Elliptic jets, part 2. Dynamics of coherent structures: Pairing

NASA Technical Reports Server (NTRS)

Husain, Hyder S.; Hussain, Fazle

1992-01-01

The dynamics of the jet column mode of vortex pairing in the near field of an elliptic jet was investigated. Hot-wire measurements and flow visualization were used to examine the details of the pairing mechanism of nonplanar vortical elliptic structures and its effect on such turbulence measures as coherent velocities, incoherent turbulence intensities, incoherent and coherent Reynolds, stresses, turbulence production, and mass entrainment. It was found that pairing of elliptic vortices in the jet column does not occur uniformly around the entire perimeter, unlike in a circular jet. Merger occurs only in the initial major-axis plane. In the initial minor-axis plane, the trailing vortex rushes through the leading vortex without pairing and then breaks down violently, producing considerably greater entrainment and mixing than in circular or plane jets.

Local destruction of superconductivity by non-magnetic impurities in mesoscopic iron-based superconductors

NASA Astrophysics Data System (ADS)

Li, Jun; Ji, Min; Schwarz, Tobias; Ke, Xiaoxing; van Tendeloo, Gustaaf; Yuan, Jie; Pereira, Paulo J.; Huang, Ya; Zhang, Gufei; Feng, Hai-Luke; Yuan, Ya-Hua; Hatano, Takeshi; Kleiner, Reinhold; Koelle, Dieter; Chibotaru, Liviu F.; Yamaura, Kazunari; Wang, Hua-Bing; Wu, Pei-Heng; Takayama-Muromachi, Eiji; Vanacken, Johan; Moshchalkov, Victor V.

2015-07-01

The determination of the pairing symmetry is one of the most crucial issues for the iron-based superconductors, for which various scenarios are discussed controversially. Non-magnetic impurity substitution is one of the most promising approaches to address the issue, because the pair-breaking mechanism from the non-magnetic impurities should be different for various models. Previous substitution experiments demonstrated that the non-magnetic zinc can suppress the superconductivity of various iron-based superconductors. Here we demonstrate the local destruction of superconductivity by non-magnetic zinc impurities in Ba0.5K0.5Fe2As2 by exploring phase-slip phenomena in a mesoscopic structure with 119 × 102 nm2 cross-section. The impurities suppress superconductivity in a three-dimensional `Swiss cheese'-like pattern with in-plane and out-of-plane characteristic lengths slightly below ~1.34 nm. This causes the superconducting order parameter to vary along abundant narrow channels with effective cross-section of a few square nanometres. The local destruction of superconductivity can be related to Cooper pair breaking by non-magnetic impurities.

Local destruction of superconductivity by non-magnetic impurities in mesoscopic iron-based superconductors

PubMed Central

Li, Jun; Ji, Min; Schwarz, Tobias; Ke, Xiaoxing; Van Tendeloo, Gustaaf; Yuan, Jie; Pereira, Paulo J.; Huang, Ya; Zhang, Gufei; Feng, Hai-Luke; Yuan, Ya-Hua; Hatano, Takeshi; Kleiner, Reinhold; Koelle, Dieter; Chibotaru, Liviu F.; Yamaura, Kazunari; Wang, Hua-Bing; Wu, Pei-Heng; Takayama-Muromachi, Eiji; Vanacken, Johan; Moshchalkov, Victor V.

2015-01-01

The determination of the pairing symmetry is one of the most crucial issues for the iron-based superconductors, for which various scenarios are discussed controversially. Non-magnetic impurity substitution is one of the most promising approaches to address the issue, because the pair-breaking mechanism from the non-magnetic impurities should be different for various models. Previous substitution experiments demonstrated that the non-magnetic zinc can suppress the superconductivity of various iron-based superconductors. Here we demonstrate the local destruction of superconductivity by non-magnetic zinc impurities in Ba0.5K0.5Fe2As2 by exploring phase-slip phenomena in a mesoscopic structure with 119 × 102 nm2 cross-section. The impurities suppress superconductivity in a three-dimensional ‘Swiss cheese'-like pattern with in-plane and out-of-plane characteristic lengths slightly below ∼1.34 nm. This causes the superconducting order parameter to vary along abundant narrow channels with effective cross-section of a few square nanometres. The local destruction of superconductivity can be related to Cooper pair breaking by non-magnetic impurities. PMID:26139568

Local destruction of superconductivity by non-magnetic impurities in mesoscopic iron-based superconductors.

PubMed

Li, Jun; Ji, Min; Schwarz, Tobias; Ke, Xiaoxing; Van Tendeloo, Gustaaf; Yuan, Jie; Pereira, Paulo J; Huang, Ya; Zhang, Gufei; Feng, Hai-Luke; Yuan, Ya-Hua; Hatano, Takeshi; Kleiner, Reinhold; Koelle, Dieter; Chibotaru, Liviu F; Yamaura, Kazunari; Wang, Hua-Bing; Wu, Pei-Heng; Takayama-Muromachi, Eiji; Vanacken, Johan; Moshchalkov, Victor V

2015-07-03

The determination of the pairing symmetry is one of the most crucial issues for the iron-based superconductors, for which various scenarios are discussed controversially. Non-magnetic impurity substitution is one of the most promising approaches to address the issue, because the pair-breaking mechanism from the non-magnetic impurities should be different for various models. Previous substitution experiments demonstrated that the non-magnetic zinc can suppress the superconductivity of various iron-based superconductors. Here we demonstrate the local destruction of superconductivity by non-magnetic zinc impurities in Ba0.5K0.5Fe2As2 by exploring phase-slip phenomena in a mesoscopic structure with 119 × 102 nm(2) cross-section. The impurities suppress superconductivity in a three-dimensional 'Swiss cheese'-like pattern with in-plane and out-of-plane characteristic lengths slightly below ∼1.34 nm. This causes the superconducting order parameter to vary along abundant narrow channels with effective cross-section of a few square nanometres. The local destruction of superconductivity can be related to Cooper pair breaking by non-magnetic impurities.

Cisplatin enhances the formation of DNA single- and double-strand breaks by hydrated electrons and hydroxyl radicals.

PubMed

Rezaee, Mohammad; Sanche, Léon; Hunting, Darel J

2013-03-01

The synergistic interaction of cisplatin with ionizing radiation is the clinical rationale for the treatment of several cancers including head and neck, cervical and lung cancer. The underlying molecular mechanism of the synergy has not yet been identified, although both DNA damage and repair processes are likely involved. Here, we investigate the indirect effect of γ rays on strand break formation in a supercoiled plasmid DNA (pGEM-3Zf-) covalently modified by cisplatin. The yields of single- and double-strand breaks were determined by irradiation of DNA and cisplatin/DNA samples with (60)Co γ rays under four different scavenging conditions to examine the involvement of hydrated electrons and hydroxyl radicals in inducing the DNA damage. At 5 mM tris in an N2 atmosphere, the presence of an average of two cisplatins per plasmid increased the yields of single- and double-strand breaks by factors of 1.9 and 2.2, respectively, relative to the irradiated unmodified DNA samples. Given that each plasmid of 3,200 base pairs contained an average of two cisplatins, this represents an increase in radiosensitivity of 3,200-fold on a per base pair basis. When hydrated electrons were scavenged by saturating the samples with N2O, these enhancement factors decreased to 1.5 and 1.2, respectively, for single- and double-strand breaks. When hydroxyl radicals were scavenged using 200 mM tris, the respective enhancement factors were 1.2 and 1.6 for single- and double-strand breaks, respectively. Furthermore, no enhancement in DNA damage by cisplatin was observed after scavenging both hydroxyl radicals and hydrated electrons. These findings show that hydrated electrons can induce both single- and double-strand breaks in the platinated DNA, but not in unmodified DNA. In addition, cisplatin modification is clearly an extremely efficient means of increasing the formation of both single- and double-strand breaks by the hydrated electrons and hydroxyl radicals created by ionizing radiation.

Effects of Fluctuations on Inhomogeneous Chiral Transitions

NASA Astrophysics Data System (ADS)

Lee, Tong-Gyu; Yoshiike, Ryo; Tatsumi, Toshitaka

We discuss the features of the order-parameter fluctuations in the normal phase near the phase boundary and their effects on the phase transition from the normal to the inhomogeneous phase with spatially modulated order parameter. Focusing on the chiral symmetry breaking, i.e., inhomogeneous chiral transition, we consider the fluctuation of the chiral pair consisting of quark-antiquark or quark-hole pair within the two-flavor Nambu-Jona-Lasinio model in the chiral limit. We clarify the roles of quantum and thermal fluctuations and also argue that anomalies for thermodynamic quantities in the inhomogeneous chiral transition should lead to phenomenological implications.

Magnetic and superconducting phase diagrams of single-crystal Er0.8R0.2Ni2B2C (R=Tb,Lu) and ErNi1.9Co0.1B2C: Identification of pair-breaking mechanisms

NASA Astrophysics Data System (ADS)

Takeya, H.; El Massalami, M.

2004-01-01

We investigated the magnetism, superconductivity and their interplay in single crystals Er0.8R0.2Ni2B2C (R=Tb,Lu) and ErNi1.9Co0.1B2C. In contrast to Co substitution, R substitutions induce considerable modifications in the magnetism of Er sublattice: e.g., Tb (Lu) substitution enhances (reduces) TN and critical fields. Both R substitutions introduce size effects and pinning centers; the former modifies the magnon specific heat while the latter hinders the formation of a weak ferromagnetism. The superconductivity, on the other hand, is strongly (weakly) influenced by Tb and Co (Lu) substitution. Taking LuNi2B2C as a nonmagnetic superconducting limit, we analyzed their superconductivities, as well as that of ErNi2B2C, in terms of multiple pair breaking theory on dirty superconductors. Based on this analysis, many of their superconducting features can be explained: The breakdown of de Gennes scaling is due to the presence of multiple pair breakers, the anisotropy of Hc2(T) is related to the magnetic anisotropy, the absence of a structure in Hc2(T) at TN of Lu substitution (TN

Oxygen isotope effect in disordered underdoped and overdoped La 2-xSr xCu 1-yZn yO 4 superconductors

NASA Astrophysics Data System (ADS)

Naqib, S. H.; Islam, R. S.

2011-04-01

The effect of oxygen isotopic substitution on the superconducting transition temperature has been studied for heavily underdoped and overdoped La 2-xSr xCu 1-yZn yO 4 compounds with different Zn contents in the CuO 2 plane. The effect of Zn on the isotope coefficient, α, was significantly more pronounced in the case of the underdoped ( x = 0.09) compounds compared to the overdoped ( x = 0.22) ones. The variation of α with disorder content can be described quite well within a model based solely on Cooper pair-breaking in the case of the underdoped compounds. This model fails to describe the behavior of α( y) for the overdoped samples, even though Zn still suppresses T c very effectively at this hole (Sr) content, indicating that the Zn induced pair-breaking is still very much at play. We discuss the implications of these findings in details by considering the Zn induced magnetism, stripe correlations, and possible changes in the superconducting order parameter as hole content in the CuO 2 plane, p (≡ x), is varied.

ψ (2 S ) versus J /ψ suppression in proton-nucleus collisions from factorization violating soft color exchanges

NASA Astrophysics Data System (ADS)

Ma, Yan-Qing; Venugopalan, Raju; Watanabe, Kazuhiro; Zhang, Hong-Fei

2018-01-01

We argue that the large suppression of the ψ (2 S ) inclusive cross section relative to the J /ψ inclusive cross section in proton-nucleus (p+A) collisions can be attributed to factorization breaking effects in the formation of quarkonium. These factorization breaking effects arise from soft color exchanges between charm-anticharm pairs undergoing hadronization and comoving partons that are long lived on time scales of quarkonium formation. We compute the short distance pair production of heavy quarks in the color glass condensate (CGC) effective field theory and employ an improved color evaporation model (ICEM) to describe their hadronization into quarkonium at large distances. The combined CGC+ICEM model provides a quantitative description of J /ψ and ψ (2 S ) data in proton-proton (p+p) collisions from both RHIC and the LHC. Factorization breaking effects in hadronization, due to additional parton comovers in the nucleus, are introduced heuristically by imposing a cutoff Λ , representing the average momentum kick from soft color exchanges, in the ICEM. Such soft exchanges have no perceptible effect on J /ψ suppression in p+A collisions. In contrast, the interplay of the physics of these soft exchanges at large distances, with the physics of semihard rescattering at short distances, causes a significant additional suppression of ψ (2 S ) yields relative to that of the J /ψ . A good fit of all RHIC and LHC J /ψ and ψ (2 S ) data, for transverse momenta P⊥≤5 GeV in p+p and p+A collisions, is obtained for Λ ˜10 MeV.

Pairing Symmetry Transitions in the Even-Denominator FQHE System

NASA Astrophysics Data System (ADS)

Nomura, Kentaro; Yoshioka, Daijiro

2001-12-01

Transitions from a paired quantum Hall state to another quantum Hall state in bilayer systems are discussed in the framework of the edge theory. Starting from the edge theory for the Haldane Rezayi state, it is shown that the charging effect of a bilayer system which breaks the SU(2) symmetry of the pseudospin shifts the central charge and the conformal dimensions of the fermionic fields which describe the pseudospin sector in the edge theory. This corresponds to the transition from the Haldane Rezayi state to Halperin's 331 state, or from a singlet d-wave to a triplet p-wave ABM type paired state in the composite fermion picture. Considering interlayer tunneling, the tunneling rate-capacitance phase diagram for the ν=5/2 paired bilayer system is discussed.

Do children report differently from their parents and from observed data? Cross-sectional data on fruit, water, sugar-sweetened beverages and break-time foods.

PubMed

van de Gaar, V M; Jansen, W; van der Kleij, M J J; Raat, H

2016-04-18

Reliable assessment of children's dietary behaviour is needed for research purposes. The aim of this study was (1) to investigate the level of agreement between observed and child-reported break-time food items; and (2) to investigate the level of agreement between children's reports and those of their parents regarding children's overall consumption of fruit, water and sugar-sweetened beverages (SSB). The children in this study were 9-13 years old, attending primary schools in Rotterdam, the Netherlands. Children were observed with respect to foods brought for break-time at school. At the same day, children completed a questionnaire in which they were asked to recall the food(s) they brought to school to consume during break-time. Only paired data (observed and child-reported) were included in the analyses (n = 407 pairs). To determine each child's daily consumption and average amounts of fruit, water and SSB consumed, children and their parents completed parallel questionnaires. Only paired data (parent-reported and child-reported) were included in the analyses (n = 275 pairs). The main statistical measures were level of agreement between break-time foods, fruit, water and SSB; and Intra-class Correlation Coefficients (ICC). More children reported bringing sandwiches and snacks for break-time than was observed (73 % vs 51 % observed and 84 % vs 33 % observed). The overall agreement between observed and child-reported break-time foods was poor to fair, with ICC range 0.16-0.39 (p < 0.05). Children reported higher average amounts of SSB consumed than did their parents (1.3 vs 0.9 L SSB, p < 0.001). Child and parent estimations of the child's water and fruit consumption were similar. ICC between parent and child reports was poor to good (range 0.22-0.62, p < 0.05). Children report higher on amount of break-time foods as compared to observations and children's reports of SSB consumption are higher than those of their parents. Since the level of agreement between the observed break-time foods and that reported by children and the agreement of child's intake between parent and child reports are relatively weak, future studies should focus on improving methods of evaluating children's consumption behaviour or on ways on how to best use and interpret multiple-source dietary intake data. Current Controlled Trials NTR3400 .

Repair of clustered DNA damage caused by high LET radiation in human fibroblasts

NASA Technical Reports Server (NTRS)

Rydberg, B.; Lobrich, M.; Cooper, P. K.; Chatterjee, A. (Principal Investigator)

1998-01-01

It has recently been demonstrated experimentally that DNA damage induced by high LET radiation in mammalian cells is non-randomly distributed along the DNA molecule in the form of clusters of various sizes. The sizes of such clusters range from a few base-pairs to at least 200 kilobase-pairs. The high biological efficiency of high LET radiation for induction of relevant biological endpoints is probably a consequence of this clustering, although the exact mechanisms by which the clustering affects the biological outcome is not known. We discuss here results for induction and repair of base damage, single-strand breaks and double-strand breaks for low and high LET radiations. These results are discussed in the context of clustering. Of particular interest is to determine how clustering at different scales affects overall rejoining and fidelity of rejoining of DNA double-strand breaks. However, existing methods for measuring repair of DNA strand breaks are unable to resolve breaks that are close together in a cluster. This causes problems in interpretation of current results from high LET radiation and will require new methods to be developed.

Bridging of double-stranded breaks by the nonhomologous end-joining ligation complex is modulated by DNA end chemistry.

PubMed

Reid, Dylan A; Conlin, Michael P; Yin, Yandong; Chang, Howard H; Watanabe, Go; Lieber, Michael R; Ramsden, Dale A; Rothenberg, Eli

2017-02-28

The nonhomologous end-joining (NHEJ) pathway is the primary repair pathway for DNA double strand breaks (DSBs) in humans. Repair is mediated by a core complex of NHEJ factors that includes a ligase (DNA Ligase IV; L4) that relies on juxtaposition of 3΄ hydroxyl and 5΄ phosphate termini of the strand breaks for catalysis. However, chromosome breaks arising from biological sources often have different end chemistries, and how these different end chemistries impact the way in which the core complex directs the necessary transitions from end pairing to ligation is not known. Here, using single-molecule FRET (smFRET), we show that prior to ligation, differences in end chemistry strongly modulate the bridging of broken ends by the NHEJ core complex. In particular, the 5΄ phosphate group is a recognition element for L4 and is critical for the ability of NHEJ factors to promote stable pairing of ends. Moreover, other chemical incompatibilities, including products of aborted ligation, are sufficient to disrupt end pairing. Based on these observations, we propose a mechanism for iterative repair of DSBs by NHEJ. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

Multiple focused EMAT designs for improved surface breaking defect characterization

NASA Astrophysics Data System (ADS)

Thring, C. B.; Fan, Y.; Edwards, R. S.

2017-02-01

Ultrasonic Rayleigh waves can be employed for the detection of surface breaking defects such as rolling contact fatigue and stress corrosion cracking. Electromagnetic Acoustic Transducers (EMATs) are well suited to this technique as they can directly generate Rayleigh waves within the sample without the requirement for wedges, and they are robust and inexpensive compared to laser ultrasonics. Three different EMAT coil types have been developed, and these are compared to assess their ability to detect and characterize small (down to 0.5 mm depth, 1 mm diameter) surface breaking defects in aluminium. These designs are: a pair of linear meander coils used in a pseudo-pulse-echo mode, a pair of focused meander coils also used in pseudo-pulse-echo mode, and a pair of focused racetrack coils used in pitch-catch mode. The linear meander coils are able to detect most of the defects tested, but have a much lower signal to noise ratio and give limited sizing information. The focused meander coils and the focused racetrack coils can detect all defects tested, but have the advantage that they can also characterize the defect sizes on the sample surface, and have a stronger sensitivity at their focal point. Measurements using all three EMAT designs are presented and compared for high resolution imaging of surface-breaking defects.

Thermodynamic properties of Dynes superconductors

NASA Astrophysics Data System (ADS)

Herman, František; Hlubina, Richard

2018-01-01

The tunneling density of states in dirty s -wave superconductors is often well described by the phenomenological Dynes formula. Recently we have shown that this formula can be derived, within the coherent potential approximation, for superconductors with simultaneously present pair-conserving and pair-breaking impurity scattering. Here we demonstrate that the theory of such so-called Dynes superconductors is thermodynamically consistent. We calculate the specific heat and critical field of the Dynes superconductors, and we show that their gap parameter, specific heat, critical field, and penetration depth exhibit power-law scaling with temperature in the low-temperature limit. We also show that in the vicinity of a coupling-constant-controlled superconductor to normal metal transition, the Homes law is replaced by a different, pair-breaking-dominated scaling law.

ψ ( 2 S ) versus J / ψ suppression in proton-nucleus collisions from factorization violating soft color exchanges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, Yan -Qing; Venugopalan, Raju; Watanabe, Kazuhiro

Here, we argue that the large suppression of themore » $$\\psi(2S)$$ inclusive cross-section relative to the $$J/\\psi$$ inclusive cross-section in proton-nucleus (p+A) collisions can be attributed to factorization breaking effects in the formation of quarkonium. These factorization breaking effects arise from soft color exchanges between charm-anticharm pairs undergoing hadronization and comoving partons that are long-lived on time scales of quarkonium formation. We compute the short distance pair production of heavy quarks in the Color Glass Condensate (CGC) effective field theory and employ an improved Color Evaporation model (ICEM) to describe their hadronization into quarkonium at large distances. The combined CGC+ICEM model provides a quantitative description of $$J/\\psi$$ and $$\\psi(2S)$$ data in proton-proton (p+p) collisions from both RHIC and the LHC. Factorization breaking effects in hadronization, due to additional parton comovers in the nucleus, are introduced heuristically by imposing a cutoff $$\\Lambda$$, representing the momentum kick from soft color exchanges, in the ICEM model. Such soft exchanges have no perceptible effect on $$J/\\psi$$ suppression in p+A collisions. In contrast, the interplay of the physics of these soft exchanges at large distances, with the physics of semi-hard rescattering at short distances, causes a significant additional suppression of $$\\psi(2S)$$ yields relative to that of the $$J/\\psi$$. A good fit of all RHIC and LHC $$J/\\psi$$ and $$\\psi(2S)$$ data, for transverse momenta $$P_\\perp\\leq 5$$ GeV in p+p and p+A collisions, is obtained for $$\\Lambda\\sim 10$$ MeV.« less

ψ ( 2 S ) versus J / ψ suppression in proton-nucleus collisions from factorization violating soft color exchanges

DOE PAGES

Ma, Yan -Qing; Venugopalan, Raju; Watanabe, Kazuhiro; ...

2018-01-31

Here, we argue that the large suppression of themore » $$\\psi(2S)$$ inclusive cross-section relative to the $$J/\\psi$$ inclusive cross-section in proton-nucleus (p+A) collisions can be attributed to factorization breaking effects in the formation of quarkonium. These factorization breaking effects arise from soft color exchanges between charm-anticharm pairs undergoing hadronization and comoving partons that are long-lived on time scales of quarkonium formation. We compute the short distance pair production of heavy quarks in the Color Glass Condensate (CGC) effective field theory and employ an improved Color Evaporation model (ICEM) to describe their hadronization into quarkonium at large distances. The combined CGC+ICEM model provides a quantitative description of $$J/\\psi$$ and $$\\psi(2S)$$ data in proton-proton (p+p) collisions from both RHIC and the LHC. Factorization breaking effects in hadronization, due to additional parton comovers in the nucleus, are introduced heuristically by imposing a cutoff $$\\Lambda$$, representing the momentum kick from soft color exchanges, in the ICEM model. Such soft exchanges have no perceptible effect on $$J/\\psi$$ suppression in p+A collisions. In contrast, the interplay of the physics of these soft exchanges at large distances, with the physics of semi-hard rescattering at short distances, causes a significant additional suppression of $$\\psi(2S)$$ yields relative to that of the $$J/\\psi$$. A good fit of all RHIC and LHC $$J/\\psi$$ and $$\\psi(2S)$$ data, for transverse momenta $$P_\\perp\\leq 5$$ GeV in p+p and p+A collisions, is obtained for $$\\Lambda\\sim 10$$ MeV.« less

In-gap quasiparticle excitations induced by non-magnetic Cu impurities in Na(Fe0.96Co0.03Cu0.01)As revealed by scanning tunnelling spectroscopy

PubMed Central

Yang, Huan; Wang, Zhenyu; Fang, Delong; Deng, Qiang; Wang, Qiang-Hua; Xiang, Yuan-Yuan; Yang, Yang; Wen, Hai-Hu

2013-01-01

The origin of superconductivity in the iron pnictides remains unclear. One suggestion is that superconductivity in these materials has a magnetic origin, which would imply a sign-reversal s± pairing symmetry. Another suggests it is the result of orbital fluctuations, which would imply a sign-equal s++ pairing symmetry. There is no consensus yet which of these two distinct and contrasting pairing symmetries is the right one in iron pnictide superconductors. Here we explore the nature of the pairing symmetry in the superconducting state of Na(Fe0.97−xCo0.03Cux)As by probing the effect of scattering of Cooper pairs by non-magnetic Cu impurities. Using scanning tunnelling spectroscopy, we identify the in-gap quasiparticle states induced by the Cu impurities, showing signatures of Cooper pair breaking by these non-magnetic impurities–a process that is only consistent with s± pairing. This experiment provides strong evidence for the s± pairing. PMID:24248097

Breaking the Communication Barrier: Guidelines to Aid Communication within Pair Programming

ERIC Educational Resources Information Center

Zarb, Mark; Hughes, Janet

2015-01-01

Pair programming is a software development technique with many cited benefits in learning and teaching. However, it is reported that novice programmers find several barriers to pairing up, typically due to the added communication that is required of this approach. This paper will present a literature review discussing the issue of communication,…

Glide-plane symmetry and superconducting gap structure of iron-based superconductors

DOE PAGES

Wang, Yan; Berlijn, Tom; Hirschfeld, Peter J.; ...

2015-03-10

We consider the effect of glide-plane symmetry of the Fe-pnictogen/chalcogen layer in Fe-based superconductors on pairing in spin fluctuation models. Recent theories propose that so-called η-pairing states with nonzero total momentum can be realized and possess such exotic properties as odd parity spin singlet symmetry and time-reversal symmetry breaking. Here we show that when there is orbital weight at the Fermi level from orbitals with even and odd mirror reflection symmetry in z, η pairing is inevitable; however, we conclude from explicit calculation that the gap function appearing in observable quantities is identical to that found in earlier pseudocrystal momentummore » calculations with 1 Fe per unit cell.« less

The origin of the mass of the Nambu-Goldstone bosons

NASA Astrophysics Data System (ADS)

Arraut, Ivan

2018-03-01

We explain the origin of the mass for the Nambu-Goldstone bosons when there is a chemical potential in the action which explicitly breaks the symmetry. The method is based on the number of independent histories for the interaction of the pair of Nambu-Goldstone bosons with the degenerate vacuum (triangle relations). The analysis suggests that under some circumstances, pairs of massive Nambu-Goldstone bosons can become a single degree of freedom with an effective mass defined by the superposition of the individual masses of each boson. Possible mass oscillations for the Nambu-Goldstone bosons are discussed.

Electromagnetic properties of impure superconductors with pair-breaking processes

NASA Astrophysics Data System (ADS)

Herman, František; Hlubina, Richard

2017-07-01

Recently, a generic model was proposed for the single-particle properties of gapless superconductors with simultaneously present pair-conserving and pair-breaking impurity scatterings (the so-called Dynes superconductors). Here we calculate the optical conductivity of the Dynes superconductors. Our approach is applicable for all disorder strengths from the clean limit up to the dirty limit and for all relative ratios of the two types of scattering; nevertheless, the complexity of our description is equivalent to that of the widely used Mattis-Bardeen theory. We identify two optical fingerprints of the Dynes superconductors: (i) the presence of two absorption edges and (ii) finite absorption at vanishing frequencies even at the lowest temperatures. We demonstrate that the recent anomalous optical data on thin MoN films can be reasonably fitted by our theory.

Rotational symmetry breaking in the topological superconductor SrxBi2Se3 probed by upper-critical field experiments

NASA Astrophysics Data System (ADS)

Pan, Y.; Nikitin, A. M.; Araizi, G. K.; Huang, Y. K.; Matsushita, Y.; Naka, T.; de Visser, A.

2016-06-01

Recently it was demonstrated that Sr intercalation provides a new route to induce superconductivity in the topological insulator Bi2Se3. Topological superconductors are predicted to be unconventional with an odd-parity pairing symmetry. An adequate probe to test for unconventional superconductivity is the upper critical field, Bc2. For a standard BCS layered superconductor Bc2 shows an anisotropy when the magnetic field is applied parallel and perpendicular to the layers, but is isotropic when the field is rotated in the plane of the layers. Here we report measurements of the upper critical field of superconducting SrxBi2Se3 crystals (Tc = 3.0 K). Surprisingly, field-angle dependent magnetotransport measurements reveal a large anisotropy of Bc2 when the magnet field is rotated in the basal plane. The large two-fold anisotropy, while six-fold is anticipated, cannot be explained with the Ginzburg-Landau anisotropic effective mass model or flux flow induced by the Lorentz force. The rotational symmetry breaking of Bc2 indicates unconventional superconductivity with odd-parity spin-triplet Cooper pairs (Δ4-pairing) recently proposed for rhombohedral topological superconductors, or might have a structural nature, such as self-organized stripe ordering of Sr atoms.

Rotational symmetry breaking in the topological superconductor SrxBi2Se3 probed by upper-critical field experiments.

PubMed

Pan, Y; Nikitin, A M; Araizi, G K; Huang, Y K; Matsushita, Y; Naka, T; de Visser, A

2016-06-28

Recently it was demonstrated that Sr intercalation provides a new route to induce superconductivity in the topological insulator Bi2Se3. Topological superconductors are predicted to be unconventional with an odd-parity pairing symmetry. An adequate probe to test for unconventional superconductivity is the upper critical field, Bc2. For a standard BCS layered superconductor Bc2 shows an anisotropy when the magnetic field is applied parallel and perpendicular to the layers, but is isotropic when the field is rotated in the plane of the layers. Here we report measurements of the upper critical field of superconducting SrxBi2Se3 crystals (Tc = 3.0 K). Surprisingly, field-angle dependent magnetotransport measurements reveal a large anisotropy of Bc2 when the magnet field is rotated in the basal plane. The large two-fold anisotropy, while six-fold is anticipated, cannot be explained with the Ginzburg-Landau anisotropic effective mass model or flux flow induced by the Lorentz force. The rotational symmetry breaking of Bc2 indicates unconventional superconductivity with odd-parity spin-triplet Cooper pairs (Δ4-pairing) recently proposed for rhombohedral topological superconductors, or might have a structural nature, such as self-organized stripe ordering of Sr atoms.

Rotational symmetry breaking in the topological superconductor SrxBi2Se3 probed by upper-critical field experiments

PubMed Central

Pan, Y.; Nikitin, A. M.; Araizi, G. K.; Huang, Y. K.; Matsushita, Y.; Naka, T.; de Visser, A.

2016-01-01

Recently it was demonstrated that Sr intercalation provides a new route to induce superconductivity in the topological insulator Bi2Se3. Topological superconductors are predicted to be unconventional with an odd-parity pairing symmetry. An adequate probe to test for unconventional superconductivity is the upper critical field, Bc2. For a standard BCS layered superconductor Bc2 shows an anisotropy when the magnetic field is applied parallel and perpendicular to the layers, but is isotropic when the field is rotated in the plane of the layers. Here we report measurements of the upper critical field of superconducting SrxBi2Se3 crystals (Tc = 3.0 K). Surprisingly, field-angle dependent magnetotransport measurements reveal a large anisotropy of Bc2 when the magnet field is rotated in the basal plane. The large two-fold anisotropy, while six-fold is anticipated, cannot be explained with the Ginzburg-Landau anisotropic effective mass model or flux flow induced by the Lorentz force. The rotational symmetry breaking of Bc2 indicates unconventional superconductivity with odd-parity spin-triplet Cooper pairs (Δ4-pairing) recently proposed for rhombohedral topological superconductors, or might have a structural nature, such as self-organized stripe ordering of Sr atoms. PMID:27350295

Protein Phosphatase 4 Promotes Chromosome Pairing and Synapsis, and Contributes to Maintaining Crossover Competence with Increasing Age

PubMed Central

Sato-Carlton, Aya; Li, Xuan; Crawley, Oliver; Testori, Sarah; Martinez-Perez, Enrique; Sugimoto, Asako; Carlton, Peter M.

2014-01-01

Prior to the meiotic divisions, dynamic chromosome reorganizations including pairing, synapsis, and recombination of maternal and paternal chromosome pairs must occur in a highly regulated fashion during meiotic prophase. How chromosomes identify each other's homology and exclusively pair and synapse with their homologous partners, while rejecting illegitimate synapsis with non-homologous chromosomes, remains obscure. In addition, how the levels of recombination initiation and crossover formation are regulated so that sufficient, but not deleterious, levels of DNA breaks are made and processed into crossovers is not understood well. We show that in Caenorhabditis elegans, the highly conserved Serine/Threonine protein phosphatase PP4 homolog, PPH-4.1, is required independently to carry out four separate functions involving meiotic chromosome dynamics: (1) synapsis-independent chromosome pairing, (2) restriction of synapsis to homologous chromosomes, (3) programmed DNA double-strand break initiation, and (4) crossover formation. Using quantitative imaging of mutant strains, including super-resolution (3D-SIM) microscopy of chromosomes and the synaptonemal complex, we show that independently-arising defects in each of these processes in the absence of PPH-4.1 activity ultimately lead to meiotic nondisjunction and embryonic lethality. Interestingly, we find that defects in double-strand break initiation and crossover formation, but not pairing or synapsis, become even more severe in the germlines of older mutant animals, indicating an increased dependence on PPH-4.1 with increasing maternal age. Our results demonstrate that PPH-4.1 plays multiple, independent roles in meiotic prophase chromosome dynamics and maintaining meiotic competence in aging germlines. PP4's high degree of conservation suggests it may be a universal regulator of meiotic prophase chromosome dynamics. PMID:25340746

Singlet-paired coupled cluster theory for open shells

NASA Astrophysics Data System (ADS)

Gomez, John A.; Henderson, Thomas M.; Scuseria, Gustavo E.

2016-06-01

Restricted single-reference coupled cluster theory truncated to single and double excitations accurately describes weakly correlated systems, but often breaks down in the presence of static or strong correlation. Good coupled cluster energies in the presence of degeneracies can be obtained by using a symmetry-broken reference, such as unrestricted Hartree-Fock, but at the cost of good quantum numbers. A large body of work has shown that modifying the coupled cluster ansatz allows for the treatment of strong correlation within a single-reference, symmetry-adapted framework. The recently introduced singlet-paired coupled cluster doubles (CCD0) method is one such model, which recovers correct behavior for strong correlation without requiring symmetry breaking in the reference. Here, we extend singlet-paired coupled cluster for application to open shells via restricted open-shell singlet-paired coupled cluster singles and doubles (ROCCSD0). The ROCCSD0 approach retains the benefits of standard coupled cluster theory and recovers correct behavior for strongly correlated, open-shell systems using a spin-preserving ROHF reference.

Recombination Proteins Mediate Meiotic Spatial Chromosome Organization and Pairing

PubMed Central

Storlazzi, Aurora; Gargano, Silvana; Ruprich-Robert, Gwenael; Falque, Matthieu; David, Michelle; Kleckner, Nancy; Zickler, Denise

2010-01-01

SUMMARY Meiotic chromosome pairing involves not only recognition of homology but also juxtaposition of entire chromosomes in a topologically regular way. Analysis of filamentous fungus Sordaria macrospora reveals that recombination proteins Mer3, Msh4 and Mlh1 play direct roles in all of these aspects, in advance of their known roles in recombination. Absence of Mer3 helicase results in interwoven chromosomes, thereby revealing the existence of features that specifically ensure “entanglement avoidance”. Entanglements that remain at zygotene, i.e. “interlockings”, require Mlh1 for resolution, likely to eliminate constraining recombinational connections. Patterns of Mer3 and Msh4 foci along aligned chromosomes show that the double-strand breaks mediating homologous alignment have spatially separated ends, one localized to each partner axis, and that pairing involves interference among developing interhomolog interactions. We propose that Mer3, Msh4 and Mlh1 execute all of these roles during pairing by modulating the state of nascent double-strand break/partner DNA contacts within axis-associated recombination complexes. PMID:20371348

Symmetry breaking motion of a vortex pair in a driven cavity

NASA Astrophysics Data System (ADS)

McHugh, John; Osman, Kahar; Farias, Jason

2002-11-01

The two-dimensional driven cavity problem with an anti-symmetric sinusoidal forcing has been found to exhibit a subcritical symmetry breaking bifurcation (Farias and McHugh, Phys. Fluids, 2002). Equilibrium solutions are either a symmetric vortex pair or an asymmetric motion. The asymmetric motion is an asymmetric vortex pair at low Reynolds numbers, but merges into a three vortex motion at higher Reynolds numbers. The asymmetric solution is obtained by initiating the flow with a single vortex centered in the domain. Symmetric motion is obtained with no initial vortex, or weak initial vortex. The steady three-vortex motion occurs at a Reynolds number of approximately 3000, where the symmetric vortex pair has already gone through a Hopf bifurcation. Further two-dimensional results show that forcing with two full oscillations across the top of the cavity results in two steady vortex motions, depending on initial conditions. Three-dimensional results have even more steady solutions. The results are computational and theoretical.

Three dimensional chiral plasmon rulers based on silver nanorod trimers.

PubMed

Han, Chunrui; Yang, Lechen; Ye, Piao; Parrott, Edward P J; Pickwell-Macpherson, Emma; Tam, Wing Yim

2018-04-16

The symmetry dependences of plasmon excitation modes are studied in 3D silver nanorod trimers. The degenerate plasmon modes split into chiral modes by breaking the inversion and mirror symmetry of the nanorod trimer through translation and/or rotation of the middle rod. With a translation operation, successive evolution of the circular dichroism (CD) spectrum can be achieved through gradual breaking of the inversion symmetry. An additional rotation operation produces even dramatic spectral changes due to breaking a quasi-mirror symmetry resulted from the same angular distance of the middle rod to the top and bottom rods. Especially, pairs of new chiral modes can be excited due to the contact of the middle rod with the top-bottom rod pair. The spectral changes in the simulations, which are also demonstrated experimentally, envision the 3D chiral nanorod trimer system as plasmon ruler for spatial configuration retrieval and dynamic bio-process analysis at the single molecule level.

Why soft UV-A damages DNA: An optical micromanipulation study

NASA Astrophysics Data System (ADS)

Rapp, A.; Greulich, K. O.

2013-09-01

Optical micromanipulation studies have solved a puzzle on DNA damage and repair. Such knowledge is crucial for understanding cancer and ageing. So far it was not understood, why the soft UV component of sunlight, UV-A, causes the dangerous DNA double strand breaks. The energy of UV-A photons is below 4 eV per photon, too low to directly cleave the corresponding chemical bonds in DNA. This is occasionally used to claim that artificial sunbeds, which mainly use UV-A, would not impose a risk on health. UV-A is only sufficient for induction of single strand breaks. The essential new observation is that, when on the opposite strand there is another single strand break at a distance of up to 20 base pairs. These two breaks will be converted into a break of the whole double strand with all its known consequences for cancer and ageing. However, in natural sun the effect is counteracted. Simultaneous red light illumination reduces UV induced DNA damages to 1/3. Since sunlight has a red component, skin tanning with natural sun is not as risky as might appear at a first glance.

Cooper pair induced frustration and nematicity of two-dimensional magnetic adatom lattices

NASA Astrophysics Data System (ADS)

Schecter, Michael; Syljuâsen, Olav F.; Paaske, Jens

2018-05-01

We propose utilizing the Cooper pair to induce magnetic frustration in systems of two-dimensional (2D) magnetic adatom lattices on s -wave superconducting surfaces. The competition between singlet electron correlations and the RKKY coupling is shown to lead to a variety of hidden-order states that break the point-group symmetry of the 2D adatom lattice at finite temperature. The phase diagram is constructed using a newly developed effective bond theory [M. Schecter et al., Phys. Rev. Lett. 119, 157202 (2017), 10.1103/PhysRevLett.119.157202], and exhibits broad regions of long-range vestigial nematic order.

Repair of DNA double-strand breaks and cell killing by charged particles

NASA Astrophysics Data System (ADS)

Eguchi-Kasai, K.; Murakami, M.; Itsukaichi, H.; Fukutsu, K.; Yatagai, F.; Kanai, T.; Ohara, H.; Sato, K.

It has been suggested that it is not simple double-strand breaks (dsb) but the non-reparable breaks which correlate well with the high biological effectiveness of high LET radiations for cell killing. We have compared the effects of charged particles on cell death in 3 pairs of cell lines which are normal or defective in the repair of DNA dsbs. For the cell lines SL3-147, M10, and SX10 which are deficient in DNA dsb repair, RBE values were close to unity for cell killing induced by charged particles with linear energy transfer (LET) up to 200 keV/mum and were even smaller than unity for the LET region greater than 300 keV/mum. The inactivation cross section (ICS) increased with LET for all 3 pairs. The ICS of dsb repair deficient mutants was always larger than that of their parents for all the LET ranges, but with increasing LET the difference in ICS between the mutant and its parent became smaller. Since a small difference in ICS remained at LET of about 300 keV/mum, dsb repair may still take place at this high LET, even if its role is apparently small. These results suggest that the DNA repair system does not play a major role in protection against the attack of high LET radiations and that a main cause of cell death is non-reparable dsb which are produced at a higher yield compared with low LET radiations. No correlation was observed between DNA content or nuclear area and ICS.

Probing the electroweak phase transition via enhanced di-Higgs boson production

NASA Astrophysics Data System (ADS)

Carena, Marcela; Liu, Zhen; Riembau, Marc

2018-05-01

We consider a singlet extension of the standard model (SM) with a spontaneous Z2 breaking and study the gluon-gluon fusion production of the heavy scalar, with subsequent decay into a pair of SM-like Higgs bosons. We find that an on-shell interference effect can notably enhance the resonant di-Higgs production rate up to 40%. In addition, consistently taking into account both the on-shell and off-shell interference effects between the heavy scalar and the SM di-Higgs diagrams significantly improves the HL-LHC and HE-LHC reach in this channel. As an example, within an effective field theory analysis in an explicitly Z2 breaking scenario, we further discuss the potential to probe the parameter region compatible with a first-order electroweak phase transition. Our analysis is applicable for general potentials of the singlet extension of the SM as well as for more general resonance searches.

Probing Electroweak Phase Transition via Enhanced Di-Higgs Production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carena, Marcela; Liu, Zhen; Riembau, Marc

2018-01-02

We consider a singlet extension of the Standard Model (SM) with a spontaneousmore » $$Z_2$$ breaking and study the gluon-gluon fusion production of the heavy scalar, with subsequent decay into a pair of SM-like Higgs bosons. We find that an on-shell interference effect can notably enhance the resonant di-Higgs production rate up to 40\\%. In addition, consistently taking into account both the on-shell and off-shell interference effects between the heavy scalar and the SM di-Higgs diagrams significantly improves the HL-LHC and HE-LHC reach in this channel. As an example, within an effective field theory analysis in an explicitly $$Z_2$$ breaking scenario, we further discuss the potential to probe the parameter region compatible with a first order electroweak phase transition. Our analysis is applicable for general potentials of the singlet extension of the SM as well as for more general resonance searches.« less

Probing Electroweak Phase Transition via Enhanced Di-Higgs Production

DOE PAGES

Carena, Marcela; Liu, Zhen; Riembau, Marc

2018-05-24

We consider a singlet extension of the Standard Model (SM) with a spontaneousmore » $$Z_2$$ breaking and study the gluon-gluon fusion production of the heavy scalar, with subsequent decay into a pair of SM-like Higgs bosons. We find that an on-shell interference effect can notably enhance the resonant di-Higgs production rate up to 40\\%. In addition, consistently taking into account both the on-shell and off-shell interference effects between the heavy scalar and the SM di-Higgs diagrams significantly improves the HL-LHC and HE-LHC reach in this channel. As an example, within an effective field theory analysis in an explicitly $$Z_2$$ breaking scenario, we further discuss the potential to probe the parameter region compatible with a first order electroweak phase transition. Our analysis is applicable for general potentials of the singlet extension of the SM as well as for more general resonance searches.« less

Window type: paired 3x2 multipaned steel window flanked by 1x3 ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Window type: paired 3x2 multipaned steel window flanked by 1x3 multipaned steel casements, breaking building corner. Broad overhanging eave also illustrated. Second story detail. Building 13, facing east - Harbor Hills Housing Project, 26607 Western Avenue, Lomita, Los Angeles County, CA

Twisted complex superfluids in optical lattices

PubMed Central

Jürgensen, Ole; Sengstock, Klaus; Lühmann, Dirk-Sören

2015-01-01

We show that correlated pair tunneling drives a phase transition to a twisted superfluid with a complex order parameter. This unconventional superfluid phase spontaneously breaks the time-reversal symmetry and is characterized by a twisting of the complex phase angle between adjacent lattice sites. We discuss the entire phase diagram of the extended Bose—Hubbard model for a honeycomb optical lattice showing a multitude of quantum phases including twisted superfluids, pair superfluids, supersolids and twisted supersolids. Furthermore, we show that the nearest-neighbor interactions lead to a spontaneous breaking of the inversion symmetry of the lattice and give rise to dimerized density-wave insulators, where particles are delocalized on dimers. For two components, we find twisted superfluid phases with strong correlations between the species already for surprisingly small pair-tunneling amplitudes. Interestingly, this ground state shows an infinite degeneracy ranging continuously from a supersolid to a twisted superfluid. PMID:26345721

Effect of the pseudogap on the transition temperature in the cuprates and implications for its origin

DOE PAGES

Mishra, Vivek; Chatterjee, U.; Campuzano, J. C.; ...

2014-03-30

We present cuprates that possess a large pseudogap that spans much of their phase diagram. The origin of this pseudogap is as debated as the mechanism for high-temperature superconductivity. In one class of theories, the pseudogap arises from some instability not related to pairing, typically charge, spin or orbital current ordering. Evidence of this has come from a variety of measurements indicating symmetry breaking. On the other side are theories where the pseudogap is associated with pairing. This ranges from preformed pairs to resonating valence bond theories where spin singlets become charge coherent. Here, we study pairing in the cupratesmore » by constructing the pair vertex using spectral functions derived from angle-resolved photoemission data. Assuming that the pseudogap is not due to pairing, we find that the superconducting instability is strongly suppressed, in stark contrast to what is actually observed. We trace this suppression to the destruction of the BCS logarithmic singularity from a combination of the pseudogap and lifetime broadening. In conclusion, our findings strongly support those theories of the cuprates where the pseudogap is instead due to pairing.« less

Golden probe of electroweak symmetry breaking

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Yi; Lykken, Joe; Spiropulu, Maria

The ratio of the Higgs couplings tomore » $WW$ and $ZZ$ pairs, $$\\lambda_{WZ}$$, is a fundamental parameter in electroweak symmetry breaking as well as a measure of the (approximate) custodial symmetry possessed by the gauge boson mass matrix. We show that Higgs decays to four leptons are sensitive, via tree level/1-loop interference effects, to both the magnitude and, in particular, overall sign of $$\\lambda_{WZ}$$. Determining this sign requires interference effects, as it is nearly impossible to measure with rate information. Furthermore, simply determining the sign effectively establishes the custodial representation of the Higgs boson. We find that $$h\\to4\\ell$$ ($$4\\ell \\equiv 2e2\\mu, 4e, 4\\mu$$) decays have excellent prospects of directly establishing the overall sign at a high luminosity 13 TeV LHC. We also examine the ultimate LHC sensitivity in $$h\\to4\\ell$$ to the magnitude of $$\\lambda_{WZ}$$. Our results are independent of other measurements of the Higgs boson couplings and, in particular, largely free of assumptions about the top quark Yukawa couplings which also enter at 1-loop. Furthermore, this makes $$h\\to4\\ell$$ a unique and independent probe of the electroweak symmetry breaking mechanism and custodial symmetry.« less

Golden probe of electroweak symmetry breaking

DOE PAGES

Chen, Yi; Lykken, Joe; Spiropulu, Maria; ...

2016-12-09

The ratio of the Higgs couplings tomore » $WW$ and $ZZ$ pairs, $$\\lambda_{WZ}$$, is a fundamental parameter in electroweak symmetry breaking as well as a measure of the (approximate) custodial symmetry possessed by the gauge boson mass matrix. We show that Higgs decays to four leptons are sensitive, via tree level/1-loop interference effects, to both the magnitude and, in particular, overall sign of $$\\lambda_{WZ}$$. Determining this sign requires interference effects, as it is nearly impossible to measure with rate information. Furthermore, simply determining the sign effectively establishes the custodial representation of the Higgs boson. We find that $$h\\to4\\ell$$ ($$4\\ell \\equiv 2e2\\mu, 4e, 4\\mu$$) decays have excellent prospects of directly establishing the overall sign at a high luminosity 13 TeV LHC. We also examine the ultimate LHC sensitivity in $$h\\to4\\ell$$ to the magnitude of $$\\lambda_{WZ}$$. Our results are independent of other measurements of the Higgs boson couplings and, in particular, largely free of assumptions about the top quark Yukawa couplings which also enter at 1-loop. Furthermore, this makes $$h\\to4\\ell$$ a unique and independent probe of the electroweak symmetry breaking mechanism and custodial symmetry.« less

Generalized seniority on a deformed single-particle basis

NASA Astrophysics Data System (ADS)

Jia, L. Y.

2017-09-01

Recently, I proposed a fast computing scheme for generalized seniority on a spherical single-particle basis [J. Phys. G: Nucl. Part. Phys. 42, 115105 (2015), 10.1088/0954-3899/42/11/115105]. This work redesigns the scheme to make it applicable to deformed single-particle basis. The algorithm is applied to the rare-earth-metal nucleus 94 64 158Gd for intrinsic (body-fixed frame) neutron excitations under the low-momentum NN interaction Vlow -k. By allowing as many as four broken pairs, I compute the lowest 300 intrinsic states of several multipolarities. These states converge well to the exact ones, showing generalized seniority is very effective in truncating the deformed shell model. Under realistic interactions, the picture remains approximately valid: The ground state is a coherent pair condensate and the pairs gradually break up as excitation energy increases.

Schwinger effect in de Sitter space

NASA Astrophysics Data System (ADS)

Fröb, Markus B.; Garriga, Jaume; Kanno, Sugumi; Sasaki, Misao; Soda, Jiro; Tanaka, Takahiro; Vilenkin, Alexander

2014-04-01

We consider Schwinger pair production in 1+1 dimensional de Sitter space, filled with a constant electric field E. This can be thought of as a model for describing false vacuum decay beyond the semiclassical approximation, where pairs of a quantum field phi of mass m and charge e play the role of vacuum bubbles. We find that the adiabatic ``in" vacuum associated with the flat chart develops a space-like expectation value for the current J, which manifestly breaks the de Sitter invariance of the background fields. We derive a simple expression for J(E), showing that both ``upward" and ``downward" tunneling contribute to the build-up of the current. For heavy fields, with m2 gg eE,H2, the current is exponentially suppressed, in agreement with the results of semiclassical instanton methods. Here, H is the inverse de Sitter radius. On the other hand, light fields with m ll H lead to a phenomenon of infrared hyperconductivity, where a very small electric field mHlesssimeE ll H2 leads to a very large current J ~ H3/E. We also show that all Hadamard states for phi necessarily break de Sitter invariance. Finally, we comment on the role of initial conditions, and ``persistence of memory" effects.

Non-Equilibrium Superconductivity and Magnetic Pair Breaking in Perovskite Half-Metallic Ferromagnet-Insulator-Superconductor (F-I-S) Heterostructures

NASA Technical Reports Server (NTRS)

Fu, C.-C.; Yeh, N.-C.; Samoilov, A. V.; Vakili, K.; Li, Y.; Vasquez, R. P.

1999-01-01

The effect of spin-polarized quasiparticle currents on the critical current density (J-c) of cuprate superconductors is studied in perovskite F-I-S heterostructures as a function of insulator thickness and of underlying magnetic materials. A pulsed current technique is employed to minimize extraneous Joule heating on the superconductor. At temperatures near T-c, F-I-S samples with insulator thicknesses\\1e2nm show precipitous decrease in J_c as current injection (I_m) is increased. In contrast, J_c in a controlled sample with a substituted non-magnetic material (N-I-S) exhibit no dependence on I_m. Similarly, a F-I-S sample with a 10 mn insulating barrier also show little J_c effect versus I_m. At low temperatures with I_m = 0, significant suppression of J-c is observed only in the thin barrier F-I-S samples, although T_c and the normal-state resistivity of all samples are comparable. These phenomena can be attributed to the Cooper pair breaking induced by externally-injected and internally-reflected spin-polarized quasiparticle currents. We estimate an order of magnitude range for the spin diffusion length of 100 nm to 100\\ mum.

Window type: paired 2x4 multipaned steel windows flanked by 1x4 ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Window type: paired 2x4 multipaned steel windows flanked by 1x4 multipaned steel casements, breaking building corner. Raised panel door front entry also illustrated. Ground floor detail Building 19, facing north - Harbor Hills Housing Project, 26607 Western Avenue, Lomita, Los Angeles County, CA

Disorder-controlled superconductivity at YBa2Cu3O7/SrTiO3 interfaces

NASA Astrophysics Data System (ADS)

Garcia-Barriocanal, J.; Perez-Muñoz, A. M.; Sefrioui, Z.; Arias, D.; Varela, M.; Leon, C.; Pennycook, S. J.; Santamaria, J.

2013-06-01

We examine the effect of interface disorder in suppressing superconductivity in coherently grown ultrathin YBa2Cu3O7 (YBCO) layers on SrTiO3 (STO) in YBCO/STO superlattices. The termination plane of the STO is TiO2 and the CuO chains are missing at the interface. Disorder (steps) at the STO interface cause alterations of the stacking sequence of the intracell YBCO atomic layers. Stacking faults give rise to antiphase boundaries which break the continuity of the CuO2 planes and depress superconductivity. We show that superconductivity is directly controlled by interface disorder outlining the importance of pair breaking and localization by disorder in ultrathin layers.

Filtering out signals of gauge-mediated supersymmetry breaking: Can we always eliminate conventional supersymmetric effects?

NASA Astrophysics Data System (ADS)

Mukhopadhyaya, Biswarup; Roy, Sourov

1998-06-01

We investigate the signal γγ+E/ in a high-energy linear e+e- collider, with a view to differentiating between gauge-mediated supersymmetry breaking and the conventional supersymmetric models. Prima facie, there is considerable chance of confusion between the two scenarios if the assumption of gaugino mass unification is relaxed. We show that the use of polarized electron beams enables one to distinguish between the two schemes in most cases. There are some regions in the parameter space where this idea does not work, and we suggest some additional methods of distinction. We also perform an analysis of some signals in the gauge-mediated model, coming from the pair production of the second-lightest neutralino.

Insulative laser shell coupler

DOEpatents

Arnold, Phillip A.; Anderson, Andrew T.; Alger, Terry W.

1994-01-01

A segmented coaxial laser shell assembly having at least two water jacket sections, two pairs of interconnection half rings, a dialectric break ring, and a pair of threaded ring sections. Each water jacket section with an inner tubular section that defines an inner laser cavity with water paths adjacent to at least a portion of the exterior of the inner tubular section, and mating faces at the end of the water jacket section through which the inner laser cavity opens and which defines at least one water port therethrough in communication with the water jackets. The water paths also define in their external surface a circumferential notch set back from and in close proximity to the mating face. The dielectric break ring has selected thickness and is placed between, and in coaxial alignment with, the mating faces of two of the adjacent water jacket sections. The break ring also defines an inner laser cavity of the same size and shape as the inner laser cavity of the water jacket sections and at least one water passage through the break ring to communicate with at least one water port through the mating faces of the water jacket sections.

Insulative laser shell coupler

DOEpatents

Arnold, P.A.; Anderson, A.T.; Alger, T.W.

1994-09-20

A segmented coaxial laser shell assembly having at least two water jacket sections, two pairs of interconnection half rings, a dielectric break ring, and a pair of threaded ring sections is disclosed. Each water jacket section with an inner tubular section that defines an inner laser cavity with water paths adjacent to at least a portion of the exterior of the inner tubular section, and mating faces at the end of the water jacket section through which the inner laser cavity opens and which defines at least one water port therethrough in communication with the water jackets. The water paths also define in their external surface a circumferential notch set back from and in close proximity to the mating face. The dielectric break ring has selected thickness and is placed between, and in coaxial alignment with, the mating faces of two of the adjacent water jacket sections. The break ring also defines an inner laser cavity of the same size and shape as the inner laser cavity of the water jacket sections and at least one water passage through the break ring to communicate with at least one water port through the mating faces of the water jacket sections. 4 figs.

Dual origin of pairing in nuclei

NASA Astrophysics Data System (ADS)

Idini, A.; Potel, G.; Barranco, F.; Vigezzi, E.; Broglia, R. A.

2016-11-01

The pairing correlations of the nucleus 120Sn 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 1 S 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 p bare) and long-range ( v p 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.

Pairing from dynamically screened Coulomb repulsion in bismuth

NASA Astrophysics Data System (ADS)

Ruhman, Jonathan; Lee, Patrick A.

2017-12-01

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

The CAF-1 and Hir Histone Chaperones Associate with Sites of Meiotic Double-Strand Breaks in Budding Yeast

PubMed Central

Brachet, Elsa; Béneut, Claire; Serrentino, Maria-Elisabetta; Borde, Valérie

2015-01-01

In the meiotic prophase, programmed DNA double-strand breaks (DSB) are introduced along chromosomes to promote homolog pairing and recombination. Although meiotic DSBs usually occur in nucleosome-depleted, accessible regions of chromatin, their repair by homologous recombination takes place in a nucleosomal environment. Nucleosomes may represent an obstacle for the recombination machinery and their timely eviction and reincorporation into chromatin may influence the outcome of recombination, for instance by stabilizing recombination intermediates. Here we show in budding yeast that nucleosomes flanking a meiotic DSB are transiently lost during recombination, and that specific histone H3 chaperones, CAF-1 and Hir, are mobilized at meiotic DSBs. However, the absence of these chaperones has no effect on meiotic recombination, suggesting that timely histone reincorporation following their eviction has no influence on the recombination outcome, or that redundant pathways are activated. This study is the first example of the involvement of histone H3 chaperones at naturally occurring, developmentally programmed DNA double-strand breaks. PMID:25938567

Variability in Conversation Management: Fragmentation of Discourse and Back-Channel Expressions in Japanese and English.

ERIC Educational Resources Information Center

Maynard, Senko K.

The casual conversation of six pairs of Japanese and six pairs of American colleges students was analyzed for evidence of two related aspects of conversation management: the linguistic characteristics of utterance units and back-channel strategies. Utterance units are defined as those occurring between identifiable pauses or breaks in tempo.…

Hydrogen bond disruption in DNA base pairs from (14)C transmutation.

PubMed

Sassi, Michel; Carter, Damien J; Uberuaga, Blas P; Stanek, Christopher R; Mancera, Ricardo L; Marks, Nigel A

2014-09-04

Recent ab initio molecular dynamics simulations have shown that radioactive carbon does not normally fragment DNA bases when it decays. Motivated by this finding, density functional theory and Bader analysis have been used to quantify the effect of C → N transmutation on hydrogen bonding in DNA base pairs. We find that (14)C decay has the potential to significantly alter hydrogen bonds in a variety of ways including direct proton shuttling (thymine and cytosine), thermally activated proton shuttling (guanine), and hydrogen bond breaking (cytosine). Transmutation substantially modifies both the absolute and relative strengths of the hydrogen bonding pattern, and in two instances (adenine and cytosine), the density at the critical point indicates development of mild covalent character. Since hydrogen bonding is an important component of Watson-Crick pairing, these (14)C-induced modifications, while infrequent, may trigger errors in DNA transcription and replication.

Leptotene/Zygotene Chromosome Movement Via the SUN/KASH Protein Bridge in Caenorhabditis elegans

PubMed Central

Baudrimont, Antoine; Penkner, Alexandra; Woglar, Alexander; Machacek, Thomas; Wegrostek, Christina; Gloggnitzer, Jiradet; Fridkin, Alexandra; Klein, Franz; Gruenbaum, Yosef; Pasierbek, Pawel; Jantsch, Verena

2010-01-01

The Caenorhabditis elegans inner nuclear envelope protein matefin/SUN-1 plays a conserved, pivotal role in the process of genome haploidization. CHK-2–dependent phosphorylation of SUN-1 regulates homologous chromosome pairing and interhomolog recombination in Caenorhabditis elegans. Using time-lapse microscopy, we characterized the movement of matefin/SUN-1::GFP aggregates (the equivalent of chromosomal attachment plaques) and showed that the dynamics of matefin/SUN-1 aggregates remained unchanged throughout leptonene/zygotene, despite the progression of pairing. Movement of SUN-1 aggregates correlated with chromatin polarization. We also analyzed the requirements for the formation of movement-competent matefin/SUN-1 aggregates in the context of chromosome structure and found that chromosome axes were required to produce wild-type numbers of attachment plaques. Abrogation of synapsis led to a deceleration of SUN-1 aggregate movement. Analysis of matefin/SUN-1 in a double-strand break deficient mutant revealed that repair intermediates influenced matefin/SUN-1 aggregate dynamics. Investigation of movement in meiotic regulator mutants substantiated that proper orchestration of the meiotic program and effective repair of DNA double-strand breaks were necessary for the wild-type behavior of matefin/SUN-1 aggregates. PMID:21124819

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gomez, John A.; Henderson, Thomas M.; Scuseria, Gustavo E.

Restricted single-reference coupled cluster theory truncated to single and double excitations accurately describes weakly correlated systems, but often breaks down in the presence of static or strong correlation. Good coupled cluster energies in the presence of degeneracies can be obtained by using a symmetry-broken reference, such as unrestricted Hartree-Fock, but at the cost of good quantum numbers. A large body of work has shown that modifying the coupled cluster ansatz allows for the treatment of strong correlation within a single-reference, symmetry-adapted framework. The recently introduced singlet-paired coupled cluster doubles (CCD0) method is one such model, which recovers correct behavior formore » strong correlation without requiring symmetry breaking in the reference. Here, we extend singlet-paired coupled cluster for application to open shells via restricted open-shell singlet-paired coupled cluster singles and doubles (ROCCSD0). The ROCCSD0 approach retains the benefits of standard coupled cluster theory and recovers correct behavior for strongly correlated, open-shell systems using a spin-preserving ROHF reference.« less

High-seniority states in spherical nuclei: Triple pair breaking in tin isotopes

NASA Astrophysics Data System (ADS)

Astier, Alain

2013-03-01

The 119-126Sn nuclei have been produced as fission fragments in two reactions induced by heavy ions: 12C+238U at 90 MeV bombarding energy, 18O+208Pb at 85 MeV. Their level schemes have been built from gamma rays detected using the Euroball array. High-spin states located above the long-lived isomeric states of the even- A and odd-A 120-126Sn nuclei have been identified. Moreover isomeric states lying around 4.5 MeV have been established in the even-A 120-126Sn from the delayed coincidences between the fission fragment detector SAPhIR and the Euroball array. All the states located above 3-MeV excitation energy are ascribed to several broken pairs of neutrons occupying the h11/2 orbit. The maximum value of angular momentum available in such a high-j shell, i.e. for mid-occupation and the breaking of the three neutron pairs (seniority v=6), has been identified.

Fluctuations in the electron system of a superconductor exposed to a photon flux

PubMed Central

de Visser, P. J.; Baselmans, J. J. A.; Bueno, J.; Llombart, N.; Klapwijk, T. M.

2014-01-01

In a superconductor, in which electrons are paired, the density of unpaired electrons should become zero when approaching zero temperature. Therefore, radiation detectors based on breaking of pairs promise supreme sensitivity, which we demonstrate using an aluminium superconducting microwave resonator. Here we show that the resonator also enables the study of the response of the electron system of the superconductor to pair-breaking photons, microwave photons and varying temperatures. A large range in radiation power (at 1.54 THz) can be chosen by carefully filtering the radiation from a blackbody source. We identify two regimes. At high radiation power, fluctuations in the electron system caused by the random arrival rate of the photons are resolved, giving a straightforward measure of the optical efficiency (48±8%) and showing an unprecedented detector sensitivity. At low radiation power, fluctuations are dominated by excess quasiparticles, the number of which is measured through their recombination lifetime. PMID:24496036

Superconducting properties of lithographic lead break junctions

NASA Astrophysics Data System (ADS)

Weber, David; Scheer, Elke

2018-01-01

We have fabricated mechanically controlled break junction samples made of lead (Pb) by means of state-of-the-art nanofabrication methods: electron beam lithography and physical vapour deposition. The electrical and magnetic properties were characterized in a {}3{He} cryostat and showed a hard superconducting gap. Temperature and magnetic field dependence of tunnel contacts were compared and quantitatively described by including either thermal broadening of the density of states or pair breaking in the framework of a Skalski model, respectively. We show point contact spectra of few-atom contacts and present tunneling spectra exhibiting a superconducting double-gap structure.

Probing the electroweak phase transition via enhanced di-Higgs boson production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carena, Marcela; Liu, Zhen; Riembau, Marc

Here, we consider a singlet extension of the Standard Model (SM) with a spontaneousmore » $$Z_2$$ breaking and study the gluon-gluon fusion production of the heavy scalar, with subsequent decay into a pair of SM-like Higgs bosons. We find that an on-shell interference effect can notably enhance the resonant di-Higgs production rate up to 40\\%. In addition, consistently taking into account both the on-shell and off-shell interference effects between the heavy scalar and the SM di-Higgs diagrams significantly improves the HL-LHC and HE-LHC reach in this channel. As an example, within an effective field theory analysis in an explicitly $$Z_2$$ breaking scenario, we further discuss the potential to probe the parameter region compatible with a first order electroweak phase transition. Our analysis is applicable for general potentials of the singlet extension of the SM as well as for more general resonance searches.« less

Probing the electroweak phase transition via enhanced di-Higgs boson production

DOE PAGES

Carena, Marcela; Liu, Zhen; Riembau, Marc

2018-05-24

Here, we consider a singlet extension of the Standard Model (SM) with a spontaneousmore » $$Z_2$$ breaking and study the gluon-gluon fusion production of the heavy scalar, with subsequent decay into a pair of SM-like Higgs bosons. We find that an on-shell interference effect can notably enhance the resonant di-Higgs production rate up to 40\\%. In addition, consistently taking into account both the on-shell and off-shell interference effects between the heavy scalar and the SM di-Higgs diagrams significantly improves the HL-LHC and HE-LHC reach in this channel. As an example, within an effective field theory analysis in an explicitly $$Z_2$$ breaking scenario, we further discuss the potential to probe the parameter region compatible with a first order electroweak phase transition. Our analysis is applicable for general potentials of the singlet extension of the SM as well as for more general resonance searches.« less

Effect of fluctuations on the NMR relaxation beyond the Abrikosov vortex state

DOE PAGES

Glatz, A.; Galda, A.; Varlamov, A. A.

2015-08-25

Here, the effect of fluctuations on the nuclear magnetic resonance (NMR) relaxation rate W = T –1 1 is studied in a complete phase diagram of a two-dimensional superconductor above the upper critical field line H c2(T). In the region of relatively high temperatures and low magnetic fields, the relaxation rate W is determined by two competing effects. The first one is its decrease in the result of suppression of the quasiparticle density of states (DOS) due to formation of fluctuation Cooper pairs (FCPs). The second one is a specific, purely quantum relaxation process of the Maki-Thompson (MT) type, whichmore » for low field leads to an increase of the relaxation rate. The latter describes particular fluctuation processes involving self-pairing of a single electron on self-intersecting trajectories of a size up to phase-breaking length ℓ Φ which becomes possible due to an electron spin-flip scattering event at a nucleus. As a result, different scenarios with either growth or decrease of the NMR relaxation rate are possible upon approaching the normal-metal–type-II superconductor transition. The character of fluctuations changes along the line H c2(T) from the thermal long-wavelength type in weak magnetic fields to the clusters of rotating FCPs in fields comparable to Hc2(0). We find that below the well-defined temperature T* 0 ≈ 0.6T c0, the MT process becomes ineffective even in the absence of intrinsic pair breaking. The small scale of the FCP rotations ξ xy in such high fields impedes formation of long (≲ℓ Φ) self-intersecting trajectories, causing the corresponding relaxation mechanism to lose its efficiency. This reduces the effect of superconducting fluctuations in the domain of high fields and low temperatures to just the suppression of quasiparticle DOS, analogous to the Abrikosov vortex phase below the H c2(T) line.« less

Calculation of DNA strand breaks due to direct and indirect effects of Auger electrons from incorporated 123I and 125I radionuclides using the Geant4 computer code.

PubMed

Raisali, Gholamreza; Mirzakhanian, Lalageh; Masoudi, Seyed Farhad; Semsarha, Farid

2013-01-01

In this work the number of DNA single-strand breaks (SSB) and double-strand breaks (DSB) due to direct and indirect effects of Auger electrons from incorporated (123)I and (125)I have been calculated by using the Geant4-DNA toolkit. We have performed and compared the calculations for several cases: (125)I versus (123)I, source positions and direct versus indirect breaks to study the capability of the Geant4-DNA in calculations of DNA damage yields. Two different simple geometries of a 41 base pair of B-DNA have been simulated. The location of (123)I has been considered to be in (123)IdUrd and three different locations for (125)I. The results showed that the simpler geometry is sufficient for direct break calculations while indirect damage yield is more sensitive to the helical shape of DNA. For (123)I Auger electrons, the average number of DSB due to the direct hits is almost twice the DSB due to the indirect hits. Furthermore, a comparison between the average number of SSB or DSB caused by Auger electrons of (125)I and (123)I in (125)IdUrd and (123)IdUrd shows that (125)I is 1.5 times more effective than (123)I per decay. The results are in reasonable agreement with previous experimental and theoretical results which shows the applicability of the Geant-DNA toolkit in nanodosimetry calculations which benefits from the open-source accessibility with the advantage that the DNA models used in this work enable us to save the computational time. Also, the results showed that the simpler geometry is suitable for direct break calculations, while for the indirect damage yield, the more precise model is preferred.

Cooper Pair-Like Systems at High Temperature and their Role on Fluctuations Near the Critical Temperature

NASA Astrophysics Data System (ADS)

Ausloos, M.; Dorbolo, S.

A logarithmic behavior is hidden in the linear temperature regime of the electrical resistivity R(T) of some YBCO sample below 2Tc where "pairs" break apart, fluctuations occur and "a gap is opening". An anomalous effect also occurs near 200 K in the normal state Hall coefficient. In a simulation of oxygen diffusion in planar 123 YBCO, an anomalous behavior is found in the oxygen-vacancy motion near such a temperature. We claim that the behavior of the specific heat above and near the critical temperature should be reexamined in order to show the influence and implications of fluctuations and dimensionality on the nature of the phase transition and on the true onset temperature.

R-Axion: A New LHC Physics Signature Involving Muon Pairs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goh, Hock-Seng; /UC, Berkeley /LBL, Berkeley; Ibe, Masahiro

2012-04-12

In a class of models with gauge mediated supersymmetry breaking, the existence of a light pseudo scalar particle, R-axion, with a mass in hundreds MeV range is predicted. The striking feature of such a light R-axion is that it mainly decays into a pair of muons and leaves a displaced vertex inside detectors once it is produced. In this talk, we show how we can search for the R-axion at the coming LHC experiments. The one main goal of the LHC experiments is discovering supersymmetry which has been anticipated for a long time to solve the hierarchy problem. Once themore » supersymmetric standard model (SSM) is confirmed experimentally, the next question is how the supersymmetry is broken and how the effects of symmetry breaking are mediated to the SSM sector. In most cases, such investigations on 'beyond the SSM physics' rely on arguments based on extrapolations of the observed supersymmetry mass parameters to higher energies. However, there is one class of models of supersymmetry breaking where we can get a direct glimpse of the structure of the hidden sector with the help of the R-symmetry. The R-symmetry plays an important role in rather generic models of spontaneous supersymmetry breaking. At the same time, however, it must be broken in some way in order for the gauginos in the SSM sector to have non-vanishing masses. One possibility of the gaugino mass generation is to consider models where the gaugino masses are generated as a result of the explicit breaking of the R-symmetries. Unfortunately, in those models, the R-symmetry leaves little trace for the collider experiments, since the mass of the R-axion is typically heavy and beyond the reach of the LHC experiments. In this talk, instead, we consider a class of models with gauge mediation where the R-symmetry in the hidden/messenger sectors is exact in the limit of the infinite reduced Planck scale, i.e. M{sub PL} {yields} {infinity}. In this case, the gaugino masses are generated only after the R-symmetry is broken spontaneously. We also assume that the R-symmetry is respected by the SSM sector as well as the origin of the higgsino mass {mu} and the Higgs mass mixing B{mu} at the classical level. We call this scenario, the minimal R-symmetry breaking scenario.« less

Magnetic disorder and gap symmetry in the optimally electron-doped Sr(Fe ,Co ) 2As2 superconductor

NASA Astrophysics Data System (ADS)

Harnagea, Luminita; Mani, Giri; Kumar, Rohit; Singh, Surjeet

2018-02-01

We study magnetic pair breaking due to Mn impurities in the optimally electron-doped superconductor Sr (Fe0.88Co0.12)2As2 . We found that the as-grown Sr (Fe0.88-yCo0.12Mny) 2As2 single crystals exhibit a Tc suppression rate of ˜30 mK/μ Ω cm . This rate is slow but in good agreement with the previous reports on various magnetic/nonmagnetic impurities doped in other structurally analogous iron-based superconductors. The slow Tc suppression rate for magnetic impurities is often cited as an evidence for the nonvalidity of the s++-wave symmetry, which should have suppressed Tc in accordance with the Abrikosov-Gor'kov theory. Here, we show that the crystallographic defects are the main source of pair breaking in the as-grown crystals. Once these defects are healed by a low-temperature annealing, the true Tc suppression rate due to Mn impurities is revealed. We thus estimate the actual Tc suppression rate due to Mn alone to be ≥325 mK / μ Ω cm , and that due to the nonmagnetic crystallographic defects to be nearly 35 mK/μ Ω cm . These findings can be reconciled with the fully gapped s+--wave symmetry provided the interband scattering is rather weak. On the other hand, the s++-wave symmetry, which is resilient to the nonmagnetic defects and fragile against the magnetic impurities, can be a possible pairing symmetry in the optimally electron-doped SrFe2As2 . The crucial information that we provide here is that the magnetic pair breaking in these superconductors is not as weak as is generally believed.

Relative biological effectiveness for photons: implication of complex DNA double-strand breaks as critical lesions

NASA Astrophysics Data System (ADS)

Liang, Ying; Fu, Qibin; Wang, Xudong; Liu, Feng; Yang, Gen; Luo, Chunxiong; Ouyang, Qi; Wang, Yugang

2017-03-01

Current knowledge in radiobiology ascribes the adverse biological effects of ionizing radiation primarily to the induction of DNA double-strand breaks (DSBs), which is supposed to be potentially lethal and may be converted to lethal damage due to misrepair. Soft and ultrasoft x-rays have been found to bear elevated biological effectiveness for cell killing compared with conventional x-rays or 60Co γ-rays. This phenomenon is qualitatively interpreted as the increased level of DSB induction for low energy photons, however, a thorough quantitative reasoning is lacking. Here, we systematically compared the relative biological effectiveness (RBE) with relative DSB induction for photons from several hundreds of eV up to MeV. Although there is an approximate two-fold increase in the yields of DSB for low energy photons found in our calculation and a large number of experimental measurements, it is far from enough to account for the three- to four-fold increase in RBE. Further theoretical investigations show that DSB complexity (additional single-strand breaks and base damage within 10 base pairs) increases notably for low energy photons, which largely reconciles the discrepancy between RBE and DSB induction. Our theoretical results are in line with accumulating experimental evidence that complex DSBs are refractory to repair machinery and may contribute predominantly to the formation of lethal damage.

Kinematically irreversible particle motion in 2D suspensions due to surface-pressure-dependent surface rheology

NASA Astrophysics Data System (ADS)

Manikantan, Harishankar; Squires, Todd

2017-11-01

The surface viscosity of many insoluble surfactants depends strongly on the surface pressure (or surface tension) of that surfactant. Surface pressure gradients naturally arise in interfacial flows, and surface-pressure-dependent surface rheology alters 2D suspension dynamics in significant ways. We use the Lorentz reciprocal theorem to asymptotically quantify the irreversible dynamics that break Newtonian symmetries. We first show that a particle embedded in a surfactant-laden interface and translating parallel to or rotating near an interfacial boundary experiences a force in the direction perpendicular to the boundary. Building on this, we extend the theory to compute the first effects of pressure-dependent surface viscosity on 2D particle pairs in suspension. The fore-aft symmetry of pair trajectories in a Newtonian interface is lost, leading to well-separated (when pressure-thickening) or aggregated (when pressure-thinning) particles. Notably, the relative motion is kinematically irreversible, and pairs steadily evolve toward a particular displacement. Based on these irreversible pair interactions, we hypothesize that pressure-thickening (or -thinning) leads to shear-thinning (or -thickening) in 2D suspensions.

Orbitally limited pair-density-wave phase of multilayer superconductors

NASA Astrophysics Data System (ADS)

Möckli, David; Yanase, Youichi; Sigrist, Manfred

2018-04-01

We investigate the magnetic field dependence of an ideal superconducting vortex lattice in the parity-mixed pair-density-wave phase of multilayer superconductors within a circular cell Ginzburg-Landau approach. In multilayer systems, due to local inversion symmetry breaking, a Rashba spin-orbit coupling is induced at the outer layers. This combined with a perpendicular paramagnetic (Pauli) limiting magnetic field stabilizes a staggered layer dependent pair-density-wave phase in the superconducting singlet channel. The high-field pair-density-wave phase is separated from the low-field BCS phase by a first-order phase transition. The motivating guiding question in this paper is: What is the minimal necessary Maki parameter αM for the appearance of the pair-density-wave phase of a superconducting trilayer system? To address this problem we generalize the circular cell method for the regular flux-line lattice of a type-II superconductor to include paramagnetic depairing effects. Then, we apply the model to the trilayer system, where each of the layers are characterized by Ginzburg-Landau parameter κ0 and a Maki parameter αM. We find that when the spin-orbit Rashba interaction compares to the superconducting condensation energy, the orbitally limited pair-density-wave phase stabilizes for Maki parameters αM>10 .

Dual origin of pairing in nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Idini, A.; Potel, G.; Barranco, F.

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 pairingmore » 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.« less

From decay to complete breaking: pulling the strings in SU(2) Yang-Mills theory.

PubMed

Pepe, M; Wiese, U-J

2009-05-15

We study {2Q+1} strings connecting two static charges Q in (2+1)D SU(2) Yang-Mills theory. While the fundamental {2} string between two charges Q=1/2 is unbreakable, the adjoint {3} string connecting two charges Q=1 can break. When a {4} string is stretched beyond a critical length, it decays into a {2} string by gluon pair creation. When a {5} string is stretched, it first decays into a {3} string, which eventually breaks completely. The energy of the screened charges at the ends of a string is well described by a phenomenological constituent gluon model.

Initial hydration processes of magnesium chloride: size-selected anion photoelectron spectroscopy and ab initio calculations.

PubMed

Feng, Gang; Liu, Cheng-Wen; Zeng, Zhen; Hou, Gao-Lei; Xu, Hong-Guang; Zheng, Wei-Jun

2017-06-14

To understand the initial hydration processes of MgCl 2 , we measured photoelectron spectra of MgCl 2 (H 2 O) n - (n = 0-6) and conducted ab initio calculations on MgCl 2 (H 2 O) n - and their neutral counterparts up to n = 7. A dramatic drop in the vertical detachment energy (VDE) was observed upon addition of the first water molecule to bare MgCl 2 - . This large variation in VDE can be associated with the charge-transfer-to-solvent (CTTS) effect occurring in the MgCl 2 (H 2 O) n - clusters, as hydration induces transfer of the excess electron of MgCl 2 - to the water molecules. Investigation of the separation of Cl - -Mg 2+ ion pair shows that, in MgCl 2 (H 2 O) n - anions, breaking of the first Mg-Cl bond occurs at n = 4, while breaking of the second Mg-Cl bond takes place at n = 6. For neutral MgCl 2 (H 2 O) n clusters, breaking of the first Mg-Cl bond starts at n = 7.

Paired D10A Cas9 nickases are sometimes more efficient than individual nucleases for gene disruption.

PubMed

Gopalappa, Ramu; Suresh, Bharathi; Ramakrishna, Suresh; Kim, Hyongbum Henry

2018-03-23

The use of paired Cas9 nickases instead of Cas9 nuclease drastically reduces off-target effects. Because both nickases must function for a nickase pair to make a double-strand break, the efficiency of paired nickases can intuitively be expected to be lower than that of either corresponding nuclease alone. Here, we carefully compared the gene-disrupting efficiency of Cas9 paired nickases with that of nucleases. Interestingly, the T7E1 assay and deep sequencing showed that on-target efficiency of paired D10A Cas9 nickases was frequently comparable, but sometimes higher than that of either corresponding nucleases in mammalian cells. As the underlying mechanism, we found that the HNH domain, which is preserved in the D10A Cas9 nickase, has higher activity than the RuvC domain in mammalian cells. In this study, we showed: (i) the in vivo cleavage efficiency of the HNH domain of Cas9 in mammalian cells is higher than that of the RuvC domain, (ii) paired Cas9 nickases are sometimes more efficient than individual nucleases for gene disruption. We envision that our findings which were overlooked in previous reports will serve as a new potential guideline for tool selection for CRISPR-Cas9-mediated gene disruption, facilitating efficient and precise genome editing.

