Breaking the temporal resolution limit by superoscillating optical beats
Eliezer, Yaniv; Lobachinsky, Lilya; Froim, Sahar; Bahabad, Alon
2016-01-01
Band-limited functions can oscillate locally at an arbitrarily fast rate through an interference phenomenon known as superoscillations. Using an optical pulse with a superoscillatory envelope we experimentally break the temporal Fourier-transform limit having a temporal feature which is approximately three times shorter than the duration of a transform-limited Gaussian pulse having a comparable bandwidth while maintaining $29.5\\%$ visibility. Numerical simulations demonstrate the ability of such signals to achieve temporal super-resolution.
Modular structure of brain functional networks: breaking the resolution limit by Surprise
Nicolini, Carlo; Bifone, Angelo
2016-01-01
The modular organization of brain networks has been widely investigated using graph theoretical approaches. Recently, it has been demonstrated that graph partitioning methods based on the maximization of global fitness functions, like Newman’s Modularity, suffer from a resolution limit, as they fail to detect modules that are smaller than a scale determined by the size of the entire network. Here we explore the effects of this limitation on the study of brain connectivity networks. We demonstrate that the resolution limit prevents detection of important details of the brain modular structure, thus hampering the ability to appreciate differences between networks and to assess the topological roles of nodes. We show that Surprise, a recently proposed fitness function based on probability theory, does not suffer from these limitations. Surprise maximization in brain co-activation and functional connectivity resting state networks reveals the presence of a rich structure of heterogeneously distributed modules, and differences in networks’ partitions that are undetectable by resolution-limited methods. Moreover, Surprise leads to a more accurate identification of the network’s connector hubs, the elements that integrate the brain modules into a cohesive structure.
Min Gu; Hong Kang; Xiangping Li
2014-01-01
Although fiber-optical two-photon endoscopy has been recognized as a potential high-resolution diagnostic and therapeutic procedure in vivo, its resolution is limited by the optical diffraction nature to a few micrometers due to the low numerical aperture of an endoscopic objective. On the other hand, stimulated emission depletion (STED) achieved by a circularly-polarized vortex beam has been used to break the diffraction-limited resolution barrier in a bulky microscope. It has been a challen...
Gu, Min; Kang, Hong; Li, Xiangping
2014-01-01
Although fiber-optical two-photon endoscopy has been recognized as a potential high-resolution diagnostic and therapeutic procedure in vivo, its resolution is limited by the optical diffraction nature to a few micrometers due to the low numerical aperture of an endoscopic objective. On the other hand, stimulated emission depletion (STED) achieved by a circularly-polarized vortex beam has been used to break the diffraction-limited resolution barrier in a bulky microscope. It has been a challenge to apply the STED principle to a fiber-optical two-photon endoscope as a circular polarization state cannot be maintained due to the birefringence of a fiber. Here, we demonstrate the first fiber-optical STED two-photon endoscope using an azimuthally-polarized beam directly generated from a double-clad fiber. As such, the diffraction-limited resolution barrier of fiber-optical two-photon endoscopy can be broken by a factor of three. Our new accomplishment has paved a robust way for high-resolution in vivo biomedical studies. PMID:24406685
Macner, Ashley; Steen, Paul
2011-11-01
Wet adhesion by liquid bridges in large arrays shows promise for use in lightweight, controllable on-demand devices. Applications include grab/release of wafer substrates, transport of micron-sized tiles for use in 3D printing and micro-dosing of personalized pharmaceutical drugs. By wetting and spreading, a drop can form a bridge and thereby ``grab'' a nearby solid substrate. By volume decrease or extension, the bridge can break. The breaking limit corresponds to bridge instability which can be predicted, knowing the static mechanical response of the bridge. Mechanical behaviors include force-volume (FV), pressure-volume (pV) and force-length (FL) responses. Instability crucially depends on the mode of failure - failure under constant-force or constant length are typical cases. We study single bridge equilibria for their breaking limits. FV diagrams for the pin-pin equal and pin-pin unequal radii boundary conditions for different bridge heights are measured in the laboratory. The FL response in the case of pin-pin equal radii is also measured. Results are compared to predictions of static theory. Static results are then used to compare to dynamical sequences where volume is driven quasistatically by syringe or an electro-osmotic pump. As the breaking limit is approached, the shape deformation accelerates leading to non-equilibrium shapes not captured by the static analysis.
Calculation of the limiting CESSAR Feedwater Line-Break and Steam Line-Break transients
International Nuclear Information System (INIS)
Argonne National Laboratory (ANL), under contract to the Nuclear Regulatory Commission, performed audit calculations of the limiting Feedwater Line Break (FLB) and Steam Line Break (SLB) transients presented in the CESSAR FSAR. The results of the FLB and SLB calculations are discussed
The Limits of Visual Resolution
Rossi, Ethan Andrew
2009-01-01
Visual resolution, the ability to see fine spatial detail, emerges from the capacities of both the eye and the brain. A great deal of insight into the anatomical and physiological basis of human visual resolution has been gained since Helmholtz first proposed his sampling theory of visual resolution. Anatomical, physiological and psychophysical investigations have revealed in great detail the properties of the biological structures underlying visual resolution and identified many of the opt...
Energy resolution limits of amplified scintillators
International Nuclear Information System (INIS)
In this paper, we analyze the potential improvement in the statistical limit to the energy resolution of a scintillator using a scintillator amplification technique. The work excludes potentially complicating factors, such as non-linearity in light yield, since these factors are dependent upon the particular choice of detector materials. The results show that energy resolutions typical of semiconductors are technically feasible for scintillators. In the example presented, introducing scintillation multiplication improved the energy resolution limit from a few percent to below 1%.
Resolution limits of ultrafast ultrasound localization microscopy
Desailly, Yann; Pierre, Juliette; Couture, Olivier; Tanter, Mickael
2015-11-01
As in other imaging methods based on waves, the resolution of ultrasound imaging is limited by the wavelength. However, the diffraction-limit can be overcome by super-localizing single events from isolated sources. In recent years, we developed plane-wave ultrasound allowing frame rates up to 20 000 fps. Ultrafast processes such as rapid movement or disruption of ultrasound contrast agents (UCA) can thus be monitored, providing us with distinct punctual sources that could be localized beyond the diffraction limit. We previously showed experimentally that resolutions beyond λ/10 can be reached in ultrafast ultrasound localization microscopy (uULM) using a 128 transducer matrix in reception. Higher resolutions are theoretically achievable and the aim of this study is to predict the maximum resolution in uULM with respect to acquisition parameters (frequency, transducer geometry, sampling electronics). The accuracy of uULM is the error on the localization of a bubble, considered a point-source in a homogeneous medium. The proposed model consists in two steps: determining the timing accuracy of the microbubble echo in radiofrequency data, then transferring this time accuracy into spatial accuracy. The simplified model predicts a maximum resolution of 40 μm for a 1.75 MHz transducer matrix composed of two rows of 64 elements. Experimental confirmation of the model was performed by flowing microbubbles within a 60 μm microfluidic channel and localizing their blinking under ultrafast imaging (500 Hz frame rate). The experimental resolution, determined as the standard deviation in the positioning of the microbubbles, was predicted within 6 μm (13%) of the theoretical values and followed the analytical relationship with respect to the number of elements and depth. Understanding the underlying physical principles determining the resolution of superlocalization will allow the optimization of the imaging setup for each organ. Ultimately, accuracies better than the size
Resolution limits for wave equation imaging
Huang, Yunsong
2014-08-01
Formulas are derived for the resolution limits of migration-data kernels associated with diving waves, primary reflections, diffractions, and multiple reflections. They are applicable to images formed by reverse time migration (RTM), least squares migration (LSM), and full waveform inversion (FWI), and suggest a multiscale approach to iterative FWI based on multiscale physics. That is, at the early stages of the inversion, events that only generate low-wavenumber resolution should be emphasized relative to the high-wavenumber resolution events. As the iterations proceed, the higher-resolution events should be emphasized. The formulas also suggest that inverting multiples can provide some low- and intermediate-wavenumber components of the velocity model not available in the primaries. Finally, diffractions can provide twice or better the resolution than specular reflections for comparable depths of the reflector and diffractor. The width of the diffraction-transmission wavepath is approximately λ at the diffractor location for the diffraction-transmission wavepath. © 2014 Elsevier B.V.
Influence of breaking waves on the oceanologic Lidar resolution
Luchinin, Alexander G.
2014-10-01
Influence of breaking waves and whitecaps on characteristics of echo signal of airborne bathymetric lidar is investigated at strong winds. The model of echo signal, considering following factors is advanced: finite height of waves, random refraction of light by sea surface, free from foam and breaking waves, diffuse scattering of light on both sites of a surface with whitecaps on crests of waves. The account of finite height of waves is represented especially important at strong winds as in these conditions influence of whitecaps can appear essential. The relations are received, allowing estimating average delay and broadening of the signal. It is shown that whitecaps weak influence on average characteristics at wind speeds to 20 m/s. This influence appears essential in that case when measurement of a delay and, accordingly, definition of depth of a bottom or reflecting object is made by times of the first arrival of a backscattering signal from water.
Yue, Liyang; Yan, Bing; Wang, Zengbo
2016-04-01
We designed a novel cylindrical metalens assembled by hexagonally arranged close-contact nanofibers. A near-field focusing nanojet with a full-width at half-maximum (FWHM) waist, 26.7% smaller than the Abbe diffraction limit for 532 nm wavelength light, is observed at the bottom of a 1600 nm diameter cylindrical metalens assembled by 160 nm diameter nanofibers irradiated by a plane wave from the top. Using differently sized nanofibers as building blocks to assemble the metalens, the waist size of the produced photonic nanojet in the near-field zone and the lateral resolution of the focus can be flexibly adjusted, simultaneously breaking the diffraction limit. PMID:27192230
Resolution limit of a phononic crystal superlens
Robillard, J.-F.; Bucay, J.; Deymier, P. A.; Shelke, A.; Muralidharan, K.; Merheb, B.; Vasseur, J. O.; Sukhovich, A.; Page, J. H.
2011-06-01
We report on the subwavelength imaging capabilities of a phononic crystal (PC) flat lens consisting of a triangular array of steel cylinders in methanol, all surrounded by water. The image resolution of the PC flat lens beats the Rayleigh diffraction limit because bound modes in the lens can be excited by evanescent waves emitted by the source. These are modes that only propagate in the direction parallel to the water-lens interface. These modes resonantly amplify evanescent waves that contribute to the reconstruction of an image. By employing the finite difference time domain method and ultrasonic experiments, we also explore the effect on the image resolution and focal point on various structural and operational parameters, such as source frequency, geometry of the lens, source position, and time. The mechanisms by which these factors affect resolution are discussed in terms of the competition between the contribution of propagative modes to focusing and the ability of the source to excite bound modes of the PC lens.
Electron-optic limitations on image resolution
Engstrom, R. W.
1973-01-01
Various approaches are considered to the solution of the electron-optical problem of designing an image tube configuration. Emphasis is placed on the method of computer design, and an illustration is given in which the technique is used in the design of an 80-mm image tube with a zoom capability of 3:1. The solutions are discussed to such problems as image distortion, magnification, and electron bundles striking the zoom electrode. Three types of an electron-optical configuration are examined for the electron-optic limitations to resolution: (1) the proximity image tube, (2) the magnetic-type image tube having uniform electric and magnetic fields, and (3) the electrostatic-type image tube such as the 80-mm zoom tube.
Breaking Quantum and Thermal Limits on Precision Measurements
Thompson, James K.
2016-05-01
I will give an overview of our efforts to use correlations and entanglement between many atoms to overcome quantum and thermal limits on precision measurements. In the first portion of my talk, I will present a path toward a 10000 times reduced sensitivity to the thermal mirror motion that limits the linewidth of today's best lasers. By utilizing narrow atomic transitions, the laser's phase information is primarily stored in the atomic gain medium rather than in the vibration-sensitive cavity field. To this end, I will present the first observation of lasing based on the mHz linewidth optical-clock transition in a laser-cooled ensemble of strontium atoms. In the second portion of my talk, I will describe how we use collective measurements to surpass the standard quantum limit on phase estimation 1 /√{ N} for N unentangled atoms. We achieve a directly observed reduction in phase variance relative to the standard quantum limit of as much as 17.7(6) dB. Supported by DARPA QuASAR, NIST, ARO, and NSF PFC. This material is based upon work supported by the National Science Foundation under Grant Number 1125844 Physics Frontier Center.
Resolution, coverage, and geometry beyond traditional limits
Energy Technology Data Exchange (ETDEWEB)
Ronen, Shuki; Ferber, Ralf
1998-12-31
The presentation relates to the optimization of the image of seismic data and improved resolution and coverage of acquired data. Non traditional processing methods such as inversion to zero offset (IZO) are used. To realize the potential of saving acquisition cost by reducing in-fill and to plan resolution improvement by processing, geometry QC methods such as DMO Dip Coverage Spectrum (DDCS) and Bull`s Eyes Analysis are used. The DDCS is a 2-D spectrum whose entries consist of the DMO (Dip Move Out) coverage for a particular reflector specified by it`s true time dip and reflector normal strike. The Bull`s Eyes Analysis relies on real time processing of synthetic data generated with the real geometry. 4 refs., 6 figs.
Liu, Yuan; Tu, Haohua; Boppart, Stephen A
2012-06-15
Wave-breaking often occurs when a short intense optical pulse propagates in a long normally dispersive optical fiber. This effect has conventionally been avoided in fiber (super-)continuum-based pulse compression because the accumulated frequency chirp of the output pulse cannot be fully compensated by a standard prism (or grating) pair. Thus, the spectral extending capability of the wave-breaking has not been utilized to shorten the compressed pulse. We demonstrate that wave-breaking-free operation is not necessary if a 4f pulse shaper-based compressor is employed to remove both the linear and nonlinear chirp of the output pulse. By propagating a 180 fs (FWHM) input pulse in a nonlinear photonic crystal fiber beyond the wave-breaking limit, we compress the wave-breaking-extended supercontinuum output pulse to the bandwidth-limited duration of 6.4 fs (FWHM). The combination of high compression ratio (28×) and short pulse width represents a significant improvement over that attained in the wave-breaking-free regime. PMID:22739845
Limiting liability via high resolution image processing
Energy Technology Data Exchange (ETDEWEB)
Greenwade, L.E.; Overlin, T.K.
1996-12-31
The utilization of high resolution image processing allows forensic analysts and visualization scientists to assist detectives by enhancing field photographs, and by providing the tools and training to increase the quality and usability of field photos. Through the use of digitized photographs and computerized enhancement software, field evidence can be obtained and processed as `evidence ready`, even in poor lighting and shadowed conditions or darkened rooms. These images, which are most often unusable when taken with standard camera equipment, can be shot in the worst of photographic condition and be processed as usable evidence. Visualization scientists have taken the use of digital photographic image processing and moved the process of crime scene photos into the technology age. The use of high resolution technology will assist law enforcement in making better use of crime scene photography and positive identification of prints. Valuable court room and investigation time can be saved and better served by this accurate, performance based process. Inconclusive evidence does not lead to convictions. Enhancement of the photographic capability helps solve one major problem with crime scene photos, that if taken with standard equipment and without the benefit of enhancement software would be inconclusive, thus allowing guilty parties to be set free due to lack of evidence.
On the limit of energy resolution in radiation detectors
International Nuclear Information System (INIS)
The limit of energy resolution in various radiation detectors is reviewed from the theoretical view-point. Fano-factors in gaseous, liquid and solid detector media for ionization and for scintillation are discussed and the limit of energy resolution in micro-calorimeters operated at low temperature is also discussed. (author)
New Limits on R-Parity Breakings in Supersymmetric Standard Models
Chang, Darwin; Keung, W. -Y.
1996-01-01
New limits on couplings $\\lambda^i_{jk}{''}$, which break both the baryon number and the $R$--parity, are derived by using a new mechanism that contributes to the neutron-anti-neutron oscillation. The constraints due to proton decay and its potential phenomenology are also reexamined.
Dielectric charged drop break-up at sub-Rayleigh limit conditions
Shrimpton, J.S.
2005-01-01
The maximum charge a drop may hold, for an electrically isolated, electrically conducting drop, in vacuum, is defined by the Rayleigh Limit. For spray plumes of electrically charged drops this condition is clearly not met due to the space charge field. We would like to simulate such spray plumes and to simulate drop break up within them, using stochastic methods. Since many simulated particles are required a dynamic drop stability analysis is clearly not computationally feasible. Based upon a...
LASER MICROPROBE MASS ANALYSIS DETECTION LIMITS AND LATERAL RESOLUTION
Wieser, P.; Wurster, R.; Seiler, H.
1984-01-01
Detection limits of the elements Li, Na, Fe, Ni, Zn, Cd, Hg and Pb obtained by lasermicroprobe massanalysis (LAMMAR 500, Leybold-Heraeus) of organic particulate matter doped with salts are given. The difference between optical and analytical spatial resolution of the lasermicroprobe is discussed. Hints are given that lateral effects may influence the microanalytical results.
Resolution-limiting factors in 2-deoxyglucose autoradiography. I
International Nuclear Information System (INIS)
The authors measured the extent to which factors other than the diffusion of the radioactive label during tissue preparation limits the spatial resolving power of 2-deoxyglucose (2-DG) autoradiography. Radioactive swept frequency gratings were created using microcircuit lithography. The gratings consisted of alternating equal width radioactive and non-radioactive bars in groups of narrowing bar width (effective range 500-20 μm). The vertical thickness of the gratings ranged from 2.25 to 20 μm. The isotope in the radioactive bars was either 14C or 3H. A variety of X-ray films were exposed to these gratings and the resulting images scanned with microdensitometers or video digitizers to determine the fall off in image contrast (dark-bar values minus light-bar values) as a function of the number of dark bars (lines) per millimeter. The power of the isotope was the resolution limiting factor. Grating thickness and type of film made little difference. The limit of resolution with 14C was 10 lines/mm: with 3H it was 25 lines/mm. The microdensitometer itself is apt to be a resolution limiting factor; the resolving power of those commonly used in autoradiography is unlikely to exceed 10 lines/mm. From measurements of the steepness of gray-matter to white-matter transitions in the image from a tissue section, they conclude that the resolution in the image was no worse than 1.6-3.2 lines/mm. Either the isotope or diffusion of the 2-DG during tissue preparation must be the factor that limits resolution. (Auth.)
Statistical Angular Resolution Limit for Ultrawideband MIMO Noise Radar
Directory of Open Access Journals (Sweden)
Xiaoli Zhou
2015-01-01
Full Text Available The two-dimensional angular resolution limit (ARL of elevation and azimuth for MIMO radar with ultrawideband (UWB noise waveforms is investigated using statistical resolution theory. First, the signal model of monostatic UWB MIMO noise radar is established in a 3D reference frame. Then, the statistical angular resolution limits (SARLs of two closely spaced targets are derived using the detection-theoretic and estimation-theoretic approaches, respectively. The detection-theoretic approach is based on the generalized likelihood ratio test (GLRT with given probabilities of false alarm and detection, while the estimation-theoretic approach is based on Smith’s criterion which involves the Cramér-Rao lower bound (CRLB. Furthermore, the relationship between the two approaches is presented, and the factors affecting the SARL, that is, detection parameters, transmit waveforms, array geometry, signal-to-noise ratio (SNR, and parameters of target (i.e., radar cross section (RCS and direction, are analyzed. Compared with the conventional radar resolution theory defined by the ambiguity function, the SARL reflects the practical resolution ability of radar and can provide an optimization criterion for radar system design.
The optical microscopy with virtual image breaks a record: 50-nm resolution imaging is demonstrated
Wang, Zengbo; Li, Lin; Liu, Zhu; Luk'yanchuk, Boris; Chen, Zaichun; Hong, Minghui
2010-01-01
We demonstrate a new 'microsphere nanoscope' that uses ordinary SiO2 microspheres as superlenses to create a virtual image of the object in near field. The magnified virtual image greatly overcomes the diffraction limit. We are able to resolve clearly 50-nm objects under a standard white light source in both transmission and reflection modes. The resolution achieved for white light opens a new opportunity to image viruses, DNA and molecules in real time.
Physical limitations on spatial resolution in electrical capacitance tomography
International Nuclear Information System (INIS)
Electrical capacitance tomography (ECT) is an imaging technique providing the distribution of permittivity in a medium by means of electrodes. As for any imaging systems, the accessible spatial resolution is a key parameter. In this paper the physical limitations on the spatial resolution of ECT sensors are analysed in terms of the accuracy of an object’s position and of the ability to distinguish between two close objects for any sensor geometry. Cylindrical geometry sensors are particularly studied and the example of a square geometry sensor is used to show how to apply the calculations to any other geometries. In cylindrical geometries, it is shown that a 50% gap between electrodes is a good compromise and that increasing the number of electrodes improves the spatial resolution near the electrodes but decreases the spatial resolution in the centre. The best spatial resolution at the centre of the sensor is obtained with 3 or 4 electrodes. In the square geometry studied, it is shown that a better distribution of the spatial resolution is obtained when there are electrodes in the corners. (paper)
Electro-optical bunch shape measurements - possible temporal resolution limits
International Nuclear Information System (INIS)
Coherent synchrotron radiation arises when the longitudinal electron bunch length is smaller than the wavelength. In storage rings, substructures on the electron bunches (micro-bunching) can lead to strong ''bursting'' of coherent radiation and investigation of such effects requires a measurement of the electron bunch length with sufficient temporal resolution. In linear accelerators, the bunch lengths themselves can be extremely short. This report considers the main electro-optical techniques for bunch length measurements and discusses systematic limitations of the method. Special emphasis is put on possible ways to increase the temporal resolution.
Noise and physical limits to maximum resolution of PET images
Energy Technology Data Exchange (ETDEWEB)
Herraiz, J.L.; Espana, S. [Dpto. Fisica Atomica, Molecular y Nuclear, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, Avda. Complutense s/n, E-28040 Madrid (Spain); Vicente, E.; Vaquero, J.J.; Desco, M. [Unidad de Medicina y Cirugia Experimental, Hospital GU ' Gregorio Maranon' , E-28007 Madrid (Spain); Udias, J.M. [Dpto. Fisica Atomica, Molecular y Nuclear, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, Avda. Complutense s/n, E-28040 Madrid (Spain)], E-mail: jose@nuc2.fis.ucm.es
2007-10-01
In this work we show that there is a limit for the maximum resolution achievable with a high resolution PET scanner, as well as for the best signal-to-noise ratio, which are ultimately related to the physical effects involved in the emission and detection of the radiation and thus they cannot be overcome with any particular reconstruction method. These effects prevent the spatial high frequency components of the imaged structures to be recorded by the scanner. Therefore, the information encoded in these high frequencies cannot be recovered by any reconstruction technique. Within this framework, we have determined the maximum resolution achievable for a given acquisition as a function of data statistics and scanner parameters, like the size of the crystals or the inter-crystal scatter. In particular, the noise level in the data as a limitation factor to yield high-resolution images in tomographs with small crystal sizes is outlined. These results have implications regarding how to decide the optimal number of voxels of the reconstructed image or how to design better PET scanners.
Beyond the resolution limit: subpixel resolution in animals and now in silicon
Wilcox, M. J.
2007-09-01
Automatic acquisition of aerial threats at thousands of kilometers distance requires high sensitivity to small differences in contrast and high optical quality for subpixel resolution, since targets occupy much less surface area than a single pixel. Targets travel at high speed and break up in the re-entry phase. Target/decoy discrimination at the earliest possible time is imperative. Real time performance requires a multifaceted approach with hyperspectral imaging and analog processing allowing feature extraction in real time. Hyperacuity Systems has developed a prototype chip capable of nonlinear increase in resolution or subpixel resolution far beyond either pixel size or spacing. Performance increase is due to a biomimetic implementation of animal retinas. Photosensitivity is not homogeneous across the sensor surface, allowing pixel parsing. It is remarkably simple to provide this profile to detectors and we showed at least three ways to do so. Individual photoreceptors have a Gaussian sensitivity profile and this nonlinear profile can be exploited to extract high-resolution. Adaptive, analog circuitry provides contrast enhancement, dynamic range setting with offset and gain control. Pixels are processed in parallel within modular elements called cartridges like photo-receptor inputs in fly eyes. These modular elements are connected by a novel function for a cell matrix known as L4. The system is exquisitely sensitive to small target motion and operates with a robust signal under degraded viewing conditions, allowing detection of targets smaller than a single pixel or at greater distance. Therefore, not only is instantaneous feature extraction possible but also subpixel resolution. Analog circuitry increases processing speed with more accurate motion specification for target tracking and identification.
DEFF Research Database (Denmark)
van Heerwaarden, Belinda; Willi, Yvonne; Kristensen, Torsten N; Hoffmann, Ary A
2008-01-01
desiccation resistance in the rain forest-restricted fly Drosophila bunnanda. After one generation of single-pair mating, additive genetic variance for desiccation resistance increased to a significant level, on average higher than for the control lines. Line crosses revealed that both dominance and epistatic......According to neutral quantitative genetic theory, population bottlenecks are expected to decrease standing levels of additive genetic variance of quantitative traits. However, some empirical and theoretical results suggest that, if nonadditive genetic effects influence the trait, bottlenecks may...... actually increase additive genetic variance. This has been an important issue in conservation genetics where it has been suggested that small population size might actually experience an increase rather than a decrease in the rate of adaptation. Here we test if bottlenecks can break a selection limit for...
Confinement, chiral symmetry breaking and continuum limits in quantum link models
International Nuclear Information System (INIS)
Using the example of compact U(1) lattice gauge theory we argue that quantum link models can be used to reproduce the physics of conventional Hamiltonian lattice gauge theories. In addition to the usual gauge coupling g, these models have a new parameter j which naturally cuts-off large electric flux quanta on each link while preserving exact U(1) gauge invariance. The j → ∞ limit recovers the conventional Hamiltonian. At strong couplings, the theory shows confinement and chiral symmetry breaking for all non-trivial values of j. The phase diagram of the 3+1 dimensional theory suggests that a coulomb phase is present at large but finite j. Setting g = 0, a new approach to the physics of compact U(1) gauge theory on the lattice emerges. In this case the parameter j takes over the role of the gauge coupling, and j → ∞ describes free photons
High-resolution calorimetry: limitations of doped semiconductor thermometers
International Nuclear Information System (INIS)
Small thermal calorimeters operating at cryogenic temperatures have achieved an energy resolution for single X-ray photons that is a factor of 20 better than the theoretical limit for a silicon ionization detector. To determine the potential for further improvements and decide on likely routes for achieving them, we discuss detector design optimization, first for an ideal calorimeter, and then for the case where components exhibit non-ideal behavior. Two serious non-ideal properties of doped semiconductor thermometers are electron-phonon decoupling and excess noise. These have been characterized over a range of sensitivity and operating temperature, and their effects on design optimization and ultimate performance can be evaluated
High-resolution calorimetry: limitations of doped semiconductor thermometers
McCammon, D; Apodaca, E; Deiker, S; Galeazzi, M; Han, S I; Lesser, A; Sanders, W; Kelley, R L; Moseley, S H; Porter, F S; Stahle, C K; Szymkowiak, A E
1999-01-01
Small thermal calorimeters operating at cryogenic temperatures have achieved an energy resolution for single X-ray photons that is a factor of 20 better than the theoretical limit for a silicon ionization detector. To determine the potential for further improvements and decide on likely routes for achieving them, we discuss detector design optimization, first for an ideal calorimeter, and then for the case where components exhibit non-ideal behavior. Two serious non-ideal properties of doped semiconductor thermometers are electron-phonon decoupling and excess noise. These have been characterized over a range of sensitivity and operating temperature, and their effects on design optimization and ultimate performance can be evaluated.
Statistical resolution limit: application to passive polarized source localization
El Korso, Mohammed Nabil; Boyer, Rémy; Renaux, Alexandre; Marcos, Sylvie
2011-01-01
This paper considers the evaluation of the so-called Co-centered Orthogonal Loop and Dipole Uniform and Linear Array (COLD-ULA) performance by mean of the Statistical Resolution Limit (SRL). The SRL adressed herein is based on the estimation accuracy. Toward this end, nonmatrix closed form expressions of the Cramér-Rao Bound (CRB) are derived and thus, the SRL is deduced by an adequat change of variable formula. Finally, concluding remarks and a comparaison between the SRL of the COLD-ULA and...
Sensitivity of Savannah River Plant loss of coolant accident power limit to break size and location
International Nuclear Information System (INIS)
Savannah River Plant reactors are low-pressure, heavy-water reactors with six external process water loops that drive the coolant into an upper plenum and then downward through the assemblies. Assembly loss-of-coolant accident power limits are currently set in these reactors to prevent Ledinegg flow instability (FI) in any assembly flow channel. This might occur due to the power-flow mismatch during the first 2 s of the transient, i.e., the flow drops faster than the power. This study determined the sensitivity of the power limit to the postulated break area and location. The transient reactor analysis code (TRAC) was used to compute steady-state and transient system flows and pressures. The FLOWTRAN code, which employs one-dimensional hydraulics and two- or three-dimensional heat transfer, used the driving pressures generated by TRAC to compute assembly thermal-hydraulic conditions. The FLOWTRAN also iterates on assembly power to determine the minimum assembly power for which the onset of nucleate boiling (ONB) is predicted. Experimental data were then used to convert from ONB to FI. The ONB criterion was recently replaced with an onset-of-significant-voiding criterion since it is a more accurate predictor of flow instability
Zavadlav, Julija; Marrink, Siewert J; Praprotnik, Matej
2016-01-01
The adaptive resolution scheme (AdResS) is a multiscale molecular dynamics simulation approach that can concurrently couple atomistic (AT) and coarse-grained (CG) resolution regions, i.e., the molecules can freely adapt their resolution according to their current position in the system. Coupling to
Electrical limitations to energy resolution in semiconductor particle detectors
International Nuclear Information System (INIS)
Based on the assumption that the noise contribution of a semiconductor detector is due solely to its bulk properties, equations are presented which indicate the theoretical limits of noise in detectoramplifier combinations. These equations show that an optimum amplifier time-constant and detector bias voltage exist for which condition the minimum noise is independent of the semiconductor resistivity. The optimum performance of a detector-amplifier system is shown to depend only upon detector area, input capacity (less detector capacity), semiconductor minority carrier lifetime and the transconductance of the amplifier input tube. A new detector structure which includes a guard-ring electrode as an integral part of the detector structure is described which has the effect of largely eliminating noise due to surface leakage. Experimental results for detector leakage and energy resolution which agree well with theory are presented. The theoretical limit of noise, expressed as full width at half maximum, is from 7 to 10 keV for 1-cm2 p-type silicon detectors at 25oC. (author)
Breaking the diffraction limit of light-sheet fluorescence microscopy by RESOLFT
Hoyer, Patrick; de Medeiros, Gustavo; Balázs, Bálint; Norlin, Nils; Besir, Christina; Hanne, Janina; Kräusslich, Hans-Georg; Engelhardt, Johann; Sahl, Steffen J.; Hell, Stefan W.; Hufnagel, Lars
2016-03-01
We present a plane-scanning RESOLFT [reversible saturable/switchable optical (fluorescence) transitions] light-sheet (LS) nanoscope, which fundamentally overcomes the diffraction barrier in the axial direction via confinement of the fluorescent molecular state to a sheet of subdiffraction thickness around the focal plane. To this end, reversibly switchable fluorophores located right above and below the focal plane are transferred to a nonfluorescent state at each scanning step. LS-RESOLFT nanoscopy offers wide-field 3D imaging of living biological specimens with low light dose and axial resolution far beyond the diffraction barrier. We demonstrate optical sections that are thinner by 5-12-fold compared with their conventional diffraction-limited LS analogs.
DNA Double Strand Break Response and Limited Repair Capacity in Mouse Elongated Spermatids
Directory of Open Access Journals (Sweden)
Emad A. Ahmed
2015-12-01
Full Text Available Spermatids are extremely sensitive to genotoxic exposures since during spermiogenesis only error-prone non homologous end joining (NHEJ repair pathways are available. Hence, genomic damage may accumulate in sperm and be transmitted to the zygote. Indirect, delayed DNA fragmentation and lesions associated with apoptotic-like processes have been observed during spermatid elongation, 27 days after irradiation. The proliferating spermatogonia and early meiotic prophase cells have been suggested to retain a memory of a radiation insult leading later to this delayed fragmentation. Here, we used meiotic spread preparations to localize phosphorylate histone H2 variant (γ-H2AX foci marking DNA double strand breaks (DSBs in elongated spermatids. This technique enabled us to determine the background level of DSB foci in elongated spermatids of RAD54/RAD54B double knockout (dko mice, severe combined immunodeficiency SCID mice, and poly adenosine diphosphate (ADP-ribose polymerase 1 (PARP1 inhibitor (DPQ-treated mice to compare them with the appropriate wild type controls. The repair kinetics data and the protein expression patterns observed indicate that the conventional NHEJ repair pathway is not available for elongated spermatids to repair the programmed and the IR-induced DSBs, reflecting the limited repair capacity of these cells. However, although elongated spermatids express the proteins of the alternative NHEJ, PARP1-inhibition had no effect on the repair kinetics after IR, suggesting that DNA damage may be passed onto sperm. Finally, our genetic mutant analysis suggests that an incomplete or defective meiotic recombinational repair of Spo11-induced DSBs may lead to a carry-over of the DSB damage or induce a delayed nuclear fragmentation during the sensitive programmed chromatin remodeling occurring in elongated spermatids.
Past break-monsoon conditions detectable by high resolution intra-annual δ18O analysis of teak rings
Managave, S. R.; Sheshshayee, M. S.; Borgaonkar, H. P.; Ramesh, R.
2010-03-01
Intra-annual variations in the cellulose oxygen isotopic composition (δ18O) of several annual growth rings of three teak (Tectona grandis L.F.) trees from central India show a clear seasonal cycle with higher values in the early and late growing seasons and lower values in the middle. This cycle is useful to identify growth occurring during different phases of the growing season. Relative humidity (RH) appears to control the intra-annual δ18O variations rather than rainfall, and therefore past break-monsoon conditions associated with lower RH, could be detected by high resolution sub-sampling of annual rings for δ18O analysis.
International Nuclear Information System (INIS)
Simple criteria for local and global instabilities were used to calculate leak-before-break-diagrams for load-controlled deformations. Relations between the tension and bending stresses in the uncracked pipe and the critical crack angle α/sub c/, below which complete fracture cannot occur, were developed for combined loading by internal pressure and external tension and bending. The different assumptions made for local and global instability lead to similar conclusions about the allowable crack length for leak-before-break behavior. It was not the intention of this paper to compare the conclusions with experimental results available
van Laarhoven, Twan; Marchiori, Elena
2014-01-01
Many graph clustering quality functions suffer from a resolution limit, the inability to find small clusters in large graphs. So called resolution-limit-free quality functions do not have this limit. This property was previously introduced for hard clustering, that is, graph partitioning. We investigate the resolution-limit-free property in the context of Non-negative Matrix Factorization (NMF) for hard and soft graph clustering. To use NMF in the hard clustering setting, a common approach is...
Limitations on building single-photon-resolution detection devices
Kok, P
2003-01-01
Single-photon resolution (SPR) detectors can tell the difference between incoming wave packets of n and n+1 photons. Such devices are especially important for linear optical quantum computing with projective measurements. However, in this paper I show that it is impossible to construct a photodetector with single-photon resolution when we are restricted to single-photon sources, linear optical elements and projective measurements with standard (non-photon-number discriminating) photodetectors. These devices include SPR detectors that sometimes fail to distinguish one- and two-photon inputs, but at the same time indicate this failure.
Energy Technology Data Exchange (ETDEWEB)
Judi, David R [Los Alamos National Laboratory; Mcpherson, Timothy N [Los Alamos National Laboratory; Burian, Steven J [UNIV OF UTAH
2009-01-01
States has many dams that are classified as high-hazard potential that need an emergency action plan (EAP). It has been found that the development of EAPs for all high-hazard dams is handicapped due to funding limitations. The majority of the cost associated with developing an EAP is determining the flooded area. The results of this study have shown that coarse resolution dam breach studies can be used to provide an acceptable estimate of the inundated area and economic impacts, with very little computational cost. Therefore, the solution to limited funding may be to perform coarse resolution dam breach studies on high-hazard potential dams and use the results to help prioritize the order in which detailed EAPs should be developed.
Derivation of an Analytical Expression of the Gaussian Model Statistical Resolution Limit
Thamery, Messaoud; Boyer, Remy; Abed-Meraim, Karim
2013-01-01
Statistical Resolution Limit (SRL), defined as the minimal separation to solve two closely spaced signals, is one of the important tools to evaluate a given system performance. Based on S.TS Smith's formulation of the SRL, this paper provides a methodology to compute an approximate analytical expression of the resolution limit in the gaussian model case. As an application, we consider the particular case of two sources located in the near field and consider the resolution limit in terms of mi...
Localized breaking of flux surfaces and the equilibrium beta limit in the W7AS stellarator
International Nuclear Information System (INIS)
We report on PIES three-dimensional equilibrium calculations for W7AS plasmas which exhibit degraded confinement at high beta with no indication that the confinement degradation is being caused by instabilities. The equilibrium calculations exhibit stochastic field lines in the outer region of the plasma, with the flux surfaces appearing to break only locally in the neighborhood of the outer midplane and to remain intact elsewhere. This conclusion follows from plots of field line trajectories, which show smooth, confined curves punctuated by rapid, erratic radial excursions appearing each time the trajectories cross the outer midplane. This result conforms with intuition and with conventional wisdom, which suggest that the flux surfaces should break near the outer midplane due to the strong compression of the three-dimensional flux surfaces there by the Shafranov shift. The results also conform with a WKB calculation (which is justified by the large mode numbers of the magnetic islands involved). This emerging picture, and the associated long connection lengths of the magnetic field lines, may explain why the impact of the predicted stochastic region on the pressure profile in the experiments may be modest. Although the pressure profile is modified in that region, a substantial pressure profile may be supported there. (author)
Resolution limits in holographic display with LED illumination
Chlipała, Maksymilian; Kozacki, Tomasz
2015-06-01
In presented paper we study the influence of spatial and temporal coherence of light source on resolution and depth of focus of holographic reconstructions. Presented holographic display setup uses phase - only spatial light modulator and realizes complex coding shame which allows to reconstruct objects in volume centered around plane of the modulator. In simulations we implement partially coherent reconstructions of complex hologram theory. It allows to investigate quality of holographic reconstructions for various degree of illuminating light coherence. During experimental tests we validate simulation results. We show that the influence of spatial coherence effect of light source on resolution of reconstructed objects is stronger than that of temporal coherence. Moreover we prove that it is possible to obtain high quality holographic reconstructions for large size source and wide spectrum for objects having large depths.
Directory of Open Access Journals (Sweden)
Xavier eLagorce
2015-06-01
Full Text Available Spike-based neuromorphic sensors such as retinas and cochleas, change the way in which the world is sampled. Instead of producing data sampled at a constant rate, these sensors output spikes that are asynchronous and event driven. The event-based nature of neuromorphic sensors implies a complete paradigm shift in current perception algorithms towards those that emphasize the importance of precise timing. The spikes produced by these sensors usually have a time resolution in the order of microseconds. This high temporal resolution is a crucial factor in learning tasks. It is also widely used in the field of biological neural networks. Sound localization for instance relies on detecting time lags between the two ears which, in the barn owl, reaches a temporal resolution of 5 microseconds. Current available neuromorphic computation platforms such as SpiNNaker often limit their users to a time resolution in the order of milliseconds that is not compatible with the asynchronous outputs of neuromorphic sensors. To overcome these limitations and allow for the exploration of new types of neuromorphic computing architectures, we introduce a novel software framework on the SpiNNaker platform. This framework allows for simulations of spiking networks and plasticity mechanisms using a completely asynchronous and event-based scheme running with a microsecond time resolution. Results on two example networks using this new implementation are presented.
Ultimate quantum limit on resolution of two thermal point sources
Nair, Ranjith
2016-01-01
We obtain the fundamental quantum limit for resolving two thermal point sources using an imaging system with limited spatial bandwidth. Using the quantum Cram\\'er-Rao bound, we show that the standard Rayleigh limit is not fundamental and can be surpassed by concrete coherent measurement techniques. Our results are valid for all values of the source strength, all ranges of the electromagnetic spectrum, and for any imaging system with an inversion-symmetric point-spread function. Our findings have applications to many areas of metrology including microscopy, astronomy, and standoff target sensing.
Resolution beyond classical limits with spatial frequency heterodyning
Institute of Scientific and Technical Information of China (English)
A. Mudassar; A. R. Harvey; A. H. Greenaway; J. D. C. Jones
2006-01-01
@@ A technique for coherent imaging based on spatial frequency heterodyning is described. Three images corresponding to three physical measurements are recorded. For the first measurement, a scene is simply illuminated with a coherent beam and for measurements 2 and 3, the scene is projected with cosine and sine fringes, respectively. Due to spatial frequency heterodyning, upper and lower side band information falls in the pass band of the imager. These bands are separated and correct phases and positions are assigned to these bands in the spatial frequency domain. An extension of bandwidth is achieved in the frequency domain and the inverse frequency domain data then give a high resolution coherent image.
Limits to phase resolution in matter wave interferometry
Jääskeläinen, M; Meystre, P
2004-01-01
We study the quantum dynamics of a two-mode Bose-Einstein condensate in a time-dependent symmetric double-well potential using analytical and numerical methods. The effects of internal degrees of freedom on the visibility of interference fringes during a stage of ballistic expansion are investigated varying particle number, nonlinear interaction sign and strength as well as tunneling coupling. Expressions for the phase resolution are derived and the possible enhancement due to squeezing is discussed. In particular, the role of the superfluid - Mott insulator cross-over and its analog for attractive interactions is recognized.
Breaking the energy-bandwidth limit of electro-optic modulators: theory and a device proposal
Lin, Hongtao; Liu, Jifeng; Zhang, Lin; Michel, Jurgen; Hu, Juejun
2013-01-01
In this paper, we quantitatively analyzed the trade-off between energy per bit for switching and modulation bandwidth of classical electro-optic modulators. A formally simple energy-bandwidth limit (Eq. 10) is derived for electro-optic modulators based on intra-cavity index modulation. To overcome this limit, we propose a dual cavity modulator device which uses a coupling modulation scheme operating at high bandwidth (> 200 GHz) not limited by cavity photon lifetime and simultaneously features an ultra-low switching energy of 0.26 aJ, representing over three orders of magnitude energy consumption reduction compared to state-of-the-art electro-optic modulators.
Breaking the Customer Code : A model to Translate Customer Expectations into Specification Limits
Gregorio, Ruben
2010-01-01
Today, firms compete with services rather than goods. Large service organizations are beginning to use Six Sigma as continuous improvement tool. An important part of the Six Sigma methodology is the calculation of number of defects in the process, i.e. points outside the specification limits. Unlike goods quality, which can be measured objectively by number of defects, in service goods the setting up of specification limits is a complicated issue because it is marked by the use and expectatio...
Recurrent myopic foveoschisis: resolution after internal limiting membrane removal
Directory of Open Access Journals (Sweden)
Renato Antunes Schiave Germano
2015-02-01
Full Text Available We report a case of a 66-year-old man with a history of high myopia and who was referred for acute decreased visual acuity of the right eye. Fundus examination and optical coherence tomography (OCT showed a mild epiretinal membrane (ERM and splitting of retinal layers. Pars plana vitrectomy was performed with intravitreous triamcinolone injection, posterior hyaloid and ERM peeling, and 12% perfluoropropane (C3F8 gas tamponade. After remaining asymptomatic for 17 months, the patient reported a new episode of sudden decreased visual acuity in his right eye, and OCT showed recurrent myopic foveoschisis (MF. He underwent vitrectomy and internal limiting membrane (ILM peeling. Six months later, the patient’s best corrected visual acuity had improved to 20/25. Optical coherence tomography showed a remarkably improved macular anatomy, with residual traction along the inferotemporal arcade, which was attributed to the vessel stiffness itself. We conclude that removing the internal limiting membrane is a challenging maneuver in myopic foveoschisis, even with staining approaches. Although myopic foveoschisis may be resolved without peeling the internal limiting membrane, its removal should be considered if the condition recurs.
Blanco, Celia; Crusats, Joaquim; El-Hachemi, Zoubir; Moyano, Albert; Hochberg, David; 10.1039/C2CP43488A
2012-01-01
We analyze limited enantioselective (LES) autocatalysis in a temperature gradient and with internal flow/recycling of hot and cold material. Microreversibility forbids broken mirror symmetry for LES in the presence of a temperature gradient alone. This symmetry can be broken however when the auto-catalysis and limited enantioselective catalysis are each localized within the regions of low and high temperature, respectively. This scheme has been recently proposed as a plausible model for spontaneous emergence of chirality in abyssal hydrothermal vents. Regions in chemical parameter space are mapped out in which the racemic state is unstable and bifurcates to chiral solutions.
Impact of Q value and gain-limit to the resolution of inverse Q filtering
International Nuclear Information System (INIS)
The earth Q-filter, including the energy dissipation of high frequency wave components and the velocity dispersion, distorts seismic wavelets, reduces the seismic resolution, and causes difficulty to obtain high resolution seismic data. The process of inverse Q-filter attempts to remove the Q-effect to produce high-resolution seismic data, but the numerical instability of inverse Q-filter amplitude compensation reduces the signal-to-noise (S/N) ratio and limits its spatial resolution. In order to control the numerical instability, a large number of papers studying the gain-limit constrained inverse Q-filter amplitude compensation method. But, papers rarely discussing whether gain-limit constrained inverse Q-filter with the medium Q value can certainly improve the seismic data resolution or not, and what gain-limit and Q value should be used in inverse Q-filter in order to improve the resolution. In this paper, we focus on understanding the impact of Q value and gain-limit to seismic data resolution, and studying a novel method to optimize Q value within a certain gain-limit constrained inverse Q-filter amplitude compensation, by which we can achieve the optimum resolution seismic data. (paper)
Diffractive optics and nanophotonics resolution below the diffraction limit
Minin, Igor
2016-01-01
In this book the authors present several examples of techniques used to overcome the Abby diffraction limit using flat and 3D diffractive optical elements, photonic crystal lenses, photonic jets, and surface plasmon diffractive optics. The structures discussed can be used in the microwave and THz range and also as scaled models for optical frequencies. Such nano-optical microlenses can be integrated, for example, into existing semiconductor heterostructure platforms for next-generation optoelectronic applications. Chapter 1 considers flat diffractive lenses and innovative 3D radiating structures including a conical millimeter-wave Fresnel zone plate (FZP) lens proposed for subwavelength focusing. In chapter 2 the subwavelength focusing properties of diffractive photonic crystal lenses are considered and it is shown that at least three different types of photonic crystal lens are possible. With the aim of achieving subwavelength focusing, in chapter 3 an alternative mechanism to produce photonic jets at Tera...
Collins, L.; Tselev, A.; Jesse, S.; Okatan, M. B.; Proksch, R.; Mathews, J. P.; Mitchell, G. D.; Rodriguez, B. J.; Kalinin, S. V.; Ivanov, I. N.
2014-10-01
The correlation between local mechanical (elasto-plastic) and structural (composition) properties of coal presents significant fundamental and practical interest for coal processing and for the development of rheological models of coal to coke transformations. Here, we explore the relationship between the local structural, chemical composition, and mechanical properties of coal using a combination of confocal micro-Raman imaging and band excitation atomic force acoustic microscopy for a bituminous coal. This allows high resolution imaging (10s of nm) of mechanical properties of the heterogeneous (banded) architecture of coal and correlating them to the optical gap, average crystallite size, the bond-bending disorder of sp2 aromatic double bonds, and the defect density. This methodology allows the structural and mechanical properties of coal components (lithotypes, microlithotypes, and macerals) to be understood, and related to local chemical structure, potentially allowing for knowledge-based modeling and optimization of coal utilization processes.
International Nuclear Information System (INIS)
The correlation between local mechanical (elasto-plastic) and structural (composition) properties of coal presents significant fundamental and practical interest for coal processing and for the development of rheological models of coal to coke transformations. Here, we explore the relationship between the local structural, chemical composition, and mechanical properties of coal using a combination of confocal micro-Raman imaging and band excitation atomic force acoustic microscopy for a bituminous coal. This allows high resolution imaging (10s of nm) of mechanical properties of the heterogeneous (banded) architecture of coal and correlating them to the optical gap, average crystallite size, the bond-bending disorder of sp2 aromatic double bonds, and the defect density. This methodology allows the structural and mechanical properties of coal components (lithotypes, microlithotypes, and macerals) to be understood, and related to local chemical structure, potentially allowing for knowledge-based modeling and optimization of coal utilization processes. (paper)
Energy Technology Data Exchange (ETDEWEB)
Gonzalez Gonzalez, R., E-mail: r.gonzalez@ing.unipi.it [San Piero a Grado Nuclear Research Group (GRNSPG), University of Pisa, Via Livornese 1291, 56122 San Piero a Grado, Pisa (Italy); Petruzzi, A., E-mail: a.petruzzi@ing.unipi.it [San Piero a Grado Nuclear Research Group (GRNSPG), University of Pisa, Via Livornese 1291, 56122 San Piero a Grado, Pisa (Italy); D’Auria, F., E-mail: f.dauria@ing.unipi.it [San Piero a Grado Nuclear Research Group (GRNSPG), University of Pisa, Via Livornese 1291, 56122 San Piero a Grado, Pisa (Italy); Mazzantini, O., E-mail: mazzantini@na-sa.com.ar [Nucleo-electrica Argentina Sociedad Anonima (NA-SA), Buenos Aires (Argentina)
2014-08-15
Atucha-2 is a Siemens-designed Pressurized Heavy Water Reactor (PHWR) reactor under construction in the Republic of Argentina. Its geometrical complexity and peculiarity (e.g. oblique Control Rods, Positive Void coefficient) required a developed and validated complex three dimensional (3D) neutron kinetics (NK) coupled thermal hydraulic (TH) model. Reactor shut-down is obtained by oblique CRs and, during accidental conditions, by an emergency shut-down system (JDJ) injecting a highly concentrated boron solution (boron clouds) in the moderator tank. The boron clouds reconstruction is obtained using a Computational Fluid Dynamics (CFD) CFX code calculation. A complete Large Break Loss Of Coolant Accident (LBLOCA) calculation implies the application of the RELAP5-3D{sup ©} system code. Within the framework of the third Agreement “Nucleoelèctrica Argentina-Sociedad Anonima (NA-SA) – University of Pisa/GRNSPG” (Contract, 2009), a new RELAP5-3D control system for the boron injection system was developed and implemented in the validated coupled RELAP5-3D/NESTLE model of the Atucha 2 NPP. The aim of this activity is to find out the limiting case (maximum break area size) for the Peak Cladding Temperature for LOCAs under fixed boundary conditions.
Rice, James H.
2007-01-01
Fluorescence microscopy is an important and extensively utilised tool for imaging biological systems. However, the image resolution that can be obtained has a limit as defined through the laws of diffraction. Demand for improved resolution has stimulated research into developing methods to image beyond the diffraction limit based on far-field fluorescence microscopy techniques. Rapid progress is being made in this area of science with methods emerging that enable fluorescence imaging in the f...
Energy Technology Data Exchange (ETDEWEB)
Kubo, Yugo, E-mail: kubo-yugo@sei.co.jp; Hamada, Kotaro; Urano, Akira
2013-12-15
The minimum detection limit and spatial resolution for a thinned semiconductor sample were determined by electron probe microanalysis (EPMA) using a Schottky field emission (FE) electron gun and wavelength dispersive X-ray spectrometry. Comparison of the FE-EPMA results with those obtained using energy dispersive X-ray spectrometry in conjunction with scanning transmission electron microscopy, confirmed that FE-EPMA is largely superior in terms of detection sensitivity. Thin-sample FE-EPMA is demonstrated as a very effective method for high resolution, high sensitivity analysis in a laboratory environment because a high probe current and high signal-to-noise ratio can be achieved. - Highlights: • Minimum detection limit and spatial resolution determined for FE-EPMA. • Detection sensitivity of FE-EPMA greatly superior to that of STEM-EDX. • Minimum detection limit and spatial resolution controllable by probe current.
