair system between fluorophore and quencher base analogues for nucleic acid-based imaging technology.

    Science.gov (United States)

    Kimoto, Michiko; Mitsui, Tsuneo; Yamashige, Rie; Sato, Akira; Yokoyama, Shigeyuki; Hirao, Ichiro

    2010-11-03

    In the development of orthogonal extra base pairs for expanding the genetic alphabet, we created novel, unnatural base pairs between fluorophore and quencher nucleobase analogues. We found that the nucleobase analogue, 2-nitropyrrole (denoted by Pn), and its 4-substitutions, such as 2-nitro-4-propynylpyrrole (Px) and 4-[3-(6-aminohexanamido)-1-propynyl]-2-nitropyrrole (NH(2)-hx-Px), act as fluorescence quenchers. The Pn and Px bases specifically pair with their pairing partner, 7-(2,2'-bithien-5-yl)imidazo[4,5-b]pyridine (Dss), which is strongly fluorescent. Thus, these unnatural Dss-Pn and Dss-Px base pairs function as reporter-quencher base pairs, and are complementarily incorporated into DNA by polymerase reactions as a third base pair in combination with the natural A-T and G-C pairs. Due to the static contact quenching, the Pn and Px quencher bases significantly decreased the fluorescence intensity of Dss by the unnatural base pairings in DNA duplexes. In addition, the Dss-Px pair exhibited high efficiency and selectivity in PCR amplification. Thus, this new unnatural base pair system would be suitable for detection methods of target nucleic acid sequences, and here we demonstrated the applications of the Dss-Pn and Dss-Px pairs as molecular beacons and in real-time PCR. The genetic alphabet expansion system with the replicable, unnatural fluorophore-quencher base pair will be a useful tool for sensing and diagnostic applications, as well as an imaging tool for basic research.

  14. 22 CFR 62.31 - Au pairs.

    Science.gov (United States)

    2010-04-01

    ... equivalent and a personality profile. Such personality profile will be based upon a psychometric test... such academic course work in an amount not to exceed $1,000 for EduCare au pair participants and in an...

  15. On the concept of frustrated Lewis pairs.

    Science.gov (United States)

    Fontaine, Frédéric-Georges; Stephan, Douglas W

    2017-08-28

    In this concept article, we consider the notion of 'frustrated Lewis pairs' (FLPs). While the original use of the term referred to steric inhibition of dative bond formation in a Lewis pair, work in the intervening decade demonstrates the limitation of this simplistic view. Analogies to known transition metal chemistry and the applications in other areas of chemistry are considered. In the light of these findings, we present reflections on the criteria for a definition of the term 'frustrated Lewis pair'. Segregation of the Lewis acid and base and the kinetic nature of FLP reactivity are discussed. We are led to the conclusion that, while an all-inclusive definition of FLP is challenging, the notion of 'FLP chemistry' is more readily recognized.This article is part of the themed issue 'Frustrated Lewis pair chemistry'. © 2017 The Author(s).

  16. Pairing properties of realistic effective interactions

    Directory of Open Access Journals (Sweden)

    Gargano A.

    2016-01-01

    Full Text Available We investigate the pairing properties of an effective shell-model interaction defined within a model space outside 132Sn and derived by means of perturbation theory from the CD-Bonn free nucleon-nucleon potential. It turns out that the neutron pairing component of the effective interaction is significantly weaker than the proton one, which accounts for the large pairing gap difference observed in the two-valence identical particle nuclei 134Sn and 134Te. The role of the contribution arising from one particle-one hole excitations in determining the pairing force is discussed and its microscopic structure is also analyzed in terms of the multipole decomposition.

  17. Colors of Dynamically Associated Asteroid Pairs

    CERN Document Server

    Moskovitz, Nicholas

    2012-01-01

    Recent dynamical studies have identified pairs of asteroids that reside in nearly identical heliocentric orbits. Possible formation scenarios for these systems include dissociation of binary asteroids, collisional disruption of a single parent body, or spin-up and rotational fission of a rubble-pile. Aside from detailed dynamical analyses and measurement of rotational light curves, little work has been done to investigate the colors or spectra of these unusual objects. A photometric and spectroscopic survey was conducted to determine the reflectance properties of asteroid pairs. New observations were obtained for a total of 34 individual asteroids. Additional photometric measurements were retrieved from the Sloan Digital Sky Survey Moving Object Catalog. Colors or spectra for a total of 42 pair components are presented here. The main findings of this work are: (1) the components in the observed pair systems have the same colors within the uncertainties of this survey, and (2) the color distribution of asteroi...

  18. Comments on Coulomb pairing in aromatic hydrocarbons

    CERN Document Server

    Huber, D L

    2013-01-01

    Recently reported anomalies in the double-photonionization spectra of aromatic molecules such as benzene, naphthalene, anthracene and coronene are attributed to Coulomb-pair resonances of pi electrons.

  19. Four square mile survey pair count instructions

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This standard operating procedure (SOP) provides guidance for conducting bird pair count measurements on wetlands for the HAPETs Four-Square-Mile survey. This set of...

  20. Conjunctival Microbiome Changes Associated With Soft Contact Lens and Orthokeratology Lens Wearing.

    Science.gov (United States)

    Zhang, Haikun; Zhao, Fuxin; Hutchinson, Diane S; Sun, Wenfeng; Ajami, Nadim J; Lai, Shujuan; Wong, Matthew C; Petrosino, Joseph F; Fang, Jianhuo; Jiang, Jun; Chen, Wei; Reinach, Peter S; Qu, Jia; Zeng, Changqing; Zhang, Dake; Zhou, Xiangtian

    2017-01-01

    Usage of different types of contact lenses is associated with increased risk of sight-threatening complications. Changes in the ocular microbiome caused by contact lens wear are suggested to affect infection development in those individuals. To address this question, this study compares conjunctival microbial communities in contact lens wearers with those in noncontact lens wearers. Paired-end sequencing of the V3 region of the 16S rRNA gene was used to characterize the bacterial communities on the conjunctival surfaces of contact lens wearers and nonwearers. No differences in microbial diversity were detected between contact lens wearers and nonwearers. Nevertheless, some slight microbe variability was evident between these two different groups. Bacillus, Tatumella and Lactobacillus abundance was less in orthokeratology lens (OKL) wearers than in nonwearers. In soft contact lenses (SCL) wearers, Delftia abundance decreased whereas Elizabethkingia levels increased. The difference in the SCL and nonwearer group was smaller than that in the OKL group. Variations in the conjunctival taxonomic composition between SCL wearers were larger than those in other groups. Sex differences in the conjunctival microbiota makeup were only evident among nonwearers. Even though there were slight percentage changes between contact lens wearers and nonwearers in some microbes, there were no differences in their diversity. On the other hand, contact lens usage might cause relative abundance of some taxa to change. Our results will help assess whether or not conjunctival microbiome changes caused by contact lens wear affect infection risk.

  1. A refractive tilting-plate technique for measurement of dynamic contact angles.

    Science.gov (United States)

    Smedley, Gregory T; Coles, Donald E

    2005-06-01

    The contact angle is a critical parameter in liquid interface dynamics ranging from liquid spreading on a solid surface on earth to liquid motion in partially filled containers in space. A refractive tilting-plate technique employing a scanning laser beam is developed to conduct an experimental study of a moving contact line, with the intention of making accurate measurements of the contact angle. The technique shows promise as an accurate and potentially fully automated means to determine the velocity dependence of the contact angle at the intersection of the interface between two transparent fluids with a transparent solid surface. Ray tracing calculations are included to reinforce the measurement concept. The principal experiments were conducted at speeds ranging from 0.05 to 1.00 mm/s, both advancing and receding, using an immiscible liquid pair (nonane/formamide) in contact with glass. The contact angle was found to depend for practical purposes only on the sign of the velocity and not on its magnitude for the range of velocities studied. Other observations revealed a bimodal behavior of the contact line that depends on which liquid first contacts the glass, with resulting drift in the dynamic contact angle with time.

  2. Multidiagnostic analysis of ultrafast laser ablation of metals with pulse pair

    OpenAIRE

    LUNNEY, JAMES

    2010-01-01

    PUBLISHED Copper targets are irradiated in the ablation regime by pairs of equal, time-delayed collinear laser pulses separated on a timescale going from 2 ps to 2 ns. The ablation plume is characterized by ion probe diagnostic, fast imaging, and temporally and spatially resolved optical emission spectroscopy. The variation in the ablation efficiency with the delay between the pulses is analyzed by measuring the ablation crater profile with a contact profilometer. The second ...