Tachyon Condensation and Brane Annihilation in Bose-Einstein Condensates: Spontaneous Symmetry Breaking in Restricted Lower-Dimensional Subspace

NASA Astrophysics Data System (ADS)

Takeuchi, Hiromitsu; Kasamatsu, Kenichi; Tsubota, Makoto; Nitta, Muneto

2013-05-01

In brane cosmology, the Big Bang is hypothesized to occur by the annihilation of the brane-anti-brane pair in a collision, where the branes are three-dimensional objects in a higher-dimensional Universe. Spontaneous symmetry breaking accompanied by the formation of lower-dimensional topological defects, e.g. cosmic strings, is triggered by the so-called `tachyon condensation', where the existence of tachyons is attributable to the instability of the brane-anti-brane system. Here, we discuss the closest analogue of the tachyon condensation in atomic Bose-Einstein condensates. We consider annihilation of domain walls, namely branes, in strongly segregated two-component condensates, where one component is sandwiched by two domains of the other component. In this system, the process of the brane annihilation can be projected effectively as ferromagnetic ordering dynamics onto a two-dimensional space. Based on this correspondence, three-dimensional formation of vortices from a domain-wall annihilation is considered to be a kink formation due to spontaneous symmetry breaking in the two-dimensional space. We also discuss a mechanism to create a `vorton' when the sandwiched component has a vortex string bridged between the branes. We hope that this study motivates experimental researches to realize this exotic phenomenon of spontaneous symmetry breaking in superfluid systems.

Su-Schrieffer-Heeger chain with one pair of [Formula: see text]-symmetric defects.

PubMed

Jin, L; Wang, P; Song, Z

2017-07-19

The topologically nontrivial edge states induce [Formula: see text] transition in Su-Schrieffer-Heeger (SSH) chain with one pair of gain and loss at boundaries. In this study, we investigated a pair of [Formula: see text]-symmetric defects located inside the SSH chain, in particular, the defects locations are at the chain centre. The [Formula: see text] symmetry breaking of the bound states leads to the [Formula: see text] transition, the [Formula: see text]-symmetric phases and the localized states were studied. In the broken [Formula: see text]-symmetric phase, all energy levels break simultaneously in topologically trivial phase; however, two edge states in topologically nontrivial phase are free from the influence of the [Formula: see text]-symmetric defects. We discovered [Formula: see text]-symmetric bound states induced by the [Formula: see text]-symmetric local defects at the SSH chain centre. The [Formula: see text]-symmetric bound states significantly increase the [Formula: see text] transition threshold and coalesce to the topologically protected zero mode with vanishing probabilities on every other site of the left-half chain and the right-half chain, respectively.

Entangled-photon coincidence fluorescence imaging

PubMed Central

Scarcelli, Giuliano; Yun, Seok H.

2009-01-01

We describe fluorescence imaging using the second-order correlation of entangled photon pairs. The proposed method is based on the principle that one photon of the pair carries information on where the other photon has been absorbed and has produced fluorescence in a sample. Because fluorescent molecules serve as “detectors” breaking the entanglement, multiply-scattered fluorescence photons within the sample do not cause image blur. We discuss experimental implementations. PMID:18825257

Compressive buckling of black phosphorene nanotubes: an atomistic study

NASA Astrophysics Data System (ADS)

Nguyen, Van-Trang; Le, Minh-Quy

2018-04-01

We investigate through molecular dynamics finite element method with Stillinger-Weber potential the uniaxial compression of armchair and zigzag black phosphorene nanotubes. We focus especially on the effects of the tube’s diameter with fixed length-diameter ratio, effects of the tube’s length for a pair of armchair and zigzag tubes of equal diameters, and effects of the tube’s diameter with fixed lengths. Their Young’s modulus, critical compressive stress and critical compressive strain are studied and discussed for these 3 case studies. Compressive buckling was clearly observed in the armchair nanotubes. Local bond breaking near the boundary occurred in the zigzag ones under compression.

Watson-Crick Base Pair Radical Cation as a Model for Oxidative Damage in DNA.

PubMed

Feketeová, Linda; Chan, Bun; Khairallah, George N; Steinmetz, Vincent; Maitre, Philippe; Radom, Leo; O'Hair, Richard A J

2017-07-06

The deleterious cellular effects of ionizing radiation are well-known, but the mechanisms causing DNA damage are poorly understood. The accepted molecular events involve initial oxidation and deprotonation at guanine sites, triggering hydrogen atom abstraction reactions from the sugar moieties, causing DNA strand breaks. Probing the chemistry of the initially formed radical cation has been challenging. Here, we generate, spectroscopically characterize, and examine the reactivity of the Watson-Crick nucleobase pair radical cation in the gas phase. We observe rich chemistry, including proton transfer between the bases and propagation of the radical site in deoxyguanosine from the base to the sugar, thus rupturing the sugar. This first example of a gas-phase model system providing molecular-level details on the chemistry of an ionized DNA base pair paves the way toward a more complete understanding of molecular processes induced by radiation. It also highlights the role of radical propagation in chemistry, biology, and nanotechnology.

Bond rupture between colloidal particles with a depletion interaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whitaker, Kathryn A.; Furst, Eric M., E-mail: furst@udel.edu

The force required to break the bonds of a depletion gel is measured by dynamically loading pairs of colloidal particles suspended in a solution of a nonadsorbing polymer. Sterically stabilized poly(methyl methacrylate) colloids that are 2.7 μm diameter are brought into contact in a solvent mixture of cyclohexane-cyclohexyl bromide and polystyrene polymer depletant. The particle pairs are subject to a tensile load at a constant loading rate over many approach-retraction cycles. The stochastic nature of the thermal rupture events results in a distribution of bond rupture forces with an average magnitude and variance that increases with increasing depletant concentration. The measuredmore » force distribution is described by the flux of particle pairs sampling the energy barrier of the bond interaction potential based on the Asakura–Oosawa depletion model. A transition state model demonstrates the significance of lubrication hydrodynamic interactions and the effect of the applied loading rate on the rupture force of bonds in a depletion gel.« less

Topological superconductivity in monolayer transition metal dichalcogenides.

PubMed

Hsu, Yi-Ting; Vaezi, Abolhassan; Fischer, Mark H; Kim, Eun-Ah

2017-04-11

Theoretically, it has been known that breaking spin degeneracy and effectively realizing spinless fermions is a promising path to topological superconductors. Yet, topological superconductors are rare to date. Here we propose to realize spinless fermions by splitting the spin degeneracy in momentum space. Specifically, we identify monolayer hole-doped transition metal dichalcogenide (TMD)s as candidates for topological superconductors out of such momentum-space-split spinless fermions. Although electron-doped TMDs have recently been found superconducting, the observed superconductivity is unlikely topological because of the near spin degeneracy. Meanwhile, hole-doped TMDs with momentum-space-split spinless fermions remain unexplored. Employing a renormalization group analysis, we propose that the unusual spin-valley locking in hole-doped TMDs together with repulsive interactions selectively favours two topological superconducting states: interpocket paired state with Chern number 2 and intrapocket paired state with finite pair momentum. A confirmation of our predictions will open up possibilities for manipulating topological superconductors on the device-friendly platform of monolayer TMDs.

Higgs pair production at NLO QCD for CP-violating Higgs sectors

NASA Astrophysics Data System (ADS)

Gröber, R.; Mühlleitner, M.; Spira, M.

2017-12-01

Higgs pair production through gluon fusion is an important process at the LHC to test the dynamics underlying electroweak symmetry breaking. Higgs sectors beyond the Standard Model (SM) can substantially modify this cross section through novel couplings not present in the SM or the on-shell production of new heavy Higgs bosons that subsequently decay into Higgs pairs. CP violation in the Higgs sector is important for the explanation of the observed matter-antimatter asymmetry through electroweak baryogenesis. In this work we compute the next-to-leading order (NLO) QCD corrections in the heavy top quark limit, including the effects of CP violation in the Higgs sector. We choose the effective theory (EFT) approach, which provides a rather model-independent way to explore New Physics (NP) effects by adding dimension-6 operators, both CP-conserving and CP-violating ones, to the SM Lagrangian. Furthermore, we perform the computation within a specific UV-complete model and choose as benchmark model the general 2-Higgs-Doublet Model with CP violation, the C2HDM. Depending on the dimension-6 coefficients, the relative NLO QCD corrections are affected by several per cent through the new CP-violating operators. This is also the case for SM-like Higgs pair production in the C2HDM, while the relative QCD corrections in the production of heavier C2HDM Higgs boson pairs deviate more strongly from the SM case. The absolute cross sections both in the EFT and the C2HDM can be modified by more than an order of magnitude. In particular, in the C2HDM the resonant production of Higgs pairs can by far exceed the SM cross section.

Effects of Thai Dancing on Median Neurodynamic Response During 4-Hour Computer Use.

PubMed

Mekhora, Keerin; Septham, Chatdao; Jalayondeja, Wattana

2015-06-01

To investigate the effects of Thai dancing on median neurodynamic response during 4-hour computer use. Twenty-four healthy participants aged 20-30 years performed 5 minutes of Thai dancing including Prom See Na, Yoong Fon Hang, Sod Soy Mala, Lor Keaw and Cha Nee Rai Mai during a 10-minute break of 4-hour computer use. All participants were assessed for nerve tension by elbow range of motion ofupper limb neurodynamic test 1 (ULNT1) and components of quick test. The discomfort was measured by visual analogue discomfort scale (VADS). These measurements were assessed before and after computer work. The statistical analyses employed paired t-test for continuous outcome and Friedman's test. The median nerve tension (indicated by elbow range of motion) was significantly reduced at before and after work, when 5 minutes of Thai dancing was introduced during the break. While components of the quick test emphasized that Thai dance immediately helped reduce the median nerve tension. The VADS in eight body areas increased over the period of 4 hours, but decreased after performing Thai dancing (p<0.05). Thai dancing helped relieve median nerve tension and body discomfort. It may be recommended as an exercise during break for computer users who continuously work to prevent WMSDs.

Cooper-pair size and binding energy for unconventional superconducting systems

NASA Astrophysics Data System (ADS)

Dinóla Neto, F.; Neto, Minos A.; Salmon, Octavio D. Rodriguez

2018-06-01

The main proposal of this paper is to analyze the size of the Cooper pairs composed by unbalanced mass fermions from different electronic bands along the BCS-BEC crossover and study the binding energy of the pairs. We are considering an interaction between fermions with different masses leading to an inter-band pairing. In addiction to the attractive interaction we have an hybridization term to couple both bands, which in general acts unfavorable for the pairing between the electrons. We get first order phase transitions as the hybridization breaks the Cooper pairs for the s-wave symmetry of the gap amplitude. The results show the dependence of the Cooper-pair size as a function of the hybridization for T = 0 . We also propose the structure of the binding energy of the inter-band system as a function of the two-bands quasi-particle energies.

Studies of Nonconventional Superfluids: Ultrasound Propagation in HELIUM-3-BORON and the Microwave Surface Impedance of the Heavy-Fermion Superconductor Uranium PLATINUM(3)

NASA Astrophysics Data System (ADS)

Zhao, Zuyu

1990-06-01

Two nonconventional superfluids, superfluid ^3He-B and the heavy fermion superconductor UPt_3 have been studied using different techniques: (1) A study of ^3He -B was performed in an acoustic sound cell with a path length of 381mum using the single-ended, c.w., acoustic impedance technique. The fundamental frequency of the x-cut quartz transducer employed in the experiments was 12.80 MHz. The following studies were performed: (a) A systematic measurement was made on the pair-breaking edge in zero magnetic field with ultrasonic frequencies of 64.3 MHz, 90.1 MHz, 141.6 MHz and 167.4 MHz, in the pressure range from 3 bar to 28 bar. The results of our measurements indirectly support the temperature scale of Greywall and the weak coupling plus (WCP) model of Rainer and Serene for the gap function. The pair-breaking edge was also measured in magnetic fields up to 1.36 kG perpendicular to the sound propagation direction and the predicted shift of the effective pair-breaking threshold (from 2 Delta(T) in zero field) by Omega = {gamma Hover 1+{1 over3}F_sp{o}{a}(2+Y) }(the renormalized Larmor frequency) has been observed. (b) The (imaginary) squashing mode was excited with sound frequencies of 141.6 MHz and 115.8 MHz. A doublet splitting (of about 0.3 MHz) of this mode was observed. This doublet splitting was found to be strongly pressure and frequency dependent, but independent of the magnetic field (at the low fields studied). Possible causes of this splitting include superfluid flow induced texture effects and finite wavevector (dispersion) effects. (c) Structure was observed with a sound frequency of 64.3 MHz in the vicinity of 2Delta(T) in a magnetic field of about 580 Gauss which is thought to be J_{z} = -1 component of the J = 1^- collective mode. (2) A surface impedance study of heavy Fermion superconductor UPt_3 was performed with an X-band microwave spectrometer (f ~eq 11.42 GHz) integrated with an Oxford 400 TLE dilution refrigerator so as to have top-loading capability. (3) Using a top loading magnetometer, measurements of the H_{cl} on UPt_3 were performed and kinks were observed along the c axis and in the basal plane. The results support a model of unconventional superconductivity by Hess, Tokuyasu and Sauls.

Breaking mean-motion resonances during Type I planet migration

NASA Astrophysics Data System (ADS)

Hands, T. O.; Alexander, R. D.

2018-03-01

We present 2D hydrodynamical simulations of pairs of planets migrating simultaneously in the Type I regime in a protoplanetary disc. Convergent migration naturally leads to the trapping of these planets in mean-motion resonances. Once in resonance the planets' eccentricity grows rapidly, and disc-planet torques cause the planets to escape resonance on a time-scale of a few hundred orbits. The effect is more pronounced in highly viscous discs, but operates efficiently even in inviscid discs. We attribute this resonance-breaking to overstable librations driven by moderate eccentricity damping, but find that this mechanism operates differently in hydrodynamic simulations than in previous analytic calculations. Planets escaping resonance in this manner can potentially explain the observed paucity of resonances in Kepler multitransiting systems, and we suggest that simultaneous disc-driven migration remains the most plausible means of assembling tightly packed planetary systems.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pogosov, Walter V.; Institute for Theoretical and Applied Electrodynamics, Russian Academy of Sciences, Izhorskaya 13, 125412 Moscow; Combescot, Monique

While the one-Cooper-pair problem is now a textbook exercise, the energy of two pairs of electrons with opposite spins and zero total momentum has not been derived yet, the exact handling of Pauli blocking between bound pairs being not that easy for N=2 already. The two-Cooper-pair problem however is quite enlightening to understand the very peculiar role played by the Pauli exclusion principle in superconductivity. Pauli blocking is known to drive the change from 1 to N pairs but no precise description of this continuous change has been given so far. Using Richardson's procedure, we here prove that Pauli blockingmore » increases the free part of the two-pair ground-state energy but decreases the binding part when compared to two isolated pairs--the excitation gap to break a pair however increasing from one to two pairs. When extrapolated to the dense BCS regime, the decrease in the pair binding while the gap increases strongly indicates that at odd with common belief, the average pair binding energy cannot be on the order of the gap.« less

Validating simple dynamical simulations of the unitary Fermi gas

NASA Astrophysics Data System (ADS)

Forbes, Michael McNeil; Sharma, Rishi

2014-10-01

We present a comparison between simulated dynamics of the unitary fermion gas using the superfluid local density approximation (SLDA) and a simplified bosonic model, the extended Thomas-Fermi (ETF) with a unitary equation of state. Small-amplitude fluctuations have similar dynamics in both theories for frequencies far below the pair-breaking threshold and wave vectors much smaller than the Fermi momentum. The low-frequency linear responses in both match well for surprisingly large wave vectors, even up to the Fermi momentum. For nonlinear dynamics such as vortex generation, the ETF provides a semiquantitative description of SLDA dynamics as long as the fluctuations do not have significant power near the pair-breaking threshold; otherwise the dynamics of the ETF cannot be trusted. Nonlinearities in the ETF tend to generate high-frequency fluctuations, and with no normal component to remove this energy from the superfluid, features such as vortex lattices cannot relax and crystallize as they do in the SLDA.

Spin-orbit coupling, electron transport and pairing instabilities in two-dimensional square structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kocharian, Armen N.; Fernando, Gayanath W.; Fang, Kun

Rashba spin-orbit effects and electron correlations in the two-dimensional cylindrical lattices of square geometries are assessed using mesoscopic two-, three- and four-leg ladder structures. Here the electron transport properties are systematically calculated by including the spin-orbit coupling in tight binding and Hubbard models threaded by a magnetic flux. These results highlight important aspects of possible symmetry breaking mechanisms in square ladder geometries driven by the combined effect of a magnetic gauge field spin-orbit interaction and temperature. The observed persistent current, spin and charge polarizations in the presence of spin-orbit coupling are driven by separation of electron and hole charges andmore » opposite spins in real-space. The modeled spin-flip processes on the pairing mechanism induced by the spin-orbit coupling in assembled nanostructures (as arrays of clusters) engineered in various two-dimensional multi-leg structures provide an ideal playground for understanding spatial charge and spin density inhomogeneities leading to electron pairing and spontaneous phase separation instabilities in unconventional superconductors. Such studies also fall under the scope of current challenging problems in superconductivity and magnetism, topological insulators and spin dependent transport associated with numerous interfaces and heterostructures.« less

Origin of the U(1) field mass in superconductors

NASA Astrophysics Data System (ADS)

Koizumi, Hiroyasu

2017-05-01

Recently, a new theory for superconductivity has been put forward, in which the persistent current generation is attributed to the emergent singularities of the electronic wave function that are created by the spin-twisting itinerant circular motion of electrons. The persistent current generated by this mechanism behaves in every respect like supercurrent in superconductors, yielding the flux quantum h/2e and the Josephson frequency 2eV/h, where h is Planck’s constant, -e is the electron charge, and V is the voltage across the Josephson junction. The mass generation of the U(1) gauge field (or the Meissner effect) in the new theory is due to the emergence of topological objects, ‘instantons’ generated by the single-valued requirement of the wave function in the presence of the emergent singularities. The current standard theory of superconductivity is based on the BCS theory, and explains the emergence of superconductivity as due to the global U(1) gauge symmetry breaking realized by the Cooper pair formation. The U(1) field mass generation is believed to be due to this global U(1) gauge symmetry breaking. However, the feasibility of this mechanism has been questioned since no known interaction can prepare the global U(1) symmetry broken state from the normal state. We argue here that the U(1) mass generation in the BCS superconductor can be attributed to the one by the instanton mentioned above if the Rashba spin-orbit interaction is added. Then, the occurrence of persistent current generation becomes due to the instanton formation, and the role of the Cooper pair formation is to stabilize the instanton by providing an energy gap for perturbative excitations. Upon forming the Cooper pair, the instanton is stabilized and persistent current generation becomes possible. Thus, the superconducting transition temperature coincides with the Cooper pair formation temperature.

Superconductivity from fractionalized excitations in URu2Si2

NASA Astrophysics Data System (ADS)

Hsu, Chen-Hsuan; Chakravarty, Sudip

2014-10-01

An unconventional pairing mechanism in the heavy-fermion material URu2Si2 is studied. We propose a mixed singlet-triplet d-density wave to be the hidden-order state in URu2Si2. The exotic order is topologically nontrivial and supports a charge 2e skyrmionic spin texture, which is assumed to fractionalize into merons and antimerons at the deconfined quantum critical point. The interaction between these fractional particles results in a (pseudo)spin-singlet chiral d-wave superconducting state, which breaks time-reversal symmetry. Therefore, it is highly likely to produce a nonzero signal of the polar Kerr effect at the onset of the superconductivity, consistent with recent experiments. In addition, the nodal structures of the possible pairing functions in our model are consistent with the thermodynamic experiments in URu2Si2.

Effect of disorder on the pressure-induced superconducting state of CeAu 2Si 2

NASA Astrophysics Data System (ADS)

Ren, Z.; Giriat, G.; Scheerer, G. W.; Lapertot, G.; Jaccard, D.

2015-03-01

CeAu2Si2 is a newly discovered pressure-induced heavy fermion superconductor, which shows very unusual interplay between superconductivity and magnetism under pressure. Here we compare the results of high-pressure measurements on single-crystalline CeAu2Si2 samples with different levels of disorder. It is found that while the magnetic properties are essentially sample independent, superconductivity is rapidly suppressed when the residual resistivity of the sample increases. We show that the depression of bulk Tc can be well understood in terms of pair breaking by nonmagnetic disorder, which strongly suggests an unconventional pairing state in pressurized CeAu2Si2 . Furthermore, increasing the level of disorder leads to the emergence of another phase transition at T* within the magnetic phase, which might be in competition with superconductivity.

Nodeless superconductivity and time-reversal symmetry breaking in the noncentrosymmetric superconductor Re24Ti5

NASA Astrophysics Data System (ADS)

Shang, T.; Pang, G. M.; Baines, C.; Jiang, W. B.; Xie, W.; Wang, A.; Medarde, M.; Pomjakushina, E.; Shi, M.; Mesot, J.; Yuan, H. Q.; Shiroka, T.

2018-01-01

The noncentrosymmetric superconductor Re24Ti5 , a time-reversal symmetry- (TRS-) breaking candidate with Tc=6 K , was studied by means of muon-spin rotation/relaxation (μ SR ) and tunnel-diode oscillator techniques. At the macroscopic level, its bulk superconductivity was investigated via electrical resistivity, magnetic susceptibility, and heat-capacity measurements. The low-temperature penetration depth, superfluid density, and electronic heat capacity all evidence an s -wave coupling with an enhanced superconducting gap. The spontaneous magnetic fields revealed by zero-field μ SR below Tc indicate a time-reversal symmetry breaking and thus the unconventional nature of superconductivity in Re24Ti5 . The concomitant occurrence of TRS breaking also in the isostructural Re6(Zr ,Hf ) compounds hints at its common origin in this superconducting family and that an enhanced spin-orbital coupling does not affect pairing symmetry.

Spin Triplet Nematic Pairing Symmetry and Superconducting Double Transition in U1-xThxBe13

NASA Astrophysics Data System (ADS)

Machida, Kazushige

2018-03-01

Motivated by a recent experiment on U1-xThxBe13 with x = 3%, we develop a theory to narrow down the possible pair symmetry to consistently describe the double transition utilizing various theoretical tools, including group theory and Ginzburg-Landau theory. It is explained in terms of the two-dimensional representation Eu with spin triplet. Symmetry breaking causes the degenerate Tc to split into two. The low-temperature phase is identified as the cyclic p wave: d(k) = \\hat{x}kx + ɛ \\hat{y}ky + ɛ 2\\hat{z}kz with ɛ3 = 1, whereas the biaxial nematic phase: d(k) = √{3} (\\hat{x}kx - \\hat{y}ky) is the high-temperature one. This allows us to simultaneously identify the uniaxial nematic phase: d(k) = 2\\hat{z}kz - \\hat{x}kx - \\hat{y}ky for UBe13, which spontaneously breaks the cubic symmetry of the system. Those pair functions are fully consistent with this description and existing data. We comment on the accidental scenario in addition to this degeneracy scenario and the intriguing topological nature hidden in this long-known material.

The concept of quasi-tissue-equivalent nanodosimeter based on the glow peak 5a/5 in LiF:Mg,Ti (TLD-100).

PubMed

Oster, L; Horowitz, Y S; Biderman, S; Haddad, J

2003-12-01

We demonstrate the viability of the concept of using existing molecular nanostructures in thermoluminescent solid-state materials as solid-state nanodosimeters. The concept is based on mimicking radiobiology (specifically the ionization density dependence of double strand breaks in DNA) by using the similar ionization density dependence of simultaneous electron-hole capture in spatially correlated trapping and luminescent centres pairs in the thermoluminescence of LiF:Mg,Ti. This simultaneous electron-hole capture has been shown to lead to ionization density dependence in the relative intensity of peak 5a to peak 5 similar to the ratio of double-strand breaks to single-strand breaks for low energy He ions.

Nematic and chiral superconductivity induced by odd-parity fluctuations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Fengcheng; Martin, Ivar

Recent experiments indicate that superconductivity in Bi 2Se 3 intercalated with Cu, Nb, or Sr is nematic with rotational symmetry breaking. Motivated by this observation, we present a model study of nematic and chiral superconductivity induced by odd-parity fluctuations. Additionally, we show that odd-parity fluctuations in the two-component E u representation of D 3d crystal point group can generate attractive interaction in both the even-parity s-wave and odd-parity E-u pairing channels, but repulsive interaction in other odd-parity pairing channels. Coulomb repulsion can suppress s-wave pairing relative to E u pairing, and thus the latter can have a higher critical temperature.more » E u pairing has two distinct phases: a nematic phase and a chiral phase, both of which can be realized in our model. Finally, when s-wave and E u pairings have similar instability temperature, we find an intermediate phase in which both types of pairing coexist.« less

Nematic and chiral superconductivity induced by odd-parity fluctuations

DOE PAGES

Wu, Fengcheng; Martin, Ivar

2017-10-09

Recent experiments indicate that superconductivity in Bi 2Se 3 intercalated with Cu, Nb, or Sr is nematic with rotational symmetry breaking. Motivated by this observation, we present a model study of nematic and chiral superconductivity induced by odd-parity fluctuations. Additionally, we show that odd-parity fluctuations in the two-component E u representation of D 3d crystal point group can generate attractive interaction in both the even-parity s-wave and odd-parity E-u pairing channels, but repulsive interaction in other odd-parity pairing channels. Coulomb repulsion can suppress s-wave pairing relative to E u pairing, and thus the latter can have a higher critical temperature.more » E u pairing has two distinct phases: a nematic phase and a chiral phase, both of which can be realized in our model. Finally, when s-wave and E u pairings have similar instability temperature, we find an intermediate phase in which both types of pairing coexist.« less

Spin precession in spin-orbit coupled weak links: Coulomb repulsion and Pauli quenching

NASA Astrophysics Data System (ADS)

Shekhter, R. I.; Entin-Wohlman, O.; Jonson, M.; Aharony, A.

2017-12-01

A simple model for the transmission of pairs of electrons through a weak electric link in the form of a nanowire made of a material with strong electron spin-orbit interaction (SOI) is presented, with emphasis on the effects of Coulomb interactions and the Pauli exclusion principle. The constraints due to the Pauli principle are shown to "quench" the coherent SOI-induced precession of the spins when the spatial wave packets of the two electrons overlap significantly. The quenching, which results from the projection of the pair's spin states onto spin-up and spin-down states on the link, breaks up the coherent propagation in the link into a sequence of coherent hops that add incoherently. Applying the model to the transmission of Cooper pairs between two superconductors, we find that in spite of Pauli quenching, the Josephson current oscillates with the strength of the SOI, but may even change its sign (compared to the limit of the Coulomb blockade, when the quenching is absent). Conditions for an experimental detection of these features are discussed.

Threshold and flavor effects in the renormalization group equations of the MSSM. II. Dimensionful couplings

NASA Astrophysics Data System (ADS)

Box, Andrew D.; Tata, Xerxes

2009-02-01

We reexamine the one-loop renormalization group equations (RGEs) for the dimensionful parameters of the minimal supersymmetric standard model (MSSM) with broken supersymmetry, allowing for arbitrary flavor structure of the soft SUSY-breaking parameters. We include threshold effects by evaluating the β-functions in a sequence of (nonsupersymmetric) effective theories with heavy particles decoupled at the scale of their mass. We present the most general form for high-scale, soft SUSY-breaking parameters that obtains if we assume that the supersymmetry-breaking mechanism does not introduce new intergenerational couplings. This form, possibly amended to allow additional sources of flavor-violation, serves as a boundary condition for solving the RGEs for the dimensionful MSSM parameters. We then present illustrative examples of numerical solutions to the RGEs. We find that in a SUSY grand unified theory with the scale of SUSY scalars split from that of gauginos and higgsinos, the gaugino mass unification condition may be violated by O(10%). As another illustration, we show that in mSUGRA, the rate for the flavor-violating ttilde 1→c Ztilde 1 decay obtained using the complete RGE solution is smaller than that obtained using the commonly used “single-step” integration of the RGEs by a factor 10-25, and so may qualitatively change expectations for topologies from top-squark pair production at colliders. Together with the RGEs for dimensionless couplings presented in a companion paper, the RGEs in Appendix 2 of this paper form a complete set of one-loop MSSM RGEs that include threshold and flavor-effects necessary for two-loop accuracy.

Mechanism-based model of a mass rapid transit system: A perspective

NASA Astrophysics Data System (ADS)

Legara, Erika Fille; Khoon, Lee Kee; Guang, Hung Gih; Monterola, Christopher

2015-01-01

In this paper, we discuss our findings on the spatiotemporal dynamics within the mass rapid transit (MRT) system of Singapore. We show that the trip distribution of Origin-Destination (OD) station pairs follows a power-law, implying the existence of critical OD pairs. We then present and discuss the empirically validated agent-based model (ABM) we have developed. The model allows recreation of the observed statistics and the setting up of various scenarios and their effects on the system, such as increasing the commuter population and the propagation of travel delays within the transportation network. The proposed model further enables identification of bottlenecks that can cause the MRT to break down, and consequently provide foresight on how such disruptions can possibly be managed. This can potentially provide a versatile approach for transport planners and government regulators to make quantifiable policies that optimally balance cost and convenience as a function of the number of the commuting public.

A novel quantitative electrochemical method to monitor DNA double-strand breaks caused by a DNA cleavage agent at a DNA sensor.

PubMed

Banasiak, Anna; Cassidy, John; Colleran, John

2018-06-01

To date, DNA cleavage, caused by cleavage agents, has been monitored mainly by gel and capillary electrophoresis. However, these techniques are time-consuming, non-quantitative and require gel stains. In this work, a novel, simple and, importantly, a quantitative method for monitoring the DNA nuclease activity of potential anti-cancer drugs, at a DNA electrochemical sensor, is presented. The DNA sensors were prepared using thiol-modified oligonucleotides that self-assembled to create a DNA monolayer at gold electrode surfaces. The quantification of DNA double-strand breaks is based on calculating the DNA surface coverage, before and after exposure to a DNA cleavage agent. The nuclease properties of a model DNA cleavage agent, copper bis-phenanthroline ([Cu II (phen) 2 ] 2+ ), that can cleave DNA in a Fenton-type reaction, were quantified electrochemically. The DNA surface coverage decreased on average by 21% after subjecting the DNA sensor to a nuclease assay containing [Cu II (phen) 2 ] 2+ , a reductant and an oxidant. This percentage indicates that 6 base pairs were cleaved in the nuclease assay from the immobilised 30 base pair strands. The DNA cleavage can be also induced electrochemically in the absence of a chemical reductant. [Cu II (phen) 2 ] 2+ intercalates between DNA base pairs and, on application of a suitable potential, can be reduced to [Cu I (phen) 2 ] + , with dissolved oxygen acting as the required oxidant. This reduction process is facilitated through DNA strands via long-range electron transfer, resulting in DNA cleavage of 23%. The control measurements for both chemically and electrochemically induced cleavage revealed that DNA strand breaks did not occur under experimental conditions in the absence of [Cu II (phen) 2 ] 2+ . Copyright © 2018 Elsevier B.V. All rights reserved.

Strong Neutron Pairing in core+4 n Nuclei

NASA Astrophysics Data System (ADS)

Revel, A.; Marqués, F. M.; Sorlin, O.; Aumann, T.; Caesar, C.; Holl, M.; Panin, V.; Vandebrouck, M.; Wamers, F.; Alvarez-Pol, H.; Atar, L.; Avdeichikov, V.; Beceiro-Novo, S.; Bemmerer, D.; Benlliure, J.; Bertulani, C. A.; Boillos, J. M.; Boretzky, K.; Borge, M. J. G.; Caamaño, M.; Casarejos, E.; Catford, W. N.; Cederkäll, J.; Chartier, M.; Chulkov, L.; Cortina-Gil, D.; Cravo, E.; Crespo, R.; Datta Pramanik, U.; Díaz Fernández, P.; Dillmann, I.; Elekes, Z.; Enders, J.; Ershova, O.; Estradé, A.; Farinon, F.; Fraile, L. M.; Freer, M.; Galaviz, D.; Geissel, H.; Gernhäuser, R.; Golubev, P.; Göbel, K.; Hagdahl, J.; Heftrich, T.; Heil, M.; Heine, M.; Heinz, A.; Henriques, A.; Ignatov, A.; Johansson, H. T.; Jonson, B.; Kahlbow, J.; Kalantar-Nayestanaki, N.; Kanungo, R.; Kelic-Heil, A.; Knyazev, A.; Kröll, T.; Kurz, N.; Labiche, M.; Langer, C.; Le Bleis, T.; Lemmon, R.; Lindberg, S.; Machado, J.; Marganiec, J.; Movsesyan, A.; Nacher, E.; Najafi, M.; Nilsson, T.; Nociforo, C.; Paschalis, S.; Perea, A.; Petri, M.; Pietri, S.; Plag, R.; Reifarth, R.; Ribeiro, G.; Rigollet, C.; Röder, M.; Rossi, D.; Savran, D.; Scheit, H.; Simon, H.; Syndikus, I.; Taylor, J. T.; Tengblad, O.; Thies, R.; Togano, Y.; Velho, P.; Volkov, V.; Wagner, A.; Weick, H.; Wheldon, C.; Wilson, G.; Winfield, J. S.; Woods, P.; Yakorev, D.; Zhukov, M.; Zilges, A.; Zuber, K.; R³B Collaboration

2018-04-01

The emission of neutron pairs from the neutron-rich N =12 isotones 18C and 20O has been studied by high-energy nucleon knockout from 19N and 21O secondary beams, populating unbound states of the two isotones up to 15 MeV above their two-neutron emission thresholds. The analysis of triple fragment-n -n correlations shows that the decay 19N (-1 p ) 18C* → 16C +n +n is clearly dominated by direct pair emission. The two-neutron correlation strength, the largest ever observed, suggests the predominance of a 14C core surrounded by four valence neutrons arranged in strongly correlated pairs. On the other hand, a significant competition of a sequential branch is found in the decay 21O (-1 n )20O*→18O +n +n , attributed to its formation through the knockout of a deeply bound neutron that breaks the 16O core and reduces the number of pairs.

QCD In Extreme Conditions

NASA Astrophysics Data System (ADS)

Wilczek, Frank

Introduction Symmetry and the Phenomena of QCD Apparent and Actual Symmetries Asymptotic Freedom Confinement Chiral Symmetry Breaking Chiral Anomalies and Instantons High Temperature QCD: Asymptotic Properties Significance of High Temperature QCD Numerical Indications for Quasi-Free Behavior Ideas About Quark-Gluon Plasma Screening Versus Confinement Models of Chiral Symmetry Breaking More Refined Numerical Experiments High-Temperature QCD: Phase Transitions Yoga of Phase Transitions and Order Parameters Application to Glue Theories Application to Chiral Transitions Close Up on Two Flavors A Genuine Critical Point! (?) High-Density QCD: Methods Hopes, Doubts, and Fruition Another Renormalization Group Pairing Theory Taming the Magnetic Singularity High-Density QCD: Color-Flavor Locking and Quark-Hadron Continuity Gauge Symmetry (Non)Breaking Symmetry Accounting Elementary Excitations A Modified Photon Quark-Hadron Continuity Remembrance of Things Past More Quarks Fewer Quarks and Reality

Educational Considerations for Children with Tourette's Syndrome.

ERIC Educational Resources Information Center

Jones, Kevin; Johnson, Genevieve Marie

1993-01-01

This paper describes the prevalence of Tourette's Syndrome and its characteristics. Instructional strategies for students with Tourette's Syndrome are discussed, including a flexible teaching style, a warm and supportive classroom environment, paired and cooperative learning strategies, frequent breaks during instruction, and a safe place to…

The mechanism of the emergence of distinct overstretched DNA states

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, You-Liang; Sun, Zhao-Yan, E-mail: zysun@ciac.ac.cn; Lu, Zhong-Yuan

Although multiple overstretched DNA states were identified in experiments, the mechanism of the emergence of distinct states is still unclear. Molecular dynamics simulation is an ideal tool to clarify the mechanism, but the force loading rates in stretching achieved by conventional all-atom DNA models are much faster, which essentially affect overstretching states. We employed a modified coarse-grained DNA model with an unprecedented low loading rate in simulations to study the overstretching transitions of end-opened double-stranded DNA. We observed two-strand peeling off for DNA with low stability and the S-DNA with high stability under tension. By introducing a melting-forbidden model whichmore » prevents base-pair breaking, we still observed the overstretching transition induced by the formation of S-DNA due to the change of dihedral angle. Hence, we confirmed that the competition between the two strain-softening manners, i.e., base-pair breaking and dihedral angle variation, results in the emergence of distinct overstretched DNA states.« less

Small Rad51 and Dmc1 Complexes Often Co-occupy Both Ends of a Meiotic DNA Double Strand Break

PubMed Central

Brown, M. Scott; Grubb, Jennifer; Zhang, Annie; Rust, Michael J.; Bishop, Douglas K.

2015-01-01

The Eukaryotic RecA-like proteins Rad51 and Dmc1 cooperate during meiosis to promote recombination between homologous chromosomes by repairing programmed DNA double strand breaks (DSBs). Previous studies showed that Rad51 and Dmc1 form partially overlapping co-foci. Here we show these Rad51-Dmc1 co-foci are often arranged in pairs separated by distances of up to 400 nm. Paired co-foci remain prevalent when DSBs are dramatically reduced or when strand exchange or synapsis is blocked. Super-resolution dSTORM microscopy reveals that individual foci observed by conventional light microscopy are often composed of two or more substructures. The data support a model in which the two tracts of ssDNA formed by a single DSB separate from one another by distances of up to 400 nm, with both tracts often bound by one or more short (about 100 nt) Rad51 filaments and also by one or more short Dmc1 filaments. PMID:26719980

Meiotic Nuclear Oscillations Are Necessary to Avoid Excessive Chromosome Associations.

PubMed

Chacón, Mariola R; Delivani, Petrina; Tolić, Iva M

2016-11-01

Pairing of homologous chromosomes is a crucial step in meiosis, which in fission yeast depends on nuclear oscillations. However, how nuclear oscillations help pairing is unknown. Here, we show that homologous loci typically pair when the spindle pole body is at the cell pole and the nucleus is elongated, whereas they unpair when the spindle pole body is in the cell center and the nucleus is round. Inhibition of oscillations demonstrated that movement is required for initial pairing and that prolonged association of loci leads to mis-segregation. The double-strand break marker Rec25 accumulates in elongated nuclei, indicating that prolonged chromosome stretching triggers recombinatory pathways leading to mis-segregation. Mis-segregation is rescued by overexpression of the Holliday junction resolvase Mus81, suggesting that prolonged pairing results in irresolvable recombination intermediates. We conclude that nuclear oscillations exhibit a dual role, promoting initial pairing and restricting the time of chromosome associations to ensure proper segregation. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

From SHG to mid-infrared SPDC generation in strained silicon waveguides

NASA Astrophysics Data System (ADS)

Castellan, Claudio; Trenti, Alessandro; Mancinelli, Mattia; Marchesini, Alessandro; Ghulinyan, Mher; Pucker, Georg; Pavesi, Lorenzo

2017-08-01

The centrosymmetric crystalline structure of Silicon inhibits second order nonlinear optical processes in this material. We report here that, by breaking the silicon symmetry with a stressing silicon nitride over-layer, Second Harmonic Generation (SHG) is obtained in suitably designed waveguides where multi-modal phase-matching is achieved. The modeling of the generated signal provides an effective strain-induced second order nonlinear coefficient of χ(2) = (0.30 +/- 0.02) pm/V. Our work opens also interesting perspectives on the reverse process, the Spontaneous Parametric Down Conversion (SPDC), through which it is possible to generate mid-infrared entangled photon pairs.

From bare to renormalized order parameter in gauge space: Structure and reactions

NASA Astrophysics Data System (ADS)

Potel, G.; Idini, A.; Barranco, F.; Vigezzi, E.; Broglia, R. A.

2017-09-01

It is not physically obvious why one can calculate with similar accuracy, as compared to the experimental data, the absolute cross section associated with two-nucleon transfer processes between members of pairing rotational bands, making use of simple BCS (constant matrix elements) or of many-body [Nambu-Gorkov (NG), nuclear field theory (NFT)] spectroscopic amplitudes. Restoration of spontaneous symmetry breaking and associated emergent generalized rigidity in gauge space provides the answer and points to a new emergence: A physical sum rule resulting from the intertwining of structure and reaction processes, closely connected with the central role induced pairing interaction plays in structure, together with the fact that successive transfer dominates Cooper pair tunneling.

Topological phases in a Kitaev chain with imbalanced pairing

NASA Astrophysics Data System (ADS)

Li, C.; Zhang, X. Z.; Zhang, G.; Song, Z.

2018-03-01

We systematically study a Kitaev chain with imbalanced pair creation and annihilation, which is introduced by non-Hermitian pairing terms. An exact phase diagram shows that the topological phase is still robust under the influence of the conditional imbalance. The gapped phases are characterized by a topological invariant, the extended Zak phase, which is defined by the biorthonormal inner product. Such phases are destroyed at the points where the coalescence of ground states occurs, associated with the time-reversal symmetry breaking. We find that the Majorana edge modes also exist in an open chain in the time-reversal symmetry-unbroken region, demonstrating the bulk-edge correspondence in such a non-Hermitian system.

Simulation of the Formation of DNA Double Strand Breaks and Chromosome Aberrations in Irradiated Cells

NASA Technical Reports Server (NTRS)

Plante, Ianik; Ponomarev, Artem L.; Wu, Honglu; Blattnig, Steve; George, Kerry

2014-01-01

The formation of DNA double-strand breaks (DSBs) and chromosome aberrations is an important consequence of ionizing radiation. To simulate DNA double-strand breaks and the formation of chromosome aberrations, we have recently merged the codes RITRACKS (Relativistic Ion Tracks) and NASARTI (NASA Radiation Track Image). The program RITRACKS is a stochastic code developed to simulate detailed event-by-event radiation track structure: [1] This code is used to calculate the dose in voxels of 20 nm, in a volume containing simulated chromosomes, [2] The number of tracks in the volume is calculated for each simulation by sampling a Poisson distribution, with the distribution parameter obtained from the irradiation dose, ion type and energy. The program NASARTI generates the chromosomes present in a cell nucleus by random walks of 20 nm, corresponding to the size of the dose voxels, [3] The generated chromosomes are located within domains which may intertwine, and [4] Each segment of the random walks corresponds to approx. 2,000 DNA base pairs. NASARTI uses pre-calculated dose at each voxel to calculate the probability of DNA damage at each random walk segment. Using the location of double-strand breaks, possible rejoining between damaged segments is evaluated. This yields various types of chromosomes aberrations, including deletions, inversions, exchanges, etc. By performing the calculations using various types of radiations, it will be possible to obtain relative biological effectiveness (RBE) values for several types of chromosome aberrations.

Systematics of first 2+ state g factors around mass 80

NASA Astrophysics Data System (ADS)

Mertzimekis, T. J.; Stuchbery, A. E.; Benczer-Koller, N.; Taylor, M. J.

2003-11-01

The systematics of the first 2+ state g factors in the mass 80 region are investigated in terms of an IBM-II analysis, a pairing-corrected geometrical model, and a shell-model approach. Subshell closure effects at N=38 and overall trends were examined using IBM-II. A large-space shell-model calculation was successful in describing the behavior for N=48 and N=50 nuclei, where single-particle features are prominent. A schematic truncated-space calculation was applied to the lighter isotopes. The variations of the effective boson g factors are discussed in connection with the role of F -spin breaking, and comparisons are made between the mass 80 and mass 180 regions.

Trifluorothymidine exhibits potent antitumor activity via the induction of DNA double-strand breaks.

PubMed

Suzuki, Norihiko; Nakagawa, Fumio; Nukatsuka, Mamoru; Fukushima, Masakazu

2011-05-01

TAS-102 is an oral anticancer drug composed of trifluorothymidine (TFT) and TPI (an inhibitor of thymidine phosphorylase that strongly inhibits the biodegradation of TFT). Similar to 5-fluorouracil (5FU) and 5-fluoro-2'-deoxyuridine (FdUrd), TFT also inhibits thymidylate synthase (TS), a rate-limiting enzyme of DNA biosynthesis, and is incorporated into DNA. TFT exhibits an anticancer effect on colorectal cancer cells that have acquired 5FU and/or FdUrd resistance as a result of the overexpression of TS. Therefore, we examined the mode of action of TFT-induced DNA damage after its incorporation into DNA. When HeLa cells were treated with TFT, the number of ring-open aldehyde forms at apurinic/apyrimidinic sites increased in a dose-dependent manner, although we previously reported that no detectable excisions of TFT paired to adenine were observed using uracil DNA glycosylases, thymine DNA glycosylase or methyl-CpG binding domain 4 and HeLa whole cell extracts. To investigate the functional mechanism of TFT-induced DNA damage, we measured the phosphorylation of ATR, ATM, BRCA2, chk1 and chk2 in nuclear extracts of HeLa cells after 0, 24, 48 or 72 h of exposure to an IC(50) concentration of TFT, FdUrd or 5FU using Western blot analysis or an enzyme-linked immunosorbent assay (ELISA). Unlike FdUrd and 5FU, TFT resulted in an earlier phosphorylation of ATR and chk1 proteins after only 24 h of exposure, while phosphorylated ATM, BRCA2 and chk2 proteins were detected after more than 48 h of exposure to TFT. These results suggest that TFT causes single-strand breaks followed by double-strand breaks in the DNA of TFT-treated cells. TFT (as TAS-102) showed a more potent antitumor activity than oral 5FU on CO-3 colon cancer xenografts in mice, and such antitumor potency was supported by the increased number of double-strand breaks occurring after single-strand breaks in the DNA of the TFT-treated tumors. These results suggest that TFT causes single-strand breaks after its incorporation into DNA followed by double-strand breaks, resulting in DNA damage. This effect of TFT on DNA may explain its potent anticancer activity in cancer therapy.

Trifluorothymidine exhibits potent antitumor activity via the induction of DNA double-strand breaks

PubMed Central

SUZUKI, NORIHIKO; NAKAGAWA, FUMIO; NUKATSUKA, MAMORU; FUKUSHIMA, MASAKAZU

2011-01-01

TAS-102 is an oral anticancer drug composed of trifluorothymidine (TFT) and TPI (an inhibitor of thymidine phosphorylase that strongly inhibits the biodegradation of TFT). Similar to 5-fluorouracil (5FU) and 5-fluoro-2′-deoxyuridine (FdUrd), TFT also inhibits thymidylate synthase (TS), a rate-limiting enzyme of DNA biosynthesis, and is incorporated into DNA. TFT exhibits an anticancer effect on colorectal cancer cells that have acquired 5FU and/or FdUrd resistance as a result of the overexpression of TS. Therefore, we examined the mode of action of TFT-induced DNA damage after its incorporation into DNA. When HeLa cells were treated with TFT, the number of ring-open aldehyde forms at apurinic/apyrimidinic sites increased in a dose-dependent manner, although we previously reported that no detectable excisions of TFT paired to adenine were observed using uracil DNA glycosylases, thymine DNA glycosylase or methyl-CpG binding domain 4 and HeLa whole cell extracts. To investigate the functional mechanism of TFT-induced DNA damage, we measured the phosphorylation of ATR, ATM, BRCA2, chk1 and chk2 in nuclear extracts of HeLa cells after 0, 24, 48 or 72 h of exposure to an IC50 concentration of TFT, FdUrd or 5FU using Western blot analysis or an enzyme-linked immunosorbent assay (ELISA). Unlike FdUrd and 5FU, TFT resulted in an earlier phosphorylation of ATR and chk1 proteins after only 24 h of exposure, while phosphorylated ATM, BRCA2 and chk2 proteins were detected after more than 48 h of exposure to TFT. These results suggest that TFT causes single-strand breaks followed by double-strand breaks in the DNA of TFT-treated cells. TFT (as TAS-102) showed a more potent antitumor activity than oral 5FU on CO-3 colon cancer xenografts in mice, and such antitumor potency was supported by the increased number of double-strand breaks occurring after single-strand breaks in the DNA of the TFT-treated tumors. These results suggest that TFT causes single-strand breaks after its incorporation into DNA followed by double-strand breaks, resulting in DNA damage. This effect of TFT on DNA may explain its potent anticancer activity in cancer therapy. PMID:22977515

Nonthermal electron-positron pairs and the break in the hard X-ray spectrum of NGC 4151

NASA Technical Reports Server (NTRS)

Coppi, Paolo S.; Zdziarski, Andrzej A.

1992-01-01

The recent observation by the detectors on board Granat of a spectral steepening above about 50 keV imposes a constraint on possible emission models for NGC 4151. This steepening, for example, is not well fitted by an exponential rollover characteristic of a purely thermal model, or by a Compton-downscattered power law. We find that this spectral behavior is consistent with that produced by a photon-starved nonthermal pair plasma with high compactness. This is the first quantitative test of the nonthermal pair plasma model against broad-band X-ray/gamma-ray observations. Above 200 keV or so, the nonthermal pair plasma model predicts an upturn in the spectrum, and a thermal annihilation feature around 511 keV. Such spectral behavior should be looked for with GRO.

Atomic substitution in selected high-temperature superconductors: Elucidating the nature of Raman spectra excitations

NASA Astrophysics Data System (ADS)

Hewitt, Kevin Cecil

2000-10-01

In this thesis, the effects of atomic substitution on the vibrational and electronic excitations found in the Raman spectra of selected high-temperature superconductors (HTS) are studied. In particular, atomic and isotopic substitution methods have been used to determine the character of features observed in the Raman spectra of Bi2Sr2Ca n-1CunO2 n+4+delta (n = 1 - Bi2201, n = 2 - Bi2212) and YBa2Cu3O7-delta (Y123). In Bi2201, Pb substitution for Bi (and Sr) has led to the reduction and eventual removal of the structural modulation, characteristic of all members of the Bi-family of HTS. The high quality single crystals and our sensitive triple spectrometer enabled identification of a pair of low frequency modes. The modes are determined to arise from shear and compressional rigid-layer vibrations. The normal state of underdoped cuprates is characterized by a pseudogap of unknown origin. In crystals of underdoped Bi2212 a spectral peak found at 590 cm-1, previously attributed to the pairing of quasiparticles (above Tc) and hence to the formation of a normal state pseudogap, has been found to soften by 3.8% with oxygen isotope exchange. In addition, the feature is absent in fully oxygenated and yttrium underdoped crystals. In this study, the first of its kind on underdoped and isotope substituted Bi2212, the feature has been assigned to stretching vibrations of oxygen in the a-b plane. Bi2212 crystals with varying hole concentrations (0.07 < p < 0.23) were studied to investigate the effects of doping on the symmetry and magnitude of the superconducting gap. Electronic Raman scattering experiments that sample the diagonal (B 2g) and principal axes (B1 g) of the BZ have led us to conclude that the superconducting gap possesses dx2-y2 symmetry, in the underdoped and overdoped regimes. It is found that the magnitude of the superconducting gap (Delta(k)) is sensitive to changes in p. Studies of the pair-breaking peak found in the B1g spectra allow us to conclude that the magnitude of the maximum gap (Deltamax) decreases monotonically with increasing hole doping, for p > 0.13. The pair-breaking effects in Bi2212 have also been compared to the doping dependence of Delta(k) in the widely studied compound Y123. (Abstract shortened by UMI.)

Superconductivity as a Synchronous Spatial Alternation of Valence Bonds.

DTIC Science & Technology

1987-04-01

approach. 9 This is likely to be the case in three-dimensions as well. As pair breaking excitations ( magnons ) can be formed at essentially no energy...cost (remember the form of the magnon dispersion curve of 1-D Heisenberg model), superconductivity cannot be achieved. In principle, these metals can be

Quantum action for time-dependent Ginzburg-Landau equations

NASA Astrophysics Data System (ADS)

Thompson, R. S.

1994-02-01

A gauge-invariant formula is derived for the quantum action of a dirty superconductor with strong pair breaking. The major complication is the coupling between the order parameter and the electro-chemical potential, which is most simply expressed as an imaginary time integral. The perturbative modes of excitation are identified.

Helical peptides with three pairs of Asp-Arg and Glu-Arg residues in different orientations and spacings.

PubMed Central

Huyghues-Despointes, B. M.; Scholtz, J. M.; Baldwin, R. L.

1993-01-01

The helix-stabilizing effects of repeating pairs of Asp-Arg and Glu-Arg residues have been characterized using a peptide system of the same design used earlier to study Glu-Lys (Marqusee, S. & Baldwin, R.L., 1987, Proc. Natl. Acad. Sci. USA 84, 8898-8902) and Asp-Lys ion pairs (Marqusee, S. & Baldwin, R.L., 1990, In Protein Folding [Gierasch, L.M. & King, J., Eds.], pp. 85-94, AAAS, Washington, D.C.). The consequences of breaking ion pair and charge-helix dipole interactions by titration to pH 2 have been compared with the results of screening these interactions with NaCl at pH 7.0 and pH 2.5. The four peptides in each set contain three pairs of acidic (A) and basic (B) residues spaced either i, i + 4 or i, i + 3 apart. In one peptide of each kind the pairwise order of residues is AB, with the charges oriented favorably to the helix macrodipole, and in the other peptide the order is BA. The results are as follows: (1) Remarkably, both Asp-Arg and Glu-Arg peptides show the same pattern of helix stabilization at pH 7.0 found earlier for Glu-Lys and Asp-Lys peptides: i + 4 AB > i + 4 BA approximately i + 3 AB > i + 3 BA. (2) The ion pairs and charge-helix dipole interactions cannot be cleanly separated, but the results suggest that both interactions make important contributions to helix stability.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8443591

Superconducting proximity in three-dimensional Dirac materials: Odd-frequency, pseudoscalar, pseudovector, and tensor-valued superconducting orders

NASA Astrophysics Data System (ADS)

Faraei, Zahra; Jafari, S. A.

2017-10-01

We find that a conventional s -wave superconductor in proximity to a three-dimensional Dirac material (3DDM), to all orders of perturbation in tunneling, induces a combination of s - and p -wave pairing only. We show that the Lorentz invariance of the superconducting pairing prevents the formation of Cooper pairs with higher orbital angular momenta in the 3DDM. This no-go theorem acquires stronger form when the probability of tunneling from the conventional superconductor to positive and negative energy states of 3DDM are equal. In this case, all the p -wave contribution except for the lowest order, identically vanish and hence we obtain an exact result for the induced p -wave superconductivity in 3DDM. Fierz decomposing the superconducting matrix we find that the temporal component of the vector superconducting order and the spatial components of the pseudovector order have odd-frequency pairing symmetry. We find that the latter is odd with respect to exchange of position and chirality of the electrons in the Cooper pair and is a spin-triplet, which is necessary for NMR detection of such an exotic pseudovector pairing. Moreover, we show that the tensorial order breaks into a polar vector and an axial vector and both of them have conventional pairing symmetry except for being a spin triplet. According to our study, for gapless 3DDM, the tensorial superconducting order will be the only order that is odd with respect to the chemical potential μ . Therefore we predict that a transverse p -n junction binds Majorana fermions. This effect can be used to control the neutral Majorana fermions with electric fields.

Unconventional quantum antiferromagnetism with a fourfold symmetry breaking in a spin-1/2 Ising-Heisenberg pentagonal chain

NASA Astrophysics Data System (ADS)

Karľová, Katarína; Strečka, Jozef; Lyra, Marcelo L.

2018-03-01

The spin-1/2 Ising-Heisenberg pentagonal chain is investigated with use of the star-triangle transformation, which establishes a rigorous mapping equivalence with the effective spin-1/2 Ising zigzag ladder. The investigated model has a rich ground-state phase diagram including two spectacular quantum antiferromagnetic ground states with a fourfold broken symmetry. It is demonstrated that these long-period quantum ground states arise due to a competition between the effective next-nearest-neighbor and nearest-neighbor interactions of the corresponding spin-1/2 Ising zigzag ladder. The concurrence is used to quantify the bipartite entanglement between the nearest-neighbor Heisenberg spin pairs, which are quantum-mechanically entangled in two quantum ground states with or without spontaneously broken symmetry. The pair correlation functions between the nearest-neighbor Heisenberg spins as well as the next-nearest-neighbor and nearest-neighbor Ising spins were investigated with the aim to bring insight into how a relevant short-range order manifests itself at low enough temperatures. It is shown that the specific heat displays temperature dependencies with either one or two separate round maxima.

MO-AB-BRA-04: Radiation Measurements with a DNA Double-Strand-Break Dosimeter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Obeidat, M; Cline, K; Stathakis, S

Purpose: Many types of dosimeters are used to measure radiation, but none of them directly measures the biological effect of this dose. The purpose here is to create a dosimeter that can measure the probability of double-strand breaks (DSB) for DNA, which is directly related to the biological effect of radiation. Methods: The dosimeter has DNA strands, which are labeled on one end with biotin and on the other with fluorescein. The biotin attaches these strands to magnetic beads. We suspended the DNA dosimeter in phosphate-buffered saline (PBS) as it matches the internal environment of the body. We placed smallmore » volumes (50µL) of the DNA dosimeter into tubes and irradiated these samples in a water-equivalent plastic phantom with several doses (three samples per dose). After irradiating the samples, a magnet was placed against the tubes. The fluorescein attached to broken DNA strands was extracted (called the supernatant) and placed into a different tube. The fluorescein on the unbroken strands remained attached to the beads in the tube and was re-suspended with 50µL of PBS. A fluorescence reader was used to measure the fluorescence for both the re-suspended beads and supernatant. To prove that we are measuring DSB, we tested dosimeter response with two different lengths of attached DNA strands (1 and 4 kilo-base pair). Results: The probability of DSB at the dose levels of 5, 10, 25, and 50 Gy were 0.05, 0.08, 0.12, and 0.19, respectively, while the coefficients of variation were 0.14, 0.07, 0.02, and 0.01, respectively. The 4 kilo-base-pair dosimeter produced 5.3 times the response of the 1 kilo-base-pair dosimeter. Conclusion: The DNA dosimeter yields a measurable response to dose that scales with the DNA strand length. The goal now is to refine the dosimeter fabrication to reproducibly create a low coefficient of variation for the lower doses. This work was supported in part by Yarmouk University (Irbid, Jordan) and CPRIT (RP140105)« less

Comprehending isospin breaking effects of X (3872 ) in a Friedrichs-model-like scheme

NASA Astrophysics Data System (ADS)

Zhou, Zhi-Yong; Xiao, Zhiguang

2018-02-01

Recently, we have shown that the X (3872 ) state can be naturally generated as a bound state by incorporating the hadron interactions into the Godfrey-Isgur quark model using a Friedrichs-like model combined with the quark pair creation model, in which the wave function for the X (3872 ) as a combination of the bare c c ¯ state and the continuum states can also be obtained. Under this scheme, we now investigate the isospin-breaking effect of X (3872 ) in its decays to J /ψ π+π- and J /ψ π+π-π0. By coupling its dominant continuum parts to J /ψ ρ and J /ψ ω through the quark rearrangement process, one could obtain the reasonable ratio of B (X (3872 )→J /ψ π+π-π0)/B (X (3872 )→J /ψ π+π-)≃ (0.58 - 0.92 ) . It is also shown that the D ¯D* invariant mass distributions in the B →D ¯D*K decays could be understood qualitatively at the same time. This scheme may provide more insight into the enigmatic nature of the X (3872 ) state.

Strong Neutron Pairing in core+4n Nuclei.

PubMed

Revel, A; Marqués, F M; Sorlin, O; Aumann, T; Caesar, C; Holl, M; Panin, V; Vandebrouck, M; Wamers, F; Alvarez-Pol, H; Atar, L; Avdeichikov, V; Beceiro-Novo, S; Bemmerer, D; Benlliure, J; Bertulani, C A; Boillos, J M; Boretzky, K; Borge, M J G; Caamaño, M; Casarejos, E; Catford, W N; Cederkäll, J; Chartier, M; Chulkov, L; Cortina-Gil, D; Cravo, E; Crespo, R; Datta Pramanik, U; Díaz Fernández, P; Dillmann, I; Elekes, Z; Enders, J; Ershova, O; Estradé, A; Farinon, F; Fraile, L M; Freer, M; Galaviz, D; Geissel, H; Gernhäuser, R; Golubev, P; Göbel, K; Hagdahl, J; Heftrich, T; Heil, M; Heine, M; Heinz, A; Henriques, A; Ignatov, A; Johansson, H T; Jonson, B; Kahlbow, J; Kalantar-Nayestanaki, N; Kanungo, R; Kelic-Heil, A; Knyazev, A; Kröll, T; Kurz, N; Labiche, M; Langer, C; Le Bleis, T; Lemmon, R; Lindberg, S; Machado, J; Marganiec, J; Movsesyan, A; Nacher, E; Najafi, M; Nilsson, T; Nociforo, C; Paschalis, S; Perea, A; Petri, M; Pietri, S; Plag, R; Reifarth, R; Ribeiro, G; Rigollet, C; Röder, M; Rossi, D; Savran, D; Scheit, H; Simon, H; Syndikus, I; Taylor, J T; Tengblad, O; Thies, R; Togano, Y; Velho, P; Volkov, V; Wagner, A; Weick, H; Wheldon, C; Wilson, G; Winfield, J S; Woods, P; Yakorev, D; Zhukov, M; Zilges, A; Zuber, K

2018-04-13

The emission of neutron pairs from the neutron-rich N=12 isotones ^{18}C and ^{20}O has been studied by high-energy nucleon knockout from ^{19}N and ^{21}O secondary beams, populating unbound states of the two isotones up to 15 MeV above their two-neutron emission thresholds. The analysis of triple fragment-n-n correlations shows that the decay ^{19}N(-1p)^{18}C^{*}→^{16}C+n+n is clearly dominated by direct pair emission. The two-neutron correlation strength, the largest ever observed, suggests the predominance of a ^{14}C core surrounded by four valence neutrons arranged in strongly correlated pairs. On the other hand, a significant competition of a sequential branch is found in the decay ^{21}O(-1n)^{20}O^{*}→^{18}O+n+n, attributed to its formation through the knockout of a deeply bound neutron that breaks the ^{16}O core and reduces the number of pairs.

Search for direct top squark pair production in events with a boson, -jets and missing transverse momentum in TeV collisions with the ATLAS detector

NASA Astrophysics Data System (ADS)

Aad, G.; Abbott, B.; Abdallah, J.; Khalek, S. Abdel; Abdinov, O.; Aben, R.; Abi, B.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; Abreu, H.; Abreu, R.; Abulaiti, Y.; Acharya, B. S.; Adamczyk, L.; Adams, D. L.; Adelman, J.; Adomeit, S.; Adye, T.; Agatonovic-Jovin, T.; Aguilar-Saavedra, J. A.; Agustoni, M.; Ahlen, S. P.; Ahmad, A.; Ahmadov, F.; Aielli, G.; Åkesson, T. P. A.; Akimoto, G.; Akimov, A. V.; Alberghi, G. L.; Albert, J.; Albrand, S.; Verzini, M. J. Alconada; Aleksa, M.; Aleksandrov, I. N.; Alexa, C.; Alexander, G.; Alexandre, G.; Alexopoulos, T.; Alhroob, M.; Alimonti, G.; Alio, L.; Alison, J.; Allbrooke, B. M. M.; Allison, L. J.; Allport, P. P.; Allwood-Spiers, S. E.; Almond, J.; Aloisio, A.; Alonso, A.; Alonso, F.; Alpigiani, C.; Altheimer, A.; Alvarez Gonzalez, B.; Alviggi, M. G.; Amako, K.; Amaral Coutinho, Y.; Amelung, C.; Amidei, D.; Amor Dos Santos, S. P.; Amorim, A.; Amoroso, S.; Amram, N.; Amundsen, G.; Anastopoulos, C.; Ancu, L. S.; Andari, N.; Andeen, T.; Anders, C. F.; Anders, G.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Anduaga, X. S.; Angelidakis, S.; Angelozzi, I.; Anger, P.; Angerami, A.; Anghinolfi, F.; Anisenkov, A. V.; Anjos, N.; Annovi, A.; Antonaki, A.; Antonelli, M.; Antonov, A.; Antos, J.; Anulli, F.; Aoki, M.; Aperio Bella, L.; Apolle, R.; Arabidze, G.; Aracena, I.; Arai, Y.; Araque, J. P.; Arce, A. T. H.; Arguin, J.-F.; Argyropoulos, S.; Arik, M.; Armbruster, A. J.; Arnaez, O.; Arnal, V.; Arnold, H.; Arslan, O.; Artamonov, A.; Artoni, G.; Asai, S.; Asbah, N.; Ashkenazi, A.; Ask, S.; Åsman, B.; Asquith, L.; Assamagan, K.; Astalos, R.; Atkinson, M.; Atlay, N. B.; Auerbach, B.; Augsten, K.; Aurousseau, M.; Avolio, G.; Azuelos, G.; Azuma, Y.; Baak, M. A.; Bacci, C.; Bachacou, H.; Bachas, K.; Backes, M.; Backhaus, M.; Backus Mayes, J.; Badescu, E.; Bagiacchi, P.; Bagnaia, P.; Bai, Y.; Bain, T.; Baines, J. T.; Baker, O. K.; Baker, S.; Balek, P.; Balli, F.; Banas, E.; Banerjee, Sw.; Banfi, D.; Bangert, A.; Bannoura, A. A. E.; Bansal, V.; Bansil, H. S.; Barak, L.; Baranov, S. P.; Barberio, E. L.; Barberis, D.; Barbero, M.; Barillari, T.; Barisonzi, M.; Barklow, T.; Barlow, N.; Barnett, B. M.; Barnett, R. M.; Barnovska, Z.; Baroncelli, A.; Barone, G.; Barr, A. J.; Barreiro, F.; Guimarães da Costa, J. Barreiro; Bartoldus, R.; Barton, A. E.; Bartos, P.; Bartsch, V.; Bassalat, A.; Basye, A.; Bates, R. L.; Batkova, L.; Batley, J. R.; Battistin, M.; Bauer, F.; Bawa, H. S.; Beau, T.; Beauchemin, P. H.; Beccherle, R.; Bechtle, P.; Beck, H. P.; Becker, K.; Becker, S.; Beckingham, M.; Becot, C.; Beddall, A. J.; Beddall, A.; Bedikian, S.; Bednyakov, V. A.; Bee, C. P.; Beemster, L. J.; Beermann, T. A.; Begel, M.; Behr, K.; Belanger-Champagne, C.; Bell, P. J.; Bell, W. H.; Bella, G.; Bellagamba, L.; Bellerive, A.; Bellomo, M.; Belloni, A.; Beloborodova, O. L.; Belotskiy, K.; Beltramello, O.; Benary, O.; Benchekroun, D.; Bendtz, K.; Benekos, N.; Benhammou, Y.; Noccioli, E. Benhar; Garcia, J. A. Benitez; Benjamin, D. P.; Bensinger, J. R.; Benslama, K.; Bentvelsen, S.; Berge, D.; Bergeaas Kuutmann, E.; Berger, N.; Berghaus, F.; Berglund, E.; Beringer, J.; Bernard, C.; Bernat, P.; Bernius, C.; Bernlochner, F. U.; Berry, T.; Berta, P.; Bertella, C.; Bertolucci, F.; Besana, M. I.; Besjes, G. J.; Bessidskaia, O.; Besson, N.; Betancourt, C.; Bethke, S.; Bhimji, W.; Bianchi, R. M.; Bianchini, L.; Bianco, M.; Biebel, O.; Bieniek, S. P.; Bierwagen, K.; Biesiada, J.; Biglietti, M.; Bilbao De Mendizabal, J.; Bilokon, H.; Bindi, M.; Binet, S.; Bingul, A.; Bini, C.; Black, C. W.; Black, J. E.; Black, K. M.; Blackburn, D.; Blair, R. E.; Blanchard, J.-B.; Blazek, T.; Bloch, I.; Blocker, C.; Blum, W.; Blumenschein, U.; Bobbink, G. J.; Bobrovnikov, V. S.; Bocchetta, S. S.; Bocci, A.; Boddy, C. R.; Boehler, M.; Boek, J.; Boek, T. T.; Bogaerts, J. A.; Bogdanchikov, A. G.; Bogouch, A.; Bohm, C.; Bohm, J.; Boisvert, V.; Bold, T.; Boldea, V.; Boldyrev, A. S.; Bomben, M.; Bona, M.; Boonekamp, M.; Borisov, A.; Borissov, G.; Borri, M.; Borroni, S.; Bortfeldt, J.; Bortolotto, V.; Bos, K.; Boscherini, D.; Bosman, M.; Boterenbrood, H.; Boudreau, J.; Bouffard, J.; Bouhova-Thacker, E. V.; Boumediene, D.; Bourdarios, C.; Bousson, N.; Boutouil, S.; Boveia, A.; Boyd, J.; Boyko, I. R.; Bozovic-Jelisavcic, I.; Bracinik, J.; Branchini, P.; Brandt, A.; Brandt, G.; Brandt, O.; Bratzler, U.; Brau, B.; Brau, J. E.; Braun, H. M.; Brazzale, S. F.; Brelier, B.; Brendlinger, K.; Brennan, A. J.; Brenner, R.; Bressler, S.; Bristow, K.; Bristow, T. M.; Britton, D.; Brochu, F. M.; Brock, I.; Brock, R.; Bromberg, C.; Bronner, J.; Brooijmans, G.; Brooks, T.; Brooks, W. K.; Brosamer, J.; Brost, E.; Brown, G.; Brown, J.; Bruckman de Renstrom, P. A.; Bruncko, D.; Bruneliere, R.; Brunet, S.; Bruni, A.; Bruni, G.; Bruschi, M.; Bryngemark, L.; Buanes, T.; Buat, Q.; Bucci, F.; Buchholz, P.; Buckingham, R. M.; Buckley, A. G.; Buda, S. I.; Budagov, I. A.; Buehrer, F.; Bugge, L.; Bugge, M. K.; Bulekov, O.; Bundock, A. C.; Burckhart, H.; Burdin, S.; Burghgrave, B.; Burke, S.; Burmeister, I.; Busato, E.; Büscher, D.; Büscher, V.; Bussey, P.; Buszello, C. P.; Butler, B.; Butler, J. M.; Butt, A. I.; Buttar, C. M.; Butterworth, J. M.; Butti, P.; Buttinger, W.; Buzatu, A.; Byszewski, M.; Cabrera Urbán, S.; Caforio, D.; Cakir, O.; Calafiura, P.; Calandri, A.; Calderini, G.; Calfayan, P.; Calkins, R.; Caloba, L. P.; Calvet, D.; Calvet, S.; Toro, R. Camacho; Camarda, S.; Cameron, D.; Caminada, L. M.; Armadans, R. Caminal; Campana, S.; Campanelli, M.; Campoverde, A.; Canale, V.; Canepa, A.; Cantero, J.; Cantrill, R.; Cao, T.; Capeans Garrido, M. D. 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M.; Trincaz-Duvoid, S.; Tripiana, M. F.; Triplett, N.; Trischuk, W.; Trocmé, B.; Troncon, C.; Trottier-McDonald, M.; Trovatelli, M.; True, P.; Trzebinski, M.; Trzupek, A.; Tsarouchas, C.; Tseng, J. C.-L.; Tsiareshka, P. V.; Tsionou, D.; Tsipolitis, G.; Tsirintanis, N.; Tsiskaridze, S.; Tsiskaridze, V.; Tskhadadze, E. G.; Tsukerman, I. I.; Tsulaia, V.; Tsuno, S.; Tsybychev, D.; Tudorache, A.; Tudorache, V.; Tuna, A. N.; Tupputi, S. A.; Turchikhin, S.; Turecek, D.; Cakir, I. Turk; Turra, R.; Tuts, P. M.; Tykhonov, A.; Tylmad, M.; Tyndel, M.; Uchida, K.; Ueda, I.; Ueno, R.; Ughetto, M.; Ugland, M.; Uhlenbrock, M.; Ukegawa, F.; Unal, G.; Undrus, A.; Unel, G.; Ungaro, F. C.; Unno, Y.; Urbaniec, D.; Urquijo, P.; Usai, G.; Usanova, A.; Vacavant, L.; Vacek, V.; Vachon, B.; Valencic, N.; Valentinetti, S.; Valero, A.; Valery, L.; Valkar, S.; Valladolid Gallego, E.; Vallecorsa, S.; Valls Ferrer, J. A.; Van Berg, R.; Van Der Deijl, P. C.; van der Geer, R.; van der Graaf, H.; Van Der Leeuw, R.; van der Ster, D.; van Eldik, N.; van Gemmeren, P.; Van Nieuwkoop, J.; van Vulpen, I.; van Woerden, M. C.; Vanadia, M.; Vandelli, W.; Vanguri, R.; Vaniachine, A.; Vankov, P.; Vannucci, F.; Vardanyan, G.; Vari, R.; Varnes, E. W.; Varol, T.; Varouchas, D.; Vartapetian, A.; Varvell, K. E.; Vassilakopoulos, V. I.; Vazeille, F.; Vazquez Schroeder, T.; Veatch, J.; Veloso, F.; Veneziano, S.; Ventura, A.; Ventura, D.; Venturi, M.; Venturi, N.; Venturini, A.; Vercesi, V.; Verducci, M.; Verkerke, W.; Vermeulen, J. C.; Vest, A.; Vetterli, M. C.; Viazlo, O.; Vichou, I.; Vickey, T.; Boeriu, O. E. Vickey; Viehhauser, G. H. A.; Viel, S.; Vigne, R.; Villa, M.; Villaplana Perez, M.; Vilucchi, E.; Vincter, M. G.; Vinogradov, V. B.; Virzi, J.; Vivarelli, I.; Vives Vaque, F.; Vlachos, S.; Vladoiu, D.; Vlasak, M.; Vogel, A.; Vokac, P.; Volpi, G.; Volpi, M.; von der Schmitt, H.; von Radziewski, H.; von Toerne, E.; Vorobel, V.; Vorobev, K.; Vos, M.; Voss, R.; Vossebeld, J. H.; Vranjes, N.; Vranjes Milosavljevic, M.; Vrba, V.; Vreeswijk, M.; Vu Anh, T.; Vuillermet, R.; Vukotic, I.; Vykydal, Z.; Wagner, W.; Wagner, P.; Wahrmund, S.; Wakabayashi, J.; Walder, J.; Walker, R.; Walkowiak, W.; Wall, R.; Waller, P.; Walsh, B.; Wang, C.; Wang, C.; Wang, F.; Wang, H.; Wang, H.; Wang, J.; Wang, J.; Wang, K.; Wang, R.; Wang, S. M.; Wang, T.; Wang, X.; Wanotayaroj, C.; Warburton, A.; Ward, C. P.; Wardrope, D. R.; Warsinsky, M.; Washbrook, A.; Wasicki, C.; Watanabe, I.; Watkins, P. M.; Watson, A. T.; Watson, I. J.; Watson, M. F.; Watts, G.; Watts, S.; Waugh, B. M.; Webb, S.; Weber, M. S.; Weber, S. W.; Webster, J. S.; Weidberg, A. R.; Weigell, P.; Weinert, B.; Weingarten, J.; Weiser, C.; Weits, H.; Wells, P. S.; Wenaus, T.; Wendland, D.; Weng, Z.; Wengler, T.; Wenig, S.; Wermes, N.; Werner, M.; Werner, P.; Wessels, M.; Wetter, J.; Whalen, K.; White, A.; White, M. J.; White, R.; White, S.; Whiteson, D.; Wicke, D.; Wickens, F. J.; Wiedenmann, W.; Wielers, M.; Wienemann, P.; Wiglesworth, C.; Wiik-Fuchs, L. A. M.; Wijeratne, P. A.; Wildauer, A.; Wildt, M. A.; Wilkens, H. G.; Will, J. Z.; Williams, H. H.; Williams, S.; Willis, C.; Willocq, S.; Wilson, J. A.; Wilson, A.; Wingerter-Seez, I.; Winklmeier, F.; Wittgen, M.; Wittig, T.; Wittkowski, J.; Wollstadt, S. J.; Wolter, M. W.; Wolters, H.; Wosiek, B. K.; Wotschack, J.; Woudstra, M. J.; Wozniak, K. W.; Wright, M.; Wu, M.; Wu, S. L.; Wu, X.; Wu, Y.; Wulf, E.; Wyatt, T. R.; Wynne, B. M.; Xella, S.; Xiao, M.; Xu, D.; Xu, L.; Yabsley, B.; Yacoob, S.; Yamada, M.; Yamaguchi, H.; Yamaguchi, Y.; Yamamoto, A.; Yamamoto, K.; Yamamoto, S.; Yamamura, T.; Yamanaka, T.; Yamauchi, K.; Yamazaki, Y.; Yan, Z.; Yang, H.; Yang, H.; Yang, U. K.; Yang, Y.; Yanush, S.; Yao, L.; Yao, W.-M.; Yasu, Y.; Yatsenko, E.; Yau Wong, K. H.; Ye, J.; Ye, S.; Yen, A. L.; Yildirim, E.; Yilmaz, M.; Yoosoofmiya, R.; Yorita, K.; Yoshida, R.; Yoshihara, K.; Young, C.; Young, C. J. S.; Youssef, S.; Yu, D. R.; Yu, J.; Yu, J. M.; Yu, J.; Yuan, L.; Yurkewicz, A.; Zabinski, B.; Zaidan, R.; Zaitsev, A. M.; Zaman, A.; Zambito, S.; Zanello, L.; Zanzi, D.; Zaytsev, A.; Zeitnitz, C.; Zeman, M.; Zemla, A.; Zengel, K.; Zenin, O.; Ženiš, T.; Zerwas, D.; Zevi della Porta, G.; Zhang, D.; Zhang, F.; Zhang, H.; Zhang, J.; Zhang, L.; Zhang, X.; Zhang, Z.; Zhao, Z.; Zhemchugov, A.; Zhong, J.; Zhou, B.; Zhou, L.; Zhou, N.; Zhu, C. G.; Zhu, H.; Zhu, J.; Zhu, Y.; Zhuang, X.; Zibell, A.; Zieminska, D.; Zimine, N. I.; Zimmermann, C.; Zimmermann, R.; Zimmermann, S.; Zimmermann, S.; Zinonos, Z.; Ziolkowski, M.; Zobernig, G.; Zoccoli, A.; zur Nedden, M.; Zurzolo, G.; Zutshi, V.; Zwalinski, L.

2014-06-01

A search is presented for direct top squark pair production using events with at least two leptons including a same-flavour opposite-sign pair with invariant mass consistent with the boson mass, jets tagged as originating from -quarks and missing transverse momentum. The analysis is performed with proton-proton collision data at collected with the ATLAS detector at the LHC in 2012 corresponding to an integrated luminosity of 20.3 fb. No excess beyond the Standard Model expectation is observed. Interpretations of the results are provided in models based on the direct pair production of the heavier top squark state () followed by the decay to the lighter top squark state () via , and for pair production in natural gauge-mediated supersymmetry breaking scenarios where the neutralino () is the next-to-lightest supersymmetric particle and decays producing a boson and a gravitino () via the process.

Evolution of record-breaking high and low monthly mean temperatures

NASA Astrophysics Data System (ADS)

Anderson, A. L.; Kostinski, A. B.

2011-12-01

We examine the ratio of record-breaking highs to record-breaking lows with respect to extent of time-series for monthly mean temperatures within the continental United States (1900-2006) and ask the following question. How are record-breaking high and low surface temperatures in the United States affected by time period? We find that the ratio of record-breaking highs to lows in 2006 increases as the time-series extend further into the past. For example: in 2006, the ratio of record-breaking highs to record-breaking lows is ≈ 13 : 1 with 1950 as the first year and ≈ 25 : 1 with 1900 as the first year; both ratios are an order of magnitude greater than 3-σ for stationary simulations. We also find record-breaking events are more sensitive to trends in time-series of monthly averages than time-series of corresponding daily values. When we consider the ratio as it evolves with respect to a fixed start year, we find it is strongly correlated with the ensemble mean. Correlation coefficients are 0.76 and 0.82 for 1900-2006 and 1950-2006 respectively; 3-σ = 0.3 for pairs of uncorrelated stationary time-series. We find similar values for globally distributed time-series: 0.87 and 0.92 for 1900-2006 and 1950-2006 respectively. However, the ratios evolve differently: global ratios increase throughout (1920-2006) while continental United States ratios decrease from about 1940 to 1970. (Based on Anderson and Kostinski (2011), Evolution and distribution of record-breaking high and low monthly mean temperatures. Journal of Applied Meteorology and Climatology. doi: 10.1175/JAMC-D-10-05025.1)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yujie; Gong, Sha; Wang, Zhen

The thermodynamic and kinetic parameters of an RNA base pair were obtained through a long-time molecular dynamics simulation of the opening-closing switch process of the base pair near its melting temperature. The thermodynamic parameters were in good agreement with the nearest-neighbor model. The opening rates showed strong temperature dependence, however, the closing rates showed only weak temperature dependence. The transition path time was weakly temperature dependent and was insensitive to the energy barrier. The diffusion constant exhibited super-Arrhenius behavior. The free energy barrier of breaking a single base stack results from the enthalpy increase, ΔH, caused by the disruption ofmore » hydrogen bonding and base-stacking interactions. The free energy barrier of base pair closing comes from the unfavorable entropy loss, ΔS, caused by the restriction of torsional angles. These results suggest that a one-dimensional free energy surface is sufficient to accurately describe the dynamics of base pair opening and closing, and the dynamics are Brownian.« less

Nick-free formation of reciprocal heteroduplexes: a simple solution to the topological problem.