International Nuclear Information System (INIS)
Measurements are presented of the far-infrared absorption of thin superconducting aluminum films in a parallel magnetic field. The results for moderately thick films (droughly-equal10 nm) are in reasonable agreement with the Abrikosov-Gor'kov theory of pair breaking. The experimental results for ultrathin films (d0μ/sub B/H. This shift of the gap is attributed to a photon-absorption process, where the quasiparticle spin is flipped with respect to the static field. The complex conductivity of a paramagnetically limited film in a parallel magnetic field is calculated, both within the Bardeen-Cooper-Schrieffer framework and using the more general Green's-function formalism with the inclusion of spin-orbit and (magnetic) spin-flip scattering. For the ultrathin Al films we obtain a good quantitative agreement between theory and experiment, assuming a spin-orbit coupling h/tau/sub SO/Δroughly-equal0.1 and a reduced value of the imaginary part of the conductivity, probably due to strong electron-phonon coupling effects
Time resolution limits of the MWPCs for the LHCb muon system
Gruber, L; Schmidt, B
2011-01-01
Detailed simulations of the timing properties of the Multi-Wire-Proportional-Chambers of the LHCb muon system are compared with actual measurements. The simulated time resolution is in good agreement with the measurement which allows to study the resolution limiting parameters like diffusion, charge deposit fluctuations, cluster position fluctuations, electronics noise, track position and wire spacing to show how they affect the performance of the system. Methods to improve the time resolution of the muon chambers are discussed. (C) 2010 Elsevier B.V. All rights reserved.
On the limiting resolution of silicon detectors for short-range particles
International Nuclear Information System (INIS)
The transition to planar tecnology has lead to substantial improvement of energy resolution of Si detectors of strongly ionizing nuclear radiations. For 5 MeV α-particles the resolution (δα) is equal 9.2 keV. The application of the method of local diffusion permitted to attain δα=8.1-8.4 keV. The comparison of the new resolution level with the theoretical limit is carried out. It is shown that the combination of partial contributions of fluctuations caused by fundamental mechanisms practically determined δα of obtained detectors
Surpassing the Path-Limited Resolution of a Fourier Transform Spectrometer with Frequency Combs
Maslowski, Piotr; Johansson, Alexandra C; Khodabakhsh, Amir; Kowzan, Grzegorz; Rutkowski, Lucile; Mills, Andrew A; Mohr, Christian; Jiang, Jie; Fermann, Martin E; Foltynowicz, Aleksandra
2015-01-01
Fourier transform spectroscopy based on incoherent light sources is a well-established tool in research fields from molecular spectroscopy and atmospheric monitoring to material science and biophysics. It provides broadband molecular spectra and information about the molecular structure and composition of absorptive media. However, the spectral resolution is fundamentally limited by the maximum delay range ({\\Delta}$_{max}$) of the interferometer, so acquisition of high-resolution spectra implies long measurement times and large instrument size. We overcome this limit by combining the Fourier transform spectrometer with an optical frequency comb and measuring the intensities of individual comb lines by precisely matching the {\\Delta}$_{max}$ to the comb line spacing. This allows measurements of absorption lines narrower than the nominal (optical path-limited) resolution without ringing effects from the instrumental lineshape and reduces the acquisition time and interferometer length by orders of magnitude.
Willey, Carson L; Simonetti, Francesco
2016-06-01
Mapping the speed of mechanical waves traveling inside a medium is a topic of great interest across many fields from geoscience to medical diagnostics. Much work has been done to characterize the fidelity with which the geometrical features of the medium can be reconstructed and multiple resolution criteria have been proposed depending on the wave-matter interaction model used to decode the wave speed map from scattering measurements. However, these criteria do not define the accuracy with which the wave speed values can be reconstructed. Using two-dimensional simulations, it is shown that the first-arrival traveltime predicted by ray theory can be an accurate representation of the arrival of a pulse first break even in the presence of diffraction and other phenomena that are not accounted for by ray theory. As a result, ray-based tomographic inversions can yield accurate wave speed estimations also when the size of a sound speed anomaly is smaller than the resolution length of the inversion method provided that traveltimes are estimated from the signal first break. This increased sensitivity however renders the inversion more susceptible to noise since the amplitude of the signal around the first break is typically low especially when three-dimensional anomalies are considered. PMID:27369139
Doppler broadening as a lower limit to the angular resolution of next-generation Compton telescopes
Zoglauer, Andreas; Kanbach, Gottfried
2003-03-01
The angular resolution of a telescope which detects gamma-rays via the Compton effect is fundamentally limited below a few hundred keV by the fact that the target electrons have an indeterminable momentum inside their atoms which introduces an uncertainty in the recoil energy of the Compton electron and the scattered photon. This additional component in the energy and momentum equation results in a Doppler broadening of the angular resolution compared to the standard Compton equation for a target at rest. The deterioration in resolution is most pronounced for low photon energy, high scatter angle, and high Z of the scatter material. This physical limit to the angular resolution of a Compton telescope is present even if all other parameters (e.g. energy and position) are measured with high accuracy. For different Compton scatter materials such as silicon, germanium and xenon, which are used in current telescope designs, the best possible angular resolution as a function of photon energy and scatter angle is calculated. Averaged over all scatter angles and energies, the Doppler-limited angular resolution of silicon is a factor of ~1.6 better than that of germanium and a factor of ~1.9 better than that of xenon. Looking at the Doppler limit of materials from Z=1 to 90 the best angular resolution can be reached for alkaline and alkaline earth metals, the worst for elements with filled p-orbitals (noble gases) and d-orbitals (e.g. Pd and Au). Of all semiconductors which might be used in a next generation Compton telescope, silicon seems to be the best choice.
Directory of Open Access Journals (Sweden)
Giovanni Di Virgilio
Full Text Available OBJECTIVES: We quantify spatial turnover in communities of 1939 plant and 59 mammal species at 2.5 km resolution across a topographically heterogeneous region in south-eastern Australia to identify distributional breaks and low turnover zones where multiple species distributions overlap. Environmental turnover is measured to determine how climate, topography and geology influence biotic turnover differently across a variety of biogeographic breaks and overlaps. We identify the genera driving turnover and confirm the versatility of this approach across spatial scales and locations. METHODS: Directional moving window analyses, rotated through 360°, were used to measure spatial turnover variation in different directions between gridded cells containing georeferenced plant and mammal occurrences and environmental variables. Generalised linear models were used to compare taxic turnover results with equivalent analyses for geology, regolith weathering, elevation, slope, solar radiation, annual precipitation and annual mean temperature, both uniformly across the entire study area and by stratifying it into zones of high and low turnover. Identified breaks and transitions were compared to a conservation bioregionalisation framework widely used in Australia. RESULTS/SIGNIFICANCE: Detailed delineations of plant and mammal turnover zones with gradational boundaries denoted subtle variation in species assemblages. Turnover patterns often diverged from bioregion boundaries, though plant turnover adhered most closely. A prominent break zone contained either comparable or greater numbers of unique genera than adjacent overlaps, but these were concentrated in a small subsection relatively under-protected by conservation reserves. The environmental correlates of biotic turnover varied for different turnover zones in different subsections of the study area. Topography and temperature showed much stronger relationships with plant turnover in a topographically
Label-Free Nanoscopy with Contact Microlenses: Super-Resolution Mechanisms and Limitations
Astratov, Vasily N; Brettin, Aaron; Allen, Kenneth W; Maslov, Alexey V; Limberopoulos, Nicholaos I; Walker, Dennis E; Urbas, Augustine M
2016-01-01
Despite all the success with developing super-resolution imaging techniques, the Abbe limit poses a severe fundamental restriction on the resolution of far-field imaging systems based on diffraction of light. Imaging with contact microlenses, such as microspheres or microfibers, can increase the resolution by a factor of two beyond the Abbe limit. The theoretical mechanisms of these methods are debated in the literature. In this work, we focus on the recently expressed idea that optical coupling between closely spaced nanoscale objects can lead to the formation of the modes that drastically impact the imaging properties. These coupling effects emerge in nanoplasmonic or nanocavity clusters, photonic molecules, or various arrays under resonant excitation conditions. The coherent nature of imaging processes is key to understanding their physical mechanisms. We used a cluster of point dipoles, as a simple model system, to study and compare the consequences of coherent and incoherent imaging. Using finite differe...
Ground-state depletion for subdiffraction-limited spatial resolution in coherent anti-Stokes Raman
Cleff, C.; Groß, P.; Fallnich, C.; Offerhaus, H. L.; Herek, J.; Kruse, K.; Beeker, W. P.; Lee, C. J.; Boller, K. J.
2012-01-01
We theoretically investigate ground-state depletion for subdiffraction-limited spatial resolution in coherent anti-Stokes Raman scattering (CARS) microscopy. We propose a scheme based on ground-state depopulation, which is achieved via a control laser light field incident prior to the CARS excitatio
Lee, Juyong; Lee, Jooyoung; Brooks, Bernard R; Ahn, Yong-Yeol
2016-01-01
We investigate the possibility of global optimization-based overlapping community detection, using link community framework. We first show that partition density, the original quality function used in link community detection method, is not suitable as a quality function for global optimization because it prefers breaking communities into triangles except in highly limited conditions. We analytically derive those conditions and confirm it with computational results on direct optimization of various synthetic and real-world networks. To overcome this limitation, we propose alternative approaches combining the weighted line graph transformation and existing quality functions for node-based communities. We suggest a new line graph weighting scheme, a normalized Jaccard index. Computational results show that community detection using the weighted line graphs generated with the normalized Jaccard index leads to a more accurate community structure.
Community detection in weighted brain connectivity networks beyond the resolution limit
Nicolini, Carlo; Bifone, Angelo
2016-01-01
Graph theory provides a powerful framework to investigate brain functional connectivity networks and their modular organization. However, most graph-based methods suffer from a fundamental resolution limit that may have affected previous studies and prevented detection of modules, or communities, that are smaller than a specific scale. Surprise, a resolution-limit-free function rooted in discrete probability theory, has been recently introduced and applied to brain networks, revealing a wide size-distribution of functional modules, in contrast with many previous reports. However, the use of Surprise is limited to binary networks, while brain networks are intrinsically weighted, reflecting a continuous distribution of connectivity strengths between different brain regions. Here, we propose Asymptotical Surprise, a continuous version of Surprise, for the study of weighted brain connectivity networks, and validate this approach in synthetic networks endowed with a ground-truth modular structure. We compare Asymp...
Obrien, S. O. (Principal Investigator)
1980-01-01
The program, LACVIN, calculates vegetative indexes numbers on limited area coverage/high resolution picture transmission data for selected IJ grid sections. The IJ grid sections were previously extracted from the full resolution data tapes and stored on disk files.
Spatial resolution limits for synchrotron-based spectromicroscopy in the mid- and near-infrared
Levenson, Erika
2008-01-01
Spatial resolution tests were performed on beamline 1.4.4 at the Advanced Light Source in Berkeley, CA, USA, a third-generation synchrotron light source. This beamline couples the high-brightness synchrotron source to a Thermo-Electron Continumum XL infrared microscope. Two types of resolution tests were performed in both the mid-IR and near-IR. The results are compared with a diffraction-limited spot size theory. At shorter near-IR wavelengths the experimental results begin to deviate from d...
Theoretical limit of spatial resolution in diffuse optical tomography using a perturbation model
Energy Technology Data Exchange (ETDEWEB)
Konovalov, A B; Vlasov, V V [E.I. Zababakhin All-Russian Scientific-Research Institute of Technical Physics, Russian Federal Nuclear Centre, Snezhinsk, Chelyabinsk region (Russian Federation)
2014-03-28
We have assessed the limit of spatial resolution of timedomain diffuse optical tomography (DOT) based on a perturbation reconstruction model. From the viewpoint of the structure reconstruction accuracy, three different approaches to solving the inverse DOT problem are compared. The first approach involves reconstruction of diffuse tomograms from straight lines, the second – from average curvilinear trajectories of photons and the third – from total banana-shaped distributions of photon trajectories. In order to obtain estimates of resolution, we have derived analytical expressions for the point spread function and modulation transfer function, as well as have performed a numerical experiment on reconstruction of rectangular scattering objects with circular absorbing inhomogeneities. It is shown that in passing from reconstruction from straight lines to reconstruction using distributions of photon trajectories we can improve resolution by almost an order of magnitude and exceed the accuracy of reconstruction of multi-step algorithms used in DOT. (optical tomography)
Scanning tunneling microscopy on rough surfaces: Tip-shape-limited resolution
Reiss, G.; Vancea, J.; Wittmann, H.; Zweck, J.; Hoffmann, H.
1990-02-01
This paper discusses the reliability of scanning tunneling microscopy (STM) images of mesoscopically rough surfaces. The specific structure of these images represents a convolution between the real surface topography and the shape of the tip. In order to interpret these images quantitatively, the line scans of steep and high steps can be used to obtain an image of the tip itself. This image shows tip radii ranging typically from 5 to 15 nm and cone angles of about 30° over a length of 80 nm, and can in turn be used to recognize the limits of STM resolution on a rough surface: High-resolution transmission electron microscopy cross-section images of Au island films on a Au-Nb double layer are convoluted with the experimentally observed tip shape; the resulting line scans correspond very well with STM graphs of the same samples. Finally an overall criterion for the resolution of the STM on such surfaces is proposed.
Sub 100 nm proton beam micromachining: theoretical calculations on resolution limits
International Nuclear Information System (INIS)
Proton beam micromachining is a novel direct-write process for the production of three-dimensional (3D) microstructures. A focused beam of MeV protons is scanned in a pre-determined pattern over a suitable resist material (e.g. PMMA or SU-8) and the latent image formed is subsequently developed chemically. In this paper calculations on theoretical resolution limits of proton beam micromachined three-dimensional microstructures are presented. Neglecting the finite beam size, a Monte Carlo ion transport code was used in combination with a theoretical model describing the delta-ray (δ-ray) energy deposition to determine the lateral energy deposition distribution in PMMA resist material. The energy deposition distribution of ion induced secondary electrons (δ-rays) has been parameterized using analytical models. It is assumed that the attainable resolution is limited by a convolution of the spread of the ion beam and energy deposition of the δ-rays
Some Fundamental Limits on SAW RFID Tag Information Capacity and Collision Resolution
Barton, Richard J.
2013-01-01
In this paper, we apply results from multi-user information theory to study the limits of information capacity and collision resolution for SAW RFID tags. In particular, we derive bounds on the achievable data rate per tag as a function of fundamental parameters such as tag time-bandwidth product, tag signal-to-noise ratio (SNR), and number of tags in the environment. We also discuss the implications of these bounds for tag waveform design and tag interrogation efficiency
Strong effect of surfaces on resolution limit of negative-index "superlens"
Bratkovsky, A. M.; A. Cano; Levanyuk, A. P.
2004-01-01
We show that subwavelength imaging by negative index materials (NIM), related to their "soft" electromagnetic response, is very (and non trivially) sensitive to the surface properties. A minute deviation of dielectric permittivity epsilon or magnetic permeability mu from the ideal values epsilon = mu = -1 in thin surface layer(s) results in drastic reduction of the resolution limit of a NIM slab. There may be a gap in the polariton spectrum and this would allow establishment of a stationary r...
Printable Nanoscopic Metamaterial Absorbers and Images with Diffraction-Limited Resolution.
Richner, Patrizia; Eghlidi, Hadi; Kress, Stephan J P; Schmid, Martin; Norris, David J; Poulikakos, Dimos
2016-05-11
The fabrication of functional metamaterials with extreme feature resolution finds a host of applications such as the broad area of surface/light interaction. Nonplanar features of such structures can significantly enhance their performance and tunability, but their facile generation remains a challenge. Here, we show that carefully designed out-of-plane nanopillars made of metal-dielectric composites integrated in a metal-dielectric-nanocomposite configuration can absorb broadband light very effectively. We further demonstrate that electrohydrodynamic printing in a rapid nanodripping mode is able to generate precise out-of-plane forests of such composite nanopillars with deposition resolutions at the diffraction limit on flat and nonflat substrates. The nanocomposite nature of the printed material allows the fine-tuning of the overall visible light absorption from complete absorption to complete reflection by simply tuning the pillar height. Almost perfect absorption (∼95%) over the entire visible spectrum is achieved by a nanopillar forest covering only 6% of the printed area. Adjusting the height of individual pillar groups by design, we demonstrate on-demand control of the gray scale of a micrograph with a spatial resolution of 400 nm. These results constitute a significant step forward in ultrahigh resolution facile fabrication of out-of-plane nanostructures, important to a broad palette of light design applications. PMID:27100105
Gagunashvili, Nikolai
2014-01-01
A procedure based on a Mixture Density Model for correcting experimental data for distortions due to finite resolution and limited detector acceptance is presented. Addressing the case that the solution is known to be non-negative, in the approach presented here the true distribution is estimated by a weighted sum of probability density functions with positive weights and with the width of the densities acting as a regularisation parameter responsible for the smoothness of the result. To obtain better smoothing in less populated regions, the width parameter scales inversely proportional to the square root of estimated density. Furthermore, the non-negative garrotte method is used to find the most economic representation of the solution. Cross-validation is employed to determine the optimal values of the resolution and garrotte parameters. The proposed approach is directly applicable to multidimensional problems. Numerical examples in one and two dimensions are presented to illustrate the procedure.
Gagunashvili, N. D.
2015-04-01
A procedure based on a Mixture Density Model for correcting experimental data for distortions due to finite resolution and limited detector acceptance is presented. Addressing the case that the solution is known to be non-negative, in the approach presented here, the true distribution is estimated by a weighted sum of probability density functions with positive weights and with the width of the densities acting as a regularization parameter responsible for the smoothness of the result. To obtain better smoothing in less populated regions, the width parameter is chosen inversely proportional to the square root of the estimated density. Furthermore, the non-negative garrote method is used to find the most economic representation of the solution. Cross-validation is employed to determine the optimal values of the resolution and garrote parameters. The proposed approach is directly applicable to multidimensional problems. Numerical examples in one and two dimensions are presented to illustrate the procedure.
Spatial resolution, information limit, and contrast transfer in piezoresponse force microscopy
International Nuclear Information System (INIS)
Scanning probe-based ferroelectric domain imaging and patterning has attracted broad attention for use in the characterization of ferroelectric materials, ultrahigh density data storage, and nanofabrication. The viability of these applications is limited by the minimal domain size that can be fabricated and reliably detected by scanning probe microscopy. Here, the contrast transfer mechanism in piezoresponse force microscopy (PFM) of ferroelectric materials is analysed in detail. A consistent definition of resolution is developed both for the writing and the imaging processes, and the concept of an information limit in PFM is established. Experimental determination of the object transfer function and the subsequent reconstruction of an 'ideal image' is demonstrated. This contrast transfer theory provides a quantitative basis for image interpretation and allows for the comparison of different instruments in PFM. It is shown that experimentally observed domain sizes can be limited by the resolution of the scanning probe microscope to the order of tens of nanometres even though smaller domains, of the order of several nanometres, can be created
Non-LTE, Relativistic Accretion Disk Fits to 3C~273 and the Origin of the Lyman Limit Spectral Break
Blaes, Omer M; Agol, E; Krolik, J H; Blaes, Omer; Hubeny, Ivan; Agol, Eric; Krolik, Julian H.
2001-01-01
We fit general relativistic, geometrically thin accretion disk models with non-LTE atmospheres to near simultaneous multiwavelength data of 3C~273, extending from the optical to the far ultraviolet. Our model fits show no flux discontinuity associated with a hydrogen Lyman edge, but they do exhibit a spectral break which qualitatively resembles that seen in the data. This break arises from relativistic smearing of Lyman emission edges which are produced locally at tens of gravitational radii in the disk. We discuss the possible effects of metal line blanketing on the model spectra, as well as the substantial Comptonization required to explain the observed soft X-ray excess. Our best fit accretion disk model underpredicts the near ultraviolet emission in this source, and also has an optical spectrum which is too red. We discuss some of the remaining physical uncertainties, and suggest in particular that an extension of our models to the slim disk regime and/or including nonzero magnetic torques across the inne...
Polymer dynamics, fluorescence correlation spectroscopy, and the limits of optical resolution
Enderlein, Joerg
2012-01-01
In recent years, fluorescence correlation spectroscopy has been increasingly applied for the study of polymer dynamics on the nanometer scale. The core idea is to extract, from a measured autocorrelation curve, an effective mean-square displacement function that contains information about the underlying conformational dynamics. The paper presents a fundamental study of the applicability of fluorescence correlation spectroscopy for the investigation of nanoscale conformational and diffusional dynamics. We find that fluorescence correlation spectroscopy cannot reliably elucidate processes on length scales much smaller than the resolution limit of the optics used and that its improper use can yield spurious results for the observed dynamics.
High-resolution (Doppler-limited) spectroscopy using quantum-cascade distributed-feedback lasers
International Nuclear Information System (INIS)
Lasing characteristics were evaluated for distributed-feedback quantum-cascade (QC) lasers operating in a continuous mode at cryogenic temperatures. These tests were performed to determine the QC lasers close-quote suitability for use in high-resolution spectroscopic applications, including Doppler-limited molecular absorption and pressure-limited lidar applications. By use of a rapid-scan technique, direct absorbance measurements of nitric oxide (NO) and ammonia (NH3 ) were performed with several QC lasers, operating at either 5.2 or 8.5 μm . Results include time-averaged linewidths of better than 40MHz and long-term laser frequency reproducibility, even after numerous temperature cycles, of 80MHz or better. Tuning rates of 2.5 cm-1 in 0.6ms can be easily achieved. Noise-equivalent absorbance of 3x10-6 was also obtained without optimizing the optical arrangement. copyright 1998 Optical Society of America
Combined X-ray-electron imaging techniques: Limitations on lateral resolution
International Nuclear Information System (INIS)
Capabilities of the imaging techniques, in which X-rays are converted to electrons and then the emitted electrons are registered by means of an electron microscope, are analyzed, the focus being on the factors limiting lateral resolution at the stage of electron emission. Bearing in mind the tendency to use harder synchrotron X-rays for some combined X-ray-electron microscopy methods, calculations were made for two significantly different X-ray energies: E = 1.828 keV (K-edge of Si) and E = 11.923 keV (L3-edge of Au). By using Monte Carlo simulations of the electron trajectories beneath the surface of the sample we show that the radius of the spot from which photoelectrons are emitted could be as small as 1 nm. However, when proper account is taken of an entire electron cascade associated with the re-building of electron shells after photoelectron emission, spots more than one order of magnitude larger result, limiting the best lateral resolution to 20-30 nm
Robertson, J. Gordon; Bland-Hawthorn, Joss
2012-09-01
As telescopes get larger, the size of a seeing-limited spectrograph for a given resolving power becomes larger also, and for ELTs the size will be so great that high resolution instruments of simple design will be infeasible. Solutions include adaptive optics (but not providing full correction for short wavelengths) or image slicers (which give feasible but still large instruments). Here we develop the solution proposed by Bland-Hawthorn and Horton: the use of diffraction-limited spectrographs which are compact even for high resolving power. Their use is made possible by the photonic lantern, which splits a multi-mode optical fiber into a number of single-mode fibers. We describe preliminary designs for such spectrographs, at a resolving power of R ~ 50,000. While they are small and use relatively simple optics, the challenges are to accommodate the longest possible fiber slit (hence maximum number of single-mode fibers in one spectrograph) and to accept the beam from each fiber at a focal ratio considerably faster than for most spectrograph collimators, while maintaining diffraction-limited imaging quality. It is possible to obtain excellent performance despite these challenges. We also briefly consider the number of such spectrographs required, which can be reduced by full or partial adaptive optics correction, and/or moving towards longer wavelengths.
Directory of Open Access Journals (Sweden)
Jinyoung Rhee
2014-08-01
Full Text Available The use of land surface temperature and vertical temperature profile data from Moderate Resolution Imaging Spectroradiometer (MODIS, to estimate high spatial resolution daily and monthly maximum and minimum 2 m above ground level (AGL air temperatures for regions with limited in situ data was investigated. A diurnal air temperature change model was proposed to consider the differences between the MODIS overpass times and the times of daily maximum and minimum temperatures, resulting in the improvements of the estimation in terms of error values, especially for minimum air temperature. Both land surface temperature and vertical temperature profile data produced relatively high coefficient of determination values and small Mean Absolute Error (MAE and Root Mean Square Error (RMSE values for air temperature estimation. The correction of the estimates using two gridded datasets, National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR reanalysis and Climate Research Unit (CRU, was performed and the errors were reduced, especially for maximum air temperature. The correction of daily and monthly air temperature estimates using the NCEP/NCAR reanalysis data, however, still produced relatively large error values compared to existing studies, while the correction of monthly air temperature estimates using the CRU data significantly reduced the errors; the MAE values for estimating monthly maximum air temperature range between 1.73 °C and 1.86 °C. Uncorrected land surface temperature generally performed better for estimating monthly minimum air temperature and the MAE values range from 1.18 °C to 1.89 °C. The suggested methodology on a monthly time scale may be applied in many data sparse areas to be used for regional environmental and agricultural studies that require high spatial resolution air temperature data.
Coexistence of Near-Field and Far-Field Sources: the Angular Resolution Limit
International Nuclear Information System (INIS)
Passive source localization is a well known inverse problem in which we convert the observed measurements into information about the direction of arrivals. In this paper we focus on the optimal resolution of such problem. More precisely, we propose in this contribution to derive and analyze the Angular Resolution Limit (ARL) for the scenario of mixed Near-Field (NF) and Far-Field (FF) Sources. This scenario is relevant to some realistic situations. We base our analysis on the Smith's equation which involves the Cramér-Rao Bound (CRB). This equation provides the theoretical ARL which is independent of a specific estimator. Our methodology is the following: first, we derive a closed-form expression of the CRB for the considered problem. Using these expressions, we can rewrite the Smith's equation as a 4-th order polynomial by assuming a small separation of the sources. Finally, we derive in closed-form the analytic ARL under or not the assumption of low noise variance. The obtained expression is compact and can provide useful qualitative informations on the behavior of the ARL
Artru, X; Honkavaara, K; Variola, A
1999-01-01
The interest in using optical transition radiation (OTR) in high energy (multiGeV) beam diagnostics has motivated theoretical and experimental investigations on the limitations brought by diffraction on the attainable resolution. This paper presents calculations of the diffraction effects in an optical set-up using OTR. The OTR diffraction pattern in a telescopic system is calculated taking into account the radial polarization of OTR. The obtained diffraction pattern is compared to the patterns obtained by other authors and the effects of different parameters on the shape and on the size of the OTR diffraction pattern are studied. The major role played by the radial polarization on the shape of the diffraction pattern is outlined. An alternative method to calculate the OTR diffraction pattern is also sketched
Quantum limit for two-dimensional resolution of two incoherent optical point sources
Ang, Shan Zheng; Tsang, Mankei
2016-01-01
We obtain the multiple-parameter quantum Cram\\'er-Rao bound for estimating the Cartesian components of the centroid and separation of two incoherent optical point sources using an imaging system with finite spatial bandwidth. Under quite general and realistic assumptions on the point-spread function of the imaging system, and for weak source strengths, we show that the Cram\\'er-Rao bounds for the x and y components of the separation are independent of the values of those components, which may be well-below the conventional Rayleigh resolution limit. We also propose two linear optics-based measurement methods that approach the quantum bound for the estimation of the Cartesian components of the separation once the centroid has been located. One of the methods is an interferometric scheme that approaches the quantum bound for sub-Rayleigh separations. The other method uses fiber coupling to attain the bound regardless of the distance between the two sources.
Temporal resolution limit estimation of x-ray streak cameras using a CsI photocathode
Energy Technology Data Exchange (ETDEWEB)
Li, Xiang; Gu, Li; Zong, Fangke; Zhang, Jingjin; Yang, Qinlao, E-mail: qlyang@szu.edu.cn [Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, Institute of Optoelectronics, Shenzhen University, Shenzhen 518060 (China)
2015-08-28
A Monte Carlo model is developed and implemented to calculate the characteristics of x-ray induced secondary electron (SE) emission from a CsI photocathode used in an x-ray streak camera. Time distributions of emitted SEs are investigated with an incident x-ray energy range from 1 to 30 keV and a CsI thickness range from 100 to 1000 nm. Simulation results indicate that SE time distribution curves have little dependence on the incident x-ray energy and CsI thickness. The calculated time dispersion within the CsI photocathode is about 70 fs, which should be the temporal resolution limit of x-ray streak cameras that use CsI as the photocathode material.
Energy Technology Data Exchange (ETDEWEB)
Kubo, Yugo, E-mail: kubo-yugo@sei.co.jp; Hamada, Kotaro
2015-10-15
The effect of sample thickness on the spatial resolution and minimum detection limit (MDL) has been investigated for field-emission electron probe microanalysis with wavelength dispersive X-ray spectroscopy (FE-EPMA–WDX). Indium gallium phosphide samples thinned to thicknesses of about 100, 130, 210, 310, and 430 nm provided effective thin-sample FE-EPMA–WDX in the resolution range of 40–350 nm and MDL range of 13,000–600 ppm (mass). A comparison of the FE-EPMA results for thin and bulk samples demonstrated that thin-sample FE-EPMA can achieve both higher sensitivity and better spatial resolution than is possible using bulk samples. Most of the X-rays that determine the MDL are generated in a surface region of the sample with a depth of approximately 300 nm. The spatial resolution and MDL can be tuned by the sample thickness. Furthermore, analysis of small amounts of Cl in SiO{sub 2} indicated that thin-sample FE-EPMA can realize a spatial resolution and MDL of 41 nm and 446 ppm at I{sub prob}=50 nA, respectively, whereas bulk-sample FE-EPMA offers a resolution of only 348 nm and MDL of 426 ppm. - Highlights: • Mechanism for FE-EPMA combining high spatial resolution with a low detection limit. • Spatial resolution and minimum detection limit controllable by sample thickness. • Achievement of a combined resolution and detection limit of 41 nm and 446 ppm. • Spatial resolution and detection limit for FE-EPMA–WDX and FE-SEM–EDX.
Aguilar, Isaac-Cesar; Kagan, David
2013-01-01
The sight of a broken bat in Major League Baseball can produce anything from a humorous dribbler in the infield to a frightening pointed projectile headed for the stands. Bats usually break at the weakest point, typically in the handle. Breaking happens because the wood gets bent beyond the breaking point due to the wave sent down the bat created…
Wolfe, Christopher Stuart
The idea that the spin degree of freedom of particles can be used to store and transport information has revolutionized the data storage industry and inspired a huge amount of research activity. Spin electronics, or spintronics, provides a plethora of potential improvements to conventional charge electronics that include increased functionality and energy efficiency. Scientists studying spintronics will need a multitude of characterization tools to sensitively detect spins in new materials and devices. There are already a handful of powerful techniques to image spin-related phenomena, but each has limitations. Magnetic resonance force microscopy, for example, offers sensitive detection of spin moments that are localized or nearly so but requires a high vacuum, cryogenic environment. Magnetometry based on nitrogen vacancy centers in diamond is a powerful approach, but requires the nitrogen vacancy center to be in very close contact to the spin system being studied to be able to measure the field generated by the system. Spin-polarized scanning tunneling microscopy provides perhaps the best demonstrated spatial resolution, but typically requires ultrahigh vacuum conditions and is limited to studying the surface of a sample. Traditional optical techniques such as Faraday or Kerr microscopy are limited in spatial resolution by the optical diffraction limit. In this dissertation I will present three new techniques we have developed to address some of these issues and to provide the community with new tools to help push forward spintronics and magnetism related research. I will start by presenting the first experimental demonstration of scanned spin-precession microscopy. This technique has the potential to turn any spin-sensitive detection technique into an imaging platform by providing the groundwork for incorporating a magnetic field gradient with that technique, akin to magnetic resonance imaging, and the mathematical tools to analyze the data and extract the local
Yamamoto, Seiichi; WATABE, Tadashi; IKEDA, Hayato; Kanai, Yasukazu; Watabe, Hiroshi; Ogata, Yoshimune; Kato, Katsuhiko; Hatazawa, Jun
2014-01-01
Objective Cerenkov-light imaging provides inherently high resolution because the light is emitted near the positron radionuclide. However, the magnitude for the high spatial resolution of Cerenkov-light imaging is unclear. Its potential molecular imaging applications also remain unclear. We developed an ultrahigh-resolution Cerenkov-light imaging system, measured its spatial resolution, and explored its applications to molecular imaging research. Methods Our Cerenkov-light imaging system cons...
Ribó, Josep M; El-Hachemi, Zoubir; Moyano, Albert; Blanco, Celia; Hochberg, David; 10.1089/ast.2012.0904
2013-01-01
The emergence of chirality in enantioselective autocatalysis for compounds unable to transform according to the Frank-like reaction network is discussed with respect to the controversial limited enantioselectivity (LES) model composed of coupled enantioselective and non-enantioselective autocatalyses. The LES model cannot lead to spontaneous mirror symmetry breaking (SMSB) either in closed systems with a homogeneous temperature distribution nor in closed systems with a stationary non-uniform temperature distribution. However, simulations of chemical kinetics in a two-compartment model demonstrate that SMSB may occur if both autocatalytic reactions are spatially separated at different temperatures in different compartments but coupled under the action of a continous internal flow. In such conditions the system can evolve, for certain reaction and system parameters, towards a chiral stationary state, i.e., the system is able to reach a bifurcation point leading to SMSB. Numerical simulations using reasonable ch...
International Nuclear Information System (INIS)
The concept of leak-before-break (LBB) has now-a-days replaced the traditional design basis event of double ended guillotine break (DEGB) to design the primary heat transport (PHT) piping system of the future generation nuclear reactors. Consequently, the LBB approach is adopted in the design of PHT system of India's future generation 500 MWe nuclear reactors. The LBB approach aims at the application of fracture mechanics principle to demonstrate that pipes are, in general, unlikely to experience DEGB without prior indication of leakage. It shows that a through wall leakage size cracks (LSC) in the pipe is stable under the maximum credible loading condition. This is to be shown for all the piping components, namely, straight pipes, elbows and branch tees in the entire PHT system. The present report details the LBB qualification of the straight pipe portions of the 500 MWe PHT pipe layout. The qualification is done through stability analysis of the pipes with postulated LSC by J-integral-tearing modulus and limit load method. The report has been split into five sections and two appendices. Section 1 describes the general methodology of the LBB analysis. Section 2 describes the evaluation of J-integrals by analytical estimation schemes. Section 3 details the finite element analysis of the pipes with postulated cracks to evaluate J-integral, limit load and crack opening area. Section 4 shows the critical loads evaluated by J-T method. Section 5 demonstrates the LBB qualification of the pipes by showing the necessary factors of safety. Appendix A describes in brief the analytical J-estimation schemes and appendix B compares the two methods to calculate tearing modulus. (author)
Veysi, Mehdi; Capolino, Filippo
2016-01-01
An azimuthally E-polarized vector beam (AEVB) has a salient feature that it contains a magnetic-dominant region within which electric field has a null and longitudinal magnetic field is maximum. Fresnel diffraction theory and plane-wave spectral (PWS) calculations are applied to quantify the field features of such a beam upon focusing through a lens. The diffraction-limited full width at half maximum (FWHM) of the beams longitudinal magnetic field intensity profile and complementary FWHM (CFWHM) of the beam's annular-shaped total electric field intensity profile are calculated at the lens's focal plane as a function of the lens's paraxial focal distance. Subsequently, we demonstrate, for the first time, that a very high resolution magnetic field at optical frequency with the total magnetic field FWHM of 0.23{\\lambda}(magnetic field spot size of 0.04{\\lambda}^2) can be achieved by placing a subwavelength dense dielectric Mie scatterer in the minimum-waist plane of a self-standing converging AEVB. The theory sh...
Possibilities and limitations of high-resolution mass spectrometry in life sciences
Arlinghaus, Heinrich F.
2008-12-01
We have applied time-of-flight secondary ion mass spectrometry (ToF-SIMS) and laser post-ionization secondary neutral mass spectrometry (laser-SNMS) to examine the immobilization process of PNA and its hybridization capability to unlabeled complementary DNA fragments, to characterize immobilized proteins, and to image intrinsic elements and molecules with subcellular spatial resolution in different types of frozen non-dehydrated biological samples. The possibilities and limitations of ToF-SIMS and laser-SNMS for imaging elements and molecules in biological samples are discussed. Furthermore possibilities for enhancing the detection sensitivity by using polyatomic and cluster primary ions and different laser post-ionization schemes, as well as ways of obtaining 3D molecular images from biological samples are described. The data shows that both ToF-SIMS and laser-SNMS are capable of imaging elements and molecules in complex biological samples and that they are very valuable tools in advancing applications in life sciences. It was found that cluster-ion bombardment is very useful for enhancing the molecular yield, while laser-SNMS resulted in much higher detection sensitivity for elements and specific molecules and is particularly well suited for imaging ultra-trace element concentrations in biological samples.
IKKalpha limits macrophage NF-kappaB activation and contributes to the resolution of inflammation.
Lawrence, Toby; Bebien, Magali; Liu, George Y; Nizet, Victor; Karin, Michael
2005-04-28
Inflammation and innate immunity involve signalling pathways leading to the production of inflammatory mediators. Usually such responses are self-limiting, but aberrant resolution of inflammation results in chronic diseases. Much attention has focused on pro-inflammatory signalling but little is known about the mechanisms that resolve inflammation. The IkappaB kinase (IKK) complex contains two catalytic subunits, IKKalpha and IKKbeta, and controls the activation of NF-kappaB transcription factors, which play a pivotal role in inflammation. Ample evidence indicates that IKKbeta mediates NF-kappaB activation in response to pro-inflammatory cytokines and microbial products. IKKalpha regulates an alternative pathway important for lymphoid organogenesis, but the role of IKKalpha in inflammation is unknown. Here we describe a new role for IKKalpha in the negative regulation of macrophage activation and inflammation. IKKalpha contributes to suppression of NF-kappaB activity by accelerating both the turnover of the NF-kappaB subunits RelA and c-Rel, and their removal from pro-inflammatory gene promoters. Inactivation of IKKalpha in mice enhances inflammation and bacterial clearance. Hence, the two IKK catalytic subunits have evolved opposing but complimentary roles needed for the intricate control of inflammation and innate immunity. PMID:15858576
Castro-Santos, Theodore; Sanz-Ronda, Francisco Javier; Ruiz-Legazpi, Jorge
2013-01-01
Sprinting behavior of free-ranging fish has long been thought to exceed that of captive fish. Here we present data from wild-caught brook trout (Salvelinus fontinalis) and brown trout (Salmo trutta), volitionally entering and sprinting against high-velocity flows in an open-channel flume. Performance of the two species was nearly identical, with the species attaining absolute speeds > 25 body lengths·s−1. These speeds far exceed previously published observations for any salmonid species and contribute to the mounting evidence that commonly accepted estimates of swimming performance are low. Brook trout demonstrated two distinct modes in the relationship between swim speed and fatigue time, similar to the shift from prolonged to sprint mode described by other authors, but in this case occurring at speeds > 19 body lengths·s−1. This is the first demonstration of multiple modes of sprint swimming at such high swim speeds. Neither species optimized for distance maximization, however, indicating that physiological limits alone are poor predictors of swimming performance. By combining distributions of volitional swim speeds with endurance, we were able to account for >80% of the variation in distance traversed by both species.
Pei, Yanbo; Wei, Ming-Yuan; Cheng, Bingbing; Liu, Yuan; Xie, Zhiwei; Nguyen, Kytai; Yuan, Baohong
2014-04-01
Fluorescence imaging in deep tissue with high spatial resolution is highly desirable because it can provide details about tissue's structural, functional, and molecular information. Unfortunately, current fluorescence imaging techniques are limited either in penetration depth (microscopy) or spatial resolution (diffuse light based imaging) as a result of strong light scattering in deep tissue. To overcome this limitation, we developed an ultrasound-switchable fluorescence (USF) imaging technique whereby ultrasound was used to switch on/off the emission of near infrared (NIR) fluorophores. We synthesized and characterized unique NIR USF contrast agents. The excellent switching properties of these agents, combined with the sensitive USF imaging system developed in this study, enabled us to image fluorescent targets in deep tissue with spatial resolution beyond the acoustic diffraction limit.
Spatial resolution limits for the isotropic-3D PET detector X’tal cube
Energy Technology Data Exchange (ETDEWEB)
Yoshida, Eiji, E-mail: rush@nirs.go.jp; Tashima, Hideaki; Hirano, Yoshiyuki; Inadama, Naoko; Nishikido, Fumihiko; Murayama, Hideo; Yamaya, Taiga
2013-11-11
Positron emission tomography (PET) has become a popular imaging method in metabolism, neuroscience, and molecular imaging. For dedicated human brain and small animal PET scanners, high spatial resolution is needed to visualize small objects. To improve the spatial resolution, we are developing the X’tal cube, which is our new PET detector to achieve isotropic 3D positioning detectability. We have shown that the X’tal cube can achieve 1 mm{sup 3} uniform crystal identification performance with the Anger-type calculation even at the block edges. We plan to develop the X’tal cube with even smaller 3D grids for sub-millimeter crystal identification. In this work, we investigate spatial resolution of a PET scanner based on the X’tal cube using Monte Carlo simulations for predicting resolution performance in smaller 3D grids. For spatial resolution evaluation, a point source emitting 511 keV photons was simulated by GATE for all physical processes involved in emission and interaction of positrons. We simulated two types of animal PET scanners. The first PET scanner had a detector ring 14.6 cm in diameter composed of 18 detectors. The second PET scanner had a detector ring 7.8 cm in diameter composed of 12 detectors. After the GATE simulations, we converted the interacting 3D position information to digitalized positions for realistic segmented crystals. We simulated several X’tal cubes with cubic crystals from (0.5 mm){sup 3} to (2 mm){sup 3} in size. Also, for evaluating the effect of DOI resolution, we simulated several X’tal cubes with crystal thickness from (0.5 mm){sup 3} to (9 mm){sup 3}. We showed that sub-millimeter spatial resolution was possible using cubic crystals smaller than (1.0 mm){sup 3} even with the assumed physical processes. Also, the weighted average spatial resolutions of both PET scanners with (0.5 mm){sup 3} cubic crystals were 0.53 mm (14.6 cm ring diameter) and 0.48 mm (7.8 cm ring diameter). For the 7.8 cm ring diameter, spatial
International Nuclear Information System (INIS)
The angular resolution of long-exposure images from ground-based telescopes equipped with laser guide star adaptive optics systems is fundamentally limited by the the accuracy with which the tip-tilt aberrations introduced by the atmosphere can be corrected. Assuming that a natural star is used as the tilt reference, the residual error due to tilt anisoplanatism can significantly degrade the long-exposure resolution even if the tilt reference star is separated from the object being imaged by a small angle. Given the observed distribution of stars in the sky, the need to find a tilt reference star quite close to the object restricts the fraction of the sky over which long-exposure images with diffraction limited resolution can be obtained. In this paper, the authors present a comprehensive performance analysis of tip-tilt compensation systems that use a natural star as a tilt reference, taking into account properties of the atmosphere and of the Galactic stellar populations, and optimizing over the system operating parameters to determine the fundamental limits to the long-exposure resolution. Their results show that for a ten meter telescope on Mauna Kea, if the image of the tilt reference star is uncorrected, about half the sky can be imaged in the V band with long-exposure resolution less than 60 milli-arc-seconds (mas), while if the image of the tilt reference star is fully corrected, about half the sky can be imaged in the V band with long-exposure resolution less than 16 mas. Furthermore, V band images long-exposure resolution of less than 16 mas may be obtained with a ten meter telescope on Mauna Kea for unresolved objects brighter than magnitude 22 that are fully corrected by a laser guide star adaptive optics system. This level of resolution represents about 70% of the diffraction limit of a ten meter telescope in the V band and is more than a factor of 45 better than the median seeing in the V band on Mauna Kea
CT energy weighting in the presence of scatter and limited energy resolution
Energy Technology Data Exchange (ETDEWEB)
Schmidt, Taly Gilat [Department of Biomedical Engineering, Marquette University, Milwaukee, Wisconsin 53201 (United States)
2010-03-15
Purpose: Energy-resolved CT has the potential to improve the contrast-to-noise ratio (CNR) through optimal weighting of photons detected in energy bins. In general, optimal weighting gives higher weight to the lower energy photons that contain the most contrast information. However, low-energy photons are generally most corrupted by scatter and spectrum tailing, an effect caused by the limited energy resolution of the detector. This article first quantifies the effects of spectrum tailing on energy-resolved data, which may also be beneficial for material decomposition applications. Subsequently, the combined effects of energy weighting, spectrum tailing, and scatter are investigated through simulations. Methods: The study first investigated the effects of spectrum tailing on the estimated attenuation coefficients of homogeneous slab objects. Next, the study compared the CNR and artifact performance of images simulated with varying levels of scatter and spectrum tailing effects, and reconstructed with energy integrating, photon-counting, and two optimal linear weighting methods: Projection-based and image-based weighting. Realistic detector energy-response functions were simulated based on a previously proposed model. The energy-response functions represent the probability that a photon incident on the detector at a particular energy will be detected at a different energy. Realistic scatter was simulated with Monte Carlo methods. Results: Spectrum tailing resulted in a negative shift in the estimated attenuation coefficient of slab objects compared to an ideal detector. The magnitude of the shift varied with material composition, increased with material thickness, and decreased with photon energy. Spectrum tailing caused cupping artifacts and CT number inaccuracies in images reconstructed with optimal energy weighting, and did not impact images reconstructed with photon counting weighting. Spectrum tailing did not significantly impact the CNR in reconstructed images
CT energy weighting in the presence of scatter and limited energy resolution
International Nuclear Information System (INIS)
Purpose: Energy-resolved CT has the potential to improve the contrast-to-noise ratio (CNR) through optimal weighting of photons detected in energy bins. In general, optimal weighting gives higher weight to the lower energy photons that contain the most contrast information. However, low-energy photons are generally most corrupted by scatter and spectrum tailing, an effect caused by the limited energy resolution of the detector. This article first quantifies the effects of spectrum tailing on energy-resolved data, which may also be beneficial for material decomposition applications. Subsequently, the combined effects of energy weighting, spectrum tailing, and scatter are investigated through simulations. Methods: The study first investigated the effects of spectrum tailing on the estimated attenuation coefficients of homogeneous slab objects. Next, the study compared the CNR and artifact performance of images simulated with varying levels of scatter and spectrum tailing effects, and reconstructed with energy integrating, photon-counting, and two optimal linear weighting methods: Projection-based and image-based weighting. Realistic detector energy-response functions were simulated based on a previously proposed model. The energy-response functions represent the probability that a photon incident on the detector at a particular energy will be detected at a different energy. Realistic scatter was simulated with Monte Carlo methods. Results: Spectrum tailing resulted in a negative shift in the estimated attenuation coefficient of slab objects compared to an ideal detector. The magnitude of the shift varied with material composition, increased with material thickness, and decreased with photon energy. Spectrum tailing caused cupping artifacts and CT number inaccuracies in images reconstructed with optimal energy weighting, and did not impact images reconstructed with photon counting weighting. Spectrum tailing did not significantly impact the CNR in reconstructed images
Using x-ray computed tomography in hydrology: Systems, resolutions, and limitations
DEFF Research Database (Denmark)
Wildenschild, Dorthe; Hopmans, J.W.; Vaz, C.M.P.;
2002-01-01
possible to resolve individual pores and to delineate air-water interfacial contacts. This kind of resolution provides a novel opportunity to follow the dynamic flow behavior on the pore scale and to verify new theoretical and numerical modeling approaches. (C) 2002 Elsevier Science Ltd. All rights...
An assessment of the resolution limitation due to radiation-damage in X-ray diffraction microscopy
Energy Technology Data Exchange (ETDEWEB)
Howells, M.R. [Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States)], E-mail: mrhowells@lbl.gov; Beetz, T. [Department of Physics, State University of New York, Stony Brook, NY 11794 (United States); Chapman, H.N. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States); Cui, C. [Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Holton, J.M. [Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158-2330 (United States); Jacobsen, C.J.; Kirz, J. [Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Department of Physics, State University of New York, Stony Brook, NY 11794 (United States); Lima, E. [Department of Physics, State University of New York, Stony Brook, NY 11794 (United States); Marchesini, S. [Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Miao, H.; Sayre, D. [Department of Physics, State University of New York, Stony Brook, NY 11794 (United States); Shapiro, D.A. [Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Spence, J.C.H. [Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Department of Physics and Astronomy, Arizona State University, Tempe, AZ 85287-1504 (United States); Starodub, D. [Department of Physics and Astronomy, Arizona State University, Tempe, AZ 85287-1504 (United States)
2009-03-15
X-ray diffraction microscopy (XDM) is a new form of X-ray imaging that is being practiced at several third-generation synchrotron-radiation X-ray facilities. Nine years have elapsed since the technique was first introduced and it has made rapid progress in demonstrating high-resolution three-dimensional imaging and promises few-nanometer resolution with much larger samples than can be imaged in the transmission electron microscope. Both life- and materials-science applications of XDM are intended, and it is expected that the principal limitation to resolution will be radiation damage for life science and the coherent power of available X-ray sources for material science. In this paper we address the question of the role of radiation damage. We use a statistical analysis based on the so-called 'dose fractionation theorem' of Hegerl and Hoppe to calculate the dose needed to make an image of a single life-science sample by XDM with a given resolution. We find that the needed dose scales with the inverse fourth power of the resolution and present experimental evidence to support this finding. To determine the maximum tolerable dose we have assembled a number of data taken from the literature plus some measurements of our own which cover ranges of resolution that are not well covered otherwise. The conclusion of this study is that, based on the natural contrast between protein and water and 'Rose-criterion' image quality, one should be able to image a frozen-hydrated biological sample using XDM at a resolution of about 10 nm.
An assessment of the resolution limitation due to radiation-damage in X-ray diffraction microscopy
International Nuclear Information System (INIS)
X-ray diffraction microscopy (XDM) is a new form of X-ray imaging that is being practiced at several third-generation synchrotron-radiation X-ray facilities. Nine years have elapsed since the technique was first introduced and it has made rapid progress in demonstrating high-resolution three-dimensional imaging and promises few-nanometer resolution with much larger samples than can be imaged in the transmission electron microscope. Both life- and materials-science applications of XDM are intended, and it is expected that the principal limitation to resolution will be radiation damage for life science and the coherent power of available X-ray sources for material science. In this paper we address the question of the role of radiation damage. We use a statistical analysis based on the so-called 'dose fractionation theorem' of Hegerl and Hoppe to calculate the dose needed to make an image of a single life-science sample by XDM with a given resolution. We find that the needed dose scales with the inverse fourth power of the resolution and present experimental evidence to support this finding. To determine the maximum tolerable dose we have assembled a number of data taken from the literature plus some measurements of our own which cover ranges of resolution that are not well covered otherwise. The conclusion of this study is that, based on the natural contrast between protein and water and 'Rose-criterion' image quality, one should be able to image a frozen-hydrated biological sample using XDM at a resolution of about 10 nm.
Yu, Wookyung; Baxa, Michael C; Gagnon, Isabelle; Freed, Karl F; Sosnick, Tobin R
2016-04-26
The relationship between folding cooperativity and downhill, or barrier-free, folding of proteins under highly stabilizing conditions remains an unresolved topic, especially for proteins such as λ-repressor that fold on the microsecond timescale. Under aqueous conditions where downhill folding is most likely to occur, we measure the stability of multiple H bonds, using hydrogen exchange (HX) in a λYA variant that is suggested to be an incipient downhill folder having an extrapolated folding rate constant of 2 × 10(5) s(-1) and a stability of 7.4 kcal·mol(-1) at 298 K. At least one H bond on each of the three largest helices (α1, α3, and α4) breaks during a common unfolding event that reflects global denaturation. The use of HX enables us to both examine folding under highly stabilizing, native-like conditions and probe the pretransition state region for stable species without the need to initiate the folding reaction. The equivalence of the stability determined at zero and high denaturant indicates that any residual denatured state structure minimally affects the stability even under native conditions. Using our ψ analysis method along with mutational ϕ analysis, we find that the three aforementioned helices are all present in the folding transition state. Hence, the free energy surface has a sufficiently high barrier separating the denatured and native states that folding appears cooperative even under extremely stable and fast folding conditions. PMID:27078098
Bali, G S; Lippert, T; Neff, H; Prkacin, Z; Schilling, K; Bali, Gunnar S; Dussel, Thomas; Lippert, Thomas; Neff, Hartmut; Prkacin, Zdravko; Schilling, Klaus
2006-01-01
We numerically investigate the transition of the static quark-antiquark string into a static-light meson-antimeson system. Improving noise reduction techniques, we are able to resolve the signature of string breaking dynamics for Nf=2 lattice QCD at zero temperature. We discuss the lattice techniques used and present results on energy levels and mixing angle of the static two-state system. We visualize the action density distribution in the region of string breaking as a function of the static colour source-antisource separation. The results can be related to properties of quarkonium systems.
Limitations of anti-scatter grids when used with high resolution image detectors.