  3. Array-Based Discovery of Aptamer Pairs

    Science.gov (United States)

    2014-12-11

    18460−18465. (25) Liu, Y.; Adams, J. D.; Turner, K.; Cochran, F. V.; Gambhir, S. S.; Soh, H. T. Lab Chip 2009, 9, 1033−1036. (26) Katilius, E.; Flores, C...discovery of aptamer pairs. We use microfluidic selection and high-throughput sequencing to obtain an enriched pool of aptamer sequences. Next, we...overcomes this problem to achieve efficient discovery of aptamer pairs. We use microfluidic selection and high- throughput sequencing to obtain an

  4. Alternative DNA base pairing through metal coordination.

    Science.gov (United States)

    Clever, Guido H; Shionoya, Mitsuhiko

    2012-01-01

    Base-pairing in the naturally occurring DNA and RNA oligonucleotide duplexes is based on π-stacking, hydrogen bonding, and shape complementarity between the nucleobases adenine, thymine, guanine, and cytosine as well as on the hydrophobic-hydrophilic balance in aqueous media. This complex system of multiple supramolecular interactions is the product of a long-term evolutionary process and thus highly optimized to serve its biological functions such as information storage and processing. After the successful implementation of automated DNA synthesis, chemists have begun to introduce artificial modifications inside the core of the DNA double helix in order to study various aspects of base pairing, generate new base pairs orthogonal to the natural ones, and equip the biopolymer with entirely new functions. The idea to replace the hydrogen bonding interactions with metal coordination between ligand-like nucleosides and suitable transition metal ions culminated in the development of a plethora of artificial base-pairing systems termed "metal base-pairs" which were shown to strongly enhance the DNA duplex stability. Furthermore, they show great potential for the use of DNA as a molecular wire in nanoscale electronic architectures. Although single electrons have proven to be transmitted by natural DNA over a distance of several base pairs, the high ohmic resistance of unmodified oligonucleotides was identified as a serious obstacle. By exchanging some or all of the Watson-Crick base pairs in DNA with metal complexes, this problem may be solved. In the future, these research efforts are supposed to lead to DNA-like materials with superior conductivity for nano-electronic applications. Other fields of potential application such as DNA-based supramolecular architecture and catalysis may be strongly influenced by these developments as well. This text is meant to illustrate the basic concepts of metal-base pairing and give an outline over recent developments in this field.

  5. Subthreshold pair production in short laser pulses

    OpenAIRE

    Nousch, T.; Seipt, D.; Kampfer, B.; Titov, A. I.

    2012-01-01

    The $e^+e^-$ pair production by a probe photon traversing a linearly polarized laser pulse is treated as generalized nonlinear Breit-Wheeler process. For short laser pulses with very few oscillations of the electromagnetic field we find below the perturbative weak-field threshold $\\sqrt{s} = 2m$ a similar enhancement of the pair production rate as for circular polarization. The strong subthreshold enhancement is traced back to the finite bandwidth of the laser pulse. A folding model is develo...

  6. Marcus Theory of Ion-Pairing

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Santanu; Baer, Marcel D.; Mundy, Christopher J.; Schenter, Gregory K.

    2017-08-08

    We present a theory for ion pair dissociation and association, motivated by the concepts of the Marcus theory of electron transfer. Despite the extensive research on ion-pairing in many chemical and biological processes, much can be learned from the exploration of collective reaction coordinates. To this end, we explore two reaction coordinates, ion pair distance and coordination number. The study of the correlation between these reaction coordinates provides a new insight into the mechanism and kinetics of ion pair dissociation and association in water. The potential of mean force on these 2D-surfaces computed from molecular dynamics simulations of different monovalent ion pairs reveal a Marcus-like mechanism for ion-pairing: Water molecules rearrange forming an activated coordination state prior to ion pair dissociation or association, followed by relaxation of the coordination state due to further water rearrangement. Like Marcus theory, we find the existence of an inverted region where the transition rates are slower with increasing exergonicity. This study provides a new perspective for the future investigations of ion-pairing and transport. SR, CJM, and GKS were supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. MDB was supported by MS3 (Materials Synthesis and Simulation Across Scales) Initiative, a Laboratory Directed Research and Development Program at Pacific Northwest National Laboratory (PNNL). The research was performed using PNNL Institutional Computing. PNNL is a multi-program national laboratory operated by Battelle for the U.S. Department of Energy.

  7. Contact metallurgy optimization for ohmic contacts to InP

    DEFF Research Database (Denmark)

    Clausen, Thomas; Pedersen, Arne Skyggebjerg; Leistiko, Otto

    1991-01-01

    AuGeNi and AuZnNi metallizations to n- and p-InP were studied as a function of the annealing temperature in a Rapid Thermal Annealing (RTA) system. For n-InP (S:8×1018cm-3) a broad minimum existed from 385°C to 500°C, in which the specific contact resistance, rc, was about 10-7 ¿cm2. The lowe...

  8. Pair Production in Low Luminosity Galactic Nuclei

    CERN Document Server

    Moscibrodzka, Monika; Dolence, Joshua C; Shiokawa, Hotaka

    2011-01-01

    Electron-positron pairs may be produced near accreting black holes by a variety of physical processes, and the resulting pair plasma may be accelerated and collimated into a relativistic jet. Here we use a self-consistent dynamical and radiative model to investigate pair production by \\gamma\\gamma collisions in weakly radiative accretion flows around a black hole of mass M and accretion rate \\dot{M}. Our flow model is drawn from general relativistic magnetohydrodynamic simulations, and our radiation field is computed by a Monte Carlo transport scheme assuming the electron distribution function is thermal. We argue that the pair production rate scales as r^{-6} M^{-1} \\dot{M}^{6}. We confirm this numerically and calibrate the scaling relation. This relation is self-consistent in a wedge in M, \\dot{M} parameter space. If \\dot{M} is too low the implied pair density over the poles of the black hole is below the Goldreich-Julian density and \\gamma\\gamma pair production is relatively unimportant; if \\dot{M} is too ...

  9. Migration of helium-pair in metals

    Energy Technology Data Exchange (ETDEWEB)

    Cao, J.L.; Geng, W.T., E-mail: geng@ustb.edu.cn

    2016-09-15

    We have carried out a first-principles density functional theory investigation into the migration of both a single interstitial He and an interstitial He-pair in Fe, Mo, W, Cu, Pd, and Pt. We find the migration trajectories and barriers are determined predominantly by low-energy He-pair configurations which depend mainly on the energy state of a single He in different interstices. The migration barrier for a He-pair in bcc metals is always slightly higher than for a single He. Configurations of a He-pair in fcc metals are very complicated, due to the existence of interstitial sites with nearly identical energy for a single He. The migration barrier for a He-pair is slightly lower than (in Cu), or similar to (in Pd and Pt) a single He. The collective migrations of a He-pair are ensured by strong He−He interactions with strength-versus-distance forms resembling chemical bonds and can be described with Morse potentials.

  10. Seniority zero pair coupled cluster doubles theory.

    Science.gov (United States)

    Stein, Tamar; Henderson, Thomas M; Scuseria, Gustavo E

    2014-06-07

    Coupled cluster theory with single and double excitations accurately describes weak electron correlation but is known to fail in cases of strong static correlation. Fascinatingly, however, pair coupled cluster doubles (p-CCD), a simplified version of the theory limited to pair excitations that preserve the seniority of the reference determinant (i.e., the number of unpaired electrons), has mean field computational cost and is an excellent approximation to the full configuration interaction (FCI) of the paired space provided that the orbital basis defining the pairing scheme is adequately optimized. In previous work, we have shown that optimization of the pairing scheme in the seniority zero FCI leads to a very accurate description of static correlation. The same conclusion extends to p-CCD if the orbitals are optimized to make the p-CCD energy stationary. We here demonstrate these results with numerous examples. We also explore the contributions of different seniority sectors to the coupled cluster doubles (CCD) correlation energy using different orbital bases. We consider both Hartree-Fock and Brueckner orbitals, and the role of orbital localization. We show how one can pair the orbitals so that the role of the Brueckner orbitals at the CCD level is retained at the p-CCD level. Moreover, we explore ways of extending CCD to accurately describe strongly correlated systems.