PubMed Central

Wilson, J H

1979-01-01

Because the individual strands of DNA are intertwined, formation of heteroduplex structures between duplexes--as in presumed recombination intermediates--presents a topological puzzle, known as the winding problem. Previous approaches to this problem have assumed that single-strand breaks are required to permit formation of fully coiled heteroduplexes. This paper describes a simple, nick-free solution to the winding problem that satisfies all topological constraints. Homologous duplexes associated by their minor-groove surfaces can switch strand pairing to form reciprocal heteroduplexes that coil together into a compact, four-stranded helix throughout the region of pairing. Model building shows that this fused heteroduplex structure is plausible, being composed entirely of right-handed primary helices with Watson-Crick base pairing throughout. Its simplicity of formation, structural symmetry, and high degree of specificity are suggestive of a natural mechanism for alignment by base pairing between intact homologous duplexes. Implications for genetic recombination are discussed. Images PMID:291028

Isoscalar neutron-proton pairing and SU(4)-symmetry breaking in Gamow-Teller transitions

NASA Astrophysics Data System (ADS)

Kaneko, K.; Sun, Y.; Mizusaki, T.

2018-05-01

The isoscalar neutron-proton pairing is thought to be important for nuclei with equal number of protons and neutrons but its manifestation in structure properties remains to be understood. We investigate the Gamow-Teller (GT) transitions for the f7 /2-shell nuclei in large-scale shell-model calculations with the realistic Hamiltonian. We show that the isoscalar T =0 ,Jπ=1+ neutron-proton pairing interaction plays a decisive role for the concentration of GT strengths at the first-excited 11+ state in 42Sc, and that the suppression of these strengths in 46V, 50Mn, and 54Co is mainly caused by the spin-orbit force supplemented by the quadrupole-quadrupole interaction. Based on the good reproduction of the charge-exchange reaction data, we further analyze the interplay between the isoscalar and isovector pairing correlations. We conclude that even for the most promising A =42 nuclei where the SU(4) isoscalar-isovector-pairing symmetry is less broken, the probability of forming an isoscalar neutron-proton pairing condensation is less than 60% as compared to the expectation at the SU(4)-symmetry limit.

Shape of primary proton spectrum in multi-TeV region from data on vertical muon flux

NASA Astrophysics Data System (ADS)

Yushkov, A. V.; Lagutin, A. A.

2008-12-01

It is shown that the primary proton spectrum, reconstructed from sea-level and underground data on muon spectrum with the use of QGSJET 01, QGSJET II, NEXUS 3.97, and SIBYLL 2.1 interaction models, demonstrates not only model-dependent intensity, but also a model-dependent form. For correct reproduction of muon spectrum shape the primary proton flux should have a nonconstant power index for all considered models, except SIBYLL 2.1, with break at energies around 10 15 TeV and a value of exponent before break close to that obtained in the ATIC-2 experiment. To validate the presence of this break, understanding of inclusive spectra behavior in the fragmentation region in p-air collisions should be improved, but we show that is impossible to do on the basis of the existing experimental data on primary nuclei, atmospheric muon, and hadron fluxes.

The Advanced Energetic Pair Telescope (AdEPT}: A Future Medium-Energy Gamma-Ray Balloon (and Explorer?) Mission

NASA Technical Reports Server (NTRS)

Hunter, Stanley D.

2011-01-01

Gamma-ray astrophysics probes the highest energy, exotic phenomena in astrophysics. In the medium-energy regime, 0.1-200 MeV, many astrophysical objects exhibit unique and transitory behavior such as the transition from electron dominated to hadron dominated processes, spectral breaks, bursts, and flares. Medium-energy gamma-ray imaging however, continues to be a major challenge particularly because of high background, low effective area, and low source intensities. The sensitivity and angular resolution required to address these challenges requires a leap in technology. The Advance Energetic Pair Telescope (AdEPT) being developed at GSFC is designed to image gamma rays above 5 MeV via pair production with angular resolution of 1-10 deg. In addition AdEPT will, for the first time, provide high polarization sensitivity in this energy range. This performance is achieved by reducing the effective area in favor of enhanced angular resolution through the use of a low-density gaseous conversion medium. AdEPT is based on the Three-Dimensional Track Imager (3-DTI) technology that combines a large volume Negative Ion Time Projection Chamber (NITPC) with 2-D Micro-Well Detector (MWD) readout. I will review the major science topics addressable with medium-energy gamma-rays and discuss the current status of the AdEPT technology, a proposed balloon instrument, and the design of a future satellite mission.

Localized Symmetry Breaking for Tuning Thermal Expansion in ScF 3 Nanoscale Frameworks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Lei; Qin, Feiyu; Sanson, Andrea

The local symmetry, beyond the averaged crystallographic structure, tends to bring unu-sual performances. Negative thermal expansion is a peculiar physical property of solids. Here, we report the delicate design of the localized symmetry breaking to achieve the controllable thermal expansion in ScF3 nano-scale frameworks. Intriguingly, an isotropic zero thermal expansion is concurrently engi-neered by localized symmetry breaking, with a remarkably low coefficient of thermal expansion of about +4.0×10-8/K up to 675K. This mechanism is investigated by the joint analysis of atomic pair dis-tribution function of synchrotron X-ray total scattering and extended X-ray absorption fine structure spectra. A localized rhombohedral distortionmore » presumably plays a critical role in stiffening ScF3 nano-scale frameworks and concomitantly suppressing transverse thermal vibrations of fluorine atoms. This physical scenario is also theoretically corroborated by the extinction of phonon modes with negative Grüneisen parameters in the rhombohedral ScF3. The present work opens an untraditional chemical modification to achieve controllable thermal expansion by breaking local symmetries of materials.« less

Colour pairs for constraining the age and metallicity of stellar populations

NASA Astrophysics Data System (ADS)

Li, Zhongmu; Han, Zhanwen

2008-04-01

Using a widely used stellar-population synthesis model, we study the possibility of using pairs of AB system colours to break the well-known stellar age-metallicity degeneracy and to give constraints on two luminosity-weighted stellar-population parameters (age and metallicity). We present the relative age and metallicity sensitivities of the AB system colours that relate to the u,B,g,V,r,R,i, I,z,J,H and K bands, and we quantify the ability of various colour pairs to break the age-metallicity degeneracy. Our results suggest that a few pairs of colours can be used to constrain the above two stellar-population parameters. This will be very useful for exploring the stellar populations of distant galaxies. In detail, colour pairs [(r-K), (u-R)] and [(r-K), (u-r)] are shown to be the best pairs for estimating the luminosity-weighted stellar ages and metallicities of galaxies. They can constrain two stellar-population parameters on average with age uncertainties less than 3.89 Gyr and metallicity uncertainties less than 0.34 dex for typical colour uncertainties. The typical age uncertainties for young populations (age < 4.6 Gyr) and metal-rich populations (Z >= 0.001) are small (about 2.26 Gyr) while those for old populations (age >= 4.6 Gyr) and metal-poor populations (Z < 0.001) are much larger (about 6.88 Gyr). However, the metallicity uncertainties for metal-poor populations (about 0.0024) are much smaller than for other populations (about 0.015). Some other colour pairs can also possibly be used for constraining the two parameters. On the whole, the estimation of stellar-population parameters is likely to be reliable only for early-type galaxies with small colour errors and globular clusters, because such objects contain less dust. In fact, no galaxy is totally dust-free and early-type galaxies are also likely have some dust [e.g. E(B- V) ~ 0.05], which can change the stellar ages by about 2.5 Gyr and metallicities (Z) by about 0.015. When we compare the photometric estimates with previous spectroscopic estimates, we find some differences, especially when comparing the stellar ages determined by two methods. The differences mainly result from the young populations of galaxies. Therefore, it is difficult to obtain the absolute values of stellar ages and metallicities, but the results are useful for obtaining some relative values. In addition, our results suggest that colours relating to both UBVRIJHK and ugriz magnitudes are much better than either UBVRIJHK or ugriz colours for breaking the well-known degeneracy. The results also show that the stellar ages and metallicities of galaxies observed by the Sloan Digital Sky Survey and the Two-Micron All-Sky Survey can be estimated via photometry data. The data are available at the Centre de Données astronomiques de Strabourg (CDS) or on request to the authors. E-mail: zhongmu.li@gmail.com

Effects of enviromental temperature and femoral fracture on wound healing in rats.

PubMed

Crowley, L V; Seifter, E; Kriss, P; Rettura, G; Nakao, K; Levenson, S M

1977-06-01

Femoral fracture, unilateral and bilateral, impaired the healing of dorsal skin incisions and formation of reparative granulation tissue in subcutaneously implanted polyvinyl alcohol sponges judged histologically and by breaking strengths and hydroxyproline contents, respectively, 1 week after injury in pair-fed rats kept at 22 degrees C. When rats were transferred to a room at 30 degrees C immediately after skin incision and sponge implants, with or without unilateral fracture, no differences in healing were observed between the two groups. Rats with skin incision, sponge implants, and either femoral fracture or sham-fracture excreted more urinary nitrogen than preoperatively when kept at 22 degrees. Counterpart groups transferred to a 30 degrees room right after operation excreted less urinary nitrogen than preoperatively, but because of lower food intakes postoperatively, the ratio of urinary nitrogen to food intake nitrogen was increased. With equivalent food intakes, pair-fed rats with fracture kept at 22 degrees postoperatively lost more weight and excreted more nitrogen than corresponding rats transfered to a 30 degrees room.

Mid-Task Break Improves Global Integration of Functional Connectivity in Lower Alpha Band

PubMed Central

Li, Junhua; Lim, Julian; Chen, Yu; Wong, Kianfoong; Thakor, Nitish; Bezerianos, Anastasios; Sun, Yu

2016-01-01

Numerous efforts have been devoted to revealing neurophysiological mechanisms of mental fatigue, aiming to find an effective way to reduce the undesirable fatigue-related outcomes. Until recently, mental fatigue is thought to be related to functional dysconnectivity among brain regions. However, the topological representation of brain functional connectivity altered by mental fatigue is only beginning to be revealed. In the current study, we applied a graph theoretical approach to analyse such topological alterations in the lower alpha band (8~10 Hz) of EEG data from 20 subjects undergoing a two-session experiment, in which one session includes four successive blocks with visual oddball tasks (session 1) whereas a mid-task break was introduced in the middle of four task blocks in the other session (session 2). Phase lag index (PLI) was then employed to measure functional connectivity strengths for all pairs of EEG channels. Behavior and connectivity maps were compared between the first and last task blocks in both sessions. Inverse efficiency scores (IES = reaction time/response accuracy) were significantly increased in the last task block, showing a clear effect of time-on-task in participants. Furthermore, a significant block-by-session interaction was revealed in the IES, suggesting the effectiveness of the mid-task break on maintaining task performance. More importantly, a significant session-independent deficit of global integration and an increase of local segregation were found in the last task block across both sessions, providing further support for the presence of a reshaped topology in functional brain connectivity networks under fatigue state. Moreover, a significant block-by-session interaction was revealed in the characteristic path length, small-worldness, and global efficiency, attributing to the significantly disrupted network topology in session 1 in comparison of the maintained network structure in session 2. Specifically, we found increased nodal betweenness centrality in several channels resided in frontal regions in session 1, resembling the observations of more segregated global architecture under fatigue state. Taken together, our findings provide insights into the substrates of brain functional dysconnectivity patterns for mental fatigue and reiterate the effectiveness of the mid-task break on maintaining brain network efficiency. PMID:27378894

Time evolution of the spectral break in the high-energy extra component of GRB 090926A

NASA Astrophysics Data System (ADS)

Yassine, M.; Piron, F.; Mochkovitch, R.; Daigne, F.

2017-10-01

Aims: The prompt light curve of the long GRB 090926A reveals a short pulse 10 s after the beginning of the burst emission, which has been observed by the Fermi observatory from the keV to the GeV energy domain. During this bright spike, the high-energy emission from GRB 090926A underwent a sudden hardening above 10 MeV in the form of an additional power-law component exhibiting a spectral attenuation at a few hundreds of MeV. This high-energy break has been previously interpreted in terms of gamma-ray opacity to pair creation and has been used to estimate the bulk Lorentz factor of the outflow. In this article, we report on a new time-resolved analysis of the GRB 090926A broadband spectrum during its prompt phase and on its interpretation in the framework of prompt emission models. Methods: We characterized the emission from GRB 090926A at the highest energies with Pass 8 data from the Fermi Large Area Telescope (LAT), which offer a greater sensitivity than any data set used in previous studies of this burst, particularly in the 30-100 MeV energy band. Then, we combined the LAT data with the Fermi Gamma-ray Burst Monitor (GBM) in joint spectral fits to characterize the time evolution of the broadband spectrum from keV to GeV energies. We paid careful attention to the systematic effects that arise from the uncertainties on the LAT response. Finally, we performed a temporal analysis of the light curves and we computed the variability timescales from keV to GeV energies during and after the bright spike. Results: Our analysis confirms and better constrains the spectral break, which has been previously reported during the bright spike. Furthermore, it reveals that the spectral attenuation persists at later times with an increase of the break characteristic energy up to the GeV domain until the end of the prompt phase. We discuss these results in terms of keV-MeV synchroton radiation of electrons accelerated during the dissipation of the jet energy and inverse Compton emission at higher energies. We interpret the high-energy spectral break as caused by photon opacity to pair creation. Requiring that all emissions are produced above the photosphere of GRB 090926A, we compute the bulk Lorentz factor of the outflow, Γ. The latter decreases from 230 during the spike to 100 at the end of the prompt emission. Assuming, instead, that the spectral break reflects the natural curvature of the inverse Compton spectrum, lower limits corresponding to larger values of Γ are also derived. Combined with the extreme temporal variability of GRB 090926A, these Lorentz factors lead to emission radii R 1014 cm, which are consistent with an internal origin of both the keV-MeV and GeV prompt emissions.

Conductance signatures of odd-frequency superconductivity in quantum spin Hall systems using a quantum point contact

NASA Astrophysics Data System (ADS)

Fleckenstein, C.; Ziani, N. Traverso; Trauzettel, B.

2018-04-01

Topological superconductors give rise to unconventional superconductivity, which is mainly characterized by the symmetry of the superconducting pairing amplitude. However, since the symmetry of the superconducting pairing amplitude is not directly observable, its experimental identification is rather difficult. In our work, we propose a system, composed of a quantum point contact and proximity-induced s -wave superconductivity at the helical edge of a two-dimensional topological insulator, for which we demonstrate the presence of odd-frequency pairing and its intimate connection to unambiguous transport signatures. Notably, our proposal requires no time-reversal symmetry breaking terms. We discover the domination of crossed Andreev reflection over electron cotunneling in a wide range of parameter space, which is a quite unusual transport regime.

Weakly and strongly coupled Belousov-Zhabotinsky patterns.

PubMed

Weiss, Stephan; Deegan, Robert D

2017-02-01

We investigate experimentally and numerically the synchronization of two-dimensional spiral wave patterns in the Belousov-Zhabotinsky reaction due to point-to-point coupling of two separate domains. Different synchronization modalities appear depending on the coupling strength and the initial patterns in each domain. The behavior as a function of the coupling strength falls into two qualitatively different regimes. The weakly coupled regime is characterized by inter-domain interactions that distorted but do not break wave fronts. Under weak coupling, spiral cores are pushed around by wave fronts in the other domain, resulting in an effective interaction between cores in opposite domains. In the case where each domain initially contains a single spiral, the cores form a bound pair and orbit each other at quantized distances. When the starting patterns consist of multiple randomly positioned spiral cores, the number of cores decreases with time until all that remains are a few cores that are synchronized with a partner in the other domain. The strongly coupled regime is characterized by interdomain interactions that break wave fronts. As a result, the wave patterns in both domains become identical.

Weakly and strongly coupled Belousov-Zhabotinsky patterns

NASA Astrophysics Data System (ADS)

Weiss, Stephan; Deegan, Robert D.

2017-02-01

We investigate experimentally and numerically the synchronization of two-dimensional spiral wave patterns in the Belousov-Zhabotinsky reaction due to point-to-point coupling of two separate domains. Different synchronization modalities appear depending on the coupling strength and the initial patterns in each domain. The behavior as a function of the coupling strength falls into two qualitatively different regimes. The weakly coupled regime is characterized by inter-domain interactions that distorted but do not break wave fronts. Under weak coupling, spiral cores are pushed around by wave fronts in the other domain, resulting in an effective interaction between cores in opposite domains. In the case where each domain initially contains a single spiral, the cores form a bound pair and orbit each other at quantized distances. When the starting patterns consist of multiple randomly positioned spiral cores, the number of cores decreases with time until all that remains are a few cores that are synchronized with a partner in the other domain. The strongly coupled regime is characterized by interdomain interactions that break wave fronts. As a result, the wave patterns in both domains become identical.

Meiotic recombination hotspots - a comparative view.

PubMed

Choi, Kyuha; Henderson, Ian R

2015-07-01

During meiosis homologous chromosomes pair and undergo reciprocal genetic exchange, termed crossover. Meiotic recombination has a profound effect on patterns of genetic variation and is an important tool during crop breeding. Crossovers initiate from programmed DNA double-stranded breaks that are processed to form single-stranded DNA, which can invade a homologous chromosome. Strand invasion events mature into double Holliday junctions that can be resolved as crossovers. Extensive variation in the frequency of meiotic recombination occurs along chromosomes and is typically focused in narrow hotspots, observed both at the level of DNA breaks and final crossovers. We review methodologies to profile hotspots at different steps of the meiotic recombination pathway that have been used in different eukaryote species. We then discuss what these studies have revealed concerning specification of hotspot locations and activity and the contributions of both genetic and epigenetic factors. Understanding hotspots is important for interpreting patterns of genetic variation in populations and how eukaryotic genomes evolve. In addition, manipulation of hotspots will allow us to accelerate crop breeding, where meiotic recombination distributions can be limiting. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

Heavy fermion behavior explained by bosons

NASA Technical Reports Server (NTRS)

Kallio, A.; Poykko, S.; Apaja, V.

1995-01-01

Conventional heavy fermion (HF) theories require existence of massive fermions. We show that heavy fermion phenomena can also be simply explained by existence of bosons with moderate mass but temperature dependent concentration below the formation temperature T(sub B), which in turn is close to room temperature. The bosons B(++) are proposed to be in chemical equilibrium with a system of holes h(+): B(++) = h(+) + h(+). This equilibrium is governed by a boson breaking function f(T), which determines the decreasing boson density and the increasing fermion density with increasing temperature. Since HF-compounds are hybridized from minimum two elements, we assume in addition existence of another fermion component h(sub s)(+) with temperature independent density. This spectator component is thought to be the main agent in binding the bosons in analogy with electronic or muonic molecules. Using a linear boson breaking function we can explain temperature dependence of the giant linear specific heat coefficient gamma(T) coming essentially from bosons. The maxima in resistivity, Hall coefficient, and susceptibility are explained by boson localization effects due to the Wigner crystallization. The antiferromagnetic transitions in turn are explained by similar localization of the pairing fermion system when their density n(sub h)(T(sub FL)) becomes lower than n(sub WC), the critical density of Wigner crystallization. The model applies irrespective whether a compound is superconducting or not. The same model explains the occurrence of low temperature antiferromagnetism also in high-T(sub c) superconductors. The double transition in UPt3 is proposed to be due to the transition of the pairing fermion liquid from spin polarized to unpolarized state.

On the Correspondence between Preference Assessment Outcomes and Progressive-Ratio Schedule Assessments of Stimulus Value

ERIC Educational Resources Information Center

DeLeon, Iser G.; Frank, Michelle A.; Gregory, Meagan K.; Allman, Melissa J.

2009-01-01

The current study examined whether stimuli of different preference levels would be associated with different amounts of work maintained by the stimuli, as determined through progressive-ratio schedule break points. Using a paired-choice preference assessment, stimuli were classified as high, moderate, or low preference for 4 individuals with…

Using Interviews and Peer Pairs to Better Understand How School Environments Affect Young Children's Playground Physical Activity Levels: A Qualitative Study

ERIC Educational Resources Information Center

Parrish, Anne-Maree; Yeatman, Heather; Iverson, Don; Russell, Ken

2012-01-01

School break times provide a daily opportunity for children to be active; however, research indicates this time is underutilized. Reasons for low children's playground activity levels have primarily focused on physical barriers. This research aimed to contribute to physical environmental findings affecting children's playground physical activity…

Computer Modelling of Cyclic Deformation of High-Temperature Materials

DTIC Science & Technology

1993-06-14

possible plying the kink pair separation by the kink height a. to extract the thermodynamic parameters which This latter procedure is not accurate for...angle a(a) (a is the radius of the circle of intersection between particle and slip plane) by F = Vb2 sin a(a) where each breaking angle (a) relates to an

Gravitoelectromagnetism and Dark Energy in Superconductors

NASA Astrophysics Data System (ADS)

de Matos, Clovis Jacinto

A gravitomagnetic analog of the London moment in superconductors could explain the anomalous Cooper pair mass excess reported by Janet Tate. Ultimately the gravitomagnetic London moment is attributed to the breaking of the principle of general covariance in superconductors. This naturally implies nonconservation of classical energy-momentum. A possible relation with the manifestation of dark energy in superconductors is questioned.

Majorana Kramers pair in a nematic vortex

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Fengcheng; Martin, Ivar

A time-reversal (TR) invariant topological superconductor is characterized by a Kramers pair of Majorana zero-energy modes on boundaries and in a core of a TR invariant vortex. A vortex defect that preserves TR symmetry has remained primarily of theoretical interest, since typically a magnetic field, which explicitly breaks TR, needs to be applied to create vortices in superconductors. In this paper, we show that an odd-parity topological superconductor with a nematic pairing order parameter can host a nematic vortex that preserves TR symmetry and binds a Majorana Kramers pair. Such a nematic superconductor could be realized in metal-doped Bi 2Semore » 3, as suggested by recent experiments. We provide an analytic solution for the zero modes in a continuous nematic vortex. In lattice, crystalline anisotropy can pin the two-component order parameter along high-symmetry directions. We show that a discrete nematic vortex, which forms when three nematic domains meet, also supports a TR pair of Majorana modes. Lastly, we discuss possible experiments to probe the zero modes.« less

Majorana Kramers pair in a nematic vortex

DOE PAGES

Wu, Fengcheng; Martin, Ivar

2017-06-05

A time-reversal (TR) invariant topological superconductor is characterized by a Kramers pair of Majorana zero-energy modes on boundaries and in a core of a TR invariant vortex. A vortex defect that preserves TR symmetry has remained primarily of theoretical interest, since typically a magnetic field, which explicitly breaks TR, needs to be applied to create vortices in superconductors. In this paper, we show that an odd-parity topological superconductor with a nematic pairing order parameter can host a nematic vortex that preserves TR symmetry and binds a Majorana Kramers pair. Such a nematic superconductor could be realized in metal-doped Bi 2Semore » 3, as suggested by recent experiments. We provide an analytic solution for the zero modes in a continuous nematic vortex. In lattice, crystalline anisotropy can pin the two-component order parameter along high-symmetry directions. We show that a discrete nematic vortex, which forms when three nematic domains meet, also supports a TR pair of Majorana modes. Lastly, we discuss possible experiments to probe the zero modes.« less

Tevatron Run II Combination of the Effective Leptonic Electroweak Mixing Angle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aaltonen, Timo Antero; et al.

Drell-Yan lepton pairs produced in the processmore » $$p \\bar{p} \\rightarrow \\ell^+\\ell^- + X$$ through an intermediate $$\\gamma^*/Z$$ boson have an asymmetry in their angular distribution related to the spontaneous symmetry breaking of the electroweak force and the associated mixing of its neutral gauge bosons. The CDF and D0 experiments have measured the effective-leptonic electroweak mixing parameter $$\\sin^2\\theta^{\\rm lept}_{\\rm eff}$$ using electron and muon pairs selected from the full Tevatron proton-antiproton data sets collected in 2001-2011, corresponding to 9-10 fb$$^{-1}$$ of integrated luminosity. The combination of these measurements yields the most precise result from hadron colliders, $$\\sin^2 \\theta^{\\rm lept}_{\\rm eff} = 0.23148 \\pm 0.00033$$. This result is consistent with, and approaches in precision, the best measurements from electron-positron colliders. The standard model inference of the on-shell electroweak mixing parameter $$\\sin^2\\theta_W$$, or equivalently the $W$-boson mass $$M_W$$, using the \\textsc{zfitter} software package yields $$\\sin^2 \\theta_W = 0.22324 \\pm 0.00033$$ or equivalently, $$M_W = 80.367 \\pm 0.017 \\;{\\rm GeV}/c^2$$.« less

Emperor penguin mates: keeping together in the crowd

PubMed Central

Ancel, André; Beaulieu, Michaël; Le Maho, Yvon; Gilbert, Caroline

2009-01-01

As emperor penguins have no breeding territories, a key issue for both members of a pair is not to be separated until the egg is laid and transferred to the male. Both birds remain silent after mating and thereby reduce the risk of having the pair bond broken by unpaired birds. However, silence prevents finding each other if the pair is separated. Huddles—the key to saving energy in the cold and the long breeding fast—continuously form and break up, but not all birds are involved simultaneously. We studied the behaviour of four pairs before laying. Temperature and light intensity measurements allowed us to precisely detect the occurrence of huddling episodes and to determine the surrounding temperature. The four pairs huddled simultaneously for only 6 per cent of the time when weather conditions were harshest. Despite this asynchrony, the huddling behaviour and the resulting benefits were similar between pairs. By contrast, the huddling behaviour of mates was synchronized for 84 per cent of events. By coordinating their huddling behaviour during courtship despite the apparent confusion within a huddle and its ever-changing structure, both individuals save energy while securing their partnership. PMID:19324739

Interaction and particle{endash}hole symmetry of Laughlin quasiparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wojs, Arkadiusz

2001-06-15

The pseudopotentials describing interaction of Laughlin quasielectrons (QE) and quasiholes (QH) in an infinite fractional quantum Hall system are studied. The QE and QH pseudopotentials are similar, which suggests the (approximate) particle{endash}hole symmetry recovered in the thermodynamical limit. The problem of the hypothetical symmetry-breaking QE hard-core repulsion is resolved by the estimate that the {open_quotes}forbidden{close_quotes} QE pair state has too high an energy and is unstable. Strong oscillations of the QE and QH pseudopotentials persist in an infinite system, and the analogous QE and QH pair states with small relative angular momentum and nearly vanishing interaction energy are predicted.

Constructing superconductors by graphene Chern-Simons wormholes

NASA Astrophysics Data System (ADS)

Capozziello, Salvatore; Pincak, Richard; Saridakis, Emmanuel N.

2018-03-01

We propose a new model which simulates the motion of free electrons in graphene by the evolution of strings on manifolds. In this model, molecules which constitute sheets of graphene are polygonal point-like structures which build (N + 1) -dimensional manifolds. By breaking the gravitational-analogue symmetry of graphene sheets, we show that two separated child sheets and a Chern-Simons bridge are produced giving rise to a wormhole. In this structure, free electrons are transmitted from one child sheet to the other producing superconductivity. An analogue between "effective gravitons" and "Cooper pairs" is found. In principle, this phenomenology provides the possibility to construct superconductor structures by using the analogue of cosmological models.

Production of extra quarks decaying to dark matter beyond the narrow width approximation at the LHC

NASA Astrophysics Data System (ADS)

Moretti, Stefano; O'Brien, Dermot; Panizzi, Luca; Prager, Hugo

2017-08-01

This paper explores the effects of finite width in processes of pair production of an extra heavy quark with charge 2 /3 (top partner) and its subsequent decay into a bosonic dark matter (DM) candidate—either scalar or vector—and SM up-type quarks at the Large Hadron Collider (LHC). This dynamics has been ignored so far in standard experimental searches of heavy quarks decaying to DM and we assess herein the regions of validity of current approaches, based on the assumption that the extra quarks have a narrow width. Further, we discuss the configurations of masses, widths and couplings where the latter breaks down.

Neutrino Mass Generation at TeV Scale and New Physics Signatures from Charged Higgs at the LHC for Photon Initiated Processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghosh, Kirtiman; Homi Bhabha National Institute, Mumbai; Jana, Sudip

We consider the collider phenomenology of a simple extension of the Standard Model (SM), which consists of an EW isospinmore » $3/2$ scalar, $$\\Delta$$ and a pair of EW isospin $1$ vector like fermions, $$\\Sigma$$ and $$\\bar{\\Sigma}$$, responsible for generating tiny neutrino mass via the effective dimension seven operator. This scalar quadruplet with hypercharge Y = 3 has a plethora of implications at the collider experiments. Its signatures at TeV scale colliders are expected to be seen, if the quadruplet masses are not too far above the electroweak symmetry breaking scale. In this article, we study the phenomenology of multi-charged quadruplet scalars. In particular, we study the multi-lepton signatures at the Large Hadron Collider (LHC) experiment, arising from the production and decays of triply and doubly charged scalars. We studied Drell-Yan (DY) pair production as well as pair production of the charged scalars via photon-photon fusion. For doubly and triply charged scalars, photon fusion contributes significantly for large scalar masses. We also studied LHC constraints on the masses of doubly charged scalars in this model. We derive a lower mass limit of 725 GeV on doubly charged quadruplet scalar.« less

Neutrino Mass Generation at TeV Scale and New Physics Signatures from Charged Higgs at the LHC for Photon Initiated Processes

DOE PAGES

Ghosh, Kirtiman; Homi Bhabha National Institute, Mumbai; Jana, Sudip; ...

2018-03-29

We consider the collider phenomenology of a simple extension of the Standard Model (SM), which consists of an EW isospinmore » $3/2$ scalar, $$\\Delta$$ and a pair of EW isospin $1$ vector like fermions, $$\\Sigma$$ and $$\\bar{\\Sigma}$$, responsible for generating tiny neutrino mass via the effective dimension seven operator. This scalar quadruplet with hypercharge Y = 3 has a plethora of implications at the collider experiments. Its signatures at TeV scale colliders are expected to be seen, if the quadruplet masses are not too far above the electroweak symmetry breaking scale. In this article, we study the phenomenology of multi-charged quadruplet scalars. In particular, we study the multi-lepton signatures at the Large Hadron Collider (LHC) experiment, arising from the production and decays of triply and doubly charged scalars. We studied Drell-Yan (DY) pair production as well as pair production of the charged scalars via photon-photon fusion. For doubly and triply charged scalars, photon fusion contributes significantly for large scalar masses. We also studied LHC constraints on the masses of doubly charged scalars in this model. We derive a lower mass limit of 725 GeV on doubly charged quadruplet scalar.« less

The effect of 111In radionuclide distance and auger electron energy on direct induction of DNA double-strand breaks: a Monte Carlo study using Geant4 toolkit.

PubMed

Piroozfar, Behnaz; Raisali, Gholamreza; Alirezapour, Behrouz; Mirzaii, Mohammad

2018-04-01

In this study, the effect of 111 In position and Auger electron energy on direct induction of DSBs was investigated. The Geant4-DNA simulation toolkit was applied using a simple B-DNA form extracted from PDBlib library. First, the simulation was performed for electrons with energies of 111 In and equal emission probabilities to find the most effective electron energies. Then, 111 In Auger electrons' actual spectrum was considered and their contribution in DSB induction analysed. The results showed that the most effective electron energy is 183 eV, but due to the higher emission probability of 350 eV electrons, most of the DSBs were induced by the latter electrons. Also, it was observed that most of the DSBs are induced by electrons emitted within 4 nm of the central axis of the DNA and were mainly due to breaks with <4 base pairs distance in opposing strands. Whilst, when 111 In atoms are very close to the DNA, 1.3 DSBs have been obtained per decay of 111 In atoms. The results show that the most effective Auger electrons are the 350 eV electrons from 111 In atoms with <4 nm distance from the central axis of the DNA which induce ∼1.3 DSBs per decay when bound to the DNA. This value seems reasonable when compared with the reported experimental data.

Semiclassical transport in nearly symmetric quantum dots. I. Symmetry breaking in the dot.

PubMed

Whitney, Robert S; Schomerus, Henning; Kopp, Marten

2009-11-01

We apply the semiclassical theory of transport to quantum dots with exact and approximate spatial symmetries; left-right mirror symmetry, up-down mirror symmetry, inversion symmetry, or fourfold symmetry. In this work-the first of a pair of articles-we consider (a) perfectly symmetric dots and (b) nearly symmetric dots in which the symmetry is broken by the dot's internal dynamics. The second article addresses symmetry-breaking by displacement of the leads. Using semiclassics, we identify the origin of the symmetry-induced interference effects that contribute to weak localization corrections and universal conductance fluctuations. For perfect spatial symmetry, we recover results previously found using the random-matrix theory conjecture. We then go on to show how the results are affected by asymmetries in the dot, magnetic fields, and decoherence. In particular, the symmetry-asymmetry crossover is found to be described by a universal dependence on an asymmetry parameter gamma_{asym} . However, the form of this parameter is very different depending on how the dot is deformed away from spatial symmetry. Symmetry-induced interference effects are completely destroyed when the dot's boundary is globally deformed by less than an electron wavelength. In contrast, these effects are only reduced by a finite amount when a part of the dot's boundary smaller than a lead-width is deformed an arbitrarily large distance.

Using English and French Proverbs as Comparative Pairs to Teach the Terminal Junctures

ERIC Educational Resources Information Center

Yurtbasi, Metin

2013-01-01

Junctures are pauses used in speech separating thought-groups from one another in order to give the listener time to digest the utterance to signal the end. Where junctures are present, hearers find it easier to understand what is said as they are able to discern the individual words between such verbal breaks. Junctures being universal…

AID and Reactive Oxygen Species Can Induce DNA Breaks within Human Chromosomal Translocation Fragile Zones.

PubMed

Pannunzio, Nicholas R; Lieber, Michael R

2017-12-07

DNA double-strand breaks (DSBs) occurring within fragile zones of less than 200 base pairs account for the formation of the most common human chromosomal translocations in lymphoid malignancies, yet the mechanism of how breaks occur remains unknown. Here, we have transferred human fragile zones into S. cerevisiae in the context of a genetic assay to understand the mechanism leading to DSBs at these sites. Our findings indicate that a combination of factors is required to sensitize these regions. Foremost, DNA strand separation by transcription or increased torsional stress can expose these DNA regions to damage from either the expression of human AID or increased oxidative stress. This damage causes DNA lesions that, if not repaired quickly, are prone to nuclease cleavage, resulting in DSBs. Our results provide mechanistic insight into why human neoplastic translocation fragile DNA sequences are more prone to enzymes or agents that cause longer-lived DNA lesions. Copyright © 2017 Elsevier Inc. All rights reserved.

Constitutional chromothripsis rearrangements involve clustered double-stranded DNA breaks and nonhomologous repair mechanisms.

PubMed

Kloosterman, Wigard P; Tavakoli-Yaraki, Masoumeh; van Roosmalen, Markus J; van Binsbergen, Ellen; Renkens, Ivo; Duran, Karen; Ballarati, Lucia; Vergult, Sarah; Giardino, Daniela; Hansson, Kerstin; Ruivenkamp, Claudia A L; Jager, Myrthe; van Haeringen, Arie; Ippel, Elly F; Haaf, Thomas; Passarge, Eberhard; Hochstenbach, Ron; Menten, Björn; Larizza, Lidia; Guryev, Victor; Poot, Martin; Cuppen, Edwin

2012-06-28

Chromothripsis represents a novel phenomenon in the structural variation landscape of cancer genomes. Here, we analyze the genomes of ten patients with congenital disease who were preselected to carry complex chromosomal rearrangements with more than two breakpoints. The rearrangements displayed unanticipated complexity resembling chromothripsis. We find that eight of them contain hallmarks of multiple clustered double-stranded DNA breaks (DSBs) on one or more chromosomes. In addition, nucleotide resolution analysis of 98 breakpoint junctions indicates that break repair involves nonhomologous or microhomology-mediated end joining. We observed that these eight rearrangements are balanced or contain sporadic deletions ranging in size between a few hundred base pairs and several megabases. The two remaining complex rearrangements did not display signs of DSBs and contain duplications, indicative of rearrangement processes involving template switching. Our work provides detailed insight into the characteristics of chromothripsis and supports a role for clustered DSBs driving some constitutional chromothripsis rearrangements. Copyright © 2012 The Authors. Published by Elsevier Inc. All rights reserved.

Selection rules for Cooper pairing in two-dimensional interfaces and sheets

NASA Astrophysics Data System (ADS)

Scheurer, Mathias S.; Agterberg, Daniel F.; Schmalian, Jörg

2017-12-01

Thin sheets deposited on a substrate and interfaces of correlated materials offer a plethora of routes towards the realization of exotic phases of matter. In these systems, inversion symmetry is broken which strongly affects the properties of possible instabilities—in particular in the superconducting channel. By combining symmetry and energetic arguments, we derive general and experimentally accessible selection rules for Cooper instabilities in noncentrosymmetric systems, which yield necessary and sufficient conditions for spontaneous time-reversal-symmetry breaking at the superconducting transition and constrain the orientation of the triplet vector. We discuss in detail the implications for various different materials. For instance, we conclude that the pairing state in thin layers of Sr2RuO4 must, as opposed to its bulk superconducting state, preserve time-reversal symmetry with its triplet vector being parallel to the plane of the system. All triplet states of this system allowed by the selection rules are predicted to display topological Majorana modes at dislocations or at the edge of the system. Applying our results to the LaAlO3/SrTiO3 heterostructures, we find that while the condensates of the (001) and (110) oriented interfaces must be time-reversal symmetric, spontaneous time-reversal-symmetry breaking can only occur for the less studied (111) interface. We also discuss the consequences for thin layers of URu2Si2 and UPt3 as well as for single-layer FeSe. On a more general level, our considerations might serve as a design principle in the search for time-reversal-symmetry-breaking superconductivity in the absence of external magnetic fields.

Plate break-up geometry in SE-Afar

NASA Astrophysics Data System (ADS)

Geoffroy, Laurent; Le Gall, Bernard; Daoud, Mohamed

2014-05-01

New structural data acquired in Djibouti strongly support the view of a magma-rich to magma-poor pair of conjugate margins developed in SE Afar since at least 9 Ma. Our model is illustrated by a crustal-scale transect that emphasizes the role of a two-stage extensional detachment fault system, with opposing senses of motion through time. The geometry and kinematics of this detachment fault pattern are mainly documented from lavas and fault dip data extracted from remote sensing imagery (Landsat ETM+, and corresponding DEM), further calibrated by field observations. Although expressed by opposite fault geometries, the two successive extensional events evidenced here are part of a two-stage continental extensional tear-system associated with the ongoing propagation of the Aden-Tadjoura oceanic axis to the NW. A flip-flop evolution of detachment faults accommodating lithosphere divergence has recently been proposed for the development of the Indian Ocean and continental margins (Sauter et al., 2013). However, the SE Afar evolution further suggests a radical and sudden change in lithosphere behavior during extension, from a long-term and widespread magmatic stage to a syn-sedimentary break-up stage where mantle melting concentrates along the future oceanic axis. Of special interest is the fact that a late and rapid stage of non-magmatic extension led to break-up, whose geometry triggered the location of the break-up axis and earliest oceanic accretion. New structural data acquired in Djibouti strongly support the view of a magma-rich to magma-poor pair of conjugate margins developed in SE Afar since at least 9 Ma. Our model is illustrated by a crustal-scale transect that emphasizes the role of a two-stage extensional detachment fault system, with opposing senses of motion through time. The geometry and kinematics of this detachment fault pattern are mainly documented from lavas and fault dip data extracted from remote sensing imagery (Landsat ETM+, and corresponding DEM), further calibrated by field observations. Although expressed by opposite fault geometries, the two successive extensional events evidenced here are part of a two-stage continental extensional tear-system associated with the ongoing propagation of the Aden-Tadjoura oceanic axis to the NW. A flip-flop evolution of detachment faults accommodating lithosphere divergence has recently been proposed for the development of the Indian Ocean and continental margins (Sauter et al., 2013). However, the SE Afar evolution further suggests a radical and sudden change in lithosphere behavior during extension, from a long-term and widespread magmatic stage to a syn-sedimentary break-up stage where mantle melting concentrates along the future oceanic axis. Of special interest is the fact that a late and rapid stage of non-magmatic extension led to break-up, whose geometry triggered the location of the break-up axis and earliest oceanic accretion.

Gamma rays from Penrose powered black holes in Centaurus A, 3C 273, and NGC 4151

NASA Technical Reports Server (NTRS)

Kafatos, M.

1980-01-01

Gamma-ray observations of Cen A, 3C 273, and NGC 4151 are examined under the assumption that Penrose collision processes in the ergospheres of massive black holes power their nuclei. The observed sharp break in the MeV region of the NGC spectrum is attributed to Penrose Compton scattering, and the absence of an MeV break in the spectra of Cen A and 3C 273 implies Penrose pair production. Central black hole masses of tens of millions of solar masses for NGC 4151 and Cen A, and tens of billions of solar masses for 3C 273, are obtained. Attention is also given to accretion rate, the efficiency of accretion, QSOs and Seyferts.

Unconventional Superconductivity in La(7)Ir(3) Revealed by Muon Spin Relaxation: Introducing a New Family of Noncentrosymmetric Superconductor That Breaks Time-Reversal Symmetry.

PubMed

Barker, J A T; Singh, D; Thamizhavel, A; Hillier, A D; Lees, M R; Balakrishnan, G; Paul, D McK; Singh, R P

2015-12-31

The superconductivity of the noncentrosymmetric compound La(7)Ir(3) is investigated using muon spin rotation and relaxation. Zero-field measurements reveal the presence of spontaneous static or quasistatic magnetic fields below the superconducting transition temperature T(c)=2.25  K-a clear indication that the superconducting state breaks time-reversal symmetry. Furthermore, transverse-field rotation measurements suggest that the superconducting gap is isotropic and that the pairing symmetry of the superconducting electrons is predominantly s wave with an enhanced binding strength. The results indicate that the superconductivity in La(7)Ir(3) may be unconventional and paves the way for further studies of this family of materials.

LEAD SEVERING CONTRIVANCE

DOEpatents

Widmaier, W.

1958-04-01

A means for breaking an electrical circuit within an electronic tube during the process of manufacture is described. Frequently such circuits must be employed for gettering or vapor coating purposes, however, since an external pair of corector pins having no use after manufacture, is undesirable, this invention permits the use of existing leads to form a temporary circuit during manufacture, and severing it thereafter. One portion of the temporary circuit, made from a springy material such as tungsten, is spot welded to a fusable member. To cut the circuit an external radiant heat source melts the fusable member, allowing the tensed tungsten spring to contract and break the circuit. This inexpensive arrangement is particularly useful when the tube has a great many external leads crowded into the tube base.

Valley-selective optical Stark effect in monolayer WS2

NASA Astrophysics Data System (ADS)

Gedik, Nuh

Monolayer semiconducting transition-metal dichalcogenides (TMDs) have a pair of valleys that, by time-reversal symmetry, are energetically degenerate. Lifting the valley degeneracy in these materials is of great interest because it would allow for valley specific band engineering and offer additional control in valleytronic applications. In this talk, I will show that circularly polarized light, which breaks time-reversal symmetry, can be used to lift the valley degeneracy by means of the optical Stark effect. We demonstrate that this effect is capable of raising the exciton level in monolayer TMD WS2 by as much as 18 meV in a controllable valley-selective manner. The resulting energy shift is extremely large, comparable to the shift that would be obtained using a very high magnetic field (approximately 100 Tesla). These results offer a novel way to control valley degree of freedom, and may provide a means to realize new valley-selective Floquet topological state of matter.

Controlling a microdisk laser by local refractive index perturbation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liew, Seng Fatt; Redding, Brandon; Cao, Hui, E-mail: hui.cao@yale.edu

2016-02-01

We demonstrate a simple yet effective approach of controlling lasing in a semiconductor microdisk by photo-thermal effect. A continuous wave green laser beam, focused onto the microdisk perimeter, can enhance or suppress lasing in different cavity modes, depending on the position of the focused beam. Its main effect is a local modification of the refractive index of the disk, which results in an increase in the power slope of some lasing modes and a decrease of others. The boundary roughness breaks the rotational symmetry of a circular disk, allowing the lasing process to be tuned by varying the green beammore » position. Using the same approach, we can also fine tune the relative intensity of a quasi-degenerate pair of lasing modes. Such post-fabrication control, enabled by an additional laser beam, is flexible and reversible, thus enhancing the functionality of semiconductor microdisk lasers.« less

Using galaxy pairs to investigate the three-point correlation function in the squeezed limit

NASA Astrophysics Data System (ADS)

Yuan, Sihan; Eisenstein, Daniel J.; Garrison, Lehman H.

2017-11-01

We investigate the three-point correlation function (3PCF) in the squeezed limit by considering galaxy pairs as discrete objects and cross-correlating them with the galaxy field. We develop an efficient algorithm using fast Fourier transforms to compute such cross-correlations and their associated pair-galaxy bias bp, g and the squeezed 3PCF coefficient Qeff. We implement our method using N-body cosmological simulations and a fiducial halo occupation distribution (HOD) and present the results in both the real space and redshift space. In real space, we observe a peak in bp, g and Qeff at pair separation of ∼2 Mpc, attributed to the fact that galaxy pairs at 2 Mpc separation trace the most massive dark matter haloes. We also see strong anisotropy in the bp, g and Qeff signals that track the large-scale filamentary structure. In redshift space, both the 2 Mpc peak and the anisotropy are significantly smeared out along the line of sight due to finger-of-God effect. In both the real space and redshift space, the squeezed 3PCF shows a factor of 2 variation, contradicting the hierarchical ansatz, but offering rich information on the galaxy-halo connection. Thus, we explore the possibility of using the squeezed 3PCF to constrain the HOD. When we compare two simple HOD models that are closely matched in their projected two-point correlation function (2PCF), we do not yet see a strong variation in the 3PCF that is clearly disentangled from variations in the projected 2PCF. Nevertheless, we propose that more complicated HOD models, e.g. those incorporating assembly bias, can break degeneracies in the 2PCF and show a distinguishable squeezed 3PCF signal.

Superconducting Fluctuations above T c and pair breaking parameters of two dimensional Niobium Nitride Films

NASA Astrophysics Data System (ADS)

Shinozaki, B.; Ezaki, S.; Odou, T.; Makise, K.; Asano, T.

2018-03-01

Transport properties have been investigated for the epitaxial superconducting NbN thin films. We analysed the excess conductance σ’ ≡ σ(T) - σN by the sum of the Aslamazov-Larkin (AL) and Maki-Thompson (MT) terms for thermal fluctuations above T c, where the σN ≡1/R sq N is the normal state sheet conductance. We have found that the theoretical expression σ’theo (T) = σ’AL (T) + σ’MT (T,δ) can be well fitted to σ’exp (T) with use of the suitable value of the pair breaking parameter δ in the MT term relating to the inelastic scattering rate 1/τin(T) as δ = πħ/8k B Tτin. The rate 1/τin(T) given by the sum of 1/τfluc(T), 1/τe-e(T) and 1/τe-ph (T) is determined from the analysis of the magneto-conductance Δσ = σ(H) – σ(0) by the sum of AL, MT and the localization terms, where the first, second and third terms correspond to the rate due to the superconducting fluctuation effect, electron-electron and electron-phonon interactions, respectively. The R sq N dependence of δ is expressed by δ = δ0 + αR sq N, where the first term δ0 due to 1/τe-ph (T) and the second term due to the sum of 1/τfluc(T) and 1/τe-e(T). Although we obtained a reasonable value of Debye temperature ΘD ≈630 K from the δ0, the magnitude of the α is about 5 times larger than the theoretical value.

Calculation on spectrum of direct DNA damage induced by low-energy electrons including dissociative electron attachment.

PubMed

Liu, Wei; Tan, Zhenyu; Zhang, Liming; Champion, Christophe

2017-03-01

In this work, direct DNA damage induced by low-energy electrons (sub-keV) is simulated using a Monte Carlo method. The characteristics of the present simulation are to consider the new mechanism of DNA damage due to dissociative electron attachment (DEA) and to allow determining damage to specific bases (i.e., adenine, thymine, guanine, or cytosine). The electron track structure in liquid water is generated, based on the dielectric response model for describing electron inelastic scattering and on a free-parameter theoretical model and the NIST database for calculating electron elastic scattering. Ionization cross sections of DNA bases are used to generate base radicals, and available DEA cross sections of DNA components are applied for determining DNA-strand breaks and base damage induced by sub-ionization electrons. The electron elastic scattering from DNA components is simulated using cross sections from different theoretical calculations. The resulting yields of various strand breaks and base damage in cellular environment are given. Especially, the contributions of sub-ionization electrons to various strand breaks and base damage are quantitatively presented, and the correlation between complex clustered DNA damage and the corresponding damaged bases is explored. This work shows that the contribution of sub-ionization electrons to strand breaks is substantial, up to about 40-70%, and this contribution is mainly focused on single-strand break. In addition, the base damage induced by sub-ionization electrons contributes to about 20-40% of the total base damage, and there is an evident correlation between single-strand break and damaged base pair A-T.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arcadi, Giorgio; Ghosh, Pradipta; Centre de Physique Théorique, Ecole polytechnique, CNRS, Université Paris-Saclay, 91128 Palaiseau Cedex

We investigate a simple setup in which an excess in the di-photon invariant mass distribution around 750 GeV, as seen by the ATLAS and CMS collaborations, is originated through a pair of collimated photon pairs. In this framework a scalar state s decays into two light pseudo-Goldstone bosons a, each of which subsequently decays into a pair of collimated photons which are misidentified as a single photon. In a minimal context of spontaneous symmetry breaking, we show that coupling a complex scalar field Φ=(s+ia)/√2 to a fermionic dark matter candidate χ, also responsible for generating its mass, allows for themore » correct relic density in a large region of the parameter space, while not being excluded by the direct or indirect detection experiments. Moreover, the correct relic abundance can naturally co-exist with a relatively large width for the resonant field s.« less

[Diagnosis and therapy of particle disease in total hip arthroplasty].

PubMed

Müller, M; Wassilew, G; Perka, C

2015-04-01

Particle disease is caused by periarticular accumulation of attrition particles and the inflammatory reaction of the body's tissue. This process may result in osteolysis or soft tissue transformation which presents itself symptomless in the beginning and can proceed to aseptic implant loosening, fracture, implant breaking as a result of the inappropriate osseous support and to algetic and destructive soft tissue reactions as well. Attrition particles originate from tribological pairing, and the extent of the attrition or the particle concentration depend on different factors as there are the tribological pairing's material, the head size, the patient's level of activity, and the implant position. Attrition particles can also be found in the range of any modular connection. Particle disease and its resulting morphological alterations of the tribological pairing is one of the most frequent reasons for re-operation in hip endoprosthetics. Georg Thieme Verlag KG Stuttgart · New York.

Antarctic Meteorite Newsletter, Volume 31, No. 1

NASA Technical Reports Server (NTRS)

Satterwhite, Cecilia (Editor); Righter, Kevin (Editor)

2008-01-01

This newsletter reports 418 new meteorites from the 2004 and 2006 ANSMET seasons from the Cumulus Hills (CMS), LaPaz Ice Field (LAP), Graves Nunataks (GRA), Grosvenor Mountains (GRO), Larkman Nunatak (LAR), MacAlpine Hills (MAC), Miller Range (MIL), Roberts Massif (RBT), and Scott Glacier (SCO). These new samples include one iron, 1 eucrite, 1 mesosiderite, 6 CK chondrites (2 with pairing), 2 CV3 chondrites, 1 CM1, 7 CM2 (4 with pairing), 3 CR2 (2 with pairing), and one each of a type 3 L and H chondrites. The CK6 chondrites (LAR 06869, 06872, 06873) are unusual in that they have no discernable chondrules, extremely fine-grained texture, and are full of veins. This newsletter represents a break from recent newsletters in which we have announced many unusual and popular samples, including new lunar and martian meteorites, an unusual achondrite (GRA 06128 and 06129 the topic of a special session at this years LPSC).

Observation of multiple superconducting gaps in Fe1+y Se x Te 1-x through Andreev reflection

NASA Astrophysics Data System (ADS)

de, Debtanu; Diaz-Pinto, Carlos; Wu, Zheng; Hor, Pei-Herng; Peng, Haibing

2011-03-01

Iron-based superconductors have been under intensive study because of the high transition temperature and the intriguing physical mechanisms involving the superconductivity and magnetic orders. Theoretical studies on the role of spin fluctuation suggest unconventional S wave pairing and multiple superconducting (SC) gaps due to the five disjoint Fermi surfaces. However, this multiple SC-gap scenario has yet to be confirmed in experiments. Here we report the experimental observation of five SC gaps in Fe 1+y Se x Te 1-x from Andreev reflection spectra, along with negative differential conductance dips due to the pair breaking related to the largest SC gap. The evolution of the multiple SC gaps is further investigated as a function of both temperature and magnetic field. For the largest SC gap, the Andreev reflection signal persists above bulk Tc, suggesting the existence of phase incoherent Cooper pairs.

Mean-field description of topological charge 4e superconductors

NASA Astrophysics Data System (ADS)

Gabriele, Victoria; Luo, Jing; Teo, Jeffrey C. Y.

BCS superconductors can be understood by a mean-field approximation of two-body interacting Hamiltonians, whose ground states break charge conservation spontaneously by allowing non-vanishing expectation values of charge 2e Cooper pairs. Topological superconductors, such as one-dimensional p-wave wires, have non-trivial ground states that support robust gapless boundary excitations. We construct a four-body Hamiltonian in one dimension and perform a mean-field analysis. The mean-field Hamiltonian is now quartic in fermions but is still exactly solvable. The ground state exhibits 4-fermion expectation values instead of Cooper pair ones. There also exists a topological phase, where the charge 4e superconductor carries exotic zero energy boundary excitations.

Gamma ray pulsars

NASA Technical Reports Server (NTRS)

Oegelman, H.; Ayasli, S.; Hacinliyan, A.

1976-01-01

Recent data from the high energy gamma ray experiment have revealed the existence of four pulsars emitting photons above 35 MeV. An attempt is made to explain the gamma ray emission from these pulsars in terms of an electron-photon cascade that develops in the magnetosphere of the pulsar. Although there is very little material above the surface of the pulsar, the very intense magnetic fields correspond to many radiation lengths which cause electrons to emit photons via magnetic bremsstrahlung and these photons to pair produce. The cascade develops until the mean photon energy drops below the pair production threshold which happens to be in the gamma ray range; at this stage the photons break out from the source.

Ion Transport via Structural Relaxations in Polymerized Ionic Liquids

NASA Astrophysics Data System (ADS)

Ganesan, Venkat; Mogurampelly, Santosh

We study the mechanisms underlying ion transport in poly(1-butyl-3-vinylimidazolium-hexafluorophosphate) polymer electrolytes. We consider polymer electrolytes of varying polymerized ionic liquid to ionic liquid (polyIL:IL) ratios and use atomistic molecular dynamics (MD) simulations to probe the dynamical and structural characteristics of the electrolyte. Our results reveal that anion diffusion along polymer backbone occurs primarily viathe formation and breaking of ion-pairs involving threepolymerized cationic monomers of twodifferent polymer chains. Moreover, we observe that the ionic diffusivities exhibit a direct correlation with the structural relaxation times of the ion-pairs and hydrogen bonds (H-bonds). These results provide new insights into the mechanisms underlying ion transport in polymerized ionic liquid electrolytes.

Stop and revive? The effectiveness of nap and active rest breaks for reducing driver sleepiness.

PubMed

Watling, Christopher N; Smith, Simon S; Horswill, Mark S

2014-11-01

The purpose of this study was to compare the effects of two commonly utilized sleepiness countermeasures: a nap break and an active rest break. The effects of the countermeasures were evaluated by physiological (EEG), subjective, and driving performance measures. Participants completed 2 h of simulated driving, followed by a 15-min nap break or a 15-min active rest break, then completed the final hour of simulated driving. The nap break reduced EEG and subjective sleepiness. The active rest break did not reduce EEG sleepiness, with sleepiness levels eventually increasing, and resulted in an immediate reduction of subjective sleepiness. No difference was found between the two breaks for the driving performance measure. The immediate reduction of subjective sleepiness after the active rest break could leave drivers with erroneous perceptions of their sleepiness, particularly with increases of physiological sleepiness after the break. Copyright © 2014 Society for Psychophysiological Research.

Topological superconductivity in the extended Kitaev-Heisenberg model

NASA Astrophysics Data System (ADS)

Schmidt, Johann; Scherer, Daniel D.; Black-Schaffer, Annica M.

2018-01-01

We study superconducting pairing in the doped Kitaev-Heisenberg model by taking into account the recently proposed symmetric off-diagonal exchange Γ . By performing a mean-field analysis, we classify all possible superconducting phases in terms of symmetry, explicitly taking into account effects of spin-orbit coupling. Solving the resulting gap equations self-consistently, we map out a phase diagram that involves several topologically nontrivial states. For Γ <0 , we find a competition between a time-reversal symmetry-breaking chiral phase with Chern number ±1 and a time-reversal symmetric nematic phase that breaks the rotational symmetry of the lattice. On the other hand, for Γ ≥0 we find a time-reversal symmetric phase that preserves all the lattice symmetries, thus yielding clearly distinguishable experimental signatures for all superconducting phases. Both of the time-reversal symmetric phases display a transition to a Z2 nontrivial phase at high doping levels. Finally, we also include a symmetry-allowed spin-orbit coupling kinetic energy and show that it destroys a tentative symmetry-protected topological order at lower doping levels. However, it can be used to tune the time-reversal symmetric phases into a Z2 nontrivial phase even at lower doping.

Quasi-Periodic Variability in NGC 5408 X-1

NASA Technical Reports Server (NTRS)

Strohmayer, Tod E.; Mushotzky, Richard F.; Winter, Lisa; Soria, Roberto; Uttley, Phil; Cropper, Mark

2007-01-01

We report the discovery with XMM-Newton of quasiperiodic variability in the 0.2 - 10 keV X-ray flux from the ultraluminous X-ray source NGC 5408 X-1. The average power spectrum of all EPIC-pn data reveals a strong 20 mHz QPO with an average amplitude (rms) of 9%, and a coherence, Q identical with nu(sub 0)/sigma approximately equal to 6. In a 33 ksec time interval when the 20 mHz QPO is strongest we also find evidence for a 2nd QPO peak at 15 mHz, the first indication for a close pair of QPOs in a ULX source. Interestingly, the frequency ratio of this QPO pair is inconsistent with 3:2 at the 3 sigma level, but is consistent with a 4:3 ratio. A powerlaw noise component with slope near 1.5 is also present below 0.1 Hz with evidence for a break to a flatter slope at about 3 mHz. The source shows substantial broadband variability, with a total amplitude (rms) of about 30% in the 0.1 - 100 mHz frequency band, and there is strong energy dependence to the variability. The power spectrum of hard X-ray photons (greater than 2 keV) shows a "classic" flat-topped continuum breaking to a power law with index 1.5 - 2. Both the break and 20 mHz QPO are detected in the hard band, and the 20 mHz QPO is essentially at the break. The QPO is both strong and narrow in this band, having an amplitude (rms) of 15%, and Q approx. equal to 25. The energy spectrum is well fit by three components, a "cool" disk with kT = 0.15 keV, a steep power law with index 2.56, and a thermal plasma at kT = 0.87 keV. The disk, power law, and thermal plasma components contribute 35, 60, and 5% of the 0.3 - 10 keV flux, respectively. Both the timing and spectral properties of NGC 5408 X-1 are strikingly reminiscent of Galactic black hole systems at high inferred accretion rates, but with its characteristic frequencies (QPO and break frequencies) scaled down by a factor of 10 - 100. We discuss the implications of these findings in the context of models for ULXs, and their implications for the object's mass.

Pairs of galaxies in low density regions of a combined redshift catalog

NASA Technical Reports Server (NTRS)

Charlton, Jane C.; Salpeter, Edwin E.

1990-01-01

The distributions of projected separations and radial velocity differences of pairs of galaxies in the CfA and Southern Sky Redshift Survey (SSRS) redshift catalogs are examined. The authors focus on pairs that fall in low density environments rather than in clusters or large groups. The projected separation distribution is nearly flat, while uncorrelated galaxies would have given one linearly rising with r sub p. There is no break in this curve even below 50 kpc, the minimum halo size consistent with measured galaxy rotation curves. The significant number of pairs at small separations is inconsistent with the N-body result that galaxies with overlapping halos will rapidly merge, unless there are significant amounts of matter distributed out to a few hundred kpc of the galaxies. This dark matter may either be in distinct halos or more loosely distributed. Large halos would allow pairs at initially large separations to head toward merger, replenishing the distribution at small separations. In the context of this model, the authors estimate that roughly 10 to 25 percent of these low density galaxies are the product of a merger, compared with the elliptical/SO fraction of 18 percent, observed in low density regions of the sample.

Divorce and infidelity are associated with skewed adult sex ratios in birds.

PubMed

Liker, András; Freckleton, Robert P; Székely, Tamás

2014-04-14

Adult sex ratio (ASR) is a fundamental concept in population demography, and recent theory suggests that ASR plays a central role in social behavior, mating systems, and parental care. Unbalanced ASRs are predicted to influence pair-bond and mating behavior, since the rarer sex in the population has more potential partners to mate with than the more common sex. Here we use phylogenetic comparative analyses to test whether ASR is related to three major aspects of mating behavior: divorce, social polygamy, and pair-bond infidelity. ASR is strongly correlated with long-term pair bonds, since the divorce rate is higher in species with a female-biased sex ratio, indicating that mate change by pair members and/or breaking of pair bonds by unmated individuals is more frequent when females outnumber males. Short-term pair bonds are also associated with unbalanced ASRs: males are more commonly polygamous when females outnumber males, and conversely, females are more polygamous when males outnumber females. Furthermore, infidelity increases with male-biased ASR in socially monogamous birds, suggesting that male coercion and/or female willingness to cheat the partner are facilitated by male-biased ASR. Our results provide the first comprehensive support for the proposition that ASR influences multiple aspects of pair-bond and mating behavior in wild populations. Copyright © 2014 Elsevier Ltd. All rights reserved.

Mixing enhancement of reacting parallel fuel jets in a supersonic combustor

NASA Technical Reports Server (NTRS)

Drummond, J. P.

1991-01-01

Pursuant to a NASA-Langley development program for a scramjet HST propulsion system entailing the optimization of the scramjet combustor's fuel-air mixing and reaction characteristics, a numerical study has been conducted of the candidate parallel fuel injectors. Attention is given to a method for flow mixing-process and combustion-efficiency enhancement in which a supersonic circular hydrogen jet coflows with a supersonic air stream. When enhanced by a planar oblique shock, the injector configuration exhibited a substantial degree of induced vorticity in the fuel stream which increased mixing and chemical reaction rates, relative to the unshocked configuration. The resulting heat release was effective in breaking down the stable hydrogen vortex pair that had inhibited more extensive fuel-air mixing.

Radiotherapy Measurements with a Deoxyribonucleic Acid Doublestrand-Break Dosimeter

NASA Astrophysics Data System (ADS)

Obeidat, Mohammad Ali

Many types of dosimeters are used in the clinic to measure radiation dose for therapy but none of them directly measures the biological effect of this dose. The overall purpose of this work was to develop a dosimeter that measures biological damage in the form of double-strand breaks to deoxyribonucleic acid. This dosimeter could provide a more biologically relevant measure of radiation damage than the currently utilized dosimeters. A pair of oligonucleotides was designed to fabricate this dosimeter. One is labeled with a 5'-end biotin and the other with a 5'-end 6 Fluorescein amidite (fluorescent dye excited at 495?nanometer, with a peak emission at 520 nanometer). These were designed to adhere to certain locations on the pRS316 vector and serve as the primers for polymerase chain reactions. The end product of this reaction is a 4 kilo-base pair double strands deoxyribonucleic acid fragment with biotin on one end and 6 Fluorescein amidite oligonucleotide on the other attached to streptavidin beads. The biotin end connects the double strands deoxyribonucleic acid to the streptavidin bead. These bead-connected double strands deoxyribonucleic acid were suspended in 50 microliter of phosphate-buffered saline and placed into a tube for irradiation. Following irradiation of the deoxyribonucleic acid dosimeter, we take advantage of the magnetic properties of the streptavidin bead by placing our sample microtube against a magnet. The magnetic field pulls the streptavidin beads against the side of the tube. If a double-strand-break has occurred for a double strands deoxyribonucleic acid, the fluorescein end of the double strands deoxyribonucleic acid becomes free and is no longer attached to the bead or held against the side of the microtube. The free fluorescein following a double-strand-break in double strands deoxyribonucleic acid is referred to here as supernatant. The supernatant is extracted and placed in another microtube, while the unbroken double strands deoxyribonucleic acid remain attached to the beads and stay in the microtube (Fig. 4). Those beads were re-suspended with 50 microliter of phosphate-buffered saline again (called beads), then we placed both supernatant and beads in a reader microplate and we read the fluorescence signal for both with a fluorescence reader (BioTek Synergy 2). These beads and supernatant fluorescence signals are denoted by B and S, respectively. The relative amount of supernatant fluorescence counts is proportional to the probability of a double-strand-break. The probability of double-strand-break was calculated with the following equation: (S-BG)/(S+B-2BG) (1). where S was the supernatant fluorescence intensity (related to the number of double strands deoxyribonucleic acid with double-strand breaks), B was the re-suspended beads fluorescence intensity (related to the number of double strands deoxyribonucleic acid without double-strand breaks), and BG was the phosphate-buffered saline fluorescence intensity (related to the background signal). There are two advantages that this type of dosimeter has over the gel separation technique. First, it is important to irradiate deoxyribonucleic acid in a solution that has similar osmolarity and ion concentrations to that in a human, such as phosphate-buffered saline. A gel dosimeter would require a transfer to gel to separate deoxyribonucleic acid, whereas our dosimeter can be separated in this solution. Currently, we use pipettes to manually perform this separation, but this step could be automated. Second, the magnetic deoxyribonucleic acid separation technique is much faster than that for gel electrophoresis. Calibration of radiotherapy equipment isn't something that happens in national science laboratories, with only world-leading experts. This is something that happens locally at every cancer clinic, with physicists that do not have the luxury of focusing solely on this one measurement. For this reason, ease of use is critical for this type of technology. (Abstract shortened by ProQuest.).

Patient focused care team design. Critical aspects of a cost-effective design strategy.

PubMed

Leander, W J

1993-01-01

It is the critical, yet largely unknown aspects of Patient Focused care team design--the "how" of a design process--which make LRMC's "Care Pairs" a ground-breaking innovation rather than just a distinctive-sounding name. Unfortunately, many hospital leaders of Patient Focused Care programs know the "what" of LRMC's "Care Pairs" but very little, if anything, about this "how." To create Patient Focused care teams which are "right" for your own institution, you must quantify the Costs of Continuity, Competency and Compartmentalization and their associated benefits. Without these informed trade-offs, you and your hospital will be forced to live with someone else's Patient Focused care team design. In summary, it is what you don't know about LRMC's "Care Pairs," not what you do know, that is important to your Patient Focused Care program. Hospitals just beginning to implement Patient Focused Care must understand this "how" if they are to design effective care teams which optimize the performance of their initial unit(s) within their unique environments. Hospitals like LRMC with established Patient Focused Care units must also periodically draw upon this "how" or they face the very real danger of having their Patient Focused care team design(s) become outdated, less effective and eventually detrimental. Or, said another way: "The man who does not read good books has no advantage over those who cannot." Mark Twain. "An out-of-date Patient Focused hospital has no advantage over those which remain unrestructured." The PFCA. The three critical aspects of Patient Focused care team design explored in this article are just the tip of the iceberg.(ABSTRACT TRUNCATED AT 250 WORDS)

Does syntax contribute to the function of duets in a parrot, Amazona auropalliata?

PubMed

Dahlin, Christine R; Wright, Timothy F

2012-07-01

Complex acoustic signals in many animal species are characterized by a syntax that governs how different notes are combined, but the importance of syntax to the communicative function of signals is not well understood. Mated pairs of yellow-naped amazons, Amazona auropalliata, produce coordinated vocal duets that are used for territory maintenance and defense. These duets follow rules that specify the ordering of notes within duets, such as a strict alternation of sex-specific notes and a defined progression of note types through each duet. These syntactical rules may function to define sex-specific roles, improve coordination, and allow individuals to combine calls into meaningful sequences. As a first step toward understanding the functional significance of syntax, we conducted two separate audio playback experiments in which we presented nesting pairs with normal duets and duets with broken syntax (i.e., one of the syntactic rules was broken). In Experiment One, we reversed the order of female and male notes within note pairs while retaining the typical progression of note types through a duet. In Experiment Two we reversed the order of note types across a whole duet while retaining the typical female-male ordering within note pairs. We hypothesized that duets with broken syntax would be less-effective signals than duets with normal syntax and predicted that pairs would respond less to broken syntax than to normal duets. Contrary to predictions, we did not observe differences in response between treatments for any variables except latency to approach the speaker. After we combined data across experiments post hoc, we observed longer latencies to approach the speakers after playbacks of broken syntax duets, suggesting that pairs could differentiate between playbacks. These responses suggest that breaking one rule of duet syntax at a time does not result in detectable loss of signal efficacy in the context of territorial intrusions.

Chromatin Folding, Fragile Sites, and Chromosome Aberrations Induced by Low- and High- LET Radiation

NASA Technical Reports Server (NTRS)

Zhang, Ye; Cox, Bradley; Asaithamby, Aroumougame; Chen, David J.; Wu, Honglu

2013-01-01

We previously demonstrated non-random distributions of breaks involved in chromosome aberrations induced by low- and high-LET radiation. To investigate the factors contributing to the break point distribution in radiation-induced chromosome aberrations, human epithelial cells were fixed in G1 phase. Interphase chromosomes were hybridized with a multicolor banding in situ hybridization (mBAND) probe for chromosome 3 which distinguishes six regions of the chromosome in separate colors. After the images were captured with a laser scanning confocal microscope, the 3-dimensional structure of interphase chromosome 3 was reconstructed at multimega base pair scale. Specific locations of the chromosome, in interphase, were also analyzed with bacterial artificial chromosome (BAC) probes. Both mBAND and BAC studies revealed non-random folding of chromatin in interphase, and suggested association of interphase chromatin folding to the radiation-induced chromosome aberration hotspots. We further investigated the distribution of genes, as well as the distribution of breaks found in tumor cells. Comparisons of these distributions to the radiation hotspots showed that some of the radiation hotspots coincide with the frequent breaks found in solid tumors and with the fragile sites for other environmental toxins. Our results suggest that multiple factors, including the chromatin structure and the gene distribution, can contribute to radiation-induced chromosome aberrations.

An Analysis of Wilson Cycle Plate Margins

NASA Astrophysics Data System (ADS)

Buiter, S.; Torsvik, T. H.

2012-12-01

The Wilson Cycle theory that oceans close and open along the same suture is a powerful concept in analyses of ancient plate tectonics. It implies that collision zones are structures that are able to localize extensional deformation for long times after the collision has waned. However, some sutures are seemingly never reactivated and already Tuzo Wilson recognized that Atlantic break-up did not follow the precise line of previous junction. We have reviewed margin pairs around the Atlantic and Indian Oceans with the aim to evaluate the extent to which oceanic opening used former sutures, summarize delay times between collision and break-up, and analyze the role of mantle plumes in continental break-up. We aid our analyses with plate tectonic reconstructions using GPlates (www.gplates.org). Although at first sight opening of the North Atlantic Ocean largely seems to follow the Iapetus and Rheic sutures, a closer look reveals deviations. For example, Atlantic opening did not utilize the Iapetus suture in Great Britain and rather than opening along the younger Rheic suture north of Florida, break-up occurred along the older Pan-African structures south of Florida. We find that today's oceanic Charlie Gibbs Fracture Zone, between Ireland and Newfoundland, is aligned with the Iapetus suture. We speculate therefore that in this region the Iapetus suture was reactivated as a transform fault. As others before us, we find no correlation of suture and break-up age. Often continental break-up occurs some hundreds of Myrs after collision, but it may also take over 1000 Myr, as for example for Australia - Antarctica and Congo - São Francisco. This places serious constraints on potential collision zone weakening mechanisms. Several studies have pointed to a link between continental break-up and large-scale mantle upwellings. It is, however, much debated whether plumes use existing rifts as a pathway, or whether plumes play an active role in causing rifting. We find a positive correlation between break-up age and plume age, which we interpret to indicate that plumes can aid the factual continental break-up. However, plumes may have been guided towards the rift for margins that experienced a long rift history (e.g., Norway-Greenland), to then trigger the break-up. This could offer a partial reconciliation in the debate of a passive or active role for mantle plumes in continental break-up.

Mapping DNA cleavage by the Type ISP restriction-modification enzymes following long-range communication between DNA sites in different orientations

PubMed Central

van Aelst, Kara; Saikrishnan, Kayarat; Szczelkun, Mark D.

2015-01-01

The prokaryotic Type ISP restriction-modification enzymes are single-chain proteins comprising an Mrr-family nuclease, a superfamily 2 helicase-like ATPase, a coupler domain, a methyltransferase, and a DNA-recognition domain. Upon recognising an unmodified DNA target site, the helicase-like domain hydrolyzes ATP to cause site release (remodeling activity) and to then drive downstream translocation consuming 1–2 ATP per base pair (motor activity). On an invading foreign DNA, double-strand breaks are introduced at random wherever two translocating enzymes form a so-called collision complex following long-range communication between a pair of target sites in inverted (head-to-head) repeat. Paradoxically, structural models for collision suggest that the nuclease domains are too far apart (>30 bp) to dimerise and produce a double-strand DNA break using just two strand-cleavage events. Here, we examined the organisation of different collision complexes and how these lead to nuclease activation. We mapped DNA cleavage when a translocating enzyme collides with a static enzyme bound to its site. By following communication between sites in both head-to-head and head-to-tail orientations, we could show that motor activity leads to activation of the nuclease domains via distant interactions of the helicase or MTase-TRD. Direct nuclease dimerization is not required. To help explain the observed cleavage patterns, we also used exonuclease footprinting to demonstrate that individual Type ISP domains can swing off the DNA. This study lends further support to a model where DNA breaks are generated by multiple random nicks due to mobility of a collision complex with an overall DNA-binding footprint of ∼30 bp. PMID:26507855

Validation of rearrangement break points identified by paired-end sequencing in natural populations of Drosophila melanogaster.

PubMed

Cridland, Julie M; Thornton, Kevin R

2010-01-13

Several recent studies have focused on the evolution of recently duplicated genes in Drosophila. Currently, however, little is known about the evolutionary forces acting upon duplications that are segregating in natural populations. We used a high-throughput, paired-end sequencing platform (Illumina) to identify structural variants in a population sample of African D. melanogaster. Polymerase chain reaction and sequencing confirmation of duplications detected by multiple, independent paired-ends showed that paired-end sequencing reliably uncovered the break points of structural rearrangements and allowed us to identify a number of tandem duplications segregating within a natural population. Our confirmation experiments show that rates of confirmation are very high, even at modest coverage. Our results also compare well with previous studies using microarrays (Emerson J, Cardoso-Moreira M, Borevitz JO, Long M. 2008. Natural selection shapes genome wide patterns of copy-number polymorphism in Drosophila melanogaster. Science. 320:1629-1631. and Dopman EB, Hartl DL. 2007. A portrait of copy-number polymorphism in Drosophila melanogaster. Proc Natl Acad Sci U S A. 104:19920-19925.), which both gives us confidence in the results of this study as well as confirms previous microarray results.We were also able to identify whole-gene duplications, such as a novel duplication of Or22a, an olfactory receptor, and identify copy-number differences in genes previously known to be under positive selection, like Cyp6g1, which confers resistance to dichlorodiphenyltrichloroethane. Several "hot spots" of duplications were detected in this study, which indicate that particular regions of the genome may be more prone to generating duplications. Finally, population frequency analysis of confirmed events also showed an excess of rare variants in our population, which indicates that duplications segregating in the population may be deleterious and ultimately destined to be lost from the population.

Combining symmetry breaking and restoration with configuration interaction: A highly accurate many-body scheme applied to the pairing Hamiltonian

NASA Astrophysics Data System (ADS)

Ripoche, J.; Lacroix, D.; Gambacurta, D.; Ebran, J.-P.; Duguet, T.

2017-01-01

Background: Ab initio many-body methods have been developed over the past ten years to address mid-mass nuclei. In their best current level of implementation, their accuracy is of the order of a few percent error on the ground-state correlation energy. Recently implemented variants of these methods are operating a breakthrough in the description of medium-mass open-shell nuclei at a polynomial computational cost while putting state-of-the-art models of internucleon interactions to the test. Purpose: As progress in the design of internucleon interactions is made, and as questions one wishes to answer are refined in connection with increasingly available experimental data, further efforts must be made to tailor many-body methods that can reach an even higher precision for an even larger number of observable quantum states or nuclei. The objective of the present work is to contribute to such a quest by designing and testing a new many-body scheme. Methods: We formulate a truncated configuration-interaction method that consists of diagonalizing the Hamiltonian in a highly truncated subspace of the total N -body Hilbert space. The reduced Hilbert space is generated via the particle-number projected BCS state along with projected seniority-zero two- and four-quasiparticle excitations. Furthermore, the extent by which the underlying BCS state breaks U(1 ) symmetry is optimized in the presence of the projected two- and four-quasiparticle excitations. This constitutes an extension of the so-called restricted variation after projection method in use within the frame of multireference energy density functional calculations. The quality of the newly designed method is tested against exact solutions of the so-called attractive pairing Hamiltonian problem. Results: By construction, the method reproduces exact results for N =2 and N =4 . For N =(8 ,16 ,20 ) , the error in the ground-state correlation energy is less than (0.006%, 0.1%, 0.15%) across the entire range of internucleon coupling defining the pairing Hamiltonian and driving the normal-to-superfluid quantum phase transition. The presently proposed method offers the advantage of automatic access to the low-lying spectroscopy, which it does with high accuracy. Conclusions: The numerical cost of the newly designed variational method is polynomial (N6) in system size. This method achieves unprecedented accuracy for the ground-state correlation energy, effective pairing gap, and one-body entropy as well as for the excitation energy of low-lying states of the attractive pairing Hamiltonian. This constitutes a sufficiently strong motivation to envision its application to realistic nuclear Hamiltonians in view of providing a complementary, accurate, and versatile ab initio description of mid-mass open-shell nuclei in the future.

Modeling the safety impacts of driving hours and rest breaks on truck drivers considering time-dependent covariates.

PubMed

Chen, Chen; Xie, Yuanchang

2014-12-01

Driving hours and rest breaks are closely related to driver fatigue, which is a major contributor to truck crashes. This study investigates the effects of driving hours and rest breaks on commercial truck driver safety. A discrete-time logistic regression model is used to evaluate the crash odds ratios of driving hours and rest breaks. Driving time is divided into 11 one hour intervals. These intervals and rest breaks are modeled as dummy variables. In addition, a Cox proportional hazards regression model with time-dependent covariates is used to assess the transient effects of rest breaks, which consists of a fixed effect and a variable effect. Data collected from two national truckload carriers in 2009 and 2010 are used. The discrete-time logistic regression result indicates that only the crash odds ratio of the 11th driving hour is statistically significant. Taking one, two, and three rest breaks can reduce drivers' crash odds by 68%, 83%, and 85%, respectively, compared to drivers who did not take any rest breaks. The Cox regression result shows clear transient effects for rest breaks. It also suggests that drivers may need some time to adjust themselves to normal driving tasks after a rest break. Overall, the third rest break's safety benefit is very limited based on the results of both models. The findings of this research can help policy makers better understand the impact of driving time and rest breaks and develop more effective rules to improve commercial truck safety. Copyright © 2014 National Safety Council and Elsevier Ltd. All rights reserved.

Suppression of HBV replication by the expression of nickase- and nuclease dead-Cas9.

PubMed

Kurihara, Takeshi; Fukuhara, Takasuke; Ono, Chikako; Yamamoto, Satomi; Uemura, Kentaro; Okamoto, Toru; Sugiyama, Masaya; Motooka, Daisuke; Nakamura, Shota; Ikawa, Masato; Mizokami, Masashi; Maehara, Yoshihiko; Matsuura, Yoshiharu

2017-07-21

Complete removal of hepatitis B virus (HBV) DNA from nuclei is difficult by the current therapies. Recent reports have shown that a novel genome-editing tool using Cas9 with a single-guide RNA (sgRNA) system can cleave the HBV genome in vitro and in vivo. However, induction of a double-strand break (DSB) on the targeted genome by Cas9 risks undesirable off-target cleavage on the host genome. Nickase-Cas9 cleaves a single strand of DNA, and thereby two sgRNAs are required for inducing DSBs. To avoid Cas9-induced off-target mutagenesis, we examined the effects of the expressions of nickase-Cas9 and nuclease dead Cas9 (d-Cas9) with sgRNAs on HBV replication. The expression of nickase-Cas9 with a pair of sgRNAs cleaved the target HBV genome and suppressed the viral-protein expression and HBV replication in vitro. Moreover, nickase-Cas9 with the sgRNA pair cleaved the targeted HBV genome in mouse liver. Interestingly, d-Cas9 expression with the sgRNAs also suppressed HBV replication in vitro without cleaving the HBV genome. These results suggest the possible use of nickase-Cas9 and d-Cas9 with a pair of sgRNAs for eliminating HBV DNA from the livers of chronic hepatitis B patients with low risk of undesirable off-target mutation on the host genome.

Instantaneous and scale-versatile gourdron theory: pair momentum equation, quasi-stability concept, and statistical indeterminacy revealing masses of elementary, bio-molecular, and cosmic particles

NASA Astrophysics Data System (ADS)

Naitoh, Ken

2014-04-01

Flexible particles, including hadrons, atoms, hydrated biological molecules, cells, organs containing water, liquid fuel droplets in engines, and stars commonly break up after becoming a gourd shape rather than that of a string; this leads to cyto-fluid dynamics that can explain the proliferation, differentiation, and replication of biomolecules, onto-biology that clarifies the relationship between information, structure, and function, and the gourd theory that clarifies masses, including quark-leptons and Plank energy. The masses are related to the super-magic numbers, including the asymmetric silver ratio and symmetric yamato ratio, and reveal further mechanisms underlying symmetry breaking. This paper gives further theoretical basis and evidence, because the gourd theory reported previously is a little analogical and instinctive.