Singh, V; Jain, A; Bednarek, D R; Rudin, S
2014-03-19
Anti-scatter grids are used in fluoroscopic systems to improve image quality by absorbing scattered radiation. A stationary Smit Rontgen X-ray grid (line density: 70 lines/cm, grid ratio: 13:1) was used with a flat panel detector (FPD) of pixel size 194 micron and a high-resolution CMOS detector, the Dexela 1207 with pixel size of 75 microns. To investigate the effectiveness of the grid, a simulated artery block was placed in a modified uniform frontal head phantom and imaged with both the FPD and the Dexela for an approximately 15 × 15 cm field of view (FOV). The contrast improved for both detectors with the grid. The contrast-to-noise ratio (CNR) does not increase as much in the case of the Dexela as it improves in the case of the FPD. Since the total noise in a single frame increases substantially for the Dexela compared to the FPD when the grid is used, the CNR is degraded. The increase in the quantum noise per frame would be similar for both detectors when the grid is used due to the attenuation of radiation, but the fixed pattern noise caused by the grid was substantially higher for the Dexela compared to the FPD and hence caused a severe reduction of CNR. Without further corrective methods this grid should not be used with high-resolution fluoroscopic detectors because the CNR does not improve significantly and the visibility of low contrast details may be reduced. Either an anti-scatter grid of different design or an additional image processing step when using a similar grid would be required to deal with the problem of scatter for high resolution detectors and the structured noise of the grid pattern. PMID:25309101
Limitations of anti-scatter grids when used with high resolution image detectors
Singh, V.; Jain, A.; Bednarek, D. R.; Rudin, S.
2014-03-01
Anti-scatter grids are used in fluoroscopic systems to improve image quality by absorbing scattered radiation. A stationary Smit Rontgen X-ray grid (line density: 70 lines/cm, grid ratio: 13:1) was used with a flat panel detector (FPD) of pixel size 194 micron and a high-resolution CMOS detector, the Dexela 1207 with pixel size of 75 microns. To investigate the effectiveness of the grid, a simulated artery block was placed in a modified uniform frontal head phantom and imaged with both the FPD and the Dexela for an approximately 15 x 15 cm field of view (FOV). The contrast improved for both detectors with the grid. The contrast-to-noise ratio (CNR) does not increase as much in the case of the Dexela as it improves in the case of the FPD. Since the total noise in a single frame increases substantially for the Dexela compared to the FPD when the grid is used, the CNR is degraded. The increase in the quantum noise per frame would be similar for both detectors when the grid is used due to the attenuation of radiation, but the fixed pattern noise caused by the grid was substantially higher for the Dexela compared to the FPD and hence caused a severe reduction of CNR. Without further corrective methods this grid should not be used with high-resolution fluoroscopic detectors because the CNR does not improve significantly and the visibility of low contrast details may be reduced. Either an anti-scatter grid of different design or an additional image processing step when using a similar grid would be required to deal with the problem of scatter for high resolution detectors and the structured noise of the grid pattern.
Pump-probe Kelvin-probe force microscopy: Principle of operation and resolution limits
International Nuclear Information System (INIS)
Knowledge on surface potential dynamics is crucial for understanding the performance of modern-type nanoscale devices. We describe an electrical pump-probe approach in Kelvin-probe force microscopy that enables a quantitative measurement of dynamic surface potentials at nanosecond-time and nanometer-length scales. Also, we investigate the performance of pump-probe Kelvin-probe force microscopy with respect to the relevant experimental parameters. We exemplify a measurement on an organic field effect transistor that verifies the undisturbed functionality of our pump-probe approach in terms of simultaneous and quantitative mapping of topographic and electronic information at a high lateral and temporal resolution
Pump-probe Kelvin-probe force microscopy: Principle of operation and resolution limits
Energy Technology Data Exchange (ETDEWEB)
Murawski, J.; Graupner, T.; Milde, P., E-mail: peter.milde@tu-dresden.de; Raupach, R.; Zerweck-Trogisch, U.; Eng, L. M. [Institute of Applied Physics, Technische Universität Dresden, D-01062 Dresden (Germany)
2015-10-21
Knowledge on surface potential dynamics is crucial for understanding the performance of modern-type nanoscale devices. We describe an electrical pump-probe approach in Kelvin-probe force microscopy that enables a quantitative measurement of dynamic surface potentials at nanosecond-time and nanometer-length scales. Also, we investigate the performance of pump-probe Kelvin-probe force microscopy with respect to the relevant experimental parameters. We exemplify a measurement on an organic field effect transistor that verifies the undisturbed functionality of our pump-probe approach in terms of simultaneous and quantitative mapping of topographic and electronic information at a high lateral and temporal resolution.
Building an atlas of gene expression driving kidney development: pushing the limits of resolution.
Potter, S Steven; Brunskill, Eric W
2014-04-01
Changing gene expression patterns is the essential driver of developmental processes. Growth factors, micro-RNAs, long intergenic noncoding RNAs, and epigenetic marks, such as DNA methylation and histone modifications, all work by impacting gene expression. The key features of developing cells, including their ability to communicate with others, are defined primarily by their gene-expression profiles. It is therefore clear that a gene-expression atlas of the developing kidney can provide a useful tool for the developmental nephrology research community. Toward this end, the GenitoUrinary Development Molecular Anatomy Project (GUDMAP) consortium has worked to create an atlas of the changing gene-expression patterns that drive kidney development. In this article, the global gene-expression profiling strategies of GUDMAP are reviewed. The initial work used laser-capture microdissection to purify multiple compartments of the developing kidney, including cap mesenchyme, renal vesicle, S-shaped bodies, proximal tubules, and more, which were then gene-expression profiled using microarrays. Resolution of the atlas was then improved by using transgenic mice with specific cell types labeled with green fluorescent protein (GFP), allowing their purification and profiling. In addition, RNA-Seq replaced microarrays. Currently, the atlas is being pushed to the single-cell resolution using microfluidic approaches that allow high-throughput RNA-Seq analysis of hundreds of individual cells. Results can identify novel types of cells and define interesting heterogeneities present within cell populations. PMID:23996451
Limits on the spatial resolution of monolithic scintillators read out by APD arrays.
van der Laan, D J Jan; Maas, Marnix C; Bruyndonckx, Peter; Schaart, Dennis R
2012-10-21
Cramér-Rao theory can be used to derive the lower bound on the spatial resolution achievable with position-sensitive scintillation detectors as a function of the detector geometry and the pertinent physical properties of the scintillator, the photosensor and the readout electronics. Knowledge of the Cramér-Rao lower bound (CRLB) can for example be used to optimize the detector design and to test the performance of the method used to derive position information from the detector signals. Here, this approach is demonstrated for monolithic scintillator detectors for positron emission tomography. Two detector geometries are investigated: a 20 × 10 × 10 mm(3) and a 20 × 10 × 20 mm(3) monolithic LYSO:Ce(3+) crystal read out by one or two Hamamatsu S8550SPL avalanche photodiode (APD) arrays, respectively. The results indicate that in these detectors the CRLB is primarily determined by the APD excess noise factor and the number of scintillation photons detected. Furthermore, it is shown that the use of a k-nearest neighbor (k-NN) algorithm for position estimation allows the experimentally obtained spatial resolution to closely approach the CRLB. The approach outlined in this work can in principle be applied to any scintillation detector in which position information is encoded in the distribution of the scintillation light over multiple photosensor elements. PMID:23001515
Limits on the spatial resolution of monolithic scintillators read out by APD arrays
International Nuclear Information System (INIS)
Cramér–Rao theory can be used to derive the lower bound on the spatial resolution achievable with position-sensitive scintillation detectors as a function of the detector geometry and the pertinent physical properties of the scintillator, the photosensor and the readout electronics. Knowledge of the Cramér–Rao lower bound (CRLB) can for example be used to optimize the detector design and to test the performance of the method used to derive position information from the detector signals. Here, this approach is demonstrated for monolithic scintillator detectors for positron emission tomography. Two detector geometries are investigated: a 20 × 10 × 10 mm3 and a 20 × 10 × 20 mm3 monolithic LYSO:Ce3+ crystal read out by one or two Hamamatsu S8550SPL avalanche photodiode (APD) arrays, respectively. The results indicate that in these detectors the CRLB is primarily determined by the APD excess noise factor and the number of scintillation photons detected. Furthermore, it is shown that the use of a k-nearest neighbor (k-NN) algorithm for position estimation allows the experimentally obtained spatial resolution to closely approach the CRLB. The approach outlined in this work can in principle be applied to any scintillation detector in which position information is encoded in the distribution of the scintillation light over multiple photosensor elements. (paper)
Indian Academy of Sciences (India)
Emilian Dudas
2009-01-01
We review the various mechanisms of supersymmetry breaking and its trans-mission to the observable sector. We argue that hybrid models where gauge dominates over gravity mediation, but gravity provides the main contributions to the Higgs sector masses and the neutralino mass, are able to combine the advantages and reduce the disadvantages of the two transmission mechanisms.
Resolution of the time dependent Pn equations by a Godunov type scheme having the diffusion limit
International Nuclear Information System (INIS)
We consider the Pn model to approximate the transport equation in one dimension of space. In a diffusive regime, the solution of this system is solution of a diffusion equation. We are looking for a numerical scheme having the diffusion limit property: in a diffusive regime, it gives the solution of the limiting diffusion equation on a mesh at the diffusion scale. The numerical scheme proposed is an extension of the Godunov type scheme proposed by L. Gosse to solve the P1 model without absorption term. Moreover, it has the well-balanced property: it preserves the steady solutions of the system. (authors)
An assessment of the resolution limitation due to radiation-damage in x-ray diffraction microscopy
Howells, M R; Chapman, H N; Cui, C; Holton, J M; Jacobsen, C J; Lima, J K E; Marchesini, S; Miao, H; Sayre, D; Shapiro, D A; Spence, J C H
2005-01-01
X-ray diffraction microscopy (XDM) is a new form of x-ray imaging that is being practiced at several third-generation synchrotron-radiation x-ray facilities. Although only five years have elapsed since the technique was first introduced, it has made rapid progress in demonstrating high-resolution threedimensional imaging and promises few-nm resolution with much larger samples than can be imaged in the transmission electron microscope. Both life- and materials-science applications of XDM are intended, and it is expected that the principal limitation to resolution will be radiation damage for life science and the coherent power of available x-ray sources for material science. In this paper we address the question of the role of radiation damage. We use a statistical analysis based on the so-called "dose fractionation theorem" of Hegerl and Hoppe to calculate the dose needed to make an image of a lifescience sample by XDM with a given resolution. We conclude that the needed dose scales with the inverse fourth po...
International Nuclear Information System (INIS)
Spatial resolution limit is a very important parameter of an imaging system that should be taken into consideration before examination of any object. The objectives of this work are the determination of a neutron imaging system's response in terms of spatial resolution. The proposed procedure is based on establishment of the Modulation Transfer Function (MTF). The imaging system being studied is based on a high sensitivity CCD neutron camera (2×10−5 lx at f1.4). The neutron beam used is from the horizontal beam port (H.6) of the Algerian Es-Salam research reactor. Our contribution is on the MTF determination by proposing an accurate edge identification method and a line spread function undersampling problem-resolving procedure. These methods and procedure are integrated into a MatLab code. The methods, procedures and approaches proposed in this work are available for any other neutron imaging system and allow for judging the ability of a neutron imaging system to produce spatial (internal details) properties of any object under examination. - Highlights: ► Determination of spatial response of a neutron imaging system. ► Ability of a neutron imaging system to reproduce spatial properties of any object. ► Spatial resolution limits measurement using MTF with the slanted edge method. ► Accurate edge identification and line spread function sampling improvement. ► Development of a MatLab code to compute automatically the MTF.
International Nuclear Information System (INIS)
We have studied spin observables in the three-body break-up reaction in deuteron–deuteron scattering in the phase-space regime that corresponds to the quasi-free deuteron–proton scattering process with the neutron as spectator. The data are compared to measurements of the elastic deuteron–proton scattering process and state-of-the-art Faddeev calculations. The results for iT11 and T22 for the quasi-free scattering data agree very well with previously published elastic-scattering data. A significant discrepancy is found for T20, which could point to a break-down of the quasi-free assumption
High-resolution digital 3D models of Algar do Penico Chamber: limitations, challenges, and potential
Ivo Silvestre M.Sc.; José I. Rodrigues PhD; Mauro Figueiredo PhD; Cristina Veiga-Pires PhD
2015-01-01
The study of karst and its geomorphological structures is important for understanding the relationships between hydrology and climate over geological time. In that context, we conducted a terrestrial laser-scan survey to map geomorphological structures in the karst cave of Algar do Penico in southern Portugal. The point cloud data set obtained was used to generate 3D meshes with different levels of detail, allowing the limitations of mapping capabilities to be explored. In addition to cave...
High-resolution digital 3D models of Algar do Penico Chamber: limitations, challenges, and potential
Silvestre, Ivo; Rodrigues, J. I.; Figueiredo, Mauro; C. Veiga-Pires
2015-01-01
The study of karst and its geomorphological structures is important for understanding the relationships between hydrology and climate over geological time. In that context, we conducted a terrestrial laser-scan survey to map geomorphological structures in the karst cave of Algar do Penico in southern Portugal. The point cloud data set obtained was used to generate 3D meshes with different levels of detail, allowing the limitations of mapping capabilities to be explored. In addition to cav...
Veysi, Mehdi; Guclu, Caner; Capolino, Filippo
2016-01-01
An azimuthally E-polarized vector beam (AEVB) has a salient feature that it contains a magnetic-dominant region within which electric field has a null and longitudinal magnetic field is maximum. Fresnel diffraction theory and plane-wave spectral (PWS) calculations are applied to quantify the field features of such a beam upon focusing through a lens. The diffraction-limited full width at half maximum (FWHM) of the beams longitudinal magnetic field intensity profile and complementary FWHM (CFW...
Sanna, N; Massi, F; Cresci, G; Origlia, L
2014-01-01
HIRES, a high resolution spectrometer, is one of the first five instruments foreseen in the ESO roadmap for the E-ELT. This spectrograph should ideally provide full spectral coverage from the UV limit to 2.5 microns, with a resolving power from R$\\sim$10,000 to R$\\sim$100,000. At visual/blue wavelengths, where the adaptive optics (AO) cannot provide an efficient light-concentration, HIRES will necessarily be a bulky, seeing-limited instrument. The fundamental question, which we address in this paper, is whether the same approach should be adopted in the near-infrared range, or HIRES should only be equipped with compact infrared module(s) with a much smaller aperture, taking advantage of an AO-correction. The main drawbacks of a seeing-limited instrument at all wavelengths are: \\textit{i)} Lower sensitivities at wavelengths dominated by thermal background (red part of the K-band). \\textit{ii)} Much higher volumes and costs for the IR spectrograph module(s). The main drawbacks of using smaller, AO-fed IR module...
De Boever, Wesley; Derluyn, Hannelore; Van Stappen, Jeroen; Dewanckele, Jan; Bultreys, Tom; Boone, Matthieu; De Schryver, Thomas; De Kock, Tim; Skjonsfjell, ETB; Diaz, Ana; Holler, Mirko; Cnudde, Veerle
2015-01-01
Characterization of microporous, clay-sized particles in natural stone is essential for the understanding of their dynamics. These processes are importand in the fields of oil and gas, groundwater, building stone weathering and soil science. Methods such as X-ray micro-computed tomography is an excellent tool to study features larger than or just under 1 μm, but below the 400 nm limit, the technique falls short. Although destructive methods exists (e.g. FIB/SEM), non-destructive imaging at th...
DEFF Research Database (Denmark)
Strand, Anete Mikkala Camille
2016-01-01
The chapter elaborates on how to deal with one of the major challenges facing organizations worldwide; Stress. The Break enacts a quantum approach to meet the challenges by proposing a combination of three different quantum storytelling technologies; protreptic mentoring, walking and material sto...... provider and witness to your elaborations. It’s really that simple! The chapter concludes towards a set of Dogmas for future reference in addressing these challenges in this manner....
Vincenti, M A; Cappeddu, M G; Akozbek, Neset; Bloemer, M J; Scalora, M
2008-01-01
We theoretically demonstrate negative refraction and sub-wavelength resolution below the diffraction limit in the UV and extreme UV ranges using semiconductors. The metal-like re-sponse of typical semiconductors such as GaAs or GaP makes it possible to achieve negative refraction and super-guiding in resonant semiconductor/dielectric multilayer stacks, similar to what has been demonstrated in metallo-dielectric photonic band gap structures. The exploita-tion of this basic property in semiconductors raises the possibility of new, yet-untapped ap-plications in the UV and soft x-ray ranges.
Vincenti, M. A.; Orazio, A. D; Cappeddu, M. G.; Akozbek, Neset; Bloemer, M. J.; Scalora, M.
2008-01-01
We theoretically demonstrate negative refraction and sub-wavelength resolution below the diffraction limit in the UV and extreme UV ranges using semiconductors. The metal-like re-sponse of typical semiconductors such as GaAs or GaP makes it possible to achieve negative refraction and super-guiding in resonant semiconductor/dielectric multilayer stacks, similar to what has been demonstrated in metallo-dielectric photonic band gap structures. The exploita-tion of this basic property in semicond...
International Nuclear Information System (INIS)
Electro-optic sampling (EOS) is widely used as a technique to measure THz-domain electric field pulses such asthe self-fields of femtosecond electron beams. We present an EOS-based approach for single-shot spectral measurement that excels in simplicity (compatible with fiber integration) and bandwidth coverage (overcomes the laser bandwidth limitation), allowing few-fs electron beams or single-cycle THz pulses to be characterized with conventional picosecond probes. It is shown that the EOS-induced optical sidebands on the narrow-bandwidth optical probe are spectrally-shifted replicas of the THz pulse. An experimental demonstration on a 0-3 THz source is presented.
Sukhanova, Maria V; Abrakhi, Sanae; Joshi, Vandana; Pastre, David; Kutuzov, Mikhail M; Anarbaev, Rashid O; Curmi, Patrick A; Hamon, Loic; Lavrik, Olga I
2016-04-01
PARP1 and PARP2 are implicated in the synthesis of poly(ADP-ribose) (PAR) after detection of DNA damage. The specificity of PARP1 and PARP2 interaction with long DNA fragments containing single- and/or double-strand breaks (SSBs and DSBs) have been studied using atomic force microscopy (AFM) imaging in combination with biochemical approaches. Our data show that PARP1 localizes mainly on DNA breaks and exhibits a slight preference for nicks over DSBs, although the protein has a moderately high affinity for undamaged DNA. In contrast to PARP1, PARP2 is mainly detected at a single DNA nick site, exhibiting a low level of binding to undamaged DNA and DSBs. The enhancement of binding affinity of PARP2 for DNA containing a single nick was also observed using fluorescence titration. AFM studies reveal that activation of both PARPs leads to the synthesis of highly branched PAR whose size depends strongly on the presence of SSBs and DSBs for PARP1 and of SSBs for PARP2. The initial affinity between the PARP1, PARP2 and the DNA damaged site appears to influence both the size of the PAR synthesized and the time of residence of PARylated PARP1 and PARP2 on DNA damages. PMID:26673720
Directory of Open Access Journals (Sweden)
Franjo Šumanovac
2007-12-01
Full Text Available The block model in a homogenous environment can generally serve for presentation of some geological models: changes of facies, changes of rock compactness-fragmentation, underground cavities, bauxite deposits, etc. Therefore, on the block model of increased resistivities in a homogenous environment of low resistivity, the potentials of the electrical tomography method were tested for the purpose of their detection. Regarding potentials of block detection, resolution methods depend on: depth of block location, ratio between block resistivity and the environment in which it is located as well as applied survey geometry, i.e. electrode array. Thus the analyses carried out for the most frequently used electrode arrays in the investigations are the following: the Wenner, Wenner-Schlumberger, dipole-dipole and pole-pole arrays. For each array, maximum depths at which a block can be detected relative to the ratio between block resistivity and parent rock environment were analyzed. The results are shown in the two-dimensional graphs, where the ratio between the block resistivity and the environment is shown on the X-axis, and the resolution depth on the Y-axis, after which the curves defining the resolution limits were drawn. These graphs have a practical use, since they enable a fast, simple determination of potentials of the method application on a specific geological model.
High-resolution digital 3D models of Algar do Penico Chamber: limitations, challenges, and potential
Directory of Open Access Journals (Sweden)
Ivo Silvestre M.Sc.
2015-01-01
Full Text Available The study of karst and its geomorphological structures is important for understanding the relationships between hydrology and climate over geological time. In that context, we conducted a terrestrial laser-scan survey to map geomorphological structures in the karst cave of Algar do Penico in southern Portugal. The point cloud data set obtained was used to generate 3D meshes with different levels of detail, allowing the limitations of mapping capabilities to be explored. In addition to cave mapping, the study focuses on 3D-mesh analysis, including the development of two algorithms for determination of stalactite extremities and contour lines, and on the interactive visualization of 3D meshes on the Web. Data processing and analysis were performed using freely available open-source software. For interactive visualization, we adopted a framework based on Web standards X3D, WebGL, and X3DOM. This solution gives both the general public and researchers access to 3D models and to additional data produced from map tools analyses through a web browser, without the need for plug-ins.
Peters, Kirstin
2010-01-01
A well-known result by Palamidessi tells us that {\\pi}mix (the {\\pi}-calculus with mixed choice) is more expressive than {\\pi}sep (its subset with only separate choice). The proof of this result argues with their different expressive power concerning leader election in symmetric networks. Later on, Gorla of- fered an arguably simpler proof that, instead of leader election in symmetric networks, employed the reducibility of "incestual" processes (mixed choices that include both enabled senders and receivers for the same channel) when running two copies in parallel. In both proofs, the role of breaking (ini- tial) symmetries is more or less apparent. In this paper, we shed more light on this role by re-proving the above result-based on a proper formalization of what it means to break symmetries-without referring to another layer of the distinguishing problem domain of leader election. Both Palamidessi and Gorla rephrased their results by stating that there is no uniform and reason- able encoding from {\\pi}mix i...
DEFF Research Database (Denmark)
Strand, Anete Mikkala Camille; Larsen, Jens
2015-01-01
to Explore your Leadership” . ”Time to reflect closer to heaven as we did in the Pyrenees, makes me humble and simplifies the thoughts on how to lead within my own set of values. It´s all about energy”, (Lars Lund Hansen, manager, Novo Nordisk) A few objects; a neckless, a candle, a dragon and five crystal...... terrain break elaborates the terrain of Organizations anno 2015 as a terrain of complexity, streamlining, language-orientation and dis-functionality. The latter in regard to a WHO acknowledged concern for health issues related to work-related stress (Prætorius, 2012) and an ongoing urge for learning...... that language and the social has been granted too much power on the dispense of the bodily, physical and biological – or in short, in dispense of the material. The break To be or not to be poses the theoretical notion of dis-/continuity (Barad, 2007, 2010) from the quantum approach to storytelling (Strand 2012...
Fairhead, J. D.; Somerton, I. W.
2011-12-01
magnetic data making gridding problematic. Instead of using minimum curvature as in WDMAM, the EMAG3 model uses the plate tectonic isochron model to directionally control grid interpolation in order to honour the strong 2D remanence (reversal magnetic field patterns) generated from Mesozoic to Recent sea floor spreading. For onshore areas many of the same problems encountered with the gravity field are present. Airborne magnetic coverage is near complete for Europe/Asia/Australia/North America but is poor in many parts of Africa, South America and Antarctica. In addition the models have upward continued the field to 4 or 5 km and many of the commercial surveys have been decimation. The talk will present many examples of these resolution limitations. For reliable geological interpretation one first needs to be sure of what the survey coverage is present and has it been decimated and/or, upward continued. Finally just because a global model is provided as a 1' (~2km) grid it does not imply that the wavelength resolution is everywhere down to 4km (twice grid cell spacing), e.g. satellite derived gravity data for the oceans has a resolution of only 15 to 20km.
Peña, José M.; Torres-Sánchez, Jorge; Serrano-Pérez, Angélica; de Castro, Ana I.; López-Granados, Francisca
2015-01-01
In order to optimize the application of herbicides in weed-crop systems, accurate and timely weed maps of the crop-field are required. In this context, this investigation quantified the efficacy and limitations of remote images collected with an unmanned aerial vehicle (UAV) for early detection of weed seedlings. The ability to discriminate weeds was significantly affected by the imagery spectral (type of camera), spatial (flight altitude) and temporal (the date of the study) resolutions. The colour-infrared images captured at 40 m and 50 days after sowing (date 2), when plants had 5–6 true leaves, had the highest weed detection accuracy (up to 91%). At this flight altitude, the images captured before date 2 had slightly better results than the images captured later. However, this trend changed in the visible-light images captured at 60 m and higher, which had notably better results on date 3 (57 days after sowing) because of the larger size of the weed plants. Our results showed the requirements on spectral and spatial resolutions needed to generate a suitable weed map early in the growing season, as well as the best moment for the UAV image acquisition, with the ultimate objective of applying site-specific weed management operations. PMID:25756867
Peña, José M; Torres-Sánchez, Jorge; Serrano-Pérez, Angélica; de Castro, Ana I; López-Granados, Francisca
2015-01-01
In order to optimize the application of herbicides in weed-crop systems, accurate and timely weed maps of the crop-field are required. In this context, this investigation quantified the efficacy and limitations of remote images collected with an unmanned aerial vehicle (UAV) for early detection of weed seedlings. The ability to discriminate weeds was significantly affected by the imagery spectral (type of camera), spatial (flight altitude) and temporal (the date of the study) resolutions. The colour-infrared images captured at 40 m and 50 days after sowing (date 2), when plants had 5-6 true leaves, had the highest weed detection accuracy (up to 91%). At this flight altitude, the images captured before date 2 had slightly better results than the images captured later. However, this trend changed in the visible-light images captured at 60 m and higher, which had notably better results on date 3 (57 days after sowing) because of the larger size of the weed plants. Our results showed the requirements on spectral and spatial resolutions needed to generate a suitable weed map early in the growing season, as well as the best moment for the UAV image acquisition, with the ultimate objective of applying site-specific weed management operations. PMID:25756867
Directory of Open Access Journals (Sweden)
José M. Peña
2015-03-01
Full Text Available In order to optimize the application of herbicides in weed-crop systems, accurate and timely weed maps of the crop-field are required. In this context, this investigation quantified the efficacy and limitations of remote images collected with an unmanned aerial vehicle (UAV for early detection of weed seedlings. The ability to discriminate weeds was significantly affected by the imagery spectral (type of camera, spatial (flight altitude and temporal (the date of the study resolutions. The colour-infrared images captured at 40 m and 50 days after sowing (date 2, when plants had 5–6 true leaves, had the highest weed detection accuracy (up to 91%. At this flight altitude, the images captured before date 2 had slightly better results than the images captured later. However, this trend changed in the visible-light images captured at 60 m and higher, which had notably better results on date 3 (57 days after sowing because of the larger size of the weed plants. Our results showed the requirements on spectral and spatial resolutions needed to generate a suitable weed map early in the growing season, as well as the best moment for the UAV image acquisition, with the ultimate objective of applying site-specific weed management operations.
Valdano, Eugenio; Colizza, Vittoria
2015-01-01
The epidemic threshold of a spreading process indicates the condition for the occurrence of the wide spreading regime, thus representing a predictor of the network vulnerability to the epidemic. Such threshold depends on the natural history of the disease and on the pattern of contacts of the network with its time variation. Based on the theoretical framework introduced in (Valdano et al. PRX 2015) for a susceptible-infectious-susceptible model, we formulate here an infection propagator approach to compute the epidemic threshold accounting for more realistic effects regarding a varying force of infection per contact, the presence of immunity, and a limited time resolution of the temporal network. We apply the approach to two temporal network models and an empirical dataset of school contacts. We find that permanent or temporary immunity do not affect the estimation of the epidemic threshold through the infection propagator approach. Comparisons with numerical results show the good agreement of the analytical ...
International Nuclear Information System (INIS)
Complete text of publication follows. A method was developed to determine metals after vapour generation, atomization in a heated quartz tube and detection using High Resolution Continuum Source AAS (ContrAA 300R equipment, Analytic Jena, Germany). High resolution continuum source AAS allows sequential analysis of elements with detection limits a factor of five better than those of Line Source AAS. This fact is due to the combined use of higher radiation intensity xenon continuum source, a high resolution monochromator and a CCD array detector. Moreover, important advantages of this technique were relatively low cost, possibility to visualize molecular absorption lines (mainly diatomic species). Modifications on the HS60 (Analytic Jena, Germany) vapor generation system were performed. The system includes three peristaltic pumps, a three channel and a one channel, controlled by software and a external peristaltic pump. Flow rates were selected from the three permitted velocities, in order to provide maximum sensitivity and an adequate operation in the gas-liquid separator. A home-made glass hydrostatic gas-liquid separator was used. A 140 cm length PTFE tube and a small piece of PharmedR tube were included to transfer vapors from the gas-liquid separator to the quartz cell. Regarding the Ar carrier flow, it must be pointed out that ContrAA 300R equipment only has three options for this parameter (6, 25, and 31 L h-1), and this is a difficulty to study possible effects on the liberation of vapors from the aqueous phase or their concentration in the quartz tube. Optimum conditions for the sequential determination of Ag, Cd, Cu, Co, Ni and Zn were obtained and technical limitations of the system are examined. Calibration curves were lineal (r = 0.995 or higher). Method is precise (RSD <10%) and with LODs lower than 20 g/L for studied elements except for Ni and Co. The authors kindly acknowledge the financial support from Xunta de Galicia (ref. PGIDIT07PXIB209034PR).
Breaking stress of neutron star crust
Chugunov, A I
2010-01-01
The breaking stress (the maximum of the stress-strain curve) of neutron star crust is important for neutron star physics including pulsar glitches, emission of gravitational waves from static mountains, and flares from star quakes. We perform many molecular dynamic simulations of the breaking stress at different coupling parameters (inverse temperatures) and strain rates. We describe our results with the Zhurkov model of strength. We apply this model to estimate the breaking stress for timescales ~1 s - 1 year, which are most important for applications, but much longer than can be directly simulated. At these timescales the breaking stress depends strongly on the temperature. For coupling parameter <200, matter breaks at very small stress, if it is applied for a few years. This viscoelastic creep can limit the lifetime of mountains on neutron stars. We also suggest an alternative model of timescale-independent breaking stress, which can be used to estimate an upper limit on the breaking stress.
Valdano, Eugenio; Poletto, Chiara; Colizza, Vittoria
2015-12-01
The epidemic threshold of a spreading process indicates the condition for the occurrence of the wide spreading regime, thus representing a predictor of the network vulnerability to the epidemic. Such threshold depends on the natural history of the disease and on the pattern of contacts of the network with its time variation. Based on the theoretical framework introduced in [E. Valdano, L. Ferreri, C. Poletto, V. Colizza, Phys. Rev. X 5, 21005 (2015)] for a susceptible-infectious-susceptible model, we formulate here an infection propagator approach to compute the epidemic threshold accounting for more realistic effects regarding a varying force of infection per contact, the presence of immunity, and a limited time resolution of the temporal network. We apply the approach to two temporal network models and an empirical dataset of school contacts. We find that permanent or temporary immunity do not affect the estimation of the epidemic threshold through the infection propagator approach. Comparisons with numerical results show the good agreement of the analytical predictions. Aggregating the temporal network rapidly deteriorates the predictions, except for slow diseases once the heterogeneity of the links is preserved. Weight-topology correlations are found to be the critical factor to be preserved to improve accuracy in the prediction.
Burke, J. J.; Breckinridge, J. B.
1978-01-01
The signal-to-noise (S/N) ratio to be expected when a 180 deg rotationally shearing interferometer is used for image recovery at the diffraction limit of a large telescope is computed. The variance and covariance of the irradiance fluctuations at the detector array are shown to yield measures of the high-frequency spatial spectrum of the source. Four fundamental sources of noise are considered: temporal fluctuations of the source, space-time fluctuations of the atmosphere, shot noise in the detected photocurrents, and the effects of finite sampling. S/N is found to be directly proportional to the angular resolution of the telescope, the single-frame integration time, the square root of the number of frames, the cube of the operating wavelength, the quantum efficiency of the detector, and the average spectral irradiance from the source on the pupil. It is inversely proportional to the cube of the field angle subtended by the source (or part thereof) under study.
Hepper, Dietmar
2011-06-10
The signal model of a superresolution optical channel can be an efficient tool for developing components of an associated high-density optical disc system. While the behavior of the laser diode, aperture, lens, and detector are properly described, a general mathematical model of the superresolution disc itself has not yet been available until recently. Different approaches have been made to describe the properties of a mask layer, mainly based on temperature- or power-dependent nonlinear effects. A complete signal-based or phenomenological optical channel model--from non-return-to-zero inverted input to disc readout signal--has recently been developed including the reflectivity of a superresolution disc with InSb used for the mask layer. In this contribution, the model is now extended and applied to a moving disc including a land-and-pit structure, and results are compared with data read from real superresolution discs. Both impulse response and resolution limits are derived and discussed. Thus the model provides a bridge from physical to readout signal properties, which count after all. The presented approach allows judging of the suitability of a mask layer material for storage density enhancement already based on static experiments, i.e., even before developing an associated disc drive. PMID:21673750
Gurcay, Savas; Cifci, Gunay; Dondurur, Derman; Okay, Seda; Atgin, Orhan; Ozel, Ozkan; Mert Kucuk, Hilmi
2016-04-01
High Resolution multi-channel seismic reflection and Chirp data were collected by K. Piri Reis, research vessel of Dokuz Eylül University, in the central Aegean coast of the West Anatolia by research cruises carried out in 2005 and 2008, respectively. Submarine stratigraphic and structural features of Sıǧacık Gulf, Kuşadası Gulf and surroundings were investigated under this survey. The data were processed and interpreted in SeisLab, D.E.U. Marine Sciences and Technology seismic laboratory. Thirteen distinct unconformities can be traced below the study area that separate thirteen progradational stacked paleo-delta sequences (Lob1-Lob13) on seismic profiles following and cutting each other. As a result of comparison with the oxygen isotopic stages (δ18), these deltas (Lob1-L13) were interpreted that they have been deposited during the sea-level lowstands within Pleistocene glacial stages. In the study area the basement surface which observed as the lowest unconformity surface of the seismic sections was called 'Acoustic Basement'. This basement which traced approximately all of the seismic sections has generally quite wavy surface and underlain the upper seismic units. It was observed that these seismic units which terminated their formation in Pleistocene (Lob1-Lob13) and Holocene period were cut and uplifted by acoustic basement, like an intrusion. These type deformations were interpreted as a result of magmatic intrusion into these upper seismic units occurred in Late Pleistocene and Holocene period. Tectonic and structural interpretation was carried out to constitute the submarine active tectonic map of the study area by correlated active faults identified on seismic sections. Submarine active tectonic map and, basement topography and sediment thickness map were correlated together to present the relationship between tectonic deformation and stratigraphy.
Super-resolution without Evanescent Waves
Huang, Fu Min; Zheludev, Nikolay I.
2008-01-01
The last decade has seen numerous efforts to achieve imaging resolution beyond that of the Abbe-Rayleigh diffraction limit. The main direction of research aiming to break this limit seeks to exploit the evanescent components containing fine detail of the electromagnetic field distribution at the immediate proximity of the object. Here we propose a solution that removes the need for evanescent fields. The object being imaged or stimulated with sub-wavelength accuracy does not need to be in the...
Hudspith, R J; Maltman, K; Wolfe, C E; Zanotti, J
2015-01-01
Continuum and lattice methods are used to investigate systematic issues in the sum rule determination of $V_{us}$ using inclusive hadronic $\\tau$ decay data. Results for $V_{us}$ employing assumptions for $D>4$ OPE contributions used in previous conventional implementations of this approach are shown to display unphysical dependence on the sum rule weight, $w$, and choice of upper limit, $s_0$, of the relevant experimental spectral integrals. Continuum and lattice results suggest a new implementation of the sum rule approach with not just $\\vert V_{us}\\vert$, but also $D>4$ effective condensates, fit to data. Lattice results are also shown to provide a quantitative assessment of truncation uncertainties for the slowly converging $D=2$ OPE series. The new sum rule implementation yields $\\vert V_{us}\\vert$ results free of unphysical $s_0$- and $w$-dependences and $\\sim 0.0020$ higher than that obtained using the conventional implementation. With preliminary new experimental results for the $K\\pi$ branching frac...
Singh, Gurmeet; Nandi, Apurba; Gadre, Shridhar R.
2016-03-01
A pragmatic method based on the molecular tailoring approach (MTA) for estimating the complete basis set (CBS) limit at Møller-Plesset second order perturbation (MP2) theory accurately for large molecular clusters with limited computational resources is developed. It is applied to water clusters, (H2O)n (n = 7, 8, 10, 16, 17, and 25) optimized employing aug-cc-pVDZ (aVDZ) basis-set. Binding energies (BEs) of these clusters are estimated at the MP2/aug-cc-pVNZ (aVNZ) [N = T, Q, and 5 (whenever possible)] levels of theory employing grafted MTA (GMTA) methodology and are found to lie within 0.2 kcal/mol of the corresponding full calculation MP2 BE, wherever available. The results are extrapolated to CBS limit using a three point formula. The GMTA-MP2 calculations are feasible on off-the-shelf hardware and show around 50%-65% saving of computational time. The methodology has a potential for application to molecular clusters containing ˜100 atoms.
Gabrielle Fredman; Yongsheng Li; Jesmond Dalli; Nan Chiang; Serhan, Charles N.
2012-01-01
Mechanisms underlying delays in resolution programs of inflammation are of interest for many diseases. Here, we addressed delayed resolution of inflammation and identified specific microRNA (miR)-metabolipidomic signatures. Delayed resolution initiated by high-dose challenges decreased miR-219-5p expression along with increased leukotriene B4 (5-fold) and decreased (~3-fold) specialized pro-resolving mediators, e.g. protectin D1. Resolvin (Rv)E1 and RvD1 (1 nM) reduced miR-219-5p in human mac...
Sweby, P. K.
1985-01-01
Roe (1981, 1985) has utilized flux limiters to obtain second order monotonicity preserving schemes. In the present paper, the foundation for flux limiters in the formulation of first order three-point schemes are discussed, and a systematic outline is provided of the method of using flux limiters to obtain second order accurate TVD schemes. Attention is given to Phi limiters, the Van Leer limiter, the Chakravarthy-Osher limiter, the linear advection equation and square wave data, the inviscid Burger's equation, and the extension of flux limiters to irregular grids, systems of equations, and implicit calculations.
Carminati, M.; Gervasoni, G.; Sampietro, M.; Ferrari, G.
2016-02-01
The resolution of digital lock-in amplifiers working with a narrow bandwidth (amplifier (tens of nV). In order to tackle this issue, affecting state-of-the-art laboratory instrumentation and here systematically quantified, three differential sensing configurations are presented. They adapt to different setup conditions and are based on manual and automatic tuning of dummy references, allowing a 25-fold resolution improvement for enhanced long-term tracking of impedance sensors.
Scott, Chris C.; Allec, Nicholas; Karim, Karim S.
2012-03-01
An amorphous selenium direct detector with a 25 μm pixel pitch is studied for mammography and fluoroscopy applications. In this paper we analyze spatial resolution by examining the main contributions to the inherent modulation transfer function (MTF) of amorphous selenium, such as primary photoelectron range and x-ray beam obliquity; and determine their significance relative to aperture MTF. Improvements in spatial resolution provided by a move to a small pixel size are complicated by deep carrier trapping. Trapped carriers cause residual charge induction across the pixel plane. We examine the significance of this effect on spatial resolution. The potential improvements of moving from a larger pixel pitch to a 25 μm pixel pitch are studied, including all significant effects, at selected pixel pitches.
An assessment of the resolution limitation due to radiation-damage in x-ray diffraction microscopy
Howells, M. R.; Beetz, T.; Chapman, H. N.; Cui, C.; Holton, J. M.; Jacobsen, C. J.; Kirz, J.; Lima, E.; Marchesini, S.; Miao, H.; Sayre, D.; Shapiro, D. A.; Spence, J. C. H.; Starodub, D.
2005-01-01
X-ray diffraction microscopy (XDM) is a new form of x-ray imaging that is being practiced at several third-generation synchrotron-radiation x-ray facilities. Nine years have elapsed since the technique was first introduced and it has made rapid progress in demonstrating high-resolution three-dimensional imaging and promises few-nm resolution with much larger samples than can be imaged in the transmission electron microscope. Both life- and materials-science applications of XDM are intended, a...
International Nuclear Information System (INIS)
Low-beam-energy X-ray microanalysis with the field-emission-gun scanning electron microscope suffers limitations due to physical factors of X-ray generation. Instrumental limitations are imposed by the poor resolution of the conventional semiconductor energy dispersive X-ray spectrometry. Wavelength dispersive X-ray spectrometry provides sufficient resolution to solve spectroscopic problems, but the poor geometric efficiency and the single channel nature of spectrum measurement restrict its practical use for low-beam-energy microanalysis. The microcalorimeter energy dispersive X-ray spectrometer combines high resolution (<10 eV) with energy dispersive operation. The utility of this new spectrometer is examined in four categories: (1) qualitative analysis; (2) quantitative analysis; (3) chemical speciation studies, and (4) measurement of trace constituents. For the low-beam-energy regime, the microcalorimeter energy dispersive X-ray spectrometer provides important new performance capabilities for qualitative analysis and chemical speciation studies. However, there are limitations for quantitative studies imposed by detector geometrical characteristics. In addition, trace element detection is impractical below 0.001 mass fraction with low-beam energy (<5 keV) because of count rate limitations. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)
Electroweak symmetry breaking through supersymmetry breaking
International Nuclear Information System (INIS)
The connection between the scales of SU(2) x U(1) gauge symmetry breaking and supersymmetry breaking is didactically displayed in the framework of a T.O.Y. (Theory Overestimating Yukawas) model, a version of the (M + 1) SSM (supersymmetric extension of the standard model with a gauge singlet) in which the relevant parameters are determined in the fixed point regime. Some conspicuous features of supersymmetric particle physics are reviewed in the light of this simplified model. An alternative theory corresponding to lim (M + 1) SSM → MSSM, leads to interesting inequalities among the supersymmetric breaking parameters of the MSSM
Latychevskaia, Tatiana
2015-01-01
In coherent diffractive imaging (CDI) the resolution with which the reconstructed object can be obtained is limited by the numerical aperture of the experimental setup. We present here a theoretical and numerical study for achieving super-resolution by post-extrapolation of coherent diffraction images, such as diffraction patterns or holograms. We proof that a diffraction pattern can unambiguously be extrapolated from just a fraction of the entire pattern and that the ratio of the extrapolated signal to the originally available signal, is linearly proportional to the oversampling ratio. While there could be in principle other methods to achieve extrapolation, we devote our discussion to employing phase retrieval methods and demonstrate their limits. We present two numerical studies; namely the extrapolation of diffraction patterns of non-binary and that of phase objects together with a discussion of the optimal extrapolation procedure.
Super-resolution photoacoustic imaging of single gold nanoparticles
Lee, Seunghyun; Kwon, Owoong; Jeon, Mansik; Song, Jaejung; Jo, Minguk; Kim, Sungjee; Son, Junwoo; Kim, Yunseok; Kim, Chulhong
2016-03-01
Photoacoustic imaging (PAI) is an emerging hybrid imaging modality that can provide a strong optical absorption contrast using the photoacoustic (PA) effect, and breaks through the fundamental imaging depth limit of existing optical microscopy such as optical coherence tomography (OCT), confocal or two-photon microscopy. In PAI, a short-pulsed laser is illuminated to the tissue, and the PA waves are generated by thermoelastic expansion. Despite the high lateral resolution of optical-resolution photoacoustic microscopy (OR-PAM) thanks to the tight optical focus, the lateral resolution of OR-PAM is limited to the optical diffraction limit, which is approximately a half of the excitation wavelength. Here, we demonstrate a new super-resolution photoacoustic microscopy (SR-PAM) system by breaking the optical diffraction limit. The conventional microscopes with nanoscale resolutions such as a scanning electron microscope (SEM) and transmission electron microscope (TEM) are typically used to image the structures of nanomaterials, but these systems should work in a high vacuum environment and cannot provide the optical properties of the materials. Our newly developed SR-PAM system provides the optical properties with a nanoscale resolution in a normal atmosphere. We have photoacoustically imaged single gold nanoparticles with an average size of 80 nm in diameter and shown their PA expansion properties individually. The lateral resolution of this system was approximately 20 nm. Therefore, this tool will provide an unprecedented optical absorption property with an accurate nanoscale resolution and greatly impact on materials science and nanotechnology field.
Energy Technology Data Exchange (ETDEWEB)
Cargo, P.; Samba, G
2007-07-01
We consider the P{sub n} model to approximate the transport equation in one dimension of space. In a diffusive regime, the solution of this system is solution of a diffusion equation. We are looking for a numerical scheme having the diffusion limit property: in a diffusive regime, it gives the solution of the limiting diffusion equation on a mesh at the diffusion scale. The numerical scheme proposed is an extension of the Godunov type scheme proposed by L. Gosse to solve the P{sub 1} model without absorption term. Moreover, it has the well-balanced property: it preserves the steady solutions of the system. (authors)
A Stylistic Analysis of Break,Break,Break
Institute of Scientific and Technical Information of China (English)
李瑶
2015-01-01
Break, Break, Break is a poem by Alfred Lord Tennyson, the Poet Laureate during the Queen Victoria's reign. This exquisite little poem is wel known for the poet's grief-stricken feelings and heart-broken emotions over the premature death of his best friend, Arthur Henry Halam. Most of the previous studies on this poem focus on the emotional level to consider it as an elegy, expressing sorrow and lamentation for the death of a particular person. However, in order to have a deep understanding in general, this paper analyzes the poem based on the stylistic theory, concerning on the lexical level and the semantic level. It aims at helping the readers to cultivate a sense of appropriateness, to sharpen the understanding and appreciation of literary works and to achieve adaptation in translation.
Ushakov, Nikolai; Markvart, Alexandr; Liokumovich, Leonid
2015-07-01
An approach for compensating the influence of interrogator noises on the readings of interferometric sensors, interrogated by means of spectral interferometry with wavelength tuning, is proposed. Theoretical analysis and a proof-of-principle experiment were performed for the example of extrinsic Fabry-Perot interferometers. Two schemes, comprised of a signal and reference interferometers, switched in different optical channels of the interrogating unit, were proposed. The approach is based on the fact that the fluctuations of some of the interrogator parameters produce correlated fluctuations of the reference and signal interferometers' optical path differences' (OPDs) measured values. The fluctuations of the reference interferometer's measured OPD can be subtracted from the measured OPD of the signal interferometer. The fluctuations of different parameters of the interrogator are considered, the correlation properties of the produced noises of the measured OPD values are demonstrated. The first scheme contains two interferometers with similar parameters and enabled a threefold resolution improvement in the performed experiments, when the difference of the interferometers OPDs was varied within about 10 nm. The second scheme contains two interferometers with OPDs difference such that all interrogator fluctuations, except for the dominating one, produce uncorrelated OPD errors. With the second scheme, a twofold resolution improvement was experimentally demonstrated when the interferometers' OPDs difference was varied within more than 1 μm. The proposed approach can be used for improving the resolution of interferometric sensors with relatively large OPDs (greater than 200-300 μm), which can be advantageous for remote materials and surface inspection. The other potential application is the use of relatively simple cheap interrogators with poor wavelength scale repeatability for high-precision measurements. PMID:26193148
Genome-wide mapping of DNA strand breaks.
Directory of Open Access Journals (Sweden)
Frédéric Leduc
Full Text Available Determination of cellular DNA damage has so far been limited to global assessment of genome integrity whereas nucleotide-level mapping has been restricted to specific loci by the use of specific primers. Therefore, only limited DNA sequences can be studied and novel regions of genomic instability can hardly be discovered. Using a well-characterized yeast model, we describe a straightforward strategy to map genome-wide DNA strand breaks without compromising nucleotide-level resolution. This technique, termed "damaged DNA immunoprecipitation" (dDIP, uses immunoprecipitation and the terminal deoxynucleotidyl transferase-mediated dUTP-biotin end-labeling (TUNEL to capture DNA at break sites. When used in combination with microarray or next-generation sequencing technologies, dDIP will allow researchers to map genome-wide DNA strand breaks as well as other types of DNA damage and to establish a clear profiling of altered genes and/or intergenic sequences in various experimental conditions. This mapping technique could find several applications for instance in the study of aging, genotoxic drug screening, cancer, meiosis, radiation and oxidative DNA damage.
Webb, G.E.; Sando, W.J.; Raymond, A.
1997-01-01
Analysis of high resolution diversity data for Mississippian corals in the western interior United States yielded mild latitudinal diversity gradients despite the small geographic area covered by samples and a large influence on diversity patterns by geographic sampling intensity (sample bias). Three competing plate tectonic reconstructions were tested using the diversity patterns. Although none could be forcefully rejected, one reconstruction proved less consistent with diversity patterns than the other two and additional coral diversity data from farther north in Canada would better discriminate the two equivalent reconstructions. Despite the relatively high sampling intensity represented by the analyzed database, diversity patterns were greatly affected by sample abundance and distribution. Hence, some effort at recognizing and accounting for sample bias should be undertaken in any study of latitudinal diversity gradients. Small-scale geographic lumping of sample localities had only small effects on geographic diversity patterns. However, large-scale (e.g., regional) geographic lumping of diversity data may not yield latitudinally sensitive diversity patterns. Temporal changes in coral diversity in this region reflect changes in eustacy, local tectonism, and terrigenous sediment flux, far more than they do shifting latitude. Highest regional diversity occurred during the interval when the studied region occupied the highest latitude. Therefore, diversity data from different regions may not be comparable, in terms of latitudinal inference. Small-scale stratigraphic lumping of the data caused a nearly complete loss of the latitudinal diversity patterns apparent prior to lumping. Hence, the narrowest possible stratigraphic resolution should be maintained in analyzing latitudinal diversity gradients.
Can AGN feedback break the self-similarity of galaxies, groups, and clusters?
Gaspari, M; Temi, P; Ettori, S
2014-01-01
It is commonly thought that AGN feedback can break the self-similar scaling relations of galaxies, groups, and clusters. Using high-resolution 3D hydrodynamic simulations, we isolate the impact of AGN feedback on the $L_{\\rm x}-T_{\\rm x} $ relation, testing the two archetypal and common regimes, self-regulated mechanical feedback and a quasar thermal blast. We find that AGN feedback has severe difficulty in breaking the relation in a consistent way. The similarity breaking is directly linked to the gas evacuation within $R_{500}$, while the central cooling times are inversely proportional to the core density. Breaking self-similarity implies thus breaking the cool core, morphing all systems to non-cool-core objects, which is in clear contradiction with the observed data populated by several cool-core systems. Self-regulated feedback, which quenches cooling flows and preserves cool cores, prevents the dramatic evacuation and similarity breaking at any scale; the relation scatter is also limited. The impulsive ...
Dynamical supersymmetry breaking
International Nuclear Information System (INIS)
Supersymmetry, and in particular, dynamical supersymmetry breaking, offers the hope of a natural solution of the gauge hierarchy problem in grand unification. I briefly review recent work on dynamical supersymmetry breaking in four-dimensional Higgs theories and its application to grand unified model building
Energy Technology Data Exchange (ETDEWEB)
Hu, Jian Zhi; Rommereim, Donald N.; Wind, Robert A.; Minard, Kevin R.; Sears, Jesse A.
2006-11-01
A simple approach is reported that yields high resolution, high sensitivity ¹H NMR spectra of biofluids with limited mass supply. This is achieved by spinning a capillary sample tube containing a biofluid at the magic angle at a frequency of about 80Hz. A 2D pulse sequence called ¹H PASS is then used to produce a high-resolution ¹H NMR spectrum that is free from magnetic susceptibility induced line broadening. With this new approach a high resolution ¹H NMR spectrum of biofluids with a volume less than 1.0 µl can be easily achieved at a magnetic field strength as low as 7.05T. Furthermore, the methodology facilitates easy sample handling, i.e., the samples can be directly collected into inexpensive and disposable capillary tubes at the site of collection and subsequently used for NMR measurements. In addition, slow magic angle spinning improves magnetic field shimming and is especially suitable for high throughput investigations. In this paper first results are shown obtained in a magnetic field of 7.05T on urine samples collected from mice using a modified commercial NMR probe.