  11. Formation of asteroid pairs by rotational fission.

    Science.gov (United States)

    Pravec, P; Vokrouhlický, D; Polishook, D; Scheeres, D J; Harris, A W; Galád, A; Vaduvescu, O; Pozo, F; Barr, A; Longa, P; Vachier, F; Colas, F; Pray, D P; Pollock, J; Reichart, D; Ivarsen, K; Haislip, J; Lacluyze, A; Kusnirák, P; Henych, T; Marchis, F; Macomber, B; Jacobson, S A; Krugly, Yu N; Sergeev, A V; Leroy, A

    2010-08-26

    Pairs of asteroids sharing similar heliocentric orbits, but not bound together, were found recently. Backward integrations of their orbits indicated that they separated gently with low relative velocities, but did not provide additional insight into their formation mechanism. A previously hypothesized rotational fission process may explain their formation-critical predictions are that the mass ratios are less than about 0.2 and, as the mass ratio approaches this upper limit, the spin period of the larger body becomes long. Here we report photometric observations of a sample of asteroid pairs, revealing that the primaries of pairs with mass ratios much less than 0.2 rotate rapidly, near their critical fission frequency. As the mass ratio approaches 0.2, the primary period grows long. This occurs as the total energy of the system approaches zero, requiring the asteroid pair to extract an increasing fraction of energy from the primary's spin in order to escape. We do not find asteroid pairs with mass ratios larger than 0.2. Rotationally fissioned systems beyond this limit have insufficient energy to disrupt. We conclude that asteroid pairs are formed by the rotational fission of a parent asteroid into a proto-binary system, which subsequently disrupts under its own internal system dynamics soon after formation.

  12. Comparative histopathology of vitiligo and contact depigmentation

    Directory of Open Access Journals (Sweden)

    Mittal R

    1992-01-01

    Full Text Available Fifteen cases of vitiligo and 12 cases of contact depigmentation were compared histopathologically. Incontinence of melanin in dermis was seen in 33% cases of contact depigmentation and 6.6% cases of vitiligo. Mononuclear infiltrate was more in contact depigmentation and had lichenoid character at places. Vasculitis with perivascular mononuclear infiltrate was seen in all cases of contact depigmentation. It is proposed that chemicals responsible for contact destruction of melanocytes.

  13. Hydrogen bonding mediated ion pairs of some aprotic ionic liquids and their structural transition in aqueous solution

    Institute of Scientific and Technical Information of China (English)

    Huiyong Wang; Miao Liu; Yuling Zhao; Xiaopeng Xuan; Yang Zhao; Jianji Wang

    2017-01-01

    Ion pair speciation of ionic liquids (ILs) has an important effect on the physical and chemical properties of ILs and recognition of the structure of ion pairs in solution is essential.It has been reported that ion pairs of some ILs can be formed by hydrogen bonding interactions between cations and anions of them.Considering the fact that far-IR (FIR) spectroscopy is a powerful tool in indicating the intermolecular and intramolecular hydrogen bonding,in this work,this spectroscopic technique has been combined with molecular dynamic (MD) simulation and nuclear magnetic resonance hydrogen spectroscopy (1H NMR) to investigate ion pairs ofaprotic ILs [Bmim][NO3],[BuPy][NO3],[Pyr14][NO3],[PP14][NO3] and [Bu-choline][NO3] in aqueous IL mixtures.The FIR spectra have been assigned with the aid of density functional theory (DFT) calculations,and the results are used to understand the effect of cationic nature on the structure of ion pairs.It is found that contact ion pairs formed in the neat aprotic ILs by hydrogen bonding interactions between cation and anion,were still maintained in aqueous solutions up to high water mole fraction (say 0.80 for [BuPy] [NO3]).When water content was increased to a critical mole fraction of water (say 0.83 for [BuPy] [NO3]),the contact ion pairs could be transformed into solvent-separated ion pairs due to the formation of the hydrogen bonding between ions and water.With the further dilution of the aqueous ILs solution,the solvent-separated ion pairs was finally turned into free cations and free anions (fully hydrated cations or anions).The concentrations of the ILs at which the contact ion pairs were transformed into solvent-separated ion pairs and solvent-separated ion pairs were transformed into free ions (fully hydrated ion) were dependent on the cationic structures.These information provides direct spectral evidence for ion pair structures of the aprotic ILs in aqueous.solution.MD simulation and 1H NMR results support the conclusion

  14. Fundamental aspects of recoupled pair bonds. I. Recoupled pair bonds in carbon and sulfur monofluoride

    Energy Technology Data Exchange (ETDEWEB)

    Dunning, Thom H., E-mail: thdjr@uw.edu; Xu, Lu T.; Takeshita, Tyler Y. [Department of Chemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews Avenue, Urbana, Illinois 61801 (United States)

    2015-01-21

    The number of singly occupied orbitals in the ground-state atomic configuration of an element defines its nominal valence. For carbon and sulfur, with two singly occupied orbitals in their {sup 3}P ground states, the nominal valence is two. However, in both cases, it is possible to form more bonds than indicated by the nominal valence—up to four bonds for carbon and six bonds for sulfur. In carbon, the electrons in the 2s lone pair can participate in bonding, and in sulfur the electrons in both the 3p and 3s lone pairs can participate. Carbon 2s and sulfur 3p recoupled pair bonds are the basis for the tetravalence of carbon and sulfur, and 3s recoupled pair bonds enable sulfur to be hexavalent. In this paper, we report generalized valence bond as well as more accurate calculations on the a{sup 4}Σ{sup −} states of CF and SF, which are archetypal examples of molecules that possess recoupled pair bonds. These calculations provide insights into the fundamental nature of recoupled pair bonds and illustrate the key differences between recoupled pair bonds formed with the 2s lone pair of carbon, as a representative of the early p-block elements, and recoupled pair bonds formed with the 3p lone pair of sulfur, as a representative of the late p-block elements.

  15. Microevolution between paired antral and paired antrum and corpus Helicobacter pylori isolates recovered from individual patients.

    Science.gov (United States)

    Carroll, Ian M; Ahmed, Niyaz; Beesley, Sarah M; Khan, Aleem A; Ghousunnissa, Sheikh; Moráin, Colm A O; Habibullah, C M; Smyth, Cyril J

    2004-07-01

    Sequence variations located at the signal sequence and mid-region within the vacA gene, the 3'-end of the cagA gene, the indel motifs at the 3'-end of the cag pathogenicity island and the regions upstream of the vacA and ribA genes were determined by PCR in 19 paired antral or antrum and corpus Helicobacter pylori isolates obtained at the same endoscopic session, and three antral pairs taken sequentially. Random amplification of polymorphic DNA (RAPD)-PCR and fluorescent amplified fragment length polymorphism (FAFLP)-PCR fingerprinting were applied to these paired clinical isolates. The FAFLP-PCR profiles generated were phylogenetically analysed. For the 22 paired isolates there were no differences within pairs at five of the genetic loci studied. However, six pairs of isolates (27%), of which four were antrum and corpus pairs, showed differences in the numbers of repeats located at the 3'-end of the cagA gene. RAPD-PCR fingerprinting showed that 16 (73%) pairs, nine of which were antrum and corpus pairs, possessed identical profiles, while six (27%) displayed distinctly different profiles, indicating mixed infections. Three of the six pairs showing differences at the 3'-end of the cagA gene yielded identical RAPD-PCR fingerprints. FAFLP-PCR fingerprinting and phylogenetic analysis revealed that all 16 pairs that displayed identical RAPD-PCR profiles had highly similar, but not identical, fingerprints, demonstrating that these pairs were ancestrally related but had undergone minor genomic alterations. Two antrum and corpus pairs of isolates, within the latter group, were isolates obtained from two siblings from the same family. This analysis demonstrated that each sibling was colonized by ancestrally related strains that exhibited differences in vacA genotype characteristics.

  16. PREFACE: Non-contact AFM Non-contact AFM

    Science.gov (United States)

    Giessibl, Franz J.; Morita, Seizo

    2012-02-01

    This special issue is focussed on high resolution non-contact atomic force microscopy (AFM). Non-contact atomic force microscopy was established approximately 15 years ago as a tool to image conducting and insulating surfaces with atomic resolution. Since 1998, an annual international conference has taken place, and although the proceedings of these conferences are a useful source of information, several key developments warrant devoting a special issue to this subject. In the theoretic field, the possibility of supplementing established techniques such as scanning tunneling microscopy (STM) and Kelvin probe microscopy with atomically resolved force micrsoscopy poses many challenges in the calculation of contrast and contrast reversal. The surface science of insulators, self-assembled monolayers and adsorbates on insulators is a fruitful field for the application of non-contact AFM: several articles in this issue are devoted to these subjects. Atomic imaging and manipulation have been pioneered using STM, but because AFM allows the measurement of forces, AFM has had a profound impact in this field as well. Three-dimensional force spectroscopy has allowed many important insights into surface science. In this issue a combined 3D tunneling and force microscopy is introduced. Non-contact AFM typically uses frequency modulation to measure force gradients and was initially used mainly in a vacuum. As can be seen in this issue, frequency modulation is now also used in ambient conditions, allowing better spatial and force resolution. We thank all of the contributors for their time and efforts in making this special issue possible. We are also very grateful to the staff of IOP Publishing for handling the administrative aspects and for steering the refereeing process. Non-contact AFM contents Relation between the chemical force and the tunnelling current in atomic point contacts: a simple model Pavel Jelínek, Martin Ondrácek and Fernando Flores Theoretical simulation of

  17. SELF-REGULATION AND INTERNAL AND EXTERNAL PARAMETERS IN METAL BAND FRICTION PAIRS-SHOE BRAKES (PART 1

    Directory of Open Access Journals (Sweden)

    Volchenko N. A.