BoD services in layer 1 VPN with dynamic virtual concatenation group

NASA Astrophysics Data System (ADS)

Du, Shu; Peng, Yunfeng; Long, Keping

2008-11-01

Bandwidth-on-Demand (BoD) services are characteristic of dynamic bandwidth provisioning based on customers' resource requirement, which will be a must for future networks. BoD services become possible with the development of make-before-break, Virtual Concatenation (VCAT) and Link Capacity Adjustment Scheme (LCAS). In this paper, we introduce BoD services into L1VPN, thus the resource assigned to a L1VPN can be gracefully adjusted at various bandwidth granularities based on customers' requirement. And we propose a dynamic bandwidth adjustment scheme, which is compromise between make-before-break and VCAT&LCAS and mainly based on the latter. The scheme minimizes the number of distinct paths to support a connection between a source-destination pair, and uses make-beforebreak technology for re-optimization.

Identification of a triplet pair intermediate in singlet exciton fission in solution

PubMed Central

Stern, Hannah L.; Musser, Andrew J.; Gelinas, Simon; Parkinson, Patrick; Herz, Laura M.; Bruzek, Matthew J.; Anthony, John; Friend, Richard H.; Walker, Brian J.

2015-01-01

Singlet exciton fission is the spin-conserving transformation of one spin-singlet exciton into two spin-triplet excitons. This exciton multiplication mechanism offers an attractive route to solar cells that circumvent the single-junction Shockley–Queisser limit. Most theoretical descriptions of singlet fission invoke an intermediate state of a pair of spin-triplet excitons coupled into an overall spin-singlet configuration, but such a state has never been optically observed. In solution, we show that the dynamics of fission are diffusion limited and enable the isolation of an intermediate species. In concentrated solutions of bis(triisopropylsilylethynyl)[TIPS]—tetracene we find rapid (<100 ps) formation of excimers and a slower (∼10 ns) break up of the excimer to two triplet exciton-bearing free molecules. These excimers are spectroscopically distinct from singlet and triplet excitons, yet possess both singlet and triplet characteristics, enabling identification as a triplet pair state. We find that this triplet pair state is significantly stabilized relative to free triplet excitons, and that it plays a critical role in the efficient endothermic singlet fission process. PMID:26060309

Effects of school breaks on influenza-like illness incidence in a temperate Chinese region: an ecological study from 2008 to 2015.

PubMed

Chu, Yanhui; Wu, Zhenyu; Ji, Jiayi; Sun, Jingyi; Sun, Xiaoyu; Qin, Guoyou; Qin, Jingning; Xiao, Zheng; Ren, Jian; Qin, Di; Zheng, Xueying; Wang, Xi-Ling

2017-03-06

To assess the effects of winter/summer school breaks on occurrences of influenza-like illness (ILI). We jointly analysed ILI surveillance data with the timing of school breaks in a temperate district in Beijing, China from 2008 to 2015. ILI incidence rate ratios (IRRs) of schoolchildren (5-14 and 15-24 years of age) to adults (25-59 and >60 years of age) were used to measure the age shift of ILI incidence before, during and after the 4-week winter/7-week summer breaks. Serfling-based Poisson regression model with adjustment for unmeasured confounders was built to further assess the effect of winter school breaks. ILI incidences were consistently lower during winter breaks than before winter breaks for all age groups. IRRs of younger schoolchildren aged 5-14 to adults were higher during winter school breaks than before breaks, while the opposite was true for the IRRs of older schoolchildren aged 15-24 to adults. Schoolchildren-to-adults IRRs during summer breaks were significantly lower than before or after school breaks (p<0.001). Both winter and summer breaks were associated with reductions of ILI incidences among schoolchildren and adults. Our study contributes additional evidence on the effects of school breaks on ILI incidence, suggesting school closure could be effective in controlling influenza transmission in developing countries. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Rolamite acceleration sensor

DOEpatents

Abbin, Joseph P.; Briner, Clifton F.; Martin, Samuel B.

1993-01-01

A rolamite acceleration sensor which has a failsafe feature including a housing, a pair of rollers, a tension band wrapped in an S shaped fashion around the rollers, wherein the band has a force-generation cut out and a failsafe cut out or weak portion. The failsafe cut out or weak portion breaks when the sensor is subjected to an excessive acceleration so that the sensor fails in an open circuit (non-conducting) state permanently.

Radioresistance of GGG Sequences to Prompt Strand Break Formation from Direct-Type Radiation Damage

PubMed Central

Black, Paul J.; Miller, Adam S.; Hayes, Jeffrey J.

2016-01-01

Purpose As humans, we are constantly exposed to ionizing radiation from natural, man-made and cosmic sources which can damage DNA, leading to deleterious effects including cancer incidence. In this work we introduce a method to monitor strand breaks resulting from damage due to the direct effect of ionizing radiation and provide evidence for sequence-dependent effects leading to strand breaks. Materials and methods To analyze only DNA strand breaks caused by radiation damage due to the direct effect of ionizing radiation, we combined an established technique to generate dehydrated DNA samples with a technique to analyze single strand breaks on short oligonucleotide sequences via denaturing gel electrophoresis. Results We find that direct damage primarily results in a reduced number of strand breaks in guanine triplet regions (GGG) when compared to isolated guanine (G) bases with identical flanking base context. In addition, we observe strand break behavior possibly indicative of protection of guanine bases when flanked by pyrimidines, and sensitization of guanine to strand break when flanked by adenine (A) bases in both isolated G and GGG cases. Conclusions These observations provide insight into the strand break behavior in GGG regions damaged via the direct effect of ionizing radiation. In addition, this could be indicative of DNA sequences that are naturally more susceptible to strand break due to the direct effect of ionizing radiation. PMID:27349757

Instability of superfluid Fermi gases induced by a rotonlike density mode in optical lattices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yunomae, Yoshihiro; Yamamoto, Daisuke; Danshita, Ippei

2009-12-15

We study the stability of superfluid Fermi gases in deep optical lattices in the BCS-Bose-Einstein condensation (BEC) crossover at zero temperature. Within the tight-binding attractive Hubbard model, we calculate the spectrum of the low-energy Anderson-Bogoliubov (AB) mode as well as the single-particle excitations in the presence of superfluid flow in order to determine the critical velocities. To obtain the spectrum of the AB mode, we calculate the density response function in the generalized random-phase approximation applying the Green's function formalism developed by Cote and Griffin to the Hubbard model. We find that the spectrum of the AB mode is separatedmore » from the particle-hole continuum having the characteristic rotonlike minimum at short wavelength due to the strong charge-density-wave fluctuations. The energy of the rotonlike minimum decreases with increasing the lattice velocity and it reaches zero at the critical velocity which is smaller than the pair-breaking velocity. This indicates that the superfluid state is energetically unstable due to the spontaneous emission of the short-wavelength rotonlike excitations of the AB mode instead due to pair breaking. We determine the critical velocities as functions of the interaction strength across the BCS-BEC crossover regime.« less

Detection of a Spectral Break in the Extra Hard Component of GRB 090926A

NASA Astrophysics Data System (ADS)

Ackermann, M.; Ajello, M.; Asano, K.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bhat, P. N.; Bissaldi, E.; Blandford, R. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Briggs, M. S.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Carrigan, S.; Casandjian, J. M.; Cecchi, C.; Çelik, Ö.; Chaplin, V.; Charles, E.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Connaughton, V.; Conrad, J.; Cutini, S.; Dermer, C. D.; de Angelis, A.; de Palma, F.; Dingus, B. L.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Goldstein, A.; Granot, J.; Greiner, J.; Grenier, I. A.; Grove, J. E.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashi, K.; Hayashida, M.; Hays, E.; Horan, D.; Hughes, R. E.; Itoh, R.; Jóhannesson, G.; Johnson, A. S.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kippen, R. M.; Knödlseder, J.; Kocevski, D.; Kouveliotou, C.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S.-H.; Llena Garde, M.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Makeev, A.; Mazziotta, M. N.; McBreen, S.; McEnery, J. E.; McGlynn, S.; Meegan, C.; Mehault, J.; Mészáros, P.; Michelson, P. F.; Mizuno, T.; Monte, C.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakajima, H.; Nakamori, T.; Naumann-Godo, M.; Nishino, S.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paciesas, W. S.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Petrosian, V.; Piron, F.; Porter, T. A.; Preece, R.; Racusin, J. L.; Rainò, S.; Rando, R.; Rau, A.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Reyes, L. C.; Ripken, J.; Ritz, S.; Roth, M.; Ryde, F.; Sadrozinski, H. F.-W.; Sander, A.; Scargle, J. D.; Schalk, T. L.; Sgrò, C.; Siskind, E. J.; Smith, P. D.; Spandre, G.; Spinelli, P.; Stamatikos, M.; Stecker, F. W.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Tanaka, T.; Tanaka, Y.; Thayer, J. B.; Thayer, J. G.; Tibaldo, L.; Tierney, D.; Toma, K.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Uehara, T.; Usher, T. L.; Vandenbroucke, J.; van der Horst, A. J.; Vasileiou, V.; Vilchez, N.; Vitale, V.; von Kienlin, A.; Waite, A. P.; Wang, P.; Wilson-Hodge, C.; Winer, B. L.; Wood, K. S.; Wu, X. F.; Yamazaki, R.; Yang, Z.; Ylinen, T.; Ziegler, M.

2011-03-01

We report on the observation of the bright, long gamma-ray burst, GRB 090926A, by the Gamma-ray Burst Monitor and Large Area Telescope (LAT) instruments on board the Fermi Gamma-ray Space Telescope. GRB 090926A shares several features with other bright LAT bursts. In particular, it clearly shows a short spike in the light curve that is present in all detectors that see the burst, and this in turn suggests that there is a common region of emission across the entire Fermi energy range. In addition, while a separate high-energy power-law component has already been observed in other gamma-ray bursts, here we report for the first time the detection with good significance of a high-energy spectral break (or cutoff) in this power-law component around 1.4 GeV in the time-integrated spectrum. If the spectral break is caused by opacity to electron-positron pair production within the source, then this observation allows us to compute the bulk Lorentz factor for the outflow, rather than a lower limit.

Detection of a spectral break in the extra hard component of GRB 090926A

DOE PAGES

Ackermann, M.; Ajello, M.; Asano, K.; ...

2011-02-16

Here, we report on the observation of the bright, long gamma-ray burst, GRB 090926A, by the Gamma-ray Burst Monitor and Large Area Telescope (LAT) instruments on board the Fermi Gamma-ray Space Telescope. GRB 090926A shares several features with other bright LAT bursts. In particular, it clearly shows a short spike in the light curve that is present in all detectors that see the burst, and this in turn suggests that there is a common region of emission across the entire Fermi energy range. In addition, while a separate high-energy power-law component has already been observed in other gamma-ray bursts, heremore » we report for the first time the detection with good significance of a high-energy spectral break (or cutoff) in this power-law component around 1.4 GeV in the time-integrated spectrum. If the spectral break is caused by opacity to electron-positron pair production within the source, then this observation allows us to compute the bulk Lorentz factor for the outflow, rather than a lower limit.« less

Polarization and Resummation in Slepton Production at Hadron Colliders

NASA Astrophysics Data System (ADS)

Klasen, M.

2006-10-01

In R-parity conserving supersymmetric (SUSY) models, sleptons are produced in pairs at hadron colliders through neutral and charged electroweak currents. We demonstrate that the polarization of the initial hadron beams allows for a direct extraction of the slepton mixing angle and thus for a determination of the underlying SUSY-breaking mechanism. We also perform a first precision calculation of the transverse-momentum ( q T) spectrum of the slepton pairs by resumming soft multiple-gluon emission at next-to-leading logarithmic order. The results show a relevant contribution of resummation both in the small and intermediate q T-regions, which strongly influences the extraction of the missing transverse-momentum signal and the subsequent slepton mass-determination, and little dependence on unphysical scales and non-perturbative contributions.

Gamma ray pulsars. [electron-photon cascades

NASA Technical Reports Server (NTRS)

Oegelman, H.; Ayasli, S.; Hacinliyan, A.

1977-01-01

Data from the SAS-2 high-energy gamma-ray experiment reveal the existence of four pulsars emitting photons above 35 MeV. An attempt is made to explain the gamma-ray emission from these pulsars in terms of an electron-photon cascade that develops in the magnetosphere of the pulsar. Although there is very little material above the surface of the pulsar, the very intense magnetic fields (10 to the 12th power gauss) correspond to many radiation lengths which cause electrons to emit photons by magnetic bremsstrahlung and which cause these photons to pair-produce. The cascade develops until the mean photon energy drops below the pair-production threshold which is in the gamma-ray range; at this stage, the photons break out from the source.

Dynamical generation of Floquet Majorana flat bands in s-wave superconductors

NASA Astrophysics Data System (ADS)

Poudel, A.; Ortiz, G.; Viola, L.

2015-04-01

We present quantum control techniques to engineer flat bands of symmetry-protected Majorana edge modes in s-wave superconductors. Specifically, we show how periodic control may be employed for designing time-independent effective Hamiltonians, which support Floquet Majorana flat bands, starting from equilibrium conditions that are either topologically trivial or only support a Majorana pair per edge. In the first approach, a suitable modulation of the chemical potential simultaneously induces Majorana flat bands and dynamically activates a pre-existing chiral symmetry which is responsible for their protection. In the second approach, the application of effective parity kicks dynamically generates a desired chiral symmetry by suppressing chirality-breaking terms in the static Hamiltonian. Our results demonstrate how the use of time-dependent control enlarges the range of possibilities for realizing gapless topological superconductivity, potentially enabling access to topological states of matter that have no known equilibrium counterpart.

The aminoglycoside antibiotic kanamycin damages DNA bases in Escherichia coli: caffeine potentiates the DNA-damaging effects of kanamycin while suppressing cell killing by ciprofloxacin in Escherichia coli and Bacillus anthracis.

PubMed

Kang, Tina Manzhu; Yuan, Jessica; Nguyen, Angelyn; Becket, Elinne; Yang, Hanjing; Miller, Jeffrey H

2012-06-01

The distribution of mutants in the Keio collection of Escherichia coli gene knockout mutants that display increased sensitivity to the aminoglycosides kanamycin and neomycin indicates that damaged bases resulting from antibiotic action can lead to cell death. Strains lacking one of a number of glycosylases (e.g., AlkA, YzaB, Ogt, KsgA) or other specific repair proteins (AlkB, PhrB, SmbC) are more sensitive to these antibiotics. Mutants lacking AlkB display the strongest sensitivity among the glycosylase- or direct lesion removal-deficient strains. This perhaps suggests the involvement of ethenoadenine adducts, resulting from reactive oxygen species and lipid peroxidation, since AlkB removes this lesion. Other sensitivities displayed by mutants lacking UvrA, polymerase V (Pol V), or components of double-strand break repair indicate that kanamycin results in damaged base pairs that need to be removed or replicated past in order to avoid double-strand breaks that saturate the cellular repair capacity. Caffeine enhances the sensitivities of these repair-deficient strains to kanamycin and neomycin. The gene knockout mutants that display increased sensitivity to caffeine (dnaQ, holC, holD, and priA knockout mutants) indicate that caffeine blocks DNA replication, ultimately leading to double-strand breaks that require recombinational repair by functions encoded by recA, recB, and recC, among others. Additionally, caffeine partially protects cells of both Escherichia coli and Bacillus anthracis from killing by the widely used fluoroquinolone antibiotic ciprofloxacin.

Heavy ion-induced DNA double-strand breaks in yeast.

PubMed

Kiefer, Jürgen; Egenolf, Ralf; Ikpeme, Samuel

2002-02-01

Induction of DSBs in the diploid yeast, Saccharomyces cerevisiae, was measured by pulsed-field gel electrophoresis (PFGE) after the cells had been exposed on membrane filters to a variety of energetic heavy ions with values of linear energy transfer (LET) ranging from about 2 to 11,500 keV/microm, (241)Am alpha particles, and 80 keV X rays. After irradiation, the cells were lysed, and the chromosomes were separated by PFGE. The gels were stained with ethidium bromide, placed on a UV transilluminator, and analyzed using a computer-coupled camera. The fluorescence intensities of the larger bands were found to decrease exponentially with dose or particle fluence. The slope of this line corresponds to the cross section for at least one double-strand break (DSB), but closely spaced multiple breaks cannot be discriminated. Based on the known size of the native DNA molecules, breakage cross sections per base pair were calculated. They increased with LET until they reached a transient plateau value of about 6 x 10(-7) microm(2) at about 300-2000 keV/microm; they then rose for the higher LETs, probably reflecting the influence of delta electrons. The relative biological effectiveness for DNA breakage displays a maximum of about 2.5 around 100-200 keV/microm and falls below unity for LET values above 10(3) keV/microm. For these yeast cells, comparison of the derived breakage cross sections with the corresponding cross section for inactivation derived from the terminal slope of the survival curves shows a strong linear relationship between these cross sections, extending over several orders of magnitude.

From Kondo lattices to Kondo superlattices

NASA Astrophysics Data System (ADS)

Shimozawa, Masaaki; Goh, Swee K.; Shibauchi, Takasada; Matsuda, Yuji

2016-07-01

The realization of new classes of ground states in strongly correlated electron systems continues to be a major issue in condensed matter physics. Heavy fermion materials, whose electronic structure is essentially three-dimensional, are one of the most suitable systems for obtaining novel electronic states because of their intriguing properties associated with many-body effects. Recently, a state-of-the-art molecular beam epitaxy technique was developed to reduce the dimensionality of heavy electron systems by fabricating artificial superlattices that include heavy fermion compounds; this approach can produce a new type of electronic state in two-dimensional (2D) heavy fermion systems. In artificial superlattices of the antiferromagnetic heavy fermion compound CeIn3 and the conventional metal LaIn3, the magnetic order is suppressed by a reduction in the thickness of the CeIn3 layers. In addition, the 2D confinement of heavy fermions leads to enhancement of the effective electron mass and deviation from the standard Fermi liquid electronic properties, which are both associated with the dimensional tuning of quantum criticality. In the superconducting superlattices of the heavy fermion superconductor CeCoIn5 and nonmagnetic metal YbCoIn5, signatures of superconductivity are observed even at the thickness of one unit-cell layer of CeCoIn5. The most remarkable feature of this 2D heavy fermion superconductor is that the thickness reduction of the CeCoIn5 layers changes the temperature and angular dependencies of the upper critical field significantly. This result is attributed to a substantial suppression of the Pauli pair-breaking effect through the local inversion symmetry breaking at the interfaces of CeCoIn5 block layers. The importance of the inversion symmetry breaking in this system has also been supported by site-selective nuclear magnetic resonance spectroscopy, which can resolve spectroscopic information from each layer separately, even within the same CeCoIn5 block layer. In addition, recent experiments involving CeCoIn5/YbCoIn5 superlattices have shown that the degree of the inversion symmetry breaking and, in turn, the Rashba splitting are controllable, offering the prospect of achieving even more fascinating superconducting states. Thus, these Kondo superlattices pave the way for the exploration of unconventional metallic and superconducting states.

Central region component1, a novel synaptonemal complex component, is essential for meiotic recombination initiation in rice.

PubMed

Miao, Chunbo; Tang, Ding; Zhang, Honggen; Wang, Mo; Li, Yafei; Tang, Shuzhu; Yu, Hengxiu; Gu, Minghong; Cheng, Zhukuan

2013-08-01

In meiosis, homologous recombination entails programmed DNA double-strand break (DSB) formation and synaptonemal complex (SC) assembly coupled with the DSB repair. Although SCs display extensive structural conservation among species, their components identified are poorly conserved at the sequence level. Here, we identified a novel SC component, designated central region component1 (CRC1), in rice (Oryza sativa). CRC1 colocalizes with ZEP1, the rice SC transverse filament protein, to the central region of SCs in a mutually dependent fashion. Consistent with this colocalization, CRC1 interacts with ZEP1 in yeast two-hybrid assays. CRC1 is orthologous to Saccharomyces cerevisiae pachytene checkpoint2 (Pch2) and Mus musculus THYROID receptor-interacting protein13 (TRIP13) and may be a conserved SC component. Additionally, we provide evidence that CRC1 is essential for meiotic DSB formation. CRC1 interacts with homologous pairing aberration in rice meiosis1 (PAIR1) in vitro, suggesting that these proteins act as a complex to promote DSB formation. PAIR2, the rice ortholog of budding yeast homolog pairing1, is required for homologous chromosome pairing. We found that CRC1 is also essential for the recruitment of PAIR2 onto meiotic chromosomes. The roles of CRC1 identified here have not been reported for Pch2 or TRIP13.

CENTRAL REGION COMPONENT1, a Novel Synaptonemal Complex Component, Is Essential for Meiotic Recombination Initiation in Rice[C][W

PubMed Central

Miao, Chunbo; Tang, Ding; Zhang, Honggen; Wang, Mo; Li, Yafei; Tang, Shuzhu; Yu, Hengxiu; Gu, Minghong; Cheng, Zhukuan

2013-01-01

In meiosis, homologous recombination entails programmed DNA double-strand break (DSB) formation and synaptonemal complex (SC) assembly coupled with the DSB repair. Although SCs display extensive structural conservation among species, their components identified are poorly conserved at the sequence level. Here, we identified a novel SC component, designated CENTRAL REGION COMPONENT1 (CRC1), in rice (Oryza sativa). CRC1 colocalizes with ZEP1, the rice SC transverse filament protein, to the central region of SCs in a mutually dependent fashion. Consistent with this colocalization, CRC1 interacts with ZEP1 in yeast two-hybrid assays. CRC1 is orthologous to Saccharomyces cerevisiae pachytene checkpoint2 (Pch2) and Mus musculus THYROID RECEPTOR-INTERACTING PROTEIN13 (TRIP13) and may be a conserved SC component. Additionally, we provide evidence that CRC1 is essential for meiotic DSB formation. CRC1 interacts with HOMOLOGOUS PAIRING ABERRATION IN RICE MEIOSIS1 (PAIR1) in vitro, suggesting that these proteins act as a complex to promote DSB formation. PAIR2, the rice ortholog of budding yeast homolog pairing1, is required for homologous chromosome pairing. We found that CRC1 is also essential for the recruitment of PAIR2 onto meiotic chromosomes. The roles of CRC1 identified here have not been reported for Pch2 or TRIP13. PMID:23943860

Intact or broken-apart RNA: an alternative concept for ALK fusion screening in non-small cell lung cancer (NSCLC).

PubMed

Kotoula, Vassiliki; Bobos, Mattheos; Vassilakopoulou, Maria; Tsolaki, Eleftheria; Chrisafi, Sofia; Psyrri, Amanda; Lazaridis, George; Papadopoulou, Kyriaki; Efstratiou, Ioannis; Michail-Strantzia, Catherine; Debelenko, Larisa V; Kosmidis, Paris; Fountzilas, George

2015-01-01

Anaplastic lymphoma kinase (ALK) break-apart fluorescent in situ hybridization (FISH) is currently used in diagnostics for the selection of non-small cell lung cancer (NSCLC) patients to receive crizotinib. We evaluated ALK status in NSCLC with a novel ALK mRNA test based on the break-apart FISH concept, which we called break-apart transcript (BAT) test. ALK5' and ALK3' transcript patterns were established with qPCR for ALK-expressing controls including fusion-negative neuroblastomas, as well as fusion-positive anaplastic large cell lymphomas and NSCLC. The BAT test was evaluated on 271 RNA samples from routinely processed paraffin NSCLC tissues. Test results were compared with ALK FISH (n=121), immunohistochemical (IHC) analysis (n=86), and automated quantitative analysis (AQUA, n=83). On the basis of the nonoverlapping ALK BAT patterns in ALK-expressing controls (P<0.0001), 8/174 adenocarcinomas (4.6%) among 259 informative NSCLC were predicted as fusion positive. Overall concordance for paired method results was high (94.1% to 98.8%) but mainly concerned negative prediction because of the limited availability of positive-matched cases. Tumors with 100% cytoplasmic IHC staining of any intensity (n=3) were positive for AQUA, FISH, and BAT test; tumors with lower IHC positivity and different staining patterns were AQUA-negative. Upon multiple reevaluations, ALK gene status was considered as originally misinterpreted by FISH in 3/121 cases (2.5%). Tumors with >4 ALK gene copies were associated with longer overall survival upon first-line chemotherapy. In conclusion, application of the ALK BAT test on routinely processed NSCLC tissues yields the same fusion partner independent information as ALK break-apart FISH but is more robust and cost-effective. The BAT concept may be considered for the development of further drug-predictive translocation tests.

Repair of exogenous DNA double-strand breaks promotes chromosome synapsis in SPO11-mutant mouse meiocytes, and is altered in the absence of HORMAD1.

PubMed

Carofiglio, Fabrizia; Sleddens-Linkels, Esther; Wassenaar, Evelyne; Inagaki, Akiko; van Cappellen, Wiggert A; Grootegoed, J Anton; Toth, Attila; Baarends, Willy M

2018-03-01

Repair of SPO11-dependent DNA double-strand breaks (DSBs) via homologous recombination (HR) is essential for stable homologous chromosome pairing and synapsis during meiotic prophase. Here, we induced radiation-induced DSBs to study meiotic recombination and homologous chromosome pairing in mouse meiocytes in the absence of SPO11 activity (Spo11 YF/YF model), and in the absence of both SPO11 and HORMAD1 (Spo11/Hormad1 dko). Within 30 min after 5 Gy irradiation of Spo11 YF/YF mice, 140-160 DSB repair foci were detected, which specifically localized to the synaptonemal complex axes. Repair of radiation-induced DSBs was incomplete in Spo11 YF/YF compared to Spo11 +/YF meiocytes. Still, repair of exogenous DSBs promoted partial recovery of chromosome pairing and synapsis in Spo11 YF/YF meiocytes. This indicates that at least part of the exogenous DSBs can be processed in an interhomolog recombination repair pathway. Interestingly, in a seperate experiment, using 3 Gy of irradiation, we observed that Spo11/Hormad1 dko spermatocytes contained fewer remaining DSB repair foci at 48 h after irradiation compared to irradiated Spo11 knockout spermatocytes. Together, these results show that recruitment of exogenous DSBs to the synaptonemal complex, in conjunction with repair of exogenous DSBs via the homologous chromosome, contributes to homology recognition. In addition, the data suggest a role for HORMAD1 in DNA repair pathway choice in mouse meiocytes. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Rolamite acceleration sensor

DOEpatents

Abbin, J.P.; Briner, C.F.; Martin, S.B.

1993-12-21

A rolamite acceleration sensor is described which has a failsafe feature including a housing, a pair of rollers, a tension band wrapped in an S shaped fashion around the rollers, wherein the band has a force-generation cut out and a failsafe cut out or weak portion. The failsafe cut out or weak portion breaks when the sensor is subjected to an excessive acceleration so that the sensor fails in an open circuit (non-conducting) state permanently. 6 figures.

Search for direct top squark pair production in events with a $Z$ boson, $b$-jets and missing transverse momentum in $$\\sqrt{s}$$= 8 TeV $pp$ collisions with the ATLAS detector

DOE PAGES

Aad, G.; Abbott, B.; Abdallah, J.; ...

2014-06-01

Here, a search is presented for direct top squark pair production using events with at least two leptons including a same-flavour opposite-sign pair with invariant mass consistent with the Z boson mass, jets tagged as originating from b-quarks and missing transverse momentum. The analysis is performed with proton–proton collision data at √s = 8 TeV collected with the ATLAS detector at the LHC in 2012 corresponding to an integrated luminosity of 20.3 fb -1. No excess beyond the Standard Model expectation is observed. Interpretations of the results are provided in models based on the direct pair production of the heavier top squark state (more » $$\\sim\\atop{t}_2$$) followed by the decay to the lighter top squark state ($$\\sim\\atop{t}_1$$) via $$\\sim\\atop{t}_2$$ → Z$$\\sim\\atop{t}_1$$, and for $$\\sim\\atop{t}_1$$ pair production in natural gauge-mediated supersymmetry breaking scenarios where the neutralino ($$\\sim\\atop{χ}$$$0\\atop{1}$$) is the next-to-lightest supersymmetric particle and decays producing a Z boson and a gravitino ($$\\sim\\atop{G}$$) via the $$\\sim\\atop{χ}$$$0\\atop{1}$$ → Z G process.« less

Breaking the Ice

NASA Technical Reports Server (NTRS)

1989-01-01

Electro-Expulsive Separation System, a low power electro-thermal deicer, was invented by Leonard A. Haslim from the Ames Research Center, who was named 1988 NASA Inventor of the Year for his work. Sold under license by Dataproducts New England, Inc., it consists of an elastic, rubber-like deicer boot on the wing's leading edge with copper ribbons embedded in it. Conductors are separated by slits in between and parallel to the ribbons. When the system is switched on, a bank of capacitors in the power supply discharges into the conductors which induces the conductor pairs to repel each other. This results in a powerful force causing the slit voids to expand explosively, removing ice on the wing. EESS is more flexible, more effective, and easier to maintain than previous systems. Potential ship, bridge and industrial applications are under study.

Search for Zγ events with large missing transverse energy in pp̄ collisions at √s=1.96 TeV

DOE PAGES

Abazov, V. M.; Abbott, B.; Acharya, B. S.; ...

2012-10-02

We present the first search for new phenomena in Zγ final states with large missing transverse energy using data corresponding to an integrated luminosity of 6.2 fb⁻¹ collected with the D0 experiment in pp̄ collisions at √s=1.96 TeV. This signature is predicted in gauge-mediated supersymmetry-breaking models, where the lightest neutralino χ˜⁰₁ is the next-to-lightest supersymmetric particle and is produced in pairs, possibly through decay from heavier supersymmetric particles. The χ˜⁰₁ can decay either to a Z boson or a photon and an associated gravitino that escapes detection. We exclude this model at the 95% C.L. for supersymmetry-breaking scales of Λ<87more » TeV.« less

Development of the Advanced Energetic Pair Telescope (AdEPT) for Medium-Energy Gamma-Ray Astronomy

NASA Technical Reports Server (NTRS)

Hunter, Stanley D.; Bloser, Peter F.; Dion, Michael P.; McConnell, Mark L.; deNolfo, Georgia A.; Son, Seunghee; Ryan, James M.; Stecker, Floyd W.

2011-01-01

Progress in high-energy gamma-ray science has been dramatic since the launch of INTEGRAL, AGILE and FERMI. These instruments, however, are not optimized for observations in the medium-energy (approx.0.3< E(sub gamma)< approx.200 MeV) regime where many astrophysical objects exhibit unique, transitory behavior, such as spectral breaks, bursts, and flares. We outline some of the major science goals of a medium-energy mission. These science goals are best achieved with a combination of two telescopes, a Compton telescope and a pair telescope, optimized to provide significant improvements in angular resolution and sensitivity. In this paper we describe the design of the Advanced Energetic Pair Telescope (AdEPT) based on the Three-Dimensional Track Imager (3-DTI) detector. This technology achieves excellent, medium-energy sensitivity, angular resolution near the kinematic limit, and gamma-ray polarization sensitivity, by high resolution 3-D electron tracking. We describe the performance of a 30x30x30 cm3 prototype of the AdEPT instrument.

Boosting Higgs pair production in the [Formula: see text] final state with multivariate techniques.

PubMed

Behr, J Katharina; Bortoletto, Daniela; Frost, James A; Hartland, Nathan P; Issever, Cigdem; Rojo, Juan

2016-01-01

The measurement of Higgs pair production will be a cornerstone of the LHC program in the coming years. Double Higgs production provides a crucial window upon the mechanism of electroweak symmetry breaking and has a unique sensitivity to the Higgs trilinear coupling. We study the feasibility of a measurement of Higgs pair production in the [Formula: see text] final state at the LHC. Our analysis is based on a combination of traditional cut-based methods with state-of-the-art multivariate techniques. We account for all relevant backgrounds, including the contributions from light and charm jet mis-identification, which are ultimately comparable in size to the irreducible 4 b QCD background. We demonstrate the robustness of our analysis strategy in a high pileup environment. For an integrated luminosity of [Formula: see text] ab[Formula: see text], a signal significance of [Formula: see text] is obtained, indicating that the [Formula: see text] final state alone could allow for the observation of double Higgs production at the High Luminosity LHC.

A compartmentalized signaling network mediates crossover control in meiosis

PubMed Central

Zhang, Liangyu; Köhler, Simone; Rillo-Bohn, Regina

2018-01-01

During meiosis, each pair of homologous chromosomes typically undergoes at least one crossover (crossover assurance), but these exchanges are strictly limited in number and widely spaced along chromosomes (crossover interference). The molecular basis for this chromosome-wide regulation remains mysterious. A family of meiotic RING finger proteins has been implicated in crossover regulation across eukaryotes. Caenorhabditis elegans expresses four such proteins, of which one (ZHP-3) is known to be required for crossovers. Here we investigate the functions of ZHP-1, ZHP-2, and ZHP-4. We find that all four ZHP proteins, like their homologs in other species, localize to the synaptonemal complex, an unusual, liquid crystalline compartment that assembles between paired homologs. Together they promote accumulation of pro-crossover factors, including ZHP-3 and ZHP-4, at a single recombination intermediate, thereby patterning exchanges along paired chromosomes. These proteins also act at the top of a hierarchical, symmetry-breaking process that enables crossovers to direct accurate chromosome segregation. PMID:29521627

Self-Attractive Hartree Decomposition: Partitioning Electron Density into Smooth Localized Fragments.

PubMed

Zhu, Tianyu; de Silva, Piotr; Van Voorhis, Troy

2018-01-09

Chemical bonding plays a central role in the description and understanding of chemistry. Many methods have been proposed to extract information about bonding from quantum chemical calculations, the majority of them resorting to molecular orbitals as basic descriptors. Here, we present a method called self-attractive Hartree (SAH) decomposition to unravel pairs of electrons directly from the electron density, which unlike molecular orbitals is a well-defined observable that can be accessed experimentally. The key idea is to partition the density into a sum of one-electron fragments that simultaneously maximize the self-repulsion and maintain regular shapes. This leads to a set of rather unusual equations in which every electron experiences self-attractive Hartree potential in addition to an external potential common for all the electrons. The resulting symmetry breaking and localization are surprisingly consistent with chemical intuition. SAH decomposition is also shown to be effective in visualization of single/multiple bonds, lone pairs, and unusual bonds due to the smooth nature of fragment densities. Furthermore, we demonstrate that it can be used to identify specific chemical bonds in molecular complexes and provides a simple and accurate electrostatic model of hydrogen bonding.

Squeezed states and graviton-entropy production in the early universe

NASA Technical Reports Server (NTRS)

Giovannini, Massimo

1994-01-01

Squeezed states are a very useful framework for the quantum treatment of tensor perturbations (i.e. gravitons production) in the early universe. In particular, the non equilibrium entropy growth in a cosmological process of pair production is completely determined by the associated squeezing parameter and is insensitive to the number of particles in the initial state. The total produced entropy may represent a significant fraction of the entropy stored today in the cosmic blackbody radiation, provided pair production originates from a change in the background metric at a curvature scale of the Planck order. Within the formalism of squeezed thermal states it is also possible to discuss the stimulated emission of gravitons from an initial thermal bath, under the action of the cosmic gravitational background field. We find that at low energy the graviton production is enhanced, if compared with spontaneous creation from the vacuum; as a consequence, the inflation scale must be lowered, in order not to exceed the observed CMB quadrupole anisotropy. This effect is important, in particular, for models based on a symmetry-breaking transition which require, as initial condition, a state of thermal equilibrium at temperatures higher than the inflation scale and in which inflation has a minimal duration.

Blind readers break mirror invariance as sighted do.

PubMed

de Heering, Adélaïde; Collignon, Olivier; Kolinsky, Régine

2018-04-01

Mirror invariance refers to a predisposition of humans, including infants and animals, which urge them to consider mirrored images as corresponding to the same object. Yet in order to learn to read a written system that incorporates mirrored letters (e.g., vs. in the Latin alphabet), humans learn to break this perceptual bias. Here we examined the role visual experience and input modality play in the emergence of this bias. To this end, we tested congenital blind (CB) participants in two same-different tactile comparison tasks including pairs of mirrored and non-mirrored Braille letters as well as embossed unfamiliar geometric shapes and Latin letters, and compared their results to those of age-matched sighted participants involved in similar but visually-presented tasks. Sighted participants showed a classical pattern of results for their material of expertise, Latin letters. CB's results signed for their expertise with the Braille script compared to the other two materials that they processed according to an internal frame of reference. They also evidenced that they automatically break mirror invariance for different materials explored through the tactile modality, including Braille letters. Altogether, these results demonstrate that learning to read Braille through the tactile modality allows breaking mirror invariance in a comparable way to what is observed in sighted individuals for the mirrored letters of the Latin alphabet. Copyright © 2018 Elsevier Ltd. All rights reserved.

Proximity within interphase chromosome contributes to the breakpoint distribution in radiation-induced intrachromosomal exchanges

NASA Astrophysics Data System (ADS)

Zhang, Ye; Uhlemeyer, Jimmy; Hada, Megumi; Asaithamby, A.; Chen, David J.; Wu, Honglu

2014-07-01

Previously, we reported that breaks involved in chromosome aberrations were clustered in several regions of chromosome 3 in human mammary epithelial cells after exposures to either low- or high-LET radiation. In particular, breaks in certain regions of the chromosome tended to rejoin with each other to form an intrachromosome exchange event. This study tests the hypothesis that proximity within a single chromosome in interphase cell nuclei contributes to the distribution of radiation-induced chromosome breaks. Chromosome 3 in G1 human mammary epithelial cells was hybridized with the multicolor banding in situ hybridization (mBAND) probes that distinguish the chromosome in six differently colored regions, and the location of these regions was measured with a laser confocal microscope. Results of the study indicated that, on a multi-mega base pair scale of the DNA, the arrangement of chromatin was non-random. Both telomere regions tended to be located towards the exterior of the chromosome domain, whereas the centromere region towards the interior. In addition, the interior of the chromosome domain was preferentially occupied by the p-arm of the chromatin, which is consistent with our previous finding of intrachromosome exchanges involving breaks on the p-arm and in the centromere region of chromosome 3. Other factors, such as the fragile sites in the 3p21 band and gene regulation, may also contribute to the breakpoint distribution in radiation-induced chromosome aberrations.

Determination of the Proper Rest Time for a Cyclic Mental Task Using ACT-R Architecture.

PubMed

Atashfeshan, Nooshin; Razavi, Hamideh

2017-03-01

Objective Analysis of the effect of mental fatigue on a cognitive task and determination of the right start time for rest breaks in work environments. Background Mental fatigue has been recognized as one of the most important factors influencing individual performance. Subjective and physiological measures are popular methods for analyzing fatigue, but they are restricted to physical experiments. Computational cognitive models are useful for predicting operator performance and can be used for analyzing fatigue in the design phase, particularly in industrial operations and inspections where cognitive tasks are frequent and the effects of mental fatigue are crucial. Method A cyclic mental task is modeled by the ACT-R architecture, and the effect of mental fatigue on response time and error rate is studied. The task includes visual inspections in a production line or control workstation where an operator has to check products' conformity to specifications. Initially, simulated and experimental results are compared using correlation coefficients and paired t test statistics. After validation of the model, the effects are studied by human and simulated results, which are obtained by running 50-minute tests. Results It is revealed that during the last 20 minutes of the tests, the response time increased by 20%, and during the last 12.5 minutes, the error rate increased by 7% on average. Conclusion The proper start time for the rest period can be identified by setting a limit on the error rate or response time. Application The proposed model can be applied early in production planning to decrease the negative effects of mental fatigue by predicting the operator performance. It can also be used for determining the rest breaks in the design phase without an operator in the loop.

Stability and tunneling dynamics of a dark-bright soliton pair in a harmonic trap

DOE PAGES

Karamatskos, E. T.; Stockhofe, J.; Kevrekidis, P. G.; ...

2015-04-30

In this study, we consider a binary repulsive Bose-Einstein condensate in a harmonic trap in one spatial dimension and investigate particular solutions consisting of two dark-bright solitons. There are two different stationary solutions characterized by the phase difference in the bright component, in-phase and out-of-phase states. We show that above a critical particle number in the bright component, a symmetry-breaking bifurcation of the pitchfork type occurs that leads to a new asymmetric solution whereas the parental branch, i.e., the out-of-phase state, becomes unstable. These three different states support different small amplitude oscillations, characterized by an almost stationary density of themore » dark component and a tunneling of the bright component between the two dark solitons. Within a suitable effective double-well picture, these can be understood as the characteristic features of a bosonic Josephson junction (BJJ), and we show within a two-mode approach that all characteristic features of the BJJ phase space are recovered. For larger deviations from the stationary states, the simplifying double-well description breaks down due to the feedback of the bright component onto the dark one, causing the solitons to move. In this regime we observe intricate anharmonic and aperiodic dynamics, exhibiting remnants of the BJJ phase space.« less

Differential Effects of Music and Video Gaming During Breaks on Auditory and Visual Learning.

PubMed

Liu, Shuyan; Kuschpel, Maxim S; Schad, Daniel J; Heinz, Andreas; Rapp, Michael A

2015-11-01

The interruption of learning processes by breaks filled with diverse activities is common in everyday life. This study investigated the effects of active computer gaming and passive relaxation (rest and music) breaks on auditory versus visual memory performance. Young adults were exposed to breaks involving (a) open eyes resting, (b) listening to music, and (c) playing a video game, immediately after memorizing auditory versus visual stimuli. To assess learning performance, words were recalled directly after the break (an 8:30 minute delay) and were recalled and recognized again after 7 days. Based on linear mixed-effects modeling, it was found that playing the Angry Birds video game during a short learning break impaired long-term retrieval in auditory learning but enhanced long-term retrieval in visual learning compared with the music and rest conditions. These differential effects of video games on visual versus auditory learning suggest specific interference of common break activities on learning.

Collider tests of the Renormalizable Coloron Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bai, Yang; Dobrescu, Bogdan A.

The coloron, a massive version of the gluon present in gauge extensions of QCD, has been searched for at the LHC as a dijet or top quark pair resonance. We point out that in the Renormalizable Coloron Model (ReCoM) with a minimal field content to break the gauge symmetry, a color-octet scalar and a singlet scalar are naturally lighter than the coloron because they are pseudo Nambu-Goldstone bosons. Consequently, the coloron may predominantly decay into scalar pairs, leading to novel signatures at the LHC. When the color-octet scalar is lighter than the singlet, or when the singlet mass is above roughly 1 TeV, the signatures consist of multi-jet resonances of multiplicity up to 12, including topologies with multi-prong jet substructure, slightly displaced vertices, and sometimes a top quark pair. When the singlet is the lightest ReCoM boson and lighter than about 1 TeV, its main decays (more » $W^+W^-$, $$\\gamma Z$$, $ZZ$) arise at three loops. The LHC signatures then involve two or four boosted electroweak bosons, often originating from highly displaced vertices, plus one or two pairs of prompt jets or top quarks.« less

Higgs boson decays to neutralinos in low-scale gauge mediation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mason, John D.; Poland, David; Morrissey, David E.

2009-12-01

We study the decays of a standard model-like minimal supersymmetric standard model Higgs boson to pairs of neutralinos, each of which subsequently decays promptly to a photon and a gravitino. Such decays can arise in supersymmetric scenarios where supersymmetry breaking is mediated to us by gauge interactions with a relatively light gauge messenger sector (M{sub mess} < or approx. 100 TeV). This process gives rise to a collider signal consisting of a pair of photons and missing energy. In the present work we investigate the bounds on this scenario within the minimal supersymmetric standard model from existing collider data. Wemore » also study the prospects for discovering the Higgs boson through this decay mode with upcoming data from the Tevatron and the LHC.« less

Galaxy bachelors, couples, spouses: Star formation in interacting galaxies

NASA Astrophysics Data System (ADS)

Sun, Jing; Barger, Kathleen; Richstein, Hannah; SDSS-IV/MaNGA

2017-01-01

We investigate the star formation activity in three galaxy systems in different stages of interaction to determine how the environment of galaxies affects their star forming ability and potential. These systems include an isolated galaxy, a pair of interacting galaxies, and a pair of merging galaxies. All of the target galaxies in these systems have similar stellar masses and similar radii and are at similar redshifts. We trace the star formation activity over the past 1-2 Gyr using spatially and kinematically resolved H-alpha emission, H-alpha equivalent width, and 4000-Angstrom break maps. This work is based on data from the fourth-generation Sloan Digital Sky Survey (SDSS-IV)/Mapping Nearby Galaxies at Apache Point Observatory (MaNGA), and is part of the Project No.0285 in SDSS-IV.

Mechanical model for a collagen fibril pair in extracellular matrix.

PubMed

Chan, Yue; Cox, Grant M; Haverkamp, Richard G; Hill, James M

2009-04-01

In this paper, we model the mechanics of a collagen pair in the connective tissue extracellular matrix that exists in abundance throughout animals, including the human body. This connective tissue comprises repeated units of two main structures, namely collagens as well as axial, parallel and regular anionic glycosaminoglycan between collagens. The collagen fibril can be modeled by Hooke's law whereas anionic glycosaminoglycan behaves more like a rubber-band rod and as such can be better modeled by the worm-like chain model. While both computer simulations and continuum mechanics models have been investigated for the behavior of this connective tissue typically, authors either assume a simple form of the molecular potential energy or entirely ignore the microscopic structure of the connective tissue. Here, we apply basic physical methodologies and simple applied mathematical modeling techniques to describe the collagen pair quantitatively. We found that the growth of fibrils was intimately related to the maximum length of the anionic glycosaminoglycan and the relative displacement of two adjacent fibrils, which in return was closely related to the effectiveness of anionic glycosaminoglycan in transmitting forces between fibrils. These reveal the importance of the anionic glycosaminoglycan in maintaining the structural shape of the connective tissue extracellular matrix and eventually the shape modulus of human tissues. We also found that some macroscopic properties, like the maximum molecular energy and the breaking fraction of the collagen, were also related to the microscopic characteristics of the anionic glycosaminoglycan.

Non-random distribution of DNA double-strand breaks induced by particle irradiation

NASA Technical Reports Server (NTRS)

Lobrich, M.; Cooper, P. K.; Rydberg, B.; Chatterjee, A. (Principal Investigator)

1996-01-01

Induction of DNA double-strand breaks (dsbs) in mammalian cells is dependent on the spatial distribution of energy deposition from the ionizing radiation. For high LET particle radiations the primary ionization sites occur in a correlated manner along the track of the particles, while for X-rays these sites are much more randomly distributed throughout the volume of the cell. It can therefore be expected that the distribution of dsbs linearly along the DNA molecule also varies with the type of radiation and the ionization density. Using pulsed-field gel and conventional gel techniques, we measured the size distribution of DNA molecules from irradiated human fibroblasts in the total range of 0.1 kbp-10 Mbp for X-rays and high LET particles (N ions, 97 keV/microns and Fe ions, 150 keV/microns). On a mega base pair scale we applied conventional pulsed-field gel electrophoresis techniques such as measurement of the fraction of DNA released from the well (FAR) and measurement of breakage within a specific NotI restriction fragment (hybridization assay). The induction rate for widely spaced breaks was found to decrease with LET. However, when the entire distribution of radiation-induced fragments was analysed, we detected an excess of fragments with sizes below about 200 kbp for the particles compared with X-irradiation. X-rays are thus more effective than high LET radiations in producing large DNA fragments but less effective in the production of smaller fragments. We determined the total induction rate of dsbs for the three radiations based on a quantitative analysis of all the measured radiation-induced fragments and found that the high LET particles were more efficient than X-rays at inducing dsbs, indicating an increasing total efficiency with LET. Conventional assays that are based only on the measurement of large fragments are therefore misleading when determining total dsb induction rates of high LET particles. The possible biological significance of this non-randomness for dsb induction is discussed.

A significant role of non-thermal equilibrated electrons in the formation of deleterious complex DNA damage.

PubMed

Kai, Takeshi; Yokoya, Akinari; Ukai, Masatoshi; Fujii, Kentaro; Toigawa, Tomohiro; Watanabe, Ritsuko

2018-01-24

Although most of the radiation damage to genomic DNA could be rendered harmless using repair enzymes in a living cell, a certain fraction of the damage is persistent resulting in serious genetic effects, such as mutation induction. In order to understand the mechanisms of the deleterious DNA damage formation in terms of its earliest physical stage at the radiation track end, dynamics of low energy electrons and their thermalization processes around DNA molecules were investigated using a dynamic Monte Carlo code. The primary incident (1 keV) electrons multiply collide within 1 nm (equivalent to three DNA-base-pairs, 3bp) and generate secondary electrons which show non-Gaussian and non-thermal equilibrium distributions within 300 fs. On the other hand, the secondary electrons are mainly distributed within approximately 10 nm from their parent cations although approximately 5% of the electrons are localized within 1 nm of the cations owing to the interaction of their Coulombic fields. The mean electron energy is 0.7 eV; however, more than 10% of the electrons fall into a much lower-energy region than 0.1 eV at 300 fs. These results indicate that pre-hydrated electrons are formed from the extremely decelerated electrons over a few nm from the cations. DNA damage sites comprising multiple nucleobase lesions or single strand breaks can therefore be formed by multiple collisions of these electrons within 3bp. This multiple damage site is hardly processed by base excision repair enzymes. However, pre-hydrated electrons can also be produced resulting in an additional base lesion (or a strand break) more than 3bp away from the multi-damage site. These damage sites may be finally converted into a double strand break (DSB) when base excision enzymes process the additional base lesions. This DSB includes another base lesion(s) at their termini, and may introduce miss-rejoining by DSB repair enzymes, and hence may result in biological effects such as mutation in surviving cells.

Multiple roles for Saccharomyces cerevisiae histone H2A in telomere position effect, Spt phenotypes and double-strand-break repair.

PubMed Central

Wyatt, Holly R; Liaw, Hungjiun; Green, George R; Lustig, Arthur J

2003-01-01

Telomere position effects on transcription (TPE, or telomeric silencing) are nucleated by association of nonhistone silencing factors with the telomere and propagated in subtelomeric regions through association of silencing factors with the specifically modified histones H3 and H4. However, the function of histone H2A in TPE is unknown. We found that deletion of either the amino or the carboxyltails of H2A substantially reduces TPE. We identified four H2A modification sites necessary for wild-type efficiency of TPE. These "hta1tpe" alleles also act as suppressors of a delta insertion allele of LYS2, suggesting shared elements of chromatin structure at both loci. Interestingly, we observed combinatorial effects of allele pairs, suggesting both interdependent acetylation and deacetylation events in the amino-terminal tail and a regulatory circuit between multiple phosphorylated residues in the carboxyl-terminal tail. Decreases in silencing and viability are observed in most hta1tpe alleles after treatment with low and high concentrations, respectively, of bleomycin, which forms double-strand breaks (DSBs). In the absence of the DSB and telomere-binding protein yKu70, the bleomycin sensitivity of hta1tpe alleles is further enhanced. We also provide data suggesting the presence of a yKu-dependent histone H2A function in TPE. These data indicate that the amino- and carboxyl-terminal tails of H2A are essential for wild-type levels of yKu-mediated TPE and DSB repair. PMID:12750320

Optomechanically induced spontaneous symmetry breaking

NASA Astrophysics Data System (ADS)

Miri, Mohammad-Ali; Verhagen, Ewold; Alú, Andrea

2017-05-01

We explore the dynamics of spontaneous breakdown of mirror symmetry in a pair of identical optomechanical cavities symmetrically coupled to a waveguide. Large optical intensities enable optomechanically induced nonlinear detuning of the optical resonators, resulting in a pitchfork bifurcation. We investigate the stability of this regime and explore the possibility of inducing multistability. By injecting proper trigger pulses, the proposed structure can toggle between two asymmetric stable states, thus serving as a low-noise nanophotonic all-optical switch or memory element.

Storage-based Intrusion Detection: Watching storage activity for suspicious behavior

DTIC Science & Technology

2002-10-01

password management involves a pair of inter-related files (/etc/ passwd and /etc/shadow). The corresponding access pat- terns seen at the storage...example, consider a UNIX system password file (/etc/ passwd ), which con- sists of a set of well-defined records. Records are delimited by a line-break, and...etc/ passwd and verify that they conform to a set of basic integrity rules: 7-field records, non-empty password field, legal default shell, legal home

Din7 and Mhr1 expression levels regulate double-strand-break-induced replication and recombination of mtDNA at ori5 in yeast.

PubMed

Ling, Feng; Hori, Akiko; Yoshitani, Ayako; Niu, Rong; Yoshida, Minoru; Shibata, Takehiko

2013-06-01

The Ntg1 and Mhr1 proteins initiate rolling-circle mitochondrial (mt) DNA replication to achieve homoplasmy, and they also induce homologous recombination to maintain mitochondrial genome integrity. Although replication and recombination profoundly influence mitochondrial inheritance, the regulatory mechanisms that determine the choice between these pathways remain unknown. In Saccharomyces cerevisiae, double-strand breaks (DSBs) introduced by Ntg1 at the mitochondrial replication origin ori5 induce homologous DNA pairing by Mhr1, and reactive oxygen species (ROS) enhance production of DSBs. Here, we show that a mitochondrial nuclease encoded by the nuclear gene DIN7 (DNA damage inducible gene) has 5'-exodeoxyribonuclease activity. Using a small ρ(-) mtDNA bearing ori5 (hypersuppressive; HS) as a model mtDNA, we revealed that DIN7 is required for ROS-enhanced mtDNA replication and recombination that are both induced at ori5. Din7 overproduction enhanced Mhr1-dependent mtDNA replication and increased the number of residual DSBs at ori5 in HS-ρ(-) cells and increased deletion mutagenesis at the ori5 region in ρ(+) cells. However, simultaneous overproduction of Mhr1 suppressed all of these phenotypes and enhanced homologous recombination. Our results suggest that after homologous pairing, the relative activity levels of Din7 and Mhr1 modulate the preference for replication versus homologous recombination to repair DSBs at ori5.

Unified phonon-based approach to the thermodynamics of solid, liquid and gas states

NASA Astrophysics Data System (ADS)

Bolmatov, Dima; Zav'yalov, Dmitry; Zhernenkov, Mikhail; Musaev, Edvard T.; Cai, Yong Q.

2015-12-01

We introduce a unified approach to states of matter (solid, liquid and gas) and describe the thermodynamics of the pressure-temperature phase diagram in terms of phonon excitations. We derive the effective Hamiltonian with low-energy cutoff in two transverse phonon polarizations (phononic band gaps) by breaking the symmetry in phonon interactions. Further, we construct the statistical mechanics of states of aggregation employing the Debye approximation. The introduced formalism covers the Debye theory of solids, the phonon theory of liquids, and thermodynamic limits such as the Dulong-Petit thermodynamic limit (cV = 3kB), the ideal gas limit (cV =3/2 kB) and the new thermodynamic limit (cV = 2kB), dubbed here the Frenkel line thermodynamic limit. We discuss the phonon propagation and localization effects in liquids above and below the Frenkel line, and explain the "fast sound" phenomenon. As a test for our theory we calculate velocity-velocity autocorrelation and pair distribution functions within the Green-Kubo formalism. We show the consistency between dynamics of phonons and pair correlations in the framework of the unified approach. New directions towards advancements in phononic band gaps engineering, hypersound manipulation technologies and exploration of exotic behaviour of fluids relevant to geo- and planetary sciences are discussed. The presented results are equally important both for practical implications and for fundamental research.

(Non-adiabatic) string creation on nice slices in Schwarzschild black holes

NASA Astrophysics Data System (ADS)

Puhm, Andrea; Rojas, Francisco; Ugajin, Tomonori

2017-04-01

Nice slices have played a pivotal role in the discussion of the black hole information paradox as they avoid regions of strong spacetime curvature and yet smoothly cut through the infalling matter and the outgoing Hawking radiation, thus, justifying the use of low energy field theory. To avoid information loss it has been argued recently, however, that local effective field theory has to break down at the horizon. To assess the extent of this breakdown in a UV complete framework we study string-theoretic effects on nice slices in Schwarzschild black holes. Our purpose is two-fold. First, we use nice slices to address various open questions and caveats of [1] where it was argued that boost-enhanced non-adiabatic string-theoretic effects at the horizon could provide a dynamical mechanism for the firewall. Second, we identify two non-adiabatic effects on nice slices in Schwarzschild black holes: pair production of open strings near the horizon enhanced by the presence of the infinite tower of highly excited string states and a late-time non-adiabatic effect intrinsic to nice slices.

(Non-adiabatic) string creation on nice slices in Schwarzschild black holes

DOE PAGES

Puhm, Andrea; Rojas, Francisco; Ugajin, Tomonori

2017-04-27

Nice slices have played a pivotal role in the discussion of the black hole information paradox as they avoid regions of strong spacetime curvature and yet smoothly cut through the infalling matter and the outgoing Hawking radiation, thus, justifying the use of low energy field theory. To avoid information loss it has been argued recently, however, that local effective field theory has to break down at the horizon. To assess the extent of this breakdown in a UV complete framework we study string-theoretic effects on nice slices in Schwarzschild black holes. Here, our purpose is two-fold. First, we use nicemore » slices to address various open questions and caveats of [1] where it was argued that boost-enhanced non-adiabatic string-theoretic effects at the horizon could provide a dynamical mechanism for the firewall. Second, we identify two non-adiabatic effects on nice slices in Schwarzschild black holes: pair production of open strings near the horizon enhanced by the presence of the infinite tower of highly excited string states and a late-time non-adiabatic effect intrinsic to nice slices.« less

(Non-adiabatic) string creation on nice slices in Schwarzschild black holes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Puhm, Andrea; Rojas, Francisco; Ugajin, Tomonori

Nice slices have played a pivotal role in the discussion of the black hole information paradox as they avoid regions of strong spacetime curvature and yet smoothly cut through the infalling matter and the outgoing Hawking radiation, thus, justifying the use of low energy field theory. To avoid information loss it has been argued recently, however, that local effective field theory has to break down at the horizon. To assess the extent of this breakdown in a UV complete framework we study string-theoretic effects on nice slices in Schwarzschild black holes. Here, our purpose is two-fold. First, we use nicemore » slices to address various open questions and caveats of [1] where it was argued that boost-enhanced non-adiabatic string-theoretic effects at the horizon could provide a dynamical mechanism for the firewall. Second, we identify two non-adiabatic effects on nice slices in Schwarzschild black holes: pair production of open strings near the horizon enhanced by the presence of the infinite tower of highly excited string states and a late-time non-adiabatic effect intrinsic to nice slices.« less

Effects of surface wave breaking on the oceanic boundary layer

NASA Astrophysics Data System (ADS)

He, Hailun; Chen, Dake

2011-04-01

Existing laboratory studies suggest that surface wave breaking may exert a significant impact on the formation and evolution of oceanic surface boundary layer, which plays an important role in the ocean-atmosphere coupled system. However, present climate models either neglect the effects of wave breaking or treat them implicitly through some crude parameterization. Here we use a one-dimensional ocean model (General Ocean Turbulence Model, GOTM) to investigate the effects of wave breaking on the oceanic boundary layer on diurnal to seasonal time scales. First a set of idealized experiments are carried out to demonstrate the basic physics and the necessity to include wave breaking. Then the model is applied to simulating observations at the northern North Sea and the Ocean Weather Station Papa, which shows that properly accounting for wave breaking effects can improve model performance and help it to successfully capture the observed upper ocean variability.

Assessment of chemical dispersant effectiveness in a wave tank under regular non-breaking and breaking wave conditions.

PubMed

Li, Zhengkai; Lee, Kenneth; King, Thomas; Boufadel, Michel C; Venosa, Albert D

2008-05-01

Current chemical dispersant effectiveness tests for product selection are commonly performed with bench-scale testing apparatus. However, for the assessment of oil dispersant effectiveness under real sea state conditions, test protocols are required to have hydrodynamic conditions closer to the natural environment, including transport and dilution effects. To achieve this goal, Fisheries and Oceans Canada and the US Environmental Protection Agency (EPA) designed and constructed a wave tank system to study chemical dispersant effectiveness under controlled mixing energy conditions (regular non-breaking, spilling breaking, and plunging breaking waves). Quantification of oil dispersant effectiveness was based on observed changes in dispersed oil concentrations and oil-droplet size distribution. The study results quantitatively demonstrated that total dispersed oil concentration and breakup kinetics of oil droplets in the water column were strongly dependent on the presence of chemical dispersants and the influence of breaking waves. These data on the effectiveness of dispersants as a function of sea state will have significant implications in the drafting of future operational guidelines for dispersant use at sea.

Higgs naturalness and dark matter stability by scale invariance

NASA Astrophysics Data System (ADS)

Guo, Jun; Kang, Zhaofeng

2015-09-01

Extending the spacetime symmetries of standard model (SM) by scale invariance (SI) may address the Higgs naturalness problem. In this article we attempt to embed accidental dark matter (DM) into SISM, requiring that the symmetry protecting DM stability is accidental due to the model structure rather than imposed by hand. In this framework, if the light SM-like Higgs boson is the pseudo Goldstone boson of SI spontaneously breaking, we can even pine down the model, two-Higgs-doublets plus a real singlet: The singlet is the DM candidate and the extra Higgs doublet triggers electroweak symmetry breaking via the Coleman-Weinberg mechanism; Moreover, it dominates DM dynamics. We study spontaneously breaking of SI using the Gillard-Weinberg approach and find that the second doublet should acquire vacuum expectation value near the weak scale. Moreover, its components should acquire masses around 380 GeV except for a light CP-odd Higgs boson. Based on these features, we explore viable ways to achieve the correct relic density of DM, facing stringent constraints from direct detections of DM. For instance, DM annihilates into b b bar near the SM-like Higgs boson pole, or into a pair of CP-odd Higgs boson with mass above that pole.

Cooper-pair-condensate fluctuations and plasmons in layered superconductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cote, R.; Griffin, A.

1993-10-01

Starting from a given attractive potential, we give a systematic analysis of the spin-singlet [ital s]-wave Cooper-pair-condensate fluctuations in a two-dimensional (2D) superconductor. These results are applied to a superlattice of superconducting sheets in which the 2D charge fluctuations are coupled via the Coulomb interaction. Our main interest is how the low-energy Anderson-Bogoliubov (AB) phonon mode in the pair-breaking gap [omega][lt]2[Delta] is modified by the Coulomb interaction. Our formal analysis is valid at arbitrary temperatures. It describes the weakly bound, large-Cooper-pair limit as well as the strongly bound, small-Cooper-pair limit and thus includes both the BCS and Bose-Einstein scenarios (asmore » discussed by Nozieres and Schmitt-Rink as well as Randeira [ital et] [ital al].). A comlete normal-mode analysis is given for a charged BCS superconductor, showing how the repulsive (Coulomb) interaction modifies the collective modes of a neutral superconductor. This complements the recent numerical study carried out by Fertig and Das Sarma. We show that the pair-response function shares the same spectrum as the charge-response function, given by the zero of the longitudinal dielectric function [epsilon]([bold q],[omega]). In 2D and layered superconductors, there is a low-frequency and high-frequency plasmon branch, separated by a relatively narrow particle-hole continuum at around 2[Delta]. The low-frequency ([omega][lt]2[Delta]) plasmon branch is a renormalized version of the AB phonon mode.« less

Clean to dirty limit and T c suppression in NdFeAsO0.7F0.3 studied by H c2 analysis

NASA Astrophysics Data System (ADS)

Pallecchi, I.; Tarantini, C.; Shen, Y.; Singh, R. K.; Newman, N.; Cheng, P.; Jia, Y.; Wen, H.-H.; Putti, M.

2018-07-01

In this work, we investigate the temperature dependence of the upper critical field, dH c2/dT, in an increasingly disordered NdFeAsO0.7F0.3 (NdFeAs(O,F)) single crystal that has been progressively irradiated up to a 5.25 × 1016 cm- 2 total α-particle dose. For the H∣∣ab-plane, dH c2/dT does not vary remarkably with irradiation, while for the H∣∣c-axis it increases sharply after the first irradiation of 3.60 × 1015 cm-2 and then more gradually with further irradiation doses. Focusing on the H∣∣c-axis, we develop a phenomenological analysis of the H c2 slope which allows us to inspect the crossover from the clean to the dirty regime. From the H c2 slope normalized to the critical temperature and to its clean limit value, we extract the ratio of the coherence length ξ BCS to the mean free path {\\ell } and we find that when T c is reduced by a factor of four from its pristine value, ξ BCS/{\\ell } becomes as large as ˜7 and {\\ell } reaches values of ˜1.8 nm, indicating that NdFeAs(O,F) is well into the dirty regime. Our analysis of the H c2 slope also allows us to compare the pair-breaking effectiveness of scattering in different superconductors, showing similarity between unconventional NdFeAs(O,F) and moderate-T c phonon-mediated devices, such as MgB2 and A15 compounds, but much a stronger difference with YBa2Cu3O7-δ . This work thus shows that dH c2/dT is a reliable parameter, providing an alternative to residual resistivity, for investigating the pair-breaking mechanism induced by impurity scattering in superconductors.

Scenarios of physics beyond the standard model

NASA Astrophysics Data System (ADS)

Fok, Ricky

This dissertation discusses three topics on scenarios beyond the Standard Model. Topic one is the effects from a fourth generation of quarks and leptons on electroweak baryogenesis in the early universe. The Standard Model is incapable of electroweak baryogenesis due to an insufficiently strong enough electroweak phase transition (EWPT) as well as insufficient CP violation. We show that the presence of heavy fourth generation fermions solves the first problem but requires additional bosons to be included to stabilize the electroweak vacuum. Introducing supersymmetric partners of the heavy fermions, we find that the EWPT can be made strong enough and new sources of CP violation are present. Topic two relates to the lepton avor problem in supersymmetry. In the Minimal Supersymmetric Standard Model (MSSM), the off-diagonal elements in the slepton mass matrix must be suppressed at the 10-3 level to avoid experimental bounds from lepton avor changing processes. This dissertation shows that an enlarged R-parity can alleviate the lepton avor problem. An analysis of all sensitive parameters was performed in the mass range below 1 TeV, and we find that slepton maximal mixing is possible without violating bounds from the lepton avor changing processes: mu → egamma; mu → e conversion, and mu → 3e. Topic three is the collider phenomenology of quirky dark matter. In this model, quirks are particles that are gauged under the electroweak group, as well as a dark" color SU(2) group. The hadronization scale of this color group is well below the quirk masses. As a result, the dark color strings never break. Quirk and anti-quirk pairs can be produced at the LHC. Once produced, they immediately form a bound state of high angular momentum. The quirk pair rapidly shed angular momentum by emitting soft radiation before they annihilate into observable signals. This dissertation presents the decay branching ratios of quirkonia where quirks obtain their masses through electroweak symmetry breaking. This dissertation includes previously published and unpublished co-authored material.

Bosonic-seesaw portal dark matter

NASA Astrophysics Data System (ADS)

Ishida, Hiroyuki; Matsuzaki, Shinya; Yamaguchi, Yuya

2017-10-01

We discuss a new type of Higgs-portal dark matter (DM) production mechanism, called the bosonic-seesaw portal (BSP) scenario. The BS provides the dynamical origin of the electroweak symmetry breaking, triggered by mixing between the elementary Higgs and a composite Higgs generated by a new-color strong dynamics, hypercolor (HC). At the HC strong coupling scale, the classical-scale invariance assumed in the model is dynamically broken, as well as the "chiral" symmetry present in the HC sector. In addition to the composite Higgs, HC baryons emerge to potentially be stable because of the unbroken HC baryon number symmetry. Hence the lightest HC baryon can be a DM candidate. Of interest in the present scenario is that HC pions can be as heavy as the HC baryon due to the possibly enhanced explicit "chiral"-breaking effect triggered after the BS mechanism, so the HC baryon pair cannot annihilate into HC pions. As in the standard setup of the freeze-in scenario, it is assumed that the DM was never in the thermal equilibrium, which ends up with no thermal abundance. It is then the non-thermal BSP process that crucially comes into the game below the HC scale: the HC baryon significantly couples to the standard-model Higgs via the BS mechanism, and can non-thermally be produced from the thermal plasma below the HC scale, which turns out to allow the TeV mass scale for the composite baryonic DM, much smaller than the generic bound placed in the conventional thermal freeze-out scenario, to account for the observed relic abundance. Thus the DM can closely be related to the mechanism of the electroweak symmetry breaking.

Nonlinear electronic stopping power of channeled slow light ions in ZnSe: Evidence of energy loss caused by formation and breaking of chemical bond

NASA Astrophysics Data System (ADS)

Li, Chang-kai; Wang, Feng; Gao, Cong-Zhang; Liao, Bin; Ouyang, Xiao-ping; Zhang, Feng-Shou

2018-07-01

Electronic stopping power of helium ions in a semiconductor material ZnSe has been investigated through non-adiabatic dynamics simulations at energies of a few keV under channeling condition. The stopping power is predicted to be proportional to velocity for the trajectory along middle axis of a 〈 1 1 0 〉 channel, as expected for the linear response theory accounts for election-hole pair creation. While for the off-center channeling trajectory, a counterintuitive of electronic stopping power versus velocity is observed. Our study, presented herein, finds a non-trivial connection between charge transfer and the force experienced by the projectile. Charge transfer can produce, throughout the collision process, additional force by continuously forming and breaking instantaneous chemical bonds between the projectile and the neighboring host atoms.

Quantifying clustered DNA damage induction and repair by gel electrophoresis, electronic imaging and number average length analysis

NASA Technical Reports Server (NTRS)

Sutherland, Betsy M.; Georgakilas, Alexandros G.; Bennett, Paula V.; Laval, Jacques; Sutherland, John C.; Gewirtz, A. M. (Principal Investigator)

2003-01-01

Assessing DNA damage induction, repair and consequences of such damages requires measurement of specific DNA lesions by methods that are independent of biological responses to such lesions. Lesions affecting one DNA strand (altered bases, abasic sites, single strand breaks (SSB)) as well as damages affecting both strands (clustered damages, double strand breaks) can be quantified by direct measurement of DNA using gel electrophoresis, gel imaging and number average length analysis. Damage frequencies as low as a few sites per gigabase pair (10(9)bp) can be quantified by this approach in about 50ng of non-radioactive DNA, and single molecule methods may allow such measurements in DNA from single cells. This review presents the theoretical basis, biochemical requirements and practical aspects of this approach, and shows examples of their applications in identification and quantitation of complex clustered damages.

DNA Damage Signals and Space Radiation Risk

NASA Technical Reports Server (NTRS)

Cucinotta, Francis A.

2011-01-01

Space radiation is comprised of high-energy and charge (HZE) nuclei and protons. The initial DNA damage from HZE nuclei is qualitatively different from X-rays or gamma rays due to the clustering of damage sites which increases their complexity. Clustering of DNA damage occurs on several scales. First there is clustering of single strand breaks (SSB), double strand breaks (DSB), and base damage within a few to several hundred base pairs (bp). A second form of damage clustering occurs on the scale of a few kbp where several DSB?s may be induced by single HZE nuclei. These forms of damage clusters do not occur at low to moderate doses of X-rays or gamma rays thus presenting new challenges to DNA repair systems. We review current knowledge of differences that occur in DNA repair pathways for different types of radiation and possible relationships to mutations, chromosomal aberrations and cancer risks.

Control of Meiotic Crossovers: From Double-Strand Break Formation to Designation

PubMed Central

Gray, Stephen

2017-01-01

Meiosis, the mechanism of creating haploid gametes, is a complex cellular process observed across sexually reproducing organisms. Fundamental to meiosis is the process of homologous recombination, whereby DNA double-strand breaks are introduced into the genome and are subsequently repaired to generate either noncrossovers or crossovers. Although homologous recombination is essential for chromosome pairing during prophase I, the resulting crossovers are critical for maintaining homolog interactions and enabling accurate segregation at the first meiotic division. Thus, the placement, timing, and frequency of crossover formation must be exquisitely controlled. In this review, we discuss the proteins involved in crossover formation, the process of their formation and designation, and the rules governing crossovers, all within the context of the important landmarks of prophase I. We draw together crossover designation data across organisms, analyze their evolutionary divergence, and propose a universal model for crossover regulation. PMID:27648641

Broken rotational symmetry on the Fermi surface of a high-Tc superconductor

DOE PAGES

Ramshaw, B. J.; Harrison, N.; Sebastian, S. E.; ...

2017-02-13

Broken fourfold rotational (C 4) symmetry is observed in the experimental properties of several classes of unconventional superconductors. It has been proposed that this symmetry breaking is important for superconducting pairing in these materials, but in the high-T c cuprates this broken symmetry has never been observed on the Fermi surface. Here we report a pronounced anisotropy in the angle dependence of the interlayer magnetoresistance of the underdoped high transition temperature (high-T c) superconductor YBa 2Cu 3O 6.58, directly revealing broken C 4 symmetry on the Fermi surface. Moreover, we demonstrate that this Fermi surface has C 2 symmetry ofmore » the type produced by a uniaxial or anisotropic density-wave phase. This establishes the central role of C 4 symmetry breaking in the Fermi surface reconstruction of YBa 2Cu 3O 6+δ , and suggests a striking degree of universality among unconventional superconductors.« less

Effect of lipid-based dry eye supplements on the tear film in wearers of eye cosmetics.

PubMed

Wang, Michael T M; Cho, Irene Sung Hee; Jung, Soo Hee; Craig, Jennifer P

2017-08-01

To compare the effects on tear film parameters and contamination in cosmetic eyeliner wearers, after single application of two lipid-based dry eye treatments: a lipid-containing lubricant eye drop and a phospholipid liposomal spray. Fifty participants were enrolled in a prospective, randomised, paired-eye, investigator-masked trial. Pencil eyeliner (Body Shop ® Crayon Eye Definer) was applied to the upper eyelid periocular skin of both eyes, anterior to the lash line. Baseline tear film quality was assessed fifteen minutes after eyeliner application. A lubricant drop (Systane ® Balance) was then applied to one eye (randomised), and liposomal spray (Tears Again ® ) to the contralateral eye. Tear film contamination, lipid layer grade, non-invasive tear film break-up time and tear evaporation rate were evaluated fifteen minutes post-treatment and compared to pre-treatment values. Pre-treatment measurements did not differ between eyes assigned to lubricant drop and liposomal spray. Tear film contamination was observed in a greater proportion of eyes following both treatments (both p<0.05), with no significant difference between treatments (p=0.41). Both treatments improved lipid layer thickness (both p≤0.01), but effected no significant change in non-invasive tear film break-up time or tear evaporation rate (all p>0.05). Changes in tear film parameters did not differ between treatments (all p>0.05). Both the lipid-containing lubricant eye drop and phospholipid liposomal spray result in clinically apparent tear film contamination in eyeliner cosmetic wearers. Although both treatments effected an increase in lipid layer thickness, neither displayed clinical efficacy in improving tear film stability. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Topology and strong four fermion interactions in four dimensions

NASA Astrophysics Data System (ADS)

Catterall, Simon; Butt, Nouman

2018-05-01

We study massless fermions interacting through a particular four-fermion term in four dimensions. Exact symmetries prevent the generation of bilinear fermion mass terms. We determine the structure of the low-energy effective action for the auxiliary field needed to generate the four-fermion term and find it has an novel structure that admits topologically nontrivial defects with nonzero Hopf invariant. We show that fermions propagating in such a background pick up a mass without breaking symmetries. Furthermore, pairs of such defects experience a logarithmic interaction. We argue that a phase transition separates a phase where these defects proliferate from a broken phase where they are bound tightly. We conjecture that, by tuning one additional operator, the broken phase can be eliminated with a single BKT-like phase transition separating the massless from massive phases.

Glide-Plane Symmetry and Superconducting Gap Structure of Iron-Based Superconductors

NASA Astrophysics Data System (ADS)

Maier, Thomas

This talk will provide a review of the implications of the glide plane symmetry of a single Fe-pnictide/chalcogen plane on the structure of the superconducting gap. It will be shown that `` η-pairing'' with non-zero total momentum occurs inevitably in this system, but that its contribution to the superconducting condensate has the usual even parity symmetry and time reversal symmetry is preserved. I will demonstrate that for a single plane the gap function, which appears in physical quantities, is identical to that found in 1 Fe per unit cell pseudo-crystal momentum calculations and discuss the effects of the symmetry breaking out-of-plane hopping integrals in three dimensions. A portion of this research was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility.

Gravitino-overproduction problem in an inflationary universe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kawasaki, Masahiro; Takahashi, Fuminobu; Deutsches Elektronen Synchrotron DESY, Notkestrasse 85, 22607 Hamburg

We show that the gravitino-overproduction problem is prevalent among inflation models in supergravity. An inflaton field {phi} generically acquires (effective) nonvanishing auxiliary field G{sub {phi}}{sup (eff)}, if the Kaehler potential is nonminimal. The inflaton field then decays into a pair of the gravitinos. We extensively study the cosmological constraints on G{sub {phi}}{sup (eff)} for a wide range of the gravitino mass. For many inflation models we explicitly estimate G{sub {phi}}{sup (eff)}, and show that the gravitino-overproduction problem severely constrains the inflation models, unless such an interaction as K={kappa}/2 vertical bar {phi}|{sup 2}z{sup 2}+H.c. is suppressed (here z is the fieldmore » responsible for the supersymmetry breaking). We find that many of them are already excluded or on the verge of, if {kappa}{approx}O(1)« less

A tractable and accurate electronic structure method for static correlations: The perfect hextuples model

NASA Astrophysics Data System (ADS)

Parkhill, John A.; Head-Gordon, Martin

2010-07-01

We present the next stage in a hierarchy of local approximations to complete active space self-consistent field (CASSCF) model in an active space of one active orbital per active electron based on the valence orbital-optimized coupled-cluster (VOO-CC) formalism. Following the perfect pairing (PP) model, which is exact for a single electron pair and extensive, and the perfect quadruples (PQ) model, which is exact for two pairs, we introduce the perfect hextuples (PH) model, which is exact for three pairs. PH is an approximation to the VOO-CC method truncated at hextuples containing all correlations between three electron pairs. While VOO-CCDTQ56 requires computational effort scaling with the 14th power of molecular size, PH requires only sixth power effort. Our implementation also introduces some techniques which reduce the scaling to fifth order and has been applied to active spaces roughly twice the size of the CASSCF limit without any symmetry. Because PH explicitly correlates up to six electrons at a time, it can faithfully model the static correlations of molecules with up to triple bonds in a size-consistent fashion and for organic reactions usually reproduces CASSCF with chemical accuracy. The convergence of the PP, PQ, and PH hierarchy is demonstrated on a variety of examples including symmetry breaking in benzene, the Cope rearrangement, the Bergman reaction, and the dissociation of fluorine.

The Effects of Spacing, Naps, and Fatigue on the Acquisition and Retention of Laparoscopic Skills.

PubMed

Spruit, Edward N; Band, Guido P H; van der Heijden, Kristiaan B; Hamming, Jaap F

Earlier research has shown that laparoscopic skills are trained more efficiently on a spaced schedule compared to a massed schedule. The aim of the study was to estimate to what extent the spacing interval, naps, and fatigue influenced the effectiveness of spacing laparoscopy training. Overall 4 groups of trainees (aged 17-41y; 72% female; N massed = 40; N break = 35; N break-nap = 37; N spaced = 37) without prior experience were trained in 3 laparoscopic tasks using a physical box trainer with different scheduling interventions. The first (massed) group received three 100-minute training sessions consecutively on a single day. The second (break) group received the sessions interrupted with two 45-minute breaks. The third (break-nap) group had the same schedule as the second group, but had two 35-minute powernap intervals during the breaks. The fourth (spaced) group had the 3 sessions on 3 consecutive days. A retention session was organized approximately 3 months after training. The results showed an overall pattern of superior performance at the end of training and at retention for the spaced group, followed by the break-nap, break, and massed group, respectively. The spaced and break-nap group significantly outperformed the break and massed group, with effect sizes ranging from 0.20 to 0.37. Spacing laparoscopic training over 3 consecutive days or weeks is superior to massed training, even if the massed training contains breaks. Breaks with sleep opportunity (i.e., lying, inactive, and muted sensory input) enhance performance over training with regular breaks and traditional massed training. Copyright © 2017 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

Thermodynamic Identities and Symmetry Breaking in Short-Range Spin Glasses

NASA Astrophysics Data System (ADS)

Arguin, L.-P.; Newman, C. M.; Stein, D. L.

2015-10-01

We present a technique to generate relations connecting pure state weights, overlaps, and correlation functions in short-range spin glasses. These are obtained directly from the unperturbed Hamiltonian and hold for general coupling distributions. All are satisfied in phases with simple thermodynamic structure, such as the droplet-scaling and chaotic pairs pictures. If instead nontrivial mixed-state pictures hold, the relations suggest that replica symmetry is broken as described by a Derrida-Ruelle cascade, with pure state weights distributed as a Poisson-Dirichlet process.

van der Waals-type forces in spontaneously broken supersymmetries

NASA Astrophysics Data System (ADS)

Radescu, E. E.

1983-03-01

In spontaneously broken rigid supersymmetry, Goldstone-fermion pair exchange should lead to a universal interaction between massive bodies uniquely fixed by the existing low-energy theorem. The resulting van der Waals-type potential is shown to be V(r)=-Mmπ-3F-4r-7+O(r-8), where M and m are the masses of the interacting bodies while F is the scale of the breaking. The change in the situation when the supersymmetry is promoted to a local symmetry is briefly discussed.