Breaking stress of neutron star crust
International Nuclear Information System (INIS)
Complete text of publication follows. The breaking stress (the maximum of the stress-strain curve) of neutron star crust is important for neutron star physics including pulsar glitches, emission of gravitational waves from static mountains, and flares from star quakes. We perform many molecular dynamic simulations of the breaking stress at different coupling parameters (inverse temperatures), strain rates and composition of matter. We describe our results with the Zhurkov model of strength. We apply this model to estimate the breaking stress for timescales ∼1 s - 1 year, which are most important for applications, but much longer than can be directly simulated. At these timescales the breaking stress depends strongly on the temperature. For coupling parameter Γ<200 matter breaks at very small stress, if it is applied for a few years. This viscoelastic creep can limit the lifetime of mountains on neutron stars. We also suggest an alternative model of timescale-independent breaking stress, which can be used to estimate an upper limit on the breaking stress. This work was partially supported by the Russian Foundation for Basic Research (grant 11-02-00253-a), by the State Program 'Leading Scientific Schools of Russian Federation' (grant NSh 3769.2010.2), by the President grant for young Russian scientists (MK-5857.2010.2), by United States DOE grant (DE-FG02-87ER40365) and by Shared University Research grants from IBM, Inc. to Indiana University.
Energy Technology Data Exchange (ETDEWEB)
Thingna, Juzar [Institute of Physics, University of Augsburg, Universitätsstrasse 1 D-86135 Augsburg (Germany); Nanosystems Initiative Munich, Schellingrstrasse 4, D-80799 München (Germany); Zhou, Hangbo [Department of Physics and Centre for Computational Science and Engineering, National University of Singapore, Singapore 117551 (Singapore); NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456 (Singapore); Wang, Jian-Sheng, E-mail: phywjs@nus.edu.sg [Department of Physics and Centre for Computational Science and Engineering, National University of Singapore, Singapore 117551 (Singapore)
2014-11-21
We present a general theory to calculate the steady-state heat and electronic currents for nonlinear systems using a perturbative expansion in the system-bath coupling. We explicitly demonstrate that using the truncated Dyson-series leads to divergences in the steady-state limit, thus making it impossible to be used for actual applications. In order to resolve the divergences, we propose a unique choice of initial condition for the reduced density matrix, which removes the divergences at each order. Our approach not only allows us to use the truncated Dyson-series, with a reasonable choice of initial condition, but also gives the expected result that the steady-state solutions should be independent of initial preparations. Using our improved Dyson series we evaluate the heat and electronic currents up to fourth-order in system-bath coupling, a considerable improvement over the standard quantum master equation techniques. We then numerically corroborate our theory for archetypal settings of linear systems using the exact nonequilibrium Green's function approach. Finally, to demonstrate the advantage of our approach, we deal with the nonlinear spin-boson model to evaluate heat current up to fourth-order and find signatures of cotunnelling process.
Estimation of unknown structure parameters from high-resolution (S)TEM images: What are the limits?
International Nuclear Information System (INIS)
Statistical parameter estimation theory is proposed as a quantitative method to measure unknown structure parameters from electron microscopy images. Images are then purely considered as data planes from which structure parameters have to be determined as accurately and precisely as possible using a parametric statistical model of the observations. For this purpose, an efficient algorithm is proposed for the estimation of atomic column positions and intensities from high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) images. Furthermore, the so-called Cramér–Rao lower bound (CRLB) is reviewed to determine the limits to the precision with which continuous parameters such as atomic column positions and intensities can be estimated. Since this lower bound can only be derived for continuous parameters, alternative measures using the principles of detection theory are introduced for problems concerning the estimation of discrete parameters such as atomic numbers. An experimental case study is presented to show the practical use of these measures for the optimization of the experiment design if the purpose is to decide between the presence of specific atom types using STEM images. - Highlights: • The benefits of parameter estimation theory for quantitative electron microscopy are reviewed. • An efficient algorithm is proposed for least squares parameter estimation from HAADF STEM images. • Performance measures are proposed for the estimation of discrete parameters such as atomic numbers. • The effective use of these measures for experiment design is shown in simulation experiments
Institute of Scientific and Technical Information of China (English)
2015-01-01
Jacky：My sister is mad at me.She refuses（拒绝）to talk to me.What can I do to break the ice？Ella：You can buy her a little gift.Break的意思是＂打破＂,ice是指＂冰块＂。冰是又冷又硬的东西,作为俗语break the ice是指＂打破沉默（僵局）＂。Jacky惹妹妹生气,妹妹不理他了,他能通过送小礼物break the ice吗？
Supersymmetry breaking from superstrings
International Nuclear Information System (INIS)
The gauge hierarchy problem is briefly reviewed and a class of effective field theories obtained from superstrings is described. These are characterized by a classical symmetry, related to the space-time duality of string theory, that is responsible for the suppression of observable supersymmetry breaking effects. At the quantum level, the symmetry is broken by anomalies that provide the seed of observable supersymmetry breaking, and an acceptably large gauge hierarchy may be generated. 26 refs
International Nuclear Information System (INIS)
This paper is the result of an attempt to understand the frequently referred terms 'Break Preclusion' (BP) and 'Leak Before Break' (LBB) criteria in the safety literature and available relevant information on internet. Break Preclusion means exclusion of assumption of double ended guillotine rupture of pipelines and instead assuming leak before break which allows to use a reliable system for leak detection signal to shutdown the reactor before the pipe rupture occurs. In other words it means discovery of leak before fracture may occur in service. Pressure vessels and Piping of main steam lines are the areas of application of LBB. Early detection of leak enables shutdown of the reactor of the nuclear power plant. The information used for review are based on abstracts and/or concise form of papers available on internet. As early as in 1982 preclusion of double ended circumferential rupture of the main coolant line was attempted. Break preclusion concept, BPC and LBB both are based on high level knowledge of fracture mechanics. (author)
Burgess, C P; de Alwis, S P; Giddings, S B; Maharana, A; Quevedo, Fernando; Suruliz, K
2008-01-01
We address the size of supersymmetry-breaking effects within higher-dimensional settings where the observable sector resides deep within a strongly warped region, with supersymmetry breaking not necessarily localized in that region. Our particular interest is in how the supersymmetry-breaking scale seen by the observable sector depends on this warping. We obtain this dependence in two ways: by computing within the microscopic (string) theory supersymmetry-breaking masses in supermultiplets; and by investigating how warping gets encoded into masses within the low-energy 4D effective theory. We find that the lightest gravitino mode can have mass much less than the straightforward estimate from the mass shift of the unwarped zero mode. This lightest Kaluza-Klein excitation plays the role of the supersymmetric partner of the graviton and has a warped mass m_{3/2} proportional to e^A, with e^A the warp factor, and controls the size of the soft SUSY breaking terms. We formulate the conditions required for the exist...
U(1) mediation of flux supersymmetry breaking
International Nuclear Information System (INIS)
We study the mediation of supersymmetry breaking triggered by background fluxes in Type II string compactifications with N = 1 supersymmetry. The mediation arises due to an U(1) vector multiplet coupling to both a hidden supersymmetry breaking flux sector and a visible D-brane sector. The required internal manifolds can be constructed by non-Kaehler resolutions of singular Calabi-Yau manifolds. The effective action encoding the U(1) coupling is then determined in terms of the global topological properties of the internal space. We investigate suitable local geometries for the hidden and visible sector in detail. This includes a systematic study of orientifold symmetries of del Pezzo surfaces realized in compact geometries after geometric transition. We construct compact examples admitting the key properties to realize flux supersymmetry breaking and U(1) mediation. Their toric realization allows us to analyze the geometry of curve classes and confirm the topological connection between the hidden and visible sector.
International Nuclear Information System (INIS)
The Higgs mechanism is reviewed in its most general form, requiring the existence of a new symmetry-breaking force and associated particles, which need not however be Higgs bosons. The first lecture reviews the essential elements of the Higgs mechanism, which suffice to establish low energy theorems for the scattering of longitudinally polarized W and Z gauge bosons. An upper bound on the scale of the symmetry-breaking physics then follows from the low energy theorems and partial wave unitarity. The second lecture reviews particular models, with and without Higgs bosons, paying special attention to how the general features discussed in lecture 1 are realized in each model. The third lecture focuses on the experimental signals of strong WW scattering that can be observed at the SSC above 1 TeV in the WW subenergy, which will allow direct measurement of the strength of the symmetry-breaking force. 52 refs., 10 figs
CP breaking in lattice chiral gauge theories
International Nuclear Information System (INIS)
The CP symmetry is not manifestly implemented for the local and doubler-free Ginsparg-Wilson operator in lattice chiral gauge theory. We precisely identify where the effects of this CP breaking appear. We show that they appear in: (I) Overall constant phase of the fermion generating functional. (II) Overall constant coefficient of the fermion generating functional. (III) Fermion propagator appearing in external fermion lines and the propagator connected to Yukawa vertices. The first effect appears from the transformation of the path integral measure and it is absorbed into a suitable definition of the constant phase factor for each topological sector; in this sense there appears no 'CP anomaly'. The second constant arises from the explicit breaking in the action and it is absorbed by the suitable weights with which topological sectors are summed. The last one in the propagator is inherent to this formulation and cannot be avoided by a mere modification of the projection operator, for example, in the framework of the Ginsparg-Wilson operator. This breaking emerges as an (almost) contact term in the propagator when the Higgs field, which is treated perturbatively, has no vacuum expectation value. In the presence of the vacuum expectation value, however, a completely new situation arises and the breaking becomes intrinsically non-local, though this breaking may still be removed in a suitable continuum limit. This non-local CP breaking is expected to persist for a non-perturbative treatment of the Higgs coupling. (author)
DEFF Research Database (Denmark)
Hartley, Jannie Møller
2011-01-01
This chapter revisits seminal theoretical categorizations of news proposed three decades earlier by US sociologist Gaye Tuchman. By exploring the definition of ”breaking news” in the contemporary online newsrooms of three Danish news organisations, the author offers us a long overdue re-theorizat...
DEFF Research Database (Denmark)
Christensen, Poul Rind; Kirketerp, Anne
2006-01-01
The paper shortly reveals the history of a small school - the KaosPilots - dedicated to educate young people to carriers as entrepreneurs. In this contribution we want to explore how the KaosPilots managed to break the waves of institutionalised concepts and practices of teaching entrepreneurship...
Model Breaking Points Conceptualized
Vig, Rozy; Murray, Eileen; Star, Jon R.
2014-01-01
Current curriculum initiatives (e.g., National Governors Association Center for Best Practices and Council of Chief State School Officers 2010) advocate that models be used in the mathematics classroom. However, despite their apparent promise, there comes a point when models break, a point in the mathematical problem space where the model cannot,…
Super-resolution without Evanescent Waves
Huang, Fu Min
2008-01-01
The last decade has seen numerous efforts to achieve imaging resolution beyond that of the Abbe-Rayleigh diffraction limit. The main direction of research aiming to break this limit seeks to exploit the evanescent components containing fine detail of the electromagnetic field distribution at the immediate proximity of the object. Here we propose a solution that removes the need for evanescent fields. The object being imaged or stimulated with sub-wavelength accuracy does not need to be in the immediate proximity of the superlens or field concentrator: an optical mask can be designed that creates constructive interference of waves known as superoscillation, leading to a sub-wavelength focus of prescribed size and shape in a `field of view' beyond the evanescent fields, when illuminated by a monochromatic wave. Moreover, we demonstrate that such a mask may be used not only as a focusing device, but also as a super-resolution imaging device.
Super-resolution without evanescent waves.
Huang, Fu Min; Zheludev, Nikolay I
2009-03-01
The past decade has seen numerous efforts to achieve imaging resolution beyond that of the Abbe-Rayleigh diffraction limit. The main direction of research aiming to break this limit seeks to exploit the evanescent components containing fine detail of the electromagnetic field distribution at the immediate proximity of the object. Here, we propose a solution that removes the need for evanescent fields. The object being imaged or stimulated with subwavelength accuracy does not need to be in the immediate proximity of the superlens or field concentrator: an optical mask can be designed that creates constructive interference of waves known as superoscillation, leading to a subwavelength focus of prescribed size and shape in a field of view beyond the evanescent fields, when illuminated by a monochromatic wave. Moreover, we demonstrate that such a mask may be used not only as a focusing device but also as a super-resolution imaging device. PMID:19182908
Crouch, Ashley D
2012-01-01
We investigate how the azimuthal ambiguity in solar vector magnetogram data can be resolved by using the divergence-free property of magnetic fields. In a previous article, by Crouch, Barnes, and Leka (Solar Phys. 260, 271, 2009), error-free synthetic data were used to test several methods that each make a different assumption about how the divergence-free property can be used to resolve the ambiguity. In this paper this testing is continued with an examination of the effects of Poisson photon noise and limited instrumental spatial resolution. We find that all currently available methods based on the divergence-free property can produce undesirable results when photon noise or unresolved structure are present in the data. We perform a series of experiments aimed at improving the performance of the global minimisation method, which is the most promising of the methods. We present a two-step approach that produces reasonable results in tests using synthetic data. The first step of this approach involves the glo...
Timonen, Hilkka; Cubison, Mike; Aurela, Minna; Brus, David; Lihavainen, Heikki; Hillamo, Risto; Canagaratna, Manjula; Nekat, Bettina; Weller, Rolf; Worsnop, Douglas; Saarikoski, Sanna
2016-07-01
The applicability, methods and limitations of constrained peak fitting on mass spectra of low mass resolving power (m/Δm50 ˜ 500) recorded with a time-of-flight aerosol chemical speciation monitor (ToF-ACSM) are explored. Calibration measurements as well as ambient data are used to exemplify the methods that should be applied to maximise data quality and assess confidence in peak-fitting results. Sensitivity analyses and basic peak fit metrics such as normalised ion separation are employed to demonstrate which peak-fitting analyses commonly performed in high-resolution aerosol mass spectrometry are appropriate to perform on spectra of this resolving power. Information on aerosol sulfate, nitrate, sodium chloride, methanesulfonic acid as well as semi-volatile metal species retrieved from these methods is evaluated. The constants in a commonly used formula for the estimation of the mass concentration of hydrocarbon-like organic aerosol may be refined based on peak-fitting results. Finally, application of a recently published parameterisation for the estimation of carbon oxidation state to ToF-ACSM spectra is validated for a range of organic standards and its use demonstrated for ambient urban data.
International Nuclear Information System (INIS)
A 56 year old house wife with a ten history of diabetes mellitus was admitted with visual impairment of both eyes. The pupil of the right eye larger than that of the lefteye, and did not react to light. Examination revealed diabetic retinopathy of both eyes with the right dilatedandfixed pupil and ocular movements were not abnormal except convergence. Computed Tomography did not show abnormal findings. It is necessary, however, to keep in mind that normal apperance of CT-scan does not always mean normal conditions, because of it's limited resolution capacity. From clinical signs and symptoms, the mydriatic fixed pupil might be diagnosed as diabetic origin. Thus, despite of outstanding technical advances such as a CT-scan, it should be emphasized that the most important diagnostic procedure is clinical signs, symptoms, accurate history, and clinical examinations. It seems to be a useful procedure that twin light reflex is applied to the fixed pupil with retina or optic nerve involvement as well as direct, consensual light reaction, and swing flashlight test. (author)
Chiral symmetry breaking in lattice electrodynamics
International Nuclear Information System (INIS)
Chiral symmetry breaking is studied in lattice quantum electrodynamics in the quenched approximation by computer-simulation methods. Simulations at zero temperature show that in non-zero for all couplings e2 greater than a critical value e2/sub c/. The sensitivity of to short-distance features of the lattice Action is studied by simulating variant gauge Actions. Simulations on asymmetric lattices do not reveal significant temperature dependence in the symmetry-breaking dynamics. Subtle effects and limitations of quenched calculations are discussed
Effective dissipation: breaking time-reversal symmetry
Brown, Aidan I
2016-01-01
At molecular scales, fluctuations play a significant role and prevent biomolecular processes from always proceeding in a preferred direction, raising the question of how limited amounts of free energy can be dissipated to obtain directed progress. We examine the system and process characteristics that efficiently break time-reversal symmetry at fixed energy loss; in particular for a simple model of a molecular machine, an intermediate energy barrier produces unusually high asymmetry for a given dissipation. Such insight into symmetry-breaking factors that produce particularly high time asymmetry suggests generalizations to a broader class of systems.
Incompatibility breaking quantum channels
International Nuclear Information System (INIS)
A typical bipartite quantum protocol, such as EPR-steering, relies on two quantum features, entanglement of states and incompatibility of measurements. Noise can delete both of these quantum features. In this work we study the behavior of incompatibility under noisy quantum channels. The starting point for our investigation is the observation that compatible measurements cannot become incompatible by the action of any channel. We focus our attention to channels which completely destroy the incompatibility of various relevant sets of measurements. We call such channels incompatibility breaking, in analogy to the concept of entanglement breaking channels. This notion is relevant especially for the understanding of noise-robustness of the local measurement resources for steering. (paper)
Breaking News as Radicalisation
DEFF Research Database (Denmark)
Hartley, Jannie Møller
The aim of the paper is to make explicit how the different categories are applied in the online newsroom and thus how new categories can be seen as positioning strategies in the form of radicalisations of already existing categories. Thus field theory provides us with tools to analyse how online...... journalists are using the categorisations to create hierarchies within the journalistic field in order to position themselves as specialists in what Tuchman has called developing news, aiming and striving for what today is know as breaking news and the “exclusive scoop,” as the trademark of online journalism...... in a media environment where immediacy rules (Domingo 2008a). Following this research the primary focus of this paper is the category breaking news and Tuchmans developing news, but as they are all connected the analysis will also draw upon the other categories in Tuchmans typology. The theoretical...
Influencing Factors of Breaking Capacity of Double-Break Vacuum Circuit Breakers
Directory of Open Access Journals (Sweden)
Shengwen Shu
2013-06-01
Full Text Available Using a series arrangement of two vacuum interrupters (VIs has been proved to be an effective way of developing higher voltage vacuum circuit breakers (VCBs, which are known as double-break VCBs. The uniform distribution of the transient recovery voltage (TRV across each VI is very critical for the breaking capacity of double-break VCBs. In this paper, the TRV distribution characteristics of double-break VCBs was studied by the synthetic test and the PSCAD/EMTDC simulation based on a vacuum arc interruption model. The results show that the bias of the TRV distribution ratio is caused by the stray capacitance and the imbalanced post arc plasma characteristic in each VI, which is consistent with the theoretical analysis. Moreover, the negative effect of grading capacitors was discussed. The results show that it is advisable to limit the value of grading capacitors to those ranges which can guarantee sufficiently improve the voltage distribution.
Dynamical Electroweak Symmetry Breaking
Czech Academy of Sciences Publication Activity Database
Hošek, Jiří; Smetana, Adam
Berlin: Springer, 2014, s. 17-28. ISBN 978-3-319-07072-8 R&D Projects: GA ČR GA202/06/0734; GA MŠk LA08015; GA MŠk LA08032 Institutional support: RVO:61389005 Keywords : dynamical electroweak symmetry breaking * top-quark condensation * neutriono condensation * strong Yukawa dynamics * flavor gauge dynamics Subject RIV: BE - Theoretical Physics
Predicting appointment breaking.
Bean, A G; Talaga, J
1995-01-01
The goal of physician referral services is to schedule appointments, but if too many patients fail to show up, the value of the service will be compromised. The authors found that appointment breaking can be predicted by the number of days to the scheduled appointment, the doctor's specialty, and the patient's age and gender. They also offer specific suggestions for modifying the marketing mix to reduce the incidence of no-shows. PMID:10142384
On the symmetry breaking phenomenon
Birtea, Petre; Puta, Mircea; Ratiu, Tudor S.; Tudoran, Ruazvan Micu
2006-01-01
We investigate the problem of symmetry breaking in the framework of dynamical systems with symmetry on a smooth manifold. Two cases will be analyzed: general and Hamiltonian dynamical systems. We give sufficient conditions for symmetry breaking in both cases.
Schinagl, Christoph W; Vrabl, Pamela; Burgstaller, Wolfgang
2016-01-01
Fungal electron transport systems (ETS) are branched, involving alternative NADH dehydrogenases and an alternative terminal oxidase. These alternative respiratory enzymes were reported to play a role in pathogenesis, production of antibiotics and excretion of organic acids. The activity of these alternative respiratory enzymes strongly depends on environmental conditions. Functional analysis of fungal ETS under highly standardised conditions for cultivation, sample processing and respirometric assay are still lacking. We developed a highly standardised protocol to explore in vivo the ETS-and in particular the alternative oxidase-in Penicillium ochrochloron. This included cultivation in glucose-limited chemostat (to achieve a defined and reproducible physiological state), direct transfer without any manipulation of a broth sample to the respirometer (to maintain the physiological state in the respirometer as close as possible to that in the chemostat), and high-resolution respirometry (small sample volume and high measuring accuracy). This protocol was aimed at avoiding any changes in the physiological phenotype due to the high phenotypic plasticity of filamentous fungi. A stable oxygen consumption (transfer of a broth sample into the respirometer. Steady state respiration was 29% below its maximum respiratory capacity. Additionally to a rotenone-sensitive complex I and most probably a functioning complex III, the ETS of P. ochrochloron also contained a cyanide-sensitive terminal oxidase (complex IV). Activity of alternative oxidase was present constitutively. The degree of inhibition strongly depended on the sequence of inhibitor addition. This suggested, as postulated for plants, that the alternative terminal oxidase was in dynamic equilibrium with complex IV-independent of the rate of electron flux. This means that the onset of activity does not depend on a complete saturation or inhibition of the cytochrome pathway. PMID:26771937
Dynamical supersymmetry breaking on quantum moduli spaces
International Nuclear Information System (INIS)
Supersymmetry breaking by the quantum deformation of a classical moduli space is considered. A simple, non-chiral, renormalizable model is presented to illustrate this mechanism. The well-known, chiral, SU(3) x SU(2) model and its generalizations are shown to break supersymmetry by this mechanism in the limit Λ2>>Λ3. Other supersymmetry breaking models, with classical flat directions that are only lifted quantum mechanically, are presented. Finally, by integrating in vector matter, the strongly coupled region of chiral models with a dynamically generated superpotential is shown to be continuously connected to a weakly coupled description in terms of confined degrees of freedom, with supersymmetry broken at tree level. (orig.)
International Nuclear Information System (INIS)
This new edition of Prof. Strocchi's well received primer on rigorous aspects of symmetry breaking presents a more detailed and thorough discussion of the mechanism of symmetry breaking in classical field theory in relation with the Noether theorem. Moreover, the link between symmetry breaking without massless Goldstone bosons in Coulomb systems and in gauge theories is made more explicit in terms of the delocalized Coulomb dynamics. Furthermore, the chapter on the Higgs mechanism has been significantly expanded with a non-perturbative treatment of the Higgs phenomenon, at the basis of the standard model of particle physics, in the local and in the Coulomb gauges. Last but not least, a subject index has been added and a number of misprints have been corrected. From the reviews of the first edition: The notion of spontaneous symmetry breaking has proven extremely valuable, the problem is that most derivations are perturbative and heuristic. Yet mathematically precise versions do exist, but are not widely known. It is precisely the aim of his book to correct this unbalance. - It is remarkable to see how much material can actually be presented in a rigorous way (incidentally, many of the results presented are due to Strocchi himself), yet this is largely ignored, the original heuristic derivations being, as a rule, more popular. - At each step he strongly emphasizes the physical meaning and motivation of the various notions introduced, a book that fills a conspicuous gap in the literature, and does it rather well. It could also be a good basis for a graduate course in mathematical physics. It can be recommended to physicists as well and, of course, for physics/mathematics libraries. J.-P. Antoine, Physicalia 28/2, 2006 Strocchi's main emphasis is on the fact that the loss of symmetric behaviour requires both the non-symmetric ground states and the infinite extension of the system. It is written in a pleasant style at a level suitable for graduate students in
Symmetry Breaking in Finite Volume
Institute of Scientific and Technical Information of China (English)
LIU Chuan
2000-01-01
Spontaneous symmetry breaking is a cooperative phenomenon for systems with infinitely many degrees of freedom and it plays an essential role in quantum field theories. Lattice O(N) model is studied within the Hamiltonian approach using an adiabatic approximation. It is shown that the low-lying spectrum of the system in the broken phase can be understood by using the adiabatic, or Born-Oppenheimer approximation, which turns out to become an expansion in the inverse power of volume. In the infinite volume limit, the symmetry is broken while in the finite volume the slow rotation of the zero-momentum mode restores the symmetry and gives rise to the rotator spectrum, which has been observed in realistic Monte Carlo simulations.
DEFF Research Database (Denmark)
Hasse, Cathrine; Trentemøller, Stine
Break the Pattern! A critical enquiry into three scientific workplace cultures: Hercules, Caretakers and Worker Bees is the third publication of the international three year long project "Understanding Puzzles in the Gendered European Map" (UPGEM). By contrasting empirical findings from academic...... workplaces in the five UPGEM-countries (Denmark, Estonia, Finland, Italy and Poland) we identify three clusters of cultural patterns in physics as culture. We call these Hercules, Caretakers and Worker Bees. We also consider the influence of national cultural historical processes on the scientific culture...
Symmetries and Symmetry Breaking
Van Oers, W T H
2003-01-01
In understanding the world of matter, the introduction of symmetry principles following experimentation or using the predictive power of symmetry principles to guide experimentation is most profound. The conservation of energy, linear momentum, angular momentum, charge, and CPT involve fundamental symmetries. All other conservation laws are valid within a restricted subspace of the four interactions: the strong, the electromagnetic, the weak, and the gravitational interaction. In this paper comments are made regarding parity violation in hadronic systems, charge symmetry breaking in two nucleon and few nucleon systems, and time-reversal-invariance in hadronic systems.
Institute of Scientific and Technical Information of China (English)
1998-01-01
Many women who suffer from vaginitis have kept silent about their illness because they think it is shameful to have such a disease. The International Women’s Health Coalition (IWHC) has publicized the problem, referring to it as a "culture of silence"inherited from traditional thinking. The coalition has made attempts to improve women’s health conditions by changing people’s misconceptions about the disease. In 1997, under a grant from the American Ford Foundation, the Sichuan Provincial Women’s Federation carried out a study on women’s repro-ductive health, aimed at "breaking the silence."
Mikkelsen, Torben
2009-01-01
Two types of wind lidar?s have become available for ground-based vertical mean wind and turbulence profiling. A continuous wave (CW) wind lidar, and a pulsed wind lidar. Although they both are build upon the same recent 1.55 μ telecom fibre technology, they possess fundamental differences between their temporal and spatial resolution capabilities. A literature review of the two lidar systems spatial and temporal resolution characteristics will be presented, and the implication for the two lid...
Garraffo, C; Drake, J J; Downs, C
2012-01-01
We study the influence of the spatial resolution on scales of $5\\deg$ and smaller of solar surface magnetic field maps on global magnetohydrodynamic solar wind models, and on a model of coronal heating and X-ray emission. We compare the solutions driven by a low-resolution Wilcox Solar Observatory magnetic map, the same map with spatial resolution artificially increased by a refinement algorithm, and a high-resolution Solar and Heliospheric Observatory Michelson Doppler Imager map. We find that both the wind structure and the X-ray morphology are affected by the fine-scale surface magnetic structure. Moreover, the X-ray morphology is dominated by the closed loop structure between mixed polarities on smaller scales and shows significant changes between high and low resolution maps. We conclude that three-dimensional modeling of coronal X-ray emission has greater surface magnetic field spatial resolution requirements than wind modeling, and can be unreliable unless the dominant mixed polarity magnetic flux is p...
Spontaneous breaking of supersymmetry
Energy Technology Data Exchange (ETDEWEB)
Zumino, B.
1981-12-01
There has been recently a revival of interest in supersymmetric gauge theories, stimulated by the hope that supersymmetry might help in clarifying some of the questions which remain unanswered in the so called Grand Unified Theories and in particular the gauge hierarchy problem. In a Grand Unified Theory one has two widely different mass scales: the unification mass M approx. = 10/sup 15/GeV at which the unification group (e.g. SU(5)) breaks down to SU(3) x SU(2) x U(1) and the mass ..mu.. approx. = 100 GeV at which SU(2) x U(1) is broken down to the U(1) of electromagnetism. There is at present no theoretical understanding of the extreme smallness of the ratio ..mu../M of these two numbers. This is the gauge hierarchy problem. This lecture attempts to review the various mechanisms for spontaneous supersymmetry breaking in gauge theories. Most of the discussions are concerned with the tree approximation, but what is presently known about radiative correction is also reviewed.
Bootstrap Dynamical Symmetry Breaking
Directory of Open Access Journals (Sweden)
Wei-Shu Hou
2013-01-01
Full Text Available Despite the emergence of a 125 GeV Higgs-like particle at the LHC, we explore the possibility of dynamical electroweak symmetry breaking by strong Yukawa coupling of very heavy new chiral quarks Q . Taking the 125 GeV object to be a dilaton with suppressed couplings, we note that the Goldstone bosons G exist as longitudinal modes V L of the weak bosons and would couple to Q with Yukawa coupling λ Q . With m Q ≳ 700 GeV from LHC, the strong λ Q ≳ 4 could lead to deeply bound Q Q ¯ states. We postulate that the leading “collapsed state,” the color-singlet (heavy isotriplet, pseudoscalar Q Q ¯ meson π 1 , is G itself, and a gap equation without Higgs is constructed. Dynamical symmetry breaking is affected via strong λ Q , generating m Q while self-consistently justifying treating G as massless in the loop, hence, “bootstrap,” Solving such a gap equation, we find that m Q should be several TeV, or λ Q ≳ 4 π , and would become much heavier if there is a light Higgs boson. For such heavy chiral quarks, we find analogy with the π − N system, by which we conjecture the possible annihilation phenomena of Q Q ¯ → n V L with high multiplicity, the search of which might be aided by Yukawa-bound Q Q ¯ resonances.
A Fourth Chiral Generation And Susy Breaking
Wingerter, Akin
2011-01-01
We revisit four generations within the context of supersymmetry. We compute the perturbativity limits for the fourth generation Yukawa couplings and show that if the masses of the fourth generation lie within reasonable limits of their present experimental lower bounds, it is possible to have perturbativity only up to scales around 1000 TeV, i.e. the current experimental bounds and perturbative unification are mutually exclusive. Such low scales are ideally suited to incorporate gauge mediated supersymmetry breaking, where the mediation scale can be as low as 10-20 TeV. The minimal messenger model, however, is highly constrained. Lack of electroweak symmetry breaking rules out a large part of the parameter space, and in the remaining part, the fourth generation stau is tachyonic.
Four Generations: SUSY and SUSY Breaking
Godbole, Rohini M; Wingerter, Akin
2009-01-01
We revisit four generations within the context of supersymmetry. We compute the perturbativity limits for the fourth generation Yukawa couplings and show that if the masses of the fourth generation lie within reasonable limits of their present experimental lower bounds, it is possible to have perturbativity only up to scales around 1000 TeV. Such low scales are ideally suited to incorporate gauge mediated supersymmetry breaking, where the mediation scale can be as low as 10-20 TeV. The minimal messenger model, however, is highly constrained. While lack of electroweak symmetry breaking rules out a large part of the parameter space, a small region exists, where the fourth generation stau is tachyonic. General gauge mediation with its broader set of boundary conditions is better suited to accommodate the fourth generation.
Symmetry Breaking in Topological Quantum Gravity
Mielke, Eckehard W.
2015-01-01
A SL(5, R) gauge-invariant topological field theory of gravity and possible gauge unifications are considered in four-dimensions. The problem of quantization is evaluated in the asymptotic safety scenario. `Minimal' BF type models for the high energy limit are physically not quite realistic, a tiny symmetry breaking is needed to recover standard Einsteinian gravity for the oscopic metrical background with induced cosmological constant.
DEFF Research Database (Denmark)
Bredmose, Henrik; Peregrine, D.H.; Bullock, G.N.
2009-01-01
When an ocean wave breaks against a steep-fronted breakwater, sea wall or a similar marine structure, its impact on the structure can be very violent. This paper describes the theoretical studies that, together with field and laboratory investigations, have been carried out in order to gain a...... better understanding of the processes involved. The wave's approach towards a structure is modelled with classical irrotational flow to obtain the different types of impact profiles that may or may not lead to air entrapment. The subsequent impact is modelled with a novel compressible-flow model for a...... homogeneous mixture of incompressible liquid and ideal gas. This enables a numerical description of both trapped air pockets and the propagation of pressure shock waves through the aerated water. An exact Riemann solver is developed to permit a finite-volume solution to the flow model with smallest possible...
Electroweak breaking in supersymmetric models
Ibáñez, L E
1992-01-01
We discuss the mechanism for electroweak symmetry breaking in supersymmetric versions of the standard model. After briefly reviewing the possible sources of supersymmetry breaking, we show how the required pattern of symmetry breaking can automatically result from the structure of quantum corrections in the theory. We demonstrate that this radiative breaking mechanism works well for a heavy top quark and can be combined in unified versions of the theory with excellent predictions for the running couplings of the model. (To be published in ``Perspectives in Higgs Physics'', G. Kane editor.)
Numerical Simulation of a Seaway with Breaking
Dommermuth, Douglas; O'Shea, Thomas; Brucker, Kyle; Wyatt, Donald
2012-11-01
The focus of this presentation is to describe the recent efforts to simulate a fully non-linear seaway with breaking by using a high-order spectral (HOS) solution of the free-surface boundary value problem to drive a three-dimensional Volume of Fluid (VOF) solution. Historically, the two main types of simulations to simulate free-surface flows are the boundary integral equations method (BIEM) and high-order spectral (HOS) methods. BIEM calculations fail at the point at which the surface impacts upon itself, if not sooner, and HOS methods can only simulate a single valued free-surface. Both also employ a single-phase approximation in which the effects of the air on the water are neglected. Due to these limitations they are unable to simulate breaking waves and air entrainment. The Volume of Fluid (VOF) method on the other hand is suitable for modeling breaking waves and air entrainment. However it is computationally intractable to generate a realistic non-linear sea-state. Here, we use the HOS solution to quickly drive, or nudge, the VOF solution into a non-linear state. The computational strategies, mathematical formulation, and numerical implementation will be discussed. The results of the VOF simulation of a seaway with breaking will also be presented, and compared to the single phase, single valued HOS results.
Break location effects on PWR small break LOCA phenomena
International Nuclear Information System (INIS)
The report presents experimental results of a small lower plenum break test of SB-PV-01 conducted at the large-Scale Test Facility (LSTF) of the Rig-of-Safety Assessment (ROSA)-IV program. This test simulates a loss-of-coolant accident (LOCA) caused by instrument tubes break (break area corresponds to 0.5% of the cold leg flow area) in a Westinghouse-type pressurized water reactor (PWR) assuming both manual actuation for all of the high pressure injection (HPI) systems and failure of the auxiliary feedwater systems. The report clarifies long-term system responses, especially the core cooling conditions related to the primary mass inventory. Also it clarifies break location effects on small break LOCA phenomena by comparing other five similar LOCA tests with break locations at cold leg, hot leg, upper head, pressurizer top (TMI-type) and SG U-tubes. It is coucluded that the lower plenum break is the severest on core heatup due to the highest break flow rate and the least primary mass recovery after the ECCS among the six tests. (author)
Breaking Barriers in Polymer Additive Manufacturing
Energy Technology Data Exchange (ETDEWEB)
Love, Lonnie J [ORNL; Duty, Chad E [ORNL; Post, Brian K [ORNL; Lind, Randall F [ORNL; Lloyd, Peter D [ORNL; Kunc, Vlastimil [ORNL; Peter, William H [ORNL; Blue, Craig A [ORNL
2015-01-01
Additive Manufacturing (AM) enables the creation of complex structures directly from a computer-aided design (CAD). There are limitations that prevent the technology from realizing its full potential. AM has been criticized for being slow and expensive with limited build size. Oak Ridge National Laboratory (ORNL) has developed a large scale AM system that improves upon each of these areas by more than an order of magnitude. The Big Area Additive Manufacturing (BAAM) system directly converts low cost pellets into a large, three-dimensional part at a rate exceeding 25 kg/h. By breaking these traditional barriers, it is possible for polymer AM to penetrate new manufacturing markets.
International Nuclear Information System (INIS)
A new algorithm is developed for reconstructing the high-resolution three-dimensional diffraction intensity function of a globular biological macromolecule from many quantum-noise-limited two-dimensional X-ray laser diffraction patterns, each for an unknown orientation. The structural resolution is expressed as a function of the incident X-ray intensity and quantities characterizing the target molecule. A new two-step algorithm is developed for reconstructing the three-dimensional diffraction intensity of a globular biological macromolecule from many experimentally measured quantum-noise-limited two-dimensional X-ray laser diffraction patterns, each for an unknown orientation. The first step is classification of the two-dimensional patterns into groups according to the similarity of direction of the incident X-rays with respect to the molecule and an averaging within each group to reduce the noise. The second step is detection of common intersecting circles between the signal-enhanced two-dimensional patterns to identify their mutual location in the three-dimensional wavenumber space. The newly developed algorithm enables one to detect a signal for classification in noisy experimental photon-count data with as low as ∼0.1 photons per effective pixel. The wavenumber of such a limiting pixel determines the attainable structural resolution. From this fact, the resolution limit due to the quantum noise attainable by this new method of analysis as well as two important experimental parameters, the number of two-dimensional patterns to be measured (the load for the detector) and the number of pairs of two-dimensional patterns to be analysed (the load for the computer), are derived as a function of the incident X-ray intensity and quantities characterizing the target molecule
R-parity breaking phenomenology
International Nuclear Information System (INIS)
We review various features of the R-parity breaking phenomenology, with particular attention to the low energy observables, and to the patterns of the R-parity breaking interactions that arise in Grand Unified models. (author). 22 refs, 1 fig., 3 tabs
On partially entanglement breaking channels
Chruściński, Dariusz; Kossakowski, Andrzej
2005-01-01
Using well known duality between quantum maps and states of composite systems we introduce the notion of Schmidt number of a quantum channel. It enables one to define classes of quantum channels which partially break quantum entanglement. These classes generalize the well known class of entanglement breaking channels.
International Nuclear Information System (INIS)
We study a set of new functionals (called entanglement–breaking indices) which characterize how many local iterations of a given (local) quantum channel are needed in order to completely destroy the entanglement between the system of interest over which the transformation is defined and an external ancilla. The possibility of contrasting the noisy effects introduced by the channel iterations via the action of intermediate (filtering) transformations is analyzed. We provide some examples in which our functionals can be exactly calculated. The differences between unitary and non-unitary filtering operations are analyzed showing that, at least for systems of dimension d larger than or equal to 3, the non-unitary choice is preferable (the gap between the performances of the two cases being divergent in some cases). For d = 2 (qubit case), on the contrary, no evidences of the presence of such gap is revealed: we conjecture that for this special case unitary filtering transformations are optimal. The scenario in which more general filtering protocols are allowed is also discussed in some detail. The case of a depolarizing noise acting on a two–qubit system is exactly solved in a general case
Kinematic dynamo, supersymmetry breaking, and chaos
Ovchinnikov, Igor V.; Enßlin, Torsten A.
2016-04-01
The kinematic dynamo (KD) describes the growth of magnetic fields generated by the flow of a conducting medium in the limit of vanishing backaction of the fields onto the flow. The KD is therefore an important model system for understanding astrophysical magnetism. Here, the mathematical correspondence between the KD and a specific stochastic differential equation (SDE) viewed from the perspective of the supersymmetric theory of stochastics (STS) is discussed. The STS is a novel, approximation-free framework to investigate SDEs. The correspondence reported here permits insights from the STS to be applied to the theory of KD and vice versa. It was previously known that the fast KD in the idealistic limit of no magnetic diffusion requires chaotic flows. The KD-STS correspondence shows that this is also true for the diffusive KD. From the STS perspective, the KD possesses a topological supersymmetry, and the dynamo effect can be viewed as its spontaneous breakdown. This supersymmetry breaking can be regarded as the stochastic generalization of the concept of dynamical chaos. As this supersymmetry breaking happens in both the diffusive and the nondiffusive cases, the necessity of the underlying SDE being chaotic is given in either case. The observed exponentially growing and oscillating KD modes prove physically that dynamical spectra of the STS evolution operator that break the topological supersymmetry exist with both real and complex ground state eigenvalues. Finally, we comment on the nonexistence of dynamos for scalar quantities.
Analysis of chiral symmetry breaking mechanism
International Nuclear Information System (INIS)
The renormalization group invariant quark condensate μ is determinate both from the consistent equation for quark condensate in the chiral limit and from the Schwinger-Dyson (SD) equation improved by the intermediate range QCD force singular like δ (q) which is associated with the gluon condensate. The solutions of μ in these two equations are consistent. We also obtain the critical strong coupling constant αc above which chiral symmetry breaks in two approaches. The nonperturbative kernel of the SD equation makes αc smaller and μ bigger. An intuitive picture of the condensation above αc is discussed. In addition, with the help of the Slavnov-Taylor-Ward (STW) identity we derive the equations for the nonperturbative quark propagator from SD equation in the presence of the intermediate-range force is also responsible for dynamical chiral symmetry breaking. (author)
Spontaneous symmetry breaking in QCD
International Nuclear Information System (INIS)
We study dynamical chiral symmetry breaking in QCD by the use of the generalized Hartree-Fock method. The low energy quark mass is calculated to the second order of diagrammatic expansion around shifted perturbative vacuum where quarks are massive. We show that the low energy mass is finite and renormalization group invariant. We find that the finite mass gap emerges as the solutions of gap equation and stationarity condition, thereby breaking the chiral symmetry. We also discuss the possibility that the breaking solution may exist up to all orders. (author)
Weidenbach, C.
1994-01-01
Minimal resolution restricts the applicability of resolution and factorization to minimal literals. Minimality is an abstract criterion. It is shown that if the minimality criterion satisfies certain properties minimal resolution is sound and complete. Hyper resolution, ordered resolution and lock resolution are known instances of minimal resolution. We also introduce new instances of the general completeness result, correct some mistakes in existing literature and give some general redundanc...
Visser, R; Godart, J; Wauben, D J L; Langendijk, J A; Van't Veld, A A; Korevaar, E W
2016-05-21
The objective of this study was to introduce a new iterative method to reconstruct multi leaf collimator (MLC) positions based on low resolution ionization detector array measurements and to evaluate its error detection performance. The iterative reconstruction method consists of a fluence model, a detector model and an optimizer. Expected detector response was calculated using a radiotherapy treatment plan in combination with the fluence model and detector model. MLC leaf positions were reconstructed by minimizing differences between expected and measured detector response. The iterative reconstruction method was evaluated for an Elekta SLi with 10.0 mm MLC leafs in combination with the COMPASS system and the MatriXX Evolution (IBA Dosimetry) detector with a spacing of 7.62 mm. The detector was positioned in such a way that each leaf pair of the MLC was aligned with one row of ionization chambers. Known leaf displacements were introduced in various field geometries ranging from -10.0 mm to 10.0 mm. Error detection performance was tested for MLC leaf position dependency relative to the detector position, gantry angle dependency, monitor unit dependency, and for ten clinical intensity modulated radiotherapy (IMRT) treatment beams. For one clinical head and neck IMRT treatment beam, influence of the iterative reconstruction method on existing 3D dose reconstruction artifacts was evaluated. The described iterative reconstruction method was capable of individual MLC leaf position reconstruction with millimeter accuracy, independent of the relative detector position within the range of clinically applied MU's for IMRT. Dose reconstruction artifacts in a clinical IMRT treatment beam were considerably reduced as compared to the current dose verification procedure. The iterative reconstruction method allows high accuracy 3D dose verification by including actual MLC leaf positions reconstructed from low resolution 2D measurements. PMID:27100169
Topcolor breaking through boundary conditions
International Nuclear Information System (INIS)
The nontrivial boundary conditions (BC's) for the topcolor breaking are investigated in the context of the TeV-scale extra dimension scenario. In the gauge symmetry breaking mechanism via the BC's we do not need to incorporate a dynamical mechanism for the topcolor breaking into the model. Moreover, the topcolor breaking can be realized without introducing explicitly a (composite) scalar field. We present a six dimensional model where the top and bottom quarks in the bulk have the topcolor charge while the other quarks in the bulk do not. We also put the electroweak gauge interaction in the six dimensional bulk. The bottom quark condensation is naturally suppressed owing to the powerlike running of the bulk U(1)Y interaction, so that only the top condensation is expected to take place. We explore such a possibility based on the ladder Schwinger-Dyson equation and show the cutoff to make the model viable
Active and break spells of the Indian summer monsoon
Indian Academy of Sciences (India)
M Rajeevan; Sulochana Gadgil; Jyoti Bhate
2010-06-01
In this paper, we suggest criteria for the identification of active and break events of the Indian summer monsoon on the basis of recently derived high resolution daily gridded rainfall dataset over India (1951–2007). Active and break events are defined as periods during the peak monsoon months of July and August, in which the normalized anomaly of the rainfall over a critical area, called the monsoon core zone exceeds 1 or is less than −1.0 respectively, provided the criterion is satisfied for at least three consecutive days. We elucidate the major features of these events. We consider very briefly the relationship of the intraseasonal fluctuations between these events and the interannual variation of the summer monsoon rainfall. We find that breaks tend to have a longer life-span than active spells. While, almost 80% of the active spells lasted 3–4 days, only 40% of the break spells were of such short duration. A small fraction (9%) of active spells and 32% of break spells lasted for a week or longer. While active events occurred almost every year, not a single break occurred in 26% of the years considered. On an average, there are 7 days of active and break events from July through August. There are no significant trends in either the days of active or break events. We have shown that there is a major difference between weak spells and long intense breaks. While weak spells are characterized by weak moist convective regimes, long intense break events have a heat trough type circulation which is similar to the circulation over the Indian subcontinent before the onset of the monsoon. The space-time evolution of the rainfall composite patterns suggests that the revival from breaks occurs primarily from northward propagations of the convective cloud zone. There are important differences between the spatial patterns of the active/break spells and those characteristic of interannual variation, particularly those associated with the link to ENSO. Hence, the
Supersymmetry Breaking in Warped Geometry
Choi, Kiwoon; Kim, Do Young; Kim, Ian-Woo; Kobayashi, Tatsuo
2003-01-01
We examine the soft supersymmetry breaking parameters in supersymmetric theories on a slice of AdS_5 which generate the hierarchical Yukawa couplings by dynamically localizing the bulk matter fields in extra dimension. Such models can be regarded as the AdS dual of the recently studied 4-dimensional models which contain a supersymmetric CFT to generate the hierarchical Yukawa couplings. In such models, if supersymmetry breaking is mediated by the bulk radion superfield and/or some brane chira...
The Beam Break-Up Numerical Simulator
Energy Technology Data Exchange (ETDEWEB)
Travish, G.A.
1989-11-01
Beam Break-Up (BBU) is a severe constraint in accelerator design, limiting beam current and quality. The control of BBU has become the focus of much research in the design of the next generation collider, recirculating and linear induction accelerators and advanced accelerators. Determining the effect on BBU of modifications to cavities, the focusing elements or the beam is frequently beyond the ability of current analytic models. A computer code was written to address this problem. The Beam Break-Up Numerical Simulator (BBUNS) was designed to numerically solve for beam break-up (BBU) due to an arbitrary transverse wakefield. BBUNS was developed to be as user friendly as possible on the Cray computer series. The user is able to control all aspects of input and output by using a single command file. In addition, the wakefield is specified by the user and read in as a table. The program can model energy variations along and within the beam, focusing magnetic field profiles can be specified, and the graphical output can be tailored. In this note we discuss BBUNS, its structure and application. Included are detailed instructions, examples and a sample session of BBUNS. This program is available for distribution. 50 refs., 18 figs., 5 tabs.
The Beam Break-Up Numerical Simulator
International Nuclear Information System (INIS)
Beam Break-Up (BBU) is a severe constraint in accelerator design, limiting beam current and quality. The control of BBU has become the focus of much research in the design of the next generation collider, recirculating and linear induction accelerators and advanced accelerators. Determining the effect on BBU of modifications to cavities, the focusing elements or the beam is frequently beyond the ability of current analytic models. A computer code was written to address this problem. The Beam Break-Up Numerical Simulator (BBUNS) was designed to numerically solve for beam break-up (BBU) due to an arbitrary transverse wakefield. BBUNS was developed to be as user friendly as possible on the Cray computer series. The user is able to control all aspects of input and output by using a single command file. In addition, the wakefield is specified by the user and read in as a table. The program can model energy variations along and within the beam, focusing magnetic field profiles can be specified, and the graphical output can be tailored. In this note we discuss BBUNS, its structure and application. Included are detailed instructions, examples and a sample session of BBUNS. This program is available for distribution. 50 refs., 18 figs., 5 tabs
Hahn, Noemi; Snedeker, Jesse; Rabagliati, Hugh
2015-12-01
Individuals with autism spectrum disorders (ASD) have often been reported to have difficulty integrating information into its broader context, which has motivated the Weak Central Coherence theory of ASD. In the linguistic domain, evidence for this difficulty comes from reports of impaired use of linguistic context to resolve ambiguous words. However, recent work has suggested that impaired use of linguistic context may not be characteristic of ASD, and is instead better explained by co-occurring language impairments. Here, we provide a strong test of these claims, using the visual world eye tracking paradigm to examine the online mechanisms by which children with autism resolve linguistic ambiguity. To address concerns about both language impairments and compensatory strategies, we used a sample whose verbal skills were strong and whose average age (7; 6) was lower than previous work on lexical ambiguity resolution in ASD. Participants (40 with autism and 40 controls) heard sentences with ambiguous words in contexts that either strongly supported one reading or were consistent with both (John fed/saw the bat). We measured activation of the unintended meaning through implicit semantic priming of an associate (looks to a depicted baseball glove). Contrary to the predictions of weak central coherence, children with ASD, like controls, quickly used context to resolve ambiguity, selecting appropriate meanings within a second. We discuss how these results constrain the generality of weak central coherence. PMID:25820816
Heavy quark solitons strangeness and symmetry breaking
Momen, A; Subbaraman, A; Momen, Arshad; Schechter, Joseph; Subbaraman, Anand
1994-01-01
We discuss the generalization of the Callan-Klebanov model to the case of heavy quark baryons. The light flavor group is considered to be $SU(3)$ and the limit of heavy spin symmetry is taken. The presence of the Wess-Zumino-Witten term permits the neat development of a picture , at the collective level, of a light diquark bound to a ``heavy" quark with decoupled spin degree of freedom. The consequences of $SU(3)$ symmetry breaking are discussed in detail. We point out that the $SU(3)$ mass splittings of the heavy baryons essentially measure the ``low energy" physics once more and that the comparison with experiment is satisfactory.
Heavy quark solitons: Strangeness and symmetry breaking
International Nuclear Information System (INIS)
We discuss the generalization of the Callan-Klebanov model to the case of heavy quark baryons. The light flavor group is considered to be SU(3) and the limit of heavy spin symmetry is taken. The presence of the Wess-Zumino-Witten term permits the neat development of a picture, at the collective level, of a light diquark bound to a ''heavy'' quark with decoupled spin degree of freedom. The consequences of SU(3) symmetry breaking are discussed in detail. We point out that the SU(3) mass splitting of the heavy baryons essentially measure the ''low energy'' physics once more and that the comparison with experiment is satisfactory
N. Bärtsch-Ritter; J. Keller; Dommen, J.; Prévôt, André,
2003-01-01
The three-dimensional photochemical model UAM-V is used to investigate the effects of various meteorological conditions and of the coarseness of emission inventories on the ozone concentration and ROG/NOx limitation of the ozone production in the Po Basin in the northern part of Italy. As a base case, the high ozone episode with up to 200 ppb on 13 May 1998 was modelled and previously thoroughly evaluated with measurements gained during a large field experiment. The performed variations in me...
Experimental investigation of two oil dispersion pathways by breaking waves
Li, Cheng; Katz, Joseph
2014-11-01
This experimental study focuses on generation and size distribution of airborne and subsurface oil droplets as breaking surface waves interact with a crude oil slick (MC252 surrogate). Experiments in a specialized wave tank investigate the effects of wave height and wave properties (e.g. spilling vs. plunging), as well as drastically reducing the oil-water interfacial tension by orders of magnitude by introducing dispersant (Coexist 9500-A). This dispersant is applied at varying dispersant-to-oil ratios either by premixing or surface spraying, the latter consistent with typical application. The data include high-speed visualizations of processes affecting the entrainment of subsurface oil and bubbles as well as airborne aerosols. High-speed digital holographic cinematography is employed to track the droplet trajectories, and quantify the droplet size distributions above and below the surface. Introduction of dispersants drastically reduces the size of subsurface droplets to micron and even submicron levels. Ahead of the wave, the 25 μm (our present resolution limit) to 2 mm airborne droplet trajectories are aligned with the wave direction. Behind the wave, these droplets reverse their direction, presumably due to the airflow above the wave. Supported by Gulf of Mexico Research Initiative (GoMRI).