    2014-09-01

    Full Text Available We've illustrated self-regulation (based on the work function of the metal friction element and the regula-tion by quasiconstant unit loads on the contact patch of micropoints of metal-polymer friction pairs of band-block brake for the evaluation of process of their normal wear

  18. HIV-1 sequence variation between isolates from mother-infant transmission pairs

    Energy Technology Data Exchange (ETDEWEB)

    Wike, C.M.; Daniels, M.R.; Furtado, M.; Wolinsky, M.; Korber, B.; Hutto, C.; Munoz, J.; Parks, W.; Saah, A.

    1991-12-31

    To examine the sequence diversity of human immunodeficiency virus type 1 (HIV-1) between known transmission sets, sequences from the V3 and V4-V5 region of the env gene from 4 mother-infant pairs were analyzed. The mean interpatient sequence variation between isolates from linked mother-infant pairs was comparable to the sequence diversity found between isolates from other close contacts. The mean intrapatient variation was significantly less in the infants` isolates then the isolates from both their mothers and other characterized intrapatient sequence sets. In addition, a distinct and characteristic difference in the glycosylation pattern preceding the V3 loop was found between each linked transmission pair. These findings indicate that selection of specific genotypic variants, which may play a role in some direct transmission sets, and the duration of infection are important factors in the degree of diversity seen between the sequence sets.

  19. Study of lubrication behavior of pure water for hydrophobic friction pair

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The perfluorooctyltrichlorosilane molecular layer was self-assembled on glass plate. The tribological properties of the molecular layer in water were studied with the method of ball on disk. An interesting phenomenon was found that low friction coefficients of 0.02―0.08 were obtained when the friction pair was lubricated with only a water droplet. Whereas, when the friction pair was encircled with large amount of water or fully immersed in water, the friction coefficient was higher than that under a droplet lubrication. A mechanism of water droplet lubrication was proposed that the surface tension caused by the solid-liquid-air three-phase interface makes water molecules enter into the contact zone, which separates the two friction surfaces and provides a low friction coefficient. However, water film can hardly form when more water encircles the friction pair, due to the attraction between water molecules.

  20. Clinical update on contact allergy

    DEFF Research Database (Denmark)

    Uter, Wolfgang; Johansen, Jeanne Duus; Orton, David I

    2005-01-01

    PURPOSE OF REVIEW: The aim of this article is to review recent findings in contact allergy, regarding clinical research. RECENT FINDINGS: The biocide methyldibromo glutaronitrile was identified to be an important sensitizer. Subsequently, it was banned from leave-on cosmetics in the European Union....... Another group of important allergens that have been studied extensively included the fragrances oak moss absolute, isoeugenol, hydroxyisohexyl 3-cyclohexene carboxaldehyde and farnesol. A new fragrance mix II has been developed for standard testing, which includes the two latter compounds. Dose response...... studies have demonstrated broad individual variation of elicitation thresholds, dependent on the allergen concentration during induction, and other factors. Some unsuspected routes of exposure to allergens include oral, inhalational, connubial or airborne contact. Experimental studies provide...

  1. Remedial Action Contacts Directory - 1997

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-05-01

    This document, which was prepared for the US Department of Energy (DOE) Office of Environmental Restoration (ER), is a directory of 2628 individuals interested or involved in environmental restoration and/or remedial actions at radioactively contaminated sites. This directory contains a list of mailing addresses and phone numbers of DOE operations, area, site, project, and contractor offices; an index of DOE operations, area, site, project, and contractor office sorted by state; a list of individuals, presented by last name, facsimile number, and e-mail address; an index of affiliations presented alphabetically, with individual contacts appearing below each affiliation name; and an index of foreign contacta sorted by country and affiliation. This document was generated from the Remedial Action Contacts Database, which is maintained by the Remedial Action Program Information Center (RAPIC).

  2. Sensing with Superconducting Point Contacts

    Directory of Open Access Journals (Sweden)

    Argo Nurbawono

    2012-05-01

    Full Text Available Superconducting point contacts have been used for measuring magnetic polarizations, identifying magnetic impurities, electronic structures, and even the vibrational modes of small molecules. Due to intrinsically small energy scale in the subgap structures of the supercurrent determined by the size of the superconducting energy gap, superconductors provide ultrahigh sensitivities for high resolution spectroscopies. The so-called Andreev reflection process between normal metal and superconductor carries complex and rich information which can be utilized as powerful sensor when fully exploited. In this review, we would discuss recent experimental and theoretical developments in the supercurrent transport through superconducting point contacts and their relevance to sensing applications, and we would highlight their current issues and potentials. A true utilization of the method based on Andreev reflection analysis opens up possibilities for a new class of ultrasensitive sensors.

  3. Heat transport through atomic contacts.

    Science.gov (United States)

    Mosso, Nico; Drechsler, Ute; Menges, Fabian; Nirmalraj, Peter; Karg, Siegfried; Riel, Heike; Gotsmann, Bernd

    2017-02-06

    Heat transport and dissipation at the nanoscale severely limit the scaling of high-performance electronic devices and circuits. Metallic atomic junctions serve as model systems to probe electrical and thermal transport down to the atomic level as well as quantum effects that occur in one-dimensional (1D) systems. Whereas charge transport in atomic junctions has been studied intensively in the past two decades, heat transport remains poorly characterized because it requires the combination of a high sensitivity to small heat fluxes and the formation of stable atomic contacts. Here we report heat-transfer measurements through atomic junctions and analyse the thermal conductance of single-atom gold contacts at room temperature. Simultaneous measurements of charge and heat transport reveal the proportionality of electrical and thermal conductance, quantized with the respective conductance quanta. This constitutes a verification of the Wiedemann-Franz law at the atomic scale.

  4. Contact dermatitis caused by preservatives.

    Science.gov (United States)

    Yim, Elizabeth; Baquerizo Nole, Katherine L; Tosti, Antonella

    2014-01-01

    Preservatives are biocidal chemicals added to food, cosmetics, and industrial products to prevent the growth of microorganisms. They are usually nontoxic and inexpensive and have a long shelf life. Unfortunately, they commonly cause contact dermatitis. This article reviews the most important classes of preservatives physicians are most likely to encounter in their daily practice, specifically isothiazolinones, formaldehyde and formaldehyde-releasers, iodopropynyl butylcarbamate, methyldibromoglutaronitrile, and parabens. For each preservative mentioned, the prevalence of sensitization, clinical presentation of contact dermatitis, patch testing concentrations, cross reactions, and related legislation will be discussed. Mandatory labeling of preservatives is required in some countries, but not required in others. Until policies are made, physicians and patients must be proactive in identifying potential sensitizers and removing their use. We hope that this article will serve as a guide for policy makers in creating legislation and future regulations on the use and concentration of certain preservatives in cosmetics and industrial products.

  5. Allergic contact dermatitis from carmine.

    Science.gov (United States)

    Shaw, Daniel W

    2009-01-01

    A 28-year-old woman developed allergic contact dermatitis within 6 to 24 hours exclusively after using carmine-containing eyeshadows and lipsticks. She had both a positive patch test result and a positive antecubital repeated open application test result with carmine 2.5% in petrolatum. Thirty other patients had negative patch test results. Carmine is a widely used pigment derived from gravid cochineal insects. Carminic acid is the source of its color. Only two previous publications describing allergic contact dermatitis from carmine could be found. The ingredient in carmine causing these delayed hypersensitivity reactions has not been studied. In contrast, there are numerous reports of immediate hypersensitivity reactions from carmine, mostly from its use in foods and beverages but also from cosmetics and pharmaceuticals. These are immunoglobulin E-mediated reactions directed against cochineal proteins.