Iron chalcogenide superconductors at high magnetic fields

PubMed Central

Lei, Hechang; Wang, Kefeng; Hu, Rongwei; Ryu, Hyejin; Abeykoon, Milinda; Bozin, Emil S; Petrovic, Cedomir

2012-01-01

Iron chalcogenide superconductors have become one of the most investigated superconducting materials in recent years due to high upper critical fields, competing interactions and complex electronic and magnetic phase diagrams. The structural complexity, defects and atomic site occupancies significantly affect the normal and superconducting states in these compounds. In this work we review the vortex behavior, critical current density and high magnetic field pair-breaking mechanism in iron chalcogenide superconductors. We also point to relevant structural features and normal-state properties. PMID:27877518

Phonon-mediated quasiparticle poisoning of superconducting microwave resonators

NASA Astrophysics Data System (ADS)

Patel, U.; Pechenezhskiy, Ivan V.; Plourde, B. L. T.; Vavilov, M. G.; McDermott, R.

2017-12-01

Nonequilibrium quasiparticles represent a significant source of decoherence in superconducting quantum circuits. Here we investigate the mechanism of quasiparticle poisoning in devices subjected to local quasiparticle injection. We find that quasiparticle poisoning is dominated by the propagation of pair-breaking phonons across the chip. We characterize the energy dependence of the time scale for quasiparticle poisoning. Finally, we observe that incorporation of extensive normal metal quasiparticle traps leads to a more than order-of-magnitude reduction in quasiparticle loss for a given injected quasiparticle power.

SU-E-T-494: Influence of Proton Track-Cell Nucleus Incidence Angle On Relative Biological Effectiveness

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pater, P; Backstrom, G; Enger, S

2015-06-15

Purpose: To explain a Monte Carlo (MC) simulation artifact whereby differences in relative biological effectiveness (RBE) in the induction of initial double strand breaks are observed as a function of the proton track incidence angles in a geometric cell nucleus model. Secondly, to offer an alternative isotropic irradiation procedure to mitigate this effect. Methods: MC tracks of 1 MeV protons were generated in an event-by-event mode. They were overlaid on a cylindrical model of a cell nucleus containing 6×109 nucleotide base pairs. The tracks incidence angle θ with respect to the cell nucleus’s axis was varied in 10 degrees intervals,more » each time generating one hundred fractions of ∼2 Gy. Strand breaks were scored in the modeled DNA sugar-phosphate groups and further sub-classified into single or double strand breaks (ssbs or dsbs). For each angle, an RBE for the induction of initial dsbs with reference to Co-60 was calculated. Results: Our results show significant angular dependencies of RBE, with maximum values for incidence angles parallel to the nucleus central axis. Further examination shows that the higher cross-sections for the creation of dsbs is due to the preferential alignment of tracks with geometrical sub-parts of the cell nucleus model, especially the nucleosomes containing the sugar-phosphate groups. To alleviate the impact of this simulation artifact, an average RBE was calculated with a procedure based on a weighted sampling of the angular data. Conclusion: This work demonstrates a possible numerical artifact in estimated RBE if the influence of the particle incidence angle is not correctly taken into account. A correction procedure is presented to better conform the simulations to real-life experimental conditions. We would like to acknowledge support from the Fonds de recherche du Quebec Sante (FRQS), from the CREATE Medical Physics Research Training Network grant (number 432290) of NSERC, support from NSERC under grants RGPIN 397711-11 and RGPIN-2014-06475 and support from the CIHR under grants MOP-114910, MOP-136774 and MOP-102550.« less

Bond-equilibrium theory of liquid Se-Te alloys. II. Effect of singly attached ring molecules

NASA Astrophysics Data System (ADS)

Cutler, Melvin; Bez, Wolfgang G.

1981-06-01

A statistical-mechanical theory for bond equilibrium of chain polymers containing threefold (3F) and onefold (1F) bond defects is extended to include the effects of free ring molecules and ring molecules attached to chains by a single 3F atom. Positively charged singly attached rings are shown to play a key role in bond equilibrium in liquid Sex Te1-x by permitting the formation of ion pairs in which both constituents are effectively chain terminators, thus decreasing the average polymer size. The theory is applied to explain the behavior of the paramagnetic susceptibility, χp, and electronic transport as affected by the Fermi energy EF. It is found that the increase in χp with the concentration of Te is primarily the result of the smaller energy for breaking Te bonds. In addition, attached rings play an important role in determining the effect of temperature on χp. At x<~0.5, the concentrations of both free and attached rings becomes small at high T because of the high concentration of bond defects.

Proximity Within Interphase Chromosome Contributes to the Breakpoint Distribution in Radiation-Induced Intrachromosomal Exchanges

NASA Technical Reports Server (NTRS)

Zhang, Ye; Uhlemeyer, Jimmy; Hada, Megumi; Asaithamby, A.; Chen, David J.; Wu, Honglu

2015-01-01

Previously, we reported that breaks involved in chromosome aberrations were clustered in several regions of chromosome3 in human mammary epithelial cells after exposures to either low-or high-LET radiation. In particular, breaks in certain regions of the chromosome tended to rejoin with each other to form an intrachromosome exchange event. This study tests the hypothesis that proximity within a single chromosome in interphase cell nuclei contributes to the distribution of radiation-induced chromosome breaks. Chromosome 3 in G1 human mammary epithelial cells was hybridized with the multicolor banding in situ hybridization (mBAND) probes that distinguish the chromosome in six differently colored regions, and the location of these regions was measured with a laser confocal microscope. Results of the study indicated that, on a multi-mega base pair scale of the DNA, the arrangement of chromatin was non-random. Both telomere regions tended to be located towards the exterior of the chromosome domain, whereas the centromere region towards the interior. In addition, the interior of the chromosome domain was preferentially occupied by the p-arm of the chromatin, which is consistent with our previous finding of intrachromosome exchanges involving breaks on the p-arm and in the centromere region of chromosome3. Other factors, such as the fragile sites in the 3p21 band and gene regulation, may also contribute to the breakpoint distribution in radiation-induced chromosome aberrations. Further investigations suggest that the 3D chromosome folding is cell type and culture condition dependent.

Interplay between superconductivity and magnetism in iron-based superconductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chubukov, Andrey V

2015-06-10

This proposal is for theoretical work on strongly correlated electron systems, which are at the center of experimental and theoretical activities in condensed-matter physics. The interest to this field is driven fascinating variety of observed effects, universality of underlying theoretical ideas, and practical applications. I propose to do research on Iron-based superconductors (FeSCs), which currently attract high attention in the physics community. My goal is to understand superconductivity and magnetism in these materials at various dopings, the interplay between the two, and the physics in the phase in which magnetism and superconductivity co-exist. A related goal is to understand themore » origin of the observed pseudogap-like behavior in the normal state. My research explores the idea that superconductivity is of electronic origin and is caused by the exchange of spin-fluctuations, enhanced due to close proximity to antiferromagnetism. The multi-orbital/multi-band nature of FeSCs opens routes for qualitatively new superconducting states, particularly the ones which break time-reversal symmetry. By all accounts, the coupling in pnictdes is below the threshold for Mott physics and I intend to analyze these systems within the itinerant approach. My plan is to do research in two stages. I first plan to address several problems within weak-coupling approach. Among them: (i) what sets stripe magnetic order at small doping, (ii) is there a preemptive instability into a spin-nematic state, and how stripe order affects fermions; (iii) is there a co-existence between magnetism and superconductivity and what are the system properties in the co-existence state; (iv) how superconductivity emerges despite strong Coulomb repulsion and can the gap be s-wave but with nodes along electron FSs, (v) are there complex superconducting states, like s+id, which break time reversal symmetry. My second goal is to go beyond weak coupling and derive spin-mediated, dynamic interaction between fermions, understand what sets the upper scale for attractive interaction, compute T_c, and then obtain and solve matrix non-linear gap equation for spin-mediated pairing and study various feedbacks from the pairing on fermions on ARPES spectra, optical and thermal conductivity, and other observables, The problems I have chosen are quite generic, and the understanding of magnetically-mediated superconductivity in the strong-coupling regime will not only advance the theory of superconductivity in FeSCs, but will contribute to a generic understanding of the pairing of fermions near quantum-critical points -- the problems ranging from s-wave pairing by soft optical phonons to to color superconductivity of quarks mediated by a gluon exchange.« less

A conservation paradox in the Great Basin—Altering sagebrush landscapes with fuel breaks to reduce habitat loss from wildfire

USGS Publications Warehouse

Shinneman, Douglas J.; Aldridge, Cameron L.; Coates, Peter S.; Germino, Matthew J.; Pilliod, David S.; Vaillant, Nicole M.

2018-03-15

Interactions between fire and nonnative, annual plant species (that is, “the grass/fire cycle”) represent one of the greatest threats to sagebrush (Artemisia spp.) ecosystems and associated wildlife, including the greater sage-grouse (Centrocercus urophasianus). In 2015, U.S. Department of the Interior called for a “science-based strategy to reduce the threat of large-scale rangeland fire to habitat for the greater sage-grouse and the sagebrush-steppe ecosystem.” An associated guidance document, the “Integrated Rangeland Fire Management Strategy Actionable Science Plan,” identified fuel breaks as high priority areas for scientific research. Fuel breaks are intended to reduce fire size and frequency, and potentially they can compartmentalize wildfire spatial distribution in a landscape. Fuel breaks are designed to reduce flame length, fireline intensity, and rates of fire spread in order to enhance firefighter access, improve response times, and provide safe and strategic anchor points for wildland fire-fighting activities. To accomplish these objectives, fuel breaks disrupt fuel continuity, reduce fuel accumulation, and (or) increase plants with high moisture content through the removal or modification of vegetation in strategically placed strips or blocks of land.Fuel breaks are being newly constructed, enhanced, or proposed across large areas of the Great Basin to reduce wildfire risk and to protect remaining sagebrush ecosystems (including greater sage-grouse habitat). These projects are likely to result in thousands of linear miles of fuel breaks that will have direct ecological effects across hundreds of thousands of acres through habitat loss and conversion. These projects may also affect millions of acres indirectly because of edge effects and habitat fragmentation created by networks of fuel breaks. Hence, land managers are often faced with a potentially paradoxical situation: the need to substantially alter sagebrush habitats with fuel breaks to ultimately reduce a greater threat of their destruction from wildfire. However, there is relatively little published science that directly addresses the ability of fuel breaks to influence fire behavior in dryland landscapes or that addresses the potential ecological effects of the construction and maintenance of fuel breaks on sagebrush ecosystems and associated wildlife species.This report is intended to provide an initial assessment of both the potential effectiveness of fuel breaks and their ecological costs and benefits. To provide this assessment, we examined prior studies on fuel breaks and other scientific evidence to address three crucial questions: (1) How effective are fuel breaks in reducing or slowing the spread of wildfire in arid and semi-arid shrubland ecosystems? (2) How do fuel breaks affect sagebrush plant communities? (3) What are the effects of fuel breaks on the greater sage-grouse, other sagebrush obligates, and sagebrush-associated wildlife species? We also provide an overview of recent federal policies and management directives aimed at protecting remaining sagebrush and greater sage-grouse habitat; describe the fuel conditions, fire behavior, and fire trends in the Great Basin; and suggest how scientific inquiry and management actions can improve our understanding of fuel breaks and their effects in sagebrush landscapes.

Recursive model for the fragmentation of polarized quarks

NASA Astrophysics Data System (ADS)

Kerbizi, A.; Artru, X.; Belghobsi, Z.; Bradamante, F.; Martin, A.

2018-04-01

We present a model for Monte Carlo simulation of the fragmentation of a polarized quark. The model is based on string dynamics and the 3P0 mechanism of quark pair creation at string breaking. The fragmentation is treated as a recursive process, where the splitting function of the subprocess q →h +q' depends on the spin density matrix of the quark q . The 3P0 mechanism is parametrized by a complex mass parameter μ , the imaginary part of which is responsible for single spin asymmetries. The model has been implemented in a Monte Carlo program to simulate jets made of pseudoscalar mesons. Results for single hadron and hadron pair transverse-spin asymmetries are found to be in agreement with experimental data from SIDIS and e+e- annihilation. The model predictions on the jet-handedness are also discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.

Results of a search for new physics in final states with photons and missing transverse energy are reported. The study is based on a sample of proton–proton collisions collected at a center-of-mass energy of 13 TeV with the CMS detector in 2015, corresponding to an integrated luminosity of 2.3 fb -1. Final states with two photons and significant missing transverse energy are used to search for supersymmetric particles in models of supersymmetry (SUSY) with general gauge-mediated (GGM) supersymmetry breaking. We did not observe an excess with respect to the standard model expectation, and the results are used to set limitsmore » on gluino pair production and squark pair production in the GGM SUSY framework. Gluino masses below 1.65 TeV and squark masses below 1.37 TeV are excluded at a 95% confidence level.« less

Confinement with Perturbation Theory, After All?

NASA Astrophysics Data System (ADS)

Hoyer, Paul

2015-09-01

I call attention to the possibility that QCD bound states (hadrons) could be derived using rigorous Hamiltonian, perturbative methods. Solving Gauss' law for A 0 with a non-vanishing boundary condition at spatial infinity gives an linear potential for color singlet and qqq states. These states are Poincaré and gauge covariant and thus can serve as initial states of a perturbative expansion, replacing the conventional free in and out states. The coupling freezes at , allowing reasonable convergence. The bound states have a sea of pairs, while transverse gluons contribute only at . Pair creation in the linear A 0 potential leads to string breaking and hadron loop corrections. These corrections give finite widths to excited states, as required by unitarity. Several of these features have been verified analytically in D = 1 + 1 dimensions, and some in D = 3 + 1.

Evaluating crude oil chemical dispersion efficacy in a flow-through wave tank under regular non-breaking wave and breaking wave conditions.

PubMed

Li, Zhengkai; Lee, Kenneth; King, Thomas; Boufadel, Michel C; Venosa, Albert D

2009-05-01

Testing dispersant effectiveness under conditions similar to that of the open environment is required for improvements in operational procedures and the formulation of regulatory guidelines. To this end, a novel wave tank facility was fabricated to study the dispersion of crude oil under regular non-breaking and irregular breaking wave conditions. This wave tank facility was designed for operation in a flow-through mode to simulate both wave- and current-driven hydrodynamic conditions. We report here an evaluation of the effectiveness of chemical dispersants (Corexit EC9500A and SPC 1000) on two crude oils (Medium South American [MESA] and Alaska North Slope [ANS]) under two different wave conditions (regular non-breaking and plunging breaking waves) in this wave tank. The dispersant effectiveness was assessed by measuring the water column oil concentration and dispersed oil droplet size distribution. In the absence of dispersants, nearly 8-19% of the test crude oils were dispersed and diluted under regular wave and breaking wave conditions. In the presence of dispersants, about 21-36% of the crude oils were dispersed and diluted under regular waves, and 42-62% under breaking waves. Consistently, physical dispersion under regular waves produced large oil droplets (volumetric mean diameter or VMD > or = 300 microm), whereas chemical dispersion under breaking waves created small droplets (VMD < or = 50 microm). The data can provide useful information for developing better operational guidelines for dispersant use and improved predictive models on dispersant effectiveness in the field.

Ferroelectricity by Bose-Einstein condensation in a quantum magnet.

PubMed

Kimura, S; Kakihata, K; Sawada, Y; Watanabe, K; Matsumoto, M; Hagiwara, M; Tanaka, H

2016-09-26

The Bose-Einstein condensation is a fascinating phenomenon, which results from quantum statistics for identical particles with an integer spin. Surprising properties, such as superfluidity, vortex quantization or Josephson effect, appear owing to the macroscopic quantum coherence, which spontaneously develops in Bose-Einstein condensates. Realization of Bose-Einstein condensation is not restricted in fluids like liquid helium, a superconducting phase of paired electrons in a metal and laser-cooled dilute alkali atoms. Bosonic quasi-particles like exciton-polariton and magnon in solids-state systems can also undergo Bose-Einstein condensation in certain conditions. Here, we report that the quantum coherence in Bose-Einstein condensate of the magnon quasi particles yields spontaneous electric polarization in the quantum magnet TlCuCl 3 , leading to remarkable magnetoelectric effect. Very soft ferroelectricity is realized as a consequence of the O(2) symmetry breaking by magnon Bose-Einstein condensation. The finding of this ferroelectricity will open a new window to explore multi-functionality of quantum magnets.

Upper critical field and Kondo effects in Fe(Te 0.9Se 0.1) thin films by pulsed field measurements

DOE PAGES

Salamon, Myron B.; Cornell, Nicholas; Jaime, Marcelo; ...

2016-02-10

The transition temperatures of epitaxial films of Fe(Te 0:9Se 0:1) are remarkably insensitive to applied magnetic field, leading to predictions of upper critical fields B c2(T = 0) in excess of 100 T. Using pulsed magnetic fields, we find B c2(0) to be on the order of 45 T, similar to values in bulk material and still in excess of the paramagnetic limit. The same films show strong magnetoresistance in fields above B c2(T), consistent with the observed Kondo minimum seen above T c. Fits to the temperature dependence in the context of the WHH model, using the experimental valuemore » of the Maki parameter, require an effective spin-orbit relaxation parameter of order unity. Lastly, we suggest that Kondo localization plays a similar role to spin-orbit pair breaking in making WHH fits to the data.« less

Adolescent externalizing behaviour, psychological control, and peer rejection: Transactional links and dopaminergic moderation.

PubMed

Janssens, Annelies; Van Den Noortgate, Wim; Goossens, Luc; Verschueren, Karine; Colpin, Hilde; Claes, Stephan; Van Heel, Martijn; Van Leeuwen, Karla

2017-09-01

This study investigated (1) reciprocal links among parental psychological control, peer rejection, and adolescent externalizing (aggressive and rule-breaking behaviour), and (2) the moderating effect of an adolescent genetic factor (biologically informed polygenic score for dopamine signalling). Three-year longitudinal data from 1,116 adolescents (51% boys; M age = 13.79) and their parents included psychological measures (adolescent-reported psychological control, peer-reported rejection, and parent-reported aggressive and rule-breaking behaviour). Cross-lagged analyses showed bidirectional effects between psychological control and both aggressive and rule-breaking behaviour and a unidirectional effect of peer rejection on both forms of problem behaviour over time. Multigroup structural equation modelling revealed genetic moderation only for rule-breaking behaviour: for adolescents with intermediate levels of dopamine signalling significant environmental effects were present, whereas adolescent effects of rule-breaking behaviour on psychological control were significant for adolescents with both intermediate and high profiles and effects on peer rejection only for adolescents with high dopamine profiles. Statement of contribution What is already known on this subject? Parental psychological control is related to adolescent externalizing problems. Experiencing peer rejection reinforces aggressive and rule-breaking behaviour. Single-gene studies show that dopaminergic genes influence externalizing problems directly or in interaction with the environment. What does this study add? Parental psychological control and adolescent aggressive and rule-breaking behaviour exacerbate one another longitudinally. Longitudinal associations between peer rejection and both subtypes of externalizing behaviour are unidirectional. With a polygenic approach, dopaminergic moderation is present for rule-breaking behaviour only. © 2017 The British Psychological Society.

Factors affecting fuel break effectiveness in the control of large fires on the Los Padres National Forest, California

USGS Publications Warehouse

Syphard, Alexandra D.; Keeley, Jon E.; Brennan, Teresa J.

2011-01-01

As wildfires have increased in frequency and extent, so have the number of homes developed in the wildland-urban interface. In California, the predominant approach to mitigating fire risk is construction of fuel breaks, but there has been little empirical study of their role in controlling large fires.We constructed a spatial database of fuel breaks on the Los Padres National Forest in southern California to better understand characteristics of fuel breaks that affect the behaviour of large fires and to map where fires and fuel breaks most commonly intersect. We evaluated whether fires stopped or crossed over fuel breaks over a 28-year period and compared the outcomes with physical characteristics of the sites, weather and firefighting activities during the fire event. Many fuel breaks never intersected fires, but others intersected several, primarily in historically fire-prone areas. Fires stopped at fuel breaks 46% of the time, almost invariably owing to fire suppression activities. Firefighter access to treatments, smaller fires and longer fuel breaks were significant direct influences, and younger vegetation and fuel break maintenance indirectly improved the outcome by facilitating firefighter access. This study illustrates the importance of strategic location of fuel breaks because they have been most effective where they provided access for firefighting activities.

Remote Sensing Characteristics of Wave Breaking Rollers

NASA Astrophysics Data System (ADS)

Haller, M. C.; Catalan, P.

2006-12-01

The wave roller has a primary influence on the balances of mass and momentum in the surf zone (e.g. Svendsen, 1984; Dally and Brown, 1995; Ruessink et al., 2001). In addition, the roller area and its angle of inclination on the wave front are important quantities governing the dissipation rates in breaking waves (e.g Madsen et al., 1997). Yet, there have been very few measurements published of individual breaking wave roller geometries in shallow water. A number of investigators have focused on observations of the initial jet-like motion at the onset of breaking before the establishment of the wave roller (e.g. Basco, 1985; Jansen, 1986), while Govender et al. (2002) provide observations of wave roller vertical cross-sections and angles of inclination for a pair of laboratory wave conditions. Nonetheless, presently very little is known about the growth, evolution, and decay of this aerated region of white water as it propagates through the surf zone; mostly due to the inherent difficulties in making the relevant observations. The present work is focused on analyzing observations of the time and space scales of individual shallow water breaking wave rollers as derived from remote sensing systems. Using a high-resolution video system in a large-scale laboratory facility, we have obtained detailed measurements of the growth and evolution of the wave breaking roller. In addition, by synchronizing the remote video with in-situ wave gages, we are able to directly relate the video intensity signal to the underlying wave shape. Results indicate that the horizontal length scale of breaking wave rollers differs significantly from the previous observations of Duncan (1981), which has been a traditional basis for roller model parameterizations. The overall approach to the video analysis is new in the sense that we concentrate on individual breaking waves, as opposed to the more commonly used time-exposure technique. In addition, a new parameter of interest, denoted Imax, is introduced based on the envelope of the intensity signal. The parameter is shown to be much less sensitive to trailing wave breaking foam, which typically corrupts time-exposure data. In the present work this parameter is shown to provide high-resolution information regarding the onset of wave breaking and the spatial evolution of the wave roller. Ongoing work will attempt to relate the shoreward transformation of the intensity maximum and the geometric characteristics of the wave roller to the spatial distribution of wave breaking dissipation. Finally, we will compare wave breaking characteristics as imaged by two separate remote sensors. Synoptic images from both video and microwave radar remote sensors were obtained in September of 2005 at Duck, NC. This combination of the two observing systems will allow direct quantitative comparisons between the two imaging mechanisms and lead to a better understanding of the strengths and weaknesses of both for nearshore research and observational remote sensing.

Effect of winter school breaks on influenza-like illness, Argentina, 2005-2008.

PubMed

Garza, Roberto C; Basurto-Dávila, Ricardo; Ortega-Sanchez, Ismael R; Carlino, Luis Oreste; Meltzer, Martin I; Albalak, Rachel; Balbuena, Karina; Orellano, Pablo; Widdowson, Marc-Alain; Averhoff, Francisco

2013-06-01

School closures are used to reduce seasonal and pandemic influenza transmission, yet evidence of their effectiveness is sparse. In Argentina, annual winter school breaks occur during the influenza season, providing an opportunity to study this intervention. We used 2005-2008 national weekly surveillance data of visits to a health care provider for influenza-like illness (ILI) from all provinces. Using Serfling-specified Poisson regressions and population-based census denominators, we developed incidence rate ratios (IRRs) for the 3 weeks before, 2 weeks during, and 3 weeks after the break. For persons 5-64 years of age, IRRs were <1 for at least 1 week after the break. Observed rates returned to expected by the third week after the break; overall decrease among persons of all ages was 14%. The largest decrease was among children 5-14 years of age during the week after the break (37% lower IRR). Among adults, effects were weaker and delayed. Two-week winter school breaks significantly decreased visits to a health care provider for ILI among school-aged children and nonelderly adults.

Effect of Winter School Breaks on Influenza-like Illness, Argentina, 2005–2008

PubMed Central

Basurto-Dávila, Ricardo; Ortega-Sanchez, Ismael R.; Carlino, Luis Oreste; Meltzer, Martin I.; Albalak, Rachel; Balbuena, Karina; Orellano, Pablo; Widdowson, Marc-Alain; Averhoff, Francisco

2013-01-01

School closures are used to reduce seasonal and pandemic influenza transmission, yet evidence of their effectiveness is sparse. In Argentina, annual winter school breaks occur during the influenza season, providing an opportunity to study this intervention. We used 2005–2008 national weekly surveillance data of visits to a health care provider for influenza-like illness (ILI) from all provinces. Using Serfling-specified Poisson regressions and population-based census denominators, we developed incidence rate ratios (IRRs) for the 3 weeks before, 2 weeks during, and 3 weeks after the break. For persons 5–64 years of age, IRRs were <1 for at least 1 week after the break. Observed rates returned to expected by the third week after the break; overall decrease among persons of all ages was 14%. The largest decrease was among children 5–14 years of age during the week after the break (37% lower IRR). Among adults, effects were weaker and delayed. Two-week winter school breaks significantly decreased visits to a health care provider for ILI among school-aged children and nonelderly adults. PMID:23735682

Dictionary Pair Learning on Grassmann Manifolds for Image Denoising.

PubMed

Zeng, Xianhua; Bian, Wei; Liu, Wei; Shen, Jialie; Tao, Dacheng

2015-11-01

Image denoising is a fundamental problem in computer vision and image processing that holds considerable practical importance for real-world applications. The traditional patch-based and sparse coding-driven image denoising methods convert 2D image patches into 1D vectors for further processing. Thus, these methods inevitably break down the inherent 2D geometric structure of natural images. To overcome this limitation pertaining to the previous image denoising methods, we propose a 2D image denoising model, namely, the dictionary pair learning (DPL) model, and we design a corresponding algorithm called the DPL on the Grassmann-manifold (DPLG) algorithm. The DPLG algorithm first learns an initial dictionary pair (i.e., the left and right dictionaries) by employing a subspace partition technique on the Grassmann manifold, wherein the refined dictionary pair is obtained through a sub-dictionary pair merging. The DPLG obtains a sparse representation by encoding each image patch only with the selected sub-dictionary pair. The non-zero elements of the sparse representation are further smoothed by the graph Laplacian operator to remove the noise. Consequently, the DPLG algorithm not only preserves the inherent 2D geometric structure of natural images but also performs manifold smoothing in the 2D sparse coding space. We demonstrate that the DPLG algorithm also improves the structural SIMilarity values of the perceptual visual quality for denoised images using the experimental evaluations on the benchmark images and Berkeley segmentation data sets. Moreover, the DPLG also produces the competitive peak signal-to-noise ratio values from popular image denoising algorithms.

Mechanistic basis of infertility of mouse intersubspecific hybrids

PubMed Central

Bhattacharyya, Tanmoy; Gregorova, Sona; Mihola, Ondrej; Anger, Martin; Sebestova, Jaroslava; Denny, Paul; Simecek, Petr; Forejt, Jiri

2013-01-01

According to the Dobzhansky–Muller model, hybrid sterility is a consequence of the independent evolution of related taxa resulting in incompatible genomic interactions of their hybrids. The model implies that the incompatibilities evolve randomly, unless a particular gene or nongenic sequence diverges much faster than the rest of the genome. Here we propose that asynapsis of heterospecific chromosomes in meiotic prophase provides a recurrently evolving trigger for the meiotic arrest of interspecific F1 hybrids. We observed extensive asynapsis of chromosomes and disturbance of the sex body in >95% of pachynemas of Mus m. musculus × Mus m. domesticus sterile F1 males. Asynapsis was not preceded by a failure of double-strand break induction, and the rate of meiotic crossing over was not affected in synapsed chromosomes. DNA double-strand break repair was delayed or failed in unsynapsed autosomes, and misexpression of chromosome X and chromosome Y genes was detected in single pachynemas and by genome-wide expression profiling. Oocytes of F1 hybrid females showed the same kind of synaptic problems but with the incidence reduced to half. Most of the oocytes with pachytene asynapsis were eliminated before birth. We propose the heterospecific pairing of homologous chromosomes as a preexisting condition of asynapsis in interspecific hybrids. The asynapsis may represent a universal mechanistic basis of F1 hybrid sterility manifested by pachytene arrest. It is tempting to speculate that a fast-evolving subset of the noncoding genomic sequence important for chromosome pairing and synapsis may be the culprit. PMID:23329330

Mechanistic basis of infertility of mouse intersubspecific hybrids.

PubMed

Bhattacharyya, Tanmoy; Gregorova, Sona; Mihola, Ondrej; Anger, Martin; Sebestova, Jaroslava; Denny, Paul; Simecek, Petr; Forejt, Jiri

2013-02-05

According to the Dobzhansky-Muller model, hybrid sterility is a consequence of the independent evolution of related taxa resulting in incompatible genomic interactions of their hybrids. The model implies that the incompatibilities evolve randomly, unless a particular gene or nongenic sequence diverges much faster than the rest of the genome. Here we propose that asynapsis of heterospecific chromosomes in meiotic prophase provides a recurrently evolving trigger for the meiotic arrest of interspecific F1 hybrids. We observed extensive asynapsis of chromosomes and disturbance of the sex body in >95% of pachynemas of Mus m. musculus × Mus m. domesticus sterile F1 males. Asynapsis was not preceded by a failure of double-strand break induction, and the rate of meiotic crossing over was not affected in synapsed chromosomes. DNA double-strand break repair was delayed or failed in unsynapsed autosomes, and misexpression of chromosome X and chromosome Y genes was detected in single pachynemas and by genome-wide expression profiling. Oocytes of F1 hybrid females showed the same kind of synaptic problems but with the incidence reduced to half. Most of the oocytes with pachytene asynapsis were eliminated before birth. We propose the heterospecific pairing of homologous chromosomes as a preexisting condition of asynapsis in interspecific hybrids. The asynapsis may represent a universal mechanistic basis of F1 hybrid sterility manifested by pachytene arrest. It is tempting to speculate that a fast-evolving subset of the noncoding genomic sequence important for chromosome pairing and synapsis may be the culprit.

Evaluation of the approach based on the concept of hyperbolicity breaking for prediction of flooding velocity of both room temperature and cryogenic fluids

NASA Astrophysics Data System (ADS)

Zhou, Rui; Yu, Liu; Xie, Huangjun; Qiu, Limin; Zhi, Xiaoqin; Zhang, Xiaobin

2018-07-01

The theoretical approach for the prediction of flooding velocity based on the concept of hyperbolicity breaking was evaluated in the counter-current two-phase flow. Detailed mathematical derivations of neutral stability condition together with the correlation of the void fraction are presented. The flooding velocity is obtained by assuming that the wavelength at flooding is proportional to the wavelength of the fastest-growing wave at Helmholtz instability. Some available experimental data for different fluid pair flow in inclined tubes is adopted for comparison with the theoretical calculations, which includes the data of water/air, aqueous oleic acid natrium solution/air, Aq. butanol 2%/air and kerosene/air in the published papers, as well as the liquid nitrogen/vapor nitrogen by the present authors. The comparison of flooding velocity proves that the approach can predict the flooding velocity with accepted accuracy for the water/air and liquid nitrogen/vapor nitrogen flow if the tube diameter is greater than 9 mm. While the diameter is smaller than 9 mm, regardless of the inclinations and the fluid pairs, the error becomes larger relative to the cases of diameter larger than 9 mm. The calculations for small diameter cases also fail to predict the critical liquid velocity at which the flooding velocity of gas reaches the maximum value, as revealed by the experiments. The reasons for the increased errors were qualitatively explained.

The Efficacy of a Brief Nature Sound Intervention on Muscle Tension, Pulse Rate, and Self-Reported Stress: Nature Contact Micro-Break in an Office or Waiting Room.

PubMed

Largo-Wight, Erin; O'Hara, Brian K; Chen, W William

2016-10-01

There is a growing recognition that environmental design impacts health and well-being. Nature contact is a design feature or exposure that is especially important in public health and healthcare. To date, there are limited findings on the impact of nature sounds. This experimental study was designed to examine the effect of nature sounds on physiological and psychological stress. Participants were randomized into one of three groups-silence (n = 9), nature sound (n = 17), and classical music (n = 14)-and listened to the assigned sound for 15 min in an office or waiting room-like environment. Pre- and postdata were collected including muscle tension (electromyogram), pulse rate, and self-reported stress. With the exception of pulse rate, there were no statistical differences in baseline or demographics among groups. A paired t-test by group showed a decrease in muscle tension, pulse rate, and self-reported stress in the nature group and no significant differences in the control or the classical music groups. The significant reduction in muscle tension occurred at least by 7 min of listening to the nature sound. This study highlights the potential benefit of even very brief (less than 7 min) exposure to nature sounds. Brief nature sound "booster breaks" are a promising area for future research with important practical implications. © The Author(s) 2016.

Initial construct validity evidence of a virtual human application for competency assessment in breaking bad news to a cancer patient.

PubMed

Guetterman, Timothy C; Kron, Frederick W; Campbell, Toby C; Scerbo, Mark W; Zelenski, Amy B; Cleary, James F; Fetters, Michael D

2017-01-01

Despite interest in using virtual humans (VHs) for assessing health care communication, evidence of validity is limited. We evaluated the validity of a VH application, MPathic-VR, for assessing performance-based competence in breaking bad news (BBN) to a VH patient. We used a two-group quasi-experimental design, with residents participating in a 3-hour seminar on BBN. Group A (n=15) completed the VH simulation before and after the seminar, and Group B (n=12) completed the VH simulation only after the BBN seminar to avoid the possibility that testing alone affected performance. Pre- and postseminar differences for Group A were analyzed with a paired t -test, and comparisons between Groups A and B were analyzed with an independent t -test. Compared to the preseminar result, Group A's postseminar scores improved significantly, indicating that the VH program was sensitive to differences in assessing performance-based competence in BBN. Postseminar scores of Group A and Group B were not significantly different, indicating that both groups performed similarly on the VH program. Improved pre-post scores demonstrate acquisition of skills in BBN to a VH patient. Pretest sensitization did not appear to influence posttest assessment. These results provide initial construct validity evidence that the VH program is effective for assessing BBN performance-based communication competence.

Initial construct validity evidence of a virtual human application for competency assessment in breaking bad news to a cancer patient

PubMed Central

Guetterman, Timothy C; Kron, Frederick W; Campbell, Toby C; Scerbo, Mark W; Zelenski, Amy B; Cleary, James F; Fetters, Michael D

2017-01-01

Background Despite interest in using virtual humans (VHs) for assessing health care communication, evidence of validity is limited. We evaluated the validity of a VH application, MPathic-VR, for assessing performance-based competence in breaking bad news (BBN) to a VH patient. Methods We used a two-group quasi-experimental design, with residents participating in a 3-hour seminar on BBN. Group A (n=15) completed the VH simulation before and after the seminar, and Group B (n=12) completed the VH simulation only after the BBN seminar to avoid the possibility that testing alone affected performance. Pre- and postseminar differences for Group A were analyzed with a paired t-test, and comparisons between Groups A and B were analyzed with an independent t-test. Results Compared to the preseminar result, Group A’s postseminar scores improved significantly, indicating that the VH program was sensitive to differences in assessing performance-based competence in BBN. Postseminar scores of Group A and Group B were not significantly different, indicating that both groups performed similarly on the VH program. Conclusion Improved pre–post scores demonstrate acquisition of skills in BBN to a VH patient. Pretest sensitization did not appear to influence posttest assessment. These results provide initial construct validity evidence that the VH program is effective for assessing BBN performance-based communication competence. PMID:28794664

The effect of an intervention to break the gender bias habit for faculty at one institution: a cluster randomized, controlled trial.

PubMed

Carnes, Molly; Devine, Patricia G; Baier Manwell, Linda; Byars-Winston, Angela; Fine, Eve; Ford, Cecilia E; Forscher, Patrick; Isaac, Carol; Kaatz, Anna; Magua, Wairimu; Palta, Mari; Sheridan, Jennifer

2015-02-01

Despite sincere commitment to egalitarian, meritocratic principles, subtle gender bias persists, constraining women's opportunities for academic advancement. The authors implemented a pair-matched, single-blind, cluster randomized, controlled study of a gender-bias-habit-changing intervention at a large public university. Participants were faculty in 92 departments or divisions at the University of Wisconsin-Madison. Between September 2010 and March 2012, experimental departments were offered a gender-bias-habit-changing intervention as a 2.5-hour workshop. Surveys measured gender bias awareness; motivation, self-efficacy, and outcome expectations to reduce bias; and gender equity action. A timed word categorization task measured implicit gender/leadership bias. Faculty completed a work-life survey before and after all experimental departments received the intervention. Control departments were offered workshops after data were collected. Linear mixed-effects models showed significantly greater changes post intervention for faculty in experimental versus control departments on several outcome measures, including self-efficacy to engage in gender-equity-promoting behaviors (P = .013). When ≥ 25% of a department's faculty attended the workshop (26 of 46 departments), significant increases in self-reported action to promote gender equity occurred at three months (P = .007). Post intervention, faculty in experimental departments expressed greater perceptions of fit (P = .024), valuing of their research (P = .019), and comfort in raising personal and professional conflicts (P = .025). An intervention that facilitates intentional behavioral change can help faculty break the gender bias habit and change department climate in ways that should support the career advancement of women in academic medicine, science, and engineering.

(-)-Stepholidine reduces cue-induced reinstatement of cocaine seeking and cocaine self-administration in rats.

PubMed

Manuszak, M; Harding, W; Gadhiya, S; Ranaldi, R

2018-05-31

Dopamine receptors are implicated in cocaine reward and seeking. We hypothesize that (-)-stepholidine, a dopamine D1/D2/D3 multi-receptor agent, would be effective in reducing cocaine reward and seeking in an animal model. We investigated the effects of (-)-stepholidine in cue-induced reinstatement of cocaine seeking and cocaine self-administration (reward). Cue-induced reinstatement experiment: Rats were trained to press a lever reinforced by cocaine (1 mg/kg/injection) for 15 consecutive daily sessions, after which the response was extinguished by withholding cocaine and cocaine-paired cues (light and pump activation). This was followed by a cue-induced reinstatement test where subjects were exposed to two cocaine cue presentations and presses on the active lever produced cues. Subjects were treated with one of four (-)-stepholidine doses prior to the reinstatement test. Cocaine self-administration (reward) experiment: Rats were trained to self-administer cocaine under a progressive ratio schedule of reinforcement. After stable breakpoints were established, rats were injected with four doses of (-)-stepholidine prior to testing; each dose was injected prior to a separate test session with no-treatment sessions intervening to re-establish break points. (-)-Stepholidine significantly reduced cue-induced reinstatement of cocaine seeking in a dose-related manner. Additionally, (-)-stepholidine significantly reduced break points for cocaine reward. (-)-Stepholidine did not significantly affect locomotor activity. (-)-Stepholidine reduces cue-induced reinstatement of cocaine seeking and cocaine reward, suggesting that it may be useful in treating relapse in cocaine addiction. Copyright © 2018 Elsevier B.V. All rights reserved.

Size effects on negative thermal expansion in cubic ScF{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, C.; Guo, X. G.; Zhang, K.

2016-07-11

Scandium trifluoride (ScF{sub 3}), adopting a cubic ReO{sub 3}-type structure at ambient pressure, undergoes a pronounced negative thermal expansion (NTE) over a wide range of temperatures (10 K–1100 K). Here, we report the size effects on the NTE properties of ScF{sub 3}. The magnitude of NTE is reduced with diminishing the crystal size. As revealed by the specific heat measurement, the low-energy phonon vibrations which account for the NTE behavior are stiffened as the crystal size decreases. With decreasing the crystal size, the peaks in high-energy X-ray pair distribution function (PDF) become broad, which cannot be illuminated by local symmetry breaking. Instead,more » the broadened PDF peaks are strongly indicative of enhanced atomic displacements which are suggested to be responsible for the stiffening of NTE-related lattice vibrations. The present study suggests that the NTE properties of ReO{sub 3}-type and other open-framework materials can be effectively adjusted by controlling the crystal size.« less

Activity-rest schedules in physically demanding work and the variation of responses with age.

PubMed

Kakarot, Nadine; Mueller, Friedrich; Bassarak, Claudia

2012-01-01

Workers in physically demanding occupations require work breaks to recover from exertion. In a laboratory setting, we investigated the impact of ergometer cycling for 7 h in two conditions with an identical total break time but with two different activity-rest schedules. We hypothesised that more frequent but shorter breaks lead to less psychophysical strain and its effects than do less frequent but longer breaks, particularly for older workers. Twenty-nine participants representing three different age groups were tested in both conditions. Heart rate, perceived exertion/tension and feelings of fatigue were assessed and used as dependent variables. Results indicate no general activity-rest differences as well as no age-related differences of break effects under the condition of subjectively equal straining load. However, heart rate was found to be lower at some measurement points in the frequent-short-break condition and perceived exertion was lower in the infrequent-long-break condition. Design of activity-rest schedules in physically demanding occupations is a key issue in the prevention of strain and hence of interest to ergonomists. Our study suggests that breaks during physically demanding work have the same effect if they are frequent and short or infrequent and long, regardless of age.

Academic stress disrupts cortical plasticity in graduate students.

PubMed

Concerto, Carmen; Patel, Dhaval; Infortuna, Carmenrita; Chusid, Eileen; Muscatello, Maria R; Bruno, Antonio; Zoccali, Rocco; Aguglia, Eugenio; Battaglia, Fortunato

2017-03-01

Medical education is a time of high stress and anxiety for many graduate students in medical professions. In this study, we sought to investigate the effect of academic stress on cortical excitability and plasticity by using transcranial magnetic stimulation (TMS). We tested two groups (n = 13 each) of healthy graduate medical students (mean age 33.7 ± 3.8 SE). One group was tested during a final exam week (High-stress group) while the other group was tested after a break, during a week without exams (Low-stress group). Students were required to fill the Perceived Stress Scale-10 (PSS) questionnaire. We investigated resting motor threshold (RMT), motor evoked potential (MEP) amplitude and cortical silent period (CSP). The paired-pulse stimulation paradigm was used to assess short interval intracortical inhibition (SICI) and intracortical facilitation (ICF). Long-term potentiation (LTP)-like plasticity was evaluated with paired associative stimulation (PAS-25). There was no between-group difference in cortical excitability. On the contrary, during examination period, levels of perceived stress were significantly higher (p= .036) and the amount of cortical plasticity (60 min after PAS) was significantly lower (p = .029). LTP-like plasticity (60 min after PAS) was inversely correlated with perceived stress in the High-stress group. The present study showed LTP-like plasticity was reduced by examining stress in graduate students. Our results provide a new opportunity to objectively quantify the negative effect of academic and examination stress on brain plasticity.

Thouless-Valatin rotational moment of inertia from linear response theory

NASA Astrophysics Data System (ADS)

Petrík, Kristian; Kortelainen, Markus

2018-03-01

Spontaneous breaking of continuous symmetries of a nuclear many-body system results in the appearance of zero-energy restoration modes. These so-called spurious Nambu-Goldstone modes represent a special case of collective motion and are sources of important information about the Thouless-Valatin inertia. The main purpose of this work is to study the Thouless-Valatin rotational moment of inertia as extracted from the Nambu-Goldstone restoration mode that results from the zero-frequency response to the total-angular-momentum operator. We examine the role and effects of the pairing correlations on the rotational characteristics of heavy deformed nuclei in order to extend our understanding of superfluidity in general. We use the finite-amplitude method of the quasiparticle random-phase approximation on top of the Skyrme energy density functional framework with the Hartree-Fock-Bogoliubov theory. We have successfully extended this formalism and established a practical method for extracting the Thouless-Valatin rotational moment of inertia from the strength function calculated in the symmetry-restoration regime. Our results reveal the relation between the pairing correlations and the moment of inertia of axially deformed nuclei of rare-earth and actinide regions of the nuclear chart. We have also demonstrated the feasibility of the method for obtaining the moment of inertia for collective Hamiltonian models. We conclude that from the numerical and theoretical perspective, the finite-amplitude method can be widely used to effectively study rotational properties of deformed nuclei within modern density functional approaches.

A first-principles study on second-order ferroelectric phase transition in two-dimensional puckered group V materials

NASA Astrophysics Data System (ADS)

Lee, Sang-Hoon; Jhi, Seung-Hoon

We study two-dimensional group V materials (P, As, Sb, and Bi) in puckered honeycomb structure using first-principles calculations. Two factors, the degree of puckering and buckling characterize not only the atomic structure but also the electronic structure and its topological phase. By analyzing the lone-pair character of constituent elements and the softening of the phonon mode, we clarify the origin of the buckling. We show that the phonon softening leads the second-order type structural phase transition from a flat to a buckled configuration. The inversion symmetry breaking associated with the structural transition induces the spontaneous polarization in these homogenous materials. Our calculations suggest that external strains or n-type doping are effective methods to control the degree of buckling. We find that the ferroelectric and non-trivial topological phase can coexist in puckered Bi when tensile strains are applied.

Impact of regular relaxation training on the cardiac autonomic nervous system of hospital cleaners and bank employees.

PubMed

Toivanen, H; Länsimies, E; Jokela, V; Hänninen, O

1993-10-01

The work-related strain of 50 female hospital cleaners and 48 female bank employees was recorded during a period of rationalization in the workplace, and the effect of daily relaxation to help the workers cope was tested. The subjects were arranged into age-matched pairs and randomly allocated into intervention and reference groups. The intervention period lasted six months. The relaxation method was brief and easily introduced as an alternative break in the workplace. Each training session lasted 15 min. A microcomputer-based system was used to record heart rate variability in response to quiet breathing, the Valsalva maneuver, deep breathing, and active orthostatic tests. Cardiac reflexes indicated that occupational strain (especially of a mental nature) caused the functioning of the autonomic nervous system to deteriorate. Regular deep relaxation normalized the function and improved the ability to cope.

CRISPR-Cas9; an efficient tool for precise plant genome editing.

PubMed

Islam, Waqar

2018-06-01

Efficient plant genome editing is dependent upon induction of double stranded DNA breaks (DSBs) through site specified nucleases. These DSBs initiate the process of DNA repair which can either base upon homologous recombination (HR) or non-homologous end jointing (NHEJ). Recently, CRISPR-Cas9 mechanism got highlighted as revolutionizing genetic tool due to its simpler frame work along with the broad range of adaptability and applications. So, in this review, I have tried to sum up the application of this biotechnological tool in plant genome editing. Furthermore, I have tried to explain successful adaptation of CRISPR in various plant species where it is used for the successful generation of stable mutations in a steadily growing number of species through NHEJ. The review also sheds light upon other biotechnological approaches relying upon single DNA lesion induction such as genomic deletion or pair wise nickases for evasion of offsite effects. Copyright © 2018 Elsevier Ltd. All rights reserved.

Phase-breaking effect on polaron transport in organic conjugated polymers

DOE PAGES

Meng, Ruixuan; Yin, Sun; Zheng, Yujun; ...

2017-06-15

Despite intense investigations and many accepted viewpoints on theory and experiment, the coherent and incoherent carrier transport in organic semiconductors remains an unsettled topic due to the strong electron-phonon coupling. Based on the tight-binding Su-Schrieffer-Heeger (SSH) model combined with a non-adiabatic dynamics method, we study the effect of phase-breaking on polaron transport by introducing a group of phase-breaking factors into π-electron wave-functions in organic conjugated polymers. Two approaches are applied: the modification of the transfer integral and the phase-breaking addition to the wave-function. Within the former, it is found that a single site phase-breaking can trap a polaron. However, withmore » a larger regular phase-breaking a polaron becomes more delocalized and lighter. Additionally, a group of disordered phase-breaking factors can make the polaron disperse in transport process. Within the latter approach, we show that the phase-breaking can render the delocalized state in valence band discrete and the state in the gap more localized. Consequently, the phase-breaking frequency and intensity can reduce the stability of a polaron. Furthermore, the phase-breaking in organic systems is the main factor that degrades the coherent transport and destroys the carrier stability.« less

Phase-breaking effect on polaron transport in organic conjugated polymers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meng, Ruixuan; Yin, Sun; Zheng, Yujun

Despite intense investigations and many accepted viewpoints on theory and experiment, the coherent and incoherent carrier transport in organic semiconductors remains an unsettled topic due to the strong electron-phonon coupling. Based on the tight-binding Su-Schrieffer-Heeger (SSH) model combined with a non-adiabatic dynamics method, we study the effect of phase-breaking on polaron transport by introducing a group of phase-breaking factors into π-electron wave-functions in organic conjugated polymers. Two approaches are applied: the modification of the transfer integral and the phase-breaking addition to the wave-function. Within the former, it is found that a single site phase-breaking can trap a polaron. However, withmore » a larger regular phase-breaking a polaron becomes more delocalized and lighter. Additionally, a group of disordered phase-breaking factors can make the polaron disperse in transport process. Within the latter approach, we show that the phase-breaking can render the delocalized state in valence band discrete and the state in the gap more localized. Consequently, the phase-breaking frequency and intensity can reduce the stability of a polaron. Furthermore, the phase-breaking in organic systems is the main factor that degrades the coherent transport and destroys the carrier stability.« less

Search for supersymmetry in events with photons and missing transverse energy in pp collisions at 13 TeV

NASA Astrophysics Data System (ADS)

Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Brondolin, E.; Dragicevic, M.; Erö, J.; Flechl, M.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Hartl, C.; Hörmann, N.; Hrubec, J.; Jeitler, M.; König, A.; Krätschmer, I.; Liko, D.; Matsushita, T.; Mikulec, I.; Rabady, D.; Rad, N.; Rahbaran, B.; Rohringer, H.; Schieck, J.; Strauss, J.; Waltenberger, W.; Wulz, C.-E.; Mossolov, V.; Shumeiko, N.; Suarez Gonzalez, J.; Alderweireldt, S.; De Wolf, E. A.; Janssen, X.; Lauwers, J.; Van De Klundert, M.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Abu Zeid, S.; Blekman, F.; D'Hondt, J.; Daci, N.; De Bruyn, I.; Deroover, K.; Heracleous, N.; Lowette, S.; Moortgat, S.; Moreels, L.; Olbrechts, A.; Python, Q.; Tavernier, S.; Van Doninck, W.; Van Mulders, P.; Van Parijs, I.; Brun, H.; Caillol, C.; Clerbaux, B.; De Lentdecker, G.; Delannoy, H.; Fasanella, G.; Favart, L.; Goldouzian, R.; Grebenyuk, A.; Karapostoli, G.; Lenzi, T.; Léonard, A.; Luetic, J.; Maerschalk, T.; Marinov, A.; Randle-conde, A.; Seva, T.; Vander Velde, C.; Vanlaer, P.; Yonamine, R.; Zenoni, F.; Zhang, F.; Cimmino, A.; Cornelis, T.; Dobur, D.; Fagot, A.; Garcia, G.; Gul, M.; Poyraz, D.; Salva, S.; Schöfbeck, R.; Sharma, A.; Tytgat, M.; Van Driessche, W.; Yazgan, E.; Zaganidis, N.; Bakhshiansohi, H.; Beluffi, C.; Bondu, O.; Brochet, S.; Bruno, G.; Caudron, A.; De Visscher, S.; Delaere, C.; Delcourt, M.; Francois, B.; Giammanco, A.; Jafari, A.; Jez, P.; Komm, M.; Lemaitre, V.; Magitteri, A.; Mertens, A.; Musich, M.; Nuttens, C.; Piotrzkowski, K.; Quertenmont, L.; Selvaggi, M.; Vidal Marono, M.; Wertz, S.; Beliy, N.; Aldá Júnior, W. L.; Alves, F. L.; Alves, G. A.; Brito, L.; Hensel, C.; Moraes, A.; Pol, M. E.; Rebello Teles, P.; Belchior Batista Das Chagas, E.; Carvalho, W.; Chinellato, J.; Custódio, A.; Da Costa, E. M.; Da Silveira, G. G.; De Jesus Damiao, D.; De Oliveira Martins, C.; Fonseca De Souza, S.; Huertas Guativa, L. M.; Malbouisson, H.; Matos Figueiredo, D.; Mora Herrera, C.; Mundim, L.; Nogima, H.; Prado Da Silva, W. L.; Santoro, A.; Sznajder, A.; Tonelli Manganote, E. J.; Vilela Pereira, A.; Ahuja, S.; Bernardes, C. A.; Dogra, S.; Fernandez Perez Tomei, T. R.; Gregores, E. M.; Mercadante, P. G.; Moon, C. S.; Novaes, S. F.; Padula, Sandra S.; Romero Abad, D.; Ruiz Vargas, J. C.; Aleksandrov, A.; Hadjiiska, R.; Iaydjiev, P.; Rodozov, M.; Stoykova, S.; Sultanov, G.; Vutova, M.; Dimitrov, A.; Glushkov, I.; Litov, L.; Pavlov, B.; Petkov, P.; Fang, W.; Ahmad, M.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Chen, M.; Chen, Y.; Cheng, T.; Jiang, C. H.; Leggat, D.; Liu, Z.; Romeo, F.; Shaheen, S. M.; Spiezia, A.; Tao, J.; Wang, C.; Wang, Z.; Zhang, H.; Zhao, J.; Ban, Y.; Chen, G.; Li, Q.; Liu, S.; Mao, Y.; Qian, S. J.; Wang, D.; Xu, Z.; Avila, C.; Cabrera, A.; Chaparro Sierra, L. F.; Florez, C.; Gomez, J. P.; González Hernández, C. F.; Ruiz Alvarez, J. D.; Sanabria, J. C.; Godinovic, N.; Lelas, D.; Puljak, I.; Ribeiro Cipriano, P. M.; Sculac, T.; Antunovic, Z.; Kovac, M.; Brigljevic, V.; Ferencek, D.; Kadija, K.; Micanovic, S.; Sudic, L.; Susa, T.; Attikis, A.; Mavromanolakis, G.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Rykaczewski, H.; Finger, M.; Finger, M.; Carrera Jarrin, E.; Abdelalim, A. A.; Mohammed, Y.; Salama, E.; Calpas, B.; Kadastik, M.; Murumaa, M.; Perrini, L.; Raidal, M.; Tiko, A.; Veelken, C.; Eerola, P.; Pekkanen, J.; Voutilainen, M.; Härkönen, J.; Karimäki, V.; Kinnunen, R.; Lampén, T.; Lassila-Perini, K.; Lehti, S.; Lindén, T.; Luukka, P.; Tuominiemi, J.; Tuovinen, E.; Wendland, L.; Talvitie, J.; Tuuva, T.; Besancon, M.; Couderc, F.; Dejardin, M.; Denegri, D.; Fabbro, B.; Faure, J. L.; Favaro, C.; Ferri, F.; Ganjour, S.; Ghosh, S.; Givernaud, A.; Gras, P.; Hamel de Monchenault, G.; Jarry, P.; Kucher, I.; Locci, E.; Machet, M.; Malcles, J.; Rander, J.; Rosowsky, A.; Titov, M.; Zghiche, A.; Abdulsalam, A.; Antropov, I.; Baffioni, S.; Beaudette, F.; Busson, P.; Cadamuro, L.; Chapon, E.; Charlot, C.; Davignon, O.; Granier de Cassagnac, R.; Jo, M.; Lisniak, S.; Miné, P.; Nguyen, M.; Ochando, C.; Ortona, G.; Paganini, P.; Pigard, P.; Regnard, S.; Salerno, R.; Sirois, Y.; Strebler, T.; Yilmaz, Y.; Zabi, A.; Agram, J.-L.; Andrea, J.; Aubin, A.; Bloch, D.; Brom, J.-M.; Buttignol, M.; Chabert, E. C.; Chanon, N.; Collard, C.; Conte, E.; Coubez, X.; Fontaine, J.-C.; Gelé, D.; Goerlach, U.; Le Bihan, A.-C.; Skovpen, K.; Van Hove, P.; Gadrat, S.; Beauceron, S.; Bernet, C.; Boudoul, G.; Bouvier, E.; Carrillo Montoya, C. A.; Chierici, R.; Contardo, D.; Courbon, B.; Depasse, P.; El Mamouni, H.; Fan, J.; Fay, J.; Gascon, S.; Gouzevitch, M.; Grenier, G.; Ille, B.; Lagarde, F.; Laktineh, I. B.; Lethuillier, M.; Mirabito, L.; Pequegnot, A. L.; Perries, S.; Popov, A.; Sabes, D.; Sordini, V.; Vander Donckt, M.; Verdier, P.; Viret, S.; Khvedelidze, A.; Tsamalaidze, Z.; Autermann, C.; Beranek, S.; Feld, L.; Heister, A.; Kiesel, M. K.; Klein, K.; Lipinski, M.; Ostapchuk, A.; Preuten, M.; Raupach, F.; Schael, S.; Schomakers, C.; Schulz, J.; Verlage, T.; Weber, H.; Zhukov, V.; Albert, A.; Brodski, M.; Dietz-Laursonn, E.; Duchardt, D.; Endres, M.; Erdmann, M.; Erdweg, S.; Esch, T.; Fischer, R.; Güth, A.; Hamer, M.; Hebbeker, T.; Heidemann, C.; Hoepfner, K.; Knutzen, S.; Merschmeyer, M.; Meyer, A.; Millet, P.; Mukherjee, S.; Olschewski, M.; Padeken, K.; Pook, T.; Radziej, M.; Reithler, H.; Rieger, M.; Scheuch, F.; Sonnenschein, L.; Teyssier, D.; Thüer, S.; Cherepanov, V.; Flügge, G.; Hoehle, F.; Kargoll, B.; Kress, T.; Künsken, A.; Lingemann, J.; Müller, T.; Nehrkorn, A.; Nowack, A.; Nugent, I. M.; Pistone, C.; Pooth, O.; Stahl, A.; Aldaya Martin, M.; Arndt, T.; Asawatangtrakuldee, C.; Beernaert, K.; Behnke, O.; Behrens, U.; Bin Anuar, A. A.; Borras, K.; Campbell, A.; Connor, P.; Contreras-Campana, C.; Costanza, F.; Diez Pardos, C.; Dolinska, G.; Eckerlin, G.; Eckstein, D.; Eichhorn, T.; Eren, E.; Gallo, E.; Garay Garcia, J.; Geiser, A.; Gizhko, A.; Grados Luyando, J. M.; Gunnellini, P.; Harb, A.; Hauk, J.; Hempel, M.; Jung, H.; Kalogeropoulos, A.; Karacheban, O.; Kasemann, M.; Keaveney, J.; Kleinwort, C.; Korol, I.; Krücker, D.; Lange, W.; Lelek, A.; Leonard, J.; Lipka, K.; Lobanov, A.; Lohmann, W.; Mankel, R.; Melzer-Pellmann, I.-A.; Meyer, A. B.; Mittag, G.; Mnich, J.; Mussgiller, A.; Ntomari, E.; Pitzl, D.; Placakyte, R.; Raspereza, A.; Roland, B.; Sahin, M. Ö.; Saxena, P.; Schoerner-Sadenius, T.; Seitz, C.; Spannagel, S.; Stefaniuk, N.; Van Onsem, G. P.; Walsh, R.; Wissing, C.; Blobel, V.; Centis Vignali, M.; Draeger, A. R.; Dreyer, T.; Garutti, E.; Gonzalez, D.; Haller, J.; Hoffmann, M.; Junkes, A.; Klanner, R.; Kogler, R.; Kovalchuk, N.; Lapsien, T.; Lenz, T.; Marchesini, I.; Marconi, D.; Meyer, M.; Niedziela, M.; Nowatschin, D.; Pantaleo, F.; Peiffer, T.; Perieanu, A.; Poehlsen, J.; Sander, C.; Scharf, C.; Schleper, P.; Schmidt, A.; Schumann, S.; Schwandt, J.; Stadie, H.; Steinbrück, G.; Stober, F. M.; Stöver, M.; Tholen, H.; Troendle, D.; Usai, E.; Vanelderen, L.; Vanhoefer, A.; Vormwald, B.; Barth, C.; Baus, C.; Berger, J.; Butz, E.; Chwalek, T.; Colombo, F.; De Boer, W.; Dierlamm, A.; Fink, S.; Friese, R.; Giffels, M.; Gilbert, A.; Goldenzweig, P.; Haitz, D.; Hartmann, F.; Heindl, S. M.; Husemann, U.; Katkov, I.; Lobelle Pardo, P.; Maier, B.; Mildner, H.; Mozer, M. U.; Müller, Th.; Plagge, M.; Quast, G.; Rabbertz, K.; Röcker, S.; Roscher, F.; Schröder, M.; Shvetsov, I.; Sieber, G.; Simonis, H. J.; Ulrich, R.; Wagner-Kuhr, J.; Wayand, S.; Weber, M.; Weiler, T.; Williamson, S.; Wöhrmann, C.; Wolf, R.; Anagnostou, G.; Daskalakis, G.; Geralis, T.; Giakoumopoulou, V. A.; Kyriakis, A.; Loukas, D.; Topsis-Giotis, I.; Kesisoglou, S.; Panagiotou, A.; Saoulidou, N.; Tziaferi, E.; Evangelou, I.; Flouris, G.; Foudas, C.; Kokkas, P.; Loukas, N.; Manthos, N.; Papadopoulos, I.; Paradas, E.; Filipovic, N.; Bencze, G.; Hajdu, C.; Hidas, P.; Horvath, D.; Sikler, F.; Veszpremi, V.; Vesztergombi, G.; Zsigmond, A. J.; Beni, N.; Czellar, S.; Karancsi, J.; Makovec, A.; Molnar, J.; Szillasi, Z.; Bartók, M.; Raics, P.; Trocsanyi, Z. L.; Ujvari, B.; Bahinipati, S.; Choudhury, S.; Mal, P.; Mandal, K.; Nayak, A.; Sahoo, D. K.; Sahoo, N.; Swain, S. K.; Bansal, S.; Beri, S. B.; Bhatnagar, V.; Chawla, R.; Bhawandeep, U.; Kalsi, A. K.; Kaur, A.; Kaur, M.; Kumar, R.; Kumari, P.; Mehta, A.; Mittal, M.; Singh, J. B.; Walia, G.; Kumar, Ashok; Bhardwaj, A.; Choudhary, B. C.; Garg, R. B.; Keshri, S.; Malhotra, S.; Naimuddin, M.; Nishu, N.; Ranjan, K.; Sharma, R.; Sharma, V.; Bhattacharya, R.; Bhattacharya, S.; Chatterjee, K.; Dey, S.; Dutt, S.; Dutta, S.; Ghosh, S.; Majumdar, N.; Modak, A.; Mondal, K.; Mukhopadhyay, S.; Nandan, S.; Purohit, A.; Roy, A.; Roy, D.; Roy Chowdhury, S.; Sarkar, S.; Sharan, M.; Thakur, S.; Behera, P. K.; Chudasama, R.; Dutta, D.; Jha, V.; Kumar, V.; Mohanty, A. K.; Netrakanti, P. K.; Pant, L. M.; Shukla, P.; Topkar, A.; Aziz, T.; Dugad, S.; Kole, G.; Mahakud, B.; Mitra, S.; Mohanty, G. B.; Parida, B.; Sur, N.; Sutar, B.; Banerjee, S.; Bhowmik, S.; Dewanjee, R. K.; Ganguly, S.; Guchait, M.; Jain, Sa.; Kumar, S.; Maity, M.; Majumder, G.; Mazumdar, K.; Sarkar, T.; Wickramage, N.; Chauhan, S.; Dube, S.; Hegde, V.; Kapoor, A.; Kothekar, K.; Rane, A.; Sharma, S.; Behnamian, H.; Chenarani, S.; Eskandari Tadavani, E.; Etesami, S. M.; Fahim, A.; Khakzad, M.; Mohammadi Najafabadi, M.; Naseri, M.; Paktinat Mehdiabadi, S.; Rezaei Hosseinabadi, F.; Safarzadeh, B.; Zeinali, M.; Felcini, M.; Grunewald, M.; Abbrescia, M.; Calabria, C.; Caputo, C.; Colaleo, A.; Creanza, D.; Cristella, L.; De Filippis, N.; De Palma, M.; Fiore, L.; Iaselli, G.; Maggi, G.; Maggi, M.; Miniello, G.; My, S.; Nuzzo, S.; Pompili, A.; Pugliese, G.; Radogna, R.; Ranieri, A.; Selvaggi, G.; Silvestris, L.; Venditti, R.; Verwilligen, P.; Abbiendi, G.; Battilana, C.; Bonacorsi, D.; Braibant-Giacomelli, S.; Brigliadori, L.; Campanini, R.; Capiluppi, P.; Castro, A.; Cavallo, F. R.; Chhibra, S. S.; Codispoti, G.; Cuffiani, M.; Dallavalle, G. M.; Fabbri, F.; Fanfani, A.; Fasanella, D.; Giacomelli, P.; Grandi, C.; Guiducci, L.; Marcellini, S.; Masetti, G.; Montanari, A.; Navarria, F. L.; Perrotta, A.; Rossi, A. M.; Rovelli, T.; Siroli, G. P.; Tosi, N.; Albergo, S.; Chiorboli, M.; Costa, S.; Di Mattia, A.; Giordano, F.; Potenza, R.; Tricomi, A.; Tuve, C.; Barbagli, G.; Ciulli, V.; Civinini, C.; D'Alessandro, R.; Focardi, E.; Gori, V.; Lenzi, P.; Meschini, M.; Paoletti, S.; Sguazzoni, G.; Viliani, L.; Benussi, L.; Bianco, S.; Fabbri, F.; Piccolo, D.; Primavera, F.; Calvelli, V.; Ferro, F.; Lo Vetere, M.; Monge, M. R.; Robutti, E.; Tosi, S.; Brianza, L.; Dinardo, M. E.; Fiorendi, S.; Gennai, S.; Ghezzi, A.; Govoni, P.; Malberti, M.; Malvezzi, S.; Manzoni, R. A.; Menasce, D.; Moroni, L.; Paganoni, M.; Pedrini, D.; Pigazzini, S.; Ragazzi, S.; Tabarelli de Fatis, T.; Buontempo, S.; Cavallo, N.; De Nardo, G.; Di Guida, S.; Esposito, M.; Fabozzi, F.; Fienga, F.; Iorio, A. O. M.; Lanza, G.; Lista, L.; Meola, S.; Paolucci, P.; Sciacca, C.; Thyssen, F.; Azzi, P.; Bacchetta, N.; Benato, L.; Bisello, D.; Boletti, A.; Carlin, R.; Carvalho Antunes De Oliveira, A.; Checchia, P.; Dall'Osso, M.; De Castro Manzano, P.; Dorigo, T.; Dosselli, U.; Gasparini, F.; Gasparini, U.; Gozzelino, A.; Lacaprara, S.; Margoni, M.; Meneguzzo, A. T.; Pazzini, J.; Pozzobon, N.; Ronchese, P.; Simonetto, F.; Torassa, E.; Zanetti, M.; Zotto, P.; Zumerle, G.; Braghieri, A.; Magnani, A.; Montagna, P.; Ratti, S. P.; Re, V.; Riccardi, C.; Salvini, P.; Vai, I.; Vitulo, P.; Alunni Solestizi, L.; Bilei, G. M.; Ciangottini, D.; Fanò, L.; Lariccia, P.; Leonardi, R.; Mantovani, G.; Menichelli, M.; Saha, A.; Santocchia, A.; Androsov, K.; Azzurri, P.; Bagliesi, G.; Bernardini, J.; Boccali, T.; Castaldi, R.; Ciocci, M. A.; Dell'Orso, R.; Donato, S.; Fedi, G.; Giassi, A.; Grippo, M. T.; Ligabue, F.; Lomtadze, T.; Martini, L.; Messineo, A.; Palla, F.; Rizzi, A.; Savoy-Navarro, A.; Spagnolo, P.; Tenchini, R.; Tonelli, G.; Venturi, A.; Verdini, P. G.; Barone, L.; Cavallari, F.; Cipriani, M.; D'imperio, G.; Del Re, D.; Diemoz, M.; Gelli, S.; Longo, E.; Margaroli, F.; Marzocchi, B.; Meridiani, P.; Organtini, G.; Paramatti, R.; Preiato, F.; Rahatlou, S.; Rovelli, C.; Santanastasio, F.; Amapane, N.; Arcidiacono, R.; Argiro, S.; Arneodo, M.; Bartosik, N.; Bellan, R.; Biino, C.; Cartiglia, N.; Cenna, F.; Costa, M.; Covarelli, R.; Degano, A.; Demaria, N.; Finco, L.; Kiani, B.; Mariotti, C.; Maselli, S.; Migliore, E.; Monaco, V.; Monteil, E.; Obertino, M. M.; Pacher, L.; Pastrone, N.; Pelliccioni, M.; Pinna Angioni, G. L.; Ravera, F.; Romero, A.; Ruspa, M.; Sacchi, R.; Shchelina, K.; Sola, V.; Solano, A.; Staiano, A.; Traczyk, P.; Belforte, S.; Casarsa, M.; Cossutti, F.; Della Ricca, G.; Zanetti, A.; Kim, D. H.; Kim, G. N.; Kim, M. S.; Lee, S.; Lee, S. W.; Oh, Y. 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F.; Mucia, N.; Odell, N.; Pollack, B.; Schmitt, M. H.; Sung, K.; Trovato, M.; Velasco, M.; Dev, N.; Hildreth, M.; Hurtado Anampa, K.; Jessop, C.; Karmgard, D. J.; Kellams, N.; Lannon, K.; Marinelli, N.; Meng, F.; Mueller, C.; Musienko, Y.; Planer, M.; Reinsvold, A.; Ruchti, R.; Smith, G.; Taroni, S.; Wayne, M.; Wolf, M.; Woodard, A.; Alimena, J.; Antonelli, L.; Brinson, J.; Bylsma, B.; Durkin, L. S.; Flowers, S.; Francis, B.; Hart, A.; Hill, C.; Hughes, R.; Ji, W.; Liu, B.; Luo, W.; Puigh, D.; Winer, B. L.; Wulsin, H. W.; Cooperstein, S.; Driga, O.; Elmer, P.; Hardenbrook, J.; Hebda, P.; Lange, D.; Luo, J.; Marlow, D.; Medvedeva, T.; Mei, K.; Mooney, M.; Olsen, J.; Palmer, C.; Piroué, P.; Stickland, D.; Tully, C.; Zuranski, A.; Malik, S.; Barker, A.; Barnes, V. E.; Folgueras, S.; Gutay, L.; Jha, M. K.; Jones, M.; Jung, A. W.; Miller, D. H.; Neumeister, N.; Schulte, J. F.; Shi, X.; Sun, J.; Svyatkovskiy, A.; Wang, F.; Xie, W.; Xu, L.; Parashar, N.; Stupak, J.; Adair, A.; Akgun, B.; Chen, Z.; Ecklund, K. M.; Geurts, F. J. M.; Guilbaud, M.; Li, W.; Michlin, B.; Northup, M.; Padley, B. P.; Redjimi, R.; Roberts, J.; Rorie, J.; Tu, Z.; Zabel, J.; Betchart, B.; Bodek, A.; de Barbaro, P.; Demina, R.; Duh, Y. t.; Ferbel, T.; Galanti, M.; Garcia-Bellido, A.; Han, J.; Hindrichs, O.; Khukhunaishvili, A.; Lo, K. H.; Tan, P.; Verzetti, M.; Agapitos, A.; Chou, J. P.; Contreras-Campana, E.; Gershtein, Y.; Gómez Espinosa, T. A.; Halkiadakis, E.; Heindl, M.; Hidas, D.; Hughes, E.; Kaplan, S.; Kunnawalkam Elayavalli, R.; Kyriacou, S.; Lath, A.; Nash, K.; Saka, H.; Salur, S.; Schnetzer, S.; Sheffield, D.; Somalwar, S.; Stone, R.; Thomas, S.; Thomassen, P.; Walker, M.; Delannoy, A. G.; Foerster, M.; Heideman, J.; Riley, G.; Rose, K.; Spanier, S.; Thapa, K.; Bouhali, O.; Celik, A.; Dalchenko, M.; De Mattia, M.; Delgado, A.; Dildick, S.; Eusebi, R.; Gilmore, J.; Huang, T.; Juska, E.; Kamon, T.; Mueller, R.; Pakhotin, Y.; Patel, R.; Perloff, A.; Perniè, L.; Rathjens, D.; Rose, A.; Safonov, A.; Tatarinov, A.; Ulmer, K. A.; Akchurin, N.; Cowden, C.; Damgov, J.; De Guio, F.; Dragoiu, C.; Dudero, P. R.; Faulkner, J.; Gurpinar, E.; Kunori, S.; Lamichhane, K.; Lee, S. W.; Libeiro, T.; Peltola, T.; Undleeb, S.; Volobouev, I.; Wang, Z.; Greene, S.; Gurrola, A.; Janjam, R.; Johns, W.; Maguire, C.; Melo, A.; Ni, H.; Sheldon, P.; Tuo, S.; Velkovska, J.; Xu, Q.; Arenton, M. W.; Barria, P.; Cox, B.; Goodell, J.; Hirosky, R.; Ledovskoy, A.; Li, H.; Neu, C.; Sinthuprasith, T.; Sun, X.; Wang, Y.; Wolfe, E.; Xia, F.; Clarke, C.; Harr, R.; Karchin, P. E.; Sturdy, J.; Belknap, D. A.; Dasu, S.; Dodd, L.; Duric, S.; Gomber, B.; Grothe, M.; Herndon, M.; Hervé, A.; Klabbers, P.; Lanaro, A.; Levine, A.; Long, K.; Loveless, R.; Ojalvo, I.; Perry, T.; Pierro, G. A.; Polese, G.; Ruggles, T.; Savin, A.; Smith, N.; Smith, W. H.; Taylor, D.; Woods, N.; CMS Collaboration

2017-06-01

The results of a search for new physics in final states with photons and missing transverse energy are reported. The study is based on a sample of proton-proton collisions collected at a center-of-mass energy of 13 TeV with the CMS detector in 2015, corresponding to an integrated luminosity of 2.3 fb-1. Final states with two photons and significant missing transverse energy are used to search for supersymmetric particles in models of supersymmetry (SUSY) with general gauge-mediated (GGM) supersymmetry breaking. No excess is observed with respect to the standard model expectation, and the results are used to set limits on gluino pair production and squark pair production in the GGM SUSY framework. Gluino masses below 1.65 TeV and squark masses below 1.37 TeV are excluded at a 95% confidence level.

Search for supersymmetry in events with photons and missing transverse energy in pp collisions at 13 TeV

DOE PAGES

Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; ...

2017-04-07

Results of a search for new physics in final states with photons and missing transverse energy are reported. The study is based on a sample of proton–proton collisions collected at a center-of-mass energy of 13 TeV with the CMS detector in 2015, corresponding to an integrated luminosity of 2.3 fb -1. Final states with two photons and significant missing transverse energy are used to search for supersymmetric particles in models of supersymmetry (SUSY) with general gauge-mediated (GGM) supersymmetry breaking. We did not observe an excess with respect to the standard model expectation, and the results are used to set limitsmore » on gluino pair production and squark pair production in the GGM SUSY framework. Gluino masses below 1.65 TeV and squark masses below 1.37 TeV are excluded at a 95% confidence level.« less

Friedberg-Lee symmetry and tribimaximal neutrino mixing in the inverse seesaw mechanism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chan, A.H.; Institute of Advanced Studies, Nanyang Technological University, Singapore 639673; Department of Physics, National University of Singapore, Singapore 117542

2009-10-01

The inverse seesaw mechanism with three pairs of gauge-singlet neutrinos offers a natural interpretation of the tiny masses of three active neutrinos at the TeV scale. We combine this picture with the newly proposed Friedberg-Lee (FL) symmetry in order to understand the observed pattern of neutrino mixing. We show that the FL symmetry requires only two pairs of the gauge-singlet neutrinos to be massive, implying that one active neutrino must be massless. We propose a phenomenological ansatz with broken FL symmetry and exact {mu}-{tau} symmetry in the gauge-singlet neutrino sector, and obtain the tribimaximal neutrino mixing pattern by means ofmore » the inverse seesaw relation. We demonstrate that nonunitary corrections to this result can possibly reach the percent level, and a soft breaking of {mu}-{tau} symmetry can give rise to CP violation in such a TeV-scale seesaw scenario.« less

Counteranion Driven Homochiral Assembly of a Cationic C3-Symmetric Gelator through Ion-Pair Assisted Hydrogen Bond.

PubMed

Maity, Arunava; Gangopadhyay, Monalisa; Basu, Arghya; Aute, Sunil; Babu, Sukumaran Santhosh; Das, Amitava

2016-09-07

The helical handedness in achiral self-assemblies is mostly complex due to spontaneous symmetry breaking or kinetically controlled random assembly formation. Here an attempt has been made to address this issue through chiral anion exchange. A new class of cationic achiral C3-symmetric gelator devoid of any conventional gelation assisting functional units is found to form both right- and left-handed helical structures. A chiral counteranion exchange-assisted approach is successfully introduced to control the chirality sign and thereby to obtain preferred homochiral assemblies. Formation of anion-assisted chiral assembly was confirmed by circular dichroism (CD) spectroscopy, microscopic images, and crystal structure. The X-ray crystal structure reveals the construction of helical assemblies with opposite handedness for (+)- and (-)-chiral anion reformed gelators. The appropriate counteranion driven ion-pair-assisted hydrogen-bonding interactions are found responsible for the helical bias control in this C3-symmetric gelator.

Bosonic Confinement and Coherence in Disordered Nanodiamond Arrays.

PubMed

Zhang, Gufei; Samuely, Tomas; Du, Hongchu; Xu, Zheng; Liu, Liwang; Onufriienko, Oleksandr; May, Paul W; Vanacken, Johan; Szabó, Pavol; Kačmarčík, Jozef; Yuan, Haifeng; Samuely, Peter; Dunin-Borkowski, Rafal E; Hofkens, Johan; Moshchalkov, Victor V

2017-11-28

In the presence of disorder, superconductivity exhibits short-range characteristics linked to localized Cooper pairs which are responsible for anomalous phase transitions and the emergence of quantum states such as the bosonic insulating state. Complementary to well-studied homogeneously disordered superconductors, superconductor-normal hybrid arrays provide tunable realizations of the degree of granular disorder for studying anomalous quantum phase transitions. Here, we investigate the superconductor-bosonic dirty metal transition in disordered nanodiamond arrays as a function of the dispersion of intergrain spacing, which ranges from angstroms to micrometers. By monitoring the evolved superconducting gaps and diminished coherence peaks in the single-quasiparticle density of states, we link the destruction of the superconducting state and the emergence of bosonic dirty metallic state to breaking of the global phase coherence and persistence of the localized Cooper pairs. The observed resistive bosonic phase transitions are well modeled using a series-parallel circuit in the framework of bosonic confinement and coherence.

Retrofitting and the mu Problem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Green, Daniel; Weigand, Timo; /SLAC /Stanford U., Phys. Dept.

2010-08-26

One of the challenges of supersymmetry (SUSY) breaking and mediation is generating a {mu} term consistent with the requirements of electro-weak symmetry breaking. The most common approach to the problem is to generate the {mu} term through a SUSY breaking F-term. Often these models produce unacceptably large B{mu} terms as a result. We will present an alternate approach, where the {mu} term is generated directly by non-perturtative effects. The same non-perturbative effect will also retrofit the model of SUSY breaking in such a way that {mu} is at the same scale as masses of the Standard Model superpartners. Because themore » {mu} term is not directly generated by SUSY breaking effects, there is no associated B{mu} problem. These results are demonstrated in a toy model where a stringy instanton generates {mu}.« less

Dose--response of initial G2-chromatid breaks induced in normal human fibroblasts by heavy ions

NASA Technical Reports Server (NTRS)

Kawata, T.; Durante, M.; Furusawa, Y.; George, K.; Takai, N.; Wu, H.; Cucinotta, F. A.; Dicello, J. F. (Principal Investigator)

2001-01-01

PURPOSE: To investigate initial chromatid breaks in prematurely condensed G2 chromosomes following exposure to heavy ions of different LET. MATERIAL AND METHODS: Exponentially growing human fibroblast cells AG1522 were irradiated with gamma-rays, energetic carbon (13 keV/ microm, 80 keV/microm), silicon (55 keV/microm) and iron (140 keV/microm, 185keV/microm, 440keV/microm) ions. Chromosomes were prematurely condensed using calyculin-A. Initial chromatid-type and isochromatid breaks in G2 cells were scored. RESULTS: The dose response curves for total chromatid breaks were linear regardless of radiation type. The relative biological effectiveness (RBE) showed a LET-dependent increase, peaking around 2.7 at 55-80keV/microm and decreasing at higher LET. The dose response curves for isochromatid-type breaks were linear for high-LET radiations, but linear-quadratic for gamma-rays and 13 keV/microm carbon ions. The RBE for the induction of isochromatid breaks obtained from linear components increased rapidly between 13keV/microm (about 7) and 80keV/microm carbon (about 71), and decreased gradually until 440 keV/microm iron ions (about 66). CONCLUSIONS: High-LET radiations are more effective at inducing isochromatid breaks, while low-LET radiations are more effective at inducing chromatid-type breaks. The densely ionizing track structures of heavy ions and the proximity of sister chromatids in G2 cells result in an increase in isochromatid breaks.

To Break or Not To Break: Sex Chromosome Hemizygosity During Meiosis in Caenorhabditis.