A Comparison of Measured and Predicted Wave-Impact Pressures from Breaking and Non-breaking Waves
Fullerton, Anne M; Brewton, Susan; Brucker, Kyle A; O'Shea, Thomas T; Dommermuth, Douglas G
2014-01-01
Impact loads from waves on vessels and coastal structures are complex and may involve wave breaking, which has made these loads difficult to estimate numerically or empirically. Results from previous experiments have shown a wide range of forces and pressures measured from breaking and nonbreaking waves, with no clear trend between wave characteristics and the localized forces and pressures that they generate. In 2008, a canonical breaking wave impact data set was obtained at the Naval Surface Warfare Center, Carderock Division, by measuring the distribution of impact pressures of incident nonbreaking and breaking waves on one face of a cube. This experimental effort was sponsored by the Office of Naval Research (ONR), under the Dynamics of Interacting Platforms Program, Program Manager Dr. Ron Joslin. The effects of wave height, wavelength, face orientation, face angle, and submergence depth were investigated. Additionally, a limited number of runs were made at low forward speeds, ranging from about 0.5 to 2...
Energy Technology Data Exchange (ETDEWEB)
Hamman, E.; Zorgati, R.
1995-12-31
Eddy current non-destructive testing is used by EDF to detect flaws affecting conductive objects such as steam generator tubes. With a view to obtaining ever more accurate information on equipment integrity, thereby facilitating diagnosis, studies aimed at using measurements to reconstruct an image of the flaw have been proceeding now for about ten years. In this context, our approach to eddy current imaging is based on inverse problem formalism. The direct problem, involving a mathematical model linking measurements provided by a probe with variables characterizing the defect, is dealt with elsewhere. Using the model results, we study the possibility of inverting it, i.e. of reconstructing an image of the flaw from the measurements. We first give an overview of the different inversion techniques, representative of the state of the art and all based on linearization of the inverse problem by means of the Born approximation. The model error resulting from an excessive Born approximation nevertheless severely limits the quantity of the images which can be obtained. In order to counteract this often critical error and extend the eddy current imaging application field, we have to del with the non-linear inverse problem. A method derived from recent research is proposed and implemented to ensure consistency with the exact model. Based on an `optimization` type approach and provided with a convergence theorem, the method is highly efficient. (authors). 17 refs., 7 figs., 1 append.
Symmetry breaking in molecular ferroelectrics.
Shi, Ping-Ping; Tang, Yuan-Yuan; Li, Peng-Fei; Liao, Wei-Qiang; Wang, Zhong-Xia; Ye, Qiong; Xiong, Ren-Gen
2016-07-11
Ferroelectrics are inseparable from symmetry breaking. Accompanying the paraelectric-to-ferroelectric phase transition, the paraelectric phase adopting one of the 32 crystallographic point groups is broken into subgroups belonging to one of the 10 ferroelectric point groups, i.e. C1, C2, C1h, C2v, C4, C4v, C3, C3v, C6 and C6v. The symmetry breaking is captured by the order parameter known as spontaneous polarization, whose switching under an external electric field results in a typical ferroelectric hysteresis loop. In addition, the responses of spontaneous polarization to other external excitations are related to a number of physical effects such as second-harmonic generation, piezoelectricity, pyroelectricity and dielectric properties. Based on these, this review summarizes recent developments in molecular ferroelectrics since 2011 and focuses on the relationship between symmetry breaking and ferroelectricity, offering ideas for exploring high-performance molecular ferroelectrics. PMID:27051889
Ramírez, Juan David; Herrera, Claudia; Bogotá, Yizeth; Duque, María Clara; Suárez-Rivillas, Alejandro; Guhl, Felipe
2013-02-15
Trypanosoma cruzi is the causative agent of American trypanosomiasis, a complex zoonotic disease that affects more than 10million people in the Americas. Strains of this parasite possess a significant amount of genetic variability and hence can be divided into at least six discrete typing units (DTUs). The life cycle of this protist suggests that multiclonal infections may emerge due to the likelihood of contact of triatomine insects with more than 100 mammal species. To date, there have been a few studies on but no consensus regarding standardised methodologies to identify multiclonal infections caused by this parasite. Hence, the aim of this study was to develop and validate a limiting dilution assay (LDA) to identify multiclonal infections in T. cruzi populations by comparing the feasibility and reliability of this method with the widely applied solid phase blood agar (SPBA) methodology. We cloned reference strains belonging to three independent genotypes (TcI, TcII, and TcIV) and mixed infections (TcI+TcII) using LDA and SPBA; the comparison was conducted by calculating the feasibility and reliability of the methods employed. Additionally, we implemented LDA in strains recently isolated from Homo sapiens, Rhodnius prolixus, Triatoma venosa, Panstrongylus geniculatus, Tamandua tetradactyla, Rattus rattus, Didelphis marsupialis and Dasypus novemcinctus, with the aim of resolving multiclonal infections using molecular characterization employing SL-IR (spliced leader intergenic region of mini-exon gene), the 24Sα rDNA gene and microsatellite loci. The results reported herein demonstrate that LDA is an optimal methodology to distinguish T. cruzi subpopulations based on microsatellite markers by showing the absence of multiple peaks within a single locus. Conversely, SPBA showed patterns of multiple peaks within a single locus suggesting multiclonal events. The biological consequences of these results and the debate between multiclonality and aneuploidy are
Give me a better break: Choosing workday break activities to maximize resource recovery.
Hunter, Emily M; Wu, Cindy
2016-02-01
Surprisingly little research investigates employee breaks at work, and even less research provides prescriptive suggestions for better workday breaks in terms of when, where, and how break activities are most beneficial. Based on the effort-recovery model and using experience sampling methodology, we examined the characteristics of employee workday breaks with 95 employees across 5 workdays. In addition, we examined resources as a mediator between break characteristics and well-being. Multilevel analysis results indicated that activities that were preferred and earlier in the work shift related to more resource recovery following the break. We also found that resources mediated the influence of preferred break activities and time of break on health symptoms and that resource recovery benefited person-level outcomes of emotional exhaustion, job satisfaction, and organizational citizenship behavior. Finally, break length interacted with the number of breaks per day such that longer breaks and frequent short breaks were associated with more resources than infrequent short breaks. PMID:26375961
Cosmic acceleration from Abelian symmetry breaking
International Nuclear Information System (INIS)
We discuss a consistent theory for a self-interacting vector field, breaking an Abelian symmetry in such a way to obtain an interesting behavior for its longitudinal polarization. In an appropriate decoupling limit, the dynamics of the longitudinal mode is controlled by Galileon interactions. The full theory away from the decoupling limit does not propagate ghost modes, and can be investigated in regimes where non-linearities become important. When coupled to gravity, this theory provides a candidate for dark energy, since it admits de Sitter cosmological solutions characterized by a technically natural value for the Hubble parameter. We also consider the homogeneous evolution when, besides the vector, additional matter in the form of perfect fluids is included. We find that the vector can have an important role in characterizing the universe expansion
An Analysis of Break,Break,Break Based on the Stylistic Theory
Institute of Scientific and Technical Information of China (English)
李瑶
2014-01-01
Break,Break,Break is a poem by Alfred Lord Tennyson, the Poet Laureate during the Queen Victoria's reign. This exquisite little poem is wel known for the poet’s grief-stricken feelings and heart-broken emotions over the premature death of his best friend, Arthur Henry Hal am. Most of the previous studies on this poem focus on the emotional level to consider it as an elegy, expressing sorrow and lamentation for the death of a particular person. However, in order to have a deep understanding in general, this paper analyzes the poem based on the stylistic theory, concerning on the phonological level and the grammatical level. It aims at helping the readers to cultivate a sense of appropriateness, to sharpen the understanding and appreciation of literary works and to achieve adaptation in translation.
Strong coupling electroweak symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Barklow, T.L. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Burdman, G. [Univ. of Wisconsin, Madison, WI (United States). Dept. of Physics; Chivukula, R.S. [Boston Univ., MA (United States). Dept. of Physics
1997-04-01
The authors review models of electroweak symmetry breaking due to new strong interactions at the TeV energy scale and discuss the prospects for their experimental tests. They emphasize the direct observation of the new interactions through high-energy scattering of vector bosons. They also discuss indirect probes of the new interactions and exotic particles predicted by specific theoretical models.
Sediment transport under breaking waves
DEFF Research Database (Denmark)
Christensen, Erik Damgaard; Hjelmager Jensen, Jacob; Mayer, Stefan
2000-01-01
generated at the surface where the wave breaks as well as the turbulence generated near the bed due to the wave-motion and the undertow. In general, the levels of turbulent kinetic energy are found to be higher than experiments show. This results in an over prediction of the sediment transport. Nevertheless...
International Nuclear Information System (INIS)
This paper contributes to the literature of the stationarity of financial time series and the literature on oil and macroeconomics in several ways. First, it uses Kejriwal and Perron (2010) sequential procedure to endogenously determine multiple structural changes in real oil prices without facing the circular testing problem between structural changes and stationary assumptions of previous tests. Second, it performs a diagnostic check to detect the significance and magnitude of the potential breaks. Third, it uses the above information to test for the existence of stochastic trends in real oil prices, and fourth, it speculates about possible explanations for the break dates found in order to encourage further work and discussions. The exercise uses monthly data from January 1861 to August 2011. - Highlights: ► The model endogenously determine multiple structural changes in real oil prices. ► The methods used does not face the circular testing problem. ► It also detect the significance and magnitude of the breaks detected. ► It tests for the existence of stochastic trends. ► It explains the reasons for the break dates found
Instantons and chiral symmetry breaking
International Nuclear Information System (INIS)
A detailed investigation of chiral symmetry breaking due to instanton dynamics is carried out, within the framework of the dilute gas approximation, for quarks in both the fundamental and adjoint representations of SU(2). The momentum dependence of the dynamical mass is found to be very similar in each representation. (orig.)
Donovan, Peter
2014-01-01
Covers the historical context and the evolution of the technically complex Allied Signals Intelligence (Sigint) activity against Japan from 1920 to 1945 Describes, explains and analyzes the code breaking techniques developed during the war in the Pacific Exposes the blunders (in code construction and use) made by the Japanese Navy that led to significant US Naval victories
Dogan, Suzan
2016-07-01
Accretion discs are common in binary systems, and they are often found to be misaligned with respect to the binary orbit. The gravitational torque from a companion induces nodal precession in misaligned disc orbits. In this study, we first calculate whether this precession is strong enough to overcome the internal disc torques communicating angular momentum. We compare the disc precession torque with the disc viscous torque to determine whether the disc should warp or break. For typical parameters precession wins: the disc breaks into distinct planes that precess effectively independently. To check our analytical findings, we perform 3D hydrodynamical numerical simulations using the PHANTOM smoothed particle hydrodynamics code, and confirm that disc breaking is widespread and enhances accretion on to the central object. For some inclinations, the disc goes through strong Kozai cycles. Disc breaking promotes markedly enhanced and variable accretion and potentially produces high-energy particles or radiation through shocks. This would have significant implications for all binary systems: e.g. accretion outbursts in X-ray binaries and fuelling supermassive black hole (SMBH) binaries. The behaviour we have discussed in this work is relevant to a variety of astrophysical systems, for example X-ray binaries, where the disc plane may be tilted by radiation warping, SMBH binaries, where accretion of misaligned gas can create effectively random inclinations and protostellar binaries, where a disc may be misaligned by a variety of effects such as binary capture/exchange, accretion after binary formation.
Small Break Air Ingress Experiment
Energy Technology Data Exchange (ETDEWEB)
Chang Oh; Eung Soo Kim
2011-09-01
The small break air-ingress experiment, described in this report, is designed to investigate air-ingress phenomena postulated to occur in pipes in a very high temperature gas-cooled reactor (VHTRs). During this experiment, air-ingress rates were measured for various flow and break conditions through small holes drilled into a pipe of the experimental apparatus. The holes were drilled at right angles to the pipe wall such that a direction vector drawn from the pipe centerline to the center of each hole was at right angles with respect to the pipe centerline. Thus the orientation of each hole was obtained by measuring the included angle between the direction vector of each hole with respect to a reference line anchored on the pipe centerline and pointing in the direction of the gravitational force. Using this reference system, the influence of several important parameters on the air ingress flow rate were measured including break orientation, break size, and flow velocity . The approach used to study the influence of these parameters on air ingress is based on measuring the changes in oxygen concentrations at various locations in the helium flow circulation system as a function of time using oxygen sensors (or detectors) to estimate the air-ingress rates through the holes. The test-section is constructed of a stainless steel pipe which had small holes drilled at the desired locations.
Inflationary implications of supersymmetry breaking
Borghese, Andrea; Roest, Diederik; Zavala, Ivonne
2013-01-01
We discuss a general bound on the possibility to realise inflation in any minimal supergravity with F-terms. The derivation crucially depends on the sGoldstini, the scalar field directions that are singled out by spontaneous supersymmetry breaking. The resulting bound involves both slow-roll paramet
Physical Activity Breaks and Facilities in US Secondary Schools
Hood, Nancy E.; Colabianchi, Natalie; Terry-McElrath, Yvonne M.; O'Malley, Patrick M.; Johnston, Lloyd D.
2014-01-01
Background: Research on physical activity breaks and facilities (indoor and outdoor) in secondary schools is relatively limited. Methods: School administrators and students in nationally representative samples of 8th (middle school) and 10th/12th grade (high school) students were surveyed annually from 2008-2009 to 2011-2012. School administrators…
A model of intrinsic symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Ge, Li [Research Center for Quantum Manipulation, Department of Physics, Fudan University, Shanghai 200433 (China); Li, Sheng [Department of Physics, Zhejiang Normal University, Zhejiang 310004 (China); George, Thomas F., E-mail: tfgeorge@umsl.edu [Office of the Chancellor and Center for Nanoscience, Department of Chemistry and Biochemistry, University of Missouri-St. Louis, St. Louis, MO 63121 (United States); Department of Physics and Astronomy, University of Missouri-St. Louis, St. Louis, MO 63121 (United States); Sun, Xin, E-mail: xin_sun@fudan.edu.cn [Research Center for Quantum Manipulation, Department of Physics, Fudan University, Shanghai 200433 (China)
2013-11-01
Different from the symmetry breaking associated with a phase transition, which occurs when the controlling parameter is manipulated across a critical point, the symmetry breaking presented in this Letter does not need parameter manipulation. Instead, the system itself suddenly undergoes symmetry breaking at a certain time during its evolution, which is intrinsic symmetry breaking. Through a polymer model, it is revealed that the origin of the intrinsic symmetry breaking is nonlinearity, which produces instability at the instance when the evolution crosses an inflexion point, where this instability breaks the original symmetry.
Energy Technology Data Exchange (ETDEWEB)
Perez, Pedro; Malano, Francisco; Valente, Mauro, E-mail: valente@famaf.unc.edu.ar [Universidad Nacional de Cordoba, Cordoba (Argentina). Fac. de Matematica, Astronomia y Fisica (FaMAF)
2012-07-01
Since its successful implementation for clinical diagnostic, positron emission tomography (PET) represents the most promising medical imaging technique. The recent major growth of PET imaging is mainly due to its ability to trace the biologic pathways of different compounds in the patient's body, assuming the patient can be labeled with some PET isotope. Regardless of the type of isotope, the PET imaging method is based on the detection of two 511-keV gamma photons being emitted in opposite directions, with almost 180 deg between them, as a consequence of electron-positron annihilation. Therefore, this imaging method is intrinsically limited by random uncertainties in spatial resolutions, related with differences between the actual position of positron emission and the location of the detected annihilation. This study presents an approach with the Monte Carlo method to analyze the influence of this effect on different isotopes of potential implementation in PET. (author)
Namiki, Ryo
2013-01-01
We consider composability of quantum channels from a limited amount of entanglement via local operations and classical communication (LOCC). We show that any $k$-partially entanglement breaking channel can be composed from an entangled state with Schmidt number of $k$ via one-way LOCC. From the entanglement assisted construction we can reach an alternative definition of partially entanglement breaking channels.
Quantum phase transitions about parity breaking in matrix product systems
Institute of Scientific and Technical Information of China (English)
ZHU Jing-Min
2011-01-01
According to our scheme to construct quantum phase transitions (QPTs) in spin chain systems with matrix product ground states, we first successfully combine matrix product state (MPS) QPTs with spontaneous symmetry breaking. For a concrete model, we take into account a kind of MPS QPTs accompanied by spontaneous parity breaking, though for either side of the critical point the GS is typically unique, and show that the kind of MPS QPTs occur only in the thermodynamic limit and are accompanied by the appearance of singularities, diverging correlation length, vanishing energy gap and the entanglement entropy of a half-infinite chain not only staying finite but also whose first derivative discontinuous.
Breaking GSM with rainbow Tables
Meyer, Steven
2011-01-01
Since 1998 the GSM security has been academically broken but no real attack has ever been done until in 2008 when two engineers of Pico Computing (FPGA manufacture) revealed that they could break the GSM encryption in 30 seconds with 200'000$ hardware and precomputed rainbow tables. Since then the hardware was either available for rich people only or was confiscated by government agencies. So Chris Paget and Karsten Nohl decided to react and do the same thing but in a distributed open source form (on torrent). This way everybody could "enjoy" breaking GSM security and operators will be forced to upgrade the GSM protocol that is being used by more than 4 billion users and that is more than 20 years old.
Renormalizable theories with symmetry breaking
Becchi, Carlo M
2016-01-01
The description of symmetry breaking proposed by K. Symanzik within the framework of renormalizable theories is generalized from the geometrical point of view. For an arbitrary compact Lie group, a soft breaking of arbitrary covariance, and an arbitrary field multiplet, the expected integrated Ward identities are shown to hold to all orders of renormalized perturbation theory provided the Lagrangian is suitably chosen. The corresponding local Ward identity which provides the Lagrangian version of current algebra through the coupling to an external, classical, Yang-Mills field, is then proved to hold up to the classical Adler-Bardeen anomaly whose general form is written down. The BPHZ renormalization scheme is used throughout in such a way that the algebraic structure analyzed in the present context may serve as an introduction to the study of fully quantized gauge theories.
Symmetry breaking in supersymmetric GUTs
International Nuclear Information System (INIS)
This paper analyzes the first step of symmetry breaking in N=1 supersymmetric unified theories. The possible patterns of gauge symmetry breaking consistent with supersymmetry are characterized. Some well-known properties of the scalar potential in supersymmetric gauge theories are reviewed. Simple methods to discover which v.e.v.'s of a given multiplet of scalar fields are consistent with the conditions of given equations are introduced. The vanishing of the D2-term and of the F2-term is discussed and a simple lemma derived from the former. The results of these discussions are applied to some possible candidates for a supersymmetric gauge theory based on the gauge groups SU(5), 0(10), and E6
Symmetries, Symmetry Breaking, Gauge Symmetries
Strocchi, Franco
2015-01-01
The concepts of symmetry, symmetry breaking and gauge symmetries are discussed, their operational meaning being displayed by the observables {\\em and} the (physical) states. For infinitely extended systems the states fall into physically disjoint {\\em phases} characterized by their behavior at infinity or boundary conditions, encoded in the ground state, which provide the cause of symmetry breaking without contradicting Curie Principle. Global gauge symmetries, not seen by the observables, are nevertheless displayed by detectable properties of the states (superselected quantum numbers and parastatistics). Local gauge symmetries are not seen also by the physical states; they appear only in non-positive representations of field algebras. Their role at the Lagrangian level is merely to ensure the validity on the physical states of local Gauss laws, obeyed by the currents which generate the corresponding global gauge symmetries; they are responsible for most distinctive physical properties of gauge quantum field ...
Breaking of de Sitter Symmetry
Bander, Myron
2010-01-01
We show that an interacting spin-0 field on a de Sitter space background will break the underlying de Sitter symmetry. This is done first for a (1+1) de Sitter space where a boson-fermion correspondence permits us to solve certain interacting theories by transforming them into free ones of opposite statistics. A massless boson interacting by a sine-Gordon potential is shown to be equivalent to a free massive fermion with the mass depending on the de Sitter time thus breaking the symmetry explicitly. We then show that for larger dimensions and any boson potential, to one loop, an anomaly develops and the currents generating the de Sitter transformations are not conserved.
Huitu, Katri; Pandita, P. N.; Tiitola, Paavo
2015-10-01
We examine the deflected mirage mediation supersymmetry breaking (DMMSB) scenario, which combines three supersymmetry breaking scenarios, namely anomaly mediation, gravity mediation and gauge mediation using the one-loop renormalization group invariants (RGIs). We examine the effects on the RGIs at the threshold where the gauge messengers emerge, and derive the supersymmetry breaking parameters in terms of the RGIs. We further discuss whether the supersymmetry breaking mediation mechanism can be determined using a limited set of invariants, and derive sum rules valid for DMMSB below the gauge messenger scale. In addition we examine the implications of the measured Higgs mass for the DMMSB spectrum.
Complete quantum measurements break entanglement
International Nuclear Information System (INIS)
A complete measurement of a quantum observable (POVM) is a measurement of the maximally refined version of the POVM. Complete measurements give information on multiplicities of measurement outcomes and can be used as state preparation procedures. Moreover, any observable can be measured completely. In this Letter, we show that a complete measurement breaks entanglement completely between the system, ancilla and their environment. Finally, consequences for the quantum Zeno effect and complete position measurements are discussed.
16th Edition Breaks New Ground
Institute of Scientific and Technical Information of China (English)
Zhao Fei
2010-01-01
@@ Breaking new ground,Intertextile Shanghai Apparel Fabrics,successfully closed its doors on October 22nd,2010at the Shanghai New International Exhibition Centre,attracting a record breaking,more than 57,000 buyers.
Single Image Super Resolution via Manifold Approximation
Dang, Chinh; Radha, Hayder
2014-01-01
Image super-resolution remains an important research topic to overcome the limitations of physical acquisition systems, and to support the development of high resolution displays. Previous example-based super-resolution approaches mainly focus on analyzing the co-occurrence properties of low resolution and high-resolution patches. Recently, we proposed a novel single image super-resolution approach based on linear manifold approximation of the high-resolution image-patch space [1]. The image ...
Spontaneous Breaking of the Quantum Superposition
Pankovic, Vladan; Predojevic, Milan
2007-01-01
In this work spontaneous (non-dynamical) breaking (effective hiding) of the unitary quantum mechanical dynamical symmetry (superposition) is considered. It represents an especial but very interesting case of the general formalism of the spontaneous symmetry breaking (effective hiding). Conceptual analogies with spontaneous breaking of the gauge symmetry in Weinberg-Sallam's electro-weak interaction are pointed out. Also, consequences of the spontaneous superposition breaking in the measuremen...
Non-minimal scalar multiplets, supersymmetry breaking and dualities
Farakos, Fotis; Kočí, Pavel; von Unge, Rikard
2015-01-01
We study supersymmetry breaking in theories with non-minimal multiplets (such as the complex linear or CNM multiplets), by using superspace higher derivative terms which give rise to new supersymmetry breaking vacuum solutions on top of the standard supersymmetric vacuum. We illustrate the decoupling of the additional massive sectors inside the complex linear and the CNM multiplets and show that only the Goldstino sector is left in the low energy limit. We also discuss the duality between non-minimal scalar multiplets and chiral multiplets in the presence of superspace higher derivatives. From the superspace Noether procedure we calculate the supercurrents, and we show that in the supersymmetry breaking vacuum the chiral superfield X which enters the Ferrara-Zumino supercurrent conservation equation does indeed flow in the IR to the chiral constrained Goldstino superfield. We also provide a universal description of the Goldstino sector in terms of the Samuel-Wess superfield.
Massive photons from Super and Lorentz symmetry breaking
Bonetti, Luca; Helayël-Neto, José A; Spallicci, Alessandro D A M
2016-01-01
In the context of Standard Model Extensions (SMEs), we analyse four general classes of Super Symmetry (SuSy) and Lorentz Symmetry (LoSy) breaking, leading to {observable} imprints at our energy scales. The photon dispersion relations show a non-Maxwellian behaviour for the CPT (Charge-Parity-Time reversal symmetry) odd and even sectors. The group velocities exhibit also a directional dependence with respect to the breaking background vector (odd CPT) or tensor (even CPT). In the former sector, the group velocity may decay following an inverse squared frequency behaviour. Thus, we extract a massive and gauge invariant Carroll-Field-Jackiw photon term in the Lagrangian and show that the mass is proportional to the breaking vector. The latter is estimated by ground measurements and leads to a photon mass upper limit of $10^{-19}$ eV or $2 \\times 10^{-55}$ kg and thereby to a potentially measurable delay at low radio frequencies.
Chiral symmetry breaking in brane models
International Nuclear Information System (INIS)
We discuss the chiral symmetry breaking in general intersecting Dq/Dp brane models consisting of Nc Dq-branes and a single Dp-brane with an s-dimensional intersection. There exists a QCD-like theory localized at the intersection and the Dq/Dp model gives a holographic description of it. The rotational symmetry of directions transverse to both of the Dq and Dp-branes can be identified with a chiral symmetry, which is non-Abelian for certain cases. The asymptotic distance between the Dq-branes and the Dp-brane corresponds to a quark mass. By studying the probe Dp-brane dynamics in a Dq-brane background in the near horizon and large Nc limit we find that the chiral symmetry is spontaneously broken and there appear (pseudo-)Nambu-Goldstone bosons. We also discuss the models at finite temperature
Electroweak symmetry breaking at photon colliders
International Nuclear Information System (INIS)
The electroweak-symmetry-breaking sector of the standard model can be weakly-coupled or can be strongly-coupled, which is characterized by some kinds of strong interaction among the Goldstone bosons of the electroweak-symmetry-breaking sector. In this paper, we summarize an investigation of probing the strong electroweak-symmetry-breaking effects at photon colliders. ((orig.))
Microsphere Super-resolution Imaging
Wang, Zengbo
2015-01-01
Recently, it was discovered that microsphere can generate super-resolution focusing beyond diffraction limit. This has led to the development of an exciting super-resolution imaging technique -microsphere nanoscopy- that features a record resolution of 50 nm under white lights. Different samples have been directly imaged in high resolution and real time without labelling, including both non-biological (nano devices, structures and materials) and biological (subcellular details, viruses) sampl...
International Nuclear Information System (INIS)
A review is given of some 'tuning' methods where the goal is to optimise energy resolution of particle spectra in two-body reactions. With a system consisting of an accelerator, beam analyser, beam transport system and magnetic spectrograph, its potential for high resolution, its limitations and the possibilities of optimising the resolution are investigated. The physics of matching to the spectrograph is considered, adjustments and diagnostics with the spectrograph at 00 are discussed and some on-line tuning methods are examined. (U.K.)
Crosslinks rather than strand breaks determine access to ancient DNA sequences from frozen sediments
DEFF Research Database (Denmark)
Hansen, Anders Johannes; Mitchell, D.L.; Wiuf, C.; Panikert, L.; Brand, Tina Blumensaadt; Binladen, Jonas Khalid Mohamed Awad; Gilichensky, D.A.; Rønn, Regin; Willerslev, Eske
2006-01-01
freely exposed sugar, phosphate, and hydroxyl groups. Intriguingly, interstrand crosslinks were found to accumulate about hundred times faster than single stranded breaks, suggesting that crosslinking rather than depurination is the primary limiting factor for ancient DNA amplification under frozen...
History of electroweak symmetry breaking
Kibble, T W B
2015-01-01
In this talk, I recall the history of the development of the unified electroweak theory, incorporating the symmetry-breaking Higgs mechanism, as I saw it from my standpoint as a member of Abdus Salam's group at Imperial College. I start by describing the state of physics in the years after the Second World War, explain how the goal of a unified gauge theory of weak and electromagnetic interactions emerged, the obstacles encountered, in particular the Goldstone theorem, and how they were overcome, followed by a brief account of more recent history, culminating in the historic discovery of the Higgs boson in 2012.
Leaders break ground for INFINITY
2008-01-01
Community leaders from Mississippi and Louisiana break ground for the new INFINITY at NASA Stennis Space Center facility during a Nov. 20 ceremony. Groundbreaking participants included (l to r): Gottfried Construction representative John Smith, Mississippi Highway Commissioner Wayne Brown, INFINITY board member and Apollo 13 astronaut Fred Haise, Stennis Director Gene Goldman, Studio South representative David Hardy, Leo Seal Jr. family representative Virginia Wagner, Hancock Bank President George Schloegel, Mississippi Rep. J.P. Compretta, Mississippi Band of Choctaw Indians representative Charlie Benn and Louisiana Sen. A.G. Crowe.
History of electroweak symmetry breaking
Kibble, T. W. B.
2015-07-01
In this talk, I recall the history of the development of the unified electroweak theory, incorporating the symmetry-breaking Higgs mechanism, as I saw it from my standpoint as a member of Abdus Salam's group at Imperial College. I start by describing the state of physics in the years after the Second World War, explain how the goal of a unified gauge theory of weak and electromagnetic interactions emerged, the obstacles encountered, in particular the Goldstone theorem, and how they were overcome, followed by a brief account of more recent history, culminating in the historic discovery of the Higgs boson in 2012.
Supersymmetry breaking in string theory
International Nuclear Information System (INIS)
I briefly review the problems with previous investigations of supersymmetry breaking in string theory --- at tree-level, at one-loop, and non-perturbatively. A variant of the original non-perturbative scenario is proposed, in which gaugino condensation takes place in two different strongly-interacting hidden-sector gauge groups. In the new scenario it is possible to generate a large hierarchy of mass scale and to simultaneously stabilize the dilaton at a large expectation value (weak coupling). However, it is still uncertain whether supersymmetry is broken in such a vacuum. 26 refs
Spontaneous Breaking of Flavor Symmetry
Törnqvist, N A
1996-01-01
It is shown that part of the quark masses of the standard model can be generated spontaneously within the strong interactions of QCD. After the breaking of U(Nf) x U(Nf) symmetry by the vacuum, also the resulting flavor symmetric, degenerate meson mass spectrum is shown to be unstable with respect to quantum loops, for rather general models. For a C-degenerate meson spectrum the stable mass spectrum obeys the Okubo-Zweig-Iizuka rule and the approximateequal spacing rule.
DEFF Research Database (Denmark)
Driscoll, Patrick Arthur
2014-01-01
This central focus of this paper is to highlight the ways in which path dependencies and increasing returns (network effects) serve to reinforce carbon lock-in in large-scale road transportation infrastructure projects. Breaking carbon lock-in requires drastic changes in the way we plan future...... transportation infrastructure projects, and documentary evidence presented here from the metropolitan regions of Copenhagen, Denmark and Portland, USA suggest that there may be a discontinuity in the system of automobility (Urry, 2004) thereby increasing the likelihood that such drastic measures may in fact be...
Progress in Electroweak Symmetry Breaking
Dawson, S
2015-01-01
In this talk, I discuss theoretical advances in understanding the properties of the Higgs boson and the implications for models of electroweak symmetry breaking. I begin by reviewing some of the recent progress in Standard Model calculations for Higgs boson production and decay rates, followed by a lightning tour of the use of effective field theories in the search for new physics in the Higgs sector. I end with a discussion of the complementarity of precision Higgs coupling measurements and direct searches for heavy particles for the discovery of Beyond the Standard Model physics in the electroweak sector.
Chiu, Ming-Hung; Lai, Chin-Fa; Tan, Chen-Tai; Lin, Yi-Zhi
2011-03-01
This paper presents a study of the lateral and axial resolutions of a transmission laser-scanning angle-deviation microscope (TADM) with different numerical aperture (NA) values. The TADM is based on geometric optics and surface plasmon resonance principles. The surface height is proportional to the phase difference between two marginal rays of the test beam, which is passed through the test medium. We used common-path heterodyne interferometry to measure the phase difference in real time, and used a personal computer to calculate and plot the surface profile. The experimental results showed that the best lateral and axial resolutions for NA = 0.41 were 0.5 μm and 3 nm, respectively, and the lateral resolution breaks through the diffraction limits.
Boundary breaking for interdisciplinary learning
Directory of Open Access Journals (Sweden)
Adi Kidron
2015-10-01
Full Text Available The purpose of this work is to contribute to the body of knowledge on processesby which students develop interdisciplinary understanding of contents, as well as to suggest technology-enhanced means for supporting them in these processes in the context of higher education. In doing so, we suggest a rethinking of three traditional practices that tend to characterise typical higher education instruction: (1 compartmentalisation of disciplines; (2 traditional pedagogy; and (3 traditional hierarchies based on levels of expertise. Our high-level conjecture was that meaningful dialogue with peers and experts supports both the deepening of ideas in one knowledge domain and the formation of connections between ideas from several domains, both of which are required for the development of interdisciplinary understanding. We developed the Boundary Breaking for Interdisciplinary Learning (BBIL model, which harnesses technology to break boundaries between disciplines, learners and organisational levels of hierarchy. Findings indicate that 36 undergraduate students who participated in an interdisciplinary online course that implemented the BBIL model have significantly improved their interdisciplinary understanding of the course contents. This study illustrates how innovative use of available, free and low-cost technology can produce a ‘positive disruption’ in higher education instruction.
Introduction to Electroweak Symmetry Breaking
Energy Technology Data Exchange (ETDEWEB)
Dawson,S.
2008-10-02
The Standard Model (SM) is the backbone of elementary particle physics-not only does it provide a consistent framework for studying the interactions of quark and leptons, but it also gives predictions which have been extensively tested experimentally. In these notes, I review the electroweak sector of the Standard Model, discuss the calculation of electroweak radiative corrections to observables, and summarize the status of SM Higgs boson searches. Despite the impressive experimental successes, however, the electroweak theory is not completely satisfactory and the mechanism of electroweak symmetry breaking is untested. I will discuss the logic behind the oft-repeated statement: 'There must be new physics at the TeV scale'. These lectures reflect my strongly held belief that upcoming results from the LHC will fundamentally change our understanding of electroweak symmetry breaking. In these lectures, I review the status of the electroweak sector of the Standard Model, with an emphasis on the importance of radiative corrections and searches for the Standard Model Higgs boson. A discussion of the special role of the TeV energy scale in electroweak physics is included.
Chiral symmetry breaking and monopoles
Di Giacomo, Adriano; Pucci, Fabrizio
2015-01-01
To understand the relation between the chiral symmetry breaking and monopoles, the chiral condensate which is the order parameter of the chiral symmetry breaking is calculated in the $\\overline{\\mbox{MS}}$ scheme at 2 [GeV]. First, we add one pair of monopoles, varying the monopole charges $m_{c}$ from zero to four, to SU(3) quenched configurations by a monopole creation operator. The low-lying eigenvalues of the Overlap Dirac operator are computed from the gauge links of the normal configurations and the configurations with additional monopoles. Next, we compare the distributions of the nearest-neighbor spacing of the low-lying eigenvalues with the prediction of the random matrix theory. The low-lying eigenvalues not depending on the scale parameter $\\Sigma$ are compared to the prediction of the random matrix theory. The results show the consistency with the random matrix theory. Thus, the additional monopoles do not affect the low-lying eigenvalues. Moreover, we discover that the additional monopoles increa...
Semilocal string with Lorentz-breaking term
International Nuclear Information System (INIS)
shown that the presence of the Lorentz symmetry violating term may lead to a peculiar effect in the vortex size. Hence,in view of the aforementioned characteristic of the semi local vortex, the solution combining both effects may result in a most malleable defect structure, which is shown to be the case. Besides, we show that the Bradlows limit depends on the magnitude of a parameter related to the Lorentz-breaking term, i. e., the vorticity is also affected. In fact, the vorticity increases as the Lorentz violating term becomes more relevant. (author)
An X-Ray Tomographic Microscope with Submicron Resolution
International Nuclear Information System (INIS)
X-ray tomographic microscopy (XTM) is a powerful non-destructive investigation method, that has been applied in many fields of modern research (material science, micro electronics, medicine, biology , archaeology). So far the major limitations were imposed by low detection efficiency and low spatial resolution. With the advent of third generation synchrotron facilities excellent high intensity X-ray sources became available that by far counterbalanced low efficiency. On the other hand the resolution of presently used detector systems is restricted by scintillator properties, optical light transfer, and CCD granularity. They impose a practical limit of about one micrometer, while the progressing research demands urgently an advance in the submicron region. A break-through in this respect is being achieved by a novel detector type. It uses the properties of asymmetric Bragg reflection to increase the cross section of the reflected X-ray beam. A suitable combination of correspondingly cut Bragg crystals yields an image magnification that even at higher energies may surpass a factor of 1000. In this way the influence of the detector resolution can be scaled down accordingly. Such a device is being constructed and installed at the SLS which delivers an optimal X-ray beam of about 23 keV. The special properties of this experiment will be presented. (author)
Research on thermal hydraulic behavior of small-break LOCAs in AP1000
International Nuclear Information System (INIS)
Highlights: • A RELAP5 model for RCS and passive safety systems in AP1000 was developed. • A spectrum of cold leg small break LOCAs was analyzed. • The PCTs are far below the limit value of 1478 K and meet the safety criterion. • This article is useful for design and operation of AP1000 and other plants. -- Abstract: As a Generation III+ reactor that received Final Design Approval by U.S. NRC, AP1000 employs a series of nature forces, such as gravity, natural circulation and compressed gas, to enhance plant safety. Although plenty of work has been done around AP600 and its updated version AP1000 both experimentally and theoretically in the past few decades, thermal hydraulic behavior of small break LOCAs in AP1000 has not been fully understood and further studies are still required. In the present study, the response of AP1000 to a spectrum of cold leg small break LOCAs is simulated and analyzed using RELAP5/MOD3.4, including 2-in. break, 4-in. break, 8-in. break as well as 10-in. break which approaches the upper limit size for small break LOCAs in AP1000. Based on the calculation results, it indicates that the passive safety systems employed by AP1000, including CMTs, ACCs, IRWST, PRHRS and ADS, combine to provide continuous passive safety injection and residual heat removal. During cold leg small break LOCAs, the core uncovery and fuel heat up do not occur. The peak cladding temperatures (PCTs) during the accident process are far below the Appendix K limit value of 1478 K/2200 °F and meet the safety criterion. Results show that the accidental consequence can be mitigated effectively and thus the safety of AP1000 during cold leg small break LOCAs is proven
Experimental demonstration of decoherence-induced spontaneous symmetry breaking
International Nuclear Information System (INIS)
We experimentally investigate the variations of exchange-symmetry properties of the four Bell states in an exchange-symmetric pure dephasing process with a two-photon system generated from spontaneous parametric down-conversion (SPDC). Experiment results show that under such an exchange-symmetric local-noise Hamiltonian, the exchange-symmetry property remains unchanged for two of the three symmetric Bell states, i.e., the states |Φ>±=(1/√(2))(|00>±|11>). For the antisymmetric Bell state |Ψ>-=(1/√(2))(|01>-|10>), the exchange-symmetry property increases and achieves a maximum value of 0.5 at the asymptotic limit. However, for the third exchange-symmetric Bell state |Ψ>+=(1/√(2))(|01>+|10>), the exchange-symmetry property breaks, surviving with a probability of 0.5 at the asymptotic limit, which provides some evidence supporting such decoherence-induced spontaneous-symmetry-breaking phenomena.
Chiral symmetry breaking in QCD Lite
Engel, Georg P; Lottini, Stefano; Sommer, Rainer
2014-01-01
A distinctive feature of the presence of spontaneous chiral symmetry breaking in QCD is the condensation of low modes of the Dirac operator near the origin. The rate of condensation must be equal to the slope of (Mpi^2 Fpi^2)/2 with respect to the quark mass m in the chiral limit, where Mpi and Fpi are the mass and the decay constant of the Nambu-Goldstone bosons. We compute the spectral density of the (Hermitian) Dirac operator, the quark mass, the pseudoscalar meson mass and decay constant by numerical simulations of lattice QCD with two light degenerate Wilson quarks. We use CLS lattices at three values of the lattice spacing in the range 0.05-0.08 fm, and for several quark masses corresponding to pseudoscalar mesons masses down to 190 MeV. Thanks to this coverage of parameters space, we can extrapolate all quantities to the chiral and continuum limits with confidence. The results show that the low quark modes do condense in the continuum as expected by the Banks-Casher mechanism, and the rate of condensat...
Cosmological Gravitino Production in Gauge Mediated Supersymmetry Breaking Models
Choi, Kiwoon; Hwang, Kyuwan; Kim, Hang Bae; Lee, Taekoon
1999-01-01
We study the cosmological gravitino production in gauge mediated supersymmetry breaking models, while properly taking into account the existence of the messenger mass scale. It is found that for sizable parameter range of the model the messenger sector contribution leads to more stringent upper bound on the reheat temperature obtained from the condition that the universe should not be overclosed by relic gravitinos. However it turns out that in the limit of relatively low messenger scale and ...
The leak before break criteria, requirements and implications
International Nuclear Information System (INIS)
Inside this work a general balance is made on the Leak before break approach (LBB), like they are the history and licensing, those limitations, the acceptance criteria of the LBB, the current state of the regulatory development and the current state of it application in countries like E.U.A, Germany, Canada, Italy and France. Everything it with the purpose of evaluating the opportunities that offers the LBB criteria for it possible application in Mexico. (Author)
Analogue symmetry breaking in superallowed Fermi β-decay
International Nuclear Information System (INIS)
The change in the Fermi matrix element due to deviations from perfect analogue symmetry has been estimated in a single-particle model with both harmonic oscillator and Saxon-Woods radial wave functions. A limitation of earlier calculations, in which the ground state of the A-1 nucleus was taken as the unique parent, is removed to allow the whole spectrum of parent states to be operative. This improvement leads to slightly larger analogue symmetry breaking effects. (Auth.)
Influence of light-quark masses in dynamical scale breaking
International Nuclear Information System (INIS)
It is demonstrated that light quark masses may significantly contribute to the logarithmic scale breaking in deep inelastic electromagnetic lepton-nucleon scattering. This is mainly due to the combination of scale variables together with large 'current' masses for u and d quarks, recently reported in the literature. Upper limits for current masses of u and d quarks, using positivity properties of the forward electromagnetic structure function F2 of the nucleon are also estimated. (Author)
Continuum strong QCD: Confinement and dynamical chiral symmetry breaking
International Nuclear Information System (INIS)
Continuum strong QCD is the application of models and continuum quantum field theory to the study of phenomena in hadronic physics, which includes; e.g., the spectrum of QCD bound states and their interactions. Herein the author provides a Dyson-Schwinger equation perspective, focusing on qualitative aspects of confinement and dynamical chiral symmetry breaking in cold, sparse QCD, and also elucidating consequences of the axial-vector Ward-Takahashi identity and features of the heavy-quark limit
Electroweak Symmetry Breaking by QCD
Kubo, Jisuke; Lindner, Manfred
2014-01-01
We propose a new mechanism to generate the electroweak scale within the framework of QCD, which is extended to include conformally invariant scalar degrees of freedom belonging to a larger irreducible representation of $SU(3)_c$. The electroweak symmetry breaking is triggered dynamically via the Higgs portal by the condensation of the colored scalar field around $1$ TeV. The mass of the colored boson is restricted to be $350$ GeV $\\lesssim m_S\\lesssim 3$ TeV, with the upper bound obtained from renormalization group evolution. This implies that the colored boson can be produced at LHC. If the colored boson is electrically charged, the branching fraction of the Higgs decaying into two photons can slightly increase, and moreover, it can be produced at future linear colliders.
Z'-mediated supersymmetry breaking.
Langacker, Paul; Paz, Gil; Wang, Lian-Tao; Yavin, Itay
2008-02-01
We consider a class of models in which supersymmetry breaking is communicated dominantly via a U1' gauge interaction, which also helps solve the mu problem. Such models can emerge naturally in top-down constructions and are a version of split supersymmetry. The spectrum contains heavy sfermions, Higgsinos, exotics, and Z' approximately 10-100 TeV, light gauginos approximately 100-1000 GeV, a light Higgs boson approximately 140 GeV, and a light singlino. A specific set of U1' charges and exotics is analyzed, and we present five benchmark models. The implications for the gluino lifetime, cold dark matter, and the gravitino and neutrino masses are discussed. PMID:18352261
Dynamical centrosymmetry breaking in graphene
Carvalho, David N; Biancalana, Fabio
2016-01-01
We discover an unusual phenomenon that occurs when a graphene monolayer is illuminated by a short and intense pulse at normal incidence. Due to the pulse-induced oscillations of the Dirac cones, a dynamical breaking of the layer's centrosymmetry takes place, leading to the generation of second harmonic waves. We prove that this result can only be found by using the full Dirac equation and show that the widely used semiconductor Bloch equations fail to reproduce this and some other important physics of graphene. Our results open new windows in the understanding of nonlinear light-matter interactions in a wide variety of new 2D materials with a gapped or ungapped Dirac-like dispersion.
Egeland, B; Jacobvitz, D; Sroufe, L A
1988-08-01
The aim of this study was to identify variables that distinguish mothers who broke the cycle of abuse from mothers who were abused as children and who also abused their own children. Based on maternal interviews and questionnaires completed over a 64-month period, measures of mothers' past and current relationship experiences, stressful life events, and personality characteristics were obtained. Abused mothers who were able to break the abusive cycle were significantly more likely to have received emotional support from a nonabusive adult during childhood, participated in therapy during any period of their lives, and to have had a nonabusive and more stable, emotionally supportive, and satisfying relationship with a mate. Abused mothers who reenacted their maltreatment with their own children experienced significantly more life stress and were more anxious, dependent, immature, and depressed. PMID:3168615
Institute of Scientific and Technical Information of China (English)
李明
2014-01-01
Three physicists, Eric Betzig, Stefan Hell and William E. Moerner were award-ed the Nobel Prize in Chemistry 2014 for developing super-resolution optical microscopy. They pushed the techniques of their time to extremes to image single molecules, discovered the on/off switching behaviors of fluorescent molecules, and applied the well-known stimulated emission phe-nomenon to bypass a presumed scientific limitation stipulating that an optical microscope can nev-er yield a resolution better than 200 nm. The new techniques will lead to a revolution in life sci-ence. Using them, scientists can now monitor the interplay between individual molecules inside cells and track cell division at the nano-level, to name but a few.%三个物理学家，因为对生命科学的贡献，赢得2014年的诺贝尔化学奖。他们做了什么重大贡献？恩斯特·阿贝为常规光学显微镜的分辨率设定了一个限制——半波长极限。贝齐格、赫尔和莫纳将已知的技术推至极限，最早探测到凝聚态体系中的单个荧光分子，利用荧光分子的开关效应，加上物理教科书上的受激辐射原理和数据分析中常用的拟合定位方法，绕开了这个似乎不能突破的极限。他们将光学显微技术带入到纳米尺度，引发了常温下活体生物学研究的又一场革命。他们对科学的追求堪称至极至美。这样的典范将来还会有，尤其是在物理学与生命科学的交叉领域。
Mutual information and spontaneous symmetry breaking
Hamma, A.; Giampaolo, S. M.; Illuminati, F.
2015-01-01
We show that the metastable, symmetry-breaking ground states of quantum many-body Hamiltonians have vanishing quantum mutual information between macroscopically separated regions, and are thus the most classical ones among all possible quantum ground states. This statement is obvious only when the symmetry-breaking ground states are simple product states, e.g. at the factorization point. On the other hand, symmetry-breaking states are in general entangled along the entire ordered phase, and t...
CFD analysis of Siphon Break in a Research Reactor
Energy Technology Data Exchange (ETDEWEB)
Park, Hong Beom; Seo, Kyoungwoo; Kim, Seong Hoon; Chi, Dae Young [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2014-05-15
The results employing the homogenous model and inhomogeneous model with the SST turbulence model were compared. Homogeneous model has higher undershooting height than inhomogeneous model. And results with various free surface option show siphon break phenomena is not associated with free surface. Based on a numerical simulation, it was evaluated that a siphon break is dependent on the air-water flow mixture and interface length scale. In open pool type research reactor, reactor core is cooled by natural circulation after the primary cooling pump is turned off and the pool water is used as the ultimate heat sink. The pool water also behaves as a shielding barrier for many kinds of radio-nuclides from the reactor core and the spent fuel. Pool water is essential for nuclear safety. So guaranteeing the pool water inventory to be higher than the required minimum level is one of the most important tasks of a research reactor design. The lowest pool penetration of cooling pipes should be located above the reactor core against a cooling pipe break. However, system components outside the pool can be installed below the core level due to the component purpose such as the acceptance of a Net Positive Suction Head(NPSH) of a pump for downward core flow research reactor. So the pool water can be drained below the core through siphon effect and the core can't be cooled through natural circulation when a postulated pipe break occurs below the reactor core position. Therefore siphon breaker should be installed to limit the pool water drain. In this study, 3D numerical simulations are performed to be applicable to the siphon breaker design for a research reactor because undershooting(height between the end of siphon break line and the final pool water level) is expected for a large pipe break. ANSYS CFD is used to solve the Navier-Stokes equation with the turbulent model and two-phase model. Siphon breaker was designed to satisfy the minimum pool water level requirement during
Gravity with background fields and diffeomorphism breaking
Bluhm, Robert
2016-01-01
Effective gravitational field theories with background fields break local Lorentz symmetry and diffeomorphism invariance. Examples include Chern-Simons gravity, massive gravity, and the Standard-Model Extension (SME). The physical properties and behavior of these theories depend greatly on whether the spacetime symmetry breaking is explicit or spontaneous. With explicit breaking, the background fields are fixed and nondynamical, and the resulting theories are fundamentally different from Einstein's General Relativity (GR). However, when the symmetry breaking is spontaneous, the background fields are dynamical in origin, and many of the usual features of Einstein's GR still apply.
Time amplifying techniques towards atomic time resolution
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
High speed imaging technology has opened applications in many fields,such as collision,detonating, high voltage discharge,disintegration and transfer of phonon and exciton in solid,photosynthesis primitive reaction,and electron dynamics inside atom shell.In principle,all of the transient processes need to be explained theoretically and,at the same time,the time amplifying technique is required for observations of these processes.The present review concerns the atomic time amplifying mechanism of optical information and the extremely-high speed imaging methods,which are expressed in terms of the short time amplifying techniques.It is well-known that for extremely-high speed imaging with the converter tube,the temporal resolution is in the order of sub-picosecond of the streak imaging,and the imaging frequency is 6×10 8 ―5×10 9 fps(frame per second)of the frame imaging.On the other hand,for the tubeless extremely-high speed imaging,the imaging frequency is 10 7 ―10 14 fps,and its mechanism of forming high speed and framing could involve a lot of factors of the light under investigation,for instance,light speed,light parallelism,the parameters of light wave such as amplitude,phase,polari- zation and wavelength,and even quantum properties of photon.In the cascaded system of electro- magnetic wave and particle wave,it is possible to simultaneously realize extremely-high resolution in time and space,which is higher than a kite resolution.Then it would be possible to break the limit of the Heisenberg uncertainty relation of the optical frequency band.
Time amplifying techniques towards atomic time resolution
Institute of Scientific and Technical Information of China (English)
LI JingZhen
2009-01-01
High speed imaging technology has opened applications in many fields,such as collision,detonating,high voltage discharge,disintegration and transfer of phonon and exciton in solid,photosynthesis primitive reaction,and electron dynamics inside atom shell.In principle,all of the transient processes need to be explained theoretically and,st the same time,the time amplifying technique is required for observations of these processes.The present review concerns the atomic time amplifying mechanism of optical information and the extremely-high speed imaging methods,which are expressed in terms of the short time amplifying techniques.It is well-known that for extremely-high speed imaging with the converter tube,the temporal resolution is in the order of sub-picosecond of the streak imaging,and the imaging frequency is 6×10~8-5×10~9 fps(frame per second)of the frame imaging.On the other hand,for the tubeless extremely-high speed imaging,the imaging frequency is 10~7-10~(14) fps,and its mechanism of forming high speed and framing could involve a lot of factors of the light under investigation,for instance,light speed,light parallelism,the parameters of light wave such as amplitude,phase,polarization and wavelength,and even quantum properties of photon.In the cascaded system of electromagnetic wave and particle wave,it is possible to simultaneously realize extremely-high resolution in time and space,which is higher than a kite resolution.Then it would be possible to break the limit of the Heisenberg uncertainty relation of the optical frequency band.