  6. DNA fingerprinting of Mycobacterium tuberculosis isolates from epidemiologically linked case pairs.

    Science.gov (United States)

    Bennett, Diane E; Onorato, Ida M; Ellis, Barbara A; Crawford, Jack T; Schable, Barbara; Byers, Robert; Kammerer, J Steve; Braden, Christopher R

    2002-11-01

    DNA fingerprinting was used to evaluate epidemiologically linked case pairs found during routine tuberculosis (TB) contact investigations in seven sentinel sites from 1996 to 2000. Transmission was confirmed when the DNA fingerprints of source and secondary cases matched. Of 538 case pairs identified, 156 (29%) did not have matching fingerprints. Case pairs from the same household were no more likely to have confirmed transmission than those linked elsewhere. Case pairs with unconfirmed transmission were more likely to include a smear-negative source case (odds ratio [OR] 2.0) or a foreign-born secondary case (OR 3.4) and less likely to include a secondary case <15 years old (OR 0.3). Our study suggests that contact investigations should focus not only on the household but also on all settings frequented by an index case. Foreign-born persons with TB may have been infected previously in high-prevalence countries; screening and preventive measures recommended by the Institute of Medicine could prevent TB reactivation in these cases.

  7. Immunology of allergic contact dermatitis.

    Science.gov (United States)

    Tončić, Ružica Jurakić; Lipozenčić, Jasna; Martinac, Ivana; Gregurić, Sanja

    2011-01-01

    Allergic contact dermatitis (ACD) is a T-cell mediated skin inflammation caused by repeated skin exposure to contact allergens. This review summarizes current knowledge on the immunology of ACD. Different phases in ACD are distinguished, i.e. sensitization, elicitation and resolution phases. We discuss contact allergen presentation and the central role of antigen presenting cells during sensitization phase. There is an extremely complex interaction of different kinds of immune cells, such as antigen presenting cells, T, B, NK lymphocytes, keratinocytes (KCs), endothelium, mast cells (MCs) and platelets, and this complex interaction is guided through orchestration of numerous cytokines and chemokines. The role of adaptive immunity has been recognized in contact hypersensitivity but we also discuss the important role of some parts of innate immunity such as natural killer T lymphocytes (NKT) and complement system. Cooperation of innate and adaptive immunity, in this case NK cells and B cells, initiates elicitation phase by complement cascade activation, vasoactive substance release and endothelial activation. KCs are not only innocent bystanders, on the contrary, they are involved in all phases of ACD, from the early phase of initiation through sending "danger" signals and activation of innate immunity, through their role in Langerhans cells (LCs) migration, T-cell trafficking, through the height of the inflammatory phase with direct interactions with epidermotropic T-cells, and finally through the resolution phase with the production of anti-inflammatory cytokines and tolerogenic presentation to effector T-cells. Th-1 and Th-17 cells are the main effector cells responsible for tissue damage. At the end, we point out several subsets of T regulatory cells, which exert down-regulatory function and regulate the magnitude and duration of inflammatory reaction.

  8. Allergic contact dermatitis to Alstroemeria.

    Science.gov (United States)

    Marks, J G

    1988-06-01

    Two female florists developed dermatitis of the fingertips. Patch testing revealed allergic contact dermatitis to the flower, Alstroemeria, used in floral arrangements. They had positive patch tests to portions of Alstroemeria, and to tuliposide A, the allergen in this plant. Vinyl gloves were not helpful since tuliposide A readily penetrates through these gloves. Nitrile gloves may be protective since they prevented positive patch test to tuliposide A.

  9. Rolling contact fatigue of ceramics

    OpenAIRE

    Hadfield, Mark

    1993-01-01

    This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University. Ceramic/ceramic and ceramic/steel contacts under lubricated rolling conditions are studied. This work is of interest to ball bearing manufacturers as the use of ceramics in the design of these components has some advantages over traditional bearing-steel materials. Low density and increased stiffness are the mechanical properties which gas-turbine and machine tool manufacturers are most likel...

  10. Contact | Office of Cancer Genomics

    Science.gov (United States)

    For more information about the Office of Cancer Genomics, please contact: Office of Cancer Genomics National Cancer Institute 31 Center Drive, 10A07 Bethesda, Maryland 20892-2580 Phone: (301) 451-8027 Fax: (301) 480-4368 Email: ocg@mail.nih.gov *Please note that this site will not function properly in Internet Explorer unless you completely turn off the Compatibility View*

  11. [Contact allergies in medical occupations].

    Science.gov (United States)

    Rustemeyer, T; Pilz, B; Frosch, P J

    1994-12-01

    Based on reports in the literature, data from the information network of German dermatology centres (Informationsverbund Dermatologischer Kliniken) and the authors own findings, a review is presented on prevalence, clinical picture and causative agents of contact allergic dermatoses in health care professions. In 1991 the proportion of suspected occupational diseases in the health care professions (including hairdressers) represented by cases of dermatitis, as reported to the responsible insurance institution, reached 72% of the total for the year (7287 out of 10127). Every 20th to 40th case was recognized as an occupational dermatosis according to German law. Accurate figures on incidence are scarce; for dentists an incidence of 0.11% has been calculated. The risk of developing occupational hand eczema has been shown to be at least three times higher for nurses than for other so-called dry professions. For persons engaged in the personal care of the ill and the elderly, relevant occupational allergens were found to be benzalkonium chloride and aldehydes in disinfectants, as well as rubber accelerators such as thiuram mix. Latex contact urticaria has increasing significance for medical personnel, with prevalence rates of sensitization between 4.5% and 10.7%. Among physicians, contact allergies to thiuram mix were found to be dominant (12.9%). For surgeons and orthopaedic surgeons, methyl methacrylate as a constituent of bone cement is of great importance. Various esters of acrylic acid and methacrylic acid are important sensitizers in the dental professions, particularly in heavily exposed dental laboratory technicians. Only a few gloves protect against these types of sensitizers. Sensitizations by medicaments can be avoided in most cases by reducing direct skin contact, as practiced with penicillin or ispaghula powder. Strategies of prevention include information of atopics regarding the increase in occupational dermatitis, the regular use of barrier creams

  12. TDDFT study of the polarity controlled ion-pair separation in an excited-state proton transfer reaction.

    Science.gov (United States)

    Liu, Yu-Hui; Mehata, Mohan Singh; Lan, Sheng-Cheng

    2014-07-15

    6-Hydroxyquinoline (6HQ) is an ideal photoacid system for exploring excited-state proton transfer (ESPT) reactions. We have previously (Mahata et al. (2002)) shown that the ESPT reaction between 6HQ and trimethylamine (TMA) leads to an "unusual" emission in the 440-450 nm range, containing two decay components (∼5 ns and ∼12 ns). The observed results suggest the presence of a contact ion-pair and a solvent separated ion-pair. In this work, density functional theory (DFT) and time-dependent density functional theory (TD-DFT) have been employed to study the nature of the contact ion-pair formed between 6HQ and TMA and to determine why the decay component ∼12 ns is absent in a non-polar solvent. Calculations of the hydrogen-bonded complexes formed between 6HQ and TMA and its ESPT reaction product, namely 6HQ-TMA and 6HQ-TMA-PT, respectively, have been carried out, both in the electronic ground and excited states. Moreover, by using the CPCM model, different dielectric constants have been introduced into the calculations. On increasing the dielectric constant, the hydrogen bond in 6HQ-TMA-PT becomes weaker and the hydrogen bond length becomes larger; this effectively facilitates the proton transfer reaction and formation of separated ion-pair. Thus, the separation and diffusion of the contact ion-pair can be controlled by changing the polarity of the surroundings.

  13. Generalized pairing strategies-a bridge from pairing strategies to colorings

    Directory of Open Access Journals (Sweden)

    Győrffy Lajos

    2016-12-01

    Full Text Available In this paper we define a bridge between pairings and colorings of the hypergraphs by introducing a generalization of pairs called t-cakes for t ∈ ℕ, t ≥ 2. For t = 2 the 2-cakes are the same as the well-known pairs of system of distinct representatives, that can be turned to pairing strategies in Maker-Breaker hypergraph games, see Hales and Jewett [12]. The two-colorings are the other extremity of t-cakes, in which the whole ground set of the hypergraph is one big cake that we divide into two parts (color classes. Starting from the pairings (2-cake placement and two-colorings we define the generalized t-cake placements where we pair p elements by q elements (p, q ∈ ℕ, 1 ≤ p, q < t, p + q = t.

  14. Body contact and body language

    DEFF Research Database (Denmark)

    Winther, Helle Dagmar

    2008-01-01

    and the boundaries between self and world. In western societies, the modern premises for contact are in some ways developing from close contact to virtual communication. With this breadth of perspective in mind, the ques­tion is whether conscious and experimental work with body contact and body language in move......­ment psychology and education provide potential for intense personal develop­ment as well as for social and cultural learning processes. This performative research project originates from the research project entitled, Movement Psy­chol­ogy: The Language of the Body and the Psy­chol­ogy of Movement based...... on the Dance Therapy Form Dansergia. The author, who is a practi­tioner-researcher, is methodologically inspir­ed by phenomenology, performative methods and a narrative and auto-ethnographic approach. The project will be presented in an organic, cre­at­ive and performative way. Through a moving dia...