PubMed

Van, Mike V; Larson, Braden J; Engebrecht, JoAnne

2016-11-01

Meiotic recombination establishes connections between homologous chromosomes to promote segregation. Hemizygous regions of sex chromosomes have no homologous chromosome to recombine with, yet must be transmitted through meiosis. An extreme case of hemizygosity exists in the genus Caenorhabditis, where males have a single X chromosome that completely lacks a homologous partner. To determine whether similar strategies have evolved to accommodate hemizygosity of the X during male meiosis in Caenorhabditis with distinct modes of sexual reproduction, we examined induction and processing of meiotic double strand breaks (DSBs) in androdioecious (hermaphrodite/male) Caenorhabditis elegans and C. briggsae, and gonochoristic (female/male) C. remanei and C. brenneri Analysis of the recombinase RAD-51 suggests more meiotic DSBs are induced in gonochoristic vs. androdioecious species. However, in late prophase in all species, chromosome pairs are restructured into bivalents around a single axis, suggesting that the holocentric nature of Caenorhabditis chromosomes dictates a single crossover per bivalent regardless of the number of DSBs induced. Interestingly, RAD-51 foci were readily observed on the X chromosome of androdioecious male germ cells, while very few were detected in gonochoristic male germ cells. As in C. elegans, the X chromosome in C. briggsae male germ cells undergoes transient pseudosynapsis and flexibility in DSB repair pathway choice. In contrast, in C. remanei and C. brenneri male germ cells, the X chromosome does not undergo pseudosynapsis and appears refractory to SPO-11-induced breaks. Together our results suggest that distinct strategies have evolved to accommodate sex chromosome hemizygosity during meiosis in closely related Caenorhabditis species. Copyright © 2016 by the Genetics Society of America.

On The Detection Of Footprints From Strong Electron Acceleration In High-Intensity Laser Fields, Including The Unruh Effect

NASA Astrophysics Data System (ADS)

Thirolf, P. G.; Habs, D.; Homma, K.; Hörlein, R.; Karsch, S.; Krausz, F.; Maia, C.; Osterhoff, J.; Popp, A.; Schmid, K.; Schreiber, J.; Schützhold, R.; Tajima, T.; Veisz, L.; Wulz, J.; Yamazaki, T.

2010-04-01

The ultra-high fields of high-power short-pulse lasers are expected to contribute to understanding fundamental properties of the quantum vacuum and quantum theory in very strong fields. For example, the neutral QED vacuum breaks down at the Schwinger field strength of 1.3 1018V/m, where a virtual e+e- pair gains its rest mass energy over a Compton wavelength and materializes as a real pair. At such an ultra-high field strength, an electron experiences an acceleration of as = 2 1028 g and hence fundamental phenomena such as the long predicted Unruh effect start to play a role. The Unruh effect implies that the accelerated electron experiences the vacuum as a thermal bath with the Unruh temperature. In its accelerated frame the electron scatters photons off the thermal bath, corresponding to the emission of an entangled pair of photons in the laboratory frame. In upcoming experiments with intense accelerating fields, we will encounter a set of opportunities to experimentally study the radiation from electrons under extreme fields. Even before the Unruh radiation detection, we should run into the copious Larmor radiation. The detection of Larmor radiation and its characterization themselves have never been experimentally carried out to the best of our knowledge, and thus this amounts to a first serious study of physics at extreme acceleration. For example, we can study radiation damping effects like the Landau-Lifshitz radiation. Furthermore, the experiment should be able to confirm or disprove whether the Larmor and Landau-Lifshitz radiation components may be enhanced by a collective (N2) radiation, if a tightly clumped cluster of electrons is accelerated. The technique of laser driven dense electron sheet formation by irradiating a thin DLC foil target should provide such a coherent electron cluster with a very high density. If and when such mildly relativistic electron sheets are realized, a counterpropagating second laser can interact with them coherently. Under these conditions enhanced Larmor and Unruh radiation signals may be observed. Detection of the Unruh photons (together with its competing radiation components) is envisaged via Compton polarimetry in a novel highly granular 2D-segmented position-sensitive germanium detector.

Heavy-light mesons in chiral AdS/QCD

NASA Astrophysics Data System (ADS)

Liu, Yizhuang; Zahed, Ismail

2017-06-01

We discuss a minimal holographic model for the description of heavy-light and light mesons with chiral symmetry, defined in a slab of AdS space. The model consists of a pair of chiral Yang-Mills and tachyon fields with specific boundary conditions that break spontaneously chiral symmetry in the infrared. The heavy-light spectrum and decay constants are evaluated explicitly. In the heavy mass limit the model exhibits both heavy-quark and chiral symmetry and allows for the explicit derivation of the one-pion axial couplings to the heavy-light mesons.

Turbulence and wave breaking effects on air-water gas exchange

PubMed

Boettcher; Fineberg; Lathrop

2000-08-28

We present an experimental characterization of the effects of turbulence and breaking gravity waves on air-water gas exchange in standing waves. We identify two regimes that govern aeration rates: turbulent transport when no wave breaking occurs and bubble dominated transport when wave breaking occurs. In both regimes, we correlate the qualitative changes in the aeration rate with corresponding changes in the wave dynamics. In the latter regime, the strongly enhanced aeration rate is correlated with measured acoustic emissions, indicating that bubble creation and dynamics dominate air-water exchange.

Period Ratio Distribution of Near-Resonant Planets Indicates Planetesimal Scattering

NASA Astrophysics Data System (ADS)

Chatterjee, Sourav; Krantzler, Seth O.; Ford, Eric B.

2016-10-01

An intriguing trend among it Kepler's multi-planet systems is an overabundance of planet pairs with period ratios just wide of mean motion resonances (MMR) and a dearth of systems just narrow of them. In a recently published paper Chatterjee & Ford (2015; henceforth CF15) has proposed that gas-disk migration traps planets in a MMR. After gas dispersal, orbits of these trapped planets are altered through interaction with a residual planetesimal disk. They found that for massive enough disks planet-planetesimal disk interactions can break resonances and naturally create moderate to large positive offsets from the initial period ratio for large ranges of planetesimal disk and planet properties. Divergence from resonance only happens if the mass of planetesimals that interact with the planets is at least a few percent of the total planet mass. This threshold, above which resonances are broken and the offset from resonances can grow, naturally explains why the asymmetric large offsets were not seen in more massive planet pairs found via past radial velocity surveys. In this article we will highlight some of the key findings of CF15. In addition, we report preliminary results from an extension of this study, that investigates the effects of planet-planetesimal disk interactions on initially non-resonant planet pairs. We find that planetesimal scattering typically increases period ratios of non-resonant planets. If the initial period ratios are below and in proximity of a resonance, under certain conditions, this increment in period ratios can create a deficit of systems with period ratios just below the exact integer corresponding to the MMR and an excess just above. From an initially uniform distribution of period ratios just below a 2:1 MMR, planetesimal interactions can create an asymmetric distribution across this MMR similar to what is observed for the kepler planet pairs.

Spontaneous Symmetry Breaking in Interdependent Networked Game

PubMed Central

Jin, Qing; Wang, Lin; Xia, Cheng-Yi; Wang, Zhen

2014-01-01

Spatial evolution game has traditionally assumed that players interact with direct neighbors on a single network, which is isolated and not influenced by other systems. However, this is not fully consistent with recent research identification that interactions between networks play a crucial rule for the outcome of evolutionary games taking place on them. In this work, we introduce the simple game model into the interdependent networks composed of two networks. By means of imitation dynamics, we display that when the interdependent factor α is smaller than a threshold value αC, the symmetry of cooperation can be guaranteed. Interestingly, as interdependent factor exceeds αC, spontaneous symmetry breaking of fraction of cooperators presents itself between different networks. With respect to the breakage of symmetry, it is induced by asynchronous expansion between heterogeneous strategy couples of both networks, which further enriches the content of spatial reciprocity. Moreover, our results can be well predicted by the strategy-couple pair approximation method. PMID:24526076

Nonadiabatic Josephson current pumping by chiral microwave irradiation

NASA Astrophysics Data System (ADS)

Venitucci, B.; Feinberg, D.; Mélin, R.; Douçot, B.

2018-05-01

Irradiating a Josephson junction with microwaves can operate not only on the amplitude but also on the phase of the Josephson current. This requires breaking time-inversion symmetry, which is achieved by introducing a phase lapse between the microwave components acting on the two sides of the junction. General symmetry arguments and the solution of a specific single-level quantum dot model show that this induces chirality in the Cooper pair dynamics due to the topology of the Andreev bound-state wave function. Another essential condition is to break electron-hole symmetry within the junction. A shift of the current-phase relation is obtained, which is controllable in sign and amplitude with the microwave phase and an electrostatic gate, thus producing a "chiral" Josephson transistor. The dot model is solved in the infinite-gap limit by Floquet theory and in the general case with Keldysh nonequilibrium Green's functions. The chiral current is nonadiabatic: it is extremal and changes sign close to resonant chiral transitions between the Andreev bound states.

Crustal deformation in southern California using SAR interferometry

USGS Publications Warehouse

Peltzer, G.; Rosen, P.; Rogez, F.; Hudnut, K.

1997-01-01

By combining pairs of ERS-1/2 SAR images of Southern California spanning long time intervals (1-4 years), we were able to measure the rate of slow deformation processes along faults activated during the Landers 1992 earthquake. Interferograms revealed several centimeters of post-seismic rebound in step-overs of the 1992 break, with a characteristic decay rate of -280 days. We interpreted this process as due to pore fluid flow as pore pressure gradients caused by coseismic stress changes dissipate. The data also revealed evidence of after-slip on different sections of the fault. The southern branches of the 1992 break experienced surface creep producing sharp phase cuts hi the interferometric maps. The same approach was used in the Los Angeles basin, which is currently undergoing NS shortening at a rate of ???8 mm/yr. The tectonic signal in imerferograms of the Los Angeles basin is intermingled with signals due to other sources such as ground subsidence caused by oil and water withdrawal.

DNA Breaks and End Resection Measured Genome-wide by End Sequencing.

PubMed

Canela, Andres; Sridharan, Sriram; Sciascia, Nicholas; Tubbs, Anthony; Meltzer, Paul; Sleckman, Barry P; Nussenzweig, André

2016-09-01

DNA double-strand breaks (DSBs) arise during physiological transcription, DNA replication, and antigen receptor diversification. Mistargeting or misprocessing of DSBs can result in pathological structural variation and mutation. Here we describe a sensitive method (END-seq) to monitor DNA end resection and DSBs genome-wide at base-pair resolution in vivo. We utilized END-seq to determine the frequency and spectrum of restriction-enzyme-, zinc-finger-nuclease-, and RAG-induced DSBs. Beyond sequence preference, chromatin features dictate the repertoire of these genome-modifying enzymes. END-seq can detect at least one DSB per cell among 10,000 cells not harboring DSBs, and we estimate that up to one out of 60 cells contains off-target RAG cleavage. In addition to site-specific cleavage, we detect DSBs distributed over extended regions during immunoglobulin class-switch recombination. Thus, END-seq provides a snapshot of DNA ends genome-wide, which can be utilized for understanding genome-editing specificities and the influence of chromatin on DSB pathway choice. Published by Elsevier Inc.

Ultrafast Photoinduced Symmetry-Breaking Charge Separation and Electron Sharing in Perylenediimide Molecular Triangles.

PubMed

Wu, Yilei; Young, Ryan M; Frasconi, Marco; Schneebeli, Severin T; Spenst, Peter; Gardner, Daniel M; Brown, Kristen E; Würthner, Frank; Stoddart, J Fraser; Wasielewski, Michael R

2015-10-21

We report on a visible-light-absorbing chiral molecular triangle composed of three covalently linked 1,6,7,12-tetra(phenoxy)perylene-3,4:9,10-bis(dicarboximide) (PDI) units. The rigid triangular architecture reduces the electronic coupling between the PDIs, so ultrafast symmetry-breaking charge separation is kinetically favored over intramolecular excimer formation, as revealed by femtosecond transient absorption spectroscopy. Photoexcitation of the PDI triangle dissolved in CH2Cl2 gives PDI(+•)-PDI(-•) in τCS = 12.0 ± 0.2 ps. Fast subsequent intramolecular electron/hole hopping can equilibrate the six possible energetically degenerate ion-pair states, as suggested by electron paramagnetic resonance/electron-nuclear double resonance spectroscopy, which shows that one-electron reduction of the PDI triangle results in complete electron sharing among the three PDIs. Charge recombination of PDI(+•)-PDI(-•) to the ground state occurs in τCR = 1.12 ± 0.01 ns with no evidence of triplet excited state formation.

The UP4FUN Intervention Effect on Breaking Up Sedentary Time in 10- to 12-Year-Old Belgian Children: The ENERGY-Project.

PubMed

Verloigne, Maïté; Berntsen, Sveinung; Ridgers, Nicola D; Cardon, Greet; Chinapaw, Mai; Altenburg, Teatske; Brug, Johannes; Bere, Elling; De Bourdeaudhuij, Ilse; Van Lippevelde, Wendy; Maes, Lea

2015-05-01

There are currently no studies available reporting intervention effects on breaking up children's sedentary time. This study examined the UP4FUN intervention effect on objectively measured number of breaks in sedentary time, number of sedentary bouts (≥ 10 mins) and total and average amount of time spent in those sedentary bouts among 10- to 12-year-old Belgian children. The total sample included 354 children (mean age: 10.9 ± 0.7 years; 59% girls) with valid ActiGraph accelerometer data at pre- and posttest. Only few and small intervention effects were found, namely on total time spent in sedentary bouts immediately after school hours (4-6PM; β = -3.51mins) and on average time spent in sedentary bouts before school hours (6-8.30AM; β = -4.83mins) and immediately after school hours in favor of children from intervention schools (β = -2.71mins). Unexpectedly, girls from intervention schools decreased the number of breaks during school hours (8.30AM-4PM; β = -23.45breaks) and increased the number of sedentary bouts on a weekend day (β = +0.90bouts), whereas girls in control schools showed an increase in number of breaks and a decrease in number of bouts. In conclusion, UP4FUN did not have a consistent or substantial effect on breaking up children's sedentary time and these data suggest that more intensive and longer lasting interventions are needed.

26 CFR 1.411(a)-9 - Amendment of break in service rules; transitional period.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 26 Internal Revenue 5 2010-04-01 2010-04-01 false Amendment of break in service rules.... § 1.411(a)-9 Amendment of break in service rules; transitional period. (a) In general. Under section... breaks in service are amended, and— (1) Such amendment is effective after January 1, 1974, and before the...

Evaluation of the UP4FUN Intervention: A Cluster Randomized Trial to Reduce and Break Up Sitting Time in European 10-12-Year-Old Children

PubMed Central

Vik, Frøydis N.; Lien, Nanna; Berntsen, Sveinung; De Bourdeaudhuij, Ilse; Grillenberger, Monika; Manios, Yannis; Kovacs, Eva; Chinapaw, Mai J. M.; Brug, Johannes; Bere, Elling

2015-01-01

Background The UP4FUN intervention is a family-involved school-based intervention aiming at reducing and breaking up sitting time at home (with special emphasis on screen time), and breaking up sitting time in school among 10–12 year olds in Europe. The purpose of the present paper was to evaluate its short term effects. Methodology/Principal Findings A total of 3147 pupils from Belgium, Germany, Greece, Hungary and Norway participated in a school-randomized controlled trial. The intervention included 1–2 school lessons per week for a period of six weeks, along with assignments for the children and their parents. Screen time and breaking up sitting time were registered by self-report and total sedentary time and breaking up sitting time by accelerometry. The effect of the intervention on these behaviors was evaluated by multilevel regression analyses. All analyses were adjusted for baseline values and gender. Significance level was p≤0.01. No significant intervention effects were observed, neither for self-reported TV/DVD or computer/game console time, nor for accelerometer-assessed total sedentary time and number of breaks in sitting time. The intervention group, however, reported more positive attitudes towards (β = 0.25 (95% CI 0.11, 0.38)) and preferences/liking for (β = 0.20 (95% CI 0.08, 0.32)) breaking up sitting time than the control group. Conclusions/Significance No significant intervention effect on self-reported screen time or accelerometer-assessed sedentary time or breaks in sitting time was observed, but positive effects on beliefs regarding breaking up sitting time were found in favor of the intervention group. Overall, these results do not warrant wider dissemination of the present UP4FUN intervention. Trial Registration International Standard Randomized Controlled Trial Number Registry ISRCTN34562078 PMID:25826704

Breaking Bad Habits: Teaching Effective PowerPoint Use to Working Graduate Students

ERIC Educational Resources Information Center

Vik, Gretchen N.

2004-01-01

One interesting aspect of teaching students to use PowerPoint and similar graphics packages effectively is that graduate students who are already in the workforce often have bad presentation habits that they need to break. In this article, the author discusses ways of breaking these bad habits. Using storyboards is one way to keep students from…

Effect of breaking up sedentary time with callisthenics on endothelial function.

PubMed

Carter, Sophie E; Gladwell, Valerie F

2017-08-01

Periods of prolonged sitting impairs endothelial function in lower limb conduit arteries, which is attenuated with physical activity breaks. The effect of activity breaks on upper limb arteries has not been examined. This study assessed changes in brachial artery endothelial function following either a prolonged sitting period or breaking up this sedentary time by performing sets of callisthenics exercises. Ten healthy participants (6 men) completed 2 conditions in a counterbalanced order: (a) 1-h 26-min sitting, or (b) breaking up this period every 20 min by performing a set of 5 callisthenics exercises. Brachial artery endothelial function was assessed via ultrasound using the flow-mediated dilation (FMD) technique prior to and following each condition, while brachial shear rate (SR) was acquired after each set of callisthenics. There was no significant change in FMD over time (P = 0.09) or between conditions (P = 0.12). Compared to sitting, brachial SR increased following each set of callisthenics, with a significant difference after the third break (Sit: 33.94 ± 12.79 s -1 ; Callisthenics: 57.16 ± 30.48 s -1 , P = 0.02). Alterations in SR in the upper limbs suggest callisthenics may be an effective intervention to break up sedentary time and attenuate the potentially deleterious effects of prolonged sitting on cardiovascular health.

Break the "wall" and become creative: Enacting embodied metaphors in virtual reality.

PubMed

Wang, Xinyue; Lu, Kelong; Runco, Mark A; Hao, Ning

2018-07-01

This study investigated whether the experience of "breaking the walls", the embodiment of the metaphor "breaking the rules", could enhance creative performance. The virtual reality technology was used to simulate the scenario where participants could "break the walls" while walking in a corridor. Participants were asked to solve the creativity-demanding problems (ie., alternative uses tasks, AUT) in either the "break" condition in which they had to break the walls to move forward in VR, or the "no-break" condition where no barrier walls would appear. Results showed higher AUT originality and AUT fluency in the "break" condition than in the "no-break" condition. Moreover, the effects of "breaking the walls" on AUT originality were fully mediated by cognitive flexibility and persistence. These findings may indicate that enacting metaphors such as "breaking the rules" contribute to creative performance. The enhanced cognitive flexibility and persistence may account for the benefits. Copyright © 2018 Elsevier Inc. All rights reserved.

Spontaneous chiral symmetry breaking in metamaterials

NASA Astrophysics Data System (ADS)

Liu, Mingkai; Powell, David A.; Shadrivov, Ilya V.; Lapine, Mikhail; Kivshar, Yuri S.

2014-07-01

Spontaneous chiral symmetry breaking underpins a variety of areas such as subatomic physics and biochemistry, and leads to an impressive range of fundamental phenomena. Here we show that this prominent effect is now available in artificial electromagnetic systems, enabled by the advent of magnetoelastic metamaterials where a mechanical degree of freedom leads to a rich variety of strong nonlinear effects such as bistability and self-oscillations. We report spontaneous symmetry breaking in torsional chiral magnetoelastic structures where two or more meta-molecules with opposite handedness are electromagnetically coupled, modifying the system stability. Importantly, we show that chiral symmetry breaking can be found in the stationary response of the system, and the effect is successfully demonstrated in a microwave pump-probe experiment. Such symmetry breaking can lead to a giant nonlinear polarization change, energy localization and mode splitting, which provides a new possibility for creating an artificial phase transition in metamaterials, analogous to that in ferrimagnetic domains.

Spontaneous chiral symmetry breaking in metamaterials.

PubMed

Liu, Mingkai; Powell, David A; Shadrivov, Ilya V; Lapine, Mikhail; Kivshar, Yuri S

2014-07-18

Spontaneous chiral symmetry breaking underpins a variety of areas such as subatomic physics and biochemistry, and leads to an impressive range of fundamental phenomena. Here we show that this prominent effect is now available in artificial electromagnetic systems, enabled by the advent of magnetoelastic metamaterials where a mechanical degree of freedom leads to a rich variety of strong nonlinear effects such as bistability and self-oscillations. We report spontaneous symmetry breaking in torsional chiral magnetoelastic structures where two or more meta-molecules with opposite handedness are electromagnetically coupled, modifying the system stability. Importantly, we show that chiral symmetry breaking can be found in the stationary response of the system, and the effect is successfully demonstrated in a microwave pump-probe experiment. Such symmetry breaking can lead to a giant nonlinear polarization change, energy localization and mode splitting, which provides a new possibility for creating an artificial phase transition in metamaterials, analogous to that in ferrimagnetic domains.

Response of jammed packings to thermal fluctuations

NASA Astrophysics Data System (ADS)

Wu, Qikai; Bertrand, Thibault; Shattuck, Mark D.; O'Hern, Corey S.

2017-12-01

We focus on the response of mechanically stable (MS) packings of frictionless, bidisperse disks to thermal fluctuations, with the aim of quantifying how nonlinearities affect system properties at finite temperature. In contrast, numerous prior studies characterized the structural and mechanical properties of MS packings of frictionless spherical particles at zero temperature. Packings of disks with purely repulsive contact interactions possess two main types of nonlinearities, one from the form of the interaction potential (e.g., either linear or Hertzian spring interactions) and one from the breaking (or forming) of interparticle contacts. To identify the temperature regime at which the contact-breaking nonlinearities begin to contribute, we first calculated the minimum temperatures Tc b required to break a single contact in the MS packing for both single- and multiple-eigenmode perturbations of the T =0 MS packing. We find that the temperature required to break a single contact for equal velocity-amplitude perturbations involving all eigenmodes approaches the minimum value obtained for a perturbation in the direction connecting disk pairs with the smallest overlap. We then studied deviations in the constant volume specific heat C¯V and deviations of the average disk positions Δ r from their T =0 values in the temperature regime TC ¯V100 for linear spring interactions is independent of system size. This result emphasizes that contact-breaking nonlinearities are dominant over form nonlinearities in the low-temperature range Tc b

Extended nicotine self-administration increases sensitivity to nicotine, motivation to seek nicotine and the reinforcing properties of nicotine-paired cues.

PubMed

Clemens, Kelly J; Lay, Belinda P P; Holmes, Nathan M

2017-03-01

An array of pharmacological and environmental factors influence the development and maintenance of tobacco addiction. The nature of these influences likely changes across the course of an extended smoking history, during which time drug seeking can become involuntary and uncontrolled. The present study used an animal model to examine the factors that drive nicotine-seeking behavior after either brief (10 days) or extended (40 days) self-administration training. In Experiment 1, extended training increased rats' sensitivity to nicotine, indicated by a leftward shift in the dose-response curve, and their motivation to work for nicotine, indicated by an increase in the break point achieved under a progressive ratio schedule. In Experiment 2, extended training imbued the nicotine-paired cue with the capacity to maintain responding to the same high level as nicotine itself. However, Experiment 3 showed that the mechanisms involved in responding for nicotine or a nicotine-paired cue are dissociable, as treatment with the partial nicotine receptor agonist, varenicline, suppressed responding for nicotine but potentiated responding for the nicotine-paired cue. Hence, across extended nicotine self-administration, pharmacological and environmental influences over nicotine seeking increase such that nicotine seeking is controlled by multiple sources, and therefore highly resistant to change. © 2015 Society for the Study of Addiction.

Anomalous scaling of Δ C versus T c in the Fe-based superconductors: the $${S}_{\\pm }$$-wave pairing state model

DOE PAGES

Bang, Yunkyu; Stewart, G. R.

2016-02-01

The strong power law behavior of the specific heat jumpmore » $${\\rm{\\Delta }}C\\;$$ versus T c $$({\\rm{\\Delta }}C/{T}_{{\\rm{c}}}\\sim {T}_{{\\rm{c}}}^{\\alpha },\\alpha \\approx 2)$$, first observed by Bud'ko et al (2009 Phys. Rev. B 79 220516), has been confirmed with several families of the Fe-based superconducting compounds with various dopings. We tested a minimal two band BCS model to understand this anomalous behavior and showed that this non-BCS relation between $${\\rm{\\Delta }}C\\;$$ versus T c is a generic property of the multiband superconducting state paired by a dominant interband interaction ($${V}_{\\mathrm{inter}}\\gt {V}_{\\mathrm{intra}}$$) reflecting the relation $$\\frac{{{\\rm{\\Delta }}}_{{\\rm{h}}}}{{{\\rm{\\Delta }}}_{{\\rm{e}}}}\\sim \\sqrt{\\frac{{N}_{{\\rm{e}}}}{{N}_{{\\rm{h}}}}}$$ near T c, as in the $${S}_{\\pm }$$-wave pairing state. We also found that this $${\\rm{\\Delta }}C\\;$$ versus T c power law can continuously change from the ideal BNC scaling to a considerable deviation by a moderate variation of the impurity scattering rate $${{\\rm{\\Gamma }}}_{0}$$ (non-pair-breaking). Finally, as a result, our model provides a consistent explanation why the electron-doped Fe-based superconductors follow the ideal BNC scaling very well while the hole-doped systems often show varying degree of deviations.« less

Single-cell paired-end genome sequencing reveals structural variation per cell cycle

PubMed Central

Voet, Thierry; Kumar, Parveen; Van Loo, Peter; Cooke, Susanna L.; Marshall, John; Lin, Meng-Lay; Zamani Esteki, Masoud; Van der Aa, Niels; Mateiu, Ligia; McBride, David J.; Bignell, Graham R.; McLaren, Stuart; Teague, Jon; Butler, Adam; Raine, Keiran; Stebbings, Lucy A.; Quail, Michael A.; D’Hooghe, Thomas; Moreau, Yves; Futreal, P. Andrew; Stratton, Michael R.; Vermeesch, Joris R.; Campbell, Peter J.

2013-01-01

The nature and pace of genome mutation is largely unknown. Because standard methods sequence DNA from populations of cells, the genetic composition of individual cells is lost, de novo mutations in cells are concealed within the bulk signal and per cell cycle mutation rates and mechanisms remain elusive. Although single-cell genome analyses could resolve these problems, such analyses are error-prone because of whole-genome amplification (WGA) artefacts and are limited in the types of DNA mutation that can be discerned. We developed methods for paired-end sequence analysis of single-cell WGA products that enable (i) detecting multiple classes of DNA mutation, (ii) distinguishing DNA copy number changes from allelic WGA-amplification artefacts by the discovery of matching aberrantly mapping read pairs among the surfeit of paired-end WGA and mapping artefacts and (iii) delineating the break points and architecture of structural variants. By applying the methods, we capture DNA copy number changes acquired over one cell cycle in breast cancer cells and in blastomeres derived from a human zygote after in vitro fertilization. Furthermore, we were able to discover and fine-map a heritable inter-chromosomal rearrangement t(1;16)(p36;p12) by sequencing a single blastomere. The methods will expedite applications in basic genome research and provide a stepping stone to novel approaches for clinical genetic diagnosis. PMID:23630320

26 CFR 1.410(a)-6 - Amendment of break in service rules; Transition period.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 26 Internal Revenue 5 2010-04-01 2010-04-01 false Amendment of break in service rules; Transition.... § 1.410(a)-6 Amendment of break in service rules; Transition period. (a) In general. Under section... breaks in service are amended, and— (1) Such amendment is effective after January 1, 1974, and before the...

A depth-averaged 2-D shallow water model for breaking and non-breaking long waves affected by rigid vegetation

USDA-ARS?s Scientific Manuscript database

This paper presents a depth-averaged two-dimensional shallow water model for simulating long waves in vegetated water bodies under breaking and non-breaking conditions. The effects of rigid vegetation are modelled in the form of drag and inertia forces as sink terms in the momentum equations. The dr...

Attributing Changing Rates of Temperature Record Breaking to Anthropogenic Influences

NASA Astrophysics Data System (ADS)

King, Andrew D.

2017-11-01

Record-breaking temperatures attract attention from the media, so understanding how and why the rate of record breaking is changing may be useful in communicating the effects of climate change. A simple methodology designed for estimating the anthropogenic influence on rates of record breaking in a given time series is proposed here. The frequency of hot and cold record-breaking temperature occurrences is shown to be changing due to the anthropogenic influence on the climate. Using ensembles of model simulations with and without human-induced forcings, it is demonstrated that the effect of climate change on global record-breaking temperatures can be detected as far back as the 1930s. On local scales, a climate change signal is detected more recently at most locations. The anthropogenic influence on the increased occurrence of hot record-breaking temperatures is clearer than it is for the decreased occurrence of cold records. The approach proposed here could be applied in rapid attribution studies of record extremes to quantify the influence of climate change on the rate of record breaking in addition to the climate anomaly being studied. This application is demonstrated for the global temperature record of 2016 and the Central England temperature record in 2014.

Ku80 Counters Oxidative Stress-Induced DNA Damage and Cataract Formation in the Human Lens.

PubMed

Smith, Andrew John Oliver; Ball, Simon Sidney Robert; Manzar, Kamal; Bowater, Richard Peter; Wormstone, Ian Michael

2015-12-01

Oxidative stress in the human lens leads to a wide range of damage including DNA strand breaks, which are likely to contribute to cataract formation. The protein Ku80 is a fundamental component of the nonhomologous end-joining pathway that repairs DNA double strand breaks. This study investigates the putative impact of Ku80 in cataract prevention in the human lens. The present study used the human lens epithelial cell line FHL124 and whole human lens organ culture. Targeted siRNA was used to deplete Ku80, with Western blot and immunocytochemistry employed to assess Ku80 expression levels. Oxidative stress was induced with hydrogen peroxide and DNA strand breaks measured by alkaline comet assay and γH2AX foci counts. Visual quality of whole human lenses was measured with image analysis software. Expression of Ku80 was predominately found in the cell nucleus of both FHL124 cells and native human lens epithelium. Treatment of FHL124 cells and whole lens cultures with siRNA targeted against Ku80 resulted in a significant knockdown at the protein level. Application of oxidative stress (30 μM H2O2) created more DNA strand breaks when added to Ku80 knockdown cells than in scrambled siRNA control cells as determined by the alkaline comet assay and the number of γH2AX foci. In whole lens cultures, exposure to 1 mM H2O2 resulted in more lens opacity in Ku80 knockdown lenses than match-paired controls. Depletion of Ku80 in the lens through acute change or a consequence of aging is likely to increase levels of DNA strand breaks, which could negatively influence physiological function and promote lens opacity. It is therefore feasible that Ku80 plays a role in retarding cataract formation.

Search for natural supersymmetry in events with top quark pairs and photons in pp collisions at $$ \\sqrt{s}=8 $$ TeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sirunyan, A. M.; Tumasyan, A.; Adam, W.

Here, results are presented from a search for natural gauge-mediated supersymmetry (SUSY) in a scenario in which the top squark is the lightest squark, the next-to-lightest SUSY particle is a bino-like neutralino, and the lightest SUSY particle is the gravitino. The strong production of top squark pairs can produce events with pairs of top quarks and neutralinos, with each bino-like neutralino decaying to a photon and a gravitino. The search is performed using a sample of pp collision data accumulated by the CMS experiment atmore » $$\\sqrt{s} = $$8 TeV, corresponding to an integrated luminosity of 19.7 fb$$^{-1}$$. The final state consists of a lepton (electron or muon), jets, and one or two photons. The imbalance in transverse momentum in the events is compared with the expected spectrum from standard model processes. No excess event yield is observed beyond the expected background, and the result is interpreted in the context of a general model of gauge-mediated SUSY breaking that leads to exclusion of top squark masses below 650-730 GeV.« less

Search for natural supersymmetry in events with top quark pairs and photons in pp collisions at $$ \\sqrt{s}=8 $$ TeV

DOE PAGES

Sirunyan, A. M.; Tumasyan, A.; Adam, W.; ...

2018-03-27

Here, results are presented from a search for natural gauge-mediated supersymmetry (SUSY) in a scenario in which the top squark is the lightest squark, the next-to-lightest SUSY particle is a bino-like neutralino, and the lightest SUSY particle is the gravitino. The strong production of top squark pairs can produce events with pairs of top quarks and neutralinos, with each bino-like neutralino decaying to a photon and a gravitino. The search is performed using a sample of pp collision data accumulated by the CMS experiment atmore » $$\\sqrt{s} = $$8 TeV, corresponding to an integrated luminosity of 19.7 fb$$^{-1}$$. The final state consists of a lepton (electron or muon), jets, and one or two photons. The imbalance in transverse momentum in the events is compared with the expected spectrum from standard model processes. No excess event yield is observed beyond the expected background, and the result is interpreted in the context of a general model of gauge-mediated SUSY breaking that leads to exclusion of top squark masses below 650-730 GeV.« less

Search for natural supersymmetry in events with top quark pairs and photons in pp collisions at √{s}=8 TeV

NASA Astrophysics Data System (ADS)

Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Brondolin, E.; Dragicevic, M.; Erö, J.; Flechl, M.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Hartl, C.; Hörmann, N.; Hrubec, J.; Jeitler, M.; König, A.; Krätschmer, I.; Liko, D.; Matsushita, T.; Mikulec, I.; Rabady, D.; Rad, N.; Rahbaran, B.; Rohringer, H.; Schieck, J.; Strauss, J.; Waltenberger, W.; Wulz, C.-E.; Dvornikov, O.; Makarenko, V.; Mossolov, V.; Suarez Gonzalez, J.; Zykunov, V.; Shumeiko, N.; Alderweireldt, S.; De Wolf, E. A.; Janssen, X.; Lauwers, J.; Van De Klundert, M.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Abu Zeid, S.; Blekman, F.; D'Hondt, J.; Daci, N.; De Bruyn, I.; Deroover, K.; Lowette, S.; Moortgat, S.; Moreels, L.; Olbrechts, A.; Python, Q.; Skovpen, K.; Tavernier, S.; Van Doninck, W.; Van Mulders, P.; Van Parijs, I.; Brun, H.; Clerbaux, B.; De Lentdecker, G.; Delannoy, H.; Fasanella, G.; Favart, L.; Goldouzian, R.; Grebenyuk, A.; Karapostoli, G.; Lenzi, T.; Léonard, A.; Luetic, J.; Maerschalk, T.; Marinov, A.; Randle-conde, A.; Seva, T.; Vander Velde, C.; Vanlaer, P.; Vannerom, D.; Yonamine, R.; Zenoni, F.; Zhang, F.; Cornelis, T.; Dobur, D.; Fagot, A.; Gul, M.; Khvastunov, I.; Poyraz, D.; Salva, S.; Schöfbeck, R.; Tytgat, M.; Van Driessche, W.; Verbeke, W.; Zaganidis, N.; Bakhshiansohi, H.; Bondu, O.; Brochet, S.; Bruno, G.; Caudron, A.; De Visscher, S.; Delaere, C.; Delcourt, M.; Francois, B.; Giammanco, A.; Jafari, A.; Komm, M.; Krintiras, G.; Lemaitre, V.; Magitteri, A.; Mertens, A.; Musich, M.; Piotrzkowski, K.; Quertenmont, L.; Vidal Marono, M.; Wertz, S.; Beliy, N.; Aldá Júnior, W. L.; Alves, F. L.; Alves, G. A.; Brito, L.; Hensel, C.; Moraes, A.; Pol, M. E.; Rebello Teles, P.; Belchior Batista Das Chagas, E.; Carvalho, W.; Chinellato, J.; Custódio, A.; Da Costa, E. M.; Da Silveira, G. G.; De Jesus Damiao, D.; De Oliveira Martins, C.; Fonseca De Souza, S.; Huertas Guativa, L. M.; Malbouisson, H.; Matos Figueiredo, D.; Mora Herrera, C.; Mundim, L.; Nogima, H.; Prado Da Silva, W. L.; Santoro, A.; Sznajder, A.; Tonelli Manganote, E. J.; Torres Da Silva De Araujo, F.; Vilela Pereira, A.; Ahuja, S.; Bernardes, C. A.; Dogra, S.; Fernandez Perez Tomei, T. R.; Gregores, E. M.; Mercadante, P. G.; Moon, C. S.; Novaes, S. F.; Padula, Sandra S.; Romero Abad, D.; Ruiz Vargas, J. C.; Aleksandrov, A.; Hadjiiska, R.; Iaydjiev, P.; Rodozov, M.; Stoykova, S.; Sultanov, G.; Vutova, M.; Dimitrov, A.; Glushkov, I.; Litov, L.; Pavlov, B.; Petkov, P.; Fang, W.; Gao, X.; Ahmad, M.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Chen, M.; Chen, Y.; Cheng, T.; Jiang, C. H.; Leggat, D.; Liu, Z.; Romeo, F.; Ruan, M.; Shaheen, S. M.; Spiezia, A.; Tao, J.; Wang, C.; Wang, Z.; Yazgan, E.; Zhang, H.; Zhao, J.; Ban, Y.; Chen, G.; Li, Q.; Liu, S.; Mao, Y.; Qian, S. J.; Wang, D.; Xu, Z.; Avila, C.; Cabrera, A.; Chaparro Sierra, L. F.; Florez, C.; Gomez, J. P.; González Hernández, C. F.; Ruiz Alvarez, J. D.; Sanabria, J. C.; Godinovic, N.; Lelas, D.; Puljak, I.; Ribeiro Cipriano, P. M.; Sculac, T.; Antunovic, Z.; Kovac, M.; Brigljevic, V.; Ferencek, D.; Kadija, K.; Mesic, B.; Susa, T.; Ather, M. W.; Attikis, A.; Mavromanolakis, G.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Rykaczewski, H.; Finger, M.; Finger, M.; Carrera Jarrin, E.; Assran, Y.; Mahmoud, M. A.; Mahrous, A.; Kadastik, M.; Perrini, L.; Raidal, M.; Tiko, A.; Veelken, C.; Eerola, P.; Pekkanen, J.; Voutilainen, M.; Härkönen, J.; Järvinen, T.; Karimäki, V.; Kinnunen, R.; Lampén, T.; Lassila-Perini, K.; Lehti, S.; Lindén, T.; Luukka, P.; Tuominiemi, J.; Tuovinen, E.; Wendland, L.; Talvitie, J.; Tuuva, T.; Besancon, M.; Couderc, F.; Dejardin, M.; Denegri, D.; Fabbro, B.; Faure, J. L.; Favaro, C.; Ferri, F.; Ganjour, S.; Ghosh, S.; Givernaud, A.; Gras, P.; Hamel de Monchenault, G.; Jarry, P.; Kucher, I.; Locci, E.; Machet, M.; Malcles, J.; Rander, J.; Rosowsky, A.; Titov, M.; Abdulsalam, A.; Antropov, I.; Baffioni, S.; Beaudette, F.; Busson, P.; Cadamuro, L.; Chapon, E.; Charlot, C.; Davignon, O.; Granier de Cassagnac, R.; Jo, M.; Lisniak, S.; Lobanov, A.; Miné, P.; Nguyen, M.; Ochando, C.; Ortona, G.; Paganini, P.; Pigard, P.; Regnard, S.; Salerno, R.; Sirois, Y.; Stahl Leiton, A. G.; Strebler, T.; Yilmaz, Y.; Zabi, A.; Zghiche, A.; Agram, J.-L.; Andrea, J.; Bloch, D.; Brom, J.-M.; Buttignol, M.; Chabert, E. C.; Chanon, N.; Collard, C.; Conte, E.; Coubez, X.; Fontaine, J.-C.; Gelé, D.; Goerlach, U.; Le Bihan, A.-C.; Van Hove, P.; Gadrat, S.; Beauceron, S.; Bernet, C.; Boudoul, G.; Carrillo Montoya, C. A.; Chierici, R.; Contardo, D.; Courbon, B.; Depasse, P.; El Mamouni, H.; Fay, J.; Finco, L.; Gascon, S.; Gouzevitch, M.; Grenier, G.; Ille, B.; Lagarde, F.; Laktineh, I. B.; Lethuillier, M.; Mirabito, L.; Pequegnot, A. L.; Perries, S.; Popov, A.; Sordini, V.; Vander Donckt, M.; Verdier, P.; Viret, S.; Khvedelidze, A.; Tsamalaidze, Z.; Autermann, C.; Beranek, S.; Feld, L.; Kiesel, M. K.; Klein, K.; Lipinski, M.; Preuten, M.; Schomakers, C.; Schulz, J.; Verlage, T.; Albert, A.; Brodski, M.; Dietz-Laursonn, E.; Duchardt, D.; Endres, M.; Erdmann, M.; Erdweg, S.; Esch, T.; Fischer, R.; Güth, A.; Hamer, M.; Hebbeker, T.; Heidemann, C.; Hoepfner, K.; Knutzen, S.; Merschmeyer, M.; Meyer, A.; Millet, P.; Mukherjee, S.; Olschewski, M.; Padeken, K.; Pook, T.; Radziej, M.; Reithler, H.; Rieger, M.; Scheuch, F.; Sonnenschein, L.; Teyssier, D.; Thüer, S.; Cherepanov, V.; Flügge, G.; Kargoll, B.; Kress, T.; Künsken, A.; Lingemann, J.; Müller, T.; Nehrkorn, A.; Nowack, A.; Pistone, C.; Pooth, O.; Stahl, A.; Aldaya Martin, M.; Arndt, T.; Asawatangtrakuldee, C.; Beernaert, K.; Behnke, O.; Behrens, U.; Bin Anuar, A. A.; Borras, K.; Campbell, A.; Connor, P.; Contreras-Campana, C.; Costanza, F.; Diez Pardos, C.; Dolinska, G.; Eckerlin, G.; Eckstein, D.; Eichhorn, T.; Eren, E.; Gallo, E.; Garay Garcia, J.; Geiser, A.; Gizhko, A.; Grados Luyando, J. M.; Grohsjean, A.; Gunnellini, P.; Harb, A.; Hauk, J.; Hempel, M.; Jung, H.; Kalogeropoulos, A.; Karacheban, O.; Kasemann, M.; Keaveney, J.; Kleinwort, C.; Korol, I.; Krücker, D.; Lange, W.; Lelek, A.; Lenz, T.; Leonard, J.; Lipka, K.; Lohmann, W.; Mankel, R.; Melzer-Pellmann, I.-A.; Meyer, A. B.; Mittag, G.; Mnich, J.; Mussgiller, A.; Ntomari, E.; Pitzl, D.; Placakyte, R.; Raspereza, A.; Roland, B.; Sahin, M. Ö.; Saxena, P.; Schoerner-Sadenius, T.; Spannagel, S.; Stefaniuk, N.; Van Onsem, G. P.; Walsh, R.; Wissing, C.; Blobel, V.; Centis Vignali, M.; Draeger, A. R.; Dreyer, T.; Garutti, E.; Gonzalez, D.; Haller, J.; Hoffmann, M.; Junkes, A.; Klanner, R.; Kogler, R.; Kovalchuk, N.; Kurz, S.; Lapsien, T.; Marchesini, I.; Marconi, D.; Meyer, M.; Niedziela, M.; Nowatschin, D.; Pantaleo, F.; Peiffer, T.; Perieanu, A.; Scharf, C.; Schleper, P.; Schmidt, A.; Schumann, S.; Schwandt, J.; Sonneveld, J.; Stadie, H.; Steinbrück, G.; Stober, F. M.; Stöver, M.; Tholen, H.; Troendle, D.; Usai, E.; Vanelderen, L.; Vanhoefer, A.; Vormwald, B.; Akbiyik, M.; Barth, C.; Baur, S.; Baus, C.; Berger, J.; Butz, E.; Caspart, R.; Chwalek, T.; Colombo, F.; De Boer, W.; Dierlamm, A.; Fink, S.; Freund, B.; Friese, R.; Giffels, M.; Gilbert, A.; Goldenzweig, P.; Haitz, D.; Hartmann, F.; Heindl, S. M.; Husemann, U.; Kassel, F.; Katkov, I.; Kudella, S.; Mildner, H.; Mozer, M. U.; Müller, Th.; Plagge, M.; Quast, G.; Rabbertz, K.; Röcker, S.; Roscher, F.; Schröder, M.; Shvetsov, I.; Sieber, G.; Simonis, H. J.; Ulrich, R.; Wayand, S.; Weber, M.; Weiler, T.; Williamson, S.; Wöhrmann, C.; Wolf, R.; Anagnostou, G.; Daskalakis, G.; Geralis, T.; Giakoumopoulou, V. A.; Kyriakis, A.; Loukas, D.; Topsis-Giotis, I.; Kesisoglou, S.; Panagiotou, A.; Saoulidou, N.; Tziaferi, E.; Kousouris, K.; Evangelou, I.; Flouris, G.; Foudas, C.; Kokkas, P.; Loukas, N.; Manthos, N.; Papadopoulos, I.; Paradas, E.; Triantis, F. A.; Filipovic, N.; Pasztor, G.; Bencze, G.; Hajdu, C.; Horvath, D.; Sikler, F.; Veszpremi, V.; Vesztergombi, G.; Zsigmond, A. J.; Beni, N.; Czellar, S.; Karancsi, J.; Makovec, A.; Molnar, J.; Szillasi, Z.; Bartók, M.; Raics, P.; Trocsanyi, Z. L.; Ujvari, B.; Choudhury, S.; Komaragiri, J. R.; Bahinipati, S.; Bhowmik, S.; Mal, P.; Mandal, K.; Nayak, A.; Sahoo, D. K.; Sahoo, N.; Swain, S. K.; Bansal, S.; Beri, S. B.; Bhatnagar, V.; Bhawandeep, U.; Chawla, R.; Kalsi, A. K.; Kaur, A.; Kaur, M.; Kumar, R.; Kumari, P.; Mehta, A.; Mittal, M.; Singh, J. B.; Walia, G.; Kumar, Ashok; Bhardwaj, A.; Choudhary, B. C.; Garg, R. B.; Keshri, S.; Kumar, A.; Malhotra, S.; Naimuddin, M.; Ranjan, K.; Sharma, R.; Sharma, V.; Bhattacharya, R.; Bhattacharya, S.; Chatterjee, K.; Dey, S.; Dutt, S.; Dutta, S.; Ghosh, S.; Majumdar, N.; Modak, A.; Mondal, K.; Mukhopadhyay, S.; Nandan, S.; Purohit, A.; Roy, A.; Roy, D.; Roy Chowdhury, S.; Sarkar, S.; Sharan, M.; Thakur, S.; Behera, P. K.; Chudasama, R.; Dutta, D.; Jha, V.; Kumar, V.; Mohanty, A. K.; Netrakanti, P. K.; Pant, L. M.; Shukla, P.; Topkar, A.; Aziz, T.; Dugad, S.; Kole, G.; Mahakud, B.; Mitra, S.; Mohanty, G. B.; Parida, B.; Sur, N.; Sutar, B.; Banerjee, S.; Dewanjee, R. K.; Ganguly, S.; Guchait, M.; Jain, Sa.; Kumar, S.; Maity, M.; Majumder, G.; Mazumdar, K.; Sarkar, T.; Wickramage, N.; Chauhan, S.; Dube, S.; Hegde, V.; Kapoor, A.; Kothekar, K.; Pandey, S.; Rane, A.; Sharma, S.; Chenarani, S.; Eskandari Tadavani, E.; Etesami, S. 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A.; Mersi, S.; Meschi, E.; Milenovic, P.; Moortgat, F.; Morovic, S.; Mulders, M.; Neugebauer, H.; Orfanelli, S.; Orsini, L.; Pape, L.; Perez, E.; Peruzzi, M.; Petrilli, A.; Petrucciani, G.; Pfeiffer, A.; Pierini, M.; Racz, A.; Reis, T.; Rolandi, G.; Rovere, M.; Sakulin, H.; Sauvan, J. B.; Schäfer, C.; Schwick, C.; Seidel, M.; Selvaggi, M.; Sharma, A.; Silva, P.; Sphicas, P.; Steggemann, J.; Stoye, M.; Takahashi, Y.; Tosi, M.; Treille, D.; Triossi, A.; Tsirou, A.; Veckalns, V.; Veres, G. I.; Verweij, M.; Wardle, N.; Wöhri, H. K.; Zagozdzinska, A.; Zeuner, W. D.; Bertl, W.; Deiters, K.; Erdmann, W.; Horisberger, R.; Ingram, Q.; Kaestli, H. C.; Kotlinski, D.; Langenegger, U.; Rohe, T.; Wiederkehr, S. A.; Bachmair, F.; Bäni, L.; Bianchini, L.; Casal, B.; Dissertori, G.; Dittmar, M.; Donegà, M.; Grab, C.; Heidegger, C.; Hits, D.; Hoss, J.; Kasieczka, G.; Lustermann, W.; Mangano, B.; Marionneau, M.; Martinez Ruiz del Arbol, P.; Masciovecchio, M.; Meinhard, M. 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M.; Maruyama, S.; Mason, D.; McBride, P.; Merkel, P.; Mrenna, S.; Nahn, S.; O'Dell, V.; Pedro, K.; Prokofyev, O.; Rakness, G.; Ristori, L.; Sexton-Kennedy, E.; Soha, A.; Spalding, W. J.; Spiegel, L.; Stoynev, S.; Strait, J.; Strobbe, N.; Taylor, L.; Tkaczyk, S.; Tran, N. V.; Uplegger, L.; Vaandering, E. W.; Vernieri, C.; Verzocchi, M.; Vidal, R.; Wang, M.; Weber, H. A.; Whitbeck, A.; Wu, Y.; Acosta, D.; Avery, P.; Bortignon, P.; Bourilkov, D.; Brinkerhoff, A.; Carnes, A.; Carver, M.; Curry, D.; Das, S.; Field, R. D.; Furic, I. K.; Konigsberg, J.; Korytov, A.; Low, J. F.; Ma, P.; Matchev, K.; Mei, H.; Mitselmakher, G.; Rank, D.; Shchutska, L.; Sperka, D.; Thomas, L.; Wang, J.; Wang, S.; Yelton, J.; Linn, S.; Markowitz, P.; Martinez, G.; Rodriguez, J. L.; Ackert, A.; Adams, T.; Askew, A.; Bein, S.; Hagopian, S.; Hagopian, V.; Johnson, K. F.; Kolberg, T.; Perry, T.; Prosper, H.; Santra, A.; Yohay, R.; Baarmand, M. M.; Bhopatkar, V.; Colafranceschi, S.; Hohlmann, M.; Noonan, D.; Roy, T.; Yumiceva, F.; Adams, M. R.; Apanasevich, L.; Berry, D.; Betts, R. R.; Cavanaugh, R.; Chen, X.; Evdokimov, O.; Gerber, C. E.; Hangal, D. A.; Hofman, D. J.; Jung, K.; Kamin, J.; Sandoval Gonzalez, I. D.; Trauger, H.; Varelas, N.; Wang, H.; Wu, Z.; Zhang, J.; Bilki, B.; Clarida, W.; Dilsiz, K.; Durgut, S.; Gandrajula, R. P.; Haytmyradov, M.; Khristenko, V.; Merlo, J.-P.; Mermerkaya, H.; Mestvirishvili, A.; Moeller, A.; Nachtman, J.; Ogul, H.; Onel, Y.; Ozok, F.; Penzo, A.; Snyder, C.; Tiras, E.; Wetzel, J.; Yi, K.; Blumenfeld, B.; Cocoros, A.; Eminizer, N.; Fehling, D.; Feng, L.; Gritsan, A. V.; Maksimovic, P.; Roskes, J.; Sarica, U.; Swartz, M.; Xiao, M.; You, C.; Al-bataineh, A.; Baringer, P.; Bean, A.; Boren, S.; Bowen, J.; Castle, J.; Forthomme, L.; Khalil, S.; Kropivnitskaya, A.; Majumder, D.; Mcbrayer, W.; Murray, M.; Sanders, S.; Stringer, R.; Tapia Takaki, J. D.; Wang, Q.; Ivanov, A.; Kaadze, K.; Maravin, Y.; Mohammadi, A.; Saini, L. K.; Skhirtladze, N.; Toda, S.; Rebassoo, F.; Wright, D.; Anelli, C.; Baden, A.; Baron, O.; Belloni, A.; Calvert, B.; Eno, S. C.; Ferraioli, C.; Hadley, N. J.; Jabeen, S.; Jeng, G. Y.; Kellogg, R. G.; Kunkle, J.; Mignerey, A. C.; Ricci-Tam, F.; Shin, Y. H.; Skuja, A.; Tonjes, M. B.; Tonwar, S. C.; Abercrombie, D.; Allen, B.; Apyan, A.; Azzolini, V.; Barbieri, R.; Baty, A.; Bi, R.; Bierwagen, K.; Brandt, S.; Busza, W.; Cali, I. A.; D'Alfonso, M.; Demiragli, Z.; Gomez Ceballos, G.; Goncharov, M.; Hsu, D.; Iiyama, Y.; Innocenti, G. M.; Klute, M.; Kovalskyi, D.; Krajczar, K.; Lai, Y. S.; Lee, Y.-J.; Levin, A.; Luckey, P. D.; Maier, B.; Marini, A. C.; Mcginn, C.; Mironov, C.; Narayanan, S.; Niu, X.; Paus, C.; Roland, C.; Roland, G.; Salfeld-Nebgen, J.; Stephans, G. S. F.; Tatar, K.; Velicanu, D.; Wang, J.; Wang, T. W.; Wyslouch, B.; Benvenuti, A. C.; Chatterjee, R. M.; Evans, A.; Hansen, P.; Kalafut, S.; Kao, S. C.; Kubota, Y.; Lesko, Z.; Mans, J.; Nourbakhsh, S.; Ruckstuhl, N.; Rusack, R.; Tambe, N.; Turkewitz, J.; Acosta, J. G.; Oliveros, S.; Avdeeva, E.; Bloom, K.; Claes, D. R.; Fangmeier, C.; Gonzalez Suarez, R.; Kamalieddin, R.; Kravchenko, I.; Malta Rodrigues, A.; Monroy, J.; Siado, J. E.; Snow, G. R.; Stieger, B.; Alyari, M.; Dolen, J.; Godshalk, A.; Harrington, C.; Iashvili, I.; Nguyen, D.; Parker, A.; Rappoccio, S.; Roozbahani, B.; Alverson, G.; Barberis, E.; Hortiangtham, A.; Massironi, A.; Morse, D. M.; Nash, D.; Orimoto, T.; Teixeira De Lima, R.; Trocino, D.; Wang, R.-J.; Wood, D.; Bhattacharya, S.; Charaf, O.; Hahn, K. A.; Mucia, N.; Odell, N.; Pollack, B.; Schmitt, M. H.; Sung, K.; Trovato, M.; Velasco, M.; Dev, N.; Hildreth, M.; Hurtado Anampa, K.; Jessop, C.; Karmgard, D. J.; Kellams, N.; Lannon, K.; Marinelli, N.; Meng, F.; Mueller, C.; Musienko, Y.; Planer, M.; Reinsvold, A.; Ruchti, R.; Rupprecht, N.; Smith, G.; Taroni, S.; Wayne, M.; Wolf, M.; Woodard, A.; Alimena, J.; Antonelli, L.; Bylsma, B.; Durkin, L. S.; Flowers, S.; Francis, B.; Hart, A.; Hill, C.; Ji, W.; Liu, B.; Luo, W.; Puigh, D.; Winer, B. L.; Wulsin, H. W.; Cooperstein, S.; Driga, O.; Elmer, P.; Hardenbrook, J.; Hebda, P.; Lange, D.; Luo, J.; Marlow, D.; Medvedeva, T.; Mei, K.; Ojalvo, I.; Olsen, J.; Palmer, C.; Piroué, P.; Stickland, D.; Svyatkovskiy, A.; Tully, C.; Malik, S.; Barker, A.; Barnes, V. E.; Folgueras, S.; Gutay, L.; Jha, M. K.; Jones, M.; Jung, A. W.; Khatiwada, A.; Miller, D. H.; Neumeister, N.; Schulte, J. F.; Sun, J.; Wang, F.; Xie, W.; Parashar, N.; Stupak, J.; Adair, A.; Akgun, B.; Chen, Z.; Ecklund, K. M.; Geurts, F. J. M.; Guilbaud, M.; Li, W.; Michlin, B.; Northup, M.; Padley, B. P.; Roberts, J.; Rorie, J.; Tu, Z.; Zabel, J.; Betchart, B.; Bodek, A.; de Barbaro, P.; Demina, R.; Duh, Y. t.; Ferbel, T.; Galanti, M.; Garcia-Bellido, A.; Han, J.; Hindrichs, O.; Khukhunaishvili, A.; Lo, K. H.; Tan, P.; Verzetti, M.; Agapitos, A.; Chou, J. P.; Gershtein, Y.; Gómez Espinosa, T. A.; Halkiadakis, E.; Heindl, M.; Hughes, E.; Kaplan, S.; Kunnawalkam Elayavalli, R.; Kyriacou, S.; Lath, A.; Montalvo, R.; Nash, K.; Osherson, M.; Saka, H.; Salur, S.; Schnetzer, S.; Sheffield, D.; Somalwar, S.; Stone, R.; Thomas, S.; Thomassen, P.; Walker, M.; Delannoy, A. G.; Foerster, M.; Heideman, J.; Riley, G.; Rose, K.; Spanier, S.; Thapa, K.; Bouhali, O.; Celik, A.; Dalchenko, M.; De Mattia, M.; Delgado, A.; Dildick, S.; Eusebi, R.; Gilmore, J.; Huang, T.; Juska, E.; Kamon, T.; Mueller, R.; Pakhotin, Y.; Patel, R.; Perloff, A.; Perniè, L.; Rathjens, D.; Safonov, A.; Tatarinov, A.; Ulmer, K. A.; Akchurin, N.; Damgov, J.; De Guio, F.; Dragoiu, C.; Dudero, P. R.; Faulkner, J.; Gurpinar, E.; Kunori, S.; Lamichhane, K.; Lee, S. W.; Libeiro, T.; Peltola, T.; Undleeb, S.; Volobouev, I.; Wang, Z.; Greene, S.; Gurrola, A.; Janjam, R.; Johns, W.; Maguire, C.; Melo, A.; Ni, H.; Sheldon, P.; Tuo, S.; Velkovska, J.; Xu, Q.; Arenton, M. W.; Barria, P.; Cox, B.; Hirosky, R.; Ledovskoy, A.; Li, H.; Neu, C.; Sinthuprasith, T.; Sun, X.; Wang, Y.; Wolfe, E.; Xia, F.; Clarke, C.; Harr, R.; Karchin, P. E.; Sturdy, J.; Zaleski, S.; Belknap, D. A.; Buchanan, J.; Caillol, C.; Dasu, S.; Dodd, L.; Duric, S.; Gomber, B.; Grothe, M.; Herndon, M.; Hervé, A.; Hussain, U.; Klabbers, P.; Lanaro, A.; Levine, A.; Long, K.; Loveless, R.; Pierro, G. A.; Polese, G.; Ruggles, T.; Savin, A.; Smith, N.; Smith, W. H.; Taylor, D.; Woods, N.

2018-03-01

Results are presented from a search for natural gauge-mediated supersymmetry (SUSY) in a scenario in which the top squark is the lightest squark, the next-to-lightest SUSY particle is a bino-like neutralino, and the lightest SUSY particle is the gravitino. The strong production of top squark pairs can produce events with pairs of top quarks and neutralinos, with each bino-like neutralino decaying to a photon and a gravitino. The search is performed using a sample of pp collision data accumulated by the CMS experiment at √{s}=8 TeV, corresponding to an integrated luminosity of 19.7 fb-1. The final state consists of a lepton (electron or muon), jets, and one or two photons. The imbalance in transverse momentum in the events is compared with the expected spectrum from standard model processes. No excess event yield is observed beyond the expected background, and the result is interpreted in the context of a general model of gauge-mediated SUSY breaking that leads to exclusion of top squark masses below 650-730 GeV. [Figure not available: see fulltext.

Evidence of protein-free homology recognition in magnetic bead force-extension experiments

NASA Astrophysics Data System (ADS)

O'Lee, D. J.; Danilowicz, C.; Rochester, C.; Kornyshev, A. A.; Prentiss, M.

2016-07-01

Earlier theoretical studies have proposed that the homology-dependent pairing of large tracts of dsDNA may be due to physical interactions between homologous regions. Such interactions could contribute to the sequence-dependent pairing of chromosome regions that may occur in the presence or the absence of double-strand breaks. Several experiments have indicated the recognition of homologous sequences in pure electrolytic solutions without proteins. Here, we report single-molecule force experiments with a designed 60 kb long dsDNA construct; one end attached to a solid surface and the other end to a magnetic bead. The 60 kb constructs contain two 10 kb long homologous tracts oriented head to head, so that their sequences match if the two tracts fold on each other. The distance between the bead and the surface is measured as a function of the force applied to the bead. At low forces, the construct molecules extend substantially less than normal, control dsDNA, indicating the existence of preferential interaction between the homologous regions. The force increase causes no abrupt but continuous unfolding of the paired homologous regions. Simple semi-phenomenological models of the unfolding mechanics are proposed, and their predictions are compared with the data.

Orbital optimisation in the perfect pairing hierarchy: applications to full-valence calculations on linear polyacenes

NASA Astrophysics Data System (ADS)

Lehtola, Susi; Parkhill, John; Head-Gordon, Martin

2018-03-01

We describe the implementation of orbital optimisation for the models in the perfect pairing hierarchy. Orbital optimisation, which is generally necessary to obtain reliable results, is pursued at perfect pairing (PP) and perfect quadruples (PQ) levels of theory for applications on linear polyacenes, which are believed to exhibit strong correlation in the π space. While local minima and σ-π symmetry breaking solutions were found for PP orbitals, no such problems were encountered for PQ orbitals. The PQ orbitals are used for single-point calculations at PP, PQ and perfect hextuples (PH) levels of theory, both only in the π subspace, as well as in the full σπ valence space. It is numerically demonstrated that the inclusion of single excitations is necessary also when optimised orbitals are used. PH is found to yield good agreement with previously published density matrix renormalisation group data in the π space, capturing over 95% of the correlation energy. Full-valence calculations made possible by our novel, efficient code reveal that strong correlations are weaker when larger basis sets or active spaces are employed than in previous calculations. The largest full-valence PH calculations presented correspond to a (192e,192o) problem.

Fragile sites, dysfunctional telomere and chromosome fusions: What is 5S rDNA role?

PubMed

Barros, Alain Victor; Wolski, Michele Andressa Vier; Nogaroto, Viviane; Almeida, Mara Cristina; Moreira-Filho, Orlando; Vicari, Marcelo Ricardo

2017-04-15

Repetitive DNA regions are known as fragile chromosomal sites which present a high flexibility and low stability. Our focus was characterize fragile sites in 5S rDNA regions. The Ancistrus sp. species shows a diploid number of 50 and an indicative Robertsonian fusion at chromosomal pair 1. Two sequences of 5S rDNA were identified: 5S.1 rDNA and 5S.2 rDNA. The first sequence gathers the necessary structures to gene expression and shows a functional secondary structure prediction. Otherwise, the 5S.2 rDNA sequence does not contain the upstream sequences that are required to expression, furthermore its structure prediction reveals a nonfunctional ribosomal RNA. The chromosomal mapping revealed several 5S.1 and 5S.2 rDNA clusters. In addition, the 5S.2 rDNA clusters were found in acrocentric and metacentric chromosomes proximal regions. The pair 1 5S.2 rDNA cluster is co-located with interstitial telomeric sites (ITS). Our results indicate that its clusters are hotspots to chromosomal breaks. During the meiotic prophase bouquet arrangement, double strand breaks (DSBs) at proximal 5S.2 rDNA of acrocentric chromosomes could lead to homologous and non-homologous repair mechanisms as Robertsonian fusions. Still, ITS sites provides chromosomal instability, resulting in telomeric recombination via TRF2 shelterin protein and a series of breakage-fusion-bridge cycles. Our proposal is that 5S rDNA derived sequences, act as chromosomal fragile sites in association with some chromosomal rearrangements of Loricariidae. Copyright © 2017 Elsevier B.V. All rights reserved.

Probing and Manipulating Ultracold Fermi Superfluids

NASA Astrophysics Data System (ADS)

Jiang, Lei

Ultracold Fermi gas is an exciting field benefiting from atomic physics, optical physics and condensed matter physics. It covers many aspects of quantum mechanics. Here I introduce some of my work during my graduate study. We proposed an optical spectroscopic method based on electromagnetically-induced transparency (EIT) as a generic probing tool that provides valuable insights into the nature of Fermi paring in ultracold Fermi gases of two hyperfine states. This technique has the capability of allowing spectroscopic response to be determined in a nearly non-destructive manner and the whole spectrum may be obtained by scanning the probe laser frequency faster than the lifetime of the sample without re-preparing the atomic sample repeatedly. Both quasiparticle picture and pseudogap picture are constructed to facilitate the physical explanation of the pairing signature in the EIT spectra. Motivated by the prospect of realizing a Fermi gas of 40K atoms with a synthetic non-Abelian gauge field, we investigated theoretically BEC-HCS crossover physics in the presence of a Rashba spin-orbit coupling in a system of two-component Fermi gas with and without a Zeeman field that breaks the population balance. A new bound state (Rashba pair) emerges because of the spin-orbit interaction. We studied the properties of Rashba pairs using a standard pair fluctuation theory. As the two-fold spin degeneracy is lifted by spin-orbit interaction, bound pairs with mixed singlet and triplet pairings (referred to as rashbons) emerge, leading to an anisotropic superfluid. We discussed in detail the experimental signatures for observing the condensation of Rashba pairs by calculating various physical observables which characterize the properties of the system and can be measured in experiment. The role of impurities as experimental probes in the detection of quantum material properties is well appreciated. Here we studied the effect of a single classical impurity in trapped ultracold Fermi superfluids. Although a non-magnetic impurity does not change macroscopic properties of s-wave Fermi superfluids, depending on its shape and strength, a magnetic impurity can induce single or multiple mid-gap bound states. The multiple mid-gap states could coincide with the development of a Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase within the superfluid. As an analog of the Scanning Tunneling Microscope, we proposed a modified radio frequency spectroscopic method to measure the focal density of states which can be employed to detect these states and other quantum phases of cold atoms. A key result of our self consistent Bogoliubov-de Gennes calculations is that a magnetic impurity can controllably induce an FFLO state at currently accessible experimental parameters.

Female Meiosis: Synapsis, Recombination, and Segregation in Drosophila melanogaster

PubMed Central

Hughes, Stacie E.; Miller, Danny E.; Miller, Angela L.; Hawley, R. Scott

2018-01-01

A century of genetic studies of the meiotic process in Drosophila melanogaster females has been greatly augmented by both modern molecular biology and major advances in cytology. These approaches, and the findings they have allowed, are the subject of this review. Specifically, these efforts have revealed that meiotic pairing in Drosophila females is not an extension of somatic pairing, but rather occurs by a poorly understood process during premeiotic mitoses. This process of meiotic pairing requires the function of several components of the synaptonemal complex (SC). When fully assembled, the SC also plays a critical role in maintaining homolog synapsis and in facilitating the maturation of double-strand breaks (DSBs) into mature crossover (CO) events. Considerable progress has been made in elucidating not only the structure, function, and assembly of the SC, but also the proteins that facilitate the formation and repair of DSBs into both COs and noncrossovers (NCOs). The events that control the decision to mature a DSB as either a CO or an NCO, as well as determining which of the two CO pathways (class I or class II) might be employed, are also being characterized by genetic and genomic approaches. These advances allow a reconsideration of meiotic phenomena such as interference and the centromere effect, which were previously described only by genetic studies. In delineating the mechanisms by which the oocyte controls the number and position of COs, it becomes possible to understand the role of CO position in ensuring the proper orientation of homologs on the first meiotic spindle. Studies of bivalent orientation have occurred in the context of numerous investigations into the assembly, structure, and function of the first meiotic spindle. Additionally, studies have examined the mechanisms ensuring the segregation of chromosomes that have failed to undergo crossing over. PMID:29487146

PVT: An Efficient Computational Procedure to Speed up Next-generation Sequence Analysis

PubMed Central

2014-01-01

Background High-throughput Next-Generation Sequencing (NGS) techniques are advancing genomics and molecular biology research. This technology generates substantially large data which puts up a major challenge to the scientists for an efficient, cost and time effective solution to analyse such data. Further, for the different types of NGS data, there are certain common challenging steps involved in analysing those data. Spliced alignment is one such fundamental step in NGS data analysis which is extremely computational intensive as well as time consuming. There exists serious problem even with the most widely used spliced alignment tools. TopHat is one such widely used spliced alignment tools which although supports multithreading, does not efficiently utilize computational resources in terms of CPU utilization and memory. Here we have introduced PVT (Pipelined Version of TopHat) where we take up a modular approach by breaking TopHat’s serial execution into a pipeline of multiple stages, thereby increasing the degree of parallelization and computational resource utilization. Thus we address the discrepancies in TopHat so as to analyze large NGS data efficiently. Results We analysed the SRA dataset (SRX026839 and SRX026838) consisting of single end reads and SRA data SRR1027730 consisting of paired-end reads. We used TopHat v2.0.8 to analyse these datasets and noted the CPU usage, memory footprint and execution time during spliced alignment. With this basic information, we designed PVT, a pipelined version of TopHat that removes the redundant computational steps during ‘spliced alignment’ and breaks the job into a pipeline of multiple stages (each comprising of different step(s)) to improve its resource utilization, thus reducing the execution time. Conclusions PVT provides an improvement over TopHat for spliced alignment of NGS data analysis. PVT thus resulted in the reduction of the execution time to ~23% for the single end read dataset. Further, PVT designed for paired end reads showed an improved performance of ~41% over TopHat (for the chosen data) with respect to execution time. Moreover we propose PVT-Cloud which implements PVT pipeline in cloud computing system. PMID:24894600

PVT: an efficient computational procedure to speed up next-generation sequence analysis.

PubMed

Maji, Ranjan Kumar; Sarkar, Arijita; Khatua, Sunirmal; Dasgupta, Subhasis; Ghosh, Zhumur

2014-06-04

High-throughput Next-Generation Sequencing (NGS) techniques are advancing genomics and molecular biology research. This technology generates substantially large data which puts up a major challenge to the scientists for an efficient, cost and time effective solution to analyse such data. Further, for the different types of NGS data, there are certain common challenging steps involved in analysing those data. Spliced alignment is one such fundamental step in NGS data analysis which is extremely computational intensive as well as time consuming. There exists serious problem even with the most widely used spliced alignment tools. TopHat is one such widely used spliced alignment tools which although supports multithreading, does not efficiently utilize computational resources in terms of CPU utilization and memory. Here we have introduced PVT (Pipelined Version of TopHat) where we take up a modular approach by breaking TopHat's serial execution into a pipeline of multiple stages, thereby increasing the degree of parallelization and computational resource utilization. Thus we address the discrepancies in TopHat so as to analyze large NGS data efficiently. We analysed the SRA dataset (SRX026839 and SRX026838) consisting of single end reads and SRA data SRR1027730 consisting of paired-end reads. We used TopHat v2.0.8 to analyse these datasets and noted the CPU usage, memory footprint and execution time during spliced alignment. With this basic information, we designed PVT, a pipelined version of TopHat that removes the redundant computational steps during 'spliced alignment' and breaks the job into a pipeline of multiple stages (each comprising of different step(s)) to improve its resource utilization, thus reducing the execution time. PVT provides an improvement over TopHat for spliced alignment of NGS data analysis. PVT thus resulted in the reduction of the execution time to ~23% for the single end read dataset. Further, PVT designed for paired end reads showed an improved performance of ~41% over TopHat (for the chosen data) with respect to execution time. Moreover we propose PVT-Cloud which implements PVT pipeline in cloud computing system.

Frequencies of micronucleated reticulocytes, a dosimeter of DNA double-strand breaks, in infants receiving computed tomography or cardiac catheterization.

PubMed

Khattab, Mona; Walker, Dale M; Albertini, Richard J; Nicklas, Janice A; Lundblad, Lennart K A; Vacek, Pamela M; Walker, Vernon E

2017-08-01

The use of computed tomography (CT scans) has increased dramatically in recent decades, raising questions about the long-term safety of CT-emitted x-rays especially in infants who are more sensitive to radiation-induced effects. Cancer risk estimates for CT scans typically are extrapolated from models; therefore, new approaches measuring actual DNA damage are needed for improved estimations. Hence, changes in a dosimeter of DNA double-strand breaks, micronucleated reticulocytes (MN-RETs) measured by flow cytometry, were investigated in mice and infants exposed to CT scans. In male C57BL/6N mice (6-8 weeks-of-age), there was a dose-related increase in MN-RETs in blood samples collected 48h after CT scans delivering targeted exposures of 1-130 cGy x-rays (n=5-10/group, r=0.994, p=0.01), with significant increases occurring at exposure levels as low as 0.83 cGy x-rays compared to control mice (p=0.002). In paired blood specimens from infants with no history of a prior CT scan, there was no difference in MN-RET frequencies found 2h before (mean, 0.10±0.07%) versus 48h after (mean, 0.11±0.05%) a scheduled CT scan/cardiac catheterization. However, in infants having prior CT scan(s), MN-RET frequencies measured at 48h after a scheduled CT scan (mean=0.22±0.12%) were significantly higher than paired baseline values (mean, 0.17±0.07%; p=0.032). Increases in baseline (r=0.722, p<0.001) and 48-h post exposure (r=0.682, p<0.001) levels of MN-RETs in infants with a history of prior CT scans were significantly correlated with the number of previous CT scans. These preliminary findings suggest that prior CT scans increase the cellular responses to subsequent CT exposures. Thus, further investigation is needed to characterize the potential cancer risk from single versus repeated CT scans or cardiac catheterizations in infants. Copyright © 2017 Elsevier B.V. All rights reserved.

A comparison of G2 phase radiation-induced chromatid break kinetics using calyculin-PCC with those obtained using colcemid block.

PubMed

Bryant, Peter E; Mozdarani, Hossein

2007-09-01

To study the possible influence of cell-cycle delay on cells reaching mitosis during conventional radiation-induced chromatid break experiments using colcemid as a blocking agent, we have compared the chromatid break kinetics following a single dose of gamma rays (0.75 Gy) in metaphase CHO cells using calyculin-induced premature chromosome condensation (PCC), with those using colcemid block. Calyculin-induced PCC causes very rapid condensation of G2 cell chromosomes without the need for a cell to progress to mitosis, hence eliminating any effect of cell-cycle checkpoint on chromatid break frequency. We found that the kinetics of the exponential first-order decrease in chromatid breaks with time after irradiation was similar (not significantly different) between the two methods of chromosome condensation. However, use of the calyculin-PCC technique resulted in a slightly increased rate of disappearance of chromatid breaks and thus higher frequencies of breaks at 1.5 and 2.5 h following irradiation. We also report on the effect of the nucleoside analogue ara A on chromatid break kinetics using the two chromosome condensation techniques. Ara A treatment of cells abrogated the decrease in chromatid breaks with time, both using the calyculin-PCC and colcemid methods. We conclude that cell-cycle delay may be a factor determining the absolute frequency of chromatid breaks at various times following irradiation of cells in G2 phase but that the first-order disappearance of chromatid breaks with time and its abrogation by ara A are not significantly influenced by the G2 checkpoint.

Controlled breaks as a fatigue countermeasure on the flight deck

NASA Technical Reports Server (NTRS)

Neri, David F.; Oyung, Raymond L.; Colletti, Laura M.; Mallis, Melissa M.; Tam, Patricia Y.; Dinges, David F.

2002-01-01

BACKGROUND: A major challenge for flight crews is the need to maintain vigilance during long, highly automated nighttime flights. No system currently exists to assist in managing alertness, and countermeasure options are limited. Surveys reveal many pilots use breaks as an in-flight countermeasure, but there have been no controlled studies of their effectiveness. HYPOTHESIS: We hypothesized that brief, regular breaks could improve alertness and performance during an overnight flight. METHOD: A 6-h, uneventful, nighttime flight in a Boeing 747-400 flight simulator was flown by fourteen two-man crews. The 14 subjects in the treatment group received 5 short breaks spaced hourly during cruise; the 14 subjects in the control group received 1 break in the middle of cruise. Continuous EEG/EOG, subjective sleepiness, and psychomotor vigilance performance data were collected. RESULTS: During the latter part of the night, the treatment group showed significant reductions for 15 min post-break in slow eye movements, theta-band activity, and unintended sleep episodes compared with the control group. The treatment group reported significantly greater subjective alertness for up to 25 min post-break, with strongest effects near the time of the circadian trough. There was no evidence of objective vigilance performance improvement at 15-25 min post-break, with expected performance deterioration occurring due to elevated sleep drive and circadian time. CONCLUSIONS: The physiological and subjective data indicate the breaks reduced nighttime sleepiness for at least 15 min post-break and may have masked sleepiness for up to 25 min, suggesting the potential usefulness of short-duration breaks as an in-flight fatigue countermeasure.

Controlled breaks as a fatigue countermeasure on the flight deck.

PubMed

Neri, David F; Oyung, Raymond L; Colletti, Laura M; Mallis, Melissa M; Tam, Patricia Y; Dinges, David F

2002-07-01

A major challenge for flight crews is the need to maintain vigilance during long, highly automated nighttime flights. No system currently exists to assist in managing alertness, and countermeasure options are limited. Surveys reveal many pilots use breaks as an in-flight countermeasure, but there have been no controlled studies of their effectiveness. We hypothesized that brief, regular breaks could improve alertness and performance during an overnight flight. A 6-h, uneventful, nighttime flight in a Boeing 747-400 flight simulator was flown by fourteen two-man crews. The 14 subjects in the treatment group received 5 short breaks spaced hourly during cruise; the 14 subjects in the control group received 1 break in the middle of cruise. Continuous EEG/EOG, subjective sleepiness, and psychomotor vigilance performance data were collected. During the latter part of the night, the treatment group showed significant reductions for 15 min post-break in slow eye movements, theta-band activity, and unintended sleep episodes compared with the control group. The treatment group reported significantly greater subjective alertness for up to 25 min post-break, with strongest effects near the time of the circadian trough. There was no evidence of objective vigilance performance improvement at 15-25 min post-break, with expected performance deterioration occurring due to elevated sleep drive and circadian time. The physiological and subjective data indicate the breaks reduced nighttime sleepiness for at least 15 min post-break and may have masked sleepiness for up to 25 min, suggesting the potential usefulness of short-duration breaks as an in-flight fatigue countermeasure.

Water level effects on breaking wave setup for Pacific Island fringing reefs

NASA Astrophysics Data System (ADS)

Becker, J. M.; Merrifield, M. A.; Ford, M.

2014-02-01

The effects of water level variations on breaking wave setup over fringing reefs are assessed using field measurements obtained at three study sites in the Republic of the Marshall Islands and the Mariana Islands in the western tropical Pacific Ocean. At each site, reef flat setup varies over the tidal range with weaker setup at high tide and stronger setup at low tide for a given incident wave height. The observed water level dependence is interpreted in the context of radiation stress gradients specified by an idealized point break model generalized for nonnormally incident waves. The tidally varying setup is due in part to depth-limited wave heights on the reef flat, as anticipated from previous reef studies, but also to tidally dependent breaking on the reef face. The tidal dependence of the breaking is interpreted in the context of the point break model in terms of a tidally varying wave height to water depth ratio at breaking. Implications for predictions of wave-driven setup at reef-fringed island shorelines are discussed.

Deep simple epicotyl morphophysiological dormancy in seeds of two Viburnum species, with special reference to shoot growth and development inside the seed.

PubMed

Chien, Ching-Te; Chen, Shun-Ying; Tsai, Ching-Chu; Baskin, Jerry M; Baskin, Carol C; Kuo-Huang, Ling-Long

2011-07-01

In seeds with deep simple epicotyl morphophysiological dormancy, warm and cold stratification are required to break dormancy of the radicle and shoot, respectively. Although the shoot remains inside the seed all winter, little is known about its growth and morphological development prior to emergence in spring. The aims of the present study were to determine the temperature requirements for radicle and shoot emergence in seeds of Viburnum betulifolium and V. parvifolium and to monitor growth of the epicotyl, plumule and cotyledons in root-emerged seeds. Fresh and pre-treated seeds of V. betulifolium and V. parvifolium were incubated under various temperature regimes and monitored for radicle and shoot emergence. Growth of the epicotyl and cotyledons at different stages was observed with dissecting and scanning electron microscopes. The optimum temperature for radicle emergence of seeds of both species, either kept continuously at a single regime or exposed to a sequence of regimes, was 20/10 °C. GA(3) had no effect on radicle emergence. Cold stratification (5 °C) was required for shoot emergence. The shoot apical meristem in fresh seeds did not form a bulge until the embryo had grown to the critical length for radicle emergence. After radicle emergence, the epicotyl--plumule and cotyledons grew slowly at 5 and 20/10 °C, and the first pair of true leaves was initiated. However, the shoot emerged only from seeds that received cold stratification. Seeds of V. betulifolium and V. parvifolium have deep simple epicotyl morphophysiological dormancy, C(1b)B (root)-C(3) (epicotyl). Warm stratification was required to break the first part of physiological dormancy (PD), thereby allowing embryo growth and subsequently radicle emergence. Although cold stratification was not required for differentiation of the epicotyl--plumule, it was required to break the second part of PD, thereby allowing the shoot to emerge in spring.