Lorentz Symmetry Breaking and its consequences on Thermodynamics
International Nuclear Information System (INIS)
Full text: In this work, we study the effects of Lorentz Symmetry Breaking on thermodynamics properties of ideal gases. We start from a dispersion relation obtained from the Carroll-Field-Jackiw model to Electrodynamics with Lorentz and CPT violation term. With this, we compute the thermodynamics quantities for a Boltzmann, Bose-Einstein and Fermi-Dirac distributions. Two regimes are analyzed: the non-relativistic and the relativistic one. In the first case we show that the topological mass induced by the Chern-Simons term behaves as a chemical potential. For the Bose-Einstein condensates with these Lorentz breaking, the critical values as particle number, and temperature, are modified. These results are the same that were obtained by Colladay et al, whose perform the non-relativistic limit directly in the Hamiltonian for a Lorentz symmetry violating theory and used this to study the Bose-Einstein condensate to obtain a bound for the background field which perform the breaking. The original contribution of these work is in the relativistic regime, where we show that a new phase transition for a Bose -Einstein gas, can be induced by the Lorentz Symmetry Breaking parameters. Some applications in cosmology and astrophysics are commented. (author)
Lorentz Symmetry Breaking and its consequences on Thermodynamics
Energy Technology Data Exchange (ETDEWEB)
Costa-Soares, T.; Sales, J.A. de; Otoya, V.J. Vasques [Instituto Federal de Educacao, Ciencia e Tecnologia do Sudeste de Minas Gerais (IF Sudeste MG), MG (Brazil)
2011-07-01
Full text: In this work, we study the effects of Lorentz Symmetry Breaking on thermodynamics properties of ideal gases. We start from a dispersion relation obtained from the Carroll-Field-Jackiw model to Electrodynamics with Lorentz and CPT violation term. With this, we compute the thermodynamics quantities for a Boltzmann, Bose-Einstein and Fermi-Dirac distributions. Two regimes are analyzed: the non-relativistic and the relativistic one. In the first case we show that the topological mass induced by the Chern-Simons term behaves as a chemical potential. For the Bose-Einstein condensates with these Lorentz breaking, the critical values as particle number, and temperature, are modified. These results are the same that were obtained by Colladay et al, whose perform the non-relativistic limit directly in the Hamiltonian for a Lorentz symmetry violating theory and used this to study the Bose-Einstein condensate to obtain a bound for the background field which perform the breaking. The original contribution of these work is in the relativistic regime, where we show that a new phase transition for a Bose -Einstein gas, can be induced by the Lorentz Symmetry Breaking parameters. Some applications in cosmology and astrophysics are commented. (author)
Resolution propositions; Proposition de resolution
Energy Technology Data Exchange (ETDEWEB)
NONE
2003-05-01
To put a resolution to the meeting in relation with the use of weapons made of depleted uranium is the purpose of this text. The situation of the use of depleted uranium by France during the Gulf war and other recent conflicts will be established. This resolution will give the most strict recommendations face to the eventual sanitary and environmental risks in the use of these kind of weapons. (N.C.)
Temporal variations in river-ice break-up over the Mackenzie River Basin, Canada
de Rham, Laurent P.; Prowse, Terry D.; Bonsal, Barrie R.
2008-02-01
SummaryFor northern and arctic regions, the spring break-up period has important socio-economic, ecological and morphological effects. While these impacts are reasonably well understood, spatial and temporal assessments of break-up timing and duration remain limited due to the lack of readily available hydrometric data. For this study, the Mackenzie River Basin (MRB) of Canada is selected as a test watershed in which the spatial and temporal aspects of observed (1913-2002) spring river-ice break-up are characterized. Data from 29 Water Survey of Canada gauging sites are used including the commonly assessed 'Last B date' (last ice effect) and two hydrometric variables extracted directly from original water-level recording charts (the timing of initiation of break-up and peak water-level during break-up). It is found that the extracted variables provide a more physically based quantitative description of the break-up season in the MRB compared to the 'Last B date' method. On average, the northwards progressing ice break-up season within the MRB lasts ∼8 weeks but historically has varied within a window representative of ∼3 months of the year. The break-up period at specific locations varies from 4 days to 4 weeks. Results also indicate an anomalous zone of earlier spring break-up in the upper Peace and Athabasca region that may be partially related to the effects of flow regulation. In addition, the Mann-Kendall test reveals significantly earlier trends in the timing of spring break-up (∼1 day/decade) in upstream portions of the major tributaries of the MRB over the period 1970-2002. While similar trends have been found for other hydroclimatic variables in the basin, this study highlights the temporal patterns and variability of the spring break-up period in the Mackenzie River system.
On breaks of the Indian monsoon
Indian Academy of Sciences (India)
Sulochana Gadgil; P V Joseph
2003-12-01
For over a century, the term break has been used for spells in which the rainfall over the Indian monsoon zone is interrupted. The phenomenon of `break monsoon' is of great interest because long intense breaks are often associated with poor monsoon seasons. Such breaks have distinct circulation characteristics (heat trough type circulation) and have a large impact on rainfed agriculture.Although interruption of the monsoon rainfall is considered to be the most important feature of the break monsoon, traditionally breaks have been identified on the basis of the surface pressure and wind patterns over the Indian region. We have defined breaks (and active spells) on the basis of rainfall over the monsoon zone. The rainfall criteria are chosen so as to ensure a large overlap with the traditional breaks documented by Ramamurthy (1969) and De et al (1998). We have identified these rainbreaks for 1901-89. We have also identified active spells on the basis of rainfall over the Indian monsoon zone. We have shown that the all-India summer monsoon rainfall is significantly negatively correlated with the number of rainbreak days (correlation coefficient −0.56) and significantly positively correlated with the number of active days (correlation coefficient 0.47).Thus the interannual variation of the all-India summer monsoon rainfall is shown to be related to the number of days of rainbreaks and active spells identified here. There have been several studies of breaks (and also active spells in several cases) identified on the basis of different criteria over regions differing in spatial scales (e.g., Webster et al 1998; Krishnan et al 2000; Goswami and Mohan 2000; and Annamalai and Slingo 2001). We find that there is considerable overlap between the rainbreaks we have identified and breaks based on the traditional definition. There is some overlap with the breaks identified by Krishnan et al (2000) but little overlap with breaks identified by Webster et al (1998). Further
Simulation of strand break induction by DNA incorporated 125I
International Nuclear Information System (INIS)
Monte Carlo calculation of 125I Auger cascades has provided electron spectra for individual decays with kinetic energies determined by Dirac-Fock methods. For these Auger electrons, track structures in liquid water have been generated and superimposed on a straight DNA plasmid model with atomic coordinates taken from X ray diffraction studies. Due to its high geometrical resolution, this DNA model makes it possible to localize the energy deposition or/and radical production events relative to the submolecular units of the DNA strands (base, sugar, phosphate). Furthermore, it is possible to distinguish between events inside (direct) and outside (indirect, radical production) of the atomic volumes of the DNA. On the basis of different assumptions for the effectiveness of strand break induction by direct hits and by OH· and H· radicals, the yields for single- and double strand breaks, as well as the strand break distribution as a function of the distance from the decay site, has been evaluated and compared with experimental and theoretical results from the literature
Simulation of breaking gravity waves during the south foehn of 7 - 13 January 1996
Energy Technology Data Exchange (ETDEWEB)
Schmid, H.; Doernbrack, A.
1998-07-01
A high-resolution mesoscale model with horizontal mesh size of 6 km is applied to simulate upper-level wave breaking above the Alps during a south foehn event in January 1996. The model reproduces the key synoptic and mesoscale features of cross-alpine airflow during foehn. High-resolution radiosonde ascents at Munich and Innsbruck are used to evaluate the quality of the model simulations. The simulations predict breaking gravity waves above the jet stream in a layer between 10 and 15 km altitude where the shear is maximum. In part of the foehn period a critical level is present at about 200 hPa that results in wave steepening below and no wave activity aloft. Regions where aircraft report clear-air turbulence encounters agree reasonably with the simulated locations of gravity wave breaking. (orig.)
Detecting Structural Breaks using Hidden Markov Models
DEFF Research Database (Denmark)
Ntantamis, Christos
Testing for structural breaks and identifying their location is essential for econometric modeling. In this paper, a Hidden Markov Model (HMM) approach is used in order to perform these tasks. Breaks are defined as the data points where the underlying Markov Chain switches from one state to another...
Electroweak Symmetry Breaking and the Higgs Boson
Pich, Antonio
2015-01-01
The first LHC run has confirmed the Standard Model as the correct theory at the electroweak scale, and the existence of a Higgs-like particle associated with the spontaneous breaking of the electroweak gauge symmetry. These lectures overview the present knowledge on the Higgs boson and discuss alternative scenarios of electroweak symmetry breaking which are already being constrained by the experimental data.
Multiscale Simulation of Breaking Wave Impacts
DEFF Research Database (Denmark)
Lindberg, Ole
compare reasonably well. The incompressible and inviscid ALE-WLS model is coupled with the potential flow model of Engsig-Karup et al. [2009], to perform multiscale calculation of breaking wave impacts on a vertical breakwater. The potential flow model provides accurate calculation of the wave...... potential flow model to provide multiscale calculation of forces from breaking wave impacts on structures....
DNA Replication Reaches the Breaking Point
Petrini, John H.J.
2009-01-01
DNA strand breaks that result in stalled or damaged replication forks can be detrimental to the DNA replication process. In this issue, Doksani et al. (2009) examine the impact of a single double-stranded DNA break on replication in the budding yeast, Saccharomyces cerevisiae.
Four Top Production and Electroweak Symmetry Breaking
Cheung, Kingman
1995-01-01
With the recent discovery of a heavy top quark $(m_t \\approx 175 - 200$ GeV), the top quark opens an window to electroweak symmetry breaking. We propose the study of four-top, $t\\bar t t\\bar t$, production at hadronic supercolliders as a probe to electroweak symmetry breaking.
Anatomy of String Breaking in QCD
Prkacin, Zdravko; Bali, Gunnar S.; Dussel, Thomas; Lippert, Thomas; Neff, Hartmut; Schilling, Klaus
2005-01-01
We investigate the string breaking mechanism in n_f=2 QCD. We discuss the lattice techniques used and present results on energy levels and mixing angle of the static BBbar|QbarQ two-state system. The string breaking is visualized, by means of an animation of the action density distribution as a function of the static colour source-antisource separation.
Miller, G A
2003-01-01
Two new experiments have detected charge-symmetry breaking, the mechanism responsible for protons and neutrons having different masses. Symmetry is a crucial concept in the theories that describe the subatomic world because it has an intimate connection with the laws of conservation. The theory of the strong interaction between quarks - quantum chromodynamics - is approximately invariant under what is called charge symmetry. In other words, if we swap an up quark for a down quark, then the strong interaction will look almost the same. This symmetry is related to the concept of sup i sospin sup , and is not the same as charge conjugation (in which a particle is replaced by its antiparticle). Charge symmetry is broken by the competition between two different effects. The first is the small difference in mass between up and down quarks, which is about 200 times less than the mass of the proton. The second is their different electric charges. The up quark has a charge of +2/3 in units of the proton charge, while ...
Research progress on dam-break floods
Wu, Jiansong
2011-08-01
Because of the catastrophic effects downstream of dam-break failure, more and more researchers around the world have been working on the study of dam-break flows to accurately forecast the downstream inundation mapping. With the rapid development of computer hardware and computing techniques, numerical study on dam-break flows has been a popular research subject. In the paper, the numerical methodologies used to solve the governing partial differential equations of dam-break flows are classified and summarized, and their characteristics and applications are discussed respectively. Furthermore, the fully-developed mathematical models developed in recent decades are reviewed, and also introduced the authors\\' on-going work. Finally, some possible future developments on modeling the dam-break flows and some solutions are presented and discussed. © 2011 IEEE.
Supersymmetry Breaking by Higher Dimension Operators
Farakos, Fotis; Kehagias, Alex; Porrati, Massimo
2014-01-01
We discuss a supersymmetry breaking mechanism for N = 1 theories triggered by higher dimensional op- erators. We consider such operators for real linear and chiral spinor superfields that break superymmetry and reduce to the Volkov-Akulov action. We also consider supersymmetry breaking induced by a higher dimensional operator of a nonminimal scalar (complex linear) multiplet. The latter differs from the stan- dard chiral multiplet in its auxiliary sector, which contains, in addition to the complex scalar auxiliary of a chiral superfield, a complex vector and two spinors auxiliaries. By adding an appropriate higher di- mension operator, the scalar auxiliary may acquire a nonzero vev triggering spontaneous supersymmetry breaking. We find that the spectrum of the theory in the supersymmetry breaking vacuum consists of a free chiral multiplet and a constraint chiral superfield describing the goldstino. Interestingly, the latter turns out to be one of the auxiliary fermions, which becomes dynamical in the supersym...
Chiral symmetry and chiral-symmetry breaking
International Nuclear Information System (INIS)
These lectures concern the dynamics of fermions in strong interaction with gauge fields. Systems of fermions coupled by gauge forces have a very rich structure of global symmetries, which are called chiral symmetries. These lectures will focus on the realization of chiral symmetries and the causes and consequences of thier spontaneous breaking. A brief introduction to the basic formalism and concepts of chiral symmetry breaking is given, then some explicit calculations of chiral symmetry breaking in gauge theories are given, treating first parity-invariant and then chiral models. These calculations are meant to be illustrative rather than accurate; they make use of unjustified mathematical approximations which serve to make the physics more clear. Some formal constraints on chiral symmetry breaking are discussed which illuminate and extend the results of our more explicit analysis. Finally, a brief review of the phenomenological theory of chiral symmetry breaking is presented, and some applications of this theory to problems in weak-interaction physics are discussed
Mixing-induced spontaneous supersymmetry breaking
International Nuclear Information System (INIS)
It is conjectured that flavor mixing furnishes a universal mechanism for the spontaneous breaking of supersymmetry. The conjecture is proved explicitly for the mixing of two chiral N=1 supermultiplets and arguments for its general validity are given. That is an instance of the O'Raifeartaigh Lagrangian for which there is no tree-level nor perturbative breaking. Nonetheless, the dynamical breaking occurs due to the vacuum condensate, a mixing-induced nonperturbative effect that lifts the zero point energy. -- Highlights: → In this paper we propose a novel mechanism for spontaneous supersymmetry (SUSY) breaking based on flavor mixing. → We prove the conjecture in detail for the free massive Wess-Zumino case and give robust arguments for the general validity. → We present here is a dynamical SUSY breaking that is induced by a nonperturbative quantum effect.
A laboratory study of breaking waves
Directory of Open Access Journals (Sweden)
Jaros³aw Têgowski
2004-09-01
Full Text Available This paper deals with some aspects of the wave-breaking phenomenon. The objectives were to study wave-breaking criteria, and the probability of whitecap coverage under fully controlled wave conditions. An additional task was to in vestigate the characteristic spectral features of the noise produced by breaking waves and the acoustic energy generated during wave breaking events. A controlled experiment was carried out in the Ocean Basin Laboratory at MARINTEK, Trondheim (Norway. Waves were generated by a computer-controlled multi-flap wave maker, which reproduced a realistic pattern of the sea surface for the prescribed spectra. Using wave staff recordings and photographic techniques, correlations between the breaking parameters and the radiated acoustic emissions were established.
Generalized geometry and partial supersymmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Triendl, Hagen Mathias
2010-08-15
This thesis consists of two parts. In the first part we use the formalism of (exceptional) generalized geometry to derive the scalar field space of SU(2) x SU(2)-structure compactifications. We show that in contrast to SU(3) x SU(3) structures, there is no dynamical SU(2) x SU(2) structure interpolating between an SU(2) structure and an identity structure. Furthermore, we derive the scalar manifold of the low-energy effective action for consistent Kaluza-Klein truncations as expected from N = 4 supergravity. In the second part we then determine the general conditions for the existence of stable Minkowski and AdS N = 1 vacua in spontaneously broken gauged N = 2 supergravities and construct the general solution under the assumption that two appropriate commuting isometries exist in the hypermultiplet sector. Furthermore, we derive the low-energy effective action below the scale of partial supersymmetry breaking and show that it satisfies the constraints of N = 1 supergravity. We then apply the discussion to special quaternionic-Kaehler geometries which appear in the low-energy limit of SU(3) x SU(3)-structure compactifications and construct Killing vectors with the right properties. Finally we discuss the string theory realizations for these solutions. (orig.)
Generalized geometry and partial supersymmetry breaking
International Nuclear Information System (INIS)
This thesis consists of two parts. In the first part we use the formalism of (exceptional) generalized geometry to derive the scalar field space of SU(2) x SU(2)-structure compactifications. We show that in contrast to SU(3) x SU(3) structures, there is no dynamical SU(2) x SU(2) structure interpolating between an SU(2) structure and an identity structure. Furthermore, we derive the scalar manifold of the low-energy effective action for consistent Kaluza-Klein truncations as expected from N = 4 supergravity. In the second part we then determine the general conditions for the existence of stable Minkowski and AdS N = 1 vacua in spontaneously broken gauged N = 2 supergravities and construct the general solution under the assumption that two appropriate commuting isometries exist in the hypermultiplet sector. Furthermore, we derive the low-energy effective action below the scale of partial supersymmetry breaking and show that it satisfies the constraints of N = 1 supergravity. We then apply the discussion to special quaternionic-Kaehler geometries which appear in the low-energy limit of SU(3) x SU(3)-structure compactifications and construct Killing vectors with the right properties. Finally we discuss the string theory realizations for these solutions. (orig.)
Breaking temporal symmetries for emission and absorption
Hadad, Yakir; Soric, Jason C.; Alu, Andrea
2016-03-01
Time-reversal symmetries impose stringent constraints on emission and absorption. Antennas, from radiofrequencies to optics, are bound to transmit and receive signals equally well from the same direction, making a directive antenna prone to receive echoes and reflections. Similarly, in thermodynamics Kirchhoff's law dictates that the absorptivity and emissivity are bound to be equal in reciprocal systems at equilibrium, e(ω,θ)=a(ω,θ), with important consequences for thermal management and energy applications. This bound requires that a good absorber emits a portion of the absorbed energy back to the source, limiting its overall efficiency. Recent works have shown that weak time modulation or mechanical motion in suitably designed structures may largely break reciprocity and time-reversal symmetry. Here we show theoretically and experimentally that a spatiotemporally modulated device can be designed to have drastically different emission and absorption properties. The proposed concept may provide significant advances for compact and efficient radiofrequency communication systems, as well as for energy harvesting and thermal management when translated to infrared frequencies.
Breaking temporal symmetries for emission and absorption.
Hadad, Yakir; Soric, Jason C; Alu, Andrea
2016-03-29
Time-reversal symmetries impose stringent constraints on emission and absorption. Antennas, from radiofrequencies to optics, are bound to transmit and receive signals equally well from the same direction, making a directive antenna prone to receive echoes and reflections. Similarly, in thermodynamics Kirchhoff's law dictates that the absorptivity and emissivity are bound to be equal in reciprocal systems at equilibrium,[Formula: see text], with important consequences for thermal management and energy applications. This bound requires that a good absorber emits a portion of the absorbed energy back to the source, limiting its overall efficiency. Recent works have shown that weak time modulation or mechanical motion in suitably designed structures may largely break reciprocity and time-reversal symmetry. Here we show theoretically and experimentally that a spatiotemporally modulated device can be designed to have drastically different emission and absorption properties. The proposed concept may provide significant advances for compact and efficient radiofrequency communication systems, as well as for energy harvesting and thermal management when translated to infrared frequencies. PMID:26984502
Energy Technology Data Exchange (ETDEWEB)
Huang, Lianjie [Los Alamos National Laboratory; Simonetti, Francesco [IMPERIAL COLLEGE LONDON; Huthwaite, Peter [IMPERIAL COLLEGE LONDON; Rosenberg, Robert [UNM; Williamson, Michael [UNM
2010-01-01
Ultrasound image resolution and quality need to be significantly improved for breast microcalcification detection. Super-resolution imaging with the factorization method has recently been developed as a promising tool to break through the resolution limit of conventional imaging. In addition, wave-equation reflection imaging has become an effective method to reduce image speckles by properly handling ultrasound scattering/diffraction from breast heterogeneities during image reconstruction. We explore the capabilities of a novel super-resolution ultrasound imaging method and a wave-equation reflection imaging scheme for detecting breast microcalcifications. Super-resolution imaging uses the singular value decomposition and a factorization scheme to achieve an image resolution that is not possible for conventional ultrasound imaging. Wave-equation reflection imaging employs a solution to the acoustic-wave equation in heterogeneous media to backpropagate ultrasound scattering/diffraction waves to scatters and form images of heterogeneities. We construct numerical breast phantoms using in vivo breast images, and use a finite-difference wave-equation scheme to generate ultrasound data scattered from inclusions that mimic microcalcifications. We demonstrate that microcalcifications can be detected at full spatial resolution using the super-resolution ultrasound imaging and wave-equation reflection imaging methods.
Huitu, Katri; Tiitola, Paavo
2015-01-01
We examine the deflected mirage mediation supersymmetry breaking (DMMSB) scenario, which includes contributions from three mediation mechanisms, namely anomaly mediation, gravity mediation and gauge mediation, using the one-loop renormalization group invariants (RGIs). We examine the effects on the RGIs at the threshold where the gauge messengers emerge, and derive the soft supersymmetry breaking parameters in terms of the RGIs. We further discuss determining the supersymmetry breaking mechanism using a limited set of invariants, and derive sum rules valid for the DMMSB. In addition we examine some of the implications of the measured Higgs mass to the DMMSB spectrum.
Time-reversal symmetry breaking in quantum billiards
Energy Technology Data Exchange (ETDEWEB)
Schaefer, Florian
2009-01-26
The present doctoral thesis describes experimentally measured properties of the resonance spectra of flat microwave billiards with partially broken timereversal invariance induced by an embedded magnetized ferrite. A vector network analyzer determines the complex scattering matrix elements. The data is interpreted in terms of the scattering formalism developed in nuclear physics. At low excitation frequencies the scattering matrix displays isolated resonances. At these the effect of the ferrite on isolated resonances (singlets) and pairs of nearly degenerate resonances (doublets) is investigated. The hallmark of time-reversal symmetry breaking is the violation of reciprocity, i.e. of the symmetry of the scattering matrix. One finds that reciprocity holds in singlets; it is violated in doublets. This is modeled by an effective Hamiltonian of the resonator. A comparison of the model to the data yields time-reversal symmetry breaking matrix elements in the order of the level spacing. Their dependence on the magnetization of the ferrite is understood in terms of its magnetic properties. At higher excitation frequencies the resonances overlap and the scattering matrix elements fluctuate irregularly (Ericson fluctuations). They are analyzed in terms of correlation functions. The data are compared to three models based on random matrix theory. The model by Verbaarschot, Weidenmueller and Zirnbauer describes time-reversal invariant scattering processes. The one by Fyodorov, Savin and Sommers achieves the same for systems with complete time-reversal symmetry breaking. An extended model has been developed that accounts for partial breaking of time-reversal invariance. This extended model is in general agreement with the data, while the applicability of the other two models is limited. The cross-correlation function between forward and backward reactions determines the time-reversal symmetry breaking matrix elements of the Hamiltonian to up to 0.3 mean level spacings. Finally
Time-reversal symmetry breaking in quantum billiards
International Nuclear Information System (INIS)
The present doctoral thesis describes experimentally measured properties of the resonance spectra of flat microwave billiards with partially broken timereversal invariance induced by an embedded magnetized ferrite. A vector network analyzer determines the complex scattering matrix elements. The data is interpreted in terms of the scattering formalism developed in nuclear physics. At low excitation frequencies the scattering matrix displays isolated resonances. At these the effect of the ferrite on isolated resonances (singlets) and pairs of nearly degenerate resonances (doublets) is investigated. The hallmark of time-reversal symmetry breaking is the violation of reciprocity, i.e. of the symmetry of the scattering matrix. One finds that reciprocity holds in singlets; it is violated in doublets. This is modeled by an effective Hamiltonian of the resonator. A comparison of the model to the data yields time-reversal symmetry breaking matrix elements in the order of the level spacing. Their dependence on the magnetization of the ferrite is understood in terms of its magnetic properties. At higher excitation frequencies the resonances overlap and the scattering matrix elements fluctuate irregularly (Ericson fluctuations). They are analyzed in terms of correlation functions. The data are compared to three models based on random matrix theory. The model by Verbaarschot, Weidenmueller and Zirnbauer describes time-reversal invariant scattering processes. The one by Fyodorov, Savin and Sommers achieves the same for systems with complete time-reversal symmetry breaking. An extended model has been developed that accounts for partial breaking of time-reversal invariance. This extended model is in general agreement with the data, while the applicability of the other two models is limited. The cross-correlation function between forward and backward reactions determines the time-reversal symmetry breaking matrix elements of the Hamiltonian to up to 0.3 mean level spacings. Finally
SUSY breaking after inflation in supergravity with inflaton in a massive vector multiplet
Aldabergenov, Yermek
2016-01-01
We propose a limited class of models, describing interacting chiral multiplets with a non-minimal coupling to a vector multiplet, in curved superspace of $N=1$ supergravity. Those models are suitable for the inflationary model building in supergravity with inflaton assigned to a massive vector multiplet and spontaneous SUSY breaking in Minkowski vacuum after inflation, for any values of the inflationary parameters $n_s$ and $r$, and any scale of SUSY breaking.
Microsphere Super-resolution Imaging
Wang, Zengbo
2015-01-01
Recently, it was discovered that microsphere can generate super-resolution focusing beyond diffraction limit. This has led to the development of an exciting super-resolution imaging technique -microsphere nanoscopy- that features a record resolution of 50 nm under white lights. Different samples have been directly imaged in high resolution and real time without labelling, including both non-biological (nano devices, structures and materials) and biological (subcellular details, viruses) samples. This chapter reviews the technique, which covers its background, fundamentals, experiments, mechanisms as well as the future outlook.
Khademi, Siamak; Darudi, Ahmad; ABBASI, Zahra
2012-01-01
One of the main limitations for the resolution of optical instruments is the size of the sensor's pixels. In this paper we introduce a new sub pixel resolution algorithm to enhance the resolution of images. This method is based on the analysis of multi-images which are fast recorded during the fine relative motion of image and pixel arrays of CCDs. It is shown that by applying this method for a sample noise free image one will enhance the resolution with order of error.
Dirac Neutrino Masses from Generalized Supersymmetry Breaking
International Nuclear Information System (INIS)
We demonstrate that Dirac neutrino masses in the experimentally preferred range are generated within supersymmetric gauge extensions of the standard model with a generalized supersymmetry breaking sector. If the superpotential neutrino Yukawa terms are forbidden by the gauge symmetry [such as a U(1)'], sub-eV scale effective Dirac mass terms can arise at tree level from hard supersymmetry breaking Yukawa couplings, or at one loop due to nonanalytic soft supersymmetry breaking trilinear scalar couplings. The radiative neutrino magnetic and electric dipole moments vanish at one-loop order
Spontaneous chiral parity breaking by hydromagnetic buoyancy
Chatterjee, Piyali; Brandenburg, Axel; Rheinhardt, Matthias
2010-01-01
Evidence for a parity-breaking nature of the magnetic buoyancy instability in a stably stratified gas is reported. In the absence of rotation, no helicity is produced, but the non-helical state is found to be unstable to small helical perturbations during the development of the instability. The parity-breaking nature of an instability in magnetohydrodynamics appears to be the first of its kind and is similar to chiral symmetry breaking in biochemistry. Applications to the production of mean fields in galaxy clusters are being discussed.
Spontaneous chiral symmetry breaking by hydromagnetic buoyancy
Chatterjee, Piyali; Mitra, Dhrubaditya; Brandenburg, Axel; Rheinhardt, Matthias
2011-08-01
Evidence for the parity-breaking nature of the magnetic buoyancy instability in a stably stratified gas is reported. In the absence of rotation, no helicity is produced, but the nonhelical state is found to be unstable to small helical perturbations during the development of the instability. The parity-breaking nature of this magnetohydrodynamic instability appears to be the first of its kind and has properties similar to those in chiral symmetry breaking in biochemistry. Applications to the production of mean fields in galaxy clusters are discussed.
Breaking Free with Wireless Networks.
Fleischman, John
2002-01-01
Discusses wireless local area networks (LANs) which typically consist of laptop computers that connect to fixed access points via infrared or radio signals. Topics include wide area networks; personal area networks; problems, including limitations of available bandwidth, interference, and security concerns; use in education; interoperability;…
Formation of radiation-induced DNA breaks: the ratio of double-strand breaks to single-strand breaks
International Nuclear Information System (INIS)
Ionizing radiation causes the formation of strand breaks in cellular DNA, as well as other types of lesions in the chromatin of cells. Some of the earliest investigations of the molecular basis of radiation-induced damage and the implications of enzymatic repair were done by Dr. H. S. Kaplan. Because it is difficult to assay for DNA lesions in the large mammalian genome, the authors have developed a method of assaying for DNA double-strand breaks in the supercoiled nucleosome-complexed Simian virus 40 (SV40) genome, irradiated intracellularly. In this communication they present their measurements of the DNA double-strand breaks (DSBs) to single-strand breaks (SSBs) ratio obtained from the intracellularly irradiated SV40 genome. After cobalt gamma ray and X ray irradiations, this ratio is about 1/10. Their methods and results are compared with pertinent data in the literature. If the DSBs/SSBs ratio of 1/10 for cellular chromatin is correct, a substantial number of DNA double-strand breaks are formed in a mammalian cell after moderate doses (1 Gy) of radiation. The implications of different types of DNA double-strand breaks are discussed
Unconventional supersymmetry and its breaking
Energy Technology Data Exchange (ETDEWEB)
Alvarez, Pedro D., E-mail: alvarez@physics.ox.ac.uk [Centro de Estudios Científicos (CECS), Av. Arturo Prat 514, Valdivia (Chile); Universidad Andrés Bello, Av. República 440, Santiago (Chile); Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Oxford (United Kingdom); Pais, Pablo, E-mail: pais@cecs.cl [Centro de Estudios Científicos (CECS), Av. Arturo Prat 514, Valdivia (Chile); Universidad Andrés Bello, Av. República 440, Santiago (Chile); Zanelli, Jorge, E-mail: z@cecs.cl [Centro de Estudios Científicos (CECS), Av. Arturo Prat 514, Valdivia (Chile); Universidad Andrés Bello, Av. República 440, Santiago (Chile)
2014-07-30
We present a gauge theory for a superalgebra that includes an internal gauge (G) and local Lorentz (so(1,D−1)) algebras. These two symmetries are connected by fermionic supercharges. The field content of the system includes a (non-)abelian gauge potential A, a spin-1/2 Dirac spinor ψ, the Lorentz connection ω{sup ab}, and the vielbein e{sub μ}{sup a}. The connection one-form A is in the adjoint representation of G, while ψ is in the fundamental. In contrast to standard supersymmetry and supergravity, the metric is not a fundamental field and is in the center of the superalgebra: it is not only invariant under the internal gauge group, G, and under Lorentz transformations, SO(1,D−1), but is also invariant under supersymmetry. The distinctive features of this theory that mark the difference with standard supersymmetries are: i) the number of fermionic and bosonic states is not necessarily the same; ii) there are no superpartners with equal mass; iii) although this supersymmetry originates in a local gauge theory and gravity is included, there is no gravitino; iv) fermions acquire mass from their coupling to the background or from higher order self-couplings, while bosons remain massless. In odd dimensions, the Chern–Simons (CS) form provides an action that is (quasi-)invariant under the entire superalgebra. In even dimensions, the Yang–Mills (YM) form is the only natural option and the symmetry breaks down to G⊗SO(1,D−1). In four dimensions, the construction follows the Townsend–Mac Dowell–Mansouri approach, starting with an osp(4|2)∼usp(2,2|1) connection. Due to the absence of osp(4|2)-invariant traces in four dimensions, the resulting Lagrangian is only invariant under u(1)⊕so(3,1), which includes a Nambu–Jona-Lasinio (NJL) term. In this case, the Lagrangian depends on a single dimensionful parameter that fixes Newton's constant, the cosmological constant and the NJL coupling.
10 microsecond time resolution studies of Cygnus X-1
Energy Technology Data Exchange (ETDEWEB)
Wen, H.C.
1997-06-01
Time variability analyses have been applied to data composed of event times of X-rays emitted from the binary system Cygnus X-1 to search for unique black hole signatures. The X-ray data analyzed was collected at ten microsecond time resolution or better from two instruments, the High Energy Astrophysical Observatory (HEAO) A-1 detector and the Rossi X-ray Timing Explorer (XTE) Proportional Counter Array (PCA). HEAO A-1 and RXTE/PCA collected data from 1977--79 and from 1996 on with energy sensitivity from 1--25 keV and 2--60 keV, respectively. Variability characteristics predicted by various models of an accretion disk around a black hole have been searched for in the data. Drop-offs or quasi-periodic oscillations (QPOs) in the Fourier power spectra are expected from some of these models. The Fourier spectral technique was applied to the HEAO A-1 and RXTE/PCA data with careful consideration given for correcting the Poisson noise floor for instrumental effects. Evidence for a drop-off may be interpreted from the faster fall off in variability at frequencies greater than the observed breaks. Both breaks occur within the range of Keplerian frequencies associated with the inner edge radii of advection-dominated accretion disks predicted for Cyg X-1. The break between 10--20 Hz is also near the sharp rollover predicted by Nowak and Wagoner`s model of accretion disk turbulence. No QPOs were observed in the data for quality factors Q > 9 with a 95% confidence level upper limit for the fractional rms amplitude at 1.2% for a 16 M{sub {circle_dot}} black hole.
Dirac neutrino masses from generalized supersymmetry breaking
International Nuclear Information System (INIS)
We demonstrate that Dirac neutrino masses in the experimentally preferred range are generated within supersymmetric gauge extensions of the Standard Model with a generalized supersymmetry breaking sector. If the usual superpotential Yukawa couplings are forbidden by the additional gauge symmetry (such as a U(1)'), effective Dirac mass terms involving the ''wrong Higgs'' field can arise either at tree level due to hard supersymmetry breaking fermion Yukawa couplings, or at one-loop due to nonanalytic or ''nonholomorphic'' soft supersymmetry breaking trilinear scalar couplings. As both of these operators are naturally suppressed in generic models of supersymmetry breaking, the resulting neutrino masses are naturally in the sub-eV range. The neutrino magnetic and electric dipole moments resulting from the radiative mechanism also vanish at one-loop order. (orig.)
Dirac Neutrino Masses from Generalized Supersymmetry Breaking
Demir, Durmus A; Langacker, Paul
2007-01-01
We demonstrate that Dirac neutrino masses in the experimentally preferred range are generated within supersymmetric gauge extensions of the Standard Model with a generalized supersymmetry breaking sector. If the usual superpotential Yukawa couplings are forbidden by the additional gauge symmetry (such as a U(1)'), effective Dirac mass terms involving the "wrong Higgs" field can arise either at tree level due to hard supersymmetry breaking fermion Yukawa couplings, or at one-loop due to nonanalytic or "nonholomorphic" soft supersymmetry breaking trilinear scalar couplings. As both of these operators are naturally suppressed in generic models of supersymmetry breaking, the resulting neutrino masses are naturally in the sub-eV range. The neutrino magnetic and electric dipole moments resulting from the radiative mechanism also vanish at one-loop order.
Spontaneous chiral symmetry breaking in metamaterials
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.
Massie, Norbert A.; Oster, Yale
1992-01-01
A large effective-aperture, low-cost optical telescope with diffraction-limited resolution enables ground-based observation of near-earth space objects. The telescope has a non-redundant, thinned-aperture array in a center-mount, single-structure space frame. It employs speckle interferometric imaging to achieve diffraction-limited resolution. The signal-to-noise ratio problem is mitigated by moving the wavelength of operation to the near-IR, and the image is sensed by a Silicon CCD. The steerable, single-structure array presents a constant pupil. The center-mount, radar-like mount enables low-earth orbit space objects to be tracked as well as increases stiffness of the space frame. In the preferred embodiment, the array has elemental telescopes with subaperture of 2.1 m in a circle-of-nine configuration. The telescope array has an effective aperture of 12 m which provides a diffraction-limited resolution of 0.02 arc seconds. Pathlength matching of the telescope array is maintained by an electro-optical system employing laser metrology. Speckle imaging relaxes pathlength matching tolerance by one order of magnitude as compared to phased arrays. Many features of the telescope contribute to substantial reduction in costs. These include eliminating the conventional protective dome and reducing on-site construction activites. The cost of the telescope scales with the first power of the aperture rather than its third power as in conventional telescopes.
Relativistic theory of string breaking in QCD
Simonov, Yu A
2011-01-01
The QCD string breaking due to quark pair creation in the vacuum confining field, possibly accompanied by vector, scalar or Nambu-Goldstone bosons, is studied nonperturbatively. The scalar light pair creation vertex occurs due to chiral symmetry breaking and has a confining form, which is computed explicitly together with subleading vector contributions. Dependence on light quark mass and flavor is specifically studied. The dominant scalar term is in good agreement with the $^3P_0$ model and experimental data.
AIR LOAD BREAK SWITCH DESIGN PARAMETERS
Støa-Aanensen, Nina Sasaki
2015-01-01
Current interruption is vital in the power system, as this makes it possible to control the use of different loads, change the grid configuration, and minimize damage when faults occur. This thesis presents a study of the different switch design and test circuit parameters involved in medium voltage air load break switching and how they affect the thermal interrupting capability. Mediumvoltage load break switches are common in the distribution grid, and are a cheaper option ...
Grand unification with large supersymmetry breaking
International Nuclear Information System (INIS)
General criteria are given for the magnitudes of mass splittings between supersymmetric partners compatible with the desired hierarchy of mass scales in GUTs. These splittings arise naturally when masses are generated radiatively from a Higgs sector breaking supersymmetry through the O'Raifeartaigh mechanism (Nucl. Phys; B96:331 (1975)). Explicit GUTs are constructed in which the supersymmetry breaking scale may easily be as large as the Planck mass. (author)
Dirac Neutrino Masses from Generalized Supersymmetry Breaking
Demir, Durmus A.; Everett, Lisa L.; Langacker, Paul
2007-01-01
We demonstrate that Dirac neutrino masses in the experimentally preferred range are generated within supersymmetric gauge extensions of the Standard Model with a generalized supersymmetry breaking sector. If the usual superpotential Yukawa couplings are forbidden by the additional gauge symmetry (such as a U(1)'), effective Dirac mass terms involving the "wrong Higgs" field can arise either at tree level due to hard supersymmetry breaking fermion Yukawa couplings, or at one-loop due to nonana...
A random fuse model for breaking processes
de Arcangelis, L.; Redner, S.; Herrmann, H. J.
1985-01-01
We introduce and study a simple idealized model to describe breaking processes by analysing the current-carrying properties of a random network consisting of insulators and fuses. By increasing the value of the external voltage applied across the network, a sequence of fuses will « burn out » and change irreversible into insultating bonds. This process terminates when a conducting path no longer exists in the network. We monitor several basic quantities during this breaking process, such as t...
Yet another symmetry breaking to be discovered
Yoshimura, M
2016-01-01
The discovery of spontaneous symmetry breaking in particle physics was the greatest contribution in Nambu's achievements. There is another class of symmetries that exist in the low energy nature, yet is doomed to be broken at high energy, due to a lack of protection of the gauge symmetry. I shall review our approach to search for this class of symmetry breaking, the lepton number violation linked to generation of the matter-antimatter asymmetry in our universe.
Dark matter from dynamical SUSY breaking
Fan, JiJi; Thaler, Jesse; Wang, Lian-Tao
2010-01-01
We consider explicit models of dynamical supersymmetry breaking where dark matter is a 10 – 100 TeV strongly-interacting composite state carrying no standard model quantum numbers. These constructions are simple variants of well-known supersymmetry breaking mechanisms, augmented to allow for a large “flavor” symmetry. Dark matter is the lightest composite modulus charged under this symmetry and is a viable cold dark matter candidate with a thermal relic abundance. This is an at...
Holographic realization of gauge mediated supersymmetry breaking
Skenderis, Kostas
2012-01-01
The general gauge mediation scenario provides a framework in which properties of a visible sector with soft supersymmetry breaking are computed from current correlation functions in the supersymmetry breaking hidden sector. In this paper we will use holography to model strongly coupled hidden sectors by weakly curved geometries and describe how the current correlators relevant for general gauge mediation are computed by holographic methods. We illustrate the general setup by a toy example which captures most of the relevant features.
Chimera Death: Symmetry Breaking in Dynamical Networks
Zakharova, Anna; Kapeller, Marie; Schöll, Eckehard
2014-01-01
For a network of generic oscillators with nonlocal topology and symmetry-breaking coupling we establish novel partially coherent inhomogeneous spatial patterns, which combine the features of chimera states (coexisting incongruous coherent and incoherent domains) and oscillation death (oscillation suppression), which we call chimera death. We show that due to the interplay of nonlocality and breaking of rotational symmetry by the coupling two distinct scenarios from oscillatory behavior to a s...
Yet another symmetry breaking to be discovered
Yoshimura, M.
2016-07-01
The discovery of spontaneous symmetry breaking in particle physics was the greatest contribution in Nambu's achievements. There is another class of symmetries that exist in low-energy nature, yet is doomed to be broken at high energy, due to a lack of protection of the gauge symmetry. I shall review our approach to searching for this class of symmetry breaking, the lepton number violation linked to the generation of the matter-antimatter asymmetry in our universe.
Tailings dam-break flow - Analysis of sediment transport
Aleixo, Rui; Altinakar, Mustafa
2015-04-01
A common solution to store mining debris is to build tailings dams near the mining site. These dams are usually built with local materials such as mining debris and are more vulnerable than concrete dams (Rico et al. 2008). of The tailings and the pond water generally contain heavy metals and various toxic chemicals used in ore extraction. Thus, the release of tailings due to a dam-break can have severe ecological consequences in the environment. A tailings dam-break has many similarities with a common dam-break flow. It is highly transient and can be severely descructive. However, a significant difference is that the released sediment-water mixture will behave as a non-Newtonian flow. Existing numerical models used to simulate dam-break flows do not represent correctly the non-Newtonian behavior of tailings under a dam-break flow and may lead to unrealistic and incorrect results. The need for experiments to extract both qualitative and quantitative information regarding these flows is therefore real and actual. The present paper explores an existing experimental data base presented in Aleixo et al. (2014a,b) to further characterize the sediment transport under conditions of a severe transient flow and to extract quantitative information regarding sediment flow rate, sediment velocity, sediment-sediment interactions a among others. Different features of the flow are also described and analyzed in detail. The analysis is made by means of imaging techniques such as Particle Image Velocimetry and Particle Tracking Velocimetry that allow extracting not only the velocity field but the Lagrangian description of the sediments as well. An analysis of the results is presented and the limitations of the presented experimental approach are discussed. References Rico, M., Benito, G., Salgueiro, AR, Diez-Herrero, A. and Pereira, H.G. (2008) Reported tailings dam failures: A review of the European incidents in the worldwide context , Journal of Hazardous Materials, 152, 846
Realization of chiral symmetry breaking and restoration in holographic QCD
Chelabi, Kaddour; Huang, Mei; Li, Danning; Wu, Yue-Liang
2015-01-01
With proper profiles of the scalar potential and the dilaton field, for the first time, the spontaneous chiral symmetry breaking in the vacuum and its restoration at finite temperature are correctly realized in the holographic QCD framework. In the chiral limit, a nonzero chiral condensate develops in the vacuum and decreases with temperature, and the phase transition is of 2nd order for two-flavor case and of 1st order for three-flavor case. In the case of explicit chiral symmetry breaking, in two-flavor case, the 2nd order phase transition turns to crossover with any nonzero current quark mass, and in three-flavor case, the 1st order phase transition turns to crossover at a finite current quark mass. The correct description of chiral symmetry breaking and restoration makes the holographic QCD models more powerful in dealing with non-perturbative QCD phenomena. This framework can be regarded as a general set up in application of AdS/CFT to describe conventional Ginzburg-Landau-Wilson type phase transitions, ...
Comparison of methods for extrapolating breaking creep results
International Nuclear Information System (INIS)
Among all the methods of extrapolation, the following have been selected: - parametric methods (Larson-Miller, Dorn, Manson-Haferd); - digital and parametric method (minimum commitment); - digital method (finite differences); - descriptive method (Givar). The Larson-Miller, Dorn and Manson-Haferd methods are commonly used for analyzing the breaking creep results of materials for which the master curves can be described simply. The other methods have been developed in order to analyze the breaking creep results of materials where the structural changes over time modify the creep behaviour. In each case the assessment of the parameters is achieved by the least squares method. These methods were compared with each other on two steels, namely: Z6 CND 17-12 (316) and Z4 CND 35-20 (800 alloy). The various analyses performed show that (a) the predictions made as from the different methods are in good agreement between each other when there is a sufficient number of experimental values and (b) the predictions of the breaking times in the case of the 800 alloy differ from one method to the next. This result is due to the limited sampling data and to the complex behaviour of this alloy, the properties of which change with ageing
A Theoretical Model for the Prediction of Siphon Breaking Phenomenon
International Nuclear Information System (INIS)
A siphon phenomenon or siphoning often refers to the movement of liquid from a higher elevation to a lower one through a tube in an inverted U shape (whose top is typically located above the liquid surface) under the action of gravity, and has been used in a variety of reallife applications such as a toilet bowl and a Greedy cup. However, liquid drainage due to siphoning sometimes needs to be prevented. For example, a siphon breaker, which is designed to limit the siphon effect by allowing the gas entrainment into a siphon line, is installed in order to maintain the pool water level above the reactor core when a loss of coolant accident (LOCA) occurs in an open-pool type research reactor. In this paper, we develop a theoretical model to predict the siphon breaking phenomenon. In this paper, a theoretical model to predict the siphon breaking phenomenon is developed. It is shown that the present model predicts well the fundamental features of the siphon breaking phenomenon and undershooting height
A Theoretical Model for the Prediction of Siphon Breaking Phenomenon
Energy Technology Data Exchange (ETDEWEB)
Bae, Youngmin; Kim, Young-In; Seo, Jae-Kwang; Kim, Keung Koo; Yoon, Juhyeon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2014-10-15
A siphon phenomenon or siphoning often refers to the movement of liquid from a higher elevation to a lower one through a tube in an inverted U shape (whose top is typically located above the liquid surface) under the action of gravity, and has been used in a variety of reallife applications such as a toilet bowl and a Greedy cup. However, liquid drainage due to siphoning sometimes needs to be prevented. For example, a siphon breaker, which is designed to limit the siphon effect by allowing the gas entrainment into a siphon line, is installed in order to maintain the pool water level above the reactor core when a loss of coolant accident (LOCA) occurs in an open-pool type research reactor. In this paper, we develop a theoretical model to predict the siphon breaking phenomenon. In this paper, a theoretical model to predict the siphon breaking phenomenon is developed. It is shown that the present model predicts well the fundamental features of the siphon breaking phenomenon and undershooting height.
Breaking object correspondence across saccadic eye movements deteriorates object recognition
Directory of Open Access Journals (Sweden)
Christian H. Poth
2015-12-01
Full Text Available Visual perception is based on information processing during periods of eye fixations that are interrupted by fast saccadic eye movements. The ability to sample and relate information on task-relevant objects across fixations implies that correspondence between presaccadic and postsaccadic objects is established. Postsaccadic object information usually updates and overwrites information on the corresponding presaccadic object. The presaccadic object representation is then lost. In contrast, the presaccadic object is conserved when object correspondence is broken. This helps transsaccadic memory but it may impose attentional costs on object recognition. Therefore, we investigated how breaking object correspondence across the saccade affects postsaccadic object recognition. In Experiment 1, object correspondence was broken by a brief postsaccadic blank screen. Observers made a saccade to a peripheral object which was displaced during the saccade. This object reappeared either immediately after the saccade or after the blank screen. Within the postsaccadic object, a letter was briefly presented (terminated by a mask. Observers reported displacement direction and letter identity in different blocks. Breaking object correspondence by blanking improved displacement identification but deteriorated postsaccadic letter recognition. In Experiment 2, object correspondence was broken by changing the object’s contrast-polarity. There were no object displacements and observers only reported letter identity. Again, breaking object correspondence deteriorated postsaccadic letter recognition. These findings identify transsaccadic object correspondence as a key determinant of object recognition across the saccade. This is in line with the recent hypothesis that breaking object correspondence results in separate representations of presaccadic and postsaccadic objects which then compete for limited attentional processing resources (Schneider, 2013. Postsaccadic
Minimal but non-minimal inflation and electroweak symmetry breaking
Marzola, Luca
2016-01-01
We consider the most minimal scale invariant extension of the standard model that allows for successful radiative electroweak symmetry breaking and inflation. The framework involves an extra scalar singlet, that plays the r\\^ole of the inflaton, and is compatibile with current experimental bounds owing to the non-minimal coupling of the latter to gravity. This inflationary scenario predicts a very low tensor-to-scalar ratio $r \\approx 10^{-3}$, typical of Higgs-inflation models, but in contrast yields a scalar spectral index $n_s \\simeq 0.97$ which departs from the Starobinsky limit. We briefly discuss the collider phenomenology of the framework.
Tranverse beam break up in a periodic linac
International Nuclear Information System (INIS)
The problem of cumulative beam break up in a periodic linac for a general impedance is discussed, with the effects of acceleration included. The transverse equations of motion for a set of identical point like bunches moving along the length of the linac are cast into a simple form using a smooth approximation. This results in a working formula that is used to analyze beam breakup. Explicit expressions for the transverse motion in the case of a single resonance impedance are found using saddle point integration. This is done first with no external focusing, and again in the strong focusing limit
Leak before break application in French PWR plants under operation
Energy Technology Data Exchange (ETDEWEB)
Faidy, C. [EDF SEPTEN, Villeurbanne (France)
1997-04-01
Practical applications of the leak-before break concept are presently limited in French Pressurized Water Reactors (PWR) compared to Fast Breeder Reactors. Neithertheless, different fracture mechanic demonstrations have been done on different primary, auxiliary and secondary PWR piping systems based on similar requirements that the American NUREG 1061 specifications. The consequences of the success in different demonstrations are still in discussion to be included in the global safety assessment of the plants, such as the consequences on in-service inspections, leak detection systems, support optimization,.... A large research and development program, realized in different co-operative agreements, completes the general approach.
Symmetry Breaking and Quark-Hadron Duality in Structure Functions
International Nuclear Information System (INIS)
We identify conditions under which a summation over nucleon resonances can yield, via quark-hadron duality, parton model results for electromagnetic and neutrino structure functions at large x. While a summation over the lowest even and odd parity multiplets is sufficient to achieve duality in the symmetric quark model, a suppression of transitions to specific final states is required for more realistic cases incorporating SU(6) breaking. We outline several scenarios consistent with duality, discuss their implications for the high Q2 behavior of transition form factors, and illustrate how they can expose the patterns in the flavor-spin dependence of short-distance forces in the strong-QCD limit
Chiral symmetry and chiral-symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Peskin, M.E.
1982-12-01
These lectures concern the dynamics of fermions in strong interaction with gauge fields. Systems of fermions coupled by gauge forces have a very rich structure of global symmetries, which are called chiral symmetries. These lectures will focus on the realization of chiral symmetries and the causes and consequences of thier spontaneous breaking. A brief introduction to the basic formalism and concepts of chiral symmetry breaking is given, then some explicit calculations of chiral symmetry breaking in gauge theories are given, treating first parity-invariant and then chiral models. These calculations are meant to be illustrative rather than accurate; they make use of unjustified mathematical approximations which serve to make the physics more clear. Some formal constraints on chiral symmetry breaking are discussed which illuminate and extend the results of our more explicit analysis. Finally, a brief review of the phenomenological theory of chiral symmetry breaking is presented, and some applications of this theory to problems in weak-interaction physics are discussed. (WHK)
Modelling oil price volatility with structural breaks
International Nuclear Information System (INIS)
In this paper, we provide two main innovations: (i) we analyze oil prices of two prominent markets namely West Texas Intermediate (WTI) and Brent using the two recently developed tests by Narayan and Popp (2010) and Liu and Narayan, 2010 both of which allow for two structural breaks in the data series; and (ii) the latter method is modified to include both symmetric and asymmetric volatility models. We identify two structural breaks that occur in 1990 and 2008 which coincidentally correspond to the Iraqi/Kuwait conflict and the global financial crisis, respectively. We find evidence of persistence and leverage effects in the oil price volatility. While further extensions can be pursued, the consideration of asymmetric effects as well as structural breaks should not be jettisoned when modelling oil price volatility. - Highlights: ► We analyze oil price volatility using NP (2010) and LN (2010) tests. ► We modify the LN (2010) to account for leverage effects in oil price. ► We find two structural breaks that reflect major global crisis in the oil market. ► We find evidence of persistence and leverage effects in oil price volatility. ► Leverage effects and structural breaks are fundamental in oil price modelling.