  15. Intracavity contacts for nitride based monolithic surface emitters by focused ion beam processing

    Energy Technology Data Exchange (ETDEWEB)

    Fandrich, Malte; Dartsch, Heiko; Tessarek, Christian; Aschenbrenner, Timo; Hommel, Detlef [Institut fuer Festkoerperphysik - Halbleiterepitaxie, Universitaet Bremen (Germany)

    2010-07-01

    The realization of electrically driven nitride based vertical-cavity surface-emitting lasers (VCSELs) is challenging due to limitations in the conductivity of the distributed Bragg reflectors (DBRs). Therefore monolithic approaches are based on a doped cavity and one or two undoped DBRs. This requires the use of technologically complex intracavity contacts. The presented process yields intracavity contacts applicable to monolithically grown VCSEL structures. Initially mesas are structured by photolithography and chemical assisted ion beam etching. The precise structuring of the prestructured mesas is performed in a focused ion beam system (FIB), where the micropillars are thinned stepwise down to a diameter of 0.5-5 {mu}m. The contacting of the pillars is realized by FIB deposited metal and insulator structures. Insulator separated Pt ring-contacts connect the micropillars with large-scale contact pads. This procedure was applied to a VCSEL structure consisting of a bottom AlInN/GaN-DBR with 40 pairs, a p/n-doped 5 {lambda} GaN-cavity with embedded InGaN quantum dots and a top 10 pair AlInN/GaN-DBR. The developed contacting structure enables a current up to 15 mA through the cavity which documents the capability for the electrical operation of VCSEL devices.

  16. Vertical Soil Profiling Using a Galvanic Contact Resistivity Scanning Approach

    Directory of Open Access Journals (Sweden)

    Luan Pan

    2014-07-01

    Full Text Available Proximal sensing of soil electromagnetic properties is widely used to map spatial land heterogeneity. The mapping instruments use galvanic contact, capacitive coupling or electromagnetic induction. Regardless of the type of instrument, the geometrical configuration between signal transmitting and receiving elements typically defines the shape of the depth response function. To assess vertical soil profiles, many modern instruments use multiple transmitter-receiver pairs. Alternatively, vertical electrical sounding can be used to measure changes in apparent soil electrical conductivity with depth at a specific location. This paper examines the possibility for the assessment of soil profiles using a dynamic surface galvanic contact resistivity scanning approach, with transmitting and receiving electrodes configured in an equatorial dipole-dipole array. An automated scanner system was developed and tested in agricultural fields with different soil profiles. While operating in the field, the distance between current injecting and measuring pairs of rolling electrodes was varied continuously from 40 to 190 cm. The preliminary evaluation included a comparison of scan results from 20 locations to shallow (less than 1.2 m deep soil profiles and to a two-layer soil profile model defined using an electromagnetic induction instrument.

  17. Vertical soil profiling using a galvanic contact resistivity scanning approach.

    Science.gov (United States)

    Pan, Luan; Adamchuk, Viacheslav I; Prasher, Shiv; Gebbers, Robin; Taylor, Richard S; Dabas, Michel

    2014-07-23

    Proximal sensing of soil electromagnetic properties is widely used to map spatial land heterogeneity. The mapping instruments use galvanic contact, capacitive coupling or electromagnetic induction. Regardless of the type of instrument, the geometrical configuration between signal transmitting and receiving elements typically defines the shape of the depth response function. To assess vertical soil profiles, many modern instruments use multiple transmitter-receiver pairs. Alternatively, vertical electrical sounding can be used to measure changes in apparent soil electrical conductivity with depth at a specific location. This paper examines the possibility for the assessment of soil profiles using a dynamic surface galvanic contact resistivity scanning approach, with transmitting and receiving electrodes configured in an equatorial dipole-dipole array. An automated scanner system was developed and tested in agricultural fields with different soil profiles. While operating in the field, the distance between current injecting and measuring pairs of rolling electrodes was varied continuously from 40 to 190 cm. The preliminary evaluation included a comparison of scan results from 20 locations to shallow (less than 1.2 m deep) soil profiles and to a two-layer soil profile model defined using an electromagnetic induction instrument.

  18. Theoretical study of pair density wave superconductors

    Science.gov (United States)

    Zheng, Zhichao

    In conventional superconductors, the Cooper pairs are formed from quasiparticles. We explore another type of superconducting state, a pair density wave (PDW) order, which spontaneously breaks some of the translational and point group symmetries. In a PDW superconductor, the order parameter is a periodic function of the center-of-mass coordinate, and the spatial average value of the superconducting order parameter vanishes. In the early 1960s, following the success of the BCS theory of superconductivity, Fulde and Ferrell and Larkin and Ovchinnikov (FFLO) developed theories of inhomogeneous superconducting states. Because of this Zeeman splitting in a magnetic field, the Cooper pairs having a nonzero center-of-mass momentum are more stable than the normal pairing, leading to the FFLO state. Experiments suggest possible occurrence of the FFLO state in the heavy-fermion compound CeCoIn5, and in quasi-low-dimensional organic superconductors. FFLO phases have also been argued to be of importance in understanding ultracold atomic Fermi gases and in the formation of color superconductivity in high density quark matter. In all Fermi superfluids known at the present time, Cooper pairs are composed of particles with spin 1/2. The spin component of a pair wave function can be characterized by its total spin S = 0 (singlet) and S = 1 (triplet). In the discovered broken inversion superconductors CePt3Si, Li2Pt3B, and Li2Pd3B, the magnetic field leads to novel inhomogeneous superconducting states, namely the helical phase and the multiple-q phase. Its order parameter exhibits periodicity similar to FFLO phase, and the consequences of both phases are same: the enhancement of transition temperature as a function of magnetic field. We have studied the PDW phases in broken parity superconductors with vortices included. By studying PDW vortex states, we find the usual Abrikosov vortex solution is unstable against a new solution with fractional vortex pairs. We have also studied the

  19. Identification of Ion-Pair Structures in Solution by Vibrational Stark Effects.

    Science.gov (United States)

    Hack, John; Grills, David C; Miller, John R; Mani, Tomoyasu

    2016-02-18

    Ion pairing is a fundamental consideration in many areas of chemistry and has implications in a wide range of sciences and technologies that include batteries and organic photovoltaics. Ions in solution are known to inhabit multiple possible states, including free ions (FI), contact ion pairs (CIP), and solvent-separated ion pairs (SSIP). However, in solutions of organic radicals and nonmetal electrolytes, it is often difficult to distinguish between these states. In the first part of this work, we report evidence for the formation of SSIPs in low-polarity solvents and distinct measurements of CIP, SSIP, and FI, by using the ν(C≡N) infrared (IR) band of a nitrile-substituted fluorene radical anion. Use of time-resolved IR detection following pulse radiolysis allowed us to unambiguously assign the peak of the FI. In the presence of nonmetal electrolytes, two distinct red-shifted peaks were observed and assigned to the CIP and SSIP. The assignments are interpreted in the framework of the vibrational Stark effect (VSE) and are supported by (1) the solvent dependence of ion-pair populations, (2) the observation of a cryptand-separated sodium ion pair that mimics the formation of SSIPs, and (3) electronic structure calculations. In the second part of this work, we show that a blue-shift of the ν(C≡N) IR band due to the VSE can be induced in a nitrile-substituted fluorene radical anion by covalently tethering it to a metal-chelating ligand that forms an intramolecular ion pair upon reduction and complexation with sodium ion. This adds support to the conclusion that the shift in IR absorptions by ion pairing originates from the VSE. These results combined show that we can identify ion-pair structures by using the VSE, including the existence of SSIPs in a low-polarity solvent.

  20. String pair production in non homogeneous backgrounds

    CERN Document Server

    Bolognesi, Stefano; Tallarita, Gianni

    2016-01-01

    We consider string pair production in non homogeneous electric backgrounds. We study several particular configurations which can be addressed with the Euclidean world-sheet instanton technique, the analogue of the world-line instanton for particles. In the first case the string is suspended between two D-branes in flat space-time, in the second case the string lives in AdS and terminates on one D-brane (this realizes the holographic Schwinger effect). In some regions of parameter space the result is well approximated by the known analytical formulas, either the particle pair production in non-homogeneous background or the string pair production in homogeneous background. In other cases we see effects which are intrinsically stringy and related to the non-homogeneity of the background. The pair production is enhanced already for particles in time dependent electric field backgrounds. The string nature enhances this even further. For spacial varying electrical background fields the string pair production is les...