Deep simple epicotyl morphophysiological dormancy in seeds of two Viburnum species, with special reference to shoot growth and development inside the seed

PubMed Central

Chien, Ching-Te; Chen, Shun-Ying; Tsai, Ching-Chu; Baskin, Jerry M.; Baskin, Carol C.; Kuo-Huang, Ling-Long

2011-01-01

Background and Aims In seeds with deep simple epicotyl morphophysiological dormancy, warm and cold stratification are required to break dormancy of the radicle and shoot, respectively. Although the shoot remains inside the seed all winter, little is known about its growth and morphological development prior to emergence in spring. The aims of the present study were to determine the temperature requirements for radicle and shoot emergence in seeds of Viburnum betulifolium and V. parvifolium and to monitor growth of the epicotyl, plumule and cotyledons in root-emerged seeds. Methods Fresh and pre-treated seeds of V. betulifolium and V. parvifolium were incubated under various temperature regimes and monitored for radicle and shoot emergence. Growth of the epicotyl and cotyledons at different stages was observed with dissecting and scanning electron microscopes. Key Results The optimum temperature for radicle emergence of seeds of both species, either kept continuously at a single regime or exposed to a sequence of regimes, was 20/10 °C. GA3 had no effect on radicle emergence. Cold stratification (5 °C) was required for shoot emergence. The shoot apical meristem in fresh seeds did not form a bulge until the embryo had grown to the critical length for radicle emergence. After radicle emergence, the epicotyl–plumule and cotyledons grew slowly at 5 and 20/10 °C, and the first pair of true leaves was initiated. However, the shoot emerged only from seeds that received cold stratification. Conclusions Seeds of V. betulifolium and V. parvifolium have deep simple epicotyl morphophysiological dormancy, C1bB (root)–C3 (epicotyl). Warm stratification was required to break the first part of physiological dormancy (PD), thereby allowing embryo growth and subsequently radicle emergence. Although cold stratification was not required for differentiation of the epicotyl–plumule, it was required to break the second part of PD, thereby allowing the shoot to emerge in spring. PMID:21562028

Mode structure symmetry breaking of energetic particle driven beta-induced Alfvén eigenmode

NASA Astrophysics Data System (ADS)

Lu, Z. X.; Wang, X.; Lauber, Ph.; Zonca, F.

2018-01-01

The mode structure symmetry breaking of energetic particle driven Beta-induced Alfvén Eigenmode (BAE) is studied based on global theory and simulation. The weak coupling formula gives a reasonable estimate of the local eigenvalue compared with global hybrid simulation using XHMGC. The non-perturbative effect of energetic particles on global mode structure symmetry breaking in radial and parallel (along B) directions is demonstrated. With the contribution from energetic particles, two dimensional (radial and poloidal) BAE mode structures with symmetric/asymmetric tails are produced using an analytical model. It is demonstrated that the symmetry breaking in radial and parallel directions is intimately connected. The effects of mode structure symmetry breaking on nonlinear physics, energetic particle transport, and the possible insight for experimental studies are discussed.

Raman amplification in the coherent wave-breaking regime.

PubMed

Farmer, J P; Pukhov, A

2015-12-01

In regimes far beyond the wave-breaking threshold of Raman amplification, we show that significant amplification can occur after the onset of wave breaking, before phase mixing destroys the coherent coupling between pump, probe, and plasma wave. Amplification in this regime is therefore a transient effect, with the higher-efficiency "coherent wave-breaking" (CWB) regime accessed by using a short, intense probe. Parameter scans illustrate the marked difference in behavior between below wave breaking, in which the energy-transfer efficiency is high but total energy transfer is low, wave breaking, in which efficiency is low, and CWB, in which moderate efficiencies allow the highest total energy transfer.

Development of a dual-axis hybrid-type tactile sensor using PET film

NASA Astrophysics Data System (ADS)

Seonggi, Kim; Koo, Ja Choon; Choi, Hyouk Ryeol; Moon, Hyungpil

2013-04-01

In previous work, a dual-axis hybrid-type tactile sensor using PDMS (Polydimethylsiloxane) with a pair of metal electrodes, (which were deposited directly on the PDMS surface), was proposed. The hybrid sensor can measure the normal force and the shear force from the measurement of the change of capacitance and resistance values from the one pair of electrodes. However, the metal is hard to be deposited on the surface of the PDMS because the PDMS is hydrophobic. The hydrophobic surface can be changed to hydrophilic using O2 Plasma treatment or UV treatment. When O2 plasma treatment or UV treatment is used, there is the problem that the processing of the metal deposition and the wiring completed in a very short period of limited time. Also, the deposited metal on the surface of the PDMS is easy to break because the deposited metal is exposed in the air. In this paper, we propose a dual-axis hybrid-type tactile sensor where the PET (polyethylene terephthalate) film is inserted between the PDMS films. The deposited metal is not removed easily from the PET film because the adhesion is strong. Also, the PDMS surrounding the PET film plays the roles of dielectric elastomer and shielding the deposited metal from the external environment at same time. Experimental results verify the effectiveness of the fabricated dual-axis hybrid-type force sensor.

A single-molecule sequencing assay for the comprehensive profiling of T4 DNA ligase fidelity and bias during DNA end-joining.

PubMed

Potapov, Vladimir; Ong, Jennifer L; Langhorst, Bradley W; Bilotti, Katharina; Cahoon, Dan; Canton, Barry; Knight, Thomas F; Evans, Thomas C; Lohman, Gregory Js

2018-05-08

DNA ligases are key enzymes in molecular and synthetic biology that catalyze the joining of breaks in duplex DNA and the end-joining of DNA fragments. Ligation fidelity (discrimination against the ligation of substrates containing mismatched base pairs) and bias (preferential ligation of particular sequences over others) have been well-studied in the context of nick ligation. However, almost no data exist for fidelity and bias in end-joining ligation contexts. In this study, we applied Pacific Biosciences Single-Molecule Real-Time sequencing technology to directly sequence the products of a highly multiplexed ligation reaction. This method has been used to profile the ligation of all three-base 5'-overhangs by T4 DNA ligase under typical ligation conditions in a single experiment. We report the relative frequency of all ligation products with or without mismatches, the position-dependent frequency of each mismatch, and the surprising observation that 5'-TNA overhangs ligate extremely inefficiently compared to all other Watson-Crick pairings. The method can easily be extended to profile other ligases, end-types (e.g. blunt ends and overhangs of different lengths), and the effect of adjacent sequence on the ligation results. Further, the method has the potential to provide new insights into the thermodynamics of annealing and the kinetics of end-joining reactions.

A Link between Meiotic Prophase Progression and CrossoverControl

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carlton, Peter M.; Farruggio, Alfonso P.; Dernburg, Abby F.

2005-07-06

During meiosis, most organisms ensure that homologous chromosomes undergo at least one exchange of DNA, or crossover, to link chromosomes together and accomplish proper segregation. How each chromosome receives a minimum of one crossover is unknown. During early meiosis in Caenorhabditis elegans and many other species, chromosomes adopt a polarized organization within the nucleus, which normally disappears upon completion of homolog synapsis. Mutations that impair synapsis even between a single pair of chromosomes in C. elegans delay this nuclear reorganization. We quantified this delay by developing a classification scheme for discrete stages of meiosis. Immunofluorescence localization of RAD-51 protein revealedmore » that delayed meiotic cells also contained persistent recombination intermediates. Through genetic analysis, we found that this cytological delay in meiotic progression requires double-strand breaks and the function of the crossover-promoting heteroduplex HIM-14 (Msh4) and MSH-5. Failure of X chromosome synapsis also resulted in impaired crossover control on autosomes, which may result from greater numbers and persistence of recombination intermediates in the delayed nuclei. We conclude that maturation of recombination events on chromosomes promotes meiotic progression, and is coupled to the regulation of crossover number and placement. Our results have broad implications for the interpretation of meiotic mutants, as we have shown that asynapsis of a single chromosome pair can exert global effects on meiotic progression and recombination frequency.« less

Addition by subtraction in coupled-cluster theory: a reconsideration of the CC and CI interface and the nCC hierarchy.

PubMed

Bartlett, Rodney J; Musiał, Monika

2006-11-28

The nCC hierarchy of coupled-cluster approximations, where n guarantees exactness for n electrons and all products of n electrons are derived and applied to several illustrative problems. The condition of exactness for n=2 defines nCCSD=2CC, with nCCSDT=3CC and nCCSDTQ=4CC being exact for three and four electrons. To achieve this, the minimum number of diagrams is evaluated, which is less than in the corresponding CC model. For all practical purposes, nCC is also the proper definition of a size-extensive CI. 2CC is also an orbitally invariant coupled electron pair approximation. The numerical results of nCC are close to those for the full CC variant, and in some cases are closer to the full CI reference result. As 2CC is exact for separated electron pairs, it is the natural zeroth-order approximation for the correlation problem in molecules with other effects introduced as these units start to interact. The nCC hierarchy of approximations has all the attractive features of CC including its size extensivity, orbital invariance, and orbital insensitivity, but in a conceptually appealing form suited to bond breaking, while being computationally less demanding. Excited states from the equation of motion (EOM-2CC) are also reported, which show results frequently approaching those of EOM-CCSDT.

Effects of cluster-shell competition and BCS-like pairing in 12C

NASA Astrophysics Data System (ADS)

Matsuno, H.; Itagaki, N.

2017-12-01

The antisymmetrized quasi-cluster model (AQCM) was proposed to describe α-cluster and jj-coupling shell models on the same footing. In this model, the cluster-shell transition is characterized by two parameters, R representing the distance between α clusters and Λ describing the breaking of α clusters, and the contribution of the spin-orbit interaction, very important in the jj-coupling shell model, can be taken into account starting with the α-cluster model wave function. Not only the closure configurations of the major shells but also the subclosure configurations of the jj-coupling shell model can be described starting with the α-cluster model wave functions; however, the particle-hole excitations of single particles have not been fully established yet. In this study we show that the framework of AQCM can be extended even to the states with the character of single-particle excitations. For ^{12}C, two-particle-two-hole (2p2h) excitations from the subclosure configuration of 0p_{3/2} corresponding to a BCS-like pairing are described, and these shell model states are coupled with the three α-cluster model wave functions. The correlation energy from the optimal configuration can be estimated not only in the cluster part but also in the shell model part. We try to pave the way to establish a generalized description of the nuclear structure.

HVOSM Studies of Cross-Slope Break on Highway Curves. Phase II Task C

DOT National Transportation Integrated Search

1982-05-01

This research was conducted to investigate the operational effects of cross-slope breaks on highway curves. These breaks are created by the superelevation of the traveled way and the adverse shoulder slope. HVOSM simulation studies were performed on ...

Evaluation of the break-out square post breakaway system.

DOT National Transportation Integrated Search

2015-02-01

Determine the effectiveness of the Break-Out Square (BOS) Post coupler as a : possible alternative to other breakaway devices. This product is designed to (upon : impact) break flush with grade with no damage apparent to base or anchor and offer a : ...

Cosmic bubble and domain wall instabilities III: the role of oscillons in three-dimensional bubble collisions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bond, J. Richard; Braden, Jonathan; Mersini-Houghton, Laura, E-mail: bond@cita.utoronto.ca, E-mail: j.braden@ucl.ac.uk, E-mail: mersini@physics.unc.edu

2015-09-01

We study collisions between pairs of bubbles nucleated in an ambient false vacuum. For the first time, we include the effects of small initial (quantum) fluctuations around the instanton profiles describing the most likely initial bubble profile. Past studies of this problem neglect these fluctuations and work under the assumption that the collisions posess an exact SO(2,1) symmetry. We use three-dimensional lattice simulations to demonstrate that for double-well potentials, small initial perturbations to this symmetry can be amplified as the system evolves. Initially the amplification is well-described by linear perturbation theory around the SO(2,1) background, but the onset of strongmore » nonlinearities amongst the fluctuations quickly leads to a drastic breaking of the original SO(2,1) symmetry and the production of oscillons in the collision region. We explore several single-field models, and we find it is hard to both realize inflation inside of a bubble and produce oscillons in a collision. Finally, we extend our results to a simple two-field model. The additional freedom allowed by the second field allows us to construct viable inflationary models that allow oscillon production in collisions. The breaking of the SO(2,1) symmetry allows for a new class of observational signatures from bubble collisions that do not posess azimuthal symmetry, including the production of gravitational waves which cannot be supported by an SO(2,1) spacetime.« less

Symmetry-breaking Hopf bifurcations to 1-, 2-, and 3-tori in small-aspect-ratio counterrotating Taylor-Couette flow.

PubMed

Altmeyer, S; Do, Y; Marques, F; Lopez, J M

2012-10-01

The nonlinear dynamics of Taylor-Couette flow in a small-aspect-ratio wide-gap annulus in the counterrotating regime is investigated by solving the full three-dimensional Navier-Stokes equations. The system is invariant under arbitrary rotations about the axis, reflection about the annulus midplane, and time translations. A systematic investigation is presented both in terms of the flow physics elucidated from the numerical simulations and from a dynamical system perspective provided by equivariant normal form theory. The dynamics are primarily associated with the behavior of the jet of angular momentum that emerges from the inner cylinder boundary layer at about the midplane. The sequence of bifurcations as the differential rotation is increased consists of an axisymmetric Hopf bifurcation breaking the reflection symmetry of the basic state leading to an axisymmetric limit cycle with a half-period-flip spatiotemporal symmetry. This undergoes a Hopf bifurcation breaking axisymmetry, leading to quasiperiodic solutions evolving on a 2-torus that is setwise symmetric. These undergo a further Hopf bifurcation, introducing a third incommensurate frequency leading to a 3-torus that is also setwise symmetric. On the 3-torus, as the differential rotation is further increased, a saddle-node-invariant-circle bifurcation takes place, destroying the 3-torus and leaving a pair of symmetrically related 2-tori states on which all symmetries of the system have been broken.

Low concentration of arsenite exacerbates UVR-induced DNA strand breaks by inhibiting PARP-1 activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qin Xujun; Department of Toxicology, Fourth Military Medical University, Xi'an, Shaanxi, 710032; Hudson, Laurie G.

2008-10-01

Epidemiological studies have associated arsenic exposure with many types of human cancers. Arsenic has also been shown to act as a co-carcinogen even at low concentrations. However, the precise mechanism of its co-carcinogenic action is unknown. Recent studies indicate that arsenic can interfere with DNA-repair processes. Poly(ADP-ribose) polymerase (PARP)-1 is a zinc-finger DNA-repair protein, which can promptly sense DNA strand breaks and initiate DNA-repair pathways. In the present study, we tested the hypothesis that low concentrations of arsenic could inhibit PAPR-1 activity and so exacerbate levels of ultraviolet radiation (UVR)-induced DNA strand breaks. HaCat cells were treated with arsenite and/ormore » UVR, and then DNA strand breaks were assessed by comet assay. Low concentrations of arsenite ({<=} 2 {mu}M) alone did not induce significant DNA strand breaks, but greatly enhanced the DNA strand breaks induced by UVR. Further studies showed that 2 {mu}M arsenite effectively inhibited PARP-1 activity. Zinc supplementation of arsenite-treated cells restored PARP-1 activity and significantly diminished the exacerbating effect of arsenite on UVR-induced DNA strand breaks. Importantly, neither arsenite treatment, nor zinc supplementation changed UVR-triggered reactive oxygen species (ROS) formation, suggesting that their effects upon UVR-induced DNA strand breaks are not through a direct free radical mechanism. Combination treatments of arsenite with PARP-1 inhibitor 3-aminobenzamide or PARP-1 siRNA demonstrate that PARP-1 is the target of arsenite. Together, these findings show that arsenite at low concentration exacerbates UVR-induced DNA strand breaks by inhibiting PARP-1 activity, which may represent an important mechanism underlying the co-carcinogenicity of arsenic.« less

Effect of an Intervention to Break the Gender Bias Habit for Faculty at One Institution: A Cluster Randomized, Controlled Trial

PubMed Central

Carnes, Molly; Devine, Patricia G.; Manwell, Linda Baier; Byars-Winston, Angela; Fine, Eve; Ford, Cecilia E.; Forscher, Patrick; Isaac, Carol; Kaatz, Anna; Magua, Wairimu; Palta, Mari; Sheridan, Jennifer

2014-01-01

Purpose Despite sincere commitment to egalitarian, meritocratic principles, subtle gender bias persists, constraining women’s opportunities for academic advancement. The authors implemented a pair-matched, single-blind, cluster-randomized, controlled study of a gender bias habit-changing intervention at a large public university. Method Participants were faculty in 92 departments or divisions at the University of Wisconsin-Madison. Between September 2010 and March 2012, experimental departments were offered a gender bias habit-changing intervention as a 2.5 hour workshop. Surveys measured gender bias awareness; motivation, self-efficacy, and outcome expectations to reduce bias; and gender equity action. A timed word categorization task measured implicit gender/leadership bias. Faculty completed a worklife survey before and after all experimental departments received the intervention. Control departments were offered workshops after data were collected. Results Linear mixed-effects models showed significantly greater changes post-intervention for faculty in experimental vs. control departments on several outcome measures, including self-efficacy to engage in gender equity promoting behaviors (P = .013). When ≥ 25% of a department’s faculty attended the workshop (26 of 46 departments), significant increases in self-reported action to promote gender equity occurred at 3 months (P = .007). Post-intervention, faculty in experimental departments expressed greater perceptions of fit (P = .024), valuing of their research (P = .019), and comfort in raising personal and professional conflicts (P = .025). Conclusions An intervention that facilitates intentional behavioral change can help faculty break the gender bias habit and change department climate in ways that should support the career advancement of women in academic medicine, science, and engineering. PMID:25374039

The Effect of Multiple Sulfatase Deficiency (MSD) on Dental Development: Can We Use the Teeth as an Early Diagnostic Tool?

PubMed

Zilberman, Uri; Bibi, Haim

2016-01-01

Multiple sulfatase deficiency (MSD) is a rare autosomal recessive inborn error of metabolism due to reduced catalytic activity of the different sulfatase. Affected individuals show neurologic deterioration with mental retardation, skeletal anomalies, organomegaly, and skin changes as in X-linked ichthyosis. The only organ that was not examined in MSD patients is the dentition. To evaluate the effect of the metabolic error on dental development in a patient with the intermediate severe late-infantile form of MSD (S155P). Histological and chemical study were performed on three deciduous and five permanent teeth from MSD patient and pair-matched normal patients. Tooth germ size and enamel thickness were reduced in both deciduous and permanent MSD teeth, and the scalloping feature of the DEJ was missing in MSD teeth causing enamel to break off from the dentin. The mineral components in the enamel and dentin were different. The metabolic error insults the teeth in the stage of organogenesis in both the deciduous and permanent dentition. The end result is teeth with very sharp cusp tips, thin hypomineralized enamel, and exposed dentin due to the break off of enamel. These findings are different from all other types of MPS syndromes.Clinically the phenotype of intermediate severe late-infantile form of MSD appeared during the third year of life. In children of parents that are carriers, we can diagnose the disease as early as birth using X-ray radiograph of the anterior upper region or as early as 6-8 months when the first deciduous tooth erupt and consider very early treatment to ameliorate the symptoms.

Instability of vortex pair leapfrogging

NASA Astrophysics Data System (ADS)

Tophøj, Laust; Aref, Hassan

2013-01-01

Leapfrogging is a periodic solution of the four-vortex problem with two positive and two negative point vortices all of the same absolute circulation arranged as co-axial vortex pairs. The set of co-axial motions can be parameterized by the ratio 0 < α < 1 of vortex pair sizes at the time when one pair passes through the other. Leapfrogging occurs for α > σ2, where σ = sqrt{2}-1 is the silver ratio. The motion is known in full analytical detail since the 1877 thesis of Gröbli and a well known 1894 paper by Love. Acheson ["Instability of vortex leapfrogging," Eur. J. Phys. 21, 269-273 (2000)], 10.1088/0143-0807/21/3/310 determined by numerical experiments that leapfrogging is linearly unstable for σ2 < α < 0.382, but apparently stable for larger α. Here we derive a linear system of equations governing small perturbations of the leapfrogging motion. We show that symmetry-breaking perturbations are essentially governed by a 2D linear system with time-periodic coefficients and perform a Floquet analysis. We find transition from linearly unstable to stable leapfrogging at α = ϕ2 ≈ 0.381966, where φ = 1/2(sqrt{5}-1) is the golden ratio. Acheson also suggested that there was a sharp transition between a "disintegration" instability mode, where two 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. Tophøj and H. Aref, "Chaotic scattering of two identical point vortex pairs revisited," Phys. Fluids 20, 093605 (2008)], 10.1063/1.2974830. Both leapfrogging and "walkabout" motions can appear as intermediate states in chaotic scattering at the same values of linear impulse and energy.

Determination of chloride in brazilian crude oils by ion chromatography after extraction induced by emulsion breaking.

PubMed

Robaina, Nicolle F; Feiteira, Fernanda N; Cassella, Alessandra R; Cassella, Ricardo J

2016-08-05

The present paper reports on the development of a novel extraction induced by emulsion breaking (EIEB) method for the determination of chloride in crude oils. The proposed method was based on the formation and breaking of oil-in-water emulsions with the samples and the consequential transference of the highly water-soluble chloride to the aqueous phase during emulsion breaking, which was achieved by centrifugation. The determination of chloride in the extracts was performed by ion chromatography (IC) with conductivity detection. Several parameters (oil phase:aqueous phase ratio, crude oil:mineral oil ratio, shaking time and type and concentration of surfactant) that could affect the performance of the method were evaluated. Total extraction of chloride from samples could be achieved when 1.0g of oil phase (0.5g of sample+0.5g of mineral oil) was emulsified in 5mL of a 2.5% (m/v) solution of Triton X-114. The obtained emulsion was shaken for 60min and broken by centrifugation for 5min at 5000rpm. The separated aqueous phase was collected, filtered and diluted before analysis by IC. Under these conditions, the limit of detection was 0.5μgg(-1) NaCl and the limit of quantification was 1.6μgg(-1) NaCl. We applied the method to the determination of chloride in six Brazilian crude oils and the results did not differ statistically from those obtained by the ASTM D6470 method when the paired Student-t-test, at 95% confidence level, was applied. Copyright © 2016 Elsevier B.V. All rights reserved.

Analysis of free-time contingencies as positive versus negative reinforcement.

PubMed

Zarcone, J R; Fisher, W W; Piazza, C C

1996-01-01

Providing a short break contingent on completed work may increase responding through positive reinforcement (e.g., access to preferred activities) or negative reinforcement (e.g., escape form work). In this investigation, three analyses conducted with a boy with profound mental retardation showed that (a) a 20-s break increased responding more than a positive reinforcer (cola) did, and (b) the reinforcing effect of a 20-s break were affected by the availability of positive reinforcers during the break were affected by the availability of positive reinforcers during the break.

Two-Channel Kondo Physics due to As Vacancies in the Layered Compound ZrAs1.58Se0.39

NASA Astrophysics Data System (ADS)

Kirchner, Stefan; Cichorek, T.; Bochenek, L.; Schmidt, M.; Niewa, R.; Czuluccki, A.; Auffermann, G.; Steglich, F.; Kniep, R.

We address the origin of the magnetic-field independent - | A | T 1 / 2 term observed in the low-temperature resistivity of several As-based metallic systems of the PbFCl structure type. For the layered compound ZrAs1.58Se0.39, we show that vacancies in the square nets of As give rise to the low-temperature transport anomaly over a wide temperature regime of almost two decades in temperature. This low-temperature behavior is in line with the non-magnetic version of the two-channel Kondo effect, whose origin we ascribe to a dynamic Jahn-Teller effect operating at the vacancy-carrying As layer with a C4 symmetry. The pair-breaking nature of the dynamical defects in the square nets of As explains the low superconducting transition temperature Tc 0 . 14 K of ZrAs1.58Se0.39, as compared to the free-of-vacancies homologue ZrP1.54S0.46 (Tc 3 . 7 K). Our findings should be relevant to a wide class of metals with disordered pnictogen layers.

Two-Channel Kondo Physics due to As Vacancies in the Layered Compound ZrAs1.58 Se0.39

NASA Astrophysics Data System (ADS)

Cichorek, T.; Bochenek, L.; Schmidt, M.; Czulucki, A.; Auffermann, G.; Kniep, R.; Niewa, R.; Steglich, F.; Kirchner, S.

2016-09-01

We address the origin of the magnetic-field-independent -|A |T1 /2 term observed in the low-temperature resistivity of several As-based metallic systems of the PbFCl structure type. For the layered compound ZrAs1.58 Se0.39 , we show that vacancies in the square nets of As give rise to the low-temperature transport anomaly over a wide temperature regime of almost two decades in temperature. This low-temperature behavior is in line with the nonmagnetic version of the two-channel Kondo effect, whose origin we ascribe to a dynamic Jahn-Teller effect operating at the vacancy-carrying As layer with a C4 symmetry. The pair-breaking nature of the dynamical defects in the square nets of As explains the low superconducting transition temperature Tc≈0.14 K of ZrAs1.58 Se0.39 compared to the free-of-vacancies homologue ZrP1.54 S0.46 (Tc≈3.7 K ). Our findings should be relevant to a wide class of metals with disordered pnictogen layers.

Symmetry-breaking bifurcations and enhanced mixing in microfluidic cross-slots

NASA Astrophysics Data System (ADS)

Poole, Rob; Haward, Simon; Oliveira, Paulo; Alves, Manuel

2014-11-01

We investigate, both experimentally and numerically, a new subcritical bifurcation phenomenon for a Newtonian fluid flowing through three-dimensional cross-slot geometries. At low Reynolds numbers the flow remains steady and symmetric. For the case of square inlets and outlets, at a critical Reynolds number of approximately 40 (based on average velocity) a pitchfork bifurcation is observed beyond which the unstable symmetrical solution is replaced by a pair of steady asymmetric solutions. Sensitivity of this critical Reynolds number to the initial conditions of the simulation, resulting in a small degree of hysteresis, suggests a subcritical instability. At higher flowrates the flow becomes unsteady. The effects of channel aspect ratio are investigated on the critical conditions and excellent agreement is found between three-dimensional finite volume simulations and flow visualisation experiments in microfluidic channels. Finally we suggest this new flow bifurcation could be an effective method of enhancing mixing in microfluidic channels as significant increases in mixing quality are observed beyond the bifurcation. This enhancement occurs at flowrates more than a factor of two smaller than those observed in the well-known T-channel micromixer.

Fluctuations in the DNA double helix

NASA Astrophysics Data System (ADS)

Peyrard, M.; López, S. C.; Angelov, D.

2007-08-01

DNA is not the static entity suggested by the famous double helix structure. It shows large fluctuational openings, in which the bases, which contain the genetic code, are temporarily open. Therefore it is an interesting system to study the effect of nonlinearity on the physical properties of a system. A simple model for DNA, at a mesoscopic scale, can be investigated by computer simulation, in the same spirit as the original work of Fermi, Pasta and Ulam. These calculations raise fundamental questions in statistical physics because they show a temporary breaking of equipartition of energy, regions with large amplitude fluctuations being able to coexist with regions where the fluctuations are very small, even when the model is studied in the canonical ensemble. This phenomenon can be related to nonlinear excitations in the model. The ability of the model to describe the actual properties of DNA is discussed by comparing theoretical and experimental results for the probability that base pairs open an a given temperature in specific DNA sequences. These studies give us indications on the proper description of the effect of the sequence in the mesoscopic model.

Effects of Co and Mn doping in K0.8Fe2-ySe2 revisited.

PubMed

Zhou, Tingting; Chen, Xiaolong; Guo, Jiangang; Jin, Shifeng; Wang, Gang; Lai, Xiaofang; Ying, Tianping; Zhang, Han; Shen, Shijie; Wang, Shunchong; Zhu, Kaixing

2013-07-10

Accumulated evidence indicates that phase separation occurs in potassium intercalated iron selenides, a superconducting phase coexisting with the antiferromagnetic phase K2Fe4Se5, the so-called '245 phase'. Here, we report a comparative study of substitution effects by Co and Mn for Fe sites in K0.8Fe2-ySe2 within the phase separation scenario. Our results demonstrate that Co and Mn dopants have distinct differences in occupancy and hence in the suppression mechanism of superconductivity upon doping of Fe sites. In K0.8Fe2-xCoxSe2, Co prefers to occupy the lattice of the superconducting phase and suppresses superconductivity very quickly, obeying the magnetic pair-breaking mechanism or the collapse of the Fermi surface nesting mechanism. In contrast, in K0.8Fe1.7-xMnxSe2, Mn shows no preferential occupancy in the superconducting phase or the 245 phase. The suppression of superconductivity can be attributed to restraining of the superconducting phase and meanwhile inducing another non-superconducting phase by Mn doping.

Topological BF field theory description of topological insulators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, Gil Young; Moore, Joel E., E-mail: jemoore@berkeley.edu; Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720

2011-06-15

Research Highlights: > We show that a BF theory is the effective theory of 2D and 3D topological insulators. > The non-gauge-invariance of the bulk theory yields surface terms for a bosonized Dirac fermion. > The 'axion' term in electromagnetism is correctly obtained from gapped surfaces. > Generalizations to possible fractional phases are discussed in closing. - Abstract: Topological phases of matter are described universally by topological field theories in the same way that symmetry-breaking phases of matter are described by Landau-Ginzburg field theories. We propose that topological insulators in two and three dimensions are described by a version ofmore » abelian BF theory. For the two-dimensional topological insulator or quantum spin Hall state, this description is essentially equivalent to a pair of Chern-Simons theories, consistent with the realization of this phase as paired integer quantum Hall effect states. The BF description can be motivated from the local excitations produced when a {pi} flux is threaded through this state. For the three-dimensional topological insulator, the BF description is less obvious but quite versatile: it contains a gapless surface Dirac fermion when time-reversal-symmetry is preserved and yields 'axion electrodynamics', i.e., an electromagnetic E . B term, when time-reversal symmetry is broken and the surfaces are gapped. Just as changing the coefficients and charges of 2D Chern-Simons theory allows one to obtain fractional quantum Hall states starting from integer states, BF theory could also describe (at a macroscopic level) fractional 3D topological insulators with fractional statistics of point-like and line-like objects.« less

Bud break responds more strongly to daytime than night-time temperature under asymmetric experimental warming.

PubMed

Rossi, Sergio; Isabel, Nathalie

2017-01-01

Global warming is diurnally asymmetric, leading to a less cold, rather than warmer, climate. We investigated the effects of asymmetric experimental warming on plant phenology by testing the hypothesis that daytime warming is more effective in advancing bud break than night-time warming. Bud break was monitored daily in Picea mariana seedlings belonging to 20 provenances from Eastern Canada and subjected to daytime and night-time warming in growth chambers at temperatures varying between 8 and 16 °C. The higher advancements of bud break and shorter times required to complete the phenological phases occurred with daytime warming. Seedlings responded to night-time warming, but still with less advancement of bud break than under daytime warming. No advancement was observed when night-time warming was associated with a daytime cooling. The effect of the treatments was uniform across provenances. Our observations realized under controlled conditions allowed to experimentally demonstrate that bud break can advance under night-time warming, but to a lesser extent than under daytime warming. Prediction models using daily timescales could neglect the diverging influence of asymmetric warming and should be recalibrated for higher temporal resolutions. © 2016 John Wiley & Sons Ltd.

Climate and floods still govern California levee breaks

USGS Publications Warehouse

Florsheim, J.L.; Dettinger, M.D.

2007-01-01

Even in heavily engineered river systems, climate still governs flood variability and thus still drives many levee breaks and geomorphic changes. We assemble a 155-year record of levee breaks for a major California river system to find that breaks occurred in 25% of years during the 20th Century. A relation between levee breaks and river discharge is present that sets a discharge threshold above which most levee breaks occurred. That threshold corresponds to small floods with recurrence intervals of ???2-3 years. Statistical analysis illustrates that levee breaks and peak discharges cycle (broadly) on a 12-15 year time scale, in time with warm-wet storm patterns in California, but more slowly or more quickly than ENSO and PDO climate phenomena, respectively. Notably, these variations and thresholds persist through the 20th Century, suggesting that historical flood-control effects have not reduced the occurrence or frequency of levee breaks. Copyright 2007 by the American Geophysical Union.

Extended Bose-Hubbard model with dipolar and contact interactions

NASA Astrophysics Data System (ADS)

Biedroń, Krzysztof; Łącki, Mateusz; Zakrzewski, Jakub

2018-06-01

We study the phase diagram of the one-dimensional boson gas trapped inside an optical lattice with contact and dipolar interaction, taking into account next-nearest terms for both tunneling and interaction. Using the density-matrix renormalization group, we calculate how the locations of phase transitions change with increasing dipolar interaction strength for average density ρ =1 . Furthermore, we show the emergence of pair-correlated phases for a large dipolar interaction strength and ρ ≥2 , including a supersolid phase with an incommensurate density wave ordering manifesting the corresponding spontaneous breaking of the translational symmetry.

[Studies of the repair of radiation-induced genetic damage in Drosophila]. Final progress report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hawley, R.S.

1998-11-01

This research focuses on the structure of the mei-41 gene and elucidation of the role the mei-41 gene product plays in both recombination and repair. Genetic and molecular studies are continuing on the mus308 locus and the mus312 and mei-9 genes. The author views mus312 as a very likely candidate for a gene required for both chromosome pairing/synopsis and for double strand break repair. A thorough genetic study has been initiated of this locus and of the cytology of the meiotic and mitotic defects of mutations at this locus.

Study of Substitution of Zn FOR Cu in YBa2Cu3O7 System

NASA Astrophysics Data System (ADS)

Sharma, P. K.; Samariya, A.; Dhawan, M. S.; Singhal, R. K.

The polycrystalline YBa2(Cu1-XZnX)3O7-δ samples (x=0.0 to 0.06) were synthesized and studied using X Ray diffraction, titration, resistivity, magnetization and X ray photoelectron spectroscopy (XPS). Results show that O2 stoichiometry (δ) changes on Zn substitution which affects their normal state resistivity as well as the TC. Zn also induces local magnetic moment as evidenced from magnetization results. A combination of change in O2 stoichiometry and magnetic pair breaking is found to be responsible for a rapid suppression of superconductivity.

KSC-02pd0384

NASA Image and Video Library

2002-04-02

KENNEDY SPACE CENTER, FLA. -- As he undergoes a final check on his launch and entry suit, STS-110 Mission Specialist Jerry Ross shows his delight in the upcoming launch. Ross will be making a record-breaking seventh Shuttle flight. The STS-110 payload includes the S0 Integrated Truss Structure (ITS), the Canadian Mobile Transporter, power distribution system modules, a heat pipe radiator for cooling, computers and a pair of rate gyroscopes. The 11-day mission is the 13th assembly flight to the ISS and includes four spacewalks to attach the S0 truss to the U.S. Lab Destiny. Launch is scheduled for April 4

Global biogeography since Pangaea.

PubMed

McIntyre, Sarah R N; Lineweaver, Charles H; Groves, Colin P; Chopra, Aditya

2017-06-14

The break-up of the supercontinent Pangaea around 180 Ma has left its imprint on the global distribution of species and resulted in vicariance-driven speciation. Here, we test the idea that the molecular clock dates, for the divergences of species whose geographical ranges were divided, should agree with the palaeomagnetic dates for the continental separations. Our analysis of recently available phylogenetic divergence dates of 42 pairs of vertebrate taxa, selected for their reduced ability to disperse, demonstrates that the divergence dates in phylogenetic trees of continent-bound terrestrial and freshwater vertebrates are consistent with the palaeomagnetic dates of continental separation. © 2017 The Author(s).

Reflections and meditations upon complex chromosomal exchanges.

PubMed

Savage, John R K

2002-12-01

The application of FISH chromosome painting techniques, especially the recent mFISH (and its equivalents) where all 23 human chromosome pairs can be distinguished, has demonstrated that many chromosome-type structural exchanges are much more complicated (involving more "break-rejoins" and arms) than has hitherto been assumed. It is clear that we have been greatly under-estimating the damage produced in chromatin by such agents as ionising radiation. This article gives a brief historical summary of observations leading up to this conclusion, and after outlining some of the problems surrounding the formation of complex chromosomes exchanges, speculates about possible solutions currently being proposed.

Effective theory and breakdown of conformal symmetry in a long-range quantum chain

NASA Astrophysics Data System (ADS)

Lepori, L.; Vodola, D.; Pupillo, G.; Gori, G.; Trombettoni, A.

2016-11-01

We deal with the problem of studying the symmetries and the effective theories of long-range models around their critical points. A prominent issue is to determine whether they possess (or not) conformal symmetry (CS) at criticality and how the presence of CS depends on the range of the interactions. To have a model, both simple to treat and interesting, where to investigate these questions, we focus on the Kitaev chain with long-range pairings decaying with distance as power-law with exponent α. This is a quadratic solvable model, yet displaying non-trivial quantum phase transitions. Two critical lines are found, occurring respectively at a positive and a negative chemical potential. Focusing first on the critical line at positive chemical potential, by means of a renormalization group approach we derive its effective theory close to criticality. Our main result is that the effective action is the sum of two terms: a Dirac action SD, found in the short-range Ising universality class, and an "anomalous" CS breaking term SAN. While SD originates from low-energy excitations in the spectrum, SAN originates from the higher energy modes where singularities develop, due to the long-range nature of the model. At criticality SAN flows to zero for α > 2, while for α < 2 it dominates and determines the breakdown of the CS. Out of criticality SAN breaks, in the considered approximation, the effective Lorentz invariance (ELI) for every finite α. As α increases such ELI breakdown becomes less and less pronounced and in the short-range limit α → ∞ the ELI is restored. In order to test the validity of the determined effective theory, we compared the two-fermion static correlation functions and the von Neumann entropy obtained from them with the ones calculated on the lattice, finding agreement. These results explain two observed features characteristic of long-range models, the hybrid decay of static correlation functions within gapped phases and the area-law violation for the von Neumann entropy. The proposed scenario is expected to hold in other long-range models displaying quasiparticle excitations in ballistic regime. From the effective theory one can also see that new phases emerge for α < 1. Finally we show that at every finite α the critical exponents, defined as for the short-range (α → ∞) model, are not altered. This also shows that the long-range paired Kitaev chain provides an example of a long-range model in which the value of α where the CS is broken does not coincide with the value at which the critical exponents start to differ from the ones of the corresponding short-range model. At variance, for the second critical line, having negative chemical potential, only SAN (SD) is present for 1 < α < 2 (for α > 2). Close to this line, where the minimum of the spectrum coincides with the momentum where singularities develop, the critical exponents change where CS is broken.

Effect of exact Coulomb-exchange calculations on band-head spectra of odd-proton nuclei

NASA Astrophysics Data System (ADS)

Koh, Meng-Hock; Nurhafiza, Mohamad Nor

2017-10-01

Previous calculations of band-head energy spectra of odd-mass heavy nuclei in the Hartree-Fock-plus-Bardeen-Cooper-Schrieffer (HF-BCS) framework showed that the agreement with data is better for odd-neutron as compared to odd-proton nuclei. The reason for a poorer agreement with data for the latter have been ascribed to the possible usage of the Slater approximation in calculating the Coulomb-exchange term. In this work, we report the effect of exact Coulomb-exchange calculations on band-head energy spectra of two odd-proton nuclei (namely 237Np and 241Am) as compared to the results obtained using the Slater approximation. We performed self-consistent blocking calculations while taking the breaking of time-reversal symmetry at the mean-field level into account due to the unpaired nucleon. The SkM* and SIII parametrizations of the Skyrme interaction have been employed to approximate the effective nucleon-nucleon interaction while a seniority force is used for the pairing channel. Contrary to what was expected, our preliminary results show no improvement on the band-head spectra as compared to data when the Coulomb-exchange term is calculated exactly.

Assessment Of Chemical Dispersant Effectiveness In A Wave Tank Under Regular Non-Breaking And Breaking Wave Conditions

EPA Science Inventory

Current chemical dispersant effectiveness tests for product selection are commonly performed with bench-scale testing apparatus. However, for the assessment of oil dispersant effectiveness under real sea state conditions, test protocols are required to have hydrodynamic conditio...

Breaking the Yardstick: The Dangers of Market-based Governance (Defense Horizons, Number 67, May 2009)

DTIC Science & Technology

2009-05-01

the implementation of free market forces, more efficient and effective use of resources can be obtained,” which the Defense Science Board asserted...actually slower, less effective, and costlier. This is, in part, because the Breaking the Yardstick: The Dangers of Market -based Governance by Don...2. REPORT TYPE 3. DATES COVERED 00-00-2009 to 00-00-2009 4. TITLE AND SUBTITLE Breaking the Yardstick: The Dangers of Market -based Governance

Disorder effects in the evolution from BCS to BEC superfluidity

NASA Astrophysics Data System (ADS)

Han, Li; de Melo, Carlos A. R. Sa

2009-03-01

We discuss the effects of disorder on the critical temperature of superfluids during the evolution from BCS to BEC. For s-wave superfluids we find that the critical temperature is weakly affected by disorder in the BCS regime as described in Anderson’s theorem, even less affected by disorder at zero chemical potential (near unitarity), but strongly affected by disorder in the BEC regime, where Anderson's theorem does not apply. This suggests that the superfluid is more robust to the effects of disorder at the interaction parameter where the chemical potential vanishes (close to unitarity). We construct a three dimensional phase diagram of critical temperature, disorder and interaction parameter [1], and show that there are regions of localized superfluidity, as well as insulating regions due to Anderson localization of fermions (BCS regime) and molecular bosons (BEC regime). The phase diagram for higher angular momentum (e.g. p-wave and d-wave) is also analyzed, where the effects of disorder are much more dramatic in the BCS regime in comparison to the s-wave case because pair breaking is strong, while the disorder effects in BEC regime are similar to what occurs in the s-wave case. [1] Li Han, C. A. R. Sa de Melo, arXiv:0812.xxxx

The autumn effect: timing of physical dormancy break in seeds of two winter annual species of Geraniaceae by a stepwise process

PubMed Central

Gama-Arachchige, N. S.; Baskin, J. M.; Geneve, R. L.; Baskin, C. C.

2012-01-01

Background and Aims The involvement of two steps in the physical dormancy (PY)-breaking process previously has been demonstrated in seeds of Fabaceae and Convolvulaceae. Even though there is a claim for a moisture-controlled stepwise PY-breaking in some species of Geraniaceae, no study has evaluated the role of temperature in the PY-breaking process in this family. The aim of this study was to determine whether a temperature-controlled stepwise PY-breaking process occurs in seeds of the winter annuals Geranium carolinianum and G. dissectum. Methods Seeds of G. carolinianum and G. dissectum were stored under different temperature regimes to test the effect of storage temperature on PY-break. The role of temperature and moisture regimes in regulating PY-break was investigated by treatments simulating natural conditions. Greenhouse (non-heated) experiments on seed germination and burial experiments (outdoors) were carried out to determine the PY-breaking behaviour in the natural habitat. Key Results Irrespective of moisture conditions, sensitivity to the PY-breaking step in seeds of G. carolinianum was induced at temperatures ≥20 °C, and exposure to temperatures ≤20 °C made the sensitive seeds permeable. Sensitivity of seeds increased with time. In G. dissectum, PY-break occurred at temperatures ≥20 °C in a single step under constant wet or dry conditions and in two steps under alternate wet–dry conditions if seeds were initially kept wet. Conclusions Timing of seed germination with the onset of autumn can be explained by PY-breaking processes involving (a) two temperature-dependent steps in G. carolinianum and (b) one or two moisture-dependent step(s) along with the inability to germinate under high temperatures in G. dissectum. Geraniaceae is the third of 18 families with PY in which a two-step PY-breaking process has been demonstrated. PMID:22684684

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sukhovoj, A. M., E-mail: suchovoj@nf.jinr.ru; Mitsyna, L. V., E-mail: mitsyna@nf.jinr.ru; Jovancevic, N., E-mail: nikola.jovancevic@uns.ac.rs

The intensities of two-step cascades in 43 nuclei of mass number in the range of 28 ≤ A ≤ 200 were approximated to a high degree of precision within a modified version of the practical cascade-gammadecay model introduced earlier. In this version, the rate of the decrease in the model-dependent density of vibrational levels has the same value for any Cooper pair undergoing breakdown. The most probable values of radiative strength functions both for E1 and for M1 transitions are determined by using one or two peaks against a smooth model dependence on the gamma-transition energy. The statement that themore » thresholds for the breaking of Cooper pairs are higher for spherical than for deformed nuclei is a basic result of the respective analysis. The parameters of the cascade-decay process are now determined to a precision that makes it possible to observe the systematic distinctions between them for nuclei characterized by different parities of neutrons and protons.« less

Topological features of vector vortex beams perturbed with uniformly polarized light

PubMed Central

D’Errico, Alessio; Maffei, Maria; Piccirillo, Bruno; de Lisio, Corrado; Cardano, Filippo; Marrucci, Lorenzo

2017-01-01

Optical singularities manifesting at the center of vector vortex beams are unstable, since their topological charge is higher than the lowest value permitted by Maxwell’s equations. Inspired by conceptually similar phenomena occurring in the polarization pattern characterizing the skylight, we show how perturbations that break the symmetry of radially symmetric vector beams lead to the formation of a pair of fundamental and stable singularities, i.e. points of circular polarization. We prepare a superposition of a radial (or azimuthal) vector beam and a uniformly linearly polarized Gaussian beam; by varying the amplitudes of the two fields, we control the formation of pairs of these singular points and their spatial separation. We complete this study by applying the same analysis to vector vortex beams with higher topological charges, and by investigating the features that arise when increasing the intensity of the Gaussian term. Our results can find application in the context of singularimetry, where weak fields are measured by considering them as perturbations of unstable optical beams. PMID:28079134

Modulation of Prdm9-controlled meiotic chromosome asynapsis overrides hybrid sterility in mice.

PubMed

Gregorova, Sona; Gergelits, Vaclav; Chvatalova, Irena; Bhattacharyya, Tanmoy; Valiskova, Barbora; Fotopulosova, Vladana; Jansa, Petr; Wiatrowska, Diana; Forejt, Jiri

2018-03-14

Hybrid sterility is one of the reproductive isolation mechanisms leading to speciation. Prdm9 , the only known vertebrate hybrid-sterility gene, causes failure of meiotic chromosome synapsis and infertility in male hybrids that are the offspring of two mouse subspecies. Within species, Prdm9 determines the sites of programmed DNA double-strand breaks (DSBs) and meiotic recombination hotspots. To investigate the relation between Prdm9 -controlled meiotic arrest and asynapsis, we inserted random stretches of consubspecific homology on several autosomal pairs in sterile hybrids, and analyzed their ability to form synaptonemal complexes and to rescue male fertility. Twenty-seven or more megabases of consubspecific (belonging to the same subspecies) homology fully restored synapsis in a given autosomal pair, and we predicted that two or more DSBs within symmetric hotspots per chromosome are necessary for successful meiosis. We hypothesize that impaired recombination between evolutionarily diverged chromosomes could function as one of the mechanisms of hybrid sterility occurring in various sexually reproducing species. © 2018, Gregorova et al.

Modulation of Prdm9-controlled meiotic chromosome asynapsis overrides hybrid sterility in mice

PubMed Central

Chvatalova, Irena; Bhattacharyya, Tanmoy; Valiskova, Barbora; Fotopulosova, Vladana; Jansa, Petr; Wiatrowska, Diana

2018-01-01

Hybrid sterility is one of the reproductive isolation mechanisms leading to speciation. Prdm9, the only known vertebrate hybrid-sterility gene, causes failure of meiotic chromosome synapsis and infertility in male hybrids that are the offspring of two mouse subspecies. Within species, Prdm9 determines the sites of programmed DNA double-strand breaks (DSBs) and meiotic recombination hotspots. To investigate the relation between Prdm9-controlled meiotic arrest and asynapsis, we inserted random stretches of consubspecific homology on several autosomal pairs in sterile hybrids, and analyzed their ability to form synaptonemal complexes and to rescue male fertility. Twenty-seven or more megabases of consubspecific (belonging to the same subspecies) homology fully restored synapsis in a given autosomal pair, and we predicted that two or more DSBs within symmetric hotspots per chromosome are necessary for successful meiosis. We hypothesize that impaired recombination between evolutionarily diverged chromosomes could function as one of the mechanisms of hybrid sterility occurring in various sexually reproducing species. PMID:29537370

Topological features of vector vortex beams perturbed with uniformly polarized light

NASA Astrophysics Data System (ADS)

D'Errico, Alessio; Maffei, Maria; Piccirillo, Bruno; de Lisio, Corrado; Cardano, Filippo; Marrucci, Lorenzo

2017-01-01

Optical singularities manifesting at the center of vector vortex beams are unstable, since their topological charge is higher than the lowest value permitted by Maxwell’s equations. Inspired by conceptually similar phenomena occurring in the polarization pattern characterizing the skylight, we show how perturbations that break the symmetry of radially symmetric vector beams lead to the formation of a pair of fundamental and stable singularities, i.e. points of circular polarization. We prepare a superposition of a radial (or azimuthal) vector beam and a uniformly linearly polarized Gaussian beam; by varying the amplitudes of the two fields, we control the formation of pairs of these singular points and their spatial separation. We complete this study by applying the same analysis to vector vortex beams with higher topological charges, and by investigating the features that arise when increasing the intensity of the Gaussian term. Our results can find application in the context of singularimetry, where weak fields are measured by considering them as perturbations of unstable optical beams.

Topological features of vector vortex beams perturbed with uniformly polarized light.

PubMed

D'Errico, Alessio; Maffei, Maria; Piccirillo, Bruno; de Lisio, Corrado; Cardano, Filippo; Marrucci, Lorenzo

2017-01-12

Optical singularities manifesting at the center of vector vortex beams are unstable, since their topological charge is higher than the lowest value permitted by Maxwell's equations. Inspired by conceptually similar phenomena occurring in the polarization pattern characterizing the skylight, we show how perturbations that break the symmetry of radially symmetric vector beams lead to the formation of a pair of fundamental and stable singularities, i.e. points of circular polarization. We prepare a superposition of a radial (or azimuthal) vector beam and a uniformly linearly polarized Gaussian beam; by varying the amplitudes of the two fields, we control the formation of pairs of these singular points and their spatial separation. We complete this study by applying the same analysis to vector vortex beams with higher topological charges, and by investigating the features that arise when increasing the intensity of the Gaussian term. Our results can find application in the context of singularimetry, where weak fields are measured by considering them as perturbations of unstable optical beams.

The marriage problem and the fate of bachelors

NASA Astrophysics Data System (ADS)

Nieuwenhuizen, Th. M.

In the marriage problem, a variant of the bi-parted matching problem, each member has a “wish-list” expressing his/her preference for all possible partners; this list consists of random, positive real numbers drawn from a certain distribution. One searches the lowest cost for the society, at the risk of breaking up pairs in the course of time. Minimization of a global cost function (Hamiltonian) is performed with statistical mechanics techniques at a finite fictitious temperature. The problem is generalized to include bachelors, needed in particular when the groups have different size, and polygamy. Exact solutions are found for the optimal solution ( T=0). The entropy is found to vanish quadratically in T. Also, other evidence is found that the replica symmetric solution is exact, implying at most a polynomial degeneracy of the optimal solution. Whether bachelors occur or not, depends not only on their intrinsic qualities, or lack thereof, but also on global aspects of the chance for pair formation in society.

Helicase Stepping Investigated with One-Nucleotide Resolution Fluorescence Resonance Energy Transfer

NASA Astrophysics Data System (ADS)

Lin, Wenxia; Ma, Jianbing; Nong, Daguan; Xu, Chunhua; Zhang, Bo; Li, Jinghua; Jia, Qi; Dou, Shuoxing; Ye, Fangfu; Xi, Xuguang; Lu, Ying; Li, Ming

2017-09-01

Single-molecule Förster resonance energy transfer is widely applied to study helicases by detecting distance changes between a pair of dyes anchored to overhangs of a forked DNA. However, it has been lacking single-base pair (1-bp) resolution required for revealing stepping kinetics of helicases. We designed a nanotensioner in which a short DNA is bent to exert force on the overhangs, just as in optical or magnetic tweezers. The strategy improved the resolution of Förster resonance energy transfer to 0.5 bp, high enough to uncover differences in DNA unwinding by yeast Pif1 and E. coli RecQ whose unwinding behaviors cannot be differentiated by currently practiced methods. We found that Pif1 exhibits 1-bp-stepping kinetics, while RecQ breaks 1 bp at a time but sequesters the nascent nucleotides and releases them randomly. The high-resolution data allowed us to propose a three-parameter model to quantitatively interpret the apparently different unwinding behaviors of the two helicases which belong to two superfamilies.

Theory of superconductivity in a three-orbital model of Sr2RuO4

NASA Astrophysics Data System (ADS)

Wang, Q. H.; Platt, C.; Yang, Y.; Honerkamp, C.; Zhang, F. C.; Hanke, W.; Rice, T. M.; Thomale, R.

2013-10-01

In conventional and high transition temperature copper oxide and iron pnictide superconductors, the Cooper pairs all have even parity. As a rare exception, Sr2RuO4 is the first prime candidate for topological chiral p-wave superconductivity, which has time-reversal breaking odd-parity Cooper pairs known to exist before only in the neutral superfluid 3He. However, there are several key unresolved issues hampering the microscopic description of the unconventional superconductivity. Spin fluctuations at both large and small wave vectors are present in experiments, but how they arise and drive superconductivity is not yet clear. Spontaneous edge current is expected but not observed conclusively. Specific experiments point to highly band- and/or momentum-dependent energy gaps for quasiparticle excitations in the superconducting state. Here, by comprehensive functional renormalization group calculations with all relevant bands, we disentangle the various competing possibilities. In particular, we show the small wave vector spin fluctuations, driven by a single two-dimensional band, trigger p-wave superconductivity with quasi-nodal energy gaps.

Single magnetic adsorbates on s-wave superconductors

NASA Astrophysics Data System (ADS)

Heinrich, Benjamin W.; Pascual, Jose I.; Franke, Katharina J.

2018-02-01

In superconductors, magnetic impurities induce a pair-breaking potential for Cooper pairs, which locally affects the Bogoliubov quasiparticles and gives rise to Yu-Shiba-Rusinov (YSR or Shiba, in short) bound states in the density of states (DoS). These states carry information on the magnetic coupling strength of the impurity with the superconductor, which determines the many-body ground state properties of the system. Recently, the interest in Shiba physics was boosted by the prediction of topological superconductivity and Majorana modes in magnetically coupled chains and arrays of Shiba impurities. Here, we review the physical insights obtained by scanning tunneling microscopy into single magnetic adsorbates on the s-wave superconductor lead (Pb). We explore the tunneling processes into Shiba states, show how magnetic anisotropy affects many-body excitations, and determine the crossing of the many-body ground state through a quantum phase transition. Finally, we discuss the coupling of impurities into dimers and chains and their relation to Majorana physics.

Evolution of volume fractions and droplet sizes by analysis of electrical conductance curves during destabilization of oil-in-water emulsions.

PubMed

Kostoglou, M; Varka, E-M; Kalogianni, E P; Karapantsios, T D

2010-09-01

Destabilization of hexane-in-water emulsions is studied by a continuous, non-intrusive, multi-probe, electrical conductance technique. Emulsions made of different oil fractions and surfactant (C(10)E(5)) concentrations are prepared in a stirred vessel using a Rushton turbine to break and agitate droplets. During the separation of phases, electrical signals from pairs of ring electrodes mounted at different heights onto the vessel wall, are recorded. The evolution of the local water volume fractions at the locations of the electrodes is estimated from these signals. It is found that in the absence of coalescence, the water fraction evolution curve from the bottom pair of electrodes is compatible with a bidisperse oil droplet size distribution. The sizes and volume fractions of the two droplet modes are estimated using theoretical arguments. The electrically determined droplet sizes are compared to data from microscopy image analysis. Results are discussed in detail. Copyright 2010 Elsevier Inc. All rights reserved.

Probability function of breaking-limited surface elevation. [wind generated waves of ocean

NASA Technical Reports Server (NTRS)

Tung, C. C.; Huang, N. E.; Yuan, Y.; Long, S. R.

1989-01-01

The effect of wave breaking on the probability function of surface elevation is examined. The surface elevation limited by wave breaking zeta sub b(t) is first related to the original wave elevation zeta(t) and its second derivative. An approximate, second-order, nonlinear, non-Gaussian model for zeta(t) of arbitrary but moderate bandwidth is presented, and an expression for the probability density function zeta sub b(t) is derived. The results show clearly that the effect of wave breaking on the probability density function of surface elevation is to introduce a secondary hump on the positive side of the probability density function, a phenomenon also observed in wind wave tank experiments.

Effect of vacuum arc cathode spot distribution on breaking capacity of the arc-extinguishing chamber

NASA Astrophysics Data System (ADS)

Ding, Can; Yuan, Zhao; He, Junjia

2017-10-01

A DC circuit breaker performs a key function in breaking an intermediate-frequency (IF) current since breaking a pure IF current is equivalent to breaking a very small DC with a reverse IF current. In this study, it is found that cathode spots show a ring-shaped distribution at 2000 Hz. An arc with an uneven distribution of cathode spots has been simulated. The simulation results show that the distribution of cathode spots significantly affect the microparameter distribution of arc plasma. The current distribution on the anode side differs from that on the cathode side under the total radial electric field. Specifically, the anode current distribution is both uneven and concentrated. The applied axial magnetic field, which cannot reduce the concentrated anode current distribution effectively, might increase the concentration of the anode current. Finally, the uneven distribution of cathode spots reduces the breaking capacity of the arc-extinguishing chamber.

Numerical modelling of wind effects on breaking waves in the surf zone

NASA Astrophysics Data System (ADS)

Xie, Zhihua

2017-10-01

Wind effects on periodic breaking waves in the surf zone have been investigated in this study using a two-phase flow model. The model solves the Reynolds-averaged Navier-Stokes equations with the k - 𝜖 turbulence model simultaneously for the flows both in the air and water. Both spilling and plunging breakers over a 1:35 sloping beach have been studied under the influence of wind, with a focus during wave breaking. Detailed information of the distribution of wave amplitudes and mean water level, wave-height-to-water-depth ratio, the water surface profiles, velocity, vorticity, and turbulence fields have been presented and discussed. The inclusion of wind alters the air flow structure above water waves, increases the generation of vorticity, and affects the wave shoaling, breaking, overturning, and splash-up processes. Wind increases the water particle velocities and causes water waves to break earlier and seaward, which agrees with the previous experiment.

[Breaking bad news in oncology: the Belgian experience].

PubMed

Delevallez, F; Lienard, A; Gibon, A-S; Razavi, D

2014-10-01

Breaking bad news is a complex and frequent clinical task for physicians working in oncology. It can have a negative impact on patients and their relatives who are often present during breaking bad news consultations. Many factors influence how the delivery of bad news will be experienced especially the communication skills used by physicians. A three-phase process (post-delivery phase, delivery phase, pre-delivery phase) has been developed to help physician to handle this task more effectively. Communication skills and specific breaking bad news training programs are both necessary and effective. A recent study conducted in Belgium has shown their impact on the time allocated to each of the three phases of this process, on the communication skills used, on the inclusion of the relative in the consultation and on physicians' physiological arousal. These results underscore the importance of promoting intensive communication skills and breaking bad news training programs for health care professionals.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Radzihovsky, Leo

Motivated by a realization of imbalanced Feshbach-resonant atomic Fermi gases, we formulate a low-energy theory of the Fulde-Ferrell and the Larkin-Ovchinnikov (LO) states and use it to analyze fluctuations, stability, and phase transitions in these enigmatic finite momentum-paired superfluids. Focusing on the unidirectional LO pair-density-wave state, which spontaneously breaks the continuous rotational and translational symmetries, we show that it is characterized by two Goldstone modes, corresponding to a superfluid phase and a smectic phonon. Because of the liquid-crystalline ''softness'' of the latter, at finite temperature the three-dimensional state is characterized by a vanishing LO order parameter, quasi-Bragg peaks in themore » structure and momentum distribution functions, and a ''charge''-4, paired-Cooper-pairs, off-diagonal long-range order, with a superfluid-stiffness anisotropy that diverges near a transition into a nonsuperfluid state. In addition to conventional integer vortices and dislocations, the LO superfluid smectic exhibits composite half-integer vortex-dislocation defects. A proliferation of defects leads to a rich variety of descendant states, such as the charge-4 superfluid and Fermi-liquid nematics and topologically ordered nonsuperfluid states, that generically intervene between the LO state and the conventional superfluid and the polarized Fermi liquid at low and high imbalance, respectively. The fermionic sector of the LO gapless superconductor is also quite unique, exhibiting a Fermi surface of Bogoliubov quasiparticles associated with the Andreev band of states, localized on the array of the LO domain walls.« less

Evaluation of coal-related model compounds using a tandem mass spectrometry.

PubMed

Li, Guo-Sheng; Dong, Xueming; Fan, Xing; You, Chun-Yan; Wu, Ge; Zhao, Yun-Peng; Lu, Yao; Wei, Xian-Yong; Ma, Feng-Yun

2018-05-08

Gas chromotography/mass spectrometry (GC/MS) is a routine and basic instrumental method for the analysis of complex coal conversion products in chemical industry. To further enhance practical potentials of GC/MS in chemical industry, a tandem MS method for the selection of ion pair applied in monitoring coal conversions was established by using GC/quadrupole time-of-flight MS (GC/Q-TOF MS). The corresponding fragmentation pathways were explored and suitable ion pairs were screened. Fourteen coal-related model compounds (CRMCs) were analyzed using a GC/Q-TOF MS with different collision induced dissociation (CID) energies (5-20 eV). The fragmentation pathways can offer a better understanding of chemical bond breaking, hydrogen transfer, rearrangement reactions and elimination of neutral fragments for CRMCs during the CID process. The precursor ions of aromatic hydrocarbons without alkyl chain were hard to fragment with a CID energy of 20 eV. But aromatic hydrocarbons with branched chains were prone to fragment via the loss of alkyl chains and further fragmented through ring-open reactions. Compared to C alk -C ar bond, C ar -C ar bond was hard to fragment duo to its high bond dissociation energy. The existence of heteroatoms facilitated fragmentation that was conducive to screening ion pair. The CID technique of GC/Q-TOF MS will contribute to the studies on the organic composition of coals and building monitoring methods for coal conversions via fragmentation and ion pair selection. This article is protected by copyright. All rights reserved.

Change of Electroweak Nuclear Reaction Rates by CP- and Isospin Symmetry Breaking - A Model Calculation

NASA Astrophysics Data System (ADS)

Stumpf, Harald

2006-09-01

Based on the assumption that electroweak bosons, leptons and quarks possess a substructure of elementary fermionic constituents, in previous papers the effect of CP-symmetry breaking on the effective dynamics of these particles was calculated. Motivated by the phenomenological procedure in this paper, isospin symmetry breaking will be added and the physical consequences of these calculations will be discussed. The dynamical law of the fermionic constituents is given by a relativistically invariant nonlinear spinor field equation with local interaction, canonical quantization, selfregularization and probability interpretation. The corresponding effective dynamics is derived by algebraic weak mapping theorems. In contrast to the commonly applied modifications of the quark mass matrices, CP-symmetry breaking is introduced into this algebraic formalism by an inequivalent vacuum with respect to the CP-invariant case, represented by a modified spinor field propagator. This leads to an extension of the standard model as effective theory which contains besides the "electric" electroweak bosons additional "magnetic" electroweak bosons and corresponding interactions. If furthermore the isospin invariance of the propagator is broken too, it will be demonstrated in detail that in combination with CP-symmetry breaking this induces a considerable modification of electroweak nuclear reaction rates.

In vivo blunt-end cloning through CRISPR/Cas9-facilitated non-homologous end-joining

PubMed Central

Geisinger, Jonathan M.; Turan, Sören; Hernandez, Sophia; Spector, Laura P.; Calos, Michele P.

2016-01-01

The CRISPR/Cas9 system facilitates precise DNA modifications by generating RNA-guided blunt-ended double-strand breaks. We demonstrate that guide RNA pairs generate deletions that are repaired with a high level of precision by non-homologous end-joining in mammalian cells. We present a method called knock-in blunt ligation for exploiting these breaks to insert exogenous PCR-generated sequences in a homology-independent manner without loss of additional nucleotides. This method is useful for making precise additions to the genome such as insertions of marker gene cassettes or functional elements, without the need for homology arms. We successfully utilized this method in human and mouse cells to insert fluorescent protein cassettes into various loci, with efficiencies up to 36% in HEK293 cells without selection. We also created versions of Cas9 fused to the FKBP12-L106P destabilization domain in an effort to improve Cas9 performance. Our in vivo blunt-end cloning method and destabilization-domain-fused Cas9 variant increase the repertoire of precision genome engineering approaches. PMID:26762978

Buoyancy fluxes in stratified flows: observations and parameterizations

NASA Astrophysics Data System (ADS)

Monismith, Stephen; Koseff, Jeffrey; Walter, Ryan; Squibb, Michael; Woodson, Brock; Davis, Kristen; Pawlak, Geno; Dunckley, Jamie

2017-11-01

We present a synthesis of observations of turbulent buoyancy fluxes, B, made at five sites where flows and turbulence are primarily associated with internal waves, both breaking and non-breaking. In four cases, B was calculated from the covariance of velocity and density whereas in the fifth case, it was inferred from the rate of temperature variance dissipation, χ . Overall, we find that the flux Richardson number, Rif , depends on the Gibson number, Gi = ɛ / νN2 : when Gi < 100, Rif 0.27 , and when Gi > 100 Rif 2.7 Gi-0.5 , in agreement with the functional relationship found originally using direct numerical simulation (DNS). Our observations do not match well other DNS-derived models that parameterize Rif in terms of the gradient Richardson number, Ri, or the turbulence Froude numbers, FrK and Frt . Similarly, Rif (Gi) is found to be the same for all the covariance data sets, despite the fact that these 4 flows produce turbulence that falls in different regimes defined by several pairs chosen from the 5 non-dimensional numbers that the Buckingham Π theorem shows may affect Rif .

The point of E 8 in F-theory GUTs

NASA Astrophysics Data System (ADS)

Heckman, Jonathan J.; Tavanfar, Alireza; Vafa, Cumrun

2010-08-01

We show that in F-theory GUTs, a natural explanation of flavor hierarchies in the quark and lepton sector requires a single point of E 8 enhancement in the internal geometry, from which all Yukawa couplings originate. The monodromy group acting on the seven-brane configuration plays a key role in this analysis. Moreover, the E 8 structure automatically leads to the existence of the additional fields and interactions needed for minimal gauge mediated supersymmetry breaking, and almost nothing else. Surprisingly, we find that in all but one Dirac neutrino scenario the messenger fields in the gauge mediated supersymmetry breaking sector transform as vector-like pairs in the 10 oplus overline {10} of SU(5). We also classify dark matter candidates available from this enhancement point, and rule out both annihilating and decaying dark matter scenarios as explanations for the recent experiments PAMELA, ATIC and FERMI. In F-theory GUT models, a 10-100 MeV mass gravitino remains as the prime candidate for dark matter, thus suggesting an astrophysical origin for recent experimental signals.

Electron Acceleration and Efficiency in Nonthermal Gamma-Ray Sources

NASA Astrophysics Data System (ADS)

Bykov, A. M.; Meszaros, P.

1996-04-01

In energetic nonthermal sources such as gamma-ray bursts, active galactic nuclei, or galactic jets, etc., one expects both relativistic and transrelativistic shocks accompanied by violent motions of moderately relativistic plasma. We present general considerations indicating that these sites are electron and positron accelerators leading to a modified power-law spectrum. The electron (or e+/-) energy index is very hard, ~ gamma -1 or flatter, up to a comoving frame break energy gamma *, and becomes steeper above that. In the example of gamma-ray bursts, the Lorentz factor reaches gamma * ~ 103 for e+/- accelerated by the internal shock ensemble on subhydrodynamical timescales. For pairs accelerated on hydrodynamical timescales in the external shocks, similar hard spectra are obtained, and the break Lorentz factor can be as high as gamma * <~ 105. Radiation from the nonthermal electrons produces photon spectra with shapes and characteristic energies in qualitative agreement with observed generic gamma-ray burst and blazar spectra. The scenario described here provides a plausible way to solve one of the crucial problems of nonthermal high-energy sources, namely, the efficient transfer of energy from the proton flow to an appropriate nonthermal lepton component.

Promotion of Homologous Recombination and Genomic Stability byRAD51AP1 via RAD51 Recombinase Enhancement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wiese, Claudia; Dray, Eloise; Groesser, Torsten

2007-04-11

Homologous recombination (HR) repairs chromosome damage and is indispensable for tumor suppression in humans. RAD51 mediates the DNA strand pairing step in HR. RAD51AP1 (RAD51 Associated Protein 1) is a RAD51-interacting protein whose function has remained elusive. Knockdown of RAD51AP1 in human cells by RNA interference engenders sensitivity to different types of genotoxic stress. Moreover, RAD51AP1-depleted cells are impaired for the recombinational repair of a DNA double-strand break and exhibit chromatid breaks both spontaneously and upon DNA damaging treatment. Purified RAD51AP1 binds dsDNA and RAD51, and it greatly stimulates the RAD51-mediated D-loop reaction. Biochemical and cytological results show that RAD51AP1more » functions at a step subsequent to the assembly of the RAD51-ssDNA nucleoprotein filament. Our findings provide the first evidence that RAD51AP1 helps maintain genomic integrity via RAD51 recombinase enhancement.« less

Method for controlling protein crystallization

NASA Technical Reports Server (NTRS)

Noever, David A. (Inventor)

1993-01-01

A method and apparatus for controlling the crystallization of protein by solvent evaporation including placing a drop of protein solution between and in contact with a pair of parallel plates and driving one of the plates toward and away from the other plate in a controlled manner to adjust the spacing between the plates is presented. The drop of solution forms a liquid cylinder having a height dependent upon the plate spacing thereby effecting the surface area available for solvent evaporation. When the spacing is close, evaporation is slow. Evaporation is increased by increasing the spacing between the plates until the breaking point of the liquid cylinder. One plate is mounted upon a fixed post while the other plate is carried by a receptacle movable relative to the post and driven by a belt driven screw drive. The temperature and humidity of the drop of protein solution are controlled by sealing the drop within the receptacle and mounting a heater and dessicant within the receptacle.

Evolution of finite-amplitude localized vortices in planar homogeneous shear flows

NASA Astrophysics Data System (ADS)

Karp, Michael; Shukhman, Ilia G.; Cohen, Jacob

2017-02-01

An analytical-based method is utilized to follow the evolution of localized initially Gaussian disturbances in flows with homogeneous shear, in which the base velocity components are at most linear functions of the coordinates, including hyperbolic, elliptic, and simple shear. Coherent structures, including counterrotating vortex pairs (CVPs) and hairpin vortices, are formed for the cases where the streamlines of the base flow are open (hyperbolic and simple shear). For hyperbolic base flows, the dominance of shear over rotation leads to elongation of the localized disturbance along the outlet asymptote and formation of CVPs. For simple shear CVPs are formed from linear and nonlinear disturbances, whereas hairpins are observed only for highly nonlinear disturbances. For elliptic base flows CVPs, hairpins and vortex loops form initially, however they do not last and break into various vortical structures that spread in the spanwise direction. The effect of the disturbance's initial amplitude and orientation is examined and the optimal orientation achieving maximal growth is identified.

Novel insights into the mechanism of the ortho/para spin conversion of hydrogen pairs: implications for catalysis and interstellar water.

PubMed

Limbach, Hans-Heinrich; Buntkowsky, Gerd; Matthes, Jochen; Gründemann, Stefan; Pery, Tal; Walaszek, Bernadeta; Chaudret, Bruno

2006-03-13

The phenomenon of exchange coupling is taken into account in the description of the magnetic nuclear spin conversion between bound ortho- and para-dihydrogen. This conversion occurs without bond breaking, in contrast to the chemical spin conversion. It is shown that the exchange coupling needs to be reduced so that the corresponding exchange barrier can increase and the given magnetic interaction can effectively induce a spin conversion. The implications for related molecules such as water are discussed. For ice, a dipolar magnetic conversion and for liquid water a chemical conversion are predicted to occur within the millisecond timescale. It follows that a separation of water into its spin isomers, as proposed by Tikhonov and Volkov (Science 2002, 296, 2363), is not feasible. Nuclear spin temperatures of water vapor in comets, which are smaller than the gas-phase equilibrium temperatures, are proposed to be diagnostic for the temperature of the ice or the dust surface from which the water was released.

Exploring the performance of thin-film superconducting multilayers as kinetic inductance detectors for low-frequency detection

NASA Astrophysics Data System (ADS)

Zhao, Songyuan; Goldie, D. J.; Withington, S.; Thomas, C. N.

2018-01-01

We have solved numerically the diffusive Usadel equations that describe the spatially varying superconducting proximity effect in Ti-Al thin-film bi- and trilayers with thickness values that are suitable for kinetic inductance detectors (KIDs) to operate as photon detectors with detection thresholds in the frequency range of 50-90 GHz. Using Nam’s extension of the Mattis-Bardeen calculation of the superconductor complex conductivity, we show how to calculate the surface impedance for the spatially varying case, and hence the surface impedance quality factor. In addition, we calculate energy-and spatially-averaged quasiparticle lifetimes at temperatures well-below the transition temperature and compare to calculation in Al. Our results for the pair-breaking threshold demonstrate differences between bilayers and trilayers with the same total film thicknesses. We also predict high quality factors and long multilayer-averaged quasiparticle recombination times compared to thin-film Al. Our calculations give a route for designing KIDs to operate in this scientifically-important frequency regime.

The problem of natural funnel asymmetries: a simulation analysis of meta-analysis in macroeconomics.

PubMed

Callot, Laurent; Paldam, Martin

2011-06-01

Effect sizes in macroeconomic are estimated by regressions on data published by statistical agencies. Funnel plots are a representation of the distribution of the resulting regression coefficients. They are normally much wider than predicted by the t-ratio of the coefficients and often asymmetric. The standard method of meta-analysts in economics assumes that the asymmetries are because of publication bias causing censoring and adjusts the average accordingly. The paper shows that some funnel asymmetries may be 'natural' so that they occur without censoring. We investigate such asymmetries by simulating funnels by pairs of data generating processes (DGPs) and estimating models (EMs), in which the EM has the problem that it disregards a property of the DGP. The problems are data dependency, structural breaks, non-normal residuals, non-linearity, and omitted variables. We show that some of these problems generate funnel asymmetries. When they do, the standard method often fails. Copyright © 2011 John Wiley & Sons, Ltd. Copyright © 2011 John Wiley & Sons, Ltd.

Scalar field dark matter with spontaneous symmetry breaking and the 3.5 keV line

NASA Astrophysics Data System (ADS)

Cosme, Catarina; Rosa, João G.; Bertolami, O.

2018-06-01

We show that the present dark matter abundance can be accounted for by an oscillating scalar field that acquires both mass and a non-zero expectation value from interactions with the Higgs field. The dark matter scalar field can be sufficiently heavy during inflation, due to a non-minimal coupling to gravity, so as to avoid the generation of large isocurvature modes in the CMB anisotropies spectrum. The field begins oscillating after reheating, behaving as radiation until the electroweak phase transition and afterwards as non-relativistic matter. The scalar field becomes unstable, although sufficiently long-lived to account for dark matter, due to mass mixing with the Higgs boson, decaying mainly into photon pairs for masses below the MeV scale. In particular, for a mass of ∼7 keV, which is effectively the only free parameter, the model predicts a dark matter lifetime compatible with the recent galactic and extragalactic observations of a 3.5 keV X-ray line.

Pair-breaking mechanisms in superconductor—normal-metal—superconductor junctions

NASA Astrophysics Data System (ADS)

Yang, H. C.; Finnemore, D. K.

1984-08-01

The critical current density Jc has been measured for superconductor—normal-metal—superconductor (S-N-S) junctions over a wide range of temperature and composition in order to determine the depairing effects of magnetic impurities. Junctions, which are in a sandwich geometry with the N layer typically 600 nm thick, show well-defined diffraction patterns indicating that the junctions are of high quality. Below 4.2 K, the temperature dependence of Jc is found to follow a modified bridge theory based on the work of Makeev et al.

Routes to heavy-fermion superconductivity

NASA Astrophysics Data System (ADS)

Steglich, F.; Stockert, O.; Wirth, S.; Geibel, C.; Yuan, H. Q.; Kirchner, S.; Si, Q.

2013-07-01

Superconductivity in lanthanide- and actinide-based heavy-fermion (HF) metals can have different microscopic origins. Among others, Cooper pair formation based on fluctuations of the valence, of the quadrupole moment or of the spin of the localized 4f/5f shell have been proposed. Spin-fluctuation mediated superconductivity in CeCu2Si2 was demonstrated by inelastic neutron scattering to exist in the vicinity of a spin-density-wave (SDW) quantum critical point (QCP). The isostructural HF compound YbRh2Si2 which is prototypical for a Kondo-breakdown QCP has so far not shown any sign of superconductivity down to T ≈ 10 mK. In contrast, results of de-Haas-van-Alphen experiments by Shishido et al. (J. Phys. Soc. Jpn. 74, 1103 (2005)) suggest superconductivity in CeRhIn5 close to an antiferromagnetic QCP beyond the SDW type, at which the Kondo effect breaks down. For the related compound CeCoIn5 however, a field-induced QCP of SDW type is extrapolated to exist inside the superconducting phase.

Effects of grand unification interactions on weak symmetry breaking in supergravity theories

NASA Astrophysics Data System (ADS)

Moxhay, Peter; Yamamoto, Katsuji

Possible effects of grand unification interactions on SU(2) × U(1) breaking are investigated by explicitly considering a supersymmetric SU(5) model coupled to N = 1 supergravity. Some remarkable features concerning the effects of renormalization on the effective soft supersymmetry breaking terms of SU(5) in the GUT region MP - MG are clarified, which are relevant for determining the SU(3) × SU(2) × U(1) theory below MG. In particular, the (mass) 2 of the Higgs doublets, g Hm g2and g overlineHm g2, might become significantly small at M G (g H ⋍ g overlineH ≈ 0.1) through the effect of SU(5) couplings such as overlineHø EH . Then, gH can rather easily become negative below MG, so as to realize SU(2) × U(1) breaking naturally even for the "diet" top quark case ( mt ≈ 40 GeV). On the other hand, if g H ⋍ g overlineH ⋍ 1 at M G by neglecting the grand unification interactions, some careful tuning of μ32/ mg2 is required with an accuracy ⪅10 -2 to achieve SU(2) × U(1) breaking with "diet" top quark, though a mass term μ 32( overlineHH) may be present.

Alternative Break Programs: From Isolated Enthusiasm to Best Practices--The Haiti Compact

ERIC Educational Resources Information Center

Piacitelli, Jill; Barwick, Molly; Doerr, Elizabeth; Porter, Melody; Sumka, Shoshanna

2013-01-01

Alternative break programs, which are short-term service-learning trips, immerse students in direct service and education, resulting in the creation of active citizens who think and act critically around the root causes of social issues. Over the last 20 years, domestic alternative breaks have effectively created strong community partnerships and…

Experimental research on the dam-break mechanisms of the Jiadanwan landslide dam triggered by the Wenchuan earthquake in China.

PubMed

Xu, Fu-gang; Yang, Xing-guo; Zhou, Jia-wen; Hao, Ming-hui

2013-01-01

Dam breaks of landslide dams are always accompanied by large numbers of casualties, a large loss of property, and negative influences on the downstream ecology and environment. This study uses the Jiadanwan landslide dam, created by the Wenchuan earthquake, as a case study example. Several laboratory experiments are carried out to analyse the dam-break mechanism of the landslide dam. The different factors that impact the dam-break process include upstream flow, the boulder effect, dam size, and channel discharge. The development of the discharge channel and the failure of the landslide dam are monitored by digital video and still cameras. Experimental results show that the upstream inflow and the dam size are the main factors that impact the dam-break process. An excavated discharge channel, especially a trapezoidal discharge channel, has a positive effect on reducing peak flow. The depth of the discharge channel also has a significant impact on the dam-break process. The experimental results are significant for landslide dam management and flood disaster prevention and mitigation.

Experimental Research on the Dam-Break Mechanisms of the Jiadanwan Landslide Dam Triggered by the Wenchuan Earthquake in China

PubMed Central

Xu, Fu-gang; Yang, Xing-guo; Hao, Ming-hui

2013-01-01

Dam breaks of landslide dams are always accompanied by large numbers of casualties, a large loss of property, and negative influences on the downstream ecology and environment. This study uses the Jiadanwan landslide dam, created by the Wenchuan earthquake, as a case study example. Several laboratory experiments are carried out to analyse the dam-break mechanism of the landslide dam. The different factors that impact the dam-break process include upstream flow, the boulder effect, dam size, and channel discharge. The development of the discharge channel and the failure of the landslide dam are monitored by digital video and still cameras. Experimental results show that the upstream inflow and the dam size are the main factors that impact the dam-break process. An excavated discharge channel, especially a trapezoidal discharge channel, has a positive effect on reducing peak flow. The depth of the discharge channel also has a significant impact on the dam-break process. The experimental results are significant for landslide dam management and flood disaster prevention and mitigation. PMID:23844387

Breaking Bad News: An Evidence-Based Review of Communication Models for Oncology Nurses.