Type III Guyon Syndrome in 'B Boy' Break-Dancer: A Case Report
Hu, Soo-young; Choi, Jin-gyu
2015-01-01
Although the musculoskeletal injuries associated with break-dancing which is gaining more popularity among adolescent and young people has been reported, the report regarding a peripheral nerve injury associated with breakdance is scarce. We report a rare case of a young amateur break-dancer, 'b-boy' who suffered from a painful paresthesia in his left hand, later diagnosed as type III Guyon's canal syndrome. A 23-year-old, right handed college man presented with a tenderness over the left hypothenar eminence and painful paresthesia over the ring and little fingers of 3 months duration. He trained himself as an amateur 'b boy' break-dancer for the last 10 months. Conservative management under the diagnosis of wrist sprain before presentation did not improve his hand pain. An magnetic resonance imaging and electrodiagnostic study revealed that painful paresthesia was caused by type III Guyon's canal syndrome, and 4 weeks of corticosteroid treatment was given with resolution of pain and paresthesia.
Quantum dynamics in the thermodynamic limit
International Nuclear Information System (INIS)
The description of spontaneous symmetry breaking that underlies the connection between classically ordered objects in the thermodynamic limit and their individual quantum-mechanical building blocks is one of the cornerstones of modern condensed-matter theory and has found applications in many different areas of physics. The theory of spontaneous symmetry breaking, however, is inherently an equilibrium theory, which does not address the dynamics of quantum systems in the thermodynamic limit. Here, we will use the example of a particular antiferromagnetic model system to show that the presence of a so-called thin spectrum of collective excitations with vanishing energy - one of the well-known characteristic properties shared by all symmetry-breaking objects - can allow these objects to also spontaneously break time-translation symmetry in the thermodynamic limit. As a result, that limit is found to be able, not only to reduce quantum-mechanical equilibrium averages to their classical counterparts, but also to turn individual-state quantum dynamics into classical physics. In the process, we find that the dynamical description of spontaneous symmetry breaking can also be used to shed some light on the possible origins of Born's rule. We conclude by describing an experiment on a condensate of exciton polaritons which could potentially be used to experimentally test the proposed mechanism
Break-glass handling exceptional situations in access control
Petritsch, Helmut
2014-01-01
Helmut Petritsch describes the first holistic approach to Break-Glass which covers the whole life-cycle: from access control modeling (pre-access), to logging the security-relevant system state during Break-Glass accesses (at-access), and the automated analysis of Break-Glass accesses (post-access). Break-Glass allows users to override security restrictions in exceptional situations. While several Break-Glass models specific to given access control models have already been discussed in research (e.g., extending RBAC with Break-Glass), the author introduces a generic Break-Glass model. The pres
Marginal Breaking of Conformal SUSY QCD
Cleary, Kevin F
2015-01-01
We provide an example of a 4D theory that exhibits the Contino-Pomarol-Rattazzi mechanism, where breaking conformal symmetry by an almost marginal operator leads to a light pseudo-Goldstone boson, the dilaton, and a parametrically suppressed contribution to vacuum energy. We consider SUSY QCD at the edge of the conformal window and break conformal symmetry by weakly gauging a subgroup of the flavor symmetry. Using Seiberg duality we show that for a range of parameters the singlet meson in the dual theory reaches the unitarity bound, however, this theory does not have a stable vacuum. We stabilize the vacuum with soft breaking terms, compute the mass of the dilaton, and determine the range of parameters where the leading contribution to the dilaton mass is from the almost marginal coupling.
Supersymmetry breaking as a quantum phase transition
International Nuclear Information System (INIS)
We explore supersymmetry breaking in the light of a rich fixed-point structure of two-dimensional supersymmetric Wess-Zumino models with one supercharge using the functional renormalization group. We relate the dynamical breaking of supersymmetry to a renormalization group relevant control parameter of the superpotential which is a common relevant direction of all fixed points of the system. Supersymmetry breaking can thus be understood as a quantum phase transition analogous to similar transitions in correlated fermion systems. Supersymmetry gives rise to a new superscaling relation between the critical exponent associated with the control parameter and the anomalous dimension of the field - a scaling relation which is not known in standard spin systems.
Supersymmetry breaking as a quantum phase transition
Gies, Holger; Wipf, Andreas
2009-01-01
We explore supersymmetry breaking in the light of a rich fixed-point structure of two-dimensional supersymmetric Wess-Zumino models with one supercharge using the functional renormalization group (RG). We relate the dynamical breaking of supersymmetry to an RG relevant control parameter of the superpotential which is a common relevant direction of all fixed points of the system. Supersymmetry breaking can thus be understood as a quantum phase transition analogously to similar transitions in correlated fermion systems. Supersymmetry gives rise to a new superscaling relation between the critical exponent associated with the control parameter and the anomalous dimension of the field -- a scaling relation which is not known in standard spin systems.
Workshop on electroweak symmetry breaking: proceedings
International Nuclear Information System (INIS)
A theoretical workshop on electroweak symmetry breaking at the Superconducting Supercollider was held at Lawrence Berkeley Laboratory, June 4-22, 1984. The purpose of the workshop was to focus theoretical attention on the ways in which experimentation at the SSC could reveal manifestations of the phenomenon responsible for electroweak symmetry breaking. This issue represents, at present, the most compelling scientific argument for the need to explore the energy region to be made accessible by the SSC, and a major aim of the workshop was to involve a broad cross section of particle theorists in the ongoing process of sharpening the requirements for both accelerator and detector design that will ensure detection and identification of meaningful signals, whatever form the electroweak symmetry breaking phenomenon should actually take. Separate entries were prepared for the data base for the papers presented
Enhanced breaking of heavy quark spin symmetry
Guo, Feng-Kun; Shen, Cheng-Ping
2014-01-01
Heavy quark spin symmetry is useful to make predictions on ratios of decay or production rates of systems involving heavy quarks. The breaking of spin symmetry is generally of the order of $O({\\Lambda_{\\rm QCD}/m_Q})$, with $\\Lambda_{\\rm QCD}$ the scale of QCD and $m_Q$ the heavy quark mass. In this paper, we propose a new mechanism to enhance the spin symmetry breaking. Taking the decays of the $\\Upsilon(10860)$ into the $\\chi_{bJ}\\omega\\, (J=0,1,2)$ as an example, we show that a small $S$- and $D$-wave mixing can induce a significant breaking of the spin symmetry relations for the ratios of the branching fractions of these decays, owing to an enhancement of the decays of the $D$-wave component due to nearby coupled channels.
A break in the obesity epidemic?
DEFF Research Database (Denmark)
Visscher, T L S; Heitmann, B L; Rissanen, A;
2015-01-01
epidemic. However, follow-ups of short duration may, in part, explain the apparent break or decrease in the obesity epidemic. On the other hand, a single focus on body mass index (BMI) ⩾25 or ⩾30 kg m(-)(2) is likely to mask a real increase in the obesity epidemic. And, in both children and adults, trends......Recent epidemiologic papers are presenting prevalence data suggesting breaks and decreases in obesity rates. However, before concluding that the obesity epidemic is not increasing anymore, the validity of the presented data should be discussed more thoroughly. We had a closer look...... into the literature presented in recent reviews to address the major potential biases and distortions, and to develop insights about how to interpret the presented suggestions for a potential break in the obesity epidemic. Decreasing participation rates, the use of reported rather than measured data and small sample...
Workshop on electroweak symmetry breaking: proceedings
Energy Technology Data Exchange (ETDEWEB)
Hinchliffe, I. (ed.)
1984-10-01
A theoretical workshop on electroweak symmetry breaking at the Superconducting Supercollider was held at Lawrence Berkeley Laboratory, June 4-22, 1984. The purpose of the workshop was to focus theoretical attention on the ways in which experimentation at the SSC could reveal manifestations of the phenomenon responsible for electroweak symmetry breaking. This issue represents, at present, the most compelling scientific argument for the need to explore the energy region to be made accessible by the SSC, and a major aim of the workshop was to involve a broad cross section of particle theorists in the ongoing process of sharpening the requirements for both accelerator and detector design that will ensure detection and identification of meaningful signals, whatever form the electroweak symmetry breaking phenomenon should actually take. Separate entries were prepared for the data base for the papers presented.
Large eddy simulation of breaking waves
DEFF Research Database (Denmark)
Christensen, Erik Damgaard; Deigaard, Rolf
2001-01-01
A numerical model is used to simulate wave breaking, the large scale water motions and turbulence induced by the breaking process. The model consists of a free surface model using the surface markers method combined with a three-dimensional model that solves the flow equations. The turbulence is...... incoming waves are specified by a flux boundary condition. The waves are approaching in the shore-normal direction and are breaking on a plane, constant slope beach. The first few wave periods are simulated by a two-dimensional model in the vertical plane normal to the beach line. The model describes the...... steepening and the overturning of the wave. At a given instant, the model domain is extended to three dimensions, and the two-dimensional flow field develops spontaneously three-dimensional flow features with turbulent eddies. After a few wave periods, stationary (periodic) conditions are achieved. The...
International Nuclear Information System (INIS)
The document establishes the maximum limits for the total activity of radionuclides and some special provisions for fissile materials which are excluded from the application of the Vienna Convention on Civil Liability for Nuclear Damage while in international nuclear transport
Breaking bad news in cancer patients
Directory of Open Access Journals (Sweden)
Apostolos Konstantis
2015-01-01
Full Text Available Objective: In a regional hospital, many patients are newly diagnosed with cancer. Breaking the bad news in these patients and their relatives is a tough task. Many doctors are not experienced in talking to patients about death or death-related diseases. In recent years, there have been great efforts to change the current situation. The aim of this study was to investigate the experience and education of medical personnel in breaking bad news in a secondary hospital. Materials and Methods: 59 doctors from General Hospital of Komotini, Greece were included in the study. All the doctors were in clinical specialties that treated cancer patients. A brief questionnaire was developed based on current guidelines such as Baile/SPIKES framework and the ABCDE mnemonic. Results: Residents are involved in delivering bad news less frequently than specialists. Only 21 doctors (35.59% had specific training on breaking bad news. 20 doctors (33.90% were aware of the available techniques and protocols on breaking bad news. 47 doctors (79.66% had a consistent plan for breaking bad news. 57 (96.61% delivered bad news in a quiet place, 53 (89.83% ensured no interruptions and enough time, 53 (89.83% used simple words and 54 (91.53% checked for understanding and did not rush through the news. 46 doctors (77.97% allowed relatives to determine patient′s knowledge about the disease. Conclusions: There were low rates of specific training in breaking bad news. However, the selected location, the physician′s speech and their plan were according to current guidelines.
Coupled simulation of steam line break accident
International Nuclear Information System (INIS)
The steam line break is a PWR type reactor design accident, which concerns coupled physical phenomena. To control these problems simulation are needed to define and validate the operating procedures. The benchmark OECD PWR MSLB (Main Steam Line Break) has been proposed by the OECD to validate the feasibility and the contribution of the multi-dimensional tools in the simulation of the core transients. First the benchmark OECD PWR MSLB is presented. Then the analysis of the three exercises (system with pinpoint kinetic, three-dimensional core and whole system with three-dimensional core) are discussed. (A.L.B.)
Polarimetric contrast microscopy by orthogonality breaking
International Nuclear Information System (INIS)
We report the design and first implementation of an active polarimetric imaging system based on the recently introduced concept of polarimetric sensing by orthogonality breaking, which involves a specific crossed-polarization dual-frequency illumination. We describe the laser source architecture and microscope set-up devoted to visible imaging at 488 nm, as well as the specific homodyne detection chain required for orthogonality breaking measurements. The first polarimetric images obtained with this non-conventional approach are presented. The polarimetric contrasts observed validate the polarimetric sensitivity of the technique. (fast track communication)
R-Parity Breaking in Minimal Supergravity
Díaz, M A
1997-01-01
We consider the Minimal Supergravity Model with universality of scalar and gaugino masses plus an extra bilinear term in the superpotential which breaks R-Parity and lepton number. We explicitly check the consistency of this model with the radiative breaking of the electroweak symmetry. A neutrino mass is radiatively induced, and large Higgs-Lepton mixings are compatible with its experimental bound. We also study briefly the lightest Higgs mass. This one-parameter extension of SUGRA-MSSM is the simplest way of introducing R-parity violation.
Variations on Minimal Gauge Mediated Supersymmetry Breaking
Dine, Michael; Shirman, Yu; Dine, Michael; Nir, Yosef; Shirman, Yuri
1997-01-01
We study various modifications to the minimal models of gauge mediated supersymmetry breaking. We argue that, under reasonable assumptions, the structure of the messenger sector is rather restricted. We investigate the effects of possible mixing between messenger and ordinary squark and slepton fields and, in particular, violation of universality. We show that acceptable values for the $\\mu$ and $B$ parameters can naturally arise from discrete, possibly horizontal, symmetries. We claim that in models where the supersymmetry breaking parameters $A$ and $B$ vanish at tree level, $\\tan\\beta$ could be large without fine tuning. We explain how the supersymmetric CP problem is solved in such models.
The experimental investigation of supersymmetry breaking
International Nuclear Information System (INIS)
If Nature is supersymmetric at the weak interaction scale, what can we hope to learn from experiments on supersymmetric particles? The most mysterious aspect of phenomenological supersymmetry is the mechanism of spontaneous supersymmetry breaking. This mechanism ties the observable pattern of supersymmetric particle masses to aspects of the underlying unified theory at very small distance scales. In this article, I will discuss a systematic experimental program to determine the mechanism of supersymmetry breaking. Both pp and e+e- colliders of the next generation play an essential role
Chiral Symmetry Breaking from Center Vortices
Höllwieser, Roman; Schweigler, Thomas; Heller, Urs M
2014-01-01
We analyze the creation of near-zero modes from would-be zero modes of various topological charge contributions from classical center vortices in SU(2) lattice gauge theory. We show that colorful spherical vortex and instanton configurations have very similar Dirac eigenmodes and also vortex intersections are able to give rise to a finite density of near-zero modes, leading to chiral symmetry breaking via the Banks-Casher formula. We discuss the influence of the magnetic vortex fluxes on quarks and how center vortices may break chiral symmetry.
Symmetry-Break in Voronoi Tessellations
Directory of Open Access Journals (Sweden)
Valerio Lucarini
2009-08-01
Full Text Available We analyse in a common framework the properties of the Voronoi tessellations resulting from regular 2D and 3D crystals and those of tessellations generated by Poisson distributions of points, thus joining on symmetry breaking processes and the approach to uniform random distributions of seeds. We perturb crystalline structures in 2D and 3D with a spatial Gaussian noise whose adimensional strength is α and analyse the statistical properties of the cells of the resulting Voronoi tessellations using an ensemble approach. In 2D we consider triangular, square and hexagonal regular lattices, resulting into hexagonal, square and triangular tessellations, respectively. In 3D we consider the simple cubic (SC, body-centred cubic (BCC, and face-centred cubic (FCC crystals, whose corresponding Voronoi cells are the cube, the truncated octahedron, and the rhombic dodecahedron, respectively. In 2D, for all values α>0, hexagons constitute the most common class of cells. Noise destroys the triangular and square tessellations, which are structurally unstable, as their topological properties are discontinuous in α=0. On the contrary, the honeycomb hexagonal tessellation is topologically stable and, experimentally, all Voronoi cells are hexagonal for small but finite noise with α<0.12. Basically, the same happens in the 3D case, where only the tessellation of the BCC crystal is topologically stable even against noise of small but finite intensity. In both 2D and 3D cases, already for a moderate amount of Gaussian noise (α>0.5, memory of the specific initial unperturbed state is lost, because the statistical properties of the three perturbed regular tessellations are indistinguishable. When α>2, results converge to those of Poisson-Voronoi tessellations. In 2D, while the isoperimetric ratio increases with noise for the perturbed hexagonal tessellation, for the perturbed triangular and square tessellations it is optimised for specific value of noise intensity
Low Power Compact Radio Galaxies at High Angular Resolution
Energy Technology Data Exchange (ETDEWEB)
Giroletti, Marcello; Giovannini, G.; /Bologna U. /Bologna, Ist. Radioastronomia; Taylor, G.B.; /KIPAC, Menlo Park /NRAO, Socorro
2005-06-30
We present sub-arcsecond resolution multi-frequency (8 and 22 GHz) VLA images of five low power compact (LPC) radio sources, and phase referenced VLBA images at 1.6 GHz of their nuclear regions. At the VLA resolution we resolve the structure and identify component positions and flux densities. The phase referenced VLBA data at 1.6 GHz reveals flat-spectrum, compact cores (down to a few milliJansky) in four of the five sources. The absolute astrometry provided by the phase referencing allows us to identify the center of activity on the VLA images. Moreover, these data reveal rich structures, including two-sided jets and secondary components. On the basis of the arcsecond scale structures and of the nuclear properties, we rule out the presence of strong relativistic effects in our LPCs, which must be intrinsically small (deprojected linear sizes {approx}< 10 kpc). Fits of continuous injection models reveal break frequencies in the GHz domain, and ages in the range 10{sup 5}-10{sup 7} yrs. In LPCs, the outermost edge may be advancing more slowly than in more powerful sources or could even be stationary; some LPCs might also have ceased their activity. In general, the properties of LPCs can be related to a number of reasons, including, but not limited to: youth, frustration, low kinematic power jets, and short-lived activity in the radio.
Directory of Open Access Journals (Sweden)
Borissova L.
2010-04-01
Full Text Available This study deals with the exact solution of Einstein's field equations for a sphere of incompressible liquid without the additional limitation initially introduced in 1916 by Schwarzschild, by which the space-time metric must have no singularities. The obtained exact solution is then applied to the Universe, the Sun, and the planets, by the assumption that these objects can be approximated as spheres of incompressible liquid. It is shown that gravitational collapse of such a sphere is permitted for an object whose characteristics (mass, density, and size are close to the Universe. Meanwhile, there is a spatial break associated with any of the mentioned stellar objects: the~break is determined as the approaching to infinity of one of the spatial components of the metric tensor. In particular, the break of the Sun's space meets the Asteroid strip, while Jupiter's space break meets the Asteroid strip from the outer side. Also, the space breaks of Mercury, Venus, Earth, and Mars are located inside the Asteroid strip (inside the Sun's space break.
The Solar System According to General Relativity: The Sun's Space Breaking Meets the Asteroid Strip
Directory of Open Access Journals (Sweden)
Borissova L.
2010-04-01
Full Text Available This study deals with the exact solution of Einstein’s field equations for a sphere of incompressible liquid without the additional limitation initially introduced in 1916 by Schwarzschild, by which the space-time metric must have no singularities. The ob- tained exact solution is then applied to the Universe, the Sun, and the planets, by the assumption that these objects can be approximated as spheres of incompressible liq- uid. It is shown that gravitational collapse of such a sphere is permitted for an object whose characteristics (mass, density, and size are close to the Universe. Meanwhile, there is a spatial break associated with any of the mentioned stellar objects: the break is determined as the approaching to infinity of one of the spatial components of the metric tensor. In particular, the break of the Sun’s space meets the Asteroid strip, while Jupiter’s space break meets the Asteroid strip from the outer side. Also, the space breaks of Mercury, Venus, Earth, and Mars are located inside the Asteroid strip (inside the Sun’s space break.
Exchange across the shelf break at high southern latitudes
Directory of Open Access Journals (Sweden)
J. M. Klinck
2010-01-01
Full Text Available Exchange of water across the Antarctic shelf break has considerable scientific and societal importance due to its effects on circulation and biology of the region, conversion of water masses as part of the global overturning circulation and basal melt of glacial ice and the consequent effect on sea level rise. The focus in this paper is the onshore transport of warm, oceanic Circumpolar Deep Water (CDW; export of dense water from these shelves is equally important, but has been the focus of other recent papers and will not be considered here. A variety of physical mechanisms are described which could play a role in this onshore flux. The relative importance of some processes are evaluated by simple calculations. A numerical model for the Ross Sea continental shelf is used as an example of a more comprehensive evaluation of the details of cross-shelf break exchange. In order for an ocean circulation model simulate these processes at high southern latitudes, it needs to have high spatial resolution, realistic geometry and bathymetry. Grid spacing smaller than the first baroclinic radius deformation (a few km is required to adequately represent the circulation. Because of flow-topography interactions, bathymetry needs to be represented at these same small scales. Atmospheric conditions used to force these circulation models also need to be known at a similar small spatial resolution (a few km in order to represent orographically controlled winds (coastal jets and katabatic winds. Significantly, time variability of surface winds strongly influences the structure of the mixed layer. Daily, if not more frequent, surface fluxes must be imposed for a realistic surface mixed layer. Sea ice and ice shelves are important components of the coastal circulation. Ice isolates the ocean from exchange with the atmosphere, especially in the winter. Melting and freezing of both sea ice and glacial ice influence salinity and thereby the character of shelf water
Exchange across the shelf break at high southern latitudes
Directory of Open Access Journals (Sweden)
J. M. Klinck
2010-05-01
Full Text Available Exchange of water across the Antarctic shelf break has considerable scientific and societal importance due to its effects on circulation and biology of the region, conversion of water masses as part of the global overturning circulation and basal melt of glacial ice and the consequent effect on sea level rise. The focus in this paper is the onshore transport of warm, oceanic Circumpolar Deep Water (CDW; export of dense water from these shelves is equally important, but has been the focus of other recent papers and will not be considered here. A variety of physical mechanisms are described which could play a role in this onshore flux. The relative importance of some processes are evaluated by simple calculations. A numerical model for the Ross Sea continental shelf is used as an example of a more comprehensive evaluation of the details of cross-shelf break exchange. In order for an ocean circulation model to simulate these processes at high southern latitudes, it needs to have high spatial resolution, realistic geometry and bathymetry. Grid spacing smaller than the first baroclinic radius of deformation (a few km is required to adequately represent the circulation. Because of flow-topography interactions, bathymetry needs to be represented at these same small scales. Atmospheric conditions used to force these circulation models also need to be known at a similar small spatial resolution (a few km in order to represent orographically controlled winds (coastal jets and katabatic winds. Significantly, time variability of surface winds strongly influences the structure of the mixed layer. Daily, if not more frequent, surface fluxes must be imposed for a realistic surface mixed layer. Sea ice and ice shelves are important components of the coastal circulation. Ice isolates the ocean from exchange with the atmosphere, especially in the winter. Melting and freezing of both sea ice and glacial ice influence salinity and thereby the character of shelf
Gorney, J E
1994-01-01
This article investigates the role of limit and limit setting within the psychoanalytic situation. Limit is understood to be a boundary between self and others, established as an interactional dimension of experience. Disorders of limit are here understood within the context of Winnicott's conception of the "anti-social tendency." Limit setting is proposed as a necessary and authentic response to the patient's acting out via holding and empathic responsiveness, viewed here as a form of boundary delineation. It is proposed that the patient attempts to repair his or her boundary problem through a seeking of secure limits within the analyst. The setting of secure and appropriate limits must arise from a working through of the analyst's own countertransference response to the patient. It is critical that this response be evoked by, and arise from, the immediate therapeutic interaction so that the patient can experience limit setting as simultaneously personal and authentic. PMID:7972580
Nuclear Physics Around the Unitarity Limit
König, Sebastian; Hammer, H -W; van Kolck, U
2016-01-01
We argue that many features of the structure of nuclei can be understood in the unitarity limit, where the two-nucleon S-waves have bound states at zero energy. In this limit, the only dimensionful parameter, related to the breaking of scale invariance to a discrete scaling symmetry, is set by the triton binding energy. For A <= 4 nucleons, we demonstrate that the spectrum can be obtained as a controlled perturbative expansion around the unitarity limit.
Stochastic properties of circuit breaking arcs
Rothhardt, L.
1985-09-01
Results are discussed for research work concerning the influence of cooling gas turbulence onto the breaker arc and the dielectric properties of the widely used cooling gases, air, and SF6, at elevated temperatures, both needed for numerical simulation of the breaking action.
Symmetry Breaking for Black-Scholes Equations
Institute of Scientific and Technical Information of China (English)
YANG Xuan-Liu; ZHANG Shun-Li; QU Chang-Zheng
2007-01-01
Black-Scholes equation is used to model stock option pricing. In this paper, optimal systems with one to four parameters of Lie point symmetries for Black-Scholes equation and its extension are obtained. Their symmetry breaking interaction associated with the optimal systems is also studied. As a result, symmetry reductions and corresponding solutions for the resulting equations are obtained.
Symmetry Breaking for Black-Scholes Equations
Yang, Xuan-Liu; Zhang, Shun-Li; Qu, Chang-Zheng
2007-06-01
Black-Scholes equation is used to model stock option pricing. In this paper, optimal systems with one to four parameters of Lie point symmetries for Black-Scholes equation and its extension are obtained. Their symmetry breaking interaction associated with the optimal systems is also studied. As a result, symmetry reductions and corresponding solutions for the resulting equations are obtained.
Symmetry Breaking for Black-Scholes Equations
International Nuclear Information System (INIS)
Black-Scholes equation is used to model stock option pricing. In this paper, optimal systems with one to four parameters of Lie point symmetries for Black-Scholes equation and its extension are obtained. Their symmetry breaking interaction associated with the optimal systems is also studied. As a result, symmetry reductions and corresponding solutions for the resulting equations are obtained.
Fragmentation in DNA double-strand breaks
International Nuclear Information System (INIS)
DNA double strand breaks are important lesions induced by irradiations. Random breakage model or quantification supported by this concept is suitable to analyze DNA double strand break data induced by low LET radiation, but deviation from random breakage model is more evident in high LET radiation data analysis. In this work we develop a new method, statistical fragmentation model, to analyze the fragmentation process of DNA double strand breaks. After charged particles enter the biological cell, they produce ionizations along their tracks, and transfer their energies to the cells and break the cellular DNA strands into fragments. The probable distribution of the fragments is obtained under the condition in which the entropy is maximum. Under the approximation E≅E0 + E1l + E2l2, the distribution functions are obtained as exp(αl + βl2). There are two components, the one proportional to exp(βl2), mainly contributes to the low mass fragment yields, the other component, proportional to exp(αl), decreases slowly as the mass of the fragments increases. Numerical solution of the constraint equations provides parameters α and β. Experimental data, especially when the energy deposition is higher, support the statistical fragmentation model. (authors)
DEFF Research Database (Denmark)
Alward, Randy; Carley, Kathleen M.; Madsen, Fredrik Huitfeldt;
2006-01-01
To help understand a network and its ability to continue operating when under attack, the break out group discussed issues that need to be considered when presenting network vulnerability information to an analyst, manager or commander in effective support of that person's "observe, orient, decide...
Weak mixing matrix under permutation symmetry breaking
International Nuclear Information System (INIS)
The two-Higgs-doublet extension of the standard electroweak model is considered. A permutation symmetry-breaking scheme is proposed and used to calculate the weak mixing matrix up to second order. The CP-violation factor J and the correction to Bjorken's approximation are then given. A special case is considered
Dynamical Symmetry Breaking in RN Quantum Gravity
Directory of Open Access Journals (Sweden)
A. T. Kotvytskiy
2011-01-01
Full Text Available We show that in the RN gravitation model, there is no dynamical symmetry breaking effect in the formalism of the Schwinger-Dyson equation (in flat background space-time. A general formula for the second variation of the gravitational action is obtained from the quantum corrections hμν (in arbitrary background metrics.
Physical implications of dynamical symmetry breaking
International Nuclear Information System (INIS)
Some model-independent physical implications of a class of hypercolorbased theories of dynamical symmetry-breaking are described and discussed. The role which e+e- colliders can play, in distinguishing between such theories and the canonical methodology, is underlined
Physician-patient communication: breaking bad news.
Fields, Scott A; Johnson, W Michael
2012-01-01
Physicians often struggle with how to manage the task of breaking bad news with patients. Moreover, the arduous nature of the task can contribute to physician detachment from the patient or an avoidance of breaking the news in a timely manner. A plan of action can only improve physician confidence in breaking bad news, and also make the task more manageable. Over a decade ago, Rabow and McPhee offered a strategy; the ABCDE plan, which provided a patient centered framework from which to deliver troubling news to patients and families. At the heart of this plan was the creation of a safe environment, the demonstration of timely communication skills, and the display of empathy on the physician's part. Careful consideration of the doctor's own reactions to death and dying also played an important role. A close review of the five tenets of this plan indicates the relevance of Rabow and McPhee's strategy today. The patient base in our nation and state continues to be older, on average, and physicians are faced with numerous patients who have terminal illness. A constructive plan with specific ideas for breaking bad news can help physicians effectively navigate this difficult task. PMID:22655433
Density Functional Simulation of a Breaking Nanowire
DEFF Research Database (Denmark)
Nakamura, A.; Brandbyge, Mads; Hansen, Lars Bruno;
1999-01-01
We study the deformation and breaking of an atomic-sized sodium wire using density functional simulations. The wire deforms through sudden atomic rearrangements and smoother atomic displacements. The conductance of the wire exhibits plateaus at integer values in units of 2e(2)/h corresponding to a...
Achromatic Breaks for Swift GRBs: Any Evidence?
S. Covino(INAF - Oss. Astronomico di Brera); Malesani, D.; Tagliaferri, G.; Vergani, S.D.; Chincarini, G.; Kann, D. A.; A. Moretti(Fermilab, Batavia, IL, USA); Stella, L.
2006-01-01
The availability of multi-wavelength high-quality data of gamma-ray burst afterglows in the Swift era, contrary to the expectations, did not allow us to fully confirm yet one of the most fundamental features of the standard afterglow picture: the presence of an achromatic break in the decaying light curve. We briefly review the most interesting cases identified so far.
The issue of supersymmetry breaking in strings
International Nuclear Information System (INIS)
We discuss the central role that supersymmetry plays in string models, both in spacetime and at the level of the string world-sheet. The problems associated with supersymmetry-breaking are reviewed together with some of the attempts to solve them, in the string as well as the field theory approach
Czech Academy of Sciences Publication Activity Database
Kočenda, Evžen; Hanousek, Jan
2012-01-01
Roč. 13, č. 2 (2012), s. 121-143. ISSN 1435-6104 R&D Projects: GA ČR GA402/09/1595 Institutional support: PRVOUK-P23 Keywords : break-up of firms * corporate performance * ownership changes Subject RIV: AH - Economics Impact factor: 0.588, year: 2012
Lifshitz-sector mediated SUSY breaking
International Nuclear Information System (INIS)
We propose a novel mechanism of SUSY breaking by coupling a Lorentz-invariant supersymmetric matter sector to non-supersymmetric gravitational interactions with Lifshitz scaling. The improved UV properties of Lifshitz propagators moderate the otherwise uncontrollable ultraviolet divergences induced by gravitational loops. This ensures that both the amount of induced Lorentz violation and SUSY breaking in the matter sector are controlled by ΛHL2/MP2, the ratio of the Hořava-Lifshitz cross-over scale ΛHL to the Planck scale MP. This ratio can be kept very small, providing a novel way of explicitly breaking supersymmetry without reintroducing fine-tuning. We illustrate our idea by considering a model of scalar gravity with Hořava-Lifshitz scaling coupled to a supersymmetric Wess-Zumino matter sector, in which we compute the two-loop SUSY breaking corrections to the masses of the light scalars due to the gravitational interactions and the heavy fields
Symmetry breaking and restoration in gauge theories
International Nuclear Information System (INIS)
A review is made of the utilization of the Higgs mechanism in spontaneous symmetry breaking. It is shown that such as ideas came from an analogy with the superconductivity phenomenological theory based on a Ginzburg-Landau lagrangean. The symmetry restoration through the temperature influence is studied. (L.C.)
RecA bundles mediate homology pairing between distant sisters during DNA break repair
Lesterlin, Christian; Ball, Graeme; Schermelleh, Lothar; Sherratt, David J.
2013-01-01
DNA double-strand break (DSB) repair by homologous recombination (HR) has evolved to maintain genetic integrity in all organisms 1 . Although many reactions that occur during HR are known 1-3 , it is unclear where, when and how they occur in cells is lacking. Here, by using conventional and super-resolution microscopy we describe the progression of DSB repair in live Escherichia coli. Specifically, we investigate whether HR can occur efficiently between distant sister loci that have segregate...
International Nuclear Information System (INIS)
With thirteen beam induced quenches and numerous Machine Development tests, the current knowledge of LHC magnets quench limits still contains a lot of unknowns. Various approaches to determine the quench limits are reviewed and results of the tests are presented. Attempt to reconstruct a coherent picture emerging from these results is taken. The available methods of computation of the quench levels are presented together with dedicated particle shower simulations which are necessary to understand the tests. The future experiments, needed to reach better understanding of quench limits as well as limits for the machine operation are investigated. The possible strategies to set BLM (Beam Loss Monitor) thresholds are discussed. (author)
Degeneracy Breaking for K2 Microlens Parallaxes
Gould, Andrew; Yee, Jennifer; Carey, Sean
2015-10-01
By adding Spitzer observations to microlensing targets being observed from Kepler and Earth, we will create the first interplanetary network of microlensing observatories. This 3-observatory configuration has the unique potential to break the famous 4-fold degeneracy for space-based microlensing parallaxes. This is crucial both for the interpretation of some individual events and to rigorously validate the statistical methods that are used when (as is usually the case) this special 3-observatory configuration is not possible. The Kepler K2 C9 microlensing campaign will monitor about 4 square degrees of the Bulge from 6 Apr to 29 Jun, with the aim of measuring microlens parallaxes. Spitzer can observe this K2 field from 18 Jun to 26 Jul. The 11-day overlap between the two campaigns will allow us to break the 4-fold degeneracy of about 50 microlensing events. Some of these events will be well-covered over the peak from K2, with Spitzer observations of the falling wing providing the necessary information to break the degeneracy in the K2-Earth parallax. Others will be the reverse, with K2 observations of the rising event breaking the degeneracy in Spitzer-Earth parallaxes (i.e., for events peaking during the Spitzer campaign). Breaking this degeneracy leads to a definitive measurement of the magnitude of the microlens parallax vector, which will enable measurements of the masses and distances of the lens systems, including events with planets that contribute to the ~12 needed to make a first measurement of the Galactic distribution of planets, binaries, and many single-lens events, some of which could be black holes, brown dwarfs, or other interesting objects. The distance distribution of the ensemble of lenses can serve as a probe of Galactic structure. All lightcurves will be reduced using our customized software and then made public (for unrestricted use), within two months of the completion of observations (as we did for our 2015 observations).
Record-breaking luminosity boosts discovery potential at Fermilab's Tevatron collider
Fermi National Accelerator Laboratory. Batavia
2006-01-01
The record-breaking performance of the Tevatron colklider at the Department of Energy's Fermi National Accelerator Laboratory is pushing tje search fpr dark matter, supersymmetric particles and extra dimensions to new limits. Repeatedly smashing peak luminosity records, the Tevatron has created record numbers of proton-antiproton collisions that provide the means to unveil the secrets of the universe
Aspects of semilocal BPS vortex in systems with Lorentz symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Villalobos, C.H.C.; Silva, J.M.H. da; Hott, M.B. [UNESP, Univ Estadual Paulista, Departamento de Fisica e Quimica, Guaratingueta, SP (Brazil); Belich, H. [Universidade Federal do Espi rito Santo (UFES), Departamento de Fisica e Quimica, Vitoria, ES (Brazil)
2014-03-15
The existence is shown of a static self-dual semilocal vortex configuration for the Maxwell-Higgs system with a Lorentz-violating CPT-even term. The dependence of the vorticity upper limit on the Lorentz-symmetry-breaking term is also investigated. (orig.)
Neutrino masses from SUSY breaking in radiative seesaw models
Energy Technology Data Exchange (ETDEWEB)
Figueiredo, Antonio J.R. [University of Lisbon, Centro de Fisica Teorica de Particulas (CFTP), Instituto Superior Tecnico, Lisbon (Portugal)
2015-03-01
Radiatively generated neutrino masses (m{sub ν}) are proportional to supersymmetry (SUSY) breaking, as a result of the SUSY non-renormalisation theorem. In this work, we investigate the space of SUSY radiative seesaw models with regard to their dependence on SUSY breaking (SUSY). In addition to contributions from sources of SUSY that are involved in electroweak symmetry breaking (SUSY{sub EWSB} contributions), and which are manifest from left angle F{sub H}{sup †} right angle = μ left angle anti H right angle ≠ 0 and left angle D right angle = g sum {sub H} left angle H{sup †} x {sub H} H right angle ≠ 0, radiatively generated m{sub ν} can also receive contributions from SUSY sources that are unrelated to EWSB (SUSY{sub EWS} contributions). We point out that recent literature overlooks pure-SUSY{sub EWSB} contributions (∝ μ/M) that can arise at the same order of perturbation theory as the leading order contribution from SUSY{sub EWS}. We show that there exist realistic radiative seesaw models in which the leading order contribution to m{sub ν} is proportional to SUSY{sub EWS}. To our knowledge no model with such a feature exists in the literature. We give a complete description of the simplest model topologies and their leading dependence on SUSY. We show that in one-loop realisations LLHH operators are suppressed by at least μ m{sub soft}/M{sup 3} or m{sub soft}{sup 2}/M{sup 3}. We construct a model example based on a oneloop type-II seesaw. An interesting aspect of these models lies in the fact that the scale of soft-SUSY effects generating the leading order m{sub ν} can be quite small without conflicting with lower limits on the mass of new particles. (orig.)
Neutrino masses from SUSY breaking in radiative seesaw models
International Nuclear Information System (INIS)
Radiatively generated neutrino masses (mν) are proportional to supersymmetry (SUSY) breaking, as a result of the SUSY non-renormalisation theorem. In this work, we investigate the space of SUSY radiative seesaw models with regard to their dependence on SUSY breaking (SUSY). In addition to contributions from sources of SUSY that are involved in electroweak symmetry breaking (SUSYEWSB contributions), and which are manifest from left angle FH† right angle = μ left angle anti H right angle ≠ 0 and left angle D right angle = g sum H left angle H† x H H right angle ≠ 0, radiatively generated mν can also receive contributions from SUSY sources that are unrelated to EWSB (SUSYEWS contributions). We point out that recent literature overlooks pure-SUSYEWSB contributions (∝ μ/M) that can arise at the same order of perturbation theory as the leading order contribution from SUSYEWS. We show that there exist realistic radiative seesaw models in which the leading order contribution to mν is proportional to SUSYEWS. To our knowledge no model with such a feature exists in the literature. We give a complete description of the simplest model topologies and their leading dependence on SUSY. We show that in one-loop realisations LLHH operators are suppressed by at least μ msoft/M3 or msoft2/M3. We construct a model example based on a oneloop type-II seesaw. An interesting aspect of these models lies in the fact that the scale of soft-SUSY effects generating the leading order mν can be quite small without conflicting with lower limits on the mass of new particles. (orig.)
Neutrino masses from SUSY breaking in radiative seesaw models
Figueiredo, António J. R.
2015-03-01
Radiatively generated neutrino masses () are proportional to supersymmetry (SUSY) breaking, as a result of the SUSY non-renormalisation theorem. In this work, we investigate the space of SUSY radiative seesaw models with regard to their dependence on SUSY breaking ([InlineEquation not available: see fulltext.]). In addition to contributions from sources of [InlineEquation not available: see fulltext.] that are involved in electroweak symmetry breaking ([InlineEquation not available: see fulltext.] contributions), and which are manifest from and , radiatively generated can also receive contributions from [InlineEquation not available: see fulltext.] sources that are unrelated to EWSB ([InlineEquation not available: see fulltext.] contributions). We point out that recent literature overlooks pure-[InlineEquation not available: see fulltext.] contributions () that can arise at the same order of perturbation theory as the leading order contribution from [InlineEquation not available: see fulltext.]. We show that there exist realistic radiative seesaw models in which the leading order contribution to is proportional to [InlineEquation not available: see fulltext.]. To our knowledge no model with such a feature exists in the literature. We give a complete description of the simplest model topologies and their leading dependence on [InlineEquation not available: see fulltext.]. We show that in one-loop realisations operators are suppressed by at least or . We construct a model example based on a one-loop type-II seesaw. An interesting aspect of these models lies in the fact that the scale of soft-[InlineEquation not available: see fulltext.] effects generating the leading order can be quite small without conflicting with lower limits on the mass of new particles.
DEFF Research Database (Denmark)
Nielsen, Morten Ebbe Juul
2006-01-01
Article Concerning the prospect of a kind of limited neutrality in place of the standard liberal egalitarian "neutrality of justification."......Article Concerning the prospect of a kind of limited neutrality in place of the standard liberal egalitarian "neutrality of justification."...
International Nuclear Information System (INIS)
The dose limit is defined to be the level of harmfulness which must not be exceeded, so that an activity can be exercised in a regular manner without running a risk unacceptable to man and the society. The paper examines the effects of radiation categorised into stochastic and non-stochastic. Dose limits for workers and the public are discussed
Campbell, Joel F; Lin, Bing; Nehrir, Amin R; Harrison, F Wallace; Obland, Michael D
2014-12-15
An interpolation method is described for range measurements of high precision altimetry with repeating intensity modulated continuous wave (IM-CW) lidar waveforms using binary phase shift keying (BPSK), where the range profile is determined by means of a cross-correlation between the digital form of the transmitted signal and the digitized return signal collected by the lidar receiver. This method uses reordering of the array elements in the frequency domain to convert a repeating synthetic pulse signal to single highly interpolated pulse. This is then enhanced further using Richardson-Lucy deconvolution to greatly enhance the resolution of the pulse. We show the sampling resolution and pulse width can be enhanced by about two orders of magnitude using the signal processing algorithms presented, thus breaking the fundamental resolution limit for BPSK modulation of a particular bandwidth and bit rate. We demonstrate the usefulness of this technique for determining cloud and tree canopy thicknesses far beyond this fundamental limit in a lidar not designed for this purpose. PMID:25503046
Self-feeding MUSE: a robust method for high resolution diffusion imaging using interleaved EPI.
Zhang, Zhe; Huang, Feng; Ma, Xiaodong; Xie, Sheng; Guo, Hua
2015-01-15
Single-shot echo planar imaging (EPI) with parallel imaging techniques has been well established as the most popular method for clinical diffusion imaging, due to its fast acquisition and motion insensitivity. However, this approach is limited by the relatively low spatial resolution and image distortion. Interleaved EPI is able to break the limitations but the phase variations among different shots must be considered for artifact suppression. The introduction of multiplexed sensitivity-encoding (MUSE) can address the phase issue using sensitivity encoding (SENSE) for self-navigation of each interleave. However, MUSE has suboptimal results when the number of shots is high. To achieve higher spatial resolution and lower geometric distortion, we introduce two new schemes into the MUSE framework: 1) a self-feeding mechanism is adopted by using prior information regularized SENSE in order to obtain reliable phase estimation; and 2) retrospective motion detection and data rejection strategies are performed to exclude unusable data corrupted by severe pulsatile motions. The proposed method is named self-feeding MUSE (SF-MUSE). Experiments on healthy volunteers demonstrate that this new SF-MUSE approach provides more accurate motion-induced phase estimation and fewer artifacts caused by data corruption when compared with the original MUSE method. SF-MUSE is a robust method for high resolution diffusion imaging and suitable for practical applications with reasonable scan time. PMID:25451470
Energy Technology Data Exchange (ETDEWEB)
Turner, W.; Welch, S.; DiPietro, E.; Cash, T.; McClure, C.; Needham, L.; Patterson, D. [CDC/ATSDR, Atlanta, GA (United States)
2004-09-15
The recent worldwide decline in background serum levels of polychlorinated dibenzo-p-dioxins, furans, and coplanar biphenyls (PCDDs/PCDFs/cPCBs) is unquestionably an important finding. However, as serum levels continue to diminish, our analytical methods for measuring these toxicants will continue to be ''pushed to their limit''. In a previous article, we investigated some of the variables that influence the quantification of ''ultra-trace'' (fg/g) concentrations of PCDDs/PCDFs and cPCBs in human serum. In this report, we continue to explore parameters that can affect the determination of the ''true'' detection limit of our method (MDL), using both analytical standards and matrix-based samples.
Verma, Prabal Singh; Sengupta, Sudip; Kaw, Predhiman
2012-07-01
A one-dimensional particle in cell simulation of large amplitude plasma oscillations is carried out to explore the physics beyond wave breaking in a cold homogeneous unmagnetized plasma. It is shown that after wave breaking, all energy of the plasma oscillation does not end up as random kinetic energy of particles, but some fraction, which is decided by Coffey's wave breaking limit in warm plasma, always remains with two oppositely propagating coherent Bernstein-Greene-Kruskal like modes with supporting trapped particle distributions. The randomized energy distribution of untrapped particles is found to be characteristically non-Maxwellian with a preponderance of energetic particles.
International Nuclear Information System (INIS)
Mosquitofish (Gambusia affines) were collected from a small pond on the US DOE reservation that is contaminated with 137Cs, 90Sr and other radionuclides. Fish from non-contaminated populations were also collected. DNA was isolated from both the liver and the blood and examined for DNA single- and double-strand breaks by gel electrophoresis. In general, both single- and double-strand DNA breaks were more prevalent in fish from radionuclide-contaminated sites than from uncontaminated sites. In addition, there were more double-strand than single-strand breaks in DNA from contaminated fish, and more strand breaks in blood cell than in liver DNA. Also, fecundity and number of malformed embryos were determined in fish from all sites. It was found that, for fish from the contaminated site, the number of DNA strand breaks was negatively correlated with fecundity, and that females with malformed embryos in their broods had more DNA strand breaks than did females with no malformed embryos. These findings have implications for both ecological risk assessment and evolutionary ecology
Multicritical Symmetry Breaking and Naturalness of Slow Nambu-Goldstone Bosons
Griffin, Tom; Horava, Petr; Yan, Ziqi
2013-01-01
We investigate spontaneous global symmetry breaking in the absence of Lorentz invariance, and study technical Naturalness of Nambu-Goldstone (NG) modes whose dispersion relation exhibits a hierarchy of multicritical phenomena with Lifshitz scaling and dynamical exponents $z>1$. For example, we find NG modes with a technically natural quadratic dispersion relation which do not break time reversal symmetry and are associated with a single broken symmetry generator, not a pair. The mechanism is protected by an enhanced `polynomial shift' symmetry in the free-field limit.
Free-surface Flow After a Dam break: A Comparative Study.
Colicchio, Giuseppina; Colagrossi, Andrea; Greco, Marilena; Landrini, Maurizio
2001-01-01
The water flow after the sudden break of a dam is schematically represented as an initially rectangular column of luid supported by a horizontal bottom, limited by a wall on one side and free to evolve on the other one. The flow is characterized by the development of a toungue of liquid quickly spreading along the horizontal boundary without any sign of free-surface breaking. This problem has been widely investigated numerically because, besides its practical meaning, it is a clean test case ...
Semiclassical treatment of symmetry breaking and bifurcations in a non-integrable potential
Koliesnik, M V; Magner, A G; Arita, K; Brack, M
2014-01-01
We have derived an analytical trace formula for the level density of the H\\'enon-Heiles potential using the improved stationary phase method, based on extensions of Gutzwiller's semiclassical path integral approach. This trace formula has the correct limit to the standard Gutzwiller trace formula for the isolated periodic orbits far from all (critical) symmetry-breaking points. It continuously joins all critical points at which an enhancement of the semiclassical amplitudes occurs. We found a good agreement between the semi- classical and the quantum oscillating level densities for the gross shell structures and for the energy shell corrections, solving the symmetry breaking problem at small energies.
International Nuclear Information System (INIS)
We report large effects of Parisi replica permutation symmetry breaking (RPSB) on elementary excitations of fermionic systems with frustrated magnetic interactions. The electronic density of states is obtained exactly in the zero temperature limit for (K = 1)- step RPSB together with relations for arbitrary breaking K, which lead to a new fermionic and dynamical Parisi solution at K = ∞. The Ward identity for charge conservation indicates RPSB-effects on the conductivity in metallic quantum spin glasses. This implies that RPSB is essential for any fermionic system showing spin glass sections within its phase diagram. An astonishing similarity with a neural network problem is also observed. (author)
Alves, S. G.; Braga, F. L.; Martins, M. L.
2007-10-01
Electrochemical ferromagnetic deposits grown under a planar magnetic field exhibit a striking morphological symmetry breaking. The present paper demonstrate through two-dimensional off-lattice simulations of an extended diffusion-limited aggregation (DLA) model that the competition between magnetic dipolar interactions and electric forces can impose locally the experimentally observed angle selection in a two-dimensional extended DLA model. The long-range correlations in the orientation of dipoles interacting with the applied and dipolar fields preserve this order over a macroscopic scale. Hence, the magnetic dipolar interactions alone cannot impose the field-induced symmetry breaking observed in ferromagnetic electrochemical deposition (ECD).
Efon, E.; Lenouo, A.; Monkam, D.; Manatsa, D.
2016-07-01
High resolution of daily rainfall dataset from the Tropical Rainfall Measuring Mission (TRMM) was used to identify active and break cloud formation periods. The clouds were characterized based on CloudSat-CALIPSO satellite images over West Africa during the summer monsoon during the period 2006-2010. The active and break periods are defined as the periods during the peak monsoon months of June to August when the normalized anomaly of rainfall over the monsoon core zone is greater than 0.9 or less than -0.9 respectively, provided the criteria is satisfied for at least three consecutive days. It is found that about 90% of the break period and 66.7% of the active spells lasted 3-4 days. Active spells lasting duration of about a week were observed while no break spell had such a long span. Cloud macrophysical (cloud base height (CBH), cloud top height (CTH) and cloud geometric depth (∆H), microphysical (cloud liquid water content, (LWC), liquid number concentration (LNC), liquid effective radius, ice water content (IWC), ice number concentration (INC) and ice effective radius) and radiative (heating rate properties) over South Central West Africa (5-15°N; 15°W-10°E) during the active and break spells were also analyzed. High-level clouds are more predominant during the break periods compared to the active periods. Active spells have lower INC compared to the break spells. Liquid water clouds are observed to have more radiative forcing during the active than break periods while ice phase clouds bring more cooling effect during the break spells compared to the active spells.
Parity-time symmetry breaking in magnetic systems
Galda, Alexey; Vinokur, Valerii M.
2016-07-01
The understanding of out-of-equilibrium physics, especially dynamic instabilities and dynamic phase transitions, is one of the major challenges of contemporary science, spanning the broadest wealth of research areas that range from quantum optics to living organisms. Focusing on nonequilibrium dynamics of an open dissipative spin system, we introduce a non-Hermitian Hamiltonian approach, in which non-Hermiticity reflects dissipation and deviation from equilibrium. The imaginary part of the proposed spin Hamiltonian describes the effects of Gilbert damping and applied Slonczewski spin-transfer torque. In the classical limit, our approach reproduces Landau-Lifshitz-Gilbert-Slonczewski dynamics of a large macrospin. We reveal the spin-transfer torque-driven parity-time symmetry-breaking phase transition corresponding to a transition from precessional to exponentially damped spin dynamics. Micromagnetic simulations for nanoscale ferromagnetic disks demonstrate the predicted effect. Our findings can pave the way to a general quantitative description of out-of-equilibrium phase transitions driven by spontaneous parity-time symmetry breaking.
Breaking seed dormancy of three orthodox Mediterranean Rosaceae species.
Iakovoglou, Valasia; Radoglou, Kalliopi
2015-03-01
Biodiversity levels could be enhanced when regenerating a site by seed-derived seedlings. However, seed dormancy poses limitations for many species. As a result, nurseries either produce seedlings from species where dormancy is not an obstacle, or they propagate through cuttings with the risk of decreasing the genetic diversity within and among species at the regenerated sites. In the present study, breaking of seed dormancy was investigated in valuable Mediterranean species of Prunus avium, Prunus spinosa and Rosa canina Specifically, in order to break dormancy, seeds of those species were warm-, cold-stratified and chemically treated. Based on the results, maximum germination for P. avium was 12% when seeds were warm stratified for four weeks altered with eight weeks of cold stratification. For P. spinosa, maximum percent germination was 26% when seeds were warm stratified for two weeks and continuously altered for eight weeks of cold stratification. Finally, for R. canina maximum percent germination was 40% under four weeks of warm stratification altered with twenty weeks of cold stratification, when seeds were pretreated with H2SO4 for 15 min. A maximum of twelve weeks of cold stratification for P. avium, P. spinosa and 20 weeks for R. canina provided almost zero percent germination. The results indicated that all three species experienced intense dormancy levels suggesting that those species need to be treated properly prior to sowing. Nonetheless, additional experiments are needed to achieve greater germination percentage of highly valuable species in orderto encourage seed derived seedling production. PMID:25895254
Pulsar Emission above the Spectral Break - A Stacked Approach
McCann, Andrew
2015-01-01
NASA's Fermi space telescope has provided us with a bountiful new population of gamma-ray sources following its discovery of 150 new gamma-ray pulsars. One common feature exhibited by all of these pulsars is the form of their spectral energy distribution, which can be described by a power law followed by a spectral break occurring between $\\sim$1 and $\\sim$8 GeV. The common wisdom is that the break is followed by an exponential cut-off driven by radiation/reaction-limited curvature emission. The discovery of pulsed gamma rays from the Crab pulsar, the only pulsar so far detected at very high energies (E$>$100GeV), contradicts this "cutoff" picture. Here we present a new stacked analysis with an average of 4.2 years of data on 115 pulsars published in the 2nd LAT catalog of pulsars. This analysis is sensitive to low-level $\\sim$100 GeV emission which cannot be resolved in individual pulsars but can be detected from an ensemble.