  1. Pairing instabilities of Dirac composite fermions

    Science.gov (United States)

    Milovanović, M. V.; Ćirić, M. Dimitrijević; Juričić, V.

    2016-09-01

    Recently, a Dirac (particle-hole symmetric) description of composite fermions in the half-filled Landau level (LL) was proposed [D. T. Son, Phys. Rev. X 5, 031027 (2015), 10.1103/PhysRevX.5.031027], and we study its possible consequences on BCS (Cooper) pairing of composite fermions (CFs). One of the main consequences is the existence of anisotropic states in single-layer and bilayer systems, which was previously suggested in Jeong and Park [J. S. Jeong and K. Park, Phys. Rev. B 91, 195119 (2015), 10.1103/PhysRevB.91.195119]. We argue that in the half-filled LL in the single-layer case the gapped states may sustain anisotropy, because isotropic pairings may coexist with anisotropic ones. Furthermore, anisotropic pairings with the addition of a particle-hole symmetry-breaking mass term may evolve into rotationally symmetric states, i.e., Pfaffian states of Halperin-Lee-Read (HLR) ordinary CFs. On the basis of the Dirac formalism, we argue that in the quantum Hall bilayer at total filling factor 1, with decreasing distance between the layers, weak pairing of p -wave paired CFs is gradually transformed from Dirac to ordinary, HLR-like, with a concomitant decrease in the CF number. Global characterization of low-energy spectra based on the Dirac CFs agrees well with previous calculations performed by exact diagonalization on a torus. Finally, we discuss features of the Dirac formalism when applied in this context.

  2. Pairing and specific heat in hot nuclei

    CERN Document Server

    Gambacurta, Danilo; Sandulescu, Nicu

    2013-01-01

    The thermodynamics of pairing phase-transition in nuclei is studied in the canonical ensemble and treating the pairing correlations in a finite-temperature variation after projection BCS approach (FT-VAP). Due to the restoration of particle number conservation, the pairing gap and the specific heat calculated in the FT-VAP approach vary smoothly with the temperature, indicating a gradual transition from the superfluid to the normal phase, as expected in finite systems. We have checked that the predictions of the FT-VAP approach are very accurate when compared to the results obtained by an exact diagonalization of the pairing Hamiltonian. The influence of pairing correlations on specific heat is analysed for the isotopes $^{161,162}$Dy and $^{171,172}$Yb. It is shown that the FT-VAP approach, applied with a level density provided by mean field calculations and supplemented, at high energies, by the level density of the back-shifted Fermi gas model, can approximate reasonably well the main properties of specifi...

  3. The environment of low redshift quasar pairs

    CERN Document Server

    Sandrinelli, Angela; Treves, Aldo; Farina, Emanuele Paolo; Uslenghi, Michela

    2014-01-01

    We investigate the properties of the galaxy environment of a sample of 14 low redshift (z $<$ 0.85) quasar physical pairs extracted from SDSS DR10 archives. The pairs have a systemic radial velocity difference $\\Delta V_\\parallel \\leqslant$ 600 $km \\ s^{-1}$ (based on [OIII]5007 \\AA \\ line) and projected distance $ R_\\bot \\leqslant$ 600 kpc. The physical association of the pairs is statistically confirmed at a level of $\\sim$ 90 %. For most of the images of these quasars we are able to resolve their host galaxies that turn out to be on average similar to those of quasars not in pairs. We also found that quasars in a pair are on average in region of modest galaxy overdensity extending up 0.5 Mpc from the QSO. This galaxy overdensity is indistinguishable from that of a homogeneous sample of isolated quasars at the same redshift and with similar host galaxy luminosity. These results, albeit derived from a small (but homogeneous) sample of objects, suggest that the rare activation of two quasars with small phy...

  4. Vector boson pair production at hadron colliders

    CERN Document Server

    Adamson, K L

    2002-01-01

    We calculate the contribution of gluon-gluon induced processes to vector boson pair production at hadron colliders, specifically the production of WZ, W gamma and Z gamma pairs. We calculate the tree level processes gg -> WZqq-bqr, gg -> W gamma qq-bar and gg -> Z gamma qq-bar, and the one loop process gg -> Z gamma. We use the helicity method and include the decay of the W and Z bosons into leptons in the narrow width approximation. We include anomalous triple gauge couplings in all of our vector boson pair production calculations. In order to integrate over the qq-bar final state phase space we use an extended version of the subtraction method to NNLO and cancel collinear singularities explicitly. The general subtraction terms that are obtained apply to all vector boson pair production processes. Due to the large gluon density at low x, the gluon induced terms of vector boson pair production are expected to be the dominant NNLO QCD correction, relevant at LHC energies. However, we show that due to a cancell...

  5. Wildlife contact analysis: Emerging methods, questions, and challenges

    Science.gov (United States)

    Cross, Paul C.; Creech, Tyler G.; Ebinger, Michael R.; Heisey, Dennis M.; Irvine, Kathryn M.; Creel, Scott

    2012-01-01

    Recent technological advances, such as proximity loggers, allow researchers to collect complete interaction histories, day and night, among sampled individuals over several months to years. Social network analyses are an obvious approach to analyzing interaction data because of their flexibility for fitting many different social structures as well as the ability to assess both direct contacts and indirect associations via intermediaries. For many network properties, however, it is not clear whether estimates based upon a sample of the network are reflective of the entire network. In wildlife applications, networks may be poorly sampled and boundary effects will be common. We present an alternative approach that utilizes a hierarchical modeling framework to assess the individual, dyadic, and environmental factors contributing to variation in the interaction rates and allows us to estimate the underlying process variation in each. In a disease control context, this approach will allow managers to focus efforts on those types of individuals and environments that contribute the most toward super-spreading events. We account for the sampling distribution of proximity loggers and the non-independence of contacts among groups by only using contact data within a group during days when the group membership of proximity loggers was known. This allows us to separate the two mechanisms responsible for a pair not contacting one another: they were not in the same group or they were in the same group but did not come within the specified contact distance. We illustrate our approach with an example dataset of female elk from northwestern Wyoming and conclude with a number of important future research directions.

  6. Space time manifolds and contact structures

    Directory of Open Access Journals (Sweden)

    K. L. Duggal

    1990-01-01

    Full Text Available A new class of contact manifolds (carring a global non-vanishing timelike vector field is introduced to establish a relation between spacetime manifolds and contact structures. We show that odd dimensional strongly causal (in particular, globally hyperbolic spacetimes can carry a regular contact structure. As examples, we present a causal spacetime with a non regular contact structure and a physical model [Gödel Universe] of Homogeneous contact manifold. Finally, we construct a model of 4-dimensional spacetime of general relativity as a contact CR-submanifold.

  7. Contact Dermatitis, Patch Testing, and Allergen Avoidance.

    Science.gov (United States)

    Burkemper, Nicole M

    2015-01-01

    In patients presenting with a complaint of rash, contact dermatitis is often the underlying diagnosis making it an entity with which health care providers should be familiar. Contact dermatitis can be divided into irritant contact dermatitis and allergic contact dermatitis. In a patient suspected of having allergic contact dermatitis, patch testing can be done to identify specific allergens. Education focused on allergen avoidance and safe products is an integral part of treatment for the contact dermatitis patient. Knowledge of the most common allergens is helpful for clinicians to be able to provide this education.

  8. Solar cell contact formation using laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Harley, Gabriel; Smith, David D.; Cousins, Peter John

    2015-07-21

    The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline material layer; and forming conductive contacts in the plurality of contact holes.

  9. Solar cell contact formation using laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Harley, Gabriel; Smith, David D.; Cousins, Peter John

    2014-07-22

    The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline materiat layer; and forming conductive contacts in the plurality of contact holes.

  10. Solar cell contact formation using laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Harley, Gabriel; Smith, David; Cousins, Peter

    2012-12-04

    The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline material layer; and forming conductive contacts in the plurality of contact holes.

  11. Contact Allergy in Danish Healthcare Workers

    DEFF Research Database (Denmark)

    Schwensen, Jakob F; Menné, Torkil; Sommerlund, Mette;

    2015-01-01

    . The primary objective was to determine whether healthcare work was associated with contact allergy to thiuram mix. Unadjusted univariate analyses revealed that healthcare work was significantly associated with occupational contact dermatitis and hand dermatitis. Contact allergy to thiuram mix was more common...... in healthcare workers was significantly associated with having occupational contact dermatitis, hand dermatitis and older age. In conclusion, we report here a potential problem of contact allergy to thiurams in healthcare workers with contact dermatitis. Legislative authorities may in the future focus...

  12. Mad-Maximized Higgs Pair Analyses

    CERN Document Server

    Kling, Felix; Schichtel, Peter

    2016-01-01

    We study Higgs pair production with a subsequent decay to a pair of photons and a pair of bottoms at the LHC. We use the log-likelihood ratio to identify the kinematic regions which either allow us to separate the di-Higgs signal from backgrounds or to determine the Higgs self-coupling. We find that both regions are separate enough to ensure that details of the background modelling will not affect the determination of the self-coupling. Assuming dominant statistical uncertainties we determine the best precision with which the Higgs self- coupling can be probed in this channel. We finally comment on the same questions at a future 100 TeV collider.

  13. Schwinger Pair Production in Pulsed Electric Fields

    CERN Document Server

    Kim, Sang Pyo; Ruffini, Remo

    2012-01-01

    We numerically investigate the temporal behavior and the structure of longitudinal momentum spectrum and the field polarity effect on pair production in pulsed electric fields in scalar quantum electrodynamics (QED). Using the evolution operator expressed in terms of the particle and antiparticle operators, we find the exact quantum states under the influence of electric pulses and measure the number of pairs of the Minkowski particle and antiparticle. The number of pairs, depending on the configuration of electric pulses, exhibits rich structures in the longitudinal momentum spectrum and undergoes diverse dynamical behaviors at the onset of the interaction but always either converges to a momentum-dependent constant or oscillates around a momentum-dependent time average after the completion of fields.

  14. Hard photodisintegration of a proton pair

    Science.gov (United States)

    Pomerantz, I.; Bubis, N.; Allada, K.; Beck, A.; Beck, S.; Berman, B. L.; Boeglin, W.; Camsonne, A.; Canan, M.; Chirapatpimol, K.; Cisbani, E.; Cusanno, F.; de Jager, C. W.; Dutta, C.; Garibaldi, F.; Geagla, O.; Gilman, R.; Glister, J.; Higinbotham, D. W.; Jiang, X.; Katramatou, A. T.; Khrosinkova, E.; Lee, B. W.; LeRose, J. J.; Lindgren, R.; McCullough, E.; Meekins, D.; Michaels, R.; Moffit, B.; Petratos, G. G.; Piasetzky, E.; Qian, X.; Qiang, Y.; Rodriguez, I.; Ron, G.; Saha, A.; Sarty, A. J.; Sawatzky, B.; Schulte, E.; Shneor, R.; Sparveris, N.; Subedi, R.; Strauch, S.; Sulkosky, V.; Wang, Y.; Wojtsekhowski, B.; Yan, X.; Yao, H.; Zhan, X.; Zheng, X.

    2010-02-01

    We present a study of high energy photodisintegration of proton-pairs through the γ+He3→p+p+n channel. Photon energies, Eγ, from 0.8 to 4.7 GeV were used in kinematics corresponding to a proton pair with high relative momentum and a neutron nearly at rest. The s scaling of the cross section, as predicted by the constituent counting rule for two nucleon photodisintegration, was observed for the first time. The onset of the scaling is at a higher energy and the cross section is significantly lower than for deuteron (pn pair) photodisintegration. For Eγ below the scaling region, the scaled cross section was found to present a strong energy-dependent structure not observed in deuteron photodisintegration.

  15. The inverse problem for Schwinger pair production

    Energy Technology Data Exchange (ETDEWEB)

    Hebenstreit, F., E-mail: hebenstreit@itp.unibe.ch

    2016-02-10

    The production of electron–positron pairs in time-dependent electric fields (Schwinger mechanism) depends non-linearly on the applied field profile. Accordingly, the resulting momentum spectrum is extremely sensitive to small variations of the field parameters. Owing to this non-linear dependence it is so far unpredictable how to choose a field configuration such that a predetermined momentum distribution is generated. We show that quantum kinetic theory along with optimal control theory can be used to approximately solve this inverse problem for Schwinger pair production. We exemplify this by studying the superposition of a small number of harmonic components resulting in predetermined signatures in the asymptotic momentum spectrum. In the long run, our results could facilitate the observation of this yet unobserved pair production mechanism in quantum electrodynamics by providing suggestions for tailored field configurations.

  16. Narrowband Photon Pair Source for Quantum Networks

    CERN Document Server

    Monteiro, F; Sanguinetti, B; Zbinden, H; Thew, R T

    2013-01-01

    We demonstrate a compact photon pair source based on a periodically poled lithium niobate nonlinear crystal in a cavity. The cavity parameters are chosen such that the emitted photon pair modes can be matched in the region of telecom ultra dense wavelength division multiplexing (U-DWDM) channel spacings. This approach provides efficient, low-loss, mode selection that is compatible with standard telecommunication networks. Photons with a coherence time of 8.6 ns (116 MHz) are produced and their purity is demonstrated. A source brightness of 134 pairs(s.mW.MHz)$^{-1}$ is reported. The high level of purity and compatibility with standard telecom networks is of great importance for complex quantum communication networks.

  17. An inverse problem for Schwinger pair production

    CERN Document Server

    Hebenstreit, Florian

    2016-01-01

    The production of electron-positron pairs in time-dependent electric fields (Schwinger mechanism) depends non-linearly on the applied field profile. Accordingly, the resulting momentum spectrum is extremely sensitive to small variations of the field parameters. Owing to this non-linear dependence it is so far unpredictable how to choose a field configuration such that a predetermined momentum distribution is generated. We show that quantum kinetic theory along with optimal control theory can be used to approximately solve this inverse problem for Schwinger pair production. We exemplify this by studying the superposition of a small number of harmonic components resulting in predetermined signatures in the asymptotic momentum spectrum. In the long run, our results could facilitate the observation of this yet unobserved pair production mechanism in quantum electrodynamics by providing suggestions for tailored field configurations.

  18. Categorical Pairs and the Indicative Shift

    CERN Document Server

    Kauffman, Louis H

    2011-01-01

    This paper introduces the notion of a categorical pair, a pair of categories (C,C') such that every morphism in C is an object in C'. Categorical pairs are precursors to 2-categories. Arrows in C' can express relationships among the morphisms of C. In particular we show that by using a model of the linguistic process of naming, we can ensure that every morphism in C has an indirect self-reference of the form a -----> Fa where this arrow occurs in the category C'. This result is shown to generalize and clarify known fixed point theorems in logic and categories, and is applied to Goedel's Incompleteness Theorem, the Cantor Diagonal Process and the Lawvere Fixed Point Theorem. In particular we show that the indirect self-reference that is central to Goedel's Theorem is an instance of a general pattern here called the indicative shift.

  19. The inverse problem for Schwinger pair production

    Directory of Open Access Journals (Sweden)

    F. Hebenstreit

    2016-02-01

    Full Text Available The production of electron–positron pairs in time-dependent electric fields (Schwinger mechanism depends non-linearly on the applied field profile. Accordingly, the resulting momentum spectrum is extremely sensitive to small variations of the field parameters. Owing to this non-linear dependence it is so far unpredictable how to choose a field configuration such that a predetermined momentum distribution is generated. We show that quantum kinetic theory along with optimal control theory can be used to approximately solve this inverse problem for Schwinger pair production. We exemplify this by studying the superposition of a small number of harmonic components resulting in predetermined signatures in the asymptotic momentum spectrum. In the long run, our results could facilitate the observation of this yet unobserved pair production mechanism in quantum electrodynamics by providing suggestions for tailored field configurations.

  20. Measurements of interfacial thermal contact conductance between pressed alloys at low temperatures

    Science.gov (United States)

    Zheng, Jiang; Li, Yanzhong; Chen, Pengwei; Yin, Geyuan; Luo, Huaihua

    2016-12-01

    Interfacial thermal contact conductance is the primary factor limiting the heat transfer in many cryogenic engineering applications. This paper presents an experimental apparatus to measure interfacial thermal contact conductance between pressed alloys in a vacuum environment at low temperatures. The measurements of thermal contact conductance between pressed alloys are conducted by using the developed apparatus. The results show that the contact conductance increases with the decrease of surface roughness, the increase of interface temperature and contact pressure. The temperature dependence of thermal conductivity and mechanical properties is analyzed to explain the results. Thermal contact conductance of a pair of stainless steel specimens is obtained in the interface temperature range of 135-245 K and in the contact pressure range of 1-9 MPa. The results are regressed as a power function of temperature and load. Thermal conductance is also obtained between aluminums as well as between stainless steel and aluminum. The load exponents of the regressed relations for different contacts are compared. Existing theoretical models (the Cooper-Mikic-Yovanovich plastic model, the Mikic elastic model and the improved Kimura model) are reviewed and compared with the experimental results. The Cooper-Mikic-Yovanovich model predictions are found to be in good agreement with experimental results, especially with measurements between aluminums.