PubMed

Bumb, Meridith; Keefe, Joanna; Miller, Lindsay; Overcash, Janine

2017-10-01

A diagnosis of cancer is a stressful, difficult, and life-altering event. Breaking bad news is distressing to patients and families and is often uncomfortable for the nurse delivering it. Evidence-based communication models have been developed and adapted for use in clinical practice to assist nurses with breaking bad news.

. The purpose of this article is to provide an overview on breaking bad news and to review the utility of the SPIKES and PEWTER evidence-based communication models for oncology nurses.
. Perceptions of breaking bad news from the nurse and patient perspectives, as well as barriers and consequences to effective communication, will be presented. Clinical examples of possible situations of breaking bad news will demonstrate how to use the SPIKES and PEWTER models of communication when disclosing bad news to patients and their families.
. By using the evidence-based communication strategies depicted in this article, oncology nurses can support the delivery of bad news and maintain communication with their patients and their patients' families in an effective and productive manner.

Breaking the rules: sex roles and genetic mating system of the pheasant coucal.

PubMed

Maurer, G; Double, M C; Milenkaya, O; Süsser, M; Magrath, R D

2011-10-01

Generally in birds, the classic sex roles of male competition and female choice result in females providing most offspring care while males face uncertain parentage. In less than 5% of species, however, reversed courtship sex roles lead to predominantly male care and low extra-pair paternity. These role-reversed species usually have reversed sexual size dimorphism and polyandry, confirming that sexual selection acts most strongly on the sex with the smaller parental investment and accordingly higher potential reproductive rate. We used parentage analyses and observations from three field seasons to establish the social and genetic mating system of pheasant coucals, Centropus phasianinus, a tropical nesting cuckoo, where males are much smaller than females and provide most parental care. Pheasant coucals are socially monogamous and in this study males produced about 80% of calls in the dawn chorus, implying greater male sexual competition. Despite the substantial male investments, extra-pair paternity was unusually high for a socially monogamous, duetting species. Using two or more mismatches to determine extra-pair parentage, we found that 11 of 59 young (18.6%) in 10 of 21 broods (47.6%) were not sired by their putative father. Male incubation, starting early in the laying sequence, may give the female opportunity and reason to seek these extra-pair copulations. Monogamy, rather than the polyandry and sex-role reversal typical of its congener, C. grillii, may be the result of the large territory size, which could prevent females from monopolising multiple males. The pheasant coucal's exceptional combination of classic sex-roles and male-biased care for extra-pair young is hard to reconcile with current sexual selection theory, but may represent an intermediate stage in the evolution of polyandry or an evolutionary remnant of polyandry.

Influence of oxidized purine processing on strand directionality of mismatch repair.

PubMed

Repmann, Simone; Olivera-Harris, Maite; Jiricny, Josef

2015-04-17

Replicative DNA polymerases are high fidelity enzymes that misincorporate nucleotides into nascent DNA with a frequency lower than [1/10(5)], and this precision is improved to about [1/10(7)] by their proofreading activity. Because this fidelity is insufficient to replicate most genomes without error, nature evolved postreplicative mismatch repair (MMR), which improves the fidelity of DNA replication by up to 3 orders of magnitude through correcting biosynthetic errors that escaped proofreading. MMR must be able to recognize non-Watson-Crick base pairs and excise the misincorporated nucleotides from the nascent DNA strand, which carries by definition the erroneous genetic information. In eukaryotes, MMR is believed to be directed to the nascent strand by preexisting discontinuities such as gaps between Okazaki fragments in the lagging strand or breaks in the leading strand generated by the mismatch-activated endonuclease of the MutL homologs PMS1 in yeast and PMS2 in vertebrates. We recently demonstrated that the eukaryotic MMR machinery can make use also of strand breaks arising during excision of uracils or ribonucleotides from DNA. We now show that intermediates of MutY homolog-dependent excision of adenines mispaired with 8-oxoguanine (G(O)) also act as MMR initiation sites in extracts of human cells or Xenopus laevis eggs. Unexpectedly, G(O)/C pairs were not processed in these extracts and failed to affect MMR directionality, but extracts supplemented with exogenous 8-oxoguanine DNA glycosylase (OGG1) did so. Because OGG1-mediated excision of G(O) might misdirect MMR to the template strand, our findings suggest that OGG1 activity might be inhibited during MMR. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

The effects of a mid-task break on the brain connectome in healthy participants: A resting-state functional MRI study.

PubMed

Sun, Yu; Lim, Julian; Dai, Zhongxiang; Wong, KianFoong; Taya, Fumihiko; Chen, Yu; Li, Junhua; Thakor, Nitish; Bezerianos, Anastasios

2017-05-15

Although rest breaks are commonly administered as a countermeasure to reduce mental fatigue and boost cognitive performance, the effects of taking a break on behavior are not consistent. Moreover, our understanding of the underlying neural mechanisms of rest breaks and how they modulate mental fatigue is still rudimentary. In this study, we investigated the effects of receiving a rest break on the topological properties of brain connectivity networks via a two-session experimental paradigm, in which one session comprised four successive blocks of a mentally demanding visual selective attention task (No-rest session), whereas the other contained a rest break between the second and third task blocks (Rest session). Functional brain networks were constructed using resting-state functional MRI data recorded from 20 healthy adults before and after the performance of the task blocks. Behaviorally, subjects displayed robust time-on-task (TOT) declines, as reflected by increasingly slower reaction time as the test progressed and lower post-task self-reported ratings of engagement. However, we did not find a significant effect on task performance due to administering a mid-task break. Compared to pre-task measurements, post-task functional brain networks demonstrated an overall decrease of optimal small-world properties together with lower global efficiency. Specifically, we found TOT-related reduced nodal efficiency in brain regions that mainly resided in the subcortical areas. More interestingly, a significant block-by-session interaction was revealed in local efficiency, attributing to a significant post-task decline in No-rest session and a preserved local efficiency when a mid-task break opportunity was introduced in the Rest session. Taken together, these findings augment our understanding of how the resting brain reorganizes following the accumulation of prolonged task, suggest dissociable processes between the neural mechanisms of fatigue and recovery, and provide some of the first quantitative insights into the cognitive neuroscience of work and rest. Copyright © 2017 Elsevier Inc. All rights reserved.

Effects of summer school participation and psychosocial outcomes on changes in body composition and physical fitness during summer break.

PubMed

Park, Kyung-Shin; Lee, Man-Gyoon

2015-06-01

Evidence suggests that adolescents gain more weight during the summer break than they do during the school year, and that participation in the summer school program is beneficial in maintaining their healthy lifestyle. It is known that obesity and physical fitness in adolescents can be affected by their socio-economic and psychological status, especially during a long school break. The purpose of this study was to examine the effects of summer school participation and psychosocial outcomes on changes in body composition and physical fitness in underprivileged adolescents during the summer break. Body composition and physical fitness in 138 underprivileged adolescents were measured at the beginning and end of the summer break. A survey on socio-economic and psychological status was conducted at the beginning of the summer break. Two-way repeated measures ANOVA and Tukey post hoc tests were used for data analysis. Pearson correlation analysis was performed to establish a relation between psychological outcomes and changes in body composition and physical fitness during the summer break. Significant increases in body weight (p = .003) and % body fat (p = .014) as well as a decrease in VO2max (p = .018) were found in summer school non-attendants during the summer whereas no significant changes were found in summer school attendants. Summer school non-attendants with lower psychosocial outcomes had a greater decline in physical fitness and weight gain; however, summer school attendants were not affected by psychosocial outcomes. The summer school program effectively prevented summer weight gain among underprivileged adolescents due to the structured environment, restricted food access, and scheduled time for exercise in addition to minimizing the effects of their psychosocial outcomes. Results indicated that summer school non-attendants may require comprehensive intervention for psychosocial outcomes and nutritional education to maintain body weight and physical fitness levels during the summer break.

Effects of summer school participation and psychosocial outcomes on changes in body composition and physical fitness during summer break

PubMed Central

Park, Kyung-Shin; Lee, Man-Gyoon

2015-01-01

[Purpose] Evidence suggests that adolescents gain more weight during the summer break than they do during the school year, and that participation in the summer school program is beneficial in maintaining their healthy lifestyle. It is known that obesity and physical fitness in adolescents can be affected by their socio-economic and psychological status, especially during a long school break. The purpose of this study was to examine the effects of summer school participation and psychosocial outcomes on changes in body composition and physical fitness in underprivileged adolescents during the summer break. [Methods] Body composition and physical fitness in 138 underprivileged adolescents were measured at the beginning and end of the summer break. A survey on socio-economic and psychological status was conducted at the beginning of the summer break. Two-way repeated measures ANOVA and Tukey post hoc tests were used for data analysis. Pearson correlation analysis was performed to establish a relation between psychological outcomes and changes in body composition and physical fitness during the summer break. [Results] Significant increases in body weight (p = .003) and % body fat (p = .014) as well as a decrease in VO2max (p = .018) were found in summer school non-attendants during the summer whereas no significant changes were found in summer school attendants. Summer school non-attendants with lower psychosocial outcomes had a greater decline in physical fitness and weight gain; however, summer school attendants were not affected by psychosocial outcomes. The summer school program effectively prevented summer weight gain among underprivileged adolescents due to the structured environment, restricted food access, and scheduled time for exercise in addition to minimizing the effects of their psychosocial outcomes. [Conclusion] Results indicated that summer school non-attendants may require comprehensive intervention for psychosocial outcomes and nutritional education to maintain body weight and physical fitness levels during the summer break. PMID:26244126

THz spectra and corresponding vibrational modes of DNA base pair cocrystals and polynucleotides

NASA Astrophysics Data System (ADS)

Wang, Fang; Zhao, Dongbo; Dong, Hao; Jiang, Ling; Huang, Lin; Liu, Yunfei; Li, Shuhua

2018-07-01

The generalized energy-based fragmentation (GEBF) approach has been applied to study the THz spectra and vibrational modes of base pair cocrystals under periodic boundary conditions (denoted as PBC-GEBF). Results of vibrational mode reveal that hydrogen bonds play a pivotal role in the pairing process of base crystals, where most Nsbnd H and Csbnd H bonds stretch to some extent. We also found that hydrogen bonds of a self-made A:T cocrystal completely break in a transition from liquid to the solid state, while self-made C:G cocrystal is different and easier to form a cocrystal, as confirmed by X-ray diffraction (XRD) and terahertz (THz) spectra. Furthermore, we have studied DNA polynucleotides (in both A and B forms) found that the vibrational modes changed a lot during the process of their forming double strand. Despite the key role played by hydrogen bonds, the key contribution originates from collective motions of the main skeleton. A comparative study of the spectra of some stranded fragments suggests that different sequences or forms have similar spectra in THz band. They distinguish from each other mainly in the low-frequency regions, especially below 1 THz. This study would make great contributions to the molecular dynamics model based DNA long-chain structure simulation in the future study.

Fast Radio Bursts and Radio Transients from Black Hole Batteries

NASA Astrophysics Data System (ADS)

Mingarelli, Chiara; Levin, Janna; Lazio, Joseph

2016-03-01

Most black holes (BHs) will absorb a neutron star (NS) companion fully intact, without tidal disruption, suggesting the pair will remain dark to telescopes. Even without tidal disruption, electromagnetic (EM) luminosity is generated from the battery phase of the binary when the BH interacts with the NS magnetic field. Originally the luminosity was expected in high-energy X-rays or gamma-rays, however we conjecture that some of the battery power is emitted in the radio bandwidth. While the luminosity and timescale are suggestive of fast radio bursts (FRBs), NS-BH coalescence rates are too low to make these a primary FRB source. Instead, we propose the transients form a FRB sub-population, distinguishable by a double peak. The main burst is from the peak luminosity before merger, while the post-merger burst follows from the NS magnetic field migration to the BH, causing a shock. NS-BH pairs are desirable for ground-based gravitational wave (GW) observatories since the pair might not be detected any other way, with EM counterparts augmenting the scientific leverage beyond the GW signal. Valuably, EM signal can break degeneracies in the parameters encoded in the GW as well as probe the NS magnetic field strength, yielding insights into open problems in NS magnetic field decay.

Higgs pair production in vector-boson fusion at the LHC and beyond.

PubMed

Bishara, Fady; Contino, Roberto; Rojo, Juan

2017-01-01

The production of pairs of Higgs bosons at hadron colliders provides unique information on the Higgs sector and on the mechanism underlying electroweak symmetry breaking (EWSB). Most studies have concentrated on the gluon-fusion production mode which has the largest cross section. However, despite its small production rate, the vector-boson fusion channel can also be relevant since even small modifications of the Higgs couplings to vector bosons induce a striking increase of the cross section as a function of the invariant mass of the Higgs boson pair. In this work we exploit this unique signature to propose a strategy to extract the hhVV quartic coupling and provide model-independent constraints on theories where EWSB is driven by new strong interactions. We take advantage of the higher signal yield of the [Formula: see text] final state and make extensive use of jet-substructure techniques to reconstruct signal events with a boosted topology, characteristic of large partonic energies, where each Higgs boson decays to a single collimated jet. Our results demonstrate that the hhVV coupling can be measured with 45% (20%) precision at the LHC for [Formula: see text] (3000) fb[Formula: see text], while a 1% precision can be achieved at a 100 TeV collider.

Evidence of protein-free homology recognition in magnetic bead force–extension experiments

PubMed Central

(O’) Lee, D. J.; Danilowicz, C.; Rochester, C.; Prentiss, M.

2016-01-01

Earlier theoretical studies have proposed that the homology-dependent pairing of large tracts of dsDNA may be due to physical interactions between homologous regions. Such interactions could contribute to the sequence-dependent pairing of chromosome regions that may occur in the presence or the absence of double-strand breaks. Several experiments have indicated the recognition of homologous sequences in pure electrolytic solutions without proteins. Here, we report single-molecule force experiments with a designed 60 kb long dsDNA construct; one end attached to a solid surface and the other end to a magnetic bead. The 60 kb constructs contain two 10 kb long homologous tracts oriented head to head, so that their sequences match if the two tracts fold on each other. The distance between the bead and the surface is measured as a function of the force applied to the bead. At low forces, the construct molecules extend substantially less than normal, control dsDNA, indicating the existence of preferential interaction between the homologous regions. The force increase causes no abrupt but continuous unfolding of the paired homologous regions. Simple semi-phenomenological models of the unfolding mechanics are proposed, and their predictions are compared with the data. PMID:27493568

Detusking fence-breaker elephants as an approach in human-elephant conflict mitigation.

PubMed

Mutinda, Matthew; Chenge, Geoffrey; Gakuya, Francis; Otiende, Moses; Omondi, Patrick; Kasiki, Samuel; Soriguer, Ramón C; Alasaad, Samer

2014-01-01

Human-elephant conflict (HEC) is a recurring problem that appears wherever the range of elephants and humans overlap. Different methods including the use of electric fences are used worldwide to mitigate this conflict. Nonetheless, elephants learn quickly that their tusks do not conduct electricity and use them to break down fences (fence-breakers). In Lewa Wildlife Conservancy, Kenya, destructive elephants (Loxodonta africana) were monitored between 2010 and 2013. The fence-breaking rate reached four incidents (fence-breaking) per elephant per 100 days. Ten bull males and 57 females were identified as fence-breakers. The bulls were involved in 85.07% and the females in 14.93% of incidents. The Kenya Wildlife Service approved detusking (partial cutting of tusks) in four of the 10 fence-breakers as a way of preventing them from breaking down fences, thereby mitigating HEC in the Conservancy. The result of the detusking was a drastic six-fold reduction in damage to fences (range: 1.67 to 14.5 times less fence-breaking) by the four worst fence-breaker elephants, because with trimmed tusks elephants lack the tools to break down fences. Detusking could not totally eliminate fence destruction because, despite lacking their tools, elephants can still destroy fences using their heads, bodies and trunks, albeit less effectively. On the other hand, apart from inherent aesthetic considerations, the detusking of elephants may have certain negative effects on factors such as elephants' social hierarchies, breeding, mate selection and their access to essential minerals and food. Elephant detusking seems to be effective in drastically reducing fence-breaking incidents, nonetheless its negative effects on behaviour, access to food and its aesthetical consequences still need to be further studied and investigated.

Detusking Fence-Breaker Elephants as an Approach in Human-Elephant Conflict Mitigation

PubMed Central

Mutinda, Matthew; Chenge, Geoffrey; Gakuya, Francis; Otiende, Moses; Omondi, Patrick; Kasiki, Samuel; Soriguer, Ramón C.; Alasaad, Samer

2014-01-01

Background Human-elephant conflict (HEC) is a recurring problem that appears wherever the range of elephants and humans overlap. Different methods including the use of electric fences are used worldwide to mitigate this conflict. Nonetheless, elephants learn quickly that their tusks do not conduct electricity and use them to break down fences (fence-breakers). Methodology/Principal Findings In Lewa Wildlife Conservancy, Kenya, destructive elephants (Loxodonta africana) were monitored between 2010 and 2013. The fence-breaking rate reached four incidents (fence-breaking) per elephant per 100 days. Ten bull males and 57 females were identified as fence-breakers. The bulls were involved in 85.07% and the females in 14.93% of incidents. The Kenya Wildlife Service approved detusking (partial cutting of tusks) in four of the 10 fence-breakers as a way of preventing them from breaking down fences, thereby mitigating HEC in the Conservancy. The result of the detusking was a drastic six-fold reduction in damage to fences (range: 1.67 to 14.5 times less fence-breaking) by the four worst fence-breaker elephants, because with trimmed tusks elephants lack the tools to break down fences. Detusking could not totally eliminate fence destruction because, despite lacking their tools, elephants can still destroy fences using their heads, bodies and trunks, albeit less effectively. On the other hand, apart from inherent aesthetic considerations, the detusking of elephants may have certain negative effects on factors such as elephants' social hierarchies, breeding, mate selection and their access to essential minerals and food. Conclusions Elephant detusking seems to be effective in drastically reducing fence-breaking incidents, nonetheless its negative effects on behaviour, access to food and its aesthetical consequences still need to be further studied and investigated. PMID:24614538

Booster Breaks in the workplace: participants’ perspectives on health-promoting work breaks

PubMed Central

Taylor, Wendell C.; King, Kathryn E.; Shegog, Ross; Paxton, Raheem J.; Evans-Hudnall, Gina L.; Rempel, David M.; Chen, Vincent; Yancey, Antronette K.

2013-01-01

Increasing sedentary work has been associated with greater cardiovascular and metabolic risk, as well as premature mortality. Interrupting the sedentary workday with health-promoting work breaks can counter these negative health effects. To examine the potential sustainability of work-break programs, we assessed the acceptance of these breaks among participants in a Booster Break program. We analyzed qualitative responses from 35 participants across five worksites where one 15-min physical activity break was taken each workday. Two worksites completed a 1-year intervention and three worksites completed a 6-month intervention. Responses to two open-ended questions about the acceptance and feasibility of Booster Breaks were obtained from a survey administered after the intervention. Three themes for benefits and two themes for barriers were identified. The benefit themes were (i) reduced stress and promoted enjoyment, (ii) increased health awareness and facilitated behavior change, and (iii) enhanced workplace social interaction. The barrier themes were the need for (iv) greater variety in Booster Break routines and (v) greater management support. This study provides empirical support for the acceptance and feasibility of Booster Breaks during the workday. Emphasizing the benefits and minimizing the barriers are strategies that can be used to implement Booster Breaks in other workplaces. PMID:23466367

Production Cross-Section Estimates for Strongly-Interacting Electroweak-Symmetry Breaking Sector Resonances at Particle Colliders

NASA Astrophysics Data System (ADS)

Dobado, Antonio; Guo, Feng-Kun; Llanes-Estrada, Felipe J.

2015-12-01

We are exploring a generic strongly-interacting Electroweak Symmetry Breaking Sector (EWSBS) with the low-energy effective field theory for the four experimentally known particles (W±L, ZL, h) and its dispersion-relation based unitary extension. In this contribution we provide simple estimates for the production cross-section of pairs of the EWSBS bosons and their resonances at proton-proton colliders as well as in a future e-e+ (or potentially a μ-μ+) collider with a typical few-TeV energy. We examine the simplest production mechanisms, tree-level production through a W (dominant when quantum numbers allow) and the simple effective boson approximation (in which the electroweak bosons are considered as collinear partons of the colliding fermions). We exemplify with custodial isovector and isotensor resonances at 2 TeV, the energy currently being discussed because of a slight excess in the ATLAS 2-jet data. We find it hard, though not unthinkable, to ascribe this excess to one of these WLWL rescattering resonances. An isovector resonance could be produced at a rate smaller than, but close to earlier CMS exclusion bounds, depending on the parameters of the effective theory. The ZZ excess is then problematic and requires additional physics (such as an additional scalar resonance). The isotensor one (that would describe all charge combinations) has smaller cross-section. Supported by the Spanish Excellence Network on Hadronic Physics FIS2014-57026-REDT, by Spanish Grants Universidad Complutense UCM:910309 and Ministerio de Economia y Competitividad MINECO:FPA2011-27853-C02-01, MINECO:FPA2014-53375-C2-1-P, by the Deutsche Forschungsgemeinschaft and National Natural Science Foundation of China through Funds Provided to the Sino-German CRC 110 “Symmetries and the Emergence of Structure in QCD” (NSFC Grant No. 11261130311) and by NSFC (Grant No. 11165005)

Damage of chromosoms under irradiation of human blood lymphocytes and development of bystander effect.

PubMed

Shemetun, O V

2016-12-01

the research the distribution of radiation induced damages among chromosomes and their bands in irra diated in vitro human blood lymphocytes and in unirradiated bystander cells.Material and methods of research: cultivation of human peripheral blood lymphocytes by semi micromethod D.A. Hungerford, modeling of radiation induced bystander effect in mixed cultures consisting of irradiated in vitro and non irradiated blood lymphocytes from persons of different gender, GTG staining of metaphase chromosomes and their cytogenetic analysis. Break points in chromosomes under the formation of aberrations were identified in exposed in vitro human peripheral blood lymphocytes in doses 0.25 Gy (95 breaks in 1248 cells) and 1.0 Gy (227 breaks in 726 cells) and in non irradiated bystander cells under their joint cultivation with irradiated in vitro human lymphocytes (51 breaks in 1137 cells at irradiation of adjacent populations of lymphocytes in dose 0.25 Gy and 75 breaks in 1321 cells at irradiation of adjacent population of lymphocytes in a dose 1.0 Gy). The distribution of injuries among the chromo somes and their bands was investigated. in radiation exposed in vitro human peripheral blood lymphocytes as well as in bystander cells the fre quency of damaged bands and number of breaks which localized in them exceeded the control value (p < 0.01). As under direct radiation exposure, as under formation of breaks due to induction of bystander effect, chromosomes were damaged according to their relative length. Location of bands with increasing number of breaks coincided with the «hot spots» of chromosome damage following irradiation and fragile sites. More sensitive to damage were G negative euchromatin chromosome bands, in which were localized 82 88 % breaks. Damageability of telomeric regions in the irradiated cells had no significant difference from the control, while in bystander cells was lower than control value (p < 0.05). O. V. Shemetun.

Unified models of the QCD axion and supersymmetry breaking

NASA Astrophysics Data System (ADS)

Harigaya, Keisuke; Leedom, Jacob M.

2017-08-01

Similarities between the gauge meditation of supersymmetry breaking and the QCD axion model suggest that they originate from the same dynamics. We present a class of models where supersymmetry and the Peccei-Quinn symmetry are simultaneously broken. The messengers that mediate the effects of these symmetry breakings to the Standard Model are identical. Since the axion resides in the supersymmetry breaking sector, the saxion and the axino are heavy. We show constraints on the axion decay constant and the gravitino mass.

The Effect of Break Edge Configuration on the Aerodynamics of Anti-Ice Jet Flow

NASA Astrophysics Data System (ADS)

Tatar, V.; Yildizay, H.; Aras, H.

2015-05-01

One of the components of a turboprop gas turbine engine is the Front Bearing Structure (FBS) which leads air into the compressor. FBS directly encounters with ambient air, as a consequence ice accretion may occur on its static vanes. There are several aerodynamic parameters which should be considered in the design of anti-icing system of FBS, such as diameter, position, exit angle of discharge holes, etc. This research focuses on the effects of break edge configuration over anti-ice jet flow. Break edge operation is a process which is applied to the hole in order to avoid sharp edges which cause high stress concentration. Numerical analyses and flow visualization test have been conducted. Four different break edge configurations were used for this investigation; without break edge, 0.35xD, 74xD, 0.87xD. Three mainstream flow conditions at the inlet of the channel are defined; 10m/s, 20 m/s and 40 m/s. Shear stresses are extracted from numerical analyses near the trailing edge of pressure surface where ice may occur under icing conditions. A specific flow visualization method was used for the experimental study. Vane surface near the trailing edge was dyed and thinner was injected into anti-ice jet flow in order to remove dye from the vane surface. Hence, film effect on the surface could be computed for each testing condition. Thickness of the dye removal area of each case was examined. The results show noticeable effects of break edge operation on jet flow, and the air film effectiveness decreases when mainstream inlet velocity decreases.

Reducing Hunger-Associated Symptoms: The Midmorning Nutrition Break

ERIC Educational Resources Information Center

Sweeney, Nancy M.; Tucker, Joanne; Reynosa, Brenda; Glaser, Dale

2006-01-01

This study measured the effectiveness of a 9 a.m. nutrition break after it had been implemented for 1 academic year at an inner-city high school. Effectiveness was measured by student participation rates, student and teacher evaluations of hunger-associated symptoms experienced by students, and teacher evaluations of the effects on the learning…

Effects of Coherence and Relevance on Shallow and Deep Text Processing.

ERIC Educational Resources Information Center

Lehman, Stephen; Schraw, Gregory

2002-01-01

Examines the effects of coherence and relevance on shallow and deeper text processing, testing the hypothesis that enhancing the relevance of text segments compensates for breaks in local and global coherence. Results reveal that breaks in local coherence had no effect on any outcome measures, whereas relevance enhanced deeper processing.…

Rule breaking mediates the developmental association between GABRA2 and adolescent substance abuse.

PubMed

Trucco, Elisa M; Villafuerte, Sandra; Heitzeg, Mary M; Burmeister, Margit; Zucker, Robert A

2014-12-01

This study's primary aim was to examine age-specific associations between GABRA2, rule breaking, problematic alcohol use, and substance abuse symptomatology. The secondary aim was to examine the extent to which rule breaking mediates the GABRA2-substance abuse relationship. A sample (n = 518) of primarily male (70.9%) and White (88.8%) adolescents from the Michigan Longitudinal Study was assessed from ages 11-18. Age-specific effects of GABRA2 on rule breaking, problematic alcohol use, and substance abuse symptomatology were examined using nested path models. The role of rule breaking as a mediator in the association between GABRA2 and substance abuse outcomes was tested using prospective cross-lagged path models. GABRA2 is significantly (p < 0.05) associated with rule breaking in mid- to late-adolescence, but not substance abuse symptomatology across adolescence. GABRA2 effects on problematic alcohol use and substance abuse symptomatology operate largely (45.3% and 71.1%, respectively, p < 0.05) via rule breaking in midadolescence. GABRA2 represents an early risk factor for an externalizing pathway to the development of problematic alcohol and drug use. © 2014 The Authors. Journal of Child Psychology and Psychiatry. © 2014 Association for Child and Adolescent Mental Health.

Assessing the benefits of napping and short rest breaks on processing speed in sleep-restricted adolescents.

PubMed

Lim, Julian; Lo, June C; Chee, Michael W L

2017-04-01

Achievement-oriented adolescents often study long hours under conditions of chronic sleep restriction, adversely affecting cognitive function. Here, we studied how napping and rest breaks (interleaved off-task periods) might ameliorate the negative effects of sleep restriction on processing speed. Fifty-seven healthy adolescents (26 female, age = 15-19 years) participated in a 15-day live-in protocol. All participants underwent sleep restriction (5 h time-in-bed), but were then randomized into two groups: one of these groups received a daily 1-h nap opportunity. Data from seven of the study days (sleep restriction days 1-5, and recovery days 1-2) are reported here. The Blocked Symbol Decoding Test, administered once a day, was used to assess time-on-task effects and the effects of rest breaks on processing speed. Controlling for baseline differences, participants who took a nap demonstrated faster speed of processing and greater benefit across testing sessions from practice. These participants were also affected significantly less by time-on-task effects. In contrast, participants who did not receive a nap benefited more from the rest breaks that were permitted between blocks of the test. Our results indicate that napping partially reverses the detrimental effects of sleep restriction on processing speed. However, rest breaks have a greater effect as a countermeasure against poor performance when sleep pressure is higher. These data add to the growing body of evidence showing the importance of sleep for good cognitive functioning in adolescents, and suggest that more frequent rest breaks might be important in situations where sleep loss is unavoidable. © 2017 European Sleep Research Society.

Propagation and Breaking at High Altitudes of Gravity Waves Excited by Tropospheric Forcing

NASA Technical Reports Server (NTRS)

Prusa, Joseph M.; Smolarkiewicz, Piotr K.; Garcia, Rolando R.

1996-01-01

An anelastic approximation is used with a time-variable coordinate transformation to formulate a two-dimensional numerical model that describes the evolution of gravity waves. The model is solved using a semi-Lagrangian method with monotone (nonoscillatory) interpolation of all advected fields. The time-variable transformation is used to generate disturbances at the lower boundary that approximate the effect of a traveling line of thunderstorms (a squall line) or of flow over a broad topographic obstacle. The vertical propagation and breaking of the gravity wave field (under conditions typical of summer solstice) is illustrated for each of these cases. It is shown that the wave field at high altitudes is dominated by a single horizontal wavelength; which is not always related simply to the horizontal dimension of the source. The morphology of wave breaking depends on the horizontal wavelength; for sufficiently short waves, breaking involves roughly one half of the wavelength. In common with other studies, it is found that the breaking waves undergo "self-acceleration," such that the zonal-mean intrinsic frequency remains approximately constant in spite of large changes in the background wind. It is also shown that many of the features obtained in the calculations can be understood in terms of linear wave theory. In particular, linear theory provides insights into the wavelength of the waves that break at high altitudes, the onset and evolution of breaking. the horizontal extent of the breaking region and its position relative to the forcing, and the minimum and maximum altitudes where breaking occurs. Wave breaking ceases at the altitude where the background dissipation rate (which in our model is a proxy for molecular diffusion) becomes greater than the rate of dissipation due to wave breaking, This altitude, in effect, the model turbopause, is shown to depend on a relatively small number of parameters that characterize the waves and the background state.

Potential landscape and flux field theory for turbulence and nonequilibrium fluid systems

NASA Astrophysics Data System (ADS)

Wu, Wei; Zhang, Feng; Wang, Jin

2018-02-01

Turbulence is a paradigm for far-from-equilibrium systems without time reversal symmetry. To capture the nonequilibrium irreversible nature of turbulence and investigate its implications, we develop a potential landscape and flux field theory for turbulent flow and more general nonequilibrium fluid systems governed by stochastic Navier-Stokes equations. We find that equilibrium fluid systems with time reversibility are characterized by a detailed balance constraint that quantifies the detailed balance condition. In nonequilibrium fluid systems with nonequilibrium steady states, detailed balance breaking leads directly to a pair of interconnected consequences, namely, the non-Gaussian potential landscape and the irreversible probability flux, forming a 'nonequilibrium trinity'. The nonequilibrium trinity characterizes the nonequilibrium irreversible essence of fluid systems with intrinsic time irreversibility and is manifested in various aspects of these systems. The nonequilibrium stochastic dynamics of fluid systems including turbulence with detailed balance breaking is shown to be driven by both the non-Gaussian potential landscape gradient and the irreversible probability flux, together with the reversible convective force and the stochastic stirring force. We reveal an underlying connection of the energy flux essential for turbulence energy cascade to the irreversible probability flux and the non-Gaussian potential landscape generated by detailed balance breaking. Using the energy flux as a center of connection, we demonstrate that the four-fifths law in fully developed turbulence is a consequence and reflection of the nonequilibrium trinity. We also show how the nonequilibrium trinity can affect the scaling laws in turbulence.

Indirect probes of supersymmetry breaking in the JEM-EUSO observatory

NASA Astrophysics Data System (ADS)

Albuquerque, Ivone F. M.; Cavalcante de Souza, Jairo

2013-01-01

In this paper we propose indirect probes of the supersymmetry-breaking scale, through observations in the Extreme Universe Space Observatory onboard the Japanese Experiment Module (JEM-EUSO). We consider scenarios where the lightest supersymmetric particle is the gravitino, and the next-to-lightest supersymmetric particle (NLSP) is a long-lived slepton. We demonstrate that JEM-EUSO will be able to probe models where the NLSP decays, therefore probing supersymmetry-breaking scales below 5×106GeV. The observatory field of view will be large enough to detect a few tens of events per year, depending on its energy threshold. This is complementary to a previous proposal [I. Albuquerque , Phys. Rev. Lett. 92, 221802 (2004)PRLTAO0031-9007] where it was shown that 1km3 neutrino telescopes can directly probe this scale. NLSPs will be produced by the interaction of high-energy neutrinos in the Earth. Here we investigate scenarios where they subsequently decay, either in the atmosphere after escaping the Earth or right before leaving the Earth, producing taus. These can be detected by JEM-EUSO and have two distinctive signatures: one, they are produced in the Earth and go upwards in the atmosphere, which allows discrimination from atmospheric taus, and second, as NLSPs are always produced in pairs, coincident taus will be a strong signature for these events. Assuming that the neutrino flux is equivalent to the Waxman-Bahcall limit, we determine the rate of taus from NLSP decays reaching JEM-EUSO’s field of view.

Possible nodal vortex state in CeRu2

NASA Astrophysics Data System (ADS)

Kadono, R.; Higemoto, W.; Koda, A.; Ohishi, K.; Yokoo, T.; Akimitsu, J.; Hedo, M.; Inada, Y.; O¯nuki, Y.; Yamamoto, E.; Haga, Y.

2001-06-01

The microscopic property of magnetic vortices in the mixed state of a high-quality CeRu2 crystal has been studied by muon spin rotation. We have found that the spatial distribution of magnetic induction B(r) probed by muons is perfectly described by the London model for the triangular vortex lattice with appropriate modifications to incorporate the high-field cutoff around the vortex core and the effect of long-range defects in the vortex lattice structure at lower fields. The vortex core radius is proportional to H(β-1)/2 with β~=0.53 (H being the magnetic field), which is in good agreement with the recently observed nonlinear field dependence of the electronic specific heat coefficient γ~Hβ. In particular, the anomalous increase of magnetic penetration depth in accordance with the peak effect in dc magnetization (>=H*~=3 T at 2.0 K) has been confirmed; this cannot be explained by the conventional pair-breaking effect due to magnetic field. In addition, the spontaneous enhancement of flux pinning, which is also associated with the peak effect, has been demonstrated microscopically. These results strongly suggest the onset of collective pinning induced by a new vortex state having an anomalously enhanced quasiparticle density of states for H>=H*.

Search for O[-1] earthquake-like precursors: a ME μSR MgO study

NASA Astrophysics Data System (ADS)

Boekema, C.; Cabot, A.; Lee, A.-L.; Lin, I.; Colebaugh, A.; Freund, Ft

We study O-1 earthquake-like precursor effects by analyzing Muon-Spin-Resonance (μSR) MgO data using Maximum Entropy (ME). Due to its presence in the Earth's crust, MgO is ideal to study these features. O-1 formation results from a 2-stage break-up in an O anion pair at high-temperature or high-pressure conditions. As T increases above room temperature, a small % of oxygen is predicted to produce an O-1 state. ME analysis of 100-Oe μSR data of a pure 3N-MgO single crystal produces a broad Gaussian at 1.36 MHz and a sharp Lorentzian at 1.4 MHz. The latter could be effects of extended O-1 states, as positive muons probe near O ions. There is no sharp 1.4-MHz signal observed in the μSR data of insulators Al2O3 and PrBCO6 data, only the expected 100-Oe Gaussian. We have fitted ME μSR transforms of MgO to obtain an empirical description of 1.36- and 1.4- MHz peaks. Their T dependences above room temperature appear to be positive-hole effects. Relations to precursor earthquake-like O-valency effects are discussed. Research supported by ISIS-UK, LANL-DOE, SETI-NASA, SJSU & AFC.

Time symmetry breaking in Bose-Einstein condensates

NASA Astrophysics Data System (ADS)

Mendonça, J. T.; Gammal, A.

2017-09-01

We consider different processes leading to time symmetry breaking in a Bose-Einstein condensate. Our approach provides a global description of time symmetry breaking, based on the equations of a thermal condensate. This includes quenching and expansion of the condensate, the Kibble-Zurek mechanism associated with the creation of vorticity, the dynamical Casimir effect and the formation of time crystals.

Laser-tissue soldering with biodegradable polymer films in vitro: film surface morphology and hydration effects.

PubMed

Sorg, B S; Welch, A J

2001-01-01

Previous research introduced the concept of using biodegradable polymer film reinforcement of a liquid albumin solder for improvement of the tensile strength of repaired incisions in vitro. In this study, the effect of creating small pores in the PLGA films on the weld breaking strength is studied. Additionally, the effect of hydration on the strength of the reinforced welds is investigated. A 50%(w/v) bovine serum albumin solder with 0.5 mg/mL Indocyanine Green dye was used to repair an incision in bovine aorta. The solder was coagulated with an 806-nm CW diode laser. A poly(DL-lactic-co-glycolic acid) (PLGA) film was used to reinforce the solder (the controls had solder but no reinforcement). Breaking strengths were measured acutely and after hydration in saline for 1 and 2 days. The data were analyzed by ANOVA (P < 0.05) and multiple comparisons of means were performed using the Newman-Keuls test. The creation of pores in the PLGA films qualitatively improved the film flexibility without having an apparent adverse effect on the breaking strength, while the actual technique of applying the film and solder had more of an effect. The acute maximum average breaking strengths of some of the film reinforced specimens (114.7 g-134.4 g) were significantly higher (P < 0.05) than the acute maximum average breaking strength of the unreinforced control specimens (68.3 g). Film reinforced specimens were shown to have a statistically significantly higher breaking strength than unreinforced controls after 1- and 2-day hydration. Reinforcement of liquid albumin solders in laser-assisted incision repair appears to have advantages over conventional methods that do not reinforce the cohesive strength of the solder in terms of acute breaking strength and after immersion in moist environments for short periods of time. Using a film with the solder applied to one surface only may be advantageous over other techniques.

Quantum hall ferromagnets

NASA Astrophysics Data System (ADS)

Kumar, Akshay

We study several quantum phases that are related to the quantum Hall effect. Our initial focus is on a pair of quantum Hall ferromagnets where the quantum Hall ordering occurs simultaneously with a spontaneous breaking of an internal symmetry associated with a semiconductor valley index. In our first example ---AlAs heterostructures--- we study domain wall structure, role of random-field disorder and dipole moment physics. Then in the second example ---Si(111)--- we show that symmetry breaking near several integer filling fractions involves a combination of selection by thermal fluctuations known as "order by disorder" and a selection by the energetics of Skyrme lattices induced by moving away from the commensurate fillings, a mechanism we term "order by doping". We also study ground state of such systems near filling factor one in the absence of valley Zeeman energy. We show that even though the lowest energy charged excitations are charge one skyrmions, the lowest energy skyrmion lattice has charge > 1 per unit cell. We then broaden our discussion to include lattice systems having multiple Chern number bands. We find analogs of quantum Hall ferromagnets in the menagerie of fractional Chern insulator phases. Unlike in the AlAs system, here the domain walls come naturally with gapped electronic excitations. We close with a result involving only topology: we show that ABC stacked multilayer graphene placed on boron nitride substrate has flat bands with non-zero local Berry curvature but zero Chern number. This allows access to an interaction dominated system with a non-trivial quantum distance metric but without the extra complication of a non-zero Chern number.

Hot accretion disks with pairs: Effects of magnetic field and thermal cyclocsynchrotron radiation

NASA Technical Reports Server (NTRS)

Kusunose, Masaaki; Zdziarski, Andrzej A.

1994-01-01

We show the effects of thermal cyclosynchrotron radiation and magnetic viscosity on the structure of hot, two-temperature accretion disks. Magnetic field, B, is assumed to be randomly oriented and the ratio of magnetic pressure to either gas pressure, alpha = P(sub mag)/P(sub gas), or the sum of the gas and radiation pressures, alpha = (P(sub mag)/P(sub gas) + P(sub rad)), is fixed. We find those effects do not change the qualitative properties of the disks, i.e., there are still two critical accretion rates related to production of e(sup +/-) pairs, (M dot)((sup U)(sub cr)) and (M dot)((sup L)(sub cr)), that affect the number of local and global disk solutions, as recently found by Bjoernsson and Svensson for the case with B = 0. However, a critical value of the alpha-viscosity parameter above which those critical accretion rates disappear becomes smaller than alpha(sub cr) = 1 found in the case of B = 0, for P(sub mag) = alpha(P(sub gas) + P(sub rad)). If P(sub mag) = alpha P(sub gas), on the other hand, alpha(sub cr) is still about unity. Moreover, when Comptonized cyclosynchrotron radiation dominates Comptonized bremsstrahlung, radiation from the disk obeys a power law with the energy spectral index of approximately 0.5, in a qualitative agreement with X-ray observations of active galactic nuclei (AGNS) and Galactic black hole candidates. We also extend the hot disk solutions for P(sub mag) = alpha(P(sub gas) + P(sub rad)) to the effectively optically thick region, where they merge with the standard cold disk solutions. We find that the mapping method by Bjoernsson and Svensson gives a good approximation to the disk structure in the hot region and show where it breaks in the transition region. Finally, we find a region in the disk parameter space with no solutions due to the inability of Coulomb heating to supply enough energy to electrons.

Chiral Symmetry Breaking in Crystal Growth: Is Hydrodynamic Convection Relevant?

NASA Technical Reports Server (NTRS)

Martin, B.; Tharrington, A.; Wu, Xiao-Lun

1996-01-01

The effects of mechanical stirring on nucleation and chiral symmetry breaking have been investigated for a simple inorganic molecule, sodium chlorate (NaClO3). In contrast to earlier findings, our experiment suggests that the symmetry breaking may have little to do with hydrodynamic convection. Rather the effect can be reasonably accounted for by mechanical damage to incipient crystals. The catastrophic events, creating numerous small 'secondary' crystals, produce statistical domination of one chiral species over the other. Our conclusion is supported by a number of observations using different mixing mechanisms.

Dissecting the hybridization of oligonucleotides to structured complementary sequences.

PubMed

Peracchi, Alessio

2016-06-01

When oligonucleotides hybridize to long target molecules, the process is slowed by the secondary structure in the targets. The phenomenon has been analyzed in several previous studies, but many details remain poorly understood. I used a spectrofluorometric strategy, focusing on the formation/breaking of individual base pairs, to study the kinetics of association between a DNA hairpin and >20 complementary oligonucleotides ('antisenses'). Hybridization rates differed by over three orders of magnitude. Association was toehold-mediated, both for antisenses binding to the target's ends and for those designed to interact with the loop. Binding of these latter, besides being consistently slower, was affected to variable, non-uniform extents by the asymmetric loop structure. Divalent metal ions accelerated hybridization, more pronouncedly when nucleation occurred at the loop. Incorporation of locked nucleic acid (LNA) residues in the antisenses substantially improved the kinetics only when LNAs participated to the earliest hybridization steps. The effects of individual LNAs placed along the antisense indicated that the reaction transition state occurred after invading at least the first base pair of the stem. The experimental approach helps dissect hybridization reactions involving structured nucleic acids. Toehold-dependent, nucleation-invasion models appear fully appropriate for describing such reactions. Estimating the stability of nucleation complexes formed at internal toeholds is the major hurdle for the quantitative prediction of hybridization rates. While analyzing the mechanisms of a fundamental biochemical process (hybridization), this work also provides suggestions for the improvement of technologies that rely on such process. Copyright © 2016 Elsevier B.V. All rights reserved.

The Relationship between the (In-)Stability of NORs and Their Chromosomal Location: The Example of Cercopithecidae and a Short Review of Other Primates.

PubMed

Gerbault-Seureau, Michèle; Cacheux, Lauriane; Dutrillaux, Bernard

2017-01-01

Amongst Cercopithecidae, the species of the Cercopithecini tribe underwent a very active chromosome evolution, principally by fissions, which increased their chromosome number up to 72. In contrast, all the species of Papionini have fairly similar karyotypes with 42 chromosomes. In animals, nucleolus organizer regions (NORs) are generally considered as instable structures, which frequently vary in size, number, and location at both infra- and interspecific levels. Although in Cercopithecinae the NORs, involved in breaks, exchanges, and translocations, behave like fragile sites in somatic cells, their number and location appear to be very stable between species. Fluorescence in situ hybridization of a 28S rDNA probe on metaphase chromosomes displayed a unique interstitial location in either an acrocentric pair (in 12 species of Cercopithecini) or a metacentric pair (in 6 species of Papionini). A non-exhaustive survey of literature data on NOR location in other primates shows that numerical variations of the NORs principally depend on their location: most multiple NORs are in terminal positions, while almost all unique NORs are in interstitial positions. We propose that this correlation is the consequence of the selection against gametic imbalances involving the chromosomal material distal to the NORs, which is effective when they are interstitially, but not terminally, located. Thus, the consequences of the interstitial NOR instability for reproduction are essentially limited to their size variations, as observed in Cercopithecidae. © 2018 S. Karger AG, Basel.

Hamiltonian bifurcation perspective on two interacting vortex pairs: From symmetric to asymmetric leapfrogging, period doubling, and chaos

NASA Astrophysics Data System (ADS)

Whitchurch, Brandon; Kevrekidis, Panayotis G.; Koukouloyannis, Vassilis

2018-01-01

In this work we study the dynamical behavior of two interacting vortex pairs, each one of them consisting of two point vortices with opposite circulation in the two-dimensional plane. The vortices are considered as effective particles and their interaction can be described in classical mechanics terms. We first construct a Poincaré section, for a typical value of the energy, in order to acquire a picture of the structure of the phase space of the system. We divide the phase space in different regions which correspond to qualitatively distinct motions and we demonstrate its different temporal evolution in the "real" vortex space. Our main emphasis is on the leapfrogging periodic orbit, around which we identify a region that we term the "leapfrogging envelope" which involves mostly regular motions, such as higher order periodic and quasiperiodic solutions. We also identify the chaotic region of the phase plane surrounding the leapfrogging envelope as well as the so-called walkabout and braiding motions. Varying the energy as our control parameter, we construct a bifurcation tree of the main leapfrogging solution and its instabilities, as well as the instabilities of its daughter branches. We identify the symmetry-breaking instability of the leapfrogging solution (in line with earlier works), and also obtain the corresponding asymmetric branches of periodic solutions. We then characterize their own instabilities (including period doubling ones) and bifurcations in an effort to provide a more systematic perspective towards the types of motions available to this dynamical system.

An Artificial Intelligence Approach for Modeling and Prediction of Water Diffusion Inside a Carbon Nanotube

PubMed Central

2009-01-01

Modeling of water flow in carbon nanotubes is still a challenge for the classic models of fluid dynamics. In this investigation, an adaptive-network-based fuzzy inference system (ANFIS) is presented to solve this problem. The proposed ANFIS approach can construct an input–output mapping based on both human knowledge in the form of fuzzy if-then rules and stipulated input–output data pairs. Good performance of the designed ANFIS ensures its capability as a promising tool for modeling and prediction of fluid flow at nanoscale where the continuum models of fluid dynamics tend to break down. PMID:20596382

The short pulse equation by a Riemann-Hilbert approach

NASA Astrophysics Data System (ADS)

Boutet de Monvel, Anne; Shepelsky, Dmitry; Zielinski, Lech

2017-07-01

We develop a Riemann-Hilbert approach to the inverse scattering transform method for the short pulse (SP) equation u_{xt}=u+{1/6}(u^3)_{xx} with zero boundary conditions (as |x|→ ∞). This approach is directly applied to a Lax pair for the SP equation. It allows us to give a parametric representation of the solution to the Cauchy problem. This representation is then used for studying the longtime behavior of the solution as well as for retrieving the soliton solutions. Finally, the analysis of the longtime behavior allows us to formulate, in spectral terms, a sufficient condition for the wave breaking.

An Artificial Intelligence Approach for Modeling and Prediction of Water Diffusion Inside a Carbon Nanotube.

PubMed

Ahadian, Samad; Kawazoe, Yoshiyuki

2009-06-04

Modeling of water flow in carbon nanotubes is still a challenge for the classic models of fluid dynamics. In this investigation, an adaptive-network-based fuzzy inference system (ANFIS) is presented to solve this problem. The proposed ANFIS approach can construct an input-output mapping based on both human knowledge in the form of fuzzy if-then rules and stipulated input-output data pairs. Good performance of the designed ANFIS ensures its capability as a promising tool for modeling and prediction of fluid flow at nanoscale where the continuum models of fluid dynamics tend to break down.

Charge Fluctuations in the NdO1-xFxBiS2 Superconductors

NASA Astrophysics Data System (ADS)

Athauda, Anushika; Mizuguchi, Yoshikazu; Nagao, Masanori; Neuefeind, Joerg; Louca, Despina

2017-12-01

The local atomic structure of superconducting NdO1-xFxBiS2 (x = 0.2 and 0.4) is investigated using neutron diffraction and the pair density function analysis technique. In the non-superconducting x = 0.2 composition, ferrodistortive displacements of the pyramidal sulfur ions break the tetragonal symmetry and a superlattice structure emerges with peaks appearing at h + k odd reflections superimposed on the even reflections of the P4/nmm symmetry. In the superconducting x = 0.4 composition, similar ferrodistortive displacements are observed but with different magnitudes coupled with in-plane Bi distortions which are indicative of charge fluctuations.

KSC-04pd0490

NASA Image and Video Library

2004-03-12

KENNEDY SPACE CENTER, FLA. - Florida Gov. Jeb Bush (left) and Center Director Jim Kennedy enjoy a humorous break at the luncheon for the 2004 Florida Regional FIRST competition held at the University of Central Florida. Both are featured speakers. The event hosted 41 teams from Canada, Brazil, Great Britain and the United States. FIRST is a nonprofit organization, For Inspiration and Recognition of Science and Technology, that sponsors the event pitting gladiator robots against each other in an athletic-style competition. The FIRST robotics competition is designed to provide students with a hands-on, inside look at engineering and other professional careers, pairing high school students with engineer mentors and corporations.

KSC-04pd0504

NASA Image and Video Library

2004-03-12

KENNEDY SPACE CENTER, FLA. - The KSC-sponsored “Pink” team poses for a photo with Florida Gov. Jeb Bush (second from left) during a break at the 2004 Florida Regional FIRST competition, held at the University of Central Florida. The annual event is hosting 41 teams from Canada, Brazil, Great Britain and the United States. FIRST is a nonprofit organization, For Inspiration and Recognition of Science and Technology, that sponsors the event pitting robots against each other in an athletic-style competition. The FIRST robotics competition is designed to provide students with a hands-on, inside look at engineering and other professional careers, pairing high school students with engineer mentors and corporations.

DNA lability induced by nimustine and ramustine in rat glioma cells.

PubMed Central

Mineura, K; Fushimi, S; Itoh, Y; Kowada, M

1988-01-01

The DNA labile sites induced by two nitrosoureas, nimustine (ACNU) and ramustine (MCNU) synthesised in Japan, have been examined in highly reiterated DNA sequences of rat glioma cells. Reiterated fragments of 167 and 203 base pairs (bp), obtained after Hind III and Hae III restriction endonuclease digestion of rat glioma cells DNA, were used as target DNA sequences to determine the labile sites. In vitro reaction with ACNU and MCNU resulted in scission products corresponding to the locations of guanine. Subsequent piperidine hydrolysis produced more frequent breaks of the phosphodiester bonds at guanine positions, thus forming alkali-labile sites. Images PMID:3236017

Prevalence and predictors of deterioration of a trustful patient-provider relationship among HIV-infected persons treated with antiretroviral therapy.

PubMed

Préau, Marie; Leport, Catherine; Villes, Virginie; Michelet, Christian; Collin, Fidéline; Carrieri, Maria-Patrizia; Ragnaud, Jean-Marie; Taieb, Audrey; Raffi, François; Spire, Bruno

2008-04-01

We studied the evolution of the patient-provider relationship (PPR) in HIV-infected patients who reported trustful relationships at highly active antiretroviral therapy (HAART) treatment initiation. Psychosocial and clinical data were obtained from the French ANRS CO-8 cohort. Break of trust was defined using the question "How much do you trust the provider who usually treats you at this clinic?" Predictors of a possible break of trust during the 5 years after initiating treatment for those patients reporting a trustful PPR at month 0 were identified using a Cox model. During a total follow-up of 3,044 person-years, 68 (7%) patients reported having at least 1 break of trust in their PPR. Break of trust is independently associated with younger age, dissatisfaction with medical staff's explanations, cigarette smoking, and self-reported side effects and is independently inversely associated with severe HIV-related events and changes of treatment. A patient's break of trust in his provider is relatively infrequent. Accounting for the influence of immunologic status and psychosocial factors, self-reported side effects are shown to be detrimental to the PPR. Interestingly, clinical events and changes of treatment prevent a possible break of trust by reinforcing the provider's role. These results underline the importance of recognizing a patient's perceived secondary effects and developing appropriate care.

Differential effects of wakeful rest, music and video game playing on working memory performance in the n-back task.

PubMed

Kuschpel, Maxim S; Liu, Shuyan; Schad, Daniel J; Heinzel, Stephan; Heinz, Andreas; Rapp, Michael A

2015-01-01

The interruption of learning processes by breaks filled with diverse activities is common in everyday life. We investigated the effects of active computer gaming and passive relaxation (rest and music) breaks on working memory performance. Young adults were exposed to breaks involving (i) eyes-open resting, (ii) listening to music and (iii) playing the video game "Angry Birds" before performing the n-back working memory task. Based on linear mixed-effects modeling, we found that playing the "Angry Birds" video game during a short learning break led to a decline in task performance over the course of the task as compared to eyes-open resting and listening to music, although overall task performance was not impaired. This effect was associated with high levels of daily mind wandering and low self-reported ability to concentrate. These findings indicate that video games can negatively affect working memory performance over time when played in between learning tasks. We suggest further investigation of these effects because of their relevance to everyday activity.

Differential effects of wakeful rest, music and video game playing on working memory performance in the n-back task

PubMed Central

Kuschpel, Maxim S.; Liu, Shuyan; Schad, Daniel J.; Heinzel, Stephan; Heinz, Andreas; Rapp, Michael A.

2015-01-01

The interruption of learning processes by breaks filled with diverse activities is common in everyday life. We investigated the effects of active computer gaming and passive relaxation (rest and music) breaks on working memory performance. Young adults were exposed to breaks involving (i) eyes-open resting, (ii) listening to music and (iii) playing the video game “Angry Birds” before performing the n-back working memory task. Based on linear mixed-effects modeling, we found that playing the “Angry Birds” video game during a short learning break led to a decline in task performance over the course of the task as compared to eyes-open resting and listening to music, although overall task performance was not impaired. This effect was associated with high levels of daily mind wandering and low self-reported ability to concentrate. These findings indicate that video games can negatively affect working memory performance over time when played in between learning tasks. We suggest further investigation of these effects because of their relevance to everyday activity. PMID:26579055

Social stimuli enhance phencyclidine (PCP) self-administration in rhesus monkeys

PubMed Central

Newman, Jennifer L.; Perry, Jennifer L.; Carroll, Marilyn E.

2007-01-01

Environmental factors, including social interaction, can alter the effects of drugs of abuse on behavior. The present study was conducted to examine the effects of social stimuli on oral phencyclidine (PCP) self-administration by rhesus monkeys. Ten adult rhesus monkeys (M. mulatta) were housed side by side in modular cages that could be configured to provide visual, auditory, and olfactory stimuli provided by another monkey located in the other side of the paired unit. During the first experiment, monkeys self-administered PCP (0.25 mg/ml) and water under concurrent fixed ratio (FR) 16 schedules of reinforcement with either a solid or a grid (social) partition separating each pair of monkeys. In the second experiment, a PCP concentration-response relationship was determined under concurrent progressive ratio (PR) schedules of reinforcement under the solid and grid partition conditions. Under the concurrent FR 16 schedules, PCP and water self-administration was significantly higher during exposure to a cage mate through a grid partition than when a solid partition separated the monkeys. The relative reinforcing strength of PCP, as measured by PR break points, was greater during the grid partition condition compared to the solid partition condition indicated by an upward shift in the concentration-response curve. To determine whether the social stimuli provided by another monkey led to activation of the hypothalamic-pituitary-adrenal (HPA) axis, which may have evoked the increase of PCP self-administration during the grid partition condition, a third experiment was conducted to examine cortisol levels under the two housing conditions. A modest, but nonsignificant increase in cortisol levels was found upon switching from the solid to the grid partition condition. The results suggest that social stimulation among monkeys in adjoining cages leads to enhanced reinforcing strength of PCP. PMID:17560636

Sensitivity of Asteroid Impact Risk to Uncertainty in Asteroid Properties and Entry Parameters

NASA Astrophysics Data System (ADS)

Wheeler, Lorien; Mathias, Donovan; Dotson, Jessie L.; NASA Asteroid Threat Assessment Project

2017-10-01

A central challenge in assessing the threat posed by asteroids striking Earth is the large amount of uncertainty inherent throughout all aspects of the problem. Many asteroid properties are not well characterized and can range widely from strong, dense, monolithic irons to loosely bound, highly porous rubble piles. Even for an object of known properties, the specific entry velocity, angle, and impact location can swing the potential consequence from no damage to causing millions of casualties. Due to the extreme rarity of large asteroid strikes, there are also large uncertainties in how different types of asteroids will interact with the atmosphere during entry, how readily they may break up or ablate, and how much surface damage will be caused by the resulting airbursts or impacts.In this work, we use our Probabilistic Asteroid Impact Risk (PAIR) model to investigate the sensitivity of asteroid impact damage to uncertainties in key asteroid properties, entry parameters, or modeling assumptions. The PAIR model combines physics-based analytic models of asteroid entry and damage in a probabilistic Monte Carlo framework to assess the risk posed by a wide range of potential impacts. The model samples from uncertainty distributions of asteroid properties and entry parameters to generate millions of specific impact cases, and models the atmospheric entry and damage for each case, including blast overpressure, thermal radiation, tsunami inundation, and global effects. To assess the risk sensitivity, we alternately fix and vary the different input parameters and compare the effect on the resulting range of damage produced. The goal of these studies is to help guide future efforts in asteroid characterization and model refinement by determining which properties most significantly affect the potential risk.

How Does Definition of Minimum Break Length Affect Objective Measures of Sitting Outcomes Among Office Workers?

PubMed

Kloster, Stine; Danquah, Ida Høgstedt; Holtermann, Andreas; Aadahl, Mette; Tolstrup, Janne Schurmann

2017-01-01

Harmful health effects associated with sedentary behavior may be attenuated by breaking up long periods of sitting by standing or walking. However, studies assess interruptions in sitting time differently, making comparisons between studies difficult. It has not previously been described how the definition of minimum break duration affects sitting outcomes. Therefore, the aim was to address how definitions of break length affect total sitting time, number of sit-to-stand transitions, prolonged sitting periods and time accumulated in prolonged sitting periods among office workers. Data were collected from 317 office workers. Thigh position was assessed with an ActiGraph GT3X+ fixed on the right thigh. Data were exported with varying bout length of breaks. Afterward, sitting outcomes were calculated for the respective break lengths. Absolute numbers of sit-to-stand transitions decreased, and number of prolonged sitting periods and total time accumulated in prolonged sitting periods increased, with increasing minimum break length. Total sitting time was not influenced by varying break length. The definition of minimum break length influenced the sitting outcomes with the exception of total sitting time. A standard definition of break length is needed for comparison and interpretation of studies in the evolving research field of sedentary behavior.

78 FR 32700 - Hours of Service of Drivers: U.S. Department of Energy (DOE); Application for Exemption

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-31

...) an exemption from the minimum 30-minute rest break provision of the Agency's hours-of-service (HOS... minutes or more of ``attendance time'' to meet the HOS rest break requirements providing they do not perform any other work during the break. DATES: This exemption is effective from July 1, 2013 through June...

Parameterization of planetary wave breaking in the middle atmosphere

NASA Technical Reports Server (NTRS)

Garcia, Rolando R.

1991-01-01

A parameterization of planetary wave breaking in the middle atmosphere has been developed and tested in a numerical model which includes governing equations for a single wave and the zonal-mean state. The parameterization is based on the assumption that wave breaking represents a steady-state equilibrium between the flux of wave activity and its dissipation by nonlinear processes, and that the latter can be represented as linear damping of the primary wave. With this and the additional assumption that the effect of breaking is to prevent further amplitude growth, the required dissipation rate is readily obtained from the steady-state equation for wave activity; diffusivity coefficients then follow from the dissipation rate. The assumptions made in the derivation are equivalent to those commonly used in parameterizations for gravity wave breaking, but the formulation in terms of wave activity helps highlight the central role of the wave group velocity in determining the dissipation rate. Comparison of model results with nonlinear calculations of wave breaking and with diagnostic determinations of stratospheric diffusion coefficients reveals remarkably good agreement, and suggests that the parameterization could be useful for simulating inexpensively, but realistically, the effects of planetary wave transport.

The Working of Circuit Breakers Within Percolation Models for Financial Markets

NASA Astrophysics Data System (ADS)

Ehrenstein, Gudrun; Westerhoff, Frank

We use a modified Cont-Bouchaud model to explore the effectiveness of trading breaks. The modifications include that the trading activity of the market participants depends positively on historical volatility and that the orders of the agents are conditioned on the observed mispricing. Trading breaks, also called circuit breakers, interrupt the trading process when prices are about to exceed a pre-specified limit. We find that trading breaks are a useful instrument to stabilize financial markets. In particular, trading breaks may reduce price volatility and deviations from fundamentals.

Quark Propagator with electroweak interactions in the Dyson-Schwinger approach

NASA Astrophysics Data System (ADS)

Mian, Walid Ahmed; Maas, Axel

2017-03-01

Motivated by the non-negligible dynamical backcoupling of the electroweak interactions with the strong interaction during neutron star mergers, we study the effects of the explicit breaking of C, P and flavor symmetry on the strong sector. The quark propagator is the simplest object which encodes the consequences of these breakings. To asses the impact, we study the influence of especially parity violation on the propagator for various masses. For this purpose the functional methods in form of Dyson-Schwinger-Equations are employed. We find that explicit isospin breaking leads to a qualitative change of behavior even for a slight explicit breaking, which is in contrast to the expectations from perturbation theory. Our results thus suggest that non-perturbative backcoupling effects could be larger than expected.

Laser Marking of the Meridian of Retinal Breaks at the Ora: A Novel Technique for Pneumatic Retinopexy.

PubMed

Yan, Peng; Minaker, Samuel; Mandelcorn, Efrem D

2016-06-01

Localization of retinal breaks in rhegmatogenous retinal detachment (RRD) after pneumatic retinopexy (PR) can be challenging once the retina is reattached. Laser can be applied to the pigmented and always-attached ora serrata in the meridian of the retinal breaks prior to pneumatic retinopexy, resulting in subsequent rapid localization of the breaks even in the presence of a gas bubble or media opacity. Ten cases of indirect laser photocoagulation marking at the ora prior to intraocular gas injection in PR for RRD. Subsequent laser retinopexy was completed 48 hours after utilizing the landmarks at the ora to localize the reattached retinal breaks. In all 10 cases, laser photocoagulation marking was easily applied to the ora in the meridian of the retinal breaks prior to gas injection with no complications. The retinal breaks were subsequently identified 48 hours after gas injection. Laser marking of the ora prior to pneumatic retinopexy is a rapid and effective way to localize the re-attached retina breaks. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:570-572.]. Copyright 2016, SLACK Incorporated.

An alternative mechanism for radioprotection by dimethyl sulfoxide; possible facilitation of DNA double-strand break repair.

PubMed

Kashino, Genro; Liu, Yong; Suzuki, Minoru; Masunaga, Shin-ichiro; Kinashi, Yuko; Ono, Koji; Tano, Keizo; Watanabe, Masami

2010-01-01

The radioprotective effects of dimethyl sulfoxide (DMSO) have been known for many years, and the suppression of hydroxyl (OH) radicals induced by ionizing radiation has been thought to be the main cause of this effect. However, the DMSO concentration used was very high, and might be toxic, in earlier studies. In the present study, we administered a lower, non-toxic concentration (0.5%, i.e., 64 mM) of DMSO before irradiation and examined its radioprotective effects. Colony formation assay and micronucleus assay showed significant radioprotective effects in CHO, but not in xrs5, which is defective in the repair function of DNA double-strand breaks. The levels of phosphorylated H2AX and the formation of 53BP1 foci 15 minutes after irradiation, which might reflect initial DNA double-strand breaks, in DMSO-treated CHO cells were similar to those in non-treated cells, suggesting that the radioprotective effects were not attributable to the suppression of general indirect action in the lower concentration of DMSO. On the other hand, 2 hours after irradiation, the average number of 53BP1 foci, which might reflect residual DNA double-strand breaks, was significantly decreased in DMSO-treated CHO cells compared to non-treated cells. The results indicated that low concentration of DMSO exerts radioprotective effects through the facilitation of DNA double-strand break repair rather than through the suppression of indirect action.

Determinants of the effectiveness of fast break actions in elite and sub-elite Italian men's basketball games.

PubMed

Conte, D; Favero, T G; Niederhausen, M; Capranica, L; Tessitore, A

2017-06-01

The aim of this study was to examine the determinants of successful and unsuccessful fast-break (FB) actions in elite and sub-elite basketball games. Fifteen 1 st -division (elite) and fifteen 3 rd -division (sub-elite) Italian men's championship games were analysed across two seasons (2012/2013 and 2013/2014). A binary logistic regression analysis was performed, and the fast-break outcome (successful vs. unsuccessful) was adopted as the dependent variable separately in both elite and sub-elite games. FB execution (initiation, advance and completion phases), typology (primary and secondary break) and the number of players involved (equal number or superiority) were used as independent variables. The results showed that the rate of success of FB actions was 63.5% and 59.7% in elite and sub-elite games, respectively. Moreover, successful FBs were more likely to be completed in the lane in relation to unsuccessful ones in both elite and sub-elite games (p<0.05). Finally, descriptive statistics showed that both elite and sub-elite teams executed FBs similarly. This study highlighted that completion zone was the only predictor of a successful fast break in basketball, while the typology and number of players involved did not predict fast break effectiveness. Moreover, elite and sub-elite teams executed fast break actions similarly. These findings might be useful for basketball coaches to optimize the training of FB actions.

Effects of (-)-epigallocatechin gallate (EGCG) on DNA strand breaks as evaluated by single-cell gel electrophoresis (SCG) in human lymphocytes.

PubMed

Yuquan, L; Takeshita, T; Morimoto, K

2001-01-01

(-)-Epigallocatechin gallate (EGCG), a catechin polyphenol component, is the main ingredient of green tea extract. Although the anti-carcinogenic and cancer inhibitory effects of EGCG have been widely reported, its genotoxicity is not clear and seldom reported. In this study, we examined the effects of EGCG on DNA strand breaks in the isolated lymphocytes and whole blood lymphocytes obtained from two smoking subjects and a nonsmoking healthy subject using a single cell gel electrophoresis (SCG) assay. The results showed that after 2 hrs of treating the isolated lymphocytes from the smokers, EGCG induced a significant, increase in DNA strand breaks at concentrations from 2.5×10(-5) M to 2.0×10(-4) M, while after 2 hrs of treating the whole blood obtained from the same smokers, EGCG suppressed the DNA strand breaks in the lymphocytes at concentrations of 1.0×10(-4) M and 2.0×10(-4) M. A similar suppressive result was also shown in the whole blood lymphocytes from the nonsmoker at nearly the same concentrations, while at concentrations of 1.0×10(-3) M or 2.0×10(-3) M, EGCG induced a significant increase in DNA strand breaks in the whole blood lymphocytes from the nonsmoker. This result suggests that EGCG is not only inhibitory against DNA strand breaks in whole blood, but also genotoxic to the isolated or whole blood lymphocytes at high concentrations. Thus, more research is needed to comprehensively assess the effects of EGCG on genetic materials.

On the soft supersymmetry-breaking parameters in gauge-mediated models

NASA Astrophysics Data System (ADS)

Wagner, C. E. M.

1998-09-01

Gauge mediation of supersymmetry breaking in the observable sector is an attractive idea, which naturally alleviates the flavor changing neutral current problem of supersymmetric theories. Quite generally, however, the number and quantum number of the messengers are not known; nor is their characteristic mass scale determined by the theory. Using the recently proposed method to extract supersymmetry-breaking parameters from wave-function renormalization, we derived general formulae for the soft supersymmetry-breaking parameters in the observable sector, valid in the small and moderate tan β regimes, for the case of split messengers. The full leading-order effects of top Yukawa and gauge couplings on the soft supersymmetry-breaking parameters are included. We give a simple interpretation of the general formulae in terms of the renormalization group evolution of the soft supersymmetry-breaking parameters. As a by-product of this analysis, the one-loop renormalization group evolution of the soft supersymmetry-breaking parameters is obtained for arbitrary boundary conditions of the scalar and gaugino mass parameters at high energies.

Can phenological models predict tree phenology accurately in the future? The unrevealed hurdle of endodormancy break.

PubMed

Chuine, Isabelle; Bonhomme, Marc; Legave, Jean-Michel; García de Cortázar-Atauri, Iñaki; Charrier, Guillaume; Lacointe, André; Améglio, Thierry

2016-10-01

The onset of the growing season of trees has been earlier by 2.3 days per decade during the last 40 years in temperate Europe because of global warming. The effect of temperature on plant phenology is, however, not linear because temperature has a dual effect on bud development. On one hand, low temperatures are necessary to break bud endodormancy, and, on the other hand, higher temperatures are necessary to promote bud cell growth afterward. Different process-based models have been developed in the last decades to predict the date of budbreak of woody species. They predict that global warming should delay or compromise endodormancy break at the species equatorward range limits leading to a delay or even impossibility to flower or set new leaves. These models are classically parameterized with flowering or budbreak dates only, with no information on the endodormancy break date because this information is very scarce. Here, we evaluated the efficiency of a set of phenological models to accurately predict the endodormancy break dates of three fruit trees. Our results show that models calibrated solely with budbreak dates usually do not accurately predict the endodormancy break date. Providing endodormancy break date for the model parameterization results in much more accurate prediction of this latter, with, however, a higher error than that on budbreak dates. Most importantly, we show that models not calibrated with endodormancy break dates can generate large discrepancies in forecasted budbreak dates when using climate scenarios as compared to models calibrated with endodormancy break dates. This discrepancy increases with mean annual temperature and is therefore the strongest after 2050 in the southernmost regions. Our results claim for the urgent need of massive measurements of endodormancy break dates in forest and fruit trees to yield more robust projections of phenological changes in a near future. © 2016 John Wiley & Sons Ltd.

Sensitivity of Middle Atmospheric Temperature and Circulation in the UIUC Mesosphere-Stratosphere-Troposphere GCM to the Treatment of Subgrid-Scale Gravity-Wave Breaking

NASA Technical Reports Server (NTRS)

Yang, Fanglin; Schlesinger, Michael E.; Andranova, Natasha; Zubov, Vladimir A.; Rozanov, Eugene V.; Callis, Lin B.

2003-01-01

The sensitivity of the middle atmospheric temperature and circulation to the treatment of mean- flow forcing due to breaking gravity waves was investigated using the University of Illinois at Urbana-Champaign 40-layer Mesosphere-Stratosphere-Troposphere General Circulation Model (MST-GCM). Three GCM experiments were performed. The gravity-wave forcing was represented first by Rayleigh friction, and then by the Alexander and Dunkerton (AD) parameterization with weak and strong breaking effects of gravity waves. In all experiments, the Palmer et al. parameterization was included to treat the breaking of topographic gravity waves in the troposphere and lower stratosphere. Overall, the experiment with the strong breaking effect simulates best the middle atmospheric temperature and circulation. With Rayleigh friction and the weak breaking effect, a large warm bias of up to 60 C was found in the summer upper mesosphere and lower thermosphere. This warm bias was linked to the inability of the GCM to simulate the reversal of the zonal winds from easterly to westerly crossing the mesopause in the summer hemisphere. With the strong breaking effect, the GCM was able to simulate this reversal, and essentially eliminated the warm bias. This improvement was the result of a much stronger meridional transport circulation that possesses a strong vertical ascending branch in the summer upper mesosphere, and hence large adiabatic cooling. Budget analysis indicates that 'in the middle atmosphere the forces that act to maintain a steady zonal-mean zonal wind are primarily those associated with the meridional transport circulation and breaking gravity waves. Contributions from the interaction of the model-resolved eddies with the mean flow are small. To obtain a transport circulation in the mesosphere of the UIUC MST-GCM that is strong enough to produce the observed cold summer mesopause, gravity-wave forcing larger than 100 m/s/day in magnitude is required near the summer mesopause. In the tropics, only with the AD parameterization can the model produce realistic semiannual oscillations.

Can phenological models predict tree phenology accurately under climate change conditions?

NASA Astrophysics Data System (ADS)

Chuine, Isabelle; Bonhomme, Marc; Legave, Jean Michel; García de Cortázar-Atauri, Inaki; Charrier, Guillaume; Lacointe, André; Améglio, Thierry

2014-05-01

The onset of the growing season of trees has been globally earlier by 2.3 days/decade during the last 50 years because of global warming and this trend is predicted to continue according to climate forecast. The effect of temperature on plant phenology is however not linear because temperature has a dual effect on bud development. On one hand, low temperatures are necessary to break bud dormancy, and on the other hand higher temperatures are necessary to promote bud cells growth afterwards. Increasing phenological changes in temperate woody species have strong impacts on forest trees distribution and productivity, as well as crops cultivation areas. Accurate predictions of trees phenology are therefore a prerequisite to understand and foresee the impacts of climate change on forests and agrosystems. Different process-based models have been developed in the last two decades to predict the date of budburst or flowering of woody species. They are two main families: (1) one-phase models which consider only the ecodormancy phase and make the assumption that endodormancy is always broken before adequate climatic conditions for cell growth occur; and (2) two-phase models which consider both the endodormancy and ecodormancy phases and predict a date of dormancy break which varies from year to year. So far, one-phase models have been able to predict accurately tree bud break and flowering under historical climate. However, because they do not consider what happens prior to ecodormancy, and especially the possible negative effect of winter temperature warming on dormancy break, it seems unlikely that they can provide accurate predictions in future climate conditions. It is indeed well known that a lack of low temperature results in abnormal pattern of bud break and development in temperate fruit trees. An accurate modelling of the dormancy break date has thus become a major issue in phenology modelling. Two-phases phenological models predict that global warming should delay or compromise dormancy break at the species equatorward range limits leading to a delay or even impossibility to flower or set new leaves. These models are classically parameterized with flowering or budburst dates only, with no information on the dormancy break date because this information is very scarce. We evaluated the efficiency of a set of process-based phenological models to accurately predict the dormancy break dates of four fruit trees. Our results show that models calibrated solely with flowering or budburst dates do not accurately predict the dormancy break date. Providing dormancy break date for the model parameterization results in much more accurate simulation of this latter, with however a higher error than that on flowering or bud break dates. But most importantly, we show also that models not calibrated with dormancy break dates can generate significant differences in forecasted flowering or bud break dates when using climate scenarios. Our results claim for the urgent need of massive measurements of dormancy break dates in forest and fruit trees to yield more robust projections of phenological changes in a near future.

Dyonic Flux Tube Structure of Nonperturbative QCD Vacuum

NASA Astrophysics Data System (ADS)

Chandola, H. C.; Pandey, H. C.

We study the flux tube structure of the nonperturbative QCD vacuum in terms of its dyonic excitations by using an infrared effective Lagrangian and show that the dyonic condensation of QCD vacuum has a close connection with the process of color confinement. Using the fiber bundle formulation of QCD, the magnetic symmetry condition is presented in a gauge covariant form and the gauge potential has been constructed in terms of the magnetic vectors on global sections. The dynamical breaking of the magnetic symmetry has been shown to lead the dyonic condensation of QCD vacuum in the infrared energy sector. Deriving the asymptotic solutions of the field equations in the dynamically broken phase, the dyonic flux tube structure of QCD vacuum is explored which has been shown to lead the confinement parameters in terms of the vector and scalar mass modes of the condensed vacuum. Evaluating the charge quantum numbers and energy associated with the dyonic flux tube solutions, the effect of electric excitation of monopole is analyzed using the Regge slope parameter (as an input parameter) and an enhancement in the dyonic pair correlations and the confining properties of QCD vacuum in its dyonically condensed mode has been demonstrated.

Theoretical study of impurity effects in iron-based superconductors

NASA Astrophysics Data System (ADS)

Navarro Gastiasoro, Maria; Hirschfeld, Peter; Andersen, Brian

2013-03-01

Several open questions remain unanswered for the iron-based superconductors (FeSC), including the importance of electronic correlations and the symmetry of the superconducting order parameter. Motivated by recent STM experiments which show a fascinating variety of resonant defect states in FeSC, we adopt a realistic five-band model including electronic Coulomb correlations to study local effects of disorder in the FeSC. In order to minimize the number of free parameters, we use the pairing interactions obtained from spin-fluctuation exchange to determine the homogeneous superconducting state. The ability of local impurity potentials to induce resonant states depends on their scattering strength Vimp; in addition, for appropriate Vimp, such states are associated with local orbital- and magnetic order. We investigate the density of states near such impurities and show how tunneling experiments may be used to probe local induced order. In the SDW phase, we show how C2 symmetry-breaking dimers are naturally formed around impurities which also form cigar-like (pi,pi) structures embedded in the (pi,0) magnetic bulk phase. Such electronic dimers have been shown to be candidates for explaining the so-called nematogens observed previously by QPI in Co-doped CaFe2As2.

Chiral phases of superfluid 3He in an anisotropic medium

NASA Astrophysics Data System (ADS)

Sauls, J. A.

2013-12-01

Recent advances in the fabrication and characterization of anisotropic silica aerogels with exceptional homogeneity provide new insight into the nature of unconventional pairing in disordered anisotropic media. I report theoretical analysis and predictions for the equilibrium phases of superfluid 3He infused into a low-density, homogeneous uniaxial aerogel. Ginzburg-Landau (GL) theory for a class of equal-spin-pairing (ESP) states in a medium with uniaxial anisotropy is developed and used to analyze recent experiments on uniaxially strained aerogels. For 3He in an axially “stretched” aerogel, GL theory predicts a transition from normal liquid into a chiral Anderson-Morel phase at Tc1 in which the chirality axis l̂ is aligned along the strain axis. This orbitally aligned state is protected from random fluctuations in the anisotropy direction, has a positive nuclear magnetic resonance (NMR) frequency shift, a sharp NMR resonance line, and is identified with the high-temperature ESP-1 phase of superfluid 3He in axially stretched aerogel. A second transition into a biaxial phase is predicted to onset at a slightly lower temperature Tc2

Operator-sum representation for bosonic Gaussian channels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ivan, J. Solomon; Sabapathy, Krishna Kumar; Simon, R.

2011-10-15

Operator-sum or Kraus representations for single-mode bosonic Gaussian channels are developed, and several of their consequences explored. The fact that the two-mode metaplectic operators acting as unitary purification of these channels do not, in their canonical form, mix the position and momentum variables is exploited to present a procedure which applies uniformly to all families in the Holevo classification. In this procedure the Kraus operators of every quantum-limited Gaussian channel can be simply read off from the matrix elements of a corresponding metaplectic operator. Kraus operators are employed to bring out, in the Fock basis, the manner in which themore » antilinear, unphysical matrix transposition map when accompanied by injection of a threshold classical noise becomes a physical channel, denoted D({kappa}) in the Holevo classification. The matrix transposition channels D({kappa}), D({kappa}{sup -1}) turn out to be a dual pair in the sense that their Kraus operators are related by the adjoint operation. The amplifier channel with amplification factor {kappa} and the beam-splitter channel with attenuation factor {kappa}{sup -1} turn out to be mutually dual in the same sense. The action of the quantum-limited attenuator and amplifier channels as simply scaling maps on suitable quasiprobabilities in phase space is examined in the Kraus picture. Consideration of cumulants is used to examine the issue of fixed points. The semigroup property of the amplifier and attenuator families leads in both cases to a Zeno-like effect arising as a consequence of interrupted evolution. In the cases of entanglement-breaking channels a description in terms of rank 1 Kraus operators is shown to emerge quite simply. In contradistinction, it is shown that there is not even one finite rank operator in the entire linear span of Kraus operators of the quantum-limited amplifier or attenuator families, an assertion far stronger than the statement that these are not entanglement breaking channels. A characterization of extremality in terms of Kraus operators, originally due to Choi, is employed to show that all quantum-limited Gaussian channels are extremal. The fact that almost every noisy Gaussian channel can be realized as a product of a pair of quantum-limited channels is used to construct a discrete set of linearly independent Kraus operators for these noisy Gaussian channels, including the classical noise channel, and these Kraus operators have a particularly simple structure.« less

Assessing the effect of a fuel break network to reduce burnt area and wildfire risk transmission

Treesearch

Tiago M. Oliveira; Ana M. G. Barros; Alan A. Ager; Paulo M. Fernandes

2016-01-01

Wildfires pose complex challenges to policymakers and fire agencies. Fuel break networks and area-wide fuel treatments are risk-management options to reduce losses from large fires. Two fuel management scenarios covering 3% of the fire-prone Algarve region of Portugal and differing in the intensity of treatment in 120-m wide fuel breaks were examined and compared with...