PIRT for large break LOCA mass and energy release calculations
International Nuclear Information System (INIS)
Pipe ruptures in the primary reactor coolant system are postulated as part of the design basis for containment integrity and equipment qualification validation for Nuclear Power Plants. The mass and energy (M and E) released from a postulated large break LOCA is the primary forcing function used as input for determining the containment response to a LOCA. The current Westinghouse LOCA M and E release calculation methodology was developed in the 1970's, when computing power was limited. The method is somewhat deterministic and includes several simplified, conservative modeling assumptions. Westinghouse is developing a mechanistic LOCA M and E release accident analysis calculation to more realistically, yet conservatively, model the containment response. A good definition of the key LOCA phenomena is needed as part of this development process. The purpose of this document is to discuss the development of the Phenomena Identification and Ranking Table (PIRT) for large break LOCA M and E release calculations. This paper lists the high ranked phenomena from the PIRT, along with the Transient Phase, and Projected Source of Validating Data. This table is the expert opinion of the selected team and is based upon and is an extension of NRC large LOCA PIRT, which was developed as part of the best estimate (BE) LOCA program for ECCS design basis analysis, the Westinghouse large LOCA PIRT developed for the WCOBRA-TRAC BE LOCA model development program, and the Westinghouse large LOCA PIRT, which was developed to address new components as part of the plant development programs
Fractional Branes and Dynamical Supersymmetry Breaking
Franco, S; Saad, F; Uranga, Angel M; Franco, Sebastian; Hanany, Amihay; Saad, Fouad; Uranga, Angel M.
2006-01-01
We study the dynamics of fractional branes at toric singularities, including cones over del Pezzo surfaces and the recently constructed Y^{p,q} theories. We find that generically the field theories on such fractional branes show dynamical supersymmetry breaking, due to the appearance of non-perturbative superpotentials. In special cases, one recovers the known cases of supersymmetric infrared behaviors, associated to SYM confinement (mapped to complex deformations of the dual geometries, in the gauge/string correspondence sense) or N=2 fractional branes. In the supersymmetry breaking cases, when the dynamics of closed string moduli at the singularity is included, the theories show a runaway behavior (involving moduli such as FI terms or equivalently dibaryonic operators), rather than stable non-supersymmetric minima. We comment on the implications of this gauge theory behavior for the infrared smoothing of the dual warped throat solutions with 3-form fluxes, describing duality cascades ending in such field th...
Symmetry breaking in non conservative systems
Martínez-Pérez, N E
2016-01-01
We apply Noether's theorem to show how the invariances of conservative systems are broken for nonconservative systems, in the variational formulation of Galley. This formulation considers a conservative action, extended by the inclusion of a time reversed sector and a nonconservative generalized potential. We assume that this potential is invariant under the symmetries of the initial conservative system. The breaking occurs because the time reversed sector requires inverse symmetry transformations, under which the nonconservative potential is not invariant. The resulting violation of the conservation laws is consistent with the equations of motion. We generalize this formulation for fermionic and sypersymmetric systems. In the case of a supersymmetric oscillator, the effect of damping is that the bosonic and fermionic components become different frequencies. Considering that initially the nonconservative action is invariant under supersymmetry, and that the breaking is associated to an instability, this resul...
The Radiative Z2 Breaking Twin Higgs
Yu, Jiang-Hao
2016-01-01
In twin Higgs model, the Higgs boson mass is protected by a $Z_2$ symmetry. The $Z_2$ symmetry needs to be broken either explicitly or spontaneously to obtain misalignment between electroweak and new physics vacua. We propose a novel $Z_2$ breaking mechanism, in which the $Z_2$ is spontaneously broken by radiative corrections to the Higgs potential. Two twin Higgses with different vacua are needed, and vacuum misalignment is realized by opposite but comparable contributions from gauge and Yukawa interactions to the potential. Due to fully radiative symmetry breaking, the Higgs sector is completely determined by twin Higgs vacuum, Yukawa and gauge couplings. There are eight pseudo-Goldstone bosons: the Higgs boson, inert doublet Higgs, and three twin scalars. We show the 125 GeV Higgs mass and constraints from Higgs coupling measurements could be satisfied.
Mechanics of breaking coal by water jet
Energy Technology Data Exchange (ETDEWEB)
Chang, Z.; Xi, B.; Zhao, Y.; Zhao, L. [Taiyuan University of Technology, Taiyuan (China)
2008-09-15
It is presumed that the elastic modulus and compressive strength of inhomogeneous rock conform to the Weibull distribution. The methods of breaking inhomogeneous rock by water jet and the threshold pressure of the water jet were deduced using percolation theory. Continuous drilling in the inhomogeneous coal by water jet was numerically simulated by the finite element method and an experiment of breaking coal by water jet was carried out. The study indicated that under the pressure of water jets, the low strength cells in inhomogeneous rock are first destroyed and a crack is created. The effect of a water wedge occurring by the water jet entering the crack space produces a tensile stress concentration at the tip of a crack, so cracks expand rapidly and converge gradually. Eventually the rock is fragmented and a cracked pit forms. The length of a crack in coal caused by a water jet at 60 MPa is over 0.5 m. 8 refs., 6 figs.
Phenomenological implications of low energy supersymmetry breaking
International Nuclear Information System (INIS)
The experimental signatures for low energy supersymmetry breaking are presented. The lightest standard model superpartner is unstable and decays to its partner plus a Goldstino, G. For a supersymmetry breaking scale below a few 1000 TeV this decay can take place within a detector, leading to very distinctive signatures. If a neutralino is the lightest standard model superpartner it decays by χ01→γ + G, and if kinematically accessible by χ01 → (Z0, h0, H0, A0) + G. These decays can give rise to displaced vertices. Alternately, if a slepton is the lightest standard model superpartner it decays by l→l + G. This can be seen as a greater than minimum ionizing charged particle track, possibly with a kink to a minimum ionizing track. (orig.)
Electroweak symmetry breaking: Higgs/whatever
International Nuclear Information System (INIS)
In the first of these two lectures the Higgs mechanism is reviewed in its most general form, which does not necessarily require the existence of Higgs bosons. The general consequences of the hypothesis that electroweak symmetry breaking is due to the Higgs mechanism are deduced just from gauge invariance and unitarity. In the second lecture the general properties are illustrated with three specific models: the Weinberg-Salam model, its minimal supersymmetric extension, and technicolor. The second lecture concludes with a discussion of the experiment signals for strong WW scattering, whose presence or absence will allow us to determine whether the symmetry breaking sector lies above or below 1 TeV. 57 refs
Rotation Breaking Induced by ELMs on EAST
DEFF Research Database (Denmark)
Xiong, H.; Xu, G.; Sun, Y.;
Spontaneous rotation has been observed in LHCD H-mode plasmas with type III ELMs (edge localized modes) on EAST, and it revealed that type III ELMs can induce the loss of both core and edge toroidal rotation. Here we work on the breaking mechanism during the ELMs. Several large tokamaks have...... of magnetic surface, thus generate NTV (neoclassical toroidal viscosity) torque that affects toroidal rotation. We adopt 1cm maximum edge magnetic surface displacement from experimental observation, and our calculation shows that the edge torque is about 0.35 N/m2, and the core very small. The...... expected angular momentum density change is about 3.8 N/m2, nearly 10 times larger than the calculation. Previous work on EAST has suggested that there is a mechanism at the edge that breaks the rotation, while the core rotation change is mostly likely related with momentum transport to the edge. In other...
Boost Breaking in the EFT of Inflation
Delacretaz, Luca V; Senatore, Leonardo
2015-01-01
If time-translations are spontaneously broken, so are boosts. This symmetry breaking pattern can be non-linearly realized by either just the Goldstone boson of time translations, or by four Goldstone bosons associated with time translations and boosts. In this paper we extend the Effective Field Theory of Multifield Inflation to consider the case in which the additional Goldstone bosons associated with boosts are light and coupled to the Goldstone boson of time translations. The symmetry breaking pattern forces a coupling to curvature so that the mass of the additional Goldstone bosons is predicted to be equal to $\\sqrt{2}H$ in the vast majority of the parameter space where they are light. This pattern therefore offers a natural way of generating self-interacting particles with Hubble mass during inflation. After constructing the general effective Lagrangian, we study how these particles mix and interact with the curvature fluctuations, generating potentially detectable non-Gaussian signals.
Lima, V; Lacroix, D; Blumenfeld, Y; Bourgeois, C; Chabot, M; Chomaz, Ph; Désesquelles, P; Duflot, V; Duprat, J; Fallot, M; Frascaria, N; Grévy, S; Guillemaud-Müller, D; Roussel-Chomaz, P; Savajols, H; Sorlin, O
2007-01-01
The break-up of 11Be was studied at 41AMeV using a secondary beam of 11Be from the GANIL facility on a 48Ti target by measuring correlations between the 10Be core, the emitted neutrons and gamma rays. The nuclear break-up leading to the emission of a neutron at large angle in the laboratory frame is identified with the towing mode through its characteristic n-fragment correlation. The experimental spectra are compared with a model where the time dependent Schrodinger equation (TDSE) is solved for the neutron initially in the 11 Be. A good agreement is found between experiment and theory for the shapes of neutron experimental energies and angular distributions. The spectroscopic factor of the 2s orbital is tentatively extracted to be 0.46+-0.15. The neutron emission from the 1p and 1d orbitals is also studied.
Isospin breaking in octet baryon mass splittings
Energy Technology Data Exchange (ETDEWEB)
Horsley, R. [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Najjar, J. [Regensburg Univ. (Germany). Institut fuer Theoretische Physik; Nakamura, Y. [RIKEN Advanced Institute for Computational Science, Kobe, Hyogo (Japan); Pleiter, D. [Forschungszentrum Juelich (Germany). Juelich Supercomputer Centre; Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Division; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Zanotti, J.M. [Adelaide Univ., SA (Australia). CSSM, School of Chemistry and Physics
2012-06-15
Using an SU(3) flavour symmetry breaking expansion in the quark mass, we determine the QCD component of the nucleon, Sigma and Xi mass splittings of the baryon octet due to up-down (and strange) quark mass differences in terms of the kaon mass splitting. Provided the average quark mass is kept constant, the expansion coefficients in our procedure can be determined from computationally cheaper simulations with mass degenerate sea quarks and partially quenched valence quarks. Both the linear and quadratic terms in the SU(3) flavour symmetry breaking expansion are considered; it is found that the quadratic terms only change the result by a few percent, indicating that the expansion is highly convergent.
Isospin breaking in octet baryon mass splittings
International Nuclear Information System (INIS)
Using an SU(3) flavour symmetry breaking expansion in the quark mass, we determine the QCD component of the nucleon, Sigma and Xi mass splittings of the baryon octet due to up-down (and strange) quark mass differences in terms of the kaon mass splitting. Provided the average quark mass is kept constant, the expansion coefficients in our procedure can be determined from computationally cheaper simulations with mass degenerate sea quarks and partially quenched valence quarks. Both the linear and quadratic terms in the SU(3) flavour symmetry breaking expansion are considered; it is found that the quadratic terms only change the result by a few percent, indicating that the expansion is highly convergent.
Symmetry Breaking in Neuroevolution: A Technical Report
Urfalioglu, Onay
2011-01-01
Artificial Neural Networks (ANN) comprise important symmetry properties, which can influence the performance of Monte Carlo methods in Neuroevolution. The problem of the symmetries is also known as the competing conventions problem or simply as the permutation problem. In the literature, symmetries are mainly addressed in Genetic Algoritm based approaches. However, investigations in this direction based on other Evolutionary Algorithms (EA) are rare or missing. Furthermore, there are different and contradictionary reports on the efficacy of symmetry breaking. By using a novel viewpoint, we offer a possible explanation for this issue. As a result, we show that a strategy which is invariant to the global optimum can only be successfull on certain problems, whereas it must fail to improve the global convergence on others. We introduce the \\emph{Minimum Global Optimum Proximity} principle as a generalized and adaptive strategy to symmetry breaking, which depends on the location of the global optimum. We apply the...
DEFF Research Database (Denmark)
Hendricks, Vincent Fella; Symons, John
2011-01-01
Skeptics argue that the acquisition of knowledge is impossible given the standing possibility of error. We present the limiting convergence strategy for responding to skepticism and discuss the relationship between conceivable error and an agent’s knowledge in the limit. We argue that the skeptic...... must demonstrate that agents are operating with a bad method or are in an epistemically cursed world. Such demonstration involves a significant step beyond conceivability and commits the skeptic to potentially convergent inquiry...
Testing Chiral Symmetry Breaking at DAPHNE
M. R. Pennington
1996-01-01
The spontaneous breakdown of the chiral symmetry of the QCD Lagrangian ensures that $\\pi\\pi$ interactions are weak at low energies. How weak depends on the nature of explicit symmetry breaking. Measurements of $K_{e4}$ decays at DA$\\Phi$NE will provide a unique insight into this mechanism and test whether the $q{\\overline q}$--condensate is large or small.
Music and Video Gaming during Breaks
Liu, Shuyan; Schad, Daniel J.; Kuschpel, Maxim S.; Michael A Rapp; Heinz, Andreas
2016-01-01
Different systems for habitual versus goal-directed control are thought to underlie human decision-making. Working memory is known to shape these decision-making systems and their interplay, and is known to support goal-directed decision making even under stress. Here, we investigated if and how decision systems are differentially influenced by breaks filled with diverse everyday life activities known to modulate working memory performance. We used a within-subject design where young adult...
Supersymmetry breaking made easy, viable, and generic
Murayama, Hitoshi
2007-01-01
The kind of supersymmetry that can be discovered at the LHC must be very much flavor-blind, which used to require very special intelligently designed models of supersymmetry breaking. This led to the pessimism for some in the community that it is not likely for the LHC to discover supersymmetry. I point out that this is not so, because a garden-variety supersymmetric theories actually can do this job.
The Experimental Investigation of Supersymmetry Breaking
Peskin, Michael E.
1996-01-01
If Nature is supersymmetric at the weak interaction scale, what can we hope to learn from experiments on supersymmetric particles? The most mysterious aspect of phenomenological supersymmetry is the mechanism of spontaneous supersymmetry breaking. This mechanism ties the observable pattern of supersymmetric particle masses to aspects of the underlying unified theory at very small distance scales. In this article, I will discuss a systematic experimental program to determine the mechanism of s...
Numerical simulation of 3D breaking waves
Fraunie, Philippe; Golay, Frederic
2015-04-01
Numerical methods dealing with two phase flows basically can be classified in two ways : the "interface tracking" methods when the two phases are resolved separately including boundary conditions fixed at the interface and the "interface capturing" methods when a single flow is considered with variable density. Physical and numerical properties of the two approaches are discussed, based on some numerical experiments performed concerning 3D breaking waves. Acknowledgements : This research was supported by the Modtercom program of Region PACA.
Dynamical symmetry breaking in quantum field theories
Miransky, Vladimir A
1993-01-01
The phenomenon of dynamical symmetry breaking (DSB) in quantum field theory is discussed in a detailed and comprehensive way. The deep connection between this phenomenon in condensed matter physics and particle physics is emphasized. The realizations of DSB in such realistic theories as quantum chromodynamics and electroweak theory are considered. Issues intimately connected with DSB such as critical phenomenona and effective lagrangian approach are also discussed.
Spontaneous symmetry breaking of SU(n)
International Nuclear Information System (INIS)
The spontaneous symmetry breaking pattern for the gauge group SU(n) is found by studying the absolute minimum of the Higgs potential, chosen as a polynomial of degree 4 of one adjoint and one fundamental representation. SU(n) may be broken into SU(n - 1) or SU(h) x SU(n - 1 - h) x U(1) (h = 1,...n - 2), depending on the values of the parameters, but without any assumption on their smallness. (orig.)
Wave breaking in tapered holey fibers
Institute of Scientific and Technical Information of China (English)
Shuguang Li; Lei Zhang; Bo Fu; Yi Zheng; Ying Han; Xingtao Zhao
2011-01-01
We numerically study the propagation of 1-ps laser pulse in three tapered holey fibers (THFs). The curvature indices of the concave, linear, and convex tapers are 2.0, 1.0, and 0.5, respectively. The central wavelength, located in the normal dispersion regime, is 800 nm. The nonlinear coefficient of the THFs increases from the initial 0.095 m-1· W-1 to the final 0.349 m-l·W-1. Wave breaking accompanied by oscillatory structures occurs near pulse edges, and sidelobes appear in the pulse spectrum. With the increase in propagation distance z, the pulse shape becomes broader and the pulse spectrum flattens. A concave THF is advantageous to the generation of wave breaking and enables easier achievement of super fiat spectra at short lengths.%@@ We numerically study the propagation of 1-ps laser pulse in three tapered holey fibers (THFs).The curvature indices of the concave, linear, and convex tapers are 2.0, 1.0, and 0.5, respectively.The central wavelength, located in the normal dispersion regime, is 800 nm.The nonlinear coefficient of the THFs increases from the initial 0.095 m-1.W-1 to the final 0.349 m-1.W-1.Wave breaking accompanied by oscillatory structures occurs near pulse edges, and sidelobes appear in the pulse spectrum.With the increase in propagation distance z, the pulse shape becomes broader and the pulse spectrum flattens.A concave THF is advantageous to the generation of wave breaking and enables easier achievement of super flat spectra at short lengths.
Soft branes in supersymmetry-breaking backgrounds
McGuirk, Paul; Shiu, Gary; Ye, Fang
2012-01-01
We revisit the analysis of effective field theories resulting from non-supersymmetric perturbations to supersymmetric flux compactifications of the type-IIB superstring with an eye towards those resulting from the backreaction of a small number of anti-D3-branes. Independently of the background, we show that the low-energy Lagrangian describing the fluctuations of a stack of probe D3-branes exhibits soft supersymmetry breaking, despite perturbations to marginal operators that were not fully c...
Electroweak Symmetry Breaking Beyond the Standard Model
Bhattacharyya, Gautam
2012-01-01
In this talk, I shall address two key issues related to electroweak symmetry breaking. First, how fine-tuned different models are that trigger this phenomenon? Second, even if a light Higgs boson exists, does it have to be necessarily elementary? After a brief introduction, I shall first review the fine-tuning aspects of the MSSM, NMSSM, generalized NMSSM and GMSB scenarios. I shall then compare and contrast the little Higgs, composite Higgs and the Higgsless models. Finally, I shall summariz...
Induced Higgs couplings and spontaneous symmetry breaking
International Nuclear Information System (INIS)
It is shown that spontaneous symmetry breaking can arise in a non-Abelian gauge theory free of quartic scalar couplings only if fermions are present in the theory. A sufficiency condition is developed for positivity of the induced PHI4-potential as PHI→infinity. The same condition guarantees the existence of asymptotically free positive-eigenvalue solutions to the renormalization group equations for running coupling constants. Correspondence is established between ''eigenvalue'' and induced-potential approaches toward total asymptotic freedom. (author)
Center vortices, confinement and chiral symmetry breaking
International Nuclear Information System (INIS)
The center vortex model, proposed as an explanation of confinement in non-abelian gauge theories is introduced. Some checks of the confinement properties of center vortices in SU(2) lattice gauge theory with improved Luescher-Weisz gauge action are presented. Phenomena related to chiral symmetry, such as topological charge and spontaneous chiral symmetry breaking (SCSB) are studied within the vortex model. In particular the influence of center vortices on the low-lying spectrum of the Dirac operator is analyzed. (author)
How does DNA break during chromosomal translocations?
Nambiar, Mridula; Raghavan, Sathees C.
2011-01-01
Chromosomal translocations are one of the most common types of genetic rearrangements and are molecular signatures for many types of cancers. They are considered as primary causes for cancers, especially lymphoma and leukemia. Although many translocations have been reported in the last four decades, the mechanism by which chromosomes break during a translocation remains largely unknown. In this review, we summarize recent advances made in understanding the molecular mechanism of chromosomal t...
Flavour Violation in Anomaly Mediated Supersymmetry Breaking
Allanach, B. C.; Hiller, G; Jones, D. R. T.; Slavich, P.(LPTHE, UPMC Univ. Paris 06, Sorbonne Universités, 4 Place Jussieu, 75252, Paris, France)
2009-01-01
32 pages, 8 figures International audience We study squark flavour violation in the anomaly mediated supersymmetry broken (AMSB) minimal supersymmetric standard model. Analytical expressions for the three-generational squark mass matrices are derived. We show that the anomaly-induced soft breaking terms have a decreasing amount of squark flavour violation when running from the GUT to the weak scale. Taking into account inter-generational squark mixing, we work out non-trivial constraint...
Breaking of Nanotube Symmetry by Substrate Polarization
Petrov, Alexey G.; Rotkin, Slava V.
2003-01-01
Substrate and nanotube polarization are shown to change qualitatively a nanotube bandstructure. The effect is studied in a linear approximation in an external potential which causes the changes. A work function difference between the nanotube and gold surface is estimated to be large enough to break the band symmetry and lift a degeneracy of a lowest but one subband of a metallic nanotube. This subband splitting for [10,10] nanotube is about 50 meV in absence of other external potential.
Breaking democracy with non renormalizable mass terms
Silva-Marcos, Joaquim I
2001-01-01
The exact democratic structure for the quark mass matrix, resulting from the action of the family symmetry group $A_{3L}\\times A_{3R}$, is broken by the vacuum expectation values of heavy singlet fields appearing in non renormalizable dimension 6 operators. Within this specific context of breaking of the family symmetry we formulate a very simple ansatz which leads to correct quark masses and mixings.
Monitoring ice break-up on the Mackenzie River using MODIS data
Directory of Open Access Journals (Sweden)
P. Muhammad
2015-05-01
Full Text Available This study involves the analysis of Moderate Resolution Imaging Spectroradiometer (MODIS Level 3 500 m snow products (MOD/MYD10A1, complemented with 250 m Level 1B data (MOD/MYD02QKM, to monitor ice cover during the break-up period on the Mackenzie River, Canada. Results from the analysis of data for 13 ice seasons (2001–2013 show that first day ice-off dates are observed between days of year (DOY 115–125 and end DOY 145–155, resulting in average melt durations of about 30–40 days. Floating ice transported northbound could therefore generate multiple periods of ice-on and ice-off observations at the same geographic location. During the ice break-up period, ice melt was initiated by in situ (thermodynamic melt over the drainage basin especially between 61–61.8° N (75–300 km. However, ice break-up process north of 61.8° N was more dynamically driven. Furthermore, years with earlier initiation of the ice break-up period correlated with above normal air temperatures and precipitation, whereas later ice break-up period was correlated with below normal precipitation and air temperatures. MODIS observations revealed that ice runs were largely influenced by channel morphology (islands and bars, confluences and channel constriction. It is concluded that the numerous MODIS daily overpasses possible with the Terra and Aqua polar orbiting satellites, provide a powerful means for monitoring ice break-up processes at multiple geographical locations simultaneously along the Mackenzie River.
Piecewise-smooth circle homeomorphisms with several break points
International Nuclear Information System (INIS)
We prove that the invariant probability measure of an ergodic piecewise-smooth circle homeomorphism with several break points and the product of the jumps at break points non-trivial is singular with respect to Lebesgue measure.
Away from resolution, assessing the information content of super-resolution images
Pengo, Thomas; Olivier, Nicolas; Manley, Suliana
2015-01-01
Super-resolution microscopy has revolutionized optical fluorescence imaging by improving 3D resolution by 1-2 orders of magnitude. While different methods can successfully increase the resolution, all methods share significant differences with standard imaging methods, making the usual measures of resolution inapplicable. In particular image quality and information content are spatially heterogeneous with variabilities that can be comparable to their mean values, limiting the use of the avera...
Enhanced breaking of heavy quark spin symmetry
International Nuclear Information System (INIS)
Heavy quark spin symmetry is useful to make predictions on ratios of decay or production rates of systems involving heavy quarks. The breaking of spin symmetry is generally of the order of O(ΛQCD/mQ), with ΛQCD the scale of QCD and mQ the heavy quark mass. In this paper, we will show that a small S- and D-wave mixing in the wave function of the heavy quarkonium could induce a large breaking in the ratios of partial decay widths. As an example, we consider the decays of the ϒ(10860) into the χbJω(J=0,1,2), which were recently measured by the Belle Collaboration. These decays exhibit a huge breaking of the spin symmetry relation were the ϒ(10860) a pure 5S bottomonium state. We propose that this could be a consequence of a mixing of the S-wave and D-wave components in the ϒ(10860). Prediction on the ratio Γ(ϒ(10860)→χb0ω)/Γ(ϒ(10860)→χb2ω) is presented assuming that the decay of the D-wave component is dominated by the coupled-channel effects
Dormancy Breaking in Ormosia arborea Seeds
Directory of Open Access Journals (Sweden)
Edilma Pereira Gonçalves
2011-01-01
Full Text Available Ormosia arborea is a tree species planted in urban areas and used to restore degraded areas. Its seeds are dormant and propagation is difficult. This study compares different dormancy breaking methods and physiological seed quality and seedling production. The seeds were germinated in sand in the laboratory of the Universidade Estadual de Santa Cruz, Ilhéus, Bahia, Brazil. The following dormancy breaking treatments were applied: control (intact seeds, 100°C water immersion; boiling water immersion followed by 24 hours of soaking; scarification with number 100 and number 50 sandpaper opposite from root emergence; sulfuric acid immersion for 1 hour, 50, 45, and 30 minutes. Seed immersion in 100°C and boiling water did not break the dormancy. The study species showed a greater vigor of seedling when its seeds were submitted to treatments associated with tegument rupturing by sandpaper or sulfuric acid. On the other hand, seed scarification with sulfuric acid for 1 hour, 50, 45, and 30 minutes or sandpaper favored seed germination and vigor.
Heavy Metal Exposure Influences Double Strand Break DNA Repair Outcomes
Morales, Maria E.; Derbes, Rebecca S.; Ade, Catherine M.; Ortego, Jonathan C.; Stark, Jeremy; Deininger, Prescott L.; Roy-Engel, Astrid M.
2016-01-01
Heavy metals such as cadmium, arsenic and nickel are classified as carcinogens. Although the precise mechanism of carcinogenesis is undefined, heavy metal exposure can contribute to genetic damage by inducing double strand breaks (DSBs) as well as inhibiting critical proteins from different DNA repair pathways. Here we take advantage of two previously published culture assay systems developed to address mechanistic aspects of DNA repair to evaluate the effects of heavy metal exposures on competing DNA repair outcomes. Our results demonstrate that exposure to heavy metals significantly alters how cells repair double strand breaks. The effects observed are both specific to the particular metal and dose dependent. Low doses of NiCl2 favored resolution of DSBs through homologous recombination (HR) and single strand annealing (SSA), which were inhibited by higher NiCl2 doses. In contrast, cells exposed to arsenic trioxide preferentially repaired using the “error prone” non-homologous end joining (alt-NHEJ) while inhibiting repair by HR. In addition, we determined that low doses of nickel and cadmium contributed to an increase in mutagenic recombination-mediated by Alu elements, the most numerous family of repetitive elements in humans. Sequence verification confirmed that the majority of the genetic deletions were the result of Alu-mediated non-allelic recombination events that predominantly arose from repair by SSA. All heavy metals showed a shift in the outcomes of alt-NHEJ repair with a significant increase of non-templated sequence insertions at the DSB repair site. Our data suggest that exposure to heavy metals will alter the choice of DNA repair pathway changing the genetic outcome of DSBs repair. PMID:26966913
Healthy breaks: tasty tips for the under fives
Public Health Agency
2014-01-01
Today the Public Health Agency is launching a new resource pack designed to assist nursery schools and playgroups deliver a healthy breaks scheme.All nursery schools and playgroups in Northern Ireland will receive the pack - 'Healthy breaks for pre-school children' - which includes a poster and information leaflets for parents explaining why a healthy break is so important for pre-school children and some tips and ideas for healthy nutritious breaks.Judith Hanvey, Regional Food in Schools Co-...
A study of symmetry breaking in a relativistic Bose gas using the contraction algorithm
Alexandru, Andrei; Bedaque, Paulo; Ridgway, Gregory W; Warrington, Neill C
2016-01-01
A relativistic Bose gas at finite density suffers from a sign problem that makes direct numerical simulations not feasible. One possible solution to the sign problem is to re-express the path integral in terms of Lefschetz thimbles. Using this approach we study the relativistic Bose gas both in the symmetric phase (low-density) and the spontaneously broken phase (high-density). In the high-density phase we break explicitly the symmetry and determine the dependence of the order parameter on the breaking. We study the relative contributions of the dominant and sub-dominant thimbles in this phase. We find that the sub-dominant thimble only contributes substantially when the explicit symmetry breaking is small, a regime that is dominated by finite volume effects. In the regime relevant for the thermodynamic limit, this contribution is negligible.
FINITE-VOLUME TVD ALGORITHM FOR DAM-BREAK FLOWS IN OPEN CHANNELS
Institute of Scientific and Technical Information of China (English)
Wang Jia-song; He You-sheng
2003-01-01
A finite-volume Total Variation Diminishing (TVD) scheme is presented for modeling dam-break flows in open channels.This method is used for solving the 2D shallow water equations on arbitrary quadrilateral meshes, based upon a second-order hybrid TVD scheme with an optimum-selected limiter in the space discretization and a two-step Runge-Kutta approach in the time discretization.Verification for a circular dam-break problem is carried out by comparing the present results with others and very good agreement is shown.The present algorithm is then used to predict dam-break flow characteristics in open channels such as in furcated channels.More complicated unsteady flow characteristics in these furcated channels than in the regular channels studied previously can observed in this work.
International Nuclear Information System (INIS)
In the nuclear engineering fields, a free surface plays an important role, for example, the cover-gas entrainment phenomenon in the FBR core design. There are various numerical techniques of computational fluid dynamics for multiphase flows based on the one-field model, such as a front tracking method, an interface capturing method and so on. A dam breaking problem is often chosen to validate these numerical techniques. As for the validation test, a few experiments of the dam-breaking problem were performed. However, those experimentations were performed for the limited conditions regarding the test section size and the boundary conditions. The dam-breaking experiments in order to establish an experimental database for validating the interface tracking method have been carried out by using a high-speed video camera. Then, some numerical simulations based on the MARS (Multi-interfaces Advection and Reconstruction Solver)(Kunugi, 2001) were performed and its results were compared to this experimental database. (author)
Energy Technology Data Exchange (ETDEWEB)
Fuks, Benjamin [Strasbourg Univ. (France). Inst. Pluridisciplinaire Hubert Curien; Herrmann, Bjoern [Savoie Univ., Annecy-le-Vieux (France). LAPTh; Klasen, Michael [Muenster Univ. (Germany). Inst. fuer Theoretische Physik 1
2011-12-15
In minimal anomaly-mediated supersymmetry breaking models, tachyonic sleptons are avoided by introducing a common scalar mass similar to the one introduced in minimal supergravity. This may lead to non-minimal flavour-violating interactions, e.g., in the squark sector. In this paper, we analyze the viable anomaly-mediated supersymmetry breaking parameter space in the light of the latest limits on low-energy observables and LHC searches, complete our analytical calculations of flavour-violating supersymmetric particle production at hadron colliders with those related to gluino production, and study the phenomenological consequences of non-minimal flavour violation in anomaly-mediated supersymmetry breaking scenarios at the LHC. Related cosmological aspects are also briefly discussed.
PT-symmetry breaking with divergent potentials: lattice and continuum cases
Joglekar, Yogesh N; Saxena, Avadh
2014-01-01
We investigate the parity- and time-reversal ($\\mathcal{PT}$)-symmetry breaking in lattice models in the presence of long-ranged, non-hermitian, $\\mathcal{PT}$-symmetric potentials that remain finite or become divergent in the continuum limit. By scaling analysis of the fragile $\\mathcal{PT}$ threshold for an open finite lattice, we show that continuum loss-gain potentials $V_\\alpha(x)\\propto i |x|^\\alpha \\mathrm{sign}(x)$ have a positive $\\mathcal{PT}$-breaking threshold for $\\alpha>-2$, and a zero threshold for $\\alpha\\leq -2$. When $\\alpha<0$ localized states with complex (conjugate) energies in the continuum energy-band occur at higher loss-gain strengths. We investigate the signatures of $\\mathcal{PT}$-symmetry breaking in coupled waveguides, and show that the emergence of localized states dramatically shortens the relevant time-scale in the $\\mathcal{PT}$-symmetry broken region.
Universality and Symmetry Breaking in Conformally Reduced Quantum Gravity
Bonanno, Alfio
2012-01-01
The scaling properties of quantum gravity are discussed by employing a class of proper-time regulators in the functional flow equation for the conformal factor within the formalism of the background field method. Renormalization group trajectories obtained by projecting the flow on a flat topology are more stable than those obtained from a projection on a spherical topology. In the latter case the ultraviolet flow can be characterized by a Hopf bifurcation with an ultraviolet attractive limiting cycle. Although the possibility of determining the infrared flow for an extended theory space can be severely hampered due to the conformal factor instability, we present a robust numerical approach to study the flow structure around the non-gaussian fixed point as an inverse-problem strategy. In particular it is shown the possibility of having a spontaneous breaking of the diffeomorphism invariance can be realized with non-local functionals of the volume operator.
Structural topography-mediated high temperature wetting symmetry breaking
Li, Jing; Liu, Yahua; Hao, Chonglei; Li, Minfei; Chaudhury, Manoj K; Yao, Shuhuai
2015-01-01
Directed motion of liquid droplets is of considerable importance in various industrial processes. Despite extensive advances in this field of research, our understanding and the ability to control droplet dynamics at high temperature remain limited, in part due to the emergence of complex wetting states intertwined by the phase change process at the triple-phase interfaces. Here we show that two concurrent wetting states (Leidenfrost and contact boiling) can be manifested in a single droplet above its boiling point rectified by the presence of asymmetric textures. The breaking of the wetting symmetry at high temperature subsequently leads to the preferential motion towards the region with higher heat transfer coefficient. We demonstrate experimentally and analytically that the droplet vectoring is intricately dependent on the interplay between the structural topography and its imposed thermal state. Our fundamental understanding and the ability to control the droplet dynamics at high temperature represent an ...
Micropropulsion and microrheology in complex fluids via symmetry breaking
Pak, On Shun; Brandt, Luca; Lauga, Eric; 10.1063/1.4758811
2013-01-01
Many biological fluids have polymeric microstructures and display non-Newtonian rheology. We take advantage of such nonlinear fluid behavior and combine it with geometrical symmetry-breaking to design a novel small-scale propeller able to move only in complex fluids. Its propulsion characteristics are explored numerically in an Oldroyd-B fluid for finite Deborah numbers while the small Deborah number limit is investigated analytically using a second-order fluid model. We then derive expressions relating the propulsion speed to the rheological properties of the complex fluid, allowing thus to infer the normal stress coefficients in the fluid from the locomotion of the propeller. Our simple mechanism can therefore be used either as a non-Newtonian micro-propeller or as a micro-rheometer.
Domain Walls and Vortices in Chiral Symmetry Breaking
Eto, Minoru; Nitta, Muneto
2013-01-01
We study domain walls and vortices in chiral symmetry breaking in QCD with N flavors in the chiral limit. If the axial anomaly was absent, there exist stable Abelian axial vortices winding around the spontaneously broken U(1)_A symmetry and non-Abelian axial vortices winding around both the U(1)_A and non-Abelian SU(N) chiral symmetries. In the presence of the axial anomaly term, metastable domain walls are present and Abelian axial vortices must be attached by N domain walls, forming domain wall junctions. We show that a domain wall junction decays into N non-Abelian vortices attached by domain walls, implying its metastability. We also show that domain walls decay through the quantum tunneling by creating a hole bounded by a closed non-Abelian vortex.
9 CFR 590.522 - Breaking room operations.
2010-01-01
... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Breaking room operations. 590.522..., Processing, and Facility Requirements § 590.522 Breaking room operations. (a) The breaking room shall be kept... room personnel shall wash their hands thoroughly with odorless soap and water each time they enter...
A strict QCD inequality and mechanisms for chiral symmetry breaking
International Nuclear Information System (INIS)
A strict QCD inequality allows one to discuss mechanisms proposed for breaking the chiral symmetry in QCD. ''Order parameters'' are identified such that if sufficiently many gauge field configurations contribute to them, spontaneous chiral symmetry breaking follows. As an application the role of instantons is discussed in chiral symmetry breaking in QCD. (orig.)
24 CFR 982.315 - Family break-up.
2010-04-01
... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Family break-up. 982.315 Section... SECTION 8 TENANT BASED ASSISTANCE: HOUSING CHOICE VOUCHER PROGRAM Leasing a Unit § 982.315 Family break-up... assistance in the program if the family breaks up. The PHA administrative plan must state PHA policies on...
Breaking of Waves over a Steep Bottom Slope
DEFF Research Database (Denmark)
Jensen, Morten S.
The thesis deals with the wave breaking process of waves propagating over a steep submerged bottom slope. The amount of energy dissipated in the wave breaking process is focused upon. An extensive number of experimental tests (>400) using regular and irregular waves breaking over a simulated reef...
Phenomenological approach to symmetry breaking pattern of democratic mass matrix
Harada, J
2002-01-01
We investigate the symmetry breaking pattern of the democratic mass matrix model, which leads to the small flavor mixing in quark sector and bi-large mixing in lepton sector. We present the symmetry breaking matrices in quark sector which are determined by alternative ways instead of conventional ansatz. These matrices might be useful for understanding the origin of democratic symmetry and its breaking.
Olteanu, Anda; Welker, Volkmar
2014-01-01
We define the Buchberger resolution, which is a graded free resolution of a monomial ideal in a polynomial ring. Its construction uses a generalization of the Buchberger graph and encodes much of the combinatorics of the Buchberger algorithm. The Buchberger resolution is a cellular resolution that coincides with the Scarf resolution for generic monomial ideals, which is the case when it is minimal. The simplicial complex underlying the Buchberger resolution is of interest for its own sake and...
Core liquid level depression due to manometric effect during PWR small break LOCA
International Nuclear Information System (INIS)
The 10, 5 and 2.5 % cold leg break loss-of-coolant accident experiments were conducted by using the Large Scale Test Facility (LSTF) of the Rig of Safety Assessment (ROSA)-IV program. In the early stage of the 5 % break experiment, the core collapsed liquid level was depressed nearly to the core bottom and the dryout of the core was observed. However, the core liquid level depression without the core dryout was observed in the 10 and 2.5 % break experiments. In the three break experiments, the core liquid levels were recovered just after the loop seal clearing. The manometric effect due to the liquid seal formation in the loop seal and the liquid holdup in the steam generator (SG) U-tubes upflow-side caused a depression of the core collapsed liquid level. The liquid holdup in the U-tubes upflow-side was observed after the termination of the two-phase circulation due to the phase separation at the U-tubes top. The counter current flow limiting (CCFL) and the condensation of steam was considered to be the main reason for the liquid holdup. In the 10, 5 and 2.5 % break experiments, the termination of the two-phase circulation and the loop seal clearing were observed approximately at 40 ∼ 60 % and 30 % mass inventory in the primary system, respectively. (author)
The evolution of the break preclusion concept for nuclear power plants in Germany
Energy Technology Data Exchange (ETDEWEB)
Schulz, H. [Gesellschaft fuer Anlagen- und Reaktorsicherheit, Koeln (Germany)
1997-04-01
In the updating of the Guidelines for PWR`s of the {open_quotes}Reaktor-Sicherheitskommission{close_quotes} (RSK) in 1981 the requirements on the design have been changed with respect to the postulated leaks and breaks in the primary pressure boundary. The major change was a revision in the requirements for pipe whip protection. As a logical consequence of the {open_quotes}concept of basic safety{close_quotes} a guillotine type break or any other break type resulting in a large opening is not postulated any longer for the calculation of reaction and jet forces. As an upper limit for a leak an area of 0, 1 A (A = open cross section of the pipe) is postulated. This decision was based on a general assessment of the present PWR system design in Germany. Since then a number of piping systems have been requalified in the older nuclear power plants to comply with the break preclusion concept. Also a number of extensions of the concept have been developed to cover also leak-assumptions for branch pipes. Furthermore due considerations have been given to other aspects which could contribute to a leak development in the primary circuit, like vessel penetrations, manhole covers, flanges, etc. Now the break preclusion concept originally applied to the main piping has been developed into an integrated concept for the whole pressure boundary within the containment and will be applied also in the periodic safety review of present nuclear power plants.
NSGIC GIS Inventory (aka Ramona) — This Break Lines dataset, was produced all or in part from Orthoimagery information as of unknown. It is described as 'Break lines were captured from Orthoimagery...
Flavour symmetry breaking in the kaon parton distribution amplitude
Directory of Open Access Journals (Sweden)
Chao Shi
2014-11-01
Full Text Available We compute the kaon's valence-quark (twist-two parton distribution amplitude (PDA by projecting its Poincaré-covariant Bethe–Salpeter wave-function onto the light-front. At a scale ζ=2 GeV, the PDA is a broad, concave and asymmetric function, whose peak is shifted 12–16% away from its position in QCD's conformal limit. These features are a clear expression of SU(3-flavour-symmetry breaking. They show that the heavier quark in the kaon carries more of the bound-state's momentum than the lighter quark and also that emergent phenomena in QCD modulate the magnitude of flavour-symmetry breaking: it is markedly smaller than one might expect based on the difference between light-quark current masses. Our results add to a body of evidence which indicates that at any energy scale accessible with existing or foreseeable facilities, a reliable guide to the interpretation of experiment requires the use of such nonperturbatively broadened PDAs in leading-order, leading-twist formulae for hard exclusive processes instead of the asymptotic PDA associated with QCD's conformal limit. We illustrate this via the ratio of kaon and pion electromagnetic form factors: using our nonperturbative PDAs in the appropriate formulae, FK/Fπ=1.23 at spacelike-Q2=17 GeV2, which compares satisfactorily with the value of 0.92(5 inferred in e+e− annihilation at s=17 GeV2.
Flavour symmetry breaking in the kaon parton distribution amplitude
Energy Technology Data Exchange (ETDEWEB)
Shi, Chao [Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics, Nanjing University, Nanjing 210093 (China); Department of Physics, Nanjing University, Nanjing 210093 (China); Chang, Lei [CSSM, School of Chemistry and Physics University of Adelaide, Adelaide, SA 5005 (Australia); Roberts, Craig D. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Schmidt, Sebastian M. [Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, D-52425 Jülich (Germany); Tandy, Peter C. [Center for Nuclear Research, Department of Physics, Kent State University, Kent, OH 44242 (United States); Zong, Hong-shi [Department of Physics, Nanjing University, Nanjing 210093 (China); State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, CAS, Beijing 100190 (China); Joint Center for Particle, Nuclear Physics and Cosmology, Nanjing 210093 (China)
2014-11-10
We compute the kaon's valence-quark (twist-two parton) distribution amplitude (PDA) by projecting its Poincaré-covariant Bethe–Salpeter wave-function onto the light-front. At a scale ζ=2 GeV, the PDA is a broad, concave and asymmetric function, whose peak is shifted 12–16% away from its position in QCD's conformal limit. These features are a clear expression of SU(3)-flavour-symmetry breaking. They show that the heavier quark in the kaon carries more of the bound-state's momentum than the lighter quark and also that emergent phenomena in QCD modulate the magnitude of flavour-symmetry breaking: it is markedly smaller than one might expect based on the difference between light-quark current masses. Our results add to a body of evidence which indicates that at any energy scale accessible with existing or foreseeable facilities, a reliable guide to the interpretation of experiment requires the use of such nonperturbatively broadened PDAs in leading-order, leading-twist formulae for hard exclusive processes instead of the asymptotic PDA associated with QCD's conformal limit. We illustrate this via the ratio of kaon and pion electromagnetic form factors: using our nonperturbative PDAs in the appropriate formulae, F{sub K}/F{sub π}=1.23 at spacelike-Q{sup 2}=17 GeV{sup 2}, which compares satisfactorily with the value of 0.92(5) inferred in e{sup +}e{sup −} annihilation at s=17 GeV{sup 2}.
Resolution in Electromagnetic Prospecting
Aldridge, D. F.; Bartel, L. C.; Knox, H. A.; Schramm, K. A.
2014-12-01
Low-frequency electromagnetic (EM) signals are commonly used in geophysical exploration of the shallow subsurface. Sensitivity to conductivity implies they are particularly useful for inferring fluid content of porous media. However, low-frequency EM wavefields are diffusive, and have significantly larger wavelengths compared to seismic signals of equal frequency. The wavelength of a 30 Hz sinusoid propagating with seismic velocity 3000 m/s is 100 m, whereas an analogous EM signal diffusing through a conductive body of 0.1 S/m (clayey shale) has wavelength 1825 m. The larger wavelength has implications for resolution of the EM prospecting method. We are investigating resolving power of the EM method via theoretical and numerical experiments. Normal incidence plane wave reflection/transmission by a thin geologic bed is amenable to analytic solution. Responses are calculated for beds that are conductive or resistive relative to the host rock. Preliminary results indicate the classic seismic resolution/detection limit of bed thickness ~1/8 wavelength is not achieved. EM responses for point or line current sources recorded by general acquisition geometries are calculated with a 3D finite-difference algorithm. These exhibit greater variability which may allow inference of bed thickness. We also examine composite responses of two point scatterers with separation when illuminated by an incident EM field. This is analogous to the Rayleigh resolution problem of estimating angular separation between two light sources. The First Born Approximation implies that perturbations in permittivity, permeability, and conductivity have different scattering patterns, which may be indicators of EM medium properties. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.
Weingeist, David M; Ge, Jing; Wood, David K; Mutamba, James T; Huang, Qiuying; Rowland, Elizabeth A; Yaffe, Michael B; Floyd, Scott; Engelward, Bevin P
2013-03-15
A key modality of non-surgical cancer management is DNA damaging therapy that causes DNA double-strand breaks that are preferentially toxic to rapidly dividing cancer cells. Double-strand break repair capacity is recognized as an important mechanism in drug resistance and is therefore a potential target for adjuvant chemotherapy. Additionally, spontaneous and environmentally induced DSBs are known to promote cancer, making DSB evaluation important as a tool in epidemiology, clinical evaluation and in the development of novel pharmaceuticals. Currently available assays to detect double-strand breaks are limited in throughput and specificity and offer minimal information concerning the kinetics of repair. Here, we present the CometChip, a 96-well platform that enables assessment of double-strand break levels and repair capacity of multiple cell types and conditions in parallel and integrates with standard high-throughput screening and analysis technologies. We demonstrate the ability to detect multiple genetic deficiencies in double-strand break repair and evaluate a set of clinically relevant chemical inhibitors of one of the major double-strand break repair pathways, non-homologous end-joining. While other high-throughput repair assays measure residual damage or indirect markers of damage, the CometChip detects physical double-strand breaks, providing direct measurement of damage induction and repair capacity, which may be useful in developing and implementing treatment strategies with reduced side effects. PMID:23422001
Sparticle spectrum and constraints in anomaly mediated supersymmetry breaking models
Huitu, K; Pandita, P N
2002-01-01
We study in detail the particle spectrum in anomaly mediated supersymmetry breaking models in which supersymmetry breaking terms are induced by super-Weyl anomaly. We investigate the minimal anomaly mediated supersymmetry breaking models, gaugino assisted supersymmetry breaking models, as well as models with additional residual non-decoupling D-term contributions due to an extra U(1) gauge symmetry at high energy scale. We derive sum rules for the sparticle masses in these models which can help in differentiating between them. We also obtain the sparticle spectrum numerically, and compare and contrast the results so obtained for the different types of anomaly mediated supersymmetry breaking models.
Raman amplification in the coherent wave-breaking regime.
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. PMID:26764840
Fuel breaks affect nonnative species abundance in Californian plant communities
Merriam, K.E.; Keeley, J.E.; Beyers, J.L.
2006-01-01
We evaluated the abundance of nonnative plants on fuel breaks and in adjacent untreated areas to determine if fuel treatments promote the invasion of nonnative plant species. Understanding the relationship between fuel treatments and nonnative plants is becoming increasingly important as federal and state agencies are currently implementing large fuel treatment programs throughout the United States to reduce the threat of wildland fire. Our study included 24 fuel breaks located across the State of California. We found that nonnative plant abundance was over 200% higher on fuel breaks than in adjacent wildland areas. Relative nonnative cover was greater on fuel breaks constructed by bulldozers (28%) than on fuel breaks constructed by other methods (7%). Canopy cover, litter cover, and duff depth also were significantly lower on fuel breaks constructed by bulldozers, and these fuel breaks had significantly more exposed bare ground than other types of fuel breaks. There was a significant decline in relative nonnative cover with increasing distance from the fuel break, particularly in areas that had experienced more numerous fires during the past 50 years, and in areas that had been grazed. These data suggest that fuel breaks could provide establishment sites for nonnative plants, and that nonnatives may invade surrounding areas, especially after disturbances such as fire or grazing. Fuel break construction and maintenance methods that leave some overstory canopy and minimize exposure of bare ground may be less likely to promote nonnative plants. ?? 2006 by the Ecological Society of America.
Break spectrum analyses for small break loss of coolant accidents in a RESAR-3S Plant
International Nuclear Information System (INIS)
A series of thermal-hydraulic analyses were performed to investigate phenomena occurring during small break loss-of-coolant-accident (LOCA) sequences in a RESAR-3S pressurized water reactor. The analysis included simulations of plant behavior using the TRAC-PF1 and RELAP5/MOD2 computer codes. Series of calculations were performed using both codes for different break sizes. The analyses presented here also served an audit function in that the results shown here were used by the US Nuclear Regulatory Commission (NRC) as an independent confirmation of similar analyses performed by Westinghouse Electric Company using another computer code. 10 refs., 62 figs., 14 tabs
Cascading Multicriticality in Nonrelativistic Spontaneous Symmetry Breaking
Griffin, Tom; Horava, Petr; Yan, Ziqi
2015-01-01
Without Lorentz invariance, spontaneous global symmetry breaking can lead to multicritical Nambu-Goldstone modes with a higher-order low-energy dispersion $\\omega\\sim k^n$ ($n=2,3,\\ldots$), whose naturalness is protected by polynomial shift symmetries. Here we investigate the role of infrared divergences and the nonrelativistic generalization of the Coleman-Hohenberg-Mermin-Wagner (CHMW) theorem. We find novel cascading phenomena with large hierarchies between the scales at which the value of $n$ changes, leading to an evasion of the "no-go" consequences of the relativistic CHMW theorem.
Breaking the fault tree circular logic
International Nuclear Information System (INIS)
Event tree - fault tree approach to model failures of nuclear plants as well as of other complex facilities is noticeably dominant now. This approach implies modeling an object in form of unidirectional logical graph - tree, i.e. graph without circular logic. However, genuine nuclear plants intrinsically demonstrate quite a few logical loops (circular logic), especially where electrical systems are involved. This paper shows the incorrectness of existing practice of circular logic breaking by elimination of part of logical dependencies and puts forward a formal algorithm, which enables the analyst to correctly model the failure of complex object, which involves logical dependencies between system and components, in form of fault tree. (author)
Spontaneous symmetry breaking in a classical particle
Sánchez, L A; Sanchez, Luis Alberto; Mahecha, Jorge
2003-01-01
Due to the fact that only matter fields have phase, frequently is believed that the gauge principle can induce gauge fields only in quantum systems. But this is not necessary. This paper, of pedagogical scope, presents a classical system constituted by a particle in a classical potential, which is used as a model to illustrate the gauge principle and the spontaneous symmetry breaking. Those concepts appear in the study of second order phase transitions. Ferroelectricity, ferromagnetism, superconductivity, plasmons in a free electron gas, and the mass of vector bosons in the gauge field Yang-Mills theories, are some of the phenomena in which these transitions occur.
String breaking in four dimensional lattice QCD
International Nuclear Information System (INIS)
Virtual quark pair screening leads to breaking of the string between fundamental representation quarks in QCD. For unquenched four dimensional lattice QCD, this (so far elusive) phenomenon is studied using the recently developed truncated determinant algorithm (TDA). The dynamical configurations were generated on a 650 MHz PC. Quark eigenmodes up to 420 MeV are included exactly in these TDA studies performed at low quark mass on large coarse [but O(a2) improved] lattices. A study of Wilson line correlators in Coulomb gauge extracted from an ensemble of 1000 two-flavor dynamical configurations reveals evidence for flattening of the string tension at distances R∼>1 